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Towards wafer-scale growth of two-dimensional cerium dioxide single crystal with high dielectric performance

Nano Research 2024年第9期17卷 8592-8599页

作者： Zhuofeng Shi Muhammad Imran Xiaohui Chen xin liu Yaqi Zhu Zhaoning Hu Saiyu Bu Jialin {3. Chunhu li xiaodong {3. li lin College of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266000China School of Materials Science and Engineering Peking UniversityBeijing 100871China Center for Nanochemistry Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular ScienceCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationCollege of Chemistry and Chemical EngineeringOcean University of ChinaQingdao 266100China

Owing to the atomically thin nature,two-dimensional(2D)oxide materials have been widely reported to exhibit exciting transport and dielectric properties,such as fine gate controllability and ultrahigh carrier mobility,that outperform their bulk ***,unlike the successful synthesis of bulk oxide single crystals,reliable methods for synthesizing large-area single crystal of 2D oxide,that would suppress the negative influence from defective grain boundaries,remain unavailable,especially for nonlayered ***,we report that the lattice symmetry between the substrate and cerium dioxide(CeO_(2))would allow for the aligned nucleation and epitaxial growth of CeO_(2)on sapphire substrates,enabling the wafer-sized growth of CeO_(2)single *** careful tuning of the growth temperature and oxygen flow rate contributed to the harvesting of CeO_(2)wafer with reduced thickness and enhanced growth *** removal of grain boundaries improved the dielectric performance in terms of high dielectric strength(E_(bd)≈8.8 MV·cm^(-1)),suppressed leakage current,along with high dielectric constants(ε_(r)≈24).Our work demonstrates that with fine dielectric performance and ease of synthesizing wafer-sized single crystals,CeO_(2)can function as potential candidate as gate insulator for 2D-materials based nanoelectronics,and we believe the reported protocol of aligned nucleation can be extended to other 2D oxides.

关键词： dielectric materials two-dimensional materials chemical vapor deposition cerium dioxide

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Single-atom-mediated electron islands boost photocatalytic CO_(2)chemical fixation

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Science china Chemistry 2024年第7期67卷 2292-2299页

作者： Shu Shang Lei li xin He Hui Wang lirong Zheng Wei Shao {3. zhang Yi Xie Hefei National Research Center for Physical sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institute of Energy Hefei Comprehensive National Science CenterHefei 230031China beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Chemistry and Chemical Engineering Hefei Normal UniversityHefei 230031China

Photocatalytic cycloadditions of CO_(2)with epoxides are emerging as a significant platform for the green synthesis of valuable carbonates,where efficient catalytic systems with spatially separated charge carriers are ***,a single p-block metal atom is proposed to be a candidate for photogenerated electron localization on a metal oxide *** taking the Bi single-atom supported on ZnO nanosheet(Bi1/ZnO)as an example,we show that the Bi atom plays the role of an electron island in the sea of delocalized holes within ***,the as-formed electron island could readily promote the rate-determining ring-opening process of cycloaddition *** from the unique spatially separated electrons and holes,the Bi1/ZnO achieves a high yield of cyclic carbonates with almost 100%*** study provides a pioneering strategy for enhancing the performances of photocatalytic CO_(2)chemical fixation.

关键词： electron islands CO_(2)photofixation photogenerated charge carriers

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Effect of Interface Form on Creep Failure and life of Dissimilar Metal Welds Involving Nickel-Based Weld Metal and Ferritic Base Metal

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chinese Journal of Mechanical Engineering 2024年第1期37卷 265-285页

作者： Xiaogang li Junfeng Nie xin Wang Kejian li Haiquan {3. Institute of Nuclear and New Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China

