Search Results (35)

In 2023, studies were carried out on the aquatic environment of the forest lake Łętowskie. The studies covered the horizontal and vertical planes and seasonal dynamics. Lake Łętowskie is a lake with an area of 402 ha, which distinguishes it from other lakes in Pomerania due to its large area. In three quarters of the lake shore border forests, changes in surface and volume have been observed in the lakes over the last century, which has affected the chemistry of the water. The aims of this study were to determine the dependencies between the concentration of biogenic substances in the near-bottom layer and subsurface water and analyze the dependencies between chemical parameters in the water of the mid-forest lake Łętowskie. In the water samples obtained, including the surface layer (SW) and the near-bottom layer (NBL), the concentrations of N-NO₃, N-NO₂, N-NH₄, N-tot, N-org, P-PO₄, P-tot, P-org, and O₂, electrolytic conductivity, pH, Ca, and Mg were determined. Statistical analyses were carried out, including tests and multidimensional PCA and cluster analysis. A significant effect of forests on the chemical composition of lake water was observed. The conducted studies of Łętowskie Lake indicate that the NBL experiences seasonal dynamics, where phosphorus and nitrogen compounds are transformed, which causes trophic changes in the lake. Based on multidimensional cluster analysis, differences between the SW and the NBL were shown. In Łętowskie Lake, the level of biogenic substances in the water is significantly influenced by processes occurring inside the lake as a result of the exchange of matter between the NBL and bottom sediments. This exchange in shallower areas of the lake is influenced by winds, especially in exposed locations: this was observed for P-tot, P-PO₄, P-org, Ca, N-NO₃ and N-NH₄, N-tot, and N-org. The conducted studies are important for supporting the protection of the Landscape Area “Łętowskie Lake and the vicinity of Kępice” to preserve the existing values of the natural environment and maintain the ecological balance of natural systems. Current scientific publications on the hydrochemical data of Łętowskie Lake are currently lacking, and the available data needs to be updated. Full article

Odonata constitute an important invertebrate group that is strongly dependent on water conditions and sensitive to habitat disturbances, rendering them reliable indicators of habitat quality of both aquatic and terrestrial habitats. We studied the compositional and diversity patterns of Odonates in total, and separately for the two suborders (Zygoptera, Anisoptera) in relation to geographic and ecological parameters at the riparian zone of four rivers and one canal within the Axios Delta National Park and the Natura 2000 SAC GR1220002 in northern Greece, using the line transect technique. In total, 6252 individuals belonging to 28 species were identified. The compositional and diversity patterns were significantly different between agricultural and natural sites. Odonata assemblages at croplands were comparatively poorer, dominated by a few, widely distributed, taxonomically proximal species, tolerant to environmental changes, as a result of modifications and consequent alterations of abiotic conditions at croplands, which also led to higher local contribution to β-diversity and species turnover. The absence of several percher, endophytic, and threatened species from agricultural sites led to significantly lower diversity, as a result of environmental filtering due to ecophysiological restrictions. Taxonomic and functional diversity, uniqueness, and Dragonfly Biotic Index (DBI) were significantly higher in riparian forests, due to the sensitivity of damselflies to dehydration, and the avoidance of habitat loss and extreme temperatures by dragonflies, which prefer natural shelters near the ecotone. The newly introduced Conservation Value Index (CVI) revealed 21 conservation hotspots of Odonata (14 at canopy cover sites), widely distributed within the borders of NATURA 2000 SAC GR1220002. Full article

This study assesses the ecological status of alpine lotic ecosystems in Khunjerab National Park, Pakistan, situated at approximately 4000 m in the Karakoram Range along the Pakistan–China border. An integrative approach was employed, evaluating alpine stream ecosystems through benthic macroinvertebrate indices in conjunction with physicochemical habitat parameters. Samples were gathered using kick nets and hand-picking at seventeen randomly selected sites in early spring and summer. The study recorded 710 summer taxa from 41 families and seven orders, and 1250 early spring taxa from 30 families and six orders. The abundance of macroinvertebrates increased in early spring, while taxonomic diversity increased during the summer. Statistical tests revealed a strong relationship between water quality conditions and biological features. The biotic index reached its peak in early spring, while diversity indices peaked in summer when Ephemeroptera dominated. Due to the macroinvertebrate source in early spring, the majority of EPT taxa were abundant at all alpine stream sites during early spring, except for upstream sites in summer. The indices from the biotic metric evaluation revealed low levels of natural environmental disturbance caused by humans. This research is significant in terms of natural resource conservation and health assessment based on the benthic fauna community structure in alpine streams. Full article

