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Study on Melting and Recrystallization of Poly(butylene succinate) Lamellar Crystals via Step Heating Differential Scanning Calorimetry

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Chinese Journal of Polymer Science 2017年第12期35卷 1552-1560页

作者： Zhi-yu Lv michael C.Zhang Yang Zhang Bao-hua Guo 徐军 Key Laboratory of Advanced Materials (Ministry of Education) Department of Chemical Engineering Tsinghua University

Differential scanning calorimetry（DSC） has been widely applied to study crystallization and melting of materials. However, for polymeric lamellar crystals, the melting thermogram during heating process usually exhibits a broad endothermic peak or even multiple endotherms, which may result from changes of metastability via recrystallization process. Sometimes, the recrystallization exotherm cannot be observed due to its overlapping with the melting endotherm. In this work, we employed a step heating procedure consisting of successive heating and temperature holding stages to measure the metastability of isothermally crystallized poly（butylene succinate）（PBS） crystals. With this approach we could gain the fraction of crystals melted at different temperature ranges and quantitatively detect the melting-recrystallization behavior. The melting-recrystallization behavior depends on the polymer chain structure and the crystallization temperature. For instance, PBS block copolymer hardly shows recrystallization behavior while PBS oligomer and high molecular weight PBS homopolymer demonstrate remarkable melting-recrystallization phenomenon. High molecular weight PBS isothermally crystallized in the low temperature range shows multiple melting-recrystallization while those isothermally crystallized at elevated temperatures do not exhibit observable recrystallization behavior. Furthermore, the melting endotherms were fitted via the melting kinetics equations. The original isothermally crystallized lamellae demonstrate quite different melting kinetics from the recrystallized lamellar crystals that melt at the highest temperature range, which is attributed to the different degrees of stabilization. Finally, the mechanism of melting-recrystallization is briefly discussed. We propose that apparent meltrecrystallization phenomenon be observed when melting of preformed lamellar crystals and recrystallization of thicker lamellae have similar free energy barrier.

关键词： DSC Step heating Poly(butylene succinate) Metastability Melting-recrystallization Melting kinetics

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-lormone levels following surgical and medical castration： defining optimal androgen suppression

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Asian Journal of Andrology 2018年第4期20卷 405-406页

作者： michael T Schweizer michael L Hancock Robert H Getzenberg Evan Y yu Division of Oncology Department of Medicine University of Washington Seattle WA 98116 USA Clinical Research Division Fred Hutchinson Cancer Research Center Seattle WA 98116 USA Veru Healthcare Miami FL 33137 USA

Dear Editor, In the 1940s, Charles Huggins discovered that surgical castration produced remarkable palliative benefits for men with advanced prostate cancer, an effect we now understand to be mediated through deprivi... 详细信息

关键词： FREE TESTOSTERONE DEPRIVATION THERAPY PROSTATE-CANCER ADRENAL-GLANDS MEN

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Discovery of the marine Eocene in the northern South China Sea

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National Science Review 2019年第5期6卷 881-886页

作者： Zhimin Jian Haiyan Jin michael A Kaminski Fabricio Ferreira Baohua Li Pai-Sen yu State Key Laboratory of Marine Geology Tongji University Geosciences Department King Fahd University of Petroleum and Minerals Institute for Geosciences Universidade Federal Fluminense Nanjing Institute of Geology and Paleontology Chinese Academy of Sciences Applied Research Laboratories(NARLabs) Taiwan Ocean Research Institute(TORI)

The nature of the Eocene stratigraphy of the South China Sea (SCS) has been a mystery for *** the southern SCS, the Eocene system with marine deposits is often considered as representing part of the ‘Proto-South Chin... 详细信息

关键词： SCS Sr Discovery of the marine Eocene in the northern South China Sea China

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Organocatalytic asymmetric[2+2] cycloaddition of alkynes with quinones

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Science China Chemistry 2023年第8期66卷 2292-2299页

作者： Huai-Ri Sun Lan Yang yu Li Le yu Bo-Bo Gou Atif Sharif Qing-Song Jian Jie Chen Ling Zhou Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry&Materials ScienceNorthwest UniversityXi’an710127China

A chiral phosphoric acid catalyzed enantioselective[2+2] cycloaddition of alkynylindols or alkynylnaphthols with quinones is disclosed.A class of functionalized cyclobutenes with excellent yields,diastereo-and enantioselectivities were prepared under mild reaction conditions(70 examples,up to 99%yield,99%ee,all>50:1 dr).Mechanistic studies revealed that a dearomatization of indole or naphthol occurred to initiate the cycloaddition,followed by an intramolecular michael addition with in situ generated allene-iminium or vinylidene-quinone methide *** competitive[2+3] cycloaddition was prevented in this catalytic *** interesting central to axial chirality conversion via a rearrangement process was realized during transformation of the product.

