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Fermi Surface Characteristics in FeP2
No full textMarcasite compounds show an interesting interplay of spin, orbital, and lattice degrees of freedom and host properties relevant for applications and fundamental science. Electronic correlations that arise in this context are critical for tuning conductivity which is of interest in electrochemical reactions in catalysis but are also important to understand high values of cryogenic thermoelectric power factor in materials with 3d orbitals related to classical rare earth Kondo semiconductors. FeP2 marcasite is isostructural to small gap Kondo-insulator-like semiconductor FeSb2. It exhibits a cascade of temperature-induced spin but also conducting state transitions as temperature is lowered from the room-temperature high spin (HS) state [1]. There is metal-to- semiconductor transition on cooling to intermediate spin (IS) state below 120 K and semiconductor-to-bad-metal transition below 20 K as FeP2 enters low spin (LS) state. In my talk I will present Fermi surface characteristics of the bad metal [2]. Quantum oscillations are composed of three main oscillation frequencies with rather light carrier mass, about few te nths of bare electron mass on some pockets. Despite three-dimensional character of the unit cell and the absence of the van der Waals bonds, angular-dependence of observed frequencies indicates the presence of a two-dimensional Fermi surface sheet with trivial Berry phase but also two three- dimensional Fermi surface sheets with possible non-trivial Berry phase.Advances in Solid State Physics and New Materials - 30 years of the Center for Solid State Physics and New Materials at the Institute of Physics Belgrade, 19 – 23 May 2025, Belgrade, Serbia
Advancing food fortification with kinetics: Stabilizing vitamin D3 through calcium carbonate-based vehicles
No full textThe addition of vitamin D3 in food products is an important health strategy. The vitamin D is heat, moisture, oxidation and pH sensitive. Given the complexity and diversity of food matrices, the use of various encapsulation strategies can more effectively address the need for vehicle system, that ensure the long-term chemical and physical stability of vitamin D. Calcium carbonate-based vehicle, modified with polyvinyl alcohol (PVA) and D-α-tocopherol succinate, were synthesized and loaded with vitamin D3 (D3/X/CaCO3). The vehicle has a form of beadlet designed to protect vitamin D3. The obtained nanostructured D3/X/CaCO3 demonstrated the desirable characteristics for powdered food matrix-vitamin D based, such as: enhanced thermal stability of vitamin D3, efficient loading, and an extended shelf-life. A detailed analysis of the physicochemical behavior of vitamin D, both structurally and kinetically, was provided presenting the fully functionalized pre-food model systems. The proposed kinetic perspective could serve as a roadmap for vitamin D₃ stability
XGBoost-based calibration of the portable PAQMON 1.0 PM monitor in outdoor conditions
No full textU ovom radu su ispitane mogućnosti primene XG kalibracione procedure za PAQMON 1.0 prenosnu platformu u terenskim uslovima. Iako je PAQMON 1.0 portabilna platforma u kojoj je moguća integracija dodatnih senzorskih modula, za potrebe ovog istraživanja je korišćena verzija koja je prilagođena za monitoring masenih koncentracija respirabilnih čestica, kao i meteoroloških parametara. Merenja su sprovedena u Boru, tokom grejnog (GP) i negrejnog (NGP) perioda, kako bi se uzele u obzir sezonske razlike u klimatskim uslovima i kvalitetu vazduha, pri čemu platforma nije pokazala značajniji drift signala i stabilno je funkcionisala bez kvarova. Korelacija PM2.5 koncentracija sa referentnim Grimm EDM180 monitorom tokom GP iznosila je R = 0.65 (p ≤ 0.001) i R = 0.40 (p ≤ 0.001) tokom NGP. Primena XGBoost (XG) modela je u značajnoj meri poboljšala tačnost PM2.5 merenja u poređenju sa linearnim regresionim modelima. Dobijene vrednosti adjR² bile su 0.68 za GP i 0.44 za NGP, dok su NRMSE vrednosti varirale od 0.43 do 0.83. Iako su performanse XG modela bile nešto slabije tokom NGP, kalibracija ovom metodom omogućila je PAQMON 1.0 platformi da dostigne DQO od 50% tokom obe kampanje merenja. Rezultati potvrđuju praktičnu primenljivost XG kalibracije za unapređenje preciznosti jeftinih senzorskih sistema prilikom monitoringa kvaliteta vazduha.This study examines the applicability of the XG calibration procedure for the PAQMON 1.0 portable platform in field conditions. Although PAQMON 1.0 is designed to accommodate additional sensor modules, this study utilized a version adapted explicitly for monitoring respirable particulate matter concentrations and meteorological parameters. Measurements were conducted in Bor, Serbia, during both the heating (GP) and non-heating (NGP) periods to account for seasonal climate and air quality variations. The platform demonstrated stable performance without significant signal drift or hardware failures. The correlation between PM2.5 concentrations and the reference Grimm EDM180 monitor was R = 0.65 (p ≤ 0.001) during GP and R = 0.40 (p ≤ 0.001) during NGP. The application of the XGBoost (XG) model significantly improved the accuracy of PM2.5 measurements compared to linear regression models. The adjusted R² values were 0.68 for GP and 0.44 for NGP, while NRMSE values ranged from 0.43 to 0.83. Although the XG model exhibited slightly lower performance during NGP, its calibration enabled the PAQMON 1.0 platform to achieve a Data Quality Objective (DQO) of 50% in both measurement campaigns. These findings confirm the practical applicability of XG calibration for enhancing the accuracy of low-cost sensor systems in air quality monitoring
