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Characteristics of Vegetation and Soil of Degraded Grasslands and Their Relationships in Xizang

Huanjing Kexue/Environmental Science 2024年第9期45卷 5341-5350页

作者： Li, Qing-wan Gu, Jin-Kai Li, Qing-Lin Li, wan-Chi xiang, Sheng-Jian Tang, guo-Yong Institute Highland Forest Science Chinese Academy of Forestry Kunming 650233 China College of Landscape Architecture Nanjing Forestry University Nanjing 210037 China Institute of International Rivers and Eco-security Yunnan University Kunming 650504 China

To investigate the characteristics of grassland degradation on a regional scale in Xizang,data on grassland degradation from the second grassland survey of Xizang and 12 vegetation and soil indicators from the National Tibetan Plateau Data Center were collected. Using ArcMap,10 000 random sample points were selected on raster data(excluding non-grassland,desertification,and salinization data,leaving 7 949 valid sample points). The multi-value extraction to-point method was applied to extract degradation and indicator data for each sample point. The characteristics of degraded grassland vegetation and soil and their relationships were analyzed in Xizang. Moreover,random forest modeling was conducted to predict the trend of grassland ecosystem changes. The results indicated that:① The grasslands in Xizang were primarily composed of alpine steppe and alpine meadow types, accounting for 45.83% and 41.15% of the valid sample points,respectively. ② With the intensification of grassland degradation,the number of steppe-type species among the 17 grassland types gradually decreased,and the proportion of steppe dominated by species such as Stipa purpurea and Carex moorcroftii decreased,whereas the proportion of miscellaneous grasses and Dasiphora fruticosa increased. ③ As the degree of degradation increased,vegetation indicators generally showed a declining trend,with soil total nitrogen, total phosphorus,total potassium,and organic carbon decreasing,whereas soil pH and bulk density increased,and soil moisture content was not significant. ④ A positive correlation exists between soil moisture content,total nitrogen,total phosphorus,total potassium,organic carbon,vegetation cover,net primary productivity of vegetation,normalized difference vegetation index,aboveground biomass,and habitat quality. However,there was a negative correlation between pH and soil bulk density,and the correlation coefficients among various indicators decreased with the intensification of degradation. ⑤

关键词： Abiotic

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Light People:*** May Lau,newly elected US NAE member in Hong Kong,talks about future of photonics and women in science

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Light(Science & Applications) 2024年第4期13卷 602-608页

作者： Yating wan Chenzi guo Electrical and Computer Engineering the ComputerElectrical and Mathematical Sciences and Engineering DivisionKing Abdullah University of Science and Technology23955-6900 ThuwalSaudi Arabia Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchunChina

Editorial Photonics technology remains a driving force in today’s scientific landscape,marked by continuous innovation and crossdisciplinary *** an enlighting conversation with Light:Science&Applications,*** May Lau,a pioneer in photonics research,shares her deep insights on the evolution of technologies of LEDs,lasers,challenges of hetero-epitaxy,and the future of micro-LEDs and quantum dot *** honored as a member of the US National Academy of Engineering(NAE)for her significant contributions to photonics and electronics using III-V semiconductors on silicon,*** stands out as the sole Hong Kong scholar inducted into the NAE this year,joining 114 new and 21 international *** this exclusive Light People interview,*** shares her journey as a pioneering woman in engineering,her commitment to mentorship and academia,and her perspective on advancing female representation in *** summary provided is distilled from ***’s thoughtful responses during the *** a deeper exploration of ***’s experiences and advice,the full interview is available in the Supplementary material.

关键词： interview lighting driving

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Effect of slow shot speed on externally solidified crystal,porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy

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China Foundry 2024年第1期21卷 11-19页

作者： Wen-ning Liu Wei Zhang Peng-yue wang Yi-xian Liu xiang-yi Jiao Ao-xiang wan Cheng-gang wang guo-dong Tong Shou-mei Xiong School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084Beijing China FAW Group Co. Ltd.Changchun 130013China China FAW Foundry Co. Ltd.Changchun 130013China

The effect of slow shot speed on externally solidified crystal(ESC),porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy(OM),scanning electron microscopy(SEM)and laboratory computed tomography(CT).Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg *** AlSi9MnMoV alloy,which was designed with trace multicomponent additions,displays a notable grain refining effect in comparison to the AlSi10MnMg *** elements Ti,Zr,V,Nb,B promote heterogeneous nucleation and reduce the grain size of primaryα-*** a lower slow shot speed,the large ESCs are easier to form and gather,developing into the dendrite net and *** an increase in slow shot speed,the size and number of ESCs and porosities significantly *** addition,the distribution of ESCs is more dispersed and the net-shrinkage *** tensile property is greatly improved by adopting a higher slow shot *** ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa(increased by 11.52%),and the elongation is enhanced from 3.72%to 6.34%(increased by 70.52%).

