«CHERNOMOR»: TO THE 50th ANNIVERSARY OF THE LONGEST EXPERIMENT

The work is devoted to a brief description of the preparation and conduct series of scientific experiments in the underwater laboratory “Chernomor” during the period of 1967–1972. The experiments were carried out at the depths from 8 to 30 meters. The place of the experiments is the Southern Branch of the Institute of Oceanology (Gelendzhik). It was unique experiments in the duration of a person’s stay underwater. The maximum depth for “Chernomor” was identified, the optimal methods of organizing work in underwater inhabited houses and the permissible depths for the use of nitrogen-oxygen breathing mixtures were determined. Specialized medical and physiological research was carried out to develop a methodology for the selection and training of aquanauts for future scientific crews. “Chernomor” was the only underwater house in the world that served on the seabed for five seasons in a row. More than 50 scientists from all over the country worked in it in different crews. The work is a tribute to the memory of all enthusiasts and dreamers: designers and developers, engineers and technicians, divers and scientists, everyone involved in those unforgettable events.

Trail erosion in the area of the Seven Rila Lakes Cirquе, Rila National Park, Bulgaria

The study is of a pilot nature and aims to investigate and document the trail erosion in the Seven Rila Lakes Cirque, Rila National Park, Bulgaria. The width and maximum depth of the trails were measured in 31 randomly selected points on the trail network. The results show that in half of the studied cases there is а trail degradation, but in other cases, recovery processes are observed.

Materials for the database on the largest lakes of the Kuril Islands (morphometry, genesis and geographic distribution)

This paper presents generalized modern data on the location, morphometry, and genesis of the largest lake basins of the Kuril Islands, obtained in a series of expeditions of the laboratory of volcanology and volcanic hazard of the Institute of Marine Geology and Geophysics FEB RAS in 2005–2020. The data is supplemented with modern geoinformation open access resources. A sample of the largest of 1099 Kuril lakes has been made according to the areal criterion, thus, 20 objects have been included in the list of studied water bodies, which are represented by 7 volcanic and 13 lagoon lakes. The considered lakes are clearly divided according to genesis, area and height of the mirror, maximum depth, as well as the ratio of the main morphometric characteristics. This information is part of a database currently being created on the largest lakes in the region.

Substantiation of resource-saving technology when mining the deposits for the production of crushed-stone products

Purpose. Scientific substantiation of the expedient depth of mining the non-metallic deposits of rocky minerals on the basis of mathematical and statistical methods, which will ensure resource-saving and rational use of natural resources. Methods. To solve the purpose set, the following methods are used: graphical-analytical – when optimizing the maximum depth of mining the deposits of building materials, and the method of mathematical modeling – for determining the maximum depth of mining the non-metallic deposits with internal dumping. By means of statistical processing according to systematized types of deposits, the patterns of a change in the maximum depth of mining the basic deposits, depending on the main parameters of the quarry field, have been studied. Findings. A new methodology, which is distinguished by taking into account in-pit dumping, has been developed for calculating the maximum depth of granite quarries, which most of all influences the efficiency of mining operations and the value of economic indicators while ensuring the maximum economic effect with the achievement of a rational maximum depth of mining the deposit. A new, theoretically substantiated methodology has been created for determining the maximum depth of mining the mineral deposits for the production of crushed-stone products while providing the resource- and land-saving during the quarry operation. Originality. For the first time for these deposits, the dependence of their maximum mining depth on the main parameters of the quarry field and the place of internal dumping of overburden rocks has been determined. This has become a determining factor in the appropriate mining of deep non-metallic deposits of building materials with internal dumping, which provides a minimal land disturbance. Practical implications. The research results have been tested and implemented in working projects for mining the Liubymivske, Chaplynske, Pervomaiske, Mykytivske, Trykratske and Novoukrainske granite deposits; as a result of additional mining of mineral reserves, their additional increment in the volume from 1 to 48 million m3 is possible, which will ensure 5-40 years of sustainable operation of the mining enterprise.

Design and analysis of low-cost underwater glider for shallow water

This paper aims to design a low-cost underwater glider to operate in shallow water. The proposed design was developed by manufacturing engineering software. Analysis of the hull using manufacturing engineering software and 3D computer-aided design (CAD). The analysis of hydrodynamics using computational fluid dynamics (CFD). This glider was designed to operate in shallow water, coastal, lake and river for a maximum depth of 10 m and a maximum speed of current 12,96 km/h, or 3,6 m/s. To reduce and minimize the cost to manufacture this underwater glider, the mechanics, electrical, electronics, and power source were using common tools on the market, not on demand. Based on numerical model, the hull pressure had 30,127 psi or 0,2077162 MPa for maximum depth 10 m and max speed 12,96 km/h. Maximum pressure occurs on the nose and behind the wings. This unmanned vehicle was designed to be in 9 compartments. The first compartment and 8th compartment are used for ballast tanks. The others for: mechanics of ballast system, altimeter and attitude controller, payload, battery pack, main controller part, propulsion system, and propulsor.

