02787nas a2200265 4500008004100000022001400041245019900055210006900254260006800323300001400391490000700405520175200412653001402164653003502178653001302213100002102226700001702247700001502264700001702279700001902296700002802315700002502343700002702368856012602395 2005 eng d a0021-899500aComparison of the pervaporation separation of a water-acetonitrile mixture with zeolite-filled sodium alginate and poly(vinyl alcohol)-polyaniline semi-interpenetrating polymer network membranes0 aComparison of the pervaporation separation of a wateracetonitril a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcJUN a1968-19780 v963 a

The pervaporation (PV) separation performance of ZSM-5- and Na-Y-type zeolite-filled sodium alginate (NaAlg) membranes were compared with those of pure NaAlg and semi-interpenetrating polymer network (semi-IPN) membranes of poly(vinyl alcohol) (PVA) with polyaniline (PANI) for the dehydration of acetonitrile. The PV separation characteristics of the zeolite-filled membranes showed a dependence on the nature of the zeolites. The variation of the acidity function of the ZSM-5 zeolite had an influence on the flux and selectivity of the membranes when compared to unfilled membranes. The crosslinked membranes were characterized by differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Increasing the PANI content of the semi-IPN network increased the separation selectivity. Among the NaAlg membranes, the plain NaAlg membrane showed the highest selectivity of 414 at 30 mass % water in the feed mixture, whereas the Na-Y- and ZSM-5 (40)-filled NaAlg membranes exhibited much lower values of selectivity, that is, 7.3 and 4.3, respectively for 30 mass % water in the feed. When the flux and selectivity data of ZSM-5 (250)-filled NaAlg membranes were compared with that of Na-Y- or ZSM-5 (40)-filled NaAlg membranes, a noticeable increase in the selectivity for the ZSM-5 (250)filled NaAlg membrane was observed, but a somewhat comparable flux was observed compared to the plain NaAlg membrane. For the first time, PANI was polymerized with PVA to yield a semi-IPN. The total flux and water flux increased systematically, whereas the selectivity decreased greatly from 251.87 to 5.95 with increasing amounts of water in the feed. (c) 2005 Wiley Periodicals, Inc.

10aDiffusion10ainterpenetrating network (IPN)10azeolites1 aNaidu, B., V. K.1 aBhat, S., D.1 aSairam, M.1 aWali, A., C.1 aSawant, D., P.1 aHalligudi, Shivaraj, B.1 aMallikarjuna, N., N.1 aAminabhavi, Tejraj, M. uhttps://library.ncl.res.in/content/comparison-pervaporation-separation-water-acetonitrile-mixture-zeolite-filled-sodium-001885nas a2200229 4500008004100000022001400041245011200055210006900167260006800236300001400304490000700318520107500325653001401400653001401414653001301428100001801441700002201459700001601481700001901497700001701516856012201533 2005 eng d a0021-899500aSwelling behavior and diffusion studies of high-water-retaining acrylamide/potassium methacrylate hydrogels0 aSwelling behavior and diffusion studies of highwaterretaining ac a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcMAY a1153-11640 v963 a

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.

10aDiffusion10ahydrogels10aswelling1 aMohan, Y., M.1 aMurthy, P., S. K.1 aRao, K., M.1 aSreeramulu, J.1 aRaju, K., M. uhttps://library.ncl.res.in/content/swelling-behavior-and-diffusion-studies-high-water-retaining-acrylamidepotassium-002309nas a2200229 4500008004100000022001400041245010400055210006900159260007300228300001200301490000800313520146100321653001401782653001901796653002201815653001301837653002201850100002801872700002501900700002201925856013201947 2006 eng d a0376-738800aEnhancement of gas permeation properties of polybenzimidazoles by systematic structure architecture0 aEnhancement of gas permeation properties of polybenzimidazoles b aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC a161-1690 v2863 a

