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Detached-eddy simulation of supersonic flow past a spike-tipped blunt nose

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Chinese Journal of Aeronautics 2018年第9期31卷 1815-1821页

作者： Yuan xue Liang WANG Song fu School of Aerospace Engineering Tsinghua University

Space vehicle in atmosphere travels mostly at supersonic speed and generates a very strong bow shockwave around its blunt nose. Oblique shock and conical separated flow zone generated by a forward disk-tip spike significantly reduce the drag by reducing the high pressure area on the blunt nose. This study employs improved delayed detached eddy simulation to investigate the characteristic flow structures around a spike-tipped blunt nose at Mach number of 3 and Reynolds number（based on the blunt-body diameter） of 2.72x10;. The calculated time-averaged quantities agree well with experimental data. Characteristic frequencies in different flow regions are extracted using fast Fourier transform. It is found that two distinct instability modes exist: oscillation mode and pulsation mode. The former is related to the foreshock/turbulence interaction with nondimensional frequency at around 0.004. The latter corresponds to the interaction between turbulence and shock structures around the blunt nose, with a typical coherent structure shedding frequency at 0.092.

关键词： Detached-eddy simulation Drag reduction Oscillation mode Pulsation mode Spike-tipped blunt vehicle Supersonic flow

Habitat influences on diversity of bacteria found on German cockroach in Beijing

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Journal of Environmental Sciences 2009年第2期21卷 249-254页

作者： fu xue YE Lefu GE Feng State Key Laboratory of lntegrated Management of Pest Insects and Rodents Institute of Zoology Chinese Academy of Sciences Beijing 100101 China Graduate University of Chinese Academy of Sciences Beijing 100080 China

Cockroaches are worldwide indoor pests carrying microorganisms of medical importance. German cockroaches （Blattella germanica） were sampled in five habitats （hospital, restaurant, office home, and market） in Beijing, and the bacteria were isolated from their external surface and alimentary tract and identified using a Biolog identification system. Cockroach densities significantly differed among habitats （market 〉 home 〉 office 〉 restaurant 〉 hospital）. However, no significant differences in bacterial abundance carried by individual German cockroaches （of either sex） were found among habitats. The bacterial abundance in the gut was significantly higher than that on the surface. There were no significant differences in bacterial species richness observed among habitats, sex, carrying position or their interaction. Cluster analysis showed that cockroach densities and bacterial abundance found in the market differed significantly from the other four habitats. The bacterial diversity was not significantly reduced in sensitive facilities such as hospital and restaurant, even though pesticide and bactericide were more frequently applied there. The implications of these findings were discussed in this article.

关键词： German cockroaches Blattella germanica diversity bacteria

Assessment of Benchmark Dose in BEAS-2B Cells by Evaluating the Cell Relative Viability with Particulates in Motorcycle Exhaust via the Air-liquid Interface Exposure

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Biomedical and Environmental Sciences 2021年第4期34卷 272-281页

作者： YU Tao ZHANG xue Yan LI Shu fei ZHOU Yu Mei LI Bin WANG Zhong Xu DAI Yu fei ADAMSON Sherleen xue-fu ZHENG Yu Xin BIN Ping National Institute of Occupational Health and Poison Control Chinese Center for Disease Control and PreventionBeijing 100050China Tianjin Center for Diseases Prevention and Control Tianjin 300011China School of Health Sciences Purdue UniversityWest Lafayette 47907Indiana USA School of Public Health Qingdao UniversityQingdao 266021ShandongChina

Objective This study aimed to use an air-liquid interface(ALI)exposure system to simulate the inhalation exposure of motorcycle exhaust particulates(MEPs)and then investigate the benchmark dose(BMD)of MEPs by evaluating cell relative viability(CRV)in lung epithelial BEAS-2B *** The MEPs dose was characterized by measuring the number concentration(NC),surface area concentration(SAC),and mass concentration(MC).BEAS-2B cells were exposed to MEPs at different concentrations via ALI and CRV was determined using Cell Counting Kit(CCK-8)*** software was applied to calculate BMD and the lower limit of benchmark dose(BMDL)according to Akaike Information Coefficient(AIC),with P-value based on Hill,Linear,Polynomial,and Power *** Our results reveal that BMD of NC and SAC were estimated by the best-fitting Hill model,while MC was estimated by Polynomial *** BMDL for CRV following ALI exposure to MEPs were as follows:364.2#/cm^(3)for NC;0.662×10^(7)nm^(2)/cm^(3)for SAC;and 0.278μg/m^(3)for *** These results indicate that MEPs exposure via ALI system induces a dose-dependent decrease of CRV and provides the potential exposure threshold of MEPs in a lung cell model.

