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Effect of Low-temperature Imidization on Properties and Aggregation Structures of Polyimide Films with Different Rigidity

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Chinese Journal of Polymer Science 2024年第8期42卷 1134-1146页

作者： Yan Jia Lei Zhai song mo Yi Liu Li-Xin Liu Xin-yu Du Min-Hui He Lin Fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

The traditional high-temperature preparation process of polyimide can cause many problems and limits the wider application in extreme *** important challenge to be solved urgently is the reduction of imidization *** this work,twelve kinds of polyimide films with different chain rigidity were prepared at low temperature of 200℃,in the absence or presence of imidazole used as the *** molecular rigidity and free volume were theoretically calculated,and relationship between structure and properties were systematically *** results show that imidization reaction under low temperatures is significantly affected by the rigidity of molecula r *** rigid structure of polyimide is not conducive to the low-temperature imidization,but this adverse effect can be eliminated by adding catalyst,resulting the notably increased imidization *** optical and thermal properties can be improved to a certain extent for the chemically catalyzed system,resulting in relatively higher heat resistance and thermal *** the mechanical performance could be determined by com plicating factors,greatly different from polyimide films prepa red by high temperature *** investigate aggregation structures of film s,the effect of chain rigidity and catalyst on the stacking or orientation of molecular chains was further *** wo rk can contribute to the understanding of chemically catalyzed imidization that is rarely reported in the existing research,and will provide guidance for the low-temperature preparation of high-performance polyimides.

关键词： Polyimide Imidization Catalyst Structure and properties Aggregation structures

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A comprehensive review on microchannel heat sinks for electronics cooling

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International Journal of Extreme Manufacturing 2024年第2期6卷 133-162页

作者： Zhi-Qiang yu mo-Tong Li Bing-Yang Cao Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

The heat generation of electronic devices is increasing dramatically,which causes a serious bottleneck in the thermal management of electronics,and overheating will result in performance deterioration and even device *** the development of micro-machining technologies,the microchannel heat sink(MCHS)has become one of the best ways to remove the considerable amount of heat generated by high-power *** has the advantages of large specific surface area,small size,coolant saving and high heat transfer *** paper comprehensively takes an overview of the research progress in MCHSs and generalizes the hotspots and bottlenecks of this *** heat transfer mechanisms and performances of different channel structures,coolants,channel materials and some other influencing factors are ***,this paper classifies the heat transfer enhancement technology and reviews the related studies on both the single-phase and phase-change flow and heat *** comprehensive review is expected to provide a theoretical reference and technical guidance for further research and application of MCHSs in the future.

关键词： microchannel heat sink thermal management of electronics microscale heat transfer heat transfer enhancement

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Discourse analysis of knowledge-based live streaming:a case study of East Buy streamer Dong yuhui

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Language and Semiotic Studies 2024年第2期10卷 222-244页

作者： Yehui song Junhua mo Korean Department Soochow UniversitySuzhou215006China English Department Soochow UniversitySuzhouChina

Live streaming e-commerce is not only an important part of China’s digital economy but also the preferred way of purchase for many Chinese,especially the *** 2022,a new model initiated by East Buy has emerged,quickly becoming known as knowledge-based live *** most famous streamer from this novel type of live streaming is Dong yuhui,a former English teacher of the New Oriental *** a top Internet influencer with millions of followers,Dong yuhui has become a conspicuous social sign of the rising China that is undergoing fast technological,economic,and cultural *** study thus takes Dong yuhui as an example to examine the typical discourses of the knowledge-based live *** a triangulation of case study,discourse analysis,and sentiment analysis,it finds that Dong yuhui mainly employs the strategies of disseminating encyclopedic knowledge,telling intriguing stories,and using poetic language in his live streaming *** unique discourse has the main function of fulfilling customers’intellectual,emotional,and psychological *** such,it is warmly received by customers,whose comments are centered on the talents of the streamer rather than the attributes of the commodity.

关键词： knowledge-based live streaming Dong yuhui typical discourses major strategies main functions customer comments

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Trial application of the envelope method to the potential ambiguity problem

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Nuclear Science and Techniques 2024年第1期35卷 73-80页

作者： Li-yuan Hu yu-Shou song Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering UniversityHarbin 150001China College of Nuclear Science and Technology Harbin Engineering UniversityHarbin 150001China Key Laboratory of Nuclear Safety and Advanced Nuclear Energy Technology Ministry of Industry and Information TechnologyHarbin 150001China

The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering *** a specific collid-ing system,ambiguous potential families can lead to different behaviors in the nearside and farside scattering *** contrast,the envelope method can decompose the experimental data into two components with negative and positive deflection angles,***,a question arises as to whether the comparison between the calculated nearside(or farside)component and the derived positive-deflection-angle(or negative-deflection-angle)component can help analyze the potential ambiguity *** this study,we conducted a trial application of the envelope method to the potential ambiguity *** envelope method was improved by including uncertainties in the experimental *** colliding systems of 16O+28Si at 215.2 MeV and 12C+12C at 1016 MeV were considered in the *** each colliding system,the angular distribution experimental data were described nearly equally well by two potential sets,one of which is“surface transpar-ent”and the other is *** calculated angular distributions were decomposed into nearside and farside scattering *** the improved envelope method,the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components,which were then compared with the calculated nearside and farside *** capability of the envelope method to analyze the potential ambiguities was also discussed.

