Search Results (3,015)

Background: Access to safe drinking water remains a critical public health concern in rural Ghana, particularly in climatically vulnerable and underserved settings. This study assessed the microbiological and chemical quality of drinking water and evaluated nitrate-related health risks in the North Gonja and North-East Gonja Districts of the Savannah Region. Methods: A cross-sectional study was conducted between January and March 2025. A total of 460 water samples were collected from groundwater sources and household storage containers. Microbial analyses targeted total coliforms and Escherichia coli. Physicochemical and chemical parameters included nitrate-nitrogen, pH, residual chlorine, major ions, and trace metals. Data was analyzed using descriptive statistics, chi-square tests, spatial interpolation, and non-carcinogenic health risk assessment based on the hazard quotient (HQ) approach. Results: Widespread microbial contamination was observed, with 91.5% of household water samples positive for total coliforms and 46.6% for E. coli. Contamination of source water was significantly higher in North Gonja than in North-East Gonja. Overall, 49.1% (n = 55) of groundwater sources exceeded the World Health Organization guideline value for nitrate-nitrogen, with exceedances predominantly occurring in North Gonja. Additionally, 67.0% (n = 75) of samples were outside the acceptable pH range (6.5–8.5), including 74 samples below 6.5 and one above 8.5. Residual chlorine was not detected in any of the samples. Health risk assessment indicated potential non-carcinogenic risks associated with nitrate exposure, particularly among infants and children. Conclusions: The study demonstrates significant microbial contamination and nitrate-related health risks in the study area, particularly in North Gonja. Interventions such as improved source protection, routine water quality monitoring, chlorination, household water treatment, and implementation of Water Safety Plans are recommended to enhance drinking water safety and reduce associated public health risks. Full article

Bonellia viridis, an echiuran polychaete that inhabits infralittoral rocky habitats around the Atlantic, Mediterranean, and Southeastern Pacific coastlines, exhibits environmentally mediated sexual dimorphism: planktonic larvae develop into dwarf males after exposure to bonellin, a green pigment produced by adult females. Bonellin is a chlorin with a structure consistent with derivation from uroporphyrinogen III, the last universal precursor of all known tetrapyrroles, yet its biosynthesis remains unknown. Here, the de novo genome assembly for a single adult female specimen of B. viridis isolated from Okinawa has been generated (via Illumina sequencing) and found to comprise 429.95 Mb across 95,859 contigs, with an N50 of 6505 bp, recovering 83.3% of near-universal metazoan BUSCO orthologs. Homologs of all canonical enzymes of the heme biosynthetic pathway (termed hem genes) were identified across the genome. The genomic resources establish a foundation for research into the biochemical basis of pigment production, chemically mediated sex determination, and the distinct biology of B. viridis. Full article

Background: Epidemiological data link hard and chlorinated water to atopic dermatitis (AD), but experimental evidence on their effect and on dermocosmetic benefit remains limited. Objectives: We aimed to compare the effects of soft, hard, and chlorinated water on atopic skin and assess whether a dermocosmetic routine mitigates these effects. Methods: In a 3-day, open-label, intra-individual study, 66 adults with atopic skin underwent repeated forearm immersions (five cycles/day) in soft, hard, or chlorinated water. One forearm received a cleansing-oil and moisturising-balm routine after each cycle; the contralateral forearm served as untreated control. TEWL, hydration, and global discomfort were assessed. In a 21-day real-life study, adults with AD regularly exposed to hard domestic or swimming-pool water used the routine daily. Discomfort and quality of life were recorded. Results: Water immersion induced modest, inconsistent TEWL changes, increased hydration and slightly reduced discomfort, without differences between water types. The routine reduced TEWL, increased hydration, and decreased discomfort for all water types. In real life, it produced immediate and sustained improvements in discomfort and quality of life. Conclusions: Under controlled exposure, soft, hard, and chlorinated water exert comparable, limited effects on atopic skin. The dermocosmetic routine consistently improves barrier-related parameters and comfort, independently of water type. Full article