关键词： hypoeutectic Al-Si alloy high pressure die casting porosity externally solidified crystal tensile property

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Vibration Control of A Flexible Marine Riser System Subject to Input Dead Zone and Extraneous Disturbances

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China Ocean Engineering 2024年第2期38卷 271-284页

作者： ZHOU Li wanG guo-rong wan Min School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China Energy Equipment Institute Southwest Petroleum UniversityChengdu 610500China National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China

An observer-based adaptive backstepping boundary control is proposed for vibration control of flexible offshore riser systems with unknown nonlinear input dead zone and uncertain environmental *** control algorithm can update the control law online through real-time data to make the controller adapt to the environment and improve the control ***,based on the adaptive backstepping framework,virtual control laws and Lyapunov functions are designed for each *** direction interference observers are designed to track the timevarying boundary *** this basis,the inverse of the dead zone and linear state transformation are used to compensate for the original system and eliminate the adverse effects of the dead *** addition,the stability of the closed-loop system is proven by Lyapunov stability *** the system states are bounded,and the vibration offset of the riser converges to a small area of the initial ***,four examples of flexible marine risers are simulated in MATLAB to verify the effectiveness of the proposed controller.

关键词： adaptive backstepping control disturbance observer flexible marine riser input dead zone vibration control

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Recent Advances in Mechanistic Understanding of Metal-Free Carbon Thermocatalysis and Electrocatalysis with Model Molecules

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Nano-Micro Letters 2024年第7期16卷 74-97页

作者： Wei guo Linhui Yu Ling Tang Yan wan Yangming Lin CAS Key Laboratory of Design and Assembly of Functional Nanostructures Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002People’s Republic of China Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen 361021People’s Republic of China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002People’s Republic of China Institute of Urban Environment Chinese Academy of SciencesXiamen 361021People’s Republic of China

Metal-free carbon,as the most representative heterogeneous metal-free catalysts,have received considerable interests in electro-and thermo-catalytic reac-tions due to their impressive performance and *** the past decade,well-designed carbon catalysts with tunable structures and heteroatom groups coupled with various characterization techniques have proposed numerous reaction ***,active sites,key intermediate species,precise structure-activity relationships and dynamic evolution processes of carbon catalysts are still rife with controversies due to the monotony and limitation of used experimental *** this Review,we sum-marize the extensive efforts on model catalysts since the 2000s,particularly in the past decade,to overcome the influences of material and structure limitations in metal-free carbon *** both nanomolecule model and bulk model,the real contribution of each alien species,defect and edge configuration to a series of fundamentally important reactions,such as thermocatalytic reactions,electrocatalytic reactions,were systematically *** with in situ techniques,isotope labeling and size control,the detailed reaction mechanisms,the precise 2D structure-activity relationships and the rate-determining steps were revealed at a molecular ***,the outlook of model carbon catalysis has also been proposed in this work.

关键词： Metal-free carbon catalysts Model catalyst Electrocatalysis Active site Reaction mechanisms

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Weighted Composition Operators That Preserve Frames On Weighted Hardy Spaces

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1645-1654页

作者： Ya Li Dong Rui Liu guo xiang Lu School of Mathematical Sciences and LPMC Nankai UniversityTianjin300071P.R.China School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan430073P.R.China

In this paper, we characterize weighted composition operators that preserve frames on the weighted Hardy spaces in the unit disk. In particular, we obtain the symbol properties of the bounded invertible weighted composition operators. Moreover, we establish the equivalence between bounded invertible operators and frame-preserving operators. Furthermore, we show that weighted composition operator preserves frames if and only if it preserves the Riesz bases property. Additionally,we investigate the weighted composition operators that preserve tight or normalized tight frames on the Dirichlet space.

关键词： Weighted composition operators Weighted Hardy spaces frames invertible

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Solid-state lithium-ion batteries for grid energy storage:opportunities and challenges

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Science China Chemistry 2024年第1期67卷 43-66页

作者： Xin Chang Yu-Ming Zhao Boheng Yuan Min Fan Qinghai Meng Yu-guo guo Li-Jun wan CAS Key Laboratory of Molecular Nanostructure and Nanotechnology CAS Research/Education Center for Excellence in Molecular SciencesBeijing National Laboratory for Molecular Sciences(BNLMS)Institute of ChemistryChinese Academy of Sciences(CAS)Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The energy crisis and environmental pollution drive more attention to the development and utilization of renewable *** the capricious nature of renewable energy resource,it has difficulty supplying electricity directly to consumers stably and efficiently,which calls for energy storage systems to collect energy and release electricity at peak *** to their flexible power and energy,quick response,and high energy conversion efficiency,lithium-ion batteries stand out among multiple energy storage technologies and are rapidly deployed in the *** superior performance and ensuring the safety of energy storage systems,intrinsically safe solid-state electrolytes are expected as an ideal alternative to liquid *** this review,we systematically evaluate the priorities and issues of traditional lithium-ion batteries in grid energy *** lithium-ion batteries containing liquid electrolytes,solid-state lithium-ion batteries have the potential to play a more significant role in grid energy *** challenges of developing solid-state lithium-ion batteries,such as low ionic conductivity of the electrolyte,unstable electrode/electrolyte interface,and complicated fabrication process,are discussed in ***,the safety of solid-state lithium-ion batteries is *** the obtained insights,inspiring prospects for solid-state lithium-ion batteries in grid energy storage are depicted.

