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Strong and tough chitin hydrogel constructed by dehydration and rehydration strategy

Nano Research 2024年第9期17卷 8192-8199页

作者： Rui-Rui Liu Li-Bo mao Shu-Hong Yu Division of Nanomaterials and Chemistry Hefei National Research Center for Physical Sciences at the MicroscaleDepartment of ChemistryInstitute of Biomimetic Materials and ChemistryAnhui Engineering Laboratory of Biomimetic MaterialsUniversity of Science and Technology of ChinaHefei 230026China Institute of Innovative Materials Department of Materials Science and EngineeringDepartment of ChemistrySouthern University of Science and TechnologyShenzhen 518055China

As a renewable,biocompatible,biodegradable soft material,chitin hydrogels have better advantages in stability,antibacterial activity,antifouling,cost,immunogenicity,and so on than most polymer ***,compared with other widely used polymer hydrogels with high strength and toughness,the practical applications of chitin-based hydrogels have been limited by their weak mechanical properties,such as cartilage repair and meniscus ***,we present the design and fabrication of chitin hydrogels with excellent mechanical strength and toughness by a dehydration and rehydration *** sequential dehydration and rehydration processes,the crystalline domains in the chitin hydrogels can be properly *** optimized crystallinity,the elastic modulus of the chitin hydrogels exceeds all previously reported values,and the fracture toughness is even comparable to some synthetic polymer hydrogels,while maintaining a high-water-content of about 80 wt.%.At the same water content,the mechanical properties of the chitin hydrogels are positively correlated with the hydrogel crystallinity,which proves that the change of mechanical properties of hydrogels is not simply dependent on weight *** hydrogels can be further strengthened by incorporating other biopolymers that are intrinsically weak,which makes the hydrogels promising for applications in fields such as cartilage repair and meniscus ***,the hydrogels enable loading and release of water-soluble and poorly water-soluble *** highly extendable strengthening and toughening strategy of chitin and chitin-based biopolymer hydrogels paves the way for their widely applications.

关键词： chitin hydrogel crystallinity rehydration chemical transformation strong and tough

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The posterior selection method for hyperparameters in regularized least squares method

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Control Theory and Technology 2024年第2期22卷 184-194页

作者： Yanxin Zhang Jing Chen Yawen mao Quanmin Zhu School of Science Jiangnan UniversityWuxi214122JiangsuChina The Science and Technology on Near-Surface Detection Laboratory Wuxi214122JiangsuChina Department of Engineering Design and Mathematics University of the West of EnglandBristolBS161QYUK

The selection of hyperparameters in regularized least squares plays an important role in large-scale system identification. The traditional methods for selecting hyperparameters are based on experience or marginal likelihood maximization method, which are inaccurate or computationally expensive. In this paper, two posterior methods are proposed to select hyperparameters based on different prior knowledge (constraints), which can obtain the optimal hyperparameters using the optimization theory. Moreover, we also give the theoretical optimal constraints, and verify its effectiveness. Numerical simulation shows that the hyperparameters and parameter vector estimate obtained by the proposed methods are the optimal ones.

关键词： Regularization method Hyperparameter System identification Least squares algorithm

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Investigation of control effects of end-wall selfadaptive jet on three-dimensional corner separation of a highly loaded compressor cascade

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Chinese Journal of Aeronautics 2024年第6期37卷 109-126页

作者： Hejian WANG Bo LIU Xiaochen mao Botao ZHANG Zonghao YANG School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China The National Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi’an 710129China Taihang Laboratory Chengdu 610000China