For dissimilar metal welds(DMWs)involving nickel-based weld metal(WM)and ferritic heat resistant steel base metal(BM)in power plants,there must be an interface between WM and BM,and this interface suffers mechanical and microstructure mismatches and is often the rupture location of premature *** this study,a new form of WM/BM interface form,namely double Y-type interface was designed for the *** behaviors and life of DMWs containing double Y-type interface and conventional I-type interface were compared by finite element analysis and creep tests,and creep failure mechanisms were investigated by stress-strain analysis and microstructure *** applying double Y-type interface instead of conventional I-type interface,failure location of DMW could be shifted from the WM/ferritic heat-affected zone(HAZ)interface into the ferritic HAZ or even the ferritic BM,and the failure mode change improved the creep life of *** interface premature failure of I-type interface DMW was related to the coupling effect of microstructure degradation,stress and strain concentrations,and oxide notch on the WM/HAZ *** creep failure of double Y-type interface DMW was the result of Type IV fracture due to the creep voids and micro-cracks on fine-grain boundaries in HAZ,which was a result of the matrix softening of HAZ and lack of precipitate pinning at fine-grain *** double Y-type interface form separated the stress and strain concentrations in DMW from the WM/HAZ interface,preventing the trigger effect of oxide notch on interface failure and inhibiting the interfacial microstructure *** is a novel scheme to prolong creep life and enhance reliability of DMW,by means of optimizing the interface form,decoupling the damage factors from WM/HAZ interface,and then changing the failure mechanism and shifting the failure location.

关键词： Dissimilar metal weld Nickel-based weld metal Ferritic heat resistant steel Interface Creep strain Microstructure Failure mechanism Creep life

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Fabrication of MXene-Bi_(2)WO_(6)heterojunction by Bi_(2)Ti_(2)O_(7)hinge for extraordinary LED-light-driven photocatalytic performance

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Nano Research 2024年第6期17卷 4729-4736页

作者： Zhiwen li liangliang Xu Zaheer Ud Din Babar Ali Raza Yifei zhang xinrui Gu Yu-xin miao Zhen Zhao Gao li Institute of Catalysis for Energy and Environment College of Chemistry and Chemical EngineeringShenyang Normal UniversityShenyang 110034China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Scuola Superiore Meridionale(SSM) University of Naples Federico IILargo S.Marcellino1080138Italy Department of Chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea University of chinese academy of sciences Beijing 100049China

Heterojunction composites with intimate interfaces can shorten the diffusion distance,which leads to a shorter path for photogenerated carriers,thereby increasing photocatalytic ***,we report the fabrication of Ti_(3.C_(2)-Bi_(2)WO_(6)(TC-BW)heterojunctions hinged by Bi_(2)Ti_(2)O_(7)joints via an in situ hydrothermal reaction of Ti_(3.C_(2)in the presence of Na_(2)WO_(4)and Bi(NO_(3.)_(3..The TC-BW was characterized using X-ray diffraction(XRD),scanning transmission electron microscopy(STEM),and Raman ***-BW showed superior photocatalytic activity(productivity over 15TC-WB reaches up to 5.0 mmolreacted BA·gcat.^(−1)·h^(−1))in the oxidation of benzyl alcohol using light-emitting diode(LED)light,arising from the surface defects and intimate heterojunction interface between the Ti_(3.C_(2)MXene and Bi_(2)WO_(6)***-BW heterojunctions provide an enhanced separation efficiency of photogenerated charges,which in turn yields superior photocatalytic ***,it is well substantiated by density functional theory(DFT)*** summary,this study elucidates the preparation of heterojunction composites with intimate interfaces for highly efficient photooxidation.

关键词： MXene-Bi_(2)WO_(6) heterojunction LED-light-driven photocatalysis Bi_(2)Ti_(2)O_(7) photooxidation

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Failure Analysis of Dissimilar Metal Welds between Ferritic Heat Resistant Steels and Austenitic Stainless Steels in Power Plant

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chinese Journal of Mechanical Engineering 2024年第4期37卷 306-326页

This study analysed the failure of dissimilar metal welds(DMWs)between ferritic heat resistant steels and austenitic stainless steels and investigated its influencing factors by means of numerical simulation,microstructure characterization and mechanical property *** the long-term high-temperature service condition in practical power plant,the DMW failure mode was along the interface between nickel-based weld metal(WM)and ferritic heat resistant steel,and the failure mechanism was stress/strain concentration,microstructure degradation and oxidation coupling acting on the *** numerical simulation results show that interface stress/strain concentration was due to the differences in coefficient of thermal expansion and creep strength,and the degree of stress/strain concentration was related to service *** ferrite band formed at the WM/ferritic steel interface was prone to cracking,attracting the fracture along the *** interface crack allowed oxidation to develop along the WM/ferritic steel *** long-term service,the interface stress/strain concentration,microstructure and oxidation all evolved,which synergistically promoted interface failure of ***,only under the long-term service of low stress conditions could trigger the interface failure of ***,long-term service would reduce the mechanical strength and plasticity of DMW.

