6(2,4-Dichlorophenoxy)dibenzo[d,f][1,3,2]dioxa-phosphepine-6-sulfide - Krishnaiah, M.; Babu, V. H. H. Surendra; Krishna, J. R.; Kumar, K. A.; Reddy, C. S.; Puranik, Vedavati G. (Acta Crystallographica Section E-Structure Reports Online, 2005)
In the title compound, C18H11Cl2O3PS, the seven-membered phosphepine ring exhibits a distorted-boat conformation, with the phosphoryl sulfide group axial and the dichlorophenoxy group equatorial. Fusion of the phosphepine ring to the biphenyl system causes strain, as evidenced by both widening and compression of the endocyclic angles in the heterocyclic ring. The P=S bond length is 1.8939 (12) angstrom and the planar dichlorophenyl ring is oriented at an angle of 28.70 (6)degrees to the phosphepine ring.

[6+3] cycloaddition of fulvenes with 3-oxidopyrylium betaine: a novel methodology for the synthesis of fused cyclooctanoid natural products - Radhakrishnan, K. V.; Krishnan, K. Syam; Bhadbhade, Mohan M.; Bhosekar, Gaurav V. (Tetrahedron Letters, 2005)
Fulvenes undergo an easy [6+3] cycloaddition with 3-oxidopyrylium betaines leading to 5-8 fused oxabridged cyclooetanoids. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: cyclooctanoids; fulvenes; oxidopyrylium betaines; [6+3] cycloaddition

Analysis of a gas-liquid-liquid-solid catalytic reaction: kinetics and modeling of a semibatch slurry reactor - Roy, D.; Chaudhari, Raghunath V. (Industrial & Engineering Chemistry Research, 2005)
Hydrogenation of aniline to cyclohexylamine was studied in a gas-liquid-liquid-solid tetraphase system using cyclohexane and water as two immiscible liquid phases and ruthenium on alumina (2% Ru/Al2O3) as the catalyst. In addition to the higher catalytic activity with respect to the conventional three-phase system, the novel four-phase system was highly efficient in catalyst-product separation. Experimental data on concentration-time as well as hydrogen-consumption-time profiles were obtained to study the effect of concentration of aniline, catalyst loading, and the partial pressure of hydrogen. A detailed analysis of gas-liquid, liquid-liquid, liquid-solid, and intraparticle mass transfer was carried out using initial rate data to ensure the kinetic regime. On the basis of these data, several rate equations were evaluated to select a kinetic model. The kinetic parameters were estimated over a temperature range of 378-418 K by fitting the integral batch reactor data. A rate model considering adsorption of hydrogen on the catalyst surface followed by reaction with the liquid-phase components as the rate-limiting step was found to give the best fitting of the experimental concentration-time as well as the hydrogen-consumption-time data at different initial sets of reaction conditions. The activation energies, heat of adsorption, and entropy of adsorption were also evaluated.
Joint 5th International Symposium on Catalysis in Multiphase Reactors/4th International Symposium on Multifunctional Reactors, Portoroz-Portorose, SLOVENIA, JUN 15-18, 2005

Arrhythmia classification using local Holder exponents and support vector machine - Joshi, Aniruddha; Rajshekhar; Chandran, S.; Phadke, S.; Jayaraman, Valadi K.; Kulkarni, B. D. (1st International Conference on Pattern Recognition and Machine Intelligence, 2005)
We propose a novel hybrid Holder-SVM detection algorithm for arrhythmia classification. The Holder exponents are computed efficiently using the wavelet transform modulus maxima (WTMM) method. The hybrid system performance is evaluated using the benchmark MIT-BIH arrhythmia database. The implemented model classifies 160 of Normal sinus rhythm, 25 of Ventricular bigeminy, 155 of Atrial fibrillation and 146 of Nodal (A-V junctional) rhythm with 96.94% accuracy. The distinct scaling properties of different types of heart rhythms may be of clinical importance.
1st International Conference on Pattern Recognition and Machine Intelligence, Statist Inst Kolkata, Kolkata, INDIA, DEC 20-22, 2005

Bioleaching of sand by the fungus fusarium oxysporum as a means of producing extracellular silica nanoparticles - Bansal, Vipul; Sanyal, A.; Rautaray, D.; Ahmad, Absar; Sastry, Murali (Advanced Materials, 2005)
A plant pathogenic fungus, Fusarium oxysporum, can be used as a biological model system for the extracellular bioleaching of hollow spherical silica nanoparticles (see Figure) from sand. The room-temperature synthesis of oxide nanomaterials using microorganisms starting from potential waste materials could lead to eco-friendly and economically viable methods for the large-scale synthesis of nanomaterials.

Biological synthesis of stable vaterite crystals by the reaction of calcium ions with germinating chickpea seeds - Rautaray, D.; Sanyal, A.; Bharde, Atul A.; Ahmad, Absar; Sastry, M. (Crystal Growth & Design, 2005)
The total biological synthesis of CaCO3 crystals of the metastable vaterite polymorph at room temperature by simple protein-mediated reaction of aqueous Ca2+ ions with the CO2 generated during the root growth from germinating chickpea (Cicer arietinum) seeds is described. Highly stable vaterite crystals of spherical morphology are obtained, indicating that the proteins secreted from the roots during growth play a crucial role in stabilizing and directing the crystal growth.

Biphenyl hydrogenation over supported transition metal catalysts under supercritical carbon dioxide solvent - Hiyoshi, Norihito; Rode, C. V.; Sato, O.; Shirai, M. (Applied Catalysis A - General, 2005)
Catalytic hydrogenation of biphenyl to bicyclohexyl, an organic hydrogen storage medium, was examined over supported transition metal catalysts in supercritical carbon dioxide solvent. The yield of bicyclohexyl was almost 100% over the charcoal-supported rhodium (Rh/C) and ruthenium (Ru/C) catalysts at the temperature of 323 K, which was much lower than that required for biphenyl hydrogenation in organic solvents (573 K). The initial activity was higher over the Rh/C catalyst, while the initial selectivity to bicyclohexyl was higher over the Ru/C catalyst. The conversion of biphenyl increased with increase in hydrogen and carbon dioxide pressures, while the selectivity to bicyclohexyl was independent of hydrogen and carbon dioxide pressures over both catalysts. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: bicyclohexyl; biphenyl; charcoal-supported rhodium catalyst; charcoal-supported ruthenium catalyst; Hydrogen storage; Hydrogenation; Supercritical carbon dioxide

Carbohydrate-based approach for the total synthesis of 1,3-polyol/alpha-pyrone antifungal natural products - Ramana, Chepuri V.; Srinivas, B.; Puranik, Vedavati G.; Gurjar, M. K. (Journal of Organic Chemistry, 2005)
An elimination and stereoselective hydrogenation of alpha-D-glucoheptonic-gamma-lactone derivative has been applied to prepare a differentially protected anti,anti-1,3,5-triol system, the utility of which has been extended for the total synthesis of anti-fungal 1,3-polyol/alpha-pyrone natural products.

Carbohydrate-based approach for the total synthesis of strictifolione - Ramana, C. V.; Raghupathi, N.; Gurjar, M. K.; Chorghade, Mukund S. (Tetrahedron Letters, 2005)
A chiral pool approach starting with D-glucose, using the Yamaguchi protocol and a Z-selective HWE reaction followed by lactonization, has been applied to execute the total synthesis of strictifolione. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: D-Glucose; double elimination; Horner-Wadsworth-Emmons reaction; lactonization; strictifolione; Yamaguchi protocol

Cataloguing Indian biota - Response - Chavan, V.; Watve, A. V.; Rane, N. S.; Krishnan, S. (Current Science, 2005)

Characterization of gas-liquid flows in rectangular bubble columns using conductivity probes - Buwa, Vivek V.; Ranade, Vivek V. (Chemical Engineering Communications, 2005)
Unsteady gas-liquid flows in bubble columns are comprised of various flow processes occurring with varying length and time scales and govern mixing and transport processes. In the present work, we have characterized dynamic and time-averaged properties of gas-liquid flows in rectangular bubble columns using conductivity probes. The development of a single-tip conductivity probe, data processing methodology, and photographic validation procedure is discussed in detail. The effect of superficial gas velocity and aerated liquid height-to-width ( H/W) ratio on voidage fluctuations and time-averaged gas holdup was investigated. The experimental data presented here can help in understanding the dynamics of various flow processes and validating computational fluid dynamics based models.
Keywords: Bubble column; gas holdup; gas-liquid flows; voidage fluctuations

Characterization of gas-liquid flows in stirred vessels using pressure and torque fluctuations - Khopkar, A. R.; Panaskar, S. S.; Pandit, A. B.; Ranade, V. V. (Industrial & Engineering Chemistry Research, 2005)
Gas-liquid flows in a stirred vessel exhibit different flow regimes and demonstrate complex interaction of transport processes with varying spatio-temporal scales. The knowledge of key space and time scales of fluid dynamics is important for designing and enhancing the performance of gas-liquid stirred reactor. The present study uses simple, robust, and nonintrusive experimental techniques (torque and pressure sensors) to characterize the fluid dynamics in a gas-liquid stirred vessel. Time series obtained from the pressure and torque sensors were analyzed to develop criteria for flow regime identification. Further analyses of torque and pressure time series were done to extract valuable information of different time scales of fluid dynamics. The detailed analysis of torque and wall pressure fluctuations provided not only an insight into the fluid dynamics but also a possible opportunity to on-line monitoring of gas-liquid flows in stirred vessel.

Characterization of nanocrystalline anatase titania: an in situ HTXRD study - Jagtap, Neelam; Bhagwat, Mahesh; Awati, Preeti; Ramaswamy, Veda (Thermochimica Acta, 2005)
Nanocrystalline titania was synthesized by the hydrolysis of titanium iso-propoxide using ultrasonication. The powder XRD patterns of the sample were recorded in static air and vacuum using a Philips X-pert Pro diffractometer equipped with a high-temperature attachment (HTK16) from room temperature (298 K) to 1173 K and were analyzed by the Rietveld refinement technique. The anatase to rutile phase transformation was observed at 1173 K for the data collected in static air. Only 3% of anatase titania transformed to rutile when the experiments were carried out at H 73 K in vacuum. The phase transformation from anatase to rutile is accompanied by a continuous increase in the crystallite size of the anatase phase from 9 nm at room temperature to 28 nm at 873 K and then to 50 nm at 1173 K in air while the process of crystallite growth was suppressed in vacuum. A linear increase in the unit cell parameters `a' and `c', and thus, an overall linear increase in the unit cell volume was observed as a function of temperature in static air as well as vacuum. The lattice and volume thermal expansion coefficients (TEC), alpha(a), alpha(c), and alpha(v) at 873 K are 8.57 x 10(-6), 8.71 x 10(-6) and 25.91 x 10(-6) K-1 in air and 18.01 x 10(-6), 14.95 x 10(-6) and 51.13 x 10(-6) K-1 in vacuum, respectively. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: Anatase; HTXRD; Rietveld refinement; rutile; thermal expansion coefficient; titania

Cloning, purification, crystallization and preliminary structural studies of penicillin V acylase from Bacillus subtilis - Rathinaswamy, P.; Pundle, A. V.; Prabhune, Asmita; SivaRaman, H.; Brannigan, James A.; Dodson, Guy G.; Suresh, C. G. (Acta Crystallographica Section F-Structural Biology Communications, 2005)
{Penicillin acylase proteins are amidohydrolase enzymes that cleave penicillins at the amide bond connecting the side chain to their beta-lactam nucleus. An unannotated protein from Bacillus subtilis has been expressed in Escherichia coli, purified and confirmed to possess penicillin V acylase activity. The protein was crystallized using the hanging-drop vapour-diffusion method from a solution containing 4 M sodium formate in 100 mM Tris-HCl buffer pH 8.2. Diffraction data were collected under cryogenic conditions to a spacing of 2.5 A. The crystals belonged to the orthorhombic space group C222(1), with unit-cell parameters a = 111.0

CO2 activation and synthesis of cyclic carbonates and alkyl/aryl carbamates over adenine-modified Ti-SBA-15 solid catalysts - Srivastava, R; Srinivas, D; Ratnasamy, P (Journal of Catalysis, 2005)
Cyclic carbonates were synthesized by the cycloaddition Of CO2 to epoxides (epichlorohydrin, propene oxide, and styrene oxide), and carbamates were synthesized by reaction of alkyl or aryl amines, CO2, and n-butyl bromide. Solvents and cocatalysts/promoters, like N,N-dimethylaminopyridine (DMAP) and quaternary ammonium salts, which are usually essential with conventional catalyst systems, could be avoided with the use of adenine-modi lied Ti-SBA-15 catalysts. The catalysts were reused in several recycle experiments. The structural and textural properties of the catalysts were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), N-2 adsorption, and Fourier transform infrared (FTIR) and diffuse reflectance ultraviolet-visible (UV-vis DRS) techniques. Acid-base properties of the solid catalysts were investigated by temperature-programmed desorption (TPD) of NH3 and CO2 and DRIFTIR spectroscopy of adsorbed pyridine and CO2 techniques. The studies reveal that the Ti4+ ions increase catalytic activity by enhancing the adsorption of the epoxide and alkyl or aryl amine substrates. CO2 molecules are activated at the basic nitrogen groups of adenine. Increasing the surface concentrations of either CO2 (by anchoring basic molecules like adenine or increasing the partial pressure of CO2) or epoxides and alkyl or aryl amines (by increasing the concentration of Lewis acidic Ti4+ ions) enhances the catalytic activity. CO2 molecules activated at the covalently anchored adenine sites react with epoxide/amines adsorbed on the silica surface to form carbonates/carbamates. (c) 2005 Elsevier Inc. All rights reserved.
Keywords: activation of CO2; CO2 fixation; DRIFTIR spectroscopy of adsorbed pyridine and CO2; organo-functionalized mesoporous silica; phosgene-free synthesis; synthesis of carbamates; synthesis of cyclic carbonates; temperature-programmed desorption of NH3 and CO2 titanosilicates; Ti-SBA-15

Computational study of a single-phase flow in packed beds of spheres - Gunjal, P. R.; Ranade, V. V.; Chaudhari, Raghunath V. (AICHE Journal, 2005)
Packed-bed reactors are widely used in petrochemical, fine chemical, and pharmaceutical industries. Detailed knowledge of interstitial flow in the void space of such packed-bed reactors is essential for understanding the heat and mass transfer characteristics. In this paper, fluid flow through the array of spheres was studied using the unit-cell approach, in which different periodically repeating arrangements of particles such as simple cubical, 1-D rhombohedral, 3-D rhombohedral, and face-centered cubical geometries were considered. Single-phase flow through these geometries was simulated using computational fluid dynamics (CFD). The model was first validated by comparing predicted results with published experimental and computational results. The validated model was further used to study the effect of particle arrangement/orientation on velocity distribution and heat transfer characteristics. The simulated results were also used to understand and to quantify, relative contributions of surface drag and form drag in overall resistance to the flow through packed-bed reactors. The model and the results presented here would be useful in elucidating the role of microscopic flow structure on mixing and other transport processes occurring in packed-bed reactors. (C) 2005 American Institute of Chemical Engineers.
Keywords: CFD; drag; heat transfer; packed bed; packing arrangement

Controlling the optical properties of lemongrass extract synthesized gold nanotriangles and potential application in infrared-absorbing optical coatings - Shankar, S. S.; Rai, A.; Ahmad, Absar; Sastry, M. (Chemistry of Materials, 2005)
Anisotropic metal nanoparticles have distinct optical behavior when compared with their spherical counterparts. In this report, we demonstrate a simple method involving the reduction of aqueous gold ions by the extract of the lemongrass plant leading to the formation of gold nanotriangles with interesting absorption in the near-infrared (NIR) region of the electromagnetic spectrum. We show that, by simple variation of the experimental conditions, it is possible to vary the size of the gold nanotriangles and, thus, to tune the absorbance of flat gold nanoparticles in the NIR region. The NIR absorption of the gold nanotriangles is expected to be of application in hyperthermia of cancer cells and in IR-absorbing optical coatings. We show that the lemongrass extract synthesized gold nanotriangles can be easily cast in the form of films on glass substrates and that these films are highly efficient in absorbing IR radiation for potential architectural applications.

Co-precipitation method for the preparation of ferroelectric CaBi4Ti4O15 - Gaikwad, S. P.; Dhage, S. R.; Ravi, V. (Journal of Materials Science-Materials in Electronics, 2005)
A simple co-precipitation technique has been successfully applied for the preparation of pure single phase CaBi4Ti4O15 (CBT) powders. Ammonium oxalate and ammonium hydroxide were used to precipitate Ca2+, Bi3+ and Ti4+ cations simultaneously. No pyrochlore phase was found while heating powder at 600&DEG; C and pure CBT phase was found to be formed by X-ray diffraction. Particle size and morphology was studied by transmission electron microscopy (TEM). The room temperature dielectric constant at 1 kHz is 400. The ferroelectric hysteresis loop parameters of these samples were also studied. (C) 2005 Springer Science + Business Media, Inc.

Co-precipitation method for the preparation of fine ferroelectric BaBi2M2O9 - Gaikwad, S. P.; Potdar, HS; Samuel, V; Ravi, V (Ceramics International, 2005)
A simple co-precipitation technique had been successfully applied for the preparation of pure fine powders of single phase BaBi2Nb2O9. Ammonium hydroxide and ammonium oxalate were used to precipitate Ba2+, Bi3+ and Nb5+ cations simultaneously. No pyrochlore phase was formed while heating powder at 800 degrees C and pure BaBi2Nb2O9 phase was found to be formed by X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at 1 kHz is 100. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Keywords: dielectric properties; Electron microscopy; ferroelectric properties; powders chemical preparation

Co-precipitation method for the preparation of nanocrystalline ferroelectric SrBi2Nb2O9 ceramics - Gaikwad, S. P.; Dhage, S. R.; Potdar, H. S.; Samuel, V.; Ravi, V. (Journal of Electroceramics, 2005)
A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase SrBi2Nb2O9. Ammonium hydroxide and ammonium oxalate were used to precipitate Sr2+, Bi3+ and Nb5+ cations simultaneously. No pyrochlore phase was found while heating powder at 850 C and pure SrBi2Nb2O9 (SBN) phase was formed as revealed by the X-ray diffraction (XRD) studies. Particle size and morphology was studied by transmission electron microscopy (TEM). The room temperature dielectric constant at 1 kHz is 100. The ferroelectric hysteresis loop parameters of these samples were also studied.
Keywords: Ceramics; Chemical synthesis; electronic materials; ferroelectricity; Oxides

Coprecipitation technique to prepare BaNb2O6 - Natarajan, N; Samuel, V; Pasricha, R; Ravi, V (Materials Science and Engineering B-Solid State Materials for Advanced Technology, 2005)
A mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and niobium ions as barium oxalate and niobium hydroxide under basic conditions. This precursor on calcination at 750degreesC yielded BaNb2O6 ceramics. This is a much lower temperature as compared to that prepared by traditional solid-state method (1000degreesC), as reported for the formation of BaNb2O6. Transmission electron microscope (TEM) investigations revealed that the average particle size is 100 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 1100. The ferroelectric hysteresis loop parameters of these samples were also studied. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: Ammonia; Ceramics; Electron microscopy; niobium oxide; Oxides

Coprecipitation technique to prepare SrNb2O6 - Ravi, V (Materials Characterization, 2005)
A mixture of ammonium oxalate and ammonium hydroxide was used to co-precipitate strontium and niobium ions as strontium oxalate and niobium hydroxide under basic conditions. This precursor yielded SrNb2O6 ceramics on calcining at 650 degrees C. This is a much lower temperature compared to preparation of SrNb2O6 by the traditional solid state method (900 degrees C). Transmission electron microscopy (TEM) revealed that the average particle size is 100 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 550. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2005 Elsevier Inc. All rights reserved.
Keywords: Ceramics; Electron microscopy; ferroelectric; Oxides; X-ray methods

Coprecipitation technique to prepare ZnM2O6 powders - Deshpande, V. V.; Patil, M. M.; Navale, S. C.; Ravi, V. (Bulletin of Materials Science, 2005)
A simple coprecipitation technique was successfully applied for the preparation of pure ultrafine single phase, ZnNb2O6 (ZN). Ammonium hydroxide was used to precipitate Zn2+ and Nb5+ cations as hydroxides simultaneously. This precursor on heating at 750 degrees, produced ZN powders. For comparison, ZN powders were also prepared by the traditional solid state method. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM).
Keywords: Ceramics; Electron microscopy; electronic materials; X-ray diffraction

Design, syntheses, and characterization of new thermoplastic polyureas based on 3,4-ethylenedioxythiophene - Ojha, U. P.; Ramesh, C.; Kumar, Anil (Journal of Polymer Science Part A-Polymer Chemistry, 2005)
New thermoplastic polyureas labeled PUn (n = 2, 3, 4, 6, 7, 9, or 10), based on 3,4-ethylenedioxythiophene (EDOT) with flexible aliphatic spacers, were synthesized and characterized for the first time. EDOT was chosen as a replacement for the aromatic phenyl group in conventional thermoplastics based on urea linkages to improve solubility without compromising the thermal properties. As synthesized, all the samples exhibited a semicrystalline nature. The glass-transition and melting temperatures showed a strong dependence on the spacer length. A comparison of the thermal properties of these polyureas with the corresponding phenyl analogues indicated that EDOT was a viable heteroatomic analogue of the phenyl group to be inserted into the main-chain polyureas without hampering their thermal stability. The polyureas with spacer lengths greater than hexamethylene formed transparent gels in N-methylpyrrolidone, 1,1,2,2-tetrachloroethane, and dimethyl sulfoxide. The molecular packing of the polyureas was assigned with wide-angle X-ray diffraction studies. (c) 2005 Wiley Periodicals, Inc.
Keywords: 3; 4-ethylenedioxythiophene; heteroaromatic polymers; Polyurea; polyurea gels; Thermogravimetric analysis (TGA); thermoplastics; WAXS

Destructive adsorption of methyl parathion over nanocrystalline MgO - Reddy, V. S.; RadheShyam, A.; Dwivedi, Reena; Gupta, R. K.; Chumbhale, Vilas R.; Prasad, R. (Indian Journal of Chemistry Section A-Inorganic Bio-Inorganic Physical Theoretical & Analytical Chemistry, 2005)
Destructive adsorption of methyl parathion (MP) has been investigated over few transition metal oxides and alkali earth metal oxides. Performance of alkaline earth oxides have been found to be better than transition metal oxides and best performance has been shown by aerogel method prepared nanocrystalline AP-MgO. The AP-MgO powder has been characterized by XRD, AFM and BET surface area measurements. Destructive adsorption of MP over AP-MgO has been compared with that of activated carbon. Both are found to adsorb methyl parathion effectively. An IR investigation of the surface of treated AP-MgO and activated carbon reveals that activated carbon adsorbs methyl parathion as such in the molecular form and AP-MgO adsorbs it destructively.

Determination of C-13 CSA tensors: extension of the model-independent approach to an RNA kissing complex undergoing anisotropic rotational diffusion in solution - Ravindranathan, S; Kim, CH; Bodenhausen, G (Journal of Biomolecular NMR, 2005)
Chemical shift anisotropy (CSA) tensor parameters have been determined for the protonated carbons of the purine bases in an RNA kissing complex in solution by extending the model-independent approach [Fushman, D., Cowburn, D. (1998) J. Am. Chem. Soc. 120, 7109-7110]. A strategy for determining CSA tensor parameters of heteronuclei in isolated X-H two-spin systems (X = C-13 or N-15) in molecules undergoing anisotropic rotational diffusion is presented. The original method relies on the fact that the ratio kappa(2)=R-2(auto)/R-2(cross) of the transverse auto- and cross-correlated relaxation rates involving the X CSA and the X-H dipolar interaction is independent of parameters related to molecular motion, provided rotational diffusion is isotropic. However, if the overall motion is anisotropic kappa(2) depends on the anisotropy D parallel to/D-perpendicular to of rotational diffusion. In this paper, the field dependence of both kappa(2) and its longitudinal counterpart kappa(1)=R-1(auto)/R-1(cross) are determined. For anisotropic rotational diffusion, our calculations show that the average kappa(av) = 1/2 (kappa(1)+kappa(2)), of the ratios is largely independent of the anisotropy parameter D parallel to/D-perpendicular to. The field dependence of the average ratio kappa(av) may thus be utilized to determine CSA tensor parameters by a generalized model-independent approach in the case of molecules with an overall motion described by an axially symmetric rotational diffusion tensor.
Keywords: anisotropic rotational diffusion; chemical shift anisotropy tensors; cross-correlation; model-independent approach; NMR

Diastereoselective amidoalkylation of (3S,7aR)-6-benzyl-7-hydroxy-3-phenyltetra-hydro-5H-imidazo[1,5-c][1, 3]thiazol-5-one : a short and highly efficient synthesis of (+)-biotin - Chavan, Subhash P.; Chittiboyina, A. G.; Ravindranathan, T.; Kamat, Subhash K.; Kalkote, Uttam R. (Journal of Organic Chemistry, 2005)
A short and highly efficient synthesis of W-biotin in 10 steps with 20% overall yield has been achieved from L-cysteine involving amidoalkylation of hydroxy imidazothiazolone 4 via an acyliminium ion intermediate to furnish C-7-substituted imidazothiazolones 5b as the key step.

