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.
Red mud, byproduct of the aluminum industry, poses a significant environmental problem due to its chemical composition and the large quantities generated. This study explores the potential for its valorization through a multi-step process that includes reduction, leaching with acid solution, purification, and ultrasonic spray pyrolysis (USP). In the first step, red mud undergoes carbothermal reduction, during which metal oxides are transformed into metal phase and slag. In the second step, the slag is subjected to leaching under various conditions, including changes in pressure, temperature, and acid concentration, which allows the recovery of titanium in the form of titanium oxysulfate and other metals. Finally, after purifying the solution using precipitation or solvent extraction, ultrasonic spray pyrolysis is used to synthesize titanium dioxide (TiO₂) nanopowders from titanium oxysulfate (TiOSO₄). This integrated approach not only reduces waste but also produces high-value materials with broad industrial applications.
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.
TIG welding is used when a good weld appearance and a highest quality of the weld are required Nevertheless, the process has also some major disadvantages like relatively shallow penetration capability and low productivity. To increase the penetration and/or productivity, instead of traditional pure Ar, gas mixtures containing gases with high thermal conduction can be used. For austenitic stainless steels, as they are not prone to hydrogen cracking, also H2 is suitable. As H2 is active gas, the process is called Tungsten Active Gas (TAG). In this research, austenitic stainless steel sheet was welded with a competitive welding speed of 40 cm min−1, with pure argon and with Ar+7.5 H2 mixture. With pure Ar, a welding current of 220 A was far too small to reach full penetration in 3 mm sheet. With the 7.5 H2 active gas mixture, only 130 A was sufficient with unchanged welding speed.
Background: Tuberous Sclerosis Complex (TSC) is an autosomal dominant genetic disorder and involves multiple organs, intellectual disability and epilepsy. Mutations in TSC1 and TSC2 genes are responsible for the molecular disease mechanism. Objective: The aim is to determine molecular background of a patient with a suspicion of TSC. Case presentation: In this case report, we describe a seven year old patient with the clinical manifestation of TSC that includes supratentorial changes, subependymal hamartomas and angifibromas in the facial area. Besides the brain and skin changes, no other TSC characteristics were observed. The patient was referred to molecular genetic testing using Next Generation Sequencing (NGS). Results: Clinical exome sequencing revealed intronic TSC2 c.4849+2T>G variant. The variant was confirmed using Sanger sequencing on the subject. However, the variant was not detected in the parents, which indicated that it arose de-novo. The RegSNP-intron, Mutation Taster and Human Splicing Finder were used as a bioinformatic tools to predict the possible effect on protein. Using bioinformatic tools, it was determined that the variant is possibly damaging to protein. Conclusion: This data suggest that observed splicing intronic variant could be the cause of TSC in this pediatric patient.
The research assessed the level of physical activity (PA) of boys and girls aged 11-14, as well as trends in PA levels. The sample included a total of 433 children aged 11-14, comprising 238 boys and 195 girls. PA was assessed using the FELS questionnaire, which included questions about the frequency of PA in sports, PA during leisure time, PA at home, and overall PA. To determine the trend in PA levels across specific domains and overall, trend analysis was applied, followed by comparisons using the LSD Post Hoc Test. Data were processed using the SPSS statistical package (p < .05). The results showed that boys had significantly higher levels of PA across all periods compared to girls. Significant changes in PA levels among boys were observed in the domain of PA in sports (Sig. = < .001) and overall PA (Sig. = .008). A significant decline in PA in sports among boys was noted between the ages of 11 and 13, as well as between 11 and 14 years, while the decline in overall PA was observed between the ages of 11 and 13. Among girls, a decline in PA in the domain of household chores was identified between the ages of 11 and 14. In the domain of overall PA, significant decreases were observed between the ages of 11 and 13, 11 and 14, 12 and 13, and 12 and 14. It was found that PA among children aged 11-14 significantly decreases around the ages of 12 and 13. Efforts should focus on promoting PA within this population group and identifying appropriate strategies to increase or at least maintain PA levels during this critical period.
