CONTEMPORARY MATERIALS

MXene-POLYURETHANE COMPOSITES AS WEARABLE STRAIN SENSORS FOR FINGER MOTION AND ON-SURFACE WRITING

Marija Pergal — 2026-04-29

The remarkable applications of flexible and wearable sensors in human motion detection and health monitoring have attracted considerable attention from both academic and industrial communities. Wearable strain sensors for finger-motion monitoring demand materials that combine high conductivity, flexibility, long-term durability, fast response, and stable interfaces. Here we report a MXene–polyurethane (PU) platform built on an MDI/HBP/PDMS network with 50 wt% soft segments (PU-50) that serves as a biocompatible, elastic substrate for a Ti₃C₂Tₓ conductive layer. MXene-PU composites were characterized by scanning electron microscopy (SEM), tensile testing and electrical measurements. SEM confirms the intended morphologies: layered, lamellar MXene stacks that form percolating pathways and a PU microphase-separated morphology between soft and hard segments. Three device variants were evaluated under finger flexion with increasing frequency: MXene on neat PU, PU with 1 wt% pure MXene in the bulk (PUMX), and PU with 1 wt% functionalized MXene (PEG-MXene) in the bulk (PUMP). Time-resolved resistance measurements acquired every 20 ms yielded clear, low-hysteresis ΔR/R₀ waveforms across all frequencies, with a consistent performance hierarchy in which PUMP exhibited the lowest baseline drift and the most stable cycle-to-cycle response, while the neat PU device displayed the largest resistance modulation amplitude. On-surface drawing tests on the neat-PU-MXene sensor further demonstrated pattern-robust sensitivity, producing distinct, repeatable temporal signatures for triangle, circle, and square trajectories with rapid baseline recovery and minor residual offsets. The obtained results validate MXene–PU as a fast, stable, and comfortable candidate for wearable finger motion sensors. They also identify mild interface optimization—via functionalized MXene in the substrate—as an effective way to enhance signal stability and suppress baseline drift while preserving signal fidelity across frequencies. This motivates future work on long-term stability, environmental compensation, and integration with compact wireless readout for multi-gesture recognition.
Keywords: MXene, polyurethanes, tensile testing, wearable sensors, finger-motion sensing.

CHROMATOGRAPHIC PARAMETERS IN THE ASSESSMENT OF LIPOPHILICITY AND TOXICITY OF THIOCARBOHYDRAZONE DERIVATIVES

Suzana Apostolov — 2026-04-29

In recent years, the number of studies focused on the design and synthesis of compounds with biological and pharmacological potential has increased significantly. Special attention has been given to molecules with antitumor activity, including thiosemicarbazones and their homologues, thiocarbohydrazones. Since drug development is a complex, lengthy, and expensive process, its optimization in early stages often relies on the application of Quantitative Structure–Activity Relationship (QSAR) approach. By selecting appropriate molecular descriptors, it is possible to quantify the impact of structural modifications on compound’s biological activity prior to synthesis, thus reducing the need for extensive experimental work. Lipophilicity as key QSAR descriptor, was determined for thiocarbohydrazones by using a hybrid approach – computationally, through appropriate software tools (logP as a standard measure of lipophilicity), and experimentally, by reversed-phase thin-layer chromatography (chromatographic parameters RM0 and m). The results indicated that the nature of the substituent had a greater effect on the chromatographic behavior of thiocarbohydrazones than the applied organic modifier. The correlation between chromatographically and computationally determined lipophilicity values, as well as the acute toxicity parameters (EC50), was assessed by linear regression analysis. The obtained models showed satisfactory predictive performance.
Keywords: thiocarbohydrazones, chromatography, lipophilicity, toxicity.

POTENTIAL OF RED MUD IN FENTON PROCESSES FOR THE DEGRADATION OF ORGANIC POLLUTANTS IN WATER - A MINI REVIEW

Nebojša Vasiljević — 2026-04-29

Fenton processes, in which hydrogen peroxide in the presence of divalent iron ions generates hydroxyl radicals (•OH), are widely used for the degradation of organic pollutants (phenols, antibiotics, dyes). In this review, red mud is analysed as a cheap source of iron ions in Fenton processes. Raw red mud can be used without additional modifications, but to increase the catalytic efficiency, its modification is required, which includes chemical reduction, carbothermal treatment or doping with metals. Particular attention is given to photo-Fenton and electro-Fenton processes, where red mud doped Cо, Sn or Cе, or in combination with reduced graphene oxide and biochar, allow the generation of not only hydroxyl radicals (•OH) but also singlet oxygen (1O2) and superoxide radicals (•O2–), achieving ≥99% pollutant removal. At the same time, the synthesised catalysts showed high stability and reusability. Based on a comparative analysis of more than 30 studies, it is concluded that red mud represents a cheap source of iron ions for heterogeneous Fenton processes, with significant potential for industrial application.
Keywords: Fenton process, hydroxyl radicals, organic pollutants, red mud.

