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Microstructure and mechanical properties of 3D printed ceramics with different vinyl acetate contents

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Rare Metals 2021年第11期40卷 3241-3250页

作者： He Li Yong-Sheng Liu yan-song Liu Qing-Feng zeng Jing-Jing Liang Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China NPU-SAS Joint Research Center of Advanced Ceramics Northwestern Polytechnical UniversityXi’an 710072China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

Stereolithography(SL)-based three-dimensional(3D) printing technique is an efficient method for the fabrication of alumina *** alumina slurry is difficult to obtain due to the barrier between hydrophilic alumina and oleophilic *** not only requires that the ceramic slurry possessed low viscosity and uniformity,but also requires that the slurry could complete the photocuring *** this study,vinyl acetate was added in the ceramic slurry as a bridge to connect alumina and resin,and the effects of vinyl acetate content on the microstructure and mechanical properties of the alumina ceramics were systematically *** results showed that the alumina ceramics were composed of three types of particles which included large aggregates,individual particles,and long-columnshaped *** shrinkage,bulk density,and crystallite size of the ceramics increased with the increase in vinyl acetate *** open porosity decreased with the increase in vinyl acetate *** flexural strength of the ceramics first increased and subsequently decreased with the increase in vinyl acetate *** shrinkage in Z direction was much greater than that in X or Y *** on the above results,the optimum vinyl acetate content for alumina slurry was 10 wt%,which resulted in sintered ceramic with the shrinkage of 15.6% in X direction,13.5% in Ydirection,21.9% in Z direction,bulk density of 1.9 g·cm^(-3),open porosity of 50.1%,and flexural strength of 24.4 *** sintered ceramics satisfy the requirement of alumina ceramic cores.

关键词： Stereolithography Alumina ceramics Vinyl acetate Microstructure Mechanical properties

Induced pluripotent stem cell-related approaches to generate dopaminergic neurons for Parkinson's disease

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Neural Regeneration Research 2025年第11期20卷 3193-3206页

作者： Ling-Xiao Yi Hui Ren Woon Genevieve Saw Li zeng Eng King Tan Zhi Dong Zhou National Neuroscience Institute Singapore Nanyang Technology University Singapore Department of Neurology Singapore General HospitalSingapore Signature Research Program in Neuroscience and Behavioral Disorders Duke-NUS Medical SchoolSingapore

The progressive loss of dopaminergic neurons in affected patient brains is one of the pathological features of Parkinson's disease,the second most common human neurodegenerative *** the detailed pathogenesis accounting for dopaminergic neuron degeneration in Parkinson's disease is still unclear,the advancement of stem cell approaches has shown promise for Parkinson's disease research and *** induced pluripotent stem cells have been commonly used to generate dopaminergic neurons,which has provided valuable insights to improve our understanding of Parkinson's disease pathogenesis and contributed to anti-Parkinson's disease *** current review discusses the practical approaches and potential applications of induced pluripotent stem cell techniques for generating and differentiating dopaminergic neurons from induced pluripotent stem *** benefits of induced pluripotent stem cell-based research are *** dopaminergic neuron differentiation protocols from induced pluripotent stem cells are *** emerging three-dimension-based brain organoid models compared with conventional two-dimensional cell culture are ***,limitations,challenges,and future directions of induced pluripotent stem cell–based approaches are analyzed and proposed,which will be significant to the future application of induced pluripotent stem cell-related techniques for Parkinson's disease.

关键词： dopaminergic neurons induced pluripotent stem cells Parkinson's disease stem cell approaches

Abiotic transformation of chlorinated organics at the active surface of iron-bearing minerals in soils and sediments

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Science China(Technological Sciences) 2024年第10期67卷 2991-3008页

作者： LI XuXin yan Chen zeng YuXi LI WenBin PENG TianWei song Biao ZHOU ChengYun College of Environmental Science and Engineering Hunan UniversityChangsha 410082China Key Laboratory of Environmental Biology and Pollution Control(Hunan University) Ministry of EducationChangsha 410082China

