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排序方式: 共有66条查询结果,搜索用时 21 毫秒
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A. Sengupta B. Rajeswari R. M. Kadam R. J. Kshirsagar 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):903-908
The use of serpentine as a potential nuclear shielding material necessitates a chemical quality control of the samples before
its use in reactors. With this in view, characterization of these mineral samples was carried out using inductively coupled
plasma atomic emission spectrometry (ICP-AES) and Instrumental neutron activation analysis (INAA) methods. The analytical
results obtained by both ICP-AES and NAA techniques were found to be comparable. Na, Cr, Co, Zn, and Cu were found to be present
in all samples of Indian origin while Ga, Ag, Ni, and Cd were found to below the limits of detection. A comparison on the
detection limits of elements of interest was also carried out by both the analytical techniques and found to be in good agreement.
An infrared spectroscopic investigation was also carried out on all the mineral samples. Bands at 3,689 and 3,648 cm−1 were attributed to inner and outer hydroxyl stretching of Mg–OH, respectively. The weak and broad band centered around 3,416 cm−1 was assigned due to the stretching vibrations of the adsorbed water molecules while three bands at 1076, 1022 and 968 cm−1 were prescribed to the vibrations of the SiO4 tetrahedra. 相似文献
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Shreyans K. Jain Samdarshi Meena Asif K. Qazi Aashiq Hussain Sunil K. Bhola Rajendra Kshirsagar Koteppa Pari Anamika Khajuria Abid Hamid R. Uma Shaanker Sandip B. Bharate Ram A. Vishwakarma 《Tetrahedron letters》2013
The chromone alkaloid dysoline (1), a new regioisomer of rohitukine (2) along with rohitukine and rohitukine-N-oxide (3) were isolated from the stem barks of Dysoxylum binectariferum. The structure of dysoline (1) was determined by extensive 2D-NMR studies and the absolute configuration was established by NOESY and CD spectra. Dysoline (1) consisted of a 5,7-dihydroxy-2-methylchromone nucleus substituted with a 2′-hydroxylated N-Me piperidine ring at the C-6 position. Dysoline differs from rohitukine by the position of the piperidine ring on the chromone nucleus. Dysoline displayed promising cytotoxicity in HT1080 fibrosarcoma cells with an IC50 of 0.21 μM, and also displayed significant inhibition of proinflammatory cytokines TNF-α and IL-6. 相似文献
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Dr. Umesh A. Kshirsagar Regev Parnes Hagit Goldshtein Dr. Rivka Ofir Dr. Raz Zarivach Dr. Doron Pappo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13575-13583
An iron‐based cross‐dehydrogenative coupling (CDC) approach was applied for the diversity‐oriented synthesis of coumestrol‐based selective estrogen receptor modulators (SERMs), representing the first application of CDC chemistry in natural product synthesis. The first stage of the two‐step synthesis of coumestrol involved a modified aerobic oxidative cross‐coupling between ethyl 2‐(2,4‐dimethoxybenzoyl)acetate and 3‐methoxyphenol, with FeCl3 (10 mol %) as the catalyst. The benzofuran coupling product was then subjected to sequential deprotection and lactonization steps, affording the natural product in 59 % overall yield. Based on this new methodology other coumestrol analogues were prepared, and their effects on the proliferation of the estrogen receptor (ER)‐dependent MCF‐7 and of the ER‐independent MDA‐MB‐231 breast cancer cells were tested. As a result, new types of estrogen receptor ligands having an acetamide group instead of the 9‐hydroxyl group of coumestrol were discovered. Both 9‐acetamido‐coumestrol and 8‐acetamidocoumestrol were found more active than the natural product against estrogen‐dependent MCF‐7 breast cancer cells, with IC50 values of 30 and 9 nM , respectively. 相似文献
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Probing Absolute Electronic Energy Levels in Hg‐Doped CdTe Semiconductor Nanocrystals by Electrochemistry and Density Functional Theory 下载免费PDF全文
Dr. Pravin P. Ingole Dr. Vladimir Lesnyak Laxman Tatikondewar Susanne Leubner Prof. Dr. Nikolai Gaponik Dr. Anjali Kshirsagar Prof. Dr. Alexander Eychmüller 《Chemphyschem》2016,17(2):244-252
