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Rubik's cube as in-situ programmable matter and a reconfigurable mechanical metamaterial

Science China Technological Sciences 2024年第10期67卷 3221-3234页

作者： ZHU ShaoWei CHEN Huan YANG XiaoQiang tan Li JIN Shuai CHEN LiMing LIU Tao tan XiaoJun WANG LianChao WANG Bing MUAMER Kadic College of Aerospace Engineering Chongqing University State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University School of Civil Aviation Northwestern Polytechnical University National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Institut FEMTO-ST CNRS UMR 6174University Bourgogne

As part of the 4th industrial revolution, programmable mechanical metamaterials exhibit great application potential in flexible robotics, vibration control, and impact protection. However, maintaining a programmed state without sustaining the external stimulus is often challenging and leads to additional energy consumption. Inspired by Rubik's cube, we design and study an insitu programmable and distribution-reconfigurable mechanical metamaterial(IPDR-MM). A matrix model is developed to model IPDR-MMs and describe their morphological transitions. Based on this model, the reinforcement learning method is employed to find the pathways for morphological transitions. We find that IPDR-MMs have controllable stiffness across several orders of magnitude and a wide range of adjustable anisotropies through morphology transformation. Additionally, because of the independence of the directions of morphology transformation and bearing, IPDR-MMs exhibit good stability in bearing and can readily achieve high stiffness. The Rubik's cube-inspired design concept is also instructive for other deformable structures and metamaterials, and the current version of the proposal should be sufficiently illustrative to attract and broaden interdisciplinary interests.

关键词： mechanical metamaterials in-situprogrammable distribution-reconfigurable Rubik's cube controllable stiffness and anisotropy

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Historical Changes and Multi-scenario Prediction of Land Use and Terrestrial Ecosystem Carbon Storage in China

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Chinese Geographical Science 2024年第3期34卷 487-503页

作者： AN Yue tan Xuelan REN Hui LI Yinqi ZHOU Zhou College of Resources Hunan Agricultural UniversityChangsha 410128China School of Geographic Science Hunan Normal UniversityChangsha 410081China

Terrestrial carbon storage(CS)plays a crucial role in achieving carbon balance and mitigating global climate *** study employs the Shared Socioeconomic Pathways and Representative Concentration Pathways(SSPs-RCPs)published by the Intergovernmental Panel on Climate Change(IPCC)and incorporates the Policy Control Scenario(PCS)regulated by China’s land management *** Future Land Use Simulation(FLUS)model is employed to generate a 1.km resolution land use/cover change(LUCC)dataset for China in 2030 and *** on the carbon density dataset of China’s terrestrial ecosystems,the study analyses CS changes and their relationship with land use changes spanning from 1.90 to *** findings indicate that the quantitative changes in land use in China from 1.90 to 2020 are characterised by a reduction in the area proportion of cropland and grassland,along with an increase in the impervious surface and forest *** changing trend is projected to continue under the PCS from 2020 to *** the SSPs-RCPs scenario,the proportion of cropland and impervious surface predominantly increases,while the proportions of forest and grassland continuously *** loss in China’s carbon storage from 1.90 to 2020 amounted to 0.53×1.^(1.)kg,primarily due to the reduced area of cropland and *** the SSPs-RCPs scenario,more significant carbon loss occurs,reaching a peak of8.07×1.^(1.)kg in the SSP4-RCP3.4 *** loss is mainly concentrated in the southeastern coastal area and the Beijing-TianjinHebei(BTH)region of China,with urbanisation and deforestation identified as the primary *** the future,it is advisable to enhance the protection of forests and grassland while stabilising cropland areas and improving the intensity of urban *** research findings offer valuable data support for China’s land management policy,land space optimisation,and the achievement of dual-carbon targets.

