Recapitulation of human pathophysiology and identification of forensic biomarkers in a translational model of chlorine inhalation injury

Chlorine gas (Cl2) has been repeatedly used as a chemical weapon, first in World War I and most recently in Syria. Life-threatening Cl2 exposures frequently occur in domestic and occupational environments, and in transportation accidents. Modeling the human etiology of Cl2-induced acute lung injury (ALI), forensic biomarkers, and targeted countermeasures development have been hampered by inadequate large animal models. The objective of this study was to develop a translational model of Cl2-induced ALI in swine to understand toxico-pathophysiology and evaluate whether it is suitable for screening potential medical countermeasures and to identify biomarkers useful for forensic analysis. Specific pathogen-free Yorkshire swine (30-40 kg) of either sex were exposed to Cl2 (≤240 ppm for 1 h) or filtered air under anesthesia and controlled mechanical ventilation. Exposure to Cl2 resulted in severe hypoxia and hypoxemia, increased airway resistance and peak inspiratory pressure, and decreased dynamic lung compliance. Cl2 exposure resulted in increased total leucocyte and neutrophil counts in bronchoalveolar lavage fluid, vascular leakage, and pulmonary edema compared with the air-exposed group. The model recapitulated all three key histopathological features of human ALI, such as neutrophilic alveolitis, deposition of hyaline membranes, and formation of microthrombi. Free and lipid-bound 2-chlorofatty acids and chlorotyrosine-modified proteins (3-chloro-l-tyrosine and 3,5-dichloro-l-tyrosine) were detected in plasma and lung tissue after Cl2 exposure. In this study, we developed a translational swine model that recapitulates key features of human Cl2 inhalation injury and is suitable for testing medical countermeasures, and validated chlorinated fatty acids and protein adducts as biomarkers of Cl2 inhalation.NEW & NOTEWORTHY We established a swine model of chlorine gas-induced acute lung injury that exhibits several features of human acute lung injury and is suitable for screening potential medical countermeasures. We validated chlorinated fatty acids and protein adducts in plasma and lung samples as forensic biomarkers of chlorine inhalation.

Chlorine-Induced Toxicity on Murine Cornea: Exploring the Potential Therapeutic Role of Antioxidants

Chlorine (Cl2) exposure poses a significant risk to ocular health, with the cornea being particularly susceptible to its corrosive effects. Antioxidants, known for their ability to neutralize reactive oxygen species (ROS) and alleviate oxidative stress, were explored as potential therapeutic agents to counteract chlorine-induced damage. In vitro experiments using human corneal epithelial cells showed decreased cell viability by chlorine-induced ROS production, which was reversed by antioxidant incubation. The mitochondrial membrane potential decreased due to both low and high doses of Cl2 exposure; however, it was recovered through antioxidants. The wound scratch assay showed that antioxidants mitigated impaired wound healing after Cl2 exposure. In vivo and ex vivo, after Cl2 exposure, increased corneal fluorescein staining indicates damaged corneal epithelial and stromal layers of mice cornea. Likewise, Cl2 exposure in human ex vivo corneas led to corneal injury characterized by epithelial fluorescein staining and epithelial erosion. However, antioxidants protected Cl2-induced damage. These results highlight the effects of Cl2 on corneal cells using in vitro, ex vivo, and in vivo models while also underscoring the potential of antioxidants, such as vitamin A, vitamin C, resveratrol, and melatonin, as protective agents against acute chlorine toxicity-induced corneal injury. Further investigation is needed to confirm the antioxidants' capacity to alleviate oxidative stress and enhance the corneal healing process.

The Ca∗Cl/P Ratio: A Novel and More Appropriate Screening Tool for Normocalcaemic or Overt Primary Hyperparathyroidism

OBJECTIVE

The main purpose of this study was to explore the diagnostic performance of the Ca∗Cl/P ratio for primary hyperparathyroidism (PHPT), especially normocalcaemic PHPT (NPHPT), to assist health care providers in making reliable and rapid clinical identifications.

METHODS

From January 1, 2013, to March 31, 2023, 230 PHPT patients, including 65 with NPHPT and 230 sex- and age-matched controls, were enrolled in this retrospective study. Differences between hypercalcaemic PHPT (HPHPT) and NPHPT and between them and their respective controls were analyzed. The diagnostic accuracy of the Ca∗Cl/P ratio, Ca/P ratio, Cl/P ratio and albumin-corrected calcium was assessed by the area under the receiver operating characteristic curve.

RESULTS

Compared with corresponding controls, NPHPT and HPHPT patients both had significantly higher Ca ∗ Cl/P ratios (271.64 ± 51.74 vs 192.71 ± 26; 419.91 ± 139.11 vs 199.14 ± 36.75, P < .001). In the overall cohort, the ROC-AUC of the Ca∗Cl/P ratio (0.964, 95% CI = 0.943-0.979) for diagnosis of PHPT patients was superior to albumin-corrected calcium (0.959, 95% CI = 0.934-0.973), the Ca/P ratio (0.956, 95% CI = 0.934-0.973), and the Cl/P ratio (0.923, 95% CI = 0.895-0.946). A Ca ∗ Cl/P ratio above 239.17 mmol/L, with sensitivity (0.952), specificity (0.922), PPV (0.924), NPV (0.951) and accuracy (0.937), can distinguish PHPT patients from healthy individuals. Furthermore, the Ca ∗ Cl/P ratio yielded a sensitivity of 0.831, specificity of 0.938, PPV of 0.931, NPV of 0.847 and accuracy of 0.885 for NPHPT.

CONCLUSION

The Ca∗Cl/P ratio provides excellent diagnostic power for diagnosis of PHPT, especially NPHPT.

Antimicrobial Tolerance in Salmonella: Contributions to Survival and Persistence in Processing Environments

Salmonella remains a top bacterial pathogen implicated in several food-borne outbreaks, despite the use of antimicrobials and sanitizers during production and processing. While these chemicals have been effective, Salmonella has shown the ability to survive and persist in poultry processing environments. This can be credited to its microbial ability to adapt and develop/acquire tolerance and/or resistance to different antimicrobial agents including oxidizers, acids (organic and inorganic), phenols, and surfactants. Moreover, there are several factors in processing environments that can limit the efficacy of these antimicrobials, thus allowing survival and persistence. This mini-review examines the antimicrobial activity of common disinfectants/sanitizers used in poultry processing environments and the ability of Salmonella to respond with innate or acquired tolerance and survive exposure to persists in such environments. Instead of relying on a single antimicrobial agent, the right combination of different disinfectants needs to be developed to target multiple pathways within Salmonella.

