Ni离子替位掺杂TiO2增强光热化学循环还原CO2研究

利用溶胶凝胶法（Sol-gel）制备纯TiO₂（ST）及Ni掺杂TiO₂（NT）纳米薄膜,将其应用在光热化学循环（PTC）还原CO₂中进行机理研究,并与商用P25（PT）进行对比.结果表明利用NT进行CO₂还原,每个循环得到的平均CO产率最高为5.30 μmol/g-cat,分别是利用ST与PT得到CO产率的3.13倍与2.28倍.利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线能量色散谱（EDXS）及X射线衍射技术（XRD）研究样品的物质组成、晶体结构与形貌.稳态与时间分辨固体光致发光光谱（PL）、紫外可见漫反射光谱（UV-vis DRS）和X射线光电子能谱（XPS）被用来进行材料光学性能及表面态检测,从而得到反应中激发电子转移机制.利用第一性原理计算研究材料表面氧空位形成能、态密度（DOS）及分态密度（PDOS）.结合实验表征与理论计算,理清控制PTC反应进行的关键因子.     

Controllable Sulfur,Nitrogen Co‐doped Porous Carbon for Ethylbenzene Oxidation: The Role of Nano‐CaCO3

Heteroatom‐doped porous carbon materials have exhibited promising applications in various fields. In this work, sulfur, nitrogen co‐doped carbon materials (SNCs) with abundant pore structure were prepared by pyrolysis of sulfur, nitrogen‐containing porous organic polymers (POPs) mixed with nano‐CaCO₃ at high temperature. Among the resultant materials, SNC‐Ca‐850 possesses a relatively high level of doped heteroatoms and exhibits an excellent catalytic performance for the selective oxidation of benzylic C?H bonds. It is noteworthy that nano‐CaCO₃ increases the doped sulfur content in the synthesized carbon materials to a large extent and impacts the existence modes of sulfur. In addition, it enhances the porous structure and specific surface area of the resultant SNCs significantly. This work provides a viable strategy to promote the doping of sulfur into carbon materials during the pyrolysis process.     

Phenanthroline‐Catalyzed Stereoretentive Glycosylations

Carbohydrates are essential moieties of many bioactive molecules in nature. However, efforts to elucidate their modes of action are often impeded by limitations in synthetic access to well‐defined oligosaccharides. Most of the current methods rely on the design of specialized coupling partners to control selectivity during the formation of glycosidic bonds. Reported herein is the use of a commercially available phenanthroline to catalyze stereoretentive glycosylation with glycosyl bromides. The method provides efficient access to α‐1,2‐cis glycosides. This protocol has been performed for the large‐scale synthesis of an octasaccharide adjuvant. Density‐functional theory calculations, together with kinetic studies, suggest that the reaction proceeds by a double S_N2 mechanism.     

如何发挥发烧器材应有的性能

每一位发烧友都希望自己的投入能获得预期的视觉和听觉享受,因而在决定购买器材之前都先作一系列的社会调查然后再作出决择。首先根据自己的经济能力结合实际使用需要,预计要购置多少种器材;然后详细调查这些器材的型号、性能指标、实际使用效果、设备间的合理配一K以及器材的价格,选择性能价格比高而且适合自己使用的器材。发烧友们对自己的行动计划作出如此周密的布署,按理应该取得十分满意的结果,但事实上不少人投人了大量的资金,所取得的实际效果与自己原来所要求的相距甚远。根据笔者的调查,出现这种现象的原因大多数既不是购…     

基于广义回归神经网络的强干扰下垂直阵目标距离估计方法

以声压场采样协方差矩阵为特征,基于广义回归神经网络研究在强干扰下的水下声源测距问题,该文提出了优化扩展因子的方法以提高神经网络估计性能.使用仅有一个网络参数的广义回归神经网络,使用SWellEX-96实验S59航次的垂直阵数据,比较了以传统匹配场处理为代表的模型驱动方法和以卷积神经网络、广义回归神经网络为代表的数据驱动...     

