259 research outputs found

    Description of radiation conditions and evaluation of the date of <sup>137</sup>Cs release to the atmosphere using the radionuclide transfer model coupled with the forecasts by the mesoscale hydrodynamic model

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    Ā© 2016, Allerton Press, Inc.The estimates of 137Cs emissions from the accident happened in Elektrostal at the beginning of April 12, 2013 are presented. The transport of radionuclides and their dry and wet deposition on the surface are computed using the Lagrangian stochastic model of the NOSTRADAMUS software package worked out by Nuclear Safety Institute of Russian Academy of Sciences. Prognostic fields of wind (horizontal and vertical components) in the lower troposphere, precipitation, and vertical and horizontal turbulence diffusivity coefficients in the lower atmosphere (up to 4 km) were used as input data. Prognostic fields were obtained using the WRF-ARW numerical mesoscale model

    Insights into the ceria-catalyzed ketonization reaction for biofuels applications

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    The ketonization of small organic acids is a valuable reaction for biorenewable applications. Ceria has long been used as a catalyst for this reaction; however, under both liquid and vapor phase conditions, it was found that given the right temperature regime of about 150-300 Ā°C, cerium oxide, which was previously believed to be a stable catalyst for ketonization, can undergo bulk transformations. This result, along with other literature reports, suggest that the long held belief of two separate reaction pathways for either bulk or surface ketonization reactions are not required to explain the interaction of cerium oxide with organic acids. X-ray photon spectroscopy, scanning electron microscopy, and temperature programmed decomposition results supported the formation of metal acetates and explained the occurrence of cerium reduction as well as the formation of cerium oxide/acetate whiskers. After thermogravimetry/mass spectrometry and FT-IR experiments, a single reaction sequence is proposed that can be applied to either surface or bulk reactions with ceria

    Contrast-enhancement cardiac magnetic resonance imaging beyond the scope of viability

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    The clinical applications of cardiovascular magnetic resonance imaging with contrast enhancement are expanding. Besides the direct visualisation of viable and non-viable myocardium, this technique is increasingly used in a variety of cardiac disorders to determine the exact aetiology, guide proper treatment, and predict outcome and prognosis. In this review, we discuss the value of cardiovascular magnetic resonance imaging with contrast enhancement in a range of cardiac disorders, in which this technique may provide insights beyond the scope of myocardial viability

    Assessment of coronary artery disease and calcified coronary plaque burden by computed tomography in patients with and without diabetes mellitus

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    Purpose: To compare the coronary atherosclerotic burden in patients with and without type-2 diabetes using CT Coronary Angiography (CTCA). Methods and Materials: 147 diabetic (mean age: 65 Ā± 10 years; male: 89) and 979 nondiabetic patients (mean age: 61 Ā± 13 years; male: 567) without a history of coronary artery disease (CAD) underwent CTCA. The per-patient number of diseased coronary segments was determined and each diseased segment was classified as showing obstructive lesion (luminal narrowing >50%) or not. Coronary calcium scoring (CCS) was assessed too. Results: Diabetics showed a higher number of diseased segments (4.1 Ā± 4.2 vs. 2.1 Ā± 3.0; p 400 (p < 0.001), obstructive CAD (37% vs. 18% of patients; p < 0.0001), and fewer normal coronary arteries (20% vs. 42%; p < 0.0001), as compared to nondiabetics. The percentage of patients with obstructive CAD paralleled increasing CCS in both groups. Diabetics with CCS ā‰¤ 10 had a higher prevalence of coronary plaque (39.6% vs. 24.5%, p = 0.003) and obstructive CAD (12.5% vs. 3.8%, p = 0.01). Among patients with CCS ā‰¤ 10 all diabetics with obstructive CAD had a zero CCS and one patient was asymptomatic. Conclusions: Diabetes was associated with higher coronary plaque burden. The present study demonstrates that the absence of coronary calcification does not exclude obstructive CAD especially in diabetics

    Coronary artery calcium screening: current status and recommendations from the European Society of Cardiac Radiology and North American Society for Cardiovascular Imaging

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    Current guidelines and literature on screening for coronary artery calcium for cardiac risk assessment are reviewed for both general and special populations. It is shown that for both general and special populations a zero score excludes most clinically relevant coronary artery disease. The importance of standardization of coronary artery calcium measurements by multi-detector CT is discussed
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