Dynamics of drop impact on solid surface: experiments and VOF simulations - Gunjal, P. R.; Ranade, V. V.; Chaudhari, Raghunath V. (AICHE Journal, 2005)
The process of spreading/recoiling of a liquid drop after collision with a flat solid surface was experimentally, and computationally studied to identify the key issues in spreading of a liquid drop oil a solid surface. The long-term objective of this study is to gain an insight in the phenomenon of wetting of solid particles in the trickle-bed reactors. Interaction of a falling liquid drop with a solid surface (impact, spreading, recoiling, and bouncing) was studied using a high-speed digital camera. Experimental data oil dynamics of a drop impact on flat surfaces (glass and Teflon) are reported over a range of Reynolds numbers (550-2500) and Weber numbers (2-20). A computational fluid dynamics (CFD) model, based on the volume of fluid (VOF) approach, was used to simulate drop dynamics on the flat sufaces. The experimental results were compared with the CFD simulations. Simulations showed reasonably good agreement with the experimental data. A VOF-based computational model was able to capture key features of the interaction of a liquid drop with solid surfaces. The CFD simulations provide information about finer details of drop interaction with the solid surface. Information about gas-liquid and liquid-solid drag obtained from VOF simulations would be useful for CFD modeling of trickle-bed reactors. (C) 2004 American Institute of Chemical Engineers.
Keywords: CFD; drop impact; recoiling; spreading; trickle bed; VOF

(E)-1-(2-Hydroxy-3,4-dimethoxyphenyl)-3-(4-hydroxyphenyl)-prop-2-en-1-on e - Krishna, J. R.; Kumar, N. J.; Krishnaiah, M.; Rao, C. V.; Rao, Y. K.; Puranik, Vedavati G. (Acta Crystallographica Section E-Structure Reports Online, 2005)
The title compound, C17H16O5, crystallizes with two independent molecules in the asymmetric unit. These are oriented approximately orthogonal to one another. The keto group adopts an s-cis conformation; the six-membered ring formed by the O-H&BULL;&BULL;&BULL; O hydrogen bond and the adjacent benzene ring are approximately coplanar. In addition to an intramolecular O-H&BULL;&BULL;&BULL; O hydrogen bond, intermolecular O-H&BULL;&BULL;&BULL; O interactions link adjacent molecules into chains.

Effect of 2-(2-pyridyl)azole-based ancillary ligands (L1-4) on the electrophilicity of the nitrosyl function in [Ru-II(trpy)(L1-4)(NO)](3+) [trpy=2,2 `: 6 `,2 `'-terpyridine]. synthesis, structures, and spectroscopic, electrochemical, and kinetic aspects - Chanda, N.; Paul, D.; Kar, S.; Mobin, Shaikh M.; Datta, Anindya; Puranik, Vedavati G.; Rao, K. K.; Lahiri, Goutam Kumar (Inorganic Chemistry, 2005)
Ruthenium nitrosyl complexes [Ru(trpy)(L1-4)(NO)](3+) (13-16) [trpy = 2,2':6',2"-terpyridine, L-1 = 2-(2-pyridyl)-benzoxazole, L-2 = 2-(2-pyridyl)benzthiazole, L-3 = 2-(2-pyridyl)benzimidazole, L-4 = 1-methyl-2-(2-pyridyl)-1H-benzimidazole] were obtained in a stepwise manner starting from [Ru-II(trpy)(L1-4) (Cl)]ClO4 (1-4) &RARR; [Ru-II(trpy)(L1-4) (H2O)](ClO4)(2) (5-8) &RARR; [Ru-II(trpy)(L1-4) (NO2)ClO4 (9-12) &RARR; [Ru-II(trpy)(L-1,L-2,L-4) (NO)](ClO4)(3) (13, 14, 16)/[Ru-II(trpy)(L-3) (NO)](Cl)(4))(2)(NO3) (15). Crystal structures of 1, 2, 4, 9, 12, 13, 15, and 16 established the stereoretentive nature of the transformation processes. Though the complexes of L1, L3, and L 4 were isolated in the isomeric form A (π-acceptor trpy and azole ring in the equatorial plane and the pyridine and chloride donors in the axial positions), complexes of L 2 preferentially stabilized in form B (trpy and pyridine in the equatorial plane and the azole ring and chloride donors in the axial positions). The v(NO) stretching frequency varied in the range of 1957-1932 cm(-1), 13 &MGT; 14 &MGT; 15 > 16, primarily depending on the electronic aspects of L as well as the isomeric structural forms. The coordinated nitrosyl function underwent successive reductions of [Ru-II-NO+](3+) &RARR; [Ru-II-NO&BULL;](2+) and [Ru-II-NO&BULL;](2+) - [Ru-II-NO-](+), and the first reduction potential follows the order 14 > 13 &MGT; 15 &AP; 16. The nearly axial EPR spectra having nitrogen hyperfine splittings (A &AP; 26 G) at 77 K of 13(-)-16(-) with (g) &AP; 2.0 established that the reduction process is largely centered around the nitrosyl function. Despite an appreciably high v(NO), the complexes were found to be unusually stable even in the aqueous medium. They transformed slowly and only partially into the corresponding nitro derivatives in H2O (k &AP; 10(-4) s(-1) and K = 0.4-3.8). The chloro (1-4), aqua (5-8), and nitro (9-12) derivatives displayed reasonably strong emissions near 700 nm at 77 K (φ = 10(-1)-10(-2)). The aqua derivative 7 was found to interact with the calf thymus and the circular form of p-Bluescript SK DNA.

Effect of connectivity and terminal functionality on mesophase behaviour of thermotropic liquid crystals containing biphenyl units - Ranganathan, T.; Ramesh, C.; Kumar, Anil (Liquid Crystals, 2005)
A series of 4,4'-disubstituted biphenyls, designated as series HBC, in which, one substituent is an ester group linked directly to the ring and the other is the hydroxy-containing group O(CH2)(n)OH, have been prepared and analysed by differential scanning Calorimetry, polarizing optical microscopy and X-ray diffraction. The introduction of a trimethylene unit between the ester functional group and the biphenyl moiety of the HBC series gives rise to the HBB series, which did not exhibit liquid crystalline behaviour. Interestingly, mesophase behaviour could be restored by replacing the methylene group ( of the trimethylene unit) that was directly attached to the biphenyl ring by a keto group (HBOB series). When the terminal hydroxy group of these three series was substituted by a group such as acetoxy or hydrogen, the transition temperatures were reduced, and the disappearance of mesophase behaviour was observed in some cases. However, this could be recovered by the replacement of the ester group by a carboxylic acid group.

Effect of RuO2 in the shape selectivity of submicron-sized SnO2 structures - Ramgir, N. S.; Mulla, Imtiaz S.; Vijayamohanan, K. P. (Journal of Physical Chemistry B, 2005)
Several dissimilar types of tin oxide microstructures including bipyramids, cubes, and wires synthesized effectively by means of a simple approach were investigated using X-ray diffraction (XRD), thermogravimetry/ differential thermometric analysis (TG-DTA), and X-ray photoelectron spectroscopy (XPS). A possible growth mechanism is proposed using the results of these studies. The texture coefficient values of all the structures, indexed to a tetragonal lattice, exhibit amazing variation in the preferred orientation with respect to their shapes. Although XPS data indicate that wires and cubes have a strong SnO2 type signal, bipyramids interestingly exhibit both SnO and SnO2 signals and a correlation of the binding energy helps in understanding the growth kinetics of such submicron structures. The. results suggest that the bipyramids are formed because of the vapor-solid process (VS) while wires and cubes are formed by the vapor-liquid-solid (VLS) progression.

Enhanced selectivity to decalin in naphthalene hydrogenation under supercritical carbon dioxide - Hiyoshi, Norihito; Miura, R.; Rode, C. V.; Sato, O.; Shirai, M. (Chemistry Letters, 2005)
A charcoal-supported rhodium catalyst was highly active and selective to decalin for the hydrogenation of naphthalene at very low temperature (333 K) under supercritical carbon dioxide.

Facile direct conversion of aldehydes to esters and amides using acetone cyanohydrin - Raj, I. V. P.; Sudalai, A. (Tetrahedron Letters, 2005)
Aromatic aldehydes with electron-withdrawing groups undergo rapid reactions with a variety of alcohols and secondary amines to afford the corresponding esters and amides, respectively, in high yields, when treated with NaCN or acetone cyanohydrin and base under ambient reaction conditions. In case of alpha,beta-unsaturated aldehydes, simultaneous reduction of the C=C bond along with esterification occurred to produce the saturated esters in high yields. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: amidation; esteritication; reduction; sodium cyanide

First synthesis of a noreremophilane isolated from the roots of ligularia przewalskii - Reddy, D. Srinivasa; Palani, K.; Balasubrahmanyam, D.; Kamath, V. B.; Iqbal, Javed (Tetrahedron Letters, 2005)
The total synthesis of a natural product noreremophilane has been achieved in just three steps from readily available starting materials. A highly stereo- and regio-selective Diels-Alder reaction was the key step in Our synthesis. (c) 2005 Elsevier Ltd. All rights reserved.

Formation of BaCrO4 nano crystallites within thermally evaporated sodium bis-2-ethylhexyl-sulfosuccinate and stearic acid thin films - Rautaray, D.; Sinha, K.; Sainkar, S. R.; Pasricha, R.; Pavaskar, N. R.; Sastry, M. (Journal of the American Ceramic Society, 2005)
This paper describes the growth of barium chromate (BaCrO4) nanocrystallites within thermally evaporated thin films of stearic acid (StA) and sodium bis-2-ethylhexyl-sulfosuccinate by a process of Ba2+ ion entrapment followed by in situ reaction CrO42- ions. Dense spherical assemblies of BaCrO4 nanocrystallites of very uniform size (similar to50 nm) were obtained within the two different host matrices. The spherical assemblies were composed of smaller (ca. 5-10 nm size) BaCrO4 crystals indicating that efficient size control over crystal size may be exercised by the matrix. Contact angle measurements of the BaCrO4-StA and BaCrO4-sodium bis-2-ethylhexyl-sulfosuccinate films indicated that they were hydrophobic, thus pointing to the possible role of hydrophobic interaction between the StA and sodium bis-2-ethylhexyl-sulfosuccinate monolayer-covered BaCrO4 crystals in the assembly process.

Free-standing nanogold membranes as supports for the growth of calcium phosphate crystals - Rautaray, D; Sastry, M (Biotechnology Progress, 2005)
Current strategies for bone tissue regeneration focus on the development of implantable matrices that mimic biological tissues. Inorganic composites are of special interest for bone substitute applications. It is necessary to create an artificial three-dimensional scaffold-like porous material with certain geometrical structure to induce bone growth. We report here the growth of calcium phosphate crystals on free-standing carboxylic acid functionalized gold nanoparticle membranes. The gold nanoparticle membrane is synthesized by the spontaneous reduction of aqueous chloroaurate ions by a diamine molecule at a liquid-liquid interface. This membrane is robust and malleable, and most importantly, the gold nanoparticles in the membrane may be functionalized with suitable ligands. In this study, the amino acids aspartic acid and cysteine together with an aromatic bifunctional molecule, anthranilic acid, were used to modify the surface of the gold nanoparticles in the membrane. The free carboxylic acid groups on the gold nanoparticles further to functionalization with these molecules were then used to bind Ca2+ ions and reacted with phosphate ions to yield calcium phosphate. The nature of the nanogold surface modifier directed the formation of either crystalline hydroxyapatite or amorphous calcium phosphate. The nanogold membrane thus suggests potential biomedical application as biocompatible implants and grafts.

Functional copolymers of p-cumyl phenyl methacrylate and glycidyl methacrylate: synthesis, characterization, and reactivity ratios - Ratnaprabha, K.; Daliya, P. K. (Journal Applied Polymer Science, 2005)
Free-radical polymerization of p-cumyl phenyl methacrylate (CPMA) was performed in benzene using bezoyl peroxide as an initiator at 80&DEG; C. The effect of time on the molecular weight was studied. Functional copolymers of CPMA and glycidyl methacrylate (GMA) with different feed ratios were synthesized by free-radical polymerization in methyl ethyl ketone at 70&DEG; C, and they were characterized by FTIR and H-1-NMR spectroscopy. The molecular weights and polydispersity indexes of the polymers and copolymers were determined by gel permeation chromatography. The copolymer composition was determined by H-1-NMR. The glass-transition temperature of the polymer and the copolymers was determined by differential scanning calorimetry. The reactivity ratios of the monomers were determined by the Fineman-Ross and Kelen-Tudos methods. © 2005 Wiley Periodicals, Inc.
Keywords: copolymerization; functionalization of polymers; glass-transition; synthesis

Fungus-mediated biosynthesis of silica and titania particles - Bansal, Vipul; Rautaray, D.; Bharde, Atul A.; Ahire, Kedar C.; Sanyal, A.; Ahmad, Absar; Sastry, Murali (Journal of Materials Chemistry, 2005)
The synthesis of inorganic materials by biological systems is characterized by processes that occur at close to ambient temperatures, pressures and neutral pH. This is exemplified by biosilicification in marine organisms such as diatoms while laboratory-based synthesis of silica involves extreme temperature and pH conditions. We show here that silica and titania particles may be produced by challenging the fungus Fusarium oxysporum with aqueous anionic complexes SiF62- and TiF62- respectively. Extra-cellular protein-mediated hydrolysis of the anionic complexes results in the facile room temperature synthesis of crystalline titania particles while calcination at 300 degrees C is required for crystallization of silica.

Gas-liquid flow generated by a Rushton turbine in stirred vessel: CARPT/CT measurements and CFD simulations - Khopkar, A. R.; Rammohan, A. R.; Ranade, V. V.; Dudukovic, M. P. (Chemical Engineering Science, 2005)
In this work, computer-automated radioactive particle tracking (CARPT), computed tomography (CT) and computational fluid dynamic (CFD) based models were used to investigate gas-liquid flow generated by a Rushton turbine. CARPT and CT measurements were carried out in a gas-liquid stirred vessel operating in two different flow regimes and captured the quantitative Eulerian information of gas-liquid flow. The CARPT data was then used to extract the circulation tune distribution in a vessel. A two-fluid model along with the standard k-epsilon turbulence model was used to simulate the dispersed gas-liquid flow in a stirred vessel. Appropriate drag corrections to account for bulk turbulence (along the lines proposed by Brucato et al. (Chem. Eng. Sci. 45(1998) 3295)) were developed to correctly simulate different flow regimes. The computational snapshot approach was used to simulate impeller rotation and was implemented in the commercial CFD code, FLUENT4.5 (of Fluent. Inc., USA). Most model predictions compared favourably with CARPT and CT measurements. Validated CFD models as attempted in this paper are promising to simulation of industrial stirred vessels. (c) 2005 Elsevier Ltd. All rights reserved.
5th International Symposium on Mixing in Industrial Processes, Seville, SPAIN, JUN 01-04, 2004
Keywords: CARPT; CFD; CT; gas-liquid flow; stirred vessel

Heavy-metal remediation by a fungus as a means of production of lead and cadmium carbonate crystals - Sanyal, A.; Rautaray, D.; Bansal, Vipul; Ahmad, Absar; Sastry, Murali (Langmuir, 2005)
We show here that reaction of the fungus, Fusarium oxysporum, with the aqueous heavy-metal ions Pb2+ and Cd2+ results in the one-step formation of the corresponding metal carbonates. The metal carbonates are formed by reaction of the heavy-metal ions with CO2 produced by the fungus during metabolism and thus provide a completely biological method for production of crystals of metal carbonates. The PbCO3 and CdCO3 crystals thus produced have interesting morphologies that are shown to arise because of interaction of the growing crystals with specific proteins secreted by the fungus during reaction. An additional advantage of this approach is that the reaction leads to detoxification of the aqueous solution and could have immense potential for bioremediation of heavy metals. Under conditions of this study, the metal ions are not toxic to the fungus, which readily grows after exposure to the metal ions.

Hydrodynamics of trickle-bed reactors: experiments and CFD modeling - Gunjal, P. R.; Kashid, M. N.; Ranade, V. V.; Chaudhari, Raghunath V. (Industrial & Engineering Chemistry Research, 2005)
{Hydrodynamics of trickle-bed reactors involve complex interactions of gas and liquid phases with packed solids. Such complex interactions manifest in different flow regimes occurring in trickle-bed reactors. Knowledge of prevailing flow regime, pressure drop, and liquid holdup is essential for design and performance evaluation of the reactor. Detailed knowledge of fluid dynamics is essential for ``a priory'' predictions as well as for interpretation of available data. In this study, we have used wall pressure fluctuation measurements to identify prevailing flow regime in trickle beds. Experiments were carried out on two scales of columns (of diameter 10 cm and 20 cm) with two sets of particles (3 min and 6 mm diameter spherical particles). Effects of prewetted and unwetted bed conditions on pressure drop and liquid holdup were reported for a range of operating conditions (V-G = 0.22-0.44 kg/m(2)s

Illustration of HIV-1 protease folding through a molten-globule-like intermediate using an experimental model that implicates alpha-crystallin and calcium ions - Dash, C; Sastry, M; Rao, M (Biochemistry, 2005)
The folding of HIV-1 protease to its active form involves the coordination of structure formation and dimerization, which follows a hierarchy consisting of folding nuclei spanning from the active site, hinge region, and dimerization domain. However, the biochemical characteristics of the folding intermediates of this protein remain to be elucidated. In an experimental model, the denaturation of the tethered dimer of HIV-1 protease by guanidine hydrochloride revealed an alternative conformation resembling the molten globule state. The molten-globule state binds to the molecular chaperone alpha-crystallin and prevents its aggregation; however, the chaperone alone failed to reconstitute HIV-1 protease into its active form. Calcium ion assisted in the release of active enzyme from the chaperone complex. alpha-crystallin, a member of the small heat-shock protein, assists proteins to fold correctly; however, the underlying principle of signals responsible for chaperone-mediated protein folding remains enigmatic. X-ray photoelectron spectroscopy has been employed to provide the evidence of calcium binding to alpha-crystallin and to decipher the effect of calcium binding on the chaperone-mediated refolding of HIV-1 protease. On the basis of our spectroscopic data, we propose that calcium ions interact with the carboxyl groups of the surface-exposed acidic amino acids of alpha-crystallin bringing electrostatic interference, which plays a pivotal role in inducing conformational changes in the chaperone responsible for the release of the active enzyme.

Immobilized molybdovanadophosphoric acids on SBA-15 for selective oxidation of alkenes - Raj, N. K. K.; Deshpande, S. S.; Ingle, Rohit H.; Raja, T.; Manikandan, Palanichamy (4th International Symposium on Nanoporous Materials, 2005)
Vanadium substituted molybdophosphoric acids have been immobilized on amine functionalized SBA-15 and characterized by different techniques. Small angle X-ray scattering analysis and SEM technique provide evidence for the structural integrity of the samples. UV-Vis, NMR and IR data confirm the incorporation of molybdovanadophosphoric acids onto the amine functionalized SBA-15. The textural properties of these materials were studied by nitrogen sorption studies. Oxidation of cyclooctene and norbornene was carried out with oxidants in aqueous (aq. H2O2) and non-aqueous (TBHP extracted in dichloroethane) medium. The reactions were carried out with both the neat catalysts (homogeneous) and the immobilized catalysts (heterogenized) and the results were compared. The selectivity of the desired products was always > 99% with the immobilized catalyst with both aq.H2O2 and TBHP. However, while the leaching was negligible in the non-aqueous medium, the aqueous medium leads to considerable leaching. The immobilized catalysts could be separated after the reaction and the reusability of the catalyst has also been demonstrated especially with oxidant in the nonaqueous medium.
4th International Symposium on Nanoporous Materials, Niagara Falls, CANADA, JUN 07-10, 2005

In situ polymerization of ethylene with bis(imino)pyridine iron(II) catalysts supported on clay: the synthesis and characterization of polyethylene-clay nanocomposites - Ray, S; Galgali, G; Lele, Arundhati C.; Sivaram, S (Journal of Polymer Science Part A-Polymer Chemistry, 2005)
Polyethylene-clay nanocomposites were synthesized by in situ polymerization with 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl] pyridine iron(II) dichloride supported on a modified montmorillonite clay pretreated with methylaluminoxane (MAO). The catalysts and the obtained nanocomposites were examined with wide-angle X-ray scattering. The exfoliation of the clay was further established by transmission electron microscopy. Upon the treatment of the clay with MAO, there was an increase in the d-spacing of the clay galleries. No further increase in the d-spacing of the galleries was observed with the iron catalyst supported on the MAO-treated clay. The catalyst activity for ethylene polymerization was independent of the Al/Fe ratio. The exfoliation of the clay inside the polymer matrix depended on various parameters, such as the clay content, catalyst content, and Al/Fe ratio. The crystallinity percentage and crystallite size of the nanocomposites were affected by the degree of exfoliation of the clay. Moreover, when ethylene was polymerized with a mixture of the homogeneous iron(II) catalyst and clay, the degree of exfoliation was significantly lower than when the polymerization was performed with a preformed clay-supported catalyst. This observation suggested that in the supported catalyst, at least some of the active centers resided within the galleries of the clay. (C) 2004 Wiley Periodicals, Inc.
Keywords: clay; In situ polymerization; Nanocomposites; polyethylene (PE); TEM; WAXS

IndCollections: biological specimens in Indian collections - Chavan, V.; Rane, N. S.; Ghate, H. V.; Krishnan, S. (Current Science, 2005)

India: apremier destination for outsourcing - Chorghade, Mukund S.; Chorghade, V. M.; Gurjar, Mukund K.; Ramana, Chepuri V.; Kamerkar, A. V.; Zafran, H.; Mashelkar, Raghunath Anant (Speciality Chemicals Magazine, 2005)

Influence of alkali metal doping on selectivity behaviour of platinum catalysts for hydrogenation of 2-butyne-1,4-diol - Telkar, M. M.; Rode, C. V.; Rane, V. H.; Chaudhari, R. (Catalysis Communications, 2005)
Hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol (B(2)D) and butane-1,4-diol (B(1)D) using Pt catalysts doped with alkali metals was studied. These catalysts showed higher selectivity to the olefinic diol (B2D) compared to that with monometallic platinum catalyst. Among various alkali metals, Cs-doped catalyst showed highest selectivity (>99%) to B(2)D. The selectivity to B(2)D increased (up to 99.9%) with increase in the concentration of Cs from 0.25% to 1%. The increase in the basic strength of alkali doped catalysts measured by CO(2)-TPD, would be responsible for the increase in electron density of Pt hence, faster desorption and higher selectivity to the intermediate olefinic diol (B(2)D). The reaction parameters; such as temperature, H(2) pressure and substrate concentration haye strong influence on the catalyst activity but almost no effect on the selectivity to B(2)D. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: 2-butene-1; 2-butyne-1; 4-diol; alkali metal doping; platinum catalysts; Selective hydrogenation

Influence of Sn- and Al- metal sources on post-synthesis modification of mesoporous SBA-15 molecular sieves - Shah, P; Ramaswamy, AV; Ramaswamy, V (3rd Conference of the Federation-of-European-Zeolite-Association, 2005)
Mesoporous silica SBA-15 has been incorporated with various amounts of Sn and Al by post synthesis grafting technique, which results in excellent structural integrity and enhanced acidity. Physico-chemical characterization was done by various spectroscopic methods to understand the chemical nature of incorporated Sn and Al. XRD and BET results show that the hexagonal structural of the SBA-15 is maintained during the grafting with no loss of long range structure ordering. (119)Sn NMR Spectrum shows the presence of Sri in essentially octahedral environment, while 27 Al MAS NMR results confirm that a large proportion of the Al is in tetrahedral position. The resulting Sn and Al-grafted materials possess considerable catalytic activity in the transesterification of diethylmalonate (medium acidity) and isopropylation of naphthalene (strong acid sites), respectively.
3rd Conference of the Federation-of-European-Zeolite-Association, Prague, CZECH REPUBLIC, AUG 23-29, 2005

Integrated fuel cell processor for a 5-kW proton-exchange membrane fuel cell - Ratnamala, G. M.; Shah, N.; Mehta, V.; Rao, P. V.; Devotta, S. (Industrial & Engineering Chemistry Research, 2005)
A fuel processor is a combination of a few reactors to generate hydrogen required for a fuel cell. The study deals with the production of hydrogen suitable for a 5-kW proton-exchange membrane fuel cell (PEMFC) for household applications using liquefied petroleum gas (LPG) as the fuel. The aim is to energy integrate the five reactors in a fuel processor, i.e., desulfurizer, steam reformer, high-temperature shift reactor, low-temperature shift reactor, preferential oxidation reactor, and various heat exchangers. Heat-exchanger network synthesis analysis has been carried out for the entire process to make the process efficient. The results obtained from the studies show that the steam reforming with LPG gives a higher concentration of hydrogen in the product of about 74%. The fuel cell efficiency is around 34%, and the thermal efficiency including lean gas is about 93%. The model developed can serve as the basis for the development of an integrated PEMFC decentralized power pack for household applications.

Kinetic modeling of reductive alkylation of aniline with acetone using Pd/Al2O3 catalyst in a batch slurry reactor - Roy, D.; Jaganathan, Rengaswamy; Chaudhari, Raghunath V. (Industrial & Engineering Chemistry Research, 2005)
The kinetics of reductive alkylation of aniline with acetone was studied in a slurry reactor under isothermal conditions in a temperature range of 378-408 K using 3% Pd/Al2O3 catalyst. Experimental data on concentration-time as well as hydrogen consumption-time profiles were obtained to study the effect of concentration of aniline, catalyst loading, and partial pressure of hydrogen. Separate controlled experiments were performed to understand the nature of the condensation reaction between aniline and acetone, which forms the Shiff's base intermediate. From the concentration-time profiles and the effect of reaction conditions, it was found that the noncatalytic equilibrium formation of the Shiff base intermediate was the slowest step in the multistep reaction sequence. Several rate equations were considered to fit the batch slurry reactor data, and rate models based on competitive dissociative adsorption of hydrogen and the reactive substrates in the rate-limiting catalytic steps were found to represent the experimental data. The kinetic parameters were evaluated by fitting the integral batch reactor data at different temperatures. The activation energies, heat of adsorption, and entropy of adsorption of all the reactant species were also evaluated.

