用半导体高-低结概念对氧化银(Ⅱ)阴极过程所作的一种新解释

在半导体中, 由于掺杂水平的不同, 在同种导电类型的半导体之间会形成一种被称为高-低结的势垒, 也会象p-n结一样表现出一定程度的整流特性。由于这一势垒的存在, 半导体中载流子的运动受到一个附加电场的作用, 它们的运动规律与没有高-低结时相比有所不同, 因此造成这种半导体电性质比较特殊。如带有高-低结的p~+/p-Si光阴极具有良好的光电转换性能~[1], 效率较高。在一些电极反应过程中, 由于反应中间物质的形成也会构成一定程度的高-低结。本文首次将半导体固结的概念引入电化学, 研究了AgO电极的放电过程。用高-低结机理满意地解释了一些现行理论所不能解释的现象。     

Stereospecific Nucleophilic Substitution with Arylboronic Acids as Nucleophiles in the Presence of a CONH Group

Stereospecific nucleophilic substitution was achieved for the first time with arylboronic acids as nucleophiles. This transition‐metal‐free coupling between chiral α‐aryl‐α‐mesylated acetamides and arylboronic acids provided access to a series of chiral α,α‐diaryl acetamides with excellent enantioselectivity and moderate to good yields. The CONH functionality proved to be crucial for bridging the reactants and promoting the reaction. Efficient syntheses of a cannabinoid CB₁ receptor ligand, the antidepressant (S)‐diclofensine, and a key chiral building block of the inhibitor implitapide were successfully accomplished by using this method.     

重度烧伤病人血清及24小时尿中7种微量元素的动态变化

从１９９４年８月起对８例重度烧伤病人的血清和２４小时尿中Ｚｎ、Ｆｅ、Ｃｕ、Ｍｏ、Ｓｅ、Ｃｒ及Ｍｎ的含量进行了系统监测，从而了解治疗过程中血清和尿中元素的动态变化。结果表明：血清中Ｚｎ、Ｆｅ、Ｓｅ明显下降，Ｃｕ变化不明显；尿中７种元素排泄量明显超过报道的正常值，尤其多尿期丢失更大。这为治疗烧伤病人，对症补充，促进元素平衡，提高疗效，提供了有益的线索。     

基于成熟度评估的武器装备体系集成性能试验方法研究

单装试验到体系试验需要架设集成试验这座桥梁,论文借鉴技术集成成熟度评估方法提出了集成成熟度试验的思路,并建立了基于集成成熟度试验评估的装备体系集成性能试验方法,实现了体系集成性能的试验与评价,并通过示例对所提出的方法进行了演示验证,证明了方法的可行性。     

离子对色谱法研究吡咯并喹呤醌与D-丝氨酸反应的化学动力学

D-丝氨酸(DSer)作为一种新的神经递质存在于胶质细胞,在中枢神经系统疾病中发挥重要的作用;吡咯并喹呤醌(PQQ)能够促进神经因子的产生和神经保护作用。采用离子对色谱法测定吡咯并喹呤醌(PQQ)与DSer反应中游离PQQ的浓度,通过化学反应动力学研究PQQ与DSer的作用,为PQQ在神经递质的调节作用机制提供重要的信息。采用四丁基溴化铵为离子对试剂,PQQ与DSer孵育反应后各物质在Amethyst C18-P柱上的分离度较好,平均回收率为94.2%～99.3%,相对标准偏差为1.05%～2.03%。PQQ-DSer反应的平均速率常数分别为0.032 h~1 (25 ℃)、0.07 h~1(37 ℃)、0.17 h~1(50 ℃);平均反应活化能为54.7 kJ/mol;半衰期分别为22.0 h(25 ℃)、9.8 h(37 ℃)和3.99 h(50 ℃)。动力学结果显示PQQ对脑内DSer的平衡具有重要的调节作用。该方法简便、可靠。     

关于氮族元素教学改革的几点建议

Based on the knowledge characteristics of the chapter on nitrogen group elements, and combined with the teaching experience of our excellent video open course, this paper has probed the teaching reform of inorganic elements chemistry from the following aspects:using the principle of chemistry to explain the structure and properties of substances, designing problems to guide students to think and cultivate their learning ability, instructing students to be good at inducing the changing laws of material properties, paying attention to the relationship between the elements and compounds and practices of production and life. It aims to guide students to learn, memorize and master the knowledge of element chemistry effectively, and improve the quality of classroom teaching.     