关键词： land use change Future Land Use Simulation(FLUS)model carbon storage carbon density dataset land use scenario China

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Impact of climate change on food security in the Central Asian countries

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Science China Earth Sciences 2024年第1期67卷 268-280页

作者： Fang SU Yu LIU Lvfan CHEN Rustam OROZBAEV Liangcheng tan School of Economics and Management Northwest UniversityXi’an 710127China School of Economics and Management Shaanxi University of Science and TechnologyXi’an 710021China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China Institute of Geology National Academy of Sciences of Kyrgyz RepublicBishkek 720040Kyrgyzstan Institute of Global Environmental Change Xi’an Jiaotong UniversityXi’an 710049China

The current and potential impacts of global warming have generated widespread concerns about food security among all sectors of *** Asian countries located deep in the interior of Asia with fragile ecological environments and lower agricultural technology are particularly more prone to severe threats from climate *** on panel data acquired in five Central Asian countries from 1.90 to 201.,a C-D-C model was developed to study how climate change affects food security in the region and to predict future *** study found that the level of food security has generally increased for these five Central Asian countries over the past 30 years,with Kazakhstan and Tajikistan having the highest and lowest food security levels,*** average annual temperature and precipitation exhibit an inverted U-shaped relationship with the region’s food security,with the most positive effect on the food security of *** high and low temperatures have significantly affected food security in the studied region,with Turkmenistan experiencing the most significant negative *** number of frost days had no significant effect on food *** analysis of future climate showed that the temperature and precipitation in Central Asia will continue to increase from 2030 to 2090,which will negatively impact the food security of these *** is recommended that the Central Asian countries enhance their understanding of climate risks,strengthen scientific climate research,and develop multiple adaptation strategies in ***,they are encouraged to consolidate international cooperation,reducing greenhouse gas emissions effectively and maintaining the ability to ensure food security.

关键词： Global warming Extreme climate Food security Future forecasts Five Central Asian countries

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Transfer-learning multi-input multi-output equalizer for mode-division multiplexing systems

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Chinese Optics Letters 2024年第7期22卷 12-18页

作者： Tianfeng Zhao Feng Wen Mingming tan Baojian Wu Bo Xu Kun Qiu Key Laboratory of Optical Fiber Sensing and Communication Ministry of EducationUniversity of Electronic Science and Technology of ChinaChengdu 611731China Aston Institute of Photonics Technologies Aston UniversityBirmingham B47ETUK

We propose a transfer-learning multi-input multi-output(TL-MIMO)scheme to significantly reduce the required training complexity for converging the equalizers in mode-division multiplexing(MDM)*** on a built three-mode(LP01.LP1.a,and LP1.b)multiplexed experimental system,we thoughtfully investigate the TL-MIMO performances on the three-typed data,collecting from different sampling times,launching optical powers,and inputting optical signal-to-noise ratios(OSNRs).A dramatic reduction of approximately 40%–83.33%in the required training complexity is achieved in all three ***,the good stability of TL-MIMO in both the launched powers and OSNR test bands has also been proved.

关键词： mode division multiplexing multi-input multi-output transfer learning training complexity

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Bifunctional interstitial phosphorous doping strategy boosts platinum-zinc alloy for efficient ammonia oxidation reaction and hydrogen evolution reaction

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Nano Research 2024年第3期17卷 1182-1189页

作者： Tianqi Yu Kexin tan Jia Wu Yongjin Zou Shibin Yin Guangxi Key Laboratory of Electrochemical Energy Materials School of Chemistry and Chemical EngineeringGuangxi UniversityNanning 530004China Guangxi Key Laboratory of Information Materials Guilin University of Electronic TechnologyGuilin 541004China

It is still a lack of bifunctional catalysts for ammonia oxidation reaction(AOR)and hydrogen evolution reaction(HER)due to their different reaction *** this work,P is doped into PtZn alloy by calcination with NaH_(2)PO_(2) as P source to induce the lattice tensile strain of Pt and the electronic interaction between P and Zn,which optimizes the AOR and HER activity *** sample with the optimal P content can drive the AOR peak current density of 293.6 mA·mgPt^(-1.,which is almost 2.7 times of *** HER,the overpotential at^(-1.0 mA·cm^(-2) is only 23 mV with Tafel slope of 34.1.mV·dec^(-1..Furthermore,only 0.59 V is needed to obtain 50 mA·mgPt^(-1. for ammonia electrolysis under a two-electrode ***,this work shows an ingenious method to design bifunctional catalysts for ammonia electrolysis.

