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A New Phytosterone from Cyanotis arachnoidea

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Chinese Chemical Letters 2002年第3期13卷 245-246页

作者： Cheng Yu TAN Jin Hui WANG Wan XIAO xian li Research Department of Natural Medicinal Shenyang Pharmaceutical UniversityShenyang110015

A new phytosterone named cyanosterone B (1) has been isolated from Cyanotis arachnoidea C. B. Clarke. The structure of cyanosterone B was elucidated as 3 b, 5 b, 14 a, 20 R, 22 R-pentahydroxy-cholest-7-en-6-one ... 详细信息

关键词： Cyanotis arachnoidea cyanosterone B

Intelligent Temperature Control System Design Based on Single-Chip Microcomputer

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Journal of Harbin Institute of Technology(New Series) 2014年第3期21卷 91-94页

作者： Jun li xian-lin Meng Wen-Long Song College of Mechanical and Electrical Engineering Northeast Forestry University School of Municipal and Environmental Engineering Harbin Institute of Technology

A design method of an intelligent temperature control system based on single-chip microcomputer is presented in this paper. The intelligent temperature control system is divided into four parts: monitor,heater,controlled process and feedback loop. Among them,the temperature detection circuit is designed with the conductivity of water by sensor detection. The optical coupler MOC3041 is used to implement the power control circuit,whose control object is 1 kW electric heater with the 220 V alternating current power; keyboard and display circuit SMC1602A include four buttons and LCD display to achieve human-computer interaction; Based on single-chip system STC89C52,the sensor signal and keyboard set target temperature are compared to the power automatically in order to finish the water temperature control. Through the static and dynamic data testing,the results show that the proposed method provides an effective way to realize the real-time acquisition and control of temperature.

关键词： microcontroller temperature sensors power control SCR

Microstructure evolution in grey cast iron during directional solidification

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International Journal of Minerals,Metallurgy and Materials 2017年第8期24卷 884-890页

作者： xian-fei Ding Xiao-zheng li Qiang Feng Warkentin Matthias Shi-yao Huang National Center for Materials Service Safety University of Science and Technology Beijing Beijing Key Laboratory of Special Melting and Preparation of High-end Metal University of Science and Technology Beijing State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Ford Research & Advanced Engineering Europe Materials and Process Research Ford Motor Research and Engineering Center

The solidification characteristics and microstructure evolution in grey cast iron were investigated through Jmat-Pro simulations and quenching performed during directional solidification. The phase transition sequence of grey cast iron was determined as L → L + γ→ L + γ + G →γ + G → P(α + Fe_3C) + α + G. The graphite can be formed in three ways: directly nucleated from liquid through the eutectic reaction(L →γ + G), independently precipitated from the oversaturated γ phase(γ→γ + G), and produced via the eutectoid transformation(γ→ G + α). The area fraction and length of graphite as well as the primary dendrite spacing decrease with increasing cooling rate. Type-A graphite is formed at a low cooling rate, whereas a high cooling rate results in the precipitation of type-D graphite. After analyzing the graphite precipitation in the as-cast and transition regions separately solidified with and without inoculation, we concluded that, induced by the inoculant addition, the location of graphite precipitation changes from mainly the γ interdendritic region to the entire γ matrix. It suggests that inoculation mainly acts on graphite precipitation in the γ matrix, not in the liquid or at the solid–liquid front.

关键词： directional solidification grey cast iron phase transition graphite

A novel adaptive-impulsive synchronization of fractional-order chaotic systems

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Chinese Physics B 2015年第10期24卷 86-92页

作者： Leung Y.T.Andrew li xian-Feng Chu Yan-Dong Zhang Hui Department of Architecture and Civil Engineering City University of Hong Kong School of Mathematics and Physics Lanzhou Jiaotong University School of Mechatronic Engineering Lanzhou Jiaotong University

A novel adaptive-impulsive scheme is proposed for synchronizing fractional-order chaotic systems without the necessity of knowing the attractors＇ bounds in priori. The nonlinear functions in these systems are supposed to satisfy local lipschitz conditions but which are estimated with adaptive laws. The novelty is that the combination of adaptive control and impulsive control offers a control strategy gathering the advantages of both. In order to guarantee the convergence is no less than an expected exponential rate, a combined feedback strength design is created such that the symmetric axis can shift freely according to the updated transient feedback strength. All of the unknown lipschitz constants are also updated exponentially in the meantime of achieving synchronization. Two different fractional-order chaotic systems are employed to demonstrate the effectiveness of the novel adaptive-impulsive control scheme.