APPLICATION OF DIRECTIVE (EU) 2020/2184 ON THE QUALITY OF WATER INTENDED FOR HUMAN CONSUMPTION

Draženko Bjelić — 2026-04-29

Drinking water is a vital resource for public health and sustainable development, yet its quality is increasingly threatened by pollution, climate change, and emerging contaminants. Directive (EU) 2020/2184 on the quality of water intended for human consumption introduces stricter requirements for monitoring, risk management, and public transparency. This paper analyzes the content and significance of the Directive, with a focus on the challenges of its implementation in Bosnia and Herzegovina.
Special attention is given to harmful substances such as bisphenol A, PFAS compounds, and cyanotoxins, which pose serious risks to human health. The Directive introduces new water quality parameters, promotes access to water as a human right, and encourages the use of tap water to reduce plastic waste.
In conclusion, aligning national legislation with this Directive is essential for improving water quality, protecting public health, and achieving sustainable development goals.
Keywords: drinking water, EU Directive 2020/2184, pollutants.

LASER-INDUCED GRAPHENE ON PDMS WITH GLYCOL COMPOUNDS AS A POTENTIAL WEARABLE SENSOR

Anđela Gavran — 2026-04-29

Laser-induced graphene (LIG) has been the subject of extensive research over the past decade and has found promising applications in physiological monitoring processes in both sports and medicine. Its excellent characteristics, such as good electrical conductivity, piezoresistivity, flexibility, and low-cost production, make it a suitable material for use in wearable electronics and sensors. Poly(dimethylsiloxane) (PDMS) has attracted attention as a substrate for wearable sensors due to its good biocompatibility, elasticity, and mechanical characteristics. However, since its structure contains no readily carbonizable atoms, PDMS must be modified with glycol additives such as diethylene glycol (PDMS/DEG) and ethylene glycol (PDMS/EG) to enable graphene induction. This paper presents the laser induction of graphene on a PDMS/DEG and PDMS/EG composite, electronic testing, and physicochemical characterization. By optimizing laser parameters, LIG with the lowest electrical resistance was obtained, with PDMS/DEG samples showing superior surface morphology compared to PDMS/EG. Raman spectroscopy revealed the characteristic D, G, and 2D bands typical for graphene. The assignment of bands in infrared spectroscopy (FTIR) and SEM micrographs confirmed the structure of graphene. Characterization revealed that the optimal glycol compound concentration in PDMS is 20 wt.%. In the future, this material has the potential to be used for measuring physiological processes and limb movements.
Keywords: laser-induced graphene, PDMS, sensors, diethylene glycol, ethylene glycol.

UTILIZATION AND RECOVERY ANALYSIS OF OAK LOGS IN A MODERN WOOD PROCESSING PLANT

Dane Marčeta — 2026-04-29

This paper analyzes the quantitative and qualitative recovery of pedunculate oak (Quercus robur) logs processed in the modern sawmilling facility of “Drvoprodex” d.o.o. in Srbac, Bosnia and Herzegovina. The research was conducted through a combination of direct measurements during two operational shifts, encompassing 185 logs and company-maintained production records. Logs were classified into three quality grades, with detailed analysis of dimensions and produced assortments, including lamellae (grades A–C), rustic-grade elements (R class), and friezes. The overall recovery from debarked log volume reached approximately 30%, aligning with the lower end of typical industry expectations for oak flooring production. Friezes dominated in quantity (2,376 pcs), particularly in 70 mm width, while lamellae and R-class elements showed optimal yields at 135 mm and 215 mm widths. Regression analysis confirmed a statistically significant positive influence of log diameter on both recovery rate and daily processing volume. While advanced equipment such as a band saw head rig, CNC optimizer, and multi-blade rip saws are employed, several older machines occasionally limit throughput, underscoring the need for further modernization. Importantly, about 70% of the log volume remains as sawmill residue, including slabs, edgings, sawdust, and bark. Recommendations are made for systematic valorization of these co-products: coarse residues can be chipped for biomass energy or panel manufacturing, while sawdust and bark can serve for pellet production or biochemical extraction (e.g. tannins). Enhancing residue utilization would increase material efficiency and economic sustainability, aligning the mill with circular economy principles and near-zero-waste production goals.
Keywords: oak sawmilling, log recovery, wood processing.

