Explore the vast range of titles available.

Using the three-dimensional linearized theory of stability and piecewise-homogeneous medium model, this study has investigated near-surface buckling in the laminated composite materials, as well as local buckling in the vicinity of interlayer macrocracks. The effects of macrocrack size and position on critical loads and buckling modes have been thoroughly analyzed. It has been demonstrated that, as the macrocrack size increases reaching a certain value, the near-surface buckling mode abruptly changes over to local buckling. To solve the problem numerically, a mesh-based method and a modified variational-difference approach have been applied. A computational experiment has been conducted using both sequential and parallel implementations of the Cholesky method to solve the resulting system of linear algebraic equations, as well as the subspace iteration method to solve the generalized eigenvalue problem.

The growth of many tumors is known to induce iron and zinc deficiency in the body. Here, we studied the tissue content of iron and zinc, as well as the specific activity of two antioxidant metalloenzymes, catalase (CAT) and superoxide dismutase (SOD), in three distant organs (thymus, liver and spleen) of mice bearing transplantable hepatoma 22a. The revealed alterations in the metal content were compared to changes in organ weights. On day 21 of tumor growth, the non-heme iron content was decreased in all three organs, while that of zinc in the thymus only, as compared to controls. CAT and SOD specific activities were increased in the thymus, while SOD activity was decreased in the liver. At the same time point, thymic involution and splenomegaly were observed to develop. In an attempt to normalize metal content, hepatoma 22a-bearing mice were supplemented with zinc sulfate (22 µg/mL in drinking water) for 3 weeks. Zinc sulfate supplementation partly compensated for zinc deficiency in the thymus, increased zinc content in the liver, and restored iron content in all three organs. It also normalized SOD activity in the liver, while having no effect on both enzymes in other organs. Zinc supplementation did not influence splenic and hepatic weights, but prevented the development of thymic involution. At the same time, the deficiency of both metals in the thymus was restored, while the activity of antioxidant enzymes remained unchanged. It was concluded that thymic involution during hepatoma 22a growth in mice was due to iron and zinc deficiency in this organ, but not to the activity of antioxidant enzymes, whereas splenomegaly was not associated with either. Thus, zinc sulphate exerts a positive effect on metabolism of two vital trace elements, zinc and iron, in mice bearing hepatoma 22a, preserving the thymus as a central immune organ and, at the same time, improving the antioxidant system of the liver.

Мета. Обгрунтування методики моделювання опускання земно! поверхш при îî шдробщ очисними роботами на шахтах Захщного Донбасу, що дозволяе розробити автоматизовану систему визначення зон i обсяпв затоплення поверхш землi для мшшгзацп пдроекологшних ризиюв при закрит шахт Захщного Донбасу. Методика. У данш робот обгрунтовуеться методика моделювання процеив осщання земно! поверхш, що дозволяе визначати плошд й обсяги затоплено! поверхш. Для цього розглянул два типи моделей побудови поверхонь ш регулярною слкою: штерполяцшна й полшомь альна. Даш моделi дозволяють отримати адекватне уявлення поверхонь, а також е базисом для пщрахунку обсяпв, представлених у виглядi суми елементарних призм по кожному вузлу сгтки. Результата. Розроблений математичний i алгоритмшний апарат дозволив створити ефективш моделi земно! поверхш та водоносного горизонту, а також пщрахувати обсяги зон мгж вихщною земною поверхнею та ось лою, а також мгж водоносним горизонтом i осшою поверхнею для визначення площ i обсяпв зон дшянок затоплення. Наукова новизна. Полягае в обгрунтуванш методики моделювання процеив осщання земно! поверхш для мь ншгзацп пдроекологшних ризиюв при л^гдацп вугшьних шахт. Практична значишсть. Полягае в розробцi апаратного та програмного комплексу для забезпечення ефективного моделювання ошдання земно! поверхш при вщпрацюваннi вугшьних пластiв, а також для зменшення похибок при пщрахунку обсягу зон затоплено! поверхш.