Cun、Agn和Aun(n≤9)团簇的静电极化率

采用B3LYP密度泛函的方法计算了Cun，Agn和Aun(n≤9)团簇的静电极化率和极化率的各向异性，并与Na原子团簇进行比较，结果表明，Cun和Agn团簇的极化率与团簇大小的关系与Na原子团簇类似，而Aun团簇的极化率有所不同；Au原子的极化率较小，而从Au2至Au7，Aun团簇极化率变化趋势与Cun和Agn团簇相似。重金属元素团簇的极化率小于Na原子团簇的极化率，具有更加紧致结构。     

R2Fe14B型永磁材料中第二磁晶各向异性常数对反磁化过程的影响

针对低温下各向同性Pr₂Fe₁₄B永磁材料的最小形核场问题，用数值 计算法和近似解 析解研究了第二磁晶各向异性常数K₂对最小形核场的影响.研究发现，尽管对于 Nd₂ Fe₁₄B永磁材料一级近似的解析解与数值计算结果很接近，但是对于低温下各向 同性P r₂Fe₁₄B永磁材料则至少要用二级近似下的解析解才能与数值计算 结果相接近.用有 关最小形核场的计算结果很好地解释了低温时各向同性Pr₂Fe₁₄B永 磁材料的矫顽力与最小形核场的关系. 关键词： 第二磁晶各向异性常数 形核场 矫顽力     

Fluorescence anisotropy and light-scattering studies of the interaction of insulin with liposomes

The interaction between zinc-stabilized insulin and lecithin liposomal membranes was studied using DPH fluorescence anisotropy and light-scattering techniques. To ascertain a possible influence of a charge on the insulin molecule, experiments were performed at pH 4.5 (insulin possesses a positive charge) and at pH 7.4 (the charge of insulin is negative). Measurements at pH 4.5 revealed significant changes in scattered light intensity induced by the addition of insulin to lecithin liposomes. With increasing time of storage of liposomes the insulin effect became faster and more pronounced. At pH 7.4, significant changes in scattered light were registered only in the case of liposomes stored for 5 days. In these liposomes a peroxidation process of lecithin was revealed. No significant changes induced by insulin were observed in DPH fluorescence anisotropy either at pH 4.5 or at pH 7.4, which suggested the absence of an interaction of insulin with the hycrophobic core of liposomes. Thus, the observed changes in scattered light could be interpreted in terms of the insulin association to the liposomal surface in the case of phospholipid peroxidation and/or acidic pH.     

Accuracy assessment to applying 20-node solid elements to pressurized composite shells

A factorial analysis is conducted to explore the impact of five factors — aspect ratio, radius-to-thickness ratio, material anisotropy, fiber angle and integration order on the finite element accuracy, with regard to the application of 20-node isoparametric solid elements to clamped composite cylindrical shells subjected to internal pressure. The maximum radial displacement at the central cross-section is employed as the indicator of accuracy. Results from finite element methods were compared with closed-form solutions. Aspect ratio, radius-to- thickness ratio, and integration order are significant main effects as predicted for isotropic materials. Material anisotropy shows no significant main effect, while the fiber angle does have strong impact on the finite element accuracy. In addition to four influential main effects, some multiple-factor interactions are shown to have significant influences on the finite element accuracy. The analysis is limited to the linear elastic range.     

Review of fluorescence anisotropy decay analysis by frequency-domain fluorescence spectroscopy

This didactic paper summarizes the mathematical expressions needed for analysis of fluorescence anisotropy decays from polarized frequency-domain fluorescence data. The observed values are the phase angle difference between the polarized components of the emission and the modulated anisotropy, which is the ratio of the polarized and amplitude-modulated components of the emission. This procedure requires a separate measurement of the intensity decay of the total emission. The expressions are suitable for any number of exponential components in both the intensity decay and the anisotropy decay. The formalism is generalized for global analysis of anisotropy decays measured at different excitation wavelengths and for different intensity decay times as the result of quenching. Additionally, we describe the expressions required for associated anisotropy decays, that is, anisotropy decays where each correlation time is associated with a decay time present in the anisotropy decay. And finally, we present expressions appropriate for distributions of correlation times. This article should serve as a reference for researchers using frequency-domain fluorometry.     

井周介质各向异性参数反演方法与应用

采用Alford矩阵旋转方法和线性变换方法对交叉偶极阵列声波测井仪器录取的资料进行井周介质各向异性方向和大小的反演进行研究. 通过对计算机合成数据的处理, 检验了方法的正确有效性， 比较了两种方法的特点. 将反演程序用于现场实际数据处理， 得到了满意的反演结果.     

MgF2单晶中位错缺陷的ESR谱——含有130多条谱线

在室温条件下的激光晶体MgF2单晶中，实验发现含有130多条峰的电子自旋共振(ESR)波谱。两个样品分别取自MgF2单晶生长放肩的尖锥部位和MgF2:Co晶体.两个样品都没有经过任何辐照处理。两个样品具有相同的各向异性谱，说明掺入的Co2+离子引发了与MgF2单晶放肩部位相同的位错缺陷，产生了相同的多核固体自由基。这些顺磁固体自由基稳定且寿命长，产生的ESR信号是各向异性的。经初步计算拟合，谱线是由三种不同的多核自由基产生的。当磁场方向与晶体的[100]或[010]方向平行时，样品的ESR信号出现在磁场从0.2292特斯拉（T）到0.4654T的0.2362T范围内（相当于能带宽度为0.233eV）。最窄的线宽DH约为0.00128特斯拉，DH相当于相邻的能级差,是非常小的，仅有1.85×10-7eV 或1.46×10-3cm-1。这一事实表明其基态简并度是相当高的，在不太高的直流磁场下几乎是一个由准连续的能级组成的能带。这有可能成为可调谐的固体激光介质的新基点。     

Representation of the Functions of the Relative Phase Permeabilities for Anisotropic Porous Media

The most general representation of the functions of the relative phase permeabilities for porous media is written explicitly. The relations proposed for the relative phase permeabilities generalize those obtained earlier for media with transversely-isotropic and orthotropic percolation properties [1, 2] which can now be obtained as a particular case. A laboratory measurement technique for finding the percolation properties and determining the absolute and phase permeabilities for media with different types of anisotropy is discussed.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, 2005, pp. 118–125.Original Russian Text Copyright © 2005 by Dmitriev, Dmitriev, and Maksimov.