关键词： adaptive-impulsive synchronization fractional order chaotic systems combined feedbackstrength

Hollow carbon nanofibers with dynamic adjustable pore sizes and closed ends as hosts for high-rate lithiumsulfur battery cathodes

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Nano Research 2018年第3期11卷 1238-1246页

作者： xiang-Qian Zhang bin He Wen-Cui li An-Hui Lu State Key Laboratory of Fine Chemicals School of Chemical Engineering Faculty of Chemical Environmental and Biological Science and Technology Dalian University of Technology Linggong Road 2 Dalian 116024 China

Designing a better carbon framework is critical for harnessing the high theoretical capacity of li-S batteries and avoiding their drawbacks, such as the insulating nature of sulfur, active material loss, and the polysulfide shuttle reaction. Here, we report an ingenious design of hollow carbon nanofibers with closed ends and protogenetic mesopores in the shell that can be retracted to micropores after sulfur infusion. Such dynamic adjustable pore sizes ensure a high sulfur loading, and more importantly, eliminate excessive contact of sulfur species with the electrolyte. Together, the high aspect ratio and thin carbon shells of the carbon nanofibers facilitate rapid transport of li^＋ ions and electrons, and the closed-end structure of the carbon nanofibers further blocks polysulfide dissolution from both ends, which is remarkably different from that for carbon nanotubes with open ends. The obtained sulfur-carbon cathodes exhibit excellent performance marked by high sulfur utilization, superior rate capability （1,170, 1,050, and 860 mA.h.g-1 at 1.0, 2.0, and 4.0 C （1 C = 1.675 A·g^-1）, respectively）, and a stable reversible capacity of 847 mA·h·g^-1 after 300 cycles at a high rate of 2.0 C.

关键词： hollow carbon nanofibers pore-adjusting strateg sulfur cathodes rate capability energy materials

Hierarchical topic modeling with nested hierarchical Dirichlet process

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 858-867页

作者： Yi-qun DING Shan-ping li Zhen ZHANG bin SHEN School of Computer Science and Technology Zhejiang University Hangzhou 310027 China State Street Hangzhou Hangzhou 310000 China

This paper deals with the statistical modeling of latent topic hierarchies in text corpora. The height of the topic tree is assumed as fixed, while the number of topics on each level as unknown a priori and to be inferred from data. Taking a nonpara-metric Bayesian approach to this problem, we propose a new probabilistic generative model based on the nested hierarchical Dirichlet process (nHDP) and present a Markov chain Monte Carlo sampling algorithm for the inference of the topic tree structure as well as the word distribution of each topic and topic distribution of each document. Our theoretical analysis and experiment results show that this model can produce a more compact hierarchical topic structure and captures more fine-grained topic rela-tionships compared to the hierarchical latent Dirichlet allocation model.

关键词： Topic modeling Natural language processing Chinese restaurant process Hierarchical Dirichlet process Markovchain Monte Carlo Nonparametric Bayesian statistics

ELECTROSTATIC INTERACTION HYBRIDS FROM WATER-BORNE CONDUCTIVE POLYANIliNE AND INORGANIC PRECURSOR CONTAINING CARBOXYL GROUP

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Chinese Journal of Polymer Science 2007年第2期25卷 181-186页

作者： Jing Luo xian-hong Wang Ji li Xiao-jiang Zhao Fo-song Wang State Key Laboratory of Polymer Physicsand Chemistry Changchun Institute of Applied Chermstry Graduate School of Chinese Academy of Sciences Changchun 130022 China

Electrostatic interaction conductive hybrids were prepared in water/ethanol solution by the sol-gel process from inorganic sol containing carboxyl group and water-borne conductive polyaniline （cPANI）. The electrostatic interaction hybrids film displayed 1-2 orders of magnitude higher electrical conductivity in comparison with common hybrids film, showing remarkable conductivity stability against water soaking. Most strikingly, it displayed ideal electrochemical activity even in a solution with pH = 14, which enlarged the conducting polyaniline application window to strong alkaline media.

