Search Results (120)

Drinking-water treatment systems must effectively control natural organic matter (NOM), a major precursor of regulated disinfection by-products (DBPs). Specific ultraviolet absorbance (SUVA) is widely used as an operational surrogate for NOM aromaticity and hydrophobicity; however, ozonation and subsequent filtration can disrupt the linear relationship between SUVA and trihalomethane formation potential (THMFP). This study evaluates whether SUVA can reliably predict THMFP under two ozonation configurations frequently applied in drinking-water treatment: pre-ozonation prior to coagulation–filtration and final ozonation following filtration. Experimental data were analyzed using conventional linear regression and artificial neural network (ANN) models, with SUVA employed as the sole predictor variable. Across all treatment configurations, reductions in SUVA were consistently more pronounced than corresponding decreases in THMFP, indicating a decoupling between chromophoric loss and chlorine-reactive precursor dynamics under ozonation-dominated conditions. Linear regression models exhibited only moderate predictive performance (R² = 0.63–0.76), reflecting the limitations of proportional surrogate-based approaches when NOM undergoes oxidative and adsorptive transformation. In contrast, single-parameter ANN models captured the nonlinear SUVA–THMFP relationship with substantially higher accuracy across both pre- and final-ozonation regimes (R² = 0.88–0.99), successfully resolving process-dependent patterns embedded within optically compressed SUVA signals. These findings demonstrate that, although SUVA alone cannot linearly represent the multistep transformation of NOM during ozonation and adsorption, it retains process-relevant structure information on DBP precursor reactivity that can be effectively extracted using nonlinear modelling. The results highlight the potential of integrating ANN-driven tools into advanced monitoring and DBP-control strategies in modern drinking-water treatment systems. Full article

Background/Objectives: Candida biofilms exhibit high resistance to antifungal treatment, motivating investigation of adjunctive physical disinfection methods. To quantitatively assess the effect of Er:YAG laser fluence on growth inhibition and viability of single-species Candida biofilms in vitro using a 7 mm full-beam handpiece. Methods: Biofilms of Candida albicans ATCC 10231, C. glabrata ATCC 90030, C. parapsilosis ATCC 22019, and C. krusei ATCC 6258 were grown on Sabouraud agar. In phase 1, growth inhibition zones (GIZs) were evaluated after non-contact Er:YAG irradiation (2 Hz, 300 µs, 10 mm distance, no air or water spray) at fluences from 0.3 to 3.4 J/cm², with incubation for 24 to 96 h. In phase 2, 96 h mature biofilms were irradiated for 120 s at 0.8, 1.0, 1.5, or 2.0 J/cm², and viability was quantified by colony-forming unit (CFU) imprinting. All experimental conditions were tested in quadruplicate. Results: GIZ diameters increased significantly with fluence for all species (p < 0.05) and remained stable up to 96 h. At the highest fluence, mean GIZs reached approximately 8.0 mm for C. albicans, 7.7 mm for C. parapsilosis, 7.0 mm for C. krusei, and 5.2 mm for C. glaxfbrata. In mature biofilms, CFU counts decreased significantly with increasing fluence (p < 0.05). For C. albicans, CFUs were reduced from 164.0 ± 25.1 at 0.8 J/cm² to 16.5 ± 5.2 at 2.0 J/cm², while C. glabrata decreased from 103.5 ± 5.4 to 20.8 ± 1.7. C. parapsilosis and C. krusei showed maximal reductions at 1.0–1.5 J/cm², followed by partial CFU rebound at 2.0 J/cm². Conclusions: Er:YAG irradiation delivered over a large, uniformly illuminated area induces stable, fluence-dependent inhibition and significant reduction of Candida biofilm viability in vitro. Optimal fluence ranges are species specific, underscoring the need for parameter optimization and further evaluation in more complex biofilm models before clinical extrapolation. Full article

