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排序方式: 共有173条查询结果,搜索用时 15 毫秒
81.
Ravhi S. Kumar Sandeep Rekhi D. Prabhakaran M. Somayazulu Eunja Kim Jeremy D. Cook Timothy Stemmler A.T. Boothroyd Mark R. Chance Andrew L. Cornelius 《Solid State Communications》2009,149(39-40):1712-1716
The crystal structure of Na0.75CoO2 was studied at ambient and low temperatures down to 10 K at pressures up to 40 GPa using synchrotron x-rays and a diamond cell in angle dispersion geometry. A reduction in the c/a ratio was observed at both conditions with the application of pressure. An increase in Co–O bond lengths and a decrease in Na–O bond lengths were observed above 10 GPa. The results of the density functional calculations performed agree well with the pressure induced bond length changes. The anomalous change in the c/a ratio and bond lengths indicate a pressure induced isostructural phase transition above 10 GPa. Bulk modulus calculations show this compound is less compressible than its hydrated analogues. 相似文献
82.
V. V. Sikolenko I. O. Troyanchuk D. V. Karpinsky A. Rogalev F. Wilhelm R. Rosenberg D. Prabhakaran E. A. Efimova V. V. Efimov S. I. Tiutiunnikov I. A. Bobrikov 《Physics of the Solid State》2018,60(2):288-291
Spin transitions of cobalt ions in LaCoO3 single crystals have been studied by the method of X-ray magnetic circular dichroism (XMCD) at the K- and L2,3-edges of Co3+ ions. The orbital momentum of cobalt ions obtained for the K-edge at the 3d level in the region of the spin transition in the temperature range from 25 to 120 K increases by a factor of approximately 1.6, whereas the slope of the magnetization curve value in the same temperature range and magnetic field increases by a factor of more than 10. XMCD experiments at the cobalt L2,3-edges demonstrate gradual growth of the ratio of the orbital momentum to the spin one L/S from 0.48 to 0.53 in the temperature range from 60 K to 120 K. 相似文献
83.
The effect of square cut-outs on the natural frequencies of square, simply-supported composite plates is investigated. The forced and free dynamic response of plates with cut-outs is formulated. Laminations are assumed to be symmetric about the mid-plane and the plates are considered analytically as homogeneous anisotropic plates. In the method of solution it is assumed that the effect of the cut-out is equivalent to an external loading on the plate. For free vibration, the method leads to an infinite system of frequency equations. Depending upon the accuracy required, a suitable size of the system of frequency equations is selected. Results are given for square, simply-supported composite plates with centrally located square cut-outs for different modulus ratios. A comparison of results obtained from this method for isotropic plates with cut-outs with available literature is made and excellent agreement is obtained. 相似文献
84.
Small strain gages were used to measure the through-the-thickness extensional strain distribution in an adhesively-bonded stiffened strip subjected to four-point bending. A comparison between experiment and analysis was conducted. The results show good correlation of the experimental and analytical trends of the through-the-thickness extensional strain distribution in the adhesive layer. 相似文献
85.
86.
S. R. Prabhakaran Nayar 《Proceedings Mathematical Sciences》1973,77(5):201-211
The elastic wave propagation in orthorhombic crystals has been studied and a condition has been derived for the existence of internal conical refraction for crystals belonging to this class. It is shown that the direction in which ICR occurs is given by the roots of a quadratic equation. Expressions have been derived for the angle of the cone and other parameters relating to the cone for the three principal planes, and these have been numerically evaluated for Barytes, Celestites, and lodic acid. 相似文献
87.
Ramamurthy Prabhakaran 《Experimental Mechanics》1982,22(12):462-467
With the interpretation of isochromatic and isoclinic fringes in transparent, birefringent, orthotropic composites established, efforts have been in progress to determine the-individual values of the principal stresses or strains. Several methods have recently been proposed. Some of them utilize the photoelastic results only partially and rely on numerical procedures. Others have attempted to obtain the required information based entirely on experimental data. In this paper, the classical oblique-incidence technique is applied to transversely isotropic-birefringent composites. The proposed extension is verified by applying it to the problem of an orthotropic half-plane subjected to an edge-load. 相似文献
88.
[reaction: see text]. The generality of a new method for aryl amination has been defined. Ketimines derived from o-bromophenethylamine cyclize to the N-substituted indoline when treated with nBu3SnH and a radical initiator. The pH-neutral conditions tolerate base- and acid-sensitive functionality. The observed regioselectivity is nonconventional for addition reactions involving carbon radicals and carbon-heteroatom pi-bonds. 相似文献
89.
A hydrosilation reaction was used to bind four compounds with one or more alkyne groups or two alkene functionalities. The diffuse reflectance infrared Fourier transform, the 29Si cross-polarization magic-angle spinning (CP-MAS) NMR, and the 13C CP-MAS NMR spectra were used to characterize the various bonded materials. The bonded phase density was determined from carbon elemental analysis. The two ten-carbon hydrophobic stationary phases were characterized chromatographically and static stability tests were run in acidic and basic solutions. 相似文献
90.
Perchlorate complexes of vanadium(IV), iron(III), dysprosium, yttrium, copper(II) and nickel with the organic ligands dimethyl sulphoxide, antipyrine, 4-aminoantipyrine, 4-(2-hydroxynaphthyl)-azoantipyrine, and 4-(2,4-dihydroxyphenyl)azoantipyrine have been prepared and analysed for their metal content after decomposition by a non-explosive pyrolytic technique, viz. heating with ammonium chloride. The results obtained agree with those obtained by the standard methods. This pyrolytic technique is found to be very convenient, rapid and accurate. 相似文献