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921.
A. E. Kochetov A. S. Mikhaylushkin 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):441-444
We report the results of our first-principles studies
of the interaction between an infinite monoatomic gold nanowire and
a carbon-monoxide molecule. We show that the gold
monoatomic nanowire is capable of absorbing the CO molecule at the
distances of about 1.8 ? and forms a bond with the carbon atom.
Further, we find that dissociation of the
CO molecule as the source of gold nanowire contamination with carbon, which is
widely discussed in literature as the possible reason for
the striking stability of gold nanowires under stretching, is thermodynamically
unfavored. 相似文献
922.
M. Choraś 《Opto-Electronics Review》2008,16(1):85-96
Geometrical methods of feature extraction from ear images in order to perform human identification are presented. Geometrical
approach is motivated by the actual procedures used by police and forensic experts (so-called ear otoscopy). In their work,
geometrical features of ears such as size, height, width, and shapes of earlobe are useful and valid proofs of identity. The
contribution of the article is development of the new and original methods of geometrical feature extraction from 2D ear images.
Four novel algorithms of ear feature extraction from contour images are described in detail. Moreover, identification results
obtained for each of the methods, based on the distance of feature vectors in the feature space, are presented. 相似文献
923.
924.
925.
王立中 《中国科学A辑(英文版)》2002,45(12):1578-1581
In this paper, we focus on the structure of p-blocks with defect group satisfying some special condition. These special conditions
include: two elements of the defect group are conjugate to each other in defect D if and only if they are conjugate to each
other in G; the number of conjugacy classes whose p-part is contained in P by conjugacy is not larger than ∣P∣ 相似文献
926.
W.H. Enright 《Numerical Algorithms》2002,31(1-4):125-137
In the last decade it has become standard for students and researchers to be introduced to state-of-the-art numerical software through a problem solving environment (PSE) rather than through the use of scientific libraries callable from a high level language such as Fortran or C. In this paper we will identify the constraints and implications that this imposes on the ODE software we investigate and develop. In particular, the way a numerical solution is displayed and viewed by a user dictates that new measures of performance and quality must be adopted. We will use the MATLAB environment and ODE software for initial value problems, boundary value problems and delay problems to illustrate the issues that arise and the progress that has been made. One of the major implications is the expectation that accurate approximations at off-mesh points must be provided. Traditional numerical methods for ODEs have produced approximations to the underlying solution on an associated discrete, adaptively chosen mesh. In recent years it has become common for the ODE software to also deliver approximations at off-mesh values of the independent variable. Such a feature can be extremely valuable in applications and leads to new measures of quality and performance which are more meaningful to users and more consistently interpreted and implemented in contemporary ODE software. Numerical examples of the robust and reliable behaviour of such software will be presented and the cost/reliability trade-offs that arise will be quantified. 相似文献
927.
N. B. Éshkobilov 《Journal of Applied Spectroscopy》2002,69(3):477-479
The main series of a silver atom with n = 5–70 are investigated. Perturbations of the np
2
P
1/2,3/2 states with n = 10 and 17 caused by interaction with the selfionization 4d5s5p
4
P
1/2,3/2 states are detected. Energies of the selfionization states are determined. 相似文献
928.
Ceramic hollow microspheres (CHMSs) were prepared to use as supports for the removal of heavy metal ions from industrial waste-water. A water extraction sol–gel technique was used to prepare porous CHMS by extracting water from an emulsion of LUDOX (silica colloid; SiO2, Aldrich Co.) and 2-ethyl-1-hexanol. Experiments were conducted to control pore size, wall thickness, and separation yield by examining the ratio of precursors (LUDOX and 2-ethyl-1-hexanol), catalyst (NH4OH), sintering temperature, surfactant (SPAN 80), extractant (n-butanol), stirring speed, and concentration of precursor (LUDOX). The results revealed that the optimum conditions were 20 ml of a 10 wt% solution of LUDOX, 10 ml of NH4OH, a sintering temperature of 500°C, 0.4 ml of SPAN 80, 200 ml of n-butanol, and a stirring speed of 730 rpm/100 ml of 2-ethyl-1-hexanol. CHMSs were impregnated in Cyanex 272 and examined for their ability to remove heavy metal ions from a solution. Based on an experiment involving the removal of metal ions using CHMSs that were prepared under optimum conditions, Zn ion was removed at a level of 0.354 mmol/g at pH 4, which was about twice the adsorption capacity of CHMSs prepared by Wilcox (Mater. Res. Soc. Symp. Proc.346, 201 (1994)). 相似文献
929.
The effect of the grain boundary microstructure on the anisotropy and coercivity was investigated in an HDDR Nd-Fe-B permanent
magnetic alloy. Considering the special microstructure of its magnetic powder grain, an anisotropic theoretical model influenced
simultaneously by the structure defect at the grain boundary and the exchange coupling interaction was put forward. The variations
of the structure defect factors based on the nucleation and pinning mechanism with 2r
0/lex (where r
0 and lex are the defect thickness and the length of exchange coupling, respectively) were calculated. The results show that the coercivity
mechanism of an HDDR Nd-Fe-B permanent magnetic alloy is greatly related to its microstructure defect at the grain boundary.
For a fixed lex, when 2r
0/lex < 1.67, the coercivity is controlled by the pinning mechanism; when 2r
0/lex > 1.67, it is determined by the nucleation mechanism. The coercivity reaches the maximum when 2r
0/lex = 1.67. The calculation result is consistent well with the experimental result given by Morimoto et al.
Supported by the National Natural Science Foundation of China (Grant No. 50671055) 相似文献
930.
啤酒酵母中β-(1-3)葡聚糖的提取及其性能分析 总被引:7,自引:0,他引:7
本文采用Sevage脱蛋白法、酸溶液浸提法、碱溶液浸提法对啤酒废酵母细胞壁中的β-(1-3)葡聚糖作了提取试验,并对所获多糖进行生化特性分析,阐述了碱溶液浸提法是从啤酒酵母中回收高质量β-(1-3)葡聚糖的理想途径. 相似文献