The study focused on essential oils (EOs) of plant origin, which are of great interest to scientists in the context of medical applications due to their biological properties, such as antimicrobial, anti-inflammatory, antioxidant, and anticancer effects. The objective of the study was to determine chemical profiles and biological activities of the essential oils extracted from five mixtures (M1 [Thymus vulgaris, Ammi visnaga, Syzygium aromaticum, Citrus sinensis]; M2 [Thymus vulgaris, Ammi visnaga, Cinnamomum verum, Citrus sinensis]; M3 [Mentha pulegium, Lavandula angustifolia, Zingiber officinale, Citrus sinensis]; M4 [Mentha pulegium, Lavandula angustifolia, Cinnamomum verum, Citrus sinensis]; M5 [Ammi visnaga, Lavandula angustifolia, Zingiber officinale, Syzygium aromaticum]). Each mixture was derived from a blend of four selected plants used in traditional medicine in Mostaganem, Algeria. When selecting the best composition, the interactions between plant components were considered in terms of potential therapeutic benefits. The chemical compositions of the EO mixtures were analyzed using GC-MS. The acute toxicity of the EO mixtures was evaluated in vivo following oral administration. The sensitivity of the microorganisms to the EO mixtures was determined using the agar diffusion method. Virucidal testing was performed using the quantitative suspension method to determine virucidal activity, as described in the European standard for disinfectants used in the medical field. The antioxidant activity of the EO mixtures was evaluated using a model membrane system based on liposomes derived from soybean phosphatidylcholine. Chemopreventive activity was assessed in vitro using cell culture. The main compounds identified were carvacrol and thymol in M1; geranial, cinnamylaldehyde, and carvacrol in M2; pulegone and limonene in M3; geranial and cinnamylaldehyde and limonene in M4; and eugenol and caryophyllene in M5. The selection of the “best” blend depended on the biological activity deemed most critical for the specific application. Specifically, M3, M4, and M5 exhibited the strongest anti-HSV-1, anti-HAdV-5, and anticancer activity, respectively. In contrast, M1, a potent antioxidant, demonstrated the strongest antibacterial and anticancer activity. These results indicate that M1, M3, M4, and M5 EOs have promising applications in the pharmaceutical industry and medical research. Full article

Background: The cysts of the protozoan parasite Giardia duodenalis, which targets a broad spectrum of hosts including humans, can withstand environmental conditions for months, making effective disinfectant measures crucial for minimizing the infection burden. Previous investigations concerning disinfection efficacy were based on cysts from fecal/water samples or animal models, which are either unfit for standardized procedures or related to ethical concerns. Methods: To perform standardized in vitro disinfectant testing, four different encystation protocols were compared firstly. The protocol with the highest efficacy in our hands (1.7 × 10⁵ cysts per tube) was used for the production of cysts to establish a disinfectant assay. Therefore, it was used for the production of cysts to establish a dis-infectant efficacy assay. After incubation with a commercial disinfectant (ViPiBaX Giardien Ex^®) or 30% hydrogen peroxide solution (H₂O₂) at 10 °C and room temperature, parasite cyst viability was evaluated by the yield of trophozoites obtained by the applied excystation protocol. Results: Only untreated Giardia cysts, which were used as a negative con-trol, released trophozoites. The protocol established for the evaluation of cyst viability delivered reproducible results and appeared suitable for testing the inactivation of cysts by chemical disinfection. Conclusions: Under the given conditions, the disinfectant ViPiBaX Giardien Ex^® and H₂O₂ inactivated Giardia cysts. Full article

The aim of the study was to investigate the effect of disinfection with penicillin and/or streptomycin, added to ethanol mist, on the surface properties of both model and historical leather materials from the collections of the Auschwitz-Birkenau State Museum (A-BSM) in Oświęcim, Poland. The experimental conditions involved application of 90% ethanol mist alone or with penicillin, streptomycin or a mixture of both antibiotics using an airbrush. Changes in the morphology, structure and chemical properties of the sample surfaces compared to non-exposed samples were evaluated using Scanning Electron Microscopy (SEM), confocal microscopy (CM) and X-ray Photoelectron Spectroscopy (XPS). Microscopic studies demonstrated that exposure to penicillin or the antibiotic mixture caused subtle smoothing and flattening of tested leathers and a significant reduction in contamination of biological and mineral origin. Decreases in fluorescence intensity and fluorescent layer thickness were also observed, which, according to the XPS results, may be caused by the removal of a large amount of surface deposits or the reveal of deeper leather layers that were previously covered with inorganic particles. Therefore, it can be concluded that the developed method of applying antibiotics in ethanol mist does not have any significant negative effect on the surface of model and historical leather. Full article

