Search

Hydrometallurgical processes for copper revalorization from overburden of abandoned mine Cerovo in Eastern Serbia were studied. Paper contain results of percolation leaching tests, performed with acidic mine waters accumulated in the bottom of the former open pit, followed by solvent extraction (SX) and electrowinning (EW) processes on achieved copper pregnant leach solutions. Usage of accumulated waste waters was objected to minimizing the environmental hazard due to uncontrolled leaking of these waters in nearby creeks and rivers. Chemical composition of acidic mine waters used for leaching tests was: (g/dm3): Cu - 0.201; Fe - 0.095; Mn - 0.041; Zn - 0.026; Ni - 0.0004; pH value - 3.3. Copper content in overburden sample used for leaching tests was 0.21% from which 64% were oxide copper minerals. In scope of leaching tests were examined influence of leaching solution pH values and iron (III) concentration on copper recovery. It was established that for 120 hours of leaching on pH=1.5 without oxidant agents, copper concentration in pregnant leach solutions enriched up to 1.08g/dm3 which was enough for copper extraction from solution with SX-EW treatment. As extraction reagent in SX circuit was used LIX-984N in a kerosene diluent. Cathode current density in electrowinning cell was 220Am-2 while electrolyte temperature was kept on 50±2oC. Produced cathode copper at the end of SX-EW process has purity of 99.95% Cu.

Whereas nonselective nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen and diclofenac, inhibit both cyclooxygenase-1 and cyclooxigenase-2 enzymes, selective inhibitors target cyclooxygenase-2, which is overexpressed in inflammation, but also in cancer, atherosclerosis, Alzheimer's disease, and Parkinson's disease. Potential cardiovascular and hepatic side effects of cyclooxygenase-2 inhibitors have limited their use. The development of selective and safe cyclooxygenase-2 inhibitors remains a high priority in drug discovery. Based on the structure of previously investigated newly synthesized b-hydroxy-b-arylpropanoic acids, two groups of compounds were designed: analogs in which one of the benzene rings was replaced by a pyrazole, while the carboxyl group was retained, and amides of b-hydroxy-b-arylpropanoic acids with pyrazole. The compounds were docked into the 3D structure of the catalytic site of the enzyme cyclooxygenase-2 using AutoDock Vina 1.2.0. and the obtained interactions were compared with the interactions of celecoxib, a selective inhibitor. The amides had lower binding energies than the designed acids, which makes them attractive target compounds for synthesis and further examination.

This study aimed to investigate the effect of 150 mg/L sodium fluoride (NaF) on redox status parameters and essential metals [copper (Cu), iron (Fe), and zinc (Zn)] in the blood, liver, kidney, brain, and spleen of Wistar rats and to determine the protective potential of selenium (Se) against fluoride (F-) toxicity. Male Wistar rats were randomly distributed in groups of five (n=5) receiving tap water (control) or water with NaF 150 mg/L, NaF 150 mg/L + Se 1.5 mg/L, and Se 1.5 mg/L solutions ad libitum for 28 days. Fluorides caused an imbalance in the redox and biometal (Cu, Fe, and Zn) status, leading to high superoxide anion (O2 .-) and malondialdehyde (MDA) levels in the blood and brain and a drop in superoxide dismutase (SOD1) activity in the liver and its increase in the brain and kidneys. Se given with NaF improved MDA, SOD1, and O2 .- in the blood, brain, and kidneys, while alone it decreased SH group levels in the liver and kidney. Biometals both reduced and increased F- toxicity. Further research is needed before Se should be considered as a promising strategy for mitigating F- toxicity.

The aim of this research was to investigate the effects of different exercises on the development of tennis players' agility. The electronic database PubMed was used to search and collect relevant studies in the field of agility in tennis. This study was conducted based on the PRISMA statement. A total of 361 participants were included in this study. Twelve studies met the criteria in order to be included in this study. The results showed that the effect was statistically significant after each exercise program (high-intensity interval training, court tennis training, neuromuscular warm-up, sport-specific training, plyometric training, neuromuscular and performance training). The exercise programs lasted from 5 - 12 weeks with a weekly frequency of three times for 45 to 90 minutes. The results, obtained in this way, indicate a sensitive period for the development of agility in this age group, i.e. junior tennis players. The analyzed areas of agility assessment, frontal and lateral agility observed on the basis of agility assessment tests, were singled out.

This paper aims to examine Serbian female entrepreneurs' performance related to digital competences based on real-life scenario questions. The research was conducted on a sample of 114 female entrepreneurs. The method used for collecting data was an online survey (Google form). The survey questions were based on Digital Competence Framework (DigComp) focusing on the first two areas, "Information and data literacy" and "Communication and collaboration". The results showed that the female entrepreneurs in Serbia achieved better performance (i.e., answered the questions correctly) in the area "Information and data literacy" especially in the segment "Browsing, searching, and filtering data, information and digital content". On the other side, lower performance of Serbian female entrepreneurs was achieved in the area "Communication and collaboration", where nine questions from thirteen were not answered correctly. Segments "Engaging in citizenship through digital technologies", "Collaborating through digital technologies" and "Netiquette" were identified as the most problematic because there was no correct answer. The authors can conclude that skills incorporated in the segments of the second area need to be improved and boosted to be in line with market demands.

