Vol. 15 No. 1 (2025) | Bulletin of Natural Sciences Research

Open Access Original Scientific Paper

STRUCTURAL AND ELECTROCHEMICAL PROPERTIES OF SYNTHESIZED NANOSTRUCTURED Ca0.9Er0.1MnO3 BY HYDRAZINE NITRITE PROCEDURE

by Tijana B. Vlašković, Milena Rosić, Branka B. Petković, Bojana B. Laban

Synthesis, structural, and electrochemical properties of nanostructured powders Ca0.9Er0.1MnO3 with perovskite-type crystal were studied. Nanopowders were prepared by the combustion method using the hydrazine nitrite procedure (HNP), which involves mixing metal nitrate salts (Ca, Mn, Er) in a stoichiometric ratio and varying the quantity of added hydrazine. In this synthetic procedure, the aim is to adjust the amount of hydrazine in order to control the combustion of the reactions, obtain the required amount of fuel energy, but also the amount that will complex the reactants in the mixture. The powders obtained by hydrazine nitrate synthesis were then calcined for 15 minutes at temperatures of 800, 900, and 1000 °C. Characterization of the synthesized and calcined samples was performed using advanced techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and electrochemical measurements. The results clearly indicate that the amount of hydrazine added is crucial in preparing the Ca0.9Er0.1MnO3 sample. This highlights the importance of precise hydrazine dosage in optimizing the synthesis process to enhance the material's properties. Further, the electrochemical properties of the obtained perovskite nanopowders were investigated by cyclic voltammetry (CV) and electrochemical spectroscopic impedance (EIS) on perovskite-modified carbon paste electrodes. Electrochemical measurements showed improved electrochemical properties of perovskite-modified carbon paste electrodes compared to bare carbon paste electrode (CPE). The electrode modified with the material synthesized with the smallest amount of hydrazine presented the best results.

View Full-Text DOI 10.5937/bnsr15-61823 Published: 25 Dec 2025

Open Access Original Scientific Paper

HYBRID BLE–PDR LOCALIZATION SYSTEM FOR SMART RETAIL ENVIRONMENTS

by Nebojša Andrijević, Zoran Lovreković, Bojan Jovanović, Vladan Radivojević, Nenad Živanović

Accurate indoor user localization is a key component in the development of cashier-free smart stores, enabling advanced customer experiences, security monitoring, and behavioral flow analysis. This paper presents a hybrid localization approach that combines inertial motion tracking (Pedestrian Dead Reckoning – PDR) with Bluetooth Low Energy (BLE) tag signals. Unlike systems that require dedicated infrastructure, the proposed solution uses existing BLE electronic shelf labels (ESLs) as reference points. Their identification signals are used to correct the PDR drift, thereby reducing the cumulative error typical of purely inertial methods. The mobile application continuously measures the Received Signal Strength Indicator (RSSI) from BLE tags and applies threshold-based position corrections, while the PDR module, based on the Scarlett step-length model, maintains continuous tracking between tags. The system additionally integrates map-based spatial constraints that eliminate physically impossible paths through a particle-filter mechanism. Experimental evaluation in a retail environment demonstrated an average error of 0.4 m for linear movement and 1.3 m for a complex circular trajectory, confirming meter-level localization accuracy without the need for cloud processing. All computations are performed locally on the user’s device, ensuring privacy protection and enabling real-time movement analysis and context-aware retail interaction.

View Full-Text DOI 10.5937/bnsr15-62101 Published: 12 Dec 2025

Open Access Original Scientific Paper

ASSESSMENT OF THE MEDICINAL PROPERTIES AND COMPONENTS OF THE BLEND OF THREE INDIGENOUS ESSENTIAL OILS (Syzygium aromaticum, Monodora myristica, AND Xylopia aethiopica) FROM AFRICA

by Shola Hezekiah Awojide, Abayomi Gideon Adeyemo, Aminat Adebola Adeyemo, Elijah Titilayo Blessing, Adebanjo Jacob Anifowose, Omolara Oladipo-Olalekan, Emmanuel Oluwafemi Adeniyi, Ummuhani Titilayo Abdulazeez