Systematic structural variations in thermally stable polybenzimidazole (PBI) are explored that led to a substantial improvement in gas permeation properties. Physical property determinations revealed that incorporation of hexafluoroisopropylidene and tert-butyl groups led to amorphous polymers with slightly lowered thermal stability and decreased chain packing. PBI based on 4,4'-(hexafluoroisopropylidene)bis(benzoic acid) and 5-tert-butyl isophthalic acid exhibited 10-40 times higher permeability, while changes in selectivities for industrially important pairs ranged from modest decrease of 75% or less than that of PBI based on isophthalic acid. The O-2/N-2 selectivity was almost doubled in case of PBI based on 5-tert-butyl isophthalic acid. Gas diffusion coefficients were estimated from solubility and permeability coefficient determinations. These, along with dual-mode sorption parameters estimated from sorption isotherms provided an insight towards variations in permeation behavior. The permeability predictions for heavier gases in isophthalic acid based PBI correlated well with physical properties. The occurrence of permeation characteristics (especially P-H2 and P-H2/P-N2) near Robeson's upper bound, high thermal stability and good solvent solubility achieved by these structural modifications depicted the potential of this family of polymers as gas separation membrane materials. (c) 2006 Elsevier B.V. All rights reserved.

10aDiffusion10aGas permeation10aPolybenzimidazole10aSorption10athermal stability1 aKumbharkar, Santosh, C.1 aKaradkar, Prasad, B.1 aKharul, Ulhas, K. uhttps://library.ncl.res.in/content/enhancement-gas-permeation-properties-polybenzimidazoles-systematic-structure-architecture-002183nas a2200253 4500008004100000022001400041245014700055210006900202260006800271300001400339490000700353520122700360653002801587653001401615653001901629653001701648653001701665653001601682653003301698100002301731700002501754700002201779856012801801 2007 eng d a0887-626600aEffect of substituent polarity, bulk, and substitution site toward enhancing gas permeation in dibromohexafluorobisphenol-A based polyarylates0 aEffect of substituent polarity bulk and substitution site toward a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcDEC a3156-31680 v453 a

The gas permeation properties of polyarylates were tuned by varying nature and site of substituents present on both of its monomers, viz., bisphenol and dicarboxylic acid. The phenyl rings of hexafluorobisphenol-A were substituted in asymmetric manner by polar bromine to obtain dibromohexafluorobisphenol-A. This bisphenol was polymerized with equimolar mixture of iso- and terephthalic acid (base case), bromo- and nitroterephthalic acid (polar group substituted acids), 4,4'-hexafluoroisopropylidene bis(benzoic acid), and t-butyl isophthalic acid (bulky group containing acids). Physical properties and gas permeation properties of these polyarylates were investigated to assess combined effects of asymmetric nature of bisphenol substitution, polar nature of substituent bromine, hexafluoroisopropylidene group present at the bridge position of bisphenol, and substituent present on the acid moiety. The combination of these substituent types led these polyarylates to lie near Robeson upper bound. The gas sorption analysis and estimation of diffusivity in these polyarylates shed a light on observed variations in gas permeation properties by attempted structural variations. (c) 2007 Wiley Periodicals, Inc.

10aasymmetric substitution10aDiffusion10aGas permeation10agas sorption10apolyarylates10aselectivity10astructure-property relations1 aIshole, Yogesh, S.1 aKaradkar, Prasad, R.1 aKharul, Ulhas, K. uhttps://library.ncl.res.in/content/effect-substituent-polarity-bulk-and-substitution-site-toward-enhancing-gas-permeation-002613nas a2200265 4500008004100000022001400041245009200055210006900147260007300216300001200289490000800301520170400309653001402013653001302027653001502040653001702055653001302072100002502085700002202110700002202132700002202154700002302176700002602199856012202225 2007 eng d a0376-738800aGas sorption and transport in polyarylates: effect of substituent symmetry and polarity0 aGas sorption and transport in polyarylates effect of substituent aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcOCT a244-2510 v3033 a

