检索结果-南通市图书馆

Journal of Materials Science & Technology 2024年第2期169卷 235-242页

作者： h.X.Lu h.Liu z.z.Fu Y.Y.Chen h.Q.Dai z.hu W.L.zhang R.Q.Guo Institute for Electric Light Sources School of Information Science and TechnologyFudan UniversityShanghai 200433China Institute of Future Lighting Academy for Engineering and TechnologyFudan UniversityShanghai 200433China Yiwu Research Institute of Fudan University YiwuZhejiang 322000China zhongshan-Fudan Joint Innovation Center Zhongshan 528437China

In this study,a two-step method was used to synthesize highly luminescent AgGaS/znS/znS quantum dots(QDs).In the first step,an inner znS shell was formed via a one-pot method,which resulted in a smaller lattice mismatch between the AgGaS core and the outer znS shell,thereby facilitating the formation of a thick outer shell.After the two-step shelling process,the synthesized AgGaS/znS/znS QDs showed an excellent photoluminescence quantum yield(PLQY)of 96.4%with a peak wavelength of 508 nm,repre-senting the highest PLQY reported thus far for AgGaS QDs.Furthermore,the effect of halogen ions in zn precursors on the shelling process was investigated.It was proposed that the capacity of halogen ions to coordinate with the QDs influenced the balance between zn cation diffusion and znS shelling reaction.Specifically,the znS shelling reaction was dominant when znCl_(2)was employed,while zn cation diffusion was the dominant process under the I^(−)-rich environment.This work provides insights into the interfacial restructuring during the znS shelling and offers a clear map for the tailored synthesis of core/shell QDs.

关键词： AgGaS Quantum dots Photoluminescence Core/shell Alloyed core/shell interface

Precipitation of multi-type nano-quasicrystals in a Mg-zn-Y alloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： W.z.Wang X.z.zhou L.F.zhang h.Q.Ye z.Q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji hua Laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging treatments.Microstructural evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy techniques.Two new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral quasicrystals.Atomic-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged aging.In addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 K.Our findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

Exploring Variability in Sea Level at a Tide Gauge Station through Control Charts

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental & Earth Sciences 2024年第1期6卷 11-18页

作者： h.Bâkiİz Independent Scholar Boca Raton Florida33496USA

Monitoring temporal changes in sea level is important in assessing coastal risk.Sea level anomalies at a tide gauge station,if kinematically conceived,include systematic variations such as trend,acceleration,periodic oscillations,and random disturbances.Among them,the non-stationary nature of the random sea level variations of known or unknown origin at coastal regions has been long recognized by the sea level community.This study proposes the analyses of subgroups of random residual statistics of a rigorously formulated kinematic model solution of tide gauge variations using X-bar and S control charts.The approach is demonstrated using Key West,Florida tide gauge records.The mean and standard errors of 5-year-long subgroups of the residuals revealed that sea level changes at this location have been progressively intensifying from 1913 to the present.Increasing oscillations in sea level at this locality may be attributed partly to the thermal expansion of seawater with increasing temperatures causing larger buoyancy-related sea level fluctuations as well as the intensification of atmospheric events including wind patterns and the impact of changes in inverted barometer effects that will alter coastal risk assessments for the future.

关键词： Climate change Sea level variance X-bar S control charts

Microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with different prestrain levels

