Al纳米线凝固过程的分子动力学模拟

结合EAM镶嵌原子作用势, 通过经典的分子动力学模拟研究了不同冷却速率下Al纳米线的凝固行为, 并采用键对分析技术探讨了体系中的原子团簇在不同冷却速率下的转化情况. 结果表明, 随着冷却速率的降低, Al纳米线的微观结构从非晶态过渡到多壳螺旋结构, 而多壳螺旋结构具有部分非晶结构的特征, 但是比非晶结构更稳定. 此外, 在冷却速率降低到1×10⁹ K·s-1的情况下, Al纳米线仍然保持多壳螺旋结构.     

核磁共振技术在保健食品非目标成分分析中的应用

采用二维扩散排序谱(2D-DOSY)和脉冲宽度(PULCON)定量等多种核磁共振(NMR)技术,对具有减肥功效的保健食品中主要成分进行了定性、定量研究。采用布鲁克AvanceⅢ600 MHz超导核磁共振波谱仪,以氘代丙酮为溶剂,对待测物进行了核磁检测。2D-DOSY表明该保健食品中含有3种主要化学成分,结合多种NMR技术对3个化合物进行了结构解析,归属了其所有的NMR谱信号,确定样品的主要成分为邻苯二甲酸二乙酯、褪黑素和奥美拉唑。最后采用PULCON定量技术测得3种成分的绝对含量分别为16.65、5.38、46.35 mg/g。测定结果与HPLC定量结果的对比表明,核磁共振方法能够在无对照品作参比,无需分离的条件下,直接、快速、准确分析保健食品中非目标成分的物质组成和绝对含量。     

气相中烯丙基负离子与N2O反应机理

采用二阶微扰理论的MP2/6-31G(d,p)方法对气相中烯丙基负离子与N2O的反应机理进行了理论计算研究, 并在相同基组下进一步用CCSD(T)方法进行了单点能的校正. 计算结果表明, 该反应存在三条反应通道, 产物分别为cis-CH2CHCNN-+H2O, trans-CH2CHCNN-+H2O和CH2CCH-+N2+H2O, 其中生成cis-CH2CHCNN-和trans-CH2CHCNN-的两条通道为相互竞争的主反应通道, 计算结果与实验相吻合. 同时利用传统的过渡态理论, 计算了各反应通道在298 K时, 速控步骤的反应速率常数k(T).     

Synthesis and Characterization of Ferrocenyl Substituted Styryl Octasilsesquioxane

4-(2-Ferrocenylethenyl)-phenyl-POSS Fc-CH=CH-C6H6-(C5H9)7Si8O12 (FEPS, Fc: ferrocene), containing metal and C=C double bond, was firstly synthesized as a mixture of E/Z isomers by the Wittig reaction. The chemical structure of FEPS was characterized by FTIR, 1H-, 13Cand 29Si-NMR.     

微波在核苷类化合物合成中的应用

核苷类化合物由于其显著的抗病毒、抗癌等生理活性而受到广泛关注. 利用微波促进核苷类化合物的合成与传统合成方法相比, 有明显的优势. 对近年来微波在核苷类化合物合成中的应用进行综述, 着重介绍了微波作用于几种重要核苷类化合物合成反应类型的研究状况.     

碱提猴头发酵菌丝体水溶性多糖HPP的结构确定

从猴头发酵菌丝体水提后残渣中用碱提出了水溶性粗多糖,对其分级纯化得到纯样HPP,SepharoseCL-6B柱层析测得其相对分子质量约为6 53×104,G C 分析表明,其单糖组成为Glc;经部分酸水解、高碘酸氧化、Smith降解和甲基化分析确定此多糖为多分枝结构,其中(1→6)Glc构成主链的核心结构;分支点为O-3;支链部分由(1→3)Glc构成,并连接一端基Glc.     

结合理论课堂的知识点设计高分子材料合成实验课程

尝试在"高分子材料合成创新实验"课程中将理论课的知识点巧妙地融入到实验教学中，有目的地设置实验环节，通过对实验现象的分析，帮助学生巩固理论课知识点。为了充分利用实验的等待时间，在有目的地组织学生对实验进行预习的基础上，还尝试"激励学生参与"实验课的教学，鼓励学生以实验小组的形式讲解与实验相关联的理论知识，进一步巩固相关知识点，并扩充知识面。2年的实验教学反馈表明，这些尝试既有效巩固了理论课堂的知识点，做到了活学活用，又激发了学生的学习兴趣，提高了分析问题的能力。     

紫外光同步固化合成互穿聚合物网络研究

互穿聚合物网络是研制高阻尼材料的理想结构,但从目前国内外文献报道的同步法互穿网络体系来看,由于在制备中采用了两种不同的聚合方法,实际上在形成网络结构的过程中都不是十分理想的同步反应,其反应速度均存在着一定程度的差别。     

A STOICHIOMETRIC DISPLACEMENT MODEL OF SOLUTE ADSORPTION IN LIQUID-SOLID SYSTEM

Based on five thermodynamic equilibria involving solutes, solvents and adsorbents, a stoichiometric displacement adsorption model adaptable to various adsorption systems consisting of different types of solutes, solvents and adsorbents has been presented. The kernel of this model is that as the solute molecules are adsorbed by the adsorbent, a stoichiometric number of the solvent molecules is necessarily released. The model was tested with originally published data from an extensive literature. The linear parameter values from the model have been used for quantitatively explaining the phenomenon of the liquid-solid adsorption. Having compared with Langmuir model in many respects, it is found that this model is better.     

Locking Function of a Key Residue in Kinesin＇s Gating Mechanism

In kinesin＇s mechanochemical cycle, ATP＇s binding to the nucleotide-free leading head is exquisitely gated so that futile hydrolysis is effectively avoided, Experiments show that, when both kinesin heads bind to a microtubule~ ATP cannot bind to kinesin＇s leading head when the neck linker （NL） of this head has a backward orientation. How NL＇s backward orientation is maintained needs understanding on a structural basis. By using steered molecular dynamics and rrmtation simulations, we investigate the backward-pointing conformation of the leading head＇s NL under different inter-head tensions. We find that the NL cannot keep in a strict backward orientation solely by the inter-head tension. LYS325 （amino acid sequence in 2KIN） has an assistant locking function which locks the NL and β0 to the β-domain. This locking function has an enhanced positive cooperation with the inter-head tension. When the inter-head tension is weakened, this locking function can be broken, resulting in a loose backward orientation of the NL. The difference between the strict and loose backward orientation of the NL might be a crucial factor in the gating mechanism. These results are consistent with relevant experiments and proposals.