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direct observation of oxygen vacancy formation and migration over ceria surface by in situ environmental transmission electron microscopy

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Journal of Rare Earths 2024年第4期42卷 676-682页

作者： Dawei Pang Wei Li Ningqiang Zhang Hong He Shengcheng Mao Yanhui Chen Liwei Cao Chong Li Ang Li Xiaodong Han Beijing Key Laboratory of Solid Microstructure and Properties Department of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Beijing Key Laboratory for Green Catalysis and Separation The Faculty of Environment and LifeBeijing University of TechnologyBeijing10124China International Joint Research Laboratory for Quantum Functional Materials of Henan School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou450001China

The extremely high structural tolerance of ceria to oxygen vacancies(Ov)has made it a desirable catalytic material for the hydrocarbon oxidation to chemicals and pharmaceuticals and the reduction of gaseous *** is proposed that the formation and diffusion of Ov originate from its outstanding reduction ***,the formation and diffusion process of Ov over the surface of ceria at the atomic level is still ***,the structural and valence evolution of CeO_(2)(111)surfaces in reductive,oxidative and vacuum environments from room temperature up to 700℃was studied with in situ aberration-corrected environmental transmission electron microscopy(ETEM)*** is found to form under a high vacuum at elevated temperatures;however,the surface can recover to the initial state through the adsorption of oxygen atoms in an oxygen-contained ***,in hydrogen environment,the step-CeO_(2)(111)surface is not stable at elevated temperatures;thus,the steps tend to be eliminated with increasing *** with first-principles density function calculations(DFT),it is proposed that O-terminated surfaces would develop in a hypoxic environment due to the dynamic diffusion of Ov from the outer surface to the ***,in a reductive environment,H2 facilitates the formation and diffusion of Ov while Ce-terminated surfaces *** results reveal dynamic atomic-scale interplay between the nanoceria surface and gas,thereby providing fundamental insights into the Ov-dependent reaction of nano-CeO_(2) during catalytic processes.

关键词： Ceria direct observation In situ ETEM Oxygen vacancy Density function calculations Rareearths

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direct observation of spreading precursor liquids in a corner

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National Science Review 2023年第7期10卷 196-202页

作者： Weining Miao Shihao Tian Quanzi Yuan Ye Tian Lei Jiang Key Laboratory of Bioinspired Smart Interfacial Science Technical Institute of Physics and Chemistry Chinese Academy of Sciences School of Future Technology University of Chinese Academy of Sciences State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences

Precursor liquid is a nanoscale liquid creeping ahead of the macroscopic edge of spreading liquids,whose behaviors tightly correlate with the three-phase reaction efficiency and patterning ***,the important spatial-temporal characteristic of the precursor liquid still remains obscure because its real-time spreading process has not been directly ***,we report that the spreading ionic liquid precursors in a silicon corner can be directly captured on video using in situ scanning electron *** situ spreading videos show that the precursor liquid spreads linearly over time(ΔL～ΔT) rather than obeying the classic Lucas-Washburn law(l～t1/2) and possesses a characteristic width of ～250-310 *** analyses and molecular dynamics simulations demonstrate that the unique behaviors of precursor liquids originate from the competing effect of van der Waals force and surface *** findings provide avenues for directly observing liquid/solid interfacial phenomena on a microscopic level.

关键词： precursor liquid spreading spatial–temporal characteristic direct observation corner ionic liquids

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Host selection by the autoparasitoid Encarsia pergandiella on primary （Bemisia tabacl） and secondary （Eretmocerus mundus） hosts

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Insect Science 2015年第6期22卷 793-802页

作者： Yi-Bo Zhang Cristina Castane Rosa Gabarra Ramon Albajes Fang-Hao Wan Sustainable Plant Protection Department Institute for Research and Technology in Agriculture (IRTA) 08348 Cabrils Barcelona Agrotecnio Center Universitat de Lleida Rovira Roure 191 25198 Lleida Spain State Key Laboratory for Biology of Plant Diseases and Insect Pests Institute of Plant Protection Chinese Academy of Agricultural Sciences Beijing 100193 China.

In autoparasitoids, females are generally primary endoparasitoids of Hemiptera, while males are hyperparasitoids developing in or on conspecific females or other primary parasitoids. Female-host acceptance can be influenced by extrinsic and/or intrinsic factors. In this paper, we are concerned with intrinsic factors such as nutritional status, mating status, etc. We observed the behavior of Encarsia pergandiella Howard （Hymenoptera： Aphelinidae） females when parasitizing primary （3rd instar larvae ofBemisia tabaci Gen- nadius [Homoptera： Aleyrodidae]） and secondary hosts （3rd instar larvae and pupae of Eretmocerus rnundus Mercet [Hymenoptera： Aphelinidae]） for a period of 1 h. Females had different reproductive （virgin or mated younger） and physiological （fed elder or mated elder） status. Virgin females killed a large number of secondary hosts while investing a long time per host. However, they did not feed upon them. Mated females killed a lower number of secondary hosts and host feeding was observed in both consuming primary and secondary hosts. It was common to observe host examining females of all physiological statues tested repeatedly stinging the same hosts when parasitizing, killing or rejecting them. Fed elder females parasitized more B. tabaci larvae than E. mundus larvae or pupae, while investing less time on the primary host than on the secondary host. They also para- sitized more B. tabaci larvae than mated elder females, while investing less time per host. The access of females to honey allowed them to lay more eggs.

