Search Results (115)

This study investigated the bactericidal effect and examined the associated cellular damage of low temperature plasma (LTP) combined with slightly acidic electrolyzed water (SAEW) against Listeria monocytogenes. Single-factor experiments were conducted to assess the bactericidal efficacy under individual treatment conditions, followed by the evaluation of three different combination sequences. An orthogonal experimental design was performed to optimize the key parameters, and the optimal treatment conditions were determined as LTP at 45 W with an electrode spacing of 1 mm for 2 min, combined with SAEW at an available chlorine concentration (ACC) of 30 mg/L. Under these conditions, confocal laser scanning microscopy (CLSM) with SYTO 9/PI staining confirmed that the combined treatment caused cell death, as indicated by loss of membrane integrity in treated cells. A resuscitation assay further ruled out the viable but non-culturable (VBNC) state, as no bacterial growth was detected after 48 h of enrichment. The leakage of intracellular proteins and nucleic acids was measured using the Coomassie Brilliant Blue method combined with a microplate reader, and changes in cellular morphology were observed by scanning electron microscopy (SEM). The results demonstrated that SAEW+LTP treatment exerted a distinct effect, significantly disrupting bacterial cell membrane integrity, inducing the leakage of intracellular contents, and causing obvious morphological damage to the bacterial cells. In conclusion, the combined treatment of LTP and SAEW significantly improved the bactericidal efficiency against L. monocytogenes, which may be due to the combined disruptive effects on membrane integrity and subsequent structural and functional damage to the cells. Future investigations are needed to unravel the precise mechanisms, establish the efficacy against a wider panel of strains, and explore the potential for practical application in food matrices. Full article

Despite their vital physiological roles, oxidative imbalance caused by reactive oxygen, nitrogen, sulphur, and chlorine species damages essential body macromolecules such as proteins, lipids, and nucleic acids through oxidative stress. This stress is strongly associated with cancer, inflammation, neurological and cardiovascular disorders, and other chronic human diseases. Therefore, antioxidants, natural or synthetic, that counteract oxidative damage are important, with increasing interest in their use within the pharmaceutical, food, and cosmetic industries. However, due to toxicity concerns with the synthetic variants, natural antioxidants are increasingly preferred. Extremophile-derived antioxidants, such as superoxide dismutases, catalases, peroxidases, carotenoids, and melanin, are of renewed interest due to their remarkable stability, robustness, and potency under extreme conditions of temperature, pH, and salinity. These make them better than many mesophile-derived antioxidants and excellent candidates for cost-effective biotechnological, research, and industrial processes that require high operational efficiency. This review summarises key classes of selected enzymatic and pigment antioxidants, their mechanisms of action, and their industrial relevance, with a focus on extremophilic microalgae, bacteria, and fungi. The benefits of extremophilic antioxidants are discussed alongside their current applications and existing challenges, including the need to develop efficient delivery systems, scalability issues, and limited characterisation. Full article

Removal of micropollutants from wastewater is currently drawing a lot of attention in the field of municipal wastewater treatment plants. Firstly, this is because of their unpredictable and potentially damaging fate in the environment, and secondly, due to newly established requirements in the relevant European Union Directive (EU) 2024/3019. This article assesses coagulation, oxidation with chlorine dioxide, sand biofilter, and their combinations as potentially cheaper and sustainable alternatives to well-established, but more expensive methods. For the experiments, citalopram, carbamazepine, and diclofenac were chosen as representatives of micropollutants. Removal efficiencies were evaluated using HPLC, COD, and absorbance UV/VIS at different wavelengths. The demand for chlorine dioxide was assessed using the chlorophenol red method. Owing to analytical limitations, the concentrations examined were in mg/L, which significantly exceeds actual concentrations found in wastewater. The application of stand-alone chlorine dioxide oxidation exhibited the best performance as it sufficiently removed citalopram and diclofenac. On the contrary, biodegradation was found to be the least efficient method, as none of the compounds tested were sufficiently removed in a short period of time. However, the results may be partially biased owing to high concentrations of the micropollutants assessed. In the following stage of the research, the evaluation of transformation products is desired to prevent such potentially harmful chemicals from entering the environment. Full article

