Combination of glass fibres and minerals in polyamides

Polyamides reinforced with glass fibres are characterised by high values for modulus of elasticity and notched impact strength but also have the negative properties of rough surfaces and anisotropy - particularly anisotropic shrinkage. Mineral-filled polyamides have good surface properties, are isotropic and have high impact strength, however, the elasticity modulus is only slightly better than for normal polyamides and notched impact strength values are relatively low. Through a combination of glass fibres and mineral filler, surface properties can be improved and anisotropy reduced. In order to achieve the optimum mechanical properties a range of 0 - 50 wt.-% glass fibre content and 0 - 40 wt.-% mineral content was systematically examined using statistically designed experiments. This investigation showed the relationship between the “Responses”, surface appearance, shrinkage, modulus of elasticity, impact strength and tensile properties and the “variables”, glass fibre and mineral content. Optimal products, based on the model functions, can be chosen in this way.     

关于无套利市场的二叉树期权定价模型性质的讨论

本文讨论了二叉树期权市场的无套利条件,引入有随机因素存在的二叉树欧式期权定价模型,并推出单阶段、多阶段情况下欧式期权的计算公式,证明了多阶段市场未定权益的重要性质.     

添加CaSO4·2H2O为晶种制备磷石膏半水硫酸钙晶须

以固体废弃物磷石膏为原料,在传统常压醇水热法的基础上添加CaSO₄·2H₂O为晶种制备半水硫酸钙晶须。采用单因素试验法探究了晶种含量、丙三醇含量和磷石膏质量分数对晶须结构和形貌的影响,确定晶须的最佳制备工艺条件。采用SEM和XRD对样品进行表征分析,实验结果表明:添加CaSO₄·2H₂O晶种制备晶须的长径比(49.29)比只添加丙三醇的样品的长径比(30.99)提高了近60%;当丙三醇与水的体积比(V)为1、晶种含量为1%、磷石膏质量分数为5%时制备的晶须的平均直径为0.65 μm,长径比达到了62.15,晶须的尺寸均匀。这说明添加1%CaSO₄·2H₂O晶种、V为1的丙三醇和质量分数为5%的磷石膏在常压下能制备出高长径比和尺寸均匀的半水硫酸钙晶须。     

Living and stereoselective polymerization of [2.2]-paracyclophan-2-ENE derivatives

Paracyclophene based monomers can be polymerized in a living fashion using the alkylidene initiator Mo(NAr)(CHCMe₂Ph)(OCMe(CF₃)₂)₂. The cis-specific nature of the polymerization is critical, since small amounts of trans olefin in the backbone renders the material insoluble. These polymers have complex photophysical behavior, probably a consequence of the close proximity of chromophores along the polymer backbone. Polymerization of 9-(tert-butyldimethylsilyloxy)-[2.2]-paracyclophan-1-ene produces a new precursor material which furnishes PPV under remarkably mild conditions.     

A Novel 3D Na(I) Coordination Polymer Constructed by 3,5-Bis(4'-Carboxy-Phenyl)-1,2,4-Triazole: Synthesis,Crystal Structure,and Photocatalytic Property

Crystallography Reports - A novel 3D metal coordination polymer, {[Na4(µ2-H2O)(DMF)2(BCT)2]?DMF}n (I) (DMF = N,N-dimethylformamide, H2BCT =...     

Quasielastic light scattering,mutual diffusion and viscoelasticity of polymer solutions

Quasielastic light (QEL) scattering studies of semidilute solutions of polystyrene in benzene and benzene plus diethyl phthalate mixed solvents have been carried out. Comparisons are made between experiment and theoretical results. It is found that the relative amplitude of the viscoelastic modes depends on the coupling parameter β (defined in the text). For the solutions with β=0, no viscoelastic component is observed in the QEL scattering spectrum, consistent with the theoretical prediction. The amplitude and a relaxation time distribution of the viscoelastic component of the QEL scattering spectrum of PS in the mixed solvent are found to depend on time. Steady state values are obtained only after the solution is equilibrated for more than a month. Time evolution of the QEL spectrum has been investigated.     

Flowfield of a helicopter submerged inlet with power output shaft

The submerged inlet is an attractive configuration for advanced helicopters due to its high stealth performance and low external drag.In this paper,a submerged ...     

Newly Emerging Strategies in Antiviral Drug Discovery: Dedicated to Prof. Dr. Erik De Clercq on Occasion of His 80th Anniversary

Viral infections pose a persistent threat to human health. The relentless epidemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global health problem, with millions of infections and fatalities so far. Traditional approaches such as random screening and optimization of lead compounds by organic synthesis have become extremely resource- and time-consuming. Various modern innovative methods or integrated paradigms are now being applied to drug discovery for significant resistance in order to simplify the drug process. This review provides an overview of newly emerging antiviral strategies, including proteolysis targeting chimera (PROTAC), ribonuclease targeting chimera (RIBOTAC), targeted covalent inhibitors, topology-matching design and antiviral drug delivery system. This article is dedicated to Prof. Dr. Erik De Clercq, an internationally renowned expert in the antiviral drug research field, on the occasion of his 80th anniversary.     

An Improved Approach for Practical Synthesis of 5-Hydroxymethyl-2′-deoxycytidine (5hmdC) Phosphoramidite and Triphosphate

5-Hydroxymethyl-2′-deoxycytidine (5hmdC) phosphoramidite and triphosphate are important building blocks in 5hmdC-containing DNA synthesis for epigenetic studies. However, efficient and practical methods for the synthesis of these compounds are still limited. The current research provides an intensively improved synthetic method that enables the preparation of commercially available cyanoethyl-protected 5hmdC phosphoramidite with an overall yield of 39% on 5 g scale. On the basis of facile and efficient accesses to cyanoethyl protected-5hmdU and 5hmdC intermediates, two efficient synthetic routes for 5hmdC triphosphate were also developed.