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High Temperature Iron Ethylene Polymerization Catalysts Bearing N,N,N'-2-(1-(2,4-Dibenzhydryl-6-fluorophenylimino)ethyl)-6-(1-(arylphenylimino)ethyl)pyridines

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chinese Journal of Polymer science 2024年第2期42卷 188-201,I0007页

作者： Chantsalnyam Bariashir Qiu-Yue Zhang Bayasgalan Ulambayar Gregory A.solan Tong-Ling Liang Wen-Hua sun Institute of Chemistry and Chemical Technology Mongolian Academy of SciencesUlaanbaatar13330Mongolia Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular science Institute of ChemistryChinese Academy of SciencesBeijing100190China Department of Chemistry University of LeicesterUniversity RoadLeicesterLE17RHUK state Key Laboratory for Oxo synthesis and selective Oxidation Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

The N,N,N'-ferrous chloride complexes,[2-{CMeN(2,4-(CHPh)_(2)-6-FC_(6)H_(2))}-6-(CMeNAr)C_(5)H_(3)N]FeCl_(2)(Ar=2,6-Me_(2)C_(6)H_(3) Fe1,2,6-Et_(2)C_(6)H_(3)Fe2,2,6-^(i)Pr_(2)C_(6)H_(3) Fe3,2,4,6-Me_(3)C_(6)H_(2) Fe4 and 2,6-Et_(2)-4-MeC_(6)H_(2) Fe5),each possessing one N-2,4-dibenzhydryl-6-fluorophenyl group,were readily synthesized from their respective unsymmetrical bis(imino)pyridines,*** identification of Fe2 highlighted the variation in the steric properties provided by the dissimilar N-aryl *** pre-treatment with either MAO or MMAO,complexes Fe1-Fe5 all displayed,at an operating temperature of 80℃,high activities for ethylene polymerization with levels falling in the order:Fe4> Fe1> Fe5> Fe2> ***,Fe4/MAO displayed the highest activity of 1.94×10^(7) g_(PE)·mol_(Fe)^(-1)·h^(-1) of the study with only a modest loss in performance at 90℃.Generally,the resulting polyethylenes were highly linear(T_(m) range:122-132℃),narrowly disperse and of low molecular weight(M_(w) range:6.73-46.04kg·mol^(-1)),with the most sterically hindered Fe3 forming the highest molecular weight polymer of the ***-group analysis by ^(1)H-and ^(13)CNMR spectroscopy revealed saturated alkyl(n-propyl and i-propyl) and unsaturated vinyl chain ends indicative of the role of both β-H elimination and chain transfer to aluminum as termination *** comparison with previou sly reported iron precatalysts with similar tridentate ligand skeletons,it is evident that the introduction of a large benzhydryl group in combination with a fluorine as the ortho-substituents of one N-aryl group has the effect of enhancing thermal stability of the iron polymerization catalyst whilst maintaining appreciable polymer molecular weight.

关键词： Iron catalyst Ethylene polymerization Linear polyethylene Fluoride effect Thermal stability

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Recent advances in graphene-based phase change composites for thermal energy storage and management

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Nano Materials science 2024年第2期6卷 115-138页

作者： Qiang Zhu Pin Jin Ong si Hui Angela Goh Reuben J.Yeo suxi Wang Zhiyuan Liu Xian Jun Loh Institute of Materials Research and Engineering A*STAR(Agency for ScienceTechnology and Research)2 Fusionopolis WayInnovis#08-03138634Singapore Institute of sustainability for Chemicals Energy and EnvironmentA*STAR(Agency for ScienceTechnology and Research)1 Pesek RoadJurong Island627833Singapore school of Chemistry Chemical Engineering and BiotechnologyNanyang Technological University21 Nanyang Link637371Singapore shenzhen Institutes of Advanced Technology(sIAT) Chinese Academy of Sciences(CAS)1068 Xueyuan AvenueShenzhen518055China Department of Material science and Engineering National University of Singapore9 Engineering Drive 1#03-09 EA117575Singapore

Energy storage and conservation are receiving increased attention due to rising global energy ***,the development of energy storage materials is *** energy storage(TEs)systems based on phase change materials(PCMs)have increased in prominence over the past two decades,not only because of their outstanding heat storage capacities but also their superior thermal energy regulation ***,issues such as leakage and low thermal conductivity limit their applicability in a variety of ***-based materials such as graphene and its derivatives can be utilized to surmount these *** study examines the recent advancements in graphene-based phase change composites(PCCs),where graphene-based nanostructures such as graphene,graphene oxide(GO),functionalized graphene/GO,and graphene aerogel(GA)are incorporated into PCMs to substantially enhance their shape stability and thermal conductivity that could be translated to better storage capacity,durability,and temperature response,thus boosting their attractiveness for TEs *** addition,the applications of these graphene-based PCCs in various TEs disciplines,such as energy conservation in buildings,solar utilization,and battery thermal management,are discussed and summarized.

