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Item Raspberry and blackberry grown in Serbia from the aspect of the green agenda(Naučno-stručno Društvo za zaštitu životne sredine Srbije ECOLOGICA, 2024) Zdravković, Milica; Grekulović, Vesna; Štrbac, Nada; Zdravković, Bojan; Gorgievski, Milan; Marković, Miljan; Marković, MarinaSerbia is one of the leading countries in the world in terms of raspberry and blackberry production. Production is focused on the cultivation of raspberries and blackberries for the purpose of the fruit selling, so large amounts of leaves of these two plants remain unused on plantations or are burned. In tradicional medicine, the healing effects of raspberry leaves and blackberry leaves are known, but due to the large production, it is impossible to use all the leaves for these purposes. Newer research indicates numerous possibilities of application of raspberry leaves and blackberry leaves. An important aspect is the use of raspberries and blackberries that grow near the mine. In addition to being used in medicine and pharmacy, extracts can be used as metal corrosion inhibitors. Depleted plant mass that can be used for biosorption, as a binding agent and starting component of cellulose production. Obtaining the extract instead of burning the leaves fulfills the first condition of the Green Agenda, which is decarbonization and reduction of industrial emissions. Environmental pollution is reduced with a focus on air quality. Better energy efficiency is achieved by an adequate selection of extragens. The circular economy is achieved by a system in which production resources (fruit and leaves) are encouraged, and waste, waste emission and energy outflow are significantly reduced. In addition to encouraging the economy and sustainable plant food systems that are characteristic of the Western Balkans, protection and investment in ecosystems is achieved.Item Malina i kupina gajene u Srbiji sa aspekta Zelene agende(Naučno-stručno Društvo za zaštitu životne sredine Srbije ECOLOGICA, 2024) Zdravković, Milica; Grekulović, Vesna; Štrbac, Nada; Zdravković, Bojan; Gorgievski, Milan; Marković, Miljan; Marković, MarinaSrbija je jedna od vodećih zemalja u svetu po proizvodnji maline i kupine. Proizvodnja je usmerena na gajenje maline i kupine radi prodaje ploda, pa velike količine lista ove dve biljke ostaju neiskorišćene na plantažama ili bivaju spaljene. U narodnoj medicini je poznato lekovito dejstvo lista maline i lista kupine, ali je zbog velike proizvodnje nemoguće iskorititi svu količinu listova u ove svrhe. Novija istraživanja ukazuju na brojne mogućnosti primene lista maline i lista kupine. Važan aspekt predstavlja upotreba maline i kupine koja raste u blizini rudnika. Pored upotrebe u medicini i farmaciji ekstrakti se mogu koristiti kao inhibitori korozije metala. Osiromašena biljna masa se može primeniti za biosorpciju, kao vezivno sredstvo i polazna komponenta proizvodnje celuloze. Dobijanjem ekstrakta umesto spaljivanja listova ispunjava se prvi uslov Zelene agende, a to je dekarbonizacija i smanjenje industrijskih emisija. Smanjuje se zagađenje životne sredine sa fokusom na kvalitet vazduha. Adekvatnim izborom ekstragensa postiže se bolja energetska efikasnost. Cirkularna ekonomija se postiže sistemom u okviru kojeg se podstiču proizvodni resursi (plod i list), a otpad, emisija otpada i energetski odliv bitno umanjuju. Pored podsticanja privrede i održivih prehrambenih sistema biljaka koje su karakteristične za Zapadni Balkan, postiže se zaštita i investiranje u ekosisteme.Item Application of AI in environmental protection: corrosion and biosorption(Naučno-stručno Društvo za zaštitu životne sredine Srbije ECOLOGICA, 2025) Zdravković, Milica; Marković, Miljan; Marković, Marina; Grekulović, Vesna; Gorgievski, Milan; Štrbac, Nada; Božinović, KristinaArtificial intelligence (AI) plays an important role in the field of scientific research. This paper aims to review the application of AI in corrosion and biosorption. The use of AI can advance the research process in terms of prediction, environmental and cost management, optimization and determination of the influence of parameters. Corrosion is a highly complex process that depends on many factors. Studying the interaction of these factors using AI enables better corrosion control. By applying AI, it is possible to determine the diverse influence of factors under real conditions using the database of numerous researches. In addition to the prevention and monitoring of corrosion and biosorption processes, it is important to focus the application of AI on environmentally friendly methods and chemicals. In this way, it is possible to identify compounds and materials of natural origin that can serve as substitutes for toxic compounds for corrosion protection or heavy metal