关键词： lithium-ion batteries grid energy storage solid-state electrolytes interface stability

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Deep genome skimming reveals the hybrid origin of Pseudosasa gracilis (Poaceae: Bambusoideae)

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Plant Diversity 2024年第3期46卷 344-352页

作者： xiang-Zhou Hu Cen guo Sheng-Yuan Qin De-Zhu Li Zhen-Hua guo Germplasm Bank of Wild Species Kunming Institute of BotanyChinese Academy of SciencesKunmingYunnan 650201China University of Chinese Academy of Sciences Beijing 100049China

Pseudosasa gracilis(Poaceae:Bambusoideae)is a temperate woody bamboo species endemic to Southcentral China with a narrow *** phylogenetic studies revealed an unexpected,isolated phylogenetic position of *** we conducted phylogenomic analysis by sampling populations of *** and its sympatric species *** and Sinosasa polytricha reflecting different genomic signals,by deep genome *** molecular evidence from chloroplast genes and genome-wide SNPs,we deciphered the phylogenetic relationships of *** plastid and nuclear data indicate that *** is more closely related to Sinosasa,which is discordant with the taxonomic *** further explore this molecular-morphological conflict,we screened 411“perfect-copy”syntenic genes to reconstruct phylogenies using both the concatenation and coalescent *** observed extensive discordance between gene trees and the putative species tree.A significant hybridization event was detected based on 411 genes from the D subgenome,showing *** was a hybrid descendant between Sinosasa longiligulata and ***,with 63.56%and 36.44%inheritance probabilities of each ***,introgression events were detected in the C subgenome between *** and *** in the same distribution *** findings suggest that sympatric hybridization and introgression play a crucial role in the origin of *** providing an empirical example of bamboo of hybrid origin using comprehensive analyses based on genomic data from different inheritance systems and morphological characters,our study represents a step forward in understanding of reticulate evolution of bamboos.

关键词： Phylogenomics Hybridization Introgression Pseudosasa gracilis Pseudosasa Sinosasa

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A novel subset assignment and matching method for DIC measurement of complex deformation in aircraft braking process

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Chinese Journal of Aeronautics 2024年第8期37卷 373-387页

作者： Xin SHI xiang guo Tao SUO Yingtao YUAN Hongli HE Zhiyong REN School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China International Research Laboratory of Impact Dynamics and its Engineering Application Xi’an 710072China Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China Chinese Flight Test Establishment Xi’an 710089China

This paper proposes a measurement method related to the braking deformation of a complex *** the braking process,the deformation of the wheel includes large amounts of movement,vibration,warping,and distortion.A novel subset assignment and correlation method is proposed to measure the complex *** proposed method can greatly improve the accuracy and stability of the calculation of complex deformations by simplifying the complex deformation into translational deformations in logarithmic coordinate *** to the simulation and actual experiments,the proposed method can be utilized to measure the deformations of up to 100%tensile strain under complex *** to the accuracy verification experiment,the error of the proposed method is less than 50 *** results show that the proposed method can effectively carry out structural deformation measurement in the complex motion and deformation *** proposed method has great significance for structural performance analysis and optimization design considering complex motion and deformation.

关键词： Complex deformation Measurement Digital image correlation Aircraft braking Deformation field

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Colo-colonic intussusception as a rare complication of colonoscopy with polypectomy: Two case reports

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World Journal of Gastrointestinal Surgery 2024年第6期16卷 1939-1947页

作者： Sai-Heng xiang guo-Qiang Xu Department of Gastroenterology The First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003Zhejiang ProvinceChina

BACKGROUND Colonoscopy is the most frequently used diagnostic and therapeutic tool for the treatment of colorectal *** the complication rate is low,it can be potentially *** is a rare and severe complication often associated with *** a handful of post-colonoscopy intussusception cases have been reported,making this study a valuable addition to the medical *** SUMMARY Case 1:A 61-year-old man underwent colonoscopy with polypectomy for chronic abdominal *** patient experienced abdominal pain 11 hours later but was still discharged after pain *** was readmitted due to recurring *** tomography(CT)showed colo-colonic *** conservative management and attempts at endoscopic reduction failed;therefore,laparoscopic right hemicolectomy was *** examination revealed tubular adenomas in the polyps and inflammation in the resected *** 2:A 59-year-old woman underwent colonoscopy with polypectomy for a polyp in the transverse *** experienced upper abdominal pain,fever,nausea,and vomiting 9 hours after the *** CT and blood tests revealed a colo-colonic intussusception near the hepatic flexure and an elevated white blood cell *** attempts at endoscopic reduction failed and conservative treatment showed no *** underwent successful laparoscopic reduction and recovered *** examination of the resected polyp revealed *** Post-colonoscopy intussusception in adults is rare,and polypectomy may contribute to its *** diagnosis is crucial,with prompt CT examination serving as *** excluding malignancies,conservative management and reduction of intussusception should be considered before surgical bowel resection.

关键词： Intussusception Colonoscopy Polypectomy Complication Case report

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