检索结果-南通市图书馆

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 conclusions.To 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)O.Here 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 impurity.The resistivity measurements show that it is a semiconductor characterized roughly by a ln(1/T)temperature dependence in wide temperature region without trace of superconductivity.Magnetization measurements show that it has a general ferromagnetic signal with a weak superparamagnetic background.Many grains of the sample show clear interactions with a Nb Fe B magnet.The detected Cu concentration is much lower than the expected nominal one.Our 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

Pressure-induced color change arising from transformation between intra-and inter-band transitions in LuH_(2±x)N_(y)

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 161-166页

作者： Zhe Liu Yingjie Zhang Shenyang huang Xue Ming Qing Li Chenghao Pan Yaomin Dai Xiaoxiang Zhou Xiyu Zhu hugen Yan 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 State Key Laboratory of Surface Physics Key Laboratory of Micro and Nano-Photonic Structures of the Ministry of EducationDepartment of PhysicsFudan UniversityShanghai 200433China

The pressure-induced color change in the nitrogen-doped lutetium hydride has triggered extensive discussions about the underlying physics and potential applications.Here,we study the optical response of LuH_(2±x)N_(y)in a broad frequency range at ambient pressure and its evolution with pressure in the visible spectral range.The broad-band optical spectra at ambient pressure reveal a Drude component associated with intra-band electronic transitions and two Lorentz components(L1 and L2)arising from inter-band electronic transitions.The application of pressure causes a spectral weight transfer from L1 to the Drude component,leading to a blue shift of the plasma edge in the reflectivity spectrum alongside a reduction of the high-frequency reflectivity.Our results suggest that the pressure-induced color change in LuH_(2±x)N_(y)is closely related to the transformation between intra-and inter-band electronic transitions,providing new insights into the mechanism of the pressure-induced color change in LuH_(2±x)N_(y).

关键词： nitrogen-doped lutetium hydride optical spectroscopy high-pressure technique color change

Superconductivity in nickel-based 112 systems

在线全文

学校读者我要写书评

暂无评论

The Innovation 2022年第1期3卷 108-121页

作者： Qiangqiang Gu hai-hu wen National Laboratory of Solid State Microstructures and Department of Physics Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Superconductivity has been discovered recently in infinite-layer nickel-based 112 thin films R_(1-x)A_(x)NiO_(2)(R=La,Nd,Pr and A=Sr,Ca).They are isostructural to the infinite-layer cuprate(Ca,Sr)CuO_(2)and are supposed to have a formal Ni 3d9 valence,thus providing a new platform to study the unconventional pairing mechanismof high-temperature superconductors.This important discovery immediately triggers a huge amount of innovative scientific curiosity in the field.In this paper,we try to give an overview of the recent research progress on the newly found superconducting nickelate systems,both from experimental and theoretical aspects.We mainly focus on the electronic structures,magnetic excitations,phase diagrams and superconducting gaps,and finally make some open discussions for possible pairing symmetries in Ni-based 112 systems.

关键词： field nickel infinite

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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 slippage.For now,it is a hotspot to grasp the slippage characteristic and explore slippage enhancement strategies.This 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 SHS.First,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 scale.Then,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 velocity.We proposed a new kind of hybrid slip boundary condition model to describe the slippage characteristic on GLI.In 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 morphology.Finally,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

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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)foams.Nevertheless,PLA foam typically suffers from low heat-resistance and poor cellular structure stemming from its inherent slow crystallization rate and low melt strength.In 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)process.Differential scanning calorimetry(DSC)results revealed that the added hydrazine-based nucleating agent(HNA)significantly increased the crystallization temperature and accelerated the crystallization process of PLA.Remarkably,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 foam.Furthermore,at 1.5 wt%HNA concentration,the tensile strength and tensile toughness of PLA blend foams demonstrated remarkable improvements of 136%and 463%,respectively.Additionally,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

Prenatal amoxicillin exposure induces developmental toxicity in fetal mice and its characteristics

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第3期137卷 287-301页

作者： Yongguo Dai Yu Peng wen hu Yi Liu hui Wang Department of Pharmacology Wuhan University School of Basic Medical SciencesWuhan 430071China Department of Pharmacy Zhongnan Hospital of Wuhan UniversityWuhan 430071China hubei Provincial Key Laboratory of Developmentally Originated Disease Wuhan 430071China

Amoxicillin,a widely used antibiotic in human and veterinary pharmaceuticals,is now considered as an“emerging contaminant”because it exists widespreadly in the environment and brings a series of adverse outcomes.Currently,systematic studies about the developmental toxicity of amoxicillin are still lacking.We explored the potential effects of amoxicillin exposure on pregnancy outcomes,maternal/fetal serum phenotypes,and fetal multiple organ development in mice,at different doses(75,150,300 mg/(kg·day))during late-pregnancy,or at a dose of 300 mg/(kg·day)during different stages(mid-/latepregnancy)and courses(single-/multi-course).Results showed that prenatal amoxicillin exposure(PAmE)had no significant infuence on the body weights of dams,but it could inhibit the physical development and reduce the survival rate of fetuses,especially during the midpregnancy.Meanwhile,PAmE altered multiple maternal/fetal serum phenotypes,especially in fetuses.Fetal multi-organ function results showed that PAmE inhibited testicular/adrenal steroid synthesis,long bone/cartilage and hippocampal development,and enhanced ovarian steroid synthesis and hepatic glycogenesis/lipogenesis,and the order of severity might be gonad(testis,ovary)>liver>others.Further analysis found that PAmE-induced multiorgan developmental and functional alterations had differences in stages,courses and fetal gender,and the most obvious changes might be in high-dose,late-pregnancy and multicourse,but there was no typical rule of a dose-response relationship.In conclusion,this study confirmed that PAmE could cause abnormal development and multi-organ function alterations,which deepens our understanding of the risk of PAmE and provides an experimental basis for further exploration of the long-term harm.

