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51.
The interaction of Me2Sn(IV)2+ and Me3Sn(IV)+ with a prodrug, sodium 2-mercaptoethane sulfonate (HSCH2CH2SO3Na, MESNA) abbreviated as (HL), has been studied potentiometrically in aqueous solution (I = 0.1 mol·L?1 KNO3, 298 K). The concentration distribution of various species formed in the solution was studied with changes in pH (~3–11). A strong coordination of MESNA with metal through the S atom of thiol group has been found. In the Me2Sn(IV)–HL system, the species [Me2Sn(L)]+ (53.1–75.6%) is predominant at acidic pH (3.73 ± 0.02) and the species [Me2Sn(L)2OH]? (29.4–38.5%) is predominant at basic pH (10.32 ± 0.08). In contrast, for the Me3Sn(IV)+ system, [Me3SnL] (37.0–57.4%) is the major species at pH 7.65 ± 0.03 and [Me3Sn(OH)] (49.9–67.2%) and [Me3Sn(L)(OH)]? (30.2–46.5%) are the major species at pH 11.05 ± 0.01. However, at physiological pH (7.01 ± 0.32), in both (1:1) and (1:2) Me2Sn(IV)–HL systems, the species [Me2Sn(L)(OH)] (67.2–89.9%) is predominant, whereas for Me3Sn(IV)–HL (1:1) and (1:2) systems, [Me3Sn(OH)] (53.5%) and [Me3SnL] (56.8%) are the respective predominant species. In order to characterize the possible geometry of the proposed complex species, multinuclear (1H, 13C and 119Sn) NMR studies were carried out at different pHs. No polymeric species were detected in the experimental pH range. 相似文献
52.
Sulata Kumari Sahu Rajesh Ganesan T. Gnanasekaran 《The Journal of chemical thermodynamics》2010,42(1):1-7
Standard molar Gibbs free energy of formation of ternary oxides Pb5CrO8(s), Pb2CrO5(s), and PbCrO4(s) were determined by measuring equilibrium oxygen partial pressures over relevant phase fields using manometry and solid oxide electrolyte based emf methods and are given by: 相似文献
53.
54.
Syahmi AR Vijayarathna S Sasidharan S Latha LY Kwan YP Lau YL Shin LN Chen Y 《Molecules (Basel, Switzerland)》2010,15(11):8111-8121
Elaeis guineensis (Arecaceae) is widely used in West African traditional medicine for treating various ailments. An evaluation on the toxicity of extracts of this plant is crucial to support the therapeutic claims. The acute oral toxicity and brine shrimp lethality of a methanolic extract of this plant was tested. Oral administration of crude extract at the highest dose of 5,000 mg/kg resulted in no mortalities or evidence of adverse effects, implying that E. guineensis is nontoxic. Normal behavioral pattern, clinical signs and histology of vital organs confirm this evidence. The E. guineensis extracts screened for toxicity against brine shrimp had 50% lethal concentration (LC??) values of more than 1.0 mg/mL (9.00 and 3.87 mg/mL, at 6 and 24 h, respectively), confirming that the extract was not toxic. Maximum mortalities occurred at 100 mg/mL concentration while the least mortalities happened to be at 0.195 mg/mL concentration. The results of both tests confirm that E. guineensis is nontoxic and hence safe for commercial utilization. 相似文献
55.
Ashutosh Tiwari Rajendra Kumar Mani Prabaharan Ravi R. Pandey Premlata Kumari Anurag Chaturvedi A. K. Mishra 《先进技术聚合物》2010,21(9):615-620
A nanofibrous polyaniline (PANI) thin film was fabricated using plasma‐induced polymerization method and explored its application in the fabrication of NO2 gas sensor. The effects of substrate position, pressure, and the number of plasma pulses on the PANI film growth rate were monitored and an optimum condition for the PANI thin film preparation was established. The resulting PANI film was characterized with UV–visible spectrophotometer, FTIR, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The PANI thin film possessed nanofibers with a diameter ranging from 15 to 20 nm. The NO2 gas sensing behavior was studied by measuring the change in electrical conductivity of PANI film with respect to NO2 gas concentration and exposure time. The optimized sensor exhibited a sensitivity factor of 206 with a response time of 23 sec. The NO2 gas sensor using nanofibrous PANI thin film as sensing probe showed a linear current response to the NO2 gas concentration in the range of 10–100 ppm. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
56.
