生物活性含硅有机锡化合物的研究

对近年来含硅有机锡化合物的进展进行了综述,结构和活性关系的研究表明化合物的生物活性主要取决于硅原子上的取代基,生物活性大小顺序为:(Me₃SiCH₂)₃SnY>>(PhMe₂SiCH₂)₃SnY＞(Ph₂MeSiCH₂)₃SnY,(PhCH₂Me₂SiCH₂)₃SnY.     

Relationships between structure, retention and biological activity of some Schiff base ligands and their complexes

The lipophilicity of a series of Schiff base ligands and their complexes with nickel(II) and copper(II) has been determined by reversed-phase thin-layer chromatography using binary dioxane-water mobile phase. Chelate ligands were prepared by condensation of diamine and the corresponding beta-diketone. Copper(II) and nickel(II) complexes with chelate ligands containing ethane-1,2-diamine or propane-1,2-diamine as the amine part and pentane-2,4-dione and/or 1-phenylbutane-1,3-dione, pentane-2,4-dione and/or 1,1,1-trifluoropentane-2,4-dione, or 1,1,1-trifluoropentane-2,4-dione and/or 1-phenylbutane-1,3-dione as the beta-diketone part were synthesized. Some of investigated compounds were screened for their in vitro antifungal activity against Sacharomyces cerevisiae and antibacterial activity against Escherichia coli. Chromatographically obtained lipophilicity parameters were correlated both with calculated n-octanol-water partition coefficient C log P and antimicrobial activities. Satisfactory correlations were obtained. Chromatographic data proved to be reliable parameters for describing the lipophilic properties of the investigated compounds. Additionally, the principal components analysis was performed on the data chromatographically obtained. This statistical method was useful for distinguishing compounds and objective comparison of their lipophilicity parameters.     

三维全息原子场作用矢量用于吡咯类抗艾滋病药物QSAR研究

采用三维全息原子场作用矢量(3D-HoVAIF)对32个吡咯类抗艾滋病药物进行结构参数化表征,并与其活性建立定量构效关系。分别采用多元线性回归(MLR)和偏最小二乘(PLS)进行建模,建模的复相关系数(R2cum)、交互校验复相关系数(Q2cum)和模型的标准偏差(SD)分别为R2cum=0.914、Q2cum=0.812、SD=0.236(MLR);R2cum=0.836、Q2cum=0.719、SD=0.314(PLS),结果均优于文献值(R2cum=0.667,Q2cum=0.581,SD=0.420)。所建模型具有良好的稳定性和预测能力,表明3D-HoVAIF能够较好地表征该类分子的结构,值得进一步推广应用。     

新烟碱类杀虫剂生物活性的理论研究和结构修饰*

在B3LYP/6-311G基组水平下,运用密度泛函理论(DFT)的量子化学方法,对20种重氮乙烷新烟碱类杀虫剂分子的电子结构特征进行了研究,获得了它们的前线轨道能(EHOMO、ENHOMO、ELUMO、ENLUMO等)、原子电荷(Qi)、摩尔熵(Sm)、偶极矩(μ)等量化参数与物理性质。经最佳变量子集回归研究发现,重氮乙烷新烟碱类杀虫剂分子对果蝇n AChRs、哺乳动物α4β2亚型的亲和力常数(p KD、p KA)分别与ELUMO、QW、QF、QN等参数具有良好的线性关系。逐一或逐四剔除交互验证以及VIF、tα/2检验,所建2个QSAR模型具有良好的稳健性及预测能力。根据2个QSAR模型推断了重氮乙烷新烟碱类分子可能的杀虫机理。进一步研究发现,在重氮乙烷新烟碱类分子的吡啶环上的合适部位,选用不含复键的吸电子能力较强的取代基团对其进行结构修饰,有利于提高修饰后分子的生物活性。基于分子17,设计出4种经结构修饰后对果蝇n AChRs亲和力显著提高的重氮乙烷新烟碱类分子(分别是分子27,28,30和31),希望能得到实验的证实。     

Development of models for prediction of the antioxidant activity of derivatives of natural compounds

Antioxidants are important for maintaining the appropriate balance between oxidizing and reducing species in the body and thus preventing oxidative stress. Many natural compounds are being screened for their possible antioxidant activity. It was found that a mushroom pigment Norbadione A, which is a pulvinic acid derivative, shows an antioxidant activity; the same was found for other pulvinic acid derivatives and structurally related coumarines. Based on the results of in vitro studies performed on these compounds as a part of this study quantitative structure–activity relationship (QSAR) predictive models were constructed using multiple linear regression, counter-propagation artificial neural networks and support vector regression (SVR). The models have been developed in accordance with current QSAR guidelines, including the assessment of the models applicability domains. A new approach for the graphical evaluation of the applicability domain for SVR models is suggested. The developed models show sufficient predictive abilities for the screening of virtual libraries for new potential antioxidants.     