固相萃取-高效液相色谱法测定啤酒中的黄腐酚

采用Waters Sep-Pak C18固相萃取小柱对啤酒样品进行分离纯化,建立了啤酒中黄腐酚的固相萃取-高效液相色谱检测方法。选用色谱柱Zorbax Eclipse XDB-C18柱(250 mm×4.6 mm,5 μm),以甲醇和0.1%甲酸水溶液为流动相进行梯度洗脱,柱温25 ℃,流速0.4 mL/min,检测波长370 nm。在此条件下,黄腐酚分离良好且无杂质峰干扰,在0.5～500 μg/L的范围内线性关系良好(r21),在高、中、低浓度下的加标回收率为91.21%～95.58%,相对标准偏差小于2%。方法的检出限为0.24 μg/L,定量限为0.80 μg/L。该方法简便快速、结果准确、重现性好,是检测啤酒中黄腐酚含量的有效方法。     

若干镧系三环戊二烯化合物的EHMO计算

用EHMO方法对LnCp_3(Ln=Pr、Nd、Pm、Sm、Eu、Gd、Tb,Cp=C_5H_5)进行了处理。计算结果表明:LnCp_3系列的能级、分子轨道百分组成等非常相似。总能量与原子序数成线性关系。Ln的4f轨道基本不参与成键。Ln-Cp间的键是以离子性为主的极性键。LnCp_3系列的电荷分布有一定规律。依据上述信息,对LnCp_3的一些化学性质作出了较为合理的解释。     

Rapid and Sensitive LC–MS/MS Analysis of Fatty Acids in Clinical Samples

Free fatty acids (FFAs), major cellular metabolites, play an important role during tumor pathogenesis. Enhanced de novo fatty acid synthesis in tissues is a characteristic feature of cancer. Therefore, measurement of FFA concentration in biological samples is beneficial for cancer research and clinical diagnosis. Herein, a rapid, stable, and sensitive detection methodology was established to simultaneously quantify 22 FFAs using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI–MS/MS). The HPLC–MS/MS system was run in negative ion mode for 15 min using multiple reaction monitoring. The lipids were extracted from colon tissues of colon cancer patients and then injected into the HPLC–MS/MS system for analysis. Colon samples were analyzed by inter-day repeatability and intra-day repeatability, with less than 5 % deviation for most fatty acids. This approach is successful to determine low picogram concentrations of each FFA molecule using milligrams of tissue, and provides a promising method for FFA microanalysis in clinical samples.

     

A well‐balanced stable generalized Riemann problem scheme for shallow water equations using adaptive moving unstructured triangular meshes

We propose a well‐balanced stable generalized Riemann problem (GRP) scheme for the shallow water equations with irregular bottom topography based on moving, adaptive, unstructured, triangular meshes. In order to stabilize the computations near equilibria, we use the Rankine–Hugoniot condition to remove a singularity from the GRP solver. Moreover, we develop a remapping onto the new mesh (after grid movement) based on equilibrium variables. This, together with the already established techniques, guarantees the well‐balancing. Numerical tests show the accuracy, efficiency, and robustness of the GRP moving mesh method: lake at rest solutions are preserved even when the underlying mesh is moving (e.g., mesh points are moved to regions of steep gradients), and various comparisons with fixed coarse and fine meshes demonstrate high resolution at relatively low cost. Copyright © 2013 John Wiley & Sons, Ltd.