The variability of natural parameters in border fields is one of the main factors leading to poor irrigation performance. To explore the impact of natural parameter variation on border irrigation performance, a four-year field irrigation experiment was conducted in this study, and the obtained parameters were combined with the WinSRFR V4.1 model to simulate the advance–recession process under different discharge scenarios. Based on the observed and simulated data, the influence of natural parameter variation on the flow process of constant discharge irrigation was analyzed, and thus the optimal observation points for advancing and discharge regulation strategy were further established. The results indicated that in a constant discharge border irrigation system, the irrigation performance index showed a trend of first increasing and then decreasing with the increase in discharge, and the variation range of the reduced section was smaller than that of the increased section. Therefore, the risk of inefficient irrigation caused by flow fluctuations could be reduced to a certain extent by increasing the discharge. Additionally, variability in natural parameters also caused the water advance time to deviate gradually from expectations, and the deviation would be obvious when the flow advanced to the point of 40 m. The adjustment range of the optimal regulation discharge q_M was greater than the corresponding optimal constant discharge q_D2 under natural parameter variations. In the ideal situation of uniform natural parameters within the border, the optimal discharge regulation scheme could improve the application efficiency, irrigation uniformity, and water storage efficiency to 97.3%, 95.5%, and 96.9%, respectively. The results of this study can provide a theoretical basis for the development of automatic regulation of border irrigation systems. Full article

The Tabuk region is located in the northern part of Saudi Arabia, and it has an area of 117,000 km² between longitudes 26° N and 29° N and latitudes 34° E and 38° E. King Salman Bin Abdulaziz Royal Natural Reserve (KSRNR) is the largest natural reserve in Saudi Arabia and covers about 130,700 km². It represents a new tourist attraction area in the Tabuk region. Human activities around the lake may lead to changes in water quality, with subsequent changes in microenvironment components, including microbial diversity. The current study was designed to assess possible changes in bacterial communities of the water sediment at some natural lakes and artificial waterpoints of KSRNR. Water samples were collected from ten different locations within KSRNR: W1, W2, W3 (at the border of the royal reserve); W4, W5, W6, W7 (at the middle); and W8, W9, and W10 (artificial waterpoints). The total DNA of the samples was extracted and subjected to 16S rRNA sequencing and metagenomic analysis; also, the environmental parameters (temperature and humidity) were recorded for all locations. Metagenomic sequencing yielded a total of 24,696 operational taxonomic units (OTUs), which were subsequently annotated to 193 phyla, 215 classes, 445 orders, 947 families, and 3960 genera. At the phylum level, Pseudomonadota dominated the microbial communities across all samples. At the class level, Gammaproteobacteria, Clostridia, Alphaproteobacteria, Bacilli, and Betaproteobacteria were the most prevalent. The dominant families included Enterobacteriaceae, Pseudomonadaceae, Clostridiaceae, Comamonadaceae, and Moraxellaceae. At the genus level, Pseudomonas, Clostridium, Acinetobacter, Paenibacillus, and Acidovorax exhibited the highest relative abundances. The most abundant species were Hungatella xylanolytica, Pseudescherichia vulneris, Pseudorhizobium tarimense, Paenibacillus sp. Yn15, and Enterobacter sp. Sa187. The observed species richness revealed substantial heterogeneity across samples using species richness estimators, Chao1 and ACE, indicating particularly high diversity in samples W3, W5, and W6. Current study results help in recognizing the structure of bacterial communities at the Tubaiq area in relation to their surroundings for planning for environmental protection and future restoration of affected ecosystems. The findings highlight the dominance of various bacterial phyla, classes, families, and genera, with remarkable species richness in some areas. These results underscore the influence of human activities on microbial diversity, as well as the significance of monitoring and conserving the reserve’s natural ecosystems. Full article