Layered inorganic-organic clay-like nanocomposites rearrange to form silsesquioxanes on acid treatment - Kumaraswamy, Guruswamy; Deshmukh, Yogesh S.; Agrawal, Vikrant V.; Rajmohanan, P. (Journal Physical Chemistry B, 2005)
The formation of talc-like compounds by the condensation of organotrialkoxy silanes with magnesium hydroxide has been recently reported. These represent layered hybrid nanomaterials that have a layer thickness of around 1 nm, have organic moieties covalently linked to the layer surfaces, and are called ``organoclays.'' We show that such compounds are sensitive to acid treatment. When a phenylclay is treated with hydrochloric acid, magnesium leaches out, destroying the layered structure. The extent to which magnesium is leached out is a function of the time of the acid treatment and the concentration of the acid used. Magnesium leaches out rapidly when the concentration of acid used to treat the phenyl-clay is higher, and the extent of structural magnesium that is leached out is also higher for higher acid concentrations. Removal of the magnesium rearranges the structure of the phenyl-clay to form oligomeric phenylsilsesquioxanes. FTIR and NMR suggest that the silsesquioxanes formed by acid treatment of the phenyl-clay comprise a mixture of ladderlike and cagelike structures.

Low temperature synthesis of MgTa2O6 powders - Navale, SC; Samuel, V; Ravi, V (Materials Letters, 2005)
A combination of digestion and further low temperature calcination to crystallize the product is employed to prepare MgTa2O6 (MT) ceramics. Freshly prepared niobium hydroxide gel is mixed with magnesium hydroxide thoroughly and allowed to react at 100 degrees C under refluxing and stirring conditions for 6-12 h. The X-ray amorphous product so formed is heated at 550 degrees C to form crystalline MgTa2O6. This is the lowest temperature so far reported for the formation of MgTa2O6. For comparison, MT powders were also prepared by the traditional solid state method. Transmission electron microscope (TEM) investigations revealed that the average particle size is 40 nm for the low temperature calcined powders. (C) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Electron microscopy; magnesium tantalate; Oxides; X-ray diffraction

Main chain thermotropic liquid crystalline polyurethanes containing biphenyl mesogens based on novel AB-type self-polycondensation route: FT-IR and XRD studies - Ranganathan, T.; Gowd, E. B.; Ramesh, C.; Kumar, Anil (Journal of Polymer Science Part A-Polymer Chemistry, 2005)
The detailed mesophasic characterization of main chain liquid crystalline polyurethanes containing biphenyl mesogen, which were synthesized by the novel AB-type self-polycondensation approach, was carried out by using Differential Scanning Calorimetry (DSC), Polarized Optical Microscopy (POM), variable temperature X-ray Diffraction (XRD), and Fourier Transform Infrared (FT-IR) spectroscopic studies. The type of mesophase present in these polymers was identified to be the smectic A phase by POM and XRD studies. The smectic layer thickness was found to increase as the length of the spacer increased. The effect of temperature on the hydrogen bonding was analyzed by FT-IR studies. The curve-fitting analysis of the NH stretching and C=O stretching modes of vibrations indicated a gradual decrease in hydrogen bonding during the transition from the crystalline state to the mesophase. The mesophase to isotropic liquid transition was then accompanied by the complete disappearance of the hydrogen bonding. The biphenyl bands also showed changes during phase transitions due to the coupling of biphenyl vibration modes with the urethane linkage attached to it. (c) 2005 Wiley Periodicals, Inc.
Keywords: FT-IR; liquid-crystalline polymers; polyurethanes; XRD studies

Matched asymptotic solution for flow in a semi-hyperbolic die - Subramanian, G; Ranade, V; Nagarkar, S; Lele, Arundhati C. (Chemical Engineering Science, 2005)
A semi-hyperbolic converging geometry finds application as an inexpensive elongation rheometer under certain flow conditions. We provide a matched asymptotic solution for the flow of a Newtonian fluid under no-slip boundary conditions. The predicted velocity and pressure profiles agree nearly quantitatively with CFD simulated values. Our theoretical approach has certain advantages over the known similarity solution proposed by James (1991. A.I.Ch.E. Journal 37, 59-64). (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: elongation viscosity; matched asymptotic solution; semi-hyperbolic

Mild and efficient method for the synthesis of vinylogous carbamates from alkyl azides - Reddy, D. Srinivasa; Rajale, T. V.; Shivakumar, K.; Iqbal, Javed (Tetrahedron Letters, 2005)
A mild and efficient one-pot method for the synthesis of vinylogous carbamates is reported starting from alkyl azides under a hydrogen atmosphere using 10% Pd/C. The resulting products are useful intermediates for the synthesis of heterocyclic compounds, natural products, and in peptidomimetics. (C) 2004 Elsevier Ltd. All rights reserved.

Modeling of rotary desiccant wheels - Harshe, Yogesh M.; Utikar, R. P.; Ranade, V. V.; Pahwa, D. (Chemical Engineering & Technology, 2005)
Rotary desiccant wheels are widely used in dehumidification and energy recovery applications. In this work, we have developed a 2D, steady state model of a rotary desiccant wheel. Mass and energy balance equations for the air streams and the desiccant wheels were developed. The hydraulic diameter and surface area for heat and mass transfer were calculated based on knowledge of the flute geometry. Appropriate correlations for the Sherwood number and Nusselt number were used to estimate heat and mass transfer coefficients. The model is capable of predicting steady state behavior of desiccant wheels having at the most three sections (process, purge, and regeneration). The mathematical model was validated using a real desiccant wheel, and the calculation results are in reasonable agreement with the experimental data. Based on this model, the temperature and humidity profiles in the wheel during both the dehumidification and the regeneration processes are analyzed. The simulated results were used to gain an insight into the operation of desiccant wheels. The model and the presented results will be useful for optimizing dehumidification and energy recovery applications.
Joint 5th International Symposium on Catalysis in Multiphase Reactors/4th International Symposium on Multifunctional Reactors, Portoroz-Portorose, SLOVENIA, JUN 15-18, 2005
Keywords: 1; 4-benzodioxan-2-carboxylate; 4-benzodioxan-2-carboxylic acid; doxazosin; enantio selectivity; enantiomeric ratio; ethyl 1; ethyl acetate; Lipases; transesterfication

Modeling of vaporization and cracking of liquid oil injected in a gas-solid riser - Nayak, S. V.; Joshi, S. L.; Ranade, V. V. (Chemical Engineering Science, 2005)
Vaporization and cracking of liquid oil injected in a gas-solid riser (fluid catalytic cracking riser reactor) was computationally studied in this work. Evaporation of a single drop injected in a stream of gas-solid mixture was analyzed first. A model for simulating evaporation of a drop considering heat transfer from the gas phase as well as from the solid particles was developed. The model relates the evaporation rate of droplet with rate of collisions of solid particles, specific heat capacities of solid and liquid, latent heat of vaporization, relative velocity of gas and liquid and temperatures of three phases. The understanding gained from such a model was then extended to simulate evaporation of liquid drops injected in FCC risers. The Eulerian-Lagrangian approach was used to simulate simultaneous evaporation and cracking reactions occurring in FCC riser reactors. A commercial CFD code, FLUENT (of Fluent Inc., USA) was used. Four and ten lump models were used for simulating cracking reactions. Appropriate user defined functions were developed to implement heterogeneous kinetics and heat transfer models in FLUENT. A special algorithm was developed to calculate accumulated coke on catalyst particles. A boiling point range was considered for simulating realistic oil feedstock. The model was first evaluated by comparing predicted results with published industrial data. The simulations were then carried out to understand influence of key design and operating parameters on performance of FCC riser reactors. The parameters studied included; initial oil droplet distribution, catalyst inlet temperature, catalyst to oil ratio and thermal cracking. The approach, model and results presented here would be useful for optimization of FCC operation, cost to benefit analysis of new FCC nozzles and related decision-making. (c) 2005 Elsevier Ltd. All rights reserved.
7th International Conference on Gas-Liquid and Gas-Liquid-Solid, Strasbourg, FRANCE, FEB, 2005
Keywords: cracking reactions; Evaporation; FCC; heat transfer; riser

Modular synthesis of cyclic peptidomimetics inspired by gamma-turns - Ramanathan, S. K.; Keeler, J.; Lee, H. L.; Reddy, D. Srinavasa; Lushington, G.; Aube, J. (Organic Letters, 2005)
A series of peptidomimetics based on a gamma-turn motif were synthesized using a modular approach, in which N-protected piperidones were reacted with a selection of 2-hydroxyalkyl azides derived from common L-amino acids. Hydrolysis of the initially formed iminium ethers afforded the targeted series of substituted 1,4-diazepin-5-ones.

Molecular mapping of stem and leaf rust resistance in wheat - Khan, R. R.; Bariana, Harbans S.; Dholakia, Bhushan B.; Naik, S. V.; Lagu, Meena D.; Rathjen, A. J.; Bhavani, Sridhar; Gupta, V. S. (Theoretical and Applied Genetics, 2005)
Stem rust caused by Puccinia graminis f. sp. tritici Eriks and Henn and leaf rust caused by Puccinia triticina Rob. ex Desm. are major constraints to wheat production worldwide. In the present study, F-4-derived SSD population, developed from a cross between Australian cultivars `Schomburgk' and `Yarralinka', was used to identify molecular markers linked to rust resistance genes Lr3a and Sr22. A total of 1,330 RAPD and 100 ISSR primers and 33 SSR primer pairs selected on the basis of chromosomal locations of these genes were used. The ISSR marker UBC 840(540) was found to be linked with Lr3a in repulsion at a distance of 6.0 cM. Markers cfa2019 and cfa2123 flanked Sr22 at a distance of 5.9 cM (distal) and 6.0 cM (proximal), respectively. The use of these markers in combination would predict the presence or absence of Sr22 in breeding populations. A previously identified PCR-based diagnostic marker STS638 linked to Lr20 was validated in this population. This marker showed a recombination value of 7.1 cM with Lr20.

Morphological consequences of interchange reactions during solid state copolymerization in poly(ethylene terephthalate) and polycarbonate oligomers - Gowd, EB; Ramesh, C (Polymer, 2005)
Poly(ethylene terephthalate) (PET) (IV:0.15dL/g) oligomer was obtained by depolymerisation of high molecular weight PET. Polycarbonate (PC) oligomer (IV: 0. 15 dL/g) was synthesized by standard melt polymerization procedure using bisphenol A and diphenyl carbonate in the presence of a basic catalyst. Blends of varying compositions were prepared by melt blending the chemically distinct PET and PC oligomers. The copolymer, poly(ethylene terephthalate-co-bisphenol A carbonate) was synthesized by simultaneous solid state polymerization and ester-carbonate interchange reaction between the oligomers of PET and PC. The reaction was carried out under reduced pressure at temperatures below the melting temperature of the blend samples. DSC and WAXS techniques characterized the structure and morphology of the blends, while (NMR)-N-1 spectroscopy was used to monitor the progress of interchange reactions between the oligomers. The studies have indicated the amorphisation of the PET and PC crystalline phases in solid state with the progress of solid-state polymerization and interchange reaction. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: amorphization; poly(ethylene terephthalate); Polycarbonate

Nature of manganese species in Ce1-xMnxO2-delta solid solutions synthesized by the solution combustion route - Murugan, B.; Ramaswamy, A. V.; Srinivas, D.; Gopinath, Chinnakonda S.; Ramaswamy, V. (Chemistry of Materials, 2005)
A series of manganese-cerium oxide composites with Mn concentrations in the range of 1-20 mol % in ceria was prepared by the solution combustion technique using urea as fuel. The nature, type, and oxidation state of Mn species in ceria were investigated by X-ray diffraction (XRD), diffuse reflectance UV-visible spectroscopy, electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy, and temperature-programmed reduction techniques. The study reveals that the method of preparation significantly influences the type of manganese species in ceria. Wet-impregnation, coprecipitation, and solid-state synthesis techniques lead to clustered MnOx-like species in the ceria matrix, while the present method of preparation (solution combustion route) yields a highly dispersed form of Mn species. In the reported series of samples, Mn is present mainly in +2 and +3 oxidation states and there is no evidence for the presence of Mn 41 species. Powder X-ray diffraction studies at variable temperatures (298-1323 K) indicate the formation of Ce1-xMnxO2-delta Solid solutions. No separate MnOx-type phase was detected even at 1323 K. EPR studies reveal that the isolated Mn2+ and Mn2+ species are present in at least three different structural locations: species A, Mn ions in ceria-lattice defect sites; species B, Mn ions in framework Ce4+ locations; and species C, Mn ions in interstitial locations and at the surface of ceria. The Mn3+ ions in ceria exhibit a facile reduction and reoxidation behavior when exposed to dry hydrogen and subsequently to air at elevated. temperatures. A highly dispersed state of Mn3+ and Mn2+ in ceria, facile redox behavior, and a synergistic Mn-ceria interaction are some of the unique properties of this material prepared by the solution combustion procedure.

New bis-andrographolide ether from androgphis paniculata nees and evaluation of anti-HIV activity - Reddy, V. L. N.; Reddy, S. M.; Ravikanth, V.; Krishnaiah, P.; Goud, T. V.; Rao, T. P.; Ram, T. S.; Gonnade, Rajesh G.; Bhadbhade, Mohan M.; Venkateswarlu, Y (Natural Product Research, 2005)
Novel bis-andrographolide ether (1) and six known compounds andrographolide, 14-deoxy-11,12-didehydroandrographolide, andrograpanin, 14-deoxyandrographolide, (+/-)-5- hydroxy-7,8-dimethoxyflavanone, and 5-hydroxy-7,8-dimethoxyflavone have been isolated from the aerial parts of Andrographis paniculota and their structures were established by spectral data. All the isolates were tested for the anti-HIV and cytotoxic activity.
Keywords: Acanthaceae; Andrographis paniculata; anti-HIV; bis-andrographolide ether; Cytotoxic activity

Nitrogen ligands: The transition metal catalyzed reaction of aryl halides with olefins (Mizoroki-Heck), phenylboronic acid (Suzuki coupling) and Buchwald-Hartwig amination, new catalysts and effect of co-catalysts - Aryl halide activation - Part I - Iyer, S; Kulkarni, GM; Ramesh, C; Sattar, AK (Indian Journal of Chemistry Section B-Organic Chemistry including Medicinal Chemistry, 2005)
Nitrogen ligands are an excellent alternative for the traditional P-ligands in the Pd catalyzed Mizoroki-Fleck reaction, Suzuki coupling and Buchwald-Hartwig aryl amination. Pd complexes of dimethyl glyoxime, 8-hydroxyquinoline, salen, picolinic acid, and DAB ligands gave high yields of the E-cinnamates and E-stilbenes from aryl iodides. Acetophenone oxime N, N-dimethybenzylamine and ferrocenyl oxime palladacycle are better catalysts with comparable yields, high TON (95, 000) and TOF's (2, 500 h(-1)) to P-ligand catalysts. Aryl bromides and in a few cases, aryl chlorides could also be activated by these complexes by the use of Lewis acid and (C(4)H(9))(4)NI as additives. Cy-DAB ligands gave good yields with electron rich aryl bromides and the use of ionic liquid improve the yield. These N-ligand metal complexes can be readily synthesized and the ligands possess the advantage of easy functional group modifications and convenient synthetic methods compared to P-ligands. The degradation reactions associated with P-ligands are not observed in the N-ligands, with comparable, high thermal, moisture and air stability and insensitivity. Activation of aryl bromides (Mizoroki-Fleck reaction, Suzuki reaction) could be achieved in high yields, TON and TOF (86-94% yield, TON: 36, 000-90, 000, TOF:6, 000-11, 500 h-1) catalyzed by monomeric amine and oxime palladacycles (Cat-8, 11, 13 B) with a N-heterocyclic carbene ligand better than a phosphorous ligand. Molten (C(4)H(9))(4)NBr is an efficient ionic liquid medium for the Mizoroki-Fleck reaction of aryl bromides, giving higher yields. Low to moderate yields of aryl amination are obtained with the carbene pallaclacycle and N, N-dibenzyl piperazine Pd complexes.
Keywords: DAB; DMG; Mizoroki-Heck reaction; nitrogen ligands; Palladacycle

Novel, benign, solid catalysts for the oxidation of hydrocarbons - Ratnasamy, P; Raja, R; Srinivasi, D (Philosophical Transactions of the Royal Society A - Mathematical, Physical and Engineering Sciences, 2005)
The catalytic properties of two classes of solid catalysts for the oxidation of hydrocarbons in the liquid phase are discussed: (i) microporous solids, encapsulating transition metal complexes in their cavities and (ii) titanosilicate molecular sieves. Copper acetate dimers encapsulated in molecular sieves Y, AICM-22 and VPI-5 use dioxygen to regioselectively ortho-hydroxylate L-tyrosine to L-dopa, phenol to catechol and cresols to the corresponding o-dihydroxy and o-quinone compounds. Monomeric copper phthalocyanine and salen complexes entrapped in zeolite-Y oxidize methane to methanol, toluene to cresols, naphthalene to naphthols, xylene to xylenols and phenol to diphenols. Trimeric mu(3)-oxo-bridged Co/Mn cluster complexes, encapsulated inside Y-zeolite, oxidize para-xylene, almost quantitatively, to terephthalic acid. In almost all cases, the intrinsic catalytic activity (turnover frequency) of the metal complex is enhanced very significantly, upon encapsulation in the porous solids. Spectroscopic and electrochemical studies suggest that the geometric distortions of the complex on encapsulation change the electron density at the metal ion site and its redox behaviour, thereby influencing its catalytic activity and selectivity in oxidation reactions. Titanosilieate molecular sieves can oxidize hydrocarbons using dioxygen when loaded with transition metals like Pd, An or Ag. The structure of surface Ti ions and the type of oxo-Ti species generated on contact with oxidants depend on several factors including the method of zeolite synthesis, zeolite structure, solvent, temperature and oxidant. Although, similar oxo-Ti species are present on all the titanosilicates, their relative concentrations vary among different structures and determine the product selectivity.
Keywords: benign catalytic oxidations; encapsulated metal complexes; Solid catalysts; titanosilicate molecular sieves

Novel method for the synthesis of siloxane nanowires and filaments using gold nanoparticle catalysts - Bhagavatula L. V. Prasad; Stoeva, S.; Sorensen, C. M.; Klabunde, Kenneth J.; Zaikovskii, V. (International Conference on Nanoscience and Technology, 2005)
A unique polymerization reaction of alkylsilanes to siloxane nanowires, filaments and tubes in presence of gold nanoparticles and water is presented. The gold nanoparticles, which catalyze this reaction also work as templates restricting the shape of the resulting polymers into wires and tubes. High resolution transmission electron microscopy images clearly reveal the presence of gold nanoparticle at the tip of each wire supporting the template hypothesis. Elemental analyses by different methods confirm the stoichiometry to be C18H37SiO1.5, when the alkylsilane used was C18H37SiH3, thus proving that the alkyl group remains intact during the polymerization reaction.
International Conference on Nanoscience and Technology, Calcutta, INDIA, DEC 17-20, 2003
Keywords: gold nanoparticles; Nanowires; siloxane polymers

Novel polymer-inorganic solid-state reaction for the synthesis of CdS nanocrystallites - Kanade, K. G.; Hawaldar, Ranjit R.; Pasricha, R.; Radhakrishnan, S.; Seth, T.; Mulik, Uttam P.; Kale, B. B.; Amalnerkar, Dinesh P. (Materials Letters, 2005)
We offer a novel polymer-inorganic solid-state reaction route for the in situ generation of nanochalcogenide semiconductor in the network of polymer which itself acts as a chalcogen source. We have exemplified feasibility of this route by reacting CdI2 with engineering thermoplastic polyphenylene sulphide (PPS). These two reactants in 1:1 and 10:1 molar ratios were simply heated at the crystalline melting temperature of PPS. The resultant products were characterized by X-ray diffractometry, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM, with selected area electron diffraction). The prima facie observations revealed the formation of cubic nanocrystallites of US with the particle size ranging from 6 to 20 nm entrapped in modified (cyclized) PPS matrix when the reactants were taken in 10:1 molar ratio. A tentative mechanism has been suggested for such hitherto unattempted solid-state reaction. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: CdS nanocrystallites; Semiconductor; solid-state reaction; Thermoplastic polymer matrix

Optimization and scale up of production of alkaline protease from Conidiobolus coronatus - Laxman, Ryali Seeta; Sonawane, A. P.; More, Shivaji V.; Rao, B. S.; Rele, M. V.; Jogdand, Vitthal V.; Deshpande, V. V.; Rao, M. B. (Process Biochemistry, 2005)
Alkaline protease secreted by Conidiobolus coronatus has been evaluated extensively in tanneries and finds application in pre-tanning operations in leather manufacture. It is important to produce the enzyme in inexpensive and optimized media on large scale for the process to be commercially viable. The present paper describes optimization of fermentation conditions in shake flasks and scale up of production to 100 L in fermentors. The production is complete in 2-3 days comparable to bacterial fermentations. The organism utilized several carbon sources such as starch, sucrose, lactose, glucose and fructose for production. Soyabean meal at an optimum concentration of 2-3% was found to be best inducer. Diammonium hydrogen phosphate, casamino acids and Hi-media peptone gave activities comparable to yeast extract. Preservation and stabilization studies showed that glycerol conferred considerable stabilization at room temperature while ammonium sulphate precipitated enzyme at 0.9 saturation was best with stability up to 2 years even at room temperature. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: Alkaline Protease; Conidiobolus; Fermentation; Optimization; scale up

Overview on the degradability of polymer nanocomposites - Pandey, JK; Reddy, KR; Kumar, AP; Singh, RP (Polymer Degradation and Stability, 2005)
Polymer nanocomposites have attracted great attention world wide from both academic and industrial points of view. The material properties of polymers can be enhanced dramatically by incorporating layered silicates at fairly low concentrations. The durability of any material depends upon several factors e.g. light, heat, microwaves, mechanical abrasion etc. The study and the effect of these factors on the performance are essentially required to extend the application limits. The durability of polymer nanocomposites has been evaluated under different environments. The present review describes the durability of different polymer nanocomposites mainly under thermal- and photoageing. Biodegradable nanoeomposites of different polymers are also discussed briefly. (c) 2004 Elsevier Ltd. All rights reserved.
Keywords: Biodegradation; Degradation; layered silicates; Nanocomposites; weathering

Oxidation of norbornene over vanadium-substituted phosphomolybdic acid catalysts and spectroscopic investigations - Raj, N. K. K.; Ramaswamy, A.; Manikandan, Palanichamy (Journal of Molecular Catalysis A-Chemical, 2005)
Oxidation of norbornene has been carried out over mono-, di- and tri-vanadium-substituted phosphomolybdic acid catalysts with aqueous hydrogen peroxide (aq. H2O2) as an oxidant in different solvents. Monovanadium-substituted phosphomolybdic acid catalyst was found to be better than other catalysts for the above reaction and acetonitrile was the suitable solvent. At the optimum temperature of 60 degreesC, the norbornene conversion was 70% and the selectivity for 2,3-epoxy norbornane was 58%. The side products were norborneols and 2-norbornanone. The lower selectivity of 2,3-epoxy norbornane with aq. H2O2 is attributed to the simultaneous formation of other products, norborneols and 2-norbornanone. The norborneols are formed from norbornene by acid-catalyzed reaction. Other oxidants like urea-hydrogen peroxide adduct (UHP) and tert-butyl hydrogen peroxide (TBHP) were also tested for norbornene oxidation reaction. With UHP, the conversion was almost same (69%) as that of aq. H2O2 reaction; however, 2,3-epoxy norbornane was the main product with >97% selectivity. Thus, the overall yield was 66.9% at 60 degreesC after 4 h. The high selectivity with UHP is attributed to the controlled release of H2O2, absence of water and less acidic nature of UHP. With TBHP the selectivity for the epoxide was >96%; however, the conversion was low (27%). A mechanism for the norbornene oxidation is believed to be proceeding via V(5+)-peroxo and V(4+)-superoxo intermediates. NMR, EPR and UV-vis spectroscopic techniques were employed to understand the reaction intermediates and reaction pathways. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: 2; 3-epoxy norbornane; aq. H2O2; epoxidation; EPR; NMR; norbornene; urea-H2O2 adduct; UV-Vis; vanadium-substituted phosphomolybdic acid

Oxidative dehydrogenation of ethylbenzene over vanadia-alumina catalysts in the presence of nitrous oxide: structure-activity relationship - Shiju, N. R.; Anilkumar, Mettu; Mirajkar, Subhash P.; Gopinath, Chinnakonda S.; Rao, B. S.; Satyanarayana, C. V. (Journal of Catalysis, 2005)
A series of vanadia-alumina catalysts with different vanadia contents were prepared by a wet impregnation method. The influence of the local structure of vanadia in these catalysts on the oxidative dehydrogenation of ethylbenzene with nitrous oxide was investigated. The use of N2O as a co-feed remarkably enhanced the styrene yield compared with the use of N-2. Characterization of these vanadia catalysts by XRD, FTIR, UV-vis, TPR, XPS, and V-51 NMR techniques suggests that the nature of the VOx species depends on the vanadia loading: the predominant species are monomeric vanadia at lower loadings, two-dimensional polyvanadates at intermediate loadings, and bulk-like V2O5 and AlVO4 at higher loadings. The rate of oxidative dehydrogenation (ODH) of ethylbenzene per vanadium atom increases with vanadia loading and reaches a maximum at 10 wt%, the loading at which the surface predominantly contains polyvanadate species. The observed variation in the selectivity of products with vanadium loading indicates that the monomeric V5+ species favors dehydrogenation, whereas bulk-like V2O5 preferentially participates in the dealkylation of ethylbenzene. The vanadium species remains at a higher oxidation state in the presence of N2O, leading to a higher styrene yield. than in a N-2 atmosphere. The ODH turnover rates increased with decreasing energy of the absorption edge in the UV-vis spectrum, at low VOx coverages of less than one monolayer on the Al2O3 surface. (c) 2005 Elsevier Inc. All rights reserved.
Keywords: absorption edge energy; Alumina; ethylbenzene; Nitrous oxide; oxidative dehydrogenation; polyvanadates; styrene; vanadia

Partial ring hydrogenation of naphthols over supported metal catalysts in supercritical carbon dioxide solvent - Mine, Eiichi; Haryu, E.; Arai, K.; Sato, T.; Sato, O.; Sasaki, A.; Rode, C. V.; Shirai, M. (Chemistry Letters, 2005)
Selective ring hydrogenation of naphthols to tetrahydronaphthols and tetralones proceeded at 323 K over a charcoal supported rhodium catalyst in supercritical carbon dioxide.

