02175nas a2200253 4500008004100000022001400041245011500055210006900170260008000239300001400319490000800333520125000341653002001591653002101611653001901632653000901651653002601660653001201686100002501698700001801723700001901741700003001760856013101790 2008 eng d a1618-264200aImaging the stomatal physiology of somatic embryo-derived peanut leaves by scanning electrochemical microscopy0 aImaging the stomatal physiology of somatic embryoderived peanut  aTIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANYbSPRINGER HEIDELBERGcJUL a2227-22330 v3913 a

The stomatal physiology, chlorophyll distribution and photosynthetic activity of somatic embryo (SE)- and seedling-derived peanut plants grown in vitro (test tube-grown) and extra vitrum (soil-grown) are investigated using scanning electrochemical microscopy (SECM). This SECM imaging is performed in two different feedback modes, corresponding to oxygen evolution and chlorophyll distribution. More specifically, the oxygen evolution profiles of the in vitro leaves indicate important differences in leaf anatomy between the SE- and seedling-derived leaves. On the other hand, the chlorophyll distribution images show individual stomata of size ca. 27 +/- 5 mu m. Further studies on senescing (aged) leaves reveal interesting voltammograms that vary widely over the stomatal complexes and the surrounding tissues, probably due to the release of electroactive metabolites during chlorophyll breakdown when the leaves turn yellow. Thus, the present investigation could open up new opportunities for characterizing botanical systems using electroanalytical techniques. In addition, it could provide further insights into various areas of current relevance, including signal transduction, cell fate/differentiation and developmental biology.

10aleaf senescence10aoxygen evolution10aphotosynthesis10aSECM10asomatic embryogenesis10astomata1 aParthasarathy, Meera1 aSingh, Shweta1 aHazra, Sulekha1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/imaging-stomatal-physiology-somatic-embryo-derived-peanut-leaves-scanning-electrochemical-002611nas a2200253 4500008004100000022001400041245019100055210006900246260013700315300001200452490000700464520149700471653002201968653003001990653002102020653004202041653001202083653003102095100002602126700002102152700002802173700003002201856012602231 2008 eng d a0956-566300aInvertase inhibition based electrochemical sensor for the detection of heavy metal ions in aqueous system: application of ultra-microlelectrode to enhance sucrose biosensor's sensitivity0 aInvertase inhibition based electrochemical sensor for the detect aOXFORD FULFILLMENT CENTRE THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER ADVANCED TECHNOLOGYcDEC a657-6640 v243 a

We are reporting fabrication and characterization of electrochemical sucrose biosensor using ultra-microelectrode (UME) for the detection of heavy metal ions (Hg(II), Ag(I), Pb(II) and Cd(II)). The working UME, with 25 mu m diameter, was modified with invertase (INV, EC: 3.2.1.26) and glucose oxidase (GOD, EC: 1.1.3.4) entrapped in agarose-guar gum. The hydrophilic character of the agarose-guar gum composite matrix was checked by water contact angle measurement. The atomic force microscopy (AFM) images of the membranes showed proper confinement of both the enzymes during co-immobilization. The dynamic range for sucrose biosensor was achieved in the range of 1 x 10(-10) to 1 x 10(-7) M with lower detection limit 1 x 10(-10) M at pH 5.5 with 9 cycles of reuse. The spectrophotometric and electrochemical studies showed linear relationship between concentration of heavy metal ions and degree of inhibition of invertase. The toxicity sequence for invertase using both methods was observed as Hg(2+) > Pb(2+) > Ag(+) > Cd(2+). The dynamic linear range for mercury using electrochemical biosensor was observed in the range of 5 x 10(-10) to 12.5 x 10(-10) M for sucrose. The lower detection limit for the fabricated biosensor was found to be 5 x 10(-10) M. The reliability of the electrochemical biosensor was conformed by testing the spike samples and the results were comparable with the conventional photometric DNSA method. (C) 2008 Elsevier B.V. All rights reserved.

10aCo-immobilization10aElectrochemical biosensor10aHeavy metal ions10aInvertase (INV)-glucose oxidase (GOD)10aMercury10aUltra-microelectrode (UME)1 aBagal-Kestwal, Dipali1 aKarve, Meena, S.1 aKakade, Bhalchandra, A.1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/invertase-inhibition-based-electrochemical-sensor-detection-heavy-metal-ions-aqueous-002367nas a2200217 4500008004100000022001400041245015500055210006900210260010200279300001200381490000800393520150000401653002301901653001201924653001101936653001301947653000901960100002501969700003001994856012502024 2009 eng d a0253-413400aImaging hydrogen oxidation activity of catalyst-coated perfluoro sulfonic acid-polymer electrolyte membranes using scanning electrochemical microscopy0 aImaging hydrogen oxidation activity of catalystcoated perfluoro  aC V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIAbINDIAN ACAD SCIENCEScSEP a719-7250 v1213 a

