检索结果-南通市图书馆

Dielectric nanocomposites with superb high-temperature capacitive performance based on high intrinsic dielectric constant polymer

引用

Nano Research 2024年第9期17卷 8504-8512页

作者： Ding Ai Yuan Chang Haoliang Liu Chenglong wu Yao Zhou Yuting Han Hao Yu Bing Xiao Yonghong Cheng Guanglei wu Zirui jia State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical EngineeringXi’an Jiaotong UniversityXi’an 710049China Institute of Materials for Energy and Environment State Key Laboratory of Bio-Fibers and Eco-TextilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China

Advancements in power electronics necessitate dielectric polymer films capable of operating at high temperatures and possessing high energy *** significant strides have been achieved by integrating inorganic fillers into high-temperature polymer matrices,the inherently low dielectric constants of these matrices have tempered the magnitude of *** this work,we report an innovative nanocomposite based on sulfonylated polyimide(SPI),distinguished by the incorporation of sulfonyl groups within the SPI backbone and the inclusion of wide bandgap hafnium dioxide(HfO_(2))*** nanocomposite has demonstrated notable enhancements in thermal stability,dielectric properties,and capacitive performance at elevated *** simulations at both molecular and mesoscopic levels have elucidated the mechanisms behind these improvements,which could be attributed to confined segmental motion,an optimized electronic band structure,and a diminished incidence of dielectric breakdown ascribed to the presence of sulfonyl ***,the SPI-HfO_(2)nanocomposite demonstrates a high charge-discharge efficiency of 95.7%at an elevated temperature of 150℃and an applied electric field of 200 MV/***,it achieves a maximum discharged energy density of 2.71 J/cm^(3),signalling its substantial potential for energy storage applications under extreme conditions.

关键词： dielectric polymer nanocomposites high-temperature high dielectric constant sulfonyl groups energy storage performance

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

Normalized glandular dose coefficients for digital breast tomosynthesis using detailed Chinese breast models

引用

Nuclear Science and Techniques 2024年第5期35卷 42-59页

作者： jia-Hao Wang Rui Qiu An-Kang Hu Ye-Qi Liu Zhen wu Hui Zhang Jun-Li Li Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging Ministry of EducationTsinghua UniversityBeijing 100084China Joint Institute of Tsinghua University Nuctech Company Limited BeijingBeijing 100084China

The rise in breast cancer diagnoses among Chinese women has necessitated the use of X-ray breast screening,which carries a radiation *** study aimed to provide a dosimetry protocol for the Chinese female population to replace the traditional standard that utilizes simplified breast models,for the accurate estimation of the mean glandular dose of a patient undergoing digital breast tomosynthesis(DBT).The first set of detailed Chinese female breast models and representative breast parameters was *** backscatter radiation and computational efficiency,we improved the combination of these models and the Chinese reference adult female whole-body voxel *** acquisition for four commercial DBT systems that are widely employed in China was simulated using the Monte Carlo method to obtain the normalized glandular dose coefficients of DBT(D_(gN)^(DBT))and the glandular depth dose(D_(g)^(dep)(z))for different breast characteristics and X-ray *** calculated a series of D_(gN)^(DBT) values for breasts with different percentage mass glandularities(5%,25%,50%,75%,and 100%)and compressed breast thicknesses(2,3,4,5,6,and 7 cm)at various tube potentials(25,28,30,32,35,and 49 kV)and target/filter combinations(W/Rh,W/Al,Mo/Mo,Rh/Rh,and Rh/Ag).The parameter dependence of the breast characteristics and beam conditions on D_(gN)^(DBT) in detailed breast models was *** D_(gN)^(DBT) results were 14.6-51.0%lower than those of the traditional dosimetry standard in *** difference in D_(gN)^(DBT) was mainly due to a decrease in the depth of the main energy deposition area caused by the glandular distribution along the depth *** results obtained in this study may be used to improve breast dosimetry in China and provide more detailed information on risk assessment during DBT.