Phase transitions in octanethiol-capped Ag nanocluster microfilm assemblies - Ellis, A.; D'Arcy-Galla, J.; Vijayamohanan, K.; Goswami, R.; Ganesan, P. G.; Ryu, C.; Ramanath, G. (Thermochimica Acta, 2005)
We describe phase transitions in microfilm assemblies of octanethiol (OT)-capped 2-4 nm-diameter Ag nanoclusters prepared from solutions with OT/Ag+ ratios of similar to50. Using DSC we observe two melting/crystallization-type reversible phase transitions: one at similar to61 degreesC due to interdigiated unattached octanethiol, and the other at similar to125 degreesC due to the phase comprised of the assembly of OT-capped nanoclusters. Increased thermal fluctuations weaken the inter-chain hydrophobic interactions between interdigitated OT molecules, leading to both phase transitions. The thiolate bond of OT-molecules bound to Ag nanoclusters are more rigid, thereby requiring a higher temperature to increase the flexibility of the alkyl chain of OT, and to melt the nanocluster assembly. The mobility of the nanoclusters in the melt is limited, and morphological features of the original assemblies are retained during recrystallization. No observable mass loss is detected up to similar to180 degreesC, above which OT molecules desorb from the Ag nanoclusters. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: differential thermal analysis; infrared spectroscopy; phase transitions; silver nanoclusters

PHB synthase from Streptomyces aureofaciens NRRL 2209 - Ramachander, TVN; Rawal, SK (FEMS Microbiology Letters, 2005)
An similar to4.9 kb Sau3A I genomic DNA fragment from the Streptomyces aureofaciens NRRL 2209 aiding in the biosynthesis of PHB in recombinant Escherichia coli has been sequenced and analysed for phaC gene. The putative phaC(sa) gene of 2 kb is 79.1% GC rich and encodes a 63.5 kDa protein. It expressed under its own promoter and significant PHA synthase activity was detected in the recombinant E coli. This is the first putative PHA synthase gene reported from a Streptomyces sp. with serine as the active nucleophile in the conserved lipase box. The phaC(sa) was found in close proximity to a regulatory gene, which apparently regulated the phaC expression. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
Keywords: PHA synthase; PHB; Streptomyces

Photodegradation of ethylene/propylene/polar monomers co- and terpolymers. I - Prepared by group 4 catalyst systems - Fernandes, Susete N.; Correia, Sandra; Prasad, A. V.; Reddy, K. R.; Rana, S.; Lonkar, Sunil P.; Marques, Maria M.; Singh, R. P. (Journal of Macromolecular Science-Pure and Applied Chemistry, 2005)
The photooxidative degradation behavior of polyethylene, its copolymers (propylene/polar monomers) and terpolymers, synthesized by a group 4 catalyst system, has been studied by Fourier transform infrared spectroscopy and confirmed with scanning elecrton microscopy for morphological changes. The kinetics of photodegradation has also been studied. Surface damage caused by polychromatic (>= 290 nm) at 55 degrees C in air is presented in different micrographs. The rate of photodegradation is very fast in terpolymers containing polar monomers as compared with copolymers and polyethylene. Morphological study of these photodegraded samples showed a very good relation with photodegradation results.
Keywords: functional polyolefins; Photodegradation; UV irradiation

Preparation and characterization of a copper based Indian traditional drug: tamra bhasma - Wadekar, M. P.; Rode, C. V.; Bendale, Y. N.; Patil, K. R.; Prabhune, Asmita (Journal of Pharmaceutical and Biomedical Analysis, 2005)
The copper based Indian traditional drug `tamra bhasma' is administered for various ailments since long. Its synthesis involves treating metallic copper with plant juices and then repeated calcination in presence of air so that the metallic state is transformed into the corresponding oxide form traditionally known as `bhasma'. In this work, we present a systematic characterization of this traditional drug using various techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM)-energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), thermogravimetry (TG) and surface area measurement. The results obtained were found to match very well with those of a standard copper oxide confirming the composition of the drug sample. In addition, some specific findings were also made which could help in interpreting the therapeutic properties of the traditional drug `tamra bhasma'. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: copper oxide; crystallite size; tamra bhasma; traditional medicine; XPS of copper oxide; XRD

Preparation of ferroelectric BaNb2O6 the urea method - Dhage, S. R.; Pasricha, R.; Ravi, V. (Materials Letters, 2005)
A precipitate was formed when an aqueous solution of BaCl2, NbF5 and urea in required ratio (the ratio of total metal cations to the urea is five) is heated on a water bath at 100 degrees C. This precipitate on decomposition at 600 degrees C yielded the nanocrystallites of BaNb2O6 (BN), as confirmed by X-ray diffraction study (XRD). This is a much lower temperature as compared to that prepared by traditional solid state method (1000 degrees C) as reported for the formation of BaNb2O6. Transmission electron microscope (TEM) investigations revealed that the average particle size is 85 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 900. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Chemical synthesis; electronic material; ferroelectricity; Oxides

Preparation of fine MgTa2O6 and Mg4Ta2O9 powders by chemical methods - Navale, SC; Ravi, V (Materials Science and Engineering B-Solid State Materials for Advanced Technology, 2005)
Two different chemical methods are applied to prepare MgTa2O6 (MT2) and Mg4Ta2O9 (M4T2) powders. A gel was formed when a aqueous solution of Mg(NO3)(2), TAF(5) and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 750 degrees C produced the fine crystallites of ternary oxide, M4T2. A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase MT2. Ammonium hydroxide was used to precipitate Mg2+ and Ta5+ cations as hydroxides simultaneously. This precursor on heating at 750 degrees produces MT2 powders. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron microscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Electron microscopy; powders-chemical preparation; X-ray methods

Preparation of nanocrystalline ferroelectric BaNb(2)O6 by citrate gel method - Gaikwad, S. P.; Samuel, V; Pasricha, R; Ravi, V (Bulletin of Materials Science, 2005)
A gel was formed when a aqueous solution of BaCl2, NbF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 600 degrees C yielded the nano crystallites of BaNb2O6, as confirmed by X-ray diffraction study (XRD). This is a much lower temperature as compared to that prepared by traditional solid state method (1000 degrees C) as reported for the formation of BaNb2O6. Transmission electron microscopic. (TEM) investigations revealed that the average particle size is 50 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 1000. The ferroelectric hysteresis loop parameters of these samples were also studied.
Keywords: Ceramics; Chemical synthesis; electronic material; ferroelectricity; Oxides

Preparation of nanocrystalline ferroelectric CaBi2Ta2O9 by the urea method - Gaikwad, S. P.; Pasricha, R; Ravi, V (Ceramics International, 2005)
A precipitate was formed when a aqueous solution of CaCl2, BiCl3, TaF5 and urea in stoichiometric ratio (total metal cations to urea ratio is 5) is heated on a water bath. This precipitate on decomposition at 600 degrees C yielded the nanocrystallites of ternary oxide CaBi2Ta2O9 (CBT) as confirmed by X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). Ferroelectric hysteresis loop parameters such as remnant polarization (P-r) and coercive field (E-C) were also determined. TEM investigations revealed that the average particle size of the polycrystalline powder is 70 nm. The room temperature dielectric constant was found to be 110. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Keywords: dielectric properties; Electron microscopy; ferroelectric properties; powders : chemical preparation

Preparation of nanocrystalline ferroelectric CaBi2TaO9 by citrate gel method - Gaikwad, S. P.; Pasricha, R; Ravi, V (Materials Science and Engineering B-Solid State Materials for Advanced Technology, 2005)
A gel was formed when an aqueous solution of CaCl2, BiCl3, TaF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 600degreesC yielded the nano-crystallites of ternary oxide, CaBi2Ta2O9 (CBT) as confirmed by X-ray diffraction study (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). Ferroelectric hysteresis loop parameters such as remnant polarization (P-r) and coercive field (E-C) are also determined. TEM investigations revealed that the average particle size of the polycrystalline powder is 40 nm. The room temperature dielectric constant was found to be 90. (C) 2004 Elsevier B.V All rights reserved.
Keywords: Bismuth; diffraction; Electron microscopy

Preparation of nanocrystalline LiNbO3 by citrate gel method - Navale, SC; Samuel, V; Ravi, V (Materials Letters, 2005)
A gel was formed when an aqueous solution of Li(NO3) NbF5 and citric acid in stoichiometric ratio is heated in a water bath at 100 degrees C. This gel on decomposition at 700 degrees C produced the fine crystallites of ternary oxide, LiNbO3 (LN). The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Electron microscopy; electronic materials; lithium niobate; X-ray diffraction

Preparation of nanocrystalline MgNb2O6 by citrate gel method - Pasricha, R; Ravi, V (Materials Letters, 2005)
A gel was formed when a aqueous solution of Mg(NO3)(2), NbF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 700 degrees C produced the fine crystallites of ternary oxide, MgNb2O6 (MN). The formation of MN phase and lattice parameters were determined by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Citrate gel; Electron microscopy; magnesium niobate; powders; X-ray diffraction

Preparation of ultrafine LiTaO3 powders by citrate gel method - Navale, SC; Samuel, V; Ravi, V (Bulletin of Materials Science, 2005)
A gel was formed when a aqueous solution of Li(NO3), TaF5 and citric acid in stoichiometric ratio was heated in a water bath. This gel on decomposition at 700 degrees C produced fine crystallites of ternary oxide, LiTaO3 (LT). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM).
Keywords: Ceramics; Electron microscopy; electronic materials; X-ray diffraction

Proceedings of the National Conference on Nanoscience and Technology - Part II - Foreword - Sood, AK; Ganesh, Krishna N.; Sundar, CS; Raychaudhuri, AK (Pramana-Journal of Physics, 2005)

Proceedings of the National Conference on Nanoscience and Technology Part I - National Chemical Laboratory - Pune - 7-8 March 2005 - Foreword - Sood, AK; Ganesh, Krishna N.; Sundar, CS; Raychaudhuri, AK (Pramana-Journal of Physics, 2005)

Purification and properties of a low molecular weight 1,4-beta-D-glucan glucohydrolase having one active site for carboxymethyl cellulose and xylan from an alkalothermophilic Thermomonospora sp - Jagtap, Sharmili; Rao, M (Biochemical and Biophysical Research Communications, 2005)
A low molecular weight 1,4-beta-D-glucan glucohydrolase from an extracellular culture filtrate of Thermomonospora sp. was purified to homogeneity. The molecular weight of the purified enzyme was 14.2 kDa by MALDI-TOF analysis and is in agreement with SDS-PAGE and gel filtration chromatography. The purified enzyme exhibited both endocarboxymethyl cellulase and endoxylanase activities. A kinetic method was employed to study the active site of the enzyme that hydrolyzes both carboxymethyl cellulose and xylan. The experimental data coincide well with the theoretical values calculated for the case of a single active site. Conformation and microenvironment at the active site was probed with fluorescent chemo-affinity labeling using o-phthalaidehyde as the chemical initiator. Formation of isoindole derivative resulted in complete inactivation of the enzyme to hydrolyze both xylan and CMC as judged by fluorescence studies corroborating a single active site for the hydrolysis of xylan and CMC. (C) 2005 Elsevier Inc. All rights reserved.
Keywords: Cellulase; CMC; OPTA; single active site; Thermomonospora sp.; xylan; Xylanase

R&D spending patterns of global firms - Bowonder, B.; Racherla, J. K.; Mastakar, N. V.; Krishnan, S. (Research-Technology Management, 2005)
R&D spending by the top 320 companies in 2004 was US\$ 331 billion. The R&D intensity of these globalfirms has decreased marginally, as there was a decrease in R&D spending by pharmaceutical firms. R&D spending as a percentage of sales is the highest in the biotechnology industry followed by pharmaceuticals and network communications. At the same time, more firms are seeking to acquire intellectual assets from external sources. Managing intellectual assets will require competence to integrate external and internal knowledge assets so that innovation efficiency can go up while idea-to-market time goes down and product pipelines get richer.
Keywords: distributed innovation; globalization; R&D spending

Recent applications of chloroaluminate ionic liquids in promoting organic reactions - Kumar, Anil; Sarma, Diganta (Symposium on Ionic Liquids - Fundamentals, Progress, Challenges and Opportunities held at the 226th American-Chemical-Society National Meeting, 2005)
Chloroaluminate ionic liquids composed of AICl(3) and organic cations can promote a variety of organic reactions. The composition of these chloroaluminate ionic liquids governs the acidity and basicity of solvent media, in which the reactions are carried out. Useful physico-chemical properties of these ionic liquids and the recent work on their role in accelerating organic reactions are described in the present article.
Symposium on Ionic Liquids - Fundamentals, Progress, Challenges and Opportunities held at the 226th American-Chemical-Society National Meeting, New York, NY, SEP 07-11, 2003

Response of trichogramma chilonis to infochemicals: an SEM and electrophysiological investigation - Sen, A; Raina, R; Joseph, Mary P.; Tungikar, VB (Biocontrol, 2005)
The external morphology and peripheral olfactory responses of antennal chemoreceptors of Trichogramma chilonis Ishii (Hymenoptera:Trichogrammatidae) to host related stimuli were examined by SEM and EAG technique respectively. The antennae of male and female T. chilonis reveal strong sexual dimorphism in structure as well as in types, density and distribution of individual sensillar types. The female antennae are characterized by the presence of a single uniporous sensilla on the apical tip of the dome and numerous multiporous pitted sensilla. Sensilla common to both males and females include the multiporous plate sensilla, the peg sensilla and trichoid sensilla. Differences between males and females occur with respect to their EAG profiles to 22 chemicals commonly found in plants viz., hexanal, β-pinene, citronellal, terpinene, citronellol, phytol, caryophyllene, R-(+)-limonene, linalool, carvacrol, cis-3-hexen-1-ol, ethanol, α-pinene, trans-2-hexanal, α-phellandrene, amyl acetate, cineole, quinolene, S-(-)limonene, β-myrcene, carvone, terpineol; hexane leaf extracts of three host plants of Helicoverpa armigera (cotton, chickpea and pigeon pea) and hexane scale extracts of adult males and females of H. armigera. Individually, the largest peak amplitudes in females were obtained with citronellal, phytol, caryophyllene, R-(+)-limonene, linalool, carvacrol and citronellol while in males citronellol, caryophyllene, linalool, R-(+)-limonene and amyl acetate caused the highest response. Among the different chemical classes, the largest peak amplitudes in females were obtained with oxygenated monoterpenes, while in males, fatty acid derivatives caused the highest response. In both males and females, the hydrocarbon monoterpenes caused the least response. Thus, the wide spectrum response of Trichogramma chilonis, to a wide group of chemicals belonging to different chemical classes, though varying, nevertheless suggests that using plant information enhances its parasitization efficiency.
Keywords: antennae; Chickpea; cotton; EAG; parasitoid; pigeon pea; scanning electron microscopy; Trichogramma chilonis; Volatiles

Ring-closing metathesis mediated total synthesis of microcarpalide and herbarumin III - Gurjar, M. K.; Nagaprasad, R.; Ramana, C. V.; Karmakar, S.; Mohapatra, Debendra K. (Arkivoc, 2005)
Total synthesis of naturally occurring microcarpalide and herbarumin III are described. The ring-closing metathesis (RCM) approach to coin the medium sized rings present in their molecular structures form the basic premise of this investigation.
Keywords: herbarumin III; microcarpalide; microfilament; phosphodiesterase; ring-closing metathesis (RCM)

Role of a co-metal in bimetallic Ni-Pt catalyst for hydrogenation of m-dinitrobenzene to m-phenylenediamine - Telkar, M. M.; Nadgeri, J. M.; Rode, C. V.; Chaudhari, R. (Applied Catalysis A-General, 2005)
Bimetallic Ni-Pt catalysts supported on carbon were found to give very high turn over frequency numbers and almost complete selectivity to m-phenylenediamine in m-dinitrobenzene hydrogenation as compared to the monometallic nickel catalysts. The XRD and XPS characterization revealed that most of the nickel remains as Ni2+ in a monometallic catalyst while, the addition of platinum leads to the stabilization of Ni-0 state, in case of bimetallic catalysts. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Bimetallic catalyst; Catalytic hydrogenation; m-dinitrobenzene; m-phenylenediamine; Selective hydrogenation; turn over number; XPS and XRD of nickel

Role of Mg ions in modulating the morphology and structure of CaCO3 crystals grown in aqueous foams - Rautaray, Debabrata; Kasture, Manasi; Sastry, M. (CrystEngComm, 2005)
We investigate the role of magnesium ions in modulating the morphology and crystallography of CaCO3 crystals grown in aqueous foam. This is accomplished by first making foams from an aqueous mixture of CaCl2+MgCl2 and the anionic surfactant aerosol-OT (AOT) followed by reaction of the foam with Na2CO3 solution. The Ca2+ and Mg2+ ions electrostatically complex with AOT and react with Na2CO3 within the foam to yield CaCO3 crystals of interesting morphology. These studies indicate that CaCO3 in a fractured, needle-like morphology was formed at high Mg2+ concentrations in the foam whereas porous, rhombic CaCO3 crystals were obtained at low Mg2+ concentrations. The effect of water drainage time and thereby, the structure of the foam on the morphology of the CaCO3 crystals grown was also studied.

Role of non-linear processes in conducting polymer blends for piezo-sensors Part 2: studies on polyaniline/SBS blends - Radhakrishnan, S; Kar, Swarnendu B. (Sensors and Actuators A-Physical, 2005)
The electrical properties and piezo-response of conducting polymer blends have been investigated with respect to composition for styrene-butadiene-styrene (SBS) elastomer containing two grades of polyaniline (PANI). The blends were synthesized using solution/dispersion technique in which the conducting PANI was prepared with either HCl or dodecyl benzene sulfonic acid (DBSA) as dopant. Thick sheets cast from these exhibited high piezo-sensitive electrical resistance even at small mechanical load. The pressure dependence of resistance followed a non-linear power law of the type R = KP-m where K and m values changed considerably with composition. The current voltage characteristics in these blends were found to be highly non-linear and the conduction mechanism was either space charge limited or tunneling type depending on the concentration and nature of conducting additive. These various results have been explained on the basis of the phenomenological model developed incorporating the non-linear processes for electrical and mechanical properties. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: conducting polymer; non-linear process; piezo-sensors

Room temperature nitric oxide sensor actualized from Ru-doped SnO2 nanowires - Ramgir, N. S.; Mulla, Imtiaz S.; Vijayamohanan, K. P. (Sensors and Actuators B - Chemical, 2005)
We report synthesis of the novel Ru-doped SnO2 nanowires and their distinctive response towards NO., and liquefied petroleum gas (LPG) in air. These nanowires have been prepared by a simple approach of evaporation of metal oxide at elevated temperature, The sensor exhibits three order of magnitude changes in the conductivity on exposure to NO2 in air at room temperature, Furthermore. Ru being one of the excellent sensitizers towards LPG these wires also exhibits sensitivity at 250&DEG; C. The amount of Ru plays a crucial role in modulating the sensitivity and lowering the operating temperature. © 2005 Elsevier B.V. All rights reserved.
Keywords: LPG; Nanowires; NO2; tin oxide ruthenium oxide

Simple procedure for the synthesis of gamma-hydroxy-alpha,beta-(E)-alkenoic esters: formal synthesis of (+)-macrosphelides A and B - Rao, K. Srinivasa; Mukkanti, K.; Reddy, D. Srinivasa; Pal, Manojit; Lqbal, Javed (Tetrahedron Letters, 2005)
A highly trans-selective conjugate reduction of 7-hydroxy-alpha,beta-alkynoic esters to produce gamma-hydroxy-alpha,beta-(E)-alkenoic esters using LiAlH4 is reported. The application of this methodology is demonstrated by a formal synthesis of the potent cell-cell adhesion inhibitors (+)-macrosphelides A and B. (c) 2005 Elsevier Ltd. All rights reserved.

Stereoselective synthesis of (2S,7S)-7-(4-phenoxymethyl)2-(1-N-hydroxyureidyl-3-butyn-4-yl)oxepane: a potential anti-asthmatic drug candidate - Gurjar, M. K.; Rao, B. V.; Krishna, L. M.; Chorghade, Mukund S.; Ley, S. V. (Tetrahedron-Asymmetry, 2005)
We have achieved a short, efficient stereoselective synthesis of 7-membered oxepane derivatives with potential against asthma. Highlights of our synthetic strategy are regioselective oxidation of a hydroxyl group and efficient ring closure of an open chain aldehyde to a 2-benzenesulfonyl oxepane derivative with PhSO2H. Surprisingly the cis-isomer showed better activity than the traps-isomer. (C) 2005 Elsevier Ltd. All rights reserved.

Structural rationalisation of co-crystals formed between trithiocyanuric acid and molecules containing hydrogen bonding functionality - Ahn, Sung-Hoon; PrakashaReddy, J.; Kariuki, B. M.; Chatterjee, S.; Ranganathan, A.; Pedireddi, V. R.; Rao, C. N. R.; Harris, Kenneth D. M. (Chemistry - A European Journal, 2005)
Crystallisation of trithiocyanuric acid (TTCA) from various organic solvents that have hydrogen bonding capability (acetone, 2-butanone, dimethylformamide, dimethyl sulfoxide, methanol and acetonitrile) leads to the formation of co-crystals in which the solvent molecules are incorporated together with TTCA in the crystal structure. Structure determination by single-crystal X-ray diffraction reveals that these co-crystals can be classified into different groups depending upon the topological arrangement of the TTCA molecules in the crystal structure. Thus, three different types of single-tape arrangements of TTCA molecules and one type of double-tape arrangement of TTCA molecules are identified. In all co-crystals, hydrogen-bonding interactions are formed through the involvement of N-H bonds of TTCA molecules in these tapes and the other molecule in the co-crystal. Detailed rationalisation of the structural properties of these co-crystals is presented.
Symposium on Chemistry-A European Conference - Stimulating Concepts in Chemistry, Inst Sci Ingenierie Supramoleculaires, Strasbourg, FRANCE, APR 15, 2005
Keywords: crystal engineering; hydrogen bonds; nitrogen heterocycles; structure elucidation

Studies on the crystallization behavior of nylon-6 in the presence of layered silicates using variable temperature WAXS and FTIR - Nair, S. S.; Ramesh, C. (Macromolecules, 2005)
The crystallization of nylon-6 clay nanocomposite was studied by variable temperature wide-angle X-ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR). Nylon-6 was found to crystallize into gamma phase at 210 degreesC, as indicated by its characteristic peaks in WAXS. However, an additional peak was observed close but on the lower angle side of the main gamma phase peak, indicating the presence of a metastable phase. The extent of metastable phase that developed was dictated by the clay content in the nanocomposite as well as the crystallization conditions. The temperature dependence of the d spacing of the gamma phase obtained in the presence of clay layers showed difference from the gamma phase obtained by treating nylon-6 in KI/I-2 solution. Variable temperature FTIR studies were conducted on the gamma phases for the first time, and it showed definite differences in the spectra of the phases obtained by the two methods.

Swelling behavior and diffusion studies of high-water-retaining acrylamide/potassium methacrylate hydrogels - Mohan, Y. M.; Murthy, P. S. K.; Rao, K. M.; Sreeramulu, J.; Raju, K. M. (Journal of Applied Polymer Science, 2005)
Poly(acrylamide-co-potassium methacrylate) hydrogels were prepared by free-radical simultaneous polymerization with aqueous solutions of acrylamide (AAm) and potassium methacrylate (KMA) with a redox initiator. The copolymerization was performed with eight different compositions of KMA at a fixed concentration of oil-soluble crosslinkers, including 1,4-butanediol diacrylate and ethylene glycol dimethacrylate (EGDMA). For every composition of AAm/KMA copolymer, the percentage swelling, swelling equilibrium, and diffusion characteristics were investigated. The copolymers were further studied for deswelling properties. The power law relationships of the hydrogels were evaluated for variation in terms of saline concentration. The AAm/KMA copolymers were confirmed by IR spectroscopy. Thermal studies of hydrogels were performed with differential scanning calorimetry and thermogravimetric analysis. EGDMA was found to be a better crosslinker for obtaining higher swelling and deswelling properties for the AAm/KMA hydrogels. (c) 2005 Wiley Periodicals, Inc.
Keywords: Diffusion; hydrogels; swelling

Synthesis, characterization, and performance evaluation of novel stabilized TDI-based polyurethane coatings under accelerated weathering - Kumar, A. P.; Reddy, K. R.; Rana, S.; Lonkar, Sunil P.; Raut, K. G.; Singh, R. P. (Journal of Vinyl & Additive Technology, 2005)
Some toluene dilsocyanate (TDI)-based polyurethane resins (PURs) for coating applications were synthesized with castor oil and their performance was estimated under accelerated UV weathering with and without a novel UV absorber. Changes in physical properties, chemical structure, and color of the samples were monitored by mechanical property testing, FTIR spectroscopy, and colorimetry, respectively. A stable polyurethane coating was achieved at 0.5% concentration of additive in the host matrix. Mechanical properties were also retained as in the pristine PUR after mixing. Commercial Tinuvin P and benzotriazole-based novel UV absorbers were found to improve the photoresistance of the PUR coating, and the highest efficiency of the novel UV absorber against weathering was estimated at 0.5 wt% concentration.(c) 2005 Society of Plastics Engineers.

