Linear and sub-linear growth and the CLT for hitting times of a random walk in random environment on a strip

The main goal of this work is to study the asymptotic behaviour of hitting times of a random walk (RW) in a quenched random environment (RE) on a strip. We introduce enlarged random environments in which the traditional hitting time can be presented as a sum of independent random variables whose distribution functions form a stationary random sequence. This allows us to obtain conditions (stated in terms of properties of random environments) for a linear growth of hitting times of relevant random walks. In some important cases (e.g. independent random environments) these conditions are also necessary for this type of behaviour. We also prove the quenched Central Limit Theorem (CLT) for hitting times in the general ergodic setting. A particular feature of these (ballistic) laws in random environment is that, whenever they hold under standard normalization, the convergence is a convergence with a speed. The latter is due to certain properties of moments of hitting times which are also studied in this paper. The asymptotic properties of the position of the walk are stated but are not proved in this work since this has been done in Goldhseid (Probab. Theory Relat. Fields 139(1):41–64, 2007).      

基于免疫原理的蚁群系统及其应用

针对蚁群算法在寻优过程中容易出现停滞现象,同意在该算法中引入免疫机制,将待求解问题看成抗原,而问题的解看成抗体,通过基于浓度的选择机制和多样性保持策略来提高蚁群算法的全局搜索能力和避免停滞现象.对TSP问题的仿真实验结果表明,该算法极大地提高了搜索能力和避免了停滞现象.     

Immobilization of the restriction endonuclease PstI

PstI has been immobilized in agarose. A solution of low melting agarose containing 1,6-hexamethylenediamine and PstI formed a gel that was effective in the linearization of pBR322 DNA. The gel containing PstI could be treated with 1,5-bis(N-acetylamino-N-succinimidoxy carbonyl)pentane, a crosslinking agent, without affecting the enzyme activity. Polymerization of acrylamide in presence of PstI led to conisderably reduced enzyme activity, although EcoRI under identical conditions showed high activity. It was found that acetylation of amino groups in PstI, by reaction with hydroxysuccinimide acetate, led to total inactivation of the enzyme activity. This reaction showed the presence of reactive amino groups that were essential for the enzyme activity of PstI. Involvement of these amino groups in binding to activated Sepharose 4B, during covalent immobilization, was responsible for inactive enzyme preparations.     

关于四元数体上自共轭矩阵的行列式和迹的几个定理

本文采用分析和代数的方法得到了四元数体上自共轭矩阵的行列式和迹的几个定理，推广和改进了文［３］，文［５］相类定理的结果。     

反相液相色谱的双柱规律

本文在液相色谱保留值方程ln κ′=A B·C_B C·InC_B的基础上,在很宽的浓度范围内考察了反相液相色谱的双柱规律,根据这个方法,在一个柱上只要做一次先行实验,就可在较宽的浓度范围内把一个柱上的k’转移到另一柱上去。     

Matrix-free infrared soft laser desorption/ionization

Infrared soft laser desorption/ionization was performed using a 2.94 µm Er : YAG laser and a commercial reflectron time-of-flight mass spectrometer. The instrument was modified so that a 337 nm nitrogen laser could be used concurrently with the IR laser to interrogate samples. Matrix-assisted laser desorption/ionization (MALDI), laser desorption/ionization and desorption/ionization on silicon with UV and IR lasers were compared. Various target materials were tested for IR soft desorption ionization, including stainless steel, aluminum, copper, silicon, porous silicon and polyethylene. Silicon surfaces gave the best performance in terms of signal level and low-mass interference. The internal energy resultant of the desorption/ionization was assessed using the easily fragmented vitamin B₁₂ molecule. IR ionization produced more analyte fragmentation than UV-MALDI analysis. Fragmentation from matrix-free IR desorption from silicon was comparable to that from IR-MALDI. The results are interpreted as soft laser desorption and ionization resulting from the absorption of the IR laser energy by the analyte and associated solvent molecules. Copyright © 2004 John Wiley & Sons, Ltd.     

Analysis of the intramolecular proximity effect on dichloroalkane + alkane mixtures using Nitta-Chao model

Literature data for vapor liquid equilibria, activity coefficients at infinite dilution, enthalpies of mixing, volumes of mixing of ,ω-dichloroalkane (ClCH₂---(CH₂)_m−2---CH₂Cl, from M=1 to 6) + − alkane mixtures together with vaporization enthalpies and molar volumes of pure dichloroalkanes were examined on the basis of the Nitta-Chao model. In this paper structure-dependent interaction energetic coefficients for this model were presented for a first time. According to the proximity effect when the two chloro groups of the chloroalkane are more separated they become independent and the reported values of the energetic parameters approach to these of the 1-chloroalkane. Similar trends were reported previously for several authors in the framework of the DISQUAC model. A comparison with the predictions of DISQUAC and UNIFAC (version of Larsen et al.) is presented.     

Optical bistability via tunable Fano-type interference in asymmetric semiconductor quantum wells

We analyze hybrid absorptive-dispersive optical bistability (OB) behavior via tunable Fano-type interference based on intersubband transitions in asymmetric double quantum wells (QWs) driven coherently by a probe laser field by means of a unidirectional ring cavity. We show that OB can be controlled efficiently by tuning the energy splitting of the two excited states (the coupling strength of the tunnelling), the Fano-type interference, and the frequency detuning. The influence of the electronic cooperation parameter on the OB behavior is also discussed. This investigation may be used for optimizing and controlling the optical switching process in the QW solid-state system, which is much more practical than that in atomic system because of its flexible design and the controllable interference strength.     

Direct chemical assembly of quaternary ammonium groups on a surface of highly dispersed silica

Direct assembly of quaternary ammonium groups onto a silica surface has been realized by use of many-stage chemical reactions. Adsorption of cholic acid in dependence on duration, equilibrium concentration, and pH solution onto a surface of silicas modified with quaternary ammonium groups has been studied. The main parameters of cholic acid adsorption have been calculated.