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Ecological effect of the plantation of Sabina vulgaris in the Mu Us Sandy Land,China

Journal of Arid Land 2024年第1期16卷 14-28页

作者： NAN Weige dong Zhibao ZHOU Zhengchao LI Qiang chen Guoxiang School of Geography and Tourism Shaanxi Normal UniversityXi'an 710062China Shaanxi Key Laboratory of Ecological Restoration in Shaanbei Mining Area Yulin UniversityYulin 719000China College of Prataculture Gansu Agricultural UniversityLanzhou 730070China

Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid *** study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land,*** collected soil samples from five depth layers(0-20,20-40,40-60,60-80,and 80-100 cm)in the *** plantation plots across four plantation ages(4,7,10,and 16 years)in November 2019,and assessed soil physical(soil bulk density,soil porosity,and soil particle size)and chemical(soil organic carbon(SOC),total nitrogen(TN),available nitrogen(AN),available phosphorus(AP),available potassium(AK),cation-exchange capacity(CEC),salinity,p H,and C/N ratio)*** results indicated that the soil predominantly consisted of sand particles(94.27%-99.67%),with the remainder being silt and *** plantation age increased,silt and very fine sand contents progressively *** 16 years of planting,there was a marked reduction in the mean soil particle *** initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an *** positive correlations were observed for the clay,silt,and very fine sand(mean diameter of 0.000-0.100 mm)with SOC,AK,and p *** contrast,fine sand and medium sand(mean diameter of 0.100-0.500 mm)showed significant negative correlations with these *** findings ascertain that the plantation of *** requires 10 years to effectively act as a windbreak and contribute to sand fixation,and needs 16 years to improve soil physical and chemical ***,these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid *** research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China.

关键词： Sabina vulgaris plantation age soil physical and chemical properties soil particle size soil fertility vegetation restoration Mu Us Sandy Land

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A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics

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Petroleum Science 2024年第1期21卷 327-342页

作者： Qian Zhang Wen-dong Wang Yu-Liang Su Wei chen Zheng-dong Lei Lei Li Yong-Mao Hao Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shale Oil Development Branch Changqing Oilfield CompanyPetroChinaQingyang745708GansuChina PetroChina Research Institute of Petroleum Exploration&Development Beijing100083China

A large number of nanopores and complex fracture structures in shale reservoirs results in multi-scale flow of oil. With the development of shale oil reservoirs, the permeability of multi-scale media undergoes changes due to stress sensitivity, which plays a crucial role in controlling pressure propagation and oil flow. This paper proposes a multi-scale coupled flow mathematical model of matrix nanopores, induced fractures, and hydraulic fractures. In this model, the micro-scale effects of shale oil flow in fractal nanopores, fractal induced fracture network, and stress sensitivity of multi-scale media are considered. We solved the model iteratively using Pedrosa transform, semi-analytic Segmented Bessel function, Laplace transform. The results of this model exhibit good agreement with the numerical solution and field production data, confirming the high accuracy of the model. As well, the influence of stress sensitivity on permeability, pressure and production is analyzed. It is shown that the permeability and production decrease significantly when induced fractures are weakly supported. Closed induced fractures can inhibit interporosity flow in the stimulated reservoir volume (SRV). It has been shown in sensitivity analysis that hydraulic fractures are beneficial to early production, and induced fractures in SRV are beneficial to middle production. The model can characterize multi-scale flow characteristics of shale oil, providing theoretical guidance for rapid productivity evaluation.

关键词： Multi-scale coupled flow Stress sensitivity Shale oil Micro-scale effect Fractal theory

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Genomic divergence and mutation load in the Begonia masoniana complex from limestone karsts

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Plant Diversity 2024年第5期46卷 575-584页

作者： Yiqing chen Lina dong Huiqin Yi Catherine Kidner Ming Kang Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China Guangzhou 510650China University of Chinese Academy of Sciences Beijing 100049China Guangxi Key Laboratory of Conservation and Restoration Ecology in Karst Terrain Guangxi Institute of BotanyGuangxi Zhang Autonomous Region and the Chinese Academy of SciencesGuilin 541006China Institute of Molecular Plant Sciences University of EdinburghDaniel Rutherford Building Max Born CrescentThe King's BuildingsEdinburgh EH93BFUK Royal Botanic Garden Edinburgh 20a Inverleith RowEdinburgh EH35LRUK State Key Laboratory of Plant Diversity and Specialty Crops South China Botanical GardenChinese Academy of SciencesGuangzhou 510650China

