检索结果-南通市图书馆

Phase Transitions in Neutron Stars Within Modified Quark-Meson Coupling Model

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第7期50卷 180-186页

作者： ma chang-Qun GAO Chun-Yuan School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China

K^- condensation and quark deconfinement phase transitions in neutron stars are investigated. We use the modified quark-meson coupling model for hadronic phase and the MIT bag model for quark phase. With the equation of state （EOS） solved self-consistently, we discuss the properties of neutron stars. We find that the EOS of pure hadron matter with condensed K- phase should be ruled out by the redshift for star EX00748-676, while EOS containing unpaired quark matter phase with B1/4 being about 180 MeV could be consistent with both this observation and the best measured mass of star PSR 1913 ＋ 16. But if the recent inferred massive star among Terzan 5 with M 〉 1.68M is confirmed, all the present EOSes with condensed phase and deconfined phase would be ruled out.

关键词： neutron star modified quark-meson coupling model nuclear matter quark matter

An accelerated augmented Lagrangian method for linearly constrained convex programming with the rate of convergence O(1/k^2)

在线全文

学校读者我要写书评

暂无评论

Applied mathematics(A Journal of Chinese Universities) 2017年第1期32卷 117-126页

作者： KE Yi-fen ma chang-feng School of mathematics and Computer Science & FJKLmaA Fujian Normal University Fuzhou 350117 China.

In this paper, we propose and analyze an accelerated augmented Lagrangian method（denoted by AALM） for solving the linearly constrained convex programming. We show that the convergence rate of AALM is O（1/k^2） while the convergence rate of the classical augmented Lagrangian method（ALM） is O1 k. Numerical experiments on the linearly constrained 1-2minimization problem are presented to demonstrate the effectiveness of AALM.

关键词： convex augmented constrained minimization accelerated Lagrangian linearly iteration sparse stopping

Ultrathin and Flexible CNTs/MXene/Cellulose Nanofibrils Composite Paper for Electromagnetic Interference Shielding

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2019年第4期11卷 276-292页

作者： Wentao Cao chang ma Shuo Tan Mingguo ma Pengbo Wan Feng Chen Department of Orthopedics Shanghai Tenth People’s HospitalTongji University School of MedicineShanghai 200072People’s Republic of China Engineering Research Center of Forestry Biomass materials and Bioenergy Beijing Key Laboratory of Lignocellulosic ChemistryCollege of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083People’s Republic of China Center of Advanced Elastomer materials State Key Laboratory of Organic-Inorganic CompositesBeijing University of Chemical TechnologyBeijing 100029People’s Republic of China

As the rapid development of portable and wearable devices,different electromagnetic interference(EMI)shielding materials with high efficiency have been desired to eliminate the resulting radiation ***,limited EMI shielding materials are successfully used in practical applications,due to the heavy thickness and absence of sufficient strength or ***,an ultrathin and flexible carbon nanotubes/MXene/cellulose nanofibrils composite paper with gradient and sandwich structure is constructed for EMI shielding application via a facile alternating vacuum-assisted filtration *** composite paper exhibits outstanding mechanical properties with a tensile strength of 97.9±5.0 MPa and a fracture strain of 4.6±0.2%.Particularly,the paper shows a high electrical conductivity of 2506.6 S m?1 and EMI shielding effectiveness(EMI SE)of 38.4 dB due to the sandwich structure in improving EMI SE,and the gradient structure on regulating the contributions from reflection and *** strategy is of great significance in fabricating ultrathin and flexible composite paper for highly efficient EMI shielding performance and in broadening the practical applications of MXene-based composite materials.

关键词： MXene Carbon nanotubes Cellulose nanofibrils Mechanical property Electromagnetic interference shielding

Lattice Bhatnagar-Gross-Krook Simulations in 2-D Incompressible magnetohydrodynamics

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2005年第5X期44卷 917-920页

作者： ma chang-Feng SHI Bao-chang CHEN Xing-Wang College of mathematics and Physics Zhejiang Normal University Jinhua 321004 China Department of Comput. Sci. and math. Guilin University of Electron. Tech. Guilin 541004 China Department of mathematics Huazhong University of Science and Technology Wuhan 430074 China

Lattice Boltzmann Method is recently developed within numerical schemes for simulating a variety of physical systems. In this paper a new lattice Bhatnagar-Gross-Krook (LBGK) model for two-dimensional incompressible magnetohydrodynamics (IMHD) is presented. The model is an extension of a hydrodynamics lattice BGK model with 9 velocities on a square lattice, resulting in a model with 17 velocities. Most of the existing LBGK models for MHD can be viewed as compressible schemes to simulate incompressible flows. The compressible effect might lead to some undesirable errors in numerical simulations. In our model the compressible effect has been overcome successfully. The model is then applied to the Hartmann flow, giving reasonable results.

关键词： lattice BGK model incompressible magnetohydrodynamics

Synthesis of 3-Methylbutanal by Strecker Reaction at Unelevated Temperature and in Acidic Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2006年第8期17卷 1041-1044页

作者： Hong Xia BI chang Wei ma College of Food Science ＆ Nutrition Engineering China Agricultural University Beijing 100083

3-Methylbutanal was obtained by the Strecker reaction with L-leucine and D-ribose at unelevated temperature and acidic conditions. Volatile compounds from reaction systems were analyzed by solid phase microextration （SPME） coupledwith gas chromatography-mass spectroscopy （GC-MS）. The formation mechanism of 3-methylbutanal was also proposed. Various reaction conditions were investigated, including reaction time, reaction temperature, pH value and salt content of the system.