The combined effect of ICT improvement, digitalization and change in clients' habits lead to changes in the financial sector worldwide. Increased use of digital financial services (DFS) is a change that might help to increase financial inclusion, which is particularly important for developing countries. As income is considered a critical driver of digital payments, this study aims to determine whether there is a linear relationship between a country's income measured by the level of Gross National Income per capita (GNI p.c.) and the use of digital payment services, i.e., making and receiving digital payments. We used data from the Global Findex and World Bank databases for 2017 to conduct the research, which covered 141 countries. The presence of a linear relationship between the level of GNI p.c. and the use of digital payments was tested using correlation analysis. The results of the correlation analysis show that there is a significant strong positive linear relationship between the level of GNI p.c. and the use of digital payment services in both segments, i.e., making and receiving payments. Findings are consistent with previous research and confirmed the important role of income as a driver of the use of DFS.

The aim of this paper is to present the changes that have occurred in the banking sector of Serbia after the beginning of its transformation, with special emphasis to the last decade of development. Twenty years after the beginning of the transformation, the fundamental features of the system are consolidation, foreign ownership, increases of all banking aggregates measured by absolute values, primarily assets, capital, deposits and loans. Also, a trend of growth in profitability, liquidity and capital adequacy of the sector was recorded. Along with the decrease in the number of banks, the ownership structure changed to predominantly foreign capital, but the degree of concentration did not change drastically. However, the share of the first 5 banks in total assets was constantly above 50%, which indicates the fact that the banking sector of Serbia is extremely fragmented, because there is a significant number of banks with a market share below 2%.

The environmental pollution is a major problem over the world. The large amount of pollutants formed during various industrial processes reaches the ecosystem. Thus, heavy metals, oils and other organic compounds are responsible for water contamination. It is known that heavy metals have toxic effect on the environment. Additionally, they are non-degradable and have ability to reach the living organisms through the food chain. Among different methods, the adsorption is widely used in wastewater treatment due to simplicity of the process and efficiency in the removal of pollutants. Natural zeolites from different deposits have shown good selectivity for heavy metal ions. Additionally, they are environmentally friendly, low-cost and have high ion exchange capacity.

Milan D Antonijević,1 Ovidiu Novac,1 Barry MG O’Hagan2 1Faculty of Engineering and Science, University of Greenwich at Medway, Chatham Maritime, ME4 4TB, UK; 2Faculty of Life and Health Sciences, School of Biomedical Sciences, Ulster University, Coleraine, BT52 1SA, UK Introduction: Emollient therapy is the mainstay for treating skin conditions such as atopic dermatitis and psoriasis. New emollients have been introduced recently and are assumed to be therapeutically interchangeable with the innovator products because, superficially, they appear to have similar compositions. This study compares a) the ex vivo human skin occlusion performance and b) the visual and microscopic properties of Isomol gel (IMG) and Doublebase gel (DBG).Materials and Methods: Occlusion was measured gravimetrically by reduction in cumulative 48-hour evaporative weight loss from ex vivo human skin samples following single applications of the two test emollients and Vaseline®. Skin samples from a single donor were mounted in Franz diffusion cells and then the emollients were spread over the skin surface with an applied dose of approximately 2 mg/cm2. The assemblies (four replicates per treatment) were then accurately weighed at baseline (T0) and again after 5-, 24-, and 48-hour postapplication. The quality of the two emollient gel formulations was compared by visual examination of their film-forming characteristics and by microstructural examination using environmental scanning electron microscopy (ESEM). Results: Occlusivity of the DBG emollient gel formulation was comparable with Vaseline and substantially better than IMG, with the DBG-treated skin samples losing less than half as much weight as the IMG-treated skin samples over 48 hours and at a much slower rate during the first 5 hours. The film-forming characteristics and microstructure of the gels were also very different. Whereas DBG maintained a smooth, uniform film over 24 hours, the IMG formulation phase-separated. ESEM results showed that the DBG emulsion has a stable structural matrix with uniform oil droplets, whereas for IMG the emulsion system is inhomogeneous with the oil phase coalescing into larger irregular shaped rafts. Conclusions: We have demonstrated substantial performance differences between two prescribed emollient gels. Keywords: gel, emollient, occlusion, microscopy, comparison, performance

One of the most important goals of electronic assessments is to achieve the smallest measurement error with tests that are as simple and short as possible. The psychological state of an examinee is typically ignored, both in the process of designing the tests and during the exam itself. Using the developed framework, we tested 35 participants in an experiment to obtain as much data as possible about the emotional states of the students depending on the different types of question posed. In this paper, we present our current results from an examination of the potential of using EEG data towards applying artificial intelligence for improvement of electronic assessments, as well as a technical platform for this purpose.