Pr3+-Activated Sr2LaF7 Nanoparticles as a Single-Phase White-Light-Emitting Nanophosphor
No full textSr2LaF7:xPr3+ (x = 0.2, 1, 2, 3, 5, 10, and 25 mol%) nanophosphors with a cubic Fm3m structure were hydrothermally synthesized, forming nearly spherical nanoparticles with an average diameter of approximately 32 nm. Diffuse reflectance measurement and excitation spectra showed a primary excitation peak of Pr3+ at 443 nm, corresponding to the ground state to the 3P2 level transition. Upon blue light excitation, Pr3+-activated Sr2LaF7 nanophosphors showed rich emission structure across the visible region of the spectrum, with blue (~483 nm), green (~525 nm), orange (~600 nm), and red (~640 nm) emissions, blue and orange being the most prominent ones. The relative intensities of these emissions varied with Pr3+ concentration, leading to tunable emission colors. The chromaticity showed slight variation with the Pr3+ content (0.350 < x < 0.417, 0.374 < y < 0.380), while the CCT value increased from 3118 K to 4901 K as the doping concentration increased. The optimized Sr2LaF7 with 2 mol% Pr3+ had the most intense emission with correlated color temperature (CCT) of 3628 K, corresponding to the warm white color. The proposed Pr3+-doping strategy offers valuable insights into discovering or optimizing single-phase phosphors for white-light-emitting applications. © 2025 by the authors
Graphene Quantum Dots in Bacterial Cellulose Hydrogels for Visible Light-Activated Antibiofilm and Angiogenesis in Infection Management
No full textA novel bacterial cellulose (BC)-based composite hydrogel with graphene quantum dots (BC-GQDs) was developed for photodynamic therapy using blue and green light (BC-GQD_blue and BC-GQD_green) to target pathogenic bacterial biofilms. This approach aims to address complications in treating nosocomial infections and combating multi-drug-resistant organisms. Short-term illumination (30 min) of both BC-GQD samples led to singlet oxygen production and a reduction in pathogenic biofilms. Significant antibiofilm activity (>50% reduction) was achieved against Staphylococcus aureus and Escherichia coli with BC-GQD_green, and against Pseudomonas aeruginosa with BC-GQD_blue. Atomic force microscopy images revealed a substantial decrease in biofilm mass, accompanied by changes in surface roughness and area, further confirming the antibiofilm efficacy of BC-GQDs under blue and green light, without any observed chemical alterations. Additionally, the biocompatibility of BC-GQDs was demonstrated with human gingival fibroblasts (HGFs). For the first time, in vitro studies explored the visible light-induced potential of BC-GQD composites to promote wound healing processes, showing increased migratory potential and the upregulation of eNOS and MMP9 gene expressions in HGFs. Chemical characterization revealed a 70 nm upshift in the photoluminescence emission spectra compared to the excitation wavelength. These novel photoactive BC-GQD hydrogel composites show great promise as effective agents for wound healing regeneration and infection management. © 2025 by the authors
The Erythrocyte Fatty Acid Profile in Multiple Sclerosis Is Linked to the Disease Course, Lipid Peroxidation, and Dietary Influence
No full textBackground/Objectives: Dietary lifestyle, particularly the intake of fatty acids (FAs), may be useful in alleviating the key pathogenic processes in multiple sclerosis (MS); however, the data are still scarce, particularly with regard to the course of disease. Therefore, the objectives of this study were to investigate the erythrocyte profile of FAs in patients with relapsing-remitting (RR)MS and progressive (P)MS, and to examine whether dietary supplementation with n-3 PUFAs could influence the FA profile, according to the course of disease. Methods: The FA profile was determined in erythrocytes by gas–liquid chromatography, in 153 patients with RRMS and 69 with PMS, whereas the group on dietary supplementation with n-3 PUFAs consisted of 36 RRMS and 17 PMS patients. Individual FAs were quantified as a percentage of the total identified FAs and analyzed in relation to the demographic and clinical parameters. Results: Compared to RRMS, the PMS patients had higher saturated (S)FAs, n-7 mono-unsaturated (MU)FAs, and n-3 polyunsaturated (PU)FAs, and lower n-6 PUFAs. In the group on omega-3 supplementation, the only difference in FA profile was higher MUFA 16:1n-7 (POA) in PMS than RRMS patients. In PMS patients, there was a positive correlation of disability (EDSS) with the total SFA levels, whereby 16:0 (PA) correlated