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21.
We have investigated two conformally flat tilted Bianchi Type-V cosmological models in general relativity. To get a determinate
solution, we have assumed a supplementary conditionA =B
n between metric potentials wheren is a constant. The behaviour of the model forn = 2 is discussed in detail. Various physical and geometrical aspects of the models are also discussed. 相似文献
22.
Kalawati Meena Sudesh Kumari Jitender M. Khurana Amita Malik Chetan Sharma Harsh Panwar 《中国化学快报》2017,28(1):136-142
A simple and efficient three component procedure has been developed for the synthesis of highly substituted spiro[indolo-3,10'-indeno[1,2-b]quinolin]-2,4,11'-triones by one pot three component condensation of enaminones, isatin and indane-1,3-dione in ethanol:water (1:1) in presence of ceric ammonium nitrate (CAN) as catalyst. This method provides several advantages such as lesser reaction time, high yield of products and operational simplicity. The antimicrobial activity of some of the compounds has been investigated against six microbial strains, some of the tested compounds showed good antimicrobial activity. 相似文献
23.
Athimoolam M Lakshmanan R Alwarappan S 《The journal of physical chemistry. A》2011,115(40):10950-10961
A mathematical model corresponding to homogeneous chemical reactions under transient chronoamperometry conditions at hemispherical microelectrodes has been developed. The analytical solutions for the concentration of species and current were obtained using Duhamel's theorem. This closed-form theoretical expression pertains to the transient concentration profiles and fluxes of chemical species involved in chemical and electrochemical reactions at hemispherical microelectrodes. As t → ∞, the analytical expressions corresponding to the concentration and current approach steady-state values. The solutions obtained are explicit only under limiting current conditions. The approximate expressions for concentrations and current as functions of time corresponding to the EC' and CE mechanisms at hemispherical microelectrodes are also reported. 相似文献
24.
R Nageswara Rao S Meena D Nagaraju A Raghuram Rao S Ravikanth 《Analytical sciences》2006,22(9):1257-1260
A simple and rapid reversed-phase high-performance liquid-chromatographic method for the separation and determination of process-related impurities of celecoxib (CXB) in bulk drugs and pharmaceuticals was developed. The separation of impurities viz., 4-methylacetophenone (I), 1-(4-methylphenyl)-4,4,4-trifluorobutane-1,3-dione (II), 4-hydrazinobenzene sulfonamide (III) and a regio-specific isomer [3-(4-methylphenyl)-5-trifluoromethyl-1H-pyrazole-1-yl]-benzenesulfonamide (IV), was accomplished on an Inertsil ODS-3 column dynamically coated with 0.1% hexamethyldisilazane (HMDS) in acetonitrile:water (55:45 v/v) as a mobile phase and detection at 242 nm using PDA at ambient temperature. The chromatographic conditions were optimized by studying the effects of HMDS, an organic modifier, time of silanization and column temperature. The method was validated and found to be suitable not only for monitoring the synthetic reactions, but also to evaluate the quality of CXB. 相似文献
25.
A new macrocyclic compound, named as garuganin-I, having unique structural features has been isolated from the n-hexane extract of the leaves and the stem bark of Garuga pinnata Roxb. The chemical and spectroscopic evidence, including 13C-NMR indicate structure I for garuganin-I. 相似文献
26.
G. L. Baheti P. K. Khatri V. L. Meena L. R. Meghwal 《Journal of Radioanalytical and Nuclear Chemistry》1994,188(1):1-7
Fuel mix monitoring is important for optimum performance of vehicles. A variety of techniques used to monitor fuel mixes have not come into widespread use due to practical difficulties. Gamma attenuation has been found to be a potential technique for petroleum based fuel mix monitoring with certain limitations. 相似文献
27.
Polycrystalline samples of U-type hexaferrite series: (Ba1−3xLa2x)4Co2Fe36O60 with 0.10≤x≤0.20 in step of 0.05, are prepared by conventional solid state reaction route. Partial substitution of Ba2+ ions with La3+ ions enhances the electron hopping and reduces the magnetic interaction in the samples over the entire X-band frequencies; leading to wide band microwave absorption in all sample. Relative complex permittivity (εr=ε′−jε″) and permeability (μr=μ′−jμ″) of the prepared samples were measured using Vector Network Analyzer (VNA, Agilent PNA-L N5230A) for X-band (8.2-12.4 GHz) frequency range. The maximum absorption of 99.8% was obtained for x=0.10 sample for thickness tm=1.8 mm and all sample showed absorption ≥96%. The reflection loss (RL) calculated using the measured parameter (εr=ε′−jε″ and μr=μ′−jμ″) shows good agreement when compared with the return loss measured directly using VNA for sample x=0.20. The material can be expected to find relevance in suppression of electromagnetic interference (EMI) shielding and reduction of radar signatures. 相似文献
28.