关键词： Dissimilar metal weld Failure Interface Stress/strain concentration Microstructure Oxidation

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A quantum-enhanced magnetometer using a single high-spin nucleus in silicon

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chinese Physics B 2024年第9期33卷 110-115页

作者： Tao xin Ke zhang Jun li Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Physikalisch-Technische Bundesanstalt Bundesallee 10038116 BraunschweigGermany Institute of Quantum Precision Measurement State Key Laboratory of Radio Frequency Heterogeneous IntegrationShenzhen UniversityShenzhen 518060China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China

Quantum enhanced metrology has the potential to go beyond the standard quantum limit and eventually to the ultimate Heisenberg *** particular,quantum probes prepared in nonclassical coherent states have recently been recognized as a useful resource for ***,there has been considerable interest in constructing magnetic quantum sensors that combine high resolution and high ***,we explore a nanoscale magnetometer with quantum-enhanced sensitivity,based on 123.b(I=7/2)nuclear spin doped in silicon,that takes advantage of techniques of spin-squeezing and coherent *** the optimal squeezed initial state,the magnetic field sensitivity may be expected to approach 6 aT·Hz^(−1/2)·cm^(−3.2) and 603.nT·Hz^(−1/2) at the single-spin *** magnetic sensor may provide a novel sensitive and high-resolution route to microscopic mapping of magnetic fields as well as other applications.

关键词： quantum magnetometer silicon quantum qubit nuclear electrical resonance

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Threshold Selection and Resource Allocation for Quantized Identification

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Journal of Systems Science & Complexity 2024年第1期37卷 204-229页

作者： WANG Ying li xin ZHAO Yanlong zhang Ji-Feng Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical sciences University of Chinese Academy of SciencesBeijing 100049China

This paper is concerned with the optimal threshold selection and resource allocation problems of quantized identification, whose aims are improving identification efficiency under limited resources. Firstly, the first-order asymptotically optimal quantized identification theory is extended to the weak persistent excitation condition. Secondly, the characteristics of time and space complexities are established based on the Cramér-Rao lower bound of quantized systems. On these basis, the optimal selection methods of fixed thresholds and adaptive thresholds are established under aperiodic signals, which answer how to achieve the best efficiency of quantized identification under the same time and space complexity. In addition, based on the principle of maximizing the identification efficiency under a given resource, the optimal resource allocation methods of quantized identification are given for the cases of fixed thresholds and adaptive thresholds, respectively, which show how to balance time and space complexity to realize the best identification efficiency of quantized identification.

关键词： Quantized output resource allocation system identification threshold selection.

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Hybrid model for BOF oxygen blowing time prediction based on oxygen balance mechanism and deep neural network

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 106-117页

作者： xin Shao Qing liu Zicheng xin Jiangshan {3. Tao Zhou Shaoshuai li State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Engineering Research Center of MES Technology for Iron&Steel Production Ministry of EducationBeijing 100083China Laiwu Iron and Steel Group Yinshan Section Steel Co. Ltd.Jinan 271104China

The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in converter. A three-step method was utilized in the hybrid model. First, the oxygen consumption volume was predicted by the OBM model and DNN model, respectively. Second, a more accurate oxygen consumption volume was obtained by integrating the OBM model and DNN model. Finally, the converter oxygen blowing time was calculated according to the oxygen consumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data collected from an integrated steel plant in china, and compared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3.hidden layer layers, 3.-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability compared with other models. The predicted hit ratio of oxygen consumption volume within the error±3.0 m^(3.is 96.67%;determination coefficient (R^(2)) and root mean square error (RMSE) are0.6984 and 150.03.m^(3., respectively. The oxygen blow time prediction hit ratio within the error±0.6 min is 89.50%;R2and RMSE are0.9486 and 0.3.92 min, respectively. As a result, the proposed model can effectively predict the oxygen consumption volume and oxygen blowing time in the converter.

