The study presents a numerical analysis of the parameters of the system for receiving solar vapor from a cylindrical collector with Syltherm800/Al
2
O
3
nanofluid as a coolant. A 3D mathematical ...model of convective heat transfer in a heat sink has been developed, which takes into account the environmental conditions and the uneven distribution of the concentrated solar flux, calculated by the Monte Carlo method. The temperature dependence of the thermophysical properties of the nanofluid was found using empirical formulas. It has been proven that at an initial coolant temperature of 300 K and a speed of 4 m/s, adding 3, 5, and 8% of Al
2
O
3
nanoparticles to the base coolant increases the heat transfer coefficient by 1.5, 3.4, and 7.8%, respectively. The problem of convective heat transfer was solved together with the hydrodynamic problem. The dependence of the Nusselt numbers of the considered coolants on the Reynolds numbers in the range from 0 to 55 × 10
4
is found. It has been determined that with an increase in the Reynolds number (
), the average Nusselt number for 3, 5, and 8% of Syltherm800/Al
2
O
3
nanofluids increases by 7.66, 11.8, and 15.76%, respectively. The method of minimizing the production of entropy was applied to find the range of Reynolds numbers that determine the optimal thermodynamic parameters. For 3% Syltherm800/Al
2
O
3
nanofluid, the optimal value of Reynolds numbers lies in the range
.
It has been earlier proposed a novel graft on basis of bioactive glass-ceramics for infected bony defects, where silver and copper ions are represented as antibacterial agents. The objective was to ...investigate clinical and radiological efficacy of the bioactive glass-ceramic composition (BGCC) as bone substitute material for periodontal intrabony defects surgery. In a group of 47 patients with periodontitis was conducted controlled clinical study of the proposed composition. As a control in 24 patients it has been used deproteinized bovine bone mineral (DBBM) with collagen membrane. Such parameters as pocket probing depth (PPD), clinical attachment level (CAL), gingival recession, the early wound-healing index (EHI), hygienic and gingival indices, radiological bone density were used for evaluation surgical outcomes. Guided tissue regeneration was carried out in 56 intrabony defects. A year after surgery it has been determined almost the same significant (p<0.05) decrease PPD to 53.5% in the BGCC group and to 45.7% in the DBBM group, CAL gain to 30.4% in the BGCC group and to 28.0% in the DBBM group. Intrabony defects were bone filled to 27.5% and to 30.1% respectively with no significant differences for comparison groups. However, it was noted the advantage of significant increasing bone density in treated sites with BGCC (p<0.05). It also has shown a tendency to decrease discomfort for patients and to improve wound healing in postsurgical period according to the EHI in the same group. The using of BGCC with collagen membrane leads to significant reduction in probing depth, clinical attachment level gain, raises bone density profile. However, further long-term clinical studies with histological evaluation are necessary.
Article is dedicated to revealing the qualitative characteristics of environment of five modern shopping centers of Kharkiv. Analysis is based on user reviews published on Google Maps. Review texts ...underwent semantic analysis with division of results under 4 qualitative categories, namely "commercial attractiveness", "comfortability", "energization of activity", "aesthetic articulation of the place". Results confirm the existence of three patterns of preferences' distribution that correspond to three types of shopping mall by structure (by B. Maitland), these being introverted, integrated and specialized or thematic type. The figures were then compared with results from similar analysis of foreign centers. Three shopping centers of Kharkiv received positive reviews in numbers comparable with foreign ones, all of the prevalent introverted type, signalling that competition between shopping complexes in Kharkiv is not high enough for their owners to seek new spatial concepts for retail objects. Meanwhile, developed retail markets of USA and Western Europe indicate the diversification of type and spatial characteristics of shopping centers. An adoption of shopping center organization methods from western practice and its belated spread in Ukraine lead to lag in new types' introduction. Particularly an idea of thematic narrative concept is a promising but underused resource in Kharkiv's situation.