For the first time, we have compiled a general list of diatoms for the Zarafshan River consisting of 428 species based on our own research and the literature data. Indicator species for nine water parameters were identified, making up more than 90% of the list. Bioindicators and statistical methods revealed that sections of the river around the city of Samarkand and further in the middle reaches reflect the complexity of the impact of the environment on diatom communities. The surveyed sections of the middle reaches of the river are divided into branches and the dynamics of water parameters and diatom communities are shown from the border with Tajikistan to the confluence of the Zarafshan with the Amu Darya. The indices of organic pollution, S, and toxic impact, WESI, were calculated. They show that there is an increase in salinity and turbidity and a decrease in organic pollution downriver. At the same time, the Navoi section is a source of water acidification. Nutrients and heavy metals, as well as phenol pollution, enter the river from various sources, mainly in the middle reaches of the river. The Zarafshan Nature Reserve in the catchment area of the upper section of the river within Uzbekistan is important for maintaining water quality. Bioindicators show an increase in self-purification, with an increase in the species richness and abundance of diatoms in the middle section of the Zarafshan River. The integrated index of river pollution, RPI, shows that most pollution comes from the northern canal of the river in the middle reaches. A general look at the Zarafshan River catchment basin and the dynamics of the identified water parameters and bioindicator species of diatoms shows that the river ecosystem successfully copes with incoming pollution, including transboundary impacts from Tajikistan. Such a conclusion could not be made based on chemical analysis of the water alone. This allowed us to recommend expanding state monitoring points to the lower section of Karakul while including biological indicators in the observations. Full article

Skin cancer is a prevalent type of malignancy on a global scale, and the early and accurate diagnosis of this condition is of utmost importance for the survival of patients. The clinical assessment of cutaneous lesions is a crucial aspect of medical practice, although it encounters several obstacles, such as prolonged waiting time and misinterpretation. The intricate nature of skin lesions, coupled with variations in appearance and texture, presents substantial barriers to accurate classification. As such, skilled clinicians often struggle to differentiate benign moles from early malignant tumors in skin images. Although deep learning-based approaches such as convolution neural networks have made significant improvements, their stability and generalization continue to experience difficulties, and their performance in accurately delineating lesion borders, capturing refined spatial connections among features, and using contextual information for classification is suboptimal. To address these limitations, we propose a novel approach for skin lesion classification that combines snake models of active contour (AC) segmentation, ResNet50 for feature extraction, and a capsule network with a fusion of lightweight attention mechanisms to attain the different feature channels and spatial regions within feature maps, enhance the feature discrimination, and improve accuracy. We employed the stochastic gradient descent (SGD) optimization algorithm to optimize the model’s parameters. The proposed model is implemented on publicly available datasets, namely, HAM10000 and ISIC 2020. The experimental results showed that the proposed model achieved an accuracy of 98% and AUC-ROC of 97.3%, showcasing substantial potential in terms of effective model generalization compared to existing state-of-the-art (SOTA) approaches. These results highlight the potential for our approach to reshape automated dermatological diagnosis and provide a helpful tool for medical practitioners. Full article

The current state of aquatic ecosystems was assessed for lakes in two river–lake systems: Święta Struga (Święte and Ocypelek) and Kałębnica (Czarne Południowe and Kałębie). Trophic states were determined using the Vollenweider, Nürnberg, and Carlson methods. Additionally, shoreline changes were analyzed for all lakes concerning their natural character, and physicochemical parameters were utilized as auxiliary elements in the assessment of the ecological state following the guidelines of Directive 2000/60/EC. Supplementary to these methods, the ecological evaluation of the littoral zone utilized meiobenthic organism grouping as an indicator. The results indicate significant differences among the studied reservoirs. Lake Święte is a reservoir bordering mesotrophy and eutrophy, with the ecological state of the littoral zone showing ongoing trophic development. Lake Ocypelek exemplifies a eutrophic reservoir undergoing progressive degradation. The lakes in the Kałębnica system also exhibit advanced trophic conditions, with Lake Kałębie being a eutrophic reservoir. Its shoreline has been significantly altered due to the development of the direct catchment area. In contrast, Lake Czarne Południowe serves as an example of a mesotrophic reservoir, with a substantially changed shoreline. Considering physicochemical elements and chlorophyll a concentration, the water quality for all examined lakes was found to be below the good category. The diagnosis of the condition of lake aquatic ecosystems requires an individualized approach to each of them. Therefore, employing various methods for their assessment, encompassing physico-chemical, biological, and morphological parameters, provides the opportunity to initiate potential remedial actions that will effectively contribute to their improvement. Conducting low-cost research involving a multidisciplinary approach to diagnose the state of aquatic ecosystems is becoming a crucial element in lake monitoring. Full article