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第4期171卷 80-93页

作者： Y.h.zhang h.Li z.W.Yang X.Liu Q.F.Gu State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of high-Performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(SMA)is a promising material in the aerospace field due to its wide transformation hysteresis.The application of shape memory effect depends on multistep thermomechan-ical loading,viz.,low-temperature deformation and subsequent heating to recovery.Low-temperature deformation prestrain plays a pivotal role in shape memory properties tailoring of SMA components.however,microstructure evolution and deformation mechanisms of Ni_(47)Ti_(44)Nb_(9)SMA subjected to vari-ous prestrain levels are still unclear.To this end,microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with prestrain levels of 8%-16%at-28℃(M_(s)+30℃)were investigated.The results demonstrate that the stress-strain curve of the specimen exhibits four distinct stages at a maximal prestrain of 16%.Whereas stageⅡand stageⅢend at prestrains of∼8%and∼12%,respectively.In stageⅡ,the stress-induced martensitic transformation is accompanied by the dislocation slip of the NiTi matrix andβ-Nb inclusions.In stageⅢ,in addition to the higher density of dislocations and further growth of stress-induced martensite variants(SIMVs),(001)compound twins are introduced as a result of the(001)deformation twinning in stress-induced martensite.More{20-1}martensite twins are gradually introduced in stageⅣ.Correspondingly,after subsequent unloading and heating,a higher density of{114}austenite twins form in the specimen with a larger prestrain of 16%.With increasing prestrain from 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases first and then decreases.Theε_(re)^(T)obtains a maximum of 7.03%at 10%prestrain and de-creases to 6.17%at 16%prestrain.The increase ofε_(re)^(T)can be attributed to the formation of new SIMVs,the further growth of existing SIMVs,and the recoverable(001)compound twins.While the decrease ofε_(re)^(T)is mainly associated with the irrecoverable strain by{20−1}martensite twins.The effect ofβ-Nb inclusions on the evolution of SIMVs i

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy Wide transformation hysteresis Thermomechanical loading Microstructure evolution Shape memory behaviors Stress-induced martensitic transformation Deformation twinning

Construction of 2D/2D Ti_(3)C_(2)T_(x)MXene/CdS heterojunction with photothermal effect for efficient photocatalytic hydrogen production

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第4期171卷 1-9页

作者： T.Y.huang z.Yang S.Y.Yang z.h.Dai Y.J.Liu J.h.Liao G.Y.zhong z.J.Xie Y.P.Fang S.S.zhang Key Laboratory for Biobased Materials and Energy of Ministry of Education Guangdong Laboratory for Lingnan Modern AgricultureCollege of Materials and EnergySouth China Agricultural UniversityGuangzhou 510643China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China School of Chemical Engineering and Energy Technology Guangdong Provincial Key Laboratory of Distributed Energy SystemsDongguan University of TechnologyDongguan 523808China

The insensitivity of semiconductors to visible and infrared light is a key constraint on the utilization of light energy in photocatalytic reactions.Constructing photocatalysts with full-spectrum absorption through surface engineering is an effective approach to fully harnessing light energy in semiconductor materials.herein,a novel stable Ti_(3)C_(2)T_(x)MXene/CdS heterojunction catalyst is obtained by in-situ epitaxial growth of two-dimensional(2D)CdS nanosheets on 2D MXene interface via a solvothermal method.The exceptional light absorption properties of MXene confer outstanding full-spectrum driven photocat-alytic hydrogen evolution capability upon the heterogeneous catalyst.The unique 2D/2D structure effectively mitigated the recombination of photogenerated carriers,enhancing the photocatalytic performance of the catalyst.Moreover,the composite catalyst exhibits a significantly higher surface temperature of 80.4℃under visible light irradiation at an intensity of 0.1 W/cm^(2),which is 1.84 times higher than that of CdS.Under irradiation of visible and near infrared light,the composite catalyst with photothermal ef-fect demonstrates a remarkable hydrogen evolution rate of 65.4 mmol g^(-1)h^(-1),which is 7.2 times higher than that of CdS catalyst.This study introduces a novel approach for constructing full-spectrum absorption catalysts and expands the application of the photothermal effect in photocatalytic hydrogen evolution research.

关键词： Two-dimensional structure heterostructure Photothermal effect Photocatalyst hydrogen evolution

Efficient photocatalytic NADh regeneration with Rh-loaded z-scheme mediator-free system

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第2期35卷 496-500页

作者： Yi zhou Yiling he Ming Gao Ningkai Ding Juying lei Yanbo zhou State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process East China University of Science and TechnologyShanghai 200237China National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery East China University of Science and TechnologyShanghai 200237China Shanghai Engineering Research Center for Multi-media Environmental Catalysis and Resource Utilization East China University of Science and TechnologyShanghai 200237China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China