关键词： Amoxicillin Prenatal exposure Fetal development Organ function Developmental toxicity

Asymmetric Drying and Wetting Trends in Eastern and Western China

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第2期41卷 221-232页

作者： wen WU Fei JI Shujuan hu Yongli HE College of Atmospheric Sciences Lanzhou UniversityLanzhou 730000China Collaborative Innovation Center for Western Ecological Safety Lanzhou UniversityLanzhou 730000China

As an important factor that directly affects agricultural production, the social economy, and policy implementation,observed changes in dry/wet conditions have become a matter of widespread concern. However, previous research has mainly focused on the long-term linear changes of dry/wet conditions, while the detection and evolution of the non-linear trends related to dry/wet changes have received less attention. The non-linear trends of the annual aridity index, obtained by the Ensemble Empirical Mode Decomposition(EEMD) method, reveal that changes in dry/wet conditions in China are asymmetric and can be characterized by contrasting features in both time and space in China. Spatially, most areas in western China have experienced transitions from drying to wetting, while opposite changes have occurred in most areas of eastern China. Temporally, the transitions occurred earlier in western China compared to eastern China. Research into the asymmetric spatial characteristics of dry/wet conditions compensates for the inadequacies of previous studies, which focused solely on temporal evolution;at the same time, it remedies the inadequacies of traditional research on linear trends over centennial timescales. Analyzing the non-linear trend also provides for a more comprehensive understanding of the drying/wetting changes in China.

关键词： aridity index EEMD dry/wet conditions asymmetric evolution

An analytical model of hot rolling force for a thick plate by combining globally optimal approximation yield criterion and egg-circular velocity field

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2024年第3期31卷 647-659页

作者： Shun-hu Zhang Yi Zhang wen-hao Tian Yan Li Shagang School of Iron and Steel Soochow UniversitySuzhou 215021JiangsuChina

For the sake of solving the problem that it is difficult to be integrated for the Mises specific plastic power due to its nonlinearity,a new linear criterion,named the globally optimal approximation criterion,is constructed by the polygonal approximation to the Mises circle.The new criterion is proved to be the linear function of the principal stress componentsσ1,σ2 andσ3 and the trajectory of it on theπ-plane is a non-equiangular but equilateral dodecagon intersecting the Mises circle.The theoretical results of the current criterion described by the Lode stress parameters are in excellent accordance with the experimental results.Meanwhile,according to the trend that the metallic flow velocity between rollers aggrandizes gradually from the inlet to the outlet during the hot rolling of a thick plate,a biomimetic velocity field is proposed in which the horizontal velocity component fits the egg-circular curve distribution.The velocity field and its simulated results agree quite well.Subsequently,using the determined linear criterion,energy analysis of the constructed velocity field is utilized to obtain the interior deformation power,while the vector decomposition approach is utilized to obtain the frictional power and shear power.On this basis,the overall power is obtained and the analytical solutions are generated for the rolling torque,rolling force and the coefficient of the stress state under different egg curves by minimizing the neutral angle.Furthermore,the parameter optimization of the characteristic parameterρwhich affects the slope of the egg-circular curve is carried out and the best egg-circular curve which can minimize the energy consumption is determined.The best agreement between the theoretical and observed values of rolling force and rolling torque is under this curve,and the mean relative errors of the rolling torque and rolling force are no more than 2.93%,while the maximum error is no more than 8.35%.

关键词： Yield criterion Plastic deformation Rolling force Velocity field Analytical solution

Price prediction of power transformer materials based on CEEMD and GRU

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Global Energy Interconnection 2024年第2期7卷 217-227页

作者： Yan huang Yufeng hu Liangzheng Wu Shangyong wen Zhengdong Wan Energy Development Research Institute China Southern Power GridGuangzhou 510623P.R.China China Southern Power Grid Guangzhou 510623P.R.China

The rapid growth of the Chinese economy has fueled the expansion of power grids.Power transformers are key equipment in power grid projects,and their price changes have a significant impact on cost control.However,the prices of power transformer materials manifest as nonsmooth and nonlinear sequences.Hence,estimating the acquisition costs of power grid projects is difficult,hindering the normal operation of power engineering construction.To more accurately predict the price of power transformer materials,this study proposes a method based on complementary ensemble empirical mode decomposition(CEEMD)and gated recurrent unit(GRU)network.First,the CEEMD decomposed the price series into multiple intrinsic mode functions(IMFs).Multiple IMFs were clustered to obtain several aggregated sequences based on the sample entropy of each IMF.Then,an empirical wavelet transform(EWT)was applied to the aggregation sequence with a large sample entropy,and the multiple subsequences obtained from the decomposition were predicted by the GRU model.The GRU model was used to directly predict the aggregation sequences with a small sample entropy.In this study,we used authentic historical pricing data for power transformer materials to validate the proposed approach.The empirical findings demonstrated the efficacy of our method across both datasets,with mean absolute percentage errors(MAPEs)of less than 1%and 3%.This approach holds a significant reference value for future research in the field of power transformer material price prediction.

关键词： Power transformer material Price prediction Complementary ensemble empirical mode decomposition Gated recurrent unit Empirical wavelet transform

Comment on:Clinical Characteristics,Diagnosis,and Treatments for COVID-19

在线全文

学校读者我要写书评

暂无评论

Current Medical Science 2024年第3期44卷 667-668页

作者： wen, Ying hu, Xin-dan Department of Infectious Diseases The First Affiliated Hospital of China Medical University Shenyang China