排序方式: 共有70条查询结果,搜索用时 46 毫秒
11.
Shridhar R. Gadre Savita S. Pundlik Indira H. Shrivastava 《Journal of Chemical Sciences》1994,106(2):303-314
The conventional electrostatic charge models (PD-AC) are constructed so as to reproduce the molecular electrostatic potential
(MESP) on and beyond the van der Waals’ (vdW) surface. The MESP distribution has recently [S R Gadre, S A Kulkarni and I H
Shrivastava (1992)J. Chem. Phys.
96 5253] been shown to exhibit rich topographical features. With this in view, a detailed topographical comparison of the MESP
derived from the charge models, with the respectiveab initio (MO) ones is taken up for water, hydrogen sulphide, methane and benzene molecules as test cases. It is shown that the point
charge models have a fundamental lacuna, viz. they fail to mimic the essential topographical features of MESP. A new model
incorporating a small number of floating spherical Gaussians is shown to restore all the critical features of the molecules
under study. A comparative study of the standard deviations of MESP derived from charge models on scaled vdW surfaces further
reveals that the present model leads to a better representation ofab initio MESP. 相似文献
12.
The paper describes the availability of crank-case manufacturing system in an automobile industry. The units discussed here fail either directly from normal working state or indirectly through partial failure state. The machines are subjected to both preventive and corrective maintenance. Failure and repair times of the units are independent. The problem is formulated using probability consideration and supplementary variable technique. The system of equations governing the working of system consists of ordinary as well as partial differential equations. Lagrange method and Runge–Kutta method is used to solve partial differential equation and ordinary differential equation respectively. The study reveals that successful program of preventive and routine maintenance will reduce equipment failures, extend the life of the equipment, and increase the system availability to considerable margin. 相似文献
13.
Asymmetric transfer hydrogenation of ketones using Ru(II)arene/amino alcohol catalyst system proceeds with significant rate enhancement by ultrasound promotion. Comparison of the silent reactions carried out at 25 degrees C with reactions under sonochemical activation at 25 degrees C clearly showed enhancement in catalytic activity by 5-10 times without significantly affecting the enantioselectivity. 相似文献
14.
Ali Moustafa R. K. Wu Yue Chapman Savita Ding Yong 《Research on Chemical Intermediates》2019,45(8):3973-3983
Research on Chemical Intermediates - Anisotropic nanoparticles, such as rods or bones, exhibit new properties due to their specific geometries. The development of unique properties on the surface... 相似文献
15.
Ashok V. Borhade Dipak R. Tope Sachin S. Kushare Savita V. Thakare 《Research on Chemical Intermediates》2018,44(12):7459-7478
A novel fly ash supported NiO (FA–NiO) nanocomposite solid heterogeneous catalyst has been prepared by impregnation of Ni(NO3)2 · 6H2O on thermally activated fly ash (FA) support. FT-IR spectroscopy, X-ray diffraction analysis, scanning electron microscopy, TEM and BET techniques were employed to characterize the catalyst. The catalytic adeptness of FA–NiO was tested and optimized in xanthene formation. Catalyst gave very high yield and good purity. Stability of the catalyst could be promising as it easily recovered and reused giving a similar yield up to four cycles. FA–NiO is an efficient catalyst providing an environmentally clean process for xanthene formation and for developing a revolutionary way to use the majority of waste fly ash. Further, we have also performed docking simulation between 1ONF and a xanthene molecule to evaluate binding orientation and affinity of the ligand. 相似文献
16.
In the present study, 20 new tetracyclic 1,4-benzothiazines (4a–4 t) were conveniently synthesized in good yields and characterized by different spectral and physical techniques. The in vitro antimicrobial evaluation of the synthesized benzothiazine derivatives was performed by serial dilution against two Gram-positive bacteria [Bacillus subtilis (MTCC 441) and Staphylococcus epidermidis (MTCC 6880)], two Gram-negative bacteria [Escherichia coli (MTCC 1652) and Pseudomonas aeruginosa (MTCC 424)], and two fungal strains [Candida albicans (MTCC 227) and Aspergillus niger (MTCC 8189)]. The derivatives 4 l and 4 t were found to be more potent than standard drug, i.e., fluconazole, against A. niger and C. albicans, respectively. 相似文献
17.
Hassan MI Kumar V Kashav T Alam N Singh TP Yadav S 《Journal of separation science》2007,30(12):1979-1988
Human seminal plasma contains a large array of proteins required for the normal physiology and metabolism of spermatozoa. These are mainly secreted from prostate epithelium, testes, and seminal vesicles. Fortunately, many of these are found to be present at elevated concentration in seminal plasma and act as a biomarker of different carcinomas as their levels are also enhanced in serum and are found to be involved in tumor progression and metastasis apart from fertility. The proteins which were overexpressed in the seminal plasma of prostate carcinoma patients were identified by 2-DE and MALDI-TOF/MS. We have designed a strategy to purify these four proteins prostate specific antigen (PSA), prostatic acid phosphatase (PAP), Zinc alpha2-glycoprotein (ZAG), and progastricsin (PG), together in homogeneity by using simple chromatographic techniques. Acidic and basic fractions of human seminal plasma were separated by ion exchange chromatography and further purified by gel permeation chromatography. Our results form a new and valuable resource for those attempting structure-based drug designing for prostate and other cancers where the amount of proteins is required in plenty and in native form. 相似文献
18.
In this paper we consider the solution of a bi-level linear fractional programming problem (BLLFPP) by weighting method. A non-dominated solution set is obtained by this method. In this article decision makers (DMs) provide their preference bounds to the decision variables that is the upper and lower bounds to the decision variables they control. We convert the hierarchical system into scalar optimization problem (SOP) by finding proper weights using the analytic hierarchy process (AHP) so that objective functions of both levels can be combined into one objective function. Here the relative weights represent the relative importance of the objective functions. 相似文献
19.
The paper mathematically establishes that magnetorotatory thermohaline convection of the Veronis [7] type cannot manifest itself as oscillatory motions of growing amplitude in an initially bottom heavy configuration if the thermohaline Rayleigh numberR s, the Lewis number τ, the thermal Prandtl number σ, the magnetic Prandtl number σ1, the Chandrasekhar numberQ and the Taylor numberT satisfy the inequality \(R_s 4\pi ^4 \left[ {1 + \frac{\tau }{{\sigma \pi ^2 }}\left\{ {\pi ^2 - \left( {O\sigma _1 + \frac{T}{{\pi ^2 }}} \right)} \right\}} \right]\) when both the boundary surfaces are rigid thus achieving magnetorotatory extension of an important characterization theorem of Banerjeeet al (1992) on the corresponding hydrodynamic problem. A similar characterization theorem is mathematically established in the context of the magnetorotatory thermohaline convection of the Stern (1960) type. 相似文献
20.
Esterification of a wide range of partially protected carbohydrate derivatives was achieved using acetic anhydride and a catalytic amount of ceric ammonium nitrate (CAN). Compatibility with the commonly used protecting groups was demonstrated, with the esterified products being furnished in good yields. Apart from affording the O-acetylated products, their mononitrated counterparts were also produced depending upon the reactivity of the starting material. Decreasing the molar equivalents of CAN afforded the O-acetylated products exclusively, while increasing it favored the mononitrated derivatives. 相似文献