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Dynamics of Polymeric Fluids：Part Ⅱ The Molecular Theory of Die Swell： Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

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Journal of Materials Science & Technology 2006年第5期22卷 664-676页

作者： Mingshi SONG Qiang XU guixian hu Sizhu WU Key Laboratory of Science and Technology of Controlled Chemical Reactions Beijing University of Chemical TechnologyBeijing 100029 China

A general expression for the correlation of the simple shear （tanφ） to the molecular parameters and the shear rate （·↑γ） was deduced. It shows that the simple shear （tanφ） may be resolved into free recoil （recoverable strain） and viscous heating （unrecoverable strain）. The magnitudes of the simple shears for recoil （tanφE） and （tanφv） for viscous heating not only depended on the molecular parameters and the operational variables, but also on the exponential fractions of the recoverable （1--↑W·↑γ） and unrecoverable （-↑W·↑γ） conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears （tanφE） for recoil and （tanφv） for viscous heating are, respectively, expressed as the partition function to the （1--↑W·↑γ）th power and the partition function to the （-↑W·↑γ）th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [n′, α, η0, GN^0 and （1--↑W·↑γ）] and the operational variables （·↑γ, （L/D） and tr） were deduced respectively, which show that at very different shear rates （0≤·↑γ≤∞） the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=（L/D）], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [n′, α, η0, GN^0 and （1--↑W·↑γ）] and the operational variables （·↑γ, （L/D） and tr） were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene （HDPE） which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.

关键词： Die swell Viscoelastic recoil Entanglement

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Correlation of cooperatively localized rearrangement on the "fluidized domain" in glass substances (or polymers) to their fragility Ⅲ:Theory of dynamic fragility at isochoric state

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Science China(Physics,Mechanics & Astronomy) 2011年第3期54卷 420-436页

作者： JIN Yan SONG MingShi hu guixian WU DaMing School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China School of Mechanical and Electrical Engineering Beijing University of Chemical Technology Beijing 100029 China

A set of universal equations on the reduced stress relaxation modulus with K-W-W stretched exponential function has been derived from the dynamics of α and β structural relaxation processes. In the present work, the K-W-W decay function is used to define the three types of relaxations (single α, single β relaxation and α-β co-relaxation), then their average times of relaxation are theoretically calculated from the reduced shear stress relaxation modulus and the relaxation time spectrum function H(τ). When the average time of co-relaxation, the reference temperatures (ficitive Tf and glass transition Tg) and the isostructural parameter achieved from the conditions of isostructural glass state are introduced into the reduced shear stress relaxation modulus (GT) under the equilibrium state, a set of correlations between isochoric fragility index (mvα, mvβ and mvαβ) and the coupling strength (α and β) under the reference temperatures are derived from the exact definition of isochoric fragility. So the theory of dynamic fragility for glass substances at isochoric state is developed. The theory can predict the following main features of structural relaxations and behavior of isochoric fragility: the temperature dependence of peak relaxation frequency exhibits a bifurcation with a pair of single α and single β relaxations; the temperature dependence of Stickel equation on 1/T exhibits two crossovers with VFTH(1) and VFTH(2) at the temperatures of Tf and Tg regime; there are two linear correlations between isochoric fragility index (mvα and mvβ) and the coupling strength. Fine agreements between the theoretical calculation and experimental results are obtained.

关键词： isochoric fragility fluidized domain constituent chains &alpha and &beta relaxation dynamics of structural relaxation reduced stress relaxation modulus

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Dynamics of Polymeric Fluids 1. The Molecular Theory of Die Swell:A Set of Equation on Swelling Ratio in Extrudates

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Journal of Materials Science & Technology 2006年第1期22卷 93-107页

作者： Mingshi SONG guixian hu Zhihong YANG Qiang xu Sizhu WU Key Laboratory of Science and Technology of Controlled Chemical Reactions Beijing University of Chemical TechnologyBeijing 100029 China

