1,804 research outputs found

    Epitaxial (111) Films of Cu, Ni, and CuxNi_xNi_yonαAl on {\alpha}-Al_2OO_3$(0001) for Graphene Growth by Chemical Vapor Deposition

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    Films of (111)-textured Cu, Ni, and Cux_xNiy_y were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of α\alpha-Al2_2O3_3(0001) at temperatures of 250 C to 650 C. The films were then annealed at 1000 C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by 6060^{\circ}. The in-plane epitaxial relationship for all films was [110]metal[110]_{metal}||[101ˉ0]Al2O3[10\bar{1}0]_{{Al}_{2}{O}_{3}}. Reactive sputtering of Al in O2_2 before metal deposition resulted in a single in-plane orientation over 97 % of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al2_2O3_3 interface, confirmed the epitaxial relationship, and showed that formation of the 6060^{\circ} twin grains was associated with features on the Al2_2O3_3 surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and and Cux_xNiy_y films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO2_2 films, but still showed thickness variations on a much smaller length scale than the distance between grains

    Classical model for laser‐induced nonadiabatic collision processes

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    By synthesizing earlier work of Orel and Miller and of Meyer, McCurdy, and Miller, a model for describing laser-induced electronically non-adiabatic collision processes is constructed which treats all degrees of freedom -- heavy particle (i.e,, translation, rotation, and vibration), electronic, and photon by classical mechanics. This then makes it relatively easy to carry out calculations to simulate such processes within a dynatnically consistent framework. Application is made to the test case H + LiF {yields} Li + HF reaction considered by Light and Altenberger-Siczek. The most interesting feature revealed by these classical calculations is maxima in the reaction probability as a function of initial translational energy at energies below the laser-free threshold. It is seen that this structure can be understood as a Franck-Condon-like effect

    Pandemic Paradox: Early Life H2N2 Pandemic Influenza Infection Enhanced Susceptibility to Death during the 2009 H1N1 Pandemic.

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    Recent outbreaks of H5, H7, and H9 influenza A viruses in humans have served as a vivid reminder of the potentially devastating effects that a novel pandemic could exert on the modern world. Those who have survived infections with influenza viruses in the past have been protected from subsequent antigenically similar pandemics through adaptive immunity. For example, during the 2009 H1N1 "swine flu" pandemic, those exposed to H1N1 viruses that circulated between 1918 and the 1940s were at a decreased risk for mortality as a result of their previous immunity. It is also generally thought that past exposures to antigenically dissimilar strains of influenza virus may also be beneficial due to cross-reactive cellular immunity. However, cohorts born during prior heterosubtypic pandemics have previously experienced elevated risk of death relative to surrounding cohorts of the same population. Indeed, individuals born during the 1890 H3Nx pandemic experienced the highest levels of excess mortality during the 1918 "Spanish flu." Applying Serfling models to monthly mortality and influenza circulation data between October 1997 and July 2014 in the United States and Mexico, we show corresponding peaks in excess mortality during the 2009 H1N1 "swine flu" pandemic and during the resurgent 2013-2014 H1N1 outbreak for those born at the time of the 1957 H2N2 "Asian flu" pandemic. We suggest that the phenomenon observed in 1918 is not unique and points to exposure to pandemic influenza early in life as a risk factor for mortality during subsequent heterosubtypic pandemics.IMPORTANCE The relatively low mortality experienced by older individuals during the 2009 H1N1 influenza virus pandemic has been well documented. However, reported situations in which previous influenza virus exposures have enhanced susceptibility are rare and poorly understood. One such instance occurred in 1918-when those born during the heterosubtypic 1890 H3Nx influenza virus pandemic experienced the highest levels of excess mortality. Here, we demonstrate that this phenomenon was not unique to the 1918 H1N1 pandemic but that it also occurred during the contemporary 2009 H1N1 pandemic and 2013-2014 H1N1-dominated season for those born during the heterosubtypic 1957 H2N2 "Asian flu" pandemic. These data highlight the heretofore underappreciated phenomenon that, in certain instances, prior exposure to pandemic influenza virus strains can enhance susceptibility during subsequent pandemics. These results have important implications for pandemic risk assessment and should inform laboratory studies aimed at uncovering the mechanism responsible for this effect

    The Lantern Vol. 26, No. 1, December 1957

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    • A Brazilian Dirge • Motion in Retrospect • The Power • The House on the Edge of the World • Twinkle, Twinkle, Little Star • Christmas at Ursinus • Grey Purple • A Woodland Idyll • Four Trees • Lifehttps://digitalcommons.ursinus.edu/lantern/1073/thumbnail.jp
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