Potential exhaled breath biomarkers identified in chlorine-exposed mice

Exhaled breath (EB) contains various volatile organic compounds (VOCs) that can indicate specific biological or pathological processes in the body. Analytical techniques like gas chromatography/mass spectrometry (GC/MS) can be used to detect and measure these exhaled biomarkers. In this study, the objective was to develop a non-invasive method of EB sampling in awake animals, as well as to analyze EB for volatile biomarkers specific for chlorine exposure and/or diagnostic biomarkers for chlorine-induced acute lung injury (ALI). To achieve this, a custom-made sampling device was used to collect EB samples from 19 female Balb/c mice. EB was sampled both pre-exposure (serving as internal control) and 30-min after exposure to chlorine. EB was collected on thermal desorption tubes and subsequently analyzed for VOCs by GC/MS. The following day, the extent of airway injury was assessed in the animals by examining neutrophils in the bronchoalveolar lavage fluid. VOC analysis revealed alterations in the EB biomarker pattern post-chlorine exposure, with eight biomarkers displaying increased levels and six exhibiting decreased levels following exposure. Four chlorinated compounds: trichloromethane, chloroacetone, 1,1-dichloroacetone, and dichloroacetonitrile, were increased in chlorine-exposed mice, suggesting their specificity as chlorine EB biomarkers. Furthermore, chlorine-exposed mice displayed a neutrophilic inflammatory response and body weight loss 24h following exposure. In conclusion, all animals developed an airway inflammation characterized by neutrophil infiltration and a specific EB pattern that could be extracted after chlorine exposure. Monitoring EB samples can readily and non-invasively provide valuable information on biomarkers for diagnosis of chlorine-induced ALI as well as confirming chlorine exposures.

Rechargeable Aqueous Zinc-Halogen Batteries: Fundamental Mechanisms, Research Issues, and Future Perspectives

Aqueous zinc-halogen batteries (AZHBs) have emerged as promising candidates for energy storage applications due to their high security features and low cost. However, several challenges including natural subliming, sluggish reaction kinetics, and shuttle effect of halogens, as well as dendrite growth of the zinc (Zn) anode, have hindered their large-scale commercialization. In this review, first the fundamental mechanisms and scientific issues associated with AZHBs are summarized. Then the research issues and progresses related to the cathode, separator, anode, and electrolyte are discussed. Additionally, emerging research opportunities in this field is explored. Finally, ideas and prospects for the future development of AZHBs are presented. The objective of this review is to stimulate further exploration, foster the advancement of AZHBs, and contribute to the diversified development of electrochemical energy storage.

Evaluation of the Effectiveness of Aeration and Chlorination during Washing to Reduce E. coli O157:H7, Salmonella enterica, and L. innocua on Cucumbers and Bell Peppers

The attachment strength of bacteria to surfaces can affect the efficacy of sanitizers during washing. This study aimed to determine the effectiveness of chlorination and aeration in the removal of pathogens from the surface of produce. Cucumbers and bell peppers were inoculated with Listeria innocua, Escherichia coli O157:H7, or Salmonella enterica; afterwards, the produce was washed with or without chlorinated water (100 ppm) for 3 min in combination with or without aeration. Cucumbers washed with chlorinated water, with or without aeration, presented significant reductions of L. innocua (3.65 log CFU/cm2 and 1.13 log CFU/cm2, respectively) (p < 0.05). Similarly, bell peppers washed in chlorinated water with aeration (1.91 log CFU/g) and without aeration (2.49 log CFU/g) presented significant reductions of L. innocua. A significant reduction of L. innocua was observed on bell peppers washed with non-chlorinated water with aeration (2.49 log CFU/g) (p < 0.05). Non-chlorinated water was also effective in significantly reducing the level of Salmonella enterica (p < 0.05) on cucumbers and bell peppers. Washing with chlorinated water with aeration reduced Salmonella enterica levels from 4.45 log CFU/cm2 on cucumbers to below the detectable limit (0.16 log CFU/cm2). The highest reduction of Salmonella enterica from bell peppers occurred after washing with chlorinated water with aeration (2.48 log CFU/g). E. coli O157:H7, L. innocua, and Salmonella enterica levels present in non-chlorinated water after washing contaminated produce with or without aeration were significantly greater than those in chlorinated water (p < 0.05). After treatment, the population levels of all pathogens in chlorinated water with or without aeration were below the detectable limit for bell peppers (<1.10 log CFU/mL) and cucumbers (<1.20 log CFU/mL). Using chlorine in combination with forced aeration during washing minimizes cross-contamination of bacterial pathogens.

Rapid Inactivation of Fungal Spores in Drinking Water by Far-UVC Photolysis of Free Chlorine

Effective and affordable disinfection technology is one key to achieving Sustainable Development Goal 6. In this work, we develop a process by integrating Far-UVC irradiation at 222 nm with free chlorine (UV222/chlorine) for rapid inactivation of the chlorine-resistant and opportunistic Aspergillus niger spores in drinking water. The UV222/chlorine process achieves a 5.0-log inactivation of the A. niger spores at a chlorine dosage of 3.0 mg L-1 and a UV fluence of 30 mJ cm-2 in deionized water, tap water, and surface water. The inactivation rate constant of the spores by the UV222/chlorine process is 0.55 min-1, which is 4.6-fold, 5.5-fold, and 1.8-fold, respectively, higher than those of the UV222 alone, chlorination alone, and the conventional UV254/chlorine process under comparable conditions. The more efficient inactivation by the UV222/chlorine process is mainly attributed to the enhanced generation of reactive chlorine species (e.g., 6.7 × 10-15 M of Cl•) instead of hydroxyl radicals from UV222 photolysis of chlorine, which is verified through both experiments and a kinetic model. We further demonstrate that UV222 photolysis damages the membrane integrity and benefits the penetration of chlorine and radicals into cells for inactivation. The merits of the UV222/chlorine process over the UV254/chlorine process also include the more effective inhibition of the photoreactivation of the spores after disinfection and the lower formation of chlorinated disinfection byproducts and toxicity.

Improved Performance of Air-Processed Perovskite Solar Cells via the Combination of Chlorine Precursors and Potassium Thiocyanate

Due to their low cost and high efficiency, hybrid perovskite solar cells (PSCs) have shown the most outstanding competitiveness among third-generation photovoltaic (PV) devices. However, several challenges remain unresolved, among which the limited stability is arguably the main. Chlorine (Cl) has been widely employed to yield PV performances, but the Cl-doping mechanism and its role in mixed-halide PSCs are not entirely understood. Here, we investigate the effect of Cl-doping using different precursors such as formamidinium chloride (FACl), cesium chloride (CsCl), and lead chloride (PbCl2), which lead to the incorporation of Cl at different sites of the perovskite crystal. We demonstrate that the stability and efficiency of air-processed PSCs are strongly affected by Cl bonding into the cationic chloride precursor. Furthermore, adding potassium thiocyanate (KSCN) leads to the maximum efficiency of 18.1%, improving the operational stability with only 18% PCE loss after 520 h, stored under ambient conditions. Incorporating CsCl and KSCN presents an effective approach to further boost the performance and thermal stability of PSCs by tailoring the composition of the perovskite's composition. Finally, we used the slot-die method to demonstrate that our strategy is scalable for large-area devices that have shown similar performance. Our results show that fully air-processed and stable PSCs with high efficiency for large production and commercialization are achievable.