The gas sorption properties of polyarylates based on bisphenol-A possessing symmetric/asymmetric substitution by nonpolar -CH3 group and symmetrically linked terephthalic acid were examined. The effects of substitution of polar bromine on terephalic acid moiety of polyarylate based on asymmetrically substituted bisphenol were also studied for physical, sorption and transport properties. The estimation of dual mode sorption parameters, solubility and diffusion coefficient revealed that nature of the substituent and substitution type plays a crucial role in depicting permeation properties. An asymmetric substitution by -CH3 group increased solubility coefficient of pure gases (N-2, O-2, CH4 and CO2) up to 27% and symmetric substitution increased the same up to 106%. This was coupled with 7-35% increase in solubility selectivity in both cases of substitution, which ascertained the usefulness of methyl group substitution in polyarylates based on terephalic acid. The pressure dependency of solubility coefficients and solubility selectivity was also investigated for these polyarylates. The sorption and transport properties of these polyarylates correlated well with physical properties of polyarylates and gases studied. The sorption/desorption kinetics of symmetrically substituted TMBisA-T was performed in order to deduce time dependent sorption behavior and to evaluate diffusivity coefficient. The apparent diffusion coefficients from sorption kinetics, desorption kinetics and from steady-states permeation-sorption were compared. The diffusion coefficients of CH4 and N-2 deduced by these methods correlated well with each other. (C) 2007 Elsevier B.V. All rights reserved.

10aDiffusion10akinetics10apermeation10apolyarylates10aSorption1 aKaradkar, Prasad, B.1 aKharul, Ulhas, K.1 aBhole, Yogesh, S.1 aBadhe, Yogesh, P.1 aTambe, Sanjeev, S.1 aKulkarni, Bhaskar, D. uhttps://library.ncl.res.in/content/gas-sorption-and-transport-polyarylates-effect-substituent-symmetry-and-polarity-001694nas a2200217 4500008004100000022001400041245007100055210006900126260007600195300001400271490000700285520093700292653001401229653001601243653002701259100002301286700002101309700002301330700002101353856010201374 2008 eng d a0887-626600aSelf-diffusion coefficient of ring polymers in semidilute solution0 aSelfdiffusion coefficient of ring polymers in semidilute solutio aCOMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USAbWILEY-BLACKWELLcNOV a2370-23790 v463 a

In a topologically constraining environment the size of a flexible nonconcatenated ring polymer (macrocycles) and its dynamics are known to differ from that of linear polymers. Hence, the diffusion coefficient of ring polymers can be expected to be different from linear chains. We present here scaling arguments for the concentration and molecular weight dependence of self-diffusion coefficient of ring polymers in semidilute solutions, and show that contrary to expectations these scaling relations are identical to what is known for linear polymers. At higher concentrations excluded volume interactions arising from possibilities of segmental overlap can become effective for large ring polymers. In this regime the diffusion coefficient of large ring polymers shows a relatively weaker dependence on concentration and molecular weight. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2370-2379, 2008

10aDiffusion10aMacrocycles10aMonte Carlo simulation1 aIyer, Balaj, V. S.1 aShanbhag, Sachin1 aJuvekar, Vinay, A.1 aLele, Ashish, K. uhttps://library.ncl.res.in/content/self-diffusion-coefficient-ring-polymers-semidilute-solution-002030nas a2200253 4500008004100000022001400041245006800055210006400123260012500187300001100312490000800323520114800331653001401479653002001493653002001513653001701533653001401550653002401564653001801588100003101606700002101637700002701658856009101685 2009 eng d a0021-960600aPolymer crystallization in the presence of ``sticky'' additives0 aPolymer crystallization in the presence of sticky additives aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScAUG a0749050 v1313 a

The effect of ``sticky'' additives (viz., those that have attractive interactions with the polymer) on polymer crystallization, has been investigated by dynamic Monte Carlo (DMC) simulations. Additive-polymer attractive interactions result in a slowing down of the polymer chain diffusivity in the melt state. Our results show that with increasing additive stickiness, polymer crystallinity decreases monotonically, and thinner crystallites form, viz., crystallization is inhibited by the presence of sticky additives. Unusually, the observed ``specific heat'' peak at the phase transition shows nonmonotonic behavior with additive stickiness, and exhibits a maximum for intermediate values of additive stickiness. While the origins of this unexpected behavior are not clear, we show that it correlates with a large interchange between crystalline and amorphous states of the monomers, in the vicinity of the additives. At this intermediate additive stickiness, we also find that crystallization follows a qualitatively different route-crystallinity shows a non-Avrami-like evolution, unlike the case at low or high additive stickiness.