The absolute electronic energy levels in Hg‐doped CdTe semiconductor nanocrystals (CdHgTe NCs) with varying sizes/volumes and Hg contents are determined by using cyclic voltammetry (CV) measurements and density functional theory (DFT) ‐based calculations. The electrochemical measurements demonstrate several distinct characteristic features in the form of oxidation and reduction peaks in the voltammograms, where the peak positions are dependent on the volume of CdHgTe NCs as well as on their composition. The estimated absolute electronic energy levels for three different volumes, namely 22, 119 and 187 nm3 with 2.7±0.3 % of Hg content, show strong volume dependence. The volume‐dependent shift in the characteristic reduction and oxidation peak potential scan can be attributed to the alteration in the energetic band positions owing to the quantum confinement effect. Moreover, the composition (Cd/Hg=98.3/1.7 and 97.0/3.0) ‐dependent alteration in the electronic energy levels of CdHgTe NCs for two different samples with similar volumes (ca. 124±5 nm3) are shown. Thus obtained electronic energy level values of CdHgTe NCs as a function of volume and composition demonstrate good congruence with the corresponding absorption and emission spectral data, as well as with DFT‐based calculations. DFT calculations reveal that incorporation of Hg into CdTe NCs mostly affects the energy levels of conduction band edge, whereas the valence band edge remains almost unaltered. 相似文献
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Stoliar P Kshirsagar R Massi M Annibale P Albonetti C de Leeuw DM Biscarini F 《Journal of the American Chemical Society》2007,129(20):6477-6484
We investigate the role of self-assembly monolayers in modulating the response of organic field-effect transistors. Alkanethiol monolayers of chain length n are self-assembled on the source and drain electrodes of pentacene field-effect transistors. The charge carrier mobility mu exhibits large fluctuations correlated with odd-even n. For n < 8, mu increases by 1 order of magnitude owing to the decrease of the hole injection barrier and the improved molecular order at the organic-metallic interface. For n > or = 8, mu decays exponentially with an inverse decay length beta = 0.6 A(-1). Our results show that (i) charge injection across the interface occurs by through-bond tunneling of holes mediated by the alkanethiol layer; (ii) in the long-chain regime, the charge injection across the alkanethiol monolayer completely governs the transistor response; (iii) the transistor is a sensitive gauge for probing charge transport across single monolayers. The odd-even effect is ascribed to the anisotropic coupling between the alkanethiol terminal sigma bond and the HOMO level of ordered pentacene molecules. 相似文献
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The present study deals with hypersurface-homogeneous cosmological models with anisotropic dark energy in Saez–Ballester theory of gravitation. Exact solutions of field equations are obtained by applying a special law of variation of Hubble’s parameter that yields a constant negative value of the deceleration parameter. Three physically viable cosmological models of the Universe are presented for the values of parameter K occurring in the metric of the space–time. The model for K = 0 corresponds to an accelerating Universe with isotropic dark energy. The other two models for K = 1 and ?1 represent accelerating Universe with anisotropic dark energy, which isotropize for large time. The physical and geometric behaviours of the models are also discussed. 相似文献
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Umesh A. Kshirsagar 《Tetrahedron》2009,65(27):5244-12595
Starting from cyclic anhydrides and tert-butyl 2-aminobenzylcarbamate, simple and efficient synthesis of diverse range of kinetically controlled angular and thermodynamically controlled linear tricyclic and tetracyclic 1,3-diaza-heterocycles have been described via the intramolecular cyclizations of the corresponding imides/anilic acid esters. The effect of imide stability on the angular/linear product selectivity has also been described. The kinetically controlled angular products were successfully transformed to the corresponding thermodynamically controlled linear products by refluxing in methanol or methanol and acetic acid mixture. An interesting in situ 1,2-intramolecular methyl group migration has also been described. 相似文献
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Aromatic aldehydes were reduced to the corresponding hydrocarbons with borohydride exchange resin (BER) - nickel acetate in methanol in excellent yields. 相似文献