Understanding genome-wide diversity,inbreeding,and the burden of accumulated deleterious mutations in small and isolated populations is essential for predicting and enhancing population persistence and ***,these effects are rarely studied in limestone karst ***,we re-sequenced the nuclear genomes of 62 individuals of the Begonia masoniana complex(***,***,*** and ***)and investigated genomic divergence and genetic load for these four *** analyses revealed four distinct clusters corresponding to each species within the ***,there was only limited admixture between *** and *** occurring in overlapping geographic *** species experienced historical bottlenecks during the Pleistocene,which were likely caused by glacial climate *** detected an asymmetric historical gene flow between group pairs within this timeframe,highlighting a distinctive pattern of interspecific divergence attributable to karst geographic *** found that isolated populations of *** have limited gene flow,the smallest recent population size,the highest inbreeding coefficients,and the greatest accumulation of recessive deleterious *** findings underscore the urgency to prioritize conservation efforts for these isolated *** study is among the first to disentangle the genetic differentiation and specific demographic history of karst Begonia plants at the whole-genome level,shedding light on the potential risks associated with the accumulation of deleterious mutations over generations of ***,our findings may facilitate conservation planning by providing critical baseline genetic data and a better understanding of the historical events that have shaped current population structure of rare and endangered karst plants.

关键词： Conservation genomics Karst landscape Demographic history Inbreeding Isolated populations Mutation load

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Mass transfer enhancement and hydrodynamic performance with wire mesh coupling solid particles in bubble column reactor

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Chinese Journal of Chemical Engineering 2024年第3期67卷 195-205页

作者： Chuanjun Di Jipeng dong Fei Gao Guanghui chen Pan Zhang Jianlong Li Key Laboratory of Multiphase Flow Reaction and Separation Engineering of Shandong Province College of Chemical EngineeringQingdao University of Science and TechnologyQingdao 266042China College of Electromechanical Engineering Qingdao University of Science and TechnologyQingdao 266043China

It is of vital significance to investigate mass transfer enhancements for chemical engineering *** work focuses on investigating the coupling influence of embedding wire mesh and adding solid particles on bubble motion and gas-liquid mass transfer process in a bubble *** image velocimetry(PIV)technology was employed to analyze the flow field and bubble motion behavior,and dynamic oxygen absorption technology was used to measure the gas-liquid volumetric mass transfer coefficient(kLa).The effect of embedding wire mesh,adding solid particles,and wire mesh coupling solid particles on the flow characteristic and kLa were analyzed and *** results show that the gas-liquid interface area increases by 33%-72%when using the wire mesh coupling solid particles strategy compared to the gas-liquid two-phase flow,which is superior to the other two strengthening *** with the system without reinforcement,kLa in the bubble column increased by 0.5-1.8 times with wire mesh coupling solid particles method,which is higher than the sum of kLa increases with inserting wire mesh and adding particles,and the coupling reinforcement mechanism for affecting gas-liquid mass transfer process was discussed to provide a new idea for enhancing gas-liquid mass transfer.

关键词： Fluid mechanics Bubble Mass transfer Wire mesh coupling solid particles Particle image velocimetry Hydrodynamics

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Genomic Surveillance for SARS-CoV-2 Variants: Dominance of XBB Replacement — China, January–June 2023

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China CDC weekly 2024年第15期6卷 324-331页

作者： Yenan Feng Qiudong Su Lili Li Xiaozhou He Peihua Niu Xiaojuan Guo xiang Zhao Jing Tang Zhiyuan Jia Ji Wang Changcheng Wu Baicheng Xia Zhixiao chen Yuchao Wu Jing Yang Songqi chen Cao chen Shiwen Wang Xiaoping dong National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases National Institute for Viral Disease Control and PreventionChinese Center for Disease Control and PreventionBeijingChina NHC Key Laboratory of Medical Virology and Viral Diseases National Institute for Viral Disease Control and PreventionChinese Center for Disease Control and PreventionBeijingChina

