Vinča Institute of Nuclear Sciences
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First-Principles Understanding of Mono- and Dual-Emissions in AZnOS:Bi3+ (A = Ba, Ca) Phosphors
No full textThe AZnOS:Bi3+ (A = Ba, Ca) phosphors exhibit mono- and dual-emission phenomena based on the different choices of cation, making them an ideal prototype for dual-emission mechanism studies of Bi3+ ions. Here, first-principles calculations were performed to investigate the site occupancy, defect levels, and luminescence properties of the AZnOS:Bi3+ systems. The formation energy calculations show that the bismuth dopants are mainly in the trivalent charge state, with the Bi3+ ions preferring the Ca sites in CaZnOS but the Zn sites in BaZnOS. Such cation-selective occupancy mainly results in the difference between the mono- and dual-emission phenomena in the two hosts. The excitation and emission energies predicted by calculations are in good agreement with the measurements. Our calculations show that the lowest excited state 3P0,1 provides the dominant emission in both CaZnOS:Bi3+ and BaZnOS:Bi3+ phosphors. In light of the experimental and theoretical results, the metastable excited state of Bi2+ + hVBM (hole at the valence band maximum) is the origin of the additional emission bands in BaZnOS:Bi3+. These results provide the basis of emission band tuning and novel material design for Bi3+-doped phosphors. © 2025 by the authors
ZnO nanoparticles enhance the efficiency of sodium hypochlorite disinfectant in reducing the adhesion of pathogenic bacteria to stainless steel surfaces
No full textThe use of commercial disinfectant in combination with other antimicrobial agent such as ZnO nanoparticles to improve disinfection efficacy could be a promising strategy in the control of pathogenic bacteria. In this context, the aim of study was to determine the minimum inhibitory concentration (MIC) of sodium hypochlorite disinfectant, ZnO nanoparticles as well as Mn-, Ce-, and Co-doped ZnO nanoparticles (doping concentrations 10%, 20%, 30%) against gram-negative bacteria Escherichia coli and Salmonella Typhimurium, and gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes using the broth microdilution method CLSI M07-A10, while the checkerboard microdilution method was carried out to assess the type interaction of sodium hypochlorite in combination with pure ZnO nanoparticles. The results specified that ZnO nanoparticles were agents that required higher concentrations to inhibit bacterial growth than sodium hypochlorite, whereby a synergistic effect was achieved in their combination. It was also revealed that doping of Mn and Co in ZnO nanoparticles improved antibacterial activity against gram-positive bacteria. Generally, this study aimed to evaluate the effectiveness of individual treatments (sodium hypochlorite and ZnO nanoparticles) and their combination on initial bacterial adhesion to stainless steel surfaces (AISI 304) exposed to different temperatures (7 °C, 25 °C, 37 °C) and pH (4.5, 7.0, 8.5) using colony-forming units count method. It was evident that ZnO nanoparticles were more effective than sodium hypochlorite in reducing bacterial adherence, while the combined tretmant showed a better effect than any individual treatment alone, highlighting its advantages as a novel disinfectant to prevent bacterial biofilms. Furthermore, data that temperature and pH affected bacterial adhesion provide comprehensive insight how bacteria survive in the food processing environments, which could assist in assessment the risk of contamination. © 2025 Elsevier Lt
Аnti-human melanoma effect of Fe(III)-containing Wells-Dawson polyoxotungstate and ascorbate: optimization of concentration ratio
No full textIn this study, the anti-human melanoma A375 effect of Fe(III)-substituted monolacunary WellsDawson polyoxometalate (Fe-WD), K7[FeIII(α2-P2W17O61)(H2O)] and L(+)-ascorbic acid sodium salt (ascorbate) mixed in the concentration ratios of 1:1 and 1:5 was evaluated. Exponentially growing A375 cells were exposed in vitro to Fe-WD, ascorbate, and Fe-WD/ascorbate mixtures for 48 and 72 h, at 37 °C. Fe-WD, ascorbate, and their mixtures resulted in concentration- and time-dependent cytotoxic actions with different potencies against A375 cells. The results of the simultaneous exposure to equimolar Fe-WD/ascorbate mixtures indicated an additive inhibitory effect of the mixture components on A375 cell viability. The equimolar Fe-WD/ascorbate ratio was found to be more favourable compared with the 1:5 Fe-WD/ascorbate ratio which demonstrated an antagonistic cytotoxic action of the studied compounds on A375 cells. Although the equimolar ratio is more suitable in the context of the potential pharmacological application of Fe-WD as an antitumor drug candidate in combination with ascorbate being commonly prescribed as a supplement therapy, further studies on different FeWD/ascorbate ratios generating abundant free radicals are suggested to find a more potent antitumor activity.International Conference “Annual conference on Challenges of Contemporary Higher Education” : February 2nd-7th, 2025, Kopaonik
Bifunctional Electrocatalysts for Alkaline Water Electrolysis Derived from Metal-Containing Ionic Liquids
