利用SELEX技术筛选小檗碱核酸适配体及其亲和力表征

小檗碱是一种价格低廉且生物安全性良好的小分子化合物,筛选能与小檗碱互相作用的核酸片段,旨在开发新型遗传元件并拓展其在生物技术领域的应用。利用指数富集的配基系统进化技术（SELEX）,经8轮实验从随机单链DNA文库中筛选出4条能与小檗碱高度特异性结合的核酸适配体。对其中两条重现性较好的适配体进行结构模拟分析表明,适配体序列富含鸟嘌呤和胞嘧啶且多形成茎环及G-四链体结构。亲和力测定结果显示,其中的2条核酸适配体与小檗碱作用的解离常数K_d都处于nmol级,表现出较高的亲和力,适配体S1的K_d值最小,仅为523 nmol/L,与小檗碱亲和力最大。     

RSA加密算法改进的研究及实现

RSA算法的安全性依赖于模幂和模乘运算,但是由于模幂运算太耗时间,一直使得RSA算法难以广泛应用,因此如何提高RSA运算中的模幂、模乘运算速度至关重要.对RSA加解密基本原理进行了相应的分析,并结合当前针对RSA算法的攻击手段,提出抵御这些攻击所应考虑的因素,从而对传统的RSA算法进行了进一步的改进.     

顶吹搅拌液相流体的水模实验与数值模拟分析

采用水模型和VOF数学模型对浸没式气体顶吹搅拌液相流体分别进行实验与数值模拟,分析在不同喷吹条件下气泡在液相中的形变、运动及液相流体的流场特性。结果表明,随着气流量和喷管浸入液面深度的增加,气-液混合区域分布范围逐渐扩大,液面波动更剧烈;气流量越大、喷管浸入液面越深、液相温度越高,气泡运动对液相流体内部的搅拌作用越强,流体内部扰动越剧烈,液相流场域中的流场速度越大,其中,当气流量为2.0m3/h、喷管浸入液面深度为340mm时,其液相流场速度最大值达到1.18m/s。     

The inverse phase sequence SmA-SmC in symmetric dimeric liquid crystals

Seven homologous symmetric dimeric liquid crystals are presented where two three-ring mesogenic units are connected by a bis(carbonyloxy)alkylene spacer. For homologues with terminal heptyloxy, octyloxy and nonyloxy chains, the unusual phase sequence SmA-SmC with increasing temperature was detected by the study of the optical textures and by X-ray diffraction measurements. This unusual behaviour is discussed on the basis of the molecular structure of these compounds.     

Ultra‐high pressure LC for astaxanthin determination in shrimp by‐products and active food packaging

Nowadays, there is increasing interest in natural antioxidants from food by‐products. Astaxanthin is a potent antioxidant and one of the major carotenoids in crustaceans and salmonids. An ultra‐high pressure liquid chromatographic method was developed and validated for the determination of astaxanthin in shrimp by‐products, and its migration from new packaging materials to food simulants was also studied. The method uses an UPLC® BEH guard‐column (2.1 × 5 mm, 1.7 µm particle size) and an UPLC® BEH analytical column (2.1 × 50 mm, 1.7 µm particle size). Chromatographic separation was achieved using a programmed gradient mobile phase consisting of (A) acetonitrile–methanol (containing 0.05 m ammonium acetate)–dichloromethane (75:20:5, v/v/v) and (B) ultrapure water. This method was evaluated with respect to validation parameters such as linearity, precision, limit of detection, limit of quantification and recovery. Low‐density polyethylene films were prepared with different amounts of the lipid fraction of fermented shrimp waste by extrusion, and migration was evaluated into food simulants (isooctane and ethanol 95%, v/v). Migration was not detected under the tested conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

High pressure treatment of pharmaceutical drug delivery and related systems

Abstract

Solids like layer silicates (kaolinite and montmorillonite) as well as ZnO are in use in pharmacy. They are pressure treated and subsequently analyzed by means of ESR spectroscopy. The structural changes indicated by Fe³⁺ ions and paramagnetic defects are reponsible for the enhanced chemical activity of the pressurized systems.

Especially active Fe-O-species are formed which can react with intercacalated organic molecules. The most probable first step of such reactions will be a solid state single electron transfer. Spin probes and spin traps were used to prove this statements. The activation of the drug delivery systems by mechanical treatments is of importance for the stability of the drugs incorporated.     

中国劳动力市场收入户籍歧视的无条件分位数分解

使用无条件分位数分解方法对2007年中国劳动力市场的收入户籍歧视程度进行了考察.实证分析的结果显示:从整体上看,2007年户籍歧视可以解释农民工和城镇职工平均收入差距的近三分之一,且歧视效应随收入分位提高而增加;从分项贡献来看,各自变量对收入差异的影响随收入分位变动明显.根据实证分析得出的政策建议为:当政策目标为缩小高收入分位的群体收入差异时,消除户籍歧视的政策效果更好;而当政策目标为缩小低收入分位的群体收入差异时,缩小两群体禀赋差异的政策效果更好.     

Wound Healing Attributes of Polyelectrolyte Multilayers Prepared with Multi‐l‐arginyl‐poly‐l‐aspartate Pairing with Hyaluronic Acid and γ‐Polyglutamic Acid

Biodegradable multi‐l ‐arginyl‐poly‐l ‐aspartate (MAPA), more commonly cyanophycin, prepared with recombinant Escherichia coli contains a polyaspartate backbone with lysine and arginine as side chains. Two assemblies of polyelectrolyte multilayers (PEMs) are fabricated at three different concentration ratios of insoluble MAPA (iMAPA) with hyaluronic acid (iMAPA/HA) and with γ‐polyglutamic acid (iMAPA/γ‐PGA), respectively, utilizing a layer‐by‐layer approach. Both films with iMAPA and its counterpart, HA or γ‐PGA, as the terminal layer are prepared to assess the effect on film roughness, cell growth, and cell migration. iMAPA incorporation is higher for a higher concentration of the anionic polymer due to better charge interaction. The iMAPA/HA films when compared to iMAPA/γ‐PGA multilayers show least roughness. The growth rates of L929 fibroblast cells on the PEMs are similar to those on glass substrate, with no supplementary effect of the terminal layer. However, the migration rates of L929 cells increase for all PEMs. γ‐PGA incorporated films impart 50% enhancement to the cell migration after 12 h of culture as compared to the untreated glass, and the smooth films containing HA display a maximum 82% improvement. The results present the use of iMAPA to construct a new layer‐by‐layer system of polyelectrolyte biopolymers with a potential application in wound dressing.