New approaches to the study of maturation changes of organic matter in humic coals

У овој дисертацији су проучаване матурационе промене органске супстанце хумусних угљева, почев од касне дијагенезе до полуантрацитског степена карбонификације, што одговара опсегу рефлексије витринита (Rr)= 0.4-1.8 %. Сазревање органске супстанце је симулирано пиролизом узорака мрког (Rr = 0.42 %) и каменог угља (Rr = 0.56 %) из Боговинског угљоносног басена. Пиролиза је изведена у затвореном систему, на температурама од 250 и 400 °C ...This thesis investigates the maturation changes of organic matter in humic coals, starting from the late diagenesis up to the semianthracite stage of carbonification, which corresponds to the vitrinite reflectance (Rr) range of 0.4-1.8 %. Organic matter maturation was simulated by the closed-system pyrolysis at 250 and 400 °C, conducted on a subbituminous (Rr = 0.42 %) and a bituminous coal (Rr = 0.56 %) from the Bogovina coal basin. The changes in kerogen and bitumen were analyzed. Vitrinite contents continually increase within 0.4-1.8 % Rr range. Sporinite, resinite, suberinite, and alginite are the most reactive liptinite macerals. The most important liquid products of their thermolysis are n-alkanes, n-alkylbenzenes, n-alkylthiophenes, and n-alkylbenzo[b]thiophenes. Liptinites substantially degrade at 400 °C (Rr = 1.8 %), producing primarily n-alkanes. Inertinite contents increase up to Rr = 0.8 %, followed by a slight decrease in Rr = 0.8-1.8 % maturation range. The distributions of various compounds in pyrolysis oil indicate a substantial increase in thermal maturity, particularly at Rr = 1.8 %. The oils obtained at 400 °C show the petroleum-type distribution of hydrocarbons. The applicability of maturity parameters was determined in 0.4-1.8 % Rr range. A new maturity parameter, having a good sensitivity in this wide maturity range, is defined based on the distribution of methylfluorenes. Coal asphaltenes were investigated by pyrolysis, in the same manner as humic coals, and by mild oxidation methods. The pyrolysis at 400 °C and the mild oxidation of asphaltenes increase the maturity level. Hence, the oil obtained at 250 °C most closely resembles bitumen, particularly in low rank coals. Coal asphaltenes have a greater hydrocarbon generation potential than coal kerogen. A new series of biomarkers was discovered (C33-C35 31-methylbenzohopanes) and their application in correlation studies was defined

Allium Species in the Balkan Region—Major Metabolites, Antioxidant and Antimicrobial Properties

Ever since ancient times, Allium species have played a significant role in the human diet, in traditional medicine for the treatment of many ailments, and in officinal medicine as a supplemental ingredient. The major metabolites of alliums, as well as their antioxidant and antimicrobial properties, with an emphasis on the species most represented in the Balkan region, are discussed in this review. Due to its richness in endemic species, the Balkan region is considered the genocenter of alliums. There are 56 recorded Allium species in the Balkans, and 17 of them are endemic. The most common and well-studied Allium species in the Balkans are A. cepa (onion), A. sativum (garlic), A. ampeloprasum (leek), A. schoenoprasum (chives), A. fistulosum (Welsh onion), and A. ursinum (wild garlic or bear’s garlic), which are known for their pungent taste and smell, especially noticeable in garlic and onion, and attributed to various organosulfur compounds. These plants are valued for their macronutrients and are used as desirable vegetables and spices. Additionally, phytochemicals such as organosulfur compounds, phenolics, fatty acids, and saponins are associated with the antioxidant and antimicrobial properties of these species, among many other bioactivities. All parts of the plant including the bulb, peel, clove, leaf, pseudostem, root, flower, and seed exhibit antioxidant properties in different in vitro assays. The characteristic phytocompounds that contribute to the antimicrobial activity of alliums include allicin, ajoene, allyl alcohol, and some diallyl sulfides. Nanoparticles synthesized using Allium species are also recognized for their notable antimicrobial properties. © 2023 by the authors