Green fair-faced concrete (GFFC) is characterized by low surface porosity and small pore sizes and is widely used in architectural concrete engineering. It remains challenging to meet the appearance quality requirements of GFFC with conventional mix ratios and additives. This paper introduces double-mix defoamers and air-entraining agents into GFFC slurry to further refine the internal bubble size of GFFC slurry, optimize the surface pore structure, and thereby improve the apparent morphology of cured GFFC. The effects of double-agent doping on the slump, mechanical strength, shrinkage performance and impermeability durability of GFFC were also investigated. The results show that, compared with the baseline, after binary doping of the defoamer and air-entraining agent, the slump loss over time of GFFC slurry has been significantly reduced; the average porosity of GFFC is 0.132%, and the maximum average pore diameter is only 1.01 mm, which is decreased by 57.35% and 67.68%, respectively; the 45 day shrinkage of the GFFC doped with 3‱ defoamer and 4‱ air-entraining agent is 338 × 10⁻⁶ with a decrease of 33.98%, and the resistance to 84d chlorine ionization migration coefficient is 1.3 × 10⁻¹² m²/s with a decrease of 38.09%. These outcomes can effectively contribute to the pore refinement and apparent morphology improvement of GFFC doped with a binary defoamer and air-entraining agent. Full article

Traditional electro-Fenton systems for chlorinated antibiotic wastewater suffer from low mineralization, catalyst deactivation, and secondary pollution caused by chloride ions. In this work, nitrogen-functionalized graphite felt cathodes were synthesized by electrodeposition-pyrolysis. Pyridinic N and graphitic N were identified by XPS. The obtained cathodes were employed in a metal-free electro-Fenton system for effective tetracycline (TC) removal and mineralization. The results show that the optimal electrode (N-GF-3) achieved 93% degradation efficiency and 73% mineralization of TC in 60 min, when the optimized conditions (pH = 3 and current density = 20 mA/cm²) were employed. Unusually, with the presence of Cl⁻, the system showed even higher catalytic performance, having a degradation kinetic constant 2.4 times higher than that without chloride. The electrode was also reusable, maintaining a TC degradation efficiency above 90% in the fifth cycle. Based on fluorescence analysis of ·OH, a possible dual-path reaction mechanism is proposed. This mechanism provides new insights into designing advanced oxidation processes for the treatment of complex chlorinated organic wastewater. Nevertheless, the potential formation of chlorinated byproducts requires additional investigation. Full article

Photodynamic therapy (PDT) represents a promising non-antibiotic strategy for addressing bacterial and fungal infections, particularly in the context of increasing antimicrobial resistance and biofilm-associated disease. PDT is based on the light-induced activation of photosensitizers, leading to the generation of reactive oxygen species (ROS), including singlet oxygen (¹O₂), which induce oxidative damage to multiple microbial targets. Unlike conventional antimicrobial drugs that often act through specific molecular pathways, antimicrobial PDT produces simultaneous damage to membranes, proteins, nucleic acids, and extracellular biofilm components, thereby reducing the probability of resistance development. This review critically analyzes the cellular, biochemical, and biophysical determinants that govern PDT selectivity toward bacterial and fungal cells in comparison with mammalian host tissues. Particular attention is given to photosensitizer localization, membrane interactions, photobleaching, oxygen dependence, light penetration, and the balance between Type I and Type II photochemical mechanisms. The review provides a comparative overview of major molecular photosensitizer classes, including phenothiazines, porphyrins, chlorins, phthalocyanines, xanthene dyes, natural polyphenols, endogenous compounds, and advanced targeted photosensitizers. In addition, this review distinguishes molecular photosensitizers from nanotechnology-based platforms and delivery systems. Nanoparticles, polymeric carriers, hydrogels, and light-activated coatings are discussed not only as photosensitizer delivery tools, but also as systems that modulate aggregation, improve localization, enhance biofilm penetration, and enable surface-confined ROS generation. ROS are capable of causing phototoxic effects wherever they are located. Unless selectively accumulated by target organisms, there can be systemic phototoxicity. Overall, PDT should be regarded as a modular antimicrobial platform in which photosensitizer chemistry, formulation, light delivery, oxygen availability, and infection biology must be co-optimized. Although further studies are required to address clinical translation, regulatory complexity, material safety, and standardized treatment protocols, PDT offers a scientifically robust and clinically relevant approach that may complement conventional antibacterial and antifungal therapies, especially in localized, biofilm-associated, and device-related infections. Full article