关键词： organocatalysis [2+2]cycloaddition asymmetric catalysis alkynes cyclobutenes

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The Efficiency of the Chinese Commodity Futures Markets: Development and Empirical Evidence

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China & World Economy 2006年第2期14卷 79-92页

作者： yu Xin Gongmeng Chen michael Firth Associate Professor Department of Finance and Investment School of Business Sun Yat-sen （Zhongshan） University Guangzhou China. Professor Antai School of Management Shanghai Jiaotong University Shanghai China. Chair Professor School of Accounting and Finance The Hong Kong Polytechnic University Hong Kong China.

This study investigates the efficiency of the Chinese metal futures （i.e. copper and aluminum） traded on China＇s Shanghai Futures Exchange. First, we thoroughly analyze the development of China＇s commodity futures markets, which provides a fundamental background. Then we examine the random walk and unbiasedness hypotheses for two metal futures during 1999-2004. Based on the empirical evidence, we argue that China＇s copper and aluminum futures markets are efficient, and that they aid the process of price discovery because futures prices can be considered as unbiased predictors of future spot prices. We attribute this efficiency to the regulatory changes made in 1999 and the increased financial skills and acumen of the participants in the market.

关键词： China commodity futures market efficiency

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Modified correlation for minimum fluidization velocity of low-density particles in inverse liquid-solid fluidized beds

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Particuology 2022年第12期71卷 56-62页

作者： michael Nelson Saleh Srabet Tian Nan Dominic Pjontek Jesse Zhu Collaborative Innovation Center of Chemical Science and Engineering School of Chemical Engineering and TechnologyTianjin UniversityChina Particle Technology Research Centre Department of Chemical and Biochemical EngineeringWestern UniversityCanada

The minimum fluidization velocity(U_(mf))is a key parameter for the scale-up of inverse liquid-solid flu-idized *** predictions using common correlations were compared against experimental minimum fluidization velocity measurements of low density(28-638 kg/m^(3)),0.80-1.13 mm Styrofoam particles in a fluidized bed with a height of 4.5 m and 0.2 m *** average absolute relative deviation for the predicted minimum fluidization velocity for particles below 300 kg/m^(3) was above 40%using the studied common correlations.A modified Wen and yu correlation was thus proposed based on novel and past measurements with low-density and small-diameter particles,expanding the range for predicting U_(mf).The new correlation predicted U_(mf) with deviations below 15%for ST028,ST122 and *** modified correlation also improved U_(mf) predictions for comparable particles from a previous study,demonstrating its validity for a larger range of low-density particles.

关键词： Liquid-solid fluidization Inverse fluidization Minimum fluidization velocity Low-density particles

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Effects of clonal integration, nutrients and cadmium on growth of the aquatic macrophyte Pistia stratiotes

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Journal of Plant Ecology 2020年第6期13卷 765-772页

作者： michael Opoku Adomako Peter Alpert Dao-Lin Du Fei-Hai yu Institute of Wetland Ecology&Clone Ecology/Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation Taizhou UniversityTaizhou 318000China Institute of Environment and Ecology Academy of Environmental Health and Ecological SecuritySchool of the Environment and Safety EngineeringJiangsu UniversityZhenjiang 212013China Department of Biology University of MassachusettsAmherstMA 01003USA

许多湿地同时遭受养分和有毒金属的污染,其植被多数为克隆植物。我们假设,富养化和克隆整合可以通过增加植物的生长来提高对有毒金属污染的植物修复能力,即使在毒性胁迫环境下也是如此。为验证此假说,我们将常见、广布的匍匐茎漂浮植物... 详细信息