The essential oils of Syzygium aromaticum, Monodora myristica, and Xylopia aethiopica have been used widely in Africa for medicinal purposes. This work is aimed at finding out the combined medicinal efficacy of the three essential oils. The crude EOs were extracted by the hydrodistillation method. The chemical components were determined by GC-MS analysis. The phytochemicals, antidiabetic, anti-inflammatory, and antioxidant activities were determined by standard analytical methods. The GC-MS analysis indicated eugenol (75.08%) as the major component in the EO of S. aromaticum, isocaryophyllene (29.36%) in the EO of M. myristica, isospathulenol (8.67%) in the EO of X. aethiopica, and eugenol (34.25%) in the blend of the EOs. The phytochemicals in all the EOs and the blend were at varying values. α-amylase and α-glucosidase inhibition showed that the EO blend with an IC50 value of 1250.69 µg/mL and 1080.56 µg/mL, respectively, had the highest inhibition compared with other EOs. S. aromaticum had the highest activity against the anti-inflammatory indicators. The least inhibitory activity for DPPH was recorded with M. myristica EO. S. aromaticum recorded the highest inhibitory efficacy against ABTS and nitric oxide assays, respectively. The blend recorded the highest inhibitory activity against lipid peroxidation, with an IC50 value of 827.22 µg/mL. The findings demonstrated that the crude EOs and the blend exhibited medicinal activities. However, the EO blend had higher potency.

View Full-Text DOI 10.5937/bnsr15-55354 Published: 17 Nov 2025

Open Access Original Scientific Paper

AN INFORMATION-PHYSICAL PERSPECTIVE ON FADING PROCESS TRANSITIONS BASED ON HIGHER ORDER STATISTICS

by Stefan Panić

This paper proposes a novel theoretical framework for analyzing fading channels by introducing the concepts of energetic orbits and entropy barriers. Inspired by atomic physics and thermodynamic analogies, here the signal envelope is modeled as a stochastic process whose transitions between different structural regimes (extrema, inflection points, level crossings) correspond to energy quantization events. Each transition is associated with a local information-energy quantum, defined as a product of amplitude displacement and transition count, normalized by local entropy. Furthermore, the ideas of entropic spin and degeneracy of states have been explored, and the dispersion of level-crossing processes, extremum-crossing process, inflection point-crossing process, saddle point-crossing process (LCR, ECR, ICR, SCR) through an autocorrelation-based energetic formalism has been characterized. This approach enables the construction of a layered energetic map of fading dynamics and offers new insights into the structural behavior of wireless signals under stochastic fluctuations.

View Full-Text DOI 10.5937/bnsr15-59743 Published: 09 Oct 2025

Open Access Original Scientific Paper

BIOACCUMULATION OF HEAVY METALS IN THE ROMAN SNAIL (HELIX POMATIA) IN THE AREA OF KOSOVSKA MITROVICA

by Željko Bulatović, Tatjana Jakšić, Maja Pavlović, Nikola Bačević

The bioaccumulation of heavy metals in the Roman snail (Helix pomatia Linnaeus, 1758) was investigated in October 2024. Animals were sampled at the location "Gornje Polje," which is situated near the former "Trepča" plant. The snails were collected by hand and then transported to the laboratory. A total of 34 medium-aged snails and 36 older snails were collected. The snails were dissected, and the content of heavy metals determined in the hemolymph, hepatopancreas, kidney and shell. In addition to analyzing the heavy metal content in the snails, an analysis of the heavy metals content in the soil was performed. The soil was collected in a quantity of 1 dm³ using a shovel and transported to the laboratory. The content of seven elements was examined: Arsenic (As), Copper (Cu), Iron (Fe), Cadmium (Cd), Manganese (Mn), Lead (Pb), and Zinc (Zn). The highest level of accumulation is heavy metal observed in the hepatopancreas. Furthermore, other structures exhibit a significantly high level of accumulation. All of this suggests that snails are a highly useful tool for diagnostic purposes in environmental of heavy metal accumulation. The analysis of heavy metal content was performed at the Public Health Institute of Kosovska Mitrovica.