A COMPARATIVE HISTOLOGICAL STUDY OF CALCIUM-SILICATE CEMENTS FOR DIRECT PULP CAPPING IN WISTAR RATS

Ognjenka Janković — 2026-04-29

Maintaining pulp vitality is essential for the long-term health of teeth. Direct pulp capping aims to stimulate reparative dentin formation and prevent pulp necrosis. This study aimed to evaluate the effects of novel calcium silicate–based materials on the pulpal inflammatory response and dentin bridge formation using a Wistar rat model.
A total of 18 Wistar rats (72 maxillary molars: 36 first and 36 second) were included and divided into two groups (A and B; n = 9). In Group A, Theracal LC was applied to the exposed pulp of the right maxillary molars, while MTA was applied to the left molars. In Group B, Calxyl was applied to the right molars, and Biodentine and MTA were applied to the first and second left molars, respectively. The Wilcoxon signed-rank test was used for statistical analysis.
After 30 days, the lowest pulpal inflammatory response was observed with Theracal LC, followed by Biodentine, which showed a comparable level of inflammation but with slightly more polymorphonuclear leukocytes. The highest inflammatory response was recorded with Calxyl. A statistically significant difference in inflammation levels was found between Theracal/Calxyl (p = 0.041), Theracal/MTA (p = 0.034), Biodentine/Calxyl (p = 0.044), and Biodentine/MTA (p = 0.039). All tested materials demonstrated a strong capacity to induce dentin bridge formation.
In conclusion, the new calcium silicate–based materials exhibited favorable biological properties, with Theracal LC and Biodentine showing the lowest inflammatory response. All materials promoted reparative dentinogenesis, confirming their potential for use in direct pulp capping procedures.
Keywords: pulp capping, Theracal LC, Biodentine.

A STUDY ON THE ZETA POTENTIAL OF GOETHITE, QUARTZ AND CLAY MINERALS DEPENDING ON pH AND THE PRESENCE OF INORGANIC DISPERSANTS

Ljiljana Tankosić — 2026-04-29

The knowledge of zeta potential is a very useful indicator of the stability of dispersed systems. This is especially important in many industrial processes, such as e.g. mineral processing, purification of water and many others. This article deals with the investigation of the electrokinetic behavior of goethite, quartz and clay minerals depending on pH and the presence of inorganic dispersants: sodiumhexamethaphosphate (SHMP), sodiumpyrophosphate (SPP) and sodium silicate (SS). All studies are conducted on natural samples, taken from Omarska iron mine (Bosnia and Herzegovina) by measuring the zeta potential. From the experimental results, it was found that the increase of the suspension pH resulted in an increase in the negative charge of all three tested samples. The clay did not show any isoelectric point (IEP). Quartz showed isoelectric points at pH about 2.6 and close to 2 in the absence and presence of sodium silicate in suspensions, respectively. Goethite showed isoelectric points at pH 6.7 and 4.95 in the absence and presence of sodium silicate in suspensions, respectively. An IEP could not be detected when the SHMP and SPP were used and the surface charge is negative from pH 2 to pH 12 in all tested samples. The addition of SHMP provided the highest negative zeta potential, i.e. the most stable dispersion, in all three tested samples.
Keywords: zeta potential, isoelectric point, goethite, quartz, clay, inorganic dispersants.

EFFECTS OF SOFT SEGMENT CONTENT AND LASER-INDUCED GRAPHENE ON THE SURFACE AND THERMAL PROPERTIES OF CROSS-LINKED POLYURTEHANES

Vanja Vojnović — 2026-04-29

The versatile chemistry of polyurethanes (PUs) makes them suitable for a wide range of applications. In particular, surface topography and thermal behavior can be effectively tailored by adjusting the soft segment content (SSC) within the PU structure. However, as an intrinsically nonconductive class of polymers, PUs are not suitable for electronic applications. With the increasing interest in polymer/graphene heterostructures, the formation of graphene conductive pathways on polymer surfaces has emerged as a promising approach to overcome this limitation. In this study, we systematically examined the effects of varying SSC (expressed in wt.%) in synthesized cross-linked PUs, as well as the influence of laser-induced graphene (LIG) transferred onto the PU surface on several key properties: surface roughness via atomic force microscopy (AFM), surface wettability using water contact angle (WCA) measurements, and thermal properties through differential scanning calorimetry (DSC). An increase in SSC led to a reduction in surface roughness and a concomitant increase in WCA, indicating enhanced hydrophobicity. The presence of LIG further augmented the hydrophobic character of the surface. The PU structure exhibited a pronounced effect on both glass transition (Tg) and melting temperatures (Tm), while LIG had a minimal impact on thermal properties. This research provides a framework for engineering the surface and thermal properties of PU-based materials for applications in flexible electronics and smart coatings.
Keywords: polymers, composites, structure-property relationship, AFM, WCA, DSC.

