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Tuning mechanical behaviors of highly entangled hydrogels with the random distribution of mobile entanglements

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 277-294页

作者： Jinlong LIU Di lu Bin CHEN Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China Beijing System Design Institute of Electro-Mechanic Engineering Beijing 100854China Intelligent Robotic Research Center Zhejiang LaboratoryHangzhou 310027China Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Hangzhou 311100China

Highly entangled hydrogels exhibit excellent mechanical properties,including high toughness,high stretchability,and low *** considering the evolution of randomly distributed entanglements within the polymer network upon mechanical stretches,we develop a constitutive theory to describe the large stretch behaviors of these *** the theory,we utilize a representative volume element(RVE)in the shape of a cube,within which there exists an averaged chain segment along each edge and a mobile entanglement at each *** employing an explicit method,we decouple the elasticity of the hydrogels from the sliding motion of their entanglements,and derive the stress-stretch relations for these *** present theoretical analysis is in agreement with experiment,and highlights the significant influence of the entanglement distribution within the hydrogels on their *** also implement the present developed constitutive theory into a commercial finite element software,and the subsequent simulations demonstrate that the exact distribution of entanglements strongly affects the mechanical behaviors of the structures of these ***,the present theory provides valuable insights into the deformation mechanism of highly entangled hydrogels,and can aid in the design of these hydrogels with enhanced performance.

关键词： highly entangled hydrogel constitutive theory entanglement gamma distribution

Theoretical insights of the pharmaceutical compound fluoxetine in water:Role in direct photolysis and indirect photolysis by free radicals

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Journal of Environmental Sciences 2024年第8期142卷 269-278页

作者： Ying lu Se Wang Yifan Shen School of Environmental Science and Engineering Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologyJiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution ControlNanjing University of Information Science and TechnologyNanjing 210044China

The frequent detection of pharmaceutical compounds in the environment has led to a growing awareness,which may pose a major threat to the aquatic *** this study,photodegradation(direct and indirect photolysis)of two different dissociation states of fluoxetine(Flu)was investigated in water,mainly including the determination of photolytic transition states and products,and the mechanisms of indirect photodegradation with·OH,CO_(3)^(*-)and NO_(3)^(*).The main direct photolysis pathways are defluorination and C–C bond *** addition,the indirect photodegradation of Flu in water is mainly through the reactions with·OH and NO_(3)^(*),and the photodegradation reaction with CO_(3)^(*-)is relatively difficult to occur in the water *** results provide a theoretical basis for understanding the phototransformation process of Flu in the water environment and assessing its potential risk.

关键词： Fluoxetine Photochemical mechanism Direct photolysis Free radical reaction DFT

Active flutter suppression of nonlinear fin-actuator system via inverse system and immersion and invariance method

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Chinese Journal of Aeronautics 2024年第4期37卷 343-362页

作者： Jin lu Zhigang WU Chao YANG Chinese Aeronautical Establishment Beijing 100029China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

Structural nonlinearities such as freeplay will affect the stability and even flight safety of the fin-actuator *** is a lack of a practical method for designing Active Flutter Suppression (AFS) control laws for nonlinear fin-actuator systems.A design method for the AFS controller of the nonlinear all-movable fin-electromechanical actuator system is established by combining the inverse system and the Immersion and Invariance (I&I) ***,the composite control law combining the inverse system principle and internal model control is used to offset the nonlinearity and dynamics of the actuator,so that its driving torque can follow the ideal ***,the ideal torque of the actuator is designed employing the I&I *** unfavorable oscillation of the fin is suppressed by making the output torque of the actuator track the ideal *** simulation results reveal that the proposed AFS method can increase the flutter speed of the nonlinear finactuator system with freeplay,and a set of controller parameters is also applicable for wider freeplay within a certain *** power required for the actuator does not exceed the power that can be provided by the commonly used aviation *** method can also resist a certain level of noise and external disturbance.

关键词： Aeroelasticity Active flutter suppression Fin-actuator system Freeplay Inverse system Immersion and invariance

Comprehensive modeling strategy for thermomechanical tribological behavior analysis of railway vehicle disc brake system

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Friction 2024年第1期12卷 74-94页

作者： Jiabao YIN Chun lu Jiliang MO School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China Technology and Equipment of Rail Transit Operation and Maintenance Key Laboratory of Sichuan Province Chengdu 610031China

A comprehensive modeling strategy for studying the thermomechanical tribological behaviors is proposed in this *** wear degradation considering the influence of temperature(T)is predicted by Archard wear model with the help of the UMESHMOTION subroutine and arbitrary Lagrangian–Eulerian(ALE)remeshing *** the proposed method,the thermomechanical tribological behaviors of railway vehicle disc brake system composed of forged steel brake disc and Cu-based powder metallurgy(PM)friction block are studied *** effectiveness of the proposed methodology is validated by experimental test on a self-designed scaled brake test bench from the perspectives of interface temperature,wear degradation,friction noise and vibration,and contact status *** work can provide an effective way for the investigation of thermomechanical tribological behaviors in the engineering field.

