3,657 research outputs found

    Modeling Heatshield Erosion Due to Dust Particle Impacts for a Martian Entry Vehicle

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    Because planetary missions to Mars take years from initial design to arrival at Mars, and because of the unpredictability of major global dust storms, the de-sign of the thermal protection system (TPS) of a Mars entry vehicle requires an estimation for the potential damage caused by dust particle impacts on the heat-shield. This paper will review previous analytical and experimental approaches to modeling dust particle ero-sion and will compare the legacy models against more modern computational techniques and new dust ero-sion models that will be based on upcoming experi-ments in the German Aerospace Center (DLR) GBK facility. The various models will be compared by incorporating them into the Icarus material response code applied to a representative vehicle entering the Martian atmosphere

    The determination of different effective concentration of ethanolic extract of bee pollen on biochemical analysis in liver, spleen and heart tissues of rainbow trout, Oncorhynchus mykiss (Walbaum, 1792)

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    The aim of this study was to investigate the effective concentration of ethanolic extract of bee pollen on liver, spleen and heart tissues of fish. Bee pollen extract in various concentrations (0.5, 2.5, 5, 10, 20 and 30 ppm) was administered to fish for 96 h under aquarium conditions. The malondialdehyde (MDA) levels, total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI) and levels of total free sulfhydryl groups were investigated in liver, spleen and heart in fish samples. MDA levels in liver, spleen and heart tissues of various concentration groups (2.5, 5, 10, 20 and 30 ppm) decreased (p<0.05) compared to the control group. The highest value of TAS (P<0.05) and the lowest value of TOS (p<0.05) occured in liver and heart tissues of 10 and 20 ppm concentration groups. The lowest levels of OSI were recorded in liver and heart tissues of 10, 20 and 30 ppm concentration groups compared to control group (p<0.05). The highest values of total sulfhydryl groups were recorded (p<0.05) in all tissues of 10 and 20 ppm groups compared with that in the control group. Finally it was observed that in liver, spleen and heart tissues of fish, the antioxidant effects of ethanolic extract of bee pollen depended on concentrations.Scientific Research Project Fund of Cumhuriyet University [F-380]This work was supported by the Scientific Research Project Fund of Cumhuriyet University under the Project number (F-380)

    Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

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    The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
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