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421.
Phase equilibria in the TbBr3-RbBr binary system were established from differential scanning calorimetry (DSC) measurements. This binary system is characterized by two compounds, namely Rb3TbBr6 and RbTb2Br7, and two eutectics located at the TbBr3 mole fractions, x = 0.117 (728 K) and x = 0.449 (718 K), respectively. Rb3TbBr6 undergoes a solid-solid phase transition at 728 K and melts congruently at 1047 K with the related enthalpies 7.8 and 58.7 kJ mol(-1), respectively. RbTb2Br7 melts incongruently at 803 K. It undergoes also a solid-solid phase transition at 712 K, a temperature very close to that (718 K) of the second eutectic, and much attention was paid in evidencing and separating these transition and eutectic effects. Separate investigations of the thermodynamic and transport properties were performed on the Rb3TbBr6 compound. These heat capacity and electrical conductivity experimental results suggest an order-disorder mechanism in the alkali-metal cation sublattice whereas the TbBr6 octahedra, forming the anionic sublattice, retain their normal lattice positions. 相似文献
422.
Leszek Olszowy 《Central European Journal of Mathematics》2014,12(4):623-635
This paper is concerned with the existence of mild solutions for impulsive semilinear differential equations with nonlocal conditions. Using the technique of measures of noncompactness in Banach and Fréchet spaces of piecewise continuous functions, existence results are obtained both on bounded and unbounded intervals, when the impulsive functions and the nonlocal item are not compact in the space of piecewise continuous functions but they are continuous and Lipschitzian with respect to some measure of noncompactness, and the linear part generates only a strongly continuous evolution system. 相似文献
423.
Tomasz Klimsiak Maurycy Rzymowski Leszek Słomiński 《Stochastic Processes and their Applications》2019,129(4):1153-1184
We consider reflected backward stochastic different equations with optional barrier and so-called regulated trajectories, i.e. trajectories with left and right finite limits. We prove existence and uniqueness results. We also show that the solution corresponds to the value of an optimal stopping problem and may be approximated by a modified penalization method. 相似文献
424.
Leszek Doszczak Witold Przychodzen Dariusz Witt Janusz Rachon 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1851-1854
Recently we have developed a convenient method for the synthesis of S -thioacyl dithiophosphates 1 , excellent thioacylating reagents. When hydroxylamines with one bulky group or two substituents on the nitrogen atom are treated with S -thioacyl dithiophosphates 1 O -thioacyl hydroxylamines 3 are produced exclusively. What is more important, compounds 3 undergo interesting reaction with dithiophosphoric acid 4 yielding amine and acyl thiophosphoryl disulfide 5 . The disulfide 5 can be formed as a product of thiophilic attack of the dithiophosphate anion on the thiocarbonyl group in protonated O -thioacyl hydroxylamine 3 . On the other hand, it is well known that dithiophosphate anions easily undergo one electron oxidation. Hence the dithiophosphate anion can act as single electron donor and disulfide 5 can be formed as a product of the SET reaction. The influence of light and radical traps strongly suggests that the second possibility operates in the reaction in focus. 相似文献
425.
Michael Heller Zdzisław Odrzygóźdź Leszek Pysiak Wiesław Sasin 《International Journal of Theoretical Physics》2008,47(10):2566-2575
We study a purely gravitational Aharonov-Bohm effect. The space-time curvature is concentrated in the quasiregular singularity
of a cosmic string, outside of which space-time is (locally) flat. The symmetries of this field configuration are described
by the groupoid symmetries rather than by the usual group symmetries. The groupoid in question is formed by homotopy classes
of piecewise smooth paths in the cosmic string region. A gravitational counterpart of the Aharonov-Bohm effect occurs if the
symmetry of the system, with respect to the groupoid action, is broken down. 相似文献
426.
The paper presents the effect of HPD laser treatment on the microstructure and selected properties of the PVD CrN, (Ti,Al) and Ti(C,N) coatings deposited onto hot-work tool steel substrates. The microstructure and surface topography of the investigated samples are characteristic of the diversified morphology connected with the applied laser beam power. Employment of laser beam at 0.7 kW power to the laser treatment of samples with Ti(C,N) coatings causes clear coating adhesion growth because of the diffusive processes induced by heat release. Because of the higher value of the (Ti,Al)N absorption coefficient one can state that the observed substrate materials change and finally coatings destruction in case of those samples is the most noticeable. The moderate effect of the laser beam treatment of the hot-work tool steel with the PVD coating was observed for CrN coatings. However, for laser beam power above 0.5 kW differences in the thermal expansion coefficients of the substrate materials and coatings generate coating crackings. 相似文献
427.
