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Simultaneous Bulk-and Surface-initiated Living Polymerization Studied with a Heterogeneous Stochastic Reaction Model

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Chinese Journal of Polymer Science 2024年第3期42卷 364-372,I0008页

作者： Jia-shu Ma Zhi-Ning Huang Jia-Hao Li Bang-Ping Jiang Yan-Da Liao shi-Chen Ji Xing-Can Shen State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources(Ministry of Education of China)School of Chemistry and Pharmaceutical SciencesGuangxi Normal UniversityGuilin 541004China School of Computer Science and Engineering&School of Software Guangxi Normal UniversityGuilin 541004China

To better characterize the properties of surface-initiated polymers, simultaneous bulk-and surface-initiated polymerizations are usually carried out by assuming that the properties of the surface-initiated polymers resemble those of the bulk-initiated polymers. Through a Monte Carlo simulation using a heterogeneous stochastic reaction model, it was discovered that the bulk-initiated polymers exhibit a higher molecular weight and a lower dispersity than the corresponding surface-initiated polymers, which indicates that the equivalent assumption is invalid. Furthermore, the molecular weight distributions of the two types of polymers are also different, suggesting different polymerization mechanisms. The results can be simply explained by the heterogeneous distributions of reactants in the system. This study is helpful to better understand surface-initiated polymerization.

关键词： Surface-initiated polymerization Polymer brush Stochastic reaction model Heterogeneous polymerization Simultaneous polymerization

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端羟基聚乳酸微球的制备与降解

现代化工 2008年第5期28卷 54-56页

作者：石淑先夏宇正李斗杨知微陈晓农焦书科北京化工大学材料科学与工程学院新型高分子材料制备与加工北京市重点实验室北京100029

以1,4-丁二醇和D,L-乳酸为原料,经缩合聚合法制备了端羟基聚乳酸,并用溶剂挥发法制备了端羟基聚乳酸微球。考察了乳化剂浓度、油水相比例及聚乳酸浓度对微球平均粒径和形貌的影响,并在pH=7.4缓冲溶液中进行了微球的降解。结果表明以二... 详细信息

以1,4-丁二醇和D,L-乳酸为原料,经缩合聚合法制备了端羟基聚乳酸,并用溶剂挥发法制备了端羟基聚乳酸微球。考察了乳化剂浓度、油水相比例及聚乳酸浓度对微球平均粒径和形貌的影响,并在pH=7.4缓冲溶液中进行了微球的降解。结果表明以二氯甲烷为溶剂,PVA作为乳化剂,室温和600 r/min搅拌速度下可制得平均粒径0.5-1.0 m的较均匀的、表面平滑的端羟基聚乳酸微球。随着在pH=7.4下降解时间增加,微球表面变得粗糙。

关键词：端羟基聚乳酸微球溶剂挥发法降解

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两亲性聚乳酸嵌段共聚物的制备及性能研究

北京化工大学学报（自然科学版） 2006年第3期33卷 52-55页

作者：刘健石淑先夏宇正刘幸欣焦书科李效玉北京化工大学新型高分子材料的制备与加工北京市重点实验室北京100029

以端羟基聚乳酸和α-溴代丙酰溴为原料,制备了溴端基的聚乳酸;再以其为大分子引发剂,以溴化亚铜/2,2’-联吡啶为催化体系进行N-乙烯基吡咯烷酮的原子转移自由基聚合,制得了两亲性聚乳酸嵌段共聚物。用IR、GPC对聚合物进行了表征,用接触... 详细信息

以端羟基聚乳酸和α-溴代丙酰溴为原料,制备了溴端基的聚乳酸;再以其为大分子引发剂,以溴化亚铜/2,2’-联吡啶为催化体系进行N-乙烯基吡咯烷酮的原子转移自由基聚合,制得了两亲性聚乳酸嵌段共聚物。用IR、GPC对聚合物进行了表征,用接触角测定仪测定了聚合物薄膜的水接触角,并考察了不同反应时间对共聚物的特性黏度和吸水率的影响。结果表明,该聚乳酸共聚物的亲水性较聚乳酸均聚物明显增大,TEM证实共聚物在水相中可形成一壳多核球状胶束,进一步佐证了该共聚物具有明显的两亲性。

关键词：两亲共聚物原子转移自由基聚合聚乳酸 N-乙烯基吡咯烷酮

Disparities in tree mortality among plant functional types(PFTs)in a temperate forest:Insights into size-dependent and PFT-specific patterns

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Forest Ecosystems 2024年第4期11卷 480-490页

