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Study of primordial deuterium abundance in Big Bang nucleosynthesis

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Nuclear Science and Techniques 2024年第3期35卷 208-215页

作者： zhi-lin Shen Jian-Jun he Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China

Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)he,^(4)he,and^(7) Li produced in the early *** these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent *** date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational *** this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium *** found that the reaction rate uncertainties of the four reactions d(d,n)^(3)he,d(d,p)t,d(p,γ)^(3)he,and p(n,γ)d had the largest influence on the calculated D/H ***,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) he *** the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.

关键词： Big Bang nucleosynthesis Abundance of deuterium Reaction cross section Reaction rate Monte Carlo method

Ballistic performances of the hourglass lattice sandwich structures under high-velocity fragments

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Defence Technology（防务技术） 2024年第1期31卷 312-325页

作者： he-xiang Wu Jia Qu lin-zhi Wu Key Laboratory of Advanced Ship Materials and Mechanics College of Aerospace and Civil EngineeringHarbin Engineering UniversityHarbin150001China School of Civil Engineering Northeast Forestry UniversityHarbin150040China

In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of *** is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of *** results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural *** this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.

关键词： Hourglass lattice sandwich structures Ballistic performances high-velocity Finite element analysis

High-Order Two-Scale Asymptotic Paradigm for the Elastodynamic Homogenization of Periodic Composites

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Acta Mechanica Solida Sinica 2024年第1期37卷 124-138页

作者： Wei-zhi Luo Mu he Liang Xia Qi-Chang he State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Laboratoire Modélisation et Simulation Multi-Echelle MSME UMR 8208 CNRSUniversite Gustave Eiffel77454 Marne-la-ValléeFrance

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable,which offers an approximate framework for the asymptotic homogenization analysis of the motion ***,in this framework,the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order *** such a context,a compact,fast,and accurate asymptotic paradigm is *** work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be ***,the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor,which is demonstrated by representative one-and two-dimensional *** numerical results show that(1)the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites,(2)the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation,and(3)the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results.

关键词： Composites Homogenization Asymptotic analysis Dynamics Dispersion

Self-Powered Absorptive Reconfigurable Intelligent Surfaces for Securing Satellite-Terrestrial Integrated Networks

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China Communications 2024年第9期21卷 276-291页

作者： lin zhi Niu hehao he Yuanzhi An Kang Zhong Xudong Chu Zheng Xiao Pei College of Electronic Engineering National University of Defense TechnologyHefei 230037China Sixty-Third Research Institute National University of Defense TechnologyNanjing 210007China Institute of Systems Engineering Academy of Military ScienceBeijing 100141China Department of Electrical and Electronic Engineering University of Nottingham Ningbo ChinaNingbo 315100China Institute for Communication Systems University of SurreyGuildford GU27XHU.K.

Satellite communications have attracted significant interests due to its advantages of large footprint and massive ***,the commonly used onboard beamforming is hard to achieve reliable security because of the highly correlated legitimate and wiretap downlink *** exploit the benefits of satellite-terrestrial integrated network(STIN)and a novel absorptive reconfigurable intelligent surface(RIS)for improving the security of satellite downlink communications(SDC)in the presence of eavesdroppers(Eves).This paper aims to maximize the achievable secrecy rate of the earth station(ES)while satisfying the signal reception constraints,harvested power threshold at the RIS,and total transmit power *** solve this nonconvex problem,we propose a penalty-function based dual decomposition scheme,which firstly transforms the original problem into a two-layer optimization ***,the outer layer and inner problems are solved by utilizing the successive convex approximation,Lagrange-dual and Rayleigh quotient methods to obtain the beamforming weight vectors and the reflective coefficient ***,simulation results verify the effectiveness of the proposed scheme for enhancing the SDC security.

