气相色谱法分析氯氰菊酯异构体

比较了DB-1和HP-5石英毛细管柱在不同柱流速、柱温下对氯氰菊酯异构体的分离效果,表明采用DB-1石英毛细管柱(30m×0.25mmi.d.,0.25μm)较好,柱温为240℃,柱流速为12cm/s,分析时间40min。该分析方法重现性好,分析结果准确、可靠。     

脱氢枞胺及其衍生物的研究与应用进展

脱氢枞胺及其衍生物在手性拆分、金属离子浮选、表面活性、杀菌、医药、染料等领域有着重要的用途。本文对脱氢枞胺的制备、脱氢枞胺成盐衍生物以及脱氢枞胺成键衍生物的研究与应用进展进行了综述,并对脱氢枞胺及其衍生物的研究及应用前景进行了展望。     

Fe(Ⅳ)的合成及其稳定性研究

通过两种方法合成出Fe(Ⅳ)溶液,研究了Fe(Ⅳ)溶液的反应性、稳定性以及添加其他离子对Fe(Ⅳ)在水溶液中的稳定性的影响,并对Fe(Ⅵ)的反应历程进行了探讨。Fe(Ⅳ)离子的氧化性较Fe(Ⅵ)离子弱,可以氧化苯甲醇,而难以氧化间二甲苯;在Fe(Ⅳ)溶液中加入磷酸钠使其稳定性下降,而加入醋酸钠可显著提高Fe(Ⅳ)在溶液中的稳定性;Fe(Ⅳ)在溶液中的浓度越高越不稳定;随着碱浓度的增加Fe(Ⅳ)在溶液中的稳定性增强且在碱水溶液中Fe(Ⅳ)比Fe(Ⅵ)更稳定。     

Structural and Electrical Properties of Be_xZn_(1-x)O Alloys under High Pressure

We conduct extensive research into the structures of Be_xZn_1-xOO ternary alloys in a pressure range of 0-60GPa,using the ab initio total energy evolutionary algorithm and total energy calculations,finding several metastable structures.Our pressure-composition phase diagram is constructed using the enthalpy results.In addition,we calculate the electronic structures of the Be_xZn_1-xOO structures and investigate the bandgap values at varying pressures and Be content.The calculated results show that the bandgap of the Be_xZn_1-xOO ternary alloys increases with an increase in Be content at the same pressure.Moreover,the bandgap of the Be_xZn_1-xOO ternary alloys increases with the increasing pressure with fixed Be content.At the same Be content,the formation enthalpy of the Be_xZn_1-xOO ternary alloys first decreases,then increases with the increasing pressure.     

纳米碳管修饰铂结合溶胶-凝胶固定酶制备高性能胆碱生物传感器

为了提高胆碱传感器的灵敏度和抗干扰性,以纳米碳管修饰铂电极为基础电极,采用溶胶-凝胶法固定胆碱氧化酶(ChOx),构建了电流型胆碱检测生物传感器,对纳米碳管修饰电极的电化学特征进行分析,得知纳米碳管的引入不仅使电极对H2O2的催化电流增大,同时降低了电催化所需的恒定电位。讨论了缓冲液介质、pH值、酶负载量对传感器响应的影响。研究表明,所制备的传感器在pH 7.2、电位为0.15V条件下对氯化胆碱的线性响应范围为5.0×10-6~1.0×10-4mol/L;检出限为5.0×10-7mol/L;灵敏度为9.48μA/mmol/L。传感器的稳定性好,经过1个月,仍可保持初始电流的85%。抗干扰能力有很大提高。用于人体血清中的胆碱浓度测定,结果令人满意。     

使用叠栅层析技术测量超音速风洞中的非对称复杂密度场

使用叠栅层析技术解决超音速风洞中复杂密度场的测量难题。应用高灵敏度叠栅偏折仪和间隔角度旋转模型的方法获取超音速风洞中流场的多方向叠栅条纹图。层析计算中使用一种新的偏折角修正迭代的叠栅层析算法,该方法可以实现对有限角采样和包含遮挡物的非完全数据重建,迭代过程中结合内边界平滑滤波提高重建精度。实验中获取了马赫数为2.52的超音速风洞中9幅不同采样角的条纹图,经过50次迭代计算后重建出膨胀波区非对称密度场的截面分布,并对测量结果和误差进行了分析和讨论。使用计算流体力学技术对该密度场进行建模和计算,验证了叠栅层析重建结果的正确性,证实了该技术在测量复杂流场领域的重要价值。     

