检索结果-南通市图书馆

Newtonian limit of Einstein equation with a cosmological constant

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 Physics C 2024年第10期48卷 264-274页

作者： li-Fang li Zhoujian cao Xiaokai He Institute of Mechanics Chinese Academy of SciencesBeijing 100190China Institute of Applied Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China School of Mathematics and Statistics Hunan First Normal UniversityChangsha 410205China

Traditionally,the cosmological constant has been viewed as dark energy that mimics matter with negative *** that matter with negative energy provides a repulsive force,which fundamentally differs from typical gravitational forces,it has been believed that the cosmological constant effectively contributes a repulsive ***,it is important to note that the concept of gravitational force is valid only within the framework of Newtonian *** this study,we demonstrate that the traditional understanding of the gravitational force contributed by the cosmological constant is not entirely *** approach involves investigating the Newtonian limit of the Einstein equation with a cosmological *** subtleties involved in this analysis are discussed in ***,we find that the effect of the cosmological constant on Newtonian gravity is an attractive force rather than a repulsive one for ordinary *** expected,this corrective force is negligibly ***,our findings may offer a way to distinguish between dark energy and the cosmological constant,as one contributes a repulsive force while the other contributes an attractive force.

关键词： cosmological constant dark matter Einstein equation Newtonian limit dark energy

Engineering FeOOH/Ni(OH)_(2) heterostructures on Ni_(3)S_(2)surface to enhance seawater splitting

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第5期43卷 1989-1998页

作者： Chen Yang Ya-Dong li li-Juan cao Xi-Long Wang Han-Pu liang Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of SciencesQingdao 266101China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Sino-Danish College University of Chinese Academy of SciencesBeijing 100049China

The construction of highly stable and efficient electrocatalysts is desirable for seawater splitting but remains challenging due to the high concentration of Cl-in ***,FeOOH/Ni(OH)_(2)heterostructure supported on Ni_(3)S_(2)-covered nickel foam(Fe–Ni/Ni_(3)S_(2)/NF)was fabricated by hydrothermal and etching methods,as well as anodic oxidation *** electronic structure of FeOOH and Ni(OH)_(2)could be modulated after depositing FeOOH nanoparticles on Ni(OH)_(2)nanosheet,which greatly boosted the catalytic *** the catalyst used as an electrode for oxygen evolution reaction(OER),it needed low overpotentials of 266 and 368 m V to achieve current densities of 100 and 800 m A·cm^(-2),respectively,in 1 mol·L^(-1)KOH+seawater *** can operate continuously at 100 m A·cm^(-2)for 400 h without obvious ***,in situ generated SO_(4)^(2-)from inner Ni_(3)S_(2)during electrolysis process would accumulate on the surface of active sites to form passivation layers to repel Cl^(-),which seemed to be responsible for superior *** study not only synthesizes an OER catalyst for highly selective and stable seawater splitting,but also gives a novel approach for industrial hydrogen production.

关键词： Anodic oxidation Heterostructure Oxygen evolution reaction Seawater splitting

维普期刊数据库

Distribution of per-and polyfluoroalkyl substances in blood,serum,and urine of patients with liver cancer and associations with liver function biomarkers

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第5期139卷 418-427页

作者： cao Dai lin Peng Yanjie li Zhendong li Da Chen Fei Wang Nan lin department of Hepatobiliary Surgery The Third Affiliated Hospital of Sun Yat-sen UniversityGuangzhou 510630China School of Environment Guangdong Key Laboratory of Environmental Pollution and HealthJinan UniversityGuangzhou 510632China State Key Laboratory of Environmental and Biological Analysis Department of ChemistryHong Kong Baptist UniversityHong Kong 999077China South China Institute of Environmental Sciences MEEGuangzhou 510655China

Studies have shown that per-and polyfluoroalkyl substances(PFASs)may be hepatotoxic in animals or ***,data on clinical epidemiology are very *** this study,21PFASs were determined in patients with liver diseases,with the highest median concentrations detected in the serum sample(26.7 ng/mL),followed by blood(10.7 ng/mL)and urine(5.02 ng/mL).Higher total PFAS concentrations were found in hepatocellular carcinoma(HCC)patients compared to non-HCC patients,with significant discrepancies in serum and blood ***,significant correlations were also found among PFAS concentrations and age,gender,body mass index(BMI),and liver function biomarkers *** example,PFAS concentrations are significantly higher in males than in females;Several serum PFASs concentrations increase with age and BMI,while the serum perfluorohexane sulfonic acid(PFHxS)concentrations are negatively correlated with *** addition,multiple regression models adjusted for age,gender and BMI found that increased serum perfluorobutane sulfonic acid(PFBS),perfluoroheptane sulfonic acid(PFHpS)and perfluorohexylphosphonic acid(PFHxPA)conentrations are correlated with elevated alkaline phosphatase(ALP),aspartate aminotransferase(AST),and alpha-fetoprotein(AFP)(pde epidemiological support for the future study on the potential clinical hepatotoxicity of PFAS.