关键词： Phase change material Nanocomposites solar energy sustainable energy Thermo-regulation

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Generation,bonding and reactivity of transient zinc-substituted silylenes

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science China Chemistry 2024年第4期67卷 1256-1262页

作者： Cheng Xu Thayalan Rajeshkumar Laurent Maron Xuebing Leng Yaofeng Chen state Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai 200032China spin-X Institute School of Chemistry and Chemical EngineeringState Key Laboratory of Luminescent Materials and DevicesGuangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional MaterialsSouth China University of TechnologyGuangzhou 510641China LPCNO CNRS&INSAUniversitéPaul SabatierToulous 31077France

The metal-substituted silylenes are of high interest,as the theoretical studies indicated that the silylenes with electropositive substituents have a small ΔE_(s-T)(singlet-triplet energy gap)or even the ground-state ***,such compounds are highly unstable,and only two transient alkali metal-substituted silylenes M(^(t)Bu_(3)si)si:(M=Li,K)were generated by photoextrusion of the alkali metal-substituted silacyclopropenes and merely studied by spectroscopic method(EPR)at low temperature(14 to 50 K).Herein,we report the generation of transient zinc-substituted silylenes from zinc silacyclopropanyl complexes under very mild and convenient *** generated transient zinc-substituted silylenes are highly reactive and undergo intermolecular cycloaddition with alkenes for the synthesis of zinc-substituted si-heterocyclic *** there is no substrate,the zinc-substituted silylenes attack the C-C bonds of the β-diketiminato ligands and break the C-C *** studies further highlight the silylene nature of the zinc-substituted silylene and a very small ΔE_(s-T)(4.4 kcal/mol).

关键词： zinc complex silylene C-C bond cleavage cycloaddition DFT calculations

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Vein visualization enhancement by dual-wavelength phase-locked denoising technology

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Journal of Innovative Optical Health sciences 2024年第3期17卷 73-83页

作者： Lihua Ruan Zhiqin Yin shibing Zhou Weibo Zheng Wei Lu Tao Zhang shaowei Wang shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083P.R.China state Key Laboratory of Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083P.R.China shanghai Engineering Research Center of Energy-saving Coatings shanghai 200083 P.R.China University of chinese academy of sciences Beijing 100049P.R.China shanghai Tech University Shanghai 201210P.R.China school of Physical science and Technology ShanghaiTech UniversityShanghai 201210P.R.China school of Information science and Technology ShanghaiTech UniversityShanghai 201210China

Visual near-infrared imaging equipment has broad applications in various fields such as venipuncture,facial injections,and safety verification due to its noncontact,compact,and portable ***,most studies utilize near-infrared single-wavelength for image acquisition of ***,many substances in the skin,including water,protein,and melanin can create significant background noise,which hinders accurate *** this paper,we developed a dual-wavelength imaging system with phase-locked denoising technology to acquire vein *** signals in the effective region are compared by using the absorption valley and peak of hemoglobin at 700nm and 940nm,*** phase-locked denoising algorithm is applied to decrease the noise and interference of complex surroundings from the *** imaging results of the vein are successfully extracted in complex noise *** is demonstrated that the denoising effect on hand veins imaging can be improved with 57.3%by using our dual-wavelength phase-locked denoising ***,this work proposes a novel approach for venous imaging with dual-wavelengths and phase-locked denoising algorithm to extract venous imaging results in complex noisy environment better.

关键词： Dual-wavelength phase-locked denoising vein visualization enhancement.

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specifications and control of spatial frequency errors of components in two-beam laser static holographic exposure for pulse compression grating fabrication

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High Power Laser science and Engineering 2024年第1期12卷 1-12页

作者： Chen Hu songlin Wan Guochang Jiang Haojin Gu Yibin Zhang Yunxia Jin shijie Liu Chengqiang Zhao Hongchao Cao Chaoyang Wei Jianda shao Precision Optical Manufacturing and Testing Center Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences(CAS)ShanghaiChina Key Laboratory for High Power Laser Material of chinese academy of sciences Shanghai Institute of Optics and Fine MechanicsCASShanghaiChina Center of Materials science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijingChina Hangzhou Institute for Advanced study University of Chinese Academy of SciencesHangzhouChina China-Russian Belt and Road Joint Laboratory on Laser science ShanghaiChina

The large-aperture pulse compression grating(PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser;however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers.

