检索结果-南通市图书馆

Origin of the near-room temperature resistance transition in lutetium with H2/N2 gas mixture under high pressure

National science Review 2024年第7期11卷 26-32页

作者： Di Peng Qiaoshi Zeng Fujun Lan Zhenfang Xing Zhidan Zeng Xiaoxing Ke Yang Ding Ho-kwang Mao Key Laboratory of Materials Physics Institute of Solid State Physics Hefei Institutes of Physical Science(HFIPS)Chinese Academy of Sciences science Island Branch Graduate School of University of Science and Technology of China Center for High Pressure science and technology Advanced Research Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments(MFree) Shanghai Advanced Research in Physical Sciences(SHARPS) State Key Laboratory of Superhard Materials Institute of PhysicsJilin University College of Materials science&Engineering Beijing University of Technology

The recent report of room-temperature superconductivity at near-ambient pressure in nitrogen-doped lutetium hydride（Lu-H-N） by Dasenbrock-Gammon et al. [Nature 615, 244–250（2023）] has attracted tremendous attention due to its anticipated great impact on technology. However, the results could not be independently reproduced by other groups worldwide in follow-up studies, which elicited intense controversy. Here, we develop a reliable experimental protocol to minimize the extensively concerned extrinsic influences on the sample by starting the reaction from pure lutetium loaded with an H2/N2gas mixture in a diamond anvil cell under different pressures and temperatures and simultaneously monitoring the entire chemical reaction process using in situ four-probe resistance measurements. Therefore, we could repeatedly reproduce the near-room temperature upsurge of electrical resistance at a relatively early stage of the chemical reaction. However, the mechanism is suggested to be a metal-to-semiconductor/insulator transition associated with the structural modulation in the non-stoichiometric Lu-H-N, rather than superconductivity.

关键词： superconductivity high pressure lutetium hydride resistance transition metal-to-semiconductor/insulator transition

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Sequence structure controllable polymerization-induced self-assembly

引用

science China Chemistry 2024年第1期67卷 390-397页

作者： Zi-Xuan Chang Ren-Man Zhu Chun-Yan Hong Wen-Jian Zhang Department of Polymer science and Engineering University of Science and Technology of ChinaHefei 230026China institute of physical science and Information technology Anhui UniversityHefei 230601China Key Laboratory of Environment-Friendly Polymeric Materials of Anhui Province Anhui UniversityHefei 230601China

Polymerization-induced self-assembly(PISA)combines synthesis and self-assembly of artificial polymers in one-pot,which brings us one step closer to emulating ***,the reported PISA formulations primarily focus on developing nano-objects with new chemical compositions and rarely on structural regulation of polymers with specific ***,sequence structure controllable polymerization-induced self-assembly(SCPISA)is reported by using 7-(2-methacryloyloxyethoxy)-4-methylcoumarin(CMA)as a *** the copolymerization of 2-hydroxyethyl methacrylate(HEMA)and CMA,controlled incorporation of CMA units into the polymer chains can be realized by programmable light/heat ***-based P(HEMA-co-CMA)copolymers with the same composition but different sequence structures generate a range of ***,the morphologies of the resultant nano-objects can also be controlled by regulating the feed molar ratio of CMA and HEMA,which is similar to the conventional PISA,but the synthesis procedure is obviously simplified in *** versatility of the methodology is further demonstrated by the fabrication of different functional nano-objects with sequence structure-dependent morphologies in SCPISA systems with different functional monomers.

关键词： polymerization-induced self-assembly sequence-controlled polymers PET-RAFT polymerization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Pressure-induced hydrogen-dominant high-temperature superconductors

引用

National science Review 2024年第7期11卷 14-16页

作者： Ho-kwang Mao Shanghai Advanced Research in physical sciences Center for High Pressure science and technology Advanced Research

Recent studies of hydrogen-dominant（superhydride） materials have led to putative discoveries of near-room temperature superconductivity at high pressures. The idea started more than half-a-century ago as a by-product of the quest for metallic hydrogen for which a natural consequence of its very high Debye temperature and phonon frequency due to the very low mass of the hydrogen atoms would lead to a high superconducting critical temperature （Tc） in weak coupling Bardeen-Cooper-Schrieffer（BCS） expression.