关键词： absorptive RIS beamforming design secure communications STIN

The Minimum Centroid Branch Spanning Tree Problem

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Journal of the Operations Research Society of China 2024年第2期12卷 528-539页

作者： Hao lin Cheng he School of Science Henan University of TechnologyZhengzhou450001HenanChina

For a spanning tree T of graph G,the centroid of T is a vertex v for which the largest component of T-v has as few vertices as *** number of vertices of this component is called the centroid branch weight of *** minimum centroid branch spanning tree problem is to find a spanning tree T of G such that the centroid branch weight is *** application to design of communication networks,the loads of all branches leading from the switch center should be as balanced as *** this paper,we prove that the problem is strongly NP-hard even for bipartite ***,the problem is shown to be polynomially solvable for split graphs,and exact formulae for special graph familis,say Kn_(1),n_(2),...,n_(k)and P_(m)×P_(n),are presented.

关键词： Spanning tree optimization Centroid branch-NP-hardness Polynomial-time algorithm

OsPDR20 is an ABCG metal transporter regulating cadmium accumulation in rice

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Journal of Environmental Sciences 2024年第2期136卷 21-34页

作者： he Li Chao Li Di Sun zhi Min Yang Department of Biochemistry and Molecular Biology College of Life SciencesNanjing Agricultural UniversityNanjing 210095China

Cadmium(Cd)is a non-essential toxic heavy metal,seriously posing high environmental risks to human *** genetic resources relevant to functional genes is important for understanding the metal absorption and accumulation in crops and bioremediation of Cd-polluted *** study investigated a functionally uncharacterized ATP binding cassette transporter G family(ABCG)gene encoding a Pleiotropic Drug Resistance 20(PDR20)type metal transporter which is localized to the plasma membrane of ***20 was transcriptionally expressed in almost all tissues and organs in lifespan and was strongly induced in roots and shoots of young rice under Cd *** expression of OsPDR20 in a yeast mutant ycf1 sensitive to Cd conferred cellular tolerance with less Cd *** of OsPDR20 by RNA interference(RNAi)moderately attenuated root/shoot elongation and biomass,with reduced chlorophylls in rice grown under hydroponic medium with 2 and 10μmol/L Cd,but led to more Cd accumulation.A field trial of rice grown in a realistic Cd-contaminated soil(0.40 mg/kg)showed that RNAi plants growth and development were also compromised compared to wild-type(WT),with smaller panicles and lower spikelet fertility but little effect on yield of ***,OsPDR20 suppression resulted in unexpectedly higher levels of Cd accumulation in rice straw including lower leaves and culm and *** results suggest that OsPDR20 is actively involved in Cd accumulation and homeostasis in rice *** increased Cd accumulation in the RNAi plants has the potential application in phytoremediation of Cd-polluted wetland soils.

关键词： Rice ABCG transporter Cadmium accumulation Phytoremediation

Prediction of contact resistance of electrical contact wear using different machine learning algorithms

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Friction 2024年第6期12卷 1250-1271页

作者： Zhen-bing CAI Chun-lin LI Lei YOU Xu-dong CheN Li-ping he Zhong-qing CAO zhi-nan ZHANG Tribology Research Institute Southwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

H62 brass material is one of the important materials in the process of electrical energy transmission and signal transmission,and has excellent performance in all *** the wear behavior of electrical contact pairs is particularly complex when they are in service,we evaluated the effects of load,sliding velocity,displacement amplitude,current intensity,and surface roughness on the changes in contact *** learning(ML)algorithms were used to predict the electrical contact performance of different factors after wear to determine the correlation between different factors and contact *** forest(RF),support vector regression(SVR)and BP neural network(BPNN)algorithms were used to establish RF,SVR and BPNN models,respectively,and the experimental data were trained and *** was proved that BP neural network model could better predict the stable mean resistance of H62 brass alloy after *** analysis shows that the load and current have great influence on the predicted electrical contact *** wear behavior of electrical contacts is influenced by factors such as load,sliding speed,displacement amplitude,current intensity,and surface roughness during *** learning algorithms can predict the electrical contact performance after wear caused by these *** results indicate that an increase in load,current,and surface roughness leads to a decrease in stable mean resistance,while an increase in displacement amplitude and frequency results in an increase in stable mean resistance,leading to a decline in electrical contact *** reduce testing time and costs and quickly obtain the electrical contact performance of H62 brass alloy after wear caused by different factors,three algorithms(random forest(RF),support vector regression(SVR),and BP neural network(BPNN))were used to train and test experimental results,resulting in a machine learning model suitable for predicting the stable mean