关键词： Digital breast tomosynthesis Normalized glandular dose coefficients Detailed breast model Monte Carlo simulation

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

Graphitic carbons: preparation, characterization,and application on K-ion batteries

引用

Rare Metals 2024年第9期43卷 4056-4075页

作者： Kang-Zhe Cao jia-Hui Ma Yu-lian Dong Yu Duan Run-Tian Zheng Dharani Bundhooa Hui-Qiao Liu Yong Lei College of Chemistry and Chemical Engineering Xinyang Normal University Xinyang Key Laboratory of Low-Carbon Energy Materials Fachgebiet Angewandte Nanophysik Institut für Physik & IMN MacroNano Technische Universit?t Ilmenau Laboratory of Inorganic Materials Chemistry (CMI) University of NamurB-5000 Namur

K-ion batteries(KIBs) have drawn much attention due to the abundant potassium reserves and wide accessibility as well as high energy density, which can be designed for large-scale energy storage systems. As the most promising anode materials for KIBs, graphitic carbons, especially those with an intermediate structure between the crystalline graphite and amorphous carbons become a hot research focus because of the improved rate capability and enhanced diffusion-controlled capacity at low voltage regions. Herein, we first review the structures of graphitic carbons in the view of graphitic domains and the structure changes in their K-ion intercalation compounds. Then, we summarize the preparation mechanisms and characterizations of graphitic carbons and the influence factors in their degree of graphitization. Furtherly, we illustrate the strategies to optimize their K-ion storage properties from four aspects, namely graphitic domain design, microstructure engineering, electrochemical active component regulation, and defect engineering. Finally, we propose the issues that urgently need to be solved in graphitic carbons and the possible solutions. We hope that this view could offer some inspiration for the further designing and optimizing of graphitic carbons for practical KIBs.

关键词： Anodes

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

Generation of macroscopic entanglement in ensemble systems based on silicon vacancy centers

引用

Chinese Physics B 2024年第9期33卷 308-315页

作者： jian-Zhuang wu Ying Xi Bo-Ya Li lian-E Lu Yong-Hong Ma School of Science Inner Mongolia University of Science and TechnologyBaotou 014010China

Entanglement in macroscopic systems,as a fundamental quantum resource,has been utilized to propel the advancement of quantum technology and probe the boundary between the quantum and classical *** study focuses on a unique hybrid quantum system comprising of an ensemble of silicon vacancy(SiV)centers coupled to phononic waveguides in diamond via strain *** employing two sets of time-dependent,non-overlapping driving fields,we investigate the generation process and dynamic properties of macroscopic quantum entanglement,providing fresh insights into the behavior of such hybrid quantum ***,it paves the way for new possibilities in utilizing quantum entanglement as an information carrier in quantum information processing and quantum communication.

关键词： quantum entanglement silicon vacancy centers diamond waveguide

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

Experimental observation of spontaneous symmetry breaking in a quantum phase transition

引用

Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 34-39页

作者： Wen Ning Ri-Hua Zheng jia-Hao Lu Fan wu Zhen-Biao Yang Shi-Biao Zheng Fujian Key Laboratory of Quantum Information and Quantum Optics College of Physics and Information EngineeringFuzhou UniversityFuzhou 350108China Hefei National Laboratory Hefei 230088China

Spontaneous symmetry breaking(SSB)plays a central role in understanding a large variety of phenomena associated with phase transitions,such as superfluid and *** far,the transition from a symmetric vacuum to a macroscopically ordered phase has been substantially *** process bridging these two distinct phases is critical to understanding how a classical world emerges from a quantum phase transition,but so far remains unexplored in *** here report an experimental demonstration of such a process with a quantum Rabi model engineered with a superconducting *** move the system from the normal phase to the superradiant phase featuring two symmetry-breaking field components,one of which is observed to emerge as the classical *** results demonstrate that the environment-induced decoherence plays a critical role in the SSB.

关键词： quantum phase transition Rabi model spontaneous symmetry breaking superconducting circuit Schrodinger cat states

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

Self-assembly tungsten selenide hybrid ternary MOF derived magnetic alloys via multi-polarization to boost microwave absorption

引用

Nano Research 2024年第3期17卷 1625-1635页

作者： Tianbao Zhao Tingting Zheng Di Lan Yan Zhang Zhengshuo Sun Chao Wang Zirui jia Guanglei wu Institute of Materials for Energy and Environment State Key Laboratory of Bio-fibers and Eco-textilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China School of Materials Science and Engineering Hubei University of Automotive TechnologyShiyan 442002China College of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071China

Confronted with severe electromagnetic wave pollution,the development of high-performance electromagnetic wave shielding or absorbing materials is an effective way to deal with ***,double transition metal alloys and transition metal dichalcogenides have attracted extensive attention in electromagnetic wave absorption,but few reports have studied the effects of these two materials on electromagnetic wave absorption at the same *** this work,cobalt-based alloy with magnetic loss mechanism was selected for composition *** ternary metal-organic framework was prepared by the one-step method,and then CoCu/C was prepared by high temperature ***,in the hydrothermal process,ultra-thin tungsten selenide nanosheets were coated on the surface of magnetic component,and the final polyhedral WSe_(2)/CoCu/C composites with multiple heterogeneous interfaces were *** synergistic effect of dielectric and magnetic components optimizes impedance matching and allows more electromagnetic waves to enter the ***,through the conduction loss of high conductivity graphitized carbon,interfacial polarization,and dipole polarization of heterogeneous interfaces between the components,the magnetic loss provided by CoCu alloy can work together to maximize the attenuation ability of electromagnetic ***,the minimum reflection loss(RLmin)value of the composite reaches-53.43 dB when the matched thickness is 2.1 mm,while the maximum effective absorption bandwidth(EABmax)reaches 6.0 GHz at a thin thickness of 1.8 *** work provides some support and reference for the design of novel electromagnetic wave absorbing materials via the dielectric/magnetic loss synergistic mechanism.