This work presents an investigation of column leaching of a chalcopyrite ore using sulphuric acid where dissolved oxygen and iron(III) ions play the role of oxidants. The investigations were carried out in PVC columns, diameter 110 mm and height 1000 mm, by percolation of the leaching solution through the ore layer. The influence of ore grain size on the degree of leaching and acid consumption was examined. The formation of gypsum on limestone results in the comminution of the initial raw material during leaching. The grain size of chalcopyrite was found to have no important influence on the leaching rate of copper. A higher consumption of sulphuric acid was found for the fractions (-3+1) mm, (-5+0) mm and (-5+3) mm than for the fractions (-10+5) mm, (-20+10) mm and (-10+0) mm. [ABSTRACT FROM AUTHOR]

Creation of a statistically reliable 3D-QSAR (Quantitative Structure Activity Relationships) model enables definition of the structure of the pharmacophore for antagonists of serotonin 5-HT2A receptors and selection of the key molecular determinants for the design of new antagonists. A 3D-QSAR study was applied on a series of 50 antagonists of 5-HT2A receptors. The data set is divided into the training set, composed of 33 compounds, and test set containing 14 molecules. The training set was used to build the 3D-QSAR model, while test set was used for model validation. This 3D-QSAR study was performed by use of the Pentacle 1.07 programs. Obtained statistical and validation parameters for training set (R²= 0.96; Q²=0.75, RMSEE= 0.211); and for test set (R²pred=0.51; RMSEP= 0.558); indicate on reliability and good predictive potential of the 3D-QSAR model. Based on the most influential variables of the selected 3D-QSAR model, the molecular determinants for the antagonistic effect on the 5-HT2A receptors were selected: hydrogen bond acceptor and hydrogen bond donor at a distance of 10.4A-10.8A (v495: O-N1); carbonyl oxygen and a steric hot spot at a distance of 14.8A-15.2A (v640: N1-TIP); hydrophobic domain and hydrogen bond acceptor at a distance of 3.2A-3.6A (v276: DRY-O); two steric hot spots at a distance of 18.8A-19.2A (v248: TIP-TIP) .

The influence of pyrolysis type on the shale oil generation and its composition was studied. Different methods such as Rock-Eval pyrolysis, thermogravimetric analysis (TGA) and pyrolysis in the open and closed systems were applied. Samples from the Upper layer of Aleksinac oil shale (Serbia) were used as a substrate and first time characterized in detail. The impact of kerogen content and type on the shale oil generation in different pyrolysis systems was also estimated. Majority of the analysed samples have total organic carbon content > 5 wt. % and contain oil prone kerogen types I and/or II. Therefore, they can be of particular interest for the pyrolytic processing. The thermal behaviour of analysed samples obtained by TGA is in agreement with Rock-Eval parameters. The pyrolysis of oil shale in the open system gives higher yield of shale oil than the pyrolysis in the closed system. The yield of hydrocarbons (HCs) in shale oil produced by the open pyrolysis system corresponds to an excellent source rock potential, while HCs yield from the closed system indicates a very good source rock potential. The kerogen content has a greater impact on the shale oil generation than kerogen type in the open pyrolysis system, while kerogen type plays a more important role on the generation of shale oil than the kerogen content in the closed system. The composition of the obtained shale oil showed certain undesirable features, due to the relatively high contents of olefinic HCs (open system) and polar compounds (closed system), which may require further treatment to be used. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 176006]

Corrosion presents the destruction of materials through chemical or electrochemical interactions with their environment. Interactions between the metal surface and bacterial cells or products of their metabolic activities can lead to microbially-influenced corrosion. Also, it is known that certain microorganisms can contribute to corrosion inhibition. In accordance to that, the literature dealing with the application of different microorganisms as a potentialy corrosion inhibitors of metals is investigated. Different bacterial strains as a corrosion inhibitor of a metalic materials are examined. Further, the role of extracellular polymeric substances in corrosion behavior of metals is emphasized. Based on the data presented in this work, it can be said that inhibition efficiency depends on microorganism as well as type of metal. Also, it is presented that some bacterial species can be used as a good corrosion inhibitor instead of toxic organic compounds.

This paper describes the waste paper recycling process. Special emphasis is placed on the description of technological phase (disintegration or grinding, screening, cleaning, washing and/or flotation, water treatment and disposal of sludge), which are generally required in the processing of waste paper, and which also represent the main phases in the mineral processing. The waste paper is a potential secondary raw materials but due to degradation of cellulose physical properties which occur during the recycling, the cellulose fibers can be recycled a limited number of times. Because of this, the impact analysis of mechanical and chemical treatment on the secondary fiber quality is also given in the paper.

This study is focussed on a comprehensive investigation on the state of pollution of Danube and Sava rivers in Belgrade region. Different complementary analytical approaches have been used covering both (i) organic ccontaminants in river water by target analyses of hormones and neonicotinoids as well as non-target screening analyses and (ii) heavy metals in sediments. Finally, some common water quality parameters have been analysed. The overall state of pollution is on a moderate level. Bulk parameters did not reveal any unusual observation. Also quantification of preselected organic contaminants did not point to elevated pollution. A more significant contamination was measured for chromium, nickel, zinc and partially copper in sediments with values above target values according to Serbian regulations. Lastly, non-target screening analysis revealed a wider spectrum of organic contaminants comprising pharmaceuticals, technical additives, personal care products and pesticides. The study presented a comprehensive view on the state of pollution of Sava and Danube rivers and is the base for setting up further monitoring programs. As a superior outcome it has been illustrated how different chemical analyses can point to different assessments of the river quality. The comparison of target and non-target analyses pointed to potential misinterpretation of the real state of pollution.