关键词： high-power laser off-axis reflective exposure system pulse compression grating spatial frequency errors specifications

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CAsIA-Iris-Africa:A Large-scale African Iris Image Database

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Machine Intelligence Research 2024年第2期21卷 383-399页

作者： Jawad Muhammad Yunlong Wang Junxing Hu Kunbo Zhang Zhenan sun school of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China Center for Research on Intelligent Perception and Computing National Laboratory of Pattern RecognitionInstitute of AutomationChinese Academy of SciencesBeijing 100190China

Iris biometrics is a phenotypic biometric trait that has proven to be agnostic to human natural physiological *** on iris biometrics has progressed tremendously,partly due to publicly available iris *** databases have been available to researchers that address pressing iris biometric challenges such as constraint,mobile,multispectral,synthetics,long-distance,contact lenses,liveness detection,***,these databases mostly contain subjects of Caucasian and Asian docents with very few *** many investigative studies on racial bias in face biometrics,very few studies on iris biometrics have been published,mainly due to the lack of racially diverse large-scale databases containing sufficient iris samples of Africans in the public ***,most of these databases contain a relatively small number of subjects and labelled *** paper proposes a large-scale African database named chinese academy of sciences Institute of Automation(CAsIA)-Iris-Africa that can be used as a complementary database for the iris recognition community to mediate the effect of racial biases on *** database contains 28717 images of 1023 African subjects(2046 iris classes)with age,gender,and ethnicity attributes that can be useful in demographically sensitive studies of *** of specific application protocols are incorporated with the database to ensure the database’s variability and *** results of some open-source state-of-the-art(sOTA)algorithms on the database are presented,which will serve as baseline *** relatively poor performances of the baseline algorithms on the proposed database despite better performance on other databases prove that racial biases exist in these iris recognition algorithms.

关键词： African iris recognition racial bias iris image database biometrics iris recognition

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Engineering of self-supported Electrocatalysts on a Three-Dimensional Nickel Foam Platform for Efficient Water Electrolysis

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Transactions of Tianjin University 2024年第2期30卷 103-116页

作者： Ceneng Chen Xian Wang Zijun Huang Jiahui Mo Xiaoyan Zhang Chao Peng Mohamed Khairy Junjie Ge Zhi Long Multiscale Crystal Materials Research Center Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China school of Chemistry and Materials science University of Science and Technology of ChinaHefei 230026China Chemistry Department Faculty of ScienceSohag UniversitySohâg 82524Egypt Dalian National Laboratory for Clean Energy Dalian 116023China

Economical water electrolysis requires highly active non-noble electrocatalysts to overcome the sluggish kinetics of the two half-cell reactions,oxygen evolution reaction,and hydrogen evolution *** intensive efforts have been committed to achieve a hydrogen economy,the expensive noble metal-based catalysts remain under ***,the engineering of self-supported electrocatalysts prepared using a direct growth strategy on three-dimensional(3D)nickel foam(NF)as a conductive substrate has garnered significant *** is due to the large active surface area and 3D porous network offered by these electrocatalysts,which can enhance the synergistic eff ect between the catalyst and the substrate,as well as improve electrocatalytic ***-assisted growth,microwave heating,electrodeposition,and other physical methods(i.e.,chemical vapor deposition and plasma treatment)have been applied to NF to fabricate competitive electrocatalysts with low overpotential and high *** this review,recent advancements in the development of self-supported electrocatalysts on 3D NF are ***,we provide future perspectives of self-supported electrode platforms in electrochemical water splitting.

关键词： Nickel foam Water splitting surface modification Hydrothermal method Microwave-assisted method Electrodeposition Chemical vapor deposition Plasma treatment

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New dating indicates intermittent human occupation of the Nwya Devu Paleolithic site on the high-altitude central Tibetan Plateau during the past 45,000 years

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science China Earth sciences 2024年第2期67卷 531-551页

作者： Junyi GE Xiaoling ZHANG shejiang WANG Linhui LI Wei HE Yingshuai JIN Peiqi ZhANG Bing XU Chenglong DENG John WOLsEN Zhengtang GUO Xing GAO Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of SciencesBeijing 100044China University of the chinese academy of sciences Beijing 100049China Tibetan Cultural Relics Conservation Institute Lhasa 850000China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of Sciences.Beijing 100029China state Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China school of Anthropology University of ArizonaTucson85721USA

