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Facile Microwave Production and Photocatalytic Activity of Bismuth Vanadate Nanoparticles over the Acid Orange 7
No full textThis work reports the rapid aqueous microwave-assisted synthesis of monoclinic scheelite BiVO4 nanoparticles and their behavior under visible light. X-ray diffraction (XRD) confirms phase-pure BiVO4 with an average crystallite size of ~19 nm, consistent with transmission electron microscopy (TEM) observations, while N2 sorption yields a BET surface area of 7.5 m2/g. UV–Vis diffuse reflectance spectroscopy (DRS) indicates a direct band gap of 2.55 eV. We evaluated the effects of catalyst dosage and initial Acid Orange 7 (AO7) concentration on visible-light degradation efficiency. Up to 77% removal was achieved within 120 min, with kinetics following a pseudo-first-order model (R2 ≈ 0.970–0.996). Under the tested conditions, BiVO4 also exhibited a modest antibacterial effect against Escherichia coli (~0.5 log reduction). These findings demonstrate that microwave-synthesized BiVO4 is a multifunctional material and provides a quantitative baseline for practical wastewater treatment studies under visible light
Surface engineering of titanium implants via anodization: Enhancing electrochemical stability and cellular response for long-term biocompatibility
No full textThe long-term success of titanium-based biomedical implants is strongly influenced by their surface properties, corrosion resistance, and biological compatibility. This study aims to systematically evaluate them effects of anodic oxidation on the electrochemical stability and biocompatibility of commercially pure titanium (cpTi, grade IV), with a focus on its application in dental and orthopedic implants. Anodization was performed in 1 M H2SO4 at a constant voltage of 15 V for 15 and 45 minutes to produce oxide layers of varying thickness and surface characteristics. Surface morphology and chemical composition were characterized using SEM coupled with EDS, while X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were utilized to elucidate and observe the phase transitions of the synthesized titanium oxides. The oxide layer thickness was estimated using a frequency-dependent capacitance method, revealing values of approximately 40 ± 15 nm and 90 ± 30 nm for 15- and 45-minute treatments, respectively. Corrosion performance was assessed in 9 g L-1 NaCl (pH 7.4), demonstrating superior corrosion stability of anodized samples compared to untreated cpTi. Cyclic polarization tests confirmed the absence of pitting corrosion, indicating that oxygen evolution was the predominant electrochemical process. Biocompatibility was evaluated by examining mitochondrial activity and gene expression in human gingival fibroblasts. The anodized surfaces, particularly those treated for 45 minutes (Ti-45), enhanced cellular adhesion and spreading. Both experimental groups, Ti-15 and Ti-45, showed a significant upregulation of N-cadherin and Vimentin. Additionally, the anodized surfaces exhibited improved hydrophilicity and elevated surface energy values, rising from 58.8 mJ m⁻² for untreated Ti to 65.1 mJ m-2 for Ti-45. The results highlight that anodic oxidation not only improves corrosion resistance but also enhances surface-driven cellular responses, supporting its potential use in optimizing implant integration and longevity in physiological environments
How polyaniline modifies corrosion pathways and enhances corrosion resistance of mild steel?
