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351.
The excess conductivity of thin superconducting Sn films has been measured. These films have been grown at room temperature and ~ 77 K on glass substrates. The results show that the pair breaking parameter is not simply and solely related to the normal state sheet resistance but depends also on the substrate temperature. 相似文献
352.
The current–voltage characteristics of Schottky diodes with an interfacial insulator layer are analysed by numerical simulation. The current–voltage data of the metal–insulator–semiconductor Schottky diode are simulated using thermionic emission diffusion (TED) equation taking into account an interfacial layer parameter. The calculated current–voltage data are fitted into ideal TED equation to see the apparent effect of interfacial layer parameters on current transport. Results obtained from the simulation studies shows that with mere presence of an interfacial layer at the metal–semiconductor interface the Schottky contact behave as an ideal diode of apparently high barrier height (BH), but with same ideality factor and series resistance as considered for a pure Schottky contact without an interfacial layer. This apparent BH decreases linearly with decreasing temperature. The effects giving rise to high ideality factor in metal–insulator–semiconductor diode are analysed. Reasons for observed temperature dependence of ideality factor in experimentally fabricated metal–insulator–semiconductor diodes are analysed and possible mechanisms are discussed. 相似文献
353.
Raj Pal Sharma Rajni Sharma Ritu Bala Dip Singh Gill Sukhjinder Singh Jugal Kishor Puri Luca Russo Kari Rissanen 《Journal of chemical crystallography》2006,36(10):619-625
The cobalt(III) complex salt [(C4H9)4N][trans-Co(NH3)2(NO2)4] has been synthesized in high yield by reacting equimolar quantities of [(C4H9)4N]Br and K[trans-Co(NH3)2(NO2)4] in aqueous medium at room temperature. The product thus formed has been re-crystallised from acetone-water mixture, in the monoclinic space group P 21/n, with cell dimensions a=11.651(3) ?, b=19.005(4) ?, c=11.733(5) ?, β=90.28(3)°. The X-ray structure determination revealed the presence of discrete ions, [(C4H9)4N]+ and [trans-Co(NH3)2(NO2)4]−. The central metal ion cobalt(III) in the anion is found in octahedral environment, in trans geometry, while the organic counterion is a quaternary alkylammonium cation. The crystal lattice is stabilized by electrostatic interactions between the cations and anions.Supplementary material Crystallographic data (excluding structure factors) for the structure(s) reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 291300. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: (44) 1223 336-033; e-mail: deposit@ccdc.cam.ac.uk. 相似文献
354.
Raj Pal Sharma Rajni Sharma Ritu Bala Juan M. Salas Miguel Quiros 《Journal of chemical crystallography》2005,35(10):769-775
Dark red crystals of bis[trans-dinitrobis(ethylenediamine)cobalt(III)] dichromate, [trans-Co(en)2(NO2)2]2(Cr2O7) have been obtained by slowly allowing to mix the solutions of potassium dichromate and trans-dinitrobis(ethylenediamine)cobalt(III)
nitrate in 1:2 molar ratio in aqueous medium. Elemental analyses and spectroscopic techniques (IR, UV/visible, 1H and 13C NMR) were used for characterizing the complex salt. The complex salt crystallizes in the orthorhombic space group Fdd2 with
unit cell dimensions a = 24.778(2) ?, b = 30.457(2) ?, c = 6.5364(5) ?, Z = 8, V = 4932.8(7) ?3, R1 = 0.0617 and wR2 = 0.1518. X-ray structure determination revealed an ionic structure consisting of cationic cobaltammine [trans-Co(en)2(NO2)2]NO3 and dichromate anion. It is the first crystal structure of this cation with a dianion. 相似文献
355.
We study bifurcations in a spatially extended nonlinear system representing population dynamics with the help of analytic calculations. The result we obtain helps in the understanding of the onset of abrupt transitions leading to the extinction of biological populations. The result is expressed in terms of Airy functions and sheds light on the behavior of bacteria in a Petri dish as well as of large animals such as rodents moving over a landscape. 相似文献
356.
The Deepwater Horizon oil discharge in the Gulf of Mexico is considered to be one of the worst environmental disasters to date. The spread of the oil spill and its consequences thereof had various environmental impacts. The National Oceanic and Atmospheric Administration (NOAA) in conjunction with the Environmental Protection Agency (EPA), the US Fish and Wildlife Service, and the American Statistical Association (ASA) have made available a few datasets containing information of the oil spill. In this paper, we analyzed four of these datasets in order to explore the use of applied statistics and machine learning methods to understand the spread of the oil spill. In particular, we analysed the “gliders, floats, boats” and “birds” data. The former contains various measurements on sea water such as salinity, temperature, spacial locations, depth and time. The latter contains information on the living conditions of birds, such as living status, oil conditions, locations and time. A varying-coefficients logistic regression was fitted to the birds data. The result indicated that the oil was spreading more quickly along the East–West direction. Analysis via boosted trees and logistic regression showed similar results based on the information provided by the above data. 相似文献
357.