A method for the determination of lead is described using thiol-functionalized gold nanoparticle. The detection method is based on the prevention of thiol-induced aggregation of gold nanoparticles by lead. Among six thiols, e.g., 4-mercapto-1-butanol, meso-2, 3-dimercaptosuccinic acid, mercaptosuccinic acid, 6-mercapto-1-hexanol, 4-(methylthio)-1-butanol, 1-propanethiol, four (4-mercapto-1-butanol, 6-mercapto-1-hexanol, 4-(methylthio)-1-butanol and 1-propanethiol) induced the aggregation of the gold nanoparticles which was measured by the change in absorbance at 520 and 650?nm. Prior incubation of the gold nanoparticles with lead decreased the 4-(methylthio)-1-butanol-induced aggregation of gold nanoparticles in a dose-dependent manner. A linear inverse relationship between the logarithmic concentration of lead and the ratio of absorbance at 650 to 520 was noted. The method has a dynamic range from 10?nM to 100?µM. However, metals such as mercury and chromium were more effective in comparison with lead in preventing the 4-methylthio-1-butanol-induced aggregation of gold nanoparticles. The method can be used for assessing the heavy metal load in water samples. 相似文献
29.
Ajay M. Sorty Kamlesh K. Meena Khushboo Choudhary Utkarsh M. Bitla P. S. Minhas K. K. Krishnani 《Applied biochemistry and biotechnology》2016,180(5):872-882
Halotolerant bacteria associated with Psoralea corylifolia L., a luxuriantly growing annual weed in salinity-affected semi-arid regions of western Maharashtra, India were evaluated for their plant growth-promoting activity in wheat. A total of 79 bacteria associated with different parts viz., root, shoot and nodule endophytes, rhizosphere, rhizoplane, and leaf epiphytes, were isolated and grouped based on their habitat. Twelve bacteria isolated for their potential in plant growth promotion were further selected for in vitro studies. Molecular identification showed the presence of the genera Bacillus, Pantoea, Marinobacterium, Acinetobacter, Enterobacter, Pseudomonas, Rhizobium, and Sinorhizobium (LC027447-53; LC027455; LC027457, LC027459, and LC128410). The phylogenetic studies along with carbon source utilization profiles using the Biolog® indicated the presence of novel species and the in planta studies revealed promising results under salinity stress. Whereas the nodule endophytes had minute plant growth-promoting (PGP) activity, the cell free culture filtrates of these strains enhanced seed germination of wheat (Triticum aestivum L). The maximum vigor index was monitored in isolate Y7 (Enterobacter sp strain NIASMVII). Indole acetic acid (IAA) production by the isolates ranged between 0.22 and 25.58 μg mL?1. This signifies the need of exploration of their individual metabolites for developing next-generation bio-inoculants through co-inoculation with other compatible microbes. This study has potential in utilization of the weed-associated microbiome in terms of alleviation of salinity stress in crop plants. 相似文献
30.
Dr. Santosh Kumar Meena Prof. Marialore Sulpizi 《Angewandte Chemie (International ed. in English)》2016,55(39):11960-11964
Directly manipulating and controlling the size and shape of metal nanoparticles is a key step for their tailored applications. In this work, molecular dynamics simulations were applied to understand the microscopic origin of the asymmetric growth mechanism in gold nanorods. Different factors influencing the growth were selectively included in the models to unravel the role of the surfactants and ions. In the early stage of the growth, when the seed is only a few nanometers large, a dramatic symmetry breaking occurs as the surfactant layer preferentially covers the (100) and (110) facets, leaving the (111) facets unprotected. This anisotropic surfactant layer in turn promotes anisotropic growth with the less protected tips growing faster. When silver salt is added to the growth solution, the asymmetry of the facets is preserved, but the Br? concentration at the interface increases, resulting in increased surface passivation. 相似文献