New approaches to the study of maturation changes of organic matter in humic coals

У овој дисертацији су проучаване матурационе промене органске супстанце хумусних угљева, почев од касне дијагенезе до полуантрацитског степена карбонификације, што одговара опсегу рефлексије витринита (Rr)= 0.4-1.8 %. Сазревање органске супстанце је симулирано пиролизом узорака мрког (Rr = 0.42 %) и каменог угља (Rr = 0.56 %) из Боговинског угљоносног басена. Пиролиза је изведена у затвореном систему, на температурама од 250 и 400 °C ...This thesis investigates the maturation changes of organic matter in humic coals, starting from the late diagenesis up to the semianthracite stage of carbonification, which corresponds to the vitrinite reflectance (Rr) range of 0.4-1.8 %. Organic matter maturation was simulated by the closed-system pyrolysis at 250 and 400 °C, conducted on a subbituminous (Rr = 0.42 %) and a bituminous coal (Rr = 0.56 %) from the Bogovina coal basin. The changes in kerogen and bitumen were analyzed. Vitrinite contents continually increase within 0.4-1.8 % Rr range. Sporinite, resinite, suberinite, and alginite are the most reactive liptinite macerals. The most important liquid products of their thermolysis are n-alkanes, n-alkylbenzenes, n-alkylthiophenes, and n-alkylbenzo[b]thiophenes. Liptinites substantially degrade at 400 °C (Rr = 1.8 %), producing primarily n-alkanes. Inertinite contents increase up to Rr = 0.8 %, followed by a slight decrease in Rr = 0.8-1.8 % maturation range. The distributions of various compounds in pyrolysis oil indicate a substantial increase in thermal maturity, particularly at Rr = 1.8 %. The oils obtained at 400 °C show the petroleum-type distribution of hydrocarbons. The applicability of maturity parameters was determined in 0.4-1.8 % Rr range. A new maturity parameter, having a good sensitivity in this wide maturity range, is defined based on the distribution of methylfluorenes. Coal asphaltenes were investigated by pyrolysis, in the same manner as humic coals, and by mild oxidation methods. The pyrolysis at 400 °C and the mild oxidation of asphaltenes increase the maturity level. Hence, the oil obtained at 250 °C most closely resembles bitumen, particularly in low rank coals. Coal asphaltenes have a greater hydrocarbon generation potential than coal kerogen. A new series of biomarkers was discovered (C33-C35 31-methylbenzohopanes) and their application in correlation studies was defined

Substrate preheating and structural properties of power plasma sprayed hydroxyapatite coatings

The aim of the present study was to investigate the influence of substrate preheating on the structural properties of hydroxyapatite coatings (HACs) deposited by using the high power (52 kW) laminar plasma jet. The deposition experiments were performed within the 20-200 degrees C temperature range at different stand-off distances. The structural properties in the thickness direction and at the surface of the HACs were investigated by using the micro-Raman spectroscopy, scanning electron microscopy coupled with energy dispersive spectrometry, and X-ray powder diffractometry. The deposition without the preheating of the substrate produced HACs with crystallinity gradient in the thickness direction. At the stand-off distance of 80 mm, the preheating of the substrate at 200 degrees C practically eliminated the crystallinity gradient. At distances from the coating/substrate interface shorter than similar to 100 mu m, the increase of crystallinity with the preheating of the substrate was dominantly attributed to the recrystallization of hydroxyl-rich ACP into HA. At longer distances and higher initial substrate temperatures ( gt 100 degrees C), the crystallinity changes were negligible, whereas the recrystallization of hydroxyl-deficient ACP into oxyapatite (OA) was also possible. The X-ray diffractometry indicated the deposition conditions under which a minimum residual stress was achieved. The results of the present study strongly suggested the relation between the ACP - gt HA remystallization process and the bonding strength of the HACs

