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An aqueous 2.1 V pseudocapacitor with MXene and V-MnO_(2) electrodes

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nano Research 2022年第1期15卷 535-541页

作者： Jiabin Wu Qun Li Christopher E.Shuck Kathleen Maleski Husam n.Alshareef Jun zhou Yury Gogotsi Liang Huang Wuhan national Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Department of Materials Science and Engineering and A./.Drexel nanomaterials Institute Drexel UniversityPhiladelphiaPennsylvania 19104USA Materials Science and Engineering Physical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia

MXenes have shown record-breaking redox capacitance in aqueous electrolytes,but in a limited voltage window due to oxidation under anodic potential and hydrogen evolution under high cathodic *** Ti3C2Tx Xene negative electrode with RuO_(2) or carbon-based positive electrodes expanded the voltage window in sulfuric acid electrolyte to about 1.5 ***,we present an asymmetric pseudocapacitor using abundant and eco-friendly vanadium doped MnO_(2) as the positive and Ti_(3)C_(2)Tx MXene as the negative electrode in a neutral 1M Li2SO4 *** all-pseudocapacitive asymmetric device not only uses a safer electrolyte and is a much less expensive counter-electrode than RuO_(2),but also can operate within a 2.1 V voltage window,leading to a maximum energy density of 46 Wh/*** study also demonstrates the possibility of using MXene electrodes to expand the working voltage window of traditional redox-capable materials.

关键词： MXene pseudocapacitors metal oxides supercapacitors manganese oxide

Laser welding study of vacuum sintered HUST-1 lunar regolith simulant

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Science China(Technological Sciences) 2024年第9期67卷 2905-2918页

作者： HAn WenBin DInG LieYun zhou Cheng zhou Yan DAnG Fen national Center of Technology Innovation for Digital Construction Huazhong University of Science and TechnologyWuhan 430074China School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 730074China

Efforts are underway to establish a permanent lunar base on the Moon. In situ lunar regolith is anticipated to be useful as a building material after sintering. However, sintering lunar regolith into a large-scale structure presents challenges. Therefore, the key to lunar construction lies in assembling multiple small-sized sintered modules into a stable, large-sized structure. This study explored the feasibility of welding the sintered HUST-1 lunar regolith simulant(HLRS) using a laser device and conducted experiments using lasers of varying power. The microstructure, mineral composition, element distribution, and shear strength of the welded joint were investigated. A few low-melting minerals were fused and vaporized during welding, leading to the generation of thermal decomposition gas. Furthermore, the welded joint exhibited numerous micro-cracks, pores, and bubbles,resulting in reduced weld shear strength. Finally, the influence of laser power on weld shear strength was investigated, revealing that the highest shear strength(15.69 n/cm) was achieved at a laser power of 1000 W. This study demonstrates the feasibility of laser welding of sintered HLRS for the first time, with potential applications in lunar base construction.

关键词： lunar regolith vacuum sintering laser welding weld shear strength lunar base

Molecular dynamics study of water diffusion in an amphiphilic block copolymer with large difference in the blocks＇ glass transition temperatures

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Frontiers of Chemical Science and Engineering 2017年第3期11卷 440-447页

作者： Yang zhou Phillip Choi Department of Chemical and Materials Engineering University of Alberta Edmonton Edmonton AB T6G 1H9 Canada

Isothermal-isobaric molecular dynamics simu- lation was used to study the diffusion mechanism of water in polyurethane-block-poly（n-isopropyl acrylamide）（PU- block-PnIPAm） with a hydrophobic PU/hydrophilic PnIPAm mass ratio of 1.4 to 1 at 298 K and 450 K. Here, the experimental glass transition temperature （Tg） of PU is 243 K while that of PnIPAm is 383 K. Different amounts of water up to 15 wt-% were added to PU-block- PnIPAm. We were able to reproduce the specific volumes and glass transition temperatures （250 K and 390 K） of PU- block-PnIPAm. The computed self-diffusion coefficient of water increased exponentially with increasing water concentration at both temperatures （i.e., following the free volume model of Fujita）. It suggested that water diffusion in PU-block-PnIPAm depends only on its fractional free volume despite the free volume inhomo- geneity. It is noted that at 298 K, PU is rubbery while PnIPAm is glassy. Regardless of temperature, radial distribution functions showed that water formed clusters with sizes in the range of 0.2-0.4 nm in PU-block- PnIPAm. At low water concentrations, more clusters were found in the PU domain but at high water concentrations, more in the PnIPAm domain. It is believed that water molecules diffuse as clusters rather than as individual molecules.

