The prospective study of the effect of Nd:YAG laser iridectomy in patients with relative pupillary block on the retina central zone according to the data of optical coherence tomography

Objective: To assess possible changes in the macular region of the retina and the thickness of the peripapillary retinal nerve fiber layer (RNFL) according to the results of a dynamic study of OCT parameters after Nd:YAG laser iridectomy in patients with relative papillary block. Material and methods. Optical coherence tomography (OCT) was performed in 28 patients (38 eyes) with a relative papillary block before and after 1 hour, 1 day, 3 days, 1 week, 1 and 6 months after Nd:YAG laser iridectomy. We analyzed changes in the thickness of the retina in 9 standard zones according to ETDRS, the thickness of the layer of ganglion cells and the peripapillary RNFL. Results. The thickness of the layer of ganglion cells, as well as the thickness of the peripapillary RNFL, did not change significantly after laser intervention (all p ˃ 0.05) during the entire observation period. According to OCT, the retinal thickness significantly increased an hour after Nd:YAG laser iridectomy in 5 zones out of 9 by ETDRS and continued to increase over the course of a day. After 1 week, the thickness of the retina returned to its original values and did not change throughout the observation period. Conclusion: In patients with the relative papillary block, Nd:YAG laser iridectomy has a negligible effect on the thickness of the retina, measured by OCT, does not fundamentally affect the thickness of the layer of ganglion cells and the thickness of the peripapillary RNFL, and is safe for the central zone of the retina

Potential technological solution for sampling the bottom sediments of the subglacial lake Vostok: relevance and formulation of investigation goals

The subglacial Lake Vostok in Antarctic is a unique natural phenomenon, its comprehensive study involves sampling of water and bottom surface rocks. For further study of the lake, it is necessary to drill a new access well and develop environmentally safe technologies for its exploration. This article discusses existing and potential technologies for sampling bottom surface rocks of subglacial lakes. All these technologies meet environmental safety requirements and are conducive for sampling. The authors have proposed an alternative technology, using a walking device, which, due to its mobility, enables selective sampling of rocks across a large area from a single access well. The principal issues, related to the implementation of the proposed technology, are investigated within this article. This report is prepared by a team of specialists with many years of experience in drilling at the Vostok Station in Antarctic and in experimental work on the design of equipment and non-standard means of mechanization for complicated mining, geological and climatic conditions

Экспериментальные исследования переноса ледяного шлама воздухом при бурении снежно-фирновой толщи

The snow-firn layer of the glaciers of Antarctica and Greenland contains data on the composition of the atmosphere in the past, volcanic eruptions, forest fires, anthropogenic pollution, and many other unique information. Nowadays, core drilling methods are widely used for sampling the snow-firn layer. Due to numerous complications (loss of air circulation, drill bit sticking, ice balling up, etc.), air ice drilling is not wide spread, yielding in productivity and reliability to thermal and auger drilling methods. However, core barrel drilling with reverse bottom-hole air circulation is a promising technology for drilling the glaciers of Antarctica and Greenland. However, core drilling with reverse bottom-hole air circulation is a promising technology for drilling Antarctic and Greenland glaciers. The authors suggest that this technology, if successfully implemented, will significantly exceed the currently used methods of drilling the upper layers of the glacier. Taking into account the failures of previous projects of core drilling with air, it was decided to conduct research in the conditions of Central Antarctica in order to substantiate the design parameters of the new drill. During 67th Russian Antarctic Expedition (RAE) experimental studies of ice cuttings air transportation while drilling of the snow-firn layer were conducted at Vostok station. In the course of the experimental studies, the VK-22 borehole was drilled to a depth of 30 m with full core and ice cuttings sampling. According to the selected probes, the dependences of the change in the density of the snow-firn layer, bulk density and fractional composition of ice cuttings on the depth of occurrence were established. By using the experimental facility, the suspension velocity (critical speed in drilling) of ice particles of various sizes and shapes was found for the first time. Directions for further research and ways to improve the experimental facility are proposed, which are planned to be implemented in the season of the 68th RAEВ целях разработки технологии бурения снежно-фирновой толщи с обратной призабойной циркуляцией воздуха на станции Восток проведены экспериментальные исследования. Установлена динамика изменения характеристик ледяного шлама, таких как: фракционный состав, насыпная плотность, форма и скорость витания в зависимости от параметров снежно-фирнового горизонта, в том числе от распределения плотности массива по глубине

Механическое бурение ледников с очисткой забоя сжатым воздухом

Forecasting of the Earth's climate change is important for many spheres of human activity but this cannot be successful without reliable paleoclimatic information, an important source of which is the ice core material obtained during drilling of glaciers. The process of core sampling from the upper permeable snow-firn layers of glaciers is complicated by huge losses of the drilling fluid. One of the possible solutions to this problem is using of compressed air to clean the borehole and transport the slime up to the surface due to its easy replenishment. A review and analysis of international experience in mechanical ice drilling using compressed air as a cleaning agent has shown that the method under consideration has a number of disadvantages (loss of air in permeable glacier layers, accumulation of heavy rime and formation of ice sticking) that limit its use. However, the scheme of air reverse bottom-hole air circulation, first applied by scientists from the St. Petersburg Mining University on the dome of the Academy of Sciences Glacier (the Severnaya Zemlya archipelago) is free of the above disadvantages. To adapt this method to conditions of drilling in Antarctica, it is necessary to carry out a complex of researches, the implementation of which will allow creating a new cable-suspended electromechanical drill for efficient and environmentally friendly drilling of the upper layers of glaciers.Проведён обзор и анализ зарубежного и отечественного опыта бурения льда с применением сжатого воздуха в качестве очистного агента. На основании анализа обзора предложен способ, отличительная особенность которого – использование буровых снарядов на грузонесущем кабеле с обратной призабойной циркуляцией воздуха. Установлены достоинства и недостатки данного метода, а также распространённых на сегодняшний день технологий бурения снежно-фирновых горизонтов. Сформулирован комплекс научно-исследовательских работ, проведение которых позволит создать новый электромеханический снаряд для реализации предлагаемого способа

Ultrastructural changes of chorioretinal complex under sub-threshold laser exposure at wavelengths of 0.81 and 0.532 μm (experimental study)

Aim: To reveal ultrastructural changes of chorioretinal complex and their possible reversibility under sub-threshold laser exposure at wavelengths of 0.81 and 0.532 μm in 1, 8 and 30 days. Methods: Experimental study was performed on 16 chinchilla rabbits (32 eyes) using laser at wavelengths of 0.532 and 0.81 μm in CW, micropulse, and transpupillary thermotherapy modes. Transmission electron microscope EM-10C (Opton, Oberkochen, Germany) was used to perform ultrastructural study of retina following laser exposure. Results: In a day after sub-threshold laser exposure, ultrastructural changes were mainly detected in retinal pigment epithelium (RPE), choriocapillaries, and photoreceptors. In 8 days, intracellular regeneration of RPE and partial restoration of choriocapillary blood flow and RPE macrophages were observed. In 30 days, RPE morphology, the number and the structure of photoreceptor outer segments were re-established. Mitochondria of photoreceptor inner segments regenerated as well. Conclusion: Ultrastructural changes of chorioretinal complex following sub-threshold laser radiation were reversible. Intracellular regeneration provided almost complete recovery of chorioretinal complex structure by day 30