Background: The purpose of this study is to compare turbo spin echo diffusion-weighted images in radial trajectory (BLADE DWI) with multi-shot echoplanar imaging (RESOLVE DWI) for imaging the metastatic lesion in the pelvic bone to find a correlation between ADC values and standardized uptake values (SUVs) of FDG uptake in PET/CT. The study also seeks to compare the values of metastatic lesions with those of benign bone lesions, specifically red marrow hyperplasia. Methods: The retrospective IRB-approved study included patients with bone metastasis and red marrow hyperplasia in the pelvic bone who underwent 3.0 T MRI with BLADE/RESOLVE DWI sequences and F-18 FDG PET/CT within one month. BVC (best value comparator) was used in determining the nature of bone lesions. Apparent diffusion coefficient (ADC) and standardized uptake value (SUV) were measured by a radiologist and a nuclear medicine physician. MRI image quality was graded with a Likert scale regarding the visualization of the sacroiliac joint, sacral neural foramen, hamstring tendon at ischial tuberosity, and tumor border. Signal-to-noise ratio (SNR) and imaging time were compared between the two DWIs. Mean, peak, and maximum SUVs between metastatic and benign red marrow lesions were compared. SUVs and ADC values were compared. AUROC analyses and cut-off values were obtained for each parameter. Mann–Whitney U, Spearman’s rho, and Kolmogorov–Smirnov tests were applied using SPSS. Results: The final study group included 58 bone lesions (19 patients (male: female = 6:13, age 52.5 ± 9.6, forty-four (75.9%) bone metastasis, fourteen (24.1%) benign red marrow hyperplasia). ADCs from BLADE and RESOLVE were significantly higher in bone metastasis than red marrow hyperplasia. BLADE showed higher ADC values, higher anatomical scores, and higher SNR than RESOLVE DWI (p < 0.05). Imaging times were longer for BLADE than RESOLVE (6 min 3 s vs. 3 min 47 s, p < 0.05). There was a poor correlation between ADC values and SUVs (correlation coefficient from 0.04 to 0.31). The AUROC values of BLADE and RESOLVE MRI ranged from 0.892~0.995. Those of PET ranged from 0.877~0.895. The cut-off ADC values between the bone metastasis and red marrow hyperplasia were 355.0, 686.5, 531.0 for BLADE min, max, and average, respectively, and 112.5, 737.0, 273.0 for RESOLVE min, max, and average, respectively. The cut-off SUV values were 1.84, 5.01, and 3.81 for mean, peak, and max values, respectively (p < 0.05). Conclusions: Compared with RESOLVE DWI, BLADE DWI showed improved image quality of pelvic bone MRI in the aspect of anatomical depiction and SNR, higher ADC values, albeit longer imaging time. BLADE and RESOLVE could differentiate bone metastasis and red marrow hyperplasia with quantifiable cut-off values. Further study is necessary to evaluate the discrepancy between the quantifiers between PET and MRI. Full article

Neom city is a unique cross-border city connecting Saudi Arabia, Jordan, and Egypt. Although Neom city is of great and critical importance for Saudi Arabia, few hydrological, natural hazard, and geomorphological studies have been undertaken on this region. This work aims to investigate the hydro-geomorphological characteristics and assess the flash flood hazards in Neom city by investigating several valuable morphometric parameters. The Shutter Radar Topography Mission (SRTM) digital elevation model and hydrological and geological data were analyzed in this study using ArcGIS software. Based on the morphometric parameter results, total stream lengths and stream orders were relatively high (17,956.03 km and 5, respectively), whereas the average bifurcation ratio was recorded to be low at 3.54. Basins 10, 12, 17, 30, 31, 32, and 34 were described as large basins, coarse-textured, elongated, with a medium drainage density, low infiltration values, long overland flows, and high values of constant maintenance. Additionally, the El-Shamy approach for flood hazard assessment was applied side by side with the morphometric analysis, which indicated that the possibility of an intense flood hazard is very low. In general, this study suggests that most of the studied basins cover similar and resistant rocks and soils. They have minimal conditions for flooding events and suitable conditions for underground and surface water resources. Therefore, they display high signals of susceptibility to erosion. The morphometric analysis and flash flood assessment techniques applied in this study were time- and cost-effective for the morphometric characterization of landforms. This text deals with the analysis of several environmental characteristics including hydro-morphological characteristics, drainage topography and lithology, soil erosion, groundwater recharge impact, and flash flood signals. Excellent sustainability plans should be reliant on extensive and varied information about the environment. Thus, integrated analyses incorporating environmental characteristics and flood hazard assessment play an important role in adjusting and adapting the suitable socioeconomic and scientific sustainability of the development of the study city. They build up the basic and essential information required to help decision-makers and sustainability managers design and adjust the most suitable sustainability plans for the study city over the long term. Full article