关键词： PtZn alloy phosphorous doping ammonia oxidation reaction hydrogen evolution reaction bifunctional catalyst

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Effects of rafting on the meso deformation and fracture behaviour of a Ni-based single crystal superalloy at room temperature: In-situ observation and simulation

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Science China(Technological Sciences) 2024年第7期67卷 2133-2146页

作者： tan Long YANG XiaoGuang SHI DuoQi FAN YongSheng SHI Yi School of Energy and Power Engineering Beihang UniversityBeijing 102206China Research Institute of Aero-Engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 102206China School of Materials Science&Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Microstructural rafting of Ni-based single-crystal(SC) superalloys is inevitable at elevated temperatures during long-term service with mechanical loading, which significantly affects the mechanical behaviour of the material. In this study, the effects of rafting on the mesodeformation and fracture behaviour of a Ni-based SC superalloy under cyclic and tensile loads were investigated using in situ scanning electron microscopy(SEM), digital image correlation(DIC), and crystal plasticity finite element method(CP-FEM) simulations. The results indicated that the tensile strength decreased significantly in the rafted specimens. In the cyclic tests, both the virgin and rafted specimens showed an increase in the maximum shear strain with cycle number. The interaction of cross-slip bands was captured by in situ SEM-DIC around the micro-notch of the virgin specimens during the tensile test, while a more homogeneous local deformation field was observed in the rafting specimens. In addition,the fracture behaviour was strongly influenced by the rafting morphology. The crack exhibited instantaneous and long-range fracture features along the octahedral plane as it propagated in the rafting specimen, whereas it deflected over a short distance between the crystallographic planes at an early stage in the virgin specimen, which is consistent with the CP-FEM ***, the CP-FEM results for the crack initiation direction on(1.1. dominant slip plane were consistent with the in situ SEM observations.

关键词： in-situ SEM-DIC Ni-based SC superalloys microstructural rafting deformation crack path CP-FEM

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Advancing mid-infrared microdisk laser emission with Tm:YAG

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 91-96页

作者： Zhaocong Wang Huiqi Li Lei Wang Yang tan Feng Chen School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China

Mid-infrared microcavity lasers have important applications in biosensing,mid-infrared spectroscopy,and environmental ***,the low output power of existing mid-infrared microcavity lasers hinders their practical *** drawback is attributed to the insufficient laser gain medium,which limits the development of mid-infrared whispering-gallerymode(WGM)*** address this issue,we have employed ion implantation-enhanced etching to fabricate Tm:YAG thin films as effective gain media for mid-infrared WGM *** Tm:YAG thin film,with a thickness of 2μm,exhibits excellent fluorescence ***,the Tm:YAG thin film is processed using focused ion beam to form microdisks with a diameter of 30μ*** 785 nm laser pumping,the maximum output power of the Tm:YAG microdisk at 2023.1.nm is229μW,with a slope efficiency of 2.9%.This work demonstrates the outstanding potential of Tm:YAG as a mid-infrared laser gain medium,providing a new option for the development of mid-infrared lasers.

关键词： microdisk microlaser ultrathin film

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Self-assembled amphiphilic NIR-Ⅱ emissive nano-micelles for imaging-guided photothermal therapy of colorectal cancer

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Science China Chemistry 2024年第8期67卷 2767-2774页

作者： Axin He Fangfang Xia Da Han Qinglai Yang Weihong tan Institute of Molecular Medicine(IMM) Renji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200240China Center for Molecular Imaging Probe Hunan Province Key Laboratory of Cancer Cellular and Molecular PathologyCancer Research InstituteHengyang Medical SchoolUniversity of South ChinaHengyang 421001China The Key Laboratory of Zhejiang Province for Aptamers and Theranostics Zhejiang Cancer Hospital Hangzhou Institute of Medicine(HIM)Chinese Academy of SciencesHangzhou 310022China Molecular Science and Biomedicine Laboratory(MBL) State Key Laboratory of Chemo/Biosensing and ChemometricsCollege of Chemistry and Chemical EngineeringCollege of BiologyAptamer Engineering Center of Hunan ProvinceHunan UniversityChangsha 410082China