Ipso Substitution of Aromatic Bromine in Chlorinated Waters: Impacts on Trihalomethane Formation

Parabens and salicylates were examined as disinfection byproduct (DBP) precursors to explore the possible influence of ipso substitution (i.e., halogen exchange) on the yield and speciation of trihalomethanes (THMs) formed during water chlorination. Substoichiometric conversion of C-Br bonds into C-Cl bonds was confirmed for several parabens and salicylates. The co-occurrence of (mono)brominated and nonhalogenated precursors in the presence of free chlorine (but in the absence of added Br-) generated polybrominated THMs, implicating ipso substitution. The THM molar yield, bromine incorporation, and bromine recovery from brominated and nonhalogenated precursor mixtures were commensurate with those observed from equimolar additions of NaBr, indicating efficient displacement of aromatic bromine by free chlorine followed by reincorporation of liberated HOBr into DBP precursors. The THM molar yield from brominated precursors was enhanced by a factor of ≤20 relative to that from nonhalogenated precursors. Trends in THM molar yields and bromine incorporation differed between brominated parabens and brominated salicylates, suggesting that the influence of ipso substitution on THM formation varies with the structure of the organic precursor. Collectively, these results provide new evidence of the often-overlooked role ipso substitution can play in promoting halogen exchange and bromine enrichment among DBPs in chlorinated waters.

CuO Promotes the Formation of Halogenated Disinfection Byproducts during Chlorination via an Enhanced Oxidation Pathway

Previous studies showed that cupric oxide (CuO) can enhance the formation of trihalomethanes (THMs), haloacetic acids, and bromate during chlorination of bromide-containing waters. In this study, the impact of CuO on the formation kinetics and mechanisms of halogenated disinfection byproducts (DBPs) during chlorination was investigated. CuO does not enhance the formation of DBPs (i.e., 1,1,1-trichloropropanone, chloroform, and trichloroacetaldehyde (TCAL) /dichloroacetonitrile) during chlorination of acetone, 3-oxopentanedioic acid (3-OPA), and aspartic acid, respectively. This indicates that the halogen substitution pathway cannot be enhanced by CuO. Instead, CuO (0.1 g L-1) accelerates the second-order rate constants for reactions of chlorine (HOCl) with TCAL, citric acid, and oxalic acid at pH 8.0 and 21 °C from <0.1 to 29.4, 7.2, and 15.8 M-1 s-1, respectively. Oxidation pathway predominates based on the quantification of oxidation products (e.g., a trichloroacetic acid yield of ∼100% from TCAL) and kinetic modeling. CuO can enhance the formation of DBPs (e.g., THMs, haloacetaldehydes, and haloacetonitriles) during chlorination of model compounds and dissolved organic matter, of which both halogen substitution and oxidation pathways are required. Reaction rate constants of rate-limiting steps (e.g., citric acid to 3-OPA, aromatic ring cleavage) could be enhanced by CuO via an oxidation pathway since CuO-HOCl complex is more oxidative toward a range of substrates than HOCl in water. These findings provide novel insights into the DBP formation pathway in copper-containing distribution systems.

Bromine and Chlorine Disinfection of Cryptosporidium parvum Oocysts, Bacillus atrophaeus Spores, and MS2 Coliphage in Water

Conventional water treatment practices utilizing chemical disinfection, especially chlorination, are considered generally effective in producing microbiologically safe drinking water. However, protozoan pathogens such as oocysts of Cryptosporidium parvum are very resistant to chlorine, which has led to consideration of alternative disinfectants for their control. Free bromine, HOBr, has not been evaluated extensively as an alternative halogen disinfectant for inactivation of Cryptosporidium parvum in drinking water or reclaimed water for non-potable uses. Bromine is a versatile disinfectant consisting of different chemical forms with persistent microbicidal efficacy under varied water quality conditions and is effective against a range of waterborne microbes of health concern. The objectives of this study are to (1) compare the efficacy of free bromine to free chlorine at similar concentrations (as milligrams per liter) for disinfection of Cryptosporidium parvum oocysts, Bacillus atrophaeus spores, and MS2 coliphage in a model buffered water and (2) evaluate the kinetics of inactivation of these microorganisms using appropriate disinfection models. Overall, at a target concentration of ∼5 mg/L, bromine averaged 0.6 log (73.8%) reductions of C. parvum oocyst infectivity after 300 min (CT: 1166 min·mg/L) and produced up to a 0.8 log reduction disinfectant activity. An ∼5.0 mg/L chlorine dose increased oocyst infectivity by only 0.4 log (64%) after 300 min (CT: 895 min·mg/L). Bacillus atrophaeus spores and MS2 coliphage treated with bromine and chlorine were reduced by 4 log10 (99.99%) for both disinfectants over the duration of the experiments.

Formation Mechanisms of Nitro Products from Transformation of Aliphatic Amines by UV/Chlorine Treatment

Formation of nitrogenous disinfection byproducts from aliphatic amines is a widespread concern owing to the serious health risks associated with them. However, the mechanisms of transforming aliphatic amines and forming nitro products in the UV/chlorine process have rarely been discussed, which are investigated in this work. Initially, secondary amines (R1R2NH) are transformed into secondary organic chloramines (R1R2NCl) via chlorination. Subsequently, radicals, such as HO• and Cl•, are found to contribute predominantly to such transformations. The rate constants at which HO•, Cl•, and Cl2•- react with R1R2NCl are (2.4-5.1) × 109, (1.5-3.8) × 109, and (1.2-6.1) × 107 M-1 s-1, respectively. Consequently, R1R2NCl are transformed into primary amines (R1NH2/R2NH2) and chlorinated primary amines (R1NHCl/R2NHCl and R1NCl2/R2NCl2) by excess chlorine. Furthermore, primarily driven by UV photolysis, chlorinated primary amines can be transformed into nitroalkanes with conversion rates of ∼10%. Dissolved oxygen and free chlorine play crucial roles in forming nitroalkanes, and post-chlorination can further form chloronitroalkanes, such as trichloronitromethane (TCNM). Radicals are involved in forming TCNM in the UV/chlorine process. This study provides new insights into the mechanisms of transforming aliphatic amines and forming nitro products using the UV/chlorine process.

Li2 MnO3 : A Catalyst for a Liquid Cl2 Electrode in Low-Temperature Aqueous Batteries

Li2 MnO3 has been contemplated as a high-capacity cathode candidate for Li-ion batteries; however, it evolves oxygen during battery charging under ambient conditions, which hinders a reversible reaction. However, it is unclear if this irreversible process still holds under subambient conditions. Here, the low-temperature electrochemical properties of Li2 MnO3 in an aqueous LiCl electrolyte are evaluated and a reversible discharge capacity of 302 mAh g-1 at a potential of 1.0 V versus Ag/AgCl at -78 °C with good rate capability and stable cycling performance, in sharp contrast to the findings in a typical Li2 MnO3 cell cycled at room temperature, is observed. However, the results reveal that the capacity does not originate from the reversible oxygen oxidation in Li2 MnO3 but the reversible Cl2 (l)/Cl- (aq.) redox from the electrolyte. The results demonstrate the good catalytic properties of Li2 MnO3 to promote the Cl2 /Cl- redox at low temperatures.