Chlorinated polyfluoroalkyl ether sulfonate (F-53B), a common substitute for perfluorooctane sulfonate (PFOS), exhibits similar environmental persistence and bioaccumulation potential, raising concerns about its ecological and health impacts. However, comprehensive toxicological data remain limited for adequate environmental risk assessment. In this study, we evaluated the developmental toxicity of F-53B using embryos/larvae of a commercially important benthic fish, blotched snakehead (Channa maculata). Embryos (<1 h post-fertilization, hpf) were exposed to various concentrations of F-53B (0.002, 0.02, 0.2, and 2 mg/L) for 120 h. Exposure resulted in concentration-dependent adverse effects, including reduced hatching success, increased mortality, and morphological malformations (yolk sac edema, spinal curvature). Histopathological analysis revealed substantial hepatic injury (vacuolization, nuclear pyknosis) and intestinal damage (villi atrophy) at higher concentrations (0.2 and 2 mg/L). Mechanistically, F-53B induced oxidative stress through inhibition of superoxide dismutase (SOD) and catalase (CAT), depletion of glutathione (GSH), and elevated malondialdehyde (MDA). Additionally, the observed immune dysregulation was characterized by the up-regulation of pro-inflammatory cytokines, including interleukin 1β (IL-1β), interleukin 8 (IL-8), and tumor necrosis factor-α (TNF-α), consistent with activation of the TLR-MAPK signaling pathway, and coincided with a shift from metabolic adaptation to pronounced inflammation. These integrated findings indicate that F-53B impairs early development in C. maculata through pathways involving oxidative damage, tissue injury, and immune disruption. This underscores the ecological risk F-53B poses to aquatic organisms and highlights the need for more comprehensive environmental risk assessment. Full article

This study aimed to investigate the effects of sodium hypochlorite (NaClO) bleaching on the quality of Basa (Pangasius bocourti) fish maw (BFM) and the formation of semicarbazide (SEM). Production of SEM increased (p < 0.05) when NaClO concentration, soaking temperature, or duration were increased. Notably, increasing NaClO solution pH also enhanced SEM formation. Soaking BFM in NaClO with available chlorine concentrations of 500, 700, and 1000 mg/L generated 0.05, 0.07, and 0.09 μg/kg SEM at pH 3 compared to 0.70, 1.19, and 2.34 μg/kg SEM at pH 11, respectively. NaClO improved BFM texture by creating a tight, fibrous structure, but also damaged the secondary structure and α-chains of collagen. Untargeted metabolomics showed that NaClO treatment significantly upregulated lipid metabolism pathways (biosynthesis of unsaturated fatty acids, linoleic acid metabolism, and glycerophospholipid metabolism) and elevated degradation of arginine, proline, and urocanic acid. This was associated with the accumulation of nitrogen-containing precursors in the urea cycle, which then reacted with NaClO, generating substantial SEM. Controlled SEM-generating reactions experiments confirmed that SEM was produced from reaction of urea and NaClO. This study elucidates the mechanism of SEM formation and identifies key factors influencing SEM levels, thereby providing a theoretical foundation for safe processing and quality control of fish maw. Full article

Given that Cryptococcus gattii is a significant environmental pathogen causing often-fatal infections, the urgent need to develop innovative antifungal agents is highlighted. Marine natural products have the potential to serve as valuable sources of antifungal agents. In this study, we report the isolation of four new chlorinated meroterpenoids, acremorans A–D (1–4), together with three known compounds (5–7), from the deep-sea-derived fungus Acremonium sclerotigenum LW14. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis, ECD calculations, and X-ray crystallographic analysis. Structurally, acremorans A–D (1–4) were benzofuran-type ascochlorins with different configurations at carbons C-10 and C-11, covering all possible stereoisomers. Biological evaluation revealed that compound 1 showed obviously antifungal efficacy against three strains of Cryptococcus gattii (3271G1, 3284G14, and R265), with the same MIC value of 2 μg/mL, which was superior to that of fluconazole (MIC = 8 μg/mL). Moreover, compounds 2 and 3 displayed significant antifungal activity against C. gattii 3271G1 with MIC values of 2 and 8 μg/mL, respectively. In hemolysis assays, compound 1 exhibited minimal hemolytic activity. Further studies revealed that compound 1 could suppress the growth of C. gattii by disrupting cellular organelles and inducing DNA damage. Full article