Chlorinated organic compounds are emerging pollutants of widespread concern because of their toxicity,bioaccumulation,persistence,and lack of adequate regulatory *** abiotic transformation,facilitated by iron-bearing minerals,is critical to their natural dissipation in soils and ***,further exploration is needed to understand their underlying mechanisms and potential engineering applications under different redox *** paper reviews the abiotic transformation behaviors and mechanisms of chlorinated organics at the active surface of iron-bearing minerals under anoxic and oxic conditions and summarizes the strategies for enhancing the abiotic transformation efficiency of chlorinated *** abiotic transformation rate under oxic conditions can be a few orders of magnitude higher than that under anoxic *** anoxic conditions,chlorinated organics undergo reductive dechlorination through reductive elimination,hydrogenolysis,dehydrohalogenation,and nucleophilic substitution.A close relationship between the abiotic transformation of chlorinated organics and the production of hydroxyl radicals by iron-bearing minerals under oxic conditions was *** active iron-bearing minerals,carbonaceous materials,and biological synergy can facilitate abiotic dechlorination under anoxic ***,the regulation of redox conditions,the introduction of ligands,and the utilization of coexisting anions are proposed to enhance oxidative *** study is expected to improve the comprehension of the abiotic degradation of chlorinated organics mediated by iron-bearing minerals and provide the theoretical foundation for developing new approaches aimed at addressing chlorinated organic pollution.

关键词： chlorinated organic compounds iron-bearing minerals dechlorination degradation remediation

ASSET-LIABILITY MANAGEMENT UNDER BENCHMARK AND MEAN-VARIANCE CRITERIA IN A JUMP DIFFUSION MARKET

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Journal of Systems Science & Complexity 2011年第2期24卷 317-327页

作者： yan zeng Zhongfei LI School of Mathematics and Computational Science Sun Yat-sen University Guangzhou 510275 China. Lingnan College & Management School Sun Yat-sen University Guangzhou 510275 China.

This paper investigates continuous-time asset-liability management under benchmark and mean-variance criteria in a jump diffusion market. Specifically, the authors consider one risk-free asset, one risky asset and one liability, where the risky asset＇s price is governed by an exponential Levy process, the liability evolves according to a Levy process, and there exists a correlation between the risky asset and the liability. Two models are established. One is the benchmark model and the other is the mean-variance model. The benchmark model is solved by employing the stochastic dynamic programming and its results are extended to the mean-variance model by adopting the duality theory. Closed-form solutions of the two models are derived.

关键词： Asset-liability management benchmark and mean-variance models duality theory jumpdiffusion market Hamilton-Jacobi-Bellman equation.

Integrated dynamic shared protection algorithm for GMPLS networks

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Journal of Systems Engineering and Electronics 2008年第6期19卷 1264-1271页

作者： Wang yan zeng Jiazhi Coll. of Computer Science and Engineering Univ. of Electronic Science and Technology of China Chengdu 610054 P. R. China

The path protection approach is widely investigated as a survivability solution for GMPLS networks, which has the advantage of efficient capacity utilization. However, there is a problem of the path protection approach that searching a disjoint backup path for a primary path is often unsuccessful. In order to resolve this problem, an integrated dynamic shared protection （IDSP） algorithm is proposed. The main idea of the proposed algorithm is that the path protection approach is first used to establish a backup path for the primary path; if the establishment is unsuccessful, then the primary path is dynamically divided into segments whose hop count are not fixed but not more than the limitation calculated by the equations introduced. In this proposal, backup bandwidth sharing is allowed to improve the capacity utilization ratio, which makes the link cost function quite different from previous ones. Simulation experiments are presented to demonstrate the efficiency of the proposed method compared with previous methods. Numerical results show that IDSP can not only achieve low protection failure probability but can also gain a better tradeoff between the protection overbuild and the average recovery time.