Microbiological hazards associated with the use of water in the post-harvest handling and processing operations of fresh and frozen fruits, vegetables and herbs (ffFVHs). Part 1 (outbreak data analysis, literature review and stakeholder questionnaire)

The contamination of water used in post-harvest handling and processing operations of fresh and frozen fruit, vegetables and herbs (ffFVHs) is a global concern. The most relevant microbial hazards associated with this water are: Listeria monocytogenes, Salmonella spp., human pathogenic Escherichia coli and enteric viruses, which have been linked to multiple outbreaks associated with ffFVHs in the European Union (EU). Contamination (i.e. the accumulation of microbiological hazards) of the process water during post-harvest handling and processing operations is affected by several factors including: the type and contamination of the FVHs being processed, duration of the operation and transfer of microorganisms from the product to the water and vice versa, etc. For food business operators (FBOp), it is important to maintain the microbiological quality of the process water to assure the safety of ffFVHs. Good manufacturing practices (GMP) and good hygienic practices (GHP) related to a water management plan and the implementation of a water management system are critical to maintain the microbiological quality of the process water. Identified hygienic practices include technical maintenance of infrastructure, training of staff and cooling of post-harvest process water. Intervention strategies (e.g. use of water disinfection treatments and water replenishment) have been suggested to maintain the microbiological quality of process water. Chlorine-based disinfectants and peroxyacetic acid have been reported as common water disinfection treatments. However, given current practices in the EU, evidence of their efficacy under industrial conditions is only available for chlorine-based disinfectants. The use of water disinfection treatments must be undertaken following an appropriate water management strategy including validation, operational monitoring and verification. During operational monitoring, real-time information on process parameters related to the process and product, as well as the water and water disinfection treatment(s) are necessary. More specific guidance for FBOp on the validation, operational monitoring and verification is needed.

The Role of Chlorine in the Formation and Development of Tap Water Biofilms under Different Flow Regimes

Water companies make efforts to reduce the risk of microbial contamination in drinking water. A widely used strategy is to introduce chlorine into the drinking water distribution system (DWDS). A subtle potential risk is that non-lethal chlorine residuals may select for chlorine resistant species in the biofilms that reside in DWDS. Here, we quantify the thickness, density, and coverage of naturally occurring multi-species biofilms grown on slides in tap water with and without chlorine, using fluorescence microscopy. We then place the slides in an annular rotating reactor and expose them to fluid-wall shears, which are redolent of those on pipe walls in DWDS. We found that biofilms in chlorine experiment were thicker, denser and with higher coverage than in non-chlorine conditions under all flow regimes and during incubation. This suggests that the formation and development of biofilms was promoted by chlorine. Surprisingly, for both chlorinated and non-chlorinated conditions, biofilm thickness, density and coverage were all positively correlated with shear stress. More differences were detected in biofilms under the different flow regimes in non-chlorine than in chlorine experiments. This suggests a more robust biofilm under chlorine conditions. While this might imply less mobilization of biofilms in high shear events in pipe networks, it might also provide refuge from chlorine residuals for pathogens.

Dramatic Reduction of Silicon Surface Recombination by ALD TiOx Capping Layer from TiCl4 and H2O: The Role of Chlorine

Amorphous thin-film TiOx prepared via atomic layer deposition (ALD) has been identified as one of the most promising materials for use in transparent passivating contacts in high-efficiency and low-cost crystalline silicon (c-Si) solar cells. As highlighted in this work, the passivation performance of ALD TiOx layers strongly depends on the metal precursor used, with films prepared using TiCl4 recently showing the best results. However, a full understanding of how such films achieve their high level of surface passivation has not yet been demonstrated. This study provides a clear demonstration that a key part of this passivation mechanism is due to chlorine (Cl) accumulation at the Si surface. This mechanism is demonstrated to be quite general in nature by showing how 2 nm of ALD TiOx (TiCl4 + H2O) can be applied as a capping layer for either ZnO or Al2O3 interlayers to dramatically reduce silicon surface recombination. Cl depth profiles obtained using secondary ion mass spectrometry confirm the presence of Cl extending through the depth of the interlayers with a peak at the silicon interface. Remarkably, this diffusion of Cl is observed following low-temperature (75 °C) deposition of the TiOx capping layer, without any subsequent thermal treatment. Contrary to earlier studies that treated residual Cl in ALD films as a general contamination issue, these findings reveal unequivocally that chlorine plays a crucial role in Si surface passivation and can be classed as an effective passivation element, similar to hydrogen in its ability to passivate Si dangling bonds. The outcomes of this research emphasize the importance of residual chlorine in enhancing the passivation of buried interfaces and provide additional motivation for employing metal chloride precursors for silicon surface passivation applications.

The Virucidal Effect of the Chlorination of Water at the Initial Phase of Disinfection May Be Underestimated If Contact Time Calculations Are Used

For the microbiological safety of drinking water, disinfection methods are used to remove or inactivate microorganisms. Chlorine and chlorine dioxide are often used as disinfectants in drinking water treatment plants (DWTPs). We investigated the effectiveness of these chemicals in inactivate echovirus 30 (E30), simian 11 rotavirus (RV SA11), and human adenovirus type 2 (HAdV2) in purified water from a DWTP. Within two minutes of contact, chlorine dioxide inactivated E30 by 4-log10, RV SA11 by 3-log10, and HAdV2 could not be detected, while chlorine reduced E30 by 3-log10, RV SA11 by 2-3log10, and HAdV2 by 3-4log10. However, viral genomes could be detected for up to 2 h using qPCR. The CT method, based on a combination of disinfectant concentration and contact time, during such a short initial phase, is problematic. The high concentrations of disinfectant needed to neutralize organic matter may have a strong immediate effect on virus viability. This may lead to the underestimation of disinfection and overdosing of disinfectants in water with organic contamination. These results are useful for the selection of disinfection systems for reuse of treated wastewater and in the risk assessment of water treatment processes using chlorine and chlorine dioxide.

Multi-Scale X-ray Imaging of the Pigment Discoloration Processes Triggered by Chlorine Compounds in the Upper Basilica of Saint Francis of Assisi

In this paper, the chromatic alteration of various types of paints, present on mural painting fragments derived from the vaults of The Upper Basilica of Saint Francis of Assisi in Italy (12th-13th century), is studied using synchrotron radiation. Six painted mural fragments, several square centimeters in size, were available for analysis, originating from the ceiling paintings attributed to Cimabue and Giotto; they correspond to originally white, blue/green, and brown/yellow/orange areas showing discoloration. As well as collecting macroscopic X-ray fluorescence and diffraction maps from the entire fragments in the laboratory and at the SOLEIL synchrotron, corresponding paint cross-sections were also analyzed using microscopic X-ray fluorescence and powder diffraction mapping at the PETRA-III synchrotron. Numerous secondary products were observed on the painted surfaces, such as (a) copper tri-hydroxychloride in green/blue areas; (b) corderoite and calomel in vermillion red/cinnabar-rich paints; (c) plattnerite and/or scrutinyite assumed to be oxidation products of (hydro)cerussite (2PbCO3·Pb(OH)2) in the white areas, and (d) the calcium oxalates whewellite and weddellite. An extensive presence of chlorinated metal salts points to the central role of chlorine-containing compounds during the degradation of the 800-year-old paint, leading to, among other things, the formation of the rare mineral cumengeite (21PbCl2·20Cu(OH)2·6H2O).

