Restoration of X-ray bone density when replacing cortical plate defects with a tissue-engineered construct in the experiment

Over the past decade, in global practice, the frequency of using high-resolution multi-layer spiral computed tomography (MSCT) for assessing the state of cancellous and cortical bone tissue has significantly increased. Using high-resolution MSCT makes it possible to assess X-ray bone density at various times after replacement of cortical plate defects with osteoplastic materials. The aim of the research. To study the restoration of cortical bone density in the area of osteoplasty using tissue-engineered construct in the experiment. Materials and methods. In an in vivo experiment on New Zeland White (NZW) rabbits, perforation defects of cortical bone were formed in the femoral diaphysis. Three study groups were set up: group 1 – without bone defect replacement; group 2 – with  bone defect replacement with deproteinized cancellous bone; group  3  – with bone defect replacement with tissue-engineered construct based on deproteinized cancellous bone with stromal vascular fraction of adipose tissue. Follow-up periods were 2, 4 and 6 weeks after the surgery. The X-ray density of cortical bone tissue was measured in Hounsfield units (HU). Fragments of deproteinized human cancellous bone were used alone and in combination with the stromal vascular fraction of NZW rabbit adipose tissue as a bone-replacing material for bone defect replacement. Results. Cortical plate density the in the area of the defect in the group 3 by the week 6 is on average 1.3 times lower than that of the intact cortical plate and corresponds to D1 according to Misch classification. Cortical plate density in the area of the defect on the side of medullary canal by the week 6 in the group 3 corresponds to D1 according to Misch classification and is equal to 1351.25 ± 221.18 HU (1052; 1805), which is 1.5  times higher than in group  2 (D2 according to Misch classification; p < 0.05). The obtained results indicate an earlier restoration of X-ray bone density when using a tissue-engineered construct (group 3) compared to the same indicators in groups 1 and 2

The Social Reorientation of Ukraine's Economic Structure

Decades of totalitarian domination in the former USSR, the five-year period of anarchistic "perestroika" of its economy according to M[ikhail] Gorbachev's methods, and the unsystematic and inconsistent market reforms of the last five years (1991-95) under the conditions of the independent existence of independent states unfortunately did not lead to deep structural and qualitative changes in the socioeconomic situation in the great majority of post-socialist countries. Moreover, their economies were extremely exhausted, their micro- and macroeconomic structures were even more deformed, and they were in a state of dire crisis.

Prices and Planned Economic Regulation of Agricultural Production

The economic policy of the Communist Party and Soviet government in the field of agriculture is aimed at stimulating greater output in every way, at further developing relationships based on economic accountability, and at increasing the effectiveness of social production. Review of the system of purchase and sales prices on agricultural products, as well as of wholesale prices on industrial goods used in the village, in the direction of a more equivalent exchange; improvements in the financing and extension of credit to state and collective farms; improvements in the system of planning and material-technical supply; introduction of a guaranteed wage for collective farmers; and other measuresâall have served as the basis for economic transformations that constitute the essence of the economic reform.

Problems in Agricultural Forecasting

Forecasting the development of agricultural production, like the forecasting of any other sphere of human activity, is probably the most complex process in comprehending and scientifically predicting patterns of the distant future. In the socialist system of national economic planning, forecasts are becoming a most important stage preceding the elaboration of long-term plans. The Directives of the Twenty-Fourth Congress of the CPSU call for improvements in long-term planning methods and for the elaboration of a long-range plan based on scientific forecasts. In the Report to the Congress, L. I. Brezhnev, Secretary General of the Central Committee of the CPSU emphasized: "The realization of the most important economic and sociopolitical tasks will require not five years but a much longer time.

Формування структури та властивостей литих деталей зі сплаву ак7ч із використанням комплексної обробки

Purpose.Formation of a separate non-dendritic structure and increasingof mechanical properties of “disk” -type parts from  AK7ch  alloy. Methodology. Material  for  this  study  were  alloy  AK7ch.  Part  of  the  charge  was  replaced  by  fine-crystalline remelt. Experimental melting in three different technological variants was carried out in a gas furnace. The study of the structure was carried  out  on  transverse  sections  of “disk”-type  parts, the  control  of  mechanical  properties  was  carried  out  on  samples  made according to GOST 1497-84 after heat treatment according to T5 mode. Findings.Studies have shown that the integrated application of  modifying  treatment  and  melted  crystalline  melt  can  significantly  improve  the  mechanical  properties  of  secondary  aluminum alloys. Originality. For  the  first  time  in  the  production  conditions,  the  technology  of  complex  processing  of  the  melt  with  a modifying complex and fine-crystalline remelting was applied. Practical value. The results obtained can improve the quality of cast parts.Цель. Формирование разрозненной не дендритной структуры и повышение механических свойств деталей типа  «диск»  из  сплава  АК7ч. Методика. Материалом для данного исследования выбран сплав  АК7ч.  Часть шихты была заменена на мелкокристаллический переплав. Экспериментальные плавки по трем различным технологическим вариантам проводили  в  газовой  печи.  Исследование  структуры  проводили  на  поперечных  шлифах  деталей  типа  «диск»,  контроль механических свойств осуществляли на образцах, изготовленных согласно ГОСТ 1497-84 после термической обработки по режиму Т5. Результаты. Проведенные исследования показали, что комплексное применение модифицирующей обработки и  мелкокристаллического  переплава  способно  значительно  повысить  механические  свойства  вторичных  алюминиевых сплавов. Научная новизна. Впервые в условиях производства была применена технология комплексной обработки расплава модифицирующим комплексом и мелкокристаллическим переплавом. Практическая значимость. Полученные результаты позволяют повысить качество литых деталей.Мета. Формування  розрізненої  недендритної  структури  та  підвищення  механічних  властивостей  деталей типу  «диск»  із  сплаву  АК7ч. Методика. Матеріалом  для  даного  дослідження  обрано  сплав  АК7ч.  Частина  шихти  була замінена  на  дрібнокристалічний  переплав.  Експериментальні  плавки  за  трьома  різними  технологічними  варіантами проводили  в  газовій  печі.  Дослідження  структури  здійснювали  на  поперечних  шліфах  деталей  типу  «диск»,  контроль механічних  властивостей  здійснювали  на  зразках,  виготовлених  відповідно  до  ГОСТ  1497-84  після  термічної  обробки  по режиму  Т5. Результати. Проведені  дослідження  показали,  що  комплексне  застосування  модифікувальної  обробки  і дрібнокристалічного переплаву, здатне значно підвищити механічні властивості вторинних алюмінієвих сплавів. Наукова новизна. Вперше  в  умовах  виробництва  була  застосована  технологія  комплексної  обробки  розплаву  модифікувальним комплексом  та  дрібнокристалічним  переплавом.  Практична  значимість.  Отримані  результати  дозволяють  підвищити якість литих деталей