sanjay nayak - Academia.edu (original) (raw)
Papers by sanjay nayak
Journal of Coatings Technology and Research, 2011
Corrosion resistance behavior of sol-gelderived organic-inorganic nanotitania-silica composite co... more Corrosion resistance behavior of sol-gelderived organic-inorganic nanotitania-silica composite coatings was studied. Hybrid sol was prepared from Ti-isopropoxide and N-phenyl-3-aminopropyl triethoxy silane. The structure, morphology, and properties of the coating were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermo gravimetric analysis. The corrosion performances of the sol-gel-coated samples were investigated by electrochemical impedance spectroscopy (EIS) and standard salt spray tests. The hybrid coatings were found to be dense, more uniform, and defect free. In addition, the coatings also proved its excellent corrosion protection on phosphated steel sheet.
Journal of Biological Chemistry, 2005
G␥ subunits modulate several distinct molecular events involved with G protein signaling. In add... more G␥ subunits modulate several distinct molecular events involved with G protein signaling. In addition to regulating several effector proteins, G␥ subunits help anchor G␣ subunits to the plasma membrane, promote interaction of G␣ with receptors, stabilize the binding of GDP to G␣ to suppress spurious activation, and provide membrane contact points for G protein-coupled receptor kinases. G␥ subunits have also been shown to inhibit the activities of GTPase-activating proteins (GAPs), both phospholipase C (PLC)-s and RGS proteins, when assayed in solution under single turnover conditions. We show here that G␥ subunits inhibit G protein GAP activity during receptor-stimulated, steady-state GTPase turnover. GDP/GTP exchange catalyzed by receptor requires G␥ in amounts approximately equimolar to G␣, but GAP inhibition was observed with superstoichiometric G␥. The potency of inhibition varied with the GAP and the G␣ subunit, but half-maximal inhibition of the GAP activity of PLC-1 was observed with 5-10 nM G␥, which is at or below the concentrations of G␥ needed for regulation of physiologically relevant effector proteins. The kinetics of GAP inhibition of both receptor-stimulated GTPase activity and single turnover, solution-based GAP assays suggested a competitive mechanism in which G␥ competes with GAPs for binding to the activated, GTP-bound G␣ subunit. An N-terminal truncation mutant of PLC-1 that cannot be directly regulated by G␥ remained sensitive to inhibition of its GAP activity, suggesting that the G␥ binding site relevant for GAP inhibition is on the G␣ subunit rather than on the GAP. Using fluorescence resonance energy transfer between cyan or yellow fluorescent protein-labeled G protein subunits and Alexa532-labeled RGS4, we found that G␥ directly competes with RGS4 for high-affinity binding to G␣ i-GDP-AlF 4. G␥ subunits perform diverse roles in G protein-mediated signaling, almost all of which are based on their regulated binding to G␣. G␥ binds most tightly to the GDP-bound form of G␣, usually considered the inactive conformation. Because G␥ and GDP bind positively cooperatively to G␣, G␥ stabilizes GDP binding and thus suppresses spontaneous G␣ activation. Conversely, GDP stabilizes G␥ binding and suppresses its ability to spontaneously regulate effector proteins. In contrast, G␥ binds least tightly to the GTP-bound, activated conformation 4 The abbreviations used are: PLC, PIP 2-selective phospholipase C; PI, phosphatidylinositol; GAP, GTPase-activating protein; FRET, fluorescence resonance energy transfer; GTP␥S, guanosine 5Ј-O-(thiotriphosphate); RGS4-197, a mutant RGS4 that lacks all cysteine residues except 197 (C2S, C48S, C71S, C132S, C183S, C204S/C12A, C33A, C95A/C148V); RGS4-197Fl, RGS4-197 covalently labeled with Alexa532; GFP, green fluorescent protein; CFP, cyan fluorescent protein; YFP, yellow fluorescent protein; AChR, acetylcholine receptor.
