Properties of concrete containing the ground calcined low-kaolinite clay was experimentally studied. Clay, calcined at 900 and 1000°C, was used as a partial replacement of cement at dosage of 20 % by the weight of cement. Tests performed on concrete samples include the consistency, air content, compressive strength and flexural strength. The experimental results show a moderate decrease in slump, as well as in compressive and flexural strength comparing to concrete containing only cement CEM I as a binder. Better results were obtained with concrete containing clay calcined at 1000°C. Further research is needed to determine the optimal dosage of calcined clay in concrete, as well as the optimal temperature of clay calcination.

Introduction: Metacognition, which refers to the ability to oversee and regulate one's cognitive activities, plays a crucial role in medical education. Evaluating metacognitive awareness is particularly important for university students, as it impacts their learning strategies and academic performance. The objective of this study was to examine the psychometric characteristics of the Serbian adaptation of the Metacognitive Awareness Inventory (MAI), with an emphasis on its construct validity and internal consistency. Materials and methods: This was a cross-sectional study conducted at the Faculty of Medicine University of Belgrade, on third-year medical students during October 2024. The psychometric properties of the Serbian version of the MAI were evaluated by assessing its factorial structure and internal consistency. The MAI consists of 52 items, comprising two primary components: 'Knowledge of Cognition' and 'Regulation of Cognition'. The subcomponent of "knowledge of cognition" were categorized into declarative knowledge, procedural knowledge, and conditional knowledge, whereas "regulation of cognition" subcomponent were classified into planning, information management strategies, comprehension monitoring, debugging, and evaluation. Results: A total of 426 medical students were included in the study. The mean age of the respondents was 21.3 ± 1.4 years, and the majority were females (68.5%). The mean score of the scale was 199.0. The internal consistency analysis of the Serbian version of the MAI questionnaire yielded a Cronbach's a of 0.94, and a McDonald's o of 0.95 for the entire scale, which indicates excellent scale reliability. The Serbian version of the MAI questionnaire was validated using confirmatory factor analysis, supporting both the hypothesized eight-factor and two-factor structures. The eight-factor model showed good fit indices (IFI = 0.908, CFI = 0.905, RMSEA = 0.042), with statistically significant factor loadings (p < 0.05). Similarly, the two-factor model demonstrated adequate fit (IFI = 0.921, CFI = 0.918, RMSEA = 0.039), with all loadings also significant (p < 0.05). Conclusion: The present study revealed the Serbian version of MAI as reliable and valid tool for identifying medical students' metaconginive awareness.

This paper aims to compare the mechanical and structural properties of butt-welded properties of dissimilar aluminum alloys 2024-T351 and AA 6082-T6 obtained by MIG and TIG welding processes. Alloy AA 6082 T6 is well weldable by classic fusion welding processes (MIG and TIG), while alloy 2024-T351 is almost non-weldable. For the welding of these two different Al alloys, MIG and TIG welding procedures were used on 8 mm thick sheet metal using additional material 4043A (AlSi5) and a mixture of argon and helium as a protective gas for the MIG welding process, or pure argon for the TIG welding process. The paper compares the mechanical properties of welded joints obtained by MIG and TIG welding. The microstructural evolution of the welded joint of dissimilar aluminum alloys AA6082-T6 and AA2024-T351 is compared. The mechanical properties of welded joints of dissimilar aluminum alloys are compared based on the results of Vickers hardness tests, tensile and bending tests of welded samples.

Proper nutrition is important for the healthy growth and development of preschool children. During this period, they undergo rapid physical, cognitive, and emotional changes, making it essential to provide both the necessary nutrients to support their overall development and hygienically safe foods. Maintaining high sanitary and hygienic standards in preschool food facilities requires a comprehensive approach that integrates regulatory compliance, facility design, staff training, and effective sanitation practices. By prioritizing these standards, preschools can provide a safe and healthy environment that supports the well-being and development of preschool children. Regulatory requirements form the backbone of sanitation standards in preschools. These guidelines are often established by public health authorities and childcare regulators, setting out minimum standards for cleanliness, food handling, and facility maintenance. Adherence to these regulations ensures that preschools provide a safe and healthy environment for children. Essential components include proper kitchen design, adequate ventilation, pest control measures, and accessible handwashing facilities. Assessing the effectiveness of hygiene practices in preschools involves a multi-pronged approach, including regular inspections, health monitoring, feedback collection, staff training assessments, and incident analysis. By continuously evaluating and improving hygiene practices, preschools can provide a safe and healthy environment for children.

