Rate Coefficients and Kinetic Isotope Effects of Cl+XCl→XCl+Cl (X=H,D, Mu) Reactions from Ring Polymer Molecular Dynamics

The ring-polymer molecular dynamics (RPMD) was used to calculate the thermal rate coefficients and kinetic isotope effects of the heavy-light-heavy abstract reaction Cl+XCl\begin{document}$ \rightarrow $\end{document}XCl+Cl (X = H, D, Mu). For the Cl+HCl reaction, the excellent agreement between the RPMD and experimental values provides a strong proof for the accuracy of the RPMD theory. And the RPMD results are also consistent with results from other theoretical methods including improved-canonical-variational-theory and quantum dynamics. The most novel finding is that there is a double peak in Cl+MuCl reaction near the transition state, leaving a free energy well. It comes from the mode softening of the reaction system at the peak of the potential energy surface. Such an explicit free energy well suggests strongly there is an observable resonance. And for the Cl+DCl reaction, the RPMD rate coefficient again gives very accurate results compared with experimental values. The only exception is at the temperature of 312.5 K, results from RPMD and all other theoretical methods are close to each other but slightly lower than the experimental value, which indicates experimental or potential energy surface deficiency.     

Recent Advances in Synergistic Antitumor Effects Exploited from the Inhibition of Ataxia Telangiectasia and RAD3-Related Protein Kinase (ATR)

As one of the key phosphatidylinositol 3-kinase-related kinases (PIKKs) family members, ataxia telangiectasia and RAD3-related protein kinase (ATR) is crucial in maintaining mammalian cell genomic integrity in DNA damage response (DDR) and repair pathways. Dysregulation of ATR has been found across different cancer types. In recent years, the inhibition of ATR has been proven to be effective in cancer therapy in preclinical and clinical studies. Importantly, tumor-specific alterations such as ATM loss and Cyclin E1 (CCNE1) amplification are more sensitive to ATR inhibition and are being exploited in synthetic lethality (SL) strategy. Besides SL, synergistic anticancer effects involving ATRi have been reported in an increasing number in recent years. This review focuses on the recent advances in different forms of synergistic antitumor effects, summarizes the pharmacological benefits and ongoing clinical trials behind the biological mechanism, and provides perspectives for future challenges and opportunities. The hope is to draw awareness to the community that targeting ATR should have great potential in developing effective anticancer medicines.     

聚芴类电致发光材料

聚芴与其衍生物是一类重要的电致发光聚合物,它们具有较高的光致发光效率,并且易于进行结构修饰,因此受到材料化学家们的高度关注。本文叙述的线索是聚合物结构与其电致发光性能之间的构效关系。通过化学修饰,可以调节材料的前线分子轨道、热和光谱稳定性,进而开发新的发光材料。文中首先简单介绍了聚芴类发光材料的聚合方法,然后把这些聚合物按结构不同分成两个部分介绍：一部分是主链仅含有共轭芴单元的聚合物,它们的化学修饰依赖于芴9位的活性碳原子;另一部分是通过共聚方法得到的主链含有芴和其它基团的聚合物。     

液相电化学沉积类金刚石薄膜的研究进展

采用电化学沉积法开展液相中类金刚石薄膜的制备工艺和理论的研究,对于完善类金刚石薄膜的合成技术,开拓类金刚石薄膜的应用领域,具有很重要的理论意义和实用价值。本文概述了液相电沉积技术的基本原理和方法,重点从四个方面介绍了电化学方法制备类金刚石薄膜的研究进展,总结了该方法所制备样品的性能,并对可能的反应机制作了综合性的阐述,最后对液相电沉积类金刚石薄膜的发展前景进行了展望。     

羟自由基对支撑磷脂双层膜的破坏及水溶性抗氧化剂保护作用的电化学研究

以支撑磷脂双层膜(supported bilayer lipid membrane, s-BLM)作为生物膜模型, 利用Fenton体系产生羟自由基(hydroxyl free radical, •OH), 采用循环伏安法研究了s-BLM与•OH之间的相互作用. 结果表明: •OH通过与磷脂发生化学反应, 诱发s-BLM上形成孔洞或缺陷, 这种作用对时间、FeSO₄和H₂O₂的浓度具有依赖性, 且不可恢复. 具有还原性基团的抗氧化剂维生素C, 还原型谷胱甘肽和L-半胱氨酸, 通过与•OH发生氧化还原反应, 可抑制•OH与s-BLM的相互作用, 降低•OH对s-BLM结构的破坏程度.     

石墨炉原子吸收法测定水系中的铍

用石墨炉原子吸收法测定水系中的铍,以Mg(NO3)2为基体改进剂,提高了测定铍的灵敏度,增强了测定铍的抗干扰能力。方法的线性范围为0－1．0μg/L,检出限为0．05μg/L。用于水库水、黄河水、饮用水和地下水等水中铍的测定,回收率为95％－110％。     

毛细管液相色谱法分离植物内源激素

建立了毛细管液相色谱法(CLC)同时分离测定4种植物内源激素的方法.采用硅胶基质ODS整体柱(27 cm×100 μm i.d.)作为分离柱,以带有光程为3 mm的光纤检测池的紫外检测器作为检测手段,在室温下以含10 mmol/L乙酸(pH 3.0)的V(甲醇):V(水)＝35:65为流动相,以0.6 μL/min的流速进行等度洗脱.采用溶剂梯度效应和扩展光程的检测池来提高检测灵敏度,该方法测定4种植物内源激素的检出限(S/N=3)在27.7～196.1 ng/mL之间,峰面积和保留时间的相对标准偏差(RSD)小于2.8%.方法已用于不同种类玉米样品的测定.     

乙炔二茂铁的合成表征和电化学性质测定

选择了一条反应条件温和且比较经济的反应途径,在惰性气氛中合成了一系列二茂铁衍生物的重要合成中间体——乙炔二茂铁。通过UV、IR、^1H NMR对化合物进行了表征,运用CV测定了电化学性质。该实验作为综合化学实验,有助于学生了解化学研究的一般过程,掌握惰性气氛合成技术及柱色谱分离方法,提高学生综合分析问题和解决问题的能力。     

干细胞迁移机理的近场扫描光学显微术研究

将内皮细胞生长因子(VEGF)置于甲基纤维素碟中形成VEGF的浓度梯度分布,并将人脐带间充质干细胞(Mesenchymal stem cells,MSCs)于此浓度梯度中培养,观察VEGF能否诱导MSCs定向迁移。应用近场扫描光学显微术(Near-field scanning optical microscopy,NSOM)同时获取了VEGF诱导前后的MSCs的形貌和光学信息。结果表明,近场光学图观测到形貌图上所没有的黑色斑点,分析认为这些黑斑为细胞的黏着斑。近场光学图显示经过VEGF诱导后细胞的黏着斑数量明显增加。同时,对诱导前后干细胞的骨架蛋白进行免疫荧光标记并用共聚焦显微镜进行观察,结果表明细胞骨架由诱导前的无序状态转变为诱导后的有序状态,说明诱导后的干细胞处于迁移状态。光学超微结构图则显示了诱导后干细胞表面的光学细节比诱导前细胞大量增加,出现了大量直径约200 nm的光斑,这是由于细胞表面大量分泌黏附分子等蛋白分子引起的,这些结果为VEGF能够诱导MSCs进行定向迁移提供了实验依据和可视化证明。也表明NSOM不但能提供高分辨的光学分辨率,还可提供生物细胞精细结构的更深层次的光学信息。