Characteristics and Prevalence of Anterior Buccal Mandibular Depression Area in Cone Beam Computed Tomography Images

Summary Background/Aim: The purpose of this study was to assess the anterior buccal mandibular depressions (ABMD) prevalence and clinical characteristics at cone beam computed tomography images (CBCT). Material and Methods: 198 CBCT images with minimal depression between the mandibular molars were evaluated retrospectively. Presence and location of ABMD, its maximum depth, maximum width, cortical width, if any, alveolar crest width at maximum depth, the distance between maximum depth and alveolar crest apex and existing teeth in the relevant region were examined in cross-sectional views. Panoramic radiography of ABMD patients was evaluated for trabecular pattern and radiopacity to determine the area of interest. The possible lingual depression area on the maximum depth of ABMD slice was investigated and the same measurements for ABMD was performed. The presence of aperture / foramen in the ABMD area was also investigated. Results: The prevalence of ABMD was found as 43.43% where 82 cases were at bilateral side and 4 cases were only at left side. Lingual depression was observed in 20.7% right side and 30.2% left side of the ABMD cases. There was no statistically significant difference for maximum depth between different age groups. Most frequent location was observed in lateral and canine region (27.4%) followed by lateral-first premolar area (25.6%). Least frequent location was at canine-second premolar area (1.2%). Conclusions: ABMD is a lesser known area with a high prevalence observed on CBCT images. The detectability of the area on panoramic radiographs is limited. Clinicians should take into consideration ABMDs’ characteristics to avoid confusion with periapical pathologies. Failure to detect these areas before implant surgeries may cause complications. For this reason, it is important to be examined in detail for ABMD before surgery.

Interpretation of Aeromagnetic Data of Part of Gwagwalada Abuja Nigeria for Potential Mineral Targets

This study analyzes aeromagnetic data over a section of Gwagwalada in Abuja. The data were obtained from the Nigerian Geological Survey Agency acquired at 100 m terrain clearance. The study area spans longitudes 7.0875 E to 7.1458 E and latitude 8.9625 N to 9.0 N (about 27 km2). The dataset was reduced to the equator (RTE) and downward continued by 50 m. Analytic signal filter was applied on TMI-RTE grid to detect the edges of the magnetic bodies present. The structure was observed to trend NE-SW. The CET lineament map reveals intersections such as junctions and corners on the map. This revealed structure liable for potential mineralization zone. Euler deconvolution technique applied over the transformed dataset ascertain the location and depth of the structure,having a maximum depth of about 421 m and a minimum of about 59 m.Variation in magnetic depth and susceptibility contrast is specified by the gridded SPI depth map.

Morphometry of Gelionys and Žaliasis Lakes

Bathymetric surveys of Gelionys and Žaliasis Lakes (located in the Baltic Uplands, Aukštadvaris Regional Park, Lithuania) were carried out on April 21, 2020, from a boat with attached Lowrance HDI SKIMMER XDCR transducer (200 kHz), Simrad GO5 chartplotter and Lowrance Point-1 GPS/Glonass receiver. At the same time, the shorelines of the lakes were revised. Average distance between profiles was ~10 m and depth measurement accuracy up to 2–5 cm. Accuracy of water surface elevation measurement using GNSS receiver Topcon Hiper SR up to 1–2 cm. Later, detailed (0.5 × 0.5 m) digital lake bottom models (DEM) were developed, bathymetric plans of the lakes were created, the main morphometric features were calculated, the boundaries and area of the lake catchments were defined, and the physical-geographical characteristics of the lakes were described based on field observations and various data. Gelionys and Žaliasis are small lakes of glaciokarst origin. Gelionys Lake is oval-shaped while shape of Žaliasis Lake is closer to the circle. Despite small surface area the lakes are quite deep. According to survey data, the surface area of Gelionys Lake is 4.79 ha, water surface elevation 216.1 m a.s.l., maximum depth 19.8 m, mean depth 6.0 m, volume 288.3 thousands m3, catchment area 71 ha. The surface area of Žaliasis Lake is 2.14 ha, water surface elevation 120.9 m a.s.l., maximum depth 15.84 m, mean depth 5.7 m, volume 122.2 thousands m3, catchment area 60 ha. During the observation period (from May of 2018 to September of 2020), the annual amplitude of water level fluctuations in Gelionys Lake reached up to 0.47 m, and in Žaliasis Lake up to 0.33 m. Keywords: Gelionys, Žaliasis, glaciokarst, lake, bathymetric chart, morphometry, Lithuania, Aukštadvaris Regional Park.

Confocal laser scanning microscopic evaluation of depth of penetration and Sealer/Dentin interface between endodontic sealers - An in-vitro study

An endodontic sealer contributes in obtaining an appropriate seal for the root canal system by establishing an association between the root canal walls and coronal restoration thereby promoting healing. This present research intended to compare the penetrating capacity and to determine sealer/dentin interface among various endodontic sealers. Horizontally sectioned tooth samples were obtained at 3 and 5mm and randomly divided into three groups: Group I - Chemically cured (AH Plus) sealer; Group II - Dual cured (EndoREZ) sealer; Group III – BioCeramic Nano sealer (iRoot SP). All three groups were coated with their respective sealers and obturated using cold lateral compaction technique. The samples were observed using Confocal Microscope for penetrating capacity evaluation and reviewing of sealer/dentin junction at 3 and 5mm depth. The results were statistically analyzed using one-way ANOVA and Tukey's Post-Hoc method. On depth of penetration evaluation, one-way ANOVA analysis showed Group II exhibited maximum depth of penetration in contrast to Group III and Group I. Group I showed the least average depth of penetration among the other two groups at both 3 and 5mm. On sealer/dentin interface evaluation at 3mm, Group II showed increased interface in comparison with to Group III and Group I. No statistical significance evident among the groups at 5mm. EndoREZ showed maximum depth of penetration in comparison with iRoot SP and AH Plus sealer at both 3 and 5mm. EndoREZ also showed significant sealer/dentin interface at the level of 3mm when compared to other sealers used.