Synthesis, characterization, and performance evaluation of polymeric HALS in ethylene-propylene-diene terpolymer (EPDM) - Lonkar, Sunil P.; Rana, S.; Singh, R. P.; Lacoste, Jacques; Gardette, Jean Luc; Jestin, F.; Brocord, E. (Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, 2005)
A polymeric hindered amine light stabilizer (HALS), wherein the hindered amine functionality was attached to the maleic anhydride graft ethylene-propylene-diene terpolymer (EPDM) was synthesized. This involves photoinduced grafting of maleic anhydride groups on unsaturated sites of EPDM, followed by incorporation of amino terminated HALS. The grafting and functionalization reactions were characterized by FTIR and C-13 NMR spectroscopy. The surface changes upon degradation are studied by SEM. The photostabilizing efficiency of this polymeric HALS was studied and compared with conventional HALS under accelerated weathering conditions. The HALS grafted EPDM showed significantly improved photostabilizing efficiency.
Keywords: EPDM; light induced grafting; Photostabilization; polymeric HALS

Synthesis of bismuth oxide nanoparticles at 100 degrees C - Patil, M. M.; Deshpande, V. V.; Dhage, S. R.; Ravi, V. (Materials Letters, 2005)
A simple gel to crystal conversion route has been followed for the preparation of ultrafine Bi2O3 particles at 80-100 degrees C under refluxing conditions. Freshly prepared bismuth hydroxide gel is allowed to crystallize under refluxing and stirring conditions for 6-12 h. Formation of nanocrystallites of Bi2O3 is confirmed by X-ray diffraction (XRD) study. The thermal decomposition of bismuth hydroxide yields Bi2O3 only at 400 degrees C. This shows the advantage of the present method. Transmission electron microscope (TEM) investigations revealed that the average particle size is 50 nm for these oven-dried powders. (c) 2005 Elsevier B.V All rights reserved.
Keywords: Ceramics; Chemical synthesis; Electron microscopy; Oxides; X-ray diffraction

Synthesis of bismuth oxide nanoparticles by citrate gel method - Anilkumar, Mettu; Pasricha, R.; Ravi, V. (Ceramics International, 2005)
A mixture of bismuth nitrate and citric acid solution is taken in 1: 1 molar ratio and heated on hot water bath. A gel is formed on evaporation of the water, which on decomposition at 400 degrees C produces nanocrystalline Bi2O3 particles. Formation of nanocrystallites of Bi2O3 is confirmed by X-ray diffraction (XRD) study. Transmission electron microscope (TEM) investigations revealed that the average particle size is 50 nm for these powders. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Keywords: Electron microscopy; powders : chemical preparation; X-ray methods

Synthesis of bismuth oxide nanoparticles using bismuth nitrate and urea - Jha, Ratnesh Kumar; Pasricha, R.; Ravi, V. (Ceramics International, 2005)
A mixture of bismuth nitrate and urea is taken in 1:5 molar ratio and heated on hot water bath. A precipitate is formed on evaporation of the water which on decomposition at 400 degrees C produces nanocrystalline Bi2O3 particles. Formation of nano crystallites of Bi2O3 is confirmed by X-ray diffraction (XRD) study. Transmission electron microscopy (TEM) investigations revealed for these powders an average particle size of 50 nm. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Keywords: calcination; Electron microscopy; X-ray methods

Synthesis of bismuth titanate by the urea method - Anilkumar, Mettu; Dhage, S. R.; Ravi, V. (Materials Letters, 2005)
A simple urea precipitation route was adopted for the preparation of bismuth titanate (Bi4Ti3O12) powders. Stoichiometric quantities of BiCl3 and TiOCl2 were mixed with the required amount of urea (the ratio of total metal cations to urea is five), and the mixture was heated on a water bath. This leads to the formation of precipitate, which was decomposed at 973 K. The formation of bismuth titanate was observed on calcining powders at 973 K by X-ray diffraction studies. The average particle size is found to be 100 nm by microscopy. The room temperature dielectric constant is found to be 150 at 1 kHz. The hysteresis loop parameters were also obtained by home-built Sawer-Tower circuit. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Chemical synthesis; dielectric properties; ferroelectricity; X-ray diffraction

Synthesis of CdS and alloyed CdMnS nanocrystals using aqueous foams - Kumar, P. Senthil; Kasture, Manasi; Raghavan, U; Pasricha, R; Sastry, M (Journal of Nanoscience and Nanotechnology, 2005)
Certain surfactant-stabilized aqueous foams provide a potentially efficient and simple chemical route for the synthesis of various nanomaterials with controllable structure, size, and shape. In the present work, a one-step process for the synthesis of CdS and Cdl(1-x)Mn(x)S (0 < x < 10) nanocrystals has been described. Aqueous CdCl2 and the aerosol-OT solutions are homogeneously mixed together and thereafter, nitrogen is bubbled through this solution to produce stable aqueous foam. After drainage of the foam, the freestanding dry foam consisting of cadmium cations electrostatically complexed with the anionic aerosol-OT molecules at the liquid-gas interface is treated with H2S vapor. The foam turns yellowish-orange and collapses, in the process yielding CdS nanoclusters of variable morphology. This morphology variation is appropriately attributed to growth of the CdS as well as alloyed Cd1-xMnxS nanoparticles in different regions of the foam contributing to the varying topological structure. Optical absorption spectra of both CdS and Cd1-xMnxS nanoparticles clearly show a well-defined exciton absorption feature around 450 nm due to quantum confinement effects. The interesting band edge emission characteristics of these AOT-capped CdS and Cd1-xMnxS nanoparticles produced in the foam are discussed with respect to their size and shape. Particular interest in the present novel aqueous foam approach arises due to the fact that the cubic zincblende CdS and alloyed Cd1-xMnxS nanocrystals could easily be obtained even under ambient experimental conditions itself.
Keywords: absorption and fluorescence; aerosol-OT; alloyed CdMnS nanocrystals; aqueous foams; CdS nanoclusters; quantum confinement; zincblende

Synthesis of Ce0.75Zr0.25O2 at 100 degrees C - Dhage, S. R.; Gaikwad, S. R.; Muthukumar, P.; Ravi, V. (Ceramics International, 2005)
A simple gel to crystal conversion route has been used for the preparation of Ce0.75Zr0.25O2 phase at 80-100degreesC under refluxing conditions. Freshly prepared metal hydroxides gel from cerium and zirconium salt solution is allowed to crystallize under refluxing and stirring conditions for 4-10 h. Formation of nano crystallites of Ce0.75Zr0.25O2 is confirmed by X-ray diffraction (XRD). Transmission electron microscopy (TEM) investigations revealed the average particle size of these powders to be 5 nm. (C) 2004 Elsevier Ltd and Techna S.r.l. All rights reserved.
Keywords: CeO2; chemical preparation; Electron microscopy; powders; X-ray methods

Synthesis of eupomatilone-6 and assignment of its absolute configuration - Gurjar, Mukund K.; Karumudi, Bhargava; Ramana, C. V. (Journal of Organic Chemistry, 2005)
[GRAPHICS] The Zn-mediated Barbier reaction of the biarylaldehyde 8 with crotyl bromide followed by hydroboration and oxidation provided the gamma-butyrolactones 4 and 5. The stereoselective installation of methyl group at C-3 by using LiHMDS and MeI completed the synthesis of racemic eupomatilone-6 (2) and its diastereomer 3. The spectroscopic data of 2 was in fall agreement with reported spectra of natural product, thus confirming the revised relative configuration of eupomatilone-6. Similarly, an optically active (3R,4R,5S)-isomer of eupomatilone-6 (23) was prepared in which the aldol reaction with thiazolidinethione as a chiral auxiliary was employed as a key step. On the basis of the spectroscopic data and optical rotation values of 23, the absolute configuration of eupomatilone-6 was proposed.

Synthesis of fine particles of ZnO at 100 degrees C - Dhage, S. R.; Pasricha, R.; Ravi, V. (Materials Letters, 2005)
A simple gel to crystal conversion route has been followed for the preparation of fine ZnO at 80-100 degreesC under refluxing conditions. Freshly prepared zinc hydroxide gel is allowed to crystallize under refluxing and stirring conditions for 4-6 It. Formation of fine crystallites of ZnO is confirmed by X-ray diffraction (XRD) study. Transmission electron microscope (TEM) investigations revealed that the average particle size is 100 nm for these powders. (C) 2004 Elsevier B.V All rights reserved.
Keywords: Ceramics; Chemical synthesis; Electron microscopy; Oxides; X-ray diffraction

Synthesis of hydroxyapatite crystals using amino acid-capped gold nanoparticles as a scaffold - Rautaray, D.; Mandal, Sujata; Sastry, M. (Langmuir, 2005)
Inorganic composites are of special interest for biomedical applications such as in dental and bone implants wherein the ability to modulate the morphology and size of the inorganic crystals is important. One interesting possibility to control the size of inorganic crystals is to grow them on nanoparticles. We report here the use of surface-modified gold nanoparticles as templates for the growth of hydroxyapatite crystals. Crystal growth is promoted by a monolayer of aspartic acid bound to the surface of the gold nanoparticles; the carboxylate ions in aspartic acid are excellent hinging sites for Ca2+ ions. Isothermal titration calorimetry studies of Ca2+ ion binding with aspartic acid-capped gold nanoparticles indicates that the process is entropically driven and that screening of the negative charge by the metal ions leads to their aggregation. The aggregates of gold nanopartictes are believed to be responsible for assembly of the platelike hydroxyapatite crystals into quasi-spherical superstructures. Control experiments using uncapped gold nanoparticles and pure aspartic acid indicate that the amino acid bound to the nanogold surface plays a key role in inducing and directing hydroxyapatite crystal growth.

Synthesis of nanocrystalline Mn3O4 at 100 degrees C - Anilkumar, Mettu; Ravi, V. (Materials Research Bulletin, 2005)
A simple gel to crystal conversion route has been followed for the preparation of nanocrystalline tetragonal Mn3O4 powders at 80-100 degrees C under refluxing conditions. Freshly prepared manganese hydroxide gel is allowed to crystallize under refluxing and stirring conditions for 4-6 h. Formation of nano crystallites of Mn3O4 is confirmed by X-ray diffraction (XRD) study. Transmission electron microscope (TEM) investigations revealed that the average particle size is 50 nm for these powders. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: Ceramics; Chemical synthesis; Electron microscopy; Oxides; X-ray diffraction

Synthesis of nanocrystalline rutile - Samuel, V; Pasricha, R; Ravi, V (Ceramics International, 2005)
Nanocrystalline titanium dioxide (TiO2) in the rutile phase has been obtained by homogeneous precipitation using urea and TiOCl2. A mixture of urea and TiOCl2 is heated on a hot water bath at 65-75 degrees C to precipitate rutile powders. X-ray diffraction (XRD) studies on these oven-dried powders indicated the formation of single-phase rutile. Raman scattering experiments were also performed to confirm the formation of the rutile phase. Transmission electron microscopy (TEM) investigations revealed the average particle size of these powders to be 40 nm. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Keywords: chemical preparation; Electron microscopy; powders; TiO2; X-ray methods

Synthesis of rutile from ATO and stearic acid - Patil, M. M.; Deshpande, V. V.; Deshpande, S. B.; Samuel, V.; Ravi, V. (Materials Letters, 2005)
Nanocrystalline titanium dioxide in the rutile phase has been obtained from the solid state reaction between ammonium titanyl oxalate (ATO) and stearic acid at 400 degrees C in air. The fine powders of ATO and stearic acid are mixed well using acetone in an agate mortar and pestle for 2 h. This mixture (weight ratio of ATO to stearic acid > 5) on heating at 400 degrees C produces rutile powders. For the ratios of ATO to stearic acid < 5, a mixture of anatase and rutile phases is obtained. Pure ATO yields anatase phase on decomposition at 400 degrees C. These powders were characterized by X-ray diffraction (XRD), BET surface area measurements and transmission electron microscopy (TEM) studies. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Chemical synthesis; Electron microscopy; Oxides; X-ray techniques

Synthesis of small cyclic peptides constrained with 3-(3-aminomethylphenyl)propionic acid linkers using free radical-mediated macrocyclization - Balraju, V.; Reddy, D. Srinivasa; Periasamy, M.; Iqbal, Javed (Tetrahedron Letters, 2005)
In this letter, we report that small peptides (di- and tri-) having a 3-bromobenzyl group at the C-termini and an acryloyl group at the N-termini undergo an efficient Bu3SnH-AlBN mediated intramolecular free radical cyclization to afford cyclic peptides in good yields. We also propose that these cyclizations are occurring via a pre-organized acyclic structure dictated by a reverse turn (gamma/beta-turn). (c) 2005 Published by Elsevier Ltd.

Synthesis of Sr0.5Ba0.5Nb2O6 by citrate gel method - Pasricha, R; Ravi, V (Materials Chemistry and Physics, 2005)
A gel was formed when an aqueous solution of BaCl2, SrCl2, NbF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 700 degrees C yielded the nanocrystallites of ternary oxide, Sr0.5Ba0.5Nb2O6 (SBN) as confirmed by X-ray diffraction study (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at I kHz is 1000. The ferroelectric hysteresis loop parameters of these samples were also studied by a home built Sawyer-Tower circuit. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Electron microscopy; ferroelectricity; Oxides

Synthesis of Sr0.5Ba0.5Nb2O6 by urea method - Dhage, S. R.; Pasricha, R.; Ravi, V. (Materials Letters, 2005)
A precipitate was formed when an aqueous solution of SrCl2, BaCl2, NbF5 and urea in stoichiometric ratio (total metal cations to urea ratio is 5) is heated on a water bath.. This precipitate on decomposition at 750 degreesC yielded the nanocrystallites of ternary oxide, Sr0.5Ba0.5Nb2O6 (SBN) as confirmed by X-ray diffraction study (XRD). This is much lower temperature as compared to that prepared by traditional solid state method (1000 degreesC as reported for the formation of SBN ceramics. Transmission electron microscope (TEM) investigations revealed that the average particle size is 100 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 1050. The ferroelectric hysteresis loop parameters of these samples were also studied. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Electron microscopy; ferroelectricity; Oxides

Synthetic studies toward tricyclic cembranoids: a modular approach for the construction of the tricyclic framework of eunicin - Gurjar, MK; Nayak, S; Ramana, CV (Tetrahedron Letters, 2005)
The synthesis of a sugar derived allene and its intramolecular silver mediated etherification followed by ring closing metathesis has been explored for building the tricyclic framework of eunicin. (C) 2005 Elsevier Ltd. All rights reserved.
Keywords: Allene; Carbohydrate; cembranoid; eunicin; Ring closing metathesis

Thermal degradation kinetics of polyesters containing mesogenic aromatic diols - Mule, Smita Atmaram; Ghadage, R. S.; Jacob, Nalini E.; Rajan, C. R.; Ponrathnam, Surendra (Journal Applied Polymer Science, 2005)
A series of polyesters were synthesized by reacting structurally differing aromatic diols with either saturated (flexible) or unsaturated (rigid) dicarboxylic acid halide by a stirred interfacial polycondensation technique. Thermal degradation kinetics of these polyesters were investigated by applying Coats-Redfern and Horowitz-Metzger nonisothermal procedures. The dynamic thermogravimetry experiments were conducted in nitrogen to obtain differential thermogravimetric plots. Thermal stability of these polyesters was discussed on the basis of semiquantitative methods such as differential procedural decomposition temperature, integral procedural decomposition temperature, and fraction decomposition temperature (e.g., 10 % DT). Degradation proceeded in multiple stages. The thermal degradation patterns and activation energies in these stages were discussed in relation to central bridging moieties of aromatic diol. The activation energies of these polyesters were found to be in the range of 100 to 200 kJ/mol. The effect of spacer type on activation energy was also reported. (c) 2005 Wiley Periodicals, Inc.
Keywords: Activation energy; Degradation; kinetics (polym.); Polycondensation; polyesters

Thermal, magnetic and spectral studies of metal-quinone complexes Part III. radical coordination and hydrogen bonding mediated exchange interaction in copper-hydroxyquinone complex - Salunke-Gawali, S.; Rane, S. Y.; Boukheddaden, K.; Codjovi, E.; Linares, J.; Varret, F.; Bakare, P. P. (Journal of Thermal Analysis and Calorimetry, 2005)
The reaction of CuCl with 2HNQ, ( viz. 2- hydroxy- 1,4- naphthoquinone), in methanol results in [Cu-2( II, II)(4HNSQ)(2)(ONQ)(2)(H2O)(4)], Cu- 3 complex; [ where ONQ is the deprotonated oxidized form of ligand ( viz. 2- oxido- 1,4- naphthoquinone) and 4HNSQ one electron reduced tautomeric form of the ligand (i.e. 4- hydroxy - 1,2- naphthosemiquinone)]. The mixed valent redox ligation is confirmed in [ 9] by us. In present report complex Cu- 3 investigated by variable temperature magnetic susceptibility measurements ( SQUID), X and Q- band EPR, DSC and CV techniques. A break is observed in the chi(m)(-1) vs. T plot similar to 200 K in Cu- 3 which is attributed to a phase transition. In Cu- 3 a quintet state ( S= 2) is populated above 200 K by the molecular association of two exo Cu( II)( 4HNSQ) units via hydrogen bonding between Cu(ONQ) unit of endo ligands in dimer. Magnetic susceptibility data is treated with tetramer model with S= 1/2,1/2,1/2,1/2. The interdimer triplet- triplet interaction ( J) in two [ Cu( 4HNSQ)] units and intradimer ( zJ(1)) interaction between [ Cu( II)( 4HNSQ)] are best fitted with J= -50 cm(-1) and zJ(1)= 28 cm(-1), respectively, using g= 2.2. `Quintet- triplet' phase transition occurs with an enthalpy change of 31.83 kJ mol(-1) estimated from DSC. Cu( II)double left right arrow Cu( I) and NSQ double left right arrow CAT redox couples at E-1/2= 0.68 V and E-1/2 = -1.12 V, respectively are result of exo ligands and Cu( II) ions interaction, while shifts of ligand based peaks viz. NQ -> NSQ and NSQ double left right arrow CAT at - 0.44 and - 0.67 V towards positive potential on complexation are due to electron transfer interactions between endo ligand and Cu( II) ion.
Keywords: antiferromagnetic coupling; copper complexes; Lawsone; model complexes; quinones; triplet state

TiO2 ceramic varistor modified with tantalum and barium - Gaikwad, A. B.; Navale, SC; Ravi, V (Materials Science and Engineering B-Solid State Materials for Advanced Technology, 2005)
The non-linear current (I)-voltage (V) characteristics of titanium dioxide doped with small quantities of tantalum and barium (99.9 TiO2 + 0.1 Ta and 99.4 TiO2 + 0.1 Ta + 0.5 Ba, all are in at.%) were investigated. These samples have the non-linear coefficient (alpha) values of (20-30) with high breakdown voltages (E-B similar to 400-700 V mm(-1)). The pentavalent tantalum acts as donor and increases the electronic conductivity. The higher electrical conductivity and decrease in the breakdown field strength with barium addition is attributed to higher density. The acceptor like surface states formed by barium ions segregate to grain boundaries due size misfit to thereby modifying the electrical barrier characteristics of grain boundaries. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Oxides; TiO2; varistor; X-ray diffraction

Ti-oxo radicals and product selectivity in olefin oxidations over titanosilicate molecular sieves - Shetti, VN; Srinivas, D; Ratnasamy, P (Zeitschrift für Physikalische Chemie International Journal of Research in Physical Chemistry and Chemical Physics, 2005)
The O-O bond of Ti-oxo species (Ti-peroxo, Ti-hydroperoxo or Ti-superoxo) generated on titanosilicate molecular sieves contacted with H2O2 cleaves either heterolytically or homolytically. While the former type of O-O cleavage (generating non-radical reactive oxygen intermediates) leads to selective epoxide products, the latter (generating reactive oxygen radical intermediates, O-2(-center dot) and HOOcenter dot) results in non-sclective, allylic oxidation products in cyclohexene oxidation. These radicals were detected using EPR spin trapping techniques 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used as the spin trap. Radical quenchers like hydroquinone suppressed their concentration and enhanced epoxide selectivity.
Keywords: cyclic voltammetry of titanosilicates; EPR-spin trap experiments; Molecular sieves; oxidations; product selectivity; reactive oxygen species; titaniunz-oxo radicals; Titanosilicates

Unusual stereochemical outcome of radical cyclization: synthesis of (+)-biotin - Chavan, Subhash P.; Chittiboyina, A. G.; Ramakrishna, G.; Tejwani, R. B.; Ravindranathan, T.; Kamat, Subhash K.; Rai, B.; Sivadasan, L.; Balakrishnan, K.; Ramalingam, S.; Deshpande, V. H. (Tetrahedron, 2005)
An enantioselective synthesis of (+)-biotin 1 starting from naturally available cysteine is described. The key steps are the unusual stereochemical outcome of radical cyclization of compound 10 to prepare 5,5-fused system 11, and the introduction of C4-sidechain at C-6 in 13 via a Grignard reaction. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: biotin; exocyclization; radical cyclization

Using the dynamic, expanding liquid-liquid interface in a Hele-Shaw cell in crystal growth and nanoparticle assembly - Rautaray, D; Kavathekar, R; Sastry, M (Faraday Discussions, 2005)
The liquid-liquid interface has been used with considerable success in the synthesis of advanced materials ranging from (bio)minerals to inorganic membranes to nanoparticles. In almost all such cases, the interface is static. The Hele-Shaw cell in which a viscous fluid is displaced by a less viscous one in a constrained manner has been invaluable in the study of dynamic instabilities at interfaces and in the study of viscous fingering pattern formation. However, the potential of the Hele-Shaw cell in carrying out reactions at the interface between the two fluids leading to the formation of inorganic materials has been largely unrecognized and underexploited. Realizing that the dynamic liquid-liquid interface in a Hele-Shaw cell would provide opportunities to control a variety of time-scales associated with material formation, we have started a program on the use of the Hele-Shaw cell in materials synthesis. In this discussion paper, we present some of our recent results on the growth of calcium carbonate crystals in the Hele-Shaw cell by the reaction of Ca2+ ions electrostatically complexed with carboxylate ions pinned to the interface with carbonate ions present in the aqueous part of the biphasic reaction medium. We show that both polymorph selectivity and the morphology of the crystals may be modulated by varying the experimental conditions in the cell. We also discuss the possibility of using the dynamic interface in the Hele-Shaw cell to cross-link gold nanoparticles in water through bifunctional linkers present in the oil phase and investigate the nature of the structures formed.

Vapor phase oxidation of 4-fluorotoluene over vanadia-titania catalyst - Maurya, S. K.; Patil, P.; Shubhangi B. Umbarkar; Gurjar, M. K.; Dongare, Mohan K.; Rudiger, S.; Kemnitz, E. (Journal of Molecular Catalysis A - Chemical, 2005)
The vapor phase oxidation of 4-fluorotoluene has been carried out over vanadia-titania catalysts with moderate conversion and selectivity for 4-fluorobenzaldehyde. Two series of V2O5/TiO2 catalysts with 1-10 mol% vanadia were prepared by sol-gel technique using vanadium and titanium peroxide as vanadia and titania precursors respectively and by impregnation technique using vanadium peroxide on anatase titania support. The samples were characterized by X-ray diffraction, NH3-TPD, FT-IR and BET surface area measurements. The XRD of the catalysts prepared by impregnation technique showed retention of the anatase titania whereas the catalysts prepared by sol-gel technique showed the formation of rutile titania with minor amount of anatase phase at lower vanadia content (1-3 %), which completely transformed into anatase phase at higher vanadia loading. The samples prepared by sol-gel method showed higher acidity and surface area compared to the samples prepared by impregnation. Pyridine adsorption study by FT-IR revealed the presence of Lewis acidity at lower vanadia loading (1-3 %) and presence of both Lewis as well as Bronsted acidity at higher vanadia loading. The catalytic activity for oxidation of 4-fluorotoluene increased with vanadia loading in the sol-gel catalysts. The catalysts prepared by impregnation technique were found to be less active. However the selectivity for 4-fluorobenzaldehyde decreased with increase in vanadia content. The influence of vanadia loading, reaction temperature and contact time on the catalytic activity for 4-fluorotoluene oxidation has been investigated. The structure of the catalyst and its catalytic activity has been correlated. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Catalyst; fluorotoluene; Oxidation; vanadia-titania; vapor phase

Wet-chemical templateless assembly of metal nanowires from nanoparticles - Maddanimath, Trupti; Kumar, Anil; D'Arcy-Galla, J.; Ganesan, P. G.; Vijayamohanan, K.; Ramanath, G. (Chemical Communications, 2005)
We describe a new, simple, room-temperature wet-chemical approach for assembling Au and Ag nanoparticles into nanowire networks, without the use of lithographic templates. Five to 35 nm-diameter nanowires passivated with a thin organic layer were synthesized by mechanically agitating a biphasic liquid mixture of an aqueous hydrosol containing the nanoparticles, and toluene. Nanowire structure and surface chemistry are discussed based on electron microscopy, UV-visible spectroscopy and thermogravimetric analyses.

Zeolite-based organic-inorganic hybrid catalysts for phosgene-free and solvent-free synthesis of cyclic carbonates and carbamates at mild conditions utilizing CO2 - Srivastava, R; Srinivas, D; Ratnasamy, P (Applied Catalysis A - General, 2005)
As-synthesized zeolite-beta exhibits high catalytic activity for the synthesis of cyclic carbonates and alkyl and aryl carbarnates by a phosgene-free route, utilizing the greenhouse effect gas CO2. The reaction occurs with high yields of the desired products at mild conditions and without using any solvent or cocatalyst. Cyclic carbonates are synthesized by cycloaddition reaction Of CO2 with oxiranes (epichlorohydrin, propene oxide, styrene oxide and n-butene oxide) at 393 K and 6.9 bar. Alkyl and aryl carbarnates are synthesized by the reaction of the corresponding amines, CO2 and n-butyl bromide at 353 K and 3.4 bar. The as-synthesized zeolite-beta containing the encapsulated quaternary ammonium ions is not only reusable in several recycling experiments, but also shows superior activity to that of the corresponding homogeneous, quaternary ammonium halide salt generally used in the commercial synthetic practice. The microporous silica (inorganic) acting in concert with the encapsulated organic component constitutes an efficient, recyclable catalyst for this reaction. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: alkyl and aryl carbamates; carbon dioxide utilization; cyclic carbonate; phosgene-free synthetic route; Polycarbonate; zeolite-beta

3-(2,4-Dichlorophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one - Rosli, Mohd Mustaqim; Patil, P. S.; Fun, Hoong-Kun; Razak, Ibrahim Abdul; Puranik, Vedavati G.; Dharmaprakash, S. M. (Acta Crystallographica Section E-Structure Reports Online, 2006)
In the title compound, C16H12Cl2O2, the dihedral angle between the benzene rings is 28.63 (6)degrees. The crystal structure is stabilized by intermolecular C-H center dot center dot center dot O hydrogen bonds and by short Cl center dot center dot center dot Cl interactions.