Background: The scientific researchers have the role of interacting through published articles in scientific journals or presentations at scientific and professional conferences where they can affect the practices that can make achievements to society and country. or worldwide. Objective: The aim of this article was to describe bibliometric indexes and explained its importance for its evaluation and measuring quality assessment of published papers in scientific journals and advantages and disadvantages of current bibliometric portals for creating the list of universities and its academic staff by counts of deposited articles in databases and number of its citations. Methods: The author searched the most influential online databases and analyzed deposited papers by bibliometric indexes, and used a descriptive method to review important facts about bibliometrics experiences in scientific and academic practice. The author used facts deposited on the main international portals for analyzing number of citations of deposited scientific papers on Scopus and Google Scholar platform–h–Index and i10-Index and number of citations as basic data for created top list of most citated scientists in almost of all countries in the world. Results and Discussion: Bibliometric methods are used for quantitative analysis of written materials. Citation is influenced by: article quality, understanding of the article, language in which the article is written, loyalty to a group of researchers, article type, etc. Some indicators used in evaluating scientific work are Impact factor (IF); Citation of the article; Journal citations; Number and order of authors, etc. The index factor of influence depends on the quality of the journal, the language in which it was printed, the area it covers, and the journal distribution system. The portals and its platforms: Webometrics, “AD Scientific Index” and Stanford Bibliometric List are not fully relevant for measuring quality assessment of universities and its academic staff. Conclusion: Current academies and academicians can propose criteria how improve indexing scientific papers with the consultation of scientific bodies and experts at universities in one country, selected regions, or worldwide. These criteria should be necessary for quality assessment of the scientific curriculum of scientists and their published papers in scientific journals.
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.
Background: MitoWizz is an advanced bioinformatics tool designed for the analysis of the human mitochondrial genome, offering precise and efficient data interpretation. It enables comparisons of sequencing results obtained from various instrumental methods with the reference Andersen genome (rCRS), aiding in the identification of alterations. This capability is particularly valuable in forensic and clinical mitochondrial DNA analysis. Objective: The primary goal of developing MitoWizz is to automate and streamline mitochondrial DNA analysis, providing researchers and forensic experts with a fast, reliable, and comprehensive tool for sequence comparison, variation detection, and data validation. Methods: MitoWizz compares query sequences in opposed to the reference genome and allows direct comparison of two sequences to identify genetic variations. To ensure accuracy, the results are validated through the Clustal Omega W by aligning sequences with the human mitochondrial DNA reference from GenBank (NC_012920.1). Results: The software detected genetic variations and generated a visual report, as demonstrated in an analysis where 11 mutations were identified in various genes, with an 88% sequence identity to the reference genome. The accuracy of the detected alterations was further validated using the Omega Clustal W program. Conslusion: MitoWizz significantly reduces analysis time and enhances result reliability by integrating multiple analytical steps into a single platform. By automating mtDNA comparisons and validation, it provides forensic and research laboratories with a high-throughput, efficient solution for precise mitochondrial genome analysis.
Background: Tranexamic acid can prevent death from bleeding after trauma and postpartum hemorrhage. Objective: The aim of the paper was to assess whether tranexamic acid reduces hematoma expansion and improves outcome in adults with stroke caused by intracerebral hemorrhage. Case presentation: Administration of Tranexamic acid in a patient after a diagnosis of intracerebral hematoma, which occurred after coronary stent implantation. Intracerebral hematoma, or neurological deficit, occurs one day after cardiac surgery in the patient. The case report will present the radiological resolution of the intracerebral hematoma, as well as the improvement of the clinical picture, neurological deficit, in the patient during a one-month follow-up, after the administration of Tranexamic acid. Conclusion: Tranexemic acid is affordable, easy to administer, appears to be safe, and is widely available, so even a modest treatment effect can have an important global impact, and it is necessary to consider its more frequent use, as well as to initiate larger randomized trials.
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.
Nema pronađenih rezultata, molimo da izmjenite uslove pretrage i pokušate ponovo!
Ova stranica koristi kolačiće da bi vam pružila najbolje iskustvo
Saznaj više