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121.
Summary Thermodynamic effective fixed charge densities of mercuric phosphate and carbonate parchment supported membranes were evaluated by a number of methods particularly those ofTeorell-Meyer-Sievers, Altug andHair andKobatake et al. The value of the permselectivity was obtained for the two membranes based onKobatake et al. procedure. Membrane transport number was calculated using a modified Nernst relation and compared with the values determined by the TMS method. The theoretical predictions for membrane potential usingKobatake et al. equation are borne out quite satisfactorily by our experimental results for both membrane.
With 8 figures and 3 tables 相似文献
Zusammenfassung Es wurden die Dichte der fixierten Ladungen von Quecksilberphosphat und Quecksilberkarbonat-Niederschlagsmembranen nach den Methoden vonTorell-Meyer-Sievers, Altug undHair undKobatake bestimmt. Weiterhin wurden Durchlässigkeit und Transportzahlen ermittelt und mit Werten der TMS-Methode verglichen. Theoretische Voraussagen über das Membranpotential nach den Gleichungen vonKobatake stimmen mit den experimentellen Ergebnissen überein.
With 8 figures and 3 tables 相似文献
122.
Vijay Kumar Kawaldeep K. Singh 《Journal of Radioanalytical and Nuclear Chemistry》1992,166(2):131-142
The sum peak method has been applied to electron capture probability changes to the 1086 keV level in the decay of152Eu in the different environments, e.g. ethylenediaminetetraacetic acid (EDTA), bovine serum albumin (BSA) and hydrochloric acid (HCl). An attempt is also made to determine the effect of chemical environment on the directional correlation coefficient of the 1409–122 keV - cascade in152Eu 152Sm decay. A change of G22 is found in the different chemical forms. 相似文献
123.
Thomas S Biswas N Venkateswaran S Kapoor S Naumov S Mukherjee T 《The journal of physical chemistry. A》2005,109(44):9928-9934
The surface-enhanced Raman scattering (SERS) studies of 5-amino tetrazole (5AT), a tetrazole derivative, in aqueous silver sol at pH approximately 9 and on deposited colloidal silver films were carried out and compared with the normal Raman spectrum of the molecule. The experimentally observed Raman bands along with their corresponding infrared bands were assigned based on the results of density functional theory (DFT) calculations. The significant changes evidenced between the SERS and the normal Raman spectra combined with the theoretical data obtained for Ag-5AT system demonstrated that the molecule is adsorbed on colloidal Ag particles through the lone pair of electrons of the nitrogen atom. The contribution of the chemical mechanism for the SERS enhancement was proved by the behavior of the electronic absorption spectrum of the Ag colloid upon addition of 5AT. This is further supported by the theoretical calculations that show that the favorable interaction of the frontier orbitals localized on Ag(+) and the negatively charged nitrogen from the tetrazole ring leads to the formation of the stable (up to 130 kJ mol(-1)) charge-transfer complex. The orientation of the adsorbed species with respect to the metal surface was also predicted by applying the "surface selection rule". In addition, the feasibility of the formation of the polymeric species has also been discussed. 相似文献
124.
In this study, chemometric techniques such as cluster analysis (CA), discriminant analysis (DA), principal component analysis (PCA) and partial least squares (PLS) were used to analyse the wastewater dataset to identify the factors which affect the composition of sewage of domestic origin, spatial and temporal variations, similarity/dissimilarity among the wastewater characteristics of cis- and trans-drains and discriminating variables. Samples collected from 24 wastewater drains in Lucknow city and from three sites on Gomti river in the month of January/February, May, August and November during the period of 5 years (1994-1999) were characterized for 32 parameters. The multivariate techniques successfully described the similarities/dissimilarities among the sewage drains on the basis of their wastewater characteristics and sources signifying the effect of routine domestic/commercial activities in respective drainage areas. Spatial and seasonal variations in wastewater composition were also determined successfully. CA generated six groups of drains on the basis of similar wastewater characteristic. PCA provided information on seasonal influence and compositional differences in sewage generated by domestic and industrial waste dominated drains and showed that drains influenced by mixed industrial effluents have high organic pollution load. DA rendered six variables (TDS, alkalinity, F, TKN, Cd and Cr) discriminating between cis- and trans-drains. PLS-DA showed dominance of Cd, Cr, NO3, PO4 and F in cis-drains wastewater. The results suggest that biological-process based STPs could treat wastewater both from the cis- as well as trans-drains, however, prior removal of toxic metals will be required from the cis-drains sewage. Further, seasonal variations in wastewater composition and pollution load could be the guiding factor for determining the STPs design parameters. The information generated would be useful in selection of process type and in designing of the proposed sewage treatment plants (STPs) for safe disposal of wastewater. 相似文献
125.