removal. The importance of using non-destructive methods and monitoring data in real time is particularly emphasized, in order to avoid statistical errors. Optimization with the RSM method for corrosion and biosorption processes is widely used, determining process parameters where the best effect of corrosion protection and biosorption is achieved.Item White willow bark extract as a copper corrosion inhibitor in 0.5 M NaCl solution(University of Split, Faculty of Chemistry and Technology, 2025) Zdravković, Milica; Grekulović, Vesna; Štrbac, Nada; Huseinović, Edina; Gorgievski, Milan; Marković, Miljan; Božinović, KristinaCorrosion can generally be defined as the degradation of materials in a reaction between the material and its environment.1 Due to its corrosive effects, the corrosion of copper and its alloys in chloride-containing media has been widely studied.2 Copper Cu-DHP is phosphorus-oxygen-free copper that does not contain arsenic and is mainly used for the manufacture of piping, construction, and appliances.3 The study of white willow bark extract (WWBE) on the corrosion process of Cu-DHP in a 0.5 M NaCl solution was carried out using a non-destructive electrochemical method of electrochemical frequency modulation (EFM) and electrochemical impedance spectroscopy (EIS). The 0.5 M NaCl solutions without and with the addition of WWBE (0.1-0.5 g/L) were used as electrolytes. The 0.5 M NaCl solution with the addition of 0.5 g/L WWBE, without and with a copper plate was analyzed by ultraviolet-visible spectroscopy (UV-VIS). The white willow bark extract was prepared by evaporating the aqueous extract obtained by extracting dry white willow bark, with distilled water. The experiments were carried out at room temperature. The EFM results show that WWBE acts as a cathodic copper corrosion inhibitor.4 The highest value for the inhibition efficiency was obtained in the 0.5 M NaCl solution with 0.5 g/L WWBE. The Bode and Nyquist diagrams were created based on the EIS results. The results were fitted using an electrochemical equivalent circuit. The Nyquist diagram shows imperfect semicircles due to frequency dispersion.5 A linear line corresponding to the Warburg coefficient was found.4 An increase in the phase angle in the Bode plot in the presence of WWBE indicates the formation of a protective inhibitor film. The calculated values show that the corrosion process is diffusion-controlled without and with the addition of WWBE. Both electrochemical methods show that WWBE is adsorbed on the copper surface in 0.5 M NaCl solution by physisorption according to the Langmuir adsorption isotherm4. The Gibbs free energy values of adsorption are similar for EFM and EIS. The UV-VIS results show that immersion of copper in an electrolyte containing 0.5 g/L WWBE for 24 hours leads to a change in the absorbance maximum, indicating the presence of a copper-WWBE complex.6Item UV-VIS identification of copper complexes with inhibitor organic components in the electrolyte(University of Belgrade, Technical Faculty in Bor, 2025) Zdravković, Milica; Grekulović, Vesna; Huseinović, Edina; Vianello, Robert; Štrbac, Nada; Huremovic, Melita; Gorgievski, MilanThe UV-VIS method is an effective, non-destructive method that enables a better understanding of the electrolyte during corrosion. The aim of the study presented in this paper is to determine the existence of an organometallic complex in a 0.5 M NaCl solution with the addition of Rubus fruticosus L. leaf extract (RFLE). The experiments were conducted in a 0.5 M NaCl solution with the addition of RFLE (5 g/L and 10 g/L) with and without the immersion of a copper coupon. The results show that after the copper coupon standing in the electrolyte, there is a change in the absorbance maximum in the solution with 5 g/L RFLE, while no change is observed in the solution with 10 g/L RFLE. Such a change indicates the existence of a copper-RFLE complex in the solution with lower inhibitor concentration. In the case of RFLE, forming a copper complex with caffeic acid, isoquercetin and astragalin is possible. The absence of the complex at a concentration of 10 g/L RFLE can be attributed to a change in the mechanism and the lack of copper ions in the solution due to adequate corrosion protection.Item Application of AI in Environmental Protection: Corrosion and Biosorption(Naučno-stručno Društvo za zaštitu životne sredine Srbije ECOLOGICA, 2025) Zdravković, Milica; Marković, Miljan; Marković, Marina; Grekulović, Vesna; Gorgievski, Milan; Štrbac, Nada; Božinović, KristinaArtificial intelligence (AI) plays an important role in the field of scientific research. This paper aims to review theapplication of AI in corrosion and biosorption. The use of AI can advance the research process in terms of prediction,environmental and cost