A novel concept for the manufacture of individual sapphire-metallic hip joint endoprostheses.

At the present time, artificial joints made with metallic, ceramic, metal-polymeric or ceramicpolymeric friction pairs substituting for the natural biomechanic articulations "head of the hip joint-acetabulum" are widely used for endoprosthetic operations on hip joints. Experience gained in the course of more than 2000 operations has shown that along with the advantageous properties of modern endoprosthetic constructions made of metal, ceramics and polymers, they have certain drawbacks. Among them are insufficient biological inertness and susceptibility to excessive wear of the friction pair components. In addition, as a result of wear of the hinge friction pair, toxic and oncologically dangerous products of degradation accumulate in the different organs and tissues. This in turn results in severe complications and demands correspondingly complicated corrective intervention, often leading to worse disability than that which the original operation was designed to cure. The aim of the study reported here was the development and clinical validation of a highly effective and long-lived hip joint endoprosthesis with a sapphire head whose wear capacity is superior to all others. The endoprosthesis consists of a metallic pedicle, a dismountable articulation (metallic necklayer of supramolecular polyethylene-sapphire head) and an acetabular cup. The endoprostheses with the sapphire head proved themselves positively in clinical trials and are considered to be highly promising for future applications

Анализ задач развития и процесса реинжиниринга надежности компьютерных связей для критических технологий

The analysis of tasks of development and reengineering of computer networks of information-control (I&C) systems of critical technologies (CT) using opened network technologies and the commercial network equipment is executed. Formal tasks of development and reengineering of computer networks I&C systems of CT are formulated and the initial data, necessary for their decision are analyzed. The principles of profile formation bases of the computer networks based on open standards, variants of a network structure and their choice are considered in view of the requirements showed to reliability, quality of service, to functional and other characteristics of computer networks. These procedures can be realized as the tool utilities, which allowing to automate the process of computer systems designing.Зроблено аналіз задач розвитку і реінжиніринга комп'ютерних мереж інформаційного контролю (I&C) системи критичних технологій (CT), що використовують відкриті мережні технології і комерційне устаткування. Формальні задачі розвитку комп'ютерних мереж I&C системи CT сформульовані, початкові дані, необхідні для їхнього рішення проаналізовані. Принципи формування профілю комп'ютерних мереж, заснованих на відкритих стандартах, а також варіанти структури мережі і їхній вибір розглядаються в розрізі вимог до надійності, якості обслуговування, до функціональних і інших особливостей комп'ютерних мереж. Ці процедури можуть бути зрозумілі як інструментальні утиліти, що дозволяють автоматизувати процес проектування

Chitosan–hydroxyapatite composite biomaterials made by a one step co-precipitation method: preparation, characterization and in vivo tests

A series of biocompatible chitosan/hydroxyapatite composites has been synthesized in an aqueous medium from chitosan solution and soluble precursor salts by a one-step coprecipitation method. The composite materials were produced in dense and porous variants. XRD and IR studies have shown that the apatite crystals in the composites have structural characteristics similar to those of crystals in biogenic apatite. A study of in vivo behaviour of the materials was carried out. Cylindrical rods made of the chitosan/ hydroxyapatite composite material were implanted into the tibial bones of rats. After 5, 10, 15 and 24 days of implantation, histological and histo-morphometric analyses of decalcified specimens were undertaken to evaluate their biocompatibility and the possibility to apply them in bone tissue engineering. The calcified specimens were examined by scanning electron microscopy combined with X-ray microanalysis to compare the elemental composition and morphological characteristics of the implant and the bone during integration. Porous specimens were osteoconducting and were replaced in vivo by newly formed bone tissue

Two-stage electro-discharge machining fabricating superhard cutting tools

Abstract A novel technique for fabricating efficiently precision cutting tools made from polycrystalline superhard materials is reported in the present paper. For this purpose, a two-stage electro-discharge machining (EDM) was applied on diamond polycrystallines, by employing first wire-electrode EDM for rough cutting and subsequently rotational disc-electrode EDM for finishing operations. Experimental results obtained clearly indicate the applicability of the proposed two-stage technique for fabricating precision cutting tools that can be used for the production of machined components made from glass and plastics, ceramics, composite materials and non-ferrous metals, at an industrial scale

Copper-catalysed diacetoxylation of butadiene. Spectroscopic and physico-chemical investigations of the catalyst

The copper(II) acetate-lithium bromide catalysed diacetoxylation of butadiene has been investigated in the acetic acid-acetic anhydride system under oxygen pressure. The distribution of positional isomers (1,4/3,4) appeared to be little dependent on the reaction conditions, the 3,4-isomer (Scheme I, compound (4)) being the kinetically controlled one. A relatively slow interconversion of the isomers was observed under the reaction conditions. The catalytic system was investigated by 7Li NMR and UV spectroscopy, and the kinetics of oxygen absorption by the catalyst were determined; the roles of acetic anhydride and water at the catalyst level were thus established. The investigation of the behaviour of potential intermediates of the diacetoxylation reaction has been considered as another tentative approach to the understanding of the reaction mechanism. © 1987