3-(3-bromophenyl)-1-(4-methoxyphenyl)-prop-2-en-1-one - Patil, P. S.; Rosli, Mohd Mustaqim; Fun, Hoong-Kun; Razak, Ibrahim Abdul; Puranik, Vedavati G.; Dharmaprakash, S. M. (Acta Crystallographica Section E-Structure Reports Online, 2006)
In the title compound, C16H13BrO2, the dihedral angle between the aromatic rings is 41.34 (6)degrees. The molecules (via two C-H center dot center dot center dot O intermolecular interactions) form chains along the a axis that stack into layers parallel to the b axis.

[6+3] cycloaddition of pentafulvenes with 3-oxidopyrylium betaine: a novel methodology toward the synthesis of 5-8 fused oxabridged cyclooctanoids - Krishnan, K. Syam; Sajisha, V. S.; Anas, S.; Suresh, C. H.; Bhadbhade, Mohan M.; Bhosekar, Gaurav V.; Radhakrishnan, K. V. (Tetrahedron, 2006)
Pentafulvenes undergo a facile [6+3] cycloaddition with 3-oxidopyrylium betaine, generated from the corresponding pyranulose acetate, leading to the formation of 5-8 fused oxabridged cyclooctanoids. The product is formed by a [6+3] cycloaddition, followed by a 1,5-hydrogen shift of the initially formed [6+3] adduct. The reaction was found to be general and a number of fulvenes with a wide range of substituents at the exocyclic double bond, that is, at the C6 position followed a similar reactivity pattern. The [6+3] adduct, a 5-8 fused oxabridged cyclooctanoid, is potentially amenable to a number of synthetic transformations due to the presence of an alpha, beta-unsaturated ketone and cyclopentadiene part. By selecting appropriately substituted fulvene and pyranulose acetates, it is possible to use this methodology for the synthesis of a wide range of 5-8 fused cyclooctanoids. The experimental results have been rationalized on the basis of theoretical calculations. (c) 2006 Elsevier Ltd. All rights reserved.
Keywords: fulvenes; oxabridged cyclooctanoids; oxidopyrylium betaine; [6+3] cycloaddition

Adsorption of methanol on Si(100)/SiO(2)and mesoporous SBA-15 - Mirji, S. A.; Halligudi, Shivaraj B.; Mathew, Nevin T.; Ravi, V.; Jacob, Nalini E.; Patil, K. R. (Colloids and Surfaces A-Physicochemical and Engineering Aspects, 2006)
Adsorption of methanol on SiO(100)/SiO2 substrate and mesoporous SBA-15 has been studied by using Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Contact angle technique is employed to study the adsorption kinetics of methanol on SiO(100)/SiO2 and thermal stability of adlayer. Thermogravimetric (TGA) technique is used to understand the thermal behavior of methanol layer on SBA-15. Adsorption kinetics fit fairly well with Langmuir isotherms giving adsorption rate constant, k(a) = 0.0021 W s(-1). FTIR results show formation of methoxy silicon (SiOCHA silicon polyhydride (SiH2), carboxylate, molecular water and hydroxyl groups on Si(100)/SiO2 surface and only methoxy silicon on SBA-15. XPS results confirm methanol adsorption and support FTIR results. The methanol adlayers are found to be thermally stable up to a temperature of similar to 262 degrees C on both Si(100)/SiO2 and SBA-15 and decompose between 262 and 450 degrees C. (c) 2006 Elsevier B.V. All rights reserved.
Keywords: Adsorption; desorption; kinetics; Methanol; SBA-15; Si(100)/SiO2; thermal stability

Amino functionalized novel cholic acid derivatives induce HIV-1 replication and syncytia formation in T cells - Salunke, Deepak B.; Ravi, D. S.; Pore, V. S.; Mitra, Debashis; Hazra, Braja G. (Journal of Medicinal Chemistry, 2006)
Synthesis of C-11 azido/amino functionalized cholic acid derivatives has been achieved in excellent yields. Contrary to the previous prediction of analogous compounds to be HIV-1 protease inhibitors, in the present study these novel cholic acid derivatives induced host cell fusion during the progress of HIV-1 infection and produced multinucleated giant cells. This is the first report of syncytia induction and enhancement of viral replication in HIV-1 infected T cells by cholic acid derivatives.

Biochemical characterization of a low molecular weight aspartic protease inhibitor from thermo-tolerant bacillus licheniformis: kinetic interactions with pepsin - Kumar, Ajit; Rao, Mala (Biochimica et Biophysica Acta-General Subjects, 2006)
The present article reports a low molecular weight aspartic protease inhibitor, API, from a newly isolated thermo-tolerant Bacillus licheniformis. The inhibitor was purified to homogeneity as shown by rp-HPLC and SDS-PAGE. API is found to be stable over a broad pH range of 2-11 and at temperature 90 degrees C for 2 1/2 h. It has a Mr (relative molecular mass) of 1363 Da as shown by MALDI-TOF spectra and 1358 Da as analyzed by SDS-PAGE The amino acid analysis of the peptide shows the presence of 12 amino acid residues having Mr of 1425Da. The secondary structure of API as analyzed by the CD spectra showed 7% alpha-helix, 49% beta-sheet and 44% aperiodic structure. The Kinetic studies of Pepsin-API interactions reveal that API is a slow-tight binding competitive inhibitor with the IC(50) and K(i) values 4.0nM and (3.83 nM - 5.31 nM) respectively. The overall inhibition constant K(i)* value is 0.107 +/- 0.015 nM. The progress curves are time-dependent and consistent with slow-tight binding inhibition: E+I reversible arrow (k(4), k(5)) EI reversible arrow (k(6), k(7)) EI*. Rate constant k(6) = 2.73 +/- 0.32 s(-1) reveals a fast isomerization of enzyme-inhibitor complex and very slow dissociation as proved by k(7)=0.068 +/- 0.009s(-1). The Rate constants from the intrinsic tryptophanyl fluorescence data is in agreement with those obtained from the kinetic analysis; therefore, the induced conformational changes were correlated to the isomerization of EI to EI*. (c) 2006 Elsevier B.V. Ail rights reserved.
Keywords: Aspartic protease inhibitor; Bacillus licheniformis; enzyme kinetic; Pepsin; Slow-tight binding inhibition

Biodegradation of gamma-sterilised biomedical polyolefins under composting and fungal culture environments - Alariqi, Sameh A. S.; Kumar, A. P.; Rao, B. S. M.; Singh, R. P. (Polymer Degradation and Stability, 2006)
Polyolefin-based commodities are widely used as biomedical devices and food packaging after gamma-sterilisation. The aim of the present work was to study the effect of gamma-sterilisation on the biodegradation of polyolefins. Films of isotactic polypropylene, high-density polyethylene and ethylene-propylene (EP) copolymers were sterilised under gamma-radiation with doses of 10 and 25 kGy. Neat and sterilised samples were incubated in compost and fungal culture environments. The changes in functional groups, surface morphology and chain scission in polymer chains were characterized by FTIR spectroscopy, SEM and viscometric measurements, respectively. A gradual decrease in intrinsic viscosity [eta] and increase in carbonyl and hydroxyl regions in FTIR spectra were found for the gamma-sterilised samples as a function of increasing dose. Polypropylene was found to be more susceptible to both radio-oxidation and biodegradation. It was observed that in case of ethylene-propylene copolymers, extent of gamma-sterilisation and/or biodegradation depends on the composition and distribution of comonomers. Important surface erosion was detected by SEM, for higher sterilisation doses, after composting. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords: Biodegradation; chain scission; Composting and fungal culture; gamma-sterilisation; Polyolefins

CFD simulation of gas-liquid stirred vessel: VC, S33, and L33 flow regimes - Khopkar, A. R.; Ranade, V. V. (AICHE Journal, 2006)
A comprehensive computational model based on the Eulerian-Eulerian approach was developed to simulate gas-liquid flows in a stirred vessel. A separate submodel was developed to quantitatively understand the influence of turbulence and presence of neighboring bubbles on drag acting on bubbles. This submodel was used to identify an appropriate correlation for estimating the interphase drag force. The standard k-epsilon turbulence model was used to simulate turbulent gas-liquid flows in a stirred vessel. A computational snapshot approach was used to simulate motion of the standard Rushton turbine in a fully baffled vessel. The computational model was mapped onto FLUENT4.5, a commercial CFD solver. The model predictions were compared with the previously published experimental data of Bombac and co-workers. The model was used to simulate three distinct flow regimes in gas-liquid stirred vessels: vortex clinging (VC), alternating small cavities (S33), and alternating large cavities (L33). The predicted results show reasonably good agreement with the experimental data for all three regimes. The computational model and results discussed in this work would be useful for understanding and simulating gas holdup distribution and flow regimes in stirred vessels. (c) 2006 American Institute of Chemical Engineers.
Keywords: computational fluid dynamics (CFD); Flow regimes; gas holdup distribution; Rushton turbine; stirred vessel

CFD simulation of mixing in tall gas-liquid stirred vessel: role of local flow patterns - Khopkar, A. R.; Kasat, Gopal R.; Pandit, A. B.; Ranade, V. V. (Chemical Engineering Science, 2006)
In this work, we have used the computational fluid dynamics (CFD)-based models to investigate the gas-liquid flows generated by three down-pumping pitched blade turbines. A two-fluid model along with the standard k-epsilon turbulence model was used to simulate the dispersed gas-liquid flow in a stirred vessel. Appropriate drag corrections to account for bulk turbulence [Khopkar and Ranade, 2005. CFD simulation of gas-liquid flow in a stirred vessel: VC, S33 and L33 flow regimes. A.I.Ch.E. Journal, accepted for publication] were developed to correctly simulate different flow regimes. The computational snapshot approach was used to simulate impeller rotation and was implemented in the commercial CFD code, FLUENT4.5 (of Fluent. Inc., USA). The computational model has successfully captured the flow regimes as observed during experiments. The particle trajectory simulations were then carried out to examine the influence of the different flow regimes on the circulation time distribution. The model predictions were verified by comparing the predicted results with the experimental data of [Shewale and Pandit, 2006. Studies in multiple impeller agitated gas-liquid contactors. Chemical Engineering Science 61, 489-504]. The computational model and results discussed in this study would be useful for explaining the implications local flow patterns on the mixing process and extending the applications of CFD models for Simulating large multiphase stirred reactors. (c) 2005 Elsevier Ltd. All rights reserved.
7th International Conference on Fluid Mixing, London, ENGLAND, APR 10-12, 2006
Keywords: CFD; Flow regimes; mixing; pitched blade turbine; stirred vessel

CFD simulation of shortstopping runaway reactions in vessels agitated with impellers and jets - Dakshinamoorthy, D.; Khopkar, A. R.; Louvar, J. F.; Ranade, V. V. (Journal of Loss Prevention in the Process Industries, 2006)
Runaway reactions are continuing to be a problem in the chemical industry. A recent study showed that 26% of our major chemical plant accidents are due to runaways. The consequences of runaway reactions are usually mitigated with (a) reliefs and containment systems or (b) shortstopping (reaction inhibition). This study covers the concept of shortstopping. One of the major reasons for runaways is power failure. In the advent of a power failure, mixing an inhibiting agent with the reactor contents is challenging. However, jets or impellers driven by a small generator can be used for mixing. This study compares shortstopping results in vessels agitated with jets and impellers using computational fluid dynamics (CFD). A commercial CFD code, Fluent is used. For shortstopping systems relying on jet mixing, angle and diameter of jet nozzle and jet velocity are the key design/operating parameters. For the systems with impellers, type, size and RPM of impeller are the key parameters. In this work, mixing with a jet mixer is first investigated for three nozzle diameters and two angles of injection. The best jet mixer configuration on the basis of mixing time is used for shortstopping studies. The simulated shortstopping results with the jet mixer are then compared with those obtained with impeller (Rushton and pitched blade turbine) stirred vessels. Our results identify the conditions for effective shortstopping; i.e., agitation requirements, locations for adding the inhibitor, and the quantity of inhibitor. The distribution of excess inhibitor is shown to be an important and essential design criterion for effective shortstopping when using impeller stirred vessels. The comparative study with a single jet shows that jet mixer is ineffective when used for shortstopping. Efforts such as adding excess inhibitor and inhibition with higher reaction rates at the same power, proved to be ineffective when using jet mixer compared to the results with impellers. (C) 2006 Elsevier Ltd. All rights reserved.
Keywords: CFD; impeller stirred vessels; jet mixer; runaway reaction; shortstopping

Chemical methods to synthesize FeTiO3 powders - Mona, J.; Kale, Sangeeta N.; Gaikwad, A. B.; Murugan, A. Vadivel; Ravi, V. (Materials Letters, 2006)
Three different techniques were used to synthesize FeTiO3 powders. The first method is simple coprecipitation of both Fe and Ti ions under basic conditions using standard ammonia solution from aqueous ferric nitrate and titanium oxy chloride. This precipitate on heating at 400 degrees C produces ilmenite phase. The second method is to digest hydroxide precipitates at 100 degrees C to form FeTiO3 phase. The third technique is to make use of citrate process to form FeTiO3 powders. The phase contents and lattice parameters were Studied by powder X-ray diffraction (XRD). Particle size and morphology were studied by Transmission Electron Microscopy (TEM). (c) 2005 Elsevier B.V. All tights reserved.
Keywords: Chemical synthesis; Electron microscopy; electronic materials; X-ray methods

Chemo-, regio- and stereo-selective aerial oxidation of limonene to the endo-1,2-epoxide over Mn(Salen)-sulfonated SBA-15 - Saikia, Lakshi; Srinivas, D.; Ratnasamy, Paul (Applied Catalysis A-General, 2006)
Mn(Salen) complexes immobilized on sulfonic acid-functionalized SBA-15 molecular sieves (SBA-15-pr-SO3-Mn(Salen)) catalyze the Mukaiyama-type oxidation of R-(+)-limonene selectively to the 1,2-epoxide with molecular oxygen at 298 K (Salen = N,N-ethylenebis(salicylidenaminato)). The endo-diastereomer is formed with a diasteromeric excess of 39.8%. This catalyst exhibited higher catalytic activity than ``neat'' Mn(Salen) complexes directly supported on SBA-15 or zeolite-Y. A change in the oxidation state of Mn from +3 in the ``neat'' complex to +2 when immobilized on the sulfonated surface is a probable cause for the observed enhancement of catalytic activity. A part of the Mn complexes was leached out of the solid phase during the reaction. (c) 2006 Elsevier B.V. All rights reserved.
Keywords: aerial oxidation of limonene; catalysis by Mn(Salen) complexes; chemo-; immobilized Mn Schiff base complexes; Mesoporous molecular sieves; Mukaiyama-type oxidation; regio- and stereo-selective epoxidation; sulfonic acid-functionalized SBA-15

Clay-mediated selective hydrolysis of 5 `-O-acetyl-2 `,3 `-isopropylidene/cyclohexylidene nucleosides - Gurjar, Mukund K.; Mondal, Dhananjoy; Ravindranadh, S. V.; Chorghade, Mukund S. (Synthetic Communications, 2006)
A generalized procedure for the selective hydrolysis of 5'O-acetyl-2',3'-isopropylidene/cyclohexylidene nucleosides with a solid catalyst, Montmorillonite K-10 in refluxing methanol, to furnish 5'-O-acetyl-nucleosides is described.
Keywords: 5-O-acetylnucleosides; isopropylidene-nucleoside hydrolysis; montmorillonite K 10

Comparative assessment of downstream processing options for lactic acid - Joglekar, H. G.; Rahman, Imran; Babu, Suresh; Kulkarni, B. D.; Joshi, Ajit (Separation and Purification Technology, 2006)
The possibility of manufacturing a biodegradable polymer from lactic acid has led to extensive research in recovery of lactic acid produced by fermentation, by different downstream processing routes. This paper assesses the suitability of different downstream processing options such as reactive extraction, adsorption, electrodialysis, esterification and reactive distillation. It compares the costs of different process routes. The assessment indicates that the conventional precipitation of calcium lactate, followed by acidification, esterification and hydrolysis will be the most economical route although it generates large quantity of gypsum sludge. (c) 2006 Elsevier B.V. All rights reserved.
Keywords: Adsorption; electrodialysis; Esterification; Lactic acid; Reactive distillation; reactive extraction

Comparison of flow structures in spacer-filled flat and annular channels - Ranade, Vivek V.; Kumar, Anil (Desalination, 2006)
Spacers are designed to create directional changes in the flow through membrane modules. Such secondary flow structures reduce concentration polarization and membrane fouling. Obviously, type of the spacer used in membrane modules strongly influences the resulting flow and therefore performance of the module. In this work, we have modeled detailed fluid dynamics of spacer filled channels by using the `unit cell' approach. The validated computational fluid dynamics (CFD) model was used to evaluate performance of certain spacer shapes and compare the resulting fluid dynamics in flat and curved channels. The simulations show that fluid flow behavior in a spacer-filled flat and a spiral channel was not significantly different. This means that pressure drops and mass transfer coefficients measured in flat channels may provide adequate guidelines, which would also be valid for spiral-wound modules. The results presented in this work will have significant implications for identifying improved spacers with higher propensities to reduce fouling in membrane modules.
International Congress on Membranes and Membrane Processes, Seoul, SOUTH KOREA, AUG 21-26, 2005
Keywords: annular channel; CFD; flat channel; membrane spacers

Computational fluid dynamics simulation of the solid suspension in a stirred slurry reactor - Khopkar, A. R.; Kasat, Gopal R.; Pandit, A. B.; Ranade, V. V. (Industrial & Engineering Chemistry Research, 2006)
A comprehensive computational fluid dynamics CFD model was developed in the present study to gain insight into the solid suspension in a stirred slurry reactor. The preliminary simulations highlighted the need for the correct modeling of the interphase drag force. A two-dimensional model problem was then developed using CFD to understand the influence of free stream turbulence on the particle drag coefficient. The proposed correlation was then incorporated in a two-fluid model (Euler-Euler) along with the standard k-epsilon turbulence model with mixture properties to simulate the turbulent solid-liquid flow in a stirred reactor. A multiple reference frame approach was used to simulate the impeller rotation in a fully baffled reactor. A computational model was mapped on to a commercial CFD solver FLUENT6.2 (of Fluent Inc., USA). The model predictions were compared with the published experimental data of Yamazaki et al. [Powder Technol. 1986, 48, 205] and Godfrey and Zhu [AIChE Symp. Ser. 1994, 299, 181]. The predicted results show reasonably good agreement with the experimental data. The computational model and results discussed in this work would be useful for extending the applications of CFD models for simulating large stirred slurry reactors.

Concise asymmetric route to the antibiotic macrolides patulolide A and pyrenophorin - Rao, K. Srinivasa; Reddy, D. Srinivasa; Mukkanti, K.; Pal, Manojit; Iqbal, Javed (Tetrahedron Letters, 2006)
In this letter, we describe an enantiospecific route to patulolide A and pyrenophorin through the synthesis of known protected seco acid precursors starting from commercially available (S)-ethyl lactate. (c) 2006 Elsevier Ltd. All rights reserved.

Conducting polymer based hybrid nano-composites for enhanced corrosion protective coatings - Patil, R. C.; Radhakrishnan, S. (Progress in Organic Coatings, 2006)
Hybrid composite coatings containing zinc oxide (ZnO) and polyaniline (PANI) as nano-additives dispersions were prepared with poly(vinyl acetate) (PVAc) as the major matrix. The steel plates dip-coated with these formulations were tested for corrosion protection by immersion in saline water over long periods. The Tafel plots for the determination of open circuit potential (OCP) and corrosion current (I-corr) were recorded. The coatings containing both ZnO and PANI showed improved corrosion resistance as compared to the single component coating. The I-corr values of PVAc-ZnO-PANI are found to be two-order magnitude lower than that of PVAc and PVAc-ZnO coatings. The results are explained on the basis of enhancement in barrier properties due to nano-particulate additives in PVAc-ZnO-PANI film together with the redox behaviour of PANI and protective oxide layer formation near the substrate. (C) 2006 Elsevier B.V All rights reserved.
Keywords: Coatings; corrosion; nano-additives; polyaniline; ZnO

Conformation and microenvironment of the active site of a low molecular weight 1,4-beta-D-glucan glucanohydrolase from an alkalothermophilic thermomonospora sp.: involvement of lysine and cysteine residues - Jagtap, Sharmili; Rao, Mala (Biochemical and Biophysical Research Communications, 2006)
Conformation and microenvironment at the active site of 1,4-beta-D-glucan glucanohydrolase was probed with fluorescent chemo-affinity labeling using o-phthalaldehyde. OPTA has been known to form a fluorescent isoindole derivative by cross-linking the proximal thiol and amino groups of cysteine and lysine. Modification of lysine of the enzyme by TNBS and of cysteine residue by PHMB abolished the ability of the enzyme to form an isoindole derivative with OPTA. Kinetic analysis of the TNBS and PHMB-modified enzyme suggested the presence of essential lysine and cysteine residues, respectively, at the active site of the enzyme. The substrate protection of the enzyme with carboxymethylcellulose (CMC) confirmed the involvement of lysine and cysteine residues in the active site of the enzyme. Multiple sequence alignment of peptides obtained by tryptic digestion of the enzyme showed cysteine is one of the conserved amino acids corroborating the chemical modification studies. (c) 2006 Elsevier Inc. All rights reserved.
Keywords: 1; 4-beta-D-glucan glucanohydrolase; active site microenvironment; Cysteine; lysine; OPTA; PHMB; Thermomonospora sp.; TNBS

Control of stereoselectivity in 4-tert-butylphenol hydrogenation over a carbon-supported rhodium catalyst by carbon dioxide solvent - Hiyoshi, Norihito; Mine, Eiichi; Rode, Chandrashekhar V.; Sato, Osamu; Ebina, Takeo; Shirai, Masayuki (Chemistry Letters, 2006)
cis-4-tert-Butylcyclohexanol was obtained with a high cis ratio (cis/(cis + trans) = 0.9) in the hydrogenation of 4-tert-butylphenol over a carbon-supported rhodium catalyst along with hydrochloric acid in supercritical carbon dioxide solvent.

Co-precipitation technique for the preparation of ferroelectric BaBi2Ta2O9 - Dhage, S. R.; Pasricha, R.; Murugan, A. Vadivel; Ravi, V. (Materials Chemistry and Physics, 2006)
A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase BaBi2Ta2O9 (BBT). Ammonium hydroxide and ammonium oxalate were used to precipitate Ba2+, Bi3+ and Ta5+ cations simultaneously. No pyrochlore phase was found while heating powder at 800 degrees C and pure BaBi2Ta2O9 phase was found to be formed by X-ray diffraction. Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at 1 kHz is 350. The ferroelectric hysteresis loop parameters of these samples were also studied. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Chemical synthesis; electronic material; ferroelectricity; Oxides

Coprecipitation technique to prepare LiTaO3 powders - Navale, SC; Gaikwad, A. B.; Ravi, V (Materials Letters, 2006)
A simple coprecipitation technique had been successfully applied for the preparation of pure ultrafine single phase LiTaO3 (LT). An aqueous mixture of ammonium carbonate and ammonium hydroxide was used to precipitate Li+ and Ta5+ cations as carbonate and hydroxide respectively. This precursor oil heating at 750 degrees C produces LT powders. For comparison, LT powders were also prepared by the traditional solid state method. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier B.V. All rights reserved.
Keywords: Ceramics; Electron microscopy; electronic materials; X-ray diffraction

Coprecipitation technique to prepare NaNbO3 and NaTaO3 - Samuel, V; Gaikwad, A. B.; Ravi, V (Bulletin of Materials Science, 2006)
A simple coprecipitation technique has been used successfully for the preparation of pure, ultrafine, single phases of NaNbO3 (NN) and NaTaO3 (NT). An alcoholic solution of ammonium carbonate and ammonium hydroxide was used to precipitate Na+ and Nb5+ (or Ta5+) cations under basic conditions as carbonate and hydroxide, respectively. On heating at 700 degrees C, these precursors produce respective products. For comparison, both NN and NT powders were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). The particle size and morphology were studied by scanning electron microscopy (SEM).
Keywords: Ceramics; Chemical synthesis; Electron microscopy; electronic materials; Oxides; X-ray methods

Coprecipitation technique to prepare Sr0.5Ba0.5Nb2O6 - Murugan, A. Vadivel; Gaikwad, A. B.; Samuel, V.; Ravi, V. (Bulletin of Materials Science, 2006)
An aqueous mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and strontium ions as oxalates and niobium ions as hydroxide under basic conditions. This precursor on calcining at 750 degrees C yielded Sr0.5Ba0.5Nb2O6 phase. This is a much lower temperature than that prepared by traditional solid state method (1000 degrees C) as reported for the formation of Sr0.5Ba0.5Nb2O6 (SBN). Transmission electron microscopic (TEM) investigations revealed that the average particle size was 80 nm for the calcined powders. The room temperature dielectric constant at I kHz was found to be 1100. The ferroelectric hysteresis loop parameters of these samples were also studied.
Keywords: Ceramics; Electron microscopy; ferroelectricity; Oxides; X-ray diffraction

Crystalline phases in nylon-11: studies using HTWAXS and HTFTIR - Nair, S. S.; Ramesh, C.; Tashiro, K. (Macromolecules, 2006)
Nylon-11 was crystallized into different crystalline phases by appropriate methods. The chance in the structure during heating was monitored in situ by wide-angle X-ray scattering (WAXS). The alpha phase obtained by precipitating nylon-11 in 1,4-butanediol started transforming into the pseudohexagonal phase on heating, but the transformation was not fully completed before melting. The melt crystallized sample at 175 degrees C gave the pseudohexagonal phase, which transformed into the alpha' phase on cooling to room temperature at about 100 degrees C. The d spacing of the 00 1 reflection also showed a change at the transition temperature. The melt-quenched sample showed the pseudohexagonal phase, which did not change during heating, but on cooling transformed into alpha' phase. The gamma phase was obtained by casting nylon-11 in trifluoroacetic acid (TFA), and it changed into the pscudohexagonal phase at about 110 degrees C on heating. The d spacing of the 001 reflection depended on the way in which it was obtained. The studies have shown that nylon-11 is one of the few nylons that exhibit an extensive degree of polymorphism. High-temperature Fourier transform infrared spectroscopy (HTFTIR) studies revealed, apart from the conformational differences between various phases of nylon-11, some information on the formation of the gamma phase.

