Carcinogenesis of asbestos switched on by inducing cross-linkage between DNA complementary pair bases

Since the beginning of the 1980s, Dai Qianhuan predicted based upon his di-region theory that the carcinogenesis switched on by the so-called physical carcinogenic factors including radiation, asbestos and foreign matter implantation, is just initiated through the cross-linking between DNA complementary pair bases induced by them. In this note, it was evidenced with the DNA filter elution method that the oxygenase activated by asbestos induces the cross-linking between DNA inter-strands and DNA-protein with dosage correlation, in which over 80% of DNA inter-strand cross-link ratio account for the total cross-link ratio. Obviously, both of the cross-linkages are just induced by hydroxyl free radical, HO ·, because the ferrous ion increased the cross-link ratios up to several times through Fenton reaction and vitamin C inhibited the cross-link ratios with factors of 8–9 by destroying the hydroxyl radical. Non-carcinogen but with lower free radical formation energy, pyrene, by culturing with asbestos gave 3–4 times cross-link ratios than the original ratios induced by asbestos only. Estradiol, an endogenous carcinogen, as a bio-electrophilic species but with higher free radical formation energy by culturing with asbestos, gave only 1.2 time cross-link ratios than expected ones. Ferrous ion which can increase HO · concentration through Fenton reaction, increased the ratios to 2–2.5 times in the former case but only 1.2 time in the latter case. Vitamin C, a free radical scavenger, gave a powerful inhibition to the cross-linking with a factor of 8–11 in the former case but a weak inhibition with a factor of 1.2 only in the latter case. So, it is evidenced further that the cross-linkages induced by asbestos are originated from hydroxyl radical. Reasonable structures of the cross-linking products induced by asbestos or hydroxyl radical have been depicted based upon AMI MO theory. These structures have been verified further by a reasonable explanation of the mutational spectrum induced by hydroxyl radical.     

Interaction of hepatitis B virus with tumor suppressor gene p53: its significance and biological function

The mechanism of the interaction of hepatitis B virus (HBV) with tumor suppressor p53 and its role in the hepatocar-cinogenesis have been studied by PCR-directed sequencing, gel shift assays and in situ ultraviolet cross-linking assay. The biological function of the interaction of HBV with p53 gene was investigated by co-transfection of chloramphenicol acetyltransferase ( CAT) reporter gene. p53 and HBV DNA. and quantitative PCR. Among the 16 primary hepatocellular carcinoma (PHC) samples. 13 were HBV-DNA positive. 10 HBxAg positive and 9 p53 protein positive. The p53 gene point mutation was found in 5 samples, one of which had a G to T substitution located at codon 249. After analyzing the HBV genome by a computer program, a p53 response element binding sequence was found in HBV genome at upstream of enhancer I. from 1047 to 1059 nucleotides. This sequence could specifically bind to p53 protein, increase p53 protein accumulation in the PHC cells and stimulate the transactivating activity of p53 and HBV replication . The results also revealed that HBxAg could combine with p53 protein to form a complex in the cells and enhance CAT expression. Immunocytochemical staining showed that p53 protein complex was located in the cytoplasm and the process of p53 entry to nuclei was. in part, blocked. From our results, we conclude that the mutation of p53 gene at codon 249 is infrequent in HBV-associated PHC. the DNA-protein binding between HBV and p53. and the protein-protein binding between HBxAg and p53 might lead to the reduction or inactivation of p53 protein, which in turn resulting in HBV-associated hepatocarcinogenesis.     

框架结构优化设计

介绍了用正多面体方法对框架结构进行优化设计，从而节省材料，使框架结构设计达到更经济的目的。     

一碳掺杂硼氮纳米管的电子结构和电学性质

用密度泛函理论的DFF／ROB3LYP方法计算了几种一碳掺杂(碳取代一个硼原子或氮原子)的硼氮纳米管的电子结构，研究了其导电性，得到了这种碳掺杂硼氮纳米管的能带结构和态密度曲线，并与纯硼氮纳米管作了比较，讨论了碳掺杂对硼氮纳米管导电性的影响．     

二氢叶酸还原酶抑制剂定量构效关系(QSAR)研究

对2，4-二氨基-5-甲基-6-(取代苯胺基)甲基吡啶[2，3-d]并嘧啶类二氢叶酸还原酶抑制剂进行了定量构效关系的量子化学研究，证明了偶极矩，LUMO能级和HOMO-LUMO能隙对其活性有着重要的影响．     

着舰导引中的H∞飞行/推力控制系统研究

运用基于线性矩阵不等式的H∞控制理论，提出了保持由地速构成的迎角αd恒定的H∞飞行／推力综合控制增广模型，使飞机接近舰尾处于雷达导引系统关闭的关键时刻，仍具有优良的姿态保持及抑制气流扰动性能，改变了传统设计由导引系统纠正气流扰动而引起的轨迹偏离；还从工程应用角度出发，提出了H∞控制器的降阶方法，并进行了实时仿真验证。     

La2O3/Y沸石上La2O3与Y型沸石载体的相互作用

用X射线衍射法(XRD)和骨架红外光谱法(IR)研究了La2O3／Y沸石上La2O3与Y型沸石的相互作用．结果表明：La2O3在Y型沸石上自发分散，且分散阈值较高；La2O3的引入对载体的结构具有破坏作用，且随负载量的增大骨架破坏得越厉害；La2O3负载过程中有部分La进入骨架内部．     

新烟碱型乙酰胆碱受体吡啶基醚类配体的3维定量构效关系

采用比较分子力场分析方法，对一系列与烟碱型乙酰胆碱受体作用的吡啶基醚类配体进行构效关系分析，建立了这类化合物的3维构效模型．其交叉验证回归系数Rcv^2、非交叉验证回归系数Rncv^2和标准偏差s分别为0．744，0．973和0．256．结论说明该系列化合物的分子立体场和静电场的分布与生物活性之间有良好的相关性．该模型对训练集分子的活性预测结果较好，表明该力场模型有一定的预测能力，可用来指导设计新的烟碱型乙酰胆碱受体配体．     

Functionalization of graphene materials by heteroatom-doping for energy conversion and storage

Recent development in nanoscience and nanotechnology has opened up new frontiers in materials science and engineering to create new materials for energy generation and storage. Owing to their earth abundance, low-cost, structural tunability, large-surface area, and unique physicochemical properties, graphitic carbon materials have attracted a great deal of attention for energy-related applications. However, the pristine graphene materials without functionalization is intractable (insoluble and infusible), which has hindered their practical applications. Therefore, considerable research effort has been devoted to the development of functionalized graphene materials with desirable properties for specific applications, including energy conversion and storage. It was demonstrated that functionalized graphene materials with tunable work functions were useful as charge-extraction materials to effectively improve solar cell performance while those with high electrocatalytic activities could be used as metal-free catalysts in fuel cells, metal-air batteries, water splitting and integrated energy systems. This article provides a timely focused review on the development of heteroatom-doped graphene materials for low-cost, but efficient, energy generation and storage.     

基于隐息学的信息安全方案

为了保证中文信息传输过程的安全,构造了一种新的信息隐藏加密方案。该方案将传统的密码设计理论与新兴的隐息学理论相结合,使用较短的加密密钥与简单的加密和隐藏算法。利用信息论的方法证明了该方案是安全的。方案实现原理简单,同时由于采用简单的查表与替换,实现效率可以提高数倍。有助于有限计算能力的用户确保中文信息传输过程的安全保密。