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排序方式: 共有366条查询结果,搜索用时 15 毫秒
361.
Tan Xiaobo Yan Xin Yi Tao He Kai Shao Zhengzheng Zhou Kaikai Gao Guilong Wang Tao Zhang Jun Zhuang Zhaowen 《光子学报》2022,(2):I0002-I0002
The traditional ultrafast electric vacuum devices are usually based on the mechanism of photoelectric conversion, and their performance is restricted by factors such as material response and space-charge effect. It is difficult for the devices like microchannel plate framing cameras, Dilation X-ray Imager (DIXI) , streak cameras to achieve high temporal resolution (100 fs similar to 1 ps) and spatial resolution (similar to mu m) two-dimensional imaging. Ultrafast imaging technology based on photorefractive effect is a new ultrafast diagnostic technology, which has the advantages of high spatiotemporal resolution, all-optical, all and anti radiation. The nonequilibrium carrier lifetime of low temperature grown AlGaAs (LT-AlGaAs) can reach ps-level. The Ultrafast Response Chip (URC) made of LT-AlGaAs has the characteristics of high temporal resolution, meanwhile, good spatial performance is the other key factor for its application. In this paper, the spatial performance of LT-AlGaAs URC is experimentally studied using X-ray, generated by high-energy nanosecond pulsed laser-produced plasma, as the signal. The results show that the URC has the ability of high spatial resolution and large-scale imaging in the X-ray energy dynamic range of 120: 1. The optimal spatial resolution is >= 35 1p/mm (R) MTF = 0.1, and the imaging frame can reach 6.7 mm x 6.7 mm. The results further verify the feasibility of ultrafast diagnostic technology based on photorefractive materials. In the future, LT-AIGaAs URC will be combined with ultrafast framing technologies such as dispersion framing and polarization chirp framing to realize multi-frames and high spatiotemporal resolution two-dimensional imaging. 相似文献
362.
Louis Godeffroy Dr. Paolo Ciocci Dr. Nathaly Ortiz Peña Dr. Damien Alloyeau Dr. Jean-Marc Noël Dr. Jean-François Lemineur Dr. Frédéric Kanoufi 《Angewandte Chemie (International ed. in English)》2023,62(29):e202304950
This work proposes a novel method for measuring the intrinsic activity of single metal-based nanoparticles towards water reduction in neutral media at industrially relevant current densities. Instead of using gas nanobubbles as proxy, the method uses optical microscopy to track the local footprint of the reaction through the precipitation of metal hydroxide, which is associated to the local pH increase during electrocatalysis. The results show the electrocatalytic activities of different types of metal nanoparticles and bifunctionnal core-shell nanostructures made of Ni and Pt, and demonstrate the importance of metal hydroxide nano-shells in enhancing electrocatalysis. This method should be generalizable to any electrocatalytic reaction involving pH changes such as nitrate or CO2 reduction. 相似文献
363.
Le Yu Syed Ali Abbas Abedi Dr. Jeongjin Lee Yunjie Xu Dr. Subin Son Prof. Weijie Chi Prof. Mingle Li Prof. Xiaogang Liu Prof. Jae Hyung Park Prof. Jong Seung Kim 《Angewandte Chemie (International ed. in English)》2023,62(32):e202307797
Photoacoustic imaging (PAI), a state-of-the-art noninvasive in vivo imaging technique, has been widely used in clinical disease diagnosis. However, the design of high-performance PAI agents with three key characteristics, i.e., near-infrared (NIR) absorption (λabs>800 nm), intense PA signals, and excellent photostability, remains a challenging goal. Herein, we present a facile but effective approach for engineering PAI agents by amplifying intramolecular low-frequency vibrations and enhancing the push-pull effect. As a demonstration of this blended approach, we constructed a PAI agent ( BDP1-NEt2 ) based on the boron-dipyrromethene (BODIPY) scaffold. Compared with indocyanine green (ICG, an FDA-approved organic dye widely utilized in PAI studies; λabs=788 nm), BDP1-NEt2 exhibited a UV/Vis-NIR spectrum peaked at 825 nm, superior in vivo PA signal intensity and outstanding stability to offer improved tumor diagnostics. We believe this work provides a promising strategy to develop the next generation of PAI agents. 相似文献
364.
Prof. Xuejiao Zhang Dr. Ievgen S. Donskyi Dr. Weihao Tang Shuo Deng Daxu Liu Prof. Siyu Zhang Prof. Qing Zhao Prof. Baoshan Xing 《Angewandte Chemie (International ed. in English)》2023,62(6):e202213336
The remarkable progress of applied black phosphorus nanomaterials (BPNMs) is attributed to BP's outstanding properties. Due to its potential for applications, environmental release and subsequent human exposure are virtually inevitable. Therefore, how BPNMs impact biological systems and human health needs to be considered. In this comprehensive Minireview, the most recent advancements in understanding the mechanisms and regulation factors of BPNMs’ endogenous toxicity to mammalian systems are presented. These achievements lay the groundwork for an understanding of its biological effects, aimed towards establishing regulatory principles to minimize the adverse health impacts. 相似文献
365.
Hannah F. Mathews Maria I. Pieper Dr. Se-Hyeong Jung Prof. Andrij Pich 《Angewandte Chemie (International ed. in English)》2023,62(36):e202304908
In pH-responsive drug carriers, the distribution of charges has been proven to affect delivery efficiency but is difficult to control and verify. Herein, we fabricate polyampholyte nanogel-in-microgel colloids (NiM−C) and show that the arrangement of the nanogels (NG) can easily be manipulated by adapting synthesis conditions. Positively and negatively charged pH-responsive NG are synthesized by precipitation polymerization and labelled with different fluorescent dyes. The obtained NG are integrated into microgel (MG) networks by subsequent inverse emulsion polymerization in droplet-based microfluidics. By confocal laser scanning microscopy (CLSM), we verify that depending on NG concentration, pH value and ionic strength, NiM−C with different NG arrangements are obtained, including Janus-like phase-separation of NG, statistical distribution of NG, and core–shell arrangements. Our approach is a major step towards uptake and release of oppositely charged (drug) molecules. 相似文献
366.
Sicong Wang Tao Ding Tong Liu Yanan Zhu Zhinan Tao Beibei Pang Xiaokang Liu Qiquan Luo Mei Sun Hongting Sheng Prof. Manzhou Zhu Prof. Tao Yao 《Angewandte Chemie (International ed. in English)》2023,62(16):e202303150
The transformation from metal nanocluster catalysts to metal single-atom catalysts is an important procedure in the rational design of atomically dispersed metal catalysts (ADCs). However, the conversion methods often involve high annealing temperature as well as reducing atmosphere. Herein, we reported a continuous and convenient approach to transfer Pd nanocluster into Pd single-atom in a ligand assisted annealing procedure, by which means we reduced its activating temperature low to 400 °C. Using ex-situ microscopy and spectroscopy, we comprehensively monitored the structural evolution of Pd species though the whole atomization process. Theoretical calculation revealed that the structural instability caused by remaining Cl ligands was the main reason for this low-temperature transformation. The present atomization strategy and mechanistic knowledge for the conversion from cluster to atomic dispersion provides guidelines for the rational design of ADCs. 相似文献