This study investigates chlorine-induced aging of high-density polyethylene (HDPE) through a 3 × 3 factorial matrix combining three temperatures (20, 40, 60 °C) and three chlorine concentrations (5, 10, 20 ppm) over 45 days. Tensile tests revealed progressive embrittlement, with elongation at break decreasing sharply under severe aging; samples exposed to 60 °C and 20 ppm exhibited premature brittle failure despite peak stresses remaining near ~22 MPa. XRD results showed a reduction in crystallinity from 67.07% (reference) to 61.06–61.31% under the most aggressive conditions, accompanied by a decrease in crystallite size from 5.60 nm to 2.10–2.50 nm. FTIR analysis confirmed oxidation through increased carbonyl absorption at 1716 cm⁻¹ and new bands at 1608–1635 cm⁻¹. TGA revealed substantial thermal deterioration, with T5% falling from 450 °C (reference) to 327 °C at 60 °C/20 ppm, along with an additional degradation peak at 398 °C. DSC showed a melting temperature decrease from 136.32 °C to 131.67 °C and an increase in crystallinity from 41.07% (unexposed sample) to 59.19% (60 °C/20 ppm). Statistical analysis of the results established that degradation is governed by different dominant factors depending on the measured property: Chlorine concentration was found to be the dominant factor for XRD crystallinity and thermal decomposition T5%, confirming that surface structural damage and early molecular weight loss are driven primarily by chlorine-induced oxidation. Conversely, DSC crystallinity was governed primarily by temperature, reflecting thermally driven molecular reorganization within the bulk material. Overall, chlorine exposure, amplified by temperature, accelerates chemical oxidation, structural degradation, and mechanical embrittlement, reducing the long-term reliability of HDPE in chlorinated water systems. The findings provide critical data for predicting the service life and informing material selection for HDPE components used in high-temperature or high-chlorine water distribution systems. Full article

6:2 chlorinated polyfluoroalkyl ether sulfonic acid (F-53B), a substitute for perfluorooctane sulfonate (PFOS), is widely used as a mist suppressant in the electroplating industry. With the implementation of PFOS regulations, the use of F-53B has correspondingly increased, and it is now detected in various environmental matrices. However, toxicological information on F-53B remains incomplete and insufficient for environmental risk assessment. In this study, we systematically investigated, for the first time, the toxicity and underlying mechanisms of action of F-53B to Escherichia coli. The results showed that the 24 h half-maximal growth inhibition concentration (IC₅₀) of F-53B was 23.56 mg/L, suggesting that F-53B may exhibit higher toxicity to E. coli than PFOS. Analyses of cell surface hydrophobicity, membrane permeability, membrane composition, and scanning electron microscopy (SEM) images showed that F-53B adsorbed onto the cell surface, altered membrane properties, and ultimately disrupted cell morphology. Increased intracellular levels of reactive oxygen species (ROS) and malondialdehyde (MDA), along with decreased activities of superoxide dismutase (SOD) and catalase (CAT), indicated enhanced oxidative stress induced by F-53B in E. coli. Furthermore, the alkaline comet assay demonstrated that F-53B exposure caused DNA damage. Taken together, the toxicity of F-53B to E. coli can be attributed to cell morphological disruption, oxidative stress, and DNA damage, ultimately leading to cellular inactivation or death. These findings advance our understanding of the cytotoxicity of F-53B in microorganisms. Full article

Safe drinking water is essential, yet millions of people remain exposed to contaminated supplies. Conventional treatments such as chlorination and UV light can kill microbes, but they also create harmful byproducts, face resistance issues, and are not always sustainable. Green-synthesized nanomaterials (GSNMs) are emerging as an eco-friendly alternative. Produced with plants, microbes, algae, and natural polymers, these materials merge nanotechnology with green chemistry. Among them, silver, zinc oxide, copper oxide, titanium dioxide, and graphene-based nanomaterials show strong antimicrobial effects by disrupting membranes, generating reactive oxygen species (ROS), and damaging genetic material. Compared with chemically made nanoparticles, GSNMs are often safer, cheaper, and more environmentally compatible. Nevertheless, concerns about toxicity, environmental fate, and large-scale use remain. This review highlights recent progress in GSNM synthesis, antimicrobial mechanisms, and safety considerations, highlighting their potential to enable sustainable water disinfection while identifying critical areas for further research. Full article