The timing and mechanisms of the human occupation of the demanding high-altitude Tibetan Plateau environment are of great ***,we report on our reinvestigations and dating of the Nwya Devu site,located nearly 4600 meters above sea level on the central Tibetan Plateau.A new microblade techno-complex was identified on a lower lake shore at this site,distinct from the previously reported blade tool *** two lithic assemblages were dated to 45.6±2.6 and10.3±0.5 ka using optically stimulated luminescence and accelerator mass spectrometry^(14)C *** represent,respectively,the earliest known Paleolithic and microlithic sites on the interior Tibetan Plateau,indicating multiple occupation episodes of hunter-gatherers during the past 45 *** studies reveal that relatively stable depositional conditions and a paleoenvironment characterized by a comparatively warm climate facilitated these multiple occupations at Nwya *** contemporaneous occurrence of the Upper Paleolithic blade technology on the Tibetan Plateau and most of Eurasia between 50 and 40 ka indicates rapid,large-scale dispersals of humans that profoundly affected human demography on a large *** new archaeological evidence and previously reported genetic data,we conclude that the Tibetan Plateau provided a relatively stable habitat for Upper Paleolithic hunter-gatherers,which may have contributed to the complex and multiple-origin gene pool of present-day Tibetans.

关键词： Tibetan Plateau Paleolithic Nwya Devu High-altitude adaptation Microblade industry Early Upper Paleolithic OsLdating AMs^(14)C dating

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Coated boron layers by boronization and a real-time boron coating using an impurity powder dropper in the LHD

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Plasma science and Technology 2024年第8期26卷 25-31页

作者： Naoko AsHIKAWA Robert LUNsFORD Federico NEsPOLI Erik GILsON Yaowei YU Jiansheng HU shinichiro KADO National Institute for Fusion science Toki 509-5292Japan Princeton Plasma Physics Laboratory Princeton NJ 08540United States of America Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China Institute of Advanced Energy Kyoto UniversityKyoto 611-0011Japan

In the Large Helical Device(LHD),diborane(B2H6)is used as a standard boron source for boronization,which is assisted by helium glow *** 2019,a new Impurity Powder Dropper(IPD)system was installed and is under evaluation as a real-time wall conditioning *** the LHD,which is a large-sized heliotron device,an additional helium(He)glow discharge cleaning(GDC)after boronization was operated for a reduction in hydrogen recycling from the coated boron *** operational time of 3 h was determined by spectroscopic data during glow discharges.A flat hydrogen profile is obtained on the top surface of the coated boron on the specimen exposed to *** results suggest a reduction in hydrogen at the top surface by *** oxygen in coated boron was obtained by boronization,and the coated boron,which has boron-oxide,on the first wall by B-IPD was also *** the difference in coating areas between B2H6 boronization and B-IPD operation,it would be most effective to use the IPD and B2H6 boronization coating together for optimized wall conditioning.

关键词： boron layer oxygen impurity hydrogen recycling impurity powder dropper LHD EAsT

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亚波长光栅与法布里-珀罗滤光片集成的高性能光谱偏振分光器

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红外与毫米波学报 2024年第2期43卷 179-186页

作者：朱远宇关学昱余沛其刘清权贾奇祥吴杰李辰璐李志锋王少伟中国科学院上海技术物理研究所红外物理国家重点实验室上海200083 上海科技大学物质学院上海201210 上海节能镀膜玻璃工程技术研究中心上海200083 中国科学院大学北京100049

光谱偏振成像技术是一种新型的光学成像技术,它不仅提高了目标的信息获取量,还降低了背景噪声,可以捕获目标细节,检测伪装目标。本文提出了一种将亚波长光栅与F-P滤光片相结合的光谱偏振测量器件,该器件可以获得超高光谱分辨率和偏振消... 详细信息

光谱偏振成像技术是一种新型的光学成像技术,它不仅提高了目标的信息获取量,还降低了背景噪声,可以捕获目标细节,检测伪装目标。本文提出了一种将亚波长光栅与F-P滤光片相结合的光谱偏振测量器件,该器件可以获得超高光谱分辨率和偏振消光比,并且光谱和偏振可以灵活调控。本文设计了一种光谱偏振同时分光器,可同时获得4个光谱通道的斯托克斯参数。仿真结果表明,其光谱分辨率为217,偏振消光比为106。实验结果表明,亚波长光栅的偏振消光比大于500,透射率为90%。全介质F-P滤光片的光谱分辨率为30,在长波红外波段的透射率为60%。该设计方法具有通用性,可用于可见光、红外甚至太赫兹等波段。得益于这些优点,器件在微型偏振光谱仪和全斯托克斯偏振检测等领域有很大的应用潜力。

关键词：光谱偏振分光器亚波长光栅法布里-珀罗滤光片光谱偏振

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