Institute of Chemistry
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Item type:Publication, Pharmacokinetics of different selenium supplements in healthy individuals and patients with autoimmune thyroiditis after oral administration(Society of Chemists and Technologists of Macedonia, 2025-06-24); ; ; Stafilov, TrajčeSelenium is essential for the function of key selenoproteins such as glutathione peroxidase, thiore-doxin reductase, and iodothyronine deiodinase, which have antioxidant properties and support thyroid hormone metabolism. Due to the low selenium content in European soils – particularly in the Southeast-ern regions, supplementation is often recommended, especially for conditions like Hashimoto's thyroidi-tis. However, careful consideration of selenium dosage and pharmacokinetics is crucial, as the margin be-tween essential and toxic levels is very narrow. The aim of this study was to investigate the pharmacoki-netics of selenium absorption and plasma concentration following oral administration of various selenium doses and chemical forms, both in the short and long term, in healthy individuals and patients with auto-immune thyroiditis. Selenium concentrations in blood plasma were measured using electrothermal atomic absorption spectrometry (ETAAS). The study found that L-selenomethionine is absorbed more efficiently than inorganic sodium selenite, with peak plasma concentrations reached and sustained within 6 – 8 hours. Selenium levels remained elevated 48 hours after ingestion compared to baseline. At a daily dose of 200 μg of selenium as L-selenomethionine, plasma selenium concentrations increased by approximate-ly 30 %, and by about 25 % at 100 μg/day, relative to the initial value. Long-term studies showed that plasma selenium concentrations rose significantly after the first month of supplementation, with a slower increase in subsequent months. After supplementation ended, selenium levels declined rapidly. Interest-ingly, no significant differences in selenium absorption or excretion were observed between patients with Hashimoto's thyroiditis and healthy controls. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Infrared and Raman spectra of racemic ibuprofen sodium dihydrate – Spectra-structure correlations(Elsevier BV, 2025-10); Koleva, V. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Unmasking the Aliphatic Repertoire: New Polyunsaturated Metabolites in Bupleurum falcatum sensu lato Provide Chemotaxonomic Insights(MDPI AG, 2025-05-10); Radulović, Niko S.Bupleurum falcatum (Apiaceae) sensu lato includes multiple infraspecific taxa with longstanding taxonomic ambiguities, often resulting from incomplete morphological and chemical characterizations. Herein, diethyl ether extracts were analyzed from four Balkan populations that were tentatively identified as B. falcatum subsp. falcatum (syn. B. falcatum) and B. falcatum subsp. cernuum (syn. B. sibthorpianum). Comprehensive chro-matography and spectroscopic techniques (GC-MS and 1D/2D NMR) enabled the iso-lation of several newly identified aliphatic polyunsaturated esters, including com-pounds bearing uncommon conjugated tetraene and triyne backbones. These novel structures differ from canonical falcarinol derivatives by lacking the usual 3-hydroxylation, suggesting a divergent branch in the crepenynate pathway. The chemical profiles of each sample correlated closely with leaf morphology and infra-specific designations: for example, the Galičica Mt. population of B. falcatum featured a unique newly detected heptadecadientriyne, while the populations from Šar Planina and Suva Planina displayed distinct polyunsaturated repertoires. Extracts from B. sibthorpianum likewise contained stereoisomeric compounds that highlight metabolic divergence. Collectively, these findings demonstrate significant chemotypic variation within the Bupleurum falcatum complex and provide the first account of less-polar sec-ondary metabolites, including newly discovered polyunsaturated metabolites. Future research integrating molecular markers and bioactivity assays may elucidate how these specialized metabolites contribute to both the taxonomy and pharmacological potential of these understudied taxa. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, 2T2D-correlation analysis of infrared specular reflectance and ratio-reflectance spectra for investigating siloxane nanofilms on silicate glass substrates(Elsevier BV, 2025-08); Mayerhöfer, Thomas G. