Cobalt(II)-Catalyzed C(sp3)−C(sp3) Coupling for the Direct Stereoselective Synthesis of 2-Deoxy-C-Glycosides from Glycals

We report a ligand-controlled Co^II-catalyzed C(sp³)−C(sp³) coupling hydroalkylation for direct and β-selective synthesis of 2-deoxy-C-glycosides from glycals. This reaction proceeds by a radical pathway for alkyl halide activation and is β-selective through ligand control. This approach may inspire the development of further stereoselective coupling reactions with potential application in the field of carbohydrates.     

CH4-O2 混合气中爆燃爆震转捩的数值模拟

运用化学流体力学基本理论和两步燃烧反应模型原理，建立了一维封闭体系可燃气爆燃爆震转变现象的数学模型，利用拉格朗日质量坐标变换下的Ｌａｘ－Ｗｅｎｄｒｏｆ和Ｍｅｃｏｒｍｉｃ气动差分与Ａｄａｍｓ化学差分格式，求解基本方程，成功地完成了过程的数值模拟，清楚地说明了可燃气中ＤＤＴ现象由压缩波到激波达到稳态爆震的发生机制和火焰带引生爆震波的过程行为。     

Immobilized complexes of the salen Schiff’s base with metal as oxidation catalysts

The immobilized metal complexes with the Schiff’s base of salen have shown high catalytic activity in oxidation of alkenes, cycloalkenes, and alcohols as compared with their unsupported analogs. Due to the heterogeneous nature of such catalysts, their separation and recycling is rather simple.     

High efficiency of Mn–Ce‐modified TiO2 catalysts for the low‐temperature oxidation of Hg0 under a reducing atmosphere

Manganese‐ and cerium oxide‐modified titania catalysts were prepared by the deposition precipitation for the removal of elemental mercury (Hg⁰) from simulated yellow phosphorus off‐gas at low temperature. In addition, these catalysts were characterized by X‐ray diffraction, Brunauer–Emmett–Teller measurements, X‐ray photoelectron spectroscopy and field‐emission scanning electron microscope to determine the surface morphology of the obtained compounds and explore their formation mechanism. The results revealed that a Mn–Ce loading and reaction temperature of 10% and 150 °C, respectively, as well as a Mn/Ce molar ratio of 2:1, led to an optimal efficiency for the oxidation of elemental mercury. Furthermore, the effects of flue gas components were investigated. The presence of O₂ clearly promoted the oxidation of Hg⁰. A CO atmosphere did not affect the Hg⁰ oxidation, when compared with N₂, whereas the presence of H₂S and water vapor inhibited the oxidation process. Furthermore, the X‐ray photoelectron spectroscopy spectra of Hg 4f revealed that the elemental mercury adsorbed by the catalyst is present as HgO. Finally, the Hg⁰ catalytic oxidation mechanism was discussed on the basis of the experimental results and characterization analysis.     

Comparison and application of different empirical correlations for estimating the hydrate safety margin of oil-based drilling fluids containing ethylene glycol

As the oil and gas industries continue to increase their activity in deep water, gas hydrate hazards will become more serious and challenging, both at present and in the future. Accurate predictions of the hydrate-free zone and the suitable addition of salts and/or alcohols in preparing drilling fluids are particularly important both in preventing hydrate problems and decreasing the cost of drilling operations. In this paper, we compared several empirical correlations commonly used to estimate the hydrate inhibition effect of aqueous organic and electrolyte solutions using experiments with ethylene glycol (EG) as a hydrate inhibitor. The results show that the Najibi et al. correlation (for single and mixed thermodynamic inhibitors) and the Ostergaard et al. empirical correlation (for single thermodynamic inhibitors) are suitable for estimating the hydrate safety margin of oil-based drilling fluids (OBDFs) in the presence of thermodynamic hydrate inhibitors. According to the two correlations, the OBDF, composed of 1.6 L vaporizing oil, 2% emulsifying agent, 1% organobentonite, 0.5% SP-1, 1% LP-1, 10% water and 40% EG, can be safely used at a water depth of up to 1900 m. However, for more accurate predictions for drilling fluids, the effects of the solid phase, especially bentonite, on hydrate inhibition need to be considered and included in the application of these two empirical correlations.     

Zinc Porphyrins with a Pyridine‐Ring‐Anchoring Group for Dye‐Sensitized Solar Cells

Anchoring groups are extremely important in controlling the performance of dye‐sensitized solar cells (DSCs). The design and characterization of sensitizers with new anchoring groups, in particular non‐carboxylic acid groups, has become a recent focus of DSC research. Herein, new donor? π? acceptor zinc? porphyrin dyes with a pyridine ring as an anchoring group have been designed and synthesized for applications in DSCs. Photophysical and electrochemical investigations demonstrated that the pyridine ring worked effectively as an anchoring group for the porphyrin sensitizers. DSCs that were based on these new porphyrins showed an overall power‐conversion efficiency of about 4.0 % under full sunlight (AM 1.5G, 100 mW cm^?2).     

Lys121-Ile的定点突变对人尿胰蛋白酶抑制剂热稳定性的影响

为检验人尿胰蛋白酶抑制剂(UTI)两个结构域中的盐键的稳定性对UTI热变性可逆性的影响,将UTI中的Lys121突变成Ile以中断Glu69与Lys121之间形成的盐键,并命名为?UTI.然后对?UTI进行表达纯化和热解折叠实验.结果显示,?UTI在大肠杆菌中成功表达,纯化复性后经园二色谱测定三级结构与UTI基本相似,酶学测定表明恢复胰蛋白酶抑制剂活性.热变性实验表明:在pH低于7.4的缓冲溶液中?UTI的热解折叠是可逆的,与UTI的结果(pH<4.2)相比,pH值提高了3.结合以前对UTI在酸性条件下可逆热解折叠而在中性与碱性条件下不可逆热解折叠的机制的研究结果,认为多结构域蛋白解折叠的曲线除考虑各个结构域单独形成的多个S曲线的叠加外,还要考虑到结构域之间相互作用强度的影响.     

基于CsPb0.9Sn0.1IBr2的全无机钙钛矿太阳能电池展示出效率和稳定性的提升

正钙钛矿太阳能电池是一种非常有前景的新型光伏器件。近年来,其光电转换效率的最高记录已经从3.8%迅速上升到22.1%~(1–5)。常见的有机-无机杂化卤化物钙钛矿材料的通用化学式为ABX3,其中A位点通常是有机阳离子(如甲基铵     

线性半向量二层规划问题的全局优化方法

研究了线性半向量二层规划问题的全局优化方法. 利用下层问题的对偶间隙构造了线性半向量二层规划问题的罚问题, 通过分析原问题的最优解与罚问题可行域顶点之间的关系, 将线性半向量二层规划问题转化为有限个线性规划问题, 从而得到线性半向量二层规划问题的全局最优解. 数值结果表明所设计的全局优化方法对线性半向量二层规划问题是可行的.