Hanna Rostkowska Leszek Lapinski Maciej J. Nowak 《Journal of Physical Organic Chemistry》2010,23(1):56-66
Monomers of 5‐mercapto‐1,3,4‐thiadiazole‐2‐thione (bismuthiol) were studied using an experimental matrix‐isolation technique as well as by carrying out theoretical quantum chemical calculations. The calculations, performed using the quadratic configuration interaction method with single and double excitations (QCISD)/6‐31++G(d,p)//DFT(B3LYP)/6‐311++G(2d,p), predict that the thione–thiol tautomer of bismuthiol should be significantly (by more than 19 kJ mol?1) more stable than other tautomeric forms. Accordingly, only the signatures of the thione–thiol tautomer were observed in the FT‐IR spectrum of bismuthiol, recorded directly after deposition of an Ar matrix. UV (λ > 320 nm) irradiation induced the conversion of the thione–thiol tautomer into the dithiol form. Analogous investigations were carried out for two related compounds: 5‐methyl‐1,3,4‐thiadiazole‐2‐thione and 5‐methylthio‐1,3,4‐thiadiazole‐2‐thione. For these two species, only the thione tautomeric forms were observed after deposition of Ar matrices. These tautomers were predicted (by QCISD calculations) to be more stable (by at least 19 kJ mol?1) than other tautomeric forms. Upon UV irradiation, the most stable thione forms of these compounds were transformed into the corresponding thiol tautomers. Direct observation of the thione → thiol phototautomeric processes provides a clear proof that intramolecular proton transfer reaction can occur in molecules, such as bismuthiol, in spite of the increased NH···S distance, in comparison to other phototautomerizing species studied so far. All the isomers of the studied compounds (substrates and products of the photoreactions) were identified by comparison of their IR spectra with the spectra calculated at the DFT(B3LYP)/6‐311++G(2d,p) level of theory for possible isomeric structures. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
428.
Raw powders of BaHfO3:Ce were prepared with modified Pechini process and were calcined in the 650–1700 °C range of temperatures, at different atmospheres – air, vacuum and nitrogen–hydrogen mixture. The powders were converted into sintered ceramics by vacuum sintering. The materials were characterized by XRD, TEM, photoluminescence and radioluminescence spectroscopy. UV-VUV excitation spectra were recorded using synchrotron radiation. Excitation spectra proved that atmosphere of preparation significantly influences the host-to-activator energy transfer, which is the most efficient for materials made in reducing conditions. Also radioluminescence efficacy was found to be superior for materials prepared in such conditions. 相似文献
429.
Andrzej Ziabicki Leszek Jarecki Angelo Perico Marina Guenza 《Macromolecular theory and simulations》1995,4(4):643-654
A semi-empirical formula for orientational relaxation times of worm-like chains in dilute solutions is proposed where τrod = τ0N3 is the relaxation time of a rigid rod composed of N segments, and x = 2a/L is the chain rigidity, i.e. the ratio of the double persistence length to the chain contour length, L. The formula, which can be used in the entire range of molecular rigidities and chain lengths, has been tested against segment relaxation times for semi-rigid chains calculated from the optimized Rouse-Zimm model. 相似文献
430.
Emilia Klimaszewska Malgorzata Zieba Klaudia Gregorczyk Leszek Markuszewski 《Molecules (Basel, Switzerland)》2021,26(23)
Traditional technologies applied for obtaining plant raw materials for cosmetic production are based primarily on high-level processing, which is reflected in the qualitative composition of the resulting materials. By using low-temperature drying, it is possible to retain in the raw materials a range of valuable ingredients. In this study, blue honeysuckle powder was used as an ingredient of cosmetic face masks. The stability of the masks was evaluated. Dynamic viscosity, yield point and texture analysis of the cosmetics was performed. The color of the emulsions and the level of skin hydration after face mask application was determined. Emulsions were found to be stable. A decrease in dynamic viscosity of the emulsions as a function of increasing concentrations of the additive and under the conditions of rising rotational speed were observed. Similarly, an increase in the concentration of blue honeysuckle in the emulsions resulted in a decrease in the value of the yield point. Based on the results, it can be stated that the addition of blue honeysuckle caused a decrease in hardness of the masks, while the opposite trend was observed for adhesive force. It was found that an increase in the concentration of blue honeysuckle gave a reddish-yellow color to the samples. Corneometric assessment confirmed proper skin hydration after the application of the emulsions. 相似文献