Three new cationic mixed-ligand Cu(II) complexes with N,N’,N’’,N’’’-tetrakis(2-pyridylmethyl)- 1,4,8,11-tetraazacyclotetradecane (tpmc) and bridging aromatic mono- or dicarboxylate ligands were prepared. Elemental analysis, conductometric and magnetic measurements, as well as electronic and IR spectroscopy were employed for their characteriization. It is proposed that the complexes [Cu2(C6H5COO)tpmc](CIO4)3MeOH and [Cu2(Hpht)tpmc](CIO4). 3H2O(H2pht=phthalic acid) are binuclear with µ-coordination of the carboxylate monoanions. The third complex [Cu4ipht(tpmc)2](CIO4)6NaClO42MeCN (H2ipht=isophthalic acid) is one of the rare tetranuclear Cu(II)-tpmc complexes with an aromatic dicarboxylate ion bridging two Cu2tpmc units. This was also confirmed by preliminary results of the determination of the crystal structure.

This paper presents the most important studies on the oxidation of pyrite particularly in aqueous solutions. The consequences of pyrite oxidation was examined, as well as its importance, from both the technical-technological and environmental points of view. The oxidation of pyrite was considered in two parts. The spontaneous oxidation of pyrite in nature was described in the first part, with this part comprising pyrite oxidation in deposits depots and mines. It is explained how way natural electrochemical processes lead to the decomposition of pyrite and other minerals associated with pyrite. The oxidation of pyrite occurring during technological processes such as grinding, flotation and leaching, was shown in the second part. Particular emphasis was placed on the oxidation of pyrite during leaching. This part includes the leaching of sulphide and oxide ores, the leaching of pyrite coal and the leaching of refractory gold-bearing ores (pressure oxidation, bacterial oxidation, oxidation by means of strong oxidants and the electrolysis of pyrite suspensions). Various mechanisms of pyrite oxidation and of the galvanic interaction of pyrite with other sulphide minerals are shown.

The kinetics of pyrite oxidation by hydrogen peroxide in phosphoric acid solutions were investigated. The effects of stirring, temperature, and particle size, as well as of the hydrogen peroxide and phosphoric acid concentrations were studied. The effect of phosphate ion addition was also examined. The oxidation kinetics was found to follow a shrinking core model, with the surface chemical reaciton as the rate-controlling step. This is in accord with an activation energy of 57 kJ/mol and a linear relationship between the rate constant and the reciprocal of the particle radius. The reaction order with respect to the hydrogen peroxide concentration was found to be equal to unity. Variation of the phosphoric acid concentration had practically no effect on the rate of pyrite oxidation. Addition of the phosphate ion in the relatively low concentration range (0.005.0.1 mol/dm 3) had a highly negative influence on the rate of pyrite oxidation, indicating that this ion has an inhibiting effect on the oxidation of pyrite by hydrogen peroxide.

In this study, pharmacological profiling and investigation of the anticoagulant activity of the newly synthesized coumarin derivative: ( E )-3-(1-((4-hydroxy-3-methoxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate ( L ) were performed. The obtained results were compared with the parameters obtained for Warfarin ( WF ), which is a standard good oral anticoagulant. The estimated high binding affinity of L toward plasma proteins (PPS% value is > 90%) justifies the investigation of binding affinity and comparative analysis of L and WF to Human Serum Albumin ( HSA ) using the spectrofluorimetric method (296, 303 and 310 K) as well as molecular docking and molecular dynamics simulations. Compound L shows a very good binding affinity especially to the active site of WF (the active site I -subdomain IIA), quenching HSA fluorescence by a static process. Also, the finite element smeared model (Kojic Transport Model, KTM), which includes blood vessels and tissue, was implemented to compute the convective-diffusion transport of L and WF within the liver. Finally, compound L shows a high degree of inhibitory activity toward the VKOR receptor comparable to the inhibitory activity of WF . Stabilization and limited flexibility of amino acid residues in the active site of the VKOR after binding of L and WF indicates a very good inhibitory potential of compound L . The high affinity of the L for the VKOR enzyme (Vitamin K antagonist), as well as the structural similarity to commercial anticoagulants ( WF ), provide a basis for further studies and potential application in the treatment of venous thrombosis, pulmonary embolism and ischemic heart disease.Communicated by Ramaswamy H. Sarma.

This study examined the antiradical activity of three synthesized coumarin derivatives: ( E )-3-(1-((2-hydroxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate ( A 1 -OH ), ( E )-3-(1-((3-hydroxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate ( A 2 -OH ), and ( E )-3-(1-((4-hydroxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate ( A 3 -OH ) against HOO•/O2•- radical species. The investigation included electron spin resonance (ESR) measurements and a DFT kinetic study. Thermodynamic and kinetic parameters of antiradical mechanisms-Formal Hydrogen Atom Transfer ( f -HAT), Radical Adduct Formation (RAF), Sequential Proton Loss followed by Electron Transfer (SPLET), and Single-Electron Transfer followed by Proton Transfer (SET-PT)-were evaluated using the Quantum Mechanics-based test for Overall Free Radical Scavenging Activity (QM-ORSA) under physiological conditions. ESR results indicated antiradical activity decreased in the sequence A 1 -OH (58.7%) > A 2 -OH (57.5%) > A 3 -OH (53.1%). Kinetic analysis revealed the f -HAT mechanism dominated HOO • inactivation. A newly formulated Sequential Proton Loss followed by Radical Adduct Formation (SPL-RAF) mechanism described interactions with O 2 •- . The activity toward O 2 •- M A 2 -OH (1.26 × 10 6 M -1 s -1 M A 3 -OH (7.71 × 10 5 M -1 s -1 M A 1 -OH (4.22 × 10 5 M -1 s -1 ). Molecular docking and dynamics studies tested inhibitory capability against enzymes producing reactive species: Lipoxygenase (LOX), Myeloperoxidase (MPO), NAD(P)H oxidase (NOX), and Xanthine Oxidase (XOD). Affinity to enzymes decreased in the order: XOD > LOX > NOX > MPO.

