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Opto-valleytronics in the 2D van der Waals heterostructure

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Nano Research 2021年第6期14卷 1901-1911页

作者： Abdullah Rasmita wei-bo gao Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore637371Singapore The Photonics Institute and Centre for Disruptive Photonic Technologies Nanyang Technological UniversitySingapore637371Singapore

The development of information processing devices with minimum carbon emission is crucial in this information age. One of the approaches to tackle this challenge is by using valleys (local extremum points in the momentum space) to encode the information instead of charges. The valley information in some material such as monolayer transition metal dichalcogenide (TMD) can be controlled by using circularly polarized light. This opens a new field called opto-valleytronics. In this article, we first review the valley physics in monolayer TMD and two-dimensional (2D) heterostructure composed of monolayer TMD and other materials. Such 2D heterostructure has been shown to exhibit interesting phenomena such as interlayer exciton, magnetic proximity effect, and spin-orbit proximity effect, which is beneficial for opto-valleytronics application. We then review some of the optical valley control methods that have been used in the monolayer TMD and the 2D heterostructure. Finally, a summary and outlook of the 2D heterostructure opto-valleytronics are given.

关键词： opto-valleytronics two-dimensional(2D)heterostructure interlayer exciton transition metal dichalcogenide proximity effect

Identifying critically ill patients at risk of death from coronavirus disease

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World Journal of Emergency Medicine 2021年第1期12卷 18-23页

作者： wei Guo Lin-yu Ran Ji-hong Zhu Qing-gang Ge Zhe Du Fei-long Wang wei-bo gao Tian-bing Wang Trauma Center Peking University People's HospitalBeijing 100044China Department of Pulmonary and Critical Care Medicine Shanghai East HospitalTongji UniversityShanghai 200120China Department of Emergency Peking University People's HospitalBeijing 100044China Department of Critical Care Unit Peking University Third HospitalBeijing 100191China

BACKGROUND:A pandemic of coronavirus disease(COVID-19)has been declared by the World Health Organization(WHO)and caring for critically ill patients is expected to be at the core of battling this ***,little is known regarding an early detection of patients at high risk of ***:This retrospective cohort study recruited consecutive adult patients admitted between February 8 and February 29,2020,to the three intensive care units(ICUs)in a designated hospital for treating COVID-19 in *** detailed clinical information and laboratory results for each patient were *** primary outcome was in-hospital *** predictors were analyzed for possible association with outcomes,and the predictive performance of indicators was assessed from the receiver operating characteristic(ROC)***:A total of 121 critically ill patients were included in the study,and 28.9%(35/121)of them died in the *** non-survivors were older and more likely to develop acute organ dysfunction,and had higher Sequential Organ Failure Assessment(SOFA)and quick SOFA(qSOFA)*** the laboratory variables on admission,we identifi ed 12 useful biomarkers for the prediction of in-hospital mortality,as suggested by area under the curve(AUC)above *** AUCs for three markers neutrophilto-lymphocyte ratio(NLR),thyroid hormones free triiodothyronine(FT3),and ferritin were 0.857,0.863,and 0.827,*** combination of two easily accessed variables NLR and ferritin had comparable AUC with SOFA score for the prediction of in-hospital mortality(0.901 vs.0.955,P=0.085).CONCLUSIONS:Acute organ dysfunction combined with older age is associated with fatal outcomes in COVID-19 *** biomarkers could be used as powerful predictors for the in-hospital mortality.