Ionic liquid-based localized high-concentration electrolytes, leveraging their intrinsically nonflammable safety characteristics and wide electrochemical windows, have emerged as strong contenders for next-generation lithium metal battery electrolytes. However, because such systems are anion-rich, the electrolyte bulk phase tends to form solvation structures dominated by bulky anionic clusters along with an excess of free anions, which triggers persistent and uncontrollable anion decomposition at the interphase. To address this issue, we adopt a strategy of constructing a compressed solvation structure by introducing a weakly interacting chlorinated diluent (TeCA), which helps form a compact solvation environment and alleviates excessive anion decomposition at electrode interphases. In this work, 1,1,2,2-tetrachloroethyl acetate (TeCA) was introduced as a weakly coordinating chlorinated diluent into an ionic-liquid localized high-concentration electrolyte (LHCE) to regulate the Li⁺-FSI⁻ solvation environment. By combining Raman spectroscopy, molecular dynamics simulations, and electrochemical characterization, the TeCA-LHCE system was found to exhibit altered ion-cluster configurations, improved oxidation tolerance, and enhanced interfacial stability under high-voltage conditions. The as-prepared TeCA-LHCE electrolyte presents improved electrochemical performance in comparison with TTE-LHCE and the baseline electrolyte (BE). The Li||Cu half-cell employing TeCA-LHCE achieved a high Coulombic efficiency above 99% over 500 cycles and formed a uniform and dense lithium deposition layer without obvious dendritic growth. When paired with a high-loading NCM811 cathode (10 mg cm⁻²), the TeCA-LHCE-based Li||NCM811 full cell delivered significantly improved cycling stability and rate capability under a high cutoff voltage of 4.3 V. Full article

Reactivity of non-aromatic 2,5-dichloro-2H-pyrroles toward S-nucleophiles was investigated. It was found that these non-aromatic derivatives exhibit both oxidative and electrophilic properties. Their reaction with thiols and xanthates proceeds as redox process to form disulfides and 5-chlorinated pyrroles as a result of 2,5-dichloro-2H-pyrroles reduction. However, the reaction with ammonium thiocyanate afforded the corresponding 5-thiocyanated 1H-pyrroles. Based on these findings, a novel one-pot method for the thiocyanation of 2,3,4-trisubstituted pyrroles was developed. The protocol involves the in situ generation of highly reactive 2,5-dichloro-2H-pyrroles via dearomative chlorination of the corresponding pyrroles using trichloroisocyanuric acid (TCCA). Subsequent addition of ammonium thiocyanate leads to regioselective incorporation of a thiocyanate group at the C5 position and rearomatization of the pyrrole core. A broad scope of pyrrole-5-thiocyanates was obtained in yields up to 82%. Furthermore, these derivatives were efficiently transformed into 5-trifluoromethylthiolated pyrroles using Ruppert’s reagent in up to 94% yield. This reaction sequence provides a cost-effective way to obtain 5-trifluoromethylthiolated pyrroles, avoiding the need for high-cost electrophilic reagents. The synthetic utility of these novel sulfur-containing pyrrole derivatives was also demonstrated. Full article

Steric effects refer to the effect of the size and spatial arrangement of atoms or groups on the reactions, interactions, and catalytic activities of molecules. The incorporation of Cl (chlorine) and Br (bromine) atoms as substituents into phthalocyanine (Pc) structures can have important catalytic effects. These effects arise mainly from their electronic and steric properties, which influence the behavior of the central metal ion and the overall catalyst performance. In this work, Co(II)PcQBr₂ was synthesized and characterized by spectral techniques. The catalytical activity of Co(II)PcQBr₂ was then evaluated for the oxidation of benzyl alcohol. The effects of the substrate/catalyst ratio, oxidant/catalyst ratio, oxidant type and temperature on the oxidation reaction of benzyl alcohol were investigated. Both catalysts exhibited high TON, TOF and total conversion yields in the presence of H₂O₂ as the oxidant at 50 °C. (substrate/oxidant/catalyst:1000/500/1). When the total product conversions were calculated for both catalysts, Co(II)PcQBr₂ was found to have a lower product conversion (88.7%, with a TON of 914 and a TOF of 457 ) than Co(II)PcQCl₂. Moreover, Co(II)PcQCl₂ was determined to have higher selectivity of benzyl benzoate (94.0%, with a TON of 940 and a TOF of 470 ). The larger size of the Br atom compared to that of the Cl atom was observed to reduce catalytic activity. Considering the size of the Cl atom, it was concluded that steric effects favor the formation of benzyl benzoate by inhibiting possible side reactions, thus increasing the catalytic activity. Full article

