Syntheses,crystal structures and properties of Cd(II) and Ag(I) complexes based on 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole

Abstract

Complexes of [CdL₂(NO₃)₂]·1.5H₂O and [Ag₂(μ-L)₂(NO₃)₂] were synthesized by the reactions of 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole (L) with Cd(NO₃)₂·4H₂O and AgNO₃, respectively. Their structures were determined by single crystal X-ray diffraction. The photophysical property and thermal stability were characterized by FT???IR, UV???Vis absorption, fluorescence, and thermogravimetric analysis (TGA). Both complexes belong to the triclinic system with space group p???1. The central metal of [CdL₂(NO₃)₂]·1.5H₂O has a distorted octahedral geometry [CdN₄O₂], while two central Ag(I) atoms of [Ag₂(μ-L)₂(NO₃)₂] exhibit distorted tetrahedral geometries [AgN₃O].     

一种基于自适应单元删除率的BESO方法

在ESO中采用动态删除率能有效地提高优化效率和稳定性,但现有的动态删除率策略都含有经验参数,确定删除率的过程较为复杂。本文提出了一种用于BESO的无经验参数自适应单元删除率确定方法。通过分析单元删除率对优化稳定性的影响,得到了结构优化过程中单元删除率的理想变化规律和单元灵敏度均匀化信息对删除率的影响情况,并据此分析了经验参数引入的原因,从而构造了评价单迭代步的单元灵敏度均匀化程度指标。然后,基于单迭代步的单元灵敏度均匀化程度指标,构造了全部迭代步信息下的单元灵敏度均匀化程度相对指标,结合单元删除率的推荐范围值,给出了一种自适应于结构优化进程的单元删除率自适应函数。最后,给出了基于自适应单元删除率的BESO方法实现流程。经典算例的结果对比说明,本文方法在保证优化质量相近的情况下,具有更好的优化效率和稳定性。     

时滞Rucklidge系统Hopf分岔分析与电路实现

以一类新的单时滞Rucklidge系统为分析对象,通过计算时滞系统的平衡点,分析该系统在各平衡点的稳定性和Hopf分岔的存在性,得到其发生Hopf分岔的条件。Matlab多组数值仿真验证了理论分析的正确性。基于此设计了一种可切换时滞与非时滞的混沌电路,并运用Multisim14.0进行仿真,实验结果表明,该电路可行且有效。     

Structure and Processing Properties of Nine Yam (Dioscorea opposita Thunb) Starches from South China: A Comparison Study

In order to explore the processing and application potential of Chinese yam starch, nine kinds of Chinese yam starch (GY11, GY5, GY2, GXPY, LCY, SFY, MPY, SYPY, ASY) from South China were collected and characterized. The chemical composition, rheological properties, thermal properties, and in vitro starch digestion were compared, and the correlation between the structure and processing properties of these yam starches was analyzed using Pearson correlation. The results show that GY2 had the highest amylose content of 28.70%. All the yam starches were similarly elliptical, and all the yam starch gels showed pseudoplastic behavior. Yam starches showed similar pasting temperatures and resistant starch content, but SYPY showed the largest particle size (28.4 μm), SFY showed the highest setback (2712.33 cp), and LCY showed the highest peak viscosity (6145.67 cp) and breakdown (2672.33 cp). In addition, these yam starches also showed different crystal types (A-type, B-type, C-type), relative crystallinity (26.54–31.48%), the ratios of 1045/1022 cm⁻¹ (0.836–1.213), pasting properties, and rheological properties, so the yam starches have different application potentials. The rheological and pasting properties were related to the structural properties of starch, such as DI, Mw, and particle size, and were also closely related to the thermodynamic properties. The appropriate processing methods and purposes of the processed products of these yam starches can be selected according to their characteristics.     

浅谈Authorware课件制作过程中的一些细节

多媒体在目前教学中扮演一个很重要的角色,但做一个好的课件,是件很不容易的事。笔者通过Authorware6.5简体中文版制作课件,现将制作过程中有关细节拿出来供大家参考,希望大家在遇到类似问题时,能少走弯路,节约时间。1对视频文件的处理中常见问题化学课件中常需要插入一些视频,     

Carbonylative Stille coupling reactions of benzyl chlorides with allyltributylstannane catalyzed by palladium nanoparticles

The carbonylative Stille coupling reaction of benzyl chlorides with allyltributylstannane was successfully conducted by using palladium nanoparticles as the catalyst under phosphine ligand-free conditions. The corresponding α,β-unsaturated ketone products were obtained in good to excellent yields.     

仿生支撑液膜法制备硫化锌自组装纳米球链

采用了一种全新的化学仿生方法——载体支撑液膜法制备ZnS纳米球链. 常温常压条件下, 利用含邻菲罗啉载体的支撑液膜(SLM)反应体系选择性传输Zn^2＋至膜另一侧, 在SLM模板作用下, 控制结晶位点, 定向结合阴离子, 加上局部过饱和及界面成核的影响, 成功制备出由8～30 nm纳米粒子自组装的直径范围为250～300 nm ZnS球链. 由XRD和TEM的结果显示, 其结构为立方闪锌矿, 晶格常数为α＝0.5390 nm. 本文还对其荧光性质及产物形成机理进行了初步探讨.     

聚乳酸/β-磷酸三钙多孔复合支架的制备及性能研究

以聚乳酸和β-磷酸三钙共混制备了多孔复合支架,并对其孔隙率、降解性和力学性能进行了研究。结果表明,β-磷酸三钙的引入可以有效地减缓支架的降解,提高支架的力学性能。     

膨胀型类磷酸酯蜜胺盐阻燃剂的合成及应用研究

以双季戊四醇(DPE)、五氧化二磷、水和三聚氰胺为原料,合成了膨胀型环状类磷酸酯蜜胺盐阻燃剂。通过实验提出了合成该阻燃剂的最佳反应条件为：双季戊四醇(DPE)、五氧化二磷、水和三聚氰胺反应物料摩尔配比为1／2．5／2.0／3．45、反应时间4h和反应温度120℃。红外吸收图谱分析表明该阻燃剂具有环状结构,在热重分析和差热分析中该阻燃剂显示出优异的热稳定性和很高的成碳性。以该阻燃剂掺入聚丙烯中,阻燃效果显著,经测试阻燃聚丙烯的极限氧指数(LOI)为33．6,烟密度等级(SDR)为44．25,通过了UL94V-0级。     

Preparative high-speed counter-current chromatography for purification of shikonin from the Chinese medicinal plant Lithospermum erythrorhizon

The bioactive compound shikonin was successfully isolated and purified from the crude extract of the traditional Chinese medicinal plant Lithospermum erythrorhizon Sieb. et Zucc. by preparative high-speed counter-current chromatography (HSCCC). The preparative HSCCC was performed using a two-phase solvent system composed of n-hexane-ethylacetate-ethanol-water (16:14:14:5 (v/v)). A total amount of 19.6 mg of shikonin at 98.9% purity was obtained from 52 mg of the crude extract (containing 38.9% shikonin) with 96.9% recovery. The preparative isolation and purification of shikonin by HSCCC was completed in 200 min in a one-step separation.