Facial Synthesis and Bioevaluation of Well-Defined OEGylated Betulinic Acid-Cyclodextrin Conjugates for Inhibition of Influenza Infection

Betulinic acid (BA) and its derivatives exhibit a variety of biological activities, especially their anti-HIV-1 activity, but generally have only modest inhibitory potency against influenza virus. The entry of influenza virus into host cells can be competitively inhibited by multivalent derivatives targeting hemagglutinin. In this study, a series of hexa-, hepta- and octavalent BA derivatives based on α-, β- and γ-cyclodextrin scaffolds, respectively, with varying lengths of flexible oligo(ethylene glycol) linkers was designed and synthesized using a microwave-assisted copper-catalyzed 1,3-dipolar cycloaddition reaction. The generated BA-cyclodextrin conjugates were tested for their in vitro activity against influenza A/WSN/33 (H1N1) virus and cytotoxicity. Among the tested compounds, 58, 80 and 82 showed slight cytotoxicity to Madin-Darby canine kidney cells with viabilities ranging from 64 to 68% at a high concentration of 100 μM. Four conjugates 51 and 69–71 showed significant inhibitory effects on influenza infection with half maximal inhibitory concentration values of 5.20, 9.82, 7.48 and 7.59 μM, respectively. The structure-activity relationships of multivalent BA-cyclodextrin conjugates were discussed, highlighting that multivalent BA derivatives may be potential antiviral agents against influenza infection.     

Transport Properties of Magnetic Nanogranular Composites with Dispersed Ions in an Insulating Matrix

Journal of Experimental and Theoretical Physics - This review is devoted to an analysis of the electrical resistance, the magnetoresistance, and the anomalous Hall effect in magnetic...     

一类只有两个不同非零交换理想的无限维李代数

构造了一类无限维李代数,它是无中心的Virasoro李代数的推广,且只有两个不同的非零交换的理想.还研究了这类李代数的理想、中心和子代数.     

大连广电中心广播电视剧场声学设计

广播电视剧场是随着电视技术的发展和需要而产生的一种新的观演建筑的形式，它不同于一般的演播室，也有别于普通的剧场。它不仅要求能够进行电视节目的转播和录制，还要求能够进行音乐、歌舞等各种文艺节目的演出，并能够举行会议和放映立体声电影，因此，广播电视剧场对音质有很高的要求。本文介绍了大连广播电视中心广播电视剧场的建声设计，在该剧场内采用了计算机控制的可调混响装置，使得各种使用功能都能有一个较为理想的建声环境。     

Influence of acceptor doping on ionic conductivity in alkali earth titanate perovskites

The electrical conductivity of the SrTi_1−xFe_xO_3−δ, BaTi_1−xFe_xO_3−δ and SrTi_1−xMn_xO_3−δ systems has been studied in a range of oxygen partial pressures between 10⁻¹⁶ and 0.21 atm at 900 and 1000 °C. The materials exhibit predominantly ionic conductivity in a wide range of intermediate oxygen partial pressures. It has been found that in Fe doped strontium and barium titanates, the dependencies of the ionic conductivity on the acceptor concentration show a local maximum near x=0.2. Taking into account that in the CaTi_1−xFe_xO_3−δ system (x=0−0.5), the concentration dependence of the ionic conductivity also has a maximum near x=0.2, it can be concluded that this is a common phenomenon for Fe doped alkali earth titanates. An assumption has been made that a scheme of defect formation devised earlier for Fe doped calcium titanate is applicable for other alkali earth titanates.     

含离子类溶质黏土的 C-H-M 本构模型简

在水力-力学本构模型基础上,采用化学软化公式引入孔隙水中含盐、碱类等离子类溶质对土体前期固结压力的影响,得到土体的化学-水力-力学耦合本构模型（C-H-M 模型）. 根据试验结果对化学软化公式的参数进行数值拟合,通过算例验证了C-H-M 本构模型的有效性     

Vibrational Convection in the Hele-Shaw Cell. Theory and Experiment

The influence of high-frequency horizontal vibrations on convection in the Hele-Shaw cell located in a uniform gravity field is considered experimentally and theoretically. Nonlinear regimes of vibrational convection in the supercritical region are examined. It is shown that horizontal vibrations (directed toward the wide sides of the cell) decrease the threshold of quasi-equilibrium stability. Regions of existence of one- and two-vortex steady flows are found, and unsteady regular and random regimes of thermal vibrational convection are considered. New random regimes in the Hele-Shaw cell are found, which result from nonlinear interaction of the “lower” modes responsible for the formation of regular supercritical convective regimes. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 2, pp. 40–48, March–April, 2006.     

Experimental and theoretical investigation of transient convective regimes in a Hele-Shaw cell

Supercritical regimes of thermal convection in a Hele-Shaw cell heated from below are investigated experimentally and theoretically. A stability map of convective regimes is plotted. Novel stable and transient pulsatory convective flows are revealed. The numerical calculations performed for a cell with thermally insulated vertical faces are in agreement with the experimental data.     

西南某大型水电站拱肩槽边坡开挖的变形响应研究

对基于结构网格的Euler方程及N-S方程求解器和基于非结构网格的Euler方程求解 器,采用结构模态分析方法和柔度矩阵方法,对无人机大展弦比机翼在Ma=0.6, α=2?, 飞行高度20km的巡航状态下的静气动弹性特性进行了数值模 拟. 验证了两种求解器对静气动弹性模拟的准确性. 同时,对模态分析方法和柔度 矩阵方法进行了对比研究,发现柔度矩阵方法更适用于静气动弹性数值模拟. 另外, 对应用物面法向偏转方法替代网格变形技术模拟静气动弹性进行了研究,计算表明 物面法向偏转方法可以大大提高静气动弹性计算效 率和克服机翼结构变形过大时动网格技术无法处理的不足.     

Microfocus X-Ray Tubes with a Silicon Autoemission Nanocathode as an X-Ray Source

To develop nanostructures with extremely low spatial resolution (to 10 nm and below), a new concept of the use of arrays of microfocus X-ray tubes based on field emission silicon nanocathodes is proposed. A new λ-tunable microfocus source of X-ray radiation, based on a thinfilm transmission target with field emission nanocathode with tunable wavelength, is proposed. The possibility of decreasing the exposed area size to 20 nm and smaller by varying the tube blocking voltage is shown. The use of these X-ray sources opens a new way of developing maskless X-ray lithography.