作者： Man Hu Hang shi Rui He Bingbin Wen Haikun Liu Kerong Zhang Xiao shu Haishan Dang Quanfa Zhang Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical GardenChinese Academy of SciencesWuhan 430074China Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station Chinese Academy of Sciences&Hubei ProvinceWuhan 430074China University of Chinese Academy of Sciences Beijing 100049China Forest&Nature Lab Department of EnvironmentGhent UniversityGeraardsbergsesteenweg 267Melle-Gontrode9090Belgium

Tree mortality significantly influences forest structure and function,yet our understanding of its dynamic patterns among a range of tree sizes and among different plant functional types(PFTs)remains *** study analysed size-dependent tree mortality in a temperate forest,encompassing 46 tree species and 32,565 individuals across different PFTs(i.e.,evergreen conifer *** broadleaf species,shade-tolerant ***-intolerant species).By employing all-subset regression procedures and logistic generalized linear mixed-effects models,we identified distinct mortality patterns influenced by biotic and abiotic *** results showed a stable mortality patte rn in eve rgreen conifer species,contrasted by a declining pattern in deciduous broadleaf and shadetolerant,as well as shade-intolerant species,across size *** contribution to tree mortality of evergreen conifer species shifted from abiotic to biotic factors with increasing size,while the mortality of deciduous broadleaf species was mainly influenced by biotic factors,such as initial diameter at breast height(DBH)and conspecific negative *** shade-tolerant species,the mortality of small individuals was mainly determined by initial DBH and conspecific negative density dependence,whereas the mortality of large individuals was subjected to the combined effect of biotic(competition from neighbours)and abiotic factors(i.e.,convexity and pH).As for shade-intolerant species,competition from neighbours was found to be the main driver of tree mortality throughout their growth ***,these insights enhance our understanding of forest dynamics by revealing the size-dependent and PFT-specific tree mortality patterns,which may inform strategies for maintaining forest diversity and resilience in temperate forest ecosystems.

关键词： Size-dependent tree mortality Plant functional type Neighbourhood competition Topography variables Soil properties

Demonstration of a small‐scale power generator using supercritical CO_(2)

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Carbon Energy 2024年第4期6卷 269-290页

作者： Ligeng Li Hua Tian Xin Lin xianyu Zeng Yurong Wang Weilin Zhuge Lingfeng shi Xuan Wang Xingyu Liang Gequn shu State Key Laboratory of Engines Tianjin UniversityTianjinChina Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefeiChina State Key Laboratory of Automotive Safety and Energy Tsinghua UniversityBeijingChina

The supercritical CO_(2)(sCO_(2))power cycle could improve efficiencies for a wide range of thermal power *** sCO_(2)turbine generator plays an important role in the sCO_(2)power cycle by directly converting thermal energy into mechanical work and electric *** operation of the generator encounters challenges,including high temperature,high pressure,high rotational speed,and other engineering problems,such as *** studies of sCO_(2)turbines are insufficient because of the significant difficulties in turbine manufacturing and system *** most experimental investigations that primarily focus on 100 kW‐or MW‐scale power generation systems,we consider,for the first time,a small‐scale power generator using sCO_(2).A partial admission axial turbine was designed and manufactured with a rated rotational speed of 40,000 rpm,and a CO_(2)transcritical power cycle test loop was constructed to validate the performance of our manufactured generator.A resistant gas was proposed in the constructed turbine expander to solve the leakage *** dynamic and steady performances were *** results indicated that a peak electric power of 11.55 kW was achieved at 29,369 *** maximum total efficiency of the turbo‐generator was 58.98%,which was affected by both the turbine rotational speed and pressure ratio,according to the proposed performance map.

关键词： generator performance map power generation supercritical CO_(2) turbine

Ideal predictors of cardiac resynchronization therapy in the canine model of pacing-induced heart failure

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Ideal predictors of cardiac resynchronization therapy in the...

聚丙烯酸-Tb@SiO2聚合物纳米粒子用于炭疽生物标志物检测

中华医学会第十次全国超声医学学术会议

作者： Wang Yong-shi,Gong Xue,shu xian-hong. Department of Echocardiography,Zhongshan Hospital of Fudan University,Shanghai 200032,China

Background:Tissue Doppler imaging(TDI),real-time three-dimensional echocardiography(RT3DE) and speckle tracking strain imaging(STSI) are methods for the assessment of left ventricular(LV) dyssynchrony. In this study w...