Purified Chlorine Dioxide as an Alternative to Chlorine Disinfection to Minimize Chlorate Formation During Postharvest Produce Washing

The washwater used to wash produce within postharvest washing facilities frequently contains high chlorine concentrations to prevent pathogen cross-contamination. To address concerns regarding the formation and uptake of chlorate (ClO3-) into produce, this study evaluated whether switching to chlorine dioxide (ClO2) could reduce chlorate concentrations within the produce. Because ClO2 exhibits lower disinfectant demand than chlorine, substantially lower concentrations can be applied. However, ClO3- can form through several pathways, particularly by reactions between ClO2 and the chlorine used to generate ClO2 via reaction with chlorite (ClO2-) or chlorine that forms when ClO2 reacts with produce. This study demonstrates that purging ClO2 from the chlorine and ClO2- mixture used for its generation through a trap containing ClO2- can scavenge chlorine, substantially reducing ClO3- concentrations in ClO2 stock solutions. Addition of low concentrations of ammonia to the produce washwater further reduced ClO3- formation by binding the chlorine produced by ClO2 reactions with produce as inactive chloramines without scavenging ClO2. While chlorate concentrations in lettuce, kale, and broccoli exceeded regulatory guidelines during treatment with chlorine, ClO3- concentrations were below regulatory guidelines for each of these vegetables when treated with ClO2 together with these two purification measures. Switching to purified ClO2 also reduced the concentrations of lipid-bound oleic acid chlorohydrins and protein-bound chlorotyrosines, which are exemplars of halogenated byproducts formed from disinfectant reactions with biomolecules within produce.

Assessment of Residual Chlorine Interaction with Different Microelements in Stormwater Sediments

One consequence of intensive outdoor disinfection using chlorinated compounds is environmental pollution. It has been found that disinfectants are the most effective tool to avoid the spread of infections and viruses. Studies have shown that the use of chlorine-based disinfectants (sodium hypochlorite) leaves residual chlorine and other disinfection byproducts in the environment. They also have harmful effects on, inter alia, water quality, ecosystems, as well as exacerbating the corrosion of surfaces. To meet regulatory standards, monitoring of the presence of residual chlorine in the environment is vitally important. The aim of this study is to analyse the occurrence of residual chlorine in stormwater after outdoor disinfection using sodium hypochlorite and to investigate its interaction with different microelements as well their possible impacts. Stormwater samples collected at permanently disinfected locations were analysed via X-ray absorption spectroscopy. The concentrations of Cl and the following elements Na, Si, K, Ca, Cr, Fe, Ni, Cu, Zn were detected and their relationship with chlorine was determined using the Python programming language. The research presents Cl concentration values (%) that vary from 0.02 to 0.04. The results of the modelling revealed strong correlations between Cl and Fe (value 0.65) and Ca (value -0.61) and the occurrence of CaCl₂ and FeCl₃. The strong relationship between Cl and Fe explains the significant increase in surface corrosion after disinfection with chlorine-based substances.

Use of Essential Oil Emulsions to Control Escherichia coli O157:H7 in the Postharvest Washing of Lettuce

Essential oils (EOs) have strong antibacterial properties and can be potential sanitizers to reduce pathogen load and prevent cross-contamination during postharvest washing. The objective of this study was to investigate the efficacy of emulsions containing oregano (OR; Origanum vulgare) and winter savory (WS; Satureja montana) EOs at different concentrations (0.94 and 1.88 µL/mL) and storage times (0 h, 24 h, and 7 days), in reducing Escherichia coli O157:H7 on the surface of three types of lettuce (romaine, crisphead, and butterhead). The EO emulsions were compared with one no-rinse treatment and three rinse treatments using water, 200 ppm chlorine, and 80 ppm peroxyacetic acid (PAA), respectively, in a simulated washing system. The results showed that while the EO emulsions significantly reduced E. coli O157:H7 on crisphead lettuce over time, not all treatments were effective for romaine and butterhead lettuce. The mixture of OR and WS at concentrations of 0.94 and 1.88 µL/mL was found to be the most effective in reducing E. coli O157:H7 on inoculated lettuce, resulting in reductions of 3.52 and 3.41 log CFU/g, respectively. Furthermore, the PAA and the mixture of OR and WS at 1.88 µL/mL effectively limited bacterial cross-contamination close to the detection limit for all lettuce types during all storage times. These results suggest that OR and WS EOs could serve as potential alternatives to chemical sanitizers for postharvest lettuce washing.

Chlorate Levels in Dairy Products Produced and Consumed in Ireland

In recent years, chlorate has become a residue of concern internationally, due to the risk that it poses to thyroid gland function. However, little is known about its occurrence in dairy products of Irish origin. To address this, a study was conducted in which samples of milk (n = 317), cream (n = 199), butter (n = 178), cheese (n = 144) and yoghurt (n = 440) were collected from grocery stores in the Republic of Ireland. Sampling was conducted across spring, summer, autumn and winter of 2021. Samples from multiple manufacturers of each respective dairy product were procured and analysed for chlorate using UPLC-MS/MS. Chlorate was detected in milk, cream, natural, blueberry, strawberry and raspberry yoghurts. Mean chlorate levels detected in these products were 0.0088, 0.0057, 0.055, 0.067, 0.077 and 0.095 mg kg^-1, respectively. Chlorate was undetected in butter and cheese (<0.01 mg kg^-1). All products sampled, except yoghurt, were found to be compliant with the EU limit for chlorate in milk (0.10 mg kg^-1). Some manufacturers produced product with greater incidence and levels of chlorate. Chlorate levels from samples tested at different times of the year did not differ significantly, with the exception of strawberry and raspberry yoghurts which had higher chlorate levels in the winter period.

Sex-Based Disparities in Leukocyte Migration and Activation in Response to Inhalation Lung Injury: Role of SDF-1/CXCR4 Signaling

The aim of the study was to determine whether sex-related differences exist in immune response to inhalation lung injury. C57BL/6 mice were exposed to Cl2 gas (500 ppm for 15, 20, or 30 min). Results showed that male mice have higher rates of mortality and lung injury than females. The binding of the chemokine ligand C-X-C motif chemokine 12 (CXCL12), also called stromal-derived-factor-1 (SDF-1), to the C-X-C chemokine receptor type 4 (CXCR4) on lung cells promotes the migration of leukocytes from circulation to lungs. Therefore, the hypothesis was that elevated SDF-1/CXCR4 signaling mediates exaggerated immune response in males. Plasma, blood leukocytes, and lung cells were collected from mice post-Cl2 exposure. Plasma levels of SDF-1 and peripheral levels of CXCR4 in lung cells were higher in male vs. female mice post-Cl2 exposure. Myeloperoxidase (MPO) and elastase activity was significantly increased in leukocytes of male mice exposed to Cl2. Lung cells were then ex vivo treated with SDF-1 (100 ng/mL) in the presence or absence of the CXCR4 inhibitor, AMD3100 (100 nM). SDF-1 significantly increased migration, MPO, and elastase activity in cells obtained from male vs. female mice post-Cl2 exposure. AMD3100 attenuated these effects, suggesting that differential SDF-1/CXCR4 signaling may be responsible for sex-based disparities in the immune response to inhalation lung injury.

