Спекание таблеток диоксида урана в высокотемпературных печах

Бакалаврская работа посвящена изучению современных подходов к производству топливных таблеток для снаряжения тепловыделяющих элементов и сборок. Основное внимание обращено процессам спекания спрессованных из порошка диоксида урана топливных таблеток в высокотемпературных печах, проходящих в атмосфере водорода. В процессе выполнения работы изучена программа - «Инженерная модель спекания в печах BTU», разработанная в НИИ прикладной математики и механики Томского государственного университета. Программа предназначена для получения прогноза по спеканию топливных таблеток диоксида урана по входным данным, полученным после прессования. После ознакомления с программой проведены расчеты. Целью данной работы является освоение современных подходов к спеканию топливных таблеток из порошка диоксидаBachelor's work is devoted to the study of contemporary approaches to the production of fuel pellets Equipment for the fuel rods and assemblies. Emphasis sintering processes drawn from the compacted powder of uranium dioxide fuel pellets in high temperature furnaces, passing under a hydrogen atmosphere. In carrying out the work program studied - "Engineering model sintering furnaces BTU», developed at the Institute of Applied Mathematics and Mechanics of Tomsk State University. The program is designed to provide forecast sintered uranium dioxide fuel pellets from the input data obtained after compression. After getting acquainted with the program were calculated. The aim of this work is the development of modern approaches to the sintering of fuel pellets of uranium dioxide ceramic powde

Myoglobin: A scavenger of bioactive NO

The present study explored the role of myoglobin (Mb) in cardiac NO homeostasis and its functional relevance by employing isolated hearts of wild-type (WT) and myoglobin knockout mice. (1)H NMR spectroscopy was used to measure directly the conversion of oxygenated Mb (MbO(2)) to metmyoglobin (metMb) by reaction with NO. NO was applied intracoronarily (5 nM to 25 μM), or its endogenous production was stimulated with bradykinin (Bk; 10 nM to 2 μM). We found that infusion of authentic NO solutions dose-dependently (≥ 2.5 μM NO) increased metMb formation in WT hearts that was rapidly reversible on cessation of NO infusion. Likewise, Bk-induced release of NO was associated with significant metMb formation in the WT (≥1 μM Bk). Hearts lacking Mb reacted more sensitively to infused NO in that vasodilatation and the cardiodepressant actions of NO were more pronounced. Similar results were obtained with Bk. The lower sensitivity of WT hearts to changes in NO concentration fits well with the hypothesis that in the presence of Mb, a continuous degradation of NO takes place by reaction of MbO(2) + NO to metMb + NO(3)(−), thereby effectively reducing cytosolic NO concentration. This breakdown protects myocytic cytochromes against transient rises in cytosolic NO. Regeneration of metMb by metMb reductase to Mb and subsequent association with O(2) leads to reformation of MbO(2) available for another NO degradation cycle. Our data indicate that this cycle is crucial in the breakdown of NO and substantially determines the dose–response curve of the NO effects on coronary blood flow and cardiac contractility

Myocardial proteome analysis reveals reduced NOS inhibition and enhanced glycolytic capacity in areas of low local blood flow

In the heart, in situ local myocardial blood flow (MBF) varies greater than 10-fold between individual areas and displays a spatially heterogeneous pattern. To analyze its molecular basis, we analyzed protein expression of low and high flow samples (300 mg, 150% of mean MBF, each n=30) of six beagle dogs by 2-D polyacrylamide gel electrophoresis (380 +/- 78 spots/gel). In low flow samples, dimethylarginine dimethylaminohydrolase (DDAH1) was increased greatly (+377%, compared with high flow samples). This increase resulted in a 75% reduction of asymmetric dimethylarginine (ADMA), the potent endogenous inhibitor of NO synthase, whereas eNOS showed no difference. Low flow samples exhibited enhanced expression of GAPDH (+89%) and phosphoglycerate kinase (+100%), whereas hydroxyacyl-CoA dehydrogenase, electron transfer flavoprotein, myoglobin, and desmin were decreased. Assessing local MBF on different days within 2 weeks revealed a high degree of MBF stability (r2 > 0.79). Thus, stable differences in local MBF are associated with significant differences in local gene and protein expression. In low flow areas, the increased DDAH1 reduces ADMA concentration and NOS inhibition, which strongly suggests enhanced NO formation. Low flow areas are also characterized by a higher glycolytic and a lower fatty acid oxidation capacity. Both the shift in substrate utilization and the rise in NO may contribute to the known lower oxygen consumption in these area