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分析化学 2021年第5期49卷 726-732页

作者：邵康凌青青施姝娴叶十一滕渊洁潘再法浙江工业大学化学工程学院长江大学生命科学学院

构建了一种对炭疽生物标志物2,6-吡啶二羧酸(DPA)具有高选择性的聚丙烯酸-Tb@SiO2(PAA-Tb@SiO2)荧光纳米探针。探针中的Tb3+能与DPA形成三配位结构,进而产生"天线效应",使探针荧光增强,可以实现对DPA的高灵敏检测。在0.1～20.0μmol/L... 详细信息

构建了一种对炭疽生物标志物2,6-吡啶二羧酸(DPA)具有高选择性的聚丙烯酸-Tb@SiO2(PAA-Tb@SiO2)荧光纳米探针。探针中的Tb3+能与DPA形成三配位结构,进而产生"天线效应",使探针荧光增强,可以实现对DPA的高灵敏检测。在0.1～20.0μmol/L浓度范围内,探针的荧光强度与DPA浓度呈良好的线性关系,相关系数(R~2)为0.9978,检出限(3σ)为6 nmol/L。采用本方法实现了自来水中DPA的测定,加标回收率在94.6%～116.8%之间,RSD<2%。本方法灵敏度高、选择性好,对环境水样中炭疽芽孢杆菌的检测具有潜在的应用价值。

关键词：炭疽病聚丙烯酸吡啶二羧酸铽二氧化硅荧光探针

脂肪酸甲酯磺酸钠作乳化剂的丙烯酸酯乳液聚合研究

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现代化工 2009年第4期29卷 50-52,54页

作者：石淑先张丁夏宇正焦书科温荔钧北京化工大学碳纤维及功能高分子教育部重点实验室北京100029 鹤岗市清华紫光英力农化有限公司黑龙江鹤岗154108

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸为单体，脂肪酸甲酯磺酸钠C16-MES为乳化剂，通过乳液聚合制备了丙烯酸酯共聚物乳液。根据Davies法计算了C16-MES的HLB值在12．8左右，并且考察了乳化剂用量、引发剂种类及用量、单体配比对聚合稳... 详细信息

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸为单体，脂肪酸甲酯磺酸钠C16-MES为乳化剂，通过乳液聚合制备了丙烯酸酯共聚物乳液。根据Davies法计算了C16-MES的HLB值在12．8左右，并且考察了乳化剂用量、引发剂种类及用量、单体配比对聚合稳定性及乳液稳定性的影响规律。实验结果表明，以C16-MES为乳化剂制备的不同单体配比的丙烯酸酯共聚物乳液稳定，随着乳化剂用量的增加，聚合反应速率增大；引发剂用量相同时，氧化还原引发体系引发的丙烯酸酯乳液聚合速率大于热引发体系。乳胶粒的粒径都在100～200nm.

关键词：脂肪酸甲酯磺酸钠丙烯酸酯乳液聚合乳化剂

Metallurgy and Solidification Microstructure Control of Fusion-Based Additive Manufacturing Fabricated Metallic Alloys:A Review

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 29-53页

作者： Qiang Li Xing-Ran Li Bai-Xin Dong Xiao-Long Zhang shi-Li shu Feng Qiu Lai-Chang Zhang Zhi-Hui Zhang Key Laboratory of Bionic Engineering(Ministry of Education) and College of Bionic Science and EngineeringJilin UniversityChangchun130022China Institute of Structured and Architected Materials Liaoning Academy of MaterialsShenyang110167China Key Laboratory of Automobile Materials Ministry of Education and Department of Materials Science and EngineeringJilin UniversityChangchun130025China School of Mechanical and Aerospace Engineering Jilin UniversityChangchun130025China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

The metal-based additive manufacturing(AM),also referred to as metal 3D printing,has drawn particular interest because it enables direct creation,aided by computationally-directed path design,of intricate components with site-specific compositions and geometrical requirements as well as low buy-to-fly *** the last two decades,the objective of this revolutionary technology has been shifting from only“rapid prototyping”to advanced manufacturing of special high-end products or devices,which,in many aspects,outperform conventional manufacturing *** fusion-based AM,significant progress has been achieved in understanding the processing window of macroscopic scales,non-equilibrium metallurgy of mesoscale scales,and grain evolution of microscopic *** the versatile capacity of AM facilitates new avenues for discovering advanced materials and structures,their potential has still not been fully *** the unique non-equilibrium solidification during the AM process,coarse columnar grains with strong textures are usually developed along the build direction,which downgrades the mechanical *** push the limits of this digital manufacturing,this review attempts to provide in-depth and comprehensive overviews of the recent progress in understanding the evolution and control of the as-built microstructure that has been made recently and the challenges encountered during the AM process.

关键词： Additive manufacturing Temperature field Microstructure control Nanoparticles Functionally graded materials