关键词： metal-organic framework dielectric/magnetic loss transition metal dichalcogenide electromagnetic wave absorption

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

Understanding the cooperative effects in the catalysis of homodimeric fluoroacetate dehalogenase

引用

Science China Chemistry 2024年第7期67卷 2382-2391页

作者： Ke-Wei Chen jia-Nan Chen Jun Zhang Chao Wang Tian-Yu Sun Yun-Dong wu Key Laboratory of Computational Chemistry and Drug Design State Key Laboratory of Chemical OncogenomicSchool of Chemical Biology and BiotechnologyPeking University Shenzhen Graduate SchoolShenzhen 518055China Institute of Chemical Biology Shenzhen Bay LaboratoryShenzhen 518132China College of Chemistry and Molecular Engineering Peking UniversityBeijing 100871China Changping Laboratory Beijing 102200China

Fluoroacetate dehalogenases(FAcD),a homodimeric enzyme,catalyzes the conversion of fluoroacetic acid to glycolic acid(GoA).It has been proved that the enzyme has a half-of-the-site ***,its catalytic(C)subunit converts the first substrate to a covalent intermediate;then,the non-catalytic(NC)subunit binds a second substrate and promotes the conversion of the intermediate in the C subunit into the final *** the release of the product,the C subunit becomes the NC subunit,and the previous NC subunit becomes the C *** elucidate the detailed mechanism behind this cooperative catalysis,we have conducted microsecond-scale MD simulations along the reaction *** simulations indicate that the substrate in the NC subunit induces W185 and Y141 adopting an open conformation in the C *** opening of W185(C)facilitates the entry of catalytic water,enhancing the catalytic activity for product formation,while the opening of Y141(C)creates an unfavorable environment for product binding,promoting its *** interaction network analysis reveals that the substrate in the NC subunit can induce conformational changes through a conserved water chain at the interface.

关键词： enzyme catalysis molecular dynamics cooperative effect pre-reaction state

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

MOF‐derived 1D/3D N‐doped porous carbon for spatially confined electrochemical CO2 reduction to adjustable syngas

引用

Carbon Energy 2024年第8期6卷 1-13页

作者： Wei Zhang Hui Li Daming Feng Chenglin wu Chenghua Sun Baohua jia Xue Liu Tianyi Ma Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials Institute of Clean Energy ChemistryCollege of ChemistryLiaoning UniversityShenyangLiaoningChina School of Science RMIT UniversityMelbourneVictoriaAustralia School of Pharmaceutical and Chemical Engineering Taizhou UniversityTaizhouZhejiangChina Department of Chemistry and Biotechnology Swinburne University of TechnologyHawthornVictoriaAustralia

Electrochemical reduction of CO_(2)to syngas(CO and H_(2))offers an efficient way to mitigate carbon emissions and store intermittent renewable energy in ***,the hierarchical one‐dimensional/three‐dimensional nitrogen‐doped porous carbon(1D/3D NPC)is prepared by carbonizing the composite of Zn‐MOF‐74 crystals in situ grown on a commercial melamine sponge(MS),for electrochemical CO_(2)reduction reaction(CO_(2)RR).The 1D/3D NPC exhibits a high CO/H_(2)ratio(5.06)and CO yield(31 mmol g^(−1)h^(−1))at−0.55 V,which are 13.7 times and 21.4 times those of 1D porous carbon(derived from Zn‐MOF‐74)and N‐doped carbon(carbonized by MS),*** is attributed to the unique spatial environment of 1D/3D NPC,which increases the adsorption capacity of CO_(2)and promotes electron transfer from the 3D N‐doped carbon framework to 1D carbon,improving the reaction kinetics of CO_(2)*** results and charge density difference plots indicate that the active site of CO_(2)RR is the positively charged carbon atom adjacent to graphitic N on 1D carbon and the active site of HER is the pyridinic N on 1D *** presence of pyridinic N and pyrrolic N reduces the number of electron transfer,decreasing the reaction kinetics and the activity of CO_(2)*** CO/H_(2)ratio is related to the distribution of N species and the specific surface area,which are determined by the degree of spatial confinement *** CO/H_(2)ratios can be regulated by adjusting the carbonization temperature to adjust the degree of spatial confinement *** the low cost of feedstock and easy strategy,1D/3D NPC catalysts have great potential for industrial application.