Predicting Sialic Acid Content of N-Linked Glycans Using the Isotopic Pattern of Chlorine

Sialic acids play several roles in both physiological and pathological processes; however, due to their labile nature, they are difficult to analyze using mass spectrometry. Previous work has shown that infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is able to detect intact sialylated N-linked glycans without the use of chemical derivatization. In this work, we describe a new rule that can predict the number of sialic acids on a glycan. Formalin-fixed paraffin-embedded human kidney tissue was prepared using previously established methods and analyzed using IR-MALDESI in negative-ion mode mass spectrometry. Using the experimental isotopic distribution of a detected glycan, we can predict the number of sialic acids on the glycan; #sialic acids is equal to the charge state minus the number of chlorine adducts, or z - #Cl^-. This new rule grants confident glycan annotations and compositions beyond accurate mass measurements, thereby further improving the capability of IR-MALDESI to study sialylated N-linked glycans within biological tissues.

Biotransformation of Flavonoids with -NO2, -CH3 Groups and -Br, -Cl Atoms by Entomopathogenic Filamentous Fungi

Combining chemical and microbiological methods using entomopathogenic filamentous fungi makes obtaining flavonoid glycosides possible. In the presented study, biotransformations were carried out in cultures of Beauveria bassiana KCH J1.5, Isaria fumosorosea KCH J2, and Isaria farinosa KCH J2.6 strains on six flavonoid compounds obtained in chemical synthesis. As a result of the biotransformation of 6-methyl-8-nitroflavanone using the strain I. fumosorosea KCH J2, two products were obtained: 6-methyl-8-nitro-2-phenylchromane 4-O-β-D-(4″-O-methyl)-glucopyranoside and 8-nitroflavan-4-ol 6-methylene-O-β-D-(4″-O-methyl)-glucopyranoside. 8-Bromo-6-chloroflavanone was transformed by this strain to 8-bromo-6-chloroflavan-4-ol 4'-O-β-D-(4″-O-methyl)-glucopyranoside. As a result of microbial transformation by I. farinosa KCH J2.6 effectively biotransformed only 8-bromo-6-chloroflavone into 8-bromo-6-chloroflavone 4'-O-β-D-(4″-O-methyl)-glucopyranoside. B. bassiana KCH J1.5 was able to transform 6-methyl-8-nitroflavone to 6-methyl-8-nitroflavone 4'-O-β-D-(4″-O-methyl)-glucopyranoside, and 3'-bromo-5'-chloro-2'-hydroxychalcone to 8-bromo-6-chloroflavanone 3'-O-β-D-(4″-O-methyl)-glucopyranoside. None of the filamentous fungi used transformed 2'-hydroxy-5'-methyl-3'-nitrochalcone effectively. Obtained flavonoid derivatives could be used to fight against antibiotic-resistant bacteria. To the best of our knowledge, all the substrates and products presented in this work are new compounds and are described for the first time.

Kinetic and Mechanistic Considerations of the Photosensitized Transformation of Chlorine in Chromophoric Dissolved Organic Matter Solutions under Simulated Solar Irradiation

Chlorination is one of the most common disinfection methods for water treatments. Although the direct photolysis of free available chlorine (FAC) induced by solar irradiation has been extensively investigated, the photosensitized transformation of FAC caused by chromophoric dissolved organic matter (CDOM) has not previously been examined. Our results suggest that the photosensitized transformation of FAC can occur in sunlit CDOM-enriched solutions. Interestingly, the photosensitized decay of FAC can be fitted using a combined zero- and first-order kinetic model. The photogenerated O₂^•- from CDOM contributes to the zero-order kinetic component. The reductive triplet CDOM (³CDOM*) contributes to the pseudo-first-order decay kinetic component. The bimolecular reaction rate constants of the model triplet (3-methoxyacetophenone) with HOCl and OCl^- were (3.6 ± 0.2) × 10⁹ and (2.7 ± 0.3) × 10⁹ M^-1 s^-1, respectively. Under simulated solar irradiation, the quantum yield coefficient of the reductive ³CDOM* toward FAC attenuation (f_FAC = 840 ± 40 M^-1) was 13 times greater than that of the oxidative ³CDOM* toward trimethylphenol (TMP) attenuation (f_TMP = 64 ± 4 M^-1). This study provides new insights into the photochemical transformation of FAC in sunlit surface waters, and the results are applicable when sunlight/FAC system is employed as an advanced oxidation process.

Chloride Applied via Fertilizer Affects Plant Nutrition and Coffee Quality

The present study had the objective to evaluate the effect of blends of KCl and K₂SO₄ fertilizers and their influence on the yield and the nutritional state of coffee plants, as well as on the chemical composition and quality of the coffee beverage. The experimental design was in randomized blocks with four repetitions and six treatments (T1: 100% KCl; T2: 75% KCl + 25% K₂SO₄; T3: 50% KCl + 50% K₂SO₄; T4: 25% KCl + 75% K₂SO₄; T5: 100% K₂SO₄; and a control, without application of K). The following analyses were performed: K and Cl content in the leaves and the soil, stocks of Cl in soil, yield, removal of K and Cl with the beans, cup quality of the beverage, polyphenol oxidase activity (PPO), electric conductivity (EC), potassium leaching (KL), the content of phenolic compounds, the content of total sugars (TS), and total titratable acidity (TTA). The stocks of Cl in the soil decreased as the proportion of KCl in the fertilizer was reduced. The fertilization with KCl reduces the cup quality and the activity of the polyphenol oxidase, probably due to the ion Cl. The increase in the application of Cl directly relates to the increase in potassium leaching, electric conductivity, and titratable acidity. Indirectly, these variables indicate damages to the cells by the use of Cl in the fertilizer. The activity of the polyphenol oxidase enzyme and the cup quality indicate that the ion Cl- reduces the quality of the coffee beverage. K content in the leaves was not influenced by the application of blends of K fertilizer while Cl content increased linearly with KCl applied. The application of KCl and K₂SO₄ blends influenced coffee yield and the optimum proportion was 25% of KCl and 75% of K₂SO₄. The highest score in the cup quality test was observed with 100% K₂SO₄.