Background: The growing disparity between the rising demand for liver transplantation (LT) and the limited availability of donor organs has prompted a greater reliance on older liver grafts. Traditionally, utilizing livers from elderly donors has been associated with outcomes inferior to those achieved with grafts from younger donors. By accounting for additional risk factors, we hypothesize that the utilization of older liver grafts has a relatively minor impact on both patient survival and graft viability., Aim: To evaluate the impact of donor age on LT outcomes using multivariate analysis and comparing young and elderly donor groups., Methods: In the period from April 2013 to December 2018, 656 adult liver transplants were performed at the University Hospital Merkur. Several multivariate Cox proportional hazards models were developed to independently assess the significance of donor age. Donor age was treated as a continuous variable. The approach involved univariate and multivariate analysis, including variable selection and assessment of interactions and transformations. Additionally, to exemplify the similarity of using young and old donor liver grafts, the group of 87 recipients of elderly donor liver grafts (≥ 75 years) was compared to a group of 124 recipients of young liver grafts (≤ 45 years) from the dataset. Survival rates of the two groups were estimated using the Kaplan-Meier method and the log-rank test was used to test the differences between groups., Results: Using multivariate Cox analysis, we found no statistical significance in the role of donor age within the constructed models. Even when retained during the entire model development, the donor age's impact on survival remained insignificant and transformations and interactions yielded no substantial effects on survival. Consistent insignificance and low coefficient values suggest that donor age does not impact patient survival in our dataset. Notably, there was no statistical evidence that the five developed models did not adhere to the proportional hazards assumption. When comparing donor age groups, transplantation using elderly grafts showed similar early graft function, similar graft ( P = 0.92), and patient survival rates ( P = 0.86), and no significant difference in the incidence of postoperative complications., Conclusion: Our center's experience indicates that donor age does not play a significant role in patient survival, with elderly livers performing comparably to younger grafts when accounting for other risk factors., Competing Interests: Conflict-of-interest statement: All authors have nothing to disclose., (©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.)

Pharmaceutical and industrial utilization of synthetic chemicals has an immerse impact on the environment. In that sense, novel chemicals with potential for industrial application should be investigated for their behaviour in reactions with hydroxyl radical, simulating AOPs (Advanced Oxidation Processes). AOPs are known for being highly effective in wastewater management and natural water remediation. In this paper, exhaustive research on the radical scavenging activity of a newly synthesized coumarin derivative (4HCBH), as a representative of the series of coumarin-benzohydrazides with high antioxidative potential was conducted. This study took into consideration the pH value range significant for practically all living organisms (pH = 7.0-8.5). According to the experimentally obtained results, the 4HCBH showed an increase in radical scavenging activity, following the slight increase in pH values, which suggested that the formation of anionic form of 4HCBH is responsible for its antiradical activity. Further investigations led to the postulation of a novel mechanistic approach called Sequential Proton Loss Electron Transfer - Radical-Radical Coupling (SPLET-RRC), in which, by a series of steps, a new, stable compound was formed. Furthermore, it was demonstrated that the product generated through SPLET-RRC showed lower toxicity than the parent molecule., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In this study, green synthesis of two derivatives of coumarin-hydroxybenzohydrazide, ( E )-2,4-dioxo-3-(1-(2-(2,3,4-trihydroxybenzoyl)hydrazyl)ethylidene)-chroman-7-yl acetate ( C-HB 1 ), and ( E )-2,4-dioxo-3-(1-(2-(3,4,5-trihydroxybenzoyl)hydrazyl)ethylidene)chroman-7-yl acetate ( C-HB 2 ) is reported. Using vinegar and ethanol as a catalyst and solvent, the reactions were carried out between 3-acetyl-4-hydroxy-coumarin acetate and corresponding trihydroxybenzoyl hydrazide. The antioxidant potential of these compounds was investigated using the DPPH and ABTS assays, as well as the FRAP test. The obtained results reveal that even at very low concentrations, these compounds show excellent radical scavenging potential. The IC 50 values for C-HB 1 and C-HB 2 in relation to the DPPH radical are 6.4 and 2.5 μM, respectively, while they are 4.5 and 2.0 μM in relation to the ABTS radical. These compounds have antioxidant activity that is comparable to well-known antioxidants such as gallic acid, NDGA, and trolox. These results are in good correlation with theoretical parameters describing these reactions. Moreover, it was found that inhibition of DPPH ● follows HAT, while inactivation of ABTS +● follows SET-PT and HAT mechanisms. Additionally, coumarin-hydroxybenzohydrazide derivatives induced moderate cytotoxic activity and show significant potential to modulate redox status in HCT-116 colorectal cancer cells. The cytotoxicity was achieved via their prooxidative activity and ability to induce oxidative stress in cancer cells by increasing O 2 ˙ - concentrations, indicated by increased MDA and GSH levels. Thus, ROS manipulation can be a potential target for cancer therapies by coumarins, as cancer cells possess an altered redox balance in comparison to normal cells. According to the ADMET analysis, the compounds investigated show good pharmacokinetic and toxicological profiles similar to vitamin C and gallic acid, which makes them good candidates for application in various fields of industry and medicine.

