Properties of dusty plasma crystal accounting charge variety of dust particles

Shock wave properties generated by impulse mechanical loading and base state structure of dusty plasma system versus the change of dusty particle charges with height were investigated in the framework of the molecular dynamics method. Spherically symmetric electrostatic confinement was used as the boundary conditions. Interactions between dusty particles were described using Debye-Huckel potential. Particle charges decreased linearly with the increase of height. Shape of dusty plasma crystals with taking into account a variable particle charge was simulated

Investigation of defect nucleation in titanium under mechanical loading

The paper undertakes a study of plastic deformation in a titanium crystallite under mechanical loading (uniaxial tension and indentation) in terms of atomic mechanisms of its generation and development. The molecular dynamics method with many-body interatomic potentials is employed. It is shown that there is a threshold strain, at which a crystal reveals the generation of local structural transformations associated with changes in atomic configurations of the first and second coordination spheres. The onset of plastic deformation in a crystallite is accompanied by a stepwise decrease in potential energy. The effect of free surfaces and grain boundaries on the generation of local structural transformations in a titanium crystallite is investigated

Drug Loaded Biodegradable Load-Bearing Nanocomposites for Damaged Bone Repair

In this paper we present a short review-scientific report on processing and properties, including in vitro degradation, of load bearing biodegradable nanocomposites as well as of macroporous 3D scaffolds for bone ingrowth. Biodegradable implantable devices should slowly degrade over time and disappear with ingrown of natural bone replacing the synthetic graft. Compared to low strength biodegradable polymers, and brittle CaP ceramics, biodegradable CaP-polymer and CaP-metal nanocomposites, mimicking structure of natural bone, as well as strong and ductile metal nanocomposites can provide to implantable devices both strengths and toughness. Nanostructuring of biodegradable [beta]- TCP (tricalcium phosphate)-polymer (PCL and PLA), [beta]-TCP-metal (FeMg and FeAg) and of Fe-Ag composites was achieved employing high energy attrition milling of powder blends. Nanocomposite powders were consolidated to densities close to theoretical by high pressure consolidation at ambient temperature-cold sintering, with retention of nanoscale structure. The strength of developed nanocomposites was significantly higher as compared with microscale composites of the same or similar composition. Heat treatment at moderate temperatures in hydrogen flow resulted in retention of nanoscale structure and higher ductility. Degradation of developed biodegradable [beta]-TCP-polymer, [beta]-TCPmetal and of Fe-Ag nanocomposites was studied in physiological solutions. Immersion tests in Ringer's and saline solution for 4 weeks resulted in 4 to 10% weight loss and less than 50% decrease in compression or bending strength, the remaining strength being significantly higher than the values reported for other biodegradable materials. Nanostructuring of Fe-Ag based materials resulted also in an increase of degradation rate because of creation on galvanic Fe-Ag nanocouples. In cell culture experiments, the developed nanocomposites supported the attachment the human osteoblast cells and exhibited no signs of cytotoxicity. Interconnected system of nanopores formed during processing of nanocomposites was used for incorporation of drugs, including antibiotics and anticancer drugs, and can be used for loading of bioactive molecules enhancing bone ingrowth

Modification of argillous raw materials by additives comprising carbonates

In order to improve technological and drying properties of argillaceous raw materials and to produce face brick of light color shades from low-melt and red-burning clay, a modification of carbonate-containing additive, in a form of oil-slime utilization product, was carried out. An influence of a concentration of an additive on structure and properties of a modified mixture is discussed. Structure of ceramics and chemical composition of minerals formed during burning is studied, their influence and an influence of organic component of the additive on a change of color and properties of ceramic brick, manufactured by means of plastic molding method, are identified

Bulk nanostructuring intermetallic composite material

The article states the results of a study of the impact rendered by the plastic strain occurring in a high-temperature synthesis product during the thermal explosion of a nickel-aluminum powdermixture on the grain structure, strength and ductility of the Ni3Al synthesized intermetallic compound

Modification of argillous raw materials by additives comprising carbonates

In order to improve technological and drying properties of argillaceous raw materials and to produce face brick of light color shades from low-melt and red-burning clay, a modification of carbonate-containing additive, in a form of oil-slime utilization product, was carried out. An influence of a concentration of an additive on structure and properties of a modified mixture is discussed. Structure of ceramics and chemical composition of minerals formed during burning is studied, their influence and an influence of organic component of the additive on a change of color and properties of ceramic brick, manufactured by means of plastic molding method, are identified

John Price, trustee portrait

Photograph of John Pric

Максимизация конкуренции в биологически правдоподобной нейронной сети

Целью данной работы является максимизация конкуренции среди биологически правдоподобных нейронов для получения максимального количества рецептивных полей. Биологически правдоподобная нейронная сеть в процессе обучения должна выучить различные независимые компоненты уникального входного сигнала. Сеть содержит 100 выходных нейронов, каждый из которых получает на вход 800 значений яркостей пикселей фрагментов изображений. Метод обучения нейронной сети основан на правиле Хебба. Для решения задачи максимизации конкуренции применяется антихеббовская модель модификации синаптических связей. Показана важная роль динамической скорости обучения, значение которой возрастает в случае низкого максимального выходного значения нейронов и уменьшается при высоком максимальном выходном значении нейронов. Это приводит к повышению конкуренции и созданию большого количества различных образов, характеризуемых соответствующими рецептивными полями