关键词： Motorcycle exhaust particulates Air-liquid interface Bronchial epithelial cells Cell relative viability Dose-dependent effect

Coupling dehydrogenation of isobutane in the presence of carbon dioxide over chromium oxide supported on active carbon

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Chinese Chemical Letters 2008年第9期19卷 1059-1062页

作者： Jian fei Ding Zhang Feng Qin xue Kuan Li Guo fu Wang Jian Guo Wang State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences P.O. Box 165 Taiyuan 030001 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

The dehydrogenation of isobutane （IB） to produce isobutene coupled with reverse water gas shift in the presence of carbon dioxide was investigated over the catalyst Cr2O3 supported on active carbon （Cr2O3/AC）. The results illustrated that isobutane conversion and isobutene yield can be enhanced through the reaction coupling in the presence of carbon dioxide. Moreover, carbon dioxide can partially eliminate carbonaceous deposition on the catalyst and keep the active phase （Cr2O3）, which are then helpful to alleviate the catalyst deactivation.

关键词： Dehydrogenation Isobutane Carbon dioxide Isobutene Reaction coupling Cr2O3/AC

Hierarchical Reinforcement Learning With Automatic Sub-Goal Identification

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IEEE/CAA Journal of Automatica Sinica 2021年第10期8卷 1686-1696页

作者： Chenghao Liu fei Zhu Quan Liu Yuchen fu School of Computer Science and Technology Soochow UniversitySuzhou 215006China School of Computer Science and Engineering Changshu Institute of TechnologyChangshu 215500China

In reinforcement learning an agent may explore ineffectively when dealing with sparse reward tasks where finding a reward point is *** solve the problem,we propose an algorithm called hierarchical deep reinforcement learning with automatic sub-goal identification via computer vision(HADS)which takes advantage of hierarchical reinforcement learning to alleviate the sparse reward problem and improve efficiency of exploration by utilizing a sub-goal *** uses a computer vision method to identify sub-goals automatically for hierarchical deep reinforcement *** to the fact that not all sub-goal points are reachable,a mechanism is proposed to remove unreachable sub-goal points so as to further improve the performance of the *** involves contour recognition to identify sub-goals from the state image where some salient states in the state image may be recognized as sub-goals,while those that are not will be removed based on prior *** experiments verified the effect of the algorithm.

关键词： Hierarchical control hierarchical reinforcement learning option sparse reward sub-goal

Human neural stem cell-derived extracellular vesicles protect against ischemic stroke by activating the PI3K/AKT/mTOR pathway

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Neural Regeneration Research 2025年第11期20卷 3245-3258页

作者： Jiayi Wang Mengke Zhao Dong fu Meina Wang Chao Han Zhongyue Lv Liang Wang Jing Liu Stem Cell Clinical Research Center The First Affiliated Hospital of Dalian Medical UniversityDalianLiaoning ProvinceChina Dalian Innovation Institute of Stem Cell and Precision Medicine DalianLiaoning ProvinceChina Institute(College)of Integrative Medicine Dalian Medical UniversityDalianLiaoning ProvinceChina

Human neural stem cell-derived extracellular vesicles exhibit analogous functions to their parental cells,and can thus be used as substitutes for stem cells in stem cell therapy,thereby mitigating the risks of stem cell therapy and advancing the frontiers of stem cell-derived *** lays a foundation for the development of potentially potent new treatment modalities for ischemic ***,the precise mechanisms underlying the efficacy and safety of human neural stem cell-derived extracellular vesicles remain unclear,presenting challenges for clinical *** promote the translation of therapy based on human neural stem cell-derived extracellular vesicles from the bench to the bedside,we conducted a comprehensive preclinical study to evaluate the efficacy and safety of human neural stem cell-derived extracellular vesicles in the treatment of ischemic *** found that administration of human neural stem cell-derived extracellular vesicles to an ischemic stroke rat model reduced the volume of cerebral infarction and promoted functional recovery by alleviating neuronal *** human neural stem cell-derived extracellular vesicles reduced neuronal apoptosis by enhancing phosphorylation of phosphoinositide 3-kinase,mammalian target of rapamycin,and protein kinase B,and these effects were reversed by treatment with a phosphoinositide 3-kinase *** findings suggest that human neural stem cell-derived extracellular vesicles play a neuroprotective role in ischemic stroke through activation of phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling ***,we showed that human neural stem cell-derived extracellular vesicles have a good in vivo safety ***,human neural stem cell-derived extracellular vesicles are a promising potential agent for the treatment of ischemic stroke.