Journal of Applied Polymer Science, 2000
Jute–polyester composites were fabricated with untreated (control) and bleached slivers with 60% ... more Jute–polyester composites were fabricated with untreated (control) and bleached slivers with 60% loading of fiber by weight and were designated as JPH(C) and JPH(B), respectively. Both types of composite specimens were subjected to water absorption and outdoor weathering tests to assess their relative performance under environmental conditions. While both composites showed low water absorption, JPH(B) showed lesser water absorption (8.48%) than did JPH(C) (12.25%). The mechanical properties like tensile and flexural strengths were measured for both the weathered and unweathered specimens and compared. The tensile strength of JPH(C) and JPH(B) decreased while the tensile modulus increased after weathering. The flexural strength, moduli, and ILSS of the weathered specimens were less than those of the unweathered ones. The nature of the fiber–matrix adhesion could be established from these results. The cause of every observation is explained. Thermal analyses (TG/DTG and DSC) of the composite specimens were also done. The overall thermal stability of JPH(C) was found to be better than that of JPH(B). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1671–1679, 2000
International Journal of Theoretical Physics, 2008
String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi ... more String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi type VI0 metric in Saez-Ballester Scalar-Tensor theory of gravitation. The field equations are solved for massive string cloud with particles attached to them. A more general linear equation of state of the cosmic string tension density with the proper energy density of the universe is considered instead of taking any
High Performance Polymers, 2014
A candid approach to analyze the prospects of organic–inorganic nanocomposites as polyelectrolyte... more A candid approach to analyze the prospects of organic–inorganic nanocomposites as polyelectrolytes has been presented in this communication. Structurally modified aromatic sulfone polymer, polysulfone, was successfully prepared through modification with trimethyl silyl chlorosulfonate, which was confirmed from Fourier transform infrared spectrographs. Different classes of nanofillers like layered silicates and inorganic oxides were reinforced in the modified macromolecular system using solvent casting technique. A comparative study was performed to evaluate the effectiveness of filled polyelectrolyte membranes in a direct methanol fuel cell operated at 60°C with 1.0 M methanol feed. Atomic force micrographs revealed the phase morphology, responsible for this behaviour. The variation in ion transfer behavior as a function of structural modification and filler composition was also conducted. Furthermore, supportive information for these characterizations were derived from morphological (x-ray diffractometry), thermal (thermogravimetric analysis), and liquid uptake studies.
We have studied the band-gap variation and stability energy in silicon carbide ͑SiC͒ nanoclusters... more We have studied the band-gap variation and stability energy in silicon carbide ͑SiC͒ nanoclusters of different polytypes using density functional theory ͑DFT͒ based on a gradient-corrected approximation. We have obtained a series of spherical SiC nanoclusters with dimensions up to 2 nm from bulk 2H, 3C, and 4H polytype crystals. All clusters with diameters smaller than 1 nm exhibit similar energy-gap-size variations, while energy gaps for clusters larger than 1 nm show a distinct size dependence with different polytypes and approach their bulk gaps with an increase in cluster size. In contrast to their bulk behavior, the binding energy difference between polytypes of clusters within the diameter range 0.5 nm− 2 nm is found to be negligible, suggesting that the problems associated with the synthesis of polytypes of SiC in bulk may disappear for small clusters. The convergence of the energy gap and binding energy with different polytypes at small size clusters and the transition between the clusters to bulk behavior in SiC systems could be exploited for making future nano-optoelectronics devices.
Acta Crystallographica Section E Structure Reports Online, 2006
... für Organische Chemie und Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, D-... more ... für Organische Chemie und Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, D-64287 Darmstadt, Germany Correspondence e-mail: snayak@mag.barc.ernet ... The results of the in vitro anti-HIV activity of some biflavonoids has previously been reported (Lin et al ...
Acta Crystallographica Section E Structure Reports Online, 2006
The crystal structure of the title compound, 1-(2,6-dihydroxyphenyl)-9-(3,4-dihydroxyphenyl)nonan... more The crystal structure of the title compound, 1-(2,6-dihydroxyphenyl)-9-(3,4-dihydroxyphenyl)nonan-1-one monohydrate, also known as malabaricone C, C 21 H 26 O 5 ÁH 2 O, is stabilized by both intra-and intermolecular O-HÁ Á ÁO hydrogen bonds. Figure 1 Molecular structure of (I), showing the atom labeling and displacement ellipsoids drawn at the 50% probability level. organic papers Acta Cryst. (2006). E62, o2202-o2203 Bauri et al. C 21 H 26 O 5 ÁH 2 O o2203 supporting information sup-6
Journal of Coatings Technology and Research, 2011
Corrosion resistance behavior of sol-gelderived organic-inorganic nanotitania-silica composite co... more Corrosion resistance behavior of sol-gelderived organic-inorganic nanotitania-silica composite coatings was studied. Hybrid sol was prepared from Ti-isopropoxide and N-phenyl-3-aminopropyl triethoxy silane. The structure, morphology, and properties of the coating were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermo gravimetric analysis. The corrosion performances of the sol-gel-coated samples were investigated by electrochemical impedance spectroscopy (EIS) and standard salt spray tests. The hybrid coatings were found to be dense, more uniform, and defect free. In addition, the coatings also proved its excellent corrosion protection on phosphated steel sheet.
