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61.
The kinetic resolution of alpha-acetoxy N-acyl oxazolidinethiones using the chiral, nonracemic O-nucleophilic acyl transfer catalyst 8 is described. The reaction proceeds on a variety of substrates in excellent yields, with s-factors ranging from 17 to 31. 相似文献
62.
63.
Tarek Kenzizi 《Applicable analysis》2013,92(5):892-912
In this work, we investigate perturbed parabolic problem on measure spaces. For strongly local Dirichlet form, we obtain some results on existence and uniqueness of nonnegative solution. We also presented some examples as an applications. 相似文献
64.
Different functions describing matrix-fracture transfer were tested for counter-current capillary imbibition interaction.
The recovery curves obtained from capillary imbibition experiments were used to fit the transfer functions. The exponential
coefficients yielding the best fit to the experimental data were obtained and correlated to the effective parameters such
as viscosity, IFT, matrix length and diameter, matrix permeability and porosity, and wettability using multivariable regression
analysis. In order to obtain the recovery curves, experiments were conducted on Berea sandstone and Indiana limestone samples.
Cylindrical samples with different shape factors were obtained by cutting the plugs 1, 2.5, and 5 cm in diameter and 2.5,
5, and 10 cm in length. All sides were coated with epoxy except one end. More than fifty static imbibition experiments were
carried out on vertically and horizontally situated samples where the imbibition took place upward and lateral directions,
respectively. Brine–air, brine–kerosene, brine–mineral oil, and surfactant solution–mineral oil pairs were used as fluids.
For many matrix shape factors (especially longer and small diameter ones), dividing the recovery curve into three parts were
needed as the early, intermediate, and late times, which are typically distinguished by the time required for the imbibition
front to reach the closed boundary at the end of the core. Correlations among the exponential coefficients and rock/fluid
properties were developed. It was observed that different rock/fluid properties and transfer mechanisms (capillary imbibition
and gravity drainage) govern the process for each part. Hence, the analyses done in this study were useful not only for developing
explicit transfer functions but also identifying the physics of the counter-current imbibition recovery. 相似文献
65.
Awad TS Helgason T Kristbergsson K Weiss J Decker EA McClements DJ 《Langmuir : the ACS journal of surfaces and colloids》2008,24(22):12779-12784
The purpose of this study was to determine whether temperature scanning ultrasonic velocity measurements could be used to monitor the complex thermal transitions that occur during the crystallization and melting of triglyceride solid lipid nanoparticles (SLNs). Ultrasonic velocity ( u) measurements were compared with differential scanning calorimetry (DSC) measurements on tripalmitin emulsions that were cooled (from 75 to 5 degrees C) and then heated (from 5 to 75 degrees C) at 0.3 degrees C min (-1). There was an excellent correspondence between the thermal transitions observed in deltaDelta u/delta T versus temperature curves determined by ultrasound and heat flow versus temperature curves determined by DSC. In particular, both techniques were sensitive to the complex melting behavior of the solidified tripalmitin, which was attributed to the dependence of the melting point of the SLNs on particle size. These studies suggest that temperature scanning ultrasonic velocity measurements may prove to be a useful alternative to conventional DSC techniques for monitoring phase transitions in colloidal systems. 相似文献
66.
In his landmark paper on amalgamation published in Algebra Universalis in 1971, Don Pigozzi posed some open questions in connection
with amalgamation of subclasses of cylindric algebras. Some of these questions were originally raised by Comer, Daigneault,
Johnson, McKenzie and others. In this paper we give answers to all these as well as a number of other related questions. Most
of the solutions were found by the authors of this paper. However, a few were contributed by others who will of course be
given due credit at the appropriate points.
This paper is dedicated to Don Pigozzi on his retirement.
Presented by R. W. Quackenbush.
The first author’s research was supported by the Hungarian National Foundation for Scientific Research grants no T30314 and
T23234. The second author’s research was supported by the Hungarian National Foundation for Scientific Reserach OKTA grant
no T30314. All the new results in this article were announced by Judit Madarász in the Workshop on Abstract Algebraic Logic,
held in Centre de Recerca Matematica Bellaterra, Spain July 1–5, 1997.
Received December 15, 2002; accepted in final form January 3, 2006. 相似文献
67.
Alaa S. Abd‐El‐Aziz Erin K. Todd Tarek H. Afifi 《Macromolecular rapid communications》2002,23(2):113-117
This communication is focused on the controlled design of star‐shaped aromatic ethers with pendent cyclopentadienyliron moieties. A trimetallic core was prepared, which was then reacted with a number of oligomeric ether complexes to give star‐shaped polymers with six, nine, twelve and fifteen pendent cationic cyclopentadienyliron moieties. Cyclic voltammetric studies showed reduction of the iron centers between –0.99 and –1.41 V. Thermogravimetric analysis showed that loss of the metallic moieties occurred between 225 and 284°C. 相似文献
68.
Mass spectral studies on 1‐n‐pentyl‐3‐(1‐naphthoyl)indole (JWH‐018), three deuterium‐labeled analogues and the inverse isomer 1‐naphthoyl‐3‐n‐pentylindole 下载免费PDF全文
69.
H. Imao M. Tarek K. Michishio Y. Enomoto T. Shimoyama Y. Kanai N. Kuroda A. Mohri H. Higaki H. Saitoh H. A. Torii Y. Nagata H. Toyoda Y. Matsuda Y. Nagashima Y. Yamazaki 《Hyperfine Interactions》2009,194(1-3):71-76
Our group “ASACUSA MUSASHI” has established an efficient way for accumulating antiprotons and extracting them as intense ultra-slow mono-energetic beams at the CERN-AD facility. This novel beam opens new frontiers for investigating a variety of physics. For realizing H? spectroscopy and the test for charge-parity-time symmetry, we have also developed the cusp trap, a combination of an anti-Helmholz superconducting coil and a multi-ring electrode trap, for trapping both antiprotons and positrons and then synthesizing antihydrogens. Recently, the cusp trap was practically used to accumulate antiprotons. The last piece for synthesizing antihydrogens in the cusp trap is the positron accumulator. We have developed a compact system to effectively accumulate positrons based on N2 gas-buffer scheme with a specially designed high precision cylindrical multi-ring electrode trap. The recent progress of the developing work is an important milestone for upcoming antihydrogen science of ASACUSA MUSASHI. 相似文献
70.
Tarek Ben Salah Hatem Garrab Sami Ghedira Bruno Allard Damien Risaletto Christophe Raynaud Kamel Besbes Herv Morel 《Superlattices and Microstructures》2006,40(4-6):580
The paper evaluates the optimal design of the low-doped base region inside power diodes and other bipolar devices. It is demonstrated theoretically that a low-doped base region of P+N−N+ diodes can provide a high breakdown voltage and an optimal on-resistance . A simple, accurate and CPU timesaving approach is presented to extract an optimal value for the base region width, WB, and its doping concentration, ND. The paper details an analytical relation between WB and ND, and gives a method for quantifying the trade-off between their values for a given breakdown voltage and for obtaining the minimal on-resistance. Analytical results are confronted with experimental results for 4H-SiC- and 6H-SiC-based diodes. 相似文献