management, optimization and determination of the influence of parameters. Corrosion is a highlycomplex process that depends on many factors. Studying the interaction of these factors using AI enables better corrosioncontrol. By applying AI, it is possible to determine the diverse influence of factors under real conditions using the databaseof numerous researches. In addition to the prevention and monitoring of corrosion and biosorption processes, it is importantto focus the application of AI on environmentally friendly methods and chemicals. In this way, it is possible to identifycompounds and materials of natural origin that can serve as substitutes for toxic compounds for corrosion protection orheavy metal removal. The importance of using non-destructive methods and monitoring data in real time is particularlyemphasized, in order to avoid statistical errors. Optimization with the RSM method for corrosion and biosorption processesis widely used, determining process parameters where the best effect of corrosion protection and biosorption is achieve.Item Change in pH and conductivity during the rinsing and the biosorption of copper ions onto pumpkin peel(Univerzitet u Zenici, Fakultet inženjerstva i prirodnih nauka, 2025) Marković, Marina; Gorgievski, Milan; Marković, Miljan; Grekulović, Vesna; Štrbac, Nada; Zdravković, Milica; Božinović, KristinaThe changes in pH and conductivity during the rinsing of the pumpkin peel, and the biosorption of Cu2+ ions, were the subject of this work. The obtained data showed that the pH value of the solutions increased during the rinsing of the biosorbent, as a result of the transfer of H+ ions from the aqueous phase into the structure of the pumpkin peel. An increase in the conductivity value was observed in the initial period of rinsing the pumpkin peel, followed by a decrease. The increase in conductivity in the initial phase is contributed to the self-leaching of the alkali and alkaline earth metal ions from the structure of the pumpkin peel, which were transferred into the aqueous phase. The further decrease in conductivity is a result of the dilution of the aqueous phase. The pH value decreased during the biosorption of Cu2+ ions, as hydrogen ions were transferred from the pumpkin peel structure into the solution, and then exchanged with Cu2+ ions. The conductivity value increased during the biosorption process, with a rapid increase in the initial period of 5 minutes, due to the transfer of alkali and alkaline earth metal ions into the solution.Item DTA-TGA and thermodynamic studies of walnut shells used for the biosorption of Cu2+ ions from synthetic solutions(Fakultet Tehničkih nauka, Kosovska Mitrovica, 2025) Marković, Marina; Gorgievski, Milan; Marković, Miljan; Štrbac, Nada; Grekulović, Vesna; Zdravković, Milica; Milošević, NemanjaBiosorption is a simple, economical and environmentally friendly process of removing pollutants by binding them to biological material [1]. Biological materials that can be used to remove or recover organic and inorganic substances from aqueous solutions include living or dead microorganisms and their components, seaweed, plant material, industrial and agricultural waste and natural residues [2]. In this paper, the thermodynamic analysis of the biosorption of copper ions on walnut shells, as well as the DTA-TGA analysis of walnut shells, are presented. Thermogravimetry was used to study the thermal degradation characteristics of walnut shells. The sample was heated in an inert atmosphere from 20 to 900 oC, using a simultaneous DSC-TGA device SDT Q600 (TA Instruments). The TGA curve showed two stages of weight loss during heating. In the interval from 20 to 150 oC, a weight loss of 6.64% was recorded, which was due to the evaporation of moisture from the sample. Further weight loss of 69.05% was observed in the temperature range from 150 to 900 oC, which was due to the decomposition of hemicellulose, cellulose and lignin present in the biosorbent structure [3]. The DTA curve showed that the process was accompanied by an endothermic peak at a temperature of 279.81 oC. The total weight loss was 75.69%. Thermodynamic studies are conducted to investigate the influence of temperature on the biosorption process and to obtain information about the feasibility, spontaneity and nature of the process [4]. Therefore, thermodynamic parameters such as the change in Gibbs free energy (ΔG0), the change in enthalpy (ΔH0) and the change in entropy (ΔS0) were determined. In order to determine the thermodynamic parameters, 0.5 g of walnut shells were brought into contact with 50 mL of a synthetic solution of copper ions with a concentration of 0.2 g L-1, at different temperatures (25 oC, 35 oC and 40 oC). The obtained results for the change in Gibbs free energy (ΔG0 ) were negative at all