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排序方式: 共有166条查询结果,搜索用时 265 毫秒
31.
32.
Density functional theory (DFT) calculations have been performed to determine the interaction energy between a CO probe molecule and all atoms from the first three rows of the periodic table coadsorbed on Rh(100), Pd(100) and Ir(100) metal surfaces. Varying the coverage of CO or the coadsorbed atom proved to have a profound effect on the strength of the interaction energy. The general trend, however, is the same in all cases: the interaction energy becomes more repulsive when moving towards the right along a row of elements, and reaches a maximum somewhere in the middle of a row of elements. The absolute value of the interaction energy between an atom-CO pair ranges from about -0.40 eV (39 kJ mol(-1)) attraction to +0.70 eV (68 kJ mol(-1)) repulsion, depending on the coadsorbate, the metal and the coverage. The general trend in interaction energies seems to be a common characteristic for several transition metals. 相似文献
33.
34.
Ian C. Watson André Schumann Haoyang Yu Prof. Dr. Emma C. Davy Dr. Robert McDonald Dr. Michael J. Ferguson Prof. Dr. Christian Hering-Junghans Prof. Dr. Eric Rivard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9678-9690
New N-heterocyclic olefins (NHOs) are described with functionalization on the ligand heterocyclic backbone and terminal alkylidene positions. Various PdII–NHO complexes have been formed and their use as pre-catalysts in Buchwald–Hartwig aminations was explored. The most active system for catalytic C−N bond formation between hindered arylamine and arylhalide substrates was accessed by combining a backbone methylated NHO with [Pd(cinnamyl)Cl]2 in the presence of NaOtBu as a base. In these active systems evidence suggests that catalysis is mediated by colloidal palladium metal, highlighting a different coordination ability of NHOs in comparison with commonly used N-heterocyclic carbene co-ligands. 相似文献
35.
R. Manasseh R. F. LaFontaine J. Davy I. Shepherd Y.-G. Zhu 《Experiments in fluids》2001,30(6):672-682
Passive acoustic bubble sizing was investigated in both controlled tests and in a stirred, sparged tank typical of the biotechnology
or minerals processing industries. Acoustic techniques have promise for industrial systems where other bubble analysis methods
are impractical. Acoustic signals were studied for bubbles precisely formed at higher airflow rates. Acoustic pulses varied
with bubble production rate as well as with bubble size. A technique of windowing pulses is proposed. Two alternative versions
of this windowing technique were applied to a stirred, sparged tank, giving good agreement. It was shown that, in some cases,
it may also be possible to acoustically estimate the spatial distribution of void fraction.
Received: 13 June 2000/Accepted: 19 October 2000 相似文献
36.
Amarande Murisier Marie Andrie Szabolcs Fekete Matthew Lauber Valentina D'Atri Katharina Iwan Davy Guillarme 《Journal of separation science》2022,45(12):1997-2007
The present study describes the possibilities offered by an innovative bioinert size exclusion chromatography column for size variant characterization of complex monoclonal antibody products. This size exclusion chromatography column includes a novel column hardware surface. The column was prepared from metallic hardware components that were treated to have prototype hydrophilically modified hybrid organic–inorganic silica surfaces called hybrid surface technology. This provides a significant reduction in nondesired hydrophobic and electrostatic interactions that can occur between column and analyte when performing size exclusion chromatography analysis with volatile mobile phase. Compared to a reference stainless-steel column packed with the same batch of packing material, peak tailing, band broadening, and above all recovery of high molecular weight species were distinctly improved for all types of monoclonal antibody products. Based on our observations, we found that 50 mM ammonium acetate in water was a suitable mobile phase offering good compromise in terms of liquid chromatography performance and mass spectrometry sensitivity. In addition, method repeatability (intra- and interday relative standard deviations) on elution times and high molecular weight species peak areas were found to be excellent. By using this innovative size exclusion chromatography material, the low and high molecular weight species contained in various stressed and nonstressed monoclonal antibody products were successfully characterized with mass spectrometry detection. 相似文献
37.
In recent years, models for (possibly multivariate) skewed distributions have become more and more popular. In the univariate case, Ferreira and Steel (2006) [Ferreira, J.T.A.S., Steel, M.F.J., 2006. A constructive representation of univariate skewed distributions. J. Amer. Statist. Assoc. 101, 823–829] introduced general skewing mechanisms in order to compare existing skewing methods in a common framework and to ease construction of new such methods according to the needs in given situations. In this paper, we make use of the classical transformation approach to define alternative skewing mechanisms for the same purpose. While keeping all the nice features of Ferreira and Steel’s skewing mechanisms (flexibility, surjectivity, the possibility of retaining prespecified characteristics of the original symmetric distribution, etc.), our skewing mechanisms, unlike theirs, can easily be extended to the multivariate case. We describe our skewing schemes, investigate their main properties, and illustrate their effects on standard (multi)normal distributions by means of a few examples. Finally, we briefly discuss their relevance in the context of optimal symmetry testing. 相似文献
38.
E. D. Davy J. Rosin W. H. Blome R. W. Morrison R. Eder W. Stucki L. van Itallie B. Kljatschkina J. M. A. Hegland A. Leulier B. Drevon L. Kofler A. Kofler A. I. Portnow E. N. Winogradowa L. Ekkert A. R. Bliss Jr. N. T. Chamberlin R. I. Grantham 《Analytical and bioanalytical chemistry》1935,102(9-10):376-384
39.
Pamela J. Davy 《Probability Theory and Related Fields》1984,68(2):243-246
Summary A conjecture concerning the maximum mean secant length through a convex body of fixed volume in
n
is verified, and other moment inequalities are established using a symmetrisation argument. 相似文献
40.
Rinda Hedwig Wahyu Setia Budi Syahrun Nur Abdulmadjid Marincan Pardede Maria Margaretha Suliyanti Tjung Jie Lie Davy Putra Kurniawan Koo Hendrik Kurniawan Kiichiro Kagawa May On Tjia 《Spectrochimica Acta Part B: Atomic Spectroscopy》2006,61(12):1285-1293
The applicability of spectrochemical analysis for liquid and powder samples of minute amount in the form of thin film was investigated using ultraviolet Nd-YAG laser (355 nm) and low-pressure ambient air. A variety of organic samples such as commercial black ink usually used for stamp pad, ginseng extract, human blood, liquid milk and ginseng powder was prepared as film deposited on the surface of an appropriate hard substrate such as copper plate or glass slide. It was demonstrated that in all cases studied, good quality spectra were obtained with very low background and free from undesirable contamination by the substrate elements, featuring ppm or even sub-ppm sensitivity and worthy of application for quantitative analysis of organic samples. The proper preparation of the films was found to be crucial in achieving the high quality spectra. It was further shown that much inferior results were obtained when the atmospheric-pressure (101 kPa) operating condition of laser-induced breakdown spectroscopy or the fundamental wavelength of the Nd-YAG laser was employed due to the excessive or improper laser ablation process. 相似文献