许多湿地同时遭受养分和有毒金属的污染,其植被多数为克隆植物。我们假设,富养化和克隆整合可以通过增加植物的生长来提高对有毒金属污染的植物修复能力,即使在毒性胁迫环境下也是如此。为验证此假说,我们将常见、广布的匍匐茎漂浮植物大薸(Pistia stratiotes L.)的单个分株种植在两种不同的养分条件下和两种镉污染处理(无镉或含0.6 mg L^(-1)的镉)中42天。通过保持或切断母株与其后代分株之间的连接来维持或阻止克隆整合,并通过保留或移除切断后的后代分株来控制克隆内竞争的有无。由于高养分条件下克隆后代分株的数量增加了一倍,因此镉处理下大薸的生物量在高养分条件下几乎是在低养分条件下的两倍。切断匍匐茎连接对整个克隆(母株和后代分株的总和)的生物量没有影响。切断连接后去除后代分株对镉污染下母株的生物量没有显著的影响,但却显著增加了无镉污染下母株的生物量。这些研究结果支持富养化可以提高水生植物对有毒金属污染的修复能力这一假说,但并不支持克隆整合有利于植物修复的假说。因此,水生植物(如大薸)可能有助于对同时遭受有毒金属和养分污染的湿地进行修复,但克隆片段化对植物的这种修复能力可能没有显著影响。

关键词：生物修复克隆片段化富养化漂浮植物有害金属

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Verification of an independent dose calculation method for portal-specific QA of proton and carbon ion beams

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Radiation Medicine and Protection 2022年第3期3卷 152-157页

作者： michael F.Moyers Qianxia Wang yu Deng Hongliang Chen Zhi Chen Xiaoli Liu Nicki Schlegel Jie Li Zhuangming Shen James Lin Pablo Yepes Shanghai Proton and Heavy Ion Center Shanghai 201315China Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy Shanghai 201315China Rice University HoustonTXUSA

Objective:To verify the accuracy of an independent dose calculation method,as incorporated into an in-house developed treatment planning system(TPS),for performing quality assurance of dose distributions delivered to a water phantom planned by a clinical ***:A Monte Carlo based track repeating algorithm was incorporated into an in-house treatment planning system for proton and carbon ion *** were performed in a flat water phantom for both a traditional pencil beam algorithm and a new Monte Carlo algorithm,and then compared to measurements made at multiple depths with a 2D ionization array for 44 patient *** comparisons utilized a Gamma ***:A total of 124 measurements were performed for proton and carbon ion patient *** a small Gamma criteria of 2%/2 mm,an average of 93%and 97%of measurement points passed for each portal for pencil beam and Monte Carlo calculations,*** passing rate was substantially higher for Monte Carlo calculations than for pencil beam calculations for portals that used a range ***:The implemented independent method has been verified against *** high passing rate with small tolerances leads to the possibility of reducing the number of required quality assurance measurements.

关键词： Ion beam Quality assurance Monte Carlo Ionization chamber array

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Seroprevalence of influenza viruses in Shandong,Northern China during the COVID-19 pandemic

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Frontiers of Medicine 2022年第6期16卷 984-990页

作者： Chuansong Quan Zhenjie Zhang Guoyong Ding Fengwei Sun Hengxia Zhao Qinghua Liu Chuanmin Ma Jing Wang Liang Wang Wenbo Zhao Jinjie He yu Wang Qian He michael J.Carr Dayan Wang Qiang Xiao Weifeng Shi Key Laboratory of Etiology and Epidemiology of Emerging Infectious Diseases in Universities of Shandong Shandong First Medical University&Shandong Academy of Medical SciencesTaian 271000China School of Public Health Shandong First Medical University&Shandong Academy of Medical SciencesJinan 250117China The Department of Infectious Disease The Second Affiliated Hospital of Shandong First Medical UniversityTaian 271000China Clinical Laboratory The Department of Clinical LaboratoryBoshan District HospitalZibo 255200China Clinical Laboratory The Department of Clinical LaboratoryThe Second Affiliated Hospital of Shandong First Medical UniversityTaian 271000China The Department of Cancer Center Taian Tumor Prevention and Treatment HospitalTaian271000China National Virus Reference Laboratory School of MedicineUniversity College DublinDublin 4Ireland International Collaboration Unit International Institute for Zoonosis ControlHokkaido UniversitySapporoHokkaido0010020Japan Chinese National Influenza Center National Institute for Viral Disease Control and PreventionCollaboration Innovation Center for Diagnosis and Treatment of Infectious DiseasesChinese Center for Disease Control and PreventionKey Laboratory for Medical VirologyNational Health and Family Planning CommissionBeijing102206China

