Indium tin oxide (ITO) thin-films were deposited on soda-lime-silicate glass using sols prepared ... more Indium tin oxide (ITO) thin-films were deposited on soda-lime-silicate glass using sols prepared from alcoholic solutions of indium chloride and stannic chloride with different In:Sn atomic ratios, namely 95/5, 90/10, 85/15 and 80/20. The electrical properties, structure and morphology of the thin-films were investigated. All the films studied, with a thickness range of 10–490 nm were polycrystalline with grain sizes
ABSTRACT Nanobiotechnology is a multidisciplinary branch of nanotechnology which includes fabrica... more ABSTRACT Nanobiotechnology is a multidisciplinary branch of nanotechnology which includes fabrication of nanosized materials using biological approaches. Highly structured metallic and metal sulfide nanoparticles have been reported to be synthesized by numerous bacteria, fungi, yeasts and viruses. However, biosynthesis of nanoparticles by Haloarchaea (salt-loving archaea) of the third domain of life, Archaea, is in its nascent stages. In this study, we report the intracellular synthesis of stable, mostly spherical silver nanoparticles (SNPs) by the haloarchaeal isolate Halococcus salifodinae BK6. The isolate adapted to silver nitrate was found to exhibit growth kinetics similar to that of cells unexposed to silver nitrate. The nitrate reductase enzyme assay and the enzyme inhibitor studies showed the involvement of NADH dependent nitrate reductase in silver tolerance, reduction, and synthesis of SNPs. UV visible spectroscopy, XRD, TEM and EDAX were used for characterization of SNPs. The XRD exhibited characteristic Bragg peaks of face centered cubic silver with crystallite domain size of 26 nm and 12 nm for SNPs synthesized in NTYE and halophilic nitrate broth, respectively. TEM analysis exhibited an average particle size of 50.3 nm and 12 nm for SNPs synthesized in NTYE and halophilic nitrate broth (HNB), respectively. The as synthesized SNPs exhibited antimicrobial activity against both Gram positive and Gram negative organisms.
Silver doped hydroxyapatite (Agx Ca100−x (PO4)6 (OH)2) nanorods were synthesized using a modified... more Silver doped hydroxyapatite (Agx Ca100−x (PO4)6 (OH)2) nanorods were synthesized using a modified sol gel method at a low temperature of 100 °C. Silver concentration was varied as x = 1, 3 and 5. X-ray diffraction studies showed that the synthesized silver doped hydroxyapatite (Ag-HAp) was fully crystalline with hexagonal structure and an average crystallite size of 25 nm. At all the doping concentrations, the nanoparticles were rod shaped with an average length of 110–180 nm and diameter of 20–25 nm as determined from transmission electron microscopy (TEM) studies. These compounds were tested for their antimicrobial activities against E. coli (MTCC 2345) and S. aureus (MTCC 737). Antimicrobial activity was observed for all the three silver doping concentrations with the highest activity for x = 3, in terms of the zone of inhibition and the percentage reduction in the number of colonies. Hemolysis ratios for x = 1 and 3 Ag-HAp samples were below 2 %, indicating that they are highly ...
High alumina fibre mats (Al 2 O 3 4 wt.% SiO 2 ) were prepared with and without organic additive... more High alumina fibre mats (Al 2 O 3 4 wt.% SiO 2 ) were prepared with and without organic additives (lactic acid and PVA) using a sol-gel spinning technique. As the organic content increased, surface roughness after calcination increased, phase transition was retarded and the strength of ...
ABSTRACT BaTiO3 ceramics have been widely studied for its application as multilayer ceramic capac... more ABSTRACT BaTiO3 ceramics have been widely studied for its application as multilayer ceramic capacitors. However, they have been reported to deviate from their insulating to semiconducting behavior upon doping, and are used as positive temperature coefficient (PTC) thermistors and transducers. In this work, sol–gel emulsion technique was used for synthesis of BaTiO3 powders of various shapes and sizes. The synthesized powders were calcined at two different temperatures i.e. 750°C, and 1000°C. XRD revealed the powders to be primarily cubic in structure. Presence of tetragonality was noted in the powders calcined at 1000°C. Crystallite size was calculated for the powders calcined at 750°C and 1000°C. Average particle size of the prepared powders varied from 42 to 94 nm. The shape and size of the particles were dependent on the type and concentration of the surfactant used. The synthesized material showed positive temperature coefficient of resistivity (PTCR) behavior. From the recorded resistivity values a maximum of 1010 Ωcm was achieved. The ferroelectric to paraelectric transition temperature, Curie point, (Tc) was found to be at 75°C from the impedance spectroscopy analysis for the prepared material.
... DOI: 10.1080/10584580590926648 Sim Lim Chong a , Ramanan Venkatesh a & Sutapa Roy Ramanan... more ... DOI: 10.1080/10584580590926648 Sim Lim Chong a , Ramanan Venkatesh a & Sutapa Roy Ramanan a pages 19-28. ... J. Am. Ceram. Soc. , 54: 1 [CrossRef], [Web of Science ®] View all references, 22. Ishida, M., Matsumi, H. and Tanaka, T. 1977. J. Vac. Soc. Jap. ...
... K Saranya, Meenal Kowshik and Sutapa Roy Ramanan 1752 ... 8 529 Bourrel M and SchechterRS 198... more ... K Saranya, Meenal Kowshik and Sutapa Roy Ramanan 1752 ... 8 529 Bourrel M and SchechterRS 1988 Microemulsions and related systems (New York: Marcel Dekker) Cai Y, Zhang S, Zeng X, Wang Y, Qian M and Weng W 2009 Thin Solid Films 517 5347 Chavan PN and ...
