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991.
A simple aptamer molecular beacon assay for rapid detection of aflatoxin B1 (AFB1) was achieved. AFB1-binding induced formation of a hairpin structure and closeness of fluorophore label and quencher probe, causing fluorescence decrease. 相似文献
992.
Ya Chen Yixiao Pan Yan‐Mei He Qing‐Hua Fan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):16987-16990
A highly enantioselective iridium‐ or ruthenium‐catalyzed intermolecular reductive amination/asymmetric hydrogenation relay with 2‐quinoline aldehydes and aromatic amines has been developed. A broad range of sterically tunable chiral N,N′‐diaryl vicinal diamines were obtained in high yields (up to 95 %) with excellent enantioselectivity (up to >99 % ee). The resulting chiral diamines could be readily transformed into sterically hindered chiral N‐heterocyclic carbene (NHC) precursors, which are otherwise difficult to access. The usefulness of this synthetic approach was further demonstrated by the successful application of one of the chiral vicinal diamines and chiral NHC ligands in a transition‐metal‐catalyzed asymmetric Suzuki–Miyaura cross‐coupling reaction and asymmetric ring‐opening cross‐metathesis, respectively. 相似文献
993.
994.
Xue‐Qiang Zhang Tao Li Bo‐Quan Li Rui Zhang Peng Shi Chong Yan Jia‐Qi Huang Qiang Zhang 《Angewandte Chemie (International ed. in English)》2020,59(8):3252-3257
High‐energy‐density Li metal batteries suffer from a short lifespan under practical conditions, such as limited lithium, high loading cathode, and lean electrolytes, owing to the absence of appropriate solid electrolyte interphase (SEI). Herein, a sustainable SEI was designed rationally by combining fluorinated co‐solvents with sustained‐release additives for practical challenges. The intrinsic uniformity of SEI and the constant supplements of building blocks of SEI jointly afford to sustainable SEI. Specific spatial distributions and abundant heterogeneous grain boundaries of LiF, LiNxOy, and Li2O effectively regulate uniformity of Li deposition. In a Li metal battery with an ultrathin Li anode (33 μm), a high‐loading LiNi0.5Co0.2Mn0.3O2 cathode (4.4 mAh cm?2), and lean electrolytes (6.1 g Ah?1), 83 % of initial capacity retains after 150 cycles. A pouch cell (3.5 Ah) demonstrated a specific energy of 340 Wh kg?1 for 60 cycles with lean electrolytes (2.3 g Ah?1). 相似文献
995.
A Diffusion‐‐Reaction Competition Mechanism to Tailor Lithium Deposition for Lithium‐Metal Batteries
Xiao‐Ru Chen Yu‐Xing Yao Chong Yan Rui Zhang Xin‐Bing Cheng Qiang Zhang 《Angewandte Chemie (International ed. in English)》2020,59(20):7743-7747
Lithium metal is recognized as one of the most promising anode materials owing to its ultrahigh theoretical specific capacity and low electrochemical potential. Nonetheless, dendritic Li growth has dramatically hindered the practical applications of Li metal anodes. Realizing spherical Li deposition is an effective approach to avoid Li dendrite growth, but the mechanism of spherical deposition is unknown. Herein, a diffusion‐reaction competition mechanism is proposed to reveal the rationale of different Li deposition morphologies. By controlling the rate‐determining step (diffusion or reaction) of Li deposition, various Li deposition scenarios are realized, in which the diffusion‐controlled process tends to lead to dendritic Li deposition while the reaction‐controlled process leads to spherical Li deposition. This study sheds fresh light on the dendrite‐free Li metal anode and guides to achieve safe batteries to benefit future wireless and fossil‐fuel‐free world. 相似文献
996.
Xiang Chen Yun‐Ke Bai Chen‐Zi Zhao Xin Shen Qiang Zhang 《Angewandte Chemie (International ed. in English)》2020,59(28):11192-11195
Lithium bonds are analogous to hydrogen bonds and are therefore expected to exhibit similar characteristics and functions. Additionally, the metallic nature and large atomic radius of Li bestow the Li bond with special features. As one of the most important applications of the element, Li batteries afford emerging opportunities for the exploration of Li bond chemistry. Herein, the historical development and concept of the Li bond are reviewed, in addition to the application of Li bonds in Li batteries. In this way, a comprehensive understanding of the Li bond in Li batteries and an outlook on its future developments is presented. 相似文献
997.