To overcome the limitations posed by three-dimensional corner separation,this paper proposes a novel flow control technology known as passive End-Wall(EW)self-adaptive *** single EW slotted schemes(EWS1 and EWS2),alongside a combined(COM)scheme featuring double EW slots,were *** results reveal that the EW slot,driven by pressure differentials between the pressure and suction sides,can generate an adaptive jet with escalating velocity as the operational load *** high-speed jet effectively re-excites the local low-energy fluid,thereby mitigating the corner ***,the EWS1 slot,positioned near the blade leading edge,exhibits relatively low jet velocities at negative incidence angles,causing jet separation and exacerbating the corner ***,the EWS2 slot is close to the blade trailing edge,resulting in massive low-energy fluid accumulating and separating before the slot outlet at positive incidence *** contrast,the COM scheme emerges as the most effective solution for comprehensive corner separation *** can significantly reduce the total pressure loss and improve the static pressure coefficient for the ORI blade at 0°-4° incidence angles,while causing minimal negative impact on the aerodynamic performance at negative incidence ***,the corner stall is delayed,and the available incidence angle range is broadened from -10°--2°to -10°-4°.This holds substantial promise for advancing the aerodynamic performance,operational stability,and load capacity of future highly loaded compressors.

关键词： Three-dimensional corner separation End-wall adaptive jet Total pressure loss Highly loaded compressor cascade Compressors

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Circulation Background and Genesis Mechanism of a Cold Vortex over the Tibetan Plateau during Late April 2018

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Advances in Atmospheric Sciences 2024年第6期41卷 1201-1216页

作者： Duming GAO Jiangyu mao Guoxiong WU Yimin LIU State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province Institute of Plateau MeteorologyChina Meteorological AdministrationChengdu 610072China Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China

A cold vortex occurred over the northeastern Tibetan Plateau(TP)on 27 April 2018 and subsequently brought excessive rainfall to the spring farming area in southern China when moving *** study investigates the genesis mechanism of the cold TP vortex(TPV)by diagnosing reanalysis data and conducting numerical *** demonstrate that the cold TPV was generated in a highly baroclinic environment with significant contributions of positive potential vorticity(PV)forcing from the tropopause and diurnal thermodynamic impact from the *** a positive PV anomaly in the lower stratosphere moved towards the TP,the PV forcing at the tropopause pushed the tropospheric isentropic surfaces upward,forming isentropic-isplacement ascent and reducing static stability over the *** descent of the tropopause over the TP also produced a tropopause folding over the northeastern TP associated with a narrow high-PV column intruding downwards over the TPV genesis site,resulting in ascending air in the free ***,in conjunction with the descending air in the valley area during the night,produced air stretching just at the TPV genesis *** the surface cooling at night increased the surface static stability,the aforementioned vertical air-stretching thus converted the produced static stability to vertical ***,the cold TPV was generated over the valley at night.

关键词： tropopause PV forcing air column stretching static stability vertical vorticity

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Shock-induced chemical reaction characteristics of PTFE-Al-Bi_(2)O_(3)reactive materials

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Defence Technology（防务技术） 2024年第6期36卷 1-12页

作者： Chunlan Jiang Rong Hu Jingbo Zhang Zaicheng Wang Liang mao State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

A ternary system of PTFE/Al/Bi_(2)O_(3)is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive *** effects of Bi_(2)O_(3)in the PTFE/Al/Bi_(2)O_(3)on both mechanical properties and the energy release were investigated through various tests such as thermogravimetry-differential scanning calorimetry,adiabatic oxygen bomb test and split Hopkinson pressure bar *** microstructure observed through scanning electron microscope and Xray diffraction results are used to analyze the ignition and reaction mechanism of PTFE/Al/Bi_(2)O_(3).The results indicate that the PTFE/Al/Bi_(2)O_(3)are capable of triggering the exothermic reaction of molten PTFE/Bi_(2)O_(3)and Al/Bi_(2)O_(3)over the PTFE/Al reactive materials,thereby promoting *** excessive aluminum in the ternary system is beneficial for increasing energy *** ignition of shock-induced chemical reactions in PTFE/Al/Bi_(2)O_(3)is closely related to the material *** dominant mechanism for hot-spot generation under Split Hopkinson Pressure Bar test is the frictional temperature rise at the microcrack after failure.