关键词： molecular dynamics simulation amphiphilic block copolymer free volume water diffusivity fujita model

Decadal change of East Asian summer tropospheric temperature meridional gradient around the early 1990s

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Science China Earth Sciences 2015年第9期58卷 1609-1622页

作者： ZHAnG LiXia zhou TianJun LASG Institute of Atmospheric Physics Chinese Academy of Sciences Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology Joint Center for Global Change Studies

During 1979–2004, the East Asian summer precipitation has experienced another significant decadal shift around the early 1990 s. Based on three radiosonde temperature datasets and four reanalysis datasets, this paper examines the decadal change of the East Asian summer tropospheric temperature around the early 1990 s. The results show that the meridional gradient of layer mean upper tropospheric temperature for 200–500 h Pa(here after UTT, UTT is upper tropospheric temperature) also underwent an obvious decadal decrease around 1992. The tropospheric temperature south to 35°n becomes decadal cooling, centered along the Yangtze River Valley, while the tropospheric temperature north to 35°n shows a decadal warming, centered in northwest China-Mongolia. JRA-25 reanalysis is better than the other reanalysis datasets in revealing this decadal change. This decadal shift of East Asian summer UTT may be ascribed to the decadal change of the EnSO period from low-frequency oscillation(4–6 yr) to quasi-biennial oscillation since 1992. It behaves as an increase of EnSO developing events and a reduction of EnSO decaying events. It leads to stronger forcing of EnSO developing summer and weaker forcing of EnSO decaying summer, leading to the dominant role of monopole cooling mode of East Asian UTT after 1992, in contrast to the dominant role of dipole mode of East Asia UTT before 1992. The summer UTT difference between 1993–2004 and 1979–1992 shows a "South cooling-north Warming" pattern, and thereby contributes to the interdecadal decrease of East Asian summer UTT meridional gradient around 1992.

关键词： decadal variation around the early 1990s East Asian summer monsoon change of EnSO period

Effect of silver nanoparticles on an integrated fixed-film activated sludge–sequencing batch reactor: Performance and community structure

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Journal of Environmental Sciences 2019年第6期31卷 229-239页

作者： Hexi zhou Guoren Xu State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology national Engineering Laboratory for Sustainable Sludge Management & Resourcelization Technology Harbin Institute of Technology

The effects of silver nanoparticles(AgnPs) on reactor performance, extracellular polymeric substances composition and microbial community structure and function in integrated fixed-film activated sludge–sequencing batch reactors(IFAS–SBRs) were *** showed that the addition of AgnPs from 0.1 to 10 mg/L exhibited no significant effects on nutrient removal. The average overall removal of COD, nH4+–n and PO43-–P was96.6%, 99.9% and 98.8%, respectively. The introduction of AgnPs caused an increase in extracellular polymeric substances content for the sludge and biofilm of IFAS–SBRs. The release of Ag+from Ag nPs and lactate dehydrogenase test implied the low toxicity of AgnPs to IFAS–SBRs. High-throughput sequencing revealed that microbial community structure showed significant shifts at phylum and genus levels after long-term exposure to AgnPs,but core functional groups responsible for nutrient removal remained at high *** function prediction indicated that the metabolic categories showed no significant shifts under AgnPs stress, therefore good process performance could still be achieved.

关键词： AgnPs Performance Toxicity Community structure IFAS-SBR

Bifurcation and Chaos of Piezoelectric Shell Reinforced with BnnTs Under Electro-Thermo-Mechanical Loadings

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Acta Mechanica Solida Sinica 2019年第1期32卷 120-132页

作者： Jinhua Yang Tao zhou School of Civil Engineering Changsha University of Science and TechnologyChangsha 410114China

By employing the nonlinear von Karman shell theory and the theory of piezoelect ricity including thermal effec ts,the constitutive relations of the BnnT-reinforced piezoelec trie shell are *** to the'XY‘rec tangle model,the material consta nts are ***,the nonlinear governing equations of the st rue ture are derived t hrough the Reissner variational principle and solved by the fourth-order Runge-Kutta *** numerical calculations,the effects of temperature,voltage,volume fraction,etc.,on the bifurcation and chaos of piezoelectric shell reinforced with BnnTs are discussed in detail.

