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981.
化学污染物总是以混合物形式存在于实际环境体系中. 化学混合物的毒性评估与预测是环境化学领域当前的研究热点与难题. 要评估与预测一个化学混合物的毒性效应, 首先要证明其是否具有加和性. 目前有3个加和参考模型即浓度加和模型(CA)、独立作用模型(IA)与效应相加模型(ES)用于化学混合物毒性的加和性检验. 如果混合物效应明显偏离加和参考模型预测效应, 则认为该混合物产生毒性相互作用, 即协同或拮抗. 选择不同的加和参考模型可能得出不同的相互作用结论. ES模型最早广泛应用, 但不能解释由同一化合物构成的所谓虚拟组合现象, 应用已开始受到限制. IA模型被认为适用于具有相异作用模式的化学物构成的混合物, 而CA模型适用于相似作用模式化学物构成的混合物并能合理解释ES模型不能解释的虚拟组合现象, 常常认为是化学混合物毒性预测的标准模型. 然而, 由于CA模型目前没有坚实的理论支持, 也不能直接联系混合物毒性作用机理, 同时在浓度-效应曲线的部分区域存在不能预测的所谓“预测盲区”, 因此, CA模型也只是一个工作模型, 需谨慎使用. 相似文献
982.
The p‐arsanilic acid (p‐ASA), as an aromatic organoarsenic compounds, had received considerable concerns for their potential toxicity and carcinogenic properties. It was essential to detect p‐ASA with a facile method. In this paper, an europium based fluorescent metal–organic framework (MOF) [Eu2(clhex)·2H2O)]·H2O ( BUC‐69 ) was successfully prepared under hydrothermal conditions with 1,2,3,4,5,6‐cyclohexanehexacarboxylic acid (H6clhex) as organic linker. BUC‐69 displayed superior fluorescence capability to achieve selective and sensitive detection toward p‐ASA in water, which presented the first example of a MOF‐based sensor to detect p‐ASA. BUC‐69 showed excellent chemical stability in solutions under pH ranging from 4 to 12, which makes it be a potential sensor both in acidity and alkalinity condition. Significantly, BUC‐69 performed well in fluorescent sensing of p‐ASA at a low concentration (10?6 M) in the simulated wastewater prepared with real lake water, and the results were comparable to the values detected by Inductively Coupled Plasma Optical Emission Spectrometer (ICP‐OES). The corresponding mechanism of fluorescent sensing toward p‐ASA with BUC‐69 was proposed and affirmed. 相似文献
983.
Xingxing Ge Xicheng Liu Zhenzhen Tian Shujiao Chen Xinyu Liu Lihua Guo Peiwei Gong Baoping Ling Xiang‐Ai Yuan Zhe Liu 《应用有机金属化学》2019,33(11)
Four half‐sandwich rutheniumII (RuII) complexes with triphenylamine‐modifed dipyridine frameworks were synthesized and characterized. The cytotoxicity of target complexes toward A549 (lung cancer cells), HeLa (cervical cancer cells) and HepG2 (hepatoma cells) were obtained by the MTT assay, which were superior to cisplatin with the IC50 values changed from 2.4 ± 0.1 μM to 9.2 ± 2.7 μM. Meanwhile, complexes possess the ability of antimetastasis to cancer cells. RuII complexes could be transported by serum albumin, catalyze the conversion of NADH (the reduced state of nicotinamide‐adenine dinucleotide) to NAD+ and induce the accumulation of reactive oxygen species, which confirmed the antineoplastic mechanism of oxidation. RuII complexes could enter A549 cells followed by a non‐energy dependent cellular uptake mechanism, target lysosomes with the Pearson's colocalization coefficient of 0.75, lead to lysosomal damage, disturb the cell cycle (S phase), and eventually induce apoptosis. The results demonstrate that these RuII complexes are potential anticancer agents with dual functions, including metastasis inhibition and lysosomal damage. 相似文献
984.
Cu‐doped Ni‐based metal–organic frameworks (MOFs) nanomaterials fabricated through a one‐pot hydrothermal reaction were characterized, and their performance as supercapacitor electrode materials was further studied for the first time. The results indicated that the doping of foreign metals and the introduction of K3[Fe(CN)6] in the KOH electrolyte significantly improve the performance of the supercapacitor. The results indicated that the Ni2.6Cu0.4 MOFs material shows the highest specific capacitance (1282 F g?1 at 1 A g?1 in mixed 2 M KOH and 0.1 M K3[Fe(CN)6]) and optimal capacitance retention (85.7% after 2000 cycles). This work provides a feasible optimization strategy for the construction of MOFs‐based supercapacitor electrode materials with excellent performance, and also provides a reliable experimental and theoretical basis for practical industrial production. 相似文献
985.