Crystallization and preliminary X-ray characterization of a thermostable low-molecular-weight 1,4-beta-D-glucan glucohydrolase from an alkalothermophilic thermomonospora sp. - Manikandan, K.; Jagtap, Sharmili; Rao, M.; Ramakumar, S. (Acta Crystallographica Section F-Structural Biology and Crystallization Communications, 2006)
{Cellulases catalyze the hydrolysis of beta-1,4-glycosidic linkages within cellulose, the most abundant organic polymer on earth. The cellulase (TSC; EC 3.2.1.4) from an alkalothermophilic Thermomonospora sp. has a low molecular weight of 14.2 kDa. It is optimally active at 323 K and stable over the wide pH range of 5 - 9. Moreover, it has bifunctional activity against cellulose and xylan polymers. In this study, TSC was purified from the native source and crystallized by the hanging-drop vapour-diffusion method. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 49.9

Cu(I)-catalyzed cycloaddition of constrained azido-alkynes: access to 12- to 17-membered monomeric triazolophanes incorporating furanoside rings - Ray, A.; Manoj, Kochunnoonny; Bhadbhade, Mohan M.; Mukhopadhyay, R.; Bhattacharjya, A. (Tetrahedron Letters, 2006)
A strained monomeric 12-membered triazolophane was formed by the Cu(I)-catalyzed intramolecular cycloaddition of an azide to an alkyne having a constrained tether incorporating ail aromatic ring and a furanoside ring. Similar cycloadditions of azido-alkynes having ester, furanoside and peptidic tethers led to the formation of monomeric triazolophanes of higher ring sizes. (c) 2006 Elsevier Ltd. All rights reserved.

Direct hydrothermal synthesis of highly ordered Sn-SBA-15 mesoporous materials - Shah, Pallavi; Ramaswamy, Arumugamangalam V.; Ramaswamy, Veda (Chemistry Letters, 2006)
Well-ordered Sn4+-incorporated mesoporous silica SBA-15 samples have been synthesized from tetraethyl orthosilicate (TEOS) and SnCl4 (Si/Sn = 114-15) using nonionic surfactants under a slightly higher pH medium (optimum H2O to HCl molar ratio) and characterized by XRD (an increase in lattice parameter), TEM (no SnO2 species) and UV-vis spectral (absorption at 211 nm) techniques to show that Sn4+ ions are in tetrahedral coordination in Sn-SBA-15.

Direct somatic embryogenesis and plant regeneration in Garcinia indica Choiss - Thengane, Shubhada Ratnakar; Deodhar, Swapna R.; Bhosle, S. V.; Rawal, S. K. (Current Science, 2006)
Direct somatic embryogenesis without an intervening callus phase was induced from immature seeds of Gar- cinia indica Choiss. Woody plant medium supplemented with 6-benzyl amino purine (BAP) (4.44-22.19 mu m) alone or in combination with a-naphthaleneacetic acid (2.69 mu m) produces somatic embryos within a period of 2-3 weeks with 80% frequency. Embryo induction was observed all over the explant surface. Origin of the embryo was confirmed histologically from sub-epidermal layer of the seed. Maturation of these embryos was achieved after 12 weeks of culture on a medium containing BAP (16.08 mu m) in combination with indole-3-acetic acid (2.85-5.71 mu m) and/or kinetin (4.65 mu m). About 75% of the regenerated somatic embryos germinated into complete plantlets. The plantlets were acclimatized successfully with 92% survival in greenhouse.
Keywords: Garcinia indica; guttifereae; seeds; somatic embryos

Effect of calcination cycles on the preparation of tin oxide based traditional drug: studies on its formation and characterization - Wadekar, M. P.; Rode, C. V.; Bendale, Y. N.; Patil, K. R.; Gaikwad, A. B.; Prabhune, Asmita (Journal of Pharmaceutical and Biomedical Analysis, 2006)
The preparation method of metal based Indian traditional drugs involves conversion of a pure metal into its oxide by repeated high temperature calcination cycles. In this work, the effect of number of calcination cycles followed in the preparation of tin oxide based Ayurvedic drug, `vanga bhasma' was studied by a systematic characterization of the drug samples after various calcination stages. It was found that tin was in the form of Sn4+ state and that the formation of SnO2 proceeded step-wise through Sn(OH)(4). (c) 2006 Elsevier B.V. All rights reserved.
Keywords: calcination cycles; Oxidation; oxidation state of tin; Particle size; tin oxide; vanga bhasma

Effect of spacer groups on the performance of MCM-41-supported platinum cluster-derived hydrogenation catalysts - Maity, Niladri; Basu, Susmit; Mapa, Maitri; Rajamohanan, Pattuparambil R.; Ganapathy, Subramanian; Gopinath, Chinnakonda S.; Bhaduri, Sumit; Lahiri, Goutam Kumar (Journal of Catalysis, 2006)
MCM-41 was functionalized with (EtO)(3)SiCH2Cl, (MeO)(3)SiCH2CH2CH2Cl, and (CH3)Cl2SiCH2Cl. The functionalized materials were characterized by solid-state NMR (CPMAS, Si-29 and C-13) and XPS. The NMR data indicate that three new silicon environments were created by(EtO)(3)SiCH2Cl and (MeO)(3)SiCH2CH2CH2Cl, whereas with (CH3)Cl2SiCH2Cl, two new silicon environments were obtained. XPS results from Si 2p core level and the valence band from the material functionalized by (MeO)(3)Si(CH2)(3)Cl was found to be the same as that of the corresponding fresh catalyst (1a), in contrast to that of the materials functionalized by the other two silane reagents. After further functionalization with triethylamine, these materials were used as inorganic anion exchangers to support the cluster anion [Pt-12(CO)(24)](2-). Solid-state NMR (29Si, C-13, N-15) was used to establish the presence of the quaternary ammonium group in the cluster-supported species. Analogous materials were also created using fumed silica as the support, and all of the cluster-supported materials were tested as catalysts for the hydrogenation of methyl pyruvate, acetophenone, nitrobenzene, benzonitrile, ethylacetoacetate, 4-nitrotoluene, cyclohexanone, allyl alcohol, and styrene. The best activity was obtained for the catalyst that had MCM-41 as the support and chloropropyl as the spacer group. TEM showed that the supports and the spacer groups had observable effects on the platinum crystallite size of the catalysts. (c) 2006 Elsevier Inc. All rights reserved.
Keywords: functionalized inorganic oxides; hydrogenation catalysts; MCM-41; platinum carbonyl cluster; Solid-state NMR; spacer groups; XPS

Effect of thermal annealing on Fe40Ni38B18Mo4 thin films: modified Herzer model for magnetic evolution - Hysen, T.; Deepa, S.; Saravanan, S.; Ramanujan, R. V.; Avasthi, D. K.; Joy, Pattayil Alias; D Kulkarni, S.; Anantharaman, Maliemadom R. (Journal of Physics D-Applied Physics, 2006)
Magnetic properties of nano-crystalline soft magnetic alloys have usually been correlated to structural evolution with heat treatment. However, literature reports pertaining to the study of nano-crystalline thin films are less abundant. Thin films of Fe40Ni38B18Mo4 were deposited on glass substrates under a high vacuum of approximate to 10(-6) Torr by employing resistive heating. They were annealed at various temperatures ranging from 373 to 773K based on differential scanning calorimetric studies carried out on the ribbons. The magnetic characteristics were investigated using vibrating sample magnetometry. Morphological characterizations were carried out using atomic force microscopy (AFM), and magnetic force microscopy (MFM) imaging is used to study the domain characteristics. The variation of magnetic properties with thermal annealing is also investigated. From AFM and MFM images it can be inferred that the crystallization temperature of the as-prepared films are lower than their bulk counterparts. Also there is a progressive evolution of coercivity up to 573 K, which is an indication of the lowering of nano-crystallization temperature in thin films. The variation of coercivity with the structural evolution of the thin films with annealing is discussed and a plausible explanation is provided using the modified random anisotropy model.

Electrical bistability in a xanthene class molecule: conduction mechanisms - Rath, Arup Kumar; Sahu, Satyajit; Pal, Amlan J. (Applied Physics Letters, 2006)
The author study conduction mechanism in two conducting states of a bistable device at range. They find that in the electrical bistable devices, electrical switching is associated with a change in the conduction mechanism. Device current in the low-conducting state follows an injection-limited mechanism. The current in the high-conducting state conforms a bulk-dominated mechanism, namely, space-charge limited conduction with an exponential distribution of traps. The bistability has an associated memory phenomenon. The devices exhibit read-only and random-access memory applications for several hours.

Electrochemical organization of monolayer protected gold nanoclusters on single-walled carbon nanotubes: significantly enhanced double layer capacitance - Mahima, Subhramanyam; Chaki, N. K.; Sharma, J.; Kakade, Bhalchandra A.; Pasricha, R.; Rao, A. M.; Vijayamohanan, K. (Journal of Nanoscience and Nanotechnology, 2006)
This paper reports a novel electrochemical route for anchoring monolayer protected gold nanoclusters (size 8 +/- 0.2 nm) on single-walled carbon nanotube bundles, resulting in the formation of hybrid materials. Monolayer protected gold nanoclusters prepared by modified Brust synthesis route were organized on SWNT bundles by cycling-the potential in dichloromethane between -1 to +1 V at a scan rate of 50 mV/s. Monolayer protected nanoclusters in electrolyte solutions possess ionic space charge around them (double layer charging), making them suitable for organization on nanotube bundles, by tuning the electrostatic interactions. More significantly, analysis of the double layer capacitance of these hybrid materials shows almost ten times increase in capacitance compared to that of bare SWNT bundles. We believe that these hybrid materials are potentially useful in nanoelectronics.
Keywords: double layer capacitance; double layer charging; hybrid materials; monolayer protected gold nanoclusters; single-walled carbon nanotubes

Enhancing cross-peak intensity in 2D-SLF spectroscopy - the role of equilibrium carbon magnetization in cross-polarization experiment - Das, Bibhuti B.; Ajithkumar, Thalasseril G.; Ramanathan, K. V. (Chemical Physics Letters, 2006)
A modification to the standard Hartmann-Hahn cross-polarization experiment has been proposed in which the initial 90 degrees pulses are applied both on the I and S spins. The inclusion of the available equilibrium polarization in the static magnetic field for the S spins is shown to have a beneficial effect for the 2D-SLF experiment, contributing to an increase in the cross-peak intensity and hence to a better resolution of the dipolar cross-peaks. (c) 2006 Elsevier B.V. All rights reserved.

Epoxidation of indene and cyclooctene on nanocrystalline anatase titania catalyst - Ramaswamy, Veda; Awati, Preeti; Ramaswamy, A. V. (Topics in Catalysis, 2006)
Nanocrystalline anatase titania samples of different crystallite sizes were prepared by sol gel method using ultrasonication and calcination at different temperatures. The calcined samples were treated with H2O2 in order to study the role of surface hydroxyl groups present on titania in generating reactive oxygen species responsible for the epoxidation reaction. The crystallite size of the calcined samples increased from 4 to 18 nm as the calcination temperature increased from 473 to 773 K, respectively. More uniform distribution/dispersion of the nanoparticles (SEM), marginally higher surface area, better thermal stability and phase purity are some of the advantages of preparation of nanocrystalline TiO2 by using ultrasonication. EPR spectral data on the H2O2-treated samples confirmed the presence of superoxide radical species. The two distinct UV bands observed at 400 and 450 nm are assigned to charge transfer of peroxide (O-2 2-) to Ti. FT-IR spectral data show that the surface hydroxyl groups are the active sites in the generation of reactive oxygen species. The catalytic activity was evaluated in a series of epoxidation reactions using indene and cyclooctene as substrates and aqueous H2O2 as oxidant. The activity was found to decrease with increase in the calcination temperature of the samples, obviously due to an increase in crystallite size and a decrease in surface hydroxyl groups. The nanoparticle titania samples show better conversion and selectivity than the standard titania (Degussa P-25). The kinetic studies revealed that the reaction followed a pseudo first order kinetics in excess of H2O2.
19th Meeting of the North-American-Catalysis-Society (NAM), Philadelphia, PA, MAY 22-27, 2005
Keywords: cyclooctene epoxidation; epoxidation of indene; nanocrystalline anatase titania; superoxide radical on titania

Eu3+ doped lanthanum oxide nanowhiskers: microwave hydrothermal synthesis, characterization and photoluminescence properties - Murugan, A. Vadivel; Viswanath, Annamraju Kasi; Kakade, Bhalchandra A.; Ravi, V.; Saaminathan, V. (Journal of Physics D-Applied Physics, 2006)
We report here a straightforward and rapid microwave - hydrothermal route providing an easy synthesis of Eu3+ doped La2O3 nanowhiskers. The nanostructured Eu3+ doped La2O3 is characterized by x-ray diffraction studies, scanning electron microscopy and photoluminescence (PL). The emission spectrum shows transitions from the excited 5D(0) state to F-7(J) (J = 0, 1, 2, 3, 4) levels of the Eu3+ ion. The most intense peak around 611 nm is due to the D-5(0) -> F-7(2) transition, expected from the Judd-Ofelt selection rules. PL spectra measurements demonstrate that the lanthanum oxide nanowhisker shows higher PL intensity.

Eulerian-lagrangian simulations of unsteady gas-liquid flows in bubble columns - Buwa, Vivek V.; Deo, Dhanannjay S.; Ranade, Vivek V. (International Journal of Multiphase Flow, 2006)
We studied the dynamics of gas-liquid flows in a rectangular bubble column using Eulerian-Lagrangian simulations. Three-dimensional, unsteady simulations were performed to simulate the dynamic characteristics of the oscillating bubble plume. The effect of superficial gas velocity and aerated liquid height-to-column width (HI K) ratio on the dynamic and time-averaged flow properties was studied and the simulated results were validated using wall pressure and voidage fluctuation measurements. The effect of lift force and numerical diffusion on the dynamic and time-averaged properties is discussed in detail. Further, the results obtained using the Eulerian-Lagrangian simulations were compared with the Eulerian-Eulerian simulations. The bubble scale information, which is otherwise lost in the Eulerian-Eulerian simulations, was validated using the voidage fluctuation measurements. Such experimentally validated Eulerian-Lagrangian models will be useful for the simulation of mass transfer and reactions in bubble columns. (c) 2006 Elsevier Ltd. All rights reserved.
Keywords: Bubble column; CFD; Dynamics; Eulerian-Eulerian simulations; Eulerian-Lagrangian simulations; gas-liquid flow

Fe-Zn double-metal cyanide complexes as novel, solid transesteritication catalysts - Srivastava, R.; Srinivas, D.; Ratnasamy, P. (Journal of Catalysis, 2006)
Fe-Zn double-metal cyanide complexes are currently used as catalysts for the ring-opening polymerization of epoxides, as well as the coupling of epoxides and CO2 for the production of polycarbonates. We report their novel application as highly efficient solid catalysts for the transesterification reactions of carbonates. The catalysts were prepared from aqueous solutions of ZnCl2 and K4Fe(CN)(6) in the presence of tert-butanol (complexing agent) and tri-block copolymer EO20PO70EO20 (average molecular weight, 5800; co-complexing agent). They were characterized by chemical analysis, XRD, thermal analysis, N-2 adsorption, magnetic susceptibility, SEM, and FTIR, diffuse reflectance UV-visible, EPR, and X-ray photoelectron spectroscopies. Their acidity was determined from the IR spectra of adsorbed pyridine and the temperature-programmed desorption of NH3. Catalyst samples prepared with both complexing and co-complexing agents were found to be more acidic and catalytically active than those prepared without these agents. These catalysts are more active/selective than other solid catalysts hitherto reported. Dimethyl carbonate, for example, could be synthesized with 100% selectivity and an isolated yield of >86% by the reaction of propene carbonate with methanol. The catalysts can be recycled without significant loss in activity. Lewis acidic Zn ions are the possible active sites for the transesterification reaction. (c) 2006 Published by Elsevier Inc.
Keywords: cyclic carbonate; Dimethyl carbonate; double metal cyanide Fe-Zn complexes; organic carbonate; transesterification catalyst

Field emission studies of novel ZnO nanostructures in high and low field regions - Ramgir, Niranjan S.; Late, Dattatray J.; Bhise, Ashok B.; Mulla, Imtiaz S.; More, Mahendra A.; Joag, Dilip S.; Pillai, Vijayamohanan K. (Nanotechnology, 2006)
A study of the field emission characteristics of novel structures of ZnO, namely marigolds, multipods and microbelts, has been carried out in both the close proximity configuration and the conventional field emission microscope. The use of a conventional field emission microscope overcomes the drawback of arc formation at high field values. The nonlinearity in the Fowler - Nordheim ( F - N) plot, a characteristic feature of semiconductors has been observed and explained on the basis of electron emission from both the conduction and the valence bands. The current stability exhibited by these structures is also promising for future device applications.

Genetic diversity analysis in Gaultheria fragrantissima wall. (Ericaceae) from the two biodiversity hotspots in India using ISSR markers - Apte, G. S.; Bahulikar, R. A.; Kulkarni, R. S.; Lagu, Meena D.; Kulkarni, B. G.; Suresh, H. S.; Rao, P. S. N.; Gupta, V. S. (Current Science, 2006)
Our study involves Inter Simple Sequence Repeat markers to analyse genetic diversity of an undershrub, Gaultheria fragrantissima Wall. (Ericaceae) from two plant diversity hotspots in India, namely Western Ghats and Northeastern Himalayas. The plants from these two regions show no morphological differences but the total heterozygosity (H-T = 0.505) is high. Furthermore, the average heterozygosity of G. fragrantissima at WG (H-s = 0.433) is higher than that at NE region (H-s, = 0.231). Within population variance is higher (15.56 %) than among population variance (8.31 %) as seen in outcrossing plant species. Mantel's test shows a strong positive correlation between the genetic and geographic distances. The plants within WG show high gene flow, which may be enough to prevent genetic drift, however, the gene flow in NE population is very low.
Keywords: Gaultheria fragrantissima; Genetic diversity; heterozygosity; ISSR markers

High-throughput screening of RNA polymerase inhibitors using a fluorescent UTP analog - Bhat, Jyothi; Rane, Rajendra; Solapure, Suresh M.; Sarkar, Dhiman; Sharma, Umender; Harish, M. N.; Lamb, Sarah; Plant, Darren; Alcock, Peter; Peters, Steve; Barde, Shubhada; Roy, Raman K. (Journal of Biomolecular Screening, 2006)
RNA polymerase (RNAP) is a well-validated target for the development of antibacterial and antituberculosis agents. Because the purification of large quantities of native RNA polymerase from pathogenic mycobacteria is hazardous and cumbersome, the primary screening was carried out using Escherichia coli RNAP. The authors have developed a high-throughput screening (HTS) assay to screen for novel inhibitors of RNAP. In this assay, a fluorescent analog of UTP, gamma-amino naphthalene sulfonic acid (gamma-AmNS) UTP, was used as one of the nucleotide substrates. Incorporation of UMP in RNA results in the release of gamma-AmNS-PPi, which has higher intrinsic fluorescence than (gamma-AmNS) UTP. The assay was optimized in a 384-well format and used to screen 670,000 compounds at a concentration of 10 mu M. About 0.1% of the compounds showed more than 60% inhibition in the primary HTS. All the primary actives tested for dose response using the same assay had an EC50 below 100 mu M. Eighty percent of the primary HTS actives obtained using E. coli RNAP showed comparable activity against Mycobacterium smegmatis RNAP in the conventional radioactive assay. Activity of hits selected for the hit-to-lead optimization was also confirmed against Mycobacterium bovis RNAP which has > 99% sequence identity with Mycobacterium tuberculosis RNAP subunits.

Hybrid foldamer with unique architecture from conformationally constrained aliphatic-aromatic amino acid conjugate - Srinivas, Deekonda; Gonnade, Rajesh G.; Ravindranathan, Sapna; Sanjayan, Gangadhar J. (Tetrahedron, 2006)
In this paper, we describe the design and synthesis of a novel hybrid foldamer, derived from a conformationally constrained aliphatic-aromatic amino acid conjugate that adopts a well-defined, compact, three-dimensional structure, governed by a combined conformational restriction imposed by the individual amino acids from which the foldamer is composed. Conformational investigations confirmed the prevalence of a unique doubly bent conformation for the foldamer, in both solid and solution states, as evidenced from single crystal X-ray and 2D NOESY studies, respectively. The findings suggest that constrained aliphatic-aromatic amino acid conjugates offer new avenues for the de novo design of hybrid foldamers with distinctive structural architectures. Furthermore, the de novo design strategy disclosed herein has the potential for significantly augmenting the `tool-box' of the modern day peptidominetic chemist, as well as providing a novel approach to the field of rational design. (c) 2006 Elsevier Ltd. All rights reserved.
Keywords: Amino acids; Conformation; Foldamer; Peptidomimetics

Hydrogen bonding and rate enhancement in the photoinduced polymerization of telechelic urethane methacrylates based on a cycloaliphatic system: tricyclodecane dimethanol - Deepak, V. D.; Rajan, J.; Asha, S. K. (Journal of Polymer Science Part A-Polymer Chemistry, 2006)
A new class of telechelic urethane methacrylic crosslinkers, based on a cycloaliphatic system (tricyclodecane dimethanol and tricyclodecane monomethanol), was synthesized. The synthesis was achieved by a two-step condensation of 1,6-hexamethylene diisocyanate or isophorone diisocyanate with tricyclodecane dimethanol and capping with hydroxyethyl methacrylate. Samples of hexanediol diacrylate, tricyclodecane monomethacrylate, and tricyclodecane dimethacrylate were used as non-hydrogen-bonding monomers for comparative studies of the curing kinetics. The photopolymerization of these telechelic systems was investigated with UV irradiation in the presence of 2,2-diethoxy acetophenone as the photoinitiator, and the kinetics were followed by the monitoring of the double-bond conversion at 815 cm−1 with Fourier transform infrared spectroscopy. The hydrogen-bonded crosslinkers had higher double-bond conversions than their non-hydrogen-bonded counterparts under identical conditions. The higher cure rate could be explained by hydrogen-bonding preassociation in these systems, which brought the methacrylate double bonds within close proximity. The temperature effects on the hydrogen bonding were also investigated. A decrease in the extent of the double-bond conversion with increasing temperature was observed for the hydrogen-bonded crosslinker, in contrast to an increased conversion with temperature for hexanediol diacrylate and tricyclodecane dimethacrylate. This was directly indicative of a reduction of hydrogen bonding at elevated temperatures leading to lower conversions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4384–4395, 2006

Hydrophobic, solid acid catalysts for production of biofuels and lubricants - Sreeprasanth, Pulinthanathu Sree; Srivastava, R.; Srinivas, D.; Ratnasamy, P. (Applied Catalysis A-General, 2006)
A novel application of Fe-Zn double-metal cyanide (DMC) complexes as solid catalysts in the preparation of fatty acid alkyl esters (biodiesel/biolubricants) from vegetable oils is reported. The catalysts are hydrophobic (no H2O adsorption at reaction temperatures) and contain only Lewis acidic sites (NH3 and pyridine adsorption). Bronsted acid sites are absent (absence of 1546 and 1639 cm(-1) bands on adsorption of pyridine). Basic sites are also absent (no CO2 adsorption). Unlike the homogeneous or other solid catalysts (like ZnO-Al2O3, for example), the Fe-Zn, DMC catalysts are highly active even for the simultaneous transesterification of triglycerides and esterification of the free fatty acids (FFA) present in unrefined and waste cooking oils as well as non-edible oils. They are also tolerant of water, probably, due to their surface hydrophobicity. A relationship between the transesterification activity and the concentration of strong Lewis acid sites has been observed. Coordinatively unsaturated Zn2+ ions in the structure of the Fe-Zn complex are the probable active sites. (c) 2006 Elsevier B.V. All rights reserved.
Keywords: alcoholysis of vegetable oils; Biodiesel; Biolubricants; double-metal cyanides (DMC); esterification of free fatty acids; fatty acid alkyl esters; fatty acid methyl esters; solid Fe-Zn catalysts; transesterification of vegetable oils

Intact cell MALDI mass spectrometry as a tool to screen drugs in vivo for regulation of protein expression - Kulkarni, Mahesh J.; Vinod, V. P.; Umashankar, P. K.; Patole, M.; Rao, M. (Molecular & Cellular Proteomics, 2006)

Isolation of new straight chain compounds from acacia nilotica - Chaubal, Rohini; Tambe, Amruta; Biswas, Sujata; Rojatkar, Supada; Deshpande, Vishnu; Deshpande, Nirinala (Indian Journal of Chemistry Section B-Organic Chemistry including Medicinal Chemistry, 2006)
A novel diester, pentacosane dioic acid dihexadecyl ester 1 has been isolated for the first time from n-hexane soxhlet extract of Acacia nilotica. Saponification of the diester reveals the presence of an alcohol, hexadecanol and pentacosane dioic acid. The structures of both the compounds are confirmed by GCMS analysis. Saponification of pet-ether extract of Acacia nilotica has been carried out. Unsaponiflable matter is further purified by column chromatography followed by repeated mixed solvent crystallization to afford heptacosan-1,2,3-triol 2.
Keywords: Acacia nilotica; diester; pentacosane dioic acid; saponification

La0.7Sr0.3MnO3 nanoparticles coated with fatty amine - Rajagopal, Rajashree; Mona, J.; Kale, Sangeeta N.; Bala, Tanushree; Pasricha, Rem; Poddar, P.; Sastry, M.; Bhagavatula L. V. Prasad; Kundaliya, Darshan C.; Ogale, S. B. (Applied Physics Letters, 2006)
We report on the synthesis of La0.7Sr0.3MnO3 (LSMO) nanoparticles having perovskite structure and particle size of the order of 30 rim. The process involves citrate-gel synthesis, size filtering, and; surface coating with a shell of octadecyl amine (ODA) using electrostatic interaction-assisted novel chemical route. Magnetic measurements show the Curie temperature of similar to 360 K establishing the desired stoichiometry and phase. Fourier transform infrared-studies bring out. that the amine group of ODA interacts with the LSMO surface. Refluidization yields uniform redispersion of the coated and dried powder. (c) 2006 American Institute of Physics.

