CONTEMPORARY MATERIALS

KINETICS OF SOLID STATE REACTIONS: SOFTWARE APPROACH AND APPLICATION

Dijana Jelić — 2025-06-23

Countless inorganic, organic and polymeric materials are in the form of solids. Understanding and controlling the mechanism of the solid-state degradation or solid/gas reactions is crucial for designing reactions for new contemporary materials. For such systems kinetics of solid state reactions is very applicable since it explains the mechanism of the thermally stimulated processes and gives information on thermal decomposition, phase transformations, crystallization etc., important for the optimization of the chemical processes. Using useful tool called kinetic triplet (KT): activation energy (Ea), pre-exponential factor (A) and reaction model (f (α)), obtained by Kinetics2015 software package, we get valuable insight into physico- chemical significance of results. The Kinetics2015 software program supports thermal analysis methods (TGA, DTA and DSC) and works in non-isothermal conditions. The presentation will cover wide range of different materials starting from metallic nanocomposites, through polymers and pharmaceuticals for which by using software approach we get information regarding thermal stability and their decomposition. A special case study of thermal degradation of catalyst copper oxide yielding to copper will be discussed in paper in details.

OVERVIEW OF THE ELECTROPHYSIOLOGICAL MODELS FOR THE LEFT VENTRICLE SIMULATIONS

Bogdan Milićević — 2025-06-23

Electrophysiological models play a crucial role in understanding the complex dynamics of the heart, particularly the left ventricle. These models provide insights into the mechanisms underlying cardiac function and are essential for developing treatments for cardiac diseases. This paper presents an overview of various electrophysiological models used for simulating the left ventricle, including the van der Pol oscillator, the FitzHugh-Nagumo model, the Luo-Rudy model, and the O’Hara-Rudy model. By exploring the historical development, applications, and future directions of these models, this paper aims to highlight their significance and potential in advancing cardiac research and clinical practice.

BATTERY AND CAPACITIVE SYSTEMS FOR STORING ELECTRICAL ENERGY

Danijela Vuković — 2025-06-23

One of the important factors that hinders the widespread adoption of green technologies is the lack of environmentally friendly batteries. The electrochemical batteries are currently the best choice for storing electricity for most industrial needs and products. Unfortunately, the production of the metals needed to make the electrodes for electrochemical batteries is a serious environmental problem. Electrolytic capacitors that show high energy densities are acceptable to the industry, but they contain, in addition to metals, very harmful organic substances. Polymer and ceramic capacitors show very low energy density compared to the conventional batteries and therefore cannot be widely used for electricity disposal. At the same time, all other features of that capacitors that characterize battery systems are ideal. A brief comparison of the basic properties of electrochemical and physical batteries was presented. Some economic aspects were also described.

POSSIBILITY OF PRODUCING PHOTOVOLTAIC ELECTRICITY ON BALCONY FENCE IN PIROT, SERBIA

Ivana Radonjić Mitić — 2025-06-23

In urban environments, PV panels are usually affixed on available buildings, but they can also be included in the initial architectural design of the constructions. PV panels mounting on/as balcony fences become frequent solution for creating PV systems in buildings. The idea of decentralized production and storage of electricity very close to the point of use represents an additional benefit. In this paper, the possibility of using PV panels in urban conditions, within the home installations of individual residential consumers with the placing of panels on the balcony fence, is analyzed. A detailed simulation of the complete PV system in the PVSYST software was used for the analysis of different mounting options for PV panels on the balcony fence. For an individual consumer from the “Household type 3” category with an annual consumption of about 6000 kWh, the installation of PV panels with a total power of 1650 Wp was analyzed. Different variants of installation of PV panels were simulated for the case of two different tilt angles (0o (vertical position) and 60o) and three different azimuthal orientations (south, east and west). Self-consumption is modeled through typical daily profiles, taking into account seasonal variation for a given type of consumer. The obtained results show that in the investigated PV system, photovoltaic energy can cover from 15.84% to 29.48% of considered household’s self-consumption, depending on the tilt angle of the PV panels on the balcony fence and their azimuthal orientation.