Nicotinamide adenine dinucleotide(NADh)regeneration is necessary for the sustainable application of enzymatic industry.The Rh-based complex[Cp^(*)Rh(bpy)(h)]+has been widely used as an important mediator in NADh regeneration systems,but it is limited by complexity and high cost.here,a z-scheme was constructed by loading Rh onto carbon nitride nanosheets/carbon nitride quantum dots(CN-CNQD).The resultant catalyst achieved a high yield of NADh in a mediator-free(M-free)system of 0.283 mmol L^(−1) g^(−1) min^(−1),which is 5.29 times that of pure CN.ADh enzyme introduction experiments confirmed that the enzyme active product 1,4-NADh could reach 34.21%selectivity in the M-free system.Mechanism research revealed that the heterojunction between CNs and CNQDs improved the NADh regeneration activity in the traditional M-involved system,while Rh loading was proved to optimize the yield and selectivity of 1,4-NADh in M-free system.The immobilized Rh shows more competitiveness than[Cp^(*)Rh(bpy)(h)]^(+).This study contributes to the construction of an M-free system for further application in greener,lower-cost enzymatic processes.

关键词： Photocatalysis NADh regeneration Mediator-free Carbon nitride z-scheme

The Short-Duration heavy Rainfall in Different Quadrants of Northeast China Cold Vortices

在线全文

学校读者我要写书评

暂无评论

Journal of Meteorological Research 2024年第2期38卷 321-338页

作者： lei YANG Yongguang zhENG Liaoning Meteorological Disaster Monitoring and Early Warning Center Shenyang 110166 National Meteorological Centre China Meteorological AdministrationBeijing 100081 China Meteorological Administration Tornado Key Laboratory Foshan 528315

The Northeast China cold vortex(NCCV)is one of the main synoptic-scale systems causing short-duration heavy rainfall(SDhR)in Northeast China.Environmental conditions(e.g.,water vapor,instability,and vertical wind shear)are known to be distinctly different over the four quadrants of NCCVs,rendering prediction of the SDhR related to NCCVs(NCCV_SDhR)more challenging.Based on 5-yr hourly rainfall observations from 3196 automatic weather stations and ERA5 reanalysis data,10,232 NCCV_SDhR events were identified and divided into four quadrant groups according to their relative position to the center of the NCCV(CVC).The results show that the southeast quadrant features the highest frequency of SDhR,with stronger intensity,longer duration,and wider coverage;and the SDhR in different quadrants presents different formation mechanisms and varied temporal evolution.A new coordinate system is established relative to the CVC that uses the CVC as the origin and the radius of the NCCV(r CV)as the unit distance.In this new coordinate system,all of the NCCV_SDhR events in the 5-yr study period are synthesized.It is found that the occurrence frequency of NCCV_SDhR initially increases and then decreases with increasing distance from the CVC.The highest frequency occurs mainly between 0.8 and 2.5 times r CV from the CVC in the southeast quadrant.This can be attributed to the favorable conditions,such as convergence of the low-level shear line and abundant water vapor,which are concentrated in this region.Furthermore,high-frequency NCCV_SDhR larger than 50 mm(NCCV_SDhR50)is observed to be closer to the CVC.When NCCV_SDhR50occurs,the NCCV is in closer proximity to the subtropical high,resulting in stronger low-level convergence and more abundant water vapor.Additionally,there are lower lifting condensation levels and stronger 0-6-and 0-1-km vertical wind shears in these environments.These findings provide a valuable reference for more accurate prediction of NCCV_SDhR.

关键词： Northeast China cold vortex short-duration heavy rainfall statistical characteristics environmental conditions

Enhanced photocatalytic performance of Bi_(2)O_(2)CO_(3)/Bi_(4)O_(5)Br_(2)/reduced graphene oxide z-schemehe terojunction via a one-pot room-temperature synthesis

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第4期138卷 418-427页

作者： Xiaoge Wu lei Yan Rongrong Qin Qikai zhang Wei Yang Xiaozhi Wang Yongcai zhang Min Luo Jianhua hou College of Environmental Science and Engineering Yangzhou UniversityYangzhouJiangsu 225009China Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Nanjing 210095China Beijing Xinfeng Aerospace Equipment Co. Ltd.Beijing 100854China Beijing System Design Institute of Electro-Mechanic Engineering Beijing 100005China College of Chemistry and Chemical Engineering Ningxia UniversityYinchuanNingxia 750021China