The aim of the study is to assess the frequency of clinical manifestations of nutritional allergies. This research was designed as a cross-sectional study conducted in the preschool institution "Dr Sima Milosevic". A specially created questionnaire for parents was used for the research. The questionnaire collected data that may have a direct or indirect significance on the occurrence of nutritional allergies. Descriptive and analytical statistical methods were used in statistical data processing. Of the total number of children, 41 children, or 1% of children, have nutritional allergies. The most common symptoms are related to skin changes (53.7%), changes on the lips (22%) and diarrhea (17.1%). Most children, 92.7%, do not have an anaphylactic manifestation of allergy, while 7.3% have an anaphylactic manifestation of allergy. Two children are allergic to eggs and have an anaphylactic manifestation of allergy, and one child is allergic to peanuts. Most children (11) who are allergic to milk have skin changes, i.e. atopic dermatitis, four children have changes on the lips, and four children have problems with the digestive tract, i.e. diarrhea. Three children who are allergic to wheat flour only have digestive tract symptoms, i.e. diarrhea. Early detection of nutritional allergies and preventive measures that are applied to reduce exposure to allergens by implementing an elimination diet and avoiding allergens from the environment can mitigate the consequences of nutritional allergies.

One of the tasks of mathematics education is to develop students' logical thinking. Logical problems that require a certain level of sharpness, ingenuity, and rational reasoning present a good challenge that can further motivate students to engage with mathematics. The progress of science and technology has led to the emergence of numerous tools that can be used in mathematics education. With the advent of artificial intelligence, these tools got a more active role as communication with users reached a new user-friendly dimension resembling human-to-human interaction. The unpredictability of the flow and the speed of development of artificial intelligence raises the question of whether it will ever reach or surpass the level of human sharpness and ingenuity. This paper illustrates inaccurate and partially accurate reasoning of artificial intelligence in solving logical problems.

This paper aimed to examine specific factors that influence and have prognostic power on the profitability of selected insurance companies in the Republic of Serbia. Panel data were used for four insurance companies operating in the Republic of Serbia from 2013 to 2022, to estimate a linear model between the determinants that are theoretically expected to affect the performance and profitability of insurance companies. The findings of the paper revealed that company size according to all three methods (method of least squares, method of fully modified least squares, and robust method of least squares) has a significantly positive influence on the profitability of insurance companies. Also, the growth rate of the premium according to the fully modified least squares method has a positive (significant) impact on the profitability indicator, i.e. ROA. Seen from the other side, the weakest i.e., negative (significant) impact on the profitability of insurance companies in the Republic of Serbia was achieved by the independent variable expense ratio.

The research was conducted in the area of Northern Serbia. The lowland hygrophilous forests of Gornji Srem where pedunculate oak is the dominant tree species were studied. In the paper was investigated the content of essential and non-essential heavy metals (Cu, Zn, As, Mn, Co, Pb, Ni, Cd) on two different soil types: hydromorphic (fluvisol) and automorphic (chernozem). Three experimental plots were analyzed on each soil type. Soil loading with heavy metals was studied by soil horizons. Based on the obtained results, it was established that the concentrations of all elements are within the allowed concentrations, except for nickel (Ni), whose values on some experimental plots and horizons exceed the maximum allowed concentrations. Content of all investigated elements are higher on fluvisol, except for As, whose amount is similar on both soil types. The obtained results indicate that the loading of heavy metals in both soil types is within the allowed limits and there is no significant negative impact on the development and production characteristics of the forest ecosystems located in researched area.

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