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Science China(Technological Sciences) 2024年第4期67卷 1160-1169页

作者： niu QingJing GAO ShuHui ZHU KongYing rEN Lixia YUAN xiaoYan School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin 300350China Analysis and Measurement Center Tianjin UniversityTianjin 300072China

Cryopreservation plays an essential role in biobanking and cell therapy,but the physiological toxicity of traditional cryoprotectants such as glycerol and dimethyl sulfoxide(DMSO)has raised safety issues for biomedical ***,a nonreducing disaccharide that accumulates in desiccation-or cold-tolerant organisms,has been considered as a biocompatible ***,a naturally occurring membrane-active cationic peptide,melittin,was utilized to facilitate membraneimpermeable trehalose entry into cells for effective cell ***(ethylene glycol)and poly(vinyl pyrrolidone)were applied as macromolecular protectants to improve the stabilization of cell *** the optimal protocol,the postthaw recovery of human red blood cells in freezing bags at a hematocrit of~50%could achieve 82.9%with favorable cell morphologies and physiological ***,the cryosurvival of L929 fibroblasts reached 84.3%compared to the conventional method using 10%(v/v)*** short,this work by using trehalose and melittin provides a biocompatible solvent-free approach for long-term cryostorage of cells.

关键词： melittin intracellular trehalose membrane stabilization macromolecular protectants cell cryopreservation

Charge-asymmetry Fe_(1)Cu single-atom alloy catalyst for efficient oxygen reduction reaction

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Nano research 2024年第6期17卷 4702-4710页

作者： xudong niu Jian Wei Dongyao xu Jiajing Pei rui Sui School of Chemical&Environmental Engineering China University of Mining and TechnologyBeijing 100083China Institute of Water Ecology and Environment Chinese Research Academy of Environmental SciencesBeijing 100083China Beijing Synchrotron radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Engineering research Center of Advanced rare Earth Materials Department of ChemistryTsinghua UniversityBeijing 100084China

The development of high-efficient and low-cost oxygen reduction reaction(Orr)electrocatalysts is crucial for the practical applications of metal-air *** promising way is to develop Fe single-atom ***,the single active center and inherent electronic structure of Fe single-atom catalysts lead to the undesirable adsorption of multiple Orr ***,a charge-asymmetry single-atom alloy(SAA)catalyst with Fe-Cu dual sites supported on nitrogen-doped carbon nanosheet(Fe_(1)Cu SAA/NC)was *** characterizations manifest the existence of electron interaction between Fe and Cu in Fe_(1)Cu SAA/NC,which facilitates the adsorption of Orr intermediate for fast ***,the charge-asymmetry Fe_(1)Cu SAA/NC exhibits much faster Orr kinetics with a half-wave potential of 0.917 V *** hydrogen electrode(rHE),outperforming its counterparts in the ***,Fe_(1)Cu SAA/NC still maintains a high half-wave potential with only a drop of 5 mV after 5000 cycles,indicating excellent *** work provides a new strategy to design highly active and non-noble metal Orr electrocatalysts,which hold great potential for various catalytic applications.

关键词： Fe_(1)Cu single-atom alloy(SAA) electrocatalysis oxygen reduction reaction charge-asymmetry

Intraspecific floral colour variation in three Pedicularis species

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Plant Diversity 2024年第2期46卷 274-279页

作者： Qiu-Yu Zhang Zhe Chen Hang Sun Yang niu State Key Laboratory of Plant Diversity and Specialty Crops Kunming Institute of BotanyChinese Academy of SciencesKunming 650201YunnanChina University of Chinese Academy of Sciences Beijing 100049China

Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging,reducing reproductive interference in natural *** extent of flower constancy is largely determined by the floral traits of co-flowering *** higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower ***,previous studies mainly focused on interspecific difference,and the intraspecific variation(consistency)of floral traits received much less *** hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering *** investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19communities composed of either single or multiple Pedicularis *** was quantified using image-based colour analysis as perceived by *** found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees,implying strongly constrained by the visual selection by *** to the hypothesis,there is no significant difference in intraspecific floral colour variation between different community *** may be due to the relatively large interspecific floral colour differences of most co-flowering *** influence of community context on intraspecific variation may be reflected in floral traits other than colours.