Nonpharmaceutical interventions(NPIs)have been commonly deployed to prevent and control the spread of the coronavirus disease 2019(COVID-19),resulting in a worldwide decline in influenza ***,the influenza risk in China warrants cautious *** conducted a cross-sectional,seroepidemiological study in Shandong Province,Northern China in *** inhibition was performed to test antibodies against four influenza vaccine strains.A combination of descriptive and meta-analyses was adopted to compare the seroprevalence of influenza antibodies before and during the COVID-19 *** overall seroprevalence values against A/H1N1pdm09,A/H3N2,B/Victoria,and B/Yamagata were 17.8%(95%CI 16.2%–19.5%),23.5%(95%CI 21.7%–25.4%),7.6%(95%CI 6.6%–8.7%),and 15.0(95%CI 13.5%–16.5%),respectively,in the study *** overall vaccination rate was extremely low(2.6%).Our results revealed that antibody titers in vaccinated participants were significantly higher than those in unvaccinated individuals(P<0.001).Notably,the meta-analysis showed that antibodies against A/H1N1pdm09 and A/H3N2 were significantly low in adults after the COVID-19 pandemic(P<0.01).Increasing vaccination rates and maintaining NPIs are recommended to prevent an elevated influenza risk in China.

关键词： influenza virus seroprevalence antibody COVID-19 cross-sectional study

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The ERα/KDM6B regulatory axis modulates osteogenic differentiation in human mesenchymal stem cells

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Bone Research 2022年第1期10卷 95-106页

作者： Zhenqing Liu Hye-Lim Lee Jin Sook Suh Peng Deng Chang-Ryul Lee Olga Bezouglaia Mojan Mirnia Vivian Chen michael Zhou Zhong-Kai Cui Reuben HKim Min Lee Tara Aghaloo Christine Hong Cun-yu Wang Division of Oral Biology and Medicine School of DentistryUniversity of CaliforniaLos Angeles(UCLA)Los AngelesCA 90095USA Department of Anatomy&Neurobiology University of CaliforniaIrvine(UCI)IrvineCA 92697USA Department of Orofacial Sciences School of DentistryUniversity of CaliforniaSan Francisco(UCSF)San FranciscoCA 94143USA School of Dentistry University of CaliforniaSan Francisco(UCSF)San FranciscoCA 94143USA Division of Diagnostic and Surgical Sciences School of DentistryUniversity of CaliforniaLos Angeles(UCLA)Los AngelesCA 90095USA School of Dentistry University of CaliforniaLos Angeles(UCLA)Los AngelesCA 90095USA Division of Advanced Prosthodontics School of DentistryUniversity of CaliforniaLos Angeles(UCLA)Los AngelesCA 90095USA Division of Constitutive and Regenerative Sciences School of DentistryUniversity of CaliforniaLos Angeles(UCLA)Los AngelesCA 90095USA Department of Bioengineering University of CaliforniaLos Angeles(UCLA)Los AngelesCA 90095USA

Osteoporosis is a highly prevalent public health burden associated with an increased risk of bone fracture, particularly in aging women. Estrogen, an important medicinal component for the preventative and therapeutic treatment of postmenopausal osteoporosis, induces osteogenesis by activating the estrogen receptor signaling pathway and upregulating the expression of osteogenic genes, such as bone morphogenetic proteins(BMPs). The epigenetic regulation of estrogen-mediated osteogenesis,however, is still unclear. In this report, we found that estrogen significantly induced the expression of lysine-specific demethylase 6B(KDM6B) and that KDM6B depletion by shRNAs led to a significant reduction in the osteogenic potential of ***, upon estrogen stimulation, estrogen receptor-α(ERα) was recruited to the KDM6B promoter, directly enhancing KDM6B expression. Subsequently, KDM6B was recruited to the BMP2 and HOXC6 promoters, resulting in the removal of H3K27me3 marks and activating the transcription of BMP2 and HOXC6, the master genes of osteogenic differentiation. Furthermore, we found that estrogen enhanced DMSC osteogenesis during calvarial bone regeneration and that estrogen’s pro-osteogenic effect was dependent on KDM6B in vivo. Taken together, our results demonstrate the vital role of the ERα/KDM6B regulatory axis in the epigenetic regulation of the estrogen-dependent osteogenic response.

关键词： expression stimulation ERα

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