10aAdditives10aamorphous state10acrystallisation10acrystallites10aDiffusion10aMonte Carlo methods10apolymer melts1 aDasmahapatra, Ashok, Kumar1 aNanavati, Hemant1 aKumaraswamy, Guruswamy uhttps://library.ncl.res.in/content/polymer-crystallization-presence-sticky-additives-002150nas a2200217 4500008004100000022001400041245011100055210006900166260007300235300001200308490000800320520134100328653001401669653001901683653001901702653002201721653001301743100002801756700002201784856012601806 2010 eng d a0376-738800aInvestigation of gas permeation properties of systematically modified polybenzimidazoles by N-substitution0 aInvestigation of gas permeation properties of systematically mod aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL a134-1420 v3573 a

Gas permeation behavior of a series of thermally stable N-substituted polybenzimidazoles by systematically varying bulk and flexibility of the substituent was investigated. Two different PBIs having variation in their acid moiety, viz., PBI-I (based on isophthalic acid) and PBI-BuI (based on 5-tert-butyl isophthalic acid) were selected for N-substitution by alkyl groups possessing different bulk and flexibility. These substituent groups were methyl, n-butyl, methylene trimethylsilane and 4-tert-butylbenzyl. Pure gas sorption and permeability using H(2), N(2), O(2), CH(4) and CO(2) were investigated and correlated with physical properties of formed polymers. Estimation of dual-mode sorption parameters, coefficients of sorption, permeability and diffusion for different gases provided an insight towards effects of nature of a substituent group and parent PBI on governing gas sorption and permeation properties. By changing the substituent group, diffusivity coefficients was found to vary to a larger extent than the solubility coefficient. This significantly enhanced gas permeability for different gases by 1.2-129 times than that of parent PBIs. The permselectivity P(O2)/P(N2) was increased (up to 237%), while for other gas pairs, it was decreased to a different extent. (C) 2010 Elsevier B.V. All rights reserved.

10aDiffusion10aGas permeation10aN-Substitution10aPolybenzimidazole10aSorption1 aKumbharkar, Santosh, C.1 aKharul, Ulhas, K. uhttps://library.ncl.res.in/content/investigation-gas-permeation-properties-systematically-modified-polybenzimidazoles-n-002284nas a2200229 4500008004100000022001400041245008300055210006900138260007300207300001200280490000800292520149100300653002101791653001401812653001901826653001901845653001101864653001301875100002801888700002201916856011601938 2010 eng d a0376-738800aNew N-substituted ABPBI: synthesis and evaluation of gas permeation properties0 aNew Nsubstituted ABPBI synthesis and evaluation of gas permeatio aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcSEP a418-4250 v3603 a

Aromatic poly(2,5-benzimidazole), ABPBI was post-modified for the first time to produce organosoluble N-substituted ABPBI. This modification was carried out by N-substitution of ABPBI with bulky alkyl groups, viz., 4-tert-butylbenzyl and methylene trimethylsilyl in an attempt to utilize high rigidity of ABPBI towards gas permeation. These substituted polymers exhibited solubility in common organic solvents, enhancing their processability than ABPBI, which is soluble only in acidic solvents. Considerable decrease in chain packing density led to increase in gas sorption as that of unsubstituted ABPBI. The permeability of pure gases of commercial significance (He, H(2), N(2), O(2), CH(4) and CO(2)) were high, coupled with attractive selectivities. In comparison to conventional PBI, methylene trimethylsilyl substituted ABPBI led to considerably high (33 folds) CO(2) permeability with almost similar selectivity (P(CO2)/P(N2) approximate to 33). Feasibility of these N-substituted ABPBIs to be converted in to required membrane form along with its considerably higher permeation properties depicted the potential of this polymer to be used as gas separation material. Gas diffusion coefficients were estimated from solubility and permeability coefficient. These, along with dual-mode sorption parameters estimated from sorption isotherms provided an insight towards variations in permeation behavior caused by the substitution. (C) 2010 Elsevier B.V. All rights reserved.