Global strategies, including application of chemical plant protection products, are important in the cultivation of safe corps and preservation of human health. A promising area of preventive ...medicine, agronomy, agroecology and agroengineering is the optimization of methods of pesticide formulations application. The aim of the work was a hygienic assessment of the most common and latest methods of crops treatment with chemical pesticides. Results. The biological effectiveness of different types of pesticides is achieved by different application rates of the working solution. The most common method of pesticide application is spraying, which ensures the application of pesticides in the drop-liquid state and is characterized by low consumption of active substance per unit area, variable-controlled distribution on the treatment surface, provides good adhesion and retention on facilities, allows the use of combined formulations. One of the most effective ways to minimize the negative impact of chemical plant protection products and achieve economic success is a rational approach to the choice of pesticide application, as it takes into account the hazard class of pesticides, the presence of water protection zones, the sensitivity of target crops, etc. Conclusion. Rational application of pesticides includes minimizing the overall effect of pesticides on human health and the environment and achieving high-targeted biological efficiency. Adherence to the methodology of choosing the type of pesticide application and selection of the type of spray is a key point in optimizing the rational use of chemical plant protection products, which requires a detailed study from the standpoint of both efficiency and safety. Control over compliance with the recommendations should be included in sanitary-hygienic and sanitary-ecological monitoring.
В статті відображені особливості етіології, перебігу та комплексного лікування захворювань пародонта (гінгівітів, генералізованого пародонтиту). Показані можливі шляхи впливу захворювань пародонту на ...розвиток загальних захворювань організму.
В статті представлені основні розділи стоматології та показане значення захворювань зубів і порожнини рота для загального стану організму. При лікуванні загальних захворювань лікар повинен ...враховувати стан порожнини рота щоб досягти успіху в лікуванні.
The number of redistributions decreasing tendency in the production of rolled products, with all the positive economic effect, leads to the fact that the metal is subjected to a less intense ...deformation effect at low temperatures. In other words, the hereditary influence of the morphological features of the primary crystallization structure associated with the distribution concentration inhomogeneity of the segregating elements during crystallization (austenite and ferrite stabilizers) will be significantly higher. An analysis of the features of the final structure hereditary formation and the properties of tubing stocks obtained from continuously-cast steels of grades 45 and 20 was carried out. Two different etching solutions were used in the work. The combined approach in revealing the structure allows correlating the location nature of the final ferrite-pearlite and primary dendritic structure. It was established that when applying high degrees of tubing stocks reduction, ferrite-pearlite inhomogeneity, which is formed in rolled products from carbon steel, is due to the predominant formation of ferrite in lakes around sulfide inclusions. It is determined that finer pearlite grain is formed with a slight deformation of 45 grade steel in areas corresponding to the former interdendritic spaces. The greatest structural inhomogeneity of the finer grain is observed in the places of growth (jointing) of second and third orders dendritic branches. Also, with a slight deformation of 45 grade steel, there is no connection between the formation of the final structure with non-metallic inclusions. It has been shown that in continuously-cast stocks with developed dendritic and zonal segregation, structural features are preserved in normal rolled products and affect the strength of steel.
Abstract An exploratory three-level analysis was conducted to identify local resources for the design of modern shopping centers integrated into the urban structure of Kharkiv. It included a ...historical analysis of its commercial spaces, a typological analysis of modern shopping centers, as well as an online survey of residents regarding their use of commercial spaces. The typological composition of shopping centers in Kharkiv indicates predominance of introverted spatial organization, with absence of thematic shopping centers focused on aesthetic qualities of their environment. Resources provided by the peculiarities of regional situation can contribute to creation of such solutions. Among them are architectural images that accompanied the development of commercial buildings in the city, complex three-dimensional solutions of their prominent examples, as well as the use of temporary functions integrated into a flexible structure. The interest of respondents of an online survey in open, green, but at the same time protected spaces indicates mixed spaces of variable use as an unused resource in the conditions of Kharkiv. The available set of local resources highlights the potential for creating a sustainable shopping center of thematic type with characteristic regional features. Further research for its implementation may be carried out situationally, on specific location-related data.
PDF
