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761.
In this paper, we consider a boundary control problem governed by a class of non-well-posed elliptic equations with nonlinear
Neumann boundary conditions. First, the existence of optimal pairs is proved. Then by considering a well-posed penalization
problem and taking limit in the optimality system for penalization problem, we obtain the necessary optimality conditions
for optimal pairs of initial control problem. 相似文献
762.
Weiling Luan Hongwei Yang Zhen Wan Binxia Yuan Xinhai Yu Shan-tung Tu 《Journal of nanoparticle research》2012,14(3):762
MPA stabilized CdSe/ZnS NCs was applied as a fluorescent probe for the sensitive detection of Pb2+ in water. The microreaction was demonstrated as a facile method for the reproducible synthesis of CdSe/ZnS NCs with a high
quantum yield. The good stability of CdSe/ZnS NCs was proved by the significant maintaining of photoluminescent (PL) after
the ligand exchange with MPA, and was further demonstrated by the excellent PL property in water solution with various pH
values. The cation exchange of Zn with Pb led to the linear quenching of PL with the concentration of Pb2+, which provided as an opportunity to apply MPA stabilized CdSe/ZnS NCs as fluorescent probes for Pb2+. A facile method by adjustment of QDs concentration was demonstrated as a suitable way to approach different detection limits.
The detection limits of 0.03 and 3.3 μM were achieved by setting QDs solutions with the absorbance of the first exciton peak
as 0.05 and 0.15, respectively. 相似文献
763.
Yangdong Hou Zhang Zhang Xinyu Sun Zheng Yang Yu-Xin Luan Prof. Dr. Pingping Tang 《Angewandte Chemie (International ed. in English)》2023,62(18):e202218919
Due to the strong electron-withdrawing nature and high lipophilicity of trifluoromethoxy group (OCF3), methods for introducing OCF3 into organic molecules are in high demand. However, the research area of direct enantioselective trifluoromethoxylation is still in the embryonic stage, with limited enantioselectivity and/or reaction types. Here, we describe the first copper-catalyzed enantioselective trifluoromethoxylation of propargyl sulfonates using trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxy source in up to 96 % ee. 相似文献
764.
Dr. Yunxiang Li Zhihao Pei Dr. Deyan Luan Prof. Dr. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2023,62(19):e202302128
Gas-liquid-solid triple-phase interfaces (TPI) are essential for promoting electrochemical CO2 reduction, but it remains challenging to maximize their efficiency while integrating other desirable properties conducive to electrocatalysis. Herein, we report the elaborate design and fabrication of a superhydrophobic, conductive, and hierarchical wire membrane in which core–shell CuO nanospheres, carbon nanotubes (CNT), and polytetrafluoroethylene (PTFE) are integrated into a wire structure (designated as CuO/F/C(w); F, PTFE; C, CNT; w, wire) to maximize their respective functions. The realized architecture allows almost all CuO nanospheres to be exposed with effective TPI and good contact to conductive CNT, thus increasing the local CO2 concentration on the CuO surface and enabling fast electron/mass transfer. As a result, the CuO/F/C(w) membrane attains a Faradaic efficiency of 56.8 % and a partial current density of 68.9 mA cm−2 for multicarbon products at −1.4 V (versus the reversible hydrogen electrode) in the H-type cell, far exceeding 10.1 % and 13.4 mA cm−2 for bare CuO. 相似文献
765.
Dongqing Wang Yuehui Liu Dr. Nelson Rowell Dr. Shanling Wang Dr. Chunchun Zhang Dr. Meng Zhang Dr. Chaoran Luan Prof. Kui Yu 《Angewandte Chemie (International ed. in English)》2023,62(28):e202304329
Colloidal semiconductor II–VI metal chalcogenide (ME) magic-size clusters (MSCs) exhibit either an optical absorption singlet or doublet. In the latter case, a sharp photoluminescence (PL) signal is observed. Whether the PL-inactive MSCs transform to the PL-active ones is unknown. We show that PL-inactive CdS MSC-322 transforms to PL-active CdS MSC-328 and MSC-373 in the presence of acetic acid (HOAc). MSC-322 displays a sharp absorption at ≈322 nm, whereas MSC-328 and MSC-373 both have broad absorptions respectively around 328 and 373 nm. In a reaction of cadmium myristate and S powder in 1-octadecene, MSC-322 develops; with HOAc, MSC-328 and MSC-373 are present. We propose that the MSCs evolve from their relatively transparent precursor compounds (PCs). The PC-322 to PC-328 quasi-isomerization involves monomer substitution, while monomer addition occurs for the PC-328 to PC-373 transformation. Our findings suggest that S dominates the precursor self-assembly quantitatively, and ligand-bonded Cd mainly controls MSC optical properties. 相似文献
766.
