14 research outputs found

    Fugitive emissions in Moravian-Silesian Region

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    Import 22/07/2015Predlo┼żen├í pr├íca sa zaober├í fugit├şvnymi emisiami na ├║zem├ş priemyselnej aglomer├ície Ostravska. Fugit├şvny prach predstavuje hlavn├║ ─Źas┼ą atmosf├ęrick├Żch aeros├│lov, zv├Ż┼íen├í pozornos┼ą je mu venovan├í kv├┤li v├Żznamn├Żm dopadom na zmenu kl├şmy, kvalitu ovzdu┼íia a zdravie ─żud├ş a ekosyst├ęmov. Hlavn├í ─Źas┼ą pr├íce je venovan├í ┼ít├║diu vertik├ílnej distrib├║cie PM1 vo v├Ż┼íke a┼ż 500 m n. m., ktor├í bola sledovan├í vo vybran├Żch lokalit├ích Ostravy v jarnom a letnom obdob├ş 2014, za pou┼żitia met├│dy merania bal├│nom. Pozornos┼ą bola venovan├í z├ívislosti koncentr├ície PM1 na v├Ż┼íke a meteorologick├Żch podmienkach. ─Äalej bolo zis┼ąovan├ę rozlo┼żenie organick├Żch l├ítok vo vertik├ílnych profiloch atmosf├ęry v najza┼ąa┼żenej┼í├şch miestach Ostravy pou┼żit├şm met├│dy Py-GC/MS a pomocou matematick├Żch met├│d boli identifikovan├ę pr├şspevky zdrojov zne─Źistenia.This thesis deals with the topic of fugitive emissions in the industrial agglomeration of Ostrava region. Fugitive dust is a major part of atmospheric aerosols, increased attention is given to it due to its significant impact on climate change, air quality and human health, and ecosystems. The main part is focused on the study of the vertical distribution of PM1 of up to 500 m a. s. l. which was monitored at selected locations during spring and summer seasons of 2014 using the balloon measuring method. Attention was given to influence of meteorological parameters on PM1 concentrations. Furthermore, distribution of organic matter in the vertical profiles of the atmosphere in the most exposed places was studied using the Py-GC/MS and, using the mathematical methods, contributions of the sources of pollution were identified.Prezen─Źn├ş546 - Institut environment├íln├şho in┼żen├Żrstv├şv├Żborn

    <i>In Situ</i> TEM on the Reversibility of Nanosized Sn Anodes during the Electrochemical Reaction

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    Excellent reversibility is crucial for the storage capacity and the cycle life of anode materials in high-performance lithium ion batteries, which has not been observed in alloy-type materials such as Si or Ge. <i>In situ</i> transmission electron microscopy reveals a sequential phase transformation in individual Sn nanowires during Li insertion, which is in a reverse order during Li extraction. Both the bright field image and the electron diffraction show a two-step reversible crystallineÔÇôcrystalline phase transformation. It is noted that the crystalline tin has a more open lattice to readily accommodate Li up to the Li<sub>2</sub>Sn<sub>5</sub> phase while retaining the crystallinity, which distinguishes Sn from its metalloid counterparts. The connected interstices along [001] inside lattice form a helix pipe for fast Li diffusion, indicating the openness of the Sn lattice. The <i>ab initio</i> simulations reveal facile Li diffusion along [001] with a low migration barrier of 0.014 eV. No phase boundary is visible in this step. In the second step, the Li<sub><i>x</i></sub>Sn<sub><i>y</i></sub> phases, including the Li<sub>22</sub>Sn<sub>5</sub> phase, nucleated with grain refinement and enormous volume expansion. The broaden phase boundary indicates that the further alloying is rate-limited not by the diffusion of Li but by the interfacial conversion reaction. The pulverization occurs during delithiation by agglomeration of regular-shape voids, showing a different mechanism from the cracking-dominated fracture in Si. These results elucidate the structural evolution and the phase transformation during the electrochemical cycling, which sheds light on engineering Sn anode materials

    Atomic Bonding between Metal and Graphene

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    To understand structural and chemical properties of metalÔÇôgraphene composites, it is crucial to unveil the chemical bonding along the interface. We provide direct experimental evidence of atomic bonding between typical metal nano structures and graphene, agreeing well with density functional theory studies. Single Cr atoms are located in the valleys of a zigzag edge, and few-atom ensembles preferentially form atomic chains by self-assembly. Low migration barriers lead to rich dynamics of metal atoms and clusters under electron irradiation. We demonstrate no electron-instigated interaction between Cr clusters and pristine graphene, though Cr has been reported to be highly reactive to graphene. The metal-mediated etching is a dynamic effect between metal clusters and pre-existing defects. The resolved atomic configurations of typical nano metal structures on graphene offer insight into modeling and simulations on properties of metal-decorated graphene for both catalysis and future carbon-based electronics

