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101.
A numerical parametric study of the flow field which develops when a planar shock wave impinge on a rigid porous material
is presented. This study complements an earlier study (Levy et al. 1996a) where the values of some dominating parameters were
estimated and the dependence of the resulting flow field on these values was not checked.
Received 22 April 1996 / Accepted 5 January 1997 相似文献
102.
A perturbation technique developed by Karihaloo et al. is employed to obtain the stress intensity factors at the tip of a kinking crack that emanates from the free surface of a beam under pure bending. Under the condition that the kink extends in the direction of vanishing K11 the crack path is obtained as well as a path stability condition. From conditions on K1 a material parameter r* akin to that of Ramulu and Kobayashi's rc is obtained. By analysis of the slope of the kinking crack a stability condition is obtained corroborating the stability condition from consideration of vanishing K11. It is shown that for a beam in pure bending the nonsingular remote stress term T must be greater than some positive critical value for kinking to occur confirming the results of Sayir and Schindler. 相似文献
103.
Conjugating flexible polymers (such as oligosaccharides) to proteins or confining a protein in a restricted volume often increases protein thermal stability. In this communication, we investigate the interplay between conjugation and confinement which is not trivial as the magnitude and the mechanism of stabilization are different in each instance. Using coarse-grained computational approach the folding biophysics is studied when the protein is placed in a sphere of variable radius and is conjugated to 0-6 mono- or penta-saccharides. We observe a synergistic effect on thermal stability when short oligosaccharides are attached and the modified protein is confined in a small cage. However, when large oligosaccharides are added, a conflict between confinement and glycosylation arises as the stabilizing effect of the cage is dramatically reduced and it is almost impossible to further stabilize the protein beyond the mild stabilization induced by the sugars. 相似文献
104.
105.
The lowest ionization potential and transition energies of methane are calculated by a second-order perturbation expansion, using a limited basis of gaussian-type orbitals. An attempt is made to rationalize the choice of basis atomic orbitals. This procedure yields 13·8 eV for the first ionization potential and 10·4 eV for the lowest allowed transition provided a diffuse molecular orbital is added to describe the excited state (the experimental values are 13·6 and 9·7 eV). These two values include contributions of -1·0 and -0·70 eV, respectively, from an approximate optimization of the basis atomic orbitals and of +0·50 and +0·25 eV from electron correlation. 相似文献
106.
The nuclear magnetic shielding of 29Si, 31P, 33S and 35Cl in SiH4, PH3, SH2 and ClH has been computed. The inner shells of the heavy atom are not introduced in the calculation for the molecule. Their effect on the valence shell is represented by a pseudo-potential. The agreement with available theoretical and experimental values is satisfactory. 相似文献
107.
108.
W. Hempel C. Paal W. Hartmann G. A. Burrell G. G. Oberfell O. Brunck Mathers J. E. Lee J. W. Robertson F. M. Seibert P. Lebeau A. Damiens O. Brunck L. A. Levy F. St. Sinnatt B. J. Cramer E. H. Weiskopf J. I. Graham Th. F. Winmill F. Haber F. Löwe O. Mohr R. L. von Klemperer O. Wolft E. Müller E. Reinhardt J. N. Pring Juan Calafat y Leon M. Guichard R. Nowicki John J. Griffin A. Sons L. Hamburger H. Filippo Izn Ch. Moureau G. Lunge und A. Rittener 《Fresenius' Journal of Analytical Chemistry》1915,54(10):504-509
Ohne Zusammenfassung 相似文献
109.
Vijay M. Rao Donald G. Mitchell Robert M. Steiner Matthew D. Rifkin D.Lawrence Burk Jr. David Levy Samir K. Ballas 《Magnetic resonance imaging》1988,6(6):661-667
Since considerable expansion of hematopoietic marrow occurs in patients with sickle cell anemia (SCA), magnetic resonance images of 20 hips in 10 patients with known homozygous SCA were reviewed to determine a) if low signal hematopoietic marrow extended into the femoral capital epiphysis and b) if the MR characteristics of avascular necrosis (AVN) differed depending on the type of epiphyseal marrow. Our results revealed variable epiphyseal marrow type; mixed (fatty and hematopoietic) marrow (42%), fatty marrow (32%), hematopoietic marrow (16%) and hemosiderotic marrow (10%). AVN occurred irrespective of the underlying marrow. Segmental areas of low signal intensity in variable shapes (ring, band, crescent or large homogeneous area) was the most consistent MR manifestation of AVN in SCA. A low signal intensity peripheral rim surrounding a central zone, isointense with epiphyseal marrow on T1 and T2 weighted images, was most frequently observed similar to that described in patients without hemoglobinopathy. The notable difference, however, was of segmental areas within the same femoral head that demonstrated variable central zone signal on T2 weighted images. Further, while an increase in hip joint fluid is commonly seen with both early and advanced AVN in patients without hemoglobinopathy; it was increased in only one hip in patients with SCA. The observed differences in MR characteristics may be due to different pathophysiology of AVN in patients with SCA. 相似文献
110.
Investigation of the photochromic system TPID/CHCl3 (TPID = triphenylimidazolyl dimer) in a CSTR provided the first example of isothermal photochemical bistability. The reaction mechanism was established and the relevant kinetic and spectroscopic parameters were estimated experimentally. In order to predict the quantitative dynamic behavior of the TPID/CHCl3 system these parameters were refined numerically using batch reactor data. The adjusted model simulates very accurately bistability either as a function of residence time τ, or as a function of incident photon flux I0. 相似文献