关键词： electrochemical CO_(2)reduction reaction melamine sponge metal‐organic frameworks porous carbon syngas

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

Differential bonding behaviors of sodium/potassium-ion storage in sawdust waste carbon derivatives

引用

Chinese Chemical Letters 2024年第4期35卷 496-501页

作者： Jun-Ming Cao Kai-Yang Zhang jia-Lin Yang Zhen-Yi Gu Xing-Long wu MOE Key Laboratory for UV Light-Emitting Materials and Technology Northeast Normal UniversityChangchun 130024China Department of Chemistry Northeast Normal UniversityChangchun 130024China

Sodium-ion batteries(SIBs) and potassium-ion batteries(PIBs) are the most promising alternatives to lithium-ion batteries, and thus have drawn intensive research attention. Porous carbon materials from different precursors have been widely used as anode materials owing to their compatible storage effectiveness of both larger radii sodium and potassium ions. However, the differential bonding behaviors of Na and K ions with porous carbon-based anode are the significant one worth investigating, which could provide a clean picture of alkali ions storage mechanism. Therefore, in this work, we prepare a porous carbon network derived from sawdust(SDC) wastes, to further analyze the differences on sodium and potassium ions storage behaviors in terms of bond-forming process. It is found that, as-prepared SDC anodes could deliver stable sodium and potassium storage capacities, however, there are notable distinctions in terms of electrochemical behaviors and diffusion processes. By virtue of ex-situ XRD and Raman spectroscopy, the phase transition reaction of potassium ions could be well-observed, and the results shows that the multiple intercalated compounds was formed in SDC network during ions insertion, further resulting in slower diffusion kinetics and larger resistance compared to non-bonded process of sodium ions storage. This study provides more insights into the differences between sodium and potassium ions storage, as well as the energy storage mechanism of porous carbon as anodes for secondary batteries.

关键词： Porous carbon Sodium-ion storage Potassium-ion storage Bonding behaviors Batteries

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

Establishment of predictive models and determinants of preoperative gastric retention in endoscopic retrograde cholangiopancreatography

引用

World Journal of Gastrointestinal Surgery 2024年第8期16卷 2574-2582页

作者： Ying jia Hao-Jun wu Tang Li jia-Bin Liu Ling Fang Zi-Ming Liu Department of Thyroid Surgery West China HospitalSichuan UniversityChengdu 610041Sichuan ProvinceChina Division of Biliary Tract Surgery Department of General SurgeryWest China HospitalSichuan UniversityChengdu 610041Sichuan ProvinceChina Division of General Surgery West China Hospital-Chengdu Shangjin NanfuWest China HospitalChengdu 611730Sichuan ProvinceChina

BACKGROUND Study on influencing factors of gastric retention before endoscopic retrograde cholangiopancreatography(ERCP)background:With the wide application of ERCP,the risk of preoperative gastric retention affects the smooth progress of the *** study found that female,biliary and pancreatic malignant tumor,digestive tract obstruction and other factors are closely related to gastric retention,so the establishment of predictive model is very important to reduce the risk of *** A retrospective analysis was conducted on 190 patients admitted to our hospital for ERCP preparation between January 2020 and February *** baseline clinical data were collected using an electronic medical record *** were randomly matched in a 1:4 ratio with data from 190 patients during the same period to establish a validation group(n=38)and a modeling group(n=152).Patients in the modeling group were divided into the gastric retention group(n=52)and non-gastric retention group(n=100)based on whether gastric retention occurred *** data of patients in the validation group and identify factors influencing preoperative gastric retention in ERCP patients.A predictive model for preoperative gastric retention in ERCP patients was constructed,and calibration curves were used for *** receiver operating characteristic(ROC)curve was analyzed to evaluate the predictive value of the *** We found no statistically significant difference in general data between the validation group and modeling group(P>0.05).The comparison of age,body mass index,hypertension,and diabetes between the two groups showed no statistically significant difference(P>0.05).However,we noted statistically significant differences in gender,primary disease,jaundice,opioid use,and gastrointestinal obstruction between the two groups(P<0.05).Mul-tivariate logistic regression analysis showed that gender,primary disease,jaundice,opioid use,and gastrointestina

关键词： Cholangiopancreatography Gastric retention Influencing factors Predictive model Endoscope

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

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：