Refinement of waste phosphogypsum from Prahovo, Serbia: characterization and assessment of application in civil engineering

Two samples collected from the phosphogypsum deposits of the chemical products industry Elixir Prahovo (Serbia) were subjected to a recrystallization experiment performed over several repeated cycles. In these tests, phosphogypsum was separated into recrystallized (purified) gypsum, insoluble residue and supernatant. Both raw phosphogypsum and recrystallized gypsum were examined using inductively coupled plasma optical emission spectrometry, X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry. The activity concentrations of (238)u, (235)u, Ra-226, Pb-210,Th- 232 and 40 K were investigated using gamma-ray spectrometry. Based on the activity concentration results, a number of radiometric parameters were calculated for the original and recrystallized phosphogypsum (i.e. radium equivalent activity, y indices for construction materials, a index and external and internal hazard indices). Raw phosphogypsum samples showed greater mean activity concentration levels of U-238 and Ra-226 than the international recommended limits, while the recrystallized gypsum demonstrated notably lower activity concentrations for these two isotopes. The activity concentration of Ra-226 in recrystallized gypsum is similar to 6 times lower than in raw phosphogypsum. Therefore, recrystallized gypsum does not present a radiation hazard when used as a building material, while raw phosphogypsum meets the requirements only for road construction materials

Reciklaža srebra i bakra iz istrošene posrebrene bakarne žice

Recycling of secondary raw materials recently become more interesting , mainly due to reduced quantities of waste and price of waste water treatment. Aim of this work was recycling and production of copper ana silver from rub out copper wire plated with silver. Silver and copper high purity (99,99%) from rub out copper wire realized by combining pyro-metallurgy, electro-metallurgy and chemical treatment in laboratory and pilot production plant in Institute of Mining and Metallurgy Bor.U novije vreme povećan je interes za recikliranjem metala čime se smanjuje količina otpada kao i troškovi tretiranja otpadnih voda. Cilj ovog rada bio je da se iz istrošene posrebrene bakarne žice valorizuju srebro i bakar, a da se nečistoće, kao što su olovo, kalaj, antimon i kadmijum uklone. Srebro i bakar visoke čistoće (99,99 %) iz istrošene žice dobijeni su kombinacijom pirometalurških, elektrometalurških i hemijskih postupaka u laboratorijama i poluindustrijskim postrojenjima Instituta za rudarstvo i metalurgiju u Boru

Supplementary data for the article: Stevanović, J. Z.; Rakitin, A. R.; Kojić, I. D.; Vuković, N. S.; Stojanović, K. Significance of Infrared Spectroscopic Branching Factor for Investigation of Structural Characteristics of Alkanes, Geochemical Properties and Viscosity of Oils: Scientific Paper. Journal of the Serbian Chemical Society 2022, 87 (1), 41–55. https://doi.org/10.2298/JSC210830091S.

Supplementary material for: [https://doi.org/10.2298/JSC210830091S]Related to published version: [https://cherry.chem.bg.ac.rs/handle/123456789/4854