关键词： Water-borne conductive polyaniline Sol-gel Electrostatic interaction.

Hepatitis B reactivation in patients receiving direct-acting antiviral therapy or interferon-based therapy for hepatitis C:A systematic review and meta-analysis

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World Journal of Gastroenterology 2018年第28期24卷 3181-3191页

作者： xian-Wan Jiang Jian-Zhong Ye Ya-Ting li Lan-Juan li State Key Laboratory for Diagnosis and Treatment of Infectious Diseases The First Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhou 310003Zhejiang ProvinceChina Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases Hangzhou 310003Zhejiang ProvinceChina

AIM To assess the incidence of hepatitis B virus(HBV) reactivation in patients receiving direct-acting antiviral agent(DAA)-based therapy or interferon(IFN)-based therapy for hepatitis C and the effectiveness of preemptive antiHBV therapy for preventing HBV *** The Pub Med, MEDliNE and EMBASE databases were searched, and 39 studies that reported HBV reactivation in HBV/hepatitis C virus coinfected patients receiving DAAbased therapy or IFN-based therapy were included. The primary outcome was the rate of HBV reactivation. The secondary outcomes included HBV reactivation-related hepatitis and the effectiveness of preemptive anti-HBV treatment with nucleos(t)ide analogues. The pooled effects were assessed using a random effects model. RESULTS The rate of HBV reactivation was 21.1% in hepatitis Bsurface antigen(HBs Ag)-positive patients receiving DAAbased therapy and 11.9% in those receiving IFN-based therapy. The incidence of hepatitis was lower in HBs Agpositive patients with undetectable HBV DNA compared to patients with detectable HBV DNA receiving DAA therapy(RR = 0.20, 95%CI: 0.06-0.64, P = 0.007). The pooled HBV reactivation rate in patients with previous HBV infection was 0.6% for those receiving DAA-based therapy and 0 for those receiving IFN-based therapy, and none of the patients experienced a hepatitis flare related to HBV reactivation. Preemptive anti-HBV treatment significantly reduced the potential risk of HBV reactivation in HBs Agpositive patients undergoing DAA-based therapy(RR = 0.31, 95%CI: 0.1-0.96, P = 0.042).CONCLUSION The rate of HBV reactivation and hepatitis flare occurrence is higher in HBs Ag-positive patients receiving DAA-based therapy than in those receiving IFN-based therapy, but these events occur less frequently in patients with previous HBV infection. Preemptive anti-HBV treatment is effective in preventing HBV reactivation.

关键词： Hepatitis C Hepatitis B virus reactivation Coinfection Direct-acting antiviral agents Meta-analysis

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不同真空度条件下爆炸焊接引起的振动特性

火工品 2024年第1期 76-80页

作者：代弦德张曹林丁猛董雷李雪交汪泉安徽理工大学化学工程学院安徽淮南232001 安徽向科化工有限公司安徽安庆246100

为探究不同真空度条件下爆炸焊接引起的振动特性,在5kg TNT当量球形真空爆炸容器中开展铝钢爆炸焊接实验,使用Nubox-8016振动测试仪测试了0,-30,-60,-90 k Pa 4组真空度条件下爆炸焊接过程产生的振动信号,并对容器顶部和距容器中心3m地... 详细信息

为探究不同真空度条件下爆炸焊接引起的振动特性,在5kg TNT当量球形真空爆炸容器中开展铝钢爆炸焊接实验,使用Nubox-8016振动测试仪测试了0,-30,-60,-90 k Pa 4组真空度条件下爆炸焊接过程产生的振动信号,并对容器顶部和距容器中心3m地面处的振动信号进行了时域和频域的分析。结果表明:容器顶部和地面测点的振动速度峰值均随容器内真空压力的升高而逐渐降低,容器结构的频率分布特征与爆炸载荷的大小没有明显关系,由爆炸容器内外气压差产生的预应力对容器结构的影响可以忽略不计。

关键词：爆炸焊接振动真空度频域分布