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61.
D. Amaranatha Reddy G. Murali R. P. Vijayalakshmi B. K. Reddy B. Sreedhar 《Crystal Research and Technology》2011,46(7):731-736
Zn1−xCrx S nanoparticles with x = 0.00, 0.005, 0.01, 0.02 and 0.03 were synthesized by chemical co‐precipitation method at room temperature for the first time. Ethylene diamine tetraacetic acid was used as stabilizer. Energy dispersive analysis of X‐rays confirmed the presence of Cr in the samples. The samples were characterized by scanning electron microscopy, X‐ray diffraction (XRD), transmission electron microscopy and optical absorption studies. XRD and selected area electron diffraction results showed that the samples of all compositions crystallized in cubic structure and the lattice parameters decreased linearly with increase in Cr content following Vegard's law indicating that the Cr ions have substituted for Zn in the ZnS lattice. The particle size estimated from XRD was in the range 6–10 nm.The optical absorption studies on the doped samples indicated that the absorption edge blue shifted with respect to those of bulk and nanocrystalline ZnS. The bandgap increased with increasing Cr concentration in a narrow range 3.81–4.03 eV. Photolumonesence studies showed blue emission with appreciable luminescence quenching with increasing Cr concentration. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
62.
Shilpa Kammaradi Sanjeeva Swathi Korrapati Chandrasekhar B. Nair P. V. Subba Rao Phani Kumar Pullela U. Vijayalakshmi Ramamoorthy Siva 《Journal of fluorescence》2014,24(4):1297-1306
Donor –linker –acceptor (DSSA) is a concept in fluorescence chemistry with acceptor being a fluorescent compound (FRET) or quencher. The DSSA probes used to measure thiol levels in vitro and in vivo. The reduction potential of these dyes are in the range of ?0.60 V, much lower than the best thiol reductant reported in literature, the DTT (?0.33 V). DSSA disulphide having an unusually low reduction potential compared to the typical thiol reductants is a puzzle. Secondly, DSSA probes have a cyclized rhodamine ring as acceptor which does not have any spectral overlap with fluorescein, but quenches its absorbance and fluorescence. To understand the structural features of DSSA probes, we have synthesized DSSANa and DSSAOr. The calculated reduction potential of these dyes suggest that DSSA probes have an alternate mechanism from the FRET based quenching, namely hydrophobic interaction or dye to dye quenching. The standard reduction potential change with increasing complexity and steric hindrance of the molecule is small, suggesting that ultra- low Eo’ has no contribution from the disulphide linker and is based on structural interactions between fluorescein and cyclized rhodamine. Our results help to understand the DSSA probe quenching mechanism and provide ways to design fluorescent probes. 相似文献
63.
J Santhanalakshmi P S Goyal V K Aswal G Vijayalakshmi 《Journal of Chemical Sciences》1999,111(5):651-658
Small-angle neutron scattering cross-section distributions of sodium dodecyl sulphate (SDS) and dodecyl trimethyl ammonium
bromide (DTAB), each 0·3 M in D2O were obtained in the absence and presence of 0·1 M 1-pentanol, 1-hexanol, and 1-octanol at 25°C. The Hayter-Penfold type
analysis was adopted. An ellipsoidal model with semiminor axis (a=16·5 ?) and semimajor axes (b=40·7 ? and 29·8 ?) for pure SDS and DTAB micelles has produced best fits. On increasing alkanol chain lengths an increase
inb values was found. Micellar parameters like effective radius (R), (a, b), fraction of counterions per micelle, and intermicellar distances were obtained. Surfactant aggregation number, additive
aggregation number intermicellar interaction potentials and values of Debye screening length were obtained for SDS and DTAB
in the presence of alkanols. Implications of partitioning effect, surfactant ionicity and intermicellar potentials on the
microstructures are rationalised. 相似文献
64.
Gisele Luiza Pavan Igor Tadeu Lazzarotto Bresolin Mariana Borsoi-Ribeiro Mookambesvaran Vijayalakshmi Sonia Maria Alves Bueno 《Adsorption》2014,20(5-6):677-688
Over the past decade, immobilized metal-affinity adsorbents have attracted increasing interest for purification of natural and recombinant immunoglobulin G (IgG). In this work, nickel and cobalt metal ions complexed with CM-Asp (carboxymethylaspartate) immobilized on poly(ethylenevinyl alcohol) (PEVA) hollow fiber membranes were evaluated for purification of human IgG from serum. The buffer system and NaCl had important effects on human serum protein adsorption in both adsorbents. Efficient purification of IgG was accomplished in sodium phosphate buffer without NaCl at pH 7.0. Under this condition, the electrostatic interactions are important for adsorption. The Ni(II)-CM-Asp–PEVA had a protein adsorption capacity of 17.5 mg of IgG mL?1 fiber when human serum diluted was loaded in crossflow filtration mode and the eluted IgG had a purity of 82.6 % (based on total protein and IgG, IgM, HSA, and Trf nephelometric analysis). Fitting the experimental IgG adsorption data to the Langmuir and Langmuir–Freundlich models showed that Ni(II)-CM-Asp and Co(II)-CM-Asp had Langmuirean and non-Langmuirean behavior, respectively, with positive cooperativity for IgG-Co(II)-CM-Asp binding, probably due to multipoint interactions (n = 2.12 ± 0.31). Thus, these membranes can be considered as alternative adsorbents for the purification or depletion of IgG from human serum. 相似文献
65.
66.
Vijayalakshmi Ghosh Amitava Mukherjee Natarajan Chandrasekaran 《Ultrasonics sonochemistry》2013,20(1):338-344
Basil oil (Ocimum basilicum) nanoemulsion was formulated using non-ionic surfactant Tween80 and water by ultrasonic emulsification method. Process of nanoemulsion development was optimized for parameters such as surfactant concentration and emulsification time to achieve minimum droplet diameter with high physical stability. Surfactant concentration was found to have a negative correlation with droplet diameter, whereas emulsification time had a positive correlation with droplet diameter and also with intrinsic stability of the emulsion. Stable basil oil nanoemulsion with droplet diameter 29.3 nm was formulated by ultrasonic emulsification for 15 min. Formulated nanoemulsion was evaluated for antibacterial activity against Escherichia coli by kinetics of killing experiment. Fluorescence microscopy and FT-IR results showed that nanoemulsion treatment resulted alteration in permeability and surface features of bacterial cell membrane. 相似文献
67.
68.
Khatkar V. Vijayalakshmi A. G. Sakthi Manjunath R. N. Olhan S. Behera B. K. 《Mechanics of Composite Materials》2020,56(3):367-378
Mechanics of Composite Materials - The role of fiber reinforcement architecture in adjusting the mechanical properties of glass-fiber-reinforced epoxy composite materials is studied. Fibrous... 相似文献
69.
Vijayalakshmi Satyen 《Hyperfine Interactions》1987,35(1-4):883-886
Mössbauer spectra of Cd0.1Ni0.9SnyFe2?2yO4 (y=0.0 to 0.5) ferrite system have been studied. The spectra suggest the existence of two hyperfine fields, one due to Fe3+ tetrahedral (A) site ions and the other due to Fe3+ octahedral (B) site ions. The variation of isomer shift, quadrupole interaction and internal magnetic fields of57Fe3+ ions in both A and B sites have been determined as function of tin concentration. The systematic decrease in Curie temperature observed in the above system with tin concentration is explained on the basis of exchange interaction. 相似文献
70.