No full textAbstract: Carbon-based electrocatalysts decorated with Pt and Ni nanoparticles were introduced herein to increase the efficiency of the water splitting process and thus reduce the price of the produced green hydrogen. The materials were prepared by innovative direct carbonization of ionic liquids containing the corresponding metal, thereby eliminating the need for additional solutions and templates. The structural integrity of the materials was validated through X-ray diffraction analysis and Fourier-transform infrared spectroscopy. The electrochemical performance of these materials in catalyzing hydrogen (HER) and oxygen (OER) evolution reactions was evaluated using voltammetry and electrochemical impedance spectroscopy, uncovering distinct behaviors and highlighting the role of ionic liquid in tailoring materials’ properties and performance. Specifically, the presence of Ni was observed to enhance the catalytic performance towards the HERs due to the interaction of Ni nanoparticles and a higher amount of sp2-hybridized carbon present. In contrast, incorporating Pt into the carbon matrix was found to augment the catalytic activity for OERs with a Tafel slope of 129 mV dec−1 and a current density of 10 mA cm−2 reached at a potential of 1.67 V. Moreover, chronoamperometric measurements evidenced materials’ steady performance under both HER and OER conditions. These findings of good activity and stability showed that the introduced approach of synthesis of carbon electrocatalysts decorated with heteroatoms by direct carbonization of ionic liquids holds great promise for the synthesis of efficient and affordable electrocatalysts for green hydrogen production
Testing algorithm for the computation of the transverse emittance of the ion beams generated by the ECR mVINIS ion source based on a pepper-pot method
No full textWithout knowing the emittance value, it is difficult to optimize ion beam optics for minimum beam loss during transmission, especially considering the very high emittance values of electron cyclotron resonance (ECR) ion sources. With this in mind, to measure the emittance of the ion beams produced by the mVINIS ECR, which is part of the FAMA facility at the Vinča Institute of Nuclear Sciences, we have developed a pepper-pot scintillator screen system combined with a CMOS camera. The application, developed on the LabVIEW platform, allows us to control the camera’s main attribute settings, such as the shutter speed and the gain, record the images in the region of interest, and process and filter the images in real time. To analyze the data from the obtained image, we have developed an algorithm called measurement and analysis of ion beam luminosity (MAIBL) to reconstruct the four-dimensional (4D) beam profile and calculate the root mean square (RMS) emittance. Before measuring emittance, we performed a simulated experiment using the pepper-pot simulation (PPS) program. An exported file (PPS) gives a numerically generated raw image (mock image) of a beam with a predefined emittance value after it has passed through a pepper-pot mask. By analyzing data from mock images instead of the image obtained by the camera and putting it into the MAIBL algorithm, we can compare the calculated emittance with PPS’s initial emittance value. In this paper, we present our computational tools and explain the method for verifying the correctness of the calculated emittance values. © 2025 Chinese Physical Society and IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.Peer reviewed manuscript: [https://vinar.vin.bg.ac.rs/handle/123456789/15100
Novel Ca-Sr-Ba hydroxyapatite: from nanoemulsion to dense bioceramic
No full textHydroxyapatite (HA) is widely recognized as a promising bioceramic material for bone replacement, due to its excellent biocompatibility and chemical similarity to natural bone. However, its inherent brittleness and limited mechanical performance often restrict its broader application. Ionic substitution at the calcium sites has emerged as a powerful strategy to tailor the structural and functional properties of HA. In this study, a novel ternary-substituted hydroxyapatite with the nominal composition (Ca,Sr,Ba)5(PO4)3(OH) was successfully synthesized using the Ouzo nanoemulsification method at room temperature, followed by calcination at 700 °C for 3 h. X-ray diffraction confirmed the formation of a pure apatite phase, with no secondary phases detected. The calcined powders were consolidated via spark plasma sintering, achieving theoretical density without decomposition. Microstructural analysis revealed a dense and uniform grain morphology. Assessment of mechanical properties revealed improved hardness and comparable Young’s modulus relative to traditional HA. Simulated body fluid test showed that apatite precipitation occurs within 24 h. The results suggest that Sr²⁺ and Ba²⁺ cosubstitution not only stabilizes the apatite phase but also enhances its sinterability and mechanical properties, while maintaining bioactivity. The ternary-substituted hydroxyapatite developed in this study shows great potential for applications in bone regeneration and implants.Programme and the Book of Abstracts / 8th Conference of The Serbian Society for Ceramic Materials, 8CSCS-2025, June 14-16, 2025, Belgrade, Serbia
Unveiling the energy landscape of Cr3Si3N8 through a multi-methodological approach