positively with EDSS and MS severity (MSSS). Also, in PMS, the MSSS correlated negatively with the total and individual n-6, and positively with the total and individual n-3 PUFAs. In PMS patients on n-3 supplementation, there was a negative correlation between MSSS and total n-6/n-3 ratio, and a positive one between MSSS and 22:6n-3 (DHA). The observed decrease in levels of circulating lipid peroxidation product 4-HNE in PMS patients was not found in the n-3 PUFA supplementation group. Conclusions: The present findings suggest that the changes in the levels of FAs and their correlations are specific for the course of MS. Detected FA profile differences can be influenced by n-3 supplementation, primarily in regard to SFAs and PUFAs, supporting an option for the use of dietary supplements in managing the clinical course and progression of MS
Luminescence Thermometry Based on Time Gates: Highly Sensitive Approach for Real-Time Sensing and Imaging
No full textUndoubtedly, one of the most significant advantages of luminescence thermometry is its ability to be used not only for spot temperature measurements but also for imaging temperature changes. Among the commonly proposed approaches, luminescence thermometry based on luminescence kinetics holds particular promise. However, most thermometric studies rely on the analysis of luminescence decay profiles, a method that significantly hinders, if not entirely precludes, real-time thermal imaging. In this Letter, we propose an alternative approach based on the luminescence intensity ratio integrated over two temporal gates. Tests conducted on two representative phosphors, Ba2LaNbO6:1%Mn4+ and Ca2LaNbO6:1%Mn4+, demonstrate that the proposed method not only enables thermal imaging but also achieves substantially higher relative sensitivity, reaching SR = 17.1% K-1 for Ba2LaNbO6:1%Mn4+ and SR = 9.4% K-1 for Ca2LaNbO6:1%Mn4+, compared to the conventional lifetime-based approach (SR = 4.2% K-1 for Ba2LaNbO6:1%Mn4+ and SR = 1.2% K-1 for Ca2LaNbO6:1%Mn4+). Furthermore, the careful selection of gate lengths allows optimization of the thermometric performance of the proposed luminescent thermometers. This approach enables expansion of the thermal operating range at the cost of relative sensitivity, providing versatility to adapt the thermometer for specific applications. © 2025 The Authors
Electrophoretic deposition of Pr3+- doped Lu2SiO5 thin films for antimicrobial applications
No full textIn this study, we utilized electrophoretic deposition to create antibacterial thin films from Pr³⁺- activated powders. The motivation for this research stems from the unique luminescent properties of Pr³⁺-doped materials. In cases where the Pr³⁺ lowest-energy 4f5d state is located below the 4f2 1S0 state, Pr³⁺ ions facilitate two-photon blue light upconversion to the ultraviolet C (UVC) spectral range. UVC light has widely known germicidal properties, which means it may effectively kill microorganisms such as bacteria, viruses, and fungi. As a result, UVC is employed in a variety of disinfection processes, including water and air purification and surface sterilization in healthcare settings. This study intends to develop functional coatings with biocidal capabilities under visible light using the upconversion properties of Pr3+-doped materials. At first, single-phase Lu₂SiO₅ doped with 0.5 mol% Pr³⁺ was produced by a Pechini-type polymerized complex technique. This method involves a polyesterification reaction between citric acid and ethylene glycol, yielding a precursor material subsequently utilized for electrophoretic deposition. Subsequently, we fabricate thin films on conductive aluminum substrates using the electrophoretic deposition of the precursor powder. Both films and precursor powders undergo full characterization employing several analytical techniques. The methods employed comprised X-ray diffraction for analyzing the crystal structure, scanning electron microscopy for examining morphology and surface characteristics, and photoluminescence spectroscopy for evaluating upconversion emission. To assess the efficacy of thin films for germicidal applications, experiments were conducted on gram-positive bacteria (Staphylococcus aureus), gram-negative bacteria (Escherichia coli), and fungus (Candida albicans), chosen due to their relevance in clinical and environmental settings.FEMS EUROMAT 2025 : 18th European Congress and Exhibition on Advanced Materials and Processes : 14-18 September 2025, Granada, Spain
Adsorption of organothiophosphate pesticides from water onto activated carbon materials obtained by carbonization of viscose fibers