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Elementary, my dear Watson! The making of a collection of the natural elements(Society of Chemists and Technologists of Macedonia, 2022-06-21); <jats:p>A unique collection of samples of the chemical elements has been created and displayed at our Institute of Chemistry. Although whole collections are now commercially available, we decided to use, as much as possible, samples from local resources. The general idea was for each item to have a story, making it more interesting for the students and visitors. We were able to acquire elemental samples mined in Macedonia. Other samples were from our student and research labs, as well as donations from colleagues, and the rest were obtained from commercial sources. A web page was created with all the information on each sample, some of them containing videos. Next to the noble gases, mini Tesla coils were mounted to light up the gases.</jats:p> - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Facile Synthesis of Cu<sub>x</sub>S Electrocatalysts for CO<sub>2</sub> Conversion into Formate and Study of Relations Between Cu and S with the Selectivity(Wiley, 2024-10-25); Koleva, Violeta<jats:title>Abstract</jats:title><jats:p>The conversion of CO<jats:sub>2</jats:sub> into formate (HCOO<jats:sup>−</jats:sup>), a techno‐economically feasible product, can be achieved using earth‐abundant Cu<jats:sub>x</jats:sub>S electrocatalysts, but questions remain regarding how catalyst structure, composition, and reaction environment influence product selectivity. A novel synthesis method based on electrodeposition of Cu foam and its subsequent sulfidation via immersion in sulfur saturated toluene solution resulted in Cu<jats:sub>x</jats:sub>S foams. Catalytic activity studies found that HCOO<jats:sup>−</jats:sup> selectivity is dependent on electrochemical activation at higher overpotentials. To understand the effects of activation, determine the active forms of the catalysts, and identify the role of sulfur, the electrodes are carefully characterized as well as gaseous and sulfur dissolved in electrolyte. This included study of the effects of intentional addition of solution sulfur species, identification of the sulfur loss, determination of the electrode composition and relating sulfur speciation to observed product selectivity. It is found that residual sulfur stabilizes Cu<jats:sup>+</jats:sup> during electrolysis at potentials favoring HCOO<jats:sup>−</jats:sup> production, in contrast to pristine Cu that undergoes complete reduction and shows poor HCOO<jats:sup>−</jats:sup> selectivity. Sulfur in both the catalyst and dissolved in electrolyte are of dynamic nature, and surface residues of SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup> species are identified in all activated catalysts which correspond with enhanced HCOO<jats:sup>−</jats:sup> production.</jats:p> - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Upcycling of plastic waste into multi-walled carbon nanotubes as efficient organic dye adsorbent(Slovenian Chemical Society, 2025-03-03); ; Kovačič, SebastijanMulti-walled CNTs with an average diameter of about 80 nm, a length of several micrometers and surface area (SBET) of 100 m2 g-1 were obtained by pyrolysis of low-density polyethylene waste. The potential of the resulting MWCNTs material to purify water containing organic dyes was tested with Bezaktiv Blau HE-RM (BB) and Bezaktiv Rot S-3B (BR) reactive dyes. 200 mg L-1 MWCNT material was used to follow the adsorption of 30 mg L-1, 40 mg L-1, 50 mg L-1 and 60 mg L-1 BB and BR at pH 3 and a temperature of ~25 oC. The results have shown that this material has a high potential as a sorbent, and its adsorption capacity of 257 mg g-1 (for Bezaktiv Blau HE-RM) and 213 mg g-1 (for Bezaktiv Rot) is close to some commercial MWCNTs and functionalized MWCNT-based adsorbents. The adsorption process was very fast, reaching 80-90 % of the dye removal in 10-15 minutes, and the equilibrium time was reached in 40-60 minutes. The adsorption isotherm showed that the Langmuir model was more suitable than the Freundlich model for describing the adsorption properties of the pollutants. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Infrared and Raman spectra of racemic ibuprofen sodium dihydrate – Spectra-structure correlations(Elsevier BV, 2025-10) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Centrosymmetric or non-centrosymmetric space group for Ca2KH7(PO4)4·2H2O and Ca2(NH4)H7(PO4)4·2H2O: Second harmonic generation and vibrational spectroscopy studies(Elsevier BV, 2025-04) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Мultivariate analysis for rapid screening and prediction of solid-state compatibility in pharmaceutical preformulation studies-paving the road for machine learning(Society of Chemists and Technologists of Macedonia, 2024-05-19)
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