Wu Yusen Pan Jisheng Wang Hao Shen Zhuoshan Luan Tianxin Yan Qiusheng 《Journal of Solid State Electrochemistry》2023,27(8):2163-2176
Journal of Solid State Electrochemistry - A magnetorheological electro-Fenton composite polishing technology was proposed that enables chemical and mechanical “double enhancement” of... 相似文献
767.
Dr. Zhuo Zhu Dr. Yinxiang Zeng Zhihao Pei Dr. Deyan Luan Prof. Xin Wang Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2023,62(31):e202305828
Lithium-sulfur (Li−S) batteries are considered as promising candidates for next-generation energy storage systems in view of the high theoretical energy density and low cost of sulfur resources. The suppression of polysulfide diffusion and promotion of redox kinetics are the main challenges for Li−S batteries. Herein, we design and prepare a novel type of ZnCo-based bimetallic metal–organic framework nanoboxes (ZnCo-MOF NBs) to serve as a functional sulfur host for Li−S batteries. The hollow architecture of ZnCo-MOF NBs can ensure fast charge transfer, improved sulfur utilization, and effective confinement of lithium polysulfides (LiPSs). The atomically dispersed Co−O4 sites in ZnCo-MOF NBs can firmly capture LiPSs and electrocatalytically accelerate their conversion kinetics. Benefiting from the multiple structural advantages, the ZnCo-MOF/S cathode shows high reversible capacity, impressive rate capability, and prolonged cycling performance for 300 cycles. 相似文献
768.
Dr. Fu-Li Wang Dr. Lin Liu Dr. Chang-Jiang Yang Cheng Luan Dr. Jing Yang Dr. Ji-Jun Chen Dr. Qiang-Shuai Gu Dr. Zhong-Liang Li Prof. Dr. Xin-Yuan Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202214709
The copper-catalyzed enantioconvergent radical C(sp3)−C(sp2) cross-coupling of tertiary α-bromo-β-lactams with organoboronate esters could provide the synthetically valuable α-quaternary β-lactams. The challenge arises mainly from the construction of sterically congested quaternary stereocenters between the tertiary alkyl radicals and chiral copper(II) species. Herein, we describe our success in achieving such transformations through the utilization of a copper/hemilabile N,N,N-ligand catalyst to forge the sterically congested chiral C(sp3)−C(sp2) bond via a single-electron reduction/transmetalation/bond formation catalytic cycle. The synthetic potential of this approach is shown in the straightforward conversion of the corresponding products into many valuable building blocks. We hope that the developed catalytic cycle would open up new vistas for more enantioconvergent cross-coupling reactions. 相似文献
769.
Chenglong Luan Johanna Angona Arjun Bala Krishnan Manuel Corva Pouya Hosseini Markus Heidelmann Ulrich Hagemann Emmanuel Batsa Tetteh Wolfgang Schuhmann Kristina Tschulik Tong Li 《Angewandte Chemie (International ed. in English)》2023,62(28):e202305982
The role of β-CoOOH crystallographic orientations in catalytic activity for the oxygen evolution reaction (OER) remains elusive. We combine correlative electron backscatter diffraction/scanning electrochemical cell microscopy with X-ray photoelectron spectroscopy, transmission electron microscopy, and atom probe tomography to establish the structure–activity relationships of various faceted β-CoOOH formed on a Co microelectrode under OER conditions. We reveal that ≈6 nm β-CoOOH(01 0), grown on [ 0]-oriented Co, exhibits higher OER activity than ≈3 nm β-CoOOH(10 3) or ≈6 nm β-CoOOH(0006) formed on [02 - and [0001]-oriented Co, respectively. This arises from higher amounts of incorporated hydroxyl ions and more easily reducible CoIII−O sites present in β-CoOOH(01 0) than those in the latter two oxyhydroxide facets. Our correlative multimodal approach shows great promise in linking local activity with atomic-scale details of structure, thickness and composition of active species, which opens opportunities to design pre-catalysts with preferred defects that promote the formation of the most active OER species. 相似文献