致密多孔介质中气体渗流的格子Boltzmann模拟

为了能用格子Boltzmann方法来正确地刻画致密多孔介质中微尺度流动问题,对单通道模型进行推广,并将其应用于孔隙群里气体渗流的数值模拟.通过对部分具有代表性的多孔介质中的实际流动问题进行模拟,研究渗透率与平均压力和Knudsen数之间的相互关系.基于理论分析及相关文献中的试验结果,验证模拟结果,为用格子Boltzmann方法深入研究气体渗流问题奠定基础.     

Organic glasses: cluster structure of the random energy landscape

An appropriate model for the random energy landscape in organic glasses is a spatially correlated Gaussian field. We calculated the distribution of the average value of a Gaussian random field in a finite domain. The results of the calculation demonstrate a strong dependence of the width of the distribution on the spatial correlations of the field. Comparison with the simulation results for the distribution of the size of the cluster indicates that the distribution of an average field could serve as a useful tool for the estimation of the asymptotic behavior of the distribution of the size of the clusters for “deep” clusters where value of the field on each site is much greater than the rms disorder. We also demonstrate significant modification of the properties of energetic disorder in organic glasses at the vicinity of the electrode.     

The influence of the electromagnetic radiation of low intensity on toxicity of an aqueous medium

The toxicity of solutions of phenol in combination with cadmium and cobalt for a culture of micro-seaweed and the opportunity of decreasing their toxicity by the influence of electromagnetic radiation in the range of the highest frequencies (UHF irradiation) are studied. The synergism between phenol and metals and a decrease in their toxicity under the influence of electromagnetic radiation are revealed.     

Der Einfluß des Atmosphärendruckes bei energiedispersiven Röntgenfluoreszenzanalysen leichter Elemente

Energiedispersive Röntgenspektrometer besitzen gegenüber wellenlängendispersiven Systemen den Vorteil einer wesentlich höheren Effektivität. Deshalb finden bei der energiedispersiven Röntgenfluoreszenzanalyse oft auch Nuklidquellen zur Anregung Verwendung. Die gebräuchlichsten Quellen dieser Art bestehen je nach Primäraktivität und Nuklid aus Scheiben mit einem Durchmesser zwischen 5 und 20 mm und einer Dicke von 5–10 mm. Damit wird von der Anregungsseite her ein einfacher Aufbau des Analysengerätes ermöglicht. Die Leistungsfähigkeit eines solchen Gerätes ist in vielen Fällen ausreichend, Spuren-elemente analytisch zu bestimmen. Deshalb ist auch die Notwendigkeit einer evakuierbaren Meßkammer oft noch umstritten. Besonders bei der Analyse leichter Elemente (mit Ordnungszahlen Z ? 20) macht sich jedoch die umgebende Atmosphäre störend bemerkbar. Dieser Einfluß ist am Beispiel des Schwefelnachweises (Z = 16) näher untersucht worden.     

Linear and non-linear stability limits for centrifugal convection in an anisotropic layer

This paper finds stability limits for the onset of convection in a fluid saturated porous layer subject to alternating directions of centrifugal acceleration. The layer is homogeneous but mechanically and thermally anisotropic. The Brinkman equation is assumed to govern the momentum balance of the fluid flow. A linear analysis based on normal mode approach and a non-linear analysis based on energy method are made. The non-linear results are unconditional and their sharp limits are obtained. The numerical solutions predicted using the compound matrix method show that the anisotropy parameters and offset distances of the axis of rotation significantly affect the stability characteristics.     

A modified SIS model with an infective medium on complex networks and its global stability

In this paper, we propose a modified susceptible-infected-susceptible model with an infective medium, which describes epidemics transmitted through an infective medium on complex networks. We examine epidemic thresholds for disease spreading by using this new model and compare it with the standard SIS model and another SIS model having an infective medium. We also study and compare the effects of the uniform immunization scheme on different models. We finally give some necessary and sufficient conditions for the global stability of the new model.     

Magnetic symmetry based definition of the chirality in the magnetically ordered media

Different definitions of the chirality have been considered for their applications to the micromagnetic structures. It was suggested to use magnetic symmetry based Barron chirality definition. The Barron chirality was obtained for all magnetic domain walls as the example. The symmetry based classification of the domain walls has been used for the chirality determination.     

导电介质表面边界问题的处理

介绍笔者在"电磁场与微波技术"的教学中,对导电介质表面边界问题的处理方法,可弥补教材不足,引导学生深入思考,提高学习能力.     

Encapsulation of the interstellar abundant H3+ in a C60 fullerene

The possible encapsulation of the interstellar abundant H₃⁺ ion inside a C₆₀ fullerene cage has been examined by using the Hartree‐Fock (HF) and the second order Møller‐Plesset perturbation (MP2) methods both with the 6‐31G** basis set. It was found that H₃⁺ forms various stable endohedral complexes inside the cage. Six configurations have been examined among which four were stable compared with the separated initial species, the dissociated H₂ + H⁺ inside the cage being the most stable. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

A systematic approach to assess amino acid conversions in SILAC experiments

SILAC is a widely accepted approach for quantitative proteomics in which proteins are labeled with stable isotopes during cell culture. A major drawback of this technique is the metabolic conversion of labeled amino acids that may hamper accurate quantification. A paradigmatic example of this phenomenon is the generation of labeled proline from arginine, known to occur in a good number of biological models. We propose a novel methodology to identify and quantitate metabolic conversions as well as to evaluate labeling efficiency in SILAC experiments. In this approach, labeled proteins are reduced to amino acids by acid hydrolysis before LC-MS/MS analysis. Since it is carried out at the amino acid level, tracking the fate of the isotope label is straightforward and can be performed for each amino acid independently. After applying this method to mammalian cells, grown in the presence of heavy arginine and lysine, labeling efficiency and amino acid conversions could be accurately evaluated. Only undesirable labeling of proline was found to occur at a significant extent, varying greatly among cell lines. Finally, increasing proline concentration in the growing medium was shown to be effective at preventing arginine conversion without any noticeable side effect.