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991.
Pandey R Mukhopadhyay S Ramasesha S Das PK Zyss J 《The Journal of chemical physics》2012,136(19):194504
We have investigated quadratic nonlinearity (β(HRS)) and linear and circular depolarization ratios (D and D('), respectively) of a series of 1:1 complexes of tropyliumtetrafluoroborate as a cation and methyl-substituted benzenes as π-donors by making polarization resolved hyper-Rayleigh scattering measurements in solution. The measured D and D(') values are much lower than the values expected from a typical sandwich or a T-shaped geometry of a complex. In the cation-π complexes studied here, the D value varies from 1.36 to 1.46 and D(') from 1.62 to 1.72 depending on the number of methyl substitutions on the benzene ring. In order to probe it further, β, D and D(') were computed using the Zerner intermediate neglect of differential overlap-correction vector self-consistent reaction field technique including single and double configuration interactions in the absence and presence of BF(4) (-) anion. In the absence of the anion, the calculated value of D varies from 4.20 to 4.60 and that of D(') from 2.45 to 2.72 which disagree with experimental values. However, by arranging three cation-π BF(4)(-) complexes in a trigonal symmetry, the computed values are brought to agreement with experiments. When such an arrangement was not considered, the calculated β values were lower than the experimental values by more than a factor of two. This unprecedented influence of the otherwise "unimportant" anion in solution on the β value and depolarization ratios of these cation-π complexes is highlighted and emphasized in this paper. 相似文献
992.
Niyoti S. Shenoy Ananya Verma S. A. Kumar S. Pandey Sangita D. Kumar A. V. R. Reddy 《Journal of Radioanalytical and Nuclear Chemistry》2012,294(3):413-417
The main objective of this work is the accurate measurement of uranium in the potable water sources of Muktsar district of Punjab, India. In the present work, a laser fluorimetry technique was used for the analysis of uranium. Inductively coupled plasma mass spectrometry (ICPMS) technique was also applied to verify and compare the uranium content analyzed using laser technique. About 16 samples from waterworks, bore wells, and hand pumps that supply the drinking water to local population were collected for this purpose. An indigenous laser fluorimeter supplied by RRCAT, Indore was employed for the analysis. Uranium concentrations obtained were in the range from 0 to 10???g?L?1 in ten samples, 11?C30???g?L?1 in three samples, and more than 100???g?L?1 in three samples namely Channu ground water, Warning Khera pump, and Killanwale village hand pump. The USEPA guideline value for uranium in safe drinking water is 30???g?L?1. Also, a data comparison with similar studies carried out in other countries is presented. 相似文献
993.
Picroside‐I and picroside‐II are known bioactive metabolites in Picrorhiza species. In the present study a simple, precise method has been established for the simultaneous determination of picrosides (picroside‐I and picroside‐II) in two different Picrorhiza species, P. kurroa and P. scrophulariiflora. This method was also validated for accuracy, precision, robustness, limit of detection and quantification, repeatability and recovery, according to International Conference of Harmonization guidelines. Separation and quantification was achieved by HPTLC using as the mobile phase chloroform–methanol (88:12, v/v) on precoated silica gel 60F254 aluminum plates. Densitometric determination was carried out at wavelength λmax 254 nm in UV absorbance mode. Comparative study also revealed that picroside‐I and picroside‐II are higher in P. scrophulariiflora than P. kurroa. Picroside‐I content was found to be 1.258 and 1.611%, and picroside‐II was estimated as 0.481 and 0.613% in P. kurroa and P. scrophulariiflora, respectively. Antioxidant potential of these two Picrorhiza species was also studied using DPPH. At a concentration of 0.1 mg/mL the scavenging activities of P. kurroa and P. scrophulariiflora were found to 37.70 and 34.30%, respectively. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
994.
Balendu Shekher Giri Asha A. Juwarkar D. B. Satpute S. N. Mudliar R. A. Pandey 《Applied biochemistry and biotechnology》2012,167(6):1744-1752
Dimethyl sulfide (DMS) is one of the sulfurous pollutants present in the waste gas generated from the pulp and paper industry. DMS has environmental health implications; therefore, it is necessary to treat the waste gas containing DMS prior to discharge into the environment. A bench-scale biofilter was operated in the laboratory as well as in a pulp and paper industry for the treatment of DMS. Both the biofilters were packed with pre-sterilized wood chips and cow dung/compost of the same origin seeded with biomass developed from garden soil enriched with DMS. The biofilters were operated for the generation of process parameters, and the potential microorganisms isolated from both the biofilters have been purified and characterized for degradation of DMS. Further, these cultures were purified on a basal medium using DMS as a sole carbon source for the growth. Further, the purified cultures were characterized through standard fatty acid methyl esters (FAME)-gas chromatography method, and the isolates were found to be mesophilic, aerobic microbes. These microbes were identified as Bacillus sphaericus-GC subgroup F, Paenibacillus polymyxa, B. sphaericus-GC subgroup F, B. sphaericus-GC subgroup F, and Bacillus megaterium-GC subgroup A, respectively. The potential culture for degradation of DMS was identified as B. sphaericus by 16s rRNA molecular analysis. 相似文献
995.
