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Ferromagnetism and insulating behavior with a logarithmic temperature dependence of resistivity in Pb_(10-x)Cux(PO_(4))_(6)O

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 106-111页

作者： Yuhang Zhang Cong Liu Xiyu Zhu hai-hu wen Center for Superconducting Physics and Materials National Laboratory of Solid State Microstructures and Department of PhysicsNational Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Recent claim of discovering above-room-temperature superconductivity(Tc≈400 K)at ambient pressure in copper doped apatite Pb10(PO_(4))_(6)O has stimulated world-wide enthusiasm and impulse of motion.A lot of follow-up works have been carried out with controversial *** check whether superconductivity is really present or absent in the material,we need samples which should have a rather pure phase of Pb_(10-x)Cux(PO_(4))_(6)*** we report the characterization results from the Pb_(10-x)Cux(PO_(4))_(6)O with a fraction of about 97 wt.%inferred from the fitting to the X-ray diffraction pattern,if assuming Cu2S as the only *** resistivity measurements show that it is a semiconductor characterized roughly by a ln(1/T)temperature dependence in wide temperature region without trace of *** measurements show that it has a general ferromagnetic signal with a weak superparamagnetic *** grains of the sample show clear interactions with a Nb Fe B *** detected Cu concentration is much lower than the expected nominal *** results show the absence of metallicity and superconductivity in Pb_(10-x)Cux(PO_(4))_(6)O at ambient pressure,and suggest the presence of strong correlation effect.

关键词： superconductivity Pb10(PO4)6O ferromagnetic correlation effect

Strong Quantum Fluctuation of Vortices in Bulk Samples of the New Superconductor MgB_(2)

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Chinese Physics Letters 2001年第6期18卷 816-819页

作者： wen hai-hu LI Shi-Liang ZHAO Zhi-wen NI Yong-Ming REN Zhi-An CHE Guang-Can YANG hai-Peng LIU Zhi-Yong ZHAO Zhong-Xian National Laboratory for Superconductivity Institute of Physics and Center for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100080

By using transport and magnetic measurement,the upper critical field H_(c2)(T)and the irreversibility line Hirr(T)has been determined.A big separation between H_(c2)(0)and Hirr(0)has been found showing the existence of a quantum vortex liquid state induced by quantum fluctuation of vortices in the new superconductor MgB_(2).Further investigation on the magnetic relaxation shows that both the quantum tunneling and the thermally activated flux creep depends weakly on ***,when the melting field Hirr is approached,a drastic rise of the relaxation rate is *** may indicate that the melting of the vortex matter at a finite temperature is also induced by the quantum fluctuation of vortices.

关键词： temperature. quantum relaxation

Lightweight,Strong and High Heat-Resistant Poly(lactide acid)Foams via Microcellular Injection Molding with Self-Assembly Nucleating Agent

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Chinese Journal of Polymer Science 2024年第6期42卷 739-750页

作者： Xiao-hu Bing wen-Yu Ma Ming-hui Wu Peng Gao Xiao Zhou hai-Bin Luo Long Wang wen-Ge Zheng School of materials Science and Engineering Shanghai UniversityShanghai200444China Ningbo Key Lab of Polymer Materials Ningbo Institute of Material Technology and EngineeringChinese Academy of SciencesNingbo315201China University of Chinese Academy of Sciences Beijing100049China

Poly(lactide acid)(PLA)foams have shown considerable promise as eco-friendly alternatives to nondegradable plastic foams,such as polystyrene(PS)***,PLA foam typically suffers from low heat-resistance and poor cellular structure stemming from its inherent slow crystallization rate and low melt *** this study,a high-performance PLA foam with well-defined cell morphology,exceptional strength and enhanced heat-resistance was successfully fabricated via a core-back microcellular injection molding(MIM)*** scanning calorimetry(DSC)results revealed that the added hydrazine-based nucleating agent(HNA)significantly increased the crystallization temperature and accelerated the crystallization process of ***,the addition of a 1.5 wt%of HNA led to a significant reduction in PLA’s cell size,from 43.5µm to 2.87µm,and a remarkable increase in cell density,from 1.08×10^(7)cells/cm^(3)to 2.15×10^(10)cells/cm^(3).This enhancement resulted in a final crystallinity of approximately 55.7%for the PLA blend foam,a marked improvement compared to the pure PLA ***,at 1.5 wt%HNA concentration,the tensile strength and tensile toughness of PLA blend foams demonstrated remarkable improvements of 136%and 463%,***,the Vicat softening temperature of PLA blend foam increased significantly to 134.8°C,whereas the pure PLA foam exhibited only about 59.7℃.These findings underscore the potential for the preparation of lightweight injection-molded PLA foam with enhanced toughness and heat-resistance,which offers a viable approach for the production of high-performance PLA foams suitable for large-scale applications.

