Long-Wave Instability of Advective Flows in Inclined Layer with Solid Heat Conductive Boundaries

We investigate the stability of the steady convective flow in a plane tilted layer with ideal thermal conductivity of solid boundaries in the presence of uniform longitudinal temperature gradient. Analytically found the stability boundary with respect to the long-wave perturbations, find the critical Grashof number for the most dangerous among them of even spiral perturbation.Comment: in Russian, 18 pages, 5 figures, submited to Appl. mechanics and physics, RAS Siberian brunch, Novosibirsk, Russia; Key words: advective flow, oblique layer, a longitudinal temperature gradient, long-wave instabilit

ТКАНЕИНЖЕНЕРНЫЙ МАТРИКС, МОДИФИЦИРОВАННЫЙ БИОЛОГИЧЕСКИ АКТИВНЫМИ МОЛЕКУЛАМИ ДЛЯ НАПРАВЛЕННОЙ РЕГЕНЕРАЦИИ ТКАНЕЙ

Search of an ideal polymer for the preparation of the artificial scaffolds is an important goal of vascular tissue engineering. Biofunctionalization of the scaffolds may assist in creation of the bioactive environment at the site of implantation. Combination of biodegradable polymers and growth factors may be an appropriate approach for the directed regeneration of the vascular tissues.Purpose. To assess tissue reaction to nonwoven scaffolds prepared from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/polycaprolactone (PCL) with vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and stromal-derived growth factor-1α (SDF -1α) implanted into the rat pericardial sac.Materials and methods. Nonwoven PHBV/PCL scaffolds with and without VEGF, bFGF, and SDF -1α were prepared using electrospinning and implanted into the rat pericardial sac for 2 weeks, 1, 2, and 3 months with the further histological examination.Results. Implantation of the scaffolds did not cause any inflammatory reaction. We detected an active neoangiogenesis in both PHBV/PCL/VEGF and PHBV/PCL/SDF -1α scaffolds and adjacent tissues at all the time points. Moreover, we observed a considerable cell infiltration and production of extracellular matrix in PHBV/PCL/SDF -1α scaffolds. PHBV/PCL/bFGF scaffolds were colonized by fibroblasts and were surrounded by a connective tissue capsule. Therefore, growth factors retained their bioactivity in the tissues during the whole time of the experiment.Conclusions. Incorporation of the growth factors into biodegradable polymers is an appropriate approach for the creation of thetissue engineered scaffolds for directed tissue regeneration. VEGF, bFGF, and SDF -1α may be used for the creation of biodegradable vascular graft promoting de novo formation of the vascular tissue after the implantation.Важной задачей тканевой инженерии кровеносных сосудов является поиск материалов для изготовления искусственного матрикса, применяемого в качестве основы для восстановления тканей. Особый интерес представляет модификация матриксов для создания биологически активной среды в месте имплантации. Возможным решением данной проблемы может стать комбинирование биодеградируемых полимеров, ростовых факторов и хемоаттрактантных молекул.Цель. Оценить реакцию окружающих тканей на нетканные матриксы из полигидроксибутирата/валерата (ПГБВ) и поликапролактона (ПКЛ) с VEGF, bFGF и SDF -1α, имплантированные на переднюю поверхность сердца крыс.Материалы и методы. Нетканные матриксы ПГБВ/ПКЛ, немодифицированные и модифицированные сосудистым эндотелиальным фактором роста (VEGF), основным фактором роста фибробластов (bFGF) или хемоаттрактантной молекулой SDF -1α, изготавливали методом двухфазного электроспиннинга и имплантировали на переднюю поверхность сердца крыс сроком на 2 недели, 1, 2 и 3 месяца. По истечении срока наблюдения матриксы эксплантировали с прилежащими тканями и проводили гистологическое исследование.Результаты. Имплантация пустых и биофункционализированных ПГБВ/ПКЛ-матриксов не вызывала местной воспалительной реакции. В матриксах с VEGF и прилежащих к ним тканях отмечали активный ангиогенез на протяжении 3 месяцев. Образцы этой группы отличались умеренной клеточной инфильтрацией. ПГБВ/ПКЛ+bFGF-матриксы были значительно заселены фибробластами и окружены наиболее выраженной соединительнотканной капсулой. В матриксах с инкорпорированным SDF -1α наблюдали активную инфильтрацию клетками, синтезирующими внеклеточный матрикс, и неоангиогенез с образованием более крупных кровеносных сосудов относительно всех исследуемых образцов. Таким образом, инкорпорированные молекулы после высвобождения из матрикса проявляли биологическую активность в окружающих тканях в течение всего эксперимента.Заключение. Введение ростовых факторов и хемоаттрактантных молекул в биодеградируемые полимеры позволяет создавать тканеинженерные матриксы, обладающие бионаправленностью своего действия. Данный подход с использованием VEGF, bFGF и SDF -1α может быть использован в разработке функционально активного биодеградируемого сосудистого графта, способствующего формированию in situ ткани de novo после имплантации

A laboratory-scale experiment and a numerical simulation of unusual spiral plumes in a High-Prandtl-number fluid, links supplementary material

We experimentally and numerically investigated the generation of plumes from a local heat source (LHS) and studied the interaction of these plumes with cellular convective motion (CCM) in a rectangular cavity filled with silicon oil at a Prandtl number (Pr) of approximately two thousand. The LHS is generated using a 0.2-W green laser beam. A roll-type CCM is generated by vertically heating one side of the cavity. The CCM may lead to the formation of an unusual spiral convective plume that resembles a vertical Archimedes spiral. A similar plume is obtained in a direct numerical simulation. We discuss the physical mechanism for the formation of a spiral plume and the application of the results to mantle convection problems. We also estimate the Reynolds (Re) and Rayleigh (Ra) numbers and apply self-similarity theory to convection in the Earth's mantle. Spiral plumes can be used to interpret mantle tomography results over the last decade

Convective bifurcations in incompressible fluid in an inclined square cavity

Abstract not available

The Leydig Steroid Cell Tumor in a Postmenopausal Woman with Clinical and Biochemical Hyperandrogenism: A Case Report

Leydig cell tumors (LCTs) refer to tumors of the stroma of the genital strand, which are found mainly in postmenopausal women. The diagnosis of LCTs in postmenopausal women is associated with specific difficulties and is based on the identification of hyperandrogenism with clinical manifestations of virilization, which has an erased picture in postmenopausal women. LCTs require differential diagnosis with other causes of hyperandrogenism. We present the clinical case of a 55-year-old Russian postmenopausal patient with LCTs of the right ovary, significantly increased levels of androgens, and rapidly progressive clinical signs of hyperandrogenism. The patient underwent laparoscopic bilateral salpingo-oophorectomy, and the androgen indices reached average values by the first and third month after surgery. This case demonstrates that LCTs are often benign with a good prognosis and normalization of the clinical and laboratory manifestations of hyperandrogenism after surgical treatment. The type of surgery performed (bilateral salpingo-oophorectomy rather than unilateral) is recommended as the treatment of choice for LCTs in postmenopausal patients

Commentary to the update 2017 AHA/ACC and ESC/EACTS Guidelines for the management of patients with valvular heart disease

Commentary to the update 2017 AHA/ACC and ESC/EACTS Guidelines for the management of patients with valvular heart diseas