Background: Hepatocellular carcinoma (HCC) is one of the leading indications for liver transplantation (LT) however, selection criteria remain controversial. We aimed to identify survival factors and predictors for tumour recurrence using machine learning (ML) methods. We also compared ML models to the Cox regression model., Methods: Thirty pretransplant donor and recipient general and tumour specific parameters were analysed from 170 patients who underwent orthotopic liver transplantation for HCC between March 2013 and December 2019 at the University Hospital Merkur, Zagreb. Survival rates were calculated using the Kaplan-Meier method and multivariate analysis was performed using the Cox proportional hazards regression model. Data was also processed through Coxnet (a regularized Cox regression model), Random Survival Forest (RSF), Survival Support Vector Machine (SVM) and Survival Gradient Boosting models, which included pre-processing, variable selection, imputation of missing data, training and cross-validation of the models. The cross-validated concordance index (CI) was used as an evaluation metric and to determine the best performing model., Results: Kaplan-Meier curves for 5-year survival time showed survival probability of 80% for recipient survival and 82% for graft survival. The 5-year HCC recurrence was observed in 19% of patients. The best predictive accuracy was observed in the RSF model with CI of 0.72, followed by the Survival SVM model (CI 0.70). Overall ML models outperform the Cox regression model with respect to their limitations. Random Forest analysis provided several relevant outcome predictors: alpha fetoprotein (AFP), donor C-reactive protein (CRP), recipient age and neutrophil to lymphocyte ratio (NLR). Cox multivariate analysis showed similarities with RSF models in identifying detrimental variables. Some variables such as donor age and number of transarterial chemoembolization treatments (TACE) were pointed out, but these were not influential in our RSF model., Conclusions: Using ML methods in addition to classical statistical analysis, it is possible to develop sufficient prognostic models, which, compared to established risk scores, could help us quantify survival probability and make changes in organ utilization., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://atm.amegroups.com/article/view/10.21037/atm-22-6469/coif). All authors report that the article processing charge has been supported by the European Regional Development Fund under the grant KK.01.1.1.01.0009 (DATACROSS). The authors have no other conflicts of interest to declare., (2023 Annals of Translational Medicine. All rights reserved.)

Coumarin derivatives are a class of compounds with pronounced biological activities that depend primarily on the present substituents. Four 3-methoxycarbonylcoumarin derivatives with substituents of different electron-donating/electron-withdrawing abilities (Br, NO 2 , OH, and OMe) were investigated structurally by NMR, IR, and UV-VIS spectroscopies and density functional theory methods. The appropriate level of theory (B3LYP-D3BJ/6-311++G(d,p) was selected after comparing similar compounds' experimental and theoretical structural parameters. The natural bond orbital and quantum theory of atoms in molecules were employed to investigate the intramolecular interactions governing stability. The electronic effects of substituents mostly affected the aromatic ring that the substituents are directly attached to. The antioxidant properties were investigated by electron paramagnetic resonance spectroscopy towards HO • , and the percentages of reduction were between 13% ( 6-Br ) and 23% ( 6-OMe ). The protein binding properties towards transport proteins were assessed by spectrofluorimetry, molecular docking, and molecular dynamics (MD). The experimentally determined binding energies were well reproduced by molecular docking, showing that the spontaneity of ibuprofen binding was comparable to the investigated compounds. The flexibility of HSA in MD simulations depended on the substituents. These results proved the importance of electronic effects for the protein binding affinities and antioxidant properties of coumarin derivatives.

Two newly synthesized coumarin-palladium(II) complexes (C1 and C2) were characterized using elemental analysis, spectroscopy (IR and 1 H- 13 C NMR), and DFT methods at the B3LYP-D3BJ/6-311+G(d,p) level of theory. The in vitro and in silico cytotoxicity of coumarin ligands and their corresponding Pd(II) complexes was examined. For in vitro testing, five cell lines were selected, namely human cervical adenocarcinoma (HeLa), the melanoma cell line (FemX), epithelial lung carcinoma (A549), the somatic umbilical vein endothelial cell line (EA.hi926), and pancreatic ductal adenocarcinoma (Panc-1). In order to examine the in silico inhibitory potential and estimate inhibitory constants and binding energies, molecular docking studies were performed. The inhibitory activity of C1 and C2 was investigated towards epidermal growth factor receptor (EGFR), receptor tyrosine kinase (RTK), and B-cell lymphoma 2 (BCL-2). According to the results obtained from the molecular docking simulations, the inhibitory activity of the investigated complexes towards all the investigated proteins is equivalent or superior in comparison with current therapeutical options. Moreover, because of the low binding energies and the high correlation rate with experimentally obtained results, it was shown that, out of the three, the inhibition of RTK is the most probable mechanism of the cytotoxic activity of the investigated compounds.

