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681.
G. J. Qureshi N. Padha V. K. Gupta M. N. Kamalasanan A. P. Singh A. Kapoor K. N. Tripathi 《Optics & Laser Technology》2003,35(5):401-407
In the present study styrene acrylonitrile based polymeric waveguides have been optimized with the help of aging (variation of baking time keeping the temperature constant), annealing (variation of baking temperature keeping the time constant), concentration and thickness (physical). Propagation losses are lowest at an annealing temperature of 100°C and aging time of 8 h. The values of effective refractive index of the waveguides change inconsistently between 1.566 and 1.569 and between 1.5660 and 1.5667 for aging and annealing effect, respectively. However, by increasing the physical thickness of the film, the value of refractive index was decreased. By increasing the concentration of the solution, the refractive index of the waveguides was increased. The birefringence in the present observation is of the order of 10−4. Polarization selective properties were also observed in the present study for certain range of concentration. 相似文献
682.
A short-range force constant model has been applied for the first time to investigate the phonons in α-NaAlH4 having body centered tetragonal Scheelite structure .The normal symmetry coordinates for the Scheelite structure were computed to investigate the phonons at the zone center. The phonons for α-NaAlH4 have been calculated involving five stretching and two bending force constants .The calculated Raman frequencies exhibit good agreement with the available measured values. The infrared frequencies have been assigned proper modes for the first time. 相似文献
683.
The kinetics of oxidation of some reducing sugars viz. glucose, galactose, fructose, maltose, and lactose by osmium(VIII) in presence of sodium metaperiodate in alkaline medium have been investigated. The reactions are zero order in periodate. The order of reaction in substrate and OH? decreases from unity to zero at higher [substrate] or [OH?], respectively. Rate of oxidation is proportional to [Osmium(VIII)]. Osmium(VIII) serves as an effective oxidant which oxidizes reducing sugars and itself reduces to osmium(VI). Role of IO4? is to regenerate osmium(VIII) from osmium(VI). An evidence for the complex formation between osmium(VIII) and reducing sugar has also been obtained. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:441–448, 2004. 相似文献
684.
Mukut Mani Tripathi Jeong-Sik Kim Seon-Bu Kim 《Proceedings Mathematical Sciences》2002,112(3):415-423
For submanifolds tangent to the structure vector field in locally conformal almost cosymplectic manifolds of pointwise constantφ-sectional curvature, we establish a basic inequality between the main intrinsic invariants of the submanifold on one side,
namely its sectional curvature and its scalar curvature; and its main extrinsic invariant on the other side, namely its squared
mean curvature. Some applications including inequalities between the intrinsic invariantδ
M
and the squared mean curvature are given. The equality cases are also discussed. 相似文献
685.
Laser-induced damage studies have been carried out on monocrystal GaAs at 1.06 μm wavelength as a function of pulse repetition rate in the nanosecond regime. The single shot observed laser damage threshold is 0.9 J/cm2. It has been found that the damage threshold decreases when the sample is irradiated with large number of pulses. However, the above effect is observed only when the repetition rate is higher than 1 Hz. Various laser damage mechanism theories have been discussed to explain the results. 相似文献
686.
U. N. Tripathi G. Venubabu Mohd. Safi Ahmad S. S. Rao Kolisetty A. K. Srivastava 《应用有机金属化学》2006,20(10):669-676
Diorganotin(IV) dipyrazolinates of the type R2Sn(C15H12N2OX)2 [where C15H12N2OX = 3(2′‐Hydroxyphenyl)‐5(4‐X‐phenyl)pyrazoline {where X = H ( a ); CH3 ( b ); OCH3 ( c ); Cl ( d ) and R = Me, Prn and Ph}] have been synthesized by the reaction of R2SnCl2 with sodium salt of pyrazolines in 1:2 molar ratio, in anhydrous benzene. These newly synthesized derivatives have been characterized by elemental analysis (C, H, N, Cl and Sn), molecular weight measurement as well as spectral [IR and multinuclear NMR (1H, 13C and 119Sn)] studies. The bidentate behaviour of the pyrazoline ligands was confirmed by IR, 1H and 13C NMR spectral data. A distorted trans‐octahedral structure around tin(IV) atom for R2Sn(C15H12N2OX)2 has been suggested. The free pyrazoline and diorganotin(IV) dipyrazolinates have also been screened for their antibacterial and antifungal activities. Some diorganotin(IV) dipyrazolinates exhibit higher antibacterial and antifungal effect than free ligand and some of the antibiotics. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
687.