Nandita Panda Nihar Bala Devi Sujata Mishra 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(3):1205-1211
The extraction of Nd(III) using binary mixtures of Cyanex 272 (HA), Cyanex 921/Cyanex 923 (B) in kerosene from nitric acid medium has been investigated. The effect of aqueous phase acidity, extractant concentration, nitrate ion concentration and diluents on the extraction of Nd(III) has been studied. On the basis of slope analysis results, extracted species are proposed as Nd(NO3)A2·3HA and Nd(NO3)2·A·3HA·B using Cyanex 272 and its mixture with Cyanex 921/Cyanex 923, respectively. With the mixture of 0.1 M Cyanex 272 and 0.1 M Cyanex 923 in kerosene, the extraction of 0.001 M Nd(III) from 0.001 M HNO3 solution was found to be 83.3 % whereas it was 73.3 % when 0.1 M Cyanex 921 used as synergist under same experimental conditions. The stripping data of Nd(III) from the loaded organic phase containing 0.1 M Cyanex 272 and 0.1 M Cyanex 921/Cyanex 923 with different acids indicated sulphuric acid to be the best stripping agent. 相似文献
358.
Nandu Bala Sharma Anirudh Singh Ram C. Mehrotra† 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1527-1539
The interaction of Bu2Sn(OPri)2 with a trifunctional tetradentate Schiff base (LH3) (where H3L = HOC6H4CH═NCH3C(CH2OH)2) yields the precursor complex Bu2Sn(LH) 1, which, on equimolar reactions with different metal alkoxides [Al(OPri)3, Bu3Sn(OPri), Ge(OEt)4]; Al(Medea)(OPri) (where Medea = CH3N- (CH2CH2O)2); and Me3SiCl in the presence of Et3N], affords, respectively, the complexes Bu2Sn(L)Al(OPri)2 2, Bu2Sn(L)Al(Medea) 3, Bu2Sn(L)Bu3Sn 4, Bu2Sn(L)Ge(OEt)3 5, and Bu2Sn(L)SiMe3 6. The reactions of 2 with 2,5-dimethyl-2,5-hexanediol in a 1:1 ratio and with acetylacetone (acacH) in a 1:2 molar ratio afforded derivatives Bu2Sn(L)Al(OC(CH3)2CH2CH2C(CH3)2 O) 7 and Bu2Sn(L)Al(acac)2 8, respectively. All of the derivatives 1– 8 have been characterized by elemental analyses, molecular weight measurements, and spectroscopic [IR and NMR (1H, 119Sn, 29Si, and 27Al)] studies. 相似文献
359.
One-pot synthesis of novel M2E2L2 type metallacycles [L(CO)3Re(μ-SeR)2Re(CO)3L] (1-5) was accomplished by oxidative addition of diaryl diselenide to low-valent transition metal carbonyl with monodentate pyridine ligands. In metallacycles 1-5, where L = pyridine ligand, R = C6H5, CH2C6H5, the pyridyl groups bonded to metal centres invariably adopted cis conformation due to π-π interaction whereas, in compounds 1a and 2a, the pyridyl ligands were oriented in trans conformation. When bulky phenyl groups are introduced at para position of pyridyl rings, as in case of metallacycle 3, the steric hindrance disrupts the soft interaction and resulted into the expansion of space in between two phenylpyridyl groups and created a void. The Metallacycles 1-5 have been characterised by elemental analysis, NMR, IR, absorption and emission spectroscopic techniques. Molecular structures of 1, 1a, 2, 2a, 3 and 4 were determined by single crystal X-ray diffraction analysis and the structural studies of 1, 2, 3 and 4 revealed that the pyridyl groups attached to the metal centres exhibited cis conformation, while 1a, 2a displayed trans conformation. 相似文献
360.
Sharma U Verma PK Kumar N Kumar V Bala M Singh B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(21):5903-5907
Iron phthalocyanine with iron sulfate has been successfully applied for high chemo- and regioselective reduction of aromatic nitro compounds to give the corresponding amines in a green solvent system without using any toxic ligand. The catalytic systems were also compatible with a large range of other reducible functional groups, such as keto, acid, amide, ester, halogen, lactone, nitrile, N-benzyl, O-benzyl, hydroxy, and heterocycles. In the present study, dinitro compounds have been regioselectively reduced to the corresponding amines with high yield. In most of the cases the conversion and selectivity was greater than 99% as determined by GC-MS analysis. 相似文献