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61.
62.
Marian Szurgot 《Crystal Research and Technology》1992,27(7):919-929
Faces of three-dimensional crystals have been divided into edge and corner ones to describe the phenomenon of their disappearance and appearance during the crystal growth. The expression for the critical growth velocity governing the presence of corner faces has been derived and verified and the validity of the previous relationship (SZURGOT , PRYWER ) for the edge faces confirmed. Three nearest neighbours control the presence of corner faces and two neighbours decide on the edge faces. 相似文献
63.
Existence of Global Weak Solutions for Coupled Thermoelasticity under Non-Linear Boundary Conditions
Marian Bien 《Mathematical Methods in the Applied Sciences》1996,19(16):1265-1277
The existence of global weak solutions for coupled thermoelasticity with non-linear contact boundary conditions corresponding to the friction problem is considered. The time-continuous Galerkin method and a priori estimates obtained with Gronwall's inequality in connection with embedding theorems are applied to accomplish a straightforward generalization of one of the results proved by Martins and Oden 9. 相似文献
64.
Marian Kryszewski 《Macromolecular Symposia》1996,104(1):17-26
Preparation of very small or nanoscopic crystallites applying wet techniques and their properties are discussed. It is shown that controlled evaporation of the solvent from the solution containing low molecular weight CT complexes and polymers leads to formation of continuous networks of microcrystallites, which are responsible for the magnetic, optical and particularly electrical properties of the obtained systems (isotropic, surface or anisotropic conductivity). Using a variation of this method one can obtain very small crystals of CT complex salts or other substances showing nonlinear optical properties. Application of the so-called “droplet technique” results in formation of the emulsion of the crystallizable compounds. The crystallization in small droplets leads to very small crystals which show, because of their nanoscopic size, different properties than bigger single crystals of these compounds. 相似文献
65.
Marian Mikoajczyk Marek Cypryk Bartomiej Gostyski Jakub Kowalczewski 《Molecules (Basel, Switzerland)》2022,27(3)
The mechanisms of three selected identity substitution reactions at phosphorus and sulfur occurring with stereospecific inversion have been investigated using density functional theory (DFT). The first identity reaction between methoxyl anion and methyl ethylphenylphosphinate 1 reported in 1963 has been shown to proceed in a stepwise fashion according to the addition–elimination (A–E) mechanism involving formation of a pentacoordinate phosphorus intermediate (TBI-1). In contrast, the results of DFT studies of the identity chloride exchange reaction in (ethoxy)ethylphosphonochloridothionate 3 in acetone solution provided evidence that it proceeds synchronously according to the classical Ingold’s SN2-P mechanism. DFT calculations of the methoxyl–methoxy exchange reaction at sulfur in methyl p-toluenesulfinate 4 catalyzed by trifluoroacetic acid in methanol revealed that it proceeds stepwise (A–E mechanism), involving the formation of the high-coordinate sulfurane intermediate. In both identity transesterification reactions, 1 and 4, the transiently formed trigonal bipyramidal intermediates with the two methoxyl groups occupying apical positions (TBI-1 and TBI-4) have higher free energy barriers for the Berry-type pseudorotation than those for direct decomposition to starting phosphinate and sulfinate ensuring stereospecific inversion of configuration at the phosphinyl and sulfinyl centers. Thus, the DFT method proved its usefulness in the distinction between both mechanisms that are often indistinguishable by kinetic measurements. 相似文献
66.
Marian Szurgot 《Crystal Research and Technology》1995,30(5):621-628
Microtopography of {100}, {110}, {111}, and {210} surfaces of sodium chlorate crystals etched in various solvents has been studied by optical microscopy. It has been established that etch pits formed on left- and right-handed crystals are chiral, and directions of dissolution steps reveal bond chains of the structure. 相似文献
67.
Jan Remsa Miroslav Jelinek Tomáš Kocourek Ji?í Oswald Marian ?erňanský Michal Jelínek 《Applied Surface Science》2009,255(10):5292-5294
High quality, thick, highly oriented crystalline thin films of Yttrium Aluminum Garnet (Y3Al5O12) and Yttrium Aluminum Perovskite (YAlO3) doped with Erbium were prepared by pulsed laser deposition. Samples were created in vacuum or oxygen environment. Depositions were arranged at room temperature, or at high substrate temperatures ranging from 800 to 1100 °C. Amorphous layers were annealed by laser, or in oven (argon flow, temperatures in range from 1200 to 1400 °C). Fused silica and sapphire (0 0 0 1) were used as substrates. Properties of films were characterized by X-ray diffraction, atomic force microscopy, and by photoluminescence measurement. Size of crystalline grains was in the range 116-773 nm. Thickness of layers was up to 17 μm. 相似文献
68.
Marian E. Robbins 《Integral Equations and Operator Theory》2002,43(4):480-487
Given a large weighted Hardy space we show there exists a composition operatorC
with that maps from that space into the unweighted Dirichlet space and lies in every Schatten p-class for 0<p<. This is in contrast to the situation in which the image space is a smaller weighted Dirichlet space. It is known that in that case it is not possible to find such a composition operator that is bounded.This research was supported in part by a summer stipend from Bellarmine College. 相似文献
69.
70.
Nuclear substructures associated with apoptosis in HeLa cells have been examined using light-microscopic morphometry, trichrome staining, spectral imaging and transmission electron microscopy. This detailed analysis reveals several sites where alterations in the normal cellular ultrastructure occur during apoptotic progression. To correlate these ultrastructural changes with the underlying molecular processes, we have characterized and quantified apoptotic cell morphology with and without inhibition of two caspases, which are key effectors of the apoptotic program. Using this analysis, early apoptotic events included: (a) the segregation of nucleolar components, a diminished granular component, and a reduction in number but increase in size of fibrillar centers, (b) an increase in the number of cytoplasmic ribosomes and (c) a very minimal increase in the amount of peripherally condensed DNA. Apoptosis progressed with: (a) an increase in the number of perichromatin granules and perichromatin fibrils, (b) a reduction in number of interchromatin granule centers concomitant with an increase in their size, (c) partial digestion and circumferential condensation of the DNA at the nuclear membrane and (d) rounding of the cytoplasm with an increase in organellar density and shrinkage in cell size. Endstage apoptotic cells showed: (a) one (or two) very large pools of incompletely digested DNA, (b) one (or two) very large interchromatin granule centers, (c) an increased number of perichromatin granules which were distanced from DNA and often closely apposed to the nucleolus, (d) formation of unusually condensed, highly coiled perinucleolar bodies and (e) blebbing of highly dense cytoplasm.In HeLa cells treated with UV and inhibitors of caspase 1 and 3, the length of time from early apoptosis to the formation of apoptotic bodies was greatly extended. Inhibiting caspase activity: (a) prevented the pooling of DNA, (b) retarded the formation of large interchromatin granule centers, (c) increased the number of perichromatin granules, (d) produced disassembly of the nucleolus, (e) prevented the formation of highly coiled perinucleolar bodies, and (f) caused vacuolization in the cell center and a unipolar blebbing of the cytoplasm.Spectral imaging in conjunction with serial section electron microscopy confirmed the staining specificities of the condensed DNA, of the large condensed interchromatin granule centers, and of the nucleoli. The results indicate that the interface between the components of the chromatin domain and the interchromatin space is a critical site of caspase activity in apoptosis, and precedes other events such as internucleosomal DNA degradation. 相似文献