Sujata Sinha Subhash Chand Pushplata Tripathi 《Applied biochemistry and biotechnology》2016,180(5):883-899
Biological activities of chitosan oligosaccharides (COS) are well documented, and numerous reports of COS production using specific and non-specific enzymes are available. However, strategies for improving the overall yield by making it monomer free need to be developed. Continuous enzymatic production from chitosan derived from marine wastes is desirable and is cost-effective. Isolation of potential microbes showing chitosanase activity from various ecological niches, gene cloning, enzyme immobilization, and fractionation/purification of COS are some areas, where lot of work is in progress. This review covers recent measures to improve monomer-free COS production using chitosanase/non-specific enzymes and purification/fractionation of these molecules using ultrafiltration and column chromatographic techniques. Various bioprocess strategies, gene cloning for enhanced chitosanase enzyme production, and other measures for COS yield improvements have also been covered in this review. COS derivative preparation as well as COS-coated nanoparticles for efficient drug delivery are being focused in recent studies. 相似文献
688.
Bhavna Sikarwar Pushpendra K. Sharma Brajesh K. Tripathi Mannan Boopathi Beer Singh Yogesh K. Jaiswal 《Electroanalysis》2016,28(4):881-889
Enzyme based electrochemical detection method developed for chemical toxicant ethanolamine (EA). Monoamine oxidase A (MAO‐A) enzyme was used for the oxidation of EA. A direct electron transfer from the electrode to EA without any mediator with the help of MAO‐A enzyme was attained and this confirms the application of this methodology for the development of third generation biosensor for EA sensing well below the IDLH (30 ppm) value of EA. Moreover, heterogeneous rate constant (0.021s?1) and the number of electron involved (5.2) were deduced for EA in PBS buffer. The calibration plot showed linearity 2.02×10?4 M to 10.10×10?4 M of EA in PBS buffer with detection limit 4.1 ppm. The modified electrodes are characterized by Raman and Electrochemical impedance spectroscopy (EIS) techniques. The outcome of this work indicates about the utility of this methodology for the sensing of EA in the environment if it is present as well as to degrade EA into other compounds without using any indicator or mediator. 相似文献
689.
Sabyasachi Rout P. M. Ravi Ajay Kumar R. M. Tripathi 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(3):1709-1717
Laboratory batch experiment of CO2 infiltration under closed conditions was conducted for a period of 30 days on mineral (uranium ore)–water system to understand, (a) how increased CO2 concentration affects the mobility and speciation of uranium (U); (b) change in water chemistry due to CO2 infiltration; and (c) identify geochemical signatures for identification CO2 infiltration. After exposure to CO2, water pH declines rapidly and again rebound and achieved equilibrium till end of the experiment. Speciation of U at mineral–water interface change from (UO2)2CO3(OH) 3 ? to carbonato (UO2CO3), fluoride (UO2F+) and sulfato (UO2SO4) complexes. pH and HCO3 ? were identified as best geochemical indicators for CO2 infiltration. 相似文献
690.
Buddhi Vallabh Tripathi Hemwati Nandan K. D. Purohit 《International Journal of Theoretical Physics》2016,55(4):2157-2161
Axially symmetric dyon solutions of a non-Abelian gauge theory model with two potentials are sought. While seeking axially symmetric (flux tube like solutions) for the model, we stumbled upon an exact solution which represents an infinite string-like dyonic configuration with cylindrical symmetry. 相似文献