关键词： 3-Methylbutanal Strecker reaction dry cured ham.

Atrial fibrillation and frailty

在线全文

学校读者我要写书评

暂无评论

Journal of Geriatric Cardiology 2020年第2期17卷 105-109页

作者： Qi GUO Xin DU chang-Sheng ma Department of Cardiology Beijing Anzhen HospitalCapital Medical UniversityNational Clinical Research Center for Cardiovascular DiseasesBeijing Advanced Innovation Center for Big Data-Based Precision Medicine for Cardiovascular Diseases

Both the prevalence of atrial fibrillation(AF)and frailty are increasing with age,and they often occur simultaneously,leading them to become the central concerns in this aging *** incidence of frailty in patients with AF is highly variable,ranging from 4.4%to 75.4%,depending on different evaluating instruments ***,the incidence of frailty among patients with AF is on the rise,which indicated that patients with AF are more prone to frailty compared to patients without *** relationship between AF and frailty is *** elevates the risk of stroke and mortality in AF patients and is also associated with longer *** the other hand,it may reduce the appropriate anticoagulation in AF ***,the evidence of the effects of frailty on anti-arrhythmic and interventional therapy in patients with AF is *** affects both the management and the prognosis of AF in the geriatric *** versa,AF could worsen the frail state and may represent a marker of ***,there are still questions need to be resolved,for example,the impact of frailty on the interventional therapy of patients with ***,the geriatric assessment of frailty should be considered when planning individualized management of AF in older patients.

关键词： Atrial fibrillation Epidemiology Frailty management Prognosis

Preparation of high-rate anode materials based on porous highly conductive carbon coating and SiOx disproportionation reaction

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:materials International 2024年第4期34卷 739-746页

作者： Haihui Liu Qiang Xu Xiao Zhang Shuliang Lv chang ma State Key Laboratory of Separation Membranes and Membrane Processes Tianjin Key Laboratory of Advanced Fibers and Energy Storage School of Materials Science and Engineering Tiangong University

Silicon monoxide（SiOx） has garnered considerable attention as an anode material owing to its high ***, its commercial viability is hampered by the low conductivity and inadequate cycling stability. In this study, a micrometer-scale silicon oxide/carbon composite（1000-SiOx/NC） was developed based on the porous and high electrical conductivity of pyrolyzed polydopamine（PDA） and the high-temperature disproportionation of SiOx. Electrochemical impedance spectroscopy（EIS） and X-ray photoelectron spectroscopy（XPS）analyses confirmed that the pyrolysis of polydopamine（PDA） not only improves electrode conductivity but also contributes to the formation of a stable solid electrolyte interface（SEI）. Additionally, SiOxundergoes disproportionation reactions during the pyrolysis of PDA, further the improves the cyclic stability of the ***, the 1000-SiOx/NC composite electrode exhibited an impressive specific capacity of 783.4 mah·g-1after 500 cycles at 1 A g-1, maintaining 80.1 % of its initial capacity. Additionally, at a high rate of 3 C, its capacity reached 607.3 mah·g-1The synthesis approach is both straightforward and economical, offering a fresh avenue for the widespread commercial deployment of SiOx.

关键词： Lithium-ion batteries Nitrogen doping 1000-SiO/NC anode Porous structure

Conjugated dendritic oligothiophenes for solution-processed bulk heterojunction solar cells

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2011年第1期4卷 12-23页

作者： chang-Qi ma Institute of Organic Chemistry II and Advanced materials Ulm University

This mini-review summarizes the recent achievements of developing conjugated dendritic oligothiophenes(DOT) for use in solution-processed bulk heterojunction(BHJ) solar cells. These DOTs are structurally defined molecules with relatively high molecular weight. Therefore, this novel class of thiophene based material possesses not only some advantages of oligomers,such as defined and monodispersed molecular structure,high chemical purity, but also some characteristics of polymers, for example, good *** addition, the step-by-step approach of its synthesis allows precise functionalization of dendritic backbones with desired moieties, which is helpful to finely tune the optical and electronic properties of materials. Power conversion efficiencies(PCE) of BHJ solar cells were achieved up to 2.5% when functionalized thiophene dendrimers were used as electron donor and electron acceptor was a fullerene derivative. These results indicated that dendritic oligothiophenes are a novel class of the materials of electron donor for solution-processed organic solar cells.

关键词： conjugated dendrimers dendritic oligothiophenes (DOT) organic semiconductors bulk heterojunction (BHJ) solar cells

Preparation of double-sided biaxially textured magnesium oxide thin films

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2023年第6期42卷 2075-2080页

作者： Hao Tang Yin-chang ma Rui-Peng Zhao Bo-Wan Tao State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China

A high-efficiency system was designed as an improvement in conventional reel-to-reel system for ion beam-assisted deposition(IBAD) and homo-epitaxy of double-sided biaxially textured MgO thin *** system enables Hastelloy tape to flip automatically and go through the deposition area twice in order to deposit MgO on its both *** this system,the output of doublesided IB AD-MgO is elevated to be 30 m·h^(-1).A 30-m tapes with 10-nm-thick double-sided biaxially textured MgO thin films was successfully made.X-ray diffraction(XRD) and atomic force microscope(AFM) show identical quality of MgO thin films on both *** yield full width at half maximum values of out-of-plane texture and in-plane texture on both sides are approximately 3.1° and 5.3°,***,the influence of ion beam flux and deposition rate on the texture of thin film was investigated.A process window in which biaxial texture can be obtained is found for large-scale production.

关键词： Coated conductors IBAD-MgO Doublesided Automatic flipping