关键词： Coronavirus disease Neutrophil-to-lymphocyte ratio Mortality Predictor

Tribological and Corrosion Properties of the CoCrAlYTaSiC-xCNTs Coatings Deposited by Laser Cladding

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 726-738页

作者： Hai Zhao Yi Ding wei gao bo Yu Jinghui Li Mingya Zhang School of Material Science and Engineering Anhui University of TechnologyMaanshan243002China Maanshan Iron&Steel Co. LtdMaanshan243000China Applied Technology Research Institute Jiujiang Vocational UniversityJiujiang332000China School of Metallurgical Engineering Anhui University of TechnologyMaanshan243002China

The MCrAlY coating has been potential candidate for the parts applied in friction and corrosion conditions, and CNTs (carbon nanotubes) are expected to improve the service performance of coatings owing to high lubrication and low chemical reactivity. In this work, a systematic investigation on the tribological and corrosion properties of CoCrAlYTaSiC-xCNTs coatings deposited by laser melting was analyzed. Results showed that the coatings had good-quality without typical metallurgical defects. The CNTs addition homogenized and refined the microstructure of coating, and also improved the tribological and corrosion properties. As the CNTs content changed from 0 to 4 wt%, the wear rate of coating decreased from 16.23 × 10^(-3) to 7.58 × 10^(-3) mg m^(−1), the jcorr of coating decreased from 4.13 × 10^(-4) to 1.23 × 10^(-4) A cm^(−2), and the Rct values increased from 12.69 to 25.07 Ω cm2.

关键词： MCrAlY coating Laser melting deposition Friction Electrochemical corrosion

Effect of Incoming Vortex on Secondary Flows in Turbine Cascades with Planar and Non-Axisymmetric Endwall

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Journal of Thermal Science 2024年第1期33卷 138-157页

作者： CAO Zhiyuan WANG Chuxuan SONG Zhigao gao Xi ZHAO wei LIU bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an 710072China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100080China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100080China

Non-Axisymmetric Endwall Profiling(NAEP) is commonly utilized in turbines to eliminate secondary ***,most of the NAEP methods consider a single-blade row environment without incorporating the effect of the stage *** paper aims to investigate the influence mechanism of the incoming vortex on the endwall secondary flow structures of NAEP in a highly loaded turbine *** model the incoming vortex in a stage environment,this study considers a half-delta wing as the vortex generator at the upstream of the turbine *** NAEP is then carried out for a highly loaded turbine cascade with an in-house numerical optimization design platform subject to no incoming *** simulation is also carried out under the influence of the incoming vortex for the turbine cascades with both planar and non-axisymmetric *** paper furthers investigated the pitchwise effect of the incoming vortex on the near endwall secondary *** results indicate that the NAEP effectively improves the endwall secondary flow of the turbine cascade,where the total pressure loss coefficient and the secondary kinetic energy(SKE) are reduced by 7.3%,and 45.7%,*** is further seen that with the incoming vortex,the NAEP achieves a considerable control effect on the endwall secondary flow of the turbine *** incoming vortex,the NAEP can still achieve considerable control effect on the endwall secondary flow of the turbine cascade;the averaged reductions of loss coefficient and SKE are 7.8% and 14.2%,*** some pitchwise locations,incoming vortex can suppress the convection of cross-passage flow toward the suction corner greatly and reduce the loss coefficient of the baseline *** incoming vortex at 4/7 pitch impinged right at the blade leading edge,leading to the generation of low-momentum fluid,which increased the size and the strength of the horseshoe *** all the pitchwise locations,NAEP can suppress the seco

关键词： non-axisymmetric endwall secondary flow incoming vortex passage vortex stage environment

boosting oxygen reduction activity and CO_(2) resistance on bismuth ferrite-based perovskite cathode for low-temperature solid oxide fuel cells below 600℃

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Journal of Energy Chemistry 2024年第3期90卷 600-609,I0013页

作者： Juntao gao Zhiyun wei Mengke Yuan Zhe Wang Zhe Lü Qiang Li Lingling Xu bo wei School of Physics Harbin Institute of TechnologyHarbin 150001HeilongjiangChina Key Laboratory of Functional Inorganic Material Chemistry Ministry of EducationSchool of Chemistry and Materials ScienceHeilongjiang UniversityHarbin 150080HeilongjiangChina School of Physics and Electronic Engineering Harbin Normal UniversityHarbin 150025HeilongjiangChina