关键词： behavior exosome extracellular vesicles ischemic stroke mammalian target of rapamycin(mTOR) middle cerebral artery occlusion neural stem cells neuronal apoptosis phosphoinositide 3-kinase(PI3K) protein kinase B(AKT)

On Counting Certain Abelian Varieties Over Finite Fields

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Acta Mathematica Sinica,English Series 2021年第1期37卷 205-228页

作者： Jiang Wei xue Chia fu YU Collaborative Innovation Center of Mathematics School of Mathematics and StatisticsWuhan UniversityWuhan 430072P.R.China Institute of Mathematics Academia Sinica and NCTS6th FloorAstronomy Mathematics BuildingNo.1Roosevelt Rd.Sec.4Taipei 10617TaiwanChina

This paper contains two parts toward studying abelian varieties from the classification point of *** a series of papers[***.,21,1607–1643(2016)],[Taiwan Residents ***.,20(4),723–741(2016)],etc.,the current authors and *** obtain explicit formulas for the numbers of superspecial abelian surfaces over finite *** this paper,we give an explicit formula for the size of the isogeny class of simple abelian surfaces with real Weil number q1/*** establishes a key step that extends our previous explicit calculation of superspecial abelian surfaces to those of supersingular abelian *** second part is to introduce the notion of genera and idealcomplexes of abelian varieties with additional structures in a general *** purpose is to generalize the previous work by the second named author[Forum Math.,22(3),565–582(2010)]on abelian varieties with additional structures to similitude classes,which establishes more results on the connection between geometrically defined and arithmetically defined masses for further investigations.

关键词： Mass formula abelian varieties over finite fields

Identification and characterization of a TLR13 gene homologue from Laodelphax striatellus involved in the immune response induced by rice stripe virus

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Journal of Integrative Agriculture 2020年第1期19卷 183-192页

作者： ZHOU xue HU Jia fu Mei-li JIN Ping ZHANG Yun-ye XIANG Ying LI Yao MA fei School of Chemistry and Biological Engineering Nanjing Normal University Taizhou CollegeTaizhou 225300P.R.China College of Horticulture and Plant Protection Yangzhou UniversityYangzhou 225009P.R.China Laboratory for Comparative Genomics and Bioinformatics&Jiangsu Key Laboratory for Biodiversity and Biotechnology College of Life ScienceNanjing Normal UniversityNanjing 210046P.R.China

Toll-like receptors(TLRs) are the critical superfamily homologues that initiate sensing of the invasion of pathogens by the Toll pathway. As one of several intracellular nucleic acid-sensing TLRs, TLR13 is activated by an unmethylated motif present in the large ribosomal subunit of bacterial RNA. However, little attention has been paid to the function of TLR13 gene homologue from Laodelphax striatellus(designated as LsToll-13) in the immune response to rice stripe virus(RSV). Herein, LsToll-13 was cloned and characterized using RACE-PCR. Phylogenetic analysis showed that LsToll-13 was clustered with the TLR13 from six insects. Real-time PCR analysis demonstrated that the expression level of LsToll-13 was significantly reduced in L. striatellus with RSV infection compared with that in the naive strain. When the expression of LsToll-13 was significantly up-regulated at 6 h after bacterial infection, the expression of ribonucleoprotein(RNP) indicated that the RSV titer in the host insect was significantly suppressed. Upon knockdown of LsToll-13, using RNA interference(RNAi) in L. striatellus, the expression level of RNP was significantly increased with enhanced RSV accumulation, suggesting that LsToll-13 potentially protects L. striatellus from RSV infection. Taken together, our results indicated that LsToll-13 might be involved in the immune response of L. striatellus to RSV infection, and provided a new insight into further elucidating the molecular mechanisms of complex pathogen-host interactions and integrative pest management.

关键词： Laodelphax striatellus RSV TLR13 RNAi antiviral immunity

M?bius Regular Maps of Order pq

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Acta Mathematica Sinica,English Series 2019年第5期35卷 690-702页

作者： fu Rong WANG Shao fei DU School of Information Beijing Wuzi University School of Mathematical Sciences Capital Normal University

M?bius regular maps are surface embeddings of graphs with doubled edges such that(i)the automorphism group of the embedding acts regularly on flags and(ii) each doubled edge is a center of a M?bius band on the surface... 详细信息

关键词： Mobius regular maps regular embedding permutation group