Introduction:In the first half of 2023,a global shift was observed towards the predominance of XBB *** faced a significant epidemic between late 2022 and early 2023 due to Omicron subvariants BA.5.2 and *** study aims to depict the evolving variant distribution among provincial-level administrative divisions(PLADs)in China and explore the factors driving the predominance of XBB ***:Sequences from local and imported coronavirus disease 2019(COVID-19)cases recorded between January 1 and June 30,2023,were *** study analyzed the changing distribution of viral variants and assessed how the prior dominance of specific variants,XBB subvariants,and imported cases influenced the prevalence of the XBB replacement ***:A total of 56,486 sequences were obtained from local cases,and 8,669 sequences were from imported *** in April,there was a shift in the prevalence of XBB from imported to local cases,with varying dominance among *** PLADs previously high in BF.7,the rise of XBB was delayed.A positive correlation was found between XBB proportions in imported cases from January to March and local cases in *** distribution pattern of XBB subvariants differed between local and imported cases within the same *** significant differences were noted in the replacement rates of XBB ***:The timing of XBB dominance differed among various PLADs in China in the first half of 2023,correlating closely with the prevalence of XBB variants among imported cases.

关键词： dominance imported distribution

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Efficient cutting path planning for a non-spherical tool based on an iso-scallop height distance field

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Chinese Journal of Aeronautics 2024年第7期37卷 496-510页

作者： Jiancheng HAO dong HE Zhaoyu LI Pengcheng HU Yuanzhi chen Kai TANG Department of Mechanical and Aerospace Engineering Hong Kong University of Science and TechnologyHong Kong 999077China The Hong Kong University of Science and Technology(Guangzhou) Smart Manufacturing ThrustNanshaGuangzhou 511400China HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute Shenzhen 518057China HKUST Shenzhen Research Institute Shenzhen 518057China

Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among various freeform surface machining strategies due to its high machining efficiency as well as better machine tool’s ***,all the existing iso-scallop height path planning methods pertain to only the ball-end or flat-end types of *** recent years,the non-spherical cutting tool has become more and more popular,especially for five-axis machining of complex freeform surfaces,majorly owing to its non-constant curvature which can be utilized to adaptively fit the tool to the surface to both avoid the local gouging and enlarge the cutting ***,there have been no reported works on iso-scallop height five-axis tool path generation for a non-spherical tool,and,in this paper,we present ***,we first define and construct two fields on the surface to be machined-the collision-free tool orientation field(vector)and the iso-scallop height distance field(scalar).The iso-lines of the scalar field and their associated tool orientation field vectors then naturally serve as potential iso-scallop height five-axis tool paths,and we present a propagation-based algorithm to construct the desired tool path from the *** computer simulation and physical cutting experiments confirm that everywhere on the surface,except maybe near the saddle curves of the scalar filed,the scallop height is exactly the given *** adding the saddle curves as extra tool paths,the final machined surface then is assured of the required scallop height requirement.

关键词： Freeform surface machining Iso-scallop tool path Customized tool Five-axis tool path Computer aided manufacturing

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Effects of dynamical spanwise retraction and stretch on flapping-wing forward flights

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Chinese Journal of Aeronautics 2024年第4期37卷 181-202页

作者： Kang LIU Bifeng SONG Ang chen Zhihe WANG dong XUE Wenqing YANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Intelligent Aircraft Research Center Chengdu Technological UniversityChengdu 610031China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Harbin Institute of Technology Shenzhen 518055China

Birds and bats retract and stretch their wings dynamically during each flap in level flights, implying intriguing mechanisms for the aerodynamic performance improvement of flapping wings. A numerical investigation into the aerodynamic effects of such bio-inspired concept in forward flights has been performed based on a three-dimensional wing in plunging motion and a twosection wing in flapping motion. The currently considered Reynolds number and Strouhal number are Re=1.5×10^(5) and St=0.3, respectively. During the research, the mean angle of attack is varied in relatively wide ranges to achieve lift-thrust interconversion for the wings. The conclusive results show that dynamical spanwise retraction and stretch has induced three absolutely desirable scenarios for the oscillating wings in forward flights, namely producing more lift and consuming less power for a given thrust generation, producing more thrust and consuming less power for a given lift generation, and producing more lift and more thrust while consuming less power. Furthermore,the morphing wings have alleviated periodical aerodynamic load fluctuations compared with the non-morphing baseline. The mechanism of the aerodynamic effects of the bionic morphing mode is analyzed with the aid of field visualization. The current article is the first to reveal the absolute advantages of the bionic spanwise morphing. Hopefully, it may help comprehend the behaviors of natural fliers and provide inspirations for performance enhancement of micro artificial flappingwing vehicles.