10a5-benzimidazole)10aDiffusion10aGas permeation10aN-Substitution10aPoly(210aSorption1 aKumbharkar, Santosh, C.1 aKharul, Ulhas, K. uhttps://library.ncl.res.in/content/new-n-substituted-abpbi-synthesis-and-evaluation-gas-permeation-properties-002525nas a2200289 4500008004100000020002200041022001400063245005200077210005200129260021600181300001200397490000900409520151800418653000801936653001401944653001301958653001901971653001101990653002302001100002102024700002302045700002502068700002002093700002002113700001602133856008602149 2010 eng d a978-0-7354-0772-5 a0094-243X00aShear induced diffusion in dense granular flows0 aShear induced diffusion in dense granular flows a2 Huntington Quadrangle, STE 1NO1, Melville, NY 11747-4501 USAbIUTAM; ISIMM; Italian Inst Higher Math; US Natl Sci Fdn; Reg Council Reggio Calabria; Prov Reggio Calabria; Mediterranean Univ Reggio CalabriacJUN a221-2290 v12273 a

The dynamics of dense granular flows subjected to gravity induced shear are investigated experimentally using the refractive index matching technique. The system consists of grains flowing inside a bin with a rectangular cross-section and sheared by a rough boundary on one side and smooth boundaries on the remaining sides. The particles flow within a viscous interstitial liquid having the same refractive index as particles and are imaged in the bulk using laser fluorescence. The particle positions are identified very accurately and tracked over long durations to obtain the mean and fluctuating properties. The shear is observed to be non-linear and localized in a region of 3 to 4 particles near the boundary. The boundary imposes a packing order, and the grains are observed to flow in layers, parallel to the shearing boundary, which get progressively more disordered with distance from the walls. We have also carried out soft particle simulations in a equivalent system incorporating the Cundall-Strack contact model between the particles and ignoring the hydrodynamic effects of the interstitial liquid to understand the effect of particle friction coefficient, elasticity, contact model and polydispersity on the mean and fluctuating flow properties. We find the mean velocity and the number density of the particles as a function of flow cross-section and the particle fluctuation properties observed in the experiments and the simulations to in very good agreement after appropriate scaling.

10aDEM10aDiffusion10agranular10aindex matching10aLAMMPS10alaser fluorescence1 aOrpe, Ashish, V.1 aRycroft, Chris, H.1 aKudrolli, Arshad, A.1 aGoddard, J., D.1 aJenkins, J., T.1 aGiovine, P. uhttps://library.ncl.res.in/content/shear-induced-diffusion-dense-granular-flows-002353nas a2200229 4500008004100000022001400041245013300055210006900188260006700257300001400324490000800338520147800346653003401824653002401858653001401882653002501896653001501921100002201936700002201958700001601980856012701996 2012 eng d a0021-899500aEffect of the surface roughness of conducting polypyrrole thin-film electrodes on the electrocatalytic reduction of nitrobenzene0 aEffect of the surface roughness of conducting polypyrrole thinfi a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcAUG a1875-18810 v1253 a

Conducting polypyrrole (PPy) thin-film electrodes were prepared by the electropolymerization of pyrrole on gold-coated glass plates. Films of various roughnesses were obtained by the variation of the scan rates during electropolymerization. These thin films were modified by doping with 6mM of the dopant NiCl2. The surface morphology of the films was studied by scanning electron microscopy and atomic force microscopy (AFM), which suggested films prepared with a high scan rate were rougher in nature than the films produced with a low scan rate. The electrocatalytic reduction of nitrobenzene was carried out with these electrodes with the cyclic voltammetry technique in acetonitrile containing 0.1M HClO4 as a supporting electrolyte. The various results obtained show that the conducting PPy thin-film electrodes were catalytically active toward the electroreduction process. The modified PPy film electrodes doped with NiCl2 were more active toward nitrobenzene electroreduction than the PPy film alone. The results indicate that the roughness of the films played a very important role in determining their catalytic activity. The PPy films that were more rough in nature were catalytically more active than the smooth films; this may have been due to the availability of more reactive sites in the case of rough films. The apparent diffusion coefficients of the PPy film electrodes were also calculated. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

