Instantaneous normal mode analysis of orientational motions in liquid water: local structural effects

We have investigated the effects of local structures on the orientational motions in liquid water in terms of the instantaneous normal mode (INM) analysis. The local structures of a molecule in liquid water are characterized by two different kinds of index: the asphericity parameter of its Voronoi polyhedron and the numbers of the H bonds donated and accepted by the molecule. According to the two kinds of index, the molecules in the simulated water are classified into subensembles, for which the rotational contributions to the INM spectrum are calculated. Our results indicate that by increasing the asphericity, the rotational contribution has a shift toward the high-frequency end in the real spectrum and a decrease in the fraction of the imaginary modes. Furthermore, we find that this shift essentially relies on the number of the donated H bonds of a molecule, but has almost nothing to do with that of the accepted H bonds. The local structural effects resulting from the geometry of water molecule are also discussed.     

Synthesis,characterization, and bioactivities of copper complexes with N-substituted Di(picolyl)amines

Three new Cu(II) complexes with ethyl bis(2-pyridylmethyl)amino-2-propionate (Etdpa), or bis(2-pyridylmethyl)amino-2-propionate (Adpa), were synthesized and characterized by physico-chemical and spectroscopic methods. The X-ray crystal structure of [(Adpa)CuCl] shows that the copper(II) atom is coordinated by three N atoms, one oxygen atom from the ligand (Adpa) and one chloride anion, forming a trigonal bipyramidal geometry. The spectrophotometric and fluorescence titration data indicate that the interaction of square pyramidal [(Etdpa)CuCl₂] with ct-DNA is weak, but the trigonal bipyramidal complexes [(Adpa)Cu(H₂O)](ClO₄) and [(Adpa)CuCl] interact with ct-DNA with the mode of intercalation. The inhibition activities of the three new copper(II) complexes on the four cancer cells (Mcf-7, Eca-109, A549, and Hela) are in the order: [(Adpa)Cu(H₂O)](ClO₄) > [(Adpa)CuCl] > [(Etdpa)CuCl₂], which correlates with their DNA-binding properties. The results show that the substituents introduced on the secondary amino nitrogen atom of dpa have great contribution to the antitumor activities of these copper(II) complexes. It is also found that the coordination of copper(II) ions with AdpaH can decrease the toxicity of AdpaH. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

“Inverted” Deep Eutectic Solvents Based on Host‐Guest Interactions

Herein, the concept of “inverted” (the mode “molecules mainly interact with cations”) deep eutectic solvents (DESs) is proposed. A strategy to form inverted DESs by host‐guest interactions was developed, and thus numerous DESs could be designed and formed by a combination of host and guest molecules. These liquids are expected to be used as nonaqueous electrolytes in potassium‐ion batteries or other fields for further exploration.     

OPA柱前衍生反相高效液相色谱法测定氨基酸含量

建立了邻苯二甲醛（ＯＰＡ）手动柱前衍生反相高效液相色谱法测定样品中氨基酸含量的方法。以邻苯二甲醛（ＯＰＡ）／３－巯基丙酸（３－ＭＰＡ）为衍生试剂进行衍生,ＯＤＳ柱分离,３４０ｎｍ检测,在４０ｍｉｎ内１８种氨基酸全部得到基线分离。测定牛血清白蛋白（ＢＳＡ）的氨基酸组成和小鼠血清中的游离氨基酸,取得满意的结果。     

Characterizations of totally ordered sets by their various endomorphisms

We characterize totally ordered sets within the class of all ordered sets containing at least three-element chains using a simple relationship between their isotone transformations and the so called 2-, 3-, 4-endomorphisms which are introduced in the paper. Another characterization of totally ordered sets within the class of ordered sets of a locally finite height with at least four-element chains in terms of the regular semigroup theory is also given.     

A new chaotic circuit with multiple memristors and its application in image encryption

Nonlinear Dynamics - In this paper, a new seventh-order mixed memristive chaotic circuit was designed, and the new mathematical model of the system was established. The origin as the only...     

烟酰胺与DNA相互作用的电化学研究

利用示差脉冲伏安法研究了烟酰胺(NA)与小牛胸腺DNA在pH 8.0条件下相互作用的电化学行为.双链DNA(dsDNA)或单链DNA(ssDNA)的存在导致NA的峰电流明显降低且峰电位负移,表明NA与DNA发生相互作用,生成了复合物,且其作用模式主要是静电模式,但NA与dsDNA的相互作用强于与ssDNA的相互作用,可用于识别dsDNA和ssDNA.通过dsDNA加入前后峰电流的变化,计算得出NA与dsDNA结合常数β=4.946×10(11),结合位点数m=3.此外,NA的峰电流Ip与DNA质量浓度在1～14mg/L的范围内呈线性关系,线性回归方程为Ip(10-5A)=-0.03451cDNA(mg/L)+1.7408,相关系数R为0.9998.该法具有良好的回收率和选择性,可用于样品中DNA的测定.     