关键词： generalized multi-protocol label switching protection hop count primary path backup path

NASTCNN: a spatio-temporal convolutional neural network with non-local attention mechanism for image-induced brain activity pattern recognition

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Optoelectronics Letters 2025年

作者： TAN Xiangxin SHAO Mingxiong zeng Ke GU Yue School of Computer Science and Engineering， Tianjin University of Technology Engineering Research Center of Learning-Based Intelligent System (Ministry of Education)， Tianjin University of Technology Krembil Research Institute， University Health Network

Deciphering the brain’s visual processing mechanisms has always been a hot topic. Using neural signal patterns to predict the corresponding external visual stimuli is crucial in understanding the interaction of real visual scenes. There are some challenges in the study of image-induced brain activity pattern recognition based on electroencephalogram (EEG)， e.g. how to fully utilize the effective features of EEG signals to improve the classification， and how the frequency and the length of EEG effect the model performance. We design an experimental paradigm that minimizes the interaction between visual stimuli， and propose a spatio-temporal convolutional neural network with non-local attention mechanism (NASTCNN) for image-induced brain activity pattern recognition. The framework utilizes non-local feature extraction operations to realize global information interaction between EEG signals over long distances and enhance the feature expression of some important information. Our model achieves the best performance on both MNIST-EEG and ImageNet-EEG datasets. The classification results are 24.00% and 50.10% respectively， higher than the random probability. We also analyze the effects of different EEG frequency bands and time subsequences of different lengths on the classification performance and which brain regions are activated over time. The results show that when full frequency band and entire length sequence are selected， the classification result is optimal. The occipital region is essential for processing visual tasks， and the temporal region and some frontal regions also play important role in the later stage of visual decoding. This research can help us better understand the visual processing mechanism of the brain.

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Microsatellite variation of Hainan Eld’s deer （Cervus eldi hainanus） in China: Implications for conservation

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Microsatellite variation of Hainan Eld’s deer （Cervus eldi...

Stress-corrosion behavior and characteristics of the friction stir welding of an AA2198-T34 alloy

中国动物学会兽类学分会第六届会员代表大会暨学术讨论会

作者： QIONG ZHANG,~(1) YA-JIE JI,~* ZHI-GAO zeng, yan-LING song, DE-XING ZHANG~* ( Division of Animal Ecology and Conservation Biology, ~*State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 25 Beisihuan-Xi Road, Beijing 100080, P. R. China, ~1Graduate School of the Chinese Academy of Sciences, Beijing 100039, P.R. China.)

＜正＞Many species of mammals have declined within the past two centuries due to human-caused disturbances such as habitat loss, habitat fragmentation and over hunting. Eld’s deer （Cervus eldi） were once distribute...

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International Journal of Minerals,Metallurgy and Materials 2020年第6期27卷 774-782页

作者： Quan-qing zeng song-sheng zeng Dong-yao Wang Research Institute of Light Alloy Central South UniversityChangsha 410083China Key Laboratory of the Ministry of Education of Nonferrous Metals Central South UniversityChangsha 410083China Technology Center Valin ArcelorMittal Automotive Steel Co.Ltd.Loudi 417009China

To better understand the stress-corrosion behavior of friction stir welding(FSW),the effects of the microstructure on the stress-corrosion behavior of the FSW in a 2198-T34 aluminum alloy were *** experimental results show that the low-angle grain boundary(LABs)of the stir zone(SZ)of FSW is significantly less than that of heated affected zone(HAZ),thermo-mechanically affected zone(TMAZ),and parent materials(PM),but the grain boundary precipitates(GBPs)T1(Al2CuLi)were less,which has a slight effect on the stress *** dislocation density in SZ was greater than that in other *** residual stress in SZ was+67 MPa,which is greater than that in the *** residual stress in the HAZ and PM is-8 MPa and-32 MPa,respectively,and both compressive *** corrosion potential in SZ is obviously less than that in other ***,micro-cracks were formed in the SZ at low strain rate,which indicates that the grain boundary characters and GBPs have no significant effect on the crack initiation in the stress-corrosion process of the ***,the residual tensile stress has significant effect on the crack initiation during the stress-corrosion process.

关键词： slow strain rate test residual stress grain boundary characteristic AA2198-T34 alloy friction stir welding

λ-Central BMO Estimates for Multilinear Commutators of Fractional Integrals

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Acta Mathematica Sinica,English Series 2010年第11期26卷 2093-2108页

作者： zeng yan SI School of Mathematical Science Beijing Normal University Beijing 100875 P. R. China

The author establishes λ-central BMO estimates for commutators of multilinear fractional integral operators on central Morrey spaces.

关键词： λ-central BMO space central Morrey space multilinear fractional operators