View Full-Text DOI 10.5937/bnsr15-57799 Published: 23 Sep 2025

Open Access Original Scientific Paper

AN IMPROVED CANOPY INTERCEPTION SCHEME INTO BIOGEOCHEMICAL ANALYSIS OF WATER FLUXES IN SUBALPINE CONIFEROUS FOREST (NORTHERN ITALY)

by Polina Lemenkova

The delicate ecosystems of the Alps' subalpine forests are crucial to water supplies as well as the local and mesoscale climate regulators. Although earlier research has assessed various aspects of the water balance, there is currently a dearth of studies that directly measure every component of the water budget. Furthermore, little is understood about the frequency and impact of fog as well as how forest layout affects water balance. Using the eddy covariance technique, sap flow sensors, phenocam images, throughfall and stemflow gauges, soil moisture sensors, water discharge measurements, and a fog interception gauge, we carried out a thorough investigation of a subalpine coniferous forest at the Renon site in the Italian Alps. Furthermore, we measured the leaf area and lichen occurrence as possible canopy water storage components. Large amount of precipitation was reflected by the canopy interception in spruce and coniferous forest. Although fog alone had no effect on total water intake, it did result in a tiny but noticeable increase in throughfall during mixed fog and rain precipitation events, however this effect seemed to be less significant than in cloud forests that are tropical or subtropical. At the catchment level, the annual balance (November–October) was almost perfectly closed when all input and output components were taken into account. This paper contributes to the ecological monitoring of the Alpine forests in South Tyrol, Northern Italy.

View Full-Text DOI 10.5937/bnsr15-57655 Published: 21 Jul 2025

Open Access Original Scientific Paper

AN APPLICATION OF RESIDUE NUMBER SYSTEM ARITHMETICS TO SECURE HASH FUNCTIONS DESIGN

by Milija Pavlović, Stefan Panić, Boris Damjanović, Negovan Stamenković

This paper presents a cryptographic hash function based on the Residue Number System (RNS), designed to enhance security and computational efficiency. The function leverages the parallelism and modular properties of RNS to achieve high-speed processing while maintaining strong diffusion and resistance to various cryptanalytic attacks. Experimental results confirm that the proposed function exhibits a pronounced Avalanche effect, ensuring that minor changes in the input result in significant alterations in the hash output. Additionally, statistical analysis using the ENT test demonstrates a high level of entropy and uniform distribution of hash values, reinforcing the function’s unpredictability—an essential characteristic for cryptographic security. The proposed hash function is suitable for applications in digital signatures, data integrity verification, and authentication systems, offering advantages in environments requiring high computational efficiency.

View Full-Text DOI 10.5937/bnsr15-58114 Published: 11 Jun 2025

Open Access Original Scientific Paper

SPECIFICITY OF GEOGRAPHICAL CONTENT FOR THE APPLICATION OF DEBATE IN GEOGRAPHY LESSONS

by Ivana Đorđević

Modern geography teaching involves a more intensive use of methods designed to encourage students to learn with reason, to think reasonably and to draw independent conclusions. One of the methods that can contribute to achieving the above goals is certainly the use of debate and its increased implementation in geography lessons. Debating is a form of dialogic method that involves a discussion between two teams and the exploration of a given topic through argumentative practice. The paper analyzes the content of geography lessons that can be learned through debating and its application in the classroom from a theoretical and practical perspective. The first part of the paper is devoted to the theoretical foundations of teaching methods, the conceptual definition of debate, the Karl Popper format and the rules that should be applied in classroom practice. The second part of the paper deals with the application of debate in geography lessons using a content analysis with concrete examples from the subject. The results of the paper show the importance of debate for the development of skills that students in Serbia lack, including argumentative reasoning, public speaking, collaboration and research skills.