REMOVAL OF AZO DYES FROM TEXTILE INDUSTRY WASTEWATER USING ELECTROOXIDATION AND ELECTRO-FENTON PROCESSES

Borislav N. Malinović — 2025-06-23

Wastewaters from the textile industry have a high content of organic matter, high coloration, various minerals and metals, and often toxic and carcinogenic substances. Azo dyes are the most common used dyes in the textile industry. Due to their complex structure, the removal of azo dyes from wastewater is challenging. In this study, electrooxidation and the electro-Fenton process, as one of the most effective Electrochemical Advanced Oxidation Processes (EAOPs) for the removal of organic pollutants in wastewater, were used for the treatment of synthetic wastewater containing “Bemacid Red” dye as a pollutant. Several process parameters affecting the efficiency of OH. formation and dye degradation were examined. Stainless steel (SS) was used as the cathode material, and the anodes used were mixed metal oxides (MMO) - Ru mixed oxide (titanium substrate coated with 6g Ru/m2) and Ru-Ir mixed oxide (titanium substrate coated with 6g Ru- Ir/m2). The results showed that the Ru:SS electrode pair is more efficient comapred to the Ru-Ir:SS pair, and that the electro-Fenton process is more efficient compared to electrooxidation.

ADHESIVE TYPE INFLUENCE ON THE COMPRESSIVE STRENGTH OF BEECH LVL REINFORCED WITH CARBON FIBER FABRIC

Vladislav Zdravković — 2025-06-23

In this research, nine-layer reinforced laminated veneer lumber (RLVL) was produced using beech veneer by inserting woven carbon fibers between the veneer sheets. Panels were made in industrial conditions with two types of adhesives - phenol-formaldehyde (PF) and polyurethane adhesive (PUR). The research aims to determine the influence of adhesives on the compressive strength in two directions of beech LVL reinforced with woven carbon fibers and its potential for use in load-bearing building structures. The experimental data was verified by the ANOVA model. Reinforced LVL produced using PF adhesive was stronger than those produced using PUR adhesive by 17.88% in longitudinal direction and by 31.89% in transverse direction. This research is part of an effort to encourage the implementation of hardwoods, especially beech, as renewable and ecologically sustainable material with long term use in load-bearing building structures.

DETERMINATION OF ACETALDEHYDE ADSORPTION ON SYNTHETIC ZEOLITES AND CHARACTERIZATION OF SAMPLES BY FTIR METHOD

Dragana Kešelj — 2025-06-23

Acetaldehyde is one of the most common carcinogenic organic compounds (pollutants) that can be found in the air in urban and industrial areas, as well as in indoor spaces. Generally, the most efficient method for removing pollutants from the air is adsorption with suitable adsorbents. To choose a suitable adsorbent, it is necessary to know its characteristics, the most significant of which is the adsorption capacity, i.e., the maximum amount of adsorbed substance per gram of adsorbent under given conditions. Nowadays, there is still a search for an adequate method that would provide an answer to how much and which organic substances are adsorbed on adsorbents. This paper presents the possibility of applying the FTIR analysis method for the identification and detection of adsorbed acetaldehyde on different types of zeolites. Adsorption of acetaldehyde from the gaseous phase was performed on ZSM zeolite (ZEOflair 100, ZEOflair 110), NaA zeolite (ZEOflair 1000), and the Na-form of mordenite (ZEOflair 800). Initial concentrations of acetaldehyde in the air ranged from 0.071 mol/m³ to 1.239 mol/m³, and the adsorption was carried out at atmospheric pressure, T=25 °C, and relative humidity (rH) 65%. On the FTIR spectra of the examined samples after adsorption, peaks were observed at a wavelength of 1700 cm⁻¹, which are characteristic of the carbonyl group of acetaldehyde. It was observed that the peak areas were proportional to the amounts of adsorbed acetaldehyde, which were very small and ranged from 0.107 mmol/g to 2.98 mmol/g of zeolite. Results indicate that FTIR is a rapid, non-destructive method suitable for qualitative and semi-quantitative analysis of low-level acetaldehyde adsorption, especially in the absence of co-adsorbed water.

BUCKLING ANALYSIS OF LAMINATED COMPOSITE PLATES

Gordana Tošić — 2025-06-23

This paper deals with laminated plates subjected to uniaxial compression. The effects of lamination scheme and material properties on the critical loads are considered, as well as variations of boundary conditions and direction of the acting loads. The buckling analysis was conducted using the finite elements method implemented in the Simcenter Femap software package. The obtained results were compared with the already available ones.