Journal of Biological Chemistry, 2005
G␥ subunits modulate several distinct molecular events involved with G protein signaling. In add... more G␥ subunits modulate several distinct molecular events involved with G protein signaling. In addition to regulating several effector proteins, G␥ subunits help anchor G␣ subunits to the plasma membrane, promote interaction of G␣ with receptors, stabilize the binding of GDP to G␣ to suppress spurious activation, and provide membrane contact points for G protein-coupled receptor kinases. G␥ subunits have also been shown to inhibit the activities of GTPase-activating proteins (GAPs), both phospholipase C (PLC)-s and RGS proteins, when assayed in solution under single turnover conditions. We show here that G␥ subunits inhibit G protein GAP activity during receptor-stimulated, steady-state GTPase turnover. GDP/GTP exchange catalyzed by receptor requires G␥ in amounts approximately equimolar to G␣, but GAP inhibition was observed with superstoichiometric G␥. The potency of inhibition varied with the GAP and the G␣ subunit, but half-maximal inhibition of the GAP activity of PLC-1 was observed with 5-10 nM G␥, which is at or below the concentrations of G␥ needed for regulation of physiologically relevant effector proteins. The kinetics of GAP inhibition of both receptor-stimulated GTPase activity and single turnover, solution-based GAP assays suggested a competitive mechanism in which G␥ competes with GAPs for binding to the activated, GTP-bound G␣ subunit. An N-terminal truncation mutant of PLC-1 that cannot be directly regulated by G␥ remained sensitive to inhibition of its GAP activity, suggesting that the G␥ binding site relevant for GAP inhibition is on the G␣ subunit rather than on the GAP. Using fluorescence resonance energy transfer between cyan or yellow fluorescent protein-labeled G protein subunits and Alexa532-labeled RGS4, we found that G␥ directly competes with RGS4 for high-affinity binding to G␣ i-GDP-AlF 4. G␥ subunits perform diverse roles in G protein-mediated signaling, almost all of which are based on their regulated binding to G␣. G␥ binds most tightly to the GDP-bound form of G␣, usually considered the inactive conformation. Because G␥ and GDP bind positively cooperatively to G␣, G␥ stabilizes GDP binding and thus suppresses spontaneous G␣ activation. Conversely, GDP stabilizes G␥ binding and suppresses its ability to spontaneously regulate effector proteins. In contrast, G␥ binds least tightly to the GTP-bound, activated conformation 4 The abbreviations used are: PLC, PIP 2-selective phospholipase C; PI, phosphatidylinositol; GAP, GTPase-activating protein; FRET, fluorescence resonance energy transfer; GTP␥S, guanosine 5Ј-O-(thiotriphosphate); RGS4-197, a mutant RGS4 that lacks all cysteine residues except 197 (C2S, C48S, C71S, C132S, C183S, C204S/C12A, C33A, C95A/C148V); RGS4-197Fl, RGS4-197 covalently labeled with Alexa532; GFP, green fluorescent protein; CFP, cyan fluorescent protein; YFP, yellow fluorescent protein; AChR, acetylcholine receptor.