View Full-Text DOI 10.5937/bnsr15-56225 Published: 13 Apr 2025

Open Access Original Scientific Paper

OPTIMIZATION OF FLUID VOLUME CONTROL IN HEMODIALYSIS USING FEDERATED LEARNING

by Suzana Đorđević, Stefan Ćirković, Danijela Milošević, Milan Gligorijević, Vladimir Mladenović

Overhydration (OH) represents a significant challenge for hemodialysis patients, significantly affecting the outcomes of their treatment. Accurate prediction and management of overhydration are key to optimizing therapy and improving patients' quality of life. The aim of this paper is to present a federated learning (FL)-based approach designed to predict overhydration in hemodialysis patients, using a dataset comprising different clinical and bioimpedance parameters. Federated learning enables collaborative learning from multiple data sources while preserving the privacy and security of individual patient data. Research results show that federated learning has the potential as an effective tool for predictive modeling in clinical settings. The developed models achieve high performance in overhydration estimation, with metrics confirming their accuracy and reliability. The proposed approach achieved a R² of 0.9999999, a MAE of 0.00018 and an MSE of 0.0031, demonstrating its predictive strength and practical applicability. This study highlights the advantages of federated learning in using distributed data to advance predictive capabilities in healthcare. By overcoming challenges related to privacy and data security, the approach presented in this paper opens up opportunities for more personalized and accurate prognoses, potentially improving decision-making and patient care in hemodialysis.

View Full-Text DOI 10.5937/bnsr15-55563 Published: 02 Mar 2025

Open Access Original Scientific Paper

EXPLORING THE NEXUS OF TOURISM DEVELOPMENT, COMMUNITY PERCEPTIONS, AND SUSTAINABILITY IN PROTECTED AREAS

by Sanja Obradović Strålman, Nikola Milentijević

Sustainable tourism integrates economic, social, and environmental aspects of sustainability. This study investigates the local community’s perceptions of tourism development impacts and factors influencing support for sustainable tourism and destination sustainability within Stara Planina Nature Park. Using a Structural Equation Modeling (SEM) approach, using multiple hypothesized relationships across key dimensions, including economic, environmental, social, and infrastructural impacts are examined. The findings highlight the importance of socio-cultural factors in fostering support, while also recognizing the negative impact of environmental and infrastructural concerns. Socio-cultural impacts significantly and positively influenced support for sustainable tourism and destination initiatives, highlighting the role of cultural exchange, tradition preservation, and community identity in garnering local support. These findings align with previous studies, emphasizing the importance of perceived socio-cultural benefits in fostering community backing for tourism development. Effective STD management requires the active involvement of local stakeholders to ensure alignment with local values and environmental goals. Policymakers should focus on enhancing socio-cultural benefits, addressing infrastructural challenges, and effectively communicating economic advantages. Limitations of the study include its cross-sectional design, suggesting the need for longitudinal research to better understand the evolving impact of tourism.

View Full-Text DOI 10.5937/bnsr15-55046 Published: 06 Feb 2025

Open Access Original Scientific Paper

OPTIMIZATION OF TOKENIZATION AND MEMORY MANAGEMENT FOR PROCESSING LARGE TEXTUAL CORPORA IN MULTILINGUAL APPLICATIONS

by Dejan Dodić, Dušan Regodić, Nikola Milutinović

Optimization of tokenization and memory management in processing large datasets represents a key challenge in the contemporary development of language models. This paper focuses on enhancing the processing of large textual corpora in Serbian using the GPT-2 model, specifically adapted for transfer learning. Tokenization optimization was achieved by adding language-specific tokens for Serbian, while memory management was improved through advanced resource management methods during training. Key findings demonstrate significant memory consumption reduction and training process acceleration, enabling more efficient utilization of available computational resources. This research contributes to the development of language models tailored for the Serbian language and provides a foundation for further studies in the field of natural language processing (NLP). The implications of this work are multifaceted: it facilitates more efficient creation of NLP applications for Serbian-speaking regions, enhances the accuracy and performance of language models, and opens opportunities for applications across various domains, from automated translation to sentiment analysis. This study paves the way for future research focusing on additional optimization of language models, including adaptation for other languages with similar characteristics, as well as exploring new methods for even more efficient memory management during large-scale textual data processing.

View Full-Text DOI 10.5937/bnsr15-54993 Published: 06 Feb 2025