3,808 research outputs found

    On the thermoelastic analysis of solar cell arrays and related material properties

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    Accurate prediction of failure of solar cell arrays requires accuracy in the computation of thermally induced stresses. This was accomplished by using the finite element technique. Improved procedures for stress calculation were introduced together with failure criteria capable of describing a wide range of ductile and brittle material behavior. The stress distribution and associated failure mechanisms in the N-interconnect junction of two solar cell designs were then studied. In such stress and failure analysis, it is essential to know the thermomechanical properties of the materials involved. Measurements were made of properties of materials suitable for the design of lightweight arrays: microsheet-0211 glass material for the solar cell filter, and Kapton-H, Kapton F, Teflon, Tedlar, and Mica Ply PG-402 for lightweight substrates. The temperature-dependence of the thermal coefficient of expansion for these materials was determined together with other properties such as the elastic moduli, Poisson's ratio, and the stress-strain behavior up to failure

    One-Mother Vertex Graphs

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    In this paper we will define a new type of graph. The idea of this definition is based on when we illustrate the cardiovascular system by a graph we find that not all vertices have the same important so we define this new graph and call it 1- mother vertex graph

    The solution of mixed integral equation of the first kind using toeplitz matrix method

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    In this work, the existence and uniqueness of the solution of mixed integral equation (MIE) of the first kind is considered in the  L2  *C[0,T], T<1 ,  is the domain of integration with respect to position and T is the time. Then, a numerical method is used to obtain a system of Fredholm integral equations (SFIE). The discontinuous kernel of the SFIE takes the form of Carleman function and logarithmic kernel. The existence and uniqueness of the solution SFIE can be proved. Moreover, Toeplitz matrix method (TMM) is used to obtain a linear algebraic system (LAS). The LAS is solved numerically, to get the eigenvalues and eigenfunctions of SFIE

    Can neutral and ionized PAHs be carriers of the UV extinction bump and the diffuse interstellar bands?

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    Up to now, no laboratory-based study has investigated polycyclic aromatic hydrocarbon (PAH) species as potential carriers of both the diffuse interstellar bands (DIBs) and the 2175 A UV bump. We examined the proposed correlation between these two features by applying experimental and theoretical techniques on two specific medium-sized/large PAHs (dibenzorubicene C30H14 and hexabenzocoronene C42H18) in their neutral and cationic states. It was already shown that mixtures of sufficiently large, neutral PAHs can partly or even completely account for the UV bump. We investigated how the absorption bands are altered upon ionization of these molecules by interstellar UV photons. The experimental studies presented here were realized by performing matrix isolation spectroscopy with subsequent far-UV irradiation. The main effects were found to be a broadening of the absorption bands in the UV combined with slight red shifts. The position of the complete pi - pi* absorption structure around 217.5 nm, however, remains more or less unchanged which could explain the observed position invariance of the interstellar bump for different lines of sight. This favors the assignment of this feature to the interstellar PAH population. As far as the DIBs are concerned, neither our investigations nor the laboratory studies carried out by other research groups support a possible connection with this class of molecules. Instead, there are reasonable arguments that neutral and singly ionized cationic PAHs cannot be made responsible for the DIBs.Comment: 11 pages, 7 figures, 1 tabl

    Ending Neglect of older people in the response to Humanitarian Emergencies

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    Older people make up a significant and growing number of those affected by humanitarian crises, yet they are often not sought out or prioritised within the humanitarian response. Humanitarian agencies, donors, and international bodies neglect older people's health and nutrition. The gaps in knowledge and research about the needs of older people in emergencies are considerable. Older people are not monitored in emergencies and they are not prioritised despite evidence of disproportionate mortality and morbidity in this group. We call for policy changes by humanitarian agencies and donors to ensure that the needs of this vulnerable group are met

    The 2.5-5.0 micron spectra of Io: Evidence for H2S and H2O frozen in SO2

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    The techniques of low temperature spectroscopy are applied to identify the constituents of the ices covering the surface of Io, a satellite of Jupiter. Infrared spectra of Io in the 4000-2000 cm exp -1 region, including new observational data, are analyzed using laboratory studies of plausible surface ices

    Ethoxyquin Inhibits the Progression of Murine Ehrlich Ascites Carcinoma through the Inhibition of Autophagy and LDH

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    Cancer cells exhibit an increased glycolysis rate for ATP generation (the Warburg effect) to sustain an increased proliferation rate. In tumor cells, the oxidation of pyruvate in the Krebs cycle is substituted by lactate production, catalyzed by LDH. In this study, we use ethoxyquin (EQ) as a novel inhibitor to target LDH in murine Ehrlich ascites carcinoma (EAC) and as a combination therapy to improve the therapeutic efficacy of the conventional chemotherapy drug, cisplatin (CIS). We investigated the anti-tumor effect of EQ on EAC-bearing mice and checked whether EQ can sustain the anti-tumor potential of CIS and whether it influences LDH activity. Treatment with EQ had evident anti-tumor effects on EAC as revealed by the remarkable decrease in the expression of the anti-apoptotic gene Bcl-2 and by a significant increase in the expression of apoptotic genes (BAX and caspase-3). EQ also caused a significant decrease in the autophagic activity of EAC cells, as shown by a reduction in the fluorescence intensity of the autophagosome marker. Additionally, EQ restored the altered hematological and biochemical parameters and improved the disrupted hepatic tissues of EAC-bearing mice. Co-administration of EQ and CIS showed the highest anti-tumor effect against EAC. Collectively, our findings propose EQ as a novel inhibitor of LDH in cancer cells and as a combinatory drug to increase the efficacy of cisplatin. Further studies are required to validate this therapeutic strategy in different cancer models and preclinical trials

    Photoinduced Fluorescence from the Perylene Cation Isolated in Ne and Ar Matrices

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    The fluorescence and fluorescence excitation spectra of the perylene cation isolated in neon and argon matrices are reported. This is the first report of the fluorescence spectrum of a polycyclic aromatic hydrocarbon ion in any phase

    Determination of Optical Constants for Titan Aerosol-, and Exoplanet and Brown Dwarf Cloud Particle Analogs from the Visible to the Far Infrared

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    Here we present optical constants covering a broad wavelength range, from the visible to the far infrared, for Titan aerosol analogs produced in the Titan Haze Simulation (THS) experiment at Ames COSmIC facility, as well as other exoplanet-relevant materials
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