Heart failure (HF) is a life-threatening condition that occurs when the heart cannot pump enough blood and oxygen to meet the body's needs. It affects mostly the elderly, commonly from the male population, especially those with obesity, diabetes, or some other chronic condition. It can be treated with different medications, and promising results were shown by a relatively new medicament called Entresto. Results obtained from molecular docking and molecular dynamics simulations to examine the inhibitory capacity of Entresto are presented in this study. Parameters obtained by the molecular docking simulations show that both parts of Entresto (sacubitril (SAC) and valsartan (VAL)) interact with targeted proteins, and inhibit their physiological function. Simulations of molecular dynamics revealed some interesting inhibitory patterns. SAC was discovered to produce structural alterations in neprilysin by binding to it, reducing neprilysin's physiological activity. In addition to blocking the active site, SAC binding causes the enzyme's structure to become less compact over time, causing changes in its biochemical characteristics and preventing the enzyme from performing its biological function. Similar to SAC, VAL also causes deviations in the structure of angiotensin receptors. The angiotensin receptor GPCR (G-protein-coupled receptors) is immersed in the lipid bilayer, and changes in the tertiary structure are only visible through RMSD and RMSF, not by examining R g . In this regard, MD simulations validated the results of molecular docking simulations, demonstrating that both SAC and VAL had inhibitory potential towards the neprilysin and angiotensin receptors, respectively., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Background: Clinopodium thymifolium is an aromatic plant species that is widespread in the Mediterranean region. It has been considered as a condiment and is used in cooking. As a promising spice plant, some efforts are being made to introduce this plant as a new crop species and it has been successfully cultivated in northern Italy., Results: Essential oils isolated from the aerial parts of a flavoring species C. thymifolium were analyzed by gas chromatography and gas chromatography/mass spectrometry. The results of a detailed analysis of the chemical composition of the oils showed the domination of pulegone, piperitone, piperitenone and isomenthone, as well as a significant alteration of the pulegone/isomenthone ratio with the developmental stage of the plant. Additionally, a comprehensive chemical analysis of the oils in combination with detailed spectral analyses and chemical synthesis of selected compounds has led to the identification of two new natural products: isomenthyl formate and neomenthyl 2-methylbutanoate., Conclusion: The observed chemical variability at the intrapopulation level appeared to be a phenological variation. In an evolutionary sense, the alteration of the pulegone/isomenthone ratio suggests their possible role in the ecological adaptation of the species to pollinators. Significant quantitative changes in the chemical composition of the oil at different phenological stages may be relevant in the case of plant material intended for edible purposes. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

In this study, the inhibitory potency of four adamantly- isothiourea derivatives (compounds 1 [4-bromobenzyl (Z)-N'-(adamantan-1-yl)-4-phenylpiperazine-1-carbothioimidate], 2 [3,5-bis(trifluoromethyl)benzyl (Z)-N'-(adamantan-1-yl)-4-phenylpiperazine-1-carbothioimidate], 3 [4-bromobenzyl (Z)-N-(adamantan-1-yl)morpholine-4-carbothioimidate] and 4 [3,5-bis(trifluoromethyl)benzyl (Z)-N-(adamantan-1-yl)morpholine-4-carbothioimidate]) was evaluated against SARS-CoV-2 targeted proteins. The investigated compounds 1 - 4 possess a similar structure to opaganib, which is used in studies like a potential drug for COVID-19 treatment. Since examined adamantly-isothiourea derivatives ( 1 - 4 ) shown broad-spectrum of antibacterial activity and significant in vitro cytotoxic effects against five human tumor cell lines and shown similarity in structure with opaganib, it was of interest to study their inhibitory potency toward some SARS-CoV-2 proteins such as SARS-CoV-2 main protease M pro and mutation of SARS-CoV-2 Spike (S) Protein D614G. The inhibitory potency of studied compounds is examined using molecular docking and molecular dynamic simulations. The results of molecular docking simulations indicate compound 1 as the most prominent candidate of inhibition of SARS-CoV-2 main protease M pro (▵G bind =11.24 kcal/mol), while almost the same inhibition potency of all studied compounds is exhibited toward D614G. Regarding the results obtained by molecular dynamic simulations, compounds 1 and 4 possess similar inhibitory potency toward SARS-CoV-2 main protease M pro as opaganib (▵G bind ≈ 40 kcal/mol)., Competing Interests: The authors declare no conflict of interest., (© 2021 Wiley‐VCH GmbH.)

Ferulic acid (FA) is used in skin formulations for protection against the damaging actions of the reactive oxygen species (ROS) produced by UVA radiation. Possible underlying protective mechanisms are not fully elucidated. By considering the kinetics of proton-coupled electron transfer (PCET) and radical-radical coupling (RRC) mechanisms, it appears that direct scavenging could be operative, providing that a high local concentration of FA is present at the place of • OH generation. The resulting FA phenoxyl radical, after the scavenging of a second • OH and keto-enol tautomerization of the intermediate, produces 5-hydroxyferulic acid (5OHFA). Inhibition of the lipoxygenase (LOX) enzyme, one of the enzymes that catalyse free radical production, by FA and 5OHFA were analysed. Results of molecular docking calculations indicate favourable binding interactions of FA and 5OHFA with the LOX active site. The exergonicity of chelation reactions of the catalytic Fe 2+ ion with FA and 5OHFA indicate the potency of these chelators to prevent the formation of • OH radicals via Fenton-like reactions. The inhibition of the prooxidant LOX enzyme could be more relevant mechanism of skin protection against UVA induced oxidative stress than iron chelation and assumed direct scavenging of ROS.