Journal of Applied Polymer Science, 2000
Jute–polyester composites were fabricated with untreated (control) and bleached slivers with 60% ... more Jute–polyester composites were fabricated with untreated (control) and bleached slivers with 60% loading of fiber by weight and were designated as JPH(C) and JPH(B), respectively. Both types of composite specimens were subjected to water absorption and outdoor weathering tests to assess their relative performance under environmental conditions. While both composites showed low water absorption, JPH(B) showed lesser water absorption (8.48%) than did JPH(C) (12.25%). The mechanical properties like tensile and flexural strengths were measured for both the weathered and unweathered specimens and compared. The tensile strength of JPH(C) and JPH(B) decreased while the tensile modulus increased after weathering. The flexural strength, moduli, and ILSS of the weathered specimens were less than those of the unweathered ones. The nature of the fiber–matrix adhesion could be established from these results. The cause of every observation is explained. Thermal analyses (TG/DTG and DSC) of the composite specimens were also done. The overall thermal stability of JPH(C) was found to be better than that of JPH(B). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1671–1679, 2000
International Journal of Theoretical Physics, 2008
String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi ... more String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi type VI0 metric in Saez-Ballester Scalar-Tensor theory of gravitation. The field equations are solved for massive string cloud with particles attached to them. A more general linear equation of state of the cosmic string tension density with the proper energy density of the universe is considered instead of taking any
High Performance Polymers, 2014
A candid approach to analyze the prospects of organic–inorganic nanocomposites as polyelectrolyte... more A candid approach to analyze the prospects of organic–inorganic nanocomposites as polyelectrolytes has been presented in this communication. Structurally modified aromatic sulfone polymer, polysulfone, was successfully prepared through modification with trimethyl silyl chlorosulfonate, which was confirmed from Fourier transform infrared spectrographs. Different classes of nanofillers like layered silicates and inorganic oxides were reinforced in the modified macromolecular system using solvent casting technique. A comparative study was performed to evaluate the effectiveness of filled polyelectrolyte membranes in a direct methanol fuel cell operated at 60°C with 1.0 M methanol feed. Atomic force micrographs revealed the phase morphology, responsible for this behaviour. The variation in ion transfer behavior as a function of structural modification and filler composition was also conducted. Furthermore, supportive information for these characterizations were derived from morphological (x-ray diffractometry), thermal (thermogravimetric analysis), and liquid uptake studies.
We have studied the band-gap variation and stability energy in silicon carbide ͑SiC͒ nanoclusters... more We have studied the band-gap variation and stability energy in silicon carbide ͑SiC͒ nanoclusters of different polytypes using density functional theory ͑DFT͒ based on a gradient-corrected approximation. We have obtained a series of spherical SiC nanoclusters with dimensions up to 2 nm from bulk 2H, 3C, and 4H polytype crystals. All clusters with diameters smaller than 1 nm exhibit similar energy-gap-size variations, while energy gaps for clusters larger than 1 nm show a distinct size dependence with different polytypes and approach their bulk gaps with an increase in cluster size. In contrast to their bulk behavior, the binding energy difference between polytypes of clusters within the diameter range 0.5 nm− 2 nm is found to be negligible, suggesting that the problems associated with the synthesis of polytypes of SiC in bulk may disappear for small clusters. The convergence of the energy gap and binding energy with different polytypes at small size clusters and the transition between the clusters to bulk behavior in SiC systems could be exploited for making future nano-optoelectronics devices.
Acta Crystallographica Section E Structure Reports Online, 2006
... für Organische Chemie und Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, D-... more ... für Organische Chemie und Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, D-64287 Darmstadt, Germany Correspondence e-mail: snayak@mag.barc.ernet ... The results of the in vitro anti-HIV activity of some biflavonoids has previously been reported (Lin et al ...
Acta Crystallographica Section E Structure Reports Online, 2006
The crystal structure of the title compound, 1-(2,6-dihydroxyphenyl)-9-(3,4-dihydroxyphenyl)nonan... more The crystal structure of the title compound, 1-(2,6-dihydroxyphenyl)-9-(3,4-dihydroxyphenyl)nonan-1-one monohydrate, also known as malabaricone C, C 21 H 26 O 5 ÁH 2 O, is stabilized by both intra-and intermolecular O-HÁ Á ÁO hydrogen bonds. Figure 1 Molecular structure of (I), showing the atom labeling and displacement ellipsoids drawn at the 50% probability level. organic papers Acta Cryst. (2006). E62, o2202-o2203 Bauri et al. C 21 H 26 O 5 ÁH 2 O o2203 supporting information sup-6