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81.
An Einstein model is used to calculate the internal vibrational free energy of approximately spherical fcc crystallites as a function of crystallite size at T/θ = 1. It is found that the free energy per surface atom does not become convergent until a size of about 3 × 107 atoms is reached. The excess free energy at convergence is used to define the macroscopic surface tension for use in the capillarity approximation. The internal free energy of microcrystallites containing of the order of 100 atoms is fortuitously well described by the capillarity approximation. A good estimate of the total free energy of the microcrystallite (nucleus) is obtained from the capillarity approximation only by adding the contributions from free translation and rotation and the replacement partition function. 相似文献
82.
We employ the Monte Carlo simulation method of classical statistical mechanics to study the structure and energetics of the crystal/amorphous interface. The interface is found to be approximately four atomic layers thick and provides good bonding between the amorphous and crystalline phases. 相似文献
83.
The treatment of O-alkyllactonium tetrafluoroborate salts with anh. NaSH in CH3CN at 0°C led to five-, six-, and seven-membered thionolactones (44– 90% yield). 相似文献
84.
Margarida Baía Farid Bozorgnia Léonard Monsaingeon Juha Videman 《Journal of Mathematical Analysis and Applications》2018,457(1):77-103
The objective of this work is to study a coupled system of degenerate and nonlinear partial differential equations governing the transport of reactive solutes in groundwater. We show that this system admits a unique weak solution provided the nonlinear adsorption isotherm associated with the reaction process satisfies certain physically reasonable structural conditions, by addressing a more general problem. In addition, we conclude, that the solute concentrations stay non-negative if the source term is componentwise non-negative and investigate numerically the finite speed of propagation of compactly supported initial concentrations, in a two-component test case. 相似文献
85.
86.
El Gabaly F Gallego S Muñoz C Szunyogh L Weinberger P Klein C Schmid AK McCarty KF de la Figuera J 《Physical review letters》2006,96(14):147202
By means of spin-polarized low-energy electron microscopy, we show that the magnetic easy axis of one to three atomic-layer thick cobalt films on Ru(0001) changes its orientation twice during deposition: One-monolayer and three-monolayer thick films are magnetized in plane, while two-monolayer films are magnetized out of plane. The Curie temperatures of films thicker than one monolayer are well above room temperature. Fully relativistic calculations based on the screened Korringa-Kohn-Rostoker method demonstrate that only for two-monolayer cobalt films does the interplay between strain, surface, and interface effects lead to perpendicular magnetization. 相似文献
87.
This paper develops a new numerical technique to price an American option written upon an underlying asset that follows a bivariate diffusion process. The technique presented here exploits the supermartingale representation of an American option price together with a coarse approximation of its early exercise surface that is based on an efficient implementation of the least-squares Monte–Carlo algorithm (LSM) of Longstaff and Schwartz (Rev Financ Stud 14:113–147, 2001). Our approach also has the advantage of avoiding two main issues associated with LSM, namely its inherent bias and the basis functions selection problem. Extensive numerical results show that our approach yields very accurate prices in a computationally efficient manner. Finally, the flexibility of our method allows for its extension to a much larger class of optimal stopping problems than addressed in this paper. 相似文献
88.
Ilyas S. Nizamov Farid D. Yambushev Ilnar D. Nizamov Alexandra D. Voloshina Vladimir A. Alfonsov 《Heteroatom Chemistry》2013,24(1):36-42
The Kabachnik–Fields reaction of E,Z‐citral with diethyl phosphite in the presence of isobutylamine has been found to form α‐aminophosphonates. The Pudovik reactions of diethyl phosphite with prenyl imines prepared on the basis of E,Z‐citral with isobutylamine also allowed us to obtain the same α‐aminophosphonates. We have managed to synthesize α‐aminophosphonates by the reaction of O,O‐dialkyl trimethylsilyl phosphites with prenyl imines in the presence of water or diethylamine. α‐Aminophosphonates were also synthesized by the reaction of diethyl phosphite with (R,S)‐citronellal in the presence of alkylamines. α‐Aminophosphonates obtained showed bacteriostatic activity against Staphylococcus aureus and Bacillus cereus. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:36–42, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21060 相似文献
89.
90.
Ijaz Ahmad Khan Syed Anwaar Hussain Amjad Farid Ali Hussnain Zeshan Adeel Umar Rajdeep Singh Rawat 《辐射效应与固体损伤》2013,168(11-12):929-943
ABSTRACTCrystalline silicon oxy-nitride (SiON) composite films are deposited on Si substrate for multiple (5, 15, 25 and 50) focus shots (FS) by plasma focus device. The X-rays diffraction patterns reveal the development of various diffraction peaks related to Si, Si3N4, and SiO2 phases which confirms the formation of SiON composite film. The intensity of Si3N4 (1 0 2) plane is linearly increased with the increase of FS. The Si3N4 (1 0 2) phase does not nucleate for 5 FS. Raman analysis confirms the formation of β–Si–N phase. Raman and Fourier transform infrared spectroscopy analysis reveals that the strength of chemical bonds like Si–N, Si–O formed during the deposition process of SiON composite films is associated with the bonds intensity which in turn depends on the number of FS. The field emission scanning electron microscopic analysis reveals that the surface morphology like size, shape and distribution of micro/nano-dimensional particles, film compactness and the formation of micro-rods, micro-teethes and micro-tubes of SiON composite films is entirely associated with the rise in substrate surface transient temperature which in turn depends on the increasing number of FS. The EDX spectrum confirms the presence of Si (22.5?±?4.7 at. %), N (13.4?±?4.5 at. %) and O (54.7?±?11.3 at. %) in the SiON composite film. The thickness of SiON composite film deposited for 50 FS is found to ~15.47?µm. 相似文献