关键词： Flapping wing Morphing wing Bionic Aerodynamics Vortex Flight

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Efficient removal of natural organo-chromium(Ⅲ)through selfcirculating decomplex and immobilization with nanoscale zerovalent iron

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Nano Research 2024年第1期17卷 364-371页

作者： Zhicheng dong Yunyun Xu Can Wu Jin Chao chen Tian Zhang Lin School of Metallurgy and Environment Central South UniversityChangsha 410083China Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution Changsha 410083China College of Ecology and Environment Chengdu University of TechnologyChengdu 610059China School of Environment and Energy The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters(Ministry of Education)South China University of TechnologyGuangzhou 510006China

Organo-chromium(III)complex is one of the chromium contaminant species,which would transform to high-toxic Cr(VI)during migrating in the *** natural organo-chromium(III)(NOCr)is difficult to remove by traditional degradation or precipitation methods,due to its high stability and ***,we demonstrated a novel NOCr removing method by transforming it to certain structures similar to Cr-Fe minerals in nature,through a self-circulating decomplex and immobilization mechanism with nano zero-valent iron(nZVI).Taking chromium glycinate(Cr-Gly)as a probe,nZVI showed a high Cr removal efficiency of 99.4%under ambient *** removal process included three stages of adsorption,decomplexation,and ***-Gly was first adsorbed on the surface of nZVI by chemisorption of the oxide ***,the adsorbed Cr-Gly was decomplexed and oxidized to Cr(VI)by·OH and 1O_(2),which were generated from molecular oxygen activated by ***,the released Cr(VI)could be in-situ adsorbed and re-reduced to Cr(III),which was further immobilized in form of Cr-O-Fe *** the Cr-O-Fe complexing structure was similar to that of Cr-Fe minerals(such as chromohercynite)in nature,this work explored a novel and efficient NOCr removing method that was potential to weaken chromium pollution in the environment.

关键词： organo-chromium(III) zero-valent iron adsorption decomplexation Cr immobilization

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Synthesis and Modulation of Low-Dimensional Transition Metal Chalcogenide Materials via Atomic Substitution

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Nano-Micro Letters 2024年第9期16卷 49-94页

作者： Xuan Wang Akang chen XinLei Wu Jiatao Zhang Jichen dong Leining Zhang Key Laboratory of Cluster Science Ministry of Education of ChinaBeijing Key Laboratory of Photoelectronic and Electrophonic Conversion MaterialsSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081People’s Republic of China Beijing National Laboratory for Molecular Sciences Key Laboratory of Organic SolidsInstitute of Chemistry Chinese Academy of SciencesBeijing 100190People’s Republic of China

In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk *** controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various *** this context,the atomic substitution method has emerged as a favorable *** involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting *** this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC *** effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are *** enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these ***,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.

关键词： Transition metal chalcogenides Atomic substitution Ion exchange Low-dimensional materials Controllable synthesis

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Spark plasma sintering of tungsten-based WTaVCr refractory high entropy alloys for nuclear fusion applications

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 146-154页

作者： Yongchul Yoo xiang Zhang Fei Wang Xin chen Xing-Zhong Li Michael Nastasi Bai Cui Department of Mechanical&Materials Engineering University of Nebraska-LincolnLincolnNE 68588USA Nebraska Center for Materials and Nanoscience University of Nebraska-LincolnLincolnNE 68588USA Department of Nuclear Engineering Texas A&M UniversityCollege StationTX 77843USA

W-based WTaVCr refractory high entropy alloys (RHEA) may be novel and promising candidate materials for plasma facing components in the first wall and diverter in fusion reactors. This alloy has been developed by a powder metallurgy process combining mechanical alloying and spark plasma sintering (SPS). The SPSed samples contained two phases, in which the matrix is RHEA with a body-centered cubic structure, while the oxide phase was most likely Ta2VO6through a combined analysis of X-ray diffraction (XRD),energy-dispersive spectroscopy (EDS), and selected area electron diffraction (SAED). The higher oxygen affinity of Ta and V may explain the preferential formation of their oxide phases based on thermodynamic calculations. Electron backscatter diffraction (EBSD) revealed an average grain size of 6.2μm. WTaVCr RHEA showed a peak compressive strength of 2997 MPa at room temperature and much higher micro-and nano-hardness than W and other W-based RHEAs in the literature. Their high Rockwell hardness can be retained to at least 1000°C.

关键词： refractory high entropy alloy plasma-facing material fusion reactor spark plasma sintering

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