关键词： Flower constancy Floral colour variation Plantepollinator interactions Pollinator vision

Building a More Sustainable Chinese Loess Plateau

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Journal of Earth Science 2024年第1期35卷 283-287页

作者： Peiyue Li xiaomei Kou Yong Wang Le niu School of Water and Environment Chang'an UniversityXi'an 710054China Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid region of the Ministry of Education Chang'an UniversityXi'an 710054China Key Laboratory of Eco-Hydrology and Water Security in Arid and Semi-Arid regions of the Ministry of Water resources Chang'an UniversityXi'an 710054China PowerChina Northwest Engineering Corporation Limited Xi'an 710065China PowerChina Sinohydro Bureau 3 Co. LTD.Xi'an 710024China

The Chinese Loess Plateau,a region of remarkable ecological and economic value,grapples with significant water management challenges due to its distinctive geology and *** perspective offers a short review of the eco-environmental protection measures undertaken in the Loess Plateau,underscoring the transformative impacts of initiatives such as the“Grain for Green”***,it also highlights the enduring challenges,including land degradation,water resources issues,socio-economic inequities,and the implications of climate ***,water management emerges as a pivotal issue with far-reaching repercussions for soil conservation,biodiversity,and human *** paper concludes by proposing future actions,emphasizing the necessity for policy modifications,novel initiatives,and research to tackle these challenges and foster sustainable development in the Loess *** insights gained from this region could offer invaluable lessons for other regions confronted with similar challenges,thereby contributing to global efforts to mitigate desertification and champion sustainable development.

关键词： Loess Plateau eco-environmental protection water management sustainable development climate change

On traceable iterated line graph and hamiltonian path index

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 239-252页

作者： niu Zhao-hong xIONG Li-ming YANG Wei-hua School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China School of Mathematics and Statistics Beijing Key Laboratory on MCAACIBeijing Institute of TechnologyBeijing 100081China Department of Mathematics Taiyuan University of TechnologyTaiyuan 030024China

xiong and Liu[21]gave a characterization of the graphs G for which the n-iterated line graph L^(n)(G)is hamiltonian,for n≥*** this paper,we study the existence of a hamiltonian path in L^(n)(G),and give a characterization of G for which L^(n)(G)has a hamiltonian *** applications,we use this characterization to give several upper bounds on the hamiltonian path index of a graph.

关键词： iterated line graph traceable hamiltonian index hamiltonian path index

Gravity Change Caused by Heavy rainfall Detected by A gPhone Gravimeter in Zhengzhou,China

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Journal of Earth Science 2024年第4期35卷 1273-1276页

作者： Lelin xing Yufei Han xiaowei niu Lei Bai Innovation Academy for Precision Measurement Science and Technology Chinese Academy of SciencesWuhan430077China Wuhan Geodesy National Observation and research Station Wuhan430077China China Earthquake Networks Center Beijing100045China

The short-term effect of heavy rainfall on gPhone gravimeter observation at Zhengzhou Seismic Station is *** to the observation data during Jul.17–20,2021,the corrected gravity residual reflects the gravimetric response caused by heavy *** observed gravity change is dominated by the local effect considering topographic effect on *** deduced water depth near the observation station is about 300 mm.

关键词： gravity gravity change gravimeter heavy rain Zhengzhou

Actin-depolymerizing factors 8 and 11 promote root hair elongation at high pH

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Plant Communications 2024年第3期5卷 232-247页

作者： Dong Qian Tian Li Chen Zheng Yue niu Yingzhi niu Chengying Li Muxuan Wang Yang Yang Lizhe An Yun xiang Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations School of Life SciencesLanzhou UniversityLanzhou 730000China These authors contributed equally to this article

A root hair is a polarly elongated single-celled structure that derives from a root epidermal cell and func-tions in uptake of water and nutrients from the surrounding *** reports have demon-strated that short periods of high pH inhibit root hair extension;but the effects of long-term high-pH treat-ment on root hair growth are still ***,we report that the duration of root hair elongation is signicantly prolonged with increasing external pH,which counteracts the effect of decreasing root hair elongation rate and ultimately produces longer root hairs,whereas loss of actin-depolymerizing factor 8 and 11(ADF8/11)function causes shortening of root hair length at high pH(pH 7.4).Accumulation of ADF8/11 at the tips of root hairs is inhibited by high pH,and increasing environmental pH affects the actinlament(F-actin)meshwork at the root hair *** high pH,the tip-focused F-actin meshwork is absent in root hairs of the adf8/11 mutant,actinlaments are disordered at the adf8/11 root hair tips,and actin turn-over is *** and recycling vesicles do not aggregate in the apical region of adf8/11 root hairs at high ***,our results suggest that,under long-term exposure to high extracellular pH,ADF8/11 may establish and maintain the tip-focused F-actin meshwork to regulate polar trafcking of secretory/recycling vesicles at the root hair tips,thereby promoting root hair elongation.