关键词： HYDRIDE LANTHANUM

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Holevo bound independent of weight matrices for estimating two parameters of a qubit

引用

Chinese Physics B 2024年第2期33卷 137-143页

作者：牛畅郁司夏 Department of Modern Physics&Hefei National Research Center for physical sciences at the Microscale and School of physical sciences University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Holevo bound plays an important role in quantum metrology as it sets the ultimate limit for multi-parameter estimations,which can be asymptotically *** for some trivial cases,the Holevo bound is implicitly defined and formulated with the help of weight *** we report the first instance of an intrinsic Holevo bound,namely,without any reference to weight matrices,in a nontrivial ***,we prove that the Holevo bound for estimating two parameters of a qubit is equivalent to the joint constraint imposed by two quantum Cramér–Rao bounds corresponding to symmetric and right logarithmic *** weightless form of Holevo bound enables us to determine the precise range of independent entries of the mean-square error matrix,i.e.,two variances and one covariance that quantify the precisions of the estimation,as illustrated by different estimation *** result sheds some new light on the relations between the Holevo bound and quantum Cramer–Rao *** generalizations are discussed.

关键词： quantum metrology quantum Fisher information Holevo bound quantum multi-parameter estimation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

U-Net Inspired Deep Neural Network-Based Smoke Plume Detection in Satellite Images

引用

Computers, Materials & Continua 2024年第4期79卷 779-799页

作者： Ananthakrishnan Balasundaram Ayesha Shaik Japmann Kaur Banga Aman Kumar Singh Centre for Cyber physical Systems Vellore Institute of Technology(VIT)ChennaiTamil Nadu600127India School of Computer science and Engineering Vellore Institute of Technology(VIT)ChennaiTamil Nadu600127India

Industrial activities, through the human-induced release of Green House Gas (GHG) emissions, have beenidentified as the primary cause of global warming. Accurate and quantitative monitoring of these emissions isessential for a comprehensive understanding of their impact on the Earth’s climate and for effectively enforcingemission regulations at a large scale. This work examines the feasibility of detecting and quantifying industrialsmoke plumes using freely accessible geo-satellite imagery. The existing systemhas so many lagging factors such aslimitations in accuracy, robustness, and efficiency and these factors hinder the effectiveness in supporting timelyresponse to industrial fires. In this work, the utilization of grayscale images is done instead of traditional colorimages for smoke plume detection. The dataset was trained through a ResNet-50 model for classification and aU-Net model for segmentation. The dataset consists of images gathered by European Space Agency’s Sentinel-2 satellite constellation from a selection of industrial sites. The acquired images predominantly capture scenesof industrial locations, some of which exhibit active smoke plume emissions. The performance of the abovementionedtechniques and models is represented by their accuracy and IOU (Intersection-over-Union) *** images are first trained on the basic RGB images where their respective classification using the ResNet-50model results in an accuracy of 94.4% and segmentation using the U-Net Model with an IOU metric of 0.5 andaccuracy of 94% which leads to the detection of exact patches where the smoke plume has occurred. This work hastrained the classification model on grayscale images achieving a good increase in accuracy of 96.4%.