关键词： Poly(lactide acid) Nucleating agent Microcellular injection molding Heat-resistance Toughness

Research progress of slippage characteristic and gas film stability enhancement methods on biomimetic hydrophobic surfaces

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Journal of Hydrodynamics 2024年第1期36卷 87-101页

作者： Meng-zhuo Zhang hai-bao hu Liu-zhen Ren Lu-yao Bao Jun wen Luo Xie School of Marine Science and Technology Northwestern Polytechnical UniversityXi’an710072China Research and Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen518063China

The biomimetic hydrophobic surface is a potentially efficient underwater drag reduction method and the drag reduction mechanism of this kind of surface comes from the interfacial *** now,it is a hotspot to grasp the slippage characteristic and explore slippage enhancement *** paper not only summarizes our numerical simulation and experimental results of slippage characteristic at the solid-liquid interface(SLI)of hydrophobic surfaces(HS)and the gas-liquid interface(GLI)of superhydrophobic surfaces(SHS)in recent years,but also introduces some innovative methods that can effectively improve the gas film stability and drag reduction effect of ***,we used the molecular dynamics(MD)simulation method to figure out the effect of the solid-liquid interaction strength,the system temperature and the shear rate on the slippage of SLI,and expound their action mechanism from molecular ***,by MD and multibody dissipative particle dynamics(MDPD)method,the slippage behavior at the GLI was studied under the influence of the microstructure size and the flow driving *** proposed a new kind of hybrid slip boundary condition model to describe the slippage characteristic on *** addition,we found through experiment that a three-dimensional backflow will appear on the GLI under the interfacial adsorption of surfactants,and the backflow direction will reverse with the change of GLI ***,we put forward the wettability step structure and gas injection method to enhance the stability and drag reduction effect of the gas film on SHS.

关键词： Hydrophobic surface superhydrophobic surface interfacial slip underwater drag reduction

Upper Critical Field and Irreversibility Line Determined by Transport Measurement of the New Superconductor MgB_(2)

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Chinese Physics Letters 2001年第6期18卷 823-825页

作者： JIN Hao wen hai-hu LI Shi-Liang ZHAO Zhi-wen NI Yong-Ming REN Zhi-An CHE Guang-Can YANG hai-Peng LIU Zhi-Yong ZHENG Dong-Ning ZHAO Zhong-Xian National Laboratory for Superconductivity Institute of Physics and Center for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100080

Resistive transitions of the new superconductor MgB_(2) are carried out under magnetic fields from 0 to 8 *** is found that the irreversibility field Hirr(T)and the upper critical field Hc2(T)obtained are very close to those determined in the magnetic *** using the Arrhenius activation lawρ=ρ0exp(-U/kBT),the activation barrier U has been determined by the low dissipation part of R(T)*** is found that U■kBT manifests a very weak thermal activation and thermal fluctuation *** may further indicate that the flux dynamics near Hirr(T)is induced by strong quantum fluctuation and tunneling of vortices.

关键词： activation Upper thermal

Field and Current Distribution in Superconducting Film Under Partial Field Penetration

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Chinese Physics Letters 1997年第9期14卷 701-704页

作者： XU Xiao-nong SUN Ai-min DING Shi-ying JIN Xin YAO Xi-xian YAN Shao-lin wen hai-hu Department of Physics and Center of Advanced Studies in Science and Technology of Microstructures Nanjing UniversityNanjing 210093 Department of Electronics Nankai UniversityTianjin 300071 National Labarmtory for Superconductivity Institute of PhysicsChinese Academy of SciencesBeijing 100080

Using finite-element analysis in a self-consistent way with the self-field of the current considered for superconducting thin film,the field and current distributions under partial field penetration are calculated based on the field dependent critical current density *** field penetrated depth is non-linear with the applied *** to the limited resolution of the vibrating sample magnetometer(VSM),the full penetrated field measured by VSM may be much smaller than its actual value.

