Novel alternating copolyoxamides with high crystallinity and heat resistance

Two series of novel alternating copolyoxamides (PAnT-alt-n2 and PAn2-alt-62) are synthesized via solution/solid-state polycondensation (SSP). The alternating structures are analyzed carefully with ¹H NMR and ¹³C NMR spectra. The melting behaviors, thermal stabilities, crystal structures and crystallinities are systematically evaluated by DSC, TGA and WAXD. The results reveal that these alternating copolyoxamides possess almost perfect alternating chain structures and have high melting temperature (T_m > 270 °C), high crystallinity (X_c > 32%) and high decomposition temperature (T₅ > 405 °C) as well as low saturated water absorption (<3.5 wt%), which suggests that they have high potential as engineering plastic of high heat resistant.     

电缆槽对电缆间串扰的影响研究

电缆在使用时一般会铺设在电缆槽中,而电缆槽对铺设其中电缆之间的串扰会形成影响.针对电缆槽中电缆之间的串扰问题,提出一种结合多端口网络理论及分块级联思想的建模方法,使用基于波导格林函数的矩量法来提取电缆槽中电缆间的分布参数,并用虚拟节点理论将提取的分布参数矩阵转化为模型中的传输函数.通过与商业电磁仿真软件的仿真结果进行对比,验证了本文的模型及算法在分析电缆槽中电缆间的串扰问题时具有较好的精确度,最后运用此方法分析了电缆处于电缆槽中不同位置时的线间串扰大小,并结合铁路现场的实际情况对电缆槽中电缆的布线方式提出了建议.     

Electro-assisted Molecular Assembly Giving Atomic-Scale Catalytic Active-Site Detection

The artificially accurate design of nonmetal electrocatalysts’ active site has been a huge challenge because no pure active species with the specific structure could be strictly controlled by traditional synthetic methods. Species with a multiconfiguration in the catalyst hinder identification of the active site and the subsequent comprehension of the reaction mechanism. We have developed a novel electro-assisted molecular assembly strategy to obtain a pure pentagon ring on perfect graphene avoiding other reconstructed structures. More importantly, the active atom was confirmed by the subtle passivation process as the topmost carbon atom. Recognition of the carbon-defect electrocatalysis reaction mechanism was first downsized to the single-atom scale from the experimental perspective. It is expected that this innovative electro-assisted molecular assembly strategy could be extensively applied in the active structure-controlled synthesis of nonmetal electrocatalysts and verification of the exact active atom.     

Flow-induced shear stress and deformation of a core–shell-structured microcapsule in a microchannel

A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications.     

基于信息化知识管理系统的中医拔尖人才培养模式

中医拔尖人才的培养是新时期中医院校和中医医院发展的"核心竞争力",信息化知识管理系统是运用信息技术将名老中医的隐性知识转化为显性知识,利用网络存储、系统开发、资源共享的便捷性探索适用面更广、形式更灵活多样、可操作性更强的中医拔尖人才培养模式.     

产气荚膜梭菌ε毒素的细胞毒机制及致病机理的研究进展

产气荚膜梭菌ε毒素（Epsilon toxin ，ETX）由B、D型产气荚膜梭菌产生并分泌至宿主动物体内，在临床上主要症状为肠毒血症．ETX属于以七聚体形式存在的β‐样成孔毒素，它能够形成由14个β折叠片组成的“β‐桶状”结构，这个“β‐桶状”结构可以插入真核细胞的质膜形成穿孔．在细胞水平，ETX能够迅速使细胞膜肿胀、多种细胞器破坏，最终导致靶细胞的坏死．在哺乳动物体内，ETX能够使哺乳动物血管产生水肿，从而穿透血脑屏障而聚积在动物肾和脑中，导致机体随着谷氨酸盐的释放而产生过度兴奋，这一系列反应的发生可以引起机体出现脑水肿和肾衰竭，最终导致动物的死亡．目前， ETX备受关注的主要原因不仅仅因为它是一种β‐样成孔毒素，而是可以作为潜在的一种工具类药物，经改造后可以携带治疗药物在短时间内靶向性地到达哺乳动物脑和中枢神经系统，继而为脑和中枢神经系统疾病的治疗提供新的方向．结合国内外相关研究，对ETX细胞毒机制及致病机理进行了综和评述．     

Formation of Azulene-Embedded Nanographene: Naphthalene to Azulene Rearrangement During the Scholl Reaction

Incorporation of a non-hexagonal ring into a nanographene framework can lead to new electronic properties. During the attempted synthesis of naphthalene-bridged double [6]helicene and heptagon-containing nanographene by the Scholl reaction, an unexpected azulene-embedded nanographene and its triflyloxylated product were obtained, as confirmed by X-ray crystallographic analysis and 2D NMR spectroscopy. A 5/7/7/5 ring-fused substructure containing two formal azulene units is formed, but only one of them shows an azulene-like electronic structure. The formation of this unique structure is explained by arenium ion mediated 1,2-phenyl migration and a naphthalene to azulene rearrangement reaction according to an in-silico study. This report represents the first experimental example of the thermodynamically unfavorable naphthalene to azulene rearrangement and may lead to new azulene-based molecular materials.     

大学生勤工助学体验性学习实践模式探索

以北京联合大学的大学生勤工助学体验性学习实践为例,通过课题研究,探讨了适用于高校大学生勤工助学体验性学习实践的模式。