Shortages of water resources and labor make it urgent to improve irrigation efficiency and automation. To respond to this need, this study demonstrates the development of an adaptive border irrigation system. The inflow is adjusted based on the functional relationship between the advance time deviation and the optimal adjustment inflow rate, thereby avoiding the real-time calculation of infiltration parameters required by traditional real-time control irrigation systems. During the irrigation process, the inflow rate is automatically adjusted based only on the advance time deviation of the observation points. The proposed system greatly simplifies the calculation and reduces the requirements for field computing equipment compared with traditional real-time control irrigation systems. Field validation experiments show that the proposed system provides high-quality irrigation by improving the application efficiency, distribution uniformity, and comprehensive irrigation performance by 11.3%, 10.7%, and 11.0%, respectively. A sensitivity analysis indicates that the proposed system maintains a satisfactory irrigation performance for all scenarios of variations in natural parameters, flow rates, and border length. Due to its satisfactory irrigation performance, robustness, facile operation, and economical merit compared with traditional real-time control irrigation systems, the proposed system has the potential to be widely applied. Full article

The carbon (C) cycle in inland waters, including carbon concentrations in and carbon dioxide (CO₂) emissions from water surfaces, are at the forefront of biogeochemical studies, especially in regions strongly impacted by ongoing climate change. Towards a better understanding of C storage, transport and emission in Central Asian mountain regions, an area of knowledge that has been extremely poorly studied until now, here, we carried out systematic measurements of dissolved C and CO₂ emissions in rivers and lakes located along a macrotransect of various natural landscapes in the Sayan–Altai mountain region, from the high mountains of the Western Sayan in the northwest of Tyva to the arid (dry) steppes and semideserts in the intermountain basins in the southeast of Tyva on the border with Mongolia. New data on major hydrochemical parameters and CO₂ fluxes (fCO₂) gathered by floating chambers and dissolved organic and inorganic carbon (DOC and DIC, respectively) concentrations collected over the four main hydrological seasons allowed us to assess the current C biogeochemical status of these water bodies in order to judge possible future changes under climate warming. We further tested the impact of permafrost, river watershed size, lake area and climate parameters as well as ‘internal’ biogeochemical drivers (pH, mineralization, organic matter quality and bacterial population) on CO₂ concentration and emissions in lakes and rivers of this region and compared them with available data from other subarctic and mountain settings. We found strong environmental control of the CO₂ pattern in the studied water bodies, with thermokarst lakes being drastically different from other lakes. In freshwater lakes, pCO₂ negatively correlated with O₂, whereas the water temperature exerted a positive impact on pCO₂ in large rivers. Overall, the large complexity of counteracting external and internal drivers of CO₂ exchange between the water surfaces and the atmosphere (CO₂-rich underground DIC influx and lateral soil and subsurface water; CO₂ production in the water column due to dissolved and particulate OC biodegradation; CO₂ uptake by aquatic biota) precluded establishing simple causalities between a single environmental parameter and the fCO₂ of rivers and lakes. The season-averaged CO₂ emission flux from the rivers of Tyva measured in this study was comparable, with some uncertainty, to the C uptake fluxes from terrestrial ecosystems of the region, which were assessed in other works. Full article