Hongyu Zhang Changlong Hao Aihua Qu Maozhong Sun Liguang Xu Chuanlai Xu Hua Kuang 《Angewandte Chemie (International ed. in English)》2020,59(18):7131-7138
The accumulation and deposition of β‐amyloid (Aβ) plaques in the brain is considered a potential pathogenic mechanism underlying Alzheimer's disease (AD). Chiral l/d ‐FexCuySe nanoparticles (NPs) were fabricated that interfer with the self‐assembly of Aβ42 monomers and trigger the Aβ42 fibrils in dense structures to become looser monomers under 808 nm near‐infrared (NIR) illumination. d ‐FexCuySe NPs have a much higher affinity for Aβ42 fibrils than l ‐FexCuySe NPs and chiral Cu2?xSe NPs. The chiral FexCuySe NPs also generate more reactive oxygen species (ROS) than chiral Cu2?xSe NPs under NIR‐light irradiation. In living MN9D cells, d ‐NPs attenuate the adhesion of Aβ42 to membranes and neuron loss after NIR treatment within 10 min without the photothermal effect. In‐vivo experiments showed that d ‐FexCuySe NPs provide an efficient protection against neuronal damage induced by the deposition of Aβ42 and alleviate symptoms in a mouse model of AD, leading to the recovery of cognitive competence. 相似文献
998.
双氧水(H2O2)是一种重要的绿色氧化剂,广泛应用于纺织、医疗、废水处理、军事等重要领域.目前, H2O2的工业生产以蒽醌法为主,该法设备投资大、运行成本高,同时工艺涉及大量的有机溶液,活性中间体蒽醌也会发生缓慢降解,产生有毒副产物.与蒽醌法相比,通过负载型贵金属催化剂催化H2与O2反应直接合成H2O2,过程绿色环保且生产工艺简单,引起了各界广泛关注.然而,从热力学上分析, H2和O2更容易反应生成H2O, H2O2只是该反应的中间产物,会继续发生加氢和直接分解反应生成H2O,导致H2和O2的低效利用,开发高H2O2选择性且高反应效率的催化剂已成为氢氧直接合成H2O2研究的重点与难点.目前大部分研究策略旨在通过调控或影响反应中心结构、价态来抑制H2O2的副反应,进而提升H2O2的选择性和反应效率;尽管已取得了良好的进展,但仍需发展新的调控策略来满足工业应用的要求.本课题组前期研究表明,促使H2O2从催化剂上脱附可以有效地提升H2O2的选择性和产率.相比于针对反应中心的调控,不稳定的H2O2从催化剂上快速脱附同样起到抑制H2O2参与副反应的作用.为此,本文提出一种炭量可控的非均一界面改性方法,以常规的Pd/TiO2作为研究对象,借助各种结构表征,发现炭物种在TiO2表面呈非均一分散状态,而且改性对于催化剂的几何结构影响较小;另外,催化剂表面的疏水性会随着碳含量的增加而增加,导致其与H2O2间的吸附能相应变小.反应结果显示,表面非均一的炭化改性技术可以显著提升Pd/TiO2催化剂的H2O2选择性和产率.通过构效关系分析,可知这种改性技术可以保持Pd颗粒与TiO2间相互作用的同时,还可以促进H2O2的快速脱附,进而提升改性Pd/TiO2催化剂的H2O2直接合成效率.该改性方法简单、易控,可拓展应用到其他类型催化剂的H2O2直接合成性能调控与改进. 相似文献
999.
1000.
Corrosion inhibition and performance evaluation on 2,5‐diaryl‐1,3,4‐thiadiazole and its derivatives 下载免费PDF全文
Xiaona Pan Lin Liu Qiang Zhang Jianhua Qian 《Surface and interface analysis : SIA》2016,48(6):373-382
Using electrochemical impedance spectroscopy (EIS) and scanning electronic microscopy (SEM), this paper evaluated the inhibition effect of four 2,5‐diaryl‐1,3,4‐thiadiazole and its derivatives named 2,5‐diphenly‐1,3,4‐thiadiazole (DPTD), 2,5‐di(2‐hydroxyphenly)‐1,3,4‐thiadiazole (2‐DHPTD), 2,5‐di(3‐hydroxyphenly)‐1,3,4‐thiadiazole (3‐DHPTD), and 2,5‐di(4‐hydroxyphenly)‐1,3,4‐thiadiazole (4‐DHPTD) on silver strip corrosion in 50 mg/l sulfur–ethanol solution under room temperature. The experiments indicated that the inhibition efficiency increased with increasing inhibitor concentrations, and the increasing order was (4‐DHPDT) > (3‐DHPDT) > (2‐DHPDT) > (DPDT). Quantum chemical calculation was applied to correlate inhibition performances with their electronic structural parameters of thiadiazole derivatives. Molecular dynamics simulations (DFT) were used to optimize the equilibrium configurations of the inhibitor molecules on the silver surface and to investigate the molecular structure effect on the corrosion inhibition efficiency. The efficiency order of the investigated inhibitors, which was obtained by experimental results, was verified by theoretical calculations. Contact angle (CA) analysis was also carried out, and finally confirmed the existence of the adsorbed film which prevailed in addition of thiadiazole derivatives. CA analysis indicated that the film of n‐DHPTD (n = 2,3,4) was hydrophilic, owing to two hydroxyl groups in their molecular. The adsorption of these compounds onto silver strip from 50 mg/l S‐ethanol system obeys Langmuir adsorption isotherm, and it belongs to mixed‐type adsorption mainly dominated by chemisorption. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献