three temperatures, indicating the feasibility of the process and spontaneous nature of the biosorption. The obtained positive value of enthalpy (ΔH0 = 1.12 kJ mol-1) indicates that the biosorption reaction is endothermic and consequently consumes energy. The negative value of entropy (ΔS0 = -6.26 J mol-1 K-1) indicates that there is less randomness at the interface between solid and solution.Item Al-Sn alloys as composite phase change materials for thermal energy storage: microstructural and thermal characterization(Fakultet Tehničkih nauka, Kosovska Mitrovica, 2025) Manasijević, Dragan; Balanović, Ljubiša; Marković, Ivana; Gorgievski, Milan; Stamenković, Uroš; Kovacević, AvramAl–Sn alloys are well known for their excellent resistance to wear and corrosion, as well as their solid mechanical performance, making them popular choices for bearing applications [1,2]. More recently, however, they have attracted attention as potential composite phase change materials (C-PCMs) for thermal energy storage (TES) systems. To determine their suitability for such applications, a thorough investigation of their thermal characteristics is essential. In this study, Al–Sn alloys containing 11.7, 22.4, 32.8, 41.1, and 53.4 atomic percent Sn were prepared by melting high-purity metals. Continuous stirring of the melt was employed to prevent segregation, followed by casting into stainless steel molds. The resulting ingots displayed uniform microstructures, free of cracks and pores. Thermal diffusivity of the solid Al–Sn samples was measured between 25°C and 150°C using the light flash method. Density at room temperature was determined via the Archimedes principle, while specific heat capacities across different temperatures were calculated using the CALPHAD (Calculation of Phase Diagrams) approach. Thermal conductivity values were then derived using an appropriate conversion relationship. Additionally, phase transition temperatures and the associated thermal effects were analyzed by differential scanning calorimetry (DSC). The study mapped how thermal conductivity changes with both alloy composition and temperature, and also assessed how latent heat of fusion varies across the compositions. Microstructural and phase composition analyses were performed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS). The findings offer valuable insights into the thermal behavior and microstructural characteristics of Al–Sn alloys, contributing to the development of advanced PCMs for thermal energy storage applications.Item Kinetic and DTA-TGA analysis of Cu2+ biosorption on hazelnut shells(Fakultet Tehničkih nauka, Kosovska Mitrovica, 2025) Gorgievski, Milan; Marković, Miljan; Štrbać, Nada; Manasijević, Dragan; Grekulović, Vesna; Jovanović, Dalibor; Marković, MarinaBiosorption can be defined as the ability of biomaterials to accumulate and concentrate heavy metals from even the most dilute aqueous solutions. The biosorption process involves a solid phase (biological material) and a liquid phase (solvent, usually water) containing the dissolved metal. [1]. In this work, hazelnut shells were used as biosorbents for the biosorption of Cu2+ ions from synthetic solutions. This paper presents the results of kinetic and DTA-TGA analysis of the biosorption of Cu2+ ions on hazelnut shells. A pseudo-first order kinetic model, a pseudo-second order kinetic model, an intraparticle diffusion kinetic model and an Elovich kinetic model were used to describe the kinetics of biosorption of Cu2+ ions with hazelnut shells. The change in the adsorption capacity of copper ions with time was determined by contacting a series of solutions of copper ions with an initial concentration of 0.2 g dm-3 with 0.5 g of the sample for different contact times. Biosorption was terminated after 90 minutes, assuming that this time was long enough to establish equilibrium in the system [2]. It can be seen from Fig. 1a that at the beginning of the process (in the first 10 minutes) the adsorption capacity increases sharply with the contact time. The sudden increase in capacity in the first 10 minutes of the process is due to the large number of active sites available on the surface of the adsorbent. Thereafter, until the end of the experiment, a slight increase in adsorption capacity can be observed, which is due to the decrease in available active sites and the decrease in the concentration of copper ions in the solution [3]. The pseudo-second order kinetic model, with the correlation coefficient R2 = 0.961, showed the best agreement with the experimental data. Based on this model it can be concluded that chemisorption is a possible binding mechanism of copper ions on the surface of hazelnut shells [4].Item Microstructural and thermal properties of the Al-Cu eutectic alloy(Fakultet tehničkih nauka, Kosovska