Zirconium (Zr) is a strategic metal resource whose performance is significantly degraded by high oxygen content. The external gettering process is an effective approach for in-depth deoxidation of Zr. In this study, the deoxidation behavior of Zr in the Ca-Y-CaCl₂ external gettering system was investigated by adjusting the chlorine potential through YCl₃ addition. The change of oxygen potential and its synergistic control mechanism during the variation of chlorine potential were systematically examined. The results demonstrated that with increasing chlorine potential, the system undergoes a sequence of reactions: chlorination of Ca, formation of metallic Y, formation of YOCl, dissolution of Y₂O₃, and formation of YCl₃, ultimately reaching a three-phase equilibrium of Y-YOCl-YCl₃. During this process, the oxygen content of Zr fluctuates notably, which is primarily attributed to the shift in the oxygen-transfer medium from Ca to Y. This transition changes the oxygen potential control mechanism from indirect Y-Ca control to direct Y control. After reaching equilibrium at 1173 K for 72 h, the equilibrium oxygen content of Zr initially remains stable with increasing chlorine potential, then gradually decreases, eventually reaching 20 ppmw. This trend is consistent with the mutual interaction of oxygen potential and chlorine potential. The findings provide important theoretical insights into the interaction between oxygen and chlorine potentials in deoxidation systems, elucidate the multi-element synergistic mechanism for oxygen control, and contribute to the design of efficient deoxidation systems. Full article

This review presents a process-based decision-making framework for chlorinated vapor intrusion (CVI) mitigation. CVI mitigation refers to the set of engineered strategies aimed at interrupting, attenuating or transforming vapor fluxes before they reach indoor environments. Existing literature and technical guidelines typically classify mitigation strategies according to technological configuration (active versus passive), rather than physical and chemical processes governing vapor transport and attenuation, which may lead to suboptimal design choices and reduced system resilience. To address this limitation, this framework proposes a process-based classification of CVI mitigation strategies based on the dominant mechanisms controlling vapor migration in subsurface. Five mechanistic categories are identified: driving-force control through pressure manipulation, dilution via air exchange, diffusive flux control through physical barriers, density-driven attenuation in permeable sub-slab layers, and in situ transformation based on sorption or degradation. By explicitly linking mitigation technologies to transport and transformation processes, the proposed framework provides a structured basis for mechanism-oriented selection, integrating performance, longevity, climate resilience, and lifecycle energy demand. In addition to established mitigation approaches, such as sub-slab depressurization, this work highlights emerging passive strategies, including high permeable granular layers and horizontal reactive or adsorbing barriers, as potential low-energy alternatives for durable management. Overall, the proposed framework supports site-specific, sustainability-oriented decision-making on CVI mitigation. Full article

Antibiotic resistance genes (ARGs) are increasingly recognized as a concern in drinking water, yet the factors influencing their persistence from raw to finished water in drinking water treatment plants remain poorly understood. This study investigated the occurrence, removal, and potential factors associated with the persistence of ARGs (sul1, sul2, and tetG) in a full-scale rapid sand filtration drinking water treatment system with intermediate and post-chlorination. ARGs were detected in raw water at a median total concentration of 10⁶ copies/L and remained detectable in finished water at 10⁴ copies/L. Relative ARG abundance increased after treatment despite substantial absolute reductions (2.1–3.6 log). Intermediate chlorination achieved the greatest ARG log reduction value (0.53–2.4 log), likely due to higher chlorine dose and lower pH favoring HOCl formation. By contrast, post-chlorination at higher pH provided limited additional removal, possibly due to predominance of less reactive OCl⁻ and survival of chlorine-tolerant bacteria. Multivariate analyses showed a shift from particle-bound ARGs in raw water to dissolved organic matter (DOM) and fine-particle-associated fractions along the treatment train. These findings suggest that reducing fine particles and DOM, together with optimized disinfection, may help lower ARG-associated risk in finished water. Full article

