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Optical properties of znO and Mn-doped znO nanocrystals by vapor phase transport processes

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Nano-Micro Letters 2009年第1期1卷 45-48页

作者： z.wang X.Y.Ma J.W.Song J.H.Yao School of Mathematics and Physics Suzhou University of Science and Technology Nankai University

In this paper we investigated the optical properties of znO and Mn doped znO nanocrystals that were fabricated by a vapor phase transport growth process, using zinc acetate dihydrate with or without Mn in a constant O2/Ar mixture gas flowing through the furnace at 400600℃, respectively. The as grown znO nanocrystals are homogeneous with a mean size of 19 nm observed by scanning electron microscope（SEM）. The optical characteristics were analyzed by absorption spectra and photoluminescence（PL） spectra at room-temperature. For znO nanocrystals, a strong and predominant UV emission peaked at 377 nm was found in the PL spectra. For Mn doped znO nanocrystals, in addition to the strong UV emission, a strong blue emission peaked at 435 nm was observed as well. By doping Mn ions, the major UV emission shifts from 377 nm to 408 nm, showing that Mn ions were not only incorporated into znO Ncs, but also introduced an impurity level in the bandgap. Moreover, with the concentration of Mn increasing, the relative intensities of the two emissions change largely, and the photoluminescence mechanism of them is discussed.

关键词： znO and Mn-doped znO nanocrystals Optical properties Vapor phase transport growth

Compressive property and energy absorption characteristic of interconnected porous Mg-zn-Y alloys with adjusting Y addition

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Journal of Magnesium and Alloys 2024年第1期12卷 171-185页

作者： J.A.Liu S.J.Liu B.wang W.B.Sun X.J.Liu z.W.Han College of Materials Science and Engineering Key Laboratory of Automobile Materials(Ministry of Education)Jilin UniversityChangchun 130022PR China Key Laboratory of Bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchun130022PR China Weihai Institute for Bionics-Jilin University Weihai 264205PR China

In this study,interconnected porous Mg-2zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption characteristics.Several characterization methods were then applied to identify the microstructure of the porous Mg-zn-Y and describe the details of the second phase.Compressive tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous Mg-zn-Y.The experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second phase.When the Y content increases,different Mg-zn-Y ternary phases appear:I-phase(Mg_(3)zn_(6)Y),W-phase(Mg_(3)zn_(3)Y_(2)),and LPSO phase(Mg_(12)znY).When the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 MJ/m^(3)to 10.97 MJ/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second phase.However,the average energy absorption efficiency is independent of the Y content.In addition,the compressive deformation behaviors of the porous Mg-zn-Y are altered by the testing temperature.The compressive strength and energy absorption capacity of the porous Mg-zn-Y decrease due to the softening effect of the high temperature on the struts.The deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

关键词： Porous magnesium Rare earth elements Microstructure Compressive behavior Energy absorption characteristic

Effective strategies to promote z(S)-scheme photocatalytic water splitting

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Chinese Chemical Letters 2024年第3期35卷 27-39页

作者： Ye Yuan Junan Pan Weinan Yin Haoxuan Yu Fengshun wang Weifeng Hu Longlu wang Dafeng Yan College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology) Nanjing University of Posts&Telecommunications(NUPT)Nanjing 210023China College of Chemistry and Chemical Engineering Hubei UniversityWuhan 430062China

Artificial z(S)-scheme photocatalytic water splitting systems have attracted extensive attention due to their advantages such as wide light absorption range,high charge separation efficiency and strong carrier redox ability.However,it is still challenging to design and prepare z(S)-scheme photocatalysts with low-cost and highly stability for efficiently photocatalytic overall water splitting using solar energy.This review mainly introduces various strategies to improve the photocatalytic water splitting performance of z(S)-scheme systems.These strategies mainly focus on enhancing or extending the range of light absorption,promoting charge separation,and enhancing surface redox reaction in z(S)-scheme systems.Finally,the main challenges of z(S)-scheme photocatalytic water splitting systems and their future development directions are pointed out.This review would be beneficial to understanding the challenges and opportunities faced by the research field of z(S)-scheme photocatalytic systems,and has important guiding significance for the development and utilization of high-performance z(S)-scheme photocatalytic reaction system in the future.

关键词： z(S)-scheme Overall water splitting Light absorption Charge separation Loading co-catalyst

Reply to “Beyond microbial carbon use efficiency”

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National Science Review 2024年第4期11卷 35-37页

作者： Feng Tao Johannes Lehmann Ying-Ping wang Lifen Jiang Bernhard Ahrens Kostiantyn Viatkin Stefano Manzoni Benjamin z.Houlton Yuanyuan Huang Xiaomeng Huang Yiqi Luo Department of Ecology and Evolutionary Biology Cornell University Soil and Crop Sciences Section School of Integrative Plant ScienceCornell University CSIRO Environment Max Planck Institute for Biogeochemistry Department of Physical Geography and Bolin Centre for Climate Research Stockholm University Department of Global Development Cornell University Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Department of Earth System Science Ministry of Education Key Laboratory for Earth System Modelling Institute for Global Change Studies Tsinghua University

In their commentary, Xiao et al.[1]cautioned that the conclusions on the critical role of microbial carbon use efficiency (CUE) in global soil organic carbon (SOC) storage in the paper by Tao et al.[2] might be too simplistic.They claimed that Tao et al.’s study lacked mechanistic consideration of SOC formation and excluded important data sets.Xiao et al. brought up important points,which can be largely reconciled with our findings by understanding the differences in expressing processes in empirical studies and in models.