SHORT HISTORY RECAP OF SERBIAN GEOLOGY

Aleksandar Grubić — 2025-06-23

The author presents in a concise form the history of geology in Serbia and the Republic of Srpska. He begins with knowledge about the Earth in the Middle Ages among Serbs. Then, he continues in chapters to write: about the work of foreign geologists in Serbia and the transfer of knowledge from geology to our environment by domestic authors. This is followed by the emergence of the first geological centers and the influence of J. Pančić’s lectures on students’ interest in our science. The formation of the domestic school and staff with J. Žujović. Notable are: the progress of geology between the two world wars and the rapid development of the science and the profession after the Second World War. Its ups and downs have been connected with the state in the country until today. This also includes the separation, organization and activity in the geology of the Republic of Srpska.

ENHANCING EMISSION REDUCTION AND EFFICIENCY IN BIOMASS STEAM BOILERS THROUGH FGR: EXAMINING NOX PRODUCTION AND OPERATIONAL DYNAMICS

Mladen Tomić — 2025-06-23

As a result of efforts to follow sustainable development trends in thermal energy, the increasing utilization of biomass-fired boilers is notable as an environmentally acceptable alternative to conventional fossil fuel-based designs. However, while more ecologically viable, biomass boilers still emit specific pollutants, with particulate matter (PM), sulfur dioxide (SO2), nitrogen oxides (NOx), and carbon monoxide (CO) being the major concerns. To mitigate these emissions, modern biomass-fired boilers often incorporate Flue Gas Recirculation (FGR). This study examines a 14 MW biomass-fired boiler with a 20% FGR rate. Analysis encompasses three scenarios: two FGR levels and operation without FGR. The research reveals a complex interdependence between emissions reduction through FGR and boiler efficiency. Moreover, findings suggest justified reduction in FGR levels to enhance boiler efficiency. The study presents a comprehensive plan for efficient FGR implementation in biomass-fired boilers while maintaining acceptable efficiency levels. For NOx emissions analysis, combustion simulation software and the Zeldovich method were employed to estimate thermal NOx production.

THE IMPACT OF DISCONTINUITY ON THE STABILITY OF TUNNEL EXCAVATION IN KARST

Aleksandar Golijanin — 2025-06-23

The position of primary and secondary (stratification surfaces and fractures) discontinuities in relation to the tunnel route significantly affects the stability of the tunnel excavation. Primary discontinuities represent interlayer surfaces or stratification surfaces that formed during the period of rock formation itself, while secondary discontinuities represent fractures, i.e., discontinuities that formed after the sedimentation process was completed and are associated with tectonic activities. In addition to existing discontinuities, groundwater can also affect the stability of the tunnel excavation.

ESTIMATION OF CHRONOLOGICAL AGE, DENTAL AGE AND SKELETAL MATURITY USING ORTHOPANTOMOGRAPHY AND LATERAL CEPHALOGRAMS

Adriana Arbutina — 2025-06-23

The patient’s age is one of the most important factors influencing the planning of orthodontic therapy. In some patients, there is a discrepancy between chronological age, dental age and skeletal maturity, which can affect the outcome of orthodontic therapy. The aim of this work was to determine the correlation between chronological age, dental age and skeletal maturity in subjects of both sexes using orthopantomographic and lateral cephalometric images. For the purpose of this study, orthopantomographic and lateral cephalometric images of 315 orthodontic patients aged 8 to 18 years were used. Dental age was determined on orthopantomographic images using the Demirjian method, while skeletal maturity was determined on lateral cephalometric images by observing the second, third and fourth cervical vertebrae. The results of the study showed an extremely strong, positive and statistically significant correlation between dental and chronological age in both sexes (rs = 0.870, N = 315, p < 0.05), with the correlation being stronger in females (rs = 0.869). A positive, extremely strong and statistically significant correlation was also found between dental age and the CVM stage of the subjects (rs = 0.684, N = 315, p < 0.05). A statistically significant difference was found in the average dental age between the most of the CVM stages of the subjects (p < 0.05). Statistically significant differences in dental maturity were not recorded only between the 1st and 2nd CVM stages, as well as between the 3rd and 4th CVM stages. Based on the results obtained, it was concluded that there is a strong positive correlation between chronological age, dental maturity and skeletal maturity in subjects of both sexes. The correlation between dental maturity and chronological age was slightly stronger in females than in males.