How the Aggregates Determine Bound Rubber Models in Silicone Rubber? A Contrast Matching Neutron Scattering Study

The correlation between aggregates and bound rubber structures in silicone rubbers(S(phr)) with various silica fractions(ΦSi) has been investigated by contrast matching small-angle neutron scattering(SANS), swelling kinetics, and low-field nuclear magnetic resonance(NMR).Mixed solvents with deuterated cyclohexane fractions of 4.9% and 53.7% were chosen to match the scattering length densities of the matrix(SMP(phr)) and the filler(SMS(phr)), respectively. All the data consistently suggest that:(i) There is a critical threshold ΦSic between 10 and 30 phr;below ΦSic, the isolated aggregates are dominant, while beyond ΦSic, some rubber fraction is trapped among the agglomerate;(ii) ΦSiindependent thicknesses around 7.5 nm(NMR) and 8.6 nm(SANS) suggest that the bound rubber formation is determined by inherent properties of the components, and the power-law around 4.2 suggests an exponential changed gradient density of the bound rubber;(iii) SMS(80) presents a bicontinuous bound rubber with three characteristic lengths of 41, 100, and 234 nm. The expanded correlation length, a 20 nm smaller aggregate sizes suggest that such existent bicontinuous network in dry samples with less ΦSi is kind of impacted by swelling. With the obtained bound rubber models, the reinforcing mechanism of filled silicone rubber is elucidated.     

The Biological Fate of Pharmaceutical Excipient β-Cyclodextrin: Pharmacokinetics,Tissue Distribution,Excretion, and Metabolism of β-Cyclodextrin in Rats

β-cyclodextrin has a unique annular hollow ultrastructure that allows encapsulation of various poorly water-soluble drugs in the resulting cavity, thereby increasing drug stability. As a bioactive molecule, the metabolism of β-cyclodextrin is mainly completed by the flora in the colon, which can interact with API. In this study, understanding the in vivo fate of β-cyclodextrin, a LC-MS/MS method was developed to facilitate simultaneous quantitative analysis of pharmaceutical excipient β-cyclodextrin and API dextromethorphan hydrobromide. The established method had been effectively used to study the pharmacokinetics, tissue distribution, excretion, and metabolism of β-cyclodextrin after oral administration in rats. Results showed that β-cyclodextrin was almost wholly removed from rat plasma within 36 h, and high concentrations of β-cyclodextrin distributed hastily to organs with increased blood flow velocities such as the spleen, liver, and kidney after administration. The excretion of intact β-cyclodextrin to urine and feces was lower than the administration dose. It can be speculated that β-cyclodextrin metabolized to maltodextrin, which was further metabolized, absorbed, and eventually discharged in the form of CO₂ and H₂O. Results proved that β-cyclodextrin, with relative low accumulation in the body, had good safety. The results will assist further study of the design and safety evaluation of adjuvant β-cyclodextrin and promote its clinical development.     

水性颜料体系无树脂色浆的制备与应用

中性墨水属于热力学上不稳定的颜料悬浮体系,选择低黏度、高稳定性的色浆是保证墨水体系分散稳定性的重要手段之一.基于此,以颜料炭黑和酞菁蓝为着色剂,配合超分散剂(EK43)与协同增效剂(BM10),制备了两款适用于中性墨水体系的无树脂色浆.首次从色浆粒径与体系分散稳定性角度出发,确定了EK43、BM10用量以及最佳研磨时间...     

Peridynamic modeling and simulation of coupled thermomechanical removal of ice from frozen structures

Meccanica - In this work, a bond-based peridynamic de-icing model has been developed to simulate the thermo-mechanical ice removal process of frozen structures. In the proposed numerical method,...