The structural model of the multiple-transient networks and the mechanism of the multiple-reptation entangled chains due to the dynamic reorganization in the entangled sites were extensively applied on the die swell of polymeric liquids in the steady simple shear flow. The total （recoverable and unrecoverable） viscoelastic free energy of deformation and flow, the constitutive equation and the expression of the simple shear （tanψ） were deduced from the conformational probability distribution function of the entangled polymer chains. It found that：（1） the magnitudes of simple shear （tanψ） depended not only on the free recoil （or recoverable strain） but also on the viscous heating （or unrecoverable strain）; （2） the total recoil may be resolved into the instantaneous and delayed recoil. Based on these facts, the functions of the partition and two experiential fractions of the recoverable （1-Wγ） and the unrecoverable （Wγ） conformations for the recoil and viscous heating of polymeric liquids were defined correspondingly. Then the correlation of the instantaneously and ultimately （or total） recoverable strains to the （N1/T12）w and the fraction of trans-form conformation was obtained. After introducing the condition of uniform two-dimensional extension （αx=αy=α, αz=α^-2） and the swell ratio （B=α）, two sets of equations on the instantaneous and ultimate swelling ratios （BE, BEVT） were obtained, and a method to determine the fraction of the recoverable transform conformation were proposed, The equations of BE and BE5 were verified by the experimental data of HDPE （high denisity polyethylene） at two different high temperatures. It shows that the molecular theory of die swell can be used to predict the correlation of the swelling to the （NI/TI2）w and the fraction of trans-form conformation.

关键词： Die swell Entanglement Viscoelastic recoil

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茭白全产业链标准化探索与实践

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农产品质量与安全 2024年第3期 5-8页

作者：胡桂仙赖爱萍李雪孙素玲刘岩钱永忠浙江省农业科学院农产品质量安全与营养研究所杭州310021 中国农业科学院农业质量标准与检测技术研究所农业农村部农产品质量标准研究中心北京100081

农产品全产业链标准化生产,是切实保障农产品质量安全,推动农业高质量发展的重要技术支撑。本文以茭白产品为主线,通过建立协同推进机制、研制全产业链标准、落实标准化生产技术、开展技术宣传推广等进行茭白全产业链标准化探索与实践,... 详细信息

农产品全产业链标准化生产,是切实保障农产品质量安全,推动农业高质量发展的重要技术支撑。本文以茭白产品为主线,通过建立协同推进机制、研制全产业链标准、落实标准化生产技术、开展技术宣传推广等进行茭白全产业链标准化探索与实践,为现代农业全产业链标准化实施工作提供参考借鉴。

关键词：茭白全产业链标准化探索实践

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Rheological Behavior for Polymer Melts and Concentrated Solutions——Part Ⅶ: A Quantitative Verification for the Molecular Theory of Non-linear Viscoelasticity with Entanglement Constraints in Polymer Melts

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Journal of Materials Science & Technology 2001年第3期17卷 375-382页

作者： Mingshi SONG, Chen ZHANG and guixian hu Research Institute of Polymeric Materials, Beijing University of Chemical Technology, Beijing 100029, China E-mail: wangzhchen@*** Res. Inst. of Polymeric Mat. Beijing Univ. of Chem. Technol. Beijing 100029 China

Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) over dot), psi (10)((gamma) over dot) and shear rate ((gamma) over dot), and topologically constrained dimension number n ' and a were derived. Linear viscoelastic parameters (eta (0) and G(N)(0)) and topologically constrained dimension number (n ' a and )over bar>) as a function of the primary molecular weight (M-n), molecular weight between entanglements (M-C) and the entanglement sites sequence distribution in polymer chain were determined. A new method for determination of viscoelastic parameters (eta (0), psi (10), G(N)(0) and J(e)(0)), topologically constrained dimension number (n ', a and v) and molecular weight (M-n, M-c and M-e) from the shear flow measurements was proposed. It was used to determine those parameters and structures of HDPE, making a good agreement between these values and those obtained by other methods. The agreement affords a quantitative verification for the molecular theory of nonlinear viscoelasticity with constrained entanglement in polymer melts.

关键词： Rheological Behavior for Polymer Melts and Concentrated Solutions A Quantitative Verification for the Molecular Theory of Non-linear Viscoelasticity with Entanglement Constraints in Polymer Melts Part

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Early Detection of the Emerging SARS-CoV-2 BA.2.86 Lineage Through Wastewater Surveillance Using a Mediator Probe PCR Assay—Shenzhen City,Guangdong Province,China,2023

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China CDC weekly 2024年第15期6卷 332-338,I0008,I0009页