Insights into the electrochemical degradation of sulfamethoxazole and its metabolite by Ti/SnO2-Sb/Er-PbO2 anode

Electrochemical degradation of sulfamethoxazole (SMX) and its metabolite acetyl-sulfamethoxazole (Ac-SMX) by Ti/SnO₂-Sb/Er-PbO₂ were investigated. Results indicated that the electrochemical degradation of SMX and Ac-SMX followed pseudo-first-order kinetics. The rate constants of SMX and Ac-SMX were 0.268 and 0.072 min^-1 at optimal current density of 10 and 14 mA/cm², respectively. Transformation products of SMX and Ac-SMX were identified and the possible degradation pathways, including the cleavage of S-N bond, opening ring of isoxazole and nitration of amino group, were proposed. Total organic carbon removal of SMX was nearly 63.2% after 3 h electrochemical degradation. 22.4% nitrogen of SMX was transformed to NO₃^-, and 98.8% sulfur of SMX was released as SO₄^2-. According to quantitative structure-activity relationship model, toxicities of SMX and Ac-SMX to aquatic organisms significantly decreased after electrochemical degradation. Electric energy consumption for 90% SMX and Ac-SMX degradation was determined to be 0.58-8.97 and 6.88-44.19 Wh/L at different experimental conditions, respectively. Compared with parent compound SMX, the metabolite Ac-SMX is more refractory and toxic, which emphasizes the importance of taking its metabolites into account when investigating the disposal of pharmaceuticals from wastewater.     

Facet-dependent antibacterial activity of Au nanocrystals

Engineered nanomaterials have attracted significantly attention as one of the most promising antimicrobial agents for against multidrug resistant infections. The toxicological responses of nanomaterials are closely related to their physicochemical properties, and establishment of a structure-activity relationship for nanomaterials at the nano-bio interface is of great significance for deep understanding antibacterial toxicity mechanisms of nanomaterials and designing safer antibacterial nanomaterials. In this study, the antibacterial behaviors of well-defined crystallographic facets of a series of Au nanocrystals, including {100}-facet cubes, {110}-facet rhombic dodecahedra, {111}-facet octahedra, {221}-facet trisoctahedra and {720}-facet concave cubes, was investigated, using the model bacteria Staphylococcus aureus. We find that Au nanocrystals display substantial facet-dependent antibacterial activities. The low-index facets of cubes, octahedra, and rhombic dodecahedra show considerable antibacterial activity, whereas the high-index facets of trisoctahedra and concave cubes remained inert under biological conditions. This result is in stark contrast to the previous paradigm that the high-index facets were considered to have higher bioactivity as compared with low-index facets. The antibacterial mechanism studies have shown that the facet-dependent antibacterial behaviors of Au nanocrystals are mainly caused by differential bacterial membrane damage as well as inhibition of cellular enzymatic activity and energy metabolism. The faceted Au nanocrystals are unique in that they do not induce generation of reactive oxygen species, as validated for most antibiotics and antimicrobial nanostructures. Our findings may provide a deeper understanding of facet-dependent toxicological responses and suggest the complexities of the nanomaterial-cell interactions, shedding some light on the development of high performance Au nanomaterials-based antibacterial therapeutics.     

金属硫化物在可充电电池中的研究进展

低成本、长寿命、高安全性、高性能且易于大规模生产的锂/钠离子电池已被证实为重要的二次储能设备。 电极材料对锂/钠电池性能与循环寿命影响极大,金属硫化物由于具有高比容量和低电势而极具潜力成为锂/钠离子电池负极材料。 在电化学循环过程中,由于金属硫化物容易产生穿梭效应和体积变化,从而电极材料结构被破坏,进一步导致电池容量衰退、稳定性降低。 本文总结了多种金属硫化物的微观结构调控策略,从三维空间构建到与其它材料的复合,增强了电极的导电性和减缓体积变化带来的负面影响,进而获得性能优异的金属硫化物负极材料。 通过对金属硫化物的结构与性能的讨论,对其研究前景进行了积极的展望。     

A refined numerical model for determining inflation-burst behavior of composite membrane structures

The airship structures made of multi-layer composite fabrics or membranes can offer the platform for earth observations, wireless communications and space research due to light weight and good mechanical performance. The structural safety and serviceability strongly depend on material properties and working conditions. Available studies are limited within service stress limits or are lack of suitable biaxial tensile constitutive models for understanding structural behavior. This paper thus focuses on a refined numerical model for determining inflation-burst behavior of composite airship structures considering new biaxial constitutive equations, novel failure criteria and manufacture factors.The differences between ideal and real forms of airship structures, e.g. volume difference, demonstrate the necessity for incorporating cutting-pattern effects in the initial numerical model. For structural analysis, stress distributions on real structural forms are different from those on ideal forms because of welding parts that can enhance local stiffness. The ultimate pressures are 56.7 kPa and 59.5 kPa for ideal and real structural forms. Structural breaking initiated at the maximum diameter of ideal structural forms propagates fast while welding parts can prevent breaking propagation for real structural forms. Therefore, the refined numerical model can reveal basic structural behavior and safety performance of airship structures in the inflation-burst processes.