No full textA multi-methodological approach, combining Global optimization, Data mining, and the Primitive Cell for Atom Exchange (PCAE) method, was used to investigate the Cr3Si3N8 compound. Global optimization generated multiple structural candidates which were refined using ab initio calculations, yielding eight distinct phases. Unlike the previously investigated Cr2SiN4 and CrSi2N4 [1,2], where data mining identified multiple candidates along with the global minimum, this Cr3Si3N8 yielded only a single structure - the Li2ZnTiO-type.This structure ranked lowest with the GGA-PBE functional but showed slight improvement with DFTLDA calculations. The PCAE method also identified one additional candidate, bringing the total to ten promising structures, with the global search directly identifying the global minimum. Additionally, to examine the behavior of these phases under high-pressure conditions, values for bulk modulus, volume, total energy, and Gibbs free energy were calculated at pressures up to 10 GPa. Due to the lack of experimental data, two functionals were used to ensure the qualitative validity of the results. These findings provide a comprehensive understanding of the Cr3Si3N8 compound and suggest that the identified structure may serve as a promising candidate for future experimental studies and applications.Programme and the Book of Abstracts / 8th Conference of The Serbian Society for Ceramic Materials, 8CSCS-2025, June 14-16, 2025, Belgrade, Serbia
Composition universe of ceramic materials: the potential for discovering new functional ceramics through high-throughput analysis
No full textA vast number of possible ceramic compounds remains unexplored, despite intensive research in the field of materials science. Through combinatorial analysis with repetition, it is shown that even with a limited number of chemical elements (e.g., 60) and high compositional precision (steps of 0.1%), it is theoretically possible to form around 10^100 different materials - a number that exceeds the number of atoms in the known universe. When the space is limited to oxides with 20 elements and 1% compositional steps, the number of potential unique compositions still reaches the order of 10^19. However, experimentally, we only know a small fraction of this space, indicating the vast potential for discovering new functional ceramics, including spinel and perovskite structures. A systematic search of this "compositional universe", with the aid of high-throughput computational and experimental methods, represents the key to finding the next generation of materials for energy, electronics, and catalysis.Programme and the Book of Abstracts / 8th Conference of The Serbian Society for Ceramic Materials, 8CSCS-2025, June 14-16, 2025, Belgrade, Serbia
The gamma vanadium oxide as a potential cathode material for rechargeable aqueous multivalent ion batteries
No full textThe focus of this study is to investigate capabilities of gamma lithium vanadium oxide (γ-LiV2O5) to accommodate ions beyond Li+. The γ-LiV2O5 has been tested electrochemically as a potential candidate for novel aqueous rechargeable batteries based on multivalent ions, namely Mg2+, Ca2+ and Al3+. The γ-LiV2O5 is prepared by a simple solid-state reaction and characterized by XRD, SEM, HRTEM, FTIR, Raman, and Impedance methods, before and after CV cycling. Li+ ions can take octahedral cationic sites in the oxide lattice, which leads to γ ↔ γ′ reversible phase transition, but their subsequent occupation of tetrahedral sites incites irreversible γ ↔ ζ transition and capacity fade during extended cycling in LiNO3. In contrast, such irreversible behavior is not observed in Ca(NO3)2 and Mg(NO3)2, where initial repeated cycling, including negative potentials, causes the CV growth. Although Ca2+ and Mg2+ ions weekly intercalate into the structure, as indicated by BVS analysis, the proton coinsertion, during early cycling stage activates the surface, causing large platelets to crumble and boosting pseudocapacitive-type redox behavior. This results in a high specific capacity in bivalent electrolytes, especially in Ca(NO3)2, which amounts to 128 mAh g−1 at 1 A g-1. Although the agglomeration of reduced particles leads to a decline in capacity over extended cycling, the capacity remains high after 150 cycles, reaching 74 mAh g−1. In LiNO3, the identification of γ’ phase after long cycling within the stable potential window, together with agglomerated microplatelets (which are not crushed during initial Li+, thus limiting capacity to ≈ 27 mA hg−1) is linked to the capacity fade. Furthermore, when cycled in Al3+ electrolyte, the material degrades quickly due to the dissolution process at the beginning of cycling. Therefore, the Ca2+ electrolyte is identified as the most promising for the development of rechargeable aqueous batteries with gamma phase V2O5 cathode
Economic Viability of Hydrogen Production via Plasma Thermal Degradation of Natural Gas
No full textThis study evaluated the economic feasibility of producing hydrogen from natural
gas via thermal degradation in a plasma reactor. Plasma pyrolysis, where natural gas passes
through the space between electrodes and serves as the working medium, enables high
hydrogen yields without emitting carbon monoxide or carbon dioxide. Instead, the primary
products are hydrogen and solid carbon. Unlike conventional methods, this approach
requires no catalysts, addressing a major technological limitation. A thermodynamic equilibrium model based on Gibbs free energy minimization was used to analyze the process
over a temperature range of 500–2500 K. The results indicate an optimal temperature of
approximately 1500 K, which achieved a 99.5% methane conversion by mass. Considering
the capital and operating costs and profit margins, the hydrogen production cost was
estimated at 3.49 EUR/kg. The sensitivity analysis revealed that the price of solid carbon
had the most significant impact, which potentially raised the hydrogen cost to 4.53 EUR/kg
or reduced it to 1.70 EUR/kg