    Atomic Bonding between Metal and Graphene

    No full text
    To understand structural and chemical properties of metalÔÇôgraphene composites, it is crucial to unveil the chemical bonding along the interface. We provide direct experimental evidence of atomic bonding between typical metal nano structures and graphene, agreeing well with density functional theory studies. Single Cr atoms are located in the valleys of a zigzag edge, and few-atom ensembles preferentially form atomic chains by self-assembly. Low migration barriers lead to rich dynamics of metal atoms and clusters under electron irradiation. We demonstrate no electron-instigated interaction between Cr clusters and pristine graphene, though Cr has been reported to be highly reactive to graphene. The metal-mediated etching is a dynamic effect between metal clusters and pre-existing defects. The resolved atomic configurations of typical nano metal structures on graphene offer insight into modeling and simulations on properties of metal-decorated graphene for both catalysis and future carbon-based electronics

    Atomic Bonding between Metal and Graphene

    No full text
    To understand structural and chemical properties of metalÔÇôgraphene composites, it is crucial to unveil the chemical bonding along the interface. We provide direct experimental evidence of atomic bonding between typical metal nano structures and graphene, agreeing well with density functional theory studies. Single Cr atoms are located in the valleys of a zigzag edge, and few-atom ensembles preferentially form atomic chains by self-assembly. Low migration barriers lead to rich dynamics of metal atoms and clusters under electron irradiation. We demonstrate no electron-instigated interaction between Cr clusters and pristine graphene, though Cr has been reported to be highly reactive to graphene. The metal-mediated etching is a dynamic effect between metal clusters and pre-existing defects. The resolved atomic configurations of typical nano metal structures on graphene offer insight into modeling and simulations on properties of metal-decorated graphene for both catalysis and future carbon-based electronics

    H<sub>2</sub>O<sub>2</sub> sensitivity in <i>D. radiodurans</i> and <i>E. coli</i> treated with DNA fragments or dNMPs.

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    <p>(A) Sensitivity of <i>D. radiodurans</i> to H<sub>2</sub>O<sub>2</sub> after the addition of 3.6 mg/ml DNA fragments or dNMPs. (B) Sensitivity of <i>E. coli</i> K-12 to H<sub>2</sub>O<sub>2</sub> after the addition of 3.6 mg/ml DNA fragments or dNMPs. Each data point represents the mean┬▒SD of three replicates. R1, <i>D. radiodurans</i> wild type strain.</p

    H<sub>2</sub>O<sub>2</sub> sensitivity in <i>D. radiodurans</i> treated with dAMP, dTMP, dCMP or dGMP.

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    <p>Sensitivity of <i>D. radiodurans</i> to 50 mM H<sub>2</sub>O<sub>2</sub> with the addition of DNA fragments (3.6 mg/ml), dNMPs, dAMP, dTMP, dCMP or dGMP (10 mM for each). Each data point represents the mean┬▒SD of three replicates. R1, <i>D. radiodurans</i> wild type strain.</p

    Addition of extracellular dGMP increases the activity of KatA in <i>D. radiodurans</i>.

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    <p>(A) Extracellular dGMP (2.5 mM) increased the activity of KatA, but not KatB. (B) Extracellular dGMP (2.5 mM) had no effect on the activity of SOD. (C) and (D) Quantification of the intensity of bands was performed using ImageJ. Each sample contains 80 ┬Ág of total protein. Values are the mean ┬▒ standard deviation of three independent measurements. R1, <i>D. radiodurans</i> wild type strain; KatA, catalase A; KatB, catalase B.</p

    Changes in Birth Weight between 2002 and 2012 in Guangzhou, China

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    <div><p>Background</p><p>Recent surveillance data suggest that mean birth weight has begun to decline in several developed countries. The aim of this study is to examine the changes in birth weight among singleton live births from 2002 to 2012 in Guangzhou, one of the most rapidly developed cities in China.</p><p>Methods</p><p>We used data from the Guangzhou Perinatal Health Care and Delivery Surveillance System for 34108 and 54575 singleton live births with 28ÔÇô41 weeks of gestation, who were born to local mothers, in 2002 and 2012, respectively. The trends in birth weight, small (SGA) and large (LGA) for gestational age and gestational length were explored in the overall population and gestational age subgroups.</p><p>Results</p><p>The mean birth weight decreased from 3162 g in 2002 to 3137 g in 2012 (crude mean difference, Ôłĺ25 g; 95% CI, Ôłĺ30 to Ôłĺ19). The adjusted change in mean birth weight appeared to be slight (Ôłĺ6 g from 2002 to 2012) after controlling for maternal age, gestational age, educational level, parity, newborn's gender and delivery mode. The percentages of SGA and LGA in 2012 were 0.6% and 1.5% lower than those in 2002, respectively. The mean gestational age dropped from 39.2 weeks in 2002 to 38.9 weeks in 2012. In the stratified analysis, we observed the changes in birth weight differed among gestational age groups. The mean birth weight decreased among very preterm births (28ÔÇô31 weeks), while remained relatively stable among other gestational age subcategories.</p><p>Conclusions</p><p>Among local population in Guangzhou from 2002 to 2012, birth weight appeared to slightly decrease. The percentage of SGA and LGA also simultaneously dropped, indicating that newborns might gain a healthier weight for gestational age.</p></div

    Maternal and newborn characteristics among singleton live births in 2002 and 2012.

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    <p>Data are expressed as mean ┬▒ standard deviation or n(%).</p><p>Maternal and newborn characteristics among singleton live births in 2002 and 2012.</p
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