No full textMild steel's widespread use in industrial applications is hindered by its poor corrosion resistance, necessitating the application of protective coatings. While organic coatings are common, their long-term performance degrades due to blistering and delamination. To enhance protection, we developed composite coatings by incorporating 5 wt.% polyaniline (PANI) into commercial alkyd-based paint. PANI was synthesized in its emeraldine salt form, followed by deprotonation and reprotonation with various organic acids, resulting in materials with different doping levels and oxidation states that influenced their anticorrosive behavior. Corrosion performance was evaluated via in situ measurements of dissolved iron concentrations in 3% NaCl solution using the ASTM 1,10-phenanthroline method, and corrosion current density was recalculated. The protective performance of the coatings was found to strongly depend on the initial oxidation state and doping level of the PANI used, revealing that the best resistance was achieved with PANI doped with sulfamic acid (doping degree 0.27). These composite coatings significantly reduced corrosion, blister formation, and delamination compared to the base coating. The primary degradation mechanisms of organic coatings involve pore formation, leading to rust and blistering. Conducting polymers such as PANI mitigate these effects by altering the oxygen reduction reaction pathway. Highly doped PANI primarily reduces oxygen to hydrogen peroxide anions (HO₂⁻) rather than hydroxyl ions (OH⁻), significantly lowering local pH and the likelihood of blister or delamination formation. Furthermore, hydrogen peroxide can react with Fe²⁺ ions to form passive Fe₂O₃ films, further enhancing corrosion resistance. Additionally, these coatings exhibit self-healing properties, offering prolonged protection even after mechanical damage. Despite challenges in appearance due to PANI agglomeration, their exceptional corrosion protection makes them suitable as primer layers for robust steel structures in harsh environments, such as bridges and industrial equipment. Our findings suggest that polyaniline-doped composite coatings can provide two to three times longer corrosion protection in chloride environments compared to base coating. Future research endeavors ought to investigate strategies for mitigating the agglomeration of polyaniline (PANI) and further refining these coatings for expanded applications, thereby underscoring the promise of conducting polymers in the enhancement of corrosion protection technologies
Cavitation resistance of talc-reinforced pyrophyllite ceramics
No full textThe paper describes the effects of changing the properties of pyrophyllite ceramics reinforced with different proportions of talc (%): 10; 20; 30. Pyrophyllite powders with a grain size of 20 μm and talc powders with a grain size of 15 μm were homogenized, pressed and sintered at a temperature of 1200⁰C. The cavitation resistance of the sintered samples was determined by the ultrasonic vibration method with a stationary sample according to the ASTM G32 standard. The evolution of surface morphology and damage was examined by scanning electron microscopy (SEM). The aim of the research was to obtain a compact ceramic with improved properties of resistance to wear and cavitation. The quality of the sintered samples was evaluated according to the values of cavitation rates and the analysis of the surface damage
Optimization of the microemulsion sol-gel method for controlling the composition of mesoporous bioactive glass
No full textDue to their bioactive properties and ability to enable controlled release of therapeutic ions and bioactive substances, mesoporous bioactive SiO2-CaO glasses (MBG) represent one of the most promising biomaterials in regenerative medicine. MBGs with spherical particles and narrow size distribution are most commonly synthesized using the microemulsion sol-gel method, where the surfactant molecules play a key role in the development of the characteristic porous structure. In addition to calcium ions, which play a key role in their bioactivity, the incorporation of therapeutic ions such as Zn²⁺, Cu²⁺, Mg²⁺, and Sr²⁺ enhances angiogenic, osteogenic, and antibacterial properties of MBGs. However, previous studies have shown substantial discrepancies between the actual and nominal compositions, particularly regarding the calcium content. The aim of this study was to improve the standard microemulsion sol-gel method to incorporate the desired amount of ions into the silicate structure while maintaining the characteristic MBG morphology. Two modifications types were investigated: one involved maintaining a constant pH during the synthesis, while the second involved post-synthetic metal ion impregnation followed by two drying methods: conventional and lyophilization. As a control, MBG synthesized by the standard microemulsion sol-gel method was used. The characterization of the synthesized powders included a detailed analysis of the composition, morphology, and textural properties of the obtained particles. The results showed that in all cases, spherical particles with the characteristic porosity were formed. Maintaining a constant pH value led to an increase in particle size and a decrease in the specific surface area, as well as improved incorporation of Ca²⁺ ions, while the impact on the incorporation of other ions was minimal. The process modification, which resulted in smaller particles and a reduced specific surface area, showed significant improvements in achieving the desired composition. Additionally, it was shown that the drying method influenced the glass structure, with lyophilization preventing the formation of undesired crystalline phases
Optimization of solid-phase extraction for the determination of quaternary ammonium compounds in water by UHPLC–MS/MS
No full textQuaternary ammonium compounds (QACs) represent a significant group of surface-active
agents widely used in disinfectants and biocidal products. Their presence in surface waters and
wastewater raises concern due to their potential adverse environmental effects, emphasizing the need for sensitive and reliable analytical methods. The determination of QACs in water is challenging due to their high polarity, low concentrations in environmental samples, and tendency to adsorb onto surfaces during sample preparation. This study aims to optimize a solid-phase extraction procedure for the determination of twelve QACs, including benzylalkyldimethylammonium, alkyltrimethylammonium, and dialkyldimethylammonium compounds, using ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). A polymer-based sorbent was applied for analyte extraction, and optimization focused on eluent volume, solvent composition, and formic acid concentration. Acetonitrile provided the most consistent recoveries among the tested solvents. Recovery was strongly influenced by formic acid concentration and elution volume, with 2% formic acid in 15 mL of acetonitrile yielding the most satisfactory results (76–108%) for all twelve QACs. These results demonstrate the effectiveness of the developed SPE procedure combined with UHPLC–MS/MS analysis for QACs determination in aqueous samples, showing promise for future applications in environmental monitoring of QACs contamination
Polyurethane composites based on TiO2 nanoparticles: hydrophobicity and swelling behavior
No full textPolyurethane composites (PUCs) based on polycaprolactone (PCL),
isophorone diisocyanate (IPDI), Boltorn® hyperbranched polyester of
the second pseudo generation (BH-20) and unmodified or surfacemodified
TiO2 nanoparticles with lauryl gallate, were synthesized (Fig.