作者： Chen Du Yuejing Peng Ziquan Lyu Zhijiao Yue Yulin Fu Xiangjie Yao Jinzhen Tang guixian Luo Chenxi Gao Shisong Fang Xiaolu Shi Chengsong Wan Yinghui Li Qinghua hu Shenzhen Center for Disease Control and Prevention Shenzhen CityGuangdong ProvinceChina BSL-3 Laboratory(Guangdong) Guangdong Provincial Key Laboratory of Tropical Disease ResearchSchool of Public HealthSouthern Medical UniversityGuangzhou CityGuangdong ProvinceChina Department of Public Health Laboratory Sciences School of Public HealthHengyang Medical SchoolUniversity of South ChinaHengyang CityHunan ProvinceChina School of Public Health Shanxi Medical UniversityTaiyuan CityShanxi ProvinceChina

Introduction:The emergence of the new severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Omicron sublineage,BA.2.86,has sparked global public health concerns for its potential heightened transmissibility and immune *** data from Shenzhen’s city-wide wastewater surveillance system,we highlight the presence of the BA.2.86 lineage in ***:A mediator probe polymerase chain reaction(PCR)assay was developed to detect the BA.2.86 lineage in wastewater by targeting a specific mutation(Spike:A264D).Between September 19 and December 10,2023,781 wastewater samples from 38 wastewater treatment plants(WWTPs)and 9 pump stations in ten districts of Shenzhen were *** multiple short-amplicon sequencing,three positive samples were ***:The BA.2.86 lineage was identified in the wastewater of Futian and Nanshan districts in Shenzhen on December 2,*** December 2 to 10,a total of 21 BA.2.86-positive wastewater samples were found across 6 districts(Futian,Nanshan,Longhua,Baoan,Longgang,and Luohu)in *** weighted average viral load of the BA.2.86 lineage in Shenzhen’s wastewater was 43.5 copies/L on December 2,increased to 219.8 copies/L on December 4,and then decreased to approximately 100 copies/L on December 6,8,and ***:The mediator probe PCR assay,designed for swift detection of low viral concentrations of the BA.2.86 lineage in wastewater samples,shows promise for detecting different SARS-CoV-2 *** surveillance could serve as an early detection system for promptly identifying specific SARS-CoV-2 variants as they emerge.

关键词： wastewater Wastewater district

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均聚物结晶与熔融化转变的稳态和亚稳态统计理论 III. 分子分凝统计结晶动力学~熔体内结晶增长速率的一般化表征和它们对生长机制的依赖性

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Chinese Journal of Chemical Physics 2005年第5期18卷 197-210页

作者：宋名实胡桂贤王海侨李效玉北京化工大学可控化学反应科学与技术基础教育部重点实验室北京100029

首先对微晶粒尺寸增长速率的表征进行总结.从微晶核和粒—高分子链组网络结构特点(高分子链组是微晶核和微晶粒同连接链段的复合体)同增长速率间的三个相关性的特征: ①晶核和晶粒加大同连接链段缩短的并存性; ②微晶核和粒表面上连接... 详细信息

首先对微晶粒尺寸增长速率的表征进行总结.从微晶核和粒—高分子链组网络结构特点(高分子链组是微晶核和微晶粒同连接链段的复合体)同增长速率间的三个相关性的特征: ①晶核和晶粒加大同连接链段缩短的并存性; ②微晶核和粒表面上连接链段的缩短机制存有简并性; ③微晶粒内和粒表面上stem的反顺式构象共存性出发.建议了一种评估和计算微晶粒尺寸增长速率的新方法和原则,基于该种计算方法和原则用统计力学和动力学相结合法推导出了高分子熔体内几种不同结晶生长机制(近邻折叠、近邻伸直分凝和近邻折叠同近邻伸直分凝并存等生长方式)下微晶粒—高分子链组中微晶粒数增长速率和微晶粒尺寸增长速率动力学方程.

关键词：结晶生长机制结晶生长动力学晶粒数增长速率晶粒尺寸增长速率

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Effects of a periodic intermittent theta burst stimulation in Alzheimer's disease

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General Psychiatry 2024年第1期37卷 53-63页

作者： Xingqi Wu Yibing Yan Panpan hu Lu Wang Yue Wu Pan Wu Zhi Geng guixian Xiao Shanshan Zhou Gongjun Ji Bensheng Qiu Ling Wei Yanghua Tian Hesheng Liu Kai Wang Department of Neurology First ffiliated Hospital of Anhui Medical UniversityHefeiAnhuiChina School of Mental Health and Psychological Sciences Anhui Medical UniversityHefeiAnhuiChina Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders HefeiAnhuiChina Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health HefeiAnhuiChina Department of Psychology and Sleep Medicine The Second Affliated Hospital of Anhui Medical UniversityHefeiAnhuiChina Center for Biomedical Imaging University of Science and Technology of ChinaHefeiAnhuiChina institute of Artificial Intlligence Hefei Comprehensive National Science CenterHefeiAnhuiChina Department of Neuroscience Medical University of South CarolinaCharlestonSouth CarolinaUSA