No full textОргано-тиофосфатни пестициди играју кључну улогу у савременој пољопривреди, посебно у развијеним земљама, где се широко користе за контролу и сузбијање биљних болести и штеточина. Међутим, њихова прекомерна употреба доводи до озбиљног загађења животне средине, нарочито водених екосистема, а њихови токсични ефекти негативно утичу на људско здравље. Ови пестициди делују као инхибитори ацетилхолинестеразе, што изазива поремећаје у неуротрансмисији и може довести до озбиљних здравствених проблема. Због потенцијалних ризика, постоји потреба за развојем ефикасних метода за уклањање пестицида из воде и других природних ресурса. Адсорпција на различите материјале, као што су активни угљенични материјали, представља један од најефикаснијих начина за смањење концентрације ових пестицида у водама. Ова докторска дисертација се бави синтезом угљеничних материјала добијених карбонизацијом вискозних влакана и испитивањем њихове примене у процесу адсорпције органотиофосфатних пестицида из водених раствора. Основни циљ истраживања је утврђивање ефикасности адсорпције и процена потенцијалне примене ових материјала у заштити животне средине, посебно у области пречишћавања воде. Материјали су синтетисани коришћењем три различита приступа, а њихове физичкохемијске особине детаљно су анализиране применом скенирајуће електронске микроскопије (енг. scanning electron microscopy - SEM), енергетски дисперзивне рендгенске анализе (енг. energydispersive X-ray analysis - EDX), Раманске спектроскопије, инфрацрвене спектроскопије са Фуријеовом трансформацијом (енг. Fourier-transform infrared spectroscopy - FTIR), мерења зета потенцијала и BET (енг. Brunauer–Emmett–Teller – BET) анализе површине. Испитивана је адсорпција органо-тиофосфатних пестицида у стационарним и динамичким условима, уз варирање температуре и концентрације, док су концентрације пестицида у раствору одређиване применом течног хроматографа ултра високих перформанси (енг. ultra-performance liquid chromatography - UPLC). Кинетика и термодинамика адсорпције анализиране су применом модела псеудо-првог и псеудо-другог реда, Еловичевог модела и модела интрачестичне дифузије. Подаци су додатно обрађени применом различитих адсорпционих изотерми, као што су Лангмирова, Фројндлихова, Темкинова, Дубинин-Радушкевичева и Сипсова изотерма. Поред тога, праћено је смањење токсичности третираних узорака мерењем активности ензима ацетилхолинестеразе (AChE), као и регенерација употребљених адсорбенаса. Материјали су тестирани и на реалним узорцима (биљни екстракти и чесменска вода). Очекује се да резултати добијени у оквиру ове докторске дисетације допринесу бољем разумевању механизама адсорпције органо-тиофосфатних пестицида на угљеничним материјалима и омогуће развој ефикасних, економичних и одрживих метода за уклањање ових загађивача из водених система.Organophosphate pesticides play a key role in modern agriculture, particularly in developed countries, where they are widely used to control plant diseases and pests. However, their excessive use leads to serious environmental pollution, especially in aquatic ecosystems, and their toxic effects negatively impact human health. These pesticides act as acetylcholinesterase inhibitors, causing neurotransmission disruptions and potentially leading to severe health problems. Due to the potential risks, there is a need to develop efficient methods for removing pesticides from water and other natural resources. Adsorption onto various materials, such as activated carbon materials, is one of the most effective ways to reduce the concentration of these pesticides in water. This doctoral dissertation focuses on synthesizing carbon materials obtained by the carbonization of viscose fibers and their application in the adsorption of organophosphate pesticides from aqueous solutions. The primary goal of the research is to determine the adsorption efficiency and evaluate the potential application of these materials in environmental protection, particularly in water purification. The materials were synthesized using three different approaches, and their physicochemical properties were thoroughly analyzed using scanning electron microscopy (SEM), energy-dispersive Xray analysis (EDX), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), zeta potential measurements, and Brunauer–Emmett–Teller (BET) surface area analysis. The adsorption of organophosphate pesticides was investigated under both static and dynamic conditions, with variations in temperature and concentration, while pesticide concentrations in the solutions were determined using ultra-performance liquid chromatography (UPLC). The kinetics and thermodynamics of adsorption were analyzed using pseudo-first-order and pseudo-second-order models, the Elovich model, and the intraparticle diffusion model. The data were further processed using various adsorption isotherms, including the Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Sips isotherms. Additionally, the reduction in the toxicity of treated samples was monitored by measuring acetylcholinesterase (AChE) activity, and the regeneration of the used adsorbents was also evaluated. The materials were tested on real samples (plant extracts and tap water). The results are expected to contribute to a better understanding of the mechanisms of organophosphate pesticide adsorption on carbon materials and enable the development of efficient, costeffective, and sustainable methods for removing these contaminants from water systems
Pyrophyllite schist - a natural purifier for zinc removal from water
No full textBio Comp Water Clean Workshop "New applications in wastewater treatment on the way to zero-waste technology", 20-21st 2025, Novi Sa