关键词： pH ADF actin rab GTPase vesicle root hair

UAV-assisted cooperative offloading energy efficiency system for mobile edge computing

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Digital Communications and Networks 2024年第1期10卷 16-24页

作者： xue-Yong Yu Wen-Jin niu Ye Zhu Hong-Bo Zhu Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Nanjing210003China Engineering research Centerof Health Service System Based on Ubiquitous Wireless Networks Ministry of EducationNanjng Universityof Posts and Telecommunications Nanjing210003China

reliable communication and intensive computing power cannot be provided effectively by temporary hot spots in disaster areas and complex terrain ground *** this has greatly developed the application and integration of UAV and Mobile Edge Computing(MEC)to the Internet of Things(loT).However,problems such as multi-user and huge data flow in large areas,which contradict the reality that a single UAV is constrained by limited computing power,still *** to allowing UAV collaboration to accomplish complex tasks,cooperative task offloading between multiple UAVs must meet the interdependence of tasks and realize parallel processing,which reduces the computing power consumption and endurance pressure of *** the computing requirements of the user terminal,delay constraint of a computing task,energy constraint,and safe distance of UAV,we constructed a UAV-Assisted cooperative offloading energy efficiency system for mobile edge computing to minimize user terminal energy ***,the resulting optimization problem is originally nonconvex and thus,difficult to solve *** tackle this problem,we developed an energy efficiency optimization algorithm using Block Coordinate Descent(BCD)that decomposes the problem into three convex ***,we jointly optimized the number of local computing tasks,number of computing offloaded tasks,trajectories of UAV,and offloading matching relationship between multi-UAVs and multiuser *** results show that the proposed approach is suitable for different channel conditions and significantly saves the user terminal energy consumption compared with other benchmark schemes.

关键词： Computation offloading Internet of things(IoT) Mobile edge computing(MEC) Block coordinate descent(BCD)

Enhancing cut selection through reinforcement learning

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Science China Mathematics 2024年第6期67卷 1377-1394页

作者： Shengchao Wang Liang Chen Lingfeng niu Yu-Hong Dai Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing100190China research Center on Fictitious Economy and Data Science Chinese Academy of SciencesBeijing100190China

With the rapid development of artificial intelligence in recent years,applying various learning techniques to solve mixed-integer linear programming(MILP)problems has emerged as a burgeoning research *** from constructing end-to-end models directly,integrating learning approaches with some modules in the traditional methods for solving MILPs is also a promising *** cutting plane method is one of the fundamental algorithms used in modern MILP solvers,and the selection of appropriate cuts from the candidate cuts subset is crucial for enhancing *** to the reliance on expert knowledge and problem-specific heuristics,classical cut selection methods are not always transferable and often limit the scalability and generalizability of the cutting plane *** provide a more efficient and generalizable strategy,we propose a reinforcement learning(rL)framework to enhance cut selection in the solving process of ***,we design feature vectors to incorporate the inherent properties of MILP and computational information from the solver and represent MILP instances as bipartite ***,we choose the weighted metrics to approximate the proximity of feasible solutions to the convex hull and utilize the learning method to determine the weights assigned to each ***,a graph convolutional neural network is adopted with a self-attention mechanism to predict the value of weighting ***,we transform the cut selection process into a Markov decision process and utilize rL method to train the *** experiments are conducted based on a leading open-source MILP solver *** on both general and specific datasets validate the effectiveness and efficiency of our proposed approach.

关键词： reinforcement learning mixed-integer linear programming cutting plane method cut selection

Sliding behaviors of the trapezoidal roof rock block under a lateral dynamic disturbance

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Journal of rock Mechanics and Geotechnical Engineering 2024年第3期16卷 741-760页

作者： Feng Dai Wancheng Zhu Min ren Shunchuan Wu Leilei niu Faculty of Land resources Engineering Kunming University of Science and TechnologyKunming650093China Center for rock Instability and Seismicity research Department of Mining EngineeringSchool of Resource and Civil EngineeringNortheastern UniversityShenyang110819China

The surrounding rock of underground space is always affected by external dynamic disturbance from the side position,such as blasting vibration from a stope at the same level or seismic waves from adjacent strata.A series of laboratory tests,numerical simulations and theoretical analyses were carried out in this study to disclose the sliding mechanism of roof rock blocks under lateral ***,the experiments on trapezoidal key block under various clamping loads and disturbance were conducted,followed by numerical simulations using the fast Lagrangian analysis of continua(FLAC3D).Then,based on the conventional wave propagation model and the classical shear-slip constitutive model,a theoretical model was proposed to capture the relative displacement between blocks and the sliding displacement of the key *** results indicate that the sliding displacement of the key block increased linearly with the disturbance energy and decreased exponentially with the clamping load when the key block was disturbed to slide(without instability).Meanwhile,when the key block was disturbed to fall,two types of instability process may appear as immediate type or delayed *** addition,the propagation of stress waves in the block system exhibited obvious low-velocity and lowfrequency characteristics,resulting in the friction reduction effect appearing at the contact interface,which is the essential reason for the sliding of rock *** results can be applied to practical underground engineering and provide valuable guidance for the early detection and prevention of rockfalling disasters.

关键词： Lateral dynamic disturbance Trapezoidal rock block system Low-velocity and low-frequency wave Friction reduction effect Instability mode