THE INFLUENCE OF ORAL HYGIENE AND DIETARY HABITS ON THE SUCCESS OF THE BLEACHING OF ENDODONTICALLY TREATED TEETH

Nataša Knežević — 2026-04-29

Introduction: In the tooth bleaching process, the primary focus is often placed on selecting an adequate bleaching technique and optimal agent concentration, while the significance of daily oral hygiene during and after the bleaching treatment is frequently underestimated. The quality of oral hygiene, along with the dietary habits of patients, plays a significant role in the success and long-term stability of the achieved tooth color. This study aimed to investigate the influence of oral hygiene, smoking, and the consumption of colored beverages on the success of bleaching endodontically treated teeth.
Materials and methods: The study included 30 endodontically treated teeth. In the first group, teeth were bleached using the walking bleach technique (10 teeth); in the second group, the in-office technique was used (10 teeth); and in the third group, teeth were bleached with a combined technique (10 teeth). Bleaching was performed using 30% carbamide peroxide and 35% hydrogen peroxide. All teeth were restored with the nanohybrid composite material Tetric EvoCeram (Ivoclar, Liechtenstein). Based on oral hygiene and dietary habits, patients were classified as having good/moderate/poor oral hygiene, as smokers/non-smokers, and as consumers/non-consumers of colored beverages. Before and after the bleaching treatment, the color of all teeth was determined using the Vita Classic shade guide. For statistical analysis, bleached teeth were analyzed based on the scale from the study by Ari et al.
Results: Based on Fisher’s exact test results, a statistically significant difference (p<0.05) in bleaching success was established among teeth with good, moderate, and poor oral hygiene. However, no statistically significant difference was found between smokers and non-smokers, or between consumers and non-consumers of colored beverages.
Conclusion: The effectiveness of non-vital tooth bleaching is affected by the oral hygiene of the patients. However, smoking and colored beverage consumption had no impact on the success of the bleaching process.
Keywords: carbamide peroxide, hydrogen peroxide, oral hygiene, smoking, colored beverages, nanohybrid composite

UNLOCKING THE FUNCTIONAL POTENTIAL OF BIS(PHENYLHYDRAZONES): SYNTHESIS AND STRUCTURAL ELUCIDATION OF THE FIRST FE(II) COMPLEX WITH A 2,6-DIACETYLPYRIDINE-BASED LIGAND

Mirjana Radanović — 2026-04-29

The reaction of a warm methanolic solution of iron(II)-bromide and an acetone solution of 2,6-diacetylpyridine-bis(phenylhydrazone) (L) gave dark red prismatic single crystals of the complex [FeL2]Br2. The composition and purity were elucidated via elemental analysis, and the coordination mode was determined based on FTIR spectra. The latter was confirmed by X-ray structural analysis. This complex is isostructural with previously synthesized complexes [CuL2]Br2 and [CoL2]I2 – all three complexes crystallize in the C2/c space group and have very similar unit cell parameters. [FeL2]2+ lies on a two-fold rotation axis; thus, the asymmetric unit consists of one ligand molecule, a half of the Fe(II) ion, and one bromide ion. Fe(II) is situated in a very distorted octahedral environment formed by six nitrogen atoms of two ligand molecules, with trans-angles having the values of 146.81° and 173.43°. Due to steric factors, the phenyl rings of the ligand are twisted, which can be seen from the torsion angles of 141.42° for one and 155.27° for the other phenylhydrazone moiety. Besides, the complex is characterized by coupled TG-MS measurements.
Keywords: metal complexes, hydrazones, synthesis, characterization.

ANALYSIS OF THE EFFICIENCY OF THE FLUE GAS DESULFURIZATION PROCESS AT THE UGLJEVIK MINE AND THERMAL POWER PLANT

Jelena Dabić — 2026-04-29

The flue gases from coal fired thermal power plants, contain combustion gases (SO₂, NOₓ, CO, CO₂) and fine particles of fly ash. The concentration of sulfur oxides in the flue gas depends on the sulfur content in the coal. The flue gas desulfurization (FGD) process at TPP Ugljevik utilizes a wet scrubbing method, where a limestone suspension serves as the absorbent medium for sulfur oxides, with gypsum as a byproduct. Comparative analysis of emission levels before and after the FGD system installation indicates that the applied desulfurization technology is highly effective. The efficiency of the desulfurization plant ranged from 83.91% to 100%, depending on the inlet concentration of SO₂ in the flue gas. Estimates show that the FGD plant, depending on the intensity of operation, can annually remove between 7,000 and 55,800 tons of sulfur, with by-product gypsum production ranging from 3,660 to 29,280 tons. The implementation of this flue gas purification process significantly reduces the impact on the environment and ambient air pollution caused by sulfur oxides. For economic reasons, the plant is unfortunately unable to operate continuously.
Keywords: Flue gases, SO₂ emissions, desulfurization, wet scrubbing process.