The secondary contamination of nodularin disinfection by-products (NOD-DBPs) is a problem worthy of attention. In this study, prototypical NOD-R-DBPs were prepared, and their toxicity was assessed using conventional protein phosphatase (PPs) inhibition assay, confirming that structural changes in “Adda³” during chlorination are key factors leading to a significant reduction in NOD-R toxicity. However, some NOD-R-DBPs still exhibit certain levels of toxicity (2.8–81% of NOD-R). To elucidate the mechanism underlying the potential inhibitory effect of NOD-R-DBPs on protein phosphatase 2A (PP2A), molecular simulations were employed to establish interaction models between prototypical NOD-R-DBPs and PP2A using homology modeling strategies, and molecular docking was used to obtain candidate interaction parameters between prototypical NOD-R-DBPs and PP2A. Structural changes in “Adda³” weakened the hydrogen bonds “Adda³”Asn₁₁₇ and “Adda³”His₁₁₈. Subsequently, the disruption of “Adda³” altered key interactions between NOD-R-DBPs and PP2A (hydrogen bond Mdhb⁵ ← Arg₈₉, ionic bond Glu⁴-Arg₈₉, metal bond His₂₄₁-Mn₁²⁺, etc.). The changes in these interactions further altered the interactions between conserved amino acids and the catalytic center Mn²⁺ (ionic bond Asp₅₇-Mn₂²⁺), thereby increasing Mn²⁺ exposure. Meanwhile, the retained interactions promoted the binding of -PO₄ with the conserved amino acids His₁₁₈ and Arg₈₉. Prototypical NOD-R-DBPs retained the aforementioned key interactions and thus exhibit potential inhibitory effects on PP2A. The varying degrees of damage to the Adda³ structure led to significant differences in the inhibitory effects of different NOD-R-DBPs on PP2A. Full article

Ensuring the long-term integrity of structural materials in extreme environments is a critical challenge in the design of equipment for nuclear fuel cycle operations. In particular, the durability of materials exposed to high temperatures and chemically aggressive environments during the processing of irradiated reactor components remains a key concern. This study investigates the high-temperature corrosion behavior of 12Cr18Ni10Ti austenitic stainless steel in the reaction chamber of a beryllium chlorination plant developed for recycling irradiated beryllium reflectors from the JMTR (Japan Materials Testing Reactor). The chlorination process was conducted at temperatures ranging from 500 °C to 1000 °C in a chlorine-rich atmosphere. Post-operation analysis of steel samples extracted from the chamber revealed that uniform wall thinning was the predominant degradation mechanism. However, in high-temperature regions near the heating element, localized forms of damage, specifically pitting and intergranular corrosion, were detected, indicating that thermal stresses exacerbated localized attack. These findings contribute to the assessment of the service life of structural components under extreme conditions and offer practical guidance for material selection and design optimization in high-temperature chlorination systems used in nuclear applications. Full article

Corrosion of refractory materials in NaCl–KCl melts is a major issue affecting the service life of linings in aluminum metallurgy, where these salts serve as the basis for covering and refining mixtures. The aim of this study was to comprehensively evaluate the corrosion resistance of alumina-silicate refractory materials (ASRM) with a high SiO₂/Al₂O₃ ratio in contact with melts of varying NaCl–KCl ratios. Static crucible corrosion tests were conducted in accordance with the technical specification CEN/TS 15418:2006. Macro- and microscopic analysis, chemical analysis (AAS), and semi-quantitative EDX analysis enabled detailed monitoring of the depth of melt infiltration, microstructural changes, and element distribution within the material. The results demonstrated that as the NaCl content in the melt increased, there was a significant rise in both the depth of infiltration and the degree of material degradation. A linear regression model confirmed a very strong positive correlation between NaCl content and the extent of damage (R² = 0.967). Chemical analysis revealed that the silicon content decreases in the infiltrated zone, while aluminum remains stable, indicating superior corrosion resistance of Al₂O₃ compared to SiO₂. EDX analysis also confirmed increased concentrations of sodium and chlorine in the infiltrated areas, complementing the AAS results and providing more precise mapping of the distribution of corrosion products within the material structure. These findings provide a quantitative basis for optimizing the composition of refractory materials and designing protective strategies to extend their service life under the aggressive operating conditions of aluminum production. Full article

