33 research outputs found

    Well-defined PE-b-PTFE diblock copolymers via combination of coordination chain transfer polymerization and condensation reaction: Facile preparation and surface modification of polyethylene film

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    In this paper, a series of well-defined polyethylene-b-polytetrafluoroethylene diblock copolymers (PE–b– PTFEs) were prepared by a coupling reaction of hydroxyl-terminated polyethylene (PE–OH) and isocyanateterminated 1H,1H-perfluoro-1-tetradecanol (PFDO–NCO). PE–OH was prepared by the coordination chain transfer polymerization using 2,6-bis[1-(2,6-diisopropylphenyl)imino ethyl] pyridine iron (II) dichloride /dry ethylaluminoxane/ZnEt2 as catalyst and subsequent in situ oxidation with oxygen. PFDO–NCO was synthesized through the condensation reaction of 1H,1H- perfluoro-1-tetradecanol (PFDO) with isophoronediisocyanate (IPDI). Subsequently, the thermal characterization and the application of these diblock copolymers were investigated. The relationship between the molecular structure and the properties was disclosed. The results indicated that the diblock copolymers were effective surface modification agents for linear low density polyethylene (LLDPE). After that the PE–b–PTFE being spin-coated onto the surface of LLDPE film, the film was dramatically turned into a superhydrophobic film with a water contact angle as high as 151.4º. This kind of film is potential to be used as selfcleaning, anti-icing and anticorrosion material

    Acute Effects of Particulate Air Pollution on Ischemic Heart Disease Hospitalizations in Shanghai, China

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    Background: Air pollution has been demonstrated to be a major risk factor for the development of cardiovascular and respiratory diseases worldwide. This study examines the relationship between the exposure to fine particulate matter (PM) and patient hospitalizations as a result of ischemic heart disease (IHD) during 2013–2014 in Shanghai, China. Methods: Daily IHD hospitalization data were acquired from the Shanghai Health Insurance Bureau (SHIB) from 1 January 2013 to 21 December 2014. Daily average concentrations of air pollution as well as meteorological data were obtained from the database of Shanghai Environmental Monitoring Center (SEMC) during the same time period, and all data were analyzed using standard epidemiological methodology. Generalized linear model (GLM) adjusted for time trends, weather conditions, and medical insurance policy was used to estimate the immediate and delayed effects of PMs on IHD hospitalizations, and the effects of PMs were also examined based on gender, age group and seasonal variation. Results: A total of 188,198 IHD hospitalizations were recorded during 2013–2014 in Shanghai, China. During this period, the average concentrations of the fine particulate matter with aerodynamic diameter of <10 μm (PM10) and ≤2.5 (PM2.5) were 76 µg/m3 and 56.3 µg/m3, respectively. The effect of PMs was strongest on days when a 10 μg/m3 increment increase of PM2.5 and PM10, which coincided with an increase in IHD hospitalizations by 0.25% (95% CI: 0.10%, 0.39%) and 0.57% (95% CI: 0.46%, 0.68%), respectively. Furthermore, the effect of PMs was significantly greater in males and people between 41 and 65 years old. Conclusions: Hospitalizations of IHD was strongly associated with short-term exposure to high levels of PM10 and PM2.5 during 2013–2014 in Shanghai, China

    The Biogeography of Coelurosaurian Theropods and Its Impact on Their Evolutionary History

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    The Coelurosauria are a group of mostly feathered theropods that gave rise to birds, the only dinosaurians that survived the Cretaceous-Paleogene extinction event and are still found today. Between their first appearance in the Middle Jurassic up to the end Cretaceous, coelurosaurians were party to dramatic geographic changes on the Earth’s surface, including the breakup of the supercontinent Pangaea, and the formation of the Atlantic Ocean. These plate tectonic events are thought to have caused vicariance or dispersal of coelurosaurian faunas, influencing their evolution. Unfortunately, few coelurosaurian biogeographic hypotheses have been supported by quantitative evidence. Here, we report the first, broadly sampled quantitative analysis of coelurosaurian biogeography using the likelihood-based package BioGeoBEARS. Mesozoic geographic configurations and changes are reconstructed and employed as constraints in this analysis, including their associated uncertainties. We use a comprehensive time-calibrated coelurosaurian evolutionary tree produced from the Theropod Working Group phylogenetic data matrix. Six biogeographic models in the BioGeoBEARS package with different assumptions about the evolution of spatial distributions are tested against geographic constraints. Our results statistically favor the DIVALIKE+J and DEC+J models, which allow vicariance and founder events, supporting continental vicariance as an important factor in coelurosaurian evolution. Ancestral range estimation indicates frequent dispersal events via the Apulian route (connecting Europe and Africa during the Early Cretaceous) and the Bering land bridge (connecting North America and Asia during the Late Cretaceous). These quantitative results are consistent with commonly inferred Mesozoic dinosaurian dispersals and continental-fragmentation-induced vicariance events. In addition, we recognize the importance of Europe as a dispersal center and gateway in the Early Cretaceous, as well as other vicariance events such as those triggered by the disappearance of land bridges

    Acute Effects of Particulate Air Pollution on Ischemic Heart Disease Hospitalizations in Shanghai, China

    No full text
    Background: Air pollution has been demonstrated to be a major risk factor for the development of cardiovascular and respiratory diseases worldwide. This study examines the relationship between the exposure to fine particulate matter (PM) and patient hospitalizations as a result of ischemic heart disease (IHD) during 2013–2014 in Shanghai, China. Methods: Daily IHD hospitalization data were acquired from the Shanghai Health Insurance Bureau (SHIB) from 1 January 2013 to 21 December 2014. Daily average concentrations of air pollution as well as meteorological data were obtained from the database of Shanghai Environmental Monitoring Center (SEMC) during the same time period, and all data were analyzed using standard epidemiological methodology. Generalized linear model (GLM) adjusted for time trends, weather conditions, and medical insurance policy was used to estimate the immediate and delayed effects of PMs on IHD hospitalizations, and the effects of PMs were also examined based on gender, age group and seasonal variation. Results: A total of 188,198 IHD hospitalizations were recorded during 2013–2014 in Shanghai, China. During this period, the average concentrations of the fine particulate matter with aerodynamic diameter of <10 μm (PM10) and ≤2.5 (PM2.5) were 76 µg/m3 and 56.3 µg/m3, respectively. The effect of PMs was strongest on days when a 10 μg/m3 increment increase of PM2.5 and PM10, which coincided with an increase in IHD hospitalizations by 0.25% (95% CI: 0.10%, 0.39%) and 0.57% (95% CI: 0.46%, 0.68%), respectively. Furthermore, the effect of PMs was significantly greater in males and people between 41 and 65 years old. Conclusions: Hospitalizations of IHD was strongly associated with short-term exposure to high levels of PM10 and PM2.5 during 2013–2014 in Shanghai, China
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