Effect of Chlorine Substituents on the Photovoltaic Properties of Monocyanated Quinoxaline-Based D-A-Type Polymers

A string of monocyanated quinoxaline (Qx)-based D-A-type polymers systematically decorated with electron-attracting chlorine (Cl) atoms was created for use in non-fullerene polymer solar cells (PSCs). First, coupling of the benzodithiophene (BDT) donor and Qx acceptor with the strong electron-attracting cyano (CN) unit at its 5-position yielded the monocyanated reference polymer PB-CNQ. Subsequently, the additional Cl atoms were separately or simultaneously incorporated into the thiophene side groups of the BDT donor and Qx acceptor to create other objective polymers, PBCl-CNQ, PB-CNQCl, and PBCl-CNQCl. The Cl substituents on the BDT donor and Qx acceptor are represented by the names of the polymers. Owing to the favorable contributions of Cl substituents, the inverted-type non-fullerene PSCs based on partially chlorinated PBCl-CNQ (12.80%) and PB-CNQCl (13.93%) exhibited better power conversion efficiencies (PCEs) than the device based on unchlorinated reference PB-CNQ (11.19%). However, a significantly reduced PCE of 9.84% was observed for the device based on PBCl-CNQCl, in which Cl atoms were loaded on both the BDT donor and Qx acceptor at the same time. Hence, these results reveal that optimization of the number and position of Cl substituents in monocyanated Qx-based polymers is essential for enhancing their photovoltaic nature through the synergistic effects between two strong electron-attracting CN and Cl substituents.

Anthracite Releases Aromatic Carbons and Reacts with Chlorine to Form Disinfection Byproducts in Drinking Water Production

Anthracite is globally used as a filter material for water purification. Herein, it was found that up to 15 disinfection byproducts (DBPs) were formed in the chlorination of anthracite-filtered pure water, while the levels of DBPs were below the detection limit in the chlorination of zeolite-, quartz sand-, and porcelain sandstone-filtered pure water. In new-anthracite-filtered water, the levels of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ammonia nitrogen (NH₃-N) ranged from 266.3 to 305.4 μg/L, 37 to 61 μg/L, and 8.6 to 17.1 μg/L, respectively. In aged anthracite (collected from a filter at a DWTP after one year of operation) filtered water, the levels of the above substances ranged from 475.1 to 597.5 μg/L, 62.1 to 125.6 μg/L, and 14 to 28.9 μg/L, respectively. Anthracite would release dissolved substances into filtered water, and aged anthracite releases more substances than new anthracite. The released organics were partly (around 5%) composed by the μg/L level of toxic and carcinogenic aromatic carbons including pyridine, paraxylene, benzene, naphthalene, and phenanthrene, while over 95% of the released organics could not be identified. Organic carbon may be torn off from the carbon skeleton structure of anthracite due to hydrodynamic force in the water filtration process.

Design and In Situ Validation of Low-Cost and Easy to Apply Anti-Biofouling Techniques for Oceanographic Continuous Monitoring with Optical Instruments

Biofouling is the major factor that limits long-term monitoring studies with automated optical instruments. Protection of the sensing areas, surfaces, and structural housing of the sensors must be considered to deliver reliable data without the need for cleaning or maintenance. In this work, we present the design and field validation of different techniques for biofouling protection based on different housing materials, biocides, and transparent coatings. Six optical turbidity probes were built using polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), PLA with copper filament, ABS coated with PDMS, ABS coated with epoxy and ABS assembled with a system for in situ chlorine production. The probes were deployed in the sea for 48 days and their anti-biofouling efficiency was evaluated using the results of the field experiment, visual inspections, and calibration signal loss after the tests. The PLA and ABS were used as samplers without fouling protection. The probe with chlorine production outperformed the other techniques, providing reliable data during the in situ experiment. The copper probe had lower performance but still retarded the biological growth. The techniques based on transparent coatings, epoxy, and PDMS did not prevent biofilm formation and suffered mostly from micro-biofouling.

Observations from the Field Concerning the Use of 1 mEq/L Potassium Dialysate, Equipment Monitoring, Staffing, and Total Chlorine Testing

Patient safety and survey readiness should be top priorities for dialysis facilities. Hemodialysis is a complex process that redisposes staff and patients to possible errors and patient harm. Some observations seen by surveyors in dialysis facilities include an increased use in 1 mEq/L potassium dialysate, incomplete testing of hemodialysis machines, incorrect total chlorine testing, and staffing shortages. This article discusses the implications for the nephrology nurse in each of these situations.

Impact of drinking water treatment processes on the residues of plant protection products for consumer and aquatic risk assessment: theoretical and experimental studies

Pesticides residues can occur in ground and surface waters, and potentially react with chemicals used for water disinfection treatments, such as chlorine. This can lead to the formation of unknown reaction products, which can be more toxic and/or persistent than the active substances themselves, and therefore become a potential risk for human health and environment. Thus, in the framework of the EU Regulation 1107/2009, the identification of these by-products and their potential risk should be assessed. Within the European Food Risk Assessment (EU-FORA) Fellowship Programme, the fellow studied the behaviour of herbicides belonging to the families of imidazolinones and sulfonylureas in waters treated with chlorine disinfectants. Due to their physicochemical properties, these herbicides are susceptible of reaching natural waters. In fact, some of them have been detected in water monitoring programmes. During the experimental part of the present work programme, reactions between the active substances and the most used chlorine disinfecting reactants (hypochlorite and chloramines) were performed. Degradation kinetic parameters such as half-lives and degradation constants were calculated. Results showed that herbicide degradation was both pH and chlorine/chloramines concentration dependent. In order to identify the degradation by-products, high-resolution mass spectrometry experiments were performed, and a possible route of formation of these compounds was proposed. Finally, their risk assessment was carried out by using tox/ecotoxicological properties determined by QSAR methodology and FOCUS modelling for hazard and exposure assessment, respectively. These results will contribute to the definition of a risk assessment scheme for pesticides by-products potentially occurring in drinking water.

Solar Driven Gas Phase Advanced Oxidation Processes for Methane Removal - Challenges and Perspectives

Methane (CH₄ ) is a potent greenhouse gas and the second highest contributor to global warming. CH₄ emissions are still growing at an alarmingly high pace. To limit global warming to 1.5 °C, one of the most effective strategies is to reduce rapidly the CH₄ emissions by developing large-scale methane removal methods. The purpose of this perspective paper is threefold. (1) To highlight the technology gap dealing with low concentration CH₄ (at many emission sources and in the atmosphere). (2) To analyze the challenges and prospects of solar-driven gas phase advanced oxidation processes for CH₄ removal. And (3) to propose some ideas, which may help to develop solar-driven gas phase advanced oxidation processes and make them deployable at a climate significant scale.

Biochemical Basis of Selective Accumulation and Targeted Delivery of Photosensitizers to Tumor Tissues

The method of photodynamic therapy for treatment of malignant neoplasms is based on the selective of accumulation of photosensitizers in the tumor tissue. Insufficient selectivity of photosensitizers in relation to pathologically altered tissues and generalized distribution throughout the body leads to the development of severe toxic effects, including skin phototoxicity. The mechanisms underlying selectivity of photosensitizers for tumor tissue include selective binding to blood proteins and lipoproteins (considering that the number of receptors for those is increased on tumor cell membranes), uptake by macrophages, better solubility at low pH (acidic pH is characteristic of tumor cells), and other mechanisms. At present, increase in the efficiency of photodynamic therapy is largely associated with the additional targeting of photosensitizers to tumor tissues. Targeted delivery strategies are based on the differences in metabolism and gene expression profiles between the tumor and healthy cells. There are differences in expression of receptors, proteases, or transmembrane transporters in these cells. In particular, accelerated metabolism in many types of tumors leads to overexpression of receptors for epidermal growth factor, folic acid, transferrin, and a number of other compounds. This review considers biochemical basis for the selective accumulation of various classes of photosensitizers in tumors (chlorins, phthalocyanines, 5-aminolevulinic acid derivatives, etc.) and discusses various strategies of targeted delivery with emphasis on conjugation of photosensitizers with the receptor ligands overexpressed in tumor cells.