关键词： PTFE/Al/Bi_(2)O_(3) Shock-induced chemical reaction Energy release

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THE TRUNCATED EM METHOD FOR JUMP-DIFFUSION SDDES WITH SUPER-LINEARLY GROWING DIFFUSION AND JUMP COEFFICIENTS

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Journal of Computational Mathematics 2024年第1期42卷 178-216页

作者： Shounian Deng Chen Fei Weiyin Fei Xuerong mao Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment Ministry of Educationand School of Mathematics-Physics and FinanceAnhui Polytechnic UniversityWuhu 241000China Business School University of Shanghai for Science and TechnologyShanghai 200093China Department of Mathematics and Statistics University of StrathclydeGlasgow G11XHUK

This work is concerned with the convergence and stability of the truncated EulerMaruyama(EM)method for super-linear stochastic differential delay equations(SDDEs)with time-variable delay and Poisson *** constructing appropriate truncated functions to control the super-linear growth of the original coefficients,we present two types of the truncated EM method for such jump-diffusion SDDEs with time-variable delay,which is proposed to be approximated by the value taken at the nearest grid points on the left of the delayed *** first type is proved to have a strong convergence order which is arbitrarily close to 1/2 in mean-square sense,under the Khasminskii-type,global monotonicity with U function and polynomial growth *** second type is convergent in q-th(q<2)moment under the local Lipschitz plus generalized Khasminskii-type *** addition,we show that the partially truncated EM method preserves the mean-square and H∞stabilities of the true ***,we carry out some numerical experiments to support the theoretical results.

关键词： SDDEs Truncated EM method Time-variable delay Poisson jumps

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Dirac method for nonlinear and non-homogenous boundary value problems of plates

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 15-38页

作者： Xiaoye mao Jiabin WU Junning ZHANG Hu DING Liqun CHEN Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Shanghai Institute of Aircraft Mechanics and Control Shanghai 200092China

The boundary value problem plays a crucial role in the analytical investigation of continuum dynamics. In this paper, an analytical method based on the Dirac operator to solve the nonlinear and non-homogeneous boundary value problem of rectangular plates is proposed. The key concept behind this method is to transform the nonlinear or non-homogeneous part on the boundary into a lateral force within the governing function by the Dirac operator, which linearizes and homogenizes the original boundary, allowing one to employ the modal superposition method for obtaining solutions to reconstructive governing equations. Once projected into the modal space, the harmonic balance method(HBM) is utilized to solve coupled ordinary differential equations(ODEs)of truncated systems with nonlinearity. To validate the convergence and accuracy of the proposed Dirac method, the results of typical examples, involving nonlinearly restricted boundaries, moment excitation, and displacement excitation, are compared with those of the differential quadrature element method(DQEM). The results demonstrate that when dealing with nonlinear boundaries, the Dirac method exhibits more excellent accuracy and convergence compared with the DQEM. However, when facing displacement excitation, there exist some discrepancies between the proposed approach and simulations;nevertheless, the proposed method still accurately predicts resonant frequencies while being uniquely capable of handling nonuniform displacement excitations. Overall, this methodology offers a convenient way for addressing nonlinear and non-homogenous plate boundaries.

关键词： rectangular plate Dirac operator nonlinear boundary time-dependent boundary boundary value problem

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A combined evaluation of the characteristics and antibiotic resistance induction potential of antibiotic wastewater during the treatment process

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Journal of Environmental Sciences 2024年第4期138卷 626-636页

作者： Sun Miao Yanyan Zhang Cong Men Yiou mao Jiane Zuo State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China School of Energy and Environmental Engineering Beijing Key Laboratory of Resource-Oriented Treatment of Industrial PollutantsUniversity of Science and Technology BeijingBeijing 100083China High School Affiliated to Renmin University of China Beijing 100080China Tsinghua Shenzhen International Graduate School Shenzhen 518055China