Quantitative Structure-Activity Relationship modeling is a powerful approach for correlating an organic compound to its lipophilicity.
In this paper QSAR models are established for estimation of correlation of the lipophilicity of a series of pyrrolyl-acetic
acid derivatives, inhibitors of the aldose reductase enzyme, in the n-octanol-water system with biological activity of aldose reductase. Lipophilicity, expressed by the logarithm of n-octnol-water partition coefficient log P and biological activity of aldose reductase inhibitory activity by log it. Result obtained by QSAR modeling of compound series
reveal a definite trend in biological activity and a further improvement in quantitative relationships are established if,
beside log P, Hammett electronic constant σ and connectivity index chi-3 (3
χ) term included in the regression equation. 相似文献
57.
P. Sumati Kumari 《Journal of the Egyptian Mathematical Society》2013,21(3):276-280
This paper proves the existence of periodic and fixed points for contractive conditions in metric (symmetric) space. 相似文献
58.
Amit Kumar Gupta Kumkum Kumari Neetu Singh Dushyant Singh Raghuvanshi Krishna Nand Singh 《Tetrahedron letters》2012,53(6):650-653
An environmentally benign, ionic liquid promoted multicomponent protocol to benzopyrano(2,3-d)pyrimidines and 4H-chromenes has been developed at room temperature. Results of the reaction depend on the nature of the nucleophile used in the reaction. Secondary amines result in the formation of benzopyrano(2,3-d)pyrimidines, whereas thiols give rise to 4H-chromenes under the same set of reaction conditions. 相似文献
59.
S.K. Das Amrita Kumari D. Bandopadhay S.A. Akbar G.K. Mondal 《Applied Mathematical Modelling》2011,35(9):4208-4221
A first principle based mathematical model has been developed to characterise the effect of total liquid hold-up on the bosh silicon distribution behaviour in the dripping zone of a blast furnace. Two specific cases of hold-up behaviour have been investigated, namely, hold-up in the absence and in the presence of counter current gas flow conditions. The model exemplifies coupled phenomenon of chemical kinetics, transport processes and liquid hold-up to characterise the silicon behaviour in the dripping zone. The present modelling investigation shows that the bosh silicon level diminishes with the enhanced liquid hold-up in the dripping zone. Further, the influence of counter current gas flow on the hold-up is not significant. However, it has been observed that the liquid phase temperature reduces with increased liquid hold-up in dripping zone under steady state operating conditions. The model predictions of bosh silicon distribution have been validated with the published literatures (bulk values) and found to be in good agreement. 相似文献
60.
The reactions of dimeric complex [Rh(CO)2Cl]2 with hemilabile ether‐phosphine ligands Ph2P(CH2) nOR [n = 1, R = CH3 (a); n = 2, R = C2H5 (b)] yield cis‐[Rh(CO)2Cl(P ~ O)] (1) [P ~ O = η 1‐(P) coordinated]. Halide abstraction reactions of 1 with AgClO4 produce cis‐[Rh(CO)2(P ∩ O)]ClO4 (2) [P ∩ O = η 2‐(P,O)chelated]. Oxidative addition reactions of 1 with CH3I and I2 give rhodium(III) complexes [Rh(CO)(COCH3)ClI(P ∩ O)] (3) and [Rh(CO)ClI2(P ∩ O)] (4) respectively. The complexes have been characterized by elemental analyses, IR, 1H, 13C and 31P NMR spectroscopy. The catalytic activity of 1 for carbonylation of methanol is higher than that of the well‐known [Rh(CO)2I2]? species. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献