Chlorinated benzoquinones, such as 2,6-dichlorobenzoquinone (DCBQ), are toxic disinfection byproducts of growing concern in aquatic environments. Advanced oxidation processes, particularly photo-Fenton treatment, provide sustainable alternatives for their degradation. However, optimization is required to ensure not only the removal of the parent compound but also the reduction in harmful intermediates. This study evaluated the degradation of DCBQ (1.0 mM H₂O₂, 150 W UV, pH 3.0, 25 °C) with ferrous ion between 0 and 1.0 mg/L. DCBQ removal followed a second-order kinetic model, reaching complete degradation. Aromaticity-loss and water color degradation adjusted to kinetics of second-order, reflecting the sequential reduction in chlorinated hydroquinones and chlorophenols type intermediates, with marked decreases after 120 min at 0.8 mg/L. Results showed that increasing iron dosage enhanced both the rate of DCBQ disappearance and the removal of aromaticity, with complete pollutant degradation. Importantly, optimal ferrous ion dosages (20 mol DCBQ: 70 mol H₂O₂: 1 mol Fe²⁺) effectively limited the persistence of intermediates, as evidenced by significant decreases in color and aromaticity, while avoiding excessive turbidity. These findings demonstrate that fine-tuning iron dosage in photo-Fenton systems can maximize contaminant elimination and minimize secondary byproducts, reinforcing their role as sustainable solutions for wastewater remediation. Full article

The increasing global incidence of infections caused by free-living amoebae (FLA) and the lack of effective, safe, and approved treatments highlight the urgent need for novel amoebicidal compounds with pharmacological potential. Despite a growing body of literature on the anti-FLA properties of various compounds, comprehensive reviews summarizing this progress remain scarce. This study aimed to identify the most promising compounds tested in vitro and/or in vivo for anti-FLA activity. A systematic review was conducted, analyzing 108 studies published between 1986 and 2024, selected from an initial pool of 23,653 database results. A total of 537 compounds were evaluated for their in vitro anti-FLA activity. Compounds exhibiting ≥50% reduction in amoeba viability relative to untreated controls were classified as promising if they showed low toxicity in mammalian cell models, particularly when active at concentrations ≤ 10 µM, consistent with predicted favorable pharmacokinetic and pharmacodynamic profiles. The most promising compounds for drug and disinfectant development include ten trophocidal agents against B. mandrillaris, thirty-two trophocidal and four cysticidal agents against N. fowleri, and sixty-two trophocidal and nineteen cysticidal agents against Acanthamoeba spp. Compounds active at low concentrations (≤10 µM or <0.014 mg/mL) prioritized for in vivo drug development studies include: against Balamuthia mandrillaris, trophocidal 515, 531, 533; against Naegleria fowleri, trophocidal 421, 416, 518, 46, 254, 522, 111–120 and cysticidal 16; and against Acanthamoeba spp., trophocidal 498, 499, 500, 535, 107, 347, 348, and 340. Future studies should evaluate their efficacy, safety, pharmacokinetics, and pharmacodynamics toward developing effective drugs, antiseptics, and disinfectants. Full article

Effect-based toxicity assessments are crucial for evaluating the risks of disinfection byproducts (DBPs), particularly unknown species, generated during drinking water chlorination. However, the accuracy of this approach is highly dependent on unbiased sample extraction. Conventional methods often employ single, low-pH extraction, which may fail to recover pH-sensitive amphoteric DBPs derived from amphoteric precursors (e.g., nitrogenous compounds). This study investigated how extraction pH affects the measured biotoxicity of DBPs formed from three model precursors: biopterin (Bip), cytosine (Cyt), and tryptophan (Trp). Under excess chlorine conditions, all three precursors degraded rapidly. The formation of aliphatic DBPs followed the order Trp > Cyt > Bip, and the maximum toxicity of the non-volatile extracts, assessed via a Vibrio fischeri bioassay, followed the reverse order: Bip > Trp > Cyt. This toxicity profile was significantly influenced by extraction pH, with maximum toxicity observed for Bip at around pH 4.0, under weakly acidic conditions for Trp, and under neutral to alkaline conditions for Cyt. For all precursors, the total organic carbon concentration remained constant throughout chlorination, indicating negligible mineralization and the predominant formation of non-aliphatic, likely heteroaromatic, products. These findings demonstrate that conventional extractions at a single low pH can lead to the incomplete recovery of toxic DBPs from amphoteric precursors. Therefore, pH-optimized extraction protocols are necessary for a more accurate risk assessment of chlorinated drinking water. Full article