关键词： Elastic scattering Optical potential ambiguities Envelope method Nearside/farside decomposition

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Prediction and validation of diffusive uptake rates for indoor volatile organic compounds in axial passive samplers

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Energy and Built Environment 2024年第1期5卷 24-31页

作者： Yan Wang Tao yu Jinhan mo Department of Building Science Tsinghua UniversityBeijing 100084China Beijing Key Laboratory of Indoor Air Quality Evaluation and Control Beijing 100084China Wuhan Second Ship Design and Research Institute Wuhan 430205China School of Energy and Power Engineering Beihang UniversityBeijing 100191China Key Laboratory of Eco Planning&Green Building Ministry of Education(Tsinghua University)Beijing 100084China

The diffusive uptake rate is essential for using passive samplers to measure indoor volatile organic compounds(VOCs).The traditional theoretical model of passive samplers requires available regression formulas of uptake rates and physicochemical properties of adsorbents to predict the uptake ***,it is difficult to obtain the uptake rates of different VOCs under different sampling periods,and it is also difficult to obtain the physical parameters of adsorbents accurately and *** study provides a reliable numerical prediction method of diffusive uptake rates of *** modeling was based on the standard automated thermal desorption(ATD)tubes packed with Tenax TA and the mass transfer process during *** experimental determinations of toluene uptake rate are carried out to verify the prediction *** uptake rates of typical indoor VOCs are obtained from the literature to calibrate the key apparent parameters in the model by statistical regression *** predicted model can provide the VOC diffusive uptake rates under different sampling duration with an average deviation of less than 5%.This study can provide the basis for fast and accurate prediction of diffusive uptake rates for various VOC pollutants in built environments.

关键词： Indoor air quality Diffusive uptake rate Prediction model Sampling Adsorption

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Type I interferon pathway in pediatric systemic lupus erythematosus

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World Journal of Pediatrics 2024年第7期20卷 653-668页

作者： yu Zhou Hong‑Mei song Department of Pediatrics Peking Union Medical College HospitalChinese Academy of Medical SciencesBeijingChina State Key Laboratory of Complex Severe and Rare Diseases Peking Union Medical College HospitalBeijingChina

Background The role of type I interferon(IFN-I)signaling in systemic lupus erythematosus(SLE)has been well ***,unanswered questions remain regarding the applicability of these findings to pediatric-onset *** aim of this review is to provide an overview of the novel discoveries on IFN-I signaling in pediatric-onset *** sources A literature search was conducted in the PubMed database using the following keywords:“pediatric systemic lupus erythematosus”and“type I interferon”.Results IFN-I signaling is increased in pediatric SLE,largely due to the presence of plasmacytoid dendritic cells and pathways such as cyclic GMP-AMP synthase–stimulator of interferon genes–TANK-binding kinase 1 and Toll-like receptor(TLR)4/*** extracellular traps and oxidative DNA damage further stimulate IFN-I *** variants in IFN-I-related genes,such as IFN-regulatory factor 5 and tyrosine kinase 2,are linked to SLE susceptibility in pediatric *** addition,type I interferonopathies,characterized by sustained IFN-I activation,can mimic SLE symptoms and are thus important to *** on interferonopathies also contribute to exploring the pathogenesis of *** IFN-I activation is crucial for SLE diagnosis and *** IFNstimulated gene expression and serum IFN-α2 levels are common *** cytometry markers such as CD169 and galectin-9 are promising ***-IFN therapies,such as sifalimumab and anifrolumab,show promise in adult patients with SLE,but their efficacy in pediatric patients requires further *** kinase inhibitors are another treatment option for severe pediatric SLE *** This review presents an overview of the IFN-I pathway in pediatric *** the intricate relationship between IFN-I and pediatric SLE may help to identify potential diagnostic markers and targeted therapies,paving the way for improved patient care and outcomes.

关键词： Interferonopathies Pediatric systemic lupus erythematosus Type I interferon

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Unknown system dynamics estimator-based impedance control for lower limb exoskeleton with enhanced performance

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Control Theory and Technology 2024年第1期22卷 56-68页

作者： Wenhao Zhang Peng song Mingying Wu Qiang Li Xinmin mo Pingxin Ji Northwest Institute of Mechanical and Electrical Engineering Xianyang712099ShaanxiChina Xi’an Exo-Smart Dynamics Technology Ltd. Xi’an712046ShaanxiChina Department of Mechanical and Engineering Beijing Institute of TechnologyBeijing100081China

In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation, i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identification in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced interaction flexibility and robustness.