Colorectal cancer(CRC) is one of the major causes of cancer-related mortality worldwide. Most near-infrared(NIR) agents used in clinical CRC treatment are at NIR-I(700–900 nm) window, which has limitations on deep tissue, and fluorescent probes in the second NIR(1.000–1.700 nm) allow high-resolution bioimaging with deep tissue penetration. However, existing NIR-II fluorophores used in clinical are still rare. Herein, based on shielding-donor-acceptor-donor-shielding(S-D-A-D-S) scaffold, we developed an organic small-molecule fluorophore IR-BTGP with NIR-II emission for imaging-guided photothermal therapy(PTT) in CRC mice model. Amphiphilic IR-BTGP can be self-assembled into spherical nano-micelles, which presents reliable water solubility and photothermal conversion efficiency(30.2%). In vitro experiments indicate that cancer cells treated with IRBTGP were significantly killed upon 808 nm light irradiation. Furthermore, in vivo NIR-II fluorescence imaging confirms that IR-BTGP accumulates in the tumor region. Remarkably, a significant tumor inhibition rate(78.5%) was observed in tumorbearing mice when treated with IR-BTGP plus 808 nm irradiation. Therefore, this work shows that IR-BTGP holds great promise as an NIR-II fluorescence imaging-guided PTT platform for CRC in the future.

关键词： photothermal therapy(PTT) second near-infrared(NIR-Ⅱ)imaging organic molecule

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Estimate pose deviation of on-orbit deployable mechanisms based on cross-ratio invariability

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Chinese Journal of Aeronautics 2024年第10期37卷 483-492页

作者： Peiran ZHANG Fuqiang ZHOU Zhipeng SONG Wentao GUO Haishu tan School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China School of Physics and Optoelectronic Engineering Foshan UniversityFoshan 528225China

With the rapid development of space science projects,large deployable mechanisms have been widely ***,due to the effects of mechanical friction and gravitational acceleration,on-orbit mechanisms cannot be always deployed to the expected *** some precision optical mechanisms,even a minor deviation can result in significant error,so it needs to be measured and *** this paper,the deployment process was modeled and simplified as rotation under single-rotation-axis constraint and translation under single-direction *** solve the problem,a method based on cross-ratio invariability was *** proposed method does not rely on camera calibration techniques,as well as artificial marking points,both of which are necessary in ***,only three calibration images before launch and a measurement image on orbit were *** and experiments demonstrated that the proposed method is more accurate than *** addition,experiments also proved that the feasibility of the proposed method under dark conditions with the aid of a light source and some reflective marking points.

关键词： Cross-ratio invariability Deployable mechanism Pose deviation estimation Single-DOF constraint Vision measurement

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Three-dimensional numerical manifold method for heat conduction problems with a simplex integral on the boundary

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Science China(Technological Sciences) 2024年第4期67卷 1007-1022页

作者： TONG DeFu YI XiongWei tan Fei JIAO YuYong LIANG JiaWei Faculty of Engineering China University of GeoscienceWuhan 430074China Department of Civil Engineering Monash UniversityMelbourne VIC 3800Australia Badong National Observation and Research Station of Geohazards China University of GeoscienceWuhan 430074China

The three-dimensional numerical manifold method(3D-NMM),which is based on the derivation of Galerkin's variation,is a powerful calculation tool that uses two cover *** 3D-NMM can be used to handle continue-discontinue problems and extend to THM *** this study,we extended the 3D-NMM to simulate both steady-state and transient heat conduction *** modelling was carried out using the raster methods(RSM).For the system equation,a variational method was employed to drive the discrete equations,and the crucial boundary conditions were solved using the penalty *** solve the boundary integral problem,the face integral of scalar fields and two-dimensional simplex integration were used to accurately describe the integral on polygonal *** numerical examples were used to verify the results of 3D steady-state and transient heat-conduction *** numerical results indicated that the 3D-NMM is effective for handling 3D both steadystate and transient heat conduction problems with high solution accuracy.

关键词： three-dimensional numerical manifold method transient analysis heat conduction problem Galerkin variation simplex integration

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