Background Previous studies havedemonstrated that excitatory repetitive transcranial magnetic stimulation(rTMS)can improve the cognitive function of patients with Alzheimer's disease(AD).Intermittent theta burst stimulation(iTBS)is a novel excitatory rTMS protocol for brain activity stimulation with the ability to induce long-term potentiation-like plasticity and represents a promising treatment for ***,the long-term effects of iTBS on cognitive decline and brain structure in patients with AD *** We aimed to explore whether repeating accelerated iTBS every three months could slow down the cognitive decline in patients with *** In this randomised,assessor-blinded,controlled trial,iTBS was administered to the left dorsolateral prefrontal cortex(DLPFC)of 42 patients with AD for 14days every *** included the Montreal Cognitive Assessment(MoCA),a comprehensive neuropsychological battery,and the grey matter volume(GMV)of the *** were evaluated at baseline and after *** longitudinal pipeline of the Computational Anatomy Toolbox for SPM was used to detect significant treatment-related changes over *** The iTBS group maintained MoCA scores relative to the control group(t=3.26,p=0.013)and reduced hippocampal atrophy,which was significantly correlated with global degeneration scale *** baseline Mini-Mental State Examination(MMSE)score,apolipoprotein E genotype and Clinical Dementia Rating were indicative of MoCA scores at ***,the GMV of the left(t=0.08,p=0.996)and right(t=0.19,p=0.977)hippocampus were maintained in the active group but significantly declined in the control group(left:t=4.13,p<0.001;right:t=5.31,p<0.001).GMV change in the left(r=0.35,p=0.023)and right(r=0.36,p=0.021)hippocampus across the intervention positively correlated with MoCA changes;left hippocampal GMV change was negatively correlated with global degeneration scale(r=-0.32,p=0.041)*** D

关键词： stimulation Alzheimer maintained

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金沙江陡岸隧道洞口施工技术

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铁道标准设计 2005年第8期25卷 76-78页

作者：胡桂先中铁十六局集团第四工程有限公司北京101400

溪洛渡水电站对外交通专用公路新滩1号隧道出口位于金沙江北岸,洞口段32m系浅埋偏压地段,设计为明洞;施工采取了自洞内导洞出洞、明洞基础加固、明洞抗偏压挡墙构筑、明洞格栅护拱构筑、拱顶回填及明洞拱下超前支护、上下断面扩挖、监... 详细信息

溪洛渡水电站对外交通专用公路新滩1号隧道出口位于金沙江北岸,洞口段32m系浅埋偏压地段,设计为明洞;施工采取了自洞内导洞出洞、明洞基础加固、明洞抗偏压挡墙构筑、明洞格栅护拱构筑、拱顶回填及明洞拱下超前支护、上下断面扩挖、监控量测等多项技术,并加强了洞口排水及周边环境保护,顺利实现了浅埋偏压明洞施工。

关键词：公路隧道隧道洞口复杂地段施工

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某校大学生视力状况调查分析

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现代医药卫生 2016年第3期32卷 373-374页

作者：胡贵贤张喆贵阳护理职业学院贵州贵阳550081

目的通过对本校不同年级学生进行视力状况调查,分析大学生视力下降的原因,为在校大学生的健康保健提供参考。方法对本校2013级、2012级、2011级5 351名学生(其中女生4 804名,男生547名)采用国家标准对数视力表,常规对两眼分别进行检查... 详细信息

目的通过对本校不同年级学生进行视力状况调查,分析大学生视力下降的原因,为在校大学生的健康保健提供参考。方法对本校2013级、2012级、2011级5 351名学生(其中女生4 804名,男生547名)采用国家标准对数视力表,常规对两眼分别进行检查。结果本校学生总的视力不良检出率为52.79%,其中轻、中、重度视力不良检出率分别为26.62%,25.45%,47.93%。3个年级学生的视力不良率分别为32.81%、60.67%、68.19%。结论视力不良率随年级的增加而逐渐增加,即学生在大学期间视力呈下降趋势。

关键词：视力,低/流行病学视力,低/预防和控制学生数据收集

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