关键词： tribological behaviors thermomechanical field wear prediction finite element simulation disc brake system railway vehicle

A flexible multiscale algorithm based on an improved smoothed particle hydrodynamics method for complex viscoelastic flows

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1387-1402页

作者： Jinlian REN Peirong lu Tao JIANG Jianfeng LIU Weigang lu College of Mathematical Science Yangzhou University College of Hydraulic Science and Engineering Yangzhou University

Viscoelastic flows play an important role in numerous engineering fields,and the multiscale algorithms for simulating viscoelastic flows have received significant attention in order to deepen our understanding of the nonlinear dynamic behaviors of viscoelastic fluids. However, traditional grid-based multiscale methods are confined to simple viscoelastic flows with short relaxation time, and there is a lack of uniform multiscale scheme available for coupling different solvers in the simulations of viscoelastic fluids. In this paper, a universal multiscale method coupling an improved smoothed particle hydrodynamics(SPH) and multiscale universal interface(MUI) library is presented for viscoelastic flows. The proposed multiscale method builds on an improved SPH method and leverages the MUI library to facilitate the exchange of information among different solvers in the overlapping domain. We test the capability and flexibility of the presented multiscale method to deal with complex viscoelastic flows by solving different multiscale problems of viscoelastic flows. In the first example, the simulation of a viscoelastic Poiseuille flow is carried out by two coupled improved SPH methods with different spatial resolutions. The effects of exchanging different physical quantities on the numerical results in both the upper and lower domains are also investigated as well as the absolute errors in the overlapping domain. In the second example, the complex Wannier flow with different Weissenberg numbers is further simulated by two improved SPH methods and coupling the improved SPH method and the dissipative particle dynamics(DPD) method. The numerical results show that the physical quantities for viscoelastic flows obtained by the presented multiscale method are in consistence with those obtained by a single solver in the overlapping domain. Moreover, transferring different physical quantities has an important effect on the numerical results.

关键词： 35Q30 76A10 76M28 complex viscoelastic flow dissipative particle dynamics (DPD) improved smoothed particle hydrodynamics (SPH) multiscale method multiscale universal interface (MUI) O373

Coupling and coordinated evolution characteristics of regional economy-energy-carbon emission multiple systems:A case study of main China's Basin

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Journal of Environmental Sciences 2024年第6期140卷 204-218页

作者： lu Chen Xin Li Jingyi Zhao Xinyu Kang lu Liu Minxi Wang Wu Chen College of Management Science Chengdu University of TechnologyChengdu 610051China SDU Life Cycle Engineering Department of Green TechnologyUniversity of Southern Denmark5230 OdenseDenmark

Comprehensive analysis of the Economy-Energy-Carbon Emission(EECE)system is beneficial for promoting sustainable social *** study analyzes the system development of major watersheds in China from 2010 to *** research fully considers the system’s internal and external inputs and outputs and proposes an evaluation index system for regional EECE coupling and coordinated ***,using the difference in system weight allocation to improve the coupling and coordination model,the study explores the dynamic system’s coupling and *** results show that(1)The development of the system structure is relatively stable,but the overall development status is not ideal;(2)The downstream of China’s main river basins has obvious economic advantages,while the energy system fluctuates *** efficiency of the carbon emission system will decrease in areas with rapid economic *** coupling and coordination level of the EECE system is better in the Yangtze River Basin than in the Yellow River Basin;(3)From the perspective of dynamic coordinated development,the main river basins have been divided into two states since 2012,but it is relatively stable *** dynamic coordination is often at a disadvantage in regions with rapid economic and energy development;(4)The coupling coordination degree of the two river basins has significant positive spatial *** provinces’significant spatial clustering characteristics of the coupling coordination degree are High-High ***-Low type provinces are mainly concentrated *** research process has certain reference significance for the collaborative governance of complex regional systems.

关键词： System structure Efficiency measure Coupling mechanism Dynamic coordination

Expression of cyclin-dependent kinase 9 is positively correlated with the autophagy level in colon cancer

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World Journal of Gastrointestinal Oncology 2024年第2期16卷 314-330页

作者： Lei Zheng Jia lu Da-lu Kong Department of Colorectal Cancer Surgery National Clinical Research Center for CancerKey Laboratory of Cancer Immunology and Biotherapy of TianjinTianjin Key Laboratory of Digestive CancerKey Laboratory of Cancer Prevention and Therapy of TianjinTianjin’s Clinical Research Center for CancerTianjin Medical University Cancer Institute and HospitalTianjin 300060China Department of Infection Management National Clinical Research Center for CancerKey Laboratory of Cancer Immunology and Biotherapy of TianjinTianjin Key Laboratory of Digestive CancerKey Laboratory of Cancer Prevention and Therapy of TianjinTianjin’s Clinical Research Center for CancerTianjin Medical University Cancer Institute and HospitalTianjin 300060China