关键词： Bifurcation and chaos Piezoelec trie shell BnnTs Reissner variational principle Runge-Kutta method

Computational analysis of(MAP_1,MAP_2)/(PH_1,PH_2)/n queues with finite buffer in wireless cellular networks

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Journal of Systems Engineering and Electronics 2011年第5期22卷 739-748页

作者： Zonghao zhou Yijun Zhu Faculty of Science Jiangsu University Zhenjiang 212013 P. R. China

This paper studies a queueing model with the finite buffer of capacity K in wireless cellular networks, which has two types of arriving calls--handoff and originating calls, both of which follow the Markov arriving process with different rates. The channel holding times of the two types of calls follow different phase-type distributions. Firstly, the joint distribution of two queue lengths is derived, and then the dropping and blocking probabilities, the mean queue length and the mean waiting time from the joint distribution are gotten. Finally, numerical examples show the impact of different call arrival rates on the performance measures.

关键词： wireless cellular network queue Markov arriving process (MAP) phase-type (PH) distribution handoff call originating call.

Tuning the selectivity of natural oils and fatty acids/esters deoxygenation to biofuels and fatty alcohols:A review

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Green Energy & Environment 2023年第3期8卷 722-743页

作者： Yingdong zhou Javier Remon Zhicheng Jiang Avtar S.Matharu Changwei Hu Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengduSichuan 610064China Instituto de Carboquímica CSICZaragoza50018Spain Department of Biomass Science and Engineering Sichuan UniversityChengdu610064China national Engineering Research Center of Clean Technology in Leather Industry Sichuan UniversityChengdu610064China Green Chemistry Centre of Excellence Department of ChemistryUniversity of YorkHeslingtonYorkYO105DDUK

The chemical transformation of natural oils provides alternatives to limited fossil fuels and produces compounds with added value for the chemical *** selective deoxygenation of natural oils to diesel-ranged hydrocarbons,bio-jet fuels,or fatty alcohols with controllable selectivity is especially attractive in natural oil feedstock *** review presents recent progress in catalytic deoxygenation of natural oils or related model compounds(e.g.,fatty acids)to renewable liquid fuels(green diesel and bio-jet fuels)and valuable fatty alcohols(unsaturated and saturated fatty alcohols).Besides,it discusses and compares the existing and potential strategies to control the product selectivity over heterogeneous *** research conducted and reviewed has only addressed the production of one category;therefore,a new integrative vision exploring how to direct the process toward fuel and/or chemicals is urgently ***,work conducted to date addressing the development of new catalysts and studying the influence of the reaction parameters(e.g.,temperature,time and hydrogen pressure)is summarized and critically discussed from a green and sustainable perspective using efficiency indicators(e.g.,yields,selectivity,turnover frequencies and catalysts lifetime).Special attention has been given to the chemical transformations occurring to identify key descriptors to tune the selectivity toward target products by manipulating the reaction conditions and the structures of the ***,the challenges and future research goals to develop novel and holistic natural oil biorefineries are *** a result,this critical review provides the readership with appropriate information to selectively control the transformation of natural oils into either biofuels and/or value-added *** new flexible vision can help pave the wave to suit the present and future market needs.

关键词： natural oil Deoxygenation Controllable selectivity Biofuels Fatty alcohols

STUDY OF MIXED RARE EARTH METAL (REM) COnVERSIOnCOATInG On ALUMInUM ALLOY LY12

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Acta Metallurgica Sinica(English Letters) 2000年第5期13卷 1034-1038页

作者： Yu, X.W. Cao, C.n. zhou, D.R. Yin, Z.D. Lab. for Corrosion and Protection Inst. of Corrosion and Protection Chinese Acad. of Sci. shenyang 110015 China Sch. of Mat. Sci. and Eng. Harbin Inst. of Technol. Harbin 150001 China

The process of mixed rare earth metal (REM) conversion coating on aluminum alloy LY12 (2024) was introduced. The corrosion resistance of mixed REM conversion coating was examined by using weight loss test and electrochemical method. The results show that the mixed REM conversion coating increases the corrosion resistance of the alloy surface. Examination result of scanning electron microscope (SEM) shows that the coating exhibits honeycomb-like feature. X-ray diffraction (XRD) analysis reveals that the coating is amorphous. The result of X-ray photoelectron spectroscopy (XPS) indicates that mixed REM conversion coating consists predominantly of Ce and O. The contents of other rare earth elements (La, Pr) are relatively low.

关键词： Aluminum alloys Composition Corrosion resistance Inorganic coatings Morphology