关键词： electrical contact wear contact resistance machine learning(ML) neural network

Synthetic Control of Thorium Metal-Organic Frameworks for Sequencing and Sensing of Radioiodine Species

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Chinese Journal of Chemistry 2024年第1期42卷 20-28,I0004页

作者： Yu Ju Zi-Jian Li xue Wang Jie Qiu Yiuhon Chan zhi-Hui Zhang Mingyang he Jian lin Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology Changzhou UniversityNo.21Gehu Middle RoadChangzhouJiangsu 213164China Schoolof Nuclear Science and Technology Xi'an Jiaotong UniversityNo.28West Xianning RoadXianShaanxi 710049China Key Laboratoryof Interfacial Physics and Technology Shanghai Institute of Applied PhysicsChinese Academy of Sciences2019JiaLuoRoadShanghai 201800China

Exploring the physiochemical properties and expanding the applications of actinide-containing materials is paramount to address the escalating challenge of radioactive waste ***,unlocking the full potential of these materials is largely crippled by the radiotoxicity of the *** report here two porous and luminescent thorium-based metal-organic frameworks(Th-BITD-1 and Th-BITD-2)that serve as a bifunctional platform for sequencing and sensing of radioiodine,a much more radioactive fission product discharged during the nuclear fuel *** particular,Th-BITD-1 displays better iodine uptake performance than Th-BITD-2 via the solution-based process and vapor diffusion with the maximum adsorption capacities of 831 and 1099 mg/g,*** thermore,Th-BITD-1 can function as a highly sensitive luminescence sensor for iodate with a quenching constant(Ksv)of 6.6(5)×10^(3) M^(-1)and a detection limit of 2.02μM,respectively,outperforming 2.96(6)×10^(3)M^(-1)and 10.5μM of ***,a positive correlation between the sensing efficacy and the iodate adsorption capacity has been *** work highlights the opportunity in designing novel actinide-based MOFs for their potential applications in radiological fields,e.g.,radionuclide separation and detection.

关键词： Thorium Metal-organic frameworks Adsorption Detection lodine Actinides Radiochemistry Luminescence

Construction of algal-bacterial consortia using green microalgae Chlorella vulgaris and As(Ⅲ)-oxidizing bacteria:As tolerance and metabolomic profiling

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Journal of Environmental Sciences 2024年第5期139卷 258-266页

作者： Xiaoman he Guobing lin Jiayuan Zeng Zhaoguang Yang lin Wang College of Chemistry and Chemical Engineering Central South UniversityChangsha 410083China Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety Central South UniversityChangsha 410083China

Bioremediation became a promising technology to resolve arsenic(As)contamination in aquatic *** monoculture such as microalgae or bacteria was sensitive to environmental disturbance and vulnerable to contamination,green microalgae Chlorella vulgaris and arsenite(As(Ⅲ))-oxidizing bacteria Pseudomonas ***11 were co-cultured to construct algal-bacterial consortia in the current *** effects of algae-bacteria(A:B)ratio and exposure As(Ⅲ)concentration on algal growth,As speciation and metabolomic profile were *** growth arrested when treated with 100 mg/L As(Ⅲ)without the co-cultured *** contrast,co-cultured with strain SMS11 significantly enhanced As tolerance in *** especially with A:B ratio of 1:*** the As(Ⅲ)in culture media of the consortia were oxidized into As(Ⅴ)on day *** of As was observed on day *** 1% and 0.5% of total As were converted into dimethylarsinic acid(DMA)after 21days cultivation when the initial concentrations of As(Ⅲ)were 1 and 10 mg/L,*** analysis was further performed to reveal the response of consortia metabolites to external As(Ⅲ).The enriched metabolomic pathways were associated with carbohydrate,amino acid and energy *** acid cycle and glyoxylate and dicarboxylate metabolism were upregulated under As stress due to their biological functions on alleviating oxidative stress and protecting *** carbohydrate and amino acid metabolisms provided precursors and potential substrates for energy production and cell protection under abiotic *** of the pathways relevant to carbohydrate or amino acid metabolism were triggered by energy requirement.

关键词： Microalgae Algal-bacterial consortia As(Ⅲ)-oxidizing bacteria Metabolomics Energy metabolism