关键词： Smoke plume ResNet-50 U-Net geo satellite images early warning global monitoring

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Strain tunable excitonic optical properties in monolayer Ga_(2)O_(3)

引用

Chinese Physics B 2024年第10期33卷 366-370页

作者： Hao-Lei Cui Zhen Quan Shu-Dong Wang School of physical science and technology Inner Mongolia UniversityHohhot 010021China

Two-dimensional(2D)Ga_(2)O_(3)has been confirmed to be a stable structure with five atomic layer thickness *** this work,we study the quasi-particle electronic band structures and then access the excitonic optical properties through solving the Bethe-Salpeter equation(BSE).The results reveal that the exciton dominates the optical absorption in the visible light region with the binding energy as large as~1.0 eV,which is highly stable at room ***,both the dominant absorption P_(1)and P_(2)peaks are optically bright without dark exciton between them,and thus is favorable for luminescence *** calculated radiative lifetime of the lowest-energy exciton is 2.0×10^(-11)s at 0 ***,the radiative lifetime under+4%tensile strain is one order of magnitude shorter than that of the strainfree case,while it is less insensitive under the compressive *** findings set the stage for future theoretical and experimental investigation on monolayer Ga_(2)O_(3).

关键词： excitons radiative lifetime Ga_(2)O_(3)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Enhancing Strength-Ductility Synergy of CoCrNi-Based Medium-Entropy Alloy Through Coherent L1_(2)Nanoprecipitates and Grain Boundary Precipitates

引用

Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 78-88页

作者： Leilei Li Kaikai Song Qingwei Gao Changshan Zhou Xiaoming Liu Yaocen Wang Xiaojun Bai Chongde Cao School of physical science and technology Northwestern Polytechnical UniversityXi’an710016China Weihai Research institute of Industrial technology Shandong UniversityWeihai264209China Research and Development institute of Northwestern Polytechnical University in ShenzhenShenzhen518057China

The L1_(2)-strengthened Co_(34)Cr_(32)Ni_(27)Al_(4)Ti_(3)medium-entropy alloy(MEA)with precipitations of grain boundaries has been developed through selective laser melting(SLM)followed by cold rolling and annealing,exhibiting excellent strength-ductility *** as-printed alloy exhibits low yield strength(YS)of~384 MPa,ultimate tensile strength(UTS)of~453 MPa,and uniform elongation(UE)of 1.5%due to the existence of the SLM-induced *** cold rolling and annealing,the YS,UTS,and UE are significantly increased to~739 MPa,~1230 MPa,and~47%,*** enhancement primarily originates from the refined grain structure induced by cold rolling and *** presence of coherent sphericalγ'precipitates(L1_(2)phases)and Al/Ti-rich precipitates at the grain boundaries,coupled with increased lattice defects such as dislocations,stacking faults,and ultrafine deformation twins,further contribute to the property’s *** study highlights the potential of SLM in producing high-strength and ductile MEA with coherent L1_(2)nanoprecipitates,which can be further optimized through subsequent rolling and annealing *** findings offer valuable insights for the development of high-performance alloys for future engineering applications.

关键词： Medium-entropy alloy Selective laser melting Precipitation Strength Ductility

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Regulating atomic Fe-Rh site distance for efficient oxygen reduction reaction

引用

science China Chemistry 2024年第4期67卷 1352-1359页

作者： Tong Liu Yudan Chen Airong Xu Xiaokang Liu Dong Liu Sicheng Li Hui Huang Li Xu Shuaiwei Jiang Qiquan Luo Tao Ding Tao Yao National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Key Laboratory of Precision and Intelligent Chemistry Hefei National Research Center for Physical Sciences at the MicroscaleUniversity of Science and Technology of ChinaHefei 230026China institutes of physical science and Information technology Anhui UniversityHefei 230601China

Exploring the atomic interaction mechanisms of dense single-atom catalysts(SACs)is of great significance for their application in oxygen reduction reaction(ORR).However,the intrinsic mechanism of the site-distance effect on the catalytic performance has been largely ***,we demonstrate the site-distance effect of Fe-Rh_(x)@NC catalysts in ORR theoretically and *** charge analysis reveals that the strong interaction between Fe and Rh atoms at a certain atomic distance(dFe-Rh)alters the catalytic electronic structure,facilitating the optimization of catalyst adsorption *** by the theoretical calculations,we designed and synthesized the Fe-Rhx@NC catalysts through a spatial confinement *** characterization results prove that the Fe-Rh_(2)@NC has the optimal d_(Fe-Rh),which improves its intrinsic ORR activity,providing a half wave potential of 0.91 V,higher than that of the commercial Pt/C(0.86 V).This study emphasizes the importance of determining the basic mechanism of the site-distance effect in dissimilar metal atoms catalysts,which is conducive to the design of efficient catalyst systems for practical applications.