Persistent Enterococcus faecalis infections represent a major cause of endodontic treatment failure, highlighting the need for innovative disinfection strategies beyond conventional irrigation. This in vitro study evaluated the antimicrobial potential of pulsed electric fields (PEF) as a non-thermal and non-chemical adjunctive method for root canal disinfection. Fifty-two extracted mandibular premolars with single canals were standardized to 16 ± 0.1 mm, inoculated with E. faecalis, and incubated for 28 days to establish mature biofilms. The teeth were subsequently exposed to PEF under varying electrical parameters using sterile water as the irrigant, and bacterial viability and metabolic activity were assessed post-treatment. Confocal laser scanning microscopy (CLSM) was performed to visualize bacterial distribution within dentinal tubules, with particular attention to the apical region, which is most resistant to disinfection. PEF application significantly reduced bacterial viability and metabolic activity compared with baseline (p < 0.05), although complete elimination was not achieved. CLSM images revealed both red-stained non-viable cells, reflecting irreversible electroporation, and green-stained viable cells, indicating reversible electroporation and residual bacterial survival. These findings demonstrate that PEF can inactivate microorganisms through electroporation while maintaining tissue compatibility, and its antimicrobial effect may be enhanced when combined with sodium hypochlorite. Optimization of electrical parameters and evaluation in polymicrobial biofilm models are warranted to establish clinical relevance and support translation into practice. Full article

Halogenated disinfection by-products such as 2,6-dichlorobenzoquinone (DCBQ) are emerging microcontaminants of concern due to their persistence and toxicity in aquatic environments. This study evaluated the oxidative degradation of DCBQ under UV irradiation, focusing on the effect of H₂O₂ dosage on removal efficiency and water quality. Batch experiments were conducted with H₂O₂ concentrations ranging from 0.0 to 10.0 mM. Kinetic analysis revealed that photolysis with UV alone followed an apparent order of 1.5, while the UV/H₂O₂ system showed an order of 2.5, reflecting the contribution of hydroxyl radicals and their dependence on both DCBQ and H₂O₂ concentrations. Color evolution displayed a series reaction behavior: the initial formation of chromophoric by-products followed first-order kinetics, whereas their subsequent removal proceeded with zero-order kinetics, consistent with radical-driven decolorization. Optimal performance was achieved with 1.0–2.0 mM H₂O₂, which promoted rapid DCBQ decay and significant reductions in aromaticity and color (100% in 2 h), whereas higher concentrations (10.0 mM) led to radical scavenging and lower efficiency. Dissolved oxygen increased during treatment, confirming oxidative pathways, while turbidity remained stable between 1 and NTU. These results demonstrate the effectiveness of UV/H₂O₂ for DCBQ removal and highlight the value of kinetic modeling in optimizing advanced oxidation processes for water treatment. Full article

The emergence of Candida auris as a disheartening fungal pathogen in healthcare settings has prompted urgent re-evaluation of containment and mitigation strategies. This review critically examines the biological persistence, environmental adaptability, and resistance to standard antifungal therapies of the pathogen, particularly regions with limited surveillance infrastructure. Based on regional experiences, such as those in Saudi Arabia and the Middle East in general, the study reveals systemic weaknesses in diagnosis, reporting, and environmental sanitation. Special consideration is paid to the combination of new disinfection technologies, including ultraviolet irradiation systems and hydrogen peroxide vaporisation, with institutional behaviour change strategies. This discussion shows the importance of synchronising technological development with frequent employee contributions and cross-functional planning. It also encourages the international standardisation of diagnostic platforms and the launch of real-time genomic surveillance to reveal evolutionary trends. Finally, the findings justify the shift towards proactive models of infection control that are founded on the resilience of systems and the agility of institutions. This paper is a synthesis of epidemiological patterns, decontamination strategies and behavioural knowledge to contribute to an emerging body of knowledge that can help to fortify healthcare settings against current fungal threats. Full article

Foodborne illness outbreaks from fresh produce underscore the urgent demand for sanitizing strategies that ensure safety while minimizing harmful by-products from high-dose chemical disinfectants such as sodium hypochlorite (NaOCl). Low-concentration combinations of organic acids and washing sanitizers were systematically evaluated to identify synergistic antibacterial effects, and citric acid (CA) was found to markedly potentiate the activity of NaOCl against Salmonella Typhimurium through a sequential assault on the cell envelope. A low-dose combination of sub-inhibitory concentrations (1/2 MIC of CA and 1/4 MIC of NaOCl) exhibited robust synergy, achieving a >6 log CFU/cm² reduction in the pathogen on a cherry tomato model within 3 min. Moreover, this synergistic entry leads to profound disruption of membrane integrity, resulting in leakage of nucleic acids and proteins, extensive oxidative damage, hyperpolarization, and cell lysis, as confirmed by electron and confocal microscopy together with physicochemical assays. Mechanistic investigation revealed that oxidative damage from NaOCl amplified CA-induced membrane acidification and permeability, facilitating deeper sanitizer penetration and accelerating envelope destruction. Collectively, these findings uncover a membrane-targeted synergistic mechanism, providing a solid scientific basis for the development of novel, low-residue, and high-efficacy food safety interventions. Full article