Chronic diseases of the urogenital tract, such as bladder cancer, prostate cancer, reproductive disorders, and nephropathies, can develop under the effects of chemical hazards in the working environment. In this respect, nanosized particles generated as by-products in many industrial processes seem to be particularly dangerous to organs such as the testes and the kidneys. Nephrotoxicity of element oxide particles has been studied in animal experiments with repeated intraperitoneal injections of Al₂O₃, TiO₂, SiO₂, PbO, CdO, CuO, and SeO nanoparticles (NPs) in total doses ranging from 4.5 to 45 mg/kg body weight of rats. NPs were synthesized by laser ablation. After cessation of exposure, we measured kidney weight and analyzed selected biochemical parameters in blood and urine, characterizing the state of the excretory system. We also examined histological sections of kidneys and estimated proportions of different cells in imprint smears of this organ. All element oxide NPs under investigation demonstrated a nephrotoxic effect following subchronic exposure. Following the exposure to SeO and SiO₂ NPs, we observed a decrease in serum creatinine and urea, respectively. Exposure to Al₂O₃ NPs caused an increase in urinary creatinine and urea, while changes in total protein were controversial, as it increased under the effect of Al₂O₃ NPs and was reduced after exposure to CuO NPs. Histomorphological changes in kidneys are associated with desquamation of the epithelium (following the exposure to all NPs except those of Al₂O₃ and SiO₂) and loss of the brush border (following the exposure to all NPs, except those of Al₂O₃, TiO₂, and SiO₂). The cytomorphological evaluation showed greater destruction of proximal sections of renal tubules. Compared to the controls, we observed statistically significant alterations in 42.1% (8 of 19) of parameters following the exposure to PbO, CuO, and SeO NPs in 21.1% (4 of 19)—following that, to CdO and Al₂O₃ NPs—and in 15.8% (3 of 19) and 10.5% (2 of 19) of indicators, following the exposure to TiO₂ and SiO₂ nanoparticles, respectively. Histomorphological changes in kidneys are associated with desquamation of epithelium and loss of the brush border. The cytomorphological evaluation showed greater destruction of proximal sections of renal tubules. The severity of cyto- and histological structural changes in kidneys depends on the chemical nature of NPs. These alterations are not always consistent with biochemical ones, thus impeding early clinical diagnosis of renal damage. Unambiguous ranking of the NPs examined by the degree of their nephrotoxicity is difficult. Additional studies are necessary to establish key indicators of the nephrotoxic effect, which can facilitate early diagnosis of occupational and nonoccupational nephropathies. Full article

The soils of uplands and partially isolated landforms located in the central Volga region were investigated in terms morphology, diversity and geogenic factor specificity. The Samarskaya Luka area is characterized by extreme spatial inhomogeneity and contrast of geogenic (lithological and topographic) conditions, and at the same time is located on the ecotone-transitional border of several natural zones. This territory is a part of two federal protected areas because of its peculiar nature. It is established that the diversity of geogenic (geological and topographic) conditions leads to the differentiation of the soil cover. Key soil types are presented by Leptosols, Cambisols, Retisols, Chernozems, Fluvisols and Technosols. By the example of the recognized upland macrolandscape, it is shown that the usual gradual course of soil zonation significantly changes due to the transformation of the soil-forming potential of the environment. The obtained data can be used for further regional verification of soil taxonomy. In addition, since the role of parent materials increases as they move from the west to the east of the East European Plain, parameterization of the role of this process becomes particularly important. Information about the diversity of chemical parameters and the granulometric composition of the key soil types of the studied area is also given. Full article

This research presents a computational investigation of the thermal convection of a heat-generating liquid having variable viscosity in a semi-cylindrical cavity. The analysis is carried out to obtain the time patterns of the average Nusselt number at the lower border of the chamber and understand the impact of the variable viscosity, the Prandtl number, and the Rayleigh number on this parameter. The natural convection in the cavity is defined by the set of non-dimensional equations based on the Boussinesq approach employing the non-primitive parameters such as vorticity and stream function. These governing equations are worked out numerically based on the finite difference technique. The time dependencies have been obtained at the Rayleigh number equal to 10⁴, 10⁵, and 10⁶ and the Prandtl number taking values of 7.0, 70, and 700. The results obtained for variable and constant viscosity have been compared. Additionally, the paper represents maps of isotherms and streamlines for the mentioned values of the Rayleigh number. The influence of variable viscosity on the parameters of natural convection is poorly studied in closed systems; therefore, this research gives necessary data to understand the general time nature of the average Nusselt number at cooling surface of various parameters. Additionally in this research, the model for simulating the natural convection in non-primitive variables is presented in polar coordinates when the dynamic viscosity varies with temperature. The computational model designed could be used to simulate the free convection in systems with inner heat production such as chemical reactors, inductive metal melting facilities, or corium in-vessel retention to analyze the impact of various factors on the parameters of the natural convection in such systems. Full article