Developing efficient and stable cathodes for low-temperature solid oxide fuel cells(LT-SOFCs) is of great importance for the practical ***,we propose a series of Sm-modified Bi_(0.7-x)Sm_xSr_(0.3)FeO_(3-δ) perovskites as highly-active catalysts for *** doping can significantly enhance the electrocata lytic activity and chemical stability of *** 600℃,Bi_(0.675)Sm_(0.025)Sr_(0.3)FeO_(3-δ)(BSSF25) cathode has been found to be the optimum composition with a polarization resistance of 0.098 Ω cm^2,which is only around 22.8% of Bi_(0.7)Sr_(0.3)FeO_(3-δ)(BSF).A full cell utilizing BSSF25 displays an exceptional output density of 790 mW cm^(-2),which can operate continuously over100 h without obvious *** remarkable electrochemical performance observed can be attributed to the improved O_(2) transport kinetics,superior surface oxygen adsorption capacity,as well as O_(2)p band centers in close proximity to the Fermi ***,larger average bonding energy(ABE) and the presence of highly acidic Bi,Sm,and Fe ions restrict the adsorption of CO_(2) on the cathode surface,resulting in excellent CO_(2) *** work provides valuable guidance for systematic design of efficient and durable catalysts for LT-SOFCs.

关键词： Low-temperature solid oxide fuel cell Perovskite cathode DFT calculations CO_(2) tolerance

A green cross-linking method for the preparation of renewable threedimensional graphene sponges for efficient adsorption of Congo red dye

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Chinese Journal of Chemical Engineering 2024年第2期66卷 84-93页

作者： Zhuang Liu bo gao Haoyuan Han Yuling Li Haiyang Fu Donghui wei Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819China

Graphene-based materials possess significant potential for the treatment of dye wastewater due to their exceptional adsorption properties toward stubborn ***,their utilization is hindered by high preparation costs,low yields,environmental pollution during synthesis,and challenges in regenerating the *** study proposes a novel approach to address these limitations by developing nitrogen-doped three-dimensional(3D)polyvinyl alcohol(PVA)crosslinked graphene sponges(N-PGA)using a cross-linking method with ammonium *** method offers a relatively mild,environmentally friendly *** carbonate serves as both a reducing and modifying agent,facilitating the formation of the intrinsic structure of N-PGA and acting as a nitrogen ***,PVA is utilized as the cross-linking *** results demonstrate that N-PGA exhibits a favorable internal 3D hierarchical porous structure and possesses robust mechanical *** measured specific surface area(BET)of N-PGA was as high as406.538 m^(2)·g^(-1),which was favorable for its efficient adsorption of Congo red(CR)dye *** an initial concentration of 50 mg·L^(-1),N-PGA achieved an impressive removal rate of 89.6%and an adsorption capacity of 112 mg·g^(-1)for CR ***,it retained 79%of its initial adsorption capacity after 10 cycles,demonstrating excellent regeneration *** summary,the synthesized N-PGA displays remarkable efficacy in the adsorption of CR dye in wastewater,opening up new possibilities for utilizing 3D porous graphene nanomaterials as efficient adsorbents in wastewater treatment.

关键词： Green chemistry Graphene sponge Adsorbents Adsorption Congo red Regeneration

Simultaneous oxidation of NO,SO_2 and Hg^0 from flue gas by pulsed corona discharge

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Journal of Environmental Sciences 2009年第3期21卷 328-332页

作者： XU Fei,LUO Zhongyang,CAO wei,WANG Peng,wei bo,gao Xiang,FANG Mengxiang,CEN Kefa State key Laboratory of Clean Energy Utilization,Zhejiang University,Hangzhou 310027,China. State key Laboratory of Clean Energy Utilization Zhejiang University Hangzhou 310027 China