关键词： Trajectory tracking Invariant manifold Funnel control Impedance control Lower limb exoskeleton

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Sulfated Cyclocarya paliurus polysaccharides exert immunomodulatory potential on macrophages via Toll-like receptor 4 mediated MAPK/NF-κB signaling pathways

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Food Science and Human Wellness 2024年第1期13卷 115-123页

作者： yue yu Haibin Zhu Mingyue Shen Qiang yu Yi Chen Shiru mo Jianhua Xie State Key Laboratory of Food Science and Technology Nanchang UniversityNanchang 330047China International Institute of Food Innovation Nanchang UniversityNanchang 330200China

The biological activity of plant polysaccharides can be enhanced by sulfated *** this study,the immunomodulatory effect of sulfated Cyclocarya paliurus polysaccharides(SCP3)on macrophages RAW264.7 and its potential molecular mechanism were *** showed that SCP3 at 25-100μg/m L increased viability and improved phagocytosis of RAW264.7 ***,SCP3 could activate mitogen-activated protein kinase(MAPK)and nuclear factor kappa B(NF-κB)signaling pathways,which increased the phosphorylation of Erk1/2,JNK,p38 and NF-κB p65,promoting secretion of cytokines tumor necrosis factorα(TNF-α),interleukin 6(IL-6)and nitric oxide(NO)as well as the production of reactive oxygen species(ROS).In addition,Toll-like receptor 4(TLR4)receptor inhibitors were able to block the production of NO and TNF-αby SCP3-stimulated *** on Western blot analysis and validation using specific inhibitors against MAPK and NF-κB signaling pathways,the results demonstrated that SCP3 induced macrophages activation and enhanced TNF-αand NO production via TLR4-mediated MAPK and NF-κB *** summary,SCP3 has significant immunomodulatory *** underlying molecular mechanism was that SCP3 activates macrophages via TLR4 receptors to promote ROS production,which in turn activates the downstream MAPK/NF-κB signaling pathway and then increases the secretion levels of cytokines and NO.

关键词： Cyclocarya paliurus Sulfated polysaccharides Macrophages Immunomodulatory Mechanism

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Precise immobilization of metal single atoms into a porphyrinic metal-organic framework for an efficient alkene hydrosilylation

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Nano Research 2024年第7期17卷 5914-5921页

作者： Chun-Ying Chen Qi-Jie mo Fu-Zhen Li Hai-Li song Li Zhang moE Laboratory of Bioinorganic and Synthetic Chemistry Lehn Institute of Functional MaterialsSchool of ChemistrySun Yat-Sen UniversityGuangzhou 510006China

Alkene hydrosilylation is one of the most concise and atom-economical methods to synthesize organosilicon ***,we reported the precise immobilization of metal single atoms(M-SAs;M=Ru,Rh,Ir,Pd,Pt,and Au)into a porphyrinic metalorganic framework(moF)of PCN-222(PCN=porous coordination network),and then applied the resultant moF composites of M-SAs@PCN-222 to alkene *** solvent-free conditions,Pt-SAs@PCN-222 displayed an especially high catalytic efficiency with the turnover frequency up to 119 s−1 and the maximum turnover number of 906,250 at room *** and theoretical studies revealed that there existed strong interactions between Pt-SAs@PCN-222 and the substrates,which helped to condense the substrates in the cavities of the porous *** density functional theory calculations and molecular dynamics simulations disclosed that PCN-222 could transfer electrons to Pt-SAs to enhance the silane oxidative addition and drive the reaction to proceed smoothly via Chalk–Harrod pathway.

关键词： alkene hydrosilylation single atom catalysts metal-organic frameworks precision chemistry synergistic catalysis

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mobile Crowdsourcing Task Allocation Based on Dynamic Self-Attention GANs

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Computers, Materials & Continua 2024年第4期79卷 607-622页

作者： Kai Wei song yu Qingxian Pan School of Computer and Control Engineering Yantai UniversityYantai264005China School of Computer and Information Science Southwest UniversityChongqing400715China

Crowdsourcing technology is widely recognized for its effectiveness in task scheduling and resource *** traditional methods for task allocation can help reduce costs and improve efficiency,they may encounter challenges when dealing with abnormal data flow nodes,leading to decreased allocation accuracy and *** address these issues,this study proposes a novel two-part invalid detection task allocation *** the first step,an anomaly detection model is developed using a dynamic self-attentive GAN to identify anomalous *** to the baseline method,the model achieves an approximately 4%increase in the F1 value on the public *** the second step of the framework,task allocation modeling is performed using a twopart graph matching *** phase introduces a P-queue KM algorithm that implements a more efficient optimization *** allocation efficiency is improved by approximately 23.83%compared to the baseline *** results confirm the effectiveness of the proposed framework in detecting abnormal data nodes,enhancing allocation precision,and achieving efficient allocation.

关键词： mobile crowdsourcing task allocation anomaly detection GAN attention mechanisms

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