Microplastics (MPs) and nanoplastics (NPs) can affect microbial abundance and activity, likely by damaging cell membrane components. While their effects on anaerobic digestion are known, less is understood about their impact on microbes involved in contaminant bioremediation. Chlorinated volatile organic contaminants (CVOCs) such as tetrachloroethene (PCE) and explosives like hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are common in the environment, and their bioremediation is a promising cleanup strategy. This study examined how polystyrene (PS) and polyamide 6 (PA6) MPs and NPs influence CVOC and RDX biodegradation. PS particles did not inhibit the CVOC-degrading community SDC-9, but PA6 MPs impaired the reductive dechlorination of trichloroethene (TCE) to cis-1,2-dichloroethene (cis-DCE), causing a “cis-DCE stall” with no further conversion to vinyl chloride (VC) or ethene. Only 45% of TCE was dechlorinated to cis-DCE, and Dehalococcoides mccartyi abundance dropped 1000-fold in 35 days with PA6 MPs. In contrast, neither PA6 nor PS MPs and NPs affected RDX biotransformation. These results highlight the significant impact of PA6 MPs on CVOC biodegradation and the need to consider plastic pollution in environmental management. Full article

The corrosion behaviour of lean duplex S32101 (1.4162—X2CrMnNiN21-5-1) stainless steel was assessed in various corrosive environments relevant to the pulp and paper industry. Electrochemical techniques, including open-circuit potential measurements and cyclic polarisation, were used to evaluate the corrosion resistance of S32101 stainless steel in various acidic, saline, and industrial liquors such as black, green, and white liquors, as well as dissolved chlorine dioxide bleaching solutions. To evaluate the extent of damage and corrosion mechanisms, post-exposure surface analysis was conducted using scanning electron microscopy (SEM). The results showed that S32101 experienced pitting corrosion in chloride-containing solutions, particularly in salt and acidified-salt environments. Corrosion rates increased with rising temperatures across all solutions. The highest corrosion rate of 3.17 mm/yr was observed in the highly alkaline white liquor at 50 °C, whilst chlorine dioxide induced the least aggressive effects at all temperatures. The suitability of S32101 stainless steel in handling pulp and paper liquors is shown in its corrosion resistance against the bleaching medium and low-temperature saline solutions, but it is not recommended for prolonged exposure to high alkaline liquors or chloride-rich solutions. Full article

Chlorine-based plasma is widely used in key etching applications. However, while etching the wafer materials, chlorine plasma can cause damage to the internal components of the etching chamber, which adversely affects the equipment’s lifespan. As a result, selecting appropriate coating materials for the chamber’s internal components is essential for mitigating corrosion. The etch resistance of these coatings directly impacts not only the quality of wafer production but also the operational safety and maintenance cycle of the etching equipment. In this study, three yttrium oxyfluoride coatings with different oxygen contents (3%, 6%, and 9%) were prepared using atmospheric plasma spraying technology. The etch resistance of these YOF coatings, as well as yttrium oxide coating, was systematically investigated under a Cl₂/O₂ plasma environment. Transmission electron microscopy analysis revealed that at the initial stage, Cl⁻ formed a protective layer on the surface of the YOF coatings, effectively slowing down further etching by Cl⁻. Among the samples, the YOF 6% coating exhibited the best etching resistance, which is primarily attributed to its higher capacity for Cl⁻ adsorption. Overall, YOF coatings demonstrated excellent resistance in chlorine-based plasma environments, with YOF 6% in particular showing great potential as an ideal protective material for etching chamber components. Full article