Mitrovici, 2025) Manasijević, Dragan; Balanović, Ljubiša; Cimpoesu, Nicanor; Markovic, Ivana; Gorgievski, Milan; Stamenković, Uroš; Stepanović, AleksandraUnderstanding thermal characteristics such as thermal conductivity, specific heat capacity, and latent heat of fusion is crucial when developing phase change materials (PCMs) for latent heat energy storage (LHES) systems [1]. Among metal-based PCMs, aluminum-based eutectic alloys have emerged as some of the most extensively studied due to their favorable thermal and mechanical properties [2].In this study, the Al–33.6 mass% Cu eutectic alloy was investigated in terms of its microstructure, thermal diffusivity, thermal conductivity, specific heat, and latent heat of melting. Techniques including scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), differential scanning calorimetry (DSC), and the light flash method were employed. Analysis revealed that the alloy’s microstructure contains both fine and coarse (Al)+Al₂Cu eutectic phases. Measurements showed that specific heat, thermal diffusivity, and thermal conductivity all increase with temperature over the range of 25–400 °C. At room temperature, the alloy exhibits a thermal conductivity of 134.3 W·m⁻¹·K⁻¹. The latent heat of fusion was determined to be 319.5 J·g⁻¹. Overall, the findings highlight the strong potential of the Al–Cu eutectic alloy as a candidate material for use in phase change thermal energy storage applications.Item Thermal properties of eutectic Sn-0.7Cu alloy reinforced with graphene nanosheets produced by powder metallurgy technique(Fakultet Tehničkih nauka, Kosovska Mitrovica, 2025) Nedeljković, Milan; Mladenović, Srba; Ćosović, Vladan; Marković, Ivana; Petrović, Jasmina; Stamenković, Uroš; Mitrović, Milijana; Kovačević, AvramIn this research, the effect of graphene nanosheets (GNS) on the thermal conductivity of Sn-0.7Cu-xGNS (x= 0, 0.02, 0.04, 0.06, 0.08 and 0.1 wt.%) nanocomposite materials was investigated. The GNS were successfully incorporated into the matrix alloy using the powder metallurgy technique, which includes mixing and mechanical alloying, cold compacting and sintering. Thermal diffusivity was measured at room temperature in an inert protective atmosphere using the xenon-flash method. The Sn-0.7Cu matrix alloy has a thermal conductivity of 53 Wm⁻¹K⁻¹ [1], while GNS exhibit a significantly higher value of 5000 Wm⁻¹K⁻¹ [2]. Therefore, it can be predicted that adding GNS will enhance thermal conductivity. However, the situation becomes more complex with composite materials [3]. The obtained value for thermal conductivity of the matrix alloy is 28.42 Wm⁻¹K⁻¹, while the composite with a 0.08 %GNS has the highest thermal conductivity of 35.29 Wm⁻¹K⁻¹. However, as the GNS content further increases, the thermal conductivity decreases. The decrease in thermal conductivity can be attributed to the agglomeration of GNS along the grain boundaries. This agglomeration leads to the accumulation of dislocations, which distort the matrix lattice, increasing the probability of electron scattering. As a result, the number of effective electrons (as heat carriers) in the crystal is reduced, which raises resistance and decreases thermal conductivity. The results indicated that the incorporated GNS enhanced the thermal conductivity of the matrix alloy to a certain extent.Item Analysis and statistical modeling of copper ions biosorption onto calcined chicken eggshell(Serbian Chemical Society, 2025) Marković, Miljan; Gorgievski, Milan; Štrbac, Nada; Grekulović, Vesna; Zdravković, Milica; Marković, Marina; Stanković, DaliborThe study on the possible use of calcined chicken eggshells as a biosorbent for copper ions removal from aqueous solutions, as well as some comparisons between raw and calcined eggshells, are presented in this paper. SEM-EDS and FTIR analysis of the calcined chicken eggshell samples were performed. In addition, the DTA-TGA analysis on raw chicken eggshells was performed. The influence of various process parameters, such as solution pH, stirring rate, biosorbent mass and Cu2+ concentration, was investigated. The kinetic analysis using four different empirical kinetic models was performed. The equilibrium analysis was done using the Langmuir, Freundlich and Temkin isotherm models. The process was optimized using the response surface methodology based on the Box–Behnken design (RSM-BBD). The obtained results are compared to our previous study on raw eggshells as a biosorbent for Cu2+ removal, in order to determine the justification for biosorbent modification (i.e., the calcination of raw eggshells).Item Effect of heat treatment on the mechanical and structural properties of X155CrVMo12-1 steel(Univerzitet u Zenici, Fakultet inženjerstva i prirodnih nauka, 