Translocation of Biopolymer Chain Through a Nanopore: Coil--Helix Transition

The translocation dynamics of a single biopolymer chain through a nanopore in a membrane is investigated by taking the coil-helix transition into account. Based on the changing of the free energy due to the coil-helix transition, the mean first passage time T is obtained, and then the corresponding numerical simulations are presented under different conditions. It is shown that the coil--helix transition can significantly shorten the translocation time of the biopolymer chain. In addition, we also discuss the scaling behaviour for T with the chain length N and some related problems.     

Calculation of magnetic multipole moment integrals using translation formulas for Slater-type orbitals

Using translation formulas for Slater type orbitals (STO’s) the infinite series through the overlap integrals are derived for the magnetic multipole moment integrals. By the use of the derived expressions the magnetic multipole moment integrals, therefore, the magnetic properties of molecules can be evaluated most efficiently and accurately. The convergence of the series is tested by calculating concrete cases. An accuracy of 10⁻⁵ for the computer results is obtained in the case 2 ^p -pole magnetic moment integrals for 1 ≤ v ≤ 5, and for the arbitrary values of internuclear distances and screening constants of atomic orbitals.     

一种基于感兴趣区域提取的医学图像检索技术

针对胸部CT扫描图像库,提出了一种基于感兴趣区域提取的图像检索方法．首先为了提取感兴趣区域,提出一种基于灰度层共现矩阵的区域增长算法,分割出病灶区域,再通过闽值算法进行边界的磨合,然后针对感兴趣区域提取形状和分布特性作为图像匹配准则的客观依据．最后,将该算法与其他底层特征算法进行比较和分析．实验结果表明,该算法能够比较有效地应用于基于内容的医学图像检索系统中．     

ICP-AES法测定蒙药紫癜灵中多种微量元素

蒙药含有多种氨基酸和丰富的微量元素,特别是人体必需的微量元素含量相对较高,而对人体有害的重金属元素含量相对较低。采用微波消解ICP-AES法同时测定了治疗过敏性紫癜的蒙药紫癜灵中Ca, Mg, Sr, Fe, Mn, Zn, Cu和Pb等15种微量元素。紫癜灵的临床药效实验,选择了过敏性紫癜患者260例,其中男性140例,女性120例;年龄最小6岁,最大62岁,6～16岁年龄段最多,占病人总数的90%左右。治疗结果显示：治愈234例,占90%;显效13例,占5%;有效11例,占4.23%;无效2例,占0.77%;总有效率达99.23%。紫癜灵中含有丰富的微量元素,尤其锶的含量相当高。方法的加标回收率在94.63%～106.40% 之间,相对标准偏差RSD≤3.17%,检出限≤0.009 μg·L-1。     

微视频在无机化学实验教学中的应用

To improve the students' autonomous learning ability and learning enthusiasm in practice course,we introduce micro video,which is short,fast,precise,easy,and fun,into inorganic chemistry laboratory teaching.As an important supplementary means of teaching,micro videos will solve the repeated problems,help students promote study efficiency,provide students with a good way for communication,and improve the students' study enthusiasm.     

Chaos in an Ar+ Composite Resonator Laser Using KNSBN;Cu Crystal Self-Pumped Phase-Conjugator

Observation of the dynamics in a single-mode Ar⁺ composite resonator laser using KNSBN;Cu crystal self-pumped phase-conjugator is reported. The sequence of instabilities occurring on gain change corresponds to the transition the chaos of the logistic equation. Period-doubling route to chaos, and period-5, -3,-3×2, and -2 together with -3 windows in the chaotic range were observed. The strange attractor which is similar to that of the forced Duffing equation is obtained by reconstructing phase-space pictures of the system.     

横向磁场导致CO2激光器混沌运转及其奇异吸引子的观测

在外加磁场的情况下,对单模均匀展宽CO₂激光器进行了实验研究。改变磁场的大小,观察到了自脉动和混沌现象,同时还获得了该系统的奇异吸引子,并对其物理机制进行了探讨。     

2-cyano Δ3 piperidines III: Total synthesis 0f (±) 20-epiuleine

The total synthesis of the indole alkaloid (±) 20-epiuleine has been achieved starting from indole itself and the appropriate 2-cyano Δ³ piperidine $\text{7}$.     

SYNTHESIS AND NMR CHARACTERIZATION OF PRECURSORS OF EPOXY NETWORK AS POLYMER HOST FOR SOLID ELECTROLYTE

To raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a noncrystalline two-component epoxy electrolyte system has been prepared. The diglycidyl ether of polyethylene glycols as precursors of the system were synthesized by a two-step process. The presumed structure of the product was characterized, by ~(13)C, ~1H NMR and IR spectroscopy. It was found that a side-reaction occurred between the secondary hydroxyl group of PEG-chlorohydrin and epichlorohydrin in some degree, resulting in a by- product containing—CH_2Cl side group. By selecting a characteristic signal, which is undistorted by the increase in the length of CH_2 CH_2—O segment, a ~1H NMR approach of determining the equivalent epoxy weight (EEW) was proposed. The method is valid to specimens even though the EEW is as high as 2,000. The examination of the specimens by DSC showed that epoxidation greatly depressed the crystallinity of the PEG's, whereas the T_g was raised.     

Tosylation/mesylation of 4-hydroxy-3-nitro-2-pyridinones as an activation step in the construction of dihydropyrido[3,4-b] benzo[f][1,4]thiazepin-1-one based anti-HIV agents

Reaction of 4-hydroxy-3-nitropyridinone 8 with TsCl and MsCl, respectively, resulted in rapid and quantitative formation of ditosylate 13 and dimesylate 16. Through chemoselective reaction of 16 with thiophenol 17 the key 4-thioaryl substituted intermediate 18 was obtained in 78% yield. This compound was efficiently converted to the target tricyclic products 4a and b. Compound 4a, in particular, is a potent inhibitor in vitro (IC₅₀ = 2 nM) of wild type HIV-1 replication.