1). PUCs were prepared by incorporation of different amount (0.5, 1
and 2 wt.%) of unmodified or surface-modified TiO2 nanoparticles into
a polyurethane network (PU) [1,2]. The hydrophobicity and swelling
behavior of pure PU and PUCs were investigated.
Water contact angle (WCA) values of PUC samples, prepared with
unmodified and modified TiO2 nanoparticles are in the range from 84.4
to 97.9° and from 86.6 to 91.1°, respectively. From the results
presented in Fig.1 it can be observed that majority of the synthesized
PUCs have WCA lower than WCA of the neat PU (96.7°). Clearly, WCA
of examined samples depends on the chemical composition and
roughness of the investigated solid surface [1].
The pseudo-second-order kinetic model was applied to describe the
kinetics of swelling of the neat PU and prepared PUCs in three different
liquids (water, THF and toluene), and some of the results are shown in
Fig. 1. The diffusion mechanism of water through the neat PU and
PUC/Ti-0.5 fits the pseudo-Fickian model, while non-Fickian diffusion
mechanism describes diffusion of water through all other examined
PUCs. Results obtained by swelling measurements were also applied to
calculate diffusion coefficient (D) of water, THF and toluene through the prepared samples. The increase of D values for these solvents can
be attributed to the lower crosslinking density of PUCs compared to the
neat PU. The obtained D values are the highest for THF because the
swelling of samples was the largest in it, which resulted in the creation
of greater voids in samples through which THF can pass. The obtained
PUCs may potentially be used as protective coatings [1]
Biotech and non-thermal treatments to upgrade value of crop and herbal residues
No full textWith the growing trend for valorization of agri-food industry residues, by-products and wastes, in order to follow bioeconomy principles, novel approaches are being developed. Herbal dust, grounded fine powder which remains after processing of medicinal herbs for tea bags remains in huge amounts and depending on the herb, could be around 15% of total mass. This is a huge loss for industry and also significant wasting of resources if not used properly. It is either landfilled which poses a significant risk to generate gaseous emissions in uncontrolled conditions or it is used for composting. However, significant amount of phenolics in these residues could negatively affect soil microbiome. Similar is the case with residues remaining after harvesting of corn or wheat, like corn stalks which are high in lignocellulose and still often burned. Conventional strategies for fractionation have high environmental impact, involving acid/alkaline treatment and usually low recovery rate, favouring cellulose fraction.
Aim of our work was to study strategies to exploit herbal and crop residues, with higher recovery rate by means of combined biotech methods, e.g. fermentation, and non-thermal technologies. Extraction of phenolics from selected herbal residues was performed with green solvents, water and ethanol, in different
ratios. Depending on the extraction conditions, solvents were evaporated to remove ethanol as an antimicrobial solvent and reconstituted with water. This way obtained extracts were subjected to lactic acid fermentation with selected lactic
acid bacteria and antioxidant activity, microbial growth and chemical compositions were monitored. For corn stalks, predominantly lignocellulosic substrate, we studied role of cold plasma treatment on fractionation and characteristics of recovered lignin and cellulose. Cold plasma was combined with alkaline hydrogen peroxide treatment to estimate the possibility of treatment’s improvement in terms of delignification and further valorization of treated biomass (Grbić et al., 2024).
Fermentation of common nettle’s extract with L. salivarius has shown potential to increase the content of caffeic acid (73%), rutin (99%) and caffeic acid derivatives (65%) during 48h while also achieving a high number of viable cells (7,5 log CFU/ml). Since L. salivarius has a probiotic potential, this way extracts with increased bioactivity and fortified with potentially probiotic and GRAS microorganisms were obtained. This simple method can be adapted and exploited for different herbal residues, enabling recovery of phenolics and their upgrade toward more potent extracts. Lignocellulosic crop residues subjected to cold plasma in the alkaline environment were richer in cellulose content (69%) than the raw biomass (40%), with an overall recovery rate of 84%. The crystallinity index increased from 50% to 59% after applied treatment. SEM micrographs confirmed that cold plasma induced significantly higher porosity of treated residues than alkaline treatment solely. Increased porosity eventually led to enhanced enzymatic digestibility, resulting in an overall conversion rate of around 91%. This unlocks new possibilities for lignocellulosic biomass valorization towards platform chemicals production through fermentation processes. At the same time, the lignin fraction could be successfully separated and tested for potential high-value applications.