This study comprehensively evaluated the antimicrobial performance of copper ions against three bacterial species relevant to water systems: E. coli (ATCC 25922), P. aeruginosa (ATCC 27853), and S. epidermidis (ATCC 12228). Disinfection kinetics were determined at three copper concentrations (0.5, 1.5, and 3.3 mg/L) using the Gard model. E. coli exhibited the highest susceptibility, with inactivation rate constants of 0.63, 3.27, and 9.83, achieving complete inactivation at 3.3 mg/L. P. aeruginosa was the most resistant, showing values below 1.0 across all concentrations, while S. epidermidis displayed intermediate responses. Selected experiments further examined the influence of growth phase, temperature, and water chemistry. Exponential-phase cells were more sensitive than stationary-phase cultures, and higher temperatures (37 °C vs. 5 °C) significantly enhanced inactivation. Moderate bicarbonate (50 mg/L) improved bacterial removal by stabilizing soluble Cu²⁺ ions (2.60 lg reduction), whereas elevated calcium and magnesium (Ca²⁺ 100 mg/L, Mg²⁺ 50 mg/L) reduced effectiveness (≤2.10 lg reduction) through competitive interactions. In addition to culture-based methods, adenosine triphosphate (ATP) bioluminescence assays and flow cytometry (FCM) provided complementary insights, confirming early metabolic disruption and membrane damage prior to culturability loss in selected experiments. Full article

Povidone-iodine (PVP-I), a widely used aquaculture disinfectant, remains poorly understood in terms of sublethal toxicity and damage reversibility. This study employed Macrobrachium rosenbergii as the model organism to evaluate the acute toxicity and sublethal effects of PVP-I through a 4-day exposure experiment followed by a 7-day depuration period. Acute toxicity tests enabled the determination of 24–96 h median lethal concentrations (LC₅₀), with the 96 h LC₅₀ being 5.67 mg/L and the safe concentration (SC) being 1.37 mg/L. Based on this, three sublethal concentrations (1.14, 1.89, and 2.84 mg/L) were tested over a 4-day exposure followed by a 7-day depuration period. Investigated endpoints included gill ultrastructure, apoptosis, and antioxidant and immune-related gene expression. Subacute exposure at 1.89 and 2.84 mg/L induced mitochondrial vacuolization, upregulated apoptosis-related genes (Cyt-c, Caspase-3, Bok), and downregulated antioxidant gene expression (SOD, CAT, GSH-Px). The high-concentration group also showed sustained Toll-like receptor (Toll) gene overexpression and acid phosphatase (ACP) gene suppression. After depuration, antioxidant gene expression normalized; however, apoptotic markers in gill tissue remained impaired. Overall, high PVP-I concentrations cause irreversible gill damage via mitochondrial-mediated apoptosis, whereas lower concentrations (≤1.14 mg/L) allow for greater recovery. These results offer crucial toxicodynamic insights for safer PVP-I use and risk assessment in M. rosenbergii aquaculture. Full article

Background: Separated endodontic instruments are a significant complication in root canal treatment, affecting disinfection and long-term prognosis. Their detection on panoramic radiographs is challenging, particularly in complex anatomy or for less experienced clinicians. Objectives: This study aimed to develop and evaluate a deep learning model using the U²-Net architecture for automated detection and segmentation of separated instruments in panoramic radiographs from multiple imaging systems. Methods: A total of 36,800 panoramic radiographs were retrospectively reviewed, and 191 met strict inclusion criteria. Separated instruments were manually segmented using the Computer Vision Annotation Tool. The U²-Net model was trained and evaluated using standard performance metrics: Dice coefficient, IoU, precision, recall, and F1 score. Results: The model achieved a Dice coefficient of 0.849 (95% CI: 0.840–0.857) and IoU of 0.790 (95% CI: 0.781–0.799). Precision was 0.877 (95% CI: 0.869–0.884), recall was 0.847 (95% CI: 0.839–0.855), and the F1-score was 0.861 (95% CI: 0.853–0.869). Conclusions: These results demonstrate a strong overlap between predictions and ground truth, indicating high segmentation accuracy. The U²-Net model showed robust performance across radiographs from various systems, suggesting its clinical utility in aiding detection and treatment planning. Further multicenter studies are recommended to confirm generalizability. Full article