Scanning Electrochemical Microscopy (SECM) is a unique technique for studying fast heterogeneous kinetics and to map reactivity gradients along the surface of an electrocatalyst, especially when it involves multiple surface sites of varying reactivity. It combines the dual advantages offered by ultramicroelectrode (UME) voltammetry in terms of reduced ohmic drop and insignificant double layer charging contribution with the advantages of imaging by rastering the UME across an electro-active surface. In this work, we demonstrate these distinctive features of SECM in evaluating reactivity gradients on catalyst (Pt/C) coated NafionA (R) films towards hydrogen oxidation activity, a reaction of immense technological relevance. Imaging has been performed in the feedback mode by allowing H(2) evolution at the tip (25 A mu m Pt UME), which is reoxidized at the substrate electrode containing Pt/C-Nafion film. Interesting distribution in H(2) oxidation activity has been observed as a function of potential applied to the Pt/C-Nafion film. In addition, a plot of normalized tip current versus the substrate electrode potential indicates the effect of potential-induced reactivity change in the catalyst-coated membranes. The results of the present investigation are believed to be useful to H(2)/O(2) PEM fuel cells with respect to evaluating reactivity gradients of catalyst-coated polymer electrolyte membranes, which is important to rectify problems related to catalyst utilization.

10ahydrogen oxidation10aImaging10aNafion10aplatinum10aSECM1 aParthasarathy, Meera1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/imaging-hydrogen-oxidation-activity-catalyst-coated-perfluoro-sulfonic-acid-polymer-002675nas a2200205 4500008004100000022001400041245013400055210006900189260011000258300001400368490000700382520180100389100002102190700002602211700002702237700002202264700002402286700003002310856012902340 2011 eng d a0959-942800aImproved performance of phosphonated carbon nanotube-polybenzimidazole composite membranes in proton exchange membrane fuel cells0 aImproved performance of phosphonated carbon nanotubepolybenzimid aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAPR a7223-72310 v213 a

Development of thermally stable polymer electrolyte membranes with higher proton conductivity as well as mechanical stability is a key challenge in commercializing PEM fuel cells operating above 100 degrees C. Polybenzimidazole membranes are one of the promising candidates in this category although with limited mechanical stability and moderate proton conductivity. Here the incorporation of functionalized MWCNT is shown to increase both these key parameters of the polybenzimidazole membranes. Further, formation of a domain like structure after the incorporation of phosphonated MWCNTs (P-MWCNTs) in phosphoric acid doped polybenzimidazole membranes is demonstrated. The enhanced performance has been attributed to the formation of proton conducting networks that formed along the sidewalls of P-MWCNTs with a domain size of 17 nm as estimated from the small angle X-ray scattering measurements. Membrane electrode assembly (MEA) impedance measurements further reveal that the activation energy of oxygen reduction reaction (ORR) reduced for the composite membranes with enhanced proton conductivity. In addition, the mechanical strength measurements reveal a significant improvement in the yield strength and ultimate strength. Also, the mechanical strength of the composite membrane has been increased significantly as indicated by the improvement in the ultimate strength from 65 MPa to 100 MPa for the pristine and composite membranes, respectively. The optimum loading of P-MWCNTs is found to be 1% as inferred from the polarization measurements carried out using pure hydrogen and oxygen. Thus, this study provides a unique opportunity to tune the properties of polymer electrolytes to prepare application oriented hybrid membranes using CNTs with tailor-made functional groups.

1 aKannan, Ramaiyan1 aKagalwala, Husain, N.1 aChaudhari, Harshal, D.1 aKharul, Ulhas, K.1 aKurungot, Sreekumar1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/improved-performance-phosphonated-carbon-nanotube-polybenzimidazole-composite-membranes-001109nas a2200169 4500008004100000022001400041245011100055210006900166260011000235300001400345490000700359520036900366100002400735700002400759700003000783856012600813 2012 eng d a1359-734500aIn situ electrochemical organization of CdSe nanoclusters on graphene during unzipping of carbon nanotubes0 aIn situ electrochemical organization of CdSe nanoclusters on gra aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcFEB a3088-30900 v483 a

In situ decoration of very small CdSe quantum dots on graphene nanoribbons (GNRs) has been achieved during the electrochemical unzipping of single walled carbon nanotubes. Critical parameters like the width of the GNRs, size distribution of quantum dots and their organization on GNRs have been shown to be strongly dependent on the electric field and time.

1 aDebgupta, Joyashish1 aShinde, Dhanraj, B.1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/situ-electrochemical-organization-cdse-nanoclusters-graphene-during-unzipping-carbon-0