关键词： Density functional theory single-atom catalyst in-situ encapsulating site-distance effect oxygen reduction reaction

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Excitonic optical properties in monolayer SnP_(2)S_(6)

引用

Chinese Physics B 2024年第10期33卷 371-375页

作者： Peng-Yuan Chen Zhen Quan Shu-Dong Wang School of physical science and technology Inner Mongolia UniversityHohhot 010021China

Quantum confinement effect and reduced dielectric screening in two-dimensional(2D)dramatically enhance theelectron-hole *** this work,we use many-body perturbation theory and Bethe-Salpeter equation(BSE)toinvestigate the electronic and excitonic optical properties of monolayer SnP_(2)S_(6).Our findings reveal that the excitoniceffect dominates the optical absorption spectra in the visible light range,and the lowest-energy exciton X0 in monolayerSnP_(2)S_(6)is optically bright with the binding energy of 0.87 eV and the radiative lifetime of~10^(-11)s,which is highly advantageousto the *** importantly,the absence of optically forbidden states below the bright statesX0 would give rise to a high quantum efficiency of 2D SnP_(2)S_(6).We also find that applied biaxial strain can further shortenthe radiative lifetime of the bright *** results imply that 2D SnP_(2)S_(6)is a promising candidate for the optoelectronicdevices.

关键词： excitons radiative lifetime SnP_(2)S_(6)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Multi-region calcium imaging in freely behaving mice with ultra-compact head-mounted fluorescence microscopes

引用

National science Review 2024年第1期11卷 161-173页

作者： Feng Xue Fei Li Ke-ming Zhang Lufeng Ding Yang Wang Xingtao Zhao Fang Xu Danke Zhang Mingzhai Sun Pak-Ming Lau Qingyuan Zhu Pengcheng Zhou Guo-Qiang Bi Department of Precision Machinery and Precision Instruments University of Science and Technology of China Hefei National Laboratory for physical sciences at the Microscale University of Science and Technology of China Interdisciplinary Center for Brain Information the Brain Cognition and Brain Disease Institute Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Faculty of Life and Health sciences Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences School of Life sciences University of Science and Technology of China institute of Semiconductors Chinese Academy of Sciences Department of Modern Life sciences and Biotecnology Xiongan Institute of Innovation Xiongan New Area Shenzhen-Hong Kong institute of Brain science-Shenzhen Fundamental Research Institutions Suzhou institute for Advanced Research University of Science and Technology of China institute of Artiflcial Intelligence Hefei Comprehensive National Science Center

To investigate the circuit-level neural mechanisms of behavior, simultaneous imaging of neuronal activity in multiple cortical and subcortical regions is highly desired. Miniature head-mounted microscopes offer the capability of calcium imaging in freely behaving animals. However, implanting multiple microscopes on a mouse brain remains challenging due to space constraints and the cumbersome weight of the ***, we present TINIscope, a Tightly Integrated Neuronal Imaging microscope optimized for electronic and opto-mechanical design. With its compact and lightweight design of 0.43 g, TINIscope enables unprecedented simultaneous imaging of behavior-relevant activity in up to four brain regions in ***-of-concept experiments with TINIscope recorded over 1000 neurons in four hippocampal subregions and revealed concurrent activity patterns spanning across these regions. Moreover, we explored potential multi-modal experimental designs by integrating additional modules for optogenetics, electrical stimulation or local field potential recordings. Overall, TINIscope represents a timely and indispensable tool for studying the brain-wide interregional coordination that underlies unrestrained behaviors.

关键词： miniature microscope multiple sites calcium imaging multimodal integration hippocampus

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：