The paper briefly presents goals, activities, challenges, and outcomes of the NETCHEM project ( http://www.netchem.ac.rs/ ) that was co-funded by the Erasmus+ Program of European Union (573885-EPP-1-2016-1-RS-EPPKA2- CBHE-JP). The project has been started in October 2016 and with extension lasted until April 2020. Western Balkan region has been targeted by upgrading capacities for education and research in environmental and food analysis in cooperation with partners from France, the UK, and Czech Republic. NETCHEM platform providing Web Accessed Remote Instrumental Analytical Laboratories (WARIAL) network, Database service and Open education system was created in order to improve the cooperation, educational, and research capacities of Higher Education Institutions involved, but also targeting whether audience not only from academic domain but from industry as well. The NETCHEM platform is free for access to public; thus, the external users to NETCHEM consortium can not only see its content but also actively participate, enter Database and WARIAL network, and upload their own educational/research material.

The removal of Cr(III) ions and methylene blue (MB) from aqueous solutions by xanthated corn cob (xCC) in batch conditions was investigated. The sorption capacity of xCC strongly depended of the pH, and increase when the pH rises. The kinetics was well fitted by pseudo-second-order and Chrastil's model. Sorption of Cr(III) ions and MB on xCC was rapid during the first 20 min of contact time and, thereafter, the biosorption rate decrease gradually until reaching equilibrium. The maximum sorption capacity of 17.13 and 83.89 mg g -1 for Cr(III) ions and MB, respectively, was obtained at 40 °C, pH 5, and sorbent dose 4 g dm -3 for removal of Cr(III) ions and 1 g dm -3 for removal of MB. The prediction of purification process was successfully carried out, and the verification of theoretically calculated amounts of sorbent was confirmed by using packed-bed column laboratory system with recirculation of the aqueous phase. The wastewater from chrome plating industry was successfully purified, i.e., after 40 min concentration of Cr(III) ions was decreased lower than 0.1 mg dm -3 . Also, removal of MB from the river water was successfully carried out and after 40 min, removal efficiency was about 94%.

Measurements of air quality in the territory of Bor (Serbia) were performed at the sampling sites in the urban-industrial, suburban and rural area during the 2003-2008 period. A high level of arsenic (As) concentration in suspended particulate matter (PM) is of a predominantly industrial origin. The major source of pollution is the copper smelter which is situated in the close vicinity of the urban area of Bor. The ambient level of PM and As is influenced by meteorological parameters as well as the remoteness from the copper smelter. Continual exceedances of the annual limit value (LV) for As (6 ng m(-3)) were recorded at the sampling sites in the urban-industrial and suburban area. Maximum annual As concentrations were recorded at Town Park (46.5 ng m(-3)) in 2004, Institute (95.4 ng m(-3)) in 2004 and Jugopetrol (74.5 ng m(-3)) in 2003. In the past 15 years not a single mean annual As concentration recorded at the sampling sites Town Park, Institute and Jugopetrol has been within the LV. When the average annual and maximum monthly As concentrations are compared, it can be concluded that the level of pollution is higher in the urban-industrial and suburban areas than in the rural area., (Copyright 2010 Elsevier B.V. All rights reserved.)

The flotation tailings pond of the Bor Copper Mine poses a great ecological problem not only for the town of Bor but also for the surrounding soils and watercourses. Since the old flotation tailings contain about 0.2% of copper on the average, we investigated their leaching with sulphuric acid in the absence and presence of an oxidant. The aim was to determine the leaching kinetics of copper and iron as affected by various factors such as: the pH value of the leach solution, stirring speed, pulp density, particle size, concentration of ferric ions, temperature and time for leaching. The average copper and iron recovery obtained was from 60% to 70% and from 2% to 3%, respectively. These results indicate that the old flotation tailings pond represents an important source of secondary raw material for the extraction of copper and that it should be valorized rather than land reclamation. At the end of the paper, a mechanism of dissolution of copper and iron minerals from the tailings was described.

The possibility of applying natural monocrystaline pyrite as a sensor for the potentiometric titration of weak acids in N,N-dimethylformamide, methylpyrrolidone and pyridine was investigated. The potential of this electrode in N,N-dimethylformamide, methylpyrrolidone and pyridine exhibits a sub-Nernst dependence. In N,N-dimethylformamide the slope (mV/pH) is 39.0 and in methylpyrrolidone it is 45.0. The potential jumps at the titration end-point obtained in the titration of weak acids are higher than those obtained by the application of a glass electrode as the indicator electrode The potential in the course of the titration and at the titration end-point (TEP) are rapidly established. Sodium methylate, potassium hydroxide and tetrabutylammonium hydroxide (TBAH) proved to be very suitable titrating agents for these titrations. The results obtained in the determination of the investigated weak acids deviate by 0.1-0.35% with respect to those obtained by using a glass electrode as the indicator electrode.