Arene Ru(II) Complexes Acted as Potential KRAS G-Quadruplex DNA Stabilizer Induced DNA Damage Mediated Apoptosis to Inhibit Breast Cancer Progress

A series of arene Ru(II) complexes, [(η⁶-MeC₆H₅)Ru(L)Cl]Cl, (L=o-ClPIP, 1; m-ClPIP, 2 and p-ClPIP, 3) (o-ClPIP=2-(2-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline; m-ClPIP=2-(3-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline; p-ClPIP=2-(4-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline) was synthesized and investigated as a potential apoptosis inducer in chemotherapy. Spectroscopy and molecular docking simulations show that 1 exhibits moderated binding affinity to KRAS G-quadruplex DNA by groove mode. Further, in vitro studies reveal that 1 displays inhibitory activity against MCF-7 growth with IC₅₀ = 3.7 ± 0.2 μM. Flow cytometric analysis, comet assay, and immunofluorescence confirm that 1 can induce the apoptosis of MCF-7 cells and G0/G1 phase arrest through DNA damage. In summary, the prepared arene Ru(II) complexes can be developed as a promising candidate for targeting G-quadruplex structure to induce the apoptosis of breast cancer cells via binding and stabilizing KRAS G-quadruplex conformation on oncogene promoter.     

Separation and Structural Characterization of a Novel Exopolysaccharide from Rhizopus nigricans

The present study aims to analyze the structural characterization and antioxidant activity of a novel exopolysaccharide from Rhizopus nigricans (EPS2-1). For this purpose, EPS2-1 was purified through DEAE-52, Sephadex G-100, and Sephadex G-75 chromatography. The structural characterization of EPS2-1 was analyzed using high-performance gel permeation chromatography (HPGPC), Fourier transform infrared spectroscopy (FT-IR), methylation analysis, nuclear magnetic resonance (NMR) spectra, transmission electron microscope (TEM), and atomic force microscope (AFM). The results revealed that EPS2-1 is composed of mannose (Man), galactose (Gal), glucose (Glc), arabinose (Ara), and Fucose (Fuc), and possesses a molecular weight of 32.803 kDa. The backbone of EPS2-1 comprised →2)-α-D-Manp-(1→ and →3)-β-D-Galp-(1→, linked with the O-6 position of (→2,6)-α-D-Manp-(1→) of the main chain is branch α-D-Manp-(1→6)-α-D-Manp-(1→, linked with the O-6 positions of (→3)-β-D-Galp-(1→) of the main chain are branches →4)-β-D-Glcp-(1→ and →3)-β-D-Galp-(1→, respectively. Finally, we demonstrated that EPS2-1 also shows free radical scavenging activity and iron ion reducing ability. At the same time, EPS2-1 could inhibit the proliferation of MFC cells and increase the cell viability of RAW264.7 cells. Our results suggested that EPS2-1 is a novel polysaccharide, and EPS2-1 has antioxidant activity. In addition, EPS2-1 may possess potential immunomodulatory and antitumor activities. This study promoted the application of EPS2-1 as the functional ingredients in the pharmaceutical and food industries.     

Two‐step cavitation in semi‐crystalline polymer during stretching at temperature below glass transition

Cavitation behavior in poly(4‐methyl‐1‐pentene) upon stretching below glass transition temperature was investigated by in situ ultra‐small angle X‐ray scattering technique. Strong stress‐whitening was observed indicating an extensive occurrence of cavitation in the material during tensile deformation below Tg. The X‐ray scattering patterns suggest oriented disc‐shaped cavities with normal mostly parallel to the stretching direction occurred. Structural parameters of such cavities such as thickness, radius, and tilting angle of the normal of the disc with respect to the stretching direction have been successfully calculated using a model fitting procedure. The results exhibited a two‐step process of cavitation that small amount of large cavities appeared first and then small cavities were triggered extensively in the samples at larger strains. This two‐step cavitation phenomenon can be weakened after the quenched sample was annealed or the sample was prepared by slow cooling. This peculiar two‐step cavitation process can be understood as a result of high frozen in internal stress in quenched sample that led to local failure of the materials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2007–2014