关键词： Per-and polyfluoroalkyl substances(PFASs) liver cancer Serum Blood Urine liver function biomarkers

维普期刊数据库

An online value iteration method for linear-quadratic mean field social control with unknown dynamics

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第4期67卷 38-39页

作者： Bing-Chang WANG Shumei li Ying cao School of Control Science and Engineering Shandong University

Mean field(MF) models have been widely applied to economics, control theory, and other fields. Its prominent feature is that the individual influence on the overall population is negligible and the impact of the entire system to the single agent is significant and cannot be ignored. As a classical problem in control theory, linear quadratic(LQ) control for MF models has been widely investigated(e.g., [1, 2]).

关键词：

Aging Mongolian pine plantations face high risks of drought-induced growth decline:evidence from both individual tree and forest stand measurements

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Forestry Research 2024年第2期35卷 109-120页

作者： Mingyong li Leilei Yang Yu cao dedong Wu Guangyou Hao CAS Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016People’s Republic of China Key Laboratory of Terrestrial Ecosystem Carbon Neutrality Liaoning ProvinceShenyang 110016People’s Republic of China Daqinggou Ecological Research Station Institute of Applied EcologyChinese Academy of SciencesShenyang 110016People’s Republic of China University of Chinese Academy of Sciences Beijing 100049People’s Republic of China Research Institute of Sand Control and Utilization Liaoning ProvinceFuxin 123000People’s Republic of China

Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited *** important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris *** litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth ***,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly *** this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger *** addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older *** of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic *** study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with *** results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.

关键词： Tree age Drought stress Mongolian pine plantation Tree rings Remote sensing Plant hydraulics

维普期刊数据库

Synergistic effect of Co and Co_(6)Mo_(6)C for electroreduction of nitrate to ammonia on Co-MOF derived Co_(6)Mo_(6)C/Co/NC

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第7期17卷 5807-5816页

作者： Xinyan Wang Yue cao Yan Hai Xiaoman li Min Luo State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering School of Chemistry and Chemical EngineeringNingxia UniversityYinchuan 750021China

Electrocatalytic nitrate reduction reaction(e-NO_(3)RR)offers a promising alternative method for nitrogen cycling and ammonia(NH3)production under ambient ***,the method is still in the dilemma of lowering the reaction overpotential and increasing the reaction *** successfully developed the composition-adjustable Co_(6)Mo_(6)C/Co/N-doped carbon(NC)catalysts by in situ carbonization of Co-based metal-organic framework(MOF)with the constrained phosphomolybdic *** adjusting the ratio of Co0 and Co_(6)Mo_(6)C,Co_(6)Mo_(6)C/Co/NC-3 could satisfy both NO_(3)−conversion at low potential and NH_(x)hydrogenation,and synthesize ammonia efficiently through the synergistic effect of Co0 and Co_(6)Mo_(6)*** achieved an ammonia yield rate as 1233.2μg·h^(−1)·mgcat^(−1)and Faradaic efficiency of NH4+93.6%at−0.33 V *** hydrogen electrode(RHE).Importantly,density functional theory(DFT)calculations and experimental results have demonstrated for the first time the excellent adsorption of nitrite(NO_(2)^(−))by the Mo sites of Co_(6)Mo_(6)C during e-NO_(3)RR,avoiding the undesirable accumulation of NO_(2)^(−).