Antibiotic wastewater contains a variety of pollutant stressors that can induce and promote antibiotic resistance(AR)when released into the *** these substances are mostly in concentrations lower than those known to induce AR individually,it is possible that antibiotic wastewater discharge might still promote the AR transmission risk via additive or synergistic ***,the comprehensive effect of antibiotic wastewater on AR development has rarely been evaluated,and its treatment efficiency remains ***,samples were collected from different stages of a cephalosporin production wastewater treatment plant,and the potential AR induction effect of their chemical mixtures was explored through the exposure of the antibiotic-sensitive Escherichia coli K12 *** with raw cephalosporin production wastewater significantly promoted mutation rates(3.6×10^(3)-9.3×10^(3)-fold)and minimum inhibition concentrations(6.0-6.7-fold)of *** against ampicillin and *** may be attributed to the inhibition effect and oxidative stress of cephalosporin wastewater on *** AR induction effect of cephalosporin wastewater decreased after the coagulation sedimentation treatment and was completely removed after the full treatment process.A Pearson correlation analysis revealed that the reduction in the AR induction effect had a strong positive correlation with the removal of organics and biological *** indicates that the antibiotic wastewater treatment had a collaborative processing effect of conventional pollutants,toxicity,and the AR induction *** study illustrates the potential AR transmission risk of antibiotic wastewater and highlights the need for its adequate treatment.

关键词： Antibiotic wastewater treatment plant Antibiotic resistance Antibiotic resistance induction effect Correlation analysis Biological toxicity

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Synthesis and Characterization of Nonionic Waterborne Polyurethane and Application to Wool Fabric Finishing

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 497-505页

作者：殷映婷 FENG mao 姚金波牛家嵘 School of Textile Science and Engineering Tiangong UniversityTianjin 300387China

A nonionic waterborne polyurethane(WPU) was synthesized by the self-emulsification method using polyether diol(N220),isophorone diisocyanate(IPDI),trimethylolpropane poly(ethylene glycol monomethyl ether)(N120),1,4-butanediol(BDO) and trimethylolpropane(TMP) as the main *** effects of the NCO/OH ratio on the emulsion and film properties of NWPU were *** experimental results show that the NWPU prepared at an NCO/OH ratio of 1.1 has good emulsion stability and easy film formation,and the resultant film was elastic,soft,and *** sample was used for wool finishing and the application performance was *** the NWPU dosage reached 40 g·L^(-1),the fabric area felt shrinkage rate reduced from 8.97% to 4.75%,the pilling rating raised from grade 2-3 to grade 4,and the whiteness value only decreased by 3.87%.

关键词： waterborne polyurethane nonionic wool finishing anti-pilling anti-shrinking

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Recent advances in stretchable triboelectric nanogenerators for use in wearable bioelectronic devices

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Bio-Design and Manufacturing 2024年第4期7卷 566-590页

作者： Yaling Wang Pengcheng Zhu Yue Sun Pan Li Yanchao mao College of Science Henan Agricultural UniversityZhengzhou 450002China Key Laboratory of Materials Physics of Ministry of Education School of PhysicsZhengzhou UniversityZhengzhou 450001China

Wearable bioelectronic devices have the capacity for real-time human health monitoring,the provision of tailored services,and natural interaction with smart ***,these wearable bioelectronic devices rely on conventional rigid batteries that are frequently charged or replaced and are incompatible with the skin,leading to a discontinuity in complex therapeutic tasks related to human health monitoring and human-machine *** triboelectric nanogenerator(TENG)is a high-efficiency energy harvesting technology that converts mechanical into electrical energy,effectively powering wearable bioelectronic *** study comprehensively overviews recent advances in stretchable TENG for use in wearable bioelectronic *** working mechanism of stretchable TENG is initially explained.A comprehensive discussion presents the approaches for fabricating stretchable TENG,including the design of stretchable structures and the selection of stretchable ***,applications of wearable bioelectronic devices based on stretchable TENG in human health monitoring(body movements,pulse,and respiration)and human-machine interaction(touch panels,machine control,and virtual reality)are ***,the challenges and developmental trends regarding wearable bioelectronic devices based on stretchable TENG are elaborated.

关键词： Stretchable Triboelectric nanogenerators Structure Human health monitoring Human-machine interaction

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