Anil K. Singh Nirmalya Majumdar 《Journal of photochemistry and photobiology. B, Biology》1995,30(2-3):105-113
All-trns-N-retinylidenetryptamine Schiff base was incorporated into aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulphosuccinate)/heptane reverse micelles. This micellar system was used as a model to study the retinal-tryptophan interactions in retinal proteins. The retinylidene Schiff base remains stable in the presence of reverse micelle-solubilized water pools. Partition coefficient and microviscosity measurements show that the Schiff base is located in the micellar interphase. The results are discussed in terms of the interaction between the retinylidene chromophore and the active site environment of rhodopsin and bacteriorhodopsin. In the present model, the quencher and emitting units are covalently attached, and are separated by two carbon spacer units. The fluorescence emission data obtained for the micelle-intercalated Schiff base chromophore are compared with the fluorescence of the native protein and intermediates in the photochemical cycle of bacteriofhodopsin. A comparison of the data obtained for tryptamine and the Schiff base with the results available for bacteriorhodopsin and bacterioopsin reveals that there is a large degree of quenching on intercalation of the retinylidene chromophore in the vicinity of the fluorophore. Evidence provided by this model suggests that energy transfer to retinal can occur from tryptophan residues located in the retinal pocket in the native protein. Thus the retinylidene unit can act as a quencher of the energy of tryptophan, the nature and extent of which may depend on the conformation and relative orientation of the protein-bound fluorophore. 相似文献
126.
Vinod K. Tiwari Archana Singh Hakkim A. Hussain Bhuwan B. Mishra Vyasji Tripathi 《Monatshefte für Chemie / Chemical Monthly》2007,138(7):653-658
Summary. A convenient and high yielding method for the synthesis of diverse dithiocarbamates having various substituents including
alkyl, aryl, heteroaryl, and alkylaryl at the thiol chain or at the amine chain or at both thiol and amine chains were developed
by the one-pot reaction of mercaptans, amines, and bis(benzotriazolyl)methanethione in presence of amidine base under mild
reaction conditions. 相似文献
127.
CNDO/force calculations have been employed to calculate the O-H stretching force constants for various structures of associated
water species such as water-dimethylether, water-acetonitrile, water-lithium fluoride, linear and cyclic water polymers. The
variation in the O-H stretching force constant in Am… O-H… Dn species where Am
and Dn represent, respectively,m number of electron-acceptor andn number of electron-donor molecules, is explained on the basis of the cooperativity effect. With increasing electron-acceptor
power of A and electron-donor power of D, the hydrogen-bonded O-H stretching force constant is significantly reduced. The
results obtained in these studies are in general agreement with experimental observations reported earlier. 相似文献
128.
A photometric method for trace analysis of Cu(II) with 1-(2-pyridylazo)-2-naphthol (PAN) in presence of a neutral surfactant, Triton X-100, has been reported in normal and derivative modes. The molar absorption coefficient () and Sandell's sensitivity (S) of PAN-Cu(II) complex at 555 nm is 5.21 x 10(4) l mol(-1) cm(-1) and 1.22 ng cm(-2) respectively. The detection limit of Cu(II) is 4.0 ng ml(-1) and Beer's law is obeyed in the range 0.08-4.00 mug ml(-1) of the analyte. Copper content of a number of commercially available alcoholic beverages, biological and standard alloy samples is reported. The results obtained are in excellent agreement with those obtained using AAS. 相似文献
129.
Chemometric analysis of groundwater quality data of alluvial aquifer of Gangetic plain, North India 总被引:10,自引:0,他引:10
Kunwar P. Singh Amrita Malik Vinod K. Singh Dinesh Mohan Sarita Sinha 《Analytica chimica acta》2005,550(1-2):82-91
Water quality data set from the alluvial region in the Gangetic plain in northern India, which is known for high fluoride levels in soil and groundwater, has been analysed by chemometric techniques, such as principal component analysis (PCA), discriminant analysis (DA) and partial least squares (PLS) in order to investigate the compositional differences between surface and groundwater samples, spatial variations in groundwater composition and influence of natural and anthropogenic factors. Trilinear plots of major ions showed that the groundwater in this region is mainly of Na/K-bicarbonate type. PCA performed on complete data matrix yielded six significant PCs explaining 65% of the data variance. Although, PCA rendered considerable data reduction, it could not clearly group and distinguish the sample types (dug well, hand-pump and surface water). However, a visible differentiation between the water samples pertaining to two watersheds (Khar and Loni) was obtained. DA identified six discriminating variables between surface and groundwater and also between different types of samples (dug well, hand pump and surface water). Distinct grouping of the surface and groundwater samples was achieved using the PLS technique. It further showed that the groundwater samples are dominated by variables having origin both in natural and anthropogenic sources in the region, whereas, variables of industrial origin dominate the surface water samples. It also suggested that the groundwater sources are contaminated with various industrial contaminants in the region. 相似文献
130.
Medha Rele Sudhir Kapoor Shweta Hedge Sergej Naumov Tulsi Mukherjee 《Research on Chemical Intermediates》2006,32(7):637-645
Many photo-physical studies have been reported for the detection of Hg2+ ions. Here we present the effect of Hg
2
2+
ions on the absorption and fluorescence of indole-2-carboxylic acid (I2C). Experimental evidence, supported by density functional
theory B3LYP/LANL2DZ/PCM, for the formation of a I2C-Hg
2
2+
complex, is reported for the first time. It was observed that I2C forms a ground-state complex with Hg
2
2+
ions in a ratio of 3:1. The possibility of I2C to be used as a selective novel chemical sensor for the spectrophotometric
detection of mercurous ions is described. 相似文献