101. Influence of curing / drying methods including microwave heating on alkali activation of waste casting coresBarbara Horvat, Vilma Ducman, 2021, published scientific conference contribution Abstract: Within previous investigation alkali activation of waste casting cores at room temperature did not give promising results, i.e. when the precursor was gently ground and sieved below 600 %m the alkali activated material fell apart at demolding, and when the precursor was ground below 90 %m, the alkali activated material did not solidify in more than 2 years. , Therefore different drying/curing methods were applied to enhance the reaction. Waste casting cores were prepared in two granulations (sieved below 600 %m and below 90 %m), activated with Na -water glass and 10 M NaOH, cured at different temperatures (70 °C and room temperature), and subsequently cured/dried at three different conditions: room temperature, 110 °C, and irradiated with microwaves. The highest compressive strength, 25 MPa, was gained with subsequent curing/drying at 110 °C. The lowest density, 0.5 kg/l, with compressive strength above 3 MPa, was achieved with subsequent curing/drying with microwaves .
Keywords: waste casting cores, alkali activation, curing, drying, microwaves, mechanical strength
Published in DiRROS: 22.01.2024; Views: 273; Downloads: 143
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103. p53 - the paradigm of tumor-suppresor genes?Barbara Jezeršek Novaković, Srdjan Novaković, 1998, review article Abstract: p53 is a tumor-suppressor gene the alterations of which are among the most frequent genetic changes detected in human neoplasms. Its product - p53 protein is a component of several biochemical pathways that are central to carcinogenesis: DNA transcription, genomic stability, DNA repair, cell cycle control, and apoptosis. The analysis of the spectrum of p53 mutations and insight into the p53 mediated biochemical pathways of programmed cell death and cell cycle arrest, provide clues to understanding of molecular pathogenesis of cancer of mechanisms related to p53 mediated tumor suppression. The purpose of the resent article is to summarise the most important facts concerning p53 since understanding of the above listed processes might provide the potential molecular targets for the development ofa rational cancer treatment.
Published in DiRROS: 19.01.2024; Views: 208; Downloads: 54
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107. Exploration of macromolecular phenotype of human skeletal muscle in diabetes using infrared spectroscopyBarbara Zupančič, Chiedozie Kenneth Ugwoke, Mohamed Elwy Abdelmonaem, Armin Alibegović, Erika Cvetko, Jože Grdadolnik, Anja Šerbec, Nejc Umek, 2023, original scientific article Abstract: Introduction: The global burden of diabetes mellitus is escalating, and more efficient investigative strategies are needed for a deeper understanding of underlying pathophysiological mechanisms. The crucial role of skeletal muscle in carbohydrate and lipid metabolism makes it one of the most susceptible tissues to diabetes-related metabolic disorders. In tissue studies, conventional histochemical methods have several technical limitations and have been shown to inadequately characterise the biomolecular phenotype of skeletal muscle to provide a holistic view of the pathologically altered proportions of macromolecular constituents. Materials and methods: In this pilot study, we examined the composition of five different human skeletal muscles from male donors diagnosed with type 2 diabetes and non-diabetic controls. We analysed the lipid, glycogen, and collagen content in the muscles in a traditional manner with histochemical assays using different staining techniques. This served as a reference for comparison with the unconventional analysis of tissue composition using Fourier-transform infrared spectroscopy as an alternative methodological approach. Results: A thorough chemometric post-processing of the infrared spectra using a multi-stage spectral decomposition allowed the simultaneous identification of various compositional details from a vibrational spectrum measured in a single experiment. We obtained multifaceted information about the proportions of the different macromolecular constituents of skeletal muscle, which even allowed us to distinguish protein constituents with different structural properties. The most important methodological steps for a comprehensive insight into muscle composition have thus been set and parameters identified that can be used for the comparison between healthy and diabetic muscles. Conclusion: We have established a methodological framework based on vibrational spectroscopy for the detailed macromolecular analysis of human skeletal muscle that can effectively complement or may even serve as an alternative to histochemical assays. As this is a pilot study with relatively small sample sets, we remain cautious at this stage in drawing definitive conclusions about diabetes-related changes in skeletal muscle composition. However, the main focus and contribution of our work has been to provide an alternative, simple and efficient approach for this purpose. We are confident that we have achieved this goal and have brought our methodology to a level from which it can be successfully transferred to a large-scale study that allows the effects of diabetes on skeletal muscle composition and the interrelationships between the macromolecular tissue alterations due to diabetes to be investigated.
Keywords: diabetes mellitus, skeletal muscle, metabolism, macromulecular composition, infrared spectroscopy, multivariate analysis, histochemical assays
Published in DiRROS: 11.01.2024; Views: 367; Downloads: 114
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110. Heavy minerals as indicators of source material in soils on carbonatesBarbara Čeplak, Miloš Miler, Nina Zupančič, Simona Jarc, 2023, original scientific article Abstract: The origin of the soils formed on carbonate rocks remains uncertain, as they are probably of polygenetic origin. Of particular interest are the elevated contents of some trace elements detected in these soils, as they can hardly be attributed to insoluble residues of carbonate rock. The aim of this study was to uncover the relationship between heavy minerals in bedrock and soil and to identify other sources that influence the mineral and chemical composition of soil. We investigated representative samples of soils and dolomite bedrock as well as sandstones and marlstones from the nearby flysch basin as an expected source of the aeolian contribution. XRD and SEM/EDS showed that mineral diversity is higher in soils compared to the dolomites. Heavy minerals found in dolomite insoluble residue include sphalerite, Ti-oxide (probably rutile), zircon, fluorite, pyrite, minerals of REE phosphates and apatite group, interpreted as terrigenous detrital material. The mineral composition of soil heavy fraction is only partly following insoluble residues of bedrock and indicates possible aeolian contribution. Comparison with nearby flysch sandstones and marlstones showed similarities in mineralogical diversity by the presence of chromite and Fe-Cr(Mn) oxides (probably carmichaelite). Other minerals present in soils and flysch layers, such as Ti-oxide (probably rutile), zircon, REE phosphates, and pyrite grains, however, show similarities in mode of occurrence and transport indications. Signs of aeolian transport on the grains detected in soils were further confirmed by SEM/EDS.
Keywords: Phaeozem, Upper Triassic dolomite, flysch layers, trace elements, SEM/EDS
Published in DiRROS: 04.01.2024; Views: 297; Downloads: 64
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