关键词： synergistic effect nitrate electroreduction Co_(6)Mo_(6)C ammonia synthesis

Hydrogen bond-bridged phosphorene flexible film for photodynamic inhibiting Staphylococcus aureus

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 5461-5468页

作者： Ziyu Wei Wenting li Zhifang liu Yongfa Zhu Huaqiang cao department of Chemistry Engineering Research Center of Advanced Rare Earth MaterialsTsinghua UniversityBeijing 100084China

Antibiotics are a widely used and effective treatment for bacterial ***,bacteria can gradually evolve during infection,leading to developing resistance to antibiotics,which renders previously effective treatments *** a useful and convenient manner to treat bacterial infections is a great ***,we report a flexible hydrogen-bond-bridged phosphorene film with photodynamic antibacterial properties and excellent mechanical properties,fabricated from electrochemical exfoliation of black phosphorus(BP).When illuminated under 700 nm light,the hydrogen bond-bridged phosphorene flexible film is capable of converting ground-state triplet oxygen(O_(2))into excited-state singlet oxygen(^(1)O_(2)),destroying the structure of the membrane of Staphylococcus aureus,and eventually leading to bacterial death,via breaking the C=C of unsaturated fatty acids within the bacterial cell membrane after the reaction between^(1)O_(2)and unsaturated fatty acids,thus realizing a highly efficient antibacterial approach,which is supported by gas chromatography-mass spectrometry(GC-MS)*** work establishes an effective phototherapy platform for treating bacterial traumatic infections.

关键词： hydrogen bond-bridged phosphorene flexible film photodynamic Staphylococcus aureus

Preparation and performance improvement of a dual-component microcapsule self-healing system for silicone rubber insulating material

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Voltage 2024年第2期9卷 453-465页

作者： Mingzhe li Bin cao Fanghui Yin Hongwei Mei liming Wang Engineering Laboratory of Power Equipment Reliability in Complicated Coastal Environments Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhenChina

A key factor limiting the development of silicone rubber insulating materials is their short service life in harsh operating *** establishment of a self-healing system is desired to improve the long-term operational performance of silicone rubber and effectively extend its service *** this study,poly(urea-formaldehyde)microcapsules containing polydimethylsiloxane healing agents are prepared and a dual-component microcapsule self-healing system for silicone rubber material is established and *** addition,the key factors affecting the self-healing performance(such as microcapsule size,rupture rate,and microcapsule doping amount)are *** is found that when SYLGARDTM 184 is used as the healing agent and matrix,with a 4:6(A:B)doping ratio of dual-component microcapsules and 20 phr doping amount,the self-healing efficiency is approximately 51%.Furthermore,increasing the microcapsule rupture rate and the interface strength between the healing agent and the matrix can effectively improve the self-healing *** relationships between key factors and self-healing performance are theoretically *** on the relationships,the microcapsule self-healing system can be appropriately *** results of this paper can provide a reference for the development of long-life silicone rubber insulating materials.

关键词： service rubber performance

Mechanism investigation of A-site doping on modulating electronic band structure and photocatalytic performance towards CO_(2) reduction of LaFeO_(3) perovskite

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第5期17卷 3733-3744页

作者： Chi cao Jinshuo li Yang Hu lin Zhang Wensheng Yang State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchun 130012China Engineering Research Center for Nanomaterials Henan UniversityKaifeng 475004China

Three kinds of metal atoms with different valence electronic configurations,Bi(6s^(2)6p^(3)),Y(4d^(1)5s^(2)),and Ce(4f^(1)5d^(1)6s^(2)),were selected to investigate the effect of A-site(La^(3+))doping on electronic band structure,photoelectric properties,and photocatalytic performance of LaFeO_(3) *** was identified that the Bi doped LaFeO_(3) presented significantly improved photocatalytic activity towards the reduction of CO_(2),while the Y or Ce doped LaFeO_(3) displayed decreased photocatalytic activity compared to the pristine LaFeO_(3).It was revealed that doping of all the three metal atoms resulted in narrowed band gap and thus extended light absorption of LaFeO_(3) by lowering its conduction band minimum(CBM).The recombination rate and mobility of the charge carriers were represented by the relative effective mass(D)between holes and electrons for pristine and A-site doped LaFeO_(3).The doping of Bi resulted in increased D value,attributed to the Bi 6s electron states at the valence band maximum(VBM),and thus promoted separation and transfer of the charge carriers and improved photocatalytic activity of LaFeO_(3).In contrast,the doping of Ce resulted in significantly decreased D value,induced by the highly localized Ce 4f hole states at the CBM,and thus higher recombination rate of the charge carriers and decreased photocatalytic activity of LaFeO_(3).Furthermore,the Y doped LaFeO_(3) with a slightly decreased D value presented slightly increased recombination rate of the charge carriers and thus decreased photocatalytic *** a work provides new insights into the A-site doping in LaFeO_(3) perovskite,which should be helpful for optimizing the electronic band structure and activity of perovskite-type photocatalysts at atomic level.

关键词： A-site doping electronic band structure charge carrier behavior photocatalytic CO_(2)reduction perovskite-type photocatalytsts