2025) Stamenković, Uroš; Marković, Ivana; Mladenović, Srba; Manasijević, Dragan; Milanović, Petar; Nedeljković, MilanThis paper investigates the effects of oil quenching and tempering at various temperatures on the mechanical and structural properties of X155CrVMo12-1 tool steel. The steel specimens were austenitized at 1030 °C for half an hour, followed by quenching and tempering at different temperatures. Mechanical properties were assessed by measuring the hardness of the samples after each heat treatment. Using the conversion formula, the tensile strength values were calculated based on the measured hardness. Structural changes were analyzed using optical microscopy. The results indicate that the highest hardness values were achieved after the quenching process. However, an increase in tempering temperature led to a decrease in hardness. Optical microscopy revealed that quenching caused the appearance of martensite in the microstructure, while tempering at various temperatures caused alterations in the martensite structure.Item Shifting from Physical to Virtual Classroom in Accounting Education: A Study of Students’ Experiences During the COVID-19 Pandemic in Serbia(Springer Nature, 2024) Fedajev, Aleksandra; Jovanović, Dejan; Veličković, MilicaThe COVID-19 pandemic onset has caused significant changes in all areas of human activities, with changes in education being among the most evident. The change in educational systems was particularly challenging for developing countries like Serbia, where most higher education institutions were still in the early stages of implementing information and communication technology (ICT) in education. The pandemic forced higher education institutions in Serbia to shift from traditional to distance learning to enable continuous teaching while implementing pandemic prevention measures. The purpose of this study was to explain how two variables—technological environment and educational environment during online courses—influence students’ perceived satisfaction with online courses and their ability to acquire additional professional skills. The statistical analysis in the study is based on surveying 180 bachelor students attending accounting education in distance learning mode. Study findings are used to define some recommendations for accounting educators in Serbia for updating future learning practices based on lessons learned during the pandemic. The derived recommendations may be useful for similar disciplines and other developing countries.Item Journal of Mining and Metallurgy, 60 A (1) (2024)(Univeristy of Belgrade, Technical Faculty in Bor, 2024) Bogdanović, Grozdanka; Sokolović, Jovica; Cocić, Mira; Stojković, Pavle; Balanović, KatarinaItem Survey on star partial order in indefinite inner product spaces(Matematički institut SANU, 2022) Stanišev, IvanaThis is a short survey on the star partial order for matrices which is considered in the spaces with indefinite metric. The specific geometry of these spaces effects even on the definition of a star partial order, demanding the existence of the Moore--Penrose inverse of a certain matrix. A characterization of this partial order is also given. Some of the interesting properties are generalized and illustrated by the appropriate examples.Item Quasihyponormal and Strongly Quasihyponormal Matrices in Inner Product Spaces(International Linear Algebra Society, 2012) Radojević, Ivana; Đorđević, DraganThe notion of quasihyponormal and strongly quasihyponormal matrices is introduced in spaces equipped with possibly degenerate indefinite inner product, based on the works that studied hyponormal and strongly hyponormal matrices in these spaces. Generalizations of some results known for normal and hyponormal matrices are established.Item New results for EP matrices in indefinite inner product spaces(Springer, 2014) Radojević, IvanaIn this paper we study J-EP matrices, as a generalization of EP-matrices in indefinite inner product spaces, with respect to indefinite matrix product. We give some properties concerning EP and J-EP matrices and find connection between them. Also, we present some results for reverse order law for Moore-Penrose inverse in indefinite setting. Finally, we deal with the star partial ordering and improve some results given in the “EP matrices in indefinite inner product spaces” (2012), by relaxing some conditions.Item Moore-Penrose Inverse in Indefinite Inner Product Spaces(University of Niš, Faculty of Sciences and Mathematics, 2017) Radojević, Ivana; Đorđević, DraganWe present the definition and some properties for the Moore-Penrose inverse in possibly degenerate indefinite inner product spaces. The extensions of appropriate results, given for matrices in Euclidean and nondegenerate indefinite inner product spaces are established. All this is done by using the concept of linear relations.