Fang Chen Hongwei Huang Lin Guo Yihe Zhang Tianyi Ma 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10164-10176
Semiconductor photocatalysis as a desirable technology shows great potential in environmental remediation and renewable energy generation, but its efficiency is severely restricted by the rapid recombination of charge carriers in the bulk phase and on the surface of photocatalysts. Polarization has emerged as one of the most effective strategies for addressing the above‐mentioned issues, thus effectively promoting photocatalysis. This review summarizes the recent advances on improvements of photocatalytic activity by polarization‐promoted bulk and surface charge separation. Highlighted is the recent progress in charge separation advanced by different types of polarization, such as macroscopic polarization, piezoelectric polarization, ferroelectric polarization, and surface polarization, and the related mechanisms. Finally, the strategies and challenges for polarization enhancement to further enhance charge separation and photocatalysis are discussed. 相似文献
986.
Shang‐Fu Yuan Cong‐Qiao Xu Jun Li Quan‐Ming Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(18):5967-5970
A golden fullerene Au32 cluster has been synthesized with amido and phosphine ligands as the protecting agents. Single‐crystal X‐ray structural analysis revealed that this gold nanocluster, [Au32(Ph3P)8(dpa)6] (SbF6)2 (Hdpa=2,2′‐dipyridylamine), has a stable pseudo‐Ih Au328+ core with S6 symmetry, which features an Au12@Au20 Keplerate cage co‐protected by Ph3P and dpa ligands. Quantum‐chemical studies were conducted to elucidate the origin of the special stability of this cluster, and suggest that it is electronically stabilized through metal–ligand interactions. 相似文献
987.
XiaoDan Fu XingQun Guo XingWei Li LiDong He YuShe Yang YouXi Chen 《Tetrahedron: Asymmetry》2013,24(13-14):827-832
An asymmetric synthesis of the melatonin receptor agonist Ramelteon 1 has been achieved, which involved a tandem C–H activation–alkylation/Heck reaction and subsequent highly diastereoselective asymmetric Michael addition to generate the corresponding chiral intermediate, which was readily converted into Ramelteon 1 in 19% overall yield in 15 linear steps. 相似文献
988.
Zhenzhen Yang Hao Chen Bo Li Wei Guo Kecheng Jie Yifan Sun De‐en Jiang Ilja Popovs Sheng Dai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):13901-13905
Progress toward the preparation of porous organic polymers (POPs) with task‐specific functionalities has been exceedingly slow—especially where polymers containing low‐oxidation phosphorus in the structure are concerned. A two‐step topotactic pathway for the preparation of phosphabenzene‐based POPs (Phos‐POPs) under metal‐free conditions is reported, without the use of unstable phosphorus‐based monomers. The synthetic route allows additional functionalities to be introduced into the porous polymer framework with ease. As an example, partially fluorinated Phos‐POPs (F‐Phos‐POPs) were obtained with a surface area of up to 591 m2 g?1. After coordination with Ru species, a Ru/F‐Phos‐POPs catalyst exhibited high catalytic efficiency in the formylation of amines (turnover frequency up to 204 h?1) using a CO2/H2 mixture, in comparison with the non‐fluorinated analogue (43 h?1) and a Au/TiO2 heterogeneous catalysts reported previously (<44 h?1). This work describes a practical method for synthesis of porous organic phosphorus‐based polymers with applications in transition‐metal‐based heterogeneous catalysis. 相似文献
989.
Wei Wang Rui Sun Jing Guo Jie Guo Jie Min 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14698-14703
A new balanced donor–acceptor molecule, namely, benzodithiophene (BDT)‐rhodanine‐[6,6]‐phenyl‐C71 butyric acid methyl ester (Rh‐PC71BM) comprising two covalently linked blocks, a p‐type oligothiophene‐containing BDT‐based moiety and an n‐type PC71BM unit was designed and synthesized. The single‐component organic solar cell (SCOSC) fabricated from Rh‐PC71BM molecules showed a power conversion efficiency (PCE) of 3.22 % with an open‐circuit voltage (Voc) of 0.98 V. These results rank are among the highest values for SCOSCs based on a monomolecular material. In particular, the one‐molecule Rh‐PC71BM device exhibits excellent thermal stability compared to reference Rh‐OH:PC71BM device. The success of our monomolecular strategy can provide a new way to develop high‐performance SCOSCs. 相似文献
990.
Hydrogenation of acetophenone over nano‐Cu/SiO2 catalysts was investigated. The catalysts, prepared by a liquid precipitation method using various precipitating agents, were characterized using low‐temperature nitrogen adsorption, X‐ray diffraction, temperature‐programmed desorption of ammonia, hydrogen temperature‐programmed reduction, transmission electron microscopy and X‐ray photoelectron spectroscopy. It was found that the catalysts prepared by a homogeneous precipitation method had better activity and stability than those prepared by a co‐precipitation method. The catalyst prepared using urea as precipitating agent had well‐dispersed copper species, high surface area and abundant pore structure. The catalytic performance and mechanism of the Cu/SiO2 catalysts were further studied. It was found that the activity and stability of the catalysts could be improved by adjusting the proportion of Cu+/(Cu+ + Cu0). The sample prepared using urea as precipitating agent presented higher activity and selectivity. Also, the catalyst prepared using urea maintained a high catalytic performance while being continuously used for 150 h under the optimal reaction conditions. 相似文献