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S. Sankar MR. Manikandan S.D. Gopal Ram T. Mahalingam G. Ravi 《Journal of Crystal Growth》2010,312(19):2729-2733
The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals. 相似文献
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Raman and resonance-Raman spectra of the I?3 ion isolated within CsI crystals have been studied using 647 nm and 488 nm exciting radiation. Sample temperatures between 300 and 20 K have been used. Eleven overtones of the symmetric stretching mode (nν1) have been observed in the resonance-Raman spectrum excited by the 488 nm Ar+ laser line. Bands centred at 153, 170, 264 and 304 cm?1 have been assigned as ν3, 2ν2, ν1+ν3 and 2ν3(Σ+) respectively. The remaining structure between the nν1 lines has been assigned as due to combinations of these lines with the lattice vibrations of the CsI crystal. 相似文献
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In this paper exact asymptotic formulae are found for singularvalues of the Cauchy operator and the logarithmic potentialtype operator (on a bounded domain), as well as their productswith Bergman's projection. It is shown that these spectral characteristicsdetect geometric properties of a domain (area and the lengthof the boundary). The hypothesis "can we hear the shape of adrum", from a paper by J.M. Anderson, D. Khavinson, and V. Lomonosov[Spectral properties of some integral operators arisingin potential theory, Quart. J. Math. Oxford (2) 43 (1992)387-407], is correct in the above sense. 1991 Mathematics SubjectClassification: 47B10. 相似文献
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A symmetric Ramsey-Bordé (Mach-Zehnder geometry) atom interferometer is studied as gravitational wave detector under the hypothesis of shot noise limited sensitivity. Full gauge-invariant response function is deduced via ABCD matrices approach and the resulting sensitivity is analyzed in the frequency domain. As an example, a possible use in a specific frequency range is studied in some detail. 相似文献
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In this paper, we examine the large Reynolds number (Re) asymptoticstructure of the wave number in the Orr–Sommerfeld regionfor the Blasius boundary layer on a semi-infinite flat plategiven by Goldstein (1983, J. Fluid Mech., 127, 59–81).We show that the inclusion of the term which contains the leading-ordernon-parallel effects, at O(Re– 1/2), leads to a non-uniformexpansion. By considering the far downstream form of each termin the asymptotic expansion, we derive a length scale at whichthe non-uniformity appears, and compare this position with theposition seen in plots of the wave number. 相似文献
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A stable vector algorithm for the solution of block diagonallinear systems is obtained by a permutation of the unknownscalled wrap-around partitioning combined with standard QR factorization.Wrap-around partitioning uses blocking and selects the unknownsin the blocks in turns. After a suitable orthogonal eliminationstep one ends up with a reduced system which is again blockbidiagonal and so wrap-around partitioning can be applied again.Using a simple model for vectorization overhead it is shownthat small block sizes give best performance. The minimal blocksize 2, which corresponds to cyclic reduction, is suboptimaldue to memory bank conflicts. 相似文献
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B. Dubini G. M. Guidi F. Montecchia M. Pergolini M. G. Ponzi Bossi F. Vetrano 《Il Nuovo Cimento D》1994,16(2):205-211
Summary In the present work some thermodynamic and structural aspects of electric-, magnetic- and electromagnetic-field interaction
at 50 Hz with lecithin liposomes mixed with azelaic acid or cholesterol have been investigated by using differential scanning
calorimetry and X-ray diffraction. Calorimetric scans and X-ray diffraction patterns show that no significant modifications
of the two mixtures occur, except a little increase of the freezing temperature of the free water after exposure to electromagnetic
field. 相似文献