BACKGROUND Cyclin-dependent kinase 9(CDK9)expression and autophagy in colorectal cancer(CRC)tissues has not been widely ***9,a key regulator of transcription,may influence the occurrence and progression of *** expression of auto-phagy-related genes BECN1 and drug resistance factor ABCG2 may also play a role in *** normal physiological conditions,autophagy can inhibit tumorigenesis,but once a tumor forms,autophagy may promote tumor ***,understanding the relationship between autophagy and cancer,partic-ularly how autophagy promotes tumor growth after its formation,is a key motivation for this *** To investigate the relationship between CDK9 expression and autophagy in CRC,assess differences in autophagy between left and right colon cancer,and analyze the associations of autophagy-related genes with clinical features and *** We collected tumor tissues and paracarcinoma tissues from colon cancer patients with liver metastasis to observe the level of autophagy in tissues with high levels of CDK9 and low levels of *** also collected primary tissue from left and right colon cancer patients with liver metastasis to compare the autophagy levels and the expression of BECN1 and ABCG2 in the tumor and paracarcinoma *** The incidence of autophagy and the expression of BECN1 and ABCG2 were different in left and right colon cancer,and autophagy might be involved in the occurrence of chemotherapy *** analysis of the rela-tionship between the expression of autophagy-related genes CDK9,ABCG2,and BECN1 and the clinical features and prognosis of colorectal cancer showed that the high expression of CDK9 indicated a poor prognosis in colorectal *** This study laid the foundation for further research on the combination of CDK9 inhibitors and autophagy inhibitors in the treatment of patients with CRC.

关键词： Autophagy Tumorigenesis Tumor tissue Paracarcinoma tissue Expression Left/right colon cancer

Progress of vegetation modelling and future research prospects

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Science China Earth Sciences 2024年第09期67卷 2718-2738页

作者： Siqi LI Xu ZHANG Zhengyao lu Jian NI Jianhua lu State Key Laboratory of Tibetan Plateau Earth System Resources and Environment (TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of Sciences College of Resources and Environment University of Chinese Academy of Sciences British Antarctic Survey Department of Physical Geography and Ecosystem Science Lund University College of Life Sciences Zhejiang Normal University School of Atmospheric Sciences Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)

Terrestrial vegetation is a crucial component of the Earth system, and its changes not only represent one of the most distinct aspects of climate change but also exert significant feedback within the climate system by exchanging energy, moisture,and carbon dioxide. To quantitatively and mechanistically study climate-vegetation feedback, numerical vegetation models have been developed on the theory of ecophysiological constraints on plant functional types. The models eventually can simulate vegetation distribution and succession across different spatial and temporal scales, and associated terrestrial carbon cycle processes by categorizing vegetation into biomes according different plant functional types and their associated environmental factors. Here we review the developing history of vegetation models and provide recent advances and future directions. Before 21st century, static vegetation models, as developed statistical models, can only simulate equilibrated characteristics of vegetation distribution. In last several decades, Dynamic Global Vegetation Models(DGVMs) have been developed to simulate instantaneous responses of vegetation to climate change and associated dynamics, and can be coupled with Earth system models to investigate interactions among atmosphere, ocean, and land. DGVMs are also widely applied to investigate the dynamics accounting for changes in the geographic distribution patterns of land surface vegetation at different spatial and temporal scales and to assess the impacts of terrestrial carbon and water fluxes and land use changes. We suggest that future vegetation modeling could integrate with machine learning, and explore vegetation transient response and feedback as well as impacts of process hierarchies and human activities on climate and ecosystem.

关键词： DGVMs Ecosystems Plant functional traits Plant functional types Vegetation models

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Fabrication of corrosion inhibiting microcapsules functional coating and their high-efficiency corrosion resistance

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Rare Metals 2024年第2期43卷 842-848页

作者： Hao-Ran Yun lu lu Xue-Long Hao Xing-Xiang Zhang School of Material Science and Engineering Tiangong UniversityTianjin300387China National Center of Analysis and Testing for Nonferrous Metals and Electronic Materials General Research Institute for Nonferrous MetalsBeijing100088China Guobiao(Beijing)Testing&Certification Co. Ltd.Beijing101407China

Benzotriazole(BTA)was loaded into calcium carbonate microsphere shell by self-assembly method and a new type of high-efficiency corrosion inhibiting microcapsules(CIMs)were fabricated,which were added and dispersed into epoxy resin coating to obtain a new corrosion resistance functional *** corrosion inhibition effect of benzotriazole on aluminum alloy matrix was verified by polarization curve *** effectiveness of the CIMs and their loading capacity on inhibitor were evaluated by scanning electron microscope,laser confocal Raman spectroscopy together with thermogravimetric analysis.

关键词： corrosion coating resistance