A process capable of simultaneously oxidizing NO, SO2, and Hg^0 was proposed, using a nigh-voltage and short-duration positive pulsed corona discharge. By focusing on NO, SO2, and Hg^0 oxidation efficiencies, the influences of pulse peak voltage, pulse frequency, initial concentration, electrode number, residence time and water vapor addition were investigated. The results indicate that NO, SO2 and Hg^0 oxidation efficiencies depend primarily on the radicals （OH, HO2, O） and the active species （O3, H2O2, etc.） produced by the pulsed corona discharge. The NO, SO2 and Hg^0 oxidation efficiencies could be improved as pulse peak voltage, pulse frequency, electrode number and residence time increased, but they were reduced with increasing initial concentrations. By adding water vapor, the SO2 oxidation efficiency was improved remarkably, while the NO oxidation efficiency decreased slightly. In our experiments, the simultaneous NO, SO2, and Hg^0 oxidation efficiencies reached to 40%, 98%, and 55% with the initial concentrations 479 mg/m^3, 1040 mg/m^3, and 15.0 μg/m^3, respectively.

关键词： pulsed corona discharge NO SO2 Hg^0 radical active species oxidation efficiency

Room-temperature third-order nonlinear Hall effect in Weyl semimetal TalrTe4

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National Science Review 2022年第12期9卷 177-184页

作者： Cong Wang Rui-Chun Xiao Huiying Liu Zhaowei Zhang Shen Lai Chao Zhu Hongbing Cai Naizhou Wang Shengyao Chen Ya Deng Zheng Liu Shengyuan A.Yang wei-bo gao College of Mathematics and Physics Beijing University of Chemical Technology Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Institute of Physical Science and Information Technology Anhui University Research Laboratory for Quantum Materials Singapore University of Technology and Design School of Materials Science and Engineering Nanyang Technological University CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology The Photonics Institute and Centre for Disruptive Photonic Technologies Nanyang Technological University

The second-order nonlinear Hall effect observed in the time-revers al symmetric system has not only shown abundant physical content,but also exhibited potential application ***,a third-order nonlinear Hall effect has been observed in MoTe2and ***,few-layer MoTe2and WTe2are usually unstable in air and the observed third-order nonlinear Hall effect can be measured only at low temperature,which hinders further investigation as well as potential ***,exploring new air-stable material systems with a sizable third-order nonlinear Hall effect at room temperature is an urgent ***,in type-Ⅱ Weyl semimetal TaIrTe4,we observed a pronounced third-order nonlinear Hall effect,which can exist at room temperature and remain stable for *** third-order nonlinear Hall effect is connected to the Berry-connection polarizability tensor instead of the Berry *** possible me chanism of the observation of the third-order nonlinear Hall effe ct in TaIrTe4at room temperature has been *** findings will open an avenue towards exploring room-temperature nonlinear devices in new quantum materials.

关键词： topological material third-order nonlinear Hall effect room temperature Berry connection polarizability tensor

OnFractional(g,f,n′,m)-Critical Covered Graphs

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Journal of the Operations Research Society of China 2024年第2期12卷 446-460页

作者： wei gao wei-Fan Wang School of Information Science and Technology Yunnan Normal UniversityKunming 650500YunnanChina Department of Mathematics Zhejiang Normal UniversityJinhua 321004ZhejiangChina

The main contribution in this article is threefold:(1)we show the necessary and sufficient condition for graphs to be fractional(g,f)-covered which can be expressed in different forms,and extended to fractional(g,f,m)-covered graphs;(2)the concept of fractional-critical covered graph is put forward and its necessary and sufficient condition is given;(3)we present the degree condition for a graph to be fractional(g,f,n′,m)-critical covered,and show that degree bound is sharp when m is ***,the related result in fractional(a,b,n′,m)-critical covered setting is also verified.

关键词： Network Fractional factor Data transmission Fractional covered graph Fractional critical covered graph