The treatment of acute corneal hydrops by subtotal penetrating keratoplasty. Clinical case

Clinical case of acute hydrops treatment using subtotal penetrating keratoplasty (PK) is presented. The diagnosis of acute hydrops was based on clinical and functional evaluations including optical coherent tomography (OCT). A part of diseased cornea was removed and examined under a light microscope. These studies revealed morphological changes in almost all corneal layers. OCT and histology demonstrated that PK was indicated to this patient. Recent literature data on the epidemiology and pathogenesis of acute hydrops are presented. This rare disease results from tears in the Descemet’s membrane that allow aqueous humor to enter the stroma. Current treatment is aimed to suppress corneal inflammation, restore endothelium and Descemet’s membrane integrity and drain stromal cysts to optimize cornea healing. In this case, subtotal PK was performed due to the significant corneal thinning and a high risk of its melting. «Material for corneal graft» (iLab, Moscow, Russia) was used as a donor material

MICROSTRUCTURE AND MATERIAL CHARACTERIZATION OF 1545K/B4C COMPOSITE PRODUCED BY STIR CASTING TECHNIQUES FOR NUCLEAR APPLICATIONS

Получен композиционный материал 1545K + 5%B4C методом механического замешивания частиц в расплав. Методом рентгенофазового анализа показано образование новых фаз Al3BC и AlB2 на границе матрица – частица, что говорит о хорошем межфазном взаимодействии. Композиционный материал 1545K + 5%B4C имеет σ0,2 = 425 МПа, σв = = 455 МПа и высокую стойкость к межкристаллитной коррозии при снижении механических характеристик менее чем на 5 %.The composite 1545K+5%B4C were successfully produced by stir casting technique. A good interface reaction between the matrix and the B4C reinforcements was observed by the formation of Al3BC and AlB2 (X-ray diffraction analysis was) phases on the matrix/B4C interface. 1545K+5%B4C alloy showed YS=425 MPa and UTS=455 MPa and, also high resistance to intercrystalline corrosion with decreasing in mechanical properties less than 5 %

Effect of Pulse Laser Welding Parameters and Filler Metal on Microstructure and Mechanical Properties of Al-4.7Mg-0.32Mn-0.21Sc-0.1Zr Alloy

The effect of pulse laser welding parameters and filler metal on microstructure and mechanical properties of the new heat-treatable, wieldable, cryogenic Al-4.7Mg-0.32Mn-0.21Sc-0.1Zr alloy were investigated. The optimum parameters of pulsed laser welding were found. They were 330–340 V in voltage, 0.2–0.25 mm in pulse overlap with 12 ms duration, and 2 mm/s speed and ramp-down pulse shape. Pulsed laser welding without and with Al-5Mg filler metal led to the formation of duplex (columnar and fine grains) as-cast structures with hot cracks and gas porosity as defects in the weld zone. Using Al-5Ti-1B filler metal for welding led to the formation of the fine grain structure with an average grain size of 4 ± 0.2 µm and without any weld defects. The average concentration of Mg is 2.8%; Mn, 0.2%; Zr, 0.1%; Sc, 0.15%; and Ti, 2.1% were formed in the weld. The ultimate tensile strength (UTS) of the welded alloy with AlTiB was 260 MPa, which was equal to the base metal in the as-cast condition. The UTS was increased by 60 MPa after annealing at 370 °C for 6 h that was 85% of UTS of the base alloy

Investigation of the influence of riboflavin-UV induced crosslinking on the cornea in the experiment

Purpose: Morphological examination of the efficiency of the influence of various doses of riboflavin-UV induced crosslinking on the state of the corneal stroma in experimental animals.Methods: In the work were used rabbits males breed Chinchilla mass of 1.5-2.0 kg. the experiment was conducted on 20 eyes of 10 animals, which performed the routine crosslinking. Experimental animals, depending on the power UV-laser irradiation, were divided into 4 groups: the animals of the 1 group with the minimum intensity of radiation (30 minutes, 0.27 J), animals 2 group with medium intensity of radiation (15 minutes, 0.34 J)), animals 3 groups with high intensity of radiation (30 minutes, 0.34 J)), the control group 4 (without UV-radiation). Date of dynamic observation of the experimental animals was 5 days, after which the animals were taken out of the experiment. Morphological investigations were carried out by means of light and electron microscopy.Results: In groups of experimental animals with the impact of riboflavin UV-radiation in the stroma of the cornea were found the appearance of the areas of cross-stitched collagen fibers and fibrils. In the zone of the crosslinking were found activated keratoblasts.Near the membranes of these cells the contents of the vacuoles are released and filaments finish building of the collagen fibers. the epithelium of the corneas of all experimental animals recovered fully, with no morphological signs of endothelial damage has been found. Electron-microscopic investigation of stroma of corneas of the experimental animals of the control group after the experiment showed the presence of keratocytes in an inactive form and collagen fibers of stroma, packed in the form of plates or beams with a characteristic orientation.Conclusion: Studies have shown that UV-irradiation of the cornea leads to the appearance of linking between the fibers of collagen and actively synthesizing cells in the stroma of the cornea, which points to a possible stimulation of collagen producing processes. When in excess of the threshold values of the energy of the UV-irradiation we have not identified any morphological signs of damage of the endothelial layer of the cornea

The influence of b4c composition in structure and thermal expansion coefficient of metal-alloy composite material based on AL-5% CO

In this paper the composite of alloy Al-5%Cu alloy reinforced with different percent of В4С (average size of 5 microns) have been prepared using stir casting technique. This technique found to be effective for giving uniform distribution of В4С particles through the matrix. Increasing the content of В4С particles in the matrix alloy leads to a minor porosity increase from 1 % to 3.1 %. The average linear thermal expansion coefficient in the temperature range from 20 to 100 °C decreases from 24.5 to 22.6 10-6 °C-1.В работе методом механического замешивания получены МКМ на основе сплава Al-5%Cu, армированные частицами В4С среднего размера 5 мкм. Разработана технология введения частиц В4С в расплав. Получено однородное распределение армирующих частиц В4С в матрице МКМ. С увеличением содержания В4С в матричном сплаве происходит незначительное повышение пористости с 1 до 3,1 %. Средний линейный коэффициент термического расширения в интервале температур от 20 до 100 °С снижается с 24,5 до 22,6 10-6 °С -1