Efikasnost sredstava respiratorne antimikrobne zaštite

Individual protection of the respiratory tract is a key factor in preventing/stopping a potential epidemic/pandemic caused naturally or during biological agents application in war or terrorist activities. Improving the existing or introducing new appropriate personal protective equipment to the military environment would be invaluable. In order to acquire a confirmation of reliability and physiological suitability for use in the protection of military personnel in case of a declared epidemic/pandemic, the protection effectiveness and physiological suitability of three models of epidemiological masks were tested in accordance with BS EN 149: 2007 under the conditions of simulated biological air contamination. The test results and their statistical processing have shown that an epidemiological mask possesses high efficiency and physiological suitability as a protective device in the case of air contamination with aerosols of biological agents. It is recommended for use in peacetime together with the existing standard military masks.Individualna zaštita respiratornog trakta predstavlja ključni faktor u sprečavanju/prekidanju potencijalne epidemije/pandemije nastale prirodnim putem ili upotrebom bioloških agenasa u ratnim ili terorističkim dejstvima. Poboljšanje postojećih ili uvođenje novih pogodnijih ličnih zaštitnih sredstava u vojnu sredinu bilo bi od neprocenjivog značaja. U cilju sticanja potvrde pouzdanosti i fiziološke pogodnosti za upotrebu u zaštiti vojnog personala u slučaju objavljene epidemije/pandemije, izvršeno je ispitivanje efikasnosti zaštite i fiziološke podobnosti tri modela epidemiološke maske u uslovima simulirane biološke kontaminacije vazduha, u skladu sa standardom SRPS EN 149:2007. Na osnovu rezultata ispitivanja i njihove statističke obrade utvrđeno je da epidemiološka maska kao zaštitno sredstvo poseduje visoku efikasnost i fiziološku podobnost u slučaju kontaminacije vazduha aerosolima bioloških agenasa. Predlaže se za upotrebu u mirnodopskim uslovima ujedno sa postojećim formacijskim maskama

Identification of a Novel Series of Benzohopanes and Their Geochemical Significance

series of novel C-33-C-35 hexacyclic benzohopanes (C(33)b-C(35)b) were identified in 39 samples of coal extracts and 39 crude oils of different ages from all over the world. C(33)b and C(34)b homologues were isolated, and their structures were determined by nuclear magnetic resonance. The structure of C(35)b benzohopane was proposed based on the mass spectrum and its similarity with the mass spectra of structurally defined C(33)b and C(34)b homologues. The structures of the C(33)b-C(35)b hexacyclic benzohopanes are closely related to isohopanes; both groups are typical for terrestrial organic matter and can be useful in the correlation analysis. A possible pathway of formation of these novel benzohopanes and their hopanoid precursors with an additional branch in the aliphatic side chain is proposed. C(33)b-C(35)b hexacyclic benzohopanes are stable up to the maturity level corresponding to random vitrinite reflectance (Rr) of similar to 0.80%, which was demonstrated by analyzing the samples of different maturity and by the maturation simulation experiments: hydrous pyrolysis of two bituminous coals (Rr = 0.55 and 0.59%) and pyrolysis of an extracted bituminous coal (Rr = 0.56%) and its asphaltenes. This represents a confirmation that the formation of these novel benzohopanes is related to specific depositional conditions and microbial activity during diagenesis. Mature samples (Rr = 0.8%) and hydrous pyrolysate of the bituminous coals (Rr lt 0.60%) obtained at 330 degrees C show a distinct distribution of benzohopanes in comparison to immature and moderately mature samples, which is characterized by a low abundance of the b series benzohopanes and the presence of regular and numerous other benzohopane isomers. The latter most likely represent isomers of regular and novel benzohopanes with different substitution patterns on the aromatic ring. This isomerization of alkyl groups attached to the aromatic ring, leading to the formation of thermodynamically more stable isomers, is a well-known maturation scenario so far reported in the series of alkylated naphthalenes, phenanthrenes, and dibenzothiophenes. Therefore, in the same way, a distribution of benzohopanes can indicate thermal maturity. In addition to the novel benzohopanes, three series (2 alpha, 2 beta, and 3 beta) of their methylated derivatives were identified in numerous samples. Finally, a novel C-35 heptacyclic benzohopane with an additional cyclopentane ring was also observed in the studied samples, and its structure was tentatively identified based on the mass spectrum. Opposite to the hexacyclic C(33)b-C(35)b benzohopanes, the formation of the C-35 heptacyclic benzohopane does not require a specific hopanoid precursor with two branches in the side chain. Therefore, this compound seems to have less geochemical significance than the new hexacyclic benzohopanes