A Study of Temperature Effect on the Rayleigh Velocity of Superconductor Material Type Bi2212 Using Acoustic Techniques

In the present work, the effect of the temperature on Rayleigh velocity VRVR of superconductor material type Bi2212 is studied, focusing on the modelling of both the reflection coefficient RR(θθ) and the acoustic signature VV(zz). Consequently, the study allows us to deduct the velocities of the acoustic waves of surface and volume, following their evolution as functions of temperature. The study is carried out in case of porous and non-porous superconductor material type Bi2212 in a temperature range from 10 to 295 K and with work frequency of 600 MHz. This modelling study is based on experimental results obtained on porous and non-porous Bi2212 superconducting materials in the temperature range of 10 to 295 K at a frequency of 600 MHz.В данной работе изучалось влияние температуры на скорость Рэлея VRVR сверхпроводникового материала типа Bi2212, сосредоточиваясь на моделировании коэффициента отражения RR(θθ) и акустической характеристики VV(zz). Исследование позволяет рассчитать скорости поверхностной и объёмной акустических волн, следуя их эволюции в зависимости от температуры. Исследование проводилось для случая пористого и непористого сверхпроводника типа Bi2212 при температуре от 10 до 295 К и рабочей частоте 600 МГц. Такое моделирование основано на экспериментальных результатах, полученных на пористых и непористых сверхпроводящих материалах Bi2212 в диапазоне температур от 10 до 295 К на частоте 600 МГц.У даній роботі досліджено вплив температури на Релейову швидкість VRVR надпровідного матеріялу типу Bi2212, зосереджуючись на моделюванні коефіцієнта відбиття RR(θθ) та акустичної характеристики VV(zz). Дослідження уможливлює вирахувати швидкості поверхневої й об’ємної акустичних хвиль за їхньою еволюцією, залежно від температури. Дослідження проводилося для випадку пористого та непористого надпровідникового матеріялу типу Bi2212 за температури від 10 до 295 К та робочої частоти у 600 МГц. Таке моделювання базувалося на експериментальних результатах, одержаних на пористих і непористих надпровідних матеріялах Bi2212 в діяпазоні температур від 10 до 295 К за частоти у 600 МГц

Genome-wide association meta-analysis of spontaneous coronary artery dissection identifies risk variants and genes related to artery integrity and tissue-mediated coagulation

Spontaneous coronary artery dissection (SCAD) is an understudied cause of myocardial infarction primarily affecting women. It is not known to what extent SCAD is genetically distinct from other cardiovascular diseases, including atherosclerotic coronary artery disease (CAD). Here we present a genome-wide association meta-analysis (1,917 cases and 9,292 controls) identifying 16 risk loci for SCAD. Integrative functional annotations prioritized genes that are likely to be regulated in vascular smooth muscle cells and artery fibroblasts and implicated in extracellular matrix biology. One locus containing the tissue factor gene F3, which is involved in blood coagulation cascade initiation, appears to be specific for SCAD risk. Several associated variants have diametrically opposite associations with CAD, suggesting that shared biological processes contribute to both diseases, but through different mechanisms. We also infer a causal role for high blood pressure in SCAD. Our findings provide novel pathophysiological insights involving arterial integrity and tissue-mediated coagulation in SCAD and set the stage for future specific therapeutics and preventions

Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993-2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTISD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTISD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTISD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming

Palladium-alloy membrane reactors for fuel reforming and hydrogen production: Hydrogen Production Modeling

Endeavors have recently been concentrated on minimizing the dependency on fossil fuels in order to mitigate the ever-increasing problem of greenhouse gas (GHG) emissions. Hydrogen energy is regarded as an alternative to fossil fuels due to its cleaner emission attributes. Reforming of hydrocarbon fuels is amongst the most popular and widely used methods for hydrogen production. Hydrogen produced from reforming processes requires additional processes to separate from the reformed gases. In some cases, further purification of hydrogen has to be carried out to use the hydrogen in power generation applications. Metallic membranes, especially palladium (Pd)-based ones, have demonstrated sustainable hydrogen separation potential with around 99.99% hydrogen purity. Comprehensive and critical research investigations must be performed to optimize membrane-assisted reforming as well as to maximize the production of hydrogen. The computational fluid dynamic (CFD) can be an excellent tool to analyze and visualize the flow/reaction/permeation mechanisms at a lower cost in contrast with the experiments. In order to provide the necessary background knowledge on membrane reactor modeling, this study reviews, summarizes and analyses the kinetics of different fuel reforming processes, equations to determine hydrogen permeation, and lastly, various geometry and operating condition adopted in the literature associated with membrane-reactor modeling works. It is indicated that hydrogen permeation through Pd-membranes depends highly on the difference in hydrogen pressure. It is found that hydrogen permeation can be improved by employing different pressure configuration, introducing sweep flow on the permeate side of the membrane, reducing retentate side flow rate, and increasing the temperature