Sharma VK Sahare PD Pandey A Mohan D 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(5):1035-1043
Dye concentration dependent gain spectra for Coumarin 460 (C 460) and Coumarin 450 (C 450) in ethanol have been studied using Amplified Spontaneous Emission (ASE) technique under Nitrogen laser (337.1 nm) excitation in the concentration range 10(-2)-10(-5) m/l. The dependence of lasing wavelength and peak gain on concentration have been understood in terms of variation of fluorescence lifetime, which is due to photo-physical processes such as radiation trapping and concentration-quenching. Pump intensity dependence of efficiency is also explained in terms of fluorescence lifetime. A comparison of the stability of the two dyes has also been made on the basis of the functional groups at different positions of the basic coumarin. 相似文献
996.
From a practical perspective, the paper demonstrates that the appropriate use of dispersion, population, and equity criteria can lead to fairly good solutions with respect to the p-median objective. The only stipulation is that the decision maker verifies (through simple constraint checks) that the chosen locations meet the dispersion, population, and equity criteria. An empirical investigation is conducted to obtain appropriate values for these parameters. From a location science perspective, a new location model that accounts for equity and efficiency simultaneously is studied and analyzed. Specifically, the p-maxian problem with side constraints on dispersion, population, and equity is developed, its NP-completeness established, and valid inequalities and bounds derived. Computational tests show encouraging results. 相似文献
997.
Zimple Matharu Pratibha Pandey M. K. Pandey Vinay Gupta B. D. Malhotra 《Electroanalysis》2009,21(14):1587-1596
Mediator free enzyme sensor has been fabricated by covalently immobilizing cholesterol oxidase (ChOx) onto 11‐mercaptoundecanoic acid functionalized gold nanoparticles (MUDA‐AuNPs) – octadecylamine (ODA) hybrid Langmuir–Blodgett film. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies reveal that MUDA‐AuNP/ODA LB film has good affinity for ChOx and provides favorable microenvironment for direct electron transfer between enzyme and electrode. Interference free estimation of cholesterol has been realized at 0.3 V with linear range from 25 to 500 mg/dL, detection limit of 23.38 mg/dL, sensitivity of 1.085 μA mM?1 and response time of 20 s at pH 7.0. 相似文献
998.
999.
Density functional theory calculations have been performed for the title phosphinidene complexes using the exchange correlation functionals BP86 and B3LYP. The optimized bond lengths and angles of the model compounds are in excellent agreement with experiment. The M-P bond lengths in linear phosphinidene complexes correspond to a Pauling bond order of ∼ 3. The bent geometries at phosphorus in the bent metal phosphinidene complexes are consistent with the presence of a trivalent phosphorus(III) center which is singly bonded to carbon and doubly bonded to transition metal. The analysis of the delocalized Kohn-Sham orbitals shows the polarization of the M-P σ bonding orbitals towards the phosphorus atom in the MPMe bonds, while in the MPMe bond, the contributions of metal and phosphorus are almost the same. In the linear phosphinidene complexes the contributions of the covalent bonding ΔEorb are more than the electrostatic interaction ΔEelstat. The bent phosphinidene complexes have a lower degree of covalent bonding than the linear phosphinidene complexes. The major differences between the linear and bent phosphinidene complexes are found in the degree of π-bonding. The MPMe bonds show a true M-P π bond and a deviated π bond due to slight bent M-P-C bond angles. The MPMe bonds show a true M-P π bond and a lone-pair on phosphorus. 相似文献
1000.
Vadapalli Chandrasekhar Arun Kumar Mrituanjay D. Pandey 《Journal of organometallic chemistry》2010,695(1):74-6926
Unsymmetrical diorganotellurium(IV) dihalides, Ar′(Ar)TeCl2 [Ar′ = 2-(R-CHN-C6H3Me; R = 1-pyrenyl, 9-anthracenyl and 9-phenanthrenyl; Ar = 4-MeO-C6H4, 1-C10H7, 2,4,6-Me3-C6H2, C6H5, 4-Me-C6H4] were synthesized from transmetallation reactions of Ar′HgCl and ArTeCl3. Orthomercuration of the Schiff’s bases (Ar′H) afforded Ar′HgCl. All of these compounds have been characterized with the help of IR, multinuclear (1H, 13C) solution NMR and ESI-HRMS spectrometry. X-ray crystal structures of pyrenyl Ar′HgCl; pyrenyl Ar′(Ar)TeCl2 (Ar = 4-MeO-C6H4); anthranyl Ar′(Ar)TeCl2 (Ar = 4-MeO-C6H4 and 1-C10H7) and; phenathranyl Ar′(Ar)TeCl2 (Ar = 1-C10H7) have been determined. Intramolecular Hg/Te?N interactions are present in these structures. Fluorescence studies of these compounds have also been carried out. 相似文献