关键词： basic oxygen furnace oxygen consumption oxygen blowing time oxygen balance mechanism deep neural network hybrid model

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Influence of Sub-Cloud Secondary Evaporation Effects on the Stable Isotopes in Precipitation of Urumqi Glacier No.1,Eastern Tianshan

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Journal of Earth Science 2024年第1期35卷 177-189页

作者： Mengyuan Song Zhongqin li Feiteng Wang xin zhang State Key Laboratory of Cryospheric sciences Northwest Institute of Eco-Environment and ResourcesTianshan Glaciological StationChinese Academy of SciencesLanzhou 730000China College of Geography and Environmental Science Northwest Normal UniversityLanzhou 730000China College of sciences Shihezi UniversityShihezi 832000China

In arid regions,the stable hydrogen and oxygen isotopic composition in raindrops is often modified by sub-cloud secondary evaporation when they descend from cloud base to ground through the unsaturated *** a result of kinetic fractionation,the slope and intercept of the δ^(2)H-δ^(18)O correlation equation *** variation of deuterium excess from cloud base to the ground is often used to quantitatively evaluate the influence of secondary evaporation effect on isotopes in *** on the event-based precipitation samples collected at Urumqi Glacier No.1,eastern Tianshan during four-year observation,the existence and impact of secondary evaporation effects were analyzed by the methods of isotope-evaporation *** high air temperature,small raindrop diameter and precipitation amount,and low relative humidity conditions,the remaining rate of raindrops is small and the change of deuterium excess is large relatively,and the slope and intercept of δ^(2)H-δ^(18)O correlation equation are much lower than those of Global Meteoric Water line,which mean that the influence secondary evaporation on precipitation *** on the conditions of low air temperature,high relative humidity,heavy rainfall,and large raindrop diameter,the change of deuterium excess is small relatively and the remaining rate of raindrops is large,and the slope and intercept of δ^(2)H-δ^(18)O correlation equation increase,the secondary evaporation is *** isotope-evaporation model described a good linear correlation between changes of deuterium excess and evaporation proportion with the slope of 0.90‰/%,which indicated that an increase of 1%in evaporation may result in a decrease of deuterium excess about 0.90‰.

关键词： stable isotopes meteoric water line deuterium excess sub-cloud secondary evaporation effect precipitation glaciers

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Height and body mass index trajectories from 1975 to 2015 and prevalence of stunting,underweight and obesity in 2016 among children in chinese cities:findings from five rounds of a national survey

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World Journal of Pediatrics 2024年第4期20卷 404-412页

作者： xin‑Nan Zong Hui li Ya‑Qin zhang Department of Growth and Development Capital Institute of PediatricsBeijing 100020China

Background A more comprehensive assessment of growth and nutrition in children is required in china due to rapid socioeconomic *** aimed to investigate height and body mass index(BMI)trajectories from 1975 to 2015 and the prevalence of stunting and obesity in 2016 among children in chinese *** A total of 904,263.children from birth to 6.9 years were collected from a series of nationally representative surveys in *** and BMI trajectories and prevalence of stunting,underweight,overweight and obesity were *** The average height level of chinese urban children under 7 years presented a positive secular trend from 1975 to 2015;however,a slowing tendency occurred in 2005‒*** apparent increase was observed at the 5th,50th and 95th percentiles of BMI in urban children aged 3.years and older,with a more prominent increase at the 95th *** total prevalence of stunting and underweight under 7 years was 1.4%and 2.0%,*** total prevalence of overweight and obesity under 7 years was 12.6%and 4.3.,respectively,with 12.7%and 4.9%for boys,12.6%and 3.6%for girls,12.1%and 4.0%in urban areas and 13.1%and 4.5%in suburban rural *** The average height level of chinese urban children has reached World Health Organization child growth standards since 2005 and presented a slowing tendency in secular trend in 2005‒*** attention and efforts and public health interventions should be urgently made to combat overweight and obesity among preschool children.

关键词： Body mass index Children Height Obesity Stunting

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