This study offers perspectives, highlighting low-energy methods for efficient agro-food waste management. Future research will focus on optimizing these valorization processes. Fermentation with probiotic bacteria cold plasma treatment
can be further optimized and integrated into industrial biomass processing for the production of high-value products such as postbiotic extracts, biofuels and platform chemicals. In additional future research will focus on process optimization, techno-economic and environmental impact to ensure the sustainable application of these innovative valorization strategies
Expanding the Structural Portfolio of Hydantoin Derivatives with Spiro Frameworks Bearing π-Functionalities
No full textThe hydantoin ring is a key structural feature in many pharmaceutically active compounds and blockbuster drugs, especially those targeting disorders of the central nervous system. In an effort to expand the molecular diversity of hydrophobic hydantoin derivatives, we synthesized a series of compounds in which the hydantoin ring is tethered to a tetralin unit in a spiro fashion, followed by the introduction of a 4-substituted benzyl group (X = H, Cl, NO2, or CN). These compounds exhibit not only a diversity in conformational flexibility but also sufficient variation in intermolecular interactions to rationalize the relationship between the molecular and crystal structures. This allowed us to evaluate effects of attaching the hydantoin ring to different positions of the tetralin ring system, as well as the number and substitution of the benzyl group on the molecular conformation and the crystal packing. The resulting crystal structures are dominated by hydrogen bonding motifs, forming either discrete (Formula presented) ring dimers or infinite chains. However, medium to weak interactions are decisive in constructing continuous supramolecular architectures. Even in the situation when there are no strong hydrogen bonds due to the introduction of an additional 4-chlorobenzyl group, these interactions lead to interesting assemblies. Advanced computational methods were employed to evaluate interaction energies, while molecular electrostatic potential (MEP) surfaces were used to elucidate the hierarchy and competition of hydrogen bonds involving different acceptor sites. These insights are valuable for understanding the design principles underlying supramolecular assemblies of potential pharmaceutical relevance
Uticaj strukture pređe na kompresiono ponašanje glatkih pletenina
No full textThe compression behaviour of textile fabrics is influenced by their structure,
fibre properties, and the compressibility and surface properties of yarn. Due to the limited
research on how yarn twist affects the compression properties of textile fabrics, this study
examined the influence of yarn twist on the compression behaviour of plain knitted fabrics.
Three plain knitted fabrics were produced from cotton yarns differing in twist intensity. The
knitted fabrics were subjected to successive compression-release cycles. The compression
release curves of plain knitted fabrics were analysed, allowing for the calculation of
specific compression parameters, including recoverable and irrecoverable compression.
Using these parameters, the non-elastic deformation components were calculated. The
results indicated that varying the yarn twists, which directly influence the packing density
and fibre mobility in yarns, as well as the fabric structure, allows for the adequate design
of the compression behaviour of plain knitted fabrics.Kompresiono ponašanje tekstilnih materijala uslovljeno je njihovom
strukturom, svojstvima vlakana, kao i kompresibilnošću i površinskim svojstvima pređe.
Usled ograničenog broja istraživanja uticaja upredenosti pređe na kompresiona svojstva
tekstilnih materijala, ovo istraživanje je posvećeno upravo ispitivanju efekata upredenosti
pređe na kompresiono ponašanje glatkih DL pletenina. U tu svrhu su od tri različito
upredene pamučne pređe proizvedene tri glatke pletenine koje su podvrgnute uzastopnim
kompresionim ciklusima. Analizirane su dobijene kompresione krive, i izračunati su
specifični parametri koji opisuju kompresiju pletenina. Koristeći ove parametre, izračunate
su neelastične komponente deformacije pletenina. Rezultati su pokazali da variranje
upredenostsi pređe, koje direktno utiče na gustinu pakovanja i pokretljivost vlakana u pređi, kao i na strukturu pletenine, omogućava adekvatno projektovanje kompresionih
svojstava glatkih DL pletenina