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141.
142.
High spin properties of 24Mg, 32S and 36S have been studied by means of the Strutinsky method. A separation degree of freedom is explicitly included by using a two-center model for the shellmodel part of the calculations. It is found that for the first two systems special configurations exist that are in their structure directly related to molecular 12C + 12C and 16O + 16O configurations and merge continuously into these with increasing separation. On the basis of these results the general problem of molecular states is discussed. 相似文献
143.
Rajinder K. Tuli Kailash Chandra Rajendra K. Sharma Narendra Kumar Bhagwan S. Garg 《Transition Metal Chemistry》1980,5(1):49-51
Summary Pseudohalide complexes of the (-cpL)TiXZ type (where cp = cyclopentadienyl, L = -McCs5-H4 and X = N3, NCS, NCO or NCSe) have been prepared in aqueous and nonaqueous media and characterized by elemental analyses, i.r. and n.m.r. spectroscopy. I.r. spectroscopy shows that NCS, NCO and NCSe are bonded to the titanium atom through nitrogen in these complexes which are thus true isothiocyanato, isocyanato and isoselenocyanato derivatives respectively. 相似文献
144.
The variation of hyperfine field, isomer shift and Curie temperature with chromium concentration has been studied for the alloys (NiFe)1?xCrx for x = 0, 5, 10 and 15 at .%. The decrease in hyperfine field and isomer shift suggests an emptying of the majority spin d-band with increasing Cr concentration (reducing number of average 3d + 4s electrons per atom). The Curie temperature is also found to reduce rapidly with Cr concentration in agreement with magnetisation data. But the Curie temperatures as determined from Mössbauer spectra are considerably lower than those given by magnetisation studies and for the 10 and 15 at .% Cr concentrations the magnetic transition is spread out over a range of temperatures suggesting a mictomagnetic behaviour. 相似文献
145.
V. G. Kulkarni R. G. Lagu Girish Chandra B. V. Thosar 《Proceedings Mathematical Sciences》1970,72(2):88-93
The value (τ2) and the intensity (I2) of the delayed component in the lifetime spectra of positrons annihilating in annealed and quenched teflon and in sulphur and crystex (polymer sulphur), at room temperature and at 77° K are reported. These data and the X-ray diffraction patterns for these materials are discussed in terms of the free volume model for the formation and quenching of positronium atoms in molecular materials. 相似文献
146.
C.?V.?A.?V.?B.?Chandra?RajuEmail author Prudhvi?R.?Chintalapati 《International Journal of Theoretical Physics》2005,44(4):443-455
Fritzsch type of mass matrices for the 2×2 case and appropriate Lagrangians enable the choice of Yukawa constants of the Lagrangians in terms of the gauge constants. The mass matrices for the four quarks are shown to be proportional to VL. The Cabibbo angle is computed to be 13∘36′. 相似文献
147.
[reaction: see text] A total synthesis of the complex, biologically active, dimeric natural product (+/-)-torreyanic acid, which is composed of seven rings and laced with dense, variegated oxy-functionalization, has been accomplished from readily available allyl-substituted p-benzoquinone 8. Our synthetic stratagem involves crafting an epoxyquinone monomer for use in a biomimetic cascade process involving tandem a 6pi electrocyclization and a Diels-Alder dimerization. 相似文献
148.
Alkali-stable, high-pI isoelectric membranes have been synthesized from quaternary ammonium derivatives of cyclodextrins and poly(vinyl alcohol), and bifunctional cross-linkers, such as glycerol-1,3-diglycidyl ether. The new, high-pI isoelectric membranes were successfully applied as cathodic membranes in isoelectric trapping separations in place of the hydrolytically more labile, polyacrylamide-based cathodic isoelectric membranes, and permitted the use of catholytes as alkaline as 1 M NaOH. The new high-pI isoelectric membranes have shown excellent mechanical stability, low electric resistance and long life times, even when subjected to electrophoresis with current densities as high as 80 mA/cm2. 相似文献
149.
Eight new macrocyclic ligands have been prepared by the reaction of the precursor diketone (benzil, glyoxal, diacetyl or 2,3-pentanedione) with a diamine (thiosemicarbazide or semicarbazide). Copper(II) complexes of these ligands have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility, i.r., u.v.–vis, 1H-n.m.r., mass and e.p.r. spectral studies. Mass, n.m.r. and i.r. data indicate the condensation of the diamine and diketone and the whole molecular ion structure. g-Values are calculated for all of the complexes in polycrystalline form as well as in DMSO solution. Spin Hamiltonian values and bonding parameters have also been calculated which indicates that an unpaired electron is present in the
orbital. The metal-ligand bonding parameters shows strong in-plane σ sigma and in-plane π bonding. The magnetic and spectral data indicate tetragonal geometry for all of the complexes except [CuH2L4]Cl2 and [CuH2L4]Cl2 which are square planar. From c.v. data reversible CuII/CuI couples are observed for these complexes. The macrocyclic complexes show more antibacterial and antiviral activity as compared to the ligands. The antibacterial activities of the compounds were tested against S. aureus, S. subtillis and E. coli. 相似文献
150.
Saravanan C Shao Y Baer R Ross PN Head-Gordon M 《Journal of computational chemistry》2003,24(5):618-622
A sparse matrix multiplication scheme with multiatom blocks is reported, a tool that can be very useful for developing linear-scaling methods with atom-centered basis functions. Compared to conventional element-by-element sparse matrix multiplication schemes, efficiency is gained by the use of the highly optimized basic linear algebra subroutines (BLAS). However, some sparsity is lost in the multiatom blocking scheme because these matrix blocks will in general contain negligible elements. As a result, an optimal block size that minimizes the CPU time by balancing these two effects is recovered. In calculations on linear alkanes, polyglycines, estane polymers, and water clusters the optimal block size is found to be between 40 and 100 basis functions, where about 55-75% of the machine peak performance was achieved on an IBM RS6000 workstation. In these calculations, the blocked sparse matrix multiplications can be 10 times faster than a standard element-by-element sparse matrix package. 相似文献