关键词： direct observation female physiological status Heteronomous hyperpara-sitoids host acceptance behavior

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Cavitation field from a horn—A new model

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Science China(Physics,Mechanics & Astronomy) 2011年第1期54卷 74-78页

作者： YING ChongFu BAI LiXin LI Chao DENG JingJun Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China

The cavitation field from a horn-type transducer is experimentally probed by the optical *** on these observations,we propose a model of the field which hypothesizes that most violent caviation bubbles originate from the vibrating surface and there-from fast drift to the near liquid *** bubbles are chiefly responsible for the practical applications of cavitation for a large power input to the *** migration they become *** bubbles are also produced in the liquid region by the acoustic wave directly emitted by the transducer,but these bubbles are weak due to the shielding effect of the bubbles clinging to the transducer vibrating ***,only weak cavitation bubbles exist in the far liquid region.

关键词： cavitation field horn-type transducer direct observation new model

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Mold Filling and Prevention of Gas Entrapment in High-pressure Die-casting

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Journal of Materials Science & Technology 2008年第1期24卷 139-140页

作者： Itsuo Ohnaka Akira Sugiyama Takashi Ikeda Hideyuki Yasuda Department of Entrepreneur Engineering/ieSolution Osaka Sangyo University Daito-shi 574-8530Japan Trois Corp. Japan Osaka University Japan

This paper presents some results of direct observation of mold filling in a specially designed die-casting by X-ray diffraction, including comparison with numerical simulation. Based on such work the authors discuss h... 详细信息

关键词： direct observation Mold filling High-pressure die-casting Computer simulation Gas entrapment

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Characterization and Monitoring of Transient Enamine Radical Intermediates in Photoredox/Chiral Primary Amine Synergistic Catalytic Cycle

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CCS Chemistry 2024年第10期6卷 2420-2426页

作者： Shixue Zhang Liang Cheng Jian-Qing Qi Zongbin Jia Long Zhang Lei Jiao Xingwei Guo Sanzhong Luo Center of Basic Molecular Science(CBMS) Department of ChemistryTsinghua UniversityBeijing 100084

Enamine-derived radicals are crucial intermediates in singly occupied molecular orbital(SOMO)***,observing them directly is elusive and remains a long-standing ***,an advanced time-resolved electron paramagnetic resonance technique was employed to characterize and monitor the key intermediates in photoredox transformations by primary aminocatalysis on a microsecond *** transient enamine radical cation,generated by single electron transfer(SET),and the deprotonated form ofα-imino radical intermediates were directly observed for the first time,both spectroscopically and *** reactions with styrene,enamine radical cation was found to be faster thanα-imino radical by one order of *** revealed the subtle role of deprotonation associated with secondary enamine radical cation in the photoredox transformations by primary aminocatalysis.

关键词： aminocatalysis radical chemistry electron paramagnetic resonance direct observation time-resolved technique

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社会学民族志的力量：重返早期社会研究的田野工作

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社会学 2019年第5期

作者：田耕

自20世纪70年代以来，社会学民族志在田野工作和叙事复兴中与传统人文学汇聚，显著扩展了自己的学科边界。但是，这种扩展并没有解决社会学民族志在深度的经验发生和强烈的理论诉求之间遭遇的紧张。对于这种紧张，本文主张再访早期社会... 详细信息

自20世纪70年代以来，社会学民族志在田野工作和叙事复兴中与传统人文学汇聚，显著扩展了自己的学科边界。但是，这种扩展并没有解决社会学民族志在深度的经验发生和强烈的理论诉求之间遭遇的紧张。对于这种紧张，本文主张再访早期社会研究的田野，即19世纪末期到一战之前的若干典型研究，从中反思早期社会学田野工作是如何在“直接经验”的倾向中完成类型化，以及如何在这个经验感获得的同时改变对社会世界的道德想象。早期社会学的田野工作的力量之一不在于以规范的诉求压制经验感，而是以独特的情感结构连接经验的观察和道德理想的重生。由此，我们不仅需要反思诸如社会调查到社区研究这样的简单思路，更要重新理解理论史上所谓的“进步主义式”的道德本身。这一工作对重新认识早期社会研究和今天的社会学民族志都具有意义上的准备。

关键词：社会学民族志田野工作情感结构直接观察进步主义道德 sociological ethnography fieldwork structure of feeling direct observation progressive morality

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