Bi_(2)O_(2)CO_(3)(BOC)/Bi_(4)O_5Br_(2)(BOB)/reduced graphene oxide(rGO)z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method.Ultra-thin nanosheets of BOC and BOB were grown in situ on r GO.The formed 2D/2D direct z-scheme heterojunction of BOC/BOB with oxygen vacancies(OVs)effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC,showing improved reduction/oxidation ability.Particularly,rGO is an acceptor of the electrons from the conduction band of BOC.Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation.With layered nanosheet structure,rich OVs,high specific surface area,and increased utilization efficiency of visible light,the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes,thereby generating more·O_(2)^(-)and h^(+).The photocatalytic reduction efficiency of CO_(2)to CO(12.91μmol/(g·hr))is three times higher than that of BOC(4.18μmol/(g·hr)).Moreover,it also achieved almost 100%removal of Rhodamine B and cyanobacterial cells within 2 hours.

关键词： Bi_(2)O_(2)CO_(3) Bi_(4)O_(5)Br_(2) Reduced graphene oxide z-scheme heterojunction Photocatalysis CO_(2)reduction

Case Studies of the Microphysical and Kinematic Structure of Summer Mesoscale Precipitation Clouds over the Eastern Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第1期41卷 97-114页

作者： Shuo JIA Jiefan YANG hengchi lei Key Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

Three cases of microphysical characteristics and kinematic structures in the negative temperature region of summer mesoscale cloud systems over the eastern Tibetan Plateau(TP)were investigated using X-band dual-polarization radar.The time-height series of radar physical variables and mesoscale horizontal divergence δderived by quasi-vertical profiles(QVPs)indicated that the dendritic growth layer(DGL,-20°C to-10°C)was ubiquitous,with large-value zones of K_(DP)(specific differential phase),z_(DR)(differential reflectivity),or both,and corresponded to various dynamic fields(ascent or descent).Ascents in the DGL of cloud systems with vigorous vertical development were coincident with large-value zones of z_(DR),signifying ice crystals with a large axis ratio,but with no obvious large values of K_(DP),which differs from previous findings.It is speculated that ascent in the DGL promoted ice crystals to undergo further growth before sinking.If there was descent in the DGL,a high echo top corresponded to large values of K_(DP),denoting a large number concentration of ice crystals;but with the echo top descending,small values of K_(DP) formed.This is similar to previous results and reveals that a high echo top is conducive to the generation of ice crystals.When ice particles fall to low levels(-10℃ to 0℃),they grow through riming,aggregation,or deposition,and may not be related to the kinematic structure.It is important to note that this study was only based on a limited number of cases and that further research is therefore needed.

关键词： Tibetan Plateau polarimetric variables microphysics dendritic growth layer kinematic structure aggregation riming

Revealing excited states of rotational Bose-Einstein condensates

在线全文

学校读者我要写书评

暂无评论

The Innovation 2024年第1期5卷 41-48页

作者： Jianyuan Yin zhen huang Yongyong Cai Qiang Du lei zhang School of Mathematical Sciences Laboratory of Mathematics and Applied MathematicsPeking UniversityBeijing 100871China Department of Mathematics National University of SingaporeSingapore 119076Singapore Department of Mathematics University of CaliforniaBerkeleyBerkeleyCA 94720USA School of Mathematical Sciences Beijing Normal UniversityBeijing 100875China Department of Applied Physics and Applied Mathematics and Data Science Institute Columbia UniversityNew YorkNY 10027USA Beijing International Center for Mathematical Research Center for Quantitative BiologyCenter for Machine Learning ResearchPeking UniversityBeijing 100871China

Rotational Bose-Einstein condensates can exhibit quantized vortices as topological excitations.In this study,the ground and excited states of the rotational Bose-Einstein condensates are systematically studied by calculating the stationary points of the Gross-Pitaevskii energy functional.Various excited states and their connections at different rotational frequencies are revealed in solution landscapes constructed with the constrained high-index saddle dynamics method.Four excitation mechanisms are identified:vortex addition,rearrangement,merging,and splitting.We demonstrate changes in the ground state with increasing rotational frequencies and decipher the evolution of the stability of ground states.

关键词： method rotational excited