Liquid phase oxidation of alkanes using Cu/Co-perchlorophthalocyanine immobilized MCM-41 under mild reaction conditions - Karandikar, Prashant R.; Chandwadkar, Asha J.; Agashe, M.; Ramgir, N. S.; Sivasanker, S. (Applied Catalysis A-General, 2006)
{Amino-functionalized MCM-41 (NH2-MCM-41) was used to immobilize CU/CO-Cl16PC complex, i.e. Cu/Co-AM(PS) for liquid phase oxidation of alkanes under mild reaction conditions. Higher rates of reaction and better catalytic activity values were obtained for Cu/Co-AM(PS) as compared to Cu/Co-Cl16PC grafted on (i) amino-functionalized SiO2 [
Keywords: Ceramics; Electron microscopy; electronic materials; X-ray diffraction

Low temperature hydrogenation of tetralin over supported rhodium catalysts in supercritical carbon dioxide solvent - Hiyoshi, Norihito; Mine, Eiichi; Rode, Chandrashekhar V.; Sato, Osamu; Shirai, Masayuki (Applied Catalysis A-General, 2006)
Hydrogenation of tetralin was studied over supported rhodium catalysts in supercritical carbon dioxide solvent at 333 K. The results were compared with those in an organic solvent and under neat conditions. Higher cis-decalin yield was obtained in supercritical carbon dioxide solvent than under non-supercritical conditions. It was observed that higher hydrogen concentration at the surface in supercritical carbon dioxide solvent led to fast direct hydrogenation of tetralin to cis-decalin; the flipping of the intermediate, octalin, to give trans-decalin could be prevented. (C) 2006 Elsevier B.V. All rights reserved.
Keywords: cis-decalin; Hydrogen storage; Hydrogenation; Supercritical carbon dioxide; supported rhodium catalysts; tetralin

Low temperature route to prepare LaMnO3 - Daundkar, A.; Kale, Sangeeta N.; Gokhale, Suresh P.; Ravi, V (Materials Letters, 2006)
A combination of digestion and further low temperature calcination to crystallize the product is employed to prepare LaMnO3(LM) ceramics. Freshly co-precipitated lanthanum and manganese hydroxides gel is allowed to react at 100 degrees C under refluxing and stirring conditions for 6-12 h. The X-ray amorphous product so formed is heated at 300 degrees C to form crystalline LM powders. This is the lowest temperature so far reported for the formation of LaMnO3. Transmission electron microscope (TEM) investigations revealed that the average particle size is 50 nm for the calcined powders. (c) 2005 Elsevier B.V All rights reserved.
Keywords: Chemical synthesis; LaMnO3; Precipitation; transmission electron microscopy; X-ray diffraction

Minimum magnetizability principle - Tanwar, Akhilesh; Pal, Sourav; Roy, Debesh Ranjan; Chattaraj, Pratim Kumar (Journal of Chemical Physics, 2006)

Modeling of rotary cement kilns: applications to reduction in energy consumption - Mujumdar, Kaustubh S.; Arora, Amit; Ranade, V. V. (Industrial & Engineering Chemistry Research, 2006)
Rotary cement kilns are used for converting calcineous raw meal into cement clinkers. In this paper, we discuss and evaluate possible ways of reducing energy consumption in rotary cement kilns. A comprehensive one-dimensional model was developed to simulate complex processes occurring in rotary cement Kilns. A modeling strategy comprising three submodels. viz. a model for simulating the variation of bed height in the kiln, a model for simulating reactions and heat transfer in the bed region, and a model for simulating coal combustion and heat transfer in the freeboard region, was developed. Melting and formation of coating within the kiln were accounted for. Combustion of coal in the freeboard region was modeled by accounting for devolatilization, finite-rate gas-phase combustion, and char reaction. The simulated results were validated with the available data from three industrial kilns. The model was then used to understand the influence of various design and operating parameters on kiln performance. Several ways of reducing energy consumption in kilns were then computationally investigated. The model was also used to propose and to evaluate a practical solution of using a secondary shell to reduce energy consumption in rotary cement kilns. Simulation results indicate that varying kiln operating variables, viz. solid flow rate or RPM, can result only in small changes in kiln energetics. Use of a secondary shell over the kiln and energy recovery by passing air through the annular gap between the two appears to be a promising way to achieve significant energy savings. The developed model and the presented results will be useful for enhancing the performance of rotary cement kilns.

Nature and mode of addition of phosphate precursor in the synthesis of aluminum phosphate and its influence on methanol dehydration to dimethyl ether - Kumar, V. Siva; Padmasri, A. H.; Satyanarayana, C. V. V.; Reddy, I. Ajit Kumar; Raju, B. David; Rao, K. S. Rama (Catalysis Communications, 2006)
Four aluminum phosphate catalysts with Al/P = 1 were prepared by precipitation of mixture of aluminum nitrate and phosphate precursor (either phosphoric acid or diammonium hydrogen phosphate) with NH3 and precipitation of aluminum nitrate with NH3 followed by impregnation of phosphate precursor (either phosphoric acid or diammonium hydrogen phosphate). The catalysts were characterized, using different physico-chemical methods viz., BET-S.A., XRD, FT-IR, and NH3-TPD. Al-27 and P-31 MAS NMR spectroscopy was used to characterize selected catalysts in order to find out the presence of Al and P environments. The catalytic conversion of methanol to dimethyl ether was conducted over these catalysts in a temperature range of 448-548 K at atmospheric pressure. AIPO(4) prepared by precipitating the mixture of aluminum nitrate and (NH4)(2)HPO4 with aq. NH3 generated more number of moderate acid sites and showed higher methanol dehydration activity with 100% selectivity to DME at 548 K. (c) 2006 Elsevier B.V. All rights reserved.
Keywords: Al-27 and P-31 MAS NMR; aluminum phosphate; dehydration; dimethyl ether; Methanol; NH3-TPD

Negative thermal expansion in silicalite-1 and zirconium silicalite-1 having MFI structure - Bhange, Deu S.; Ramaswamy, V. (Materials Research Bulletin, 2006)
In situ high temperature X-ray diffraction (HTXRD) studies on monoclinic silicalite-1 (S-1, silica polymorph of ZSM-5) and an orthorhombic metallosilicate molecular sieve, zirconium silicalite-1 (ZrS-1) with MFI structure (Si/Zr = 50) have been carried out using a laboratory X-ray diffractometer with an Anton Parr HTK 1600 attachment. While the structure of the S-I collapsed at 1123 K forming alpha-cristobalite. S-1 and ZrS-1 showed a complex thermal expansion behavior in the temperature range 298-1023 K, ZrS-1 was stable. Powder X-ray diffraction (PXRD) data taken in this region have shown strong negative lattice thermal expansion coefficient, alpha(v) = -6.75 x 10(-6) and - 17.92 x 10(-6) K-1 in the temperature range 298-1023 K-1 for S-1 and ZrS-1 samples, respectively. The thermal expansion behavior of S-1 and ZrS-1 is anisotropic, with the relative strength of contraction along a axis is more than that along b and c axes. Three different thermal expansion regions could be identified in the overall temperature range (298-1023 K) studied, corroborating with the three steps of weight loss in the TG curve of ZrS-1 sample. While the region between 298 and 423 K, displays positive thermal expansion coefficient with alpha(v) = 2.647 x 10(-6) and 4.24 x 10(-6) K-1, the second region between 423 and 873 K shows strong negative thermal expansion (NTE) coefficient alpha(v) = -7.602 x 10(-6) and - 15.04 x 10(-6) K-1, respectively, for S-1 and ZrS-1 samples. The region between 873 and 1023 K, shows a very strong NTE coefficient with alpha(v) = - 12.08 x 10(-6) and -45.622 x 10(-6) K-1 for S-1 and ZrS-1, respectively, which is the highest in the whole temperature range studied. NTE seen over a temperature range 298-1023 K could be associated with transverse vibrations of bridging oxygen atoms in the structure which results in an apparent shortening of the Si-O distances. (C) 2006 Elsevier Ltd. All rights reserved.
Keywords: microporous materials; phase transitions; Thermal expansion; X-ray diffraction

Off-site emergency scenario, a case study from a LPG bottling plant - Ruj, Biswajit; Rehman, Imranur; Bandyopadhya, A. K. (Journal of Loss Prevention in the Process Industries, 2006)
After Bhopal disaster, emergency planning in an industrial area has become inevitable. The off-site emergency plan is an integral part of any major hazard control system. Boiling Liquid Expanding Vapour Explosion (BLEVE) leads to fatal consequences. This paper highlights some salient features of the emergency scenario, which ultimately leads to fireball with enormous pressure wave all around. (C) 2006 Elsevier Ltd. All rights reserved.
Keywords: BLEVE; emergency plan; LPG; off-site

Oxidation of aniline over titania pillared montmorillonite clays - Jagtap, Neelam; Ramaswamy, Veda (Applied Clay Science, 2006)
Titania pillared clays (Ti-PILC) have been synthesized employing conventional stirring (method I) and ultrasonic agitation (method II) techniques followed by hydrothermal treatment. The characterization results revealed the formation of Ti-PILC with significant reduction of time when ultrasonic method was used. Subsequent hydrothermal treatment on the samples has resulted in the increase in the crystallinity and the transformation of anatase TiO2 to rutile TiO2. The rutile phase is more prominent in the samples prepared by stirring method. UV-Vis studies on the samples exhibit blue shift in the absorption band due to the quantum size effect. This indicates that a major part of TiO2 in the pillared clay could be well below 10 nm in size, which is supported by XRD and the average pore size. The pillared clay catalysts have proved to be promising in aniline oxidation with H2O2, selectively forming azoxybenzene under the working conditions. The aniline conversion and the product distribution largely depended on the catalyst concentration, H2O2 to aniline mole ratio, the nature of the solvent and the oxidant. Higher conversion of aniline and greater selectivity for azoxybenzene was obtained with methanol as the solvent. (C) 2006 Elsevier B.V. All rights reserved.
Keywords: aniline oxidation; Azoxybenzene; hydrothermal treatment; pillared clays

Palladium mediated cycloisomerization of sugar alkynols: synthesis of cyclic enol-ethers and spiroketals - Ramana, C. V.; Mallik, Rosy; Gonnade, Rajesh G.; Gurjar, Mukund K. (Tetrahedron Letters, 2006)
Functionalized bicyclic enol-ethers and spiroketals are prepared by Pd catalyzed cycloisomerization of 3-C-alkynylfuranosyl derivatives. Cycloisomerization of differently substituted alkyne derivatives revealed a preference for 6-endo-dig cyclization over 5-exo-dig if the substituent is not sufficiently electron withdrawing. The scope of these cycloisomerizations has been further extended by integrating with conjugate addition. (c) 2006 Elsevier Ltd. All rights reserved.
Keywords: c-alkynylfuranose; cycloisomerization; enol-ether; Palladium; Spiroketal

Phase evolution of NiTiO3 prepared by coprecipitation method - Murugan, A. Vadivel; Samuel, V.; Navale, S. C.; Ravi, V. (Materials Letters, 2006)
A simple coprecipitation technique was used for the preparation of NiTiO3 powders. Ammonium carbonate solution was added to a solution mixture containing stoichiometric amounts of Ni(NO3)(2) and TiOCl2 to precipitate nickel as carbonate and titanium as hydroxide under basic conditions. The precipitate was calcined at different temperatures ranging from 100 to 800 degrees C and phase evolution of NiTiO3 was investigated by X-ray diffraction (XRD) studies. It is observed that nickel titanate was formed at 750 degrees C. For comparison, NiTiO3 was also prepared by standard ceramic process. Particle size and morphology was studied by transmission electron microscopy (TEM). (c) 2005 Elsevier B.V. All fights reserved.
Keywords: Ceramics; Chemical synthesis; Electron microscopy; NiTiO3; Oxides; X-ray diffraction

Photoluminescence studies of Eu3+ doped Y2O3 nanophosphor prepared by microwave hydrothermal method - Murugan, A. Vadivel; Viswanath, Annamraju Kasi; Ravi, V.; Kakade, Bhalchandra A.; Saaminathan, V. (Applied Physics Letters, 2006)
In this letter, the authors report the photoluminescence studies of Eu3+ doped Y2O3 nanorods, which have been synthesized by rapid microwave hydrothermal route within 6 min. The nanostructured Eu3+ doped Y2O3 is characterized by x-ray diffraction, transmission electron microscopy, and photoluminescence. The emission spectrum shows transitions from the excited 5D(0) state to F-7(J) (J=0,1,2,3,4) levels of the Eu3+ ion. The most intense peak around 612 nm is due to the D-5(0)-> F-7(2) transition, expected from the Judd-Ofelt selection rules [B. R. Judd, Phys. Rev. 127, 750 (1962); G. S. Ofelt, J. Chem. Phys. 37, 511 (1962)]. Photoluminescence measurements demonstrated that the nanocrystalline Eu3+:Y2O3 phase shows higher photoluminescence intensity. (c) 2006 American Institute of Physics.

Photooxidation of vulcanized EPDM/montmorillonite nanocomposites - Morlat-Therias, Sandrine; Fanton, Elisabeth; Tomer, Namrata S.; Rana, Sravendra; Singh, R. P.; Gardette, Jean Luc (Polymer Degradation and Stability, 2006)
The photooxidation of a vulcanized ethylene-propylene-diene monomer (EPDM)/montmorillonite nanocomposite as well as EPDM/nanocomposite with stabilizers was studied under accelerated UV-light irradiation (lambda >= 300 nm, 60 degrees C) for different times. The development of functional groups during oxidation was monitored by infrared spectroscopy. Photodegradation of the neat polymer and composites took place and the increases of absorbance in hydroxyl and carbonyl groups with irradiation times and also the decreases of the EPDM unsaturations were measured. The data indicated that the photooxidation products were not changed in the presence of the nanofiller. However, the presence of MMt was observed to dramatically enhance the rate of photooxidation of EPDM with a shortening of the oxidation induction time, leading to a decrease of the durability of the nanocomposites. On the other hand, it was observed that addition of stabilizers, either Tinuvin P or 2-mercaptobenzimidazole, was efficient in inhibiting the degradative effect of MMt. (c) 2006 Elsevier Ltd. All rights reserved.
Keywords: EPDM; Nanocomposite; photooxidation rate; stabilization

Pictet-Spengler cyclization in room temperature ionic liquid: a convenient access to tetrahydro beta-carbolines - Muthukrishnan, Murugan; More, Shivaji V.; Garud, Dinesh R.; Ramana, C. V.; Joshi, Rohini R.; Joshi, Ramesh A. (Journal of Heterocyclic Chemistry, 2006)
1,2,3,4-Tetrahydro-beta-carbolines have been synthesized in moderate to good yields in short reaction time using the ionic liquid [bbim] BF4 as reaction medium and promoter. There was no need for the use of an additional catalyst normally employed in Pictet-Spengler condensation.

Preparation and characterization of sulfonated syndiotactic polystyrene ionomers/organoclay nanocomposites - Govindaiah, P.; Mallikarjuna, S. R.; Ramesh, C. (Macromolecules, 2006)

Preparation and characterization of urea-formaldehyde-pepsin bioconjugate: a new biocatalyst system - Vinod, V. P.; Shinde, Sudhirkumar; D'Britto, Virginia; Shukla, P. G.; Rao, Mala (Biotechnology Progress, 2006)
This study describes the synthesis of urea formaldehyde (UF) microspheres by a dispersion polycondensation polymerization method. These microspheres with proper F/U molar ratio can provide highly reactive groups, capable of further condensation with the amino acid residues of enzyme/proteins. Presence of methylols groups in UF microspheres was confirmed by C-13 NMR study. Pepsin, a proteolytic enzyme, was immobilized on the UF microspheres to form bioconjugate system. As compared to the free enzyme in solution, the pepsin in the bioconjugate system exhibited significantly enhanced pH and temperature stability. The urea-formaldehydepepsin bioconjugate system also exhibited excellent proteolytic activity over eight successive reuse cycles with more than 50% of initial activity. A highlight of this new biocatalyst is the ease with which separation of this biocatalyst from the reaction medium may be achieved by mild centrifugation.

Preparation and performance evaluation of EPDM nanocomposites under accelerated weathering - Rana, Sravendra; Tevtia, Amit K.; Kumar, Bijendra; Singh, R. P. (Journal of Thermoplastic Composite Materials, 2006)
The degradability of ethylene propylene diene monomer (EPDM) nanocomposites, prepared from organically modified montmorillonite (CMMT), is studied under accelerated UV irradiation (lambda >= 290 nm) for different time intervals. The development of functional groups during degradation is monitored by FT-IR spectroscopy whereas, surface changes are studied by scanning electron microscopy (SEM). The effect of clay modifier and clay concentration on the degradability are studied. The degradation of neat polymer and composites taking place traditionally and an increase in carbonyl and hydroxyl groups are observed with irradiation time. Neat EPDM is found to be less degradable than nanocomposites. Degradation products, as seen by FT-IR in nanocomposites are found to be the same as in neat polymer but are generated at a faster rate. According to the experimental results, one can define that both ammonium ion and neat montmorillonite (MMT) accelerate the photo-oxidation of EPDM.
Keywords: carbonyl index; Degradation; EPDM; layered silicates; Nanocomposites; photooxidation

Preparation of nanocrystalline ferroelectric BaBi4Ti4O15 by Pechini method - Murugan, A. Vadivel; Navale, S. C.; Ravi, V. (Materials Letters, 2006)
A gel was formed when an aqueous solution of BaCl2, BiNO3, TiOCl2 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 600 degrees C produced the nano crystallites of ternary oxide, BaBi4Ti4O15 (BBT). The phase contents and lattice parameters were Studied by the powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). The room temperature dielectric constant at I KHz is 90. The ferroelectric hysteresis loop parameters of these samples were also studied by a home built Sawyer-tower circuit. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: dielectric properties; Electron microscopy; ferroelectric properties; powders chemical preparation

Repetitive somatic embryogenesis and plant regeneration in Garcinia indica Choiss - Thengane, Shubhada Ratnakar; Deodhar, Swapna R.; Bhosle, S. V.; Rawal, S. K. (In Vitro Cellular & Developmental Biology-Plant, 2006)
Immature seeds of Garcinia indica Choiss. were excised from immature fruits and cultured on Lloyd and McCown (1980), woody plant medium (WPM) with different combinations of auxins and cytokinins. Somatic embryos were obtained on the media supplemented with 6-benzylaminopurine (BA; 2.2-22.1 mu M) alone or in combination with alpha-naphthalene acetic acid (NAA; 2.6 mu M) with 80% frequency within a period of 2-3 wk. Subculture of embryos on medium containing BA (16.0 mu M) supplemented with indole-3-acetic acid (IAA; 2.8-5.7 mu M) and/or kinetin (4.6 mu M) gave rise to clusters of secondary somatic embryos along with maturation of primary embryos. In subsequent subculture on hormone-free half-strength WPM, the embryo clusters germinated with an increase in the number of secondary somatic embryos. About 70% of somatic embryos germinated into complete plantlets, which were successfully established under greenhouse conditions.
Keywords: Garcinia indica; guttifereae; secondary somatic embryos; seeds; somatic embryos

Response characteristics of conducting polypyrrole bi-layer actuators: role of backing layer polymer - Radhakrishnan, S.; Kar, Swarnendu B. (Sensors and Actuators B-Chemical, 2006)
The response of a bi-layer conducting polymer-based actuator has been studied with respect to various parameters such as backing layer thickness, backing layer modulus, applied voltage, etc. The bending angles for the bi-layer actuators made by depositing, conducting polypyrrole (PPy) films on backing layers using LDPE/LLDPE, SBS, Hytrel, PP, PET materials have been compared. The response of the bi-layer actuators indicates that there is optimum for the backing layer thickness as well as its material modulus together with the thickness of the conducting polymer at which the maximum bending is observed. Other geometrical parameters such as a length to width ratio also influence the response of these actuators and have to be chosen properly for the best actuator performance. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: actuator; bi-layer; conducting polymer; polypyrrole; response

Ring hydrogenation of naphthalene and 1-naphthol over supported metal catalysts in supercritical carbon dioxide solvent - Shirai, M.; Rode, C. V.; Mine, Eiichi; Sasaki, A.; Sato, O.; Hiyoshi, Norihito (Catalysis Today, 2006)
Catalytic ring hydrogenations of naphthalene and 1-naphthol were studied over several supported metal catalysts in supercritical carbon dioxide solvent at low temperature. Higher concentration of hydrogen in supercritical carbon dioxide and lower reaction temperature were responsible for higher catalyst activity and selectivities to the desired partial ring hydrogenated products as compared with those observed in organic solvent for the same catalyst. (c) 2006 Elsevier B.V. All rights reserved.
8th International Conference on Carbon Dioxide Utilization, Univ Oslo, Oslo, NORWAY, JUN 20-23, 2005
Keywords: 1-naphthol; Hydrogenation; Naphthalene; Supercritical carbon dioxide; supported metal catalyst

Role of dopant ions in electrocatalytic oxidation of methanol using conducting polypyrrole electrodes - Radhakrishnan, S.; Adhikari, Arindam (Journal of Power Sources, 2006)
Conducting polypyrrole electrodes obtained by electro-polymerization of pyrrole on vacuum metallized glass substrates are modified by doping with a range of metal halides as dopant ions having different electronegativity. Electro-oxidation of methanol using these electrodes is studied by means of cyclic voltammetry in 0.1 M HCiO(4) as supporting electrolyte. It is found that the electronegativity of the dopant ion plays a very important role in the electrocatalytic activity. Polypyrrole doped with zirconium chloride gives the highest anodic current of 10 mA cm(-2) at the oxidation potential of methanol. The results are explained on the basis of the charge-transfer efficiency at the electrode I electrolyte interface, which is associated with the acceptor state created by the dopant in the semi-conducting polymer. (c) 2005 Published by Elsevier B.V.
Keywords: conducting polymers; electrocatalysis; fuel cells; Methanol oxidation; polypyrrole

Role of halide ions and temperature on the morphology of biologically synthesized gold nanotriangles - Rai, A.; Singh, A.; Ahmad, Absar; Sastry, M. (Langmuir, 2006)
{In this paper, we demonstrate the effect of halide ions on the formation of biogenically prepared gold nanotriangles using the leaf extract of lemongrass (Cymbopogonflextiosus) plant. We have also studied the effect of halide ions on the morphology of biogenic nanotriangles. It has been shown that iodide ions have a greater propensity to transform flat gold nanotriangles into circular disklike structures as compared to other halide ions. The study also suggests that the presence of Cl- ions during the synthesis promotes the growth of nanotriangles, whereas the presence of I- ions distorts the nanotriangle morphology and induces the formation of aggregated spherical nanoparticles. The change in the morphology of gold nanotriangles has been explained in terms of the ability of the halide ions to stabilize or inhibit the formation of (I 11) faces to form [
Keywords: DME steam reforming; fuel cells; Hydrogen; Mixed oxides; supported Ga2O3; XPS

Selective hydrogenation of naphthols to tetralones over supported palladium catalysts in supercritical carbon dioxide solvent - Mine, Eiichi; Hiyoshi, Norihito; Sato, Osamu; Rode, Chandrashekhar V.; Shirai, Masayuki (Chemistry Letters, 2006)
Naphthols were selectively hydrogenated to the corresponding tetralones over supported palladium metal catalysts in super-critical carbon dioxide solvent.

Selective ortho-methylation of phenol with methanol over copper manganese mixed-oxide spinel catalysts - Reddy, A. Satyanarayana; Gopinath, Chinnakonda S.; Chilukuri, Satyanarayana V. (Journal of Catalysis, 2006)
Methylation of phenol with methanol as an alkylating agent to produce 2,6-xylenol was investigated over copper manganese mixed oxide spinels, CuxMn3-xO4 (x = 0, 0.25, 0.5, 0.75, and 1) prepared through co-precipitation. The catalytic activity strongly depends on the composition, acid-base properties, and structural stability. Various parameters, including catalyst composition, reaction temperature, feed composition, and durability of the catalyst during methylation, were investigated. Mainly o-cresol and 2,6-xylenol, along with small amounts of mesitol, were found in the product. A high ortho-selectivity of 100%, with 2,6-xylenol selectivity of 74%, was observed over Cu0.25Mn2.75O4 at 673 K. These catalysts were investigated using various techniques, including BET surface area, XRD, DRS UV-vis, TPD of NH3 and CO2, TPR, and X-ray photoemission spectroscopy (XPS). Powder XRD of the catalysts revealed the formation of copper-manganese spinels with hausmannite (Mn3O4) tetragonal structure, for x = 0-0.5, whereas an increase in copper content (x > 0.5) led to the formation of cubic Cu1.5Mn1.5O4 phase. DRS UV-vis, and FTIR further supported the changes in structural phases observed by XRD. Temperature-programmed desorption Of CO2 and NH3 showed that the catalysts have strong basicity along with weak acidity when x = 0 and 0.25. XPS and XAES analysis revealed the presence of only Cu2+ ions in fresh sample with x = 0.25, whereas for x = 1.0, both Cu1+ and Cu2+ were observed. The deactivation of the catalysts is attributed to structural changes occurring during the reaction. Catalytic activity is correlated with structure, as well as with acid-base properties. (c) 2006 Elsevier Inc. All rights reserved.
Keywords: 2; 6-xylenol; acidity-basicity; copper-manganese oxides; ortho-alkylation; phenol methylation; Spinels