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Solid-state Circuit Breaker Based on Cascaded Normally-on SiC JFETs for Medium-voltage DC Distribution Networks

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Protection and Control of Modern Power Systems 2024年第2期9卷 32-46页

作者： Dong He Haohui zhou zheng Lan Wei wang Jinhui zeng Xueping Yu z.John Shen Chongqing University of Posts and Telecommunications ChongqingChina Henan Polytechnic University JiaozuoChina College of Electrical and Information Engineering Hunan University of TechnologyZhuzhou 412007China Hunan University ChangshaChina College of Electrical and Information Engineering Hunan UniversityChangshaChina College of Electrical Engineering Three Gorges University Rensselaer Polytechnic Institute TroyNYUSA

Solid-state circuit breakers(SSCBs)are critical components in the protection of medium-voltage DC distribution networks to facilitate arc-free,fast and reliable isolation of DC faults.However,limited by the capacity of a single semiconductor device,using semi-conductor-based SSCBs at high voltage is challenging.This study presents the details of a 1.5 kV,63 A medi-um-voltage SSCB,composed primarily of a solid-state switch based on three cascaded normally-on silicon car-bide(SiC)junction field-effect transistors(JFETs)and a low-cost programmable gate drive circuit.Dynamic and static voltage sharing among the cascaded SiC JFETs of the SSCB during fault isolation is realized using the pro-posed gate drive circuit.The selection conditions for the key parameters of the SSCB gate driver are also analyzed.Additionally,an improved pulse-width modulation cur-rent-limiting protection solution is proposed to identify the permanent overcurrent and transient inrush current associated with capacitive load startup in a DC distribu-tion network.Using the developed SSCB prototype and the fault test system,experimental results are obtained to validate the fault response performance of the SSCB.Index Terms—Solid-state circuit breaker,DC distribu-tion network,SiC JFET,voltage balancing,inrush current.

关键词： Solid-state circuit breaker DC distribu-tion network SiC JFET voltage balancing inrush current

Remote Observations in China’s Ramsar Sites: Wetland Dynamics, Anthropogenic Threats, and Implications for Sustainable Development Goals

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Journal of Remote Sensing 2021年第1期2021卷 319-331页

作者： D.Mao z.wang Y.wang C.-Y.Choi M.Jia M.V.Jackson R.A.Fuller Key Laboratory of Wetland Ecology and Environment Northeast Institute of Geography and AgroecologyChinese Academy of SciencesChangchun 130102China National Earth System Science Data Center BeijingChina Department of Natural Resources Sciences University of Rhode IslandKingstonRI 02881USA School of Environmental Science and Engineering College of EngineeringSouthern University of Science and TechnologyShenzhen 518055China School of Biological Sciences The University of QueenslandBrisbaneAustralia

The Ramsar Convention on Wetlands is an international framework through which countries identify and protect important wetlands.Yet Ramsar wetlands are under substantial anthropogenic pressure worldwide,and tracking ecological change relies on multitemporal data sets.Here,we evaluated the spatial extent,temporal change,and anthropogenic threat to Ramsar wetlands at a national scale across China to determine whether their management is currently sustainable.We analyzed Landsat data to examine wetland dynamics and anthropogenic threats at the 57 Ramsar wetlands in China between 1980 and 2018.Results reveal that Ramsar sites play important roles in preventing wetland loss compared to the dramatic decline of wetlands in the surrounding areas.However,there are declines in wetland area at 18 Ramsar sites.Among those,six lost a wetland area greater than 100 km^(2),primarily caused by agricultural activities.Consistent expansion of anthropogenic land covers occurred within 43(75%)Ramsar sites,and anthropogenic threats from land cover change were particularly notable in eastern China.Aquaculture pond expansion and Spartina alterniflora invasion were prominent threats to coastal Ramsar wetlands.The observations within China’s Ramsar sites,which in management regulations have higher levels of protection than other wetlands,can help track progress towards achieving United Nations Sustainable Development Goals(SDGs).The study findings suggest that further and timely actions are required to control the loss and degradation of wetland ecosystems.