Indium tin oxide (ITO) thin-films were deposited on soda-lime-silicate glass using sols prepared ... more Indium tin oxide (ITO) thin-films were deposited on soda-lime-silicate glass using sols prepared from alcoholic solutions of indium chloride and stannic chloride with different In:Sn atomic ratios, namely 95/5, 90/10, 85/15 and 80/20. The electrical properties, structure and morphology of the thin-films were investigated. All the films studied, with a thickness range of 10–490 nm were polycrystalline with grain sizes
ABSTRACT Nanobiotechnology is a multidisciplinary branch of nanotechnology which includes fabrica... more ABSTRACT Nanobiotechnology is a multidisciplinary branch of nanotechnology which includes fabrication of nanosized materials using biological approaches. Highly structured metallic and metal sulfide nanoparticles have been reported to be synthesized by numerous bacteria, fungi, yeasts and viruses. However, biosynthesis of nanoparticles by Haloarchaea (salt-loving archaea) of the third domain of life, Archaea, is in its nascent stages. In this study, we report the intracellular synthesis of stable, mostly spherical silver nanoparticles (SNPs) by the haloarchaeal isolate Halococcus salifodinae BK6. The isolate adapted to silver nitrate was found to exhibit growth kinetics similar to that of cells unexposed to silver nitrate. The nitrate reductase enzyme assay and the enzyme inhibitor studies showed the involvement of NADH dependent nitrate reductase in silver tolerance, reduction, and synthesis of SNPs. UV visible spectroscopy, XRD, TEM and EDAX were used for characterization of SNPs. The XRD exhibited characteristic Bragg peaks of face centered cubic silver with crystallite domain size of 26 nm and 12 nm for SNPs synthesized in NTYE and halophilic nitrate broth, respectively. TEM analysis exhibited an average particle size of 50.3 nm and 12 nm for SNPs synthesized in NTYE and halophilic nitrate broth (HNB), respectively. The as synthesized SNPs exhibited antimicrobial activity against both Gram positive and Gram negative organisms.
Silver doped hydroxyapatite (Agx Ca100−x (PO4)6 (OH)2) nanorods were synthesized using a modified... more Silver doped hydroxyapatite (Agx Ca100−x (PO4)6 (OH)2) nanorods were synthesized using a modified sol gel method at a low temperature of 100 °C. Silver concentration was varied as x = 1, 3 and 5. X-ray diffraction studies showed that the synthesized silver doped hydroxyapatite (Ag-HAp) was fully crystalline with hexagonal structure and an average crystallite size of 25 nm. At all the doping concentrations, the nanoparticles were rod shaped with an average length of 110–180 nm and diameter of 20–25 nm as determined from transmission electron microscopy (TEM) studies. These compounds were tested for their antimicrobial activities against E. coli (MTCC 2345) and S. aureus (MTCC 737). Antimicrobial activity was observed for all the three silver doping concentrations with the highest activity for x = 3, in terms of the zone of inhibition and the percentage reduction in the number of colonies. Hemolysis ratios for x = 1 and 3 Ag-HAp samples were below 2 %, indicating that they are highly ...
High alumina fibre mats (Al 2 O 3 4 wt.% SiO 2 ) were prepared with and without organic additive... more High alumina fibre mats (Al 2 O 3 4 wt.% SiO 2 ) were prepared with and without organic additives (lactic acid and PVA) using a sol-gel spinning technique. As the organic content increased, surface roughness after calcination increased, phase transition was retarded and the strength of ...
ABSTRACT BaTiO3 ceramics have been widely studied for its application as multilayer ceramic capac... more ABSTRACT BaTiO3 ceramics have been widely studied for its application as multilayer ceramic capacitors. However, they have been reported to deviate from their insulating to semiconducting behavior upon doping, and are used as positive temperature coefficient (PTC) thermistors and transducers. In this work, sol–gel emulsion technique was used for synthesis of BaTiO3 powders of various shapes and sizes. The synthesized powders were calcined at two different temperatures i.e. 750°C, and 1000°C. XRD revealed the powders to be primarily cubic in structure. Presence of tetragonality was noted in the powders calcined at 1000°C. Crystallite size was calculated for the powders calcined at 750°C and 1000°C. Average particle size of the prepared powders varied from 42 to 94 nm. The shape and size of the particles were dependent on the type and concentration of the surfactant used. The synthesized material showed positive temperature coefficient of resistivity (PTCR) behavior. From the recorded resistivity values a maximum of 1010 Ωcm was achieved. The ferroelectric to paraelectric transition temperature, Curie point, (Tc) was found to be at 75°C from the impedance spectroscopy analysis for the prepared material.
... DOI: 10.1080/10584580590926648 Sim Lim Chong a , Ramanan Venkatesh a & Sutapa Roy Ramanan... more ... DOI: 10.1080/10584580590926648 Sim Lim Chong a , Ramanan Venkatesh a & Sutapa Roy Ramanan a pages 19-28. ... J. Am. Ceram. Soc. , 54: 1 [CrossRef], [Web of Science ®] View all references, 22. Ishida, M., Matsumi, H. and Tanaka, T. 1977. J. Vac. Soc. Jap. ...
... K Saranya, Meenal Kowshik and Sutapa Roy Ramanan 1752 ... 8 529 Bourrel M and SchechterRS 198... more ... K Saranya, Meenal Kowshik and Sutapa Roy Ramanan 1752 ... 8 529 Bourrel M and SchechterRS 1988 Microemulsions and related systems (New York: Marcel Dekker) Cai Y, Zhang S, Zeng X, Wang Y, Qian M and Weng W 2009 Thin Solid Films 517 5347 Chavan PN and ...
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