10aatomic force microscopy (AFM)10aconducting polymers10aDiffusion10asurface modification10aThin films1 aAdhikari, Arindam1 aRadhakrishnan, S.1 aVijayan, M. uhttps://library.ncl.res.in/content/effect-surface-roughness-conducting-polypyrrole-thin-film-electrodes-electrocatalytic-002013nas a2200241 4500008004100000022001400041245008600055210006900141260009000210300001000300490000700310520116100317653001401478653001201492653002001504653001901524653001901543653001701562653002201579100002201601700003201623856011601655 2012 eng d a0363-904500apH Sensitive graft copolymers for zero order drug release: a mechanistic analysis0 apH Sensitive graft copolymers for zero order drug release a mech aTELEPHONE HOUSE, 69-77 PAUL STREET, LONDON EC2A 4LQ, ENGLANDbINFORMA HEALTHCAREcJAN a73-830 v383 a

Aliphatic polyesters containing pendent unsaturation were synthesized by the polycondensation of a diol, dicarboxylic acid and glycidyl methacrylate. Grafting methacrylic acid (MAA) resulted in graft copolymers containing polyester backbone and MAA grafts. Depending on composition, the polymers swelled extensively and eroded or dissolved at near neutral pH but remained in collapsed state at acidic pH. Three representative drugs differing in solubility, viz., Diltiazem hydrochloride (DH), Indomethacin (IM) and Verapamil hydrochloride (VH) were released at constant rate from tablets made by compressing spray-dried microparticles. The release of DH at constant rate has been attributed to increase in diffusion coefficient of the drug from the swollen layer of matrix. The release of IM and VH at constant rate was governed by erosion and was enhanced in matrices which undergo dissolution. The release rate was enhanced with increasing MAA content and the frequency of grafts along the polyester backbone. Once a day dosage forms for drugs differing in solubility have been developed using a single polymer matrix which is easy to manufacture.

10aDiffusion10aerosion10aGraft copolymer10amatrix tablets10amicroparticles10aspray drying10asustained release1 aMuthusamy, Ramesh1 aKulkarni, Mohan, Gopalkrish uhttps://library.ncl.res.in/content/ph-sensitive-graft-copolymers-zero-order-drug-release-mechanistic-analysis-001863nas a2200265 4500008004100000022001400041245009900055210006900154260007900223300001400302490000800316520096200324653001701286653002001303653001401323653001101337653002101348653001101369100002101380700002401401700002001425700001801445700001501463856011901478 2013 eng d a0273-228900aBiodegradation of phenol by the yeast candida tropicalis: an investigation by NMR spectroscopy0 aBiodegradation of phenol by the yeast candida tropicalis an inve a999 RIVERVIEW DRIVE SUITE 208, TOTOWA, NJ 07512 USAbHUMANA PRESS INCcAPR a2029-20370 v1693 a

The process of phenol biodegradation by the yeast Candida tropicalis NCIM 3556 in aqueous medium was studied by H-1, C-13, and DOSY NMR techniques. Samples at regular intervals were centrifuged to separate the cells, and H-1 spectral data were collected at 400 MHz. Though a gradual decrease in the concentration of phenol was observed, after an incubation period of similar to 8 h, formation of any intermediate products could not be detected. Experiments carried out with uniformly C-13-labeled phenol also failed to detect formation of any carboxylic acid intermediates during degradation. The studies indicated that the phenol was completely degraded to carbon dioxide and water in approximately 20 h. Self-diffusion coefficient measurements showed that the lifetime of phenol in the bound form is too small to impart any change in its diffusion behavior and the intermediates formed are converted to carbon dioxide and water at a very fast rate.

10abiocatalysis10aCarboxylic acid10aDiffusion10aEnzyme10aNMR spectroscopy10aphenol1 aPhalgune, U., D.1 aRajamohanan, P., R.1 aGaikwad, B., G.1 aVarma, R., J.1 aGeorge, S. uhttps://library.ncl.res.in/content/biodegradation-phenol-yeast-candida-tropicalis-investigation-nmr-spectroscopy-0