离子色谱-串联电喷雾质谱法检测自来水中二氯乙酸和三氯乙酸

建立了一种采用离子色谱-串联电喷雾四级杆质谱联用技术检测自来水中可致癌的饮用水消毒副产物二氯乙酸和三氯乙酸的方法。该方法使用IonPacPrototype-10高容量阴离子交换柱为分离柱,以ICS-3000多功能色谱系统的淋洗液自动发生装置在线产生不同浓度的KOH淋洗液,在合适的梯度条件下,实现对自来水样品中两种卤代乙酸和多种常见阴离子的高效分离,经抑制器将淋洗液抑制为近中性后,在不添加有机溶剂的情况下,进入API3200 ESI-MS/MS质谱系统,选取适合的离子对和温度、能量条件,进行准确定量分析。在优化的色谱和质谱条件下,二氯乙酸和三氯乙酸的检出限分别为0.053和0.46μg/L。峰面积校正曲线的线性范围均跨越两个数量级以上。对4种不同浓度的标准溶液和实际样品连续9次进样,峰面积的相对标准偏差小于7%。选取北京市18个区县及全国部分省市的自来水样品进行检测,所得结果令人满意。挑选其中的典型样品进行不同浓度的标准加入实验,回收率在86.7%-119.0%之间。     

A Comprehensive Computational Investigation into the Conserved Virulent Proteins of Shigella species Unveils Potential Small-Interfering RNA Candidates as a New Therapeutic Strategy against Shigellosis

Shigella species account for the second-leading cause of deaths due to diarrheal diseases among children of less than 5 years of age. The emergence of multi-drug-resistant Shigella isolates and the lack of availability of Shigella vaccines have led to the pertinence in the efforts made for the development of new therapeutic strategies against shigellosis. Consequently, designing small-interfering RNA (siRNA) candidates against such infectious agents represents a novel approach to propose new therapeutic candidates to curb the rampant rise of anti-microbial resistance in such pathogens. In this study, we analyzed 264 conserved sequences from 15 different conserved virulence genes of Shigella sp., through extensive rational validation using a plethora of first-generation and second-generation computational algorithms for siRNA designing. Fifty-eight siRNA candidates were obtained by using the first-generation algorithms, out of which only 38 siRNA candidates complied with the second-generation rules of siRNA designing. Further computational validation showed that 16 siRNA candidates were found to have a substantial functional efficiency, out of which 11 siRNA candidates were found to be non-immunogenic. Finally, three siRNA candidates exhibited a sterically feasible three-dimensional structure as exhibited by parameters of nucleic acid geometry such as: the probability of wrong sugar puckers, bad backbone confirmations, bad bonds, and bad angles being within the accepted threshold for stable tertiary structure. Although the findings of our study require further wet-lab validation and optimization for therapeutic use in the treatment of shigellosis, the computationally validated siRNA candidates are expected to suppress the expression of the virulence genes, namely: IpgD (siRNA 9) and OspB (siRNA 15 and siRNA 17) and thus act as a prospective tool in the RNA interference (RNAi) pathway. However, the findings of our study require further wet-lab validation and optimization for regular therapeutic use for treatment of shigellosis.     

锐钛矿相TiO2(101)表面对有机分子不同官能团微观吸附的机制

挥发性有机化合物(VOCs)严重危害了生态环境和人体健康,因此对具有典型官能团的VOCs气体进行灵敏检测具有重要意义.文章研究了具有典型官能团的VOCs气体C₂H₂、C₂H₄、HCOOH、CH₃OH、HCHO和CH₃COCH₃分子在锐钛矿相TiO₂(101)表面吸附的传感特性.结果表明：具有氧空位缺陷的表面对极性分子吸附时,偶极矩越大,吸附体系越稳定;对非极性分子吸附时,C原子成键饱和程度越低,吸附体系越稳定.分析发现,差分电荷密度和电荷布局体现出偶极矩大小和C原子成键饱和程度对气体分子得失电子能力的影响.对于极性分子,气体分子官能团中O原子得到电子的能力为OCH₃COCH₃>OHCHO>OCH₃OH>OHCOOH;对于非极性分子,官能团中C原子得到电子的能力为CC₂H₂>CC