The presence of xenobiotics in wastewater, particularly emerging contaminants such as pharmaceuticals, poses an ecotoxicological risk to the environment and human health. One of the main pharmaceutical products detected in water is diclofenac, which can be sold without a prescription. The lack of health regulations indicates the necessity of finding environmentally friendly treatment alternatives to remove this type of contaminant. Among these alternatives, biotechnology, specifically biological processes, offers a sustainable option compared to conventional treatments. Current treatment methods used in wastewater treatment plants are ineffective at removing diclofenac, a chlorinated aromatic compound highly resistant to degradation processes. In recent years, new treatment methods have gained prominence due to the favorable results they have yielded, including physicochemical, biological, and advanced processes. Biological treatments are notable for their low cost and the high level of effectiveness and efficiency with which they can remove toxic compounds. For this reason, the aim of this research project was to evaluate the degradation efficiency of a biological treatment in a bioreactor using a microbial community consisting of five bacterial strains, which was isolated from a pharmaceutical effluent and cultivated in a continuous culture system. Removal efficiencies ranging from 99.38 to 99.98% were achieved at various volumetric loading rates (from 0.087 to 1.043 g L⁻¹d⁻¹). Influents and effluents from the biological reactor were analyzed using bioassays to determine any potential toxic effects. The results showed that the effluents did not elicit a negative response in the bioindicators, indicating high toxicity in the influents. Full article

Microplastics (MPs) in wastewater treatment plants are exposed to oxidative conditions during disinfection and advanced oxidation processes (AOPs), which can alter morphology and surface chemistry and influence interactions with coexisting contaminants. Here, accelerated chemical oxidation was simulated using heat-activated potassium persulfate (K₂S₂O₈) and sodium hypochlorite (NaOCl) to examine the oxidative aging of MPs made from polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP). Changes in particle morphology and surface chemistry before and after oxidant treatment were characterized using scanning electron microscopy (SEM) for morphological analysis and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy for chemical characterization. Carbonyl formation, an indicator of polymer oxidation, was evaluated using the carbonyl index (CI). Both oxidants induced surface morphological defects and carbonyl functional groups in the MPs, with CI increasing with degradation time. The CI trends suggest that MP oxidation varies with polymer type and oxidant. The effect of oxidative aging on MP sorption capacity was also investigated using copper ions as a model inorganic constituent. Although oxidative aging introduced oxygen-containing functional groups, no statistically significant differences in copper sorption were observed between pristine and oxidized MPs, indicating that MPs can act as vectors for copper regardless of their degree of surface oxidation. Full article

Most water supply systems rely on free chlorine residual to ensure disinfection through the network and at the user’s tap. Temperature increase is known to accelerate the chlorine decay process and is typically associated with water quality deterioration. This is a challenging situation under the current climate change scenario, which is bound to increase average temperatures and the intensity and frequency of extreme-temperature events. Moreover, water temperature varies through the supply network due to seasonal changes and thermal interaction, so it is not straightforward to model chlorine evolution through the network considering temperature effects. Previous works have highlighted the importance of considering the Arrhenius formula when accounting for temperature changes in the bulk chlorine decay coefficient (typically characterized through bottle tests), but these studies have never explicitly considered the uncertainty of the bulk decay coefficient itself. Recent studies have identified that the uncertainty of the bulk decay coefficient may be relevant (>15%) and should be considered when cross-comparing bottle test results (e.g., at different temperatures). The aim of this work is to propose a new method that statistically computes the mean and standard deviation of the key parameters in the Arrhenius formula (the reference bulk decay coefficient $k_{b_0}$ and activation coefficient E/R) from free chlorine residual bottle test results (with replicated measurements over samples from the entrance to the network) at different temperatures. This approach (here called the ensemble temperature state estimation approach) ensures that bottle test measurements at different temperatures are jointly assessed to derive an equation that provides the bulk decay coefficient at any water temperature. Therefore, the new method improves the characterization of the bulk decay component (and its associated uncertainty) and could be crucial for improving the understanding and modeling capabilities of complex chlorine dynamics within supply infrastructure. Full article