关键词： field magnetometer vibrating

Influence of Weak Self-Field Effect on Calculated Activation Energy for Superconducting Thin Film

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Chinese Physics Letters 1997年第8期14卷 617-620页

作者： XU Xiao-nong SUN Ai-min DING Shi-ying JIN Xin YAO Xi-xian YAN Shao-lin wen hai-hu Department of Physics and Center of Advanced Studies in Science and Technology of Microstructures Nanjing UniversityNanjing 210093 Department of Electronics Nankai UniversityTianjin 300071 National Laboratory for Superconductivity Institute of PhysicsChinese Academy of SciencesBeijing 100080

When the applied field Ba=μ0 H_(a)(H_(a)>H_(p))is perpendicular to the surface of a disk-shaped superconducting thin film with the full penetrated field H_(p),the radius R,and the thickness d,a quantitative relation between the average fieldand the magnetization M is described by=μ_(0)[H_(a)+(0.81 d/R)M]for R»d,where the termμ0(0.81 d/R)M also is the average self-field of the *** this relation with the magnetic flux conservation equation and the Arrhenius relation,the effective activation energy is extracted from the experimental magnetization relaxation and the dynamic magnetization relaxation,respectively.

关键词： magnetization relaxation relation

Decision and Coordination in a Closed-Loop Supply Chain with Product Recycling Under Different Low-Carbon Regulations

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Journal of the Operations Research Society of China 2024年第3期12卷 695-728页

作者： Qian-Dong Dong hai-wen Xu School of Management and Engineering Nanjing UniversityNanjing210093JiangsuChina School of Science Civil Aviation Flight University of ChinaGuanghan618307SichuanChina

The implementation of recycling activity is of great significance to closed-loop supply chain ***’environmental awareness and governmental subsidy are considered in the two-echelon closed-loop supply *** types of decision-making structures are proposed under different carbon emission *** subsidy sharing mechanism is designed to resolve the channel members’conflict caused by double *** paper provides insight into the effect of environmental awareness and government subsidy under different low-carbon regulations on the supply chain benefit and social welfare via the game *** analysis results display that the government subsidy and subsidy sharing mechanism are profitably beneficial to the whole supply chain and social ***,a noteworthy result reveals that social welfare is not always directly proportional to consumers’environmental *** welfare decreases slightly with the increase in consumers’environmental awareness when consumers’environmental awareness is ***,social welfare will be significantly improved when consumers’environmental awareness increases beyond a certain threshold.

关键词： Closed-loop supply chain Recycling Coordination Social welfare Game theory Carbon emissions

Preparation and Characterization of the New Superconductor MgB_(2)

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Chinese Physics Letters 2001年第4期18卷 587-588页

作者： SUN Yu-Ping SONG wen-hai DAI Jian-Ming WU Xing-Cai WANG Kai-You ZHAO Bing XIAO Hong DU Jia-Ju wen hai-hu ZHAO Zhong-Xian Laboratory of Internal Friction and Defects in Solids Institute of Solid State PhysicsChinese Academy of SciencesHefei 230031 Laboratory of Internal Friction and Defects in Solids National High Magnetic Field LaboratoryHefei 230031 National Laboratory for Superconductivity Institute of Physics and Centre for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100080

Polycrystalline samples of the new superconductor MgB_(2) are prepared by solid state reaction using Mg and B *** resistance measurement shows that the onset transition temperature and zero resistance transition temperature are Tonsetc=43.8 K and Tc0=37 K,*** Tc0 depends on measuring current *** diamagnetic transition temperature of~38 K is obtained by the ac susceptibility measurement.X-ray powder diffraction spectra of MgB_(2) can be indexed using hexagonal structure with space group P6/mmm and lattice parameters a=0.30864 and c=0.35212 nm.A second phase,probably MgO,is also found.

关键词： resistance transition Superconductor