关键词： Sustainable threat wetland

Esophageal inserted subclavian catheter:a rare complication

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World Journal of Emergency Medicine 2024年第3期15卷 243-245页

作者： DilberÜçöz Kocaşaban SertaçGüler Emergency Medicine Clinic Health Sciences University Ankara Training and Research HospitalAnkara 06930Turkey

Central venous catheterization(CVC) is an invasive procedure for administering fluids,nutrients,and drugs;monitoring central venous pressure;performing pulmonary artery catheterization;and placing transvenous pacemakers in intensive care units and all specialties,from anesthesia to emergency medicine,for the treatment of trauma and hemodynamically unstable pediatric and adult patients.[1,2]Complications have been observed in more than 15% of patients who underwent CVC.Mechanical,infectious,and thrombotic complications have been reported in 5%–19%,5%–26%,and 2%–26% of patients,respectively.[3] Malposition,on the other hand,is common in subclavian catheter insertion and is usually associated with an initially misplaced guidewire.[4]

关键词： unstable insertion initially

Dysregulation of RNA modification systems in clinical populations with neurocognitive disorders

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Neural Regeneration Research 2024年第6期19卷 1256-1261页

作者： Helen M.Knight Merve Demirbugen ?z Adriana PerezGrovas-Saltijeral Division of Cells Organisms and Molecular Genetics School of Life Sciences University of Notingham Department of Pharmaceutical Toxicology Faculty of Pharmacy Ankara University

The study of modified RNA known as epitranscriptomics has become increasingly relevant in our understanding of disease-modifying mechanisms. Methylation of N6 adenosine(m6A) and C5 cytosine(m5C) bases occur on mRNAs, tRNA, mt-tRNA, and rRNA species as well as non-coding RNAs. With emerging knowledge of RNA binding proteins that act as writer, reader, and eraser effector proteins, comes a new understanding of physiological processes controlled by these systems. Such processes when spatiotemporally disrupted within cellular nanodomains in highly specialized tissues such as the brain, give rise to different forms of disease. In this review, we discuss accumulating evidence that changes in the m6A and m5C methylation systems contribute to neurocognitive disorders. Early studies first identified mutations within FMR1 to cause intellectual disability Fragile X syndromes several years before FMR1 was identified as an m6A RNA reader protein. Subsequently, familial mutations within the m6A writer gene METTL5, m5C writer genes NSUN2, NSUN3, NSUN5, and NSUN6, as well as THOC2 and THOC6 that form a protein complex with the m5C reader protein ALYREF, were recognized to cause intellectual development disorders. Similarly, differences in expression of the m5C writer and reader effector proteins, NSUN6, NSUN7, and ALYREF in brain tissue are indicated in individuals with Alzheimer’s disease, individuals with a high neuropathological load or have suffered traumatic brain injury. Likewise, an abundance of m6A reader and anti-reader proteins are reported to change across brain regions in Lewy bodies diseases, Alzheimer’s disease, and individuals with high cognitive reserve. m6A-modified RNAs are also reported significantly more abundant in dementia with Lewy bodies brain tissue but significantly reduced in Parkinson’s disease tissue, whilst modified RNAs are misplaced within diseased cells, particularly where synapses are located. In parahippocampal brain tissue, m6A modification is enriched in transcripts associated with psychiatri

关键词： 5-methylcytosine methylation Alzheimer’s disease cognitive diseases epitranscriptomics intellectual disability Lewy body diseases N6 adenosine RNA modification

Overcoming the strength-ductility trade-off by tailoring grain-boundary metastable Si-containing phase in β-type titanium alloy

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Journal of Materials Science & Technology 2021年第9期68卷 112-123页

作者： X.Luo L.H.Liu C.Yang H.z Lu H.W.Ma z.wang D.D.Li L.C.zhang Y.Y.Li National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou510640China State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan430074China Key Laboratory of Automobile Materials of MOE Department of Materials ScienceJilin UniversityChangchun130012China School of Engineering Edith Cowan University270Joondalup DriveJoondalupPerthWA 6027Australia

It is well accepted that grain-boundary phases in metallic alloys greatly deteriorate the mechanical properties.In our work,we report on a novel strategy to prepare high strength-ductility β-type(Ti69.71 Nb23.72zr4.83Ta1.74)97Si3(at.%)(TNzTS) alloys by tailoring grain-boundary metastable Si-containing phase.Specifically,the thin shell-shaped metastable S1 phase surrounding the columnar β-Ti grain was intercepted successfully via nonequilibrium rapid solidification achieved by selective laser melting(SLM).Subsequently,the thin shell-shaped metastable(Ti,Nb,zr)5 Si3(called S1) phase was transformed into globular(Ti,Nb,zr)2 Si(called S2) phase by the solution heat treatment.Interestingly,the globular S2 phases reinforced TNzTS alloy exhibits ultrahigh yield strength of 978 MPa,ultimate strength of 1010 MPa and large elongation of 10.4 %,overcoming the strength-ductility trade-off of TNzTS alloys by various methods.Especially,the reported yield strength herein is 55 % higher than that of conventionally forged TNzT alloys.Dynamic analysis indicates the globularization process of the metastable S1 phase is controlled by the model of termination migration.The quantitative analysis on strengthening mechanism demonstrates that the increase in yield strength of the heat-treated alloys is mainly ascribed to the strengthening of the precipitated silicide and the dislocations induced by high cooling rate.The obtained results provide some basis guidelines for designing and fabricating β-titanium alloys with excellent mechanical properties,and pave the way for biomedical application of TNzTS alloy by SLM.

关键词： Selective laser melting βtitanium alloys Heat treatment