Evaluation of System-Level, Passive Chlorination in Gravity-Fed Piped Water Systems in Rural Nepal

Over 2 billion people globally lack access to safely managed drinking water. In contrast to the household-level, manually implemented treatment products that have been the dominant strategy for gaining low-cost access to safe drinking water, passive chlorination technologies have the potential to treat water and reduce reliance on individual behavior change. However, few studies exist that evaluate the performance and costs of these technologies over time, especially in small, rural systems. We conducted a nonrandomized evaluation of two passive chlorination technologies for system-level water treatment in six gravity-fed, piped water systems in small communities in the hilly region of western Nepal. We monitored water quality indicators upstream of the treatment, at shared taps, and at households, as well as user acceptability and maintenance costs, over 1 year. At baseline, over 80% of tap samples were contaminated with Escherichia coli. After 1 year of system-level chlorination, only 7% of those same taps had E. coli. However, 29% of household stored water was positive for E. coli. Per cubic meter of treated water, the cost of chlorine was 0.06-0.09 USD, similar to the cost of monitoring technology installations. Safe storage, service delivery models, and reliable supply chains are required, but passive chlorination technologies have the potential to radically improve how rural households gain access to safely managed water.

Evaluation of water-assisted UV-C light and its additive effect with peracetic acid for the inactivation of Listeria monocytogenes, Salmonella enterica and murine norovirus on whole and fresh-cut strawberries during shelf-life

BACKGROUND

The purpose of the present study was to examine the inactivation of Salmonella enterica (50 μL; 10⁹  CFU g^-1 ), Listeria monocytogenes (50 μL; 10⁹  CFU g^-1 ), and murine norovirus (MNV-1; 50 μL; 10⁷ 50% tissue culture infectious dose (TCID₅₀ ) mL^-1 ) on whole and fresh-cut strawberries after 2 min disinfection treatments (water (H₂ O), chlorine 200 mg L^-1 (NaClO), water-assisted ultraviolet-C (UV-C) (WUV), and the combination WUV and 40 mg L^-1 of PA (WUV + PA)) in a water tank (15 L) equipped with 4 UV-C lamps (17.2 W each), and after 7 days of cold storage (4 and 10 °C). For MNV-1, dry UV-C treatment (DUV) was also tested. For all UV-C treatments, an irradiation dose of 1.3 kJ m^-2 was used.

RESULTS

When strawberries were washed with WUV, L. monocytogenes and S. enterica were reduced by 2.8 and 2.2 log CFU g^-1 , respectively. The addition of 40 mg L^-1 of PA to WUV (WUV + PA) increased the reduction range of L. monocytogenes and S. enterica by 1.9 and 0.8 log, respectively. Regarding the wash water, no pathogens were recovered after the WUV + PA treatment (detection limit 50 CFU mL^-1 ). Depending on storage conditions (7 days at 4 or 10 °C), reductions observed were 0.5 to 2.0 log for S. enterica and 0.5 to 3.0 log for L. monocytogenes. The reductions in MNV-1 titer after disinfection treatments ranged from 1.3 to 1.7 log. No significant differences between storage conditions were observed for MNV-1: titers did not decline or were reduced up to 0.3 log after 7 days of cold storage.

CONCLUSION

The three-way action for disinfecting strawberries by UV-C irradiation and PA, plus the physical removal of the microorganisms by agitated water, are effective against foodborne pathogens on strawberries and water wash. During storage, WUV had a larger impact on the inactivation kinetics of S. enterica. Storage had little impact on MNV-1 inactivation. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The biogeochemical cycling of chlorine

Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from -1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth.

Chlorine Concentration Modelling and Supervision in Water Distribution Systems

The quality of the drinking water distributed through the networks has become the main concern of most operators. This work focuses on one of the most important variables of the drinking water distribution networks (WDN) that use disinfection, chlorine. This powerful disinfectant must be dosed carefully in order to reduce disinfection byproducts (DBPs). The literature demonstrates researchers' interest in modelling chlorine decay and using several different approaches. Nevertheless, the full-scale application of these models is far from being a reality in the supervision of water distribution networks. This paper combines the use of validated chlorine prediction models with an intensive study of a large amount of data and its influence on the model's parameters. These parameters are estimated and validated using data coming from the Supervisory Control and Data Acquisition (SCADA) software, a full-scale water distribution system, and using off-line analytics. The result is a powerful methodology for calibrating a chlorine decay model on-line which coherently evolves over time along with the significant variables that influence it.

Selective Ru Adsorption on SnO2/CeO2 Mixed Oxides for Efficient Destruction of Multicomponent Volatile Organic Compounds: From Laboratory to Practical Possibility

Ru-based catalysts have been extensively employed for the catalytic destruction of chlorinated volatile organic compounds (VOCs), but their versatility for other routine VOCs' destruction has been less explored. Herein, we show that Ru-decorated SnO₂/CeO₂ mixed oxides can sustain H₂O and HCl poisonings and are endowed with extraordinary versatility for a wide range of VOCs' destruction. Selective adsorption of Ru on the cassiterite SnO₂ and CeO₂ nanorods through a Coulomb force can rationally tune the oxidation and dechlorination centers on decorated catalysts, where the epitaxial growth of RuO_x on top of SnO₂ is endowed with excellent dechlorination ability and that on CeO₂ is functional as an oxidation center; the latter could also activate H₂O to provide sufficient H protons for HCl formation. Our developed Ru/SnO₂/CeO₂ catalyst can steadily destruct mono-chlorobenzene, ortho-dichlorobenzene, trichloroethylene, dichloromethane, epichlorohydrin, N-hexane, ethyl acetate, toluene, and their mixtures at an optimum temperature of 300 °C, and its monolithic form is also functional at this temperature with few dioxins being detected in the off-gas. Our results imply that the Ru-decorated SnO₂/CeO₂ catalyst can meet the demands of regenerative catalytic oxidation for the treatment of a wide range of VOCs from industrial exhausts.

New Halogen-Containing Drugs Approved by FDA in 2021: An Overview on Their Syntheses and Pharmaceutical Use

This review describes the recent Food and Drug Administration (FDA)-approved drugs (in the year 2021) containing at least one halogen atom (covalently bound). The structures proposed throughout this work are grouped according to their therapeutical use. Their synthesis is presented as well. The number of halogenated molecules that are reaching the market is regularly preserved, and 14 of the 50 molecules approved by the FDA in the last year contain halogens. This underlines the emergent role of halogens and, in particular, of fluorine and chlorine in the preparation of drugs for the treatment of several diseases such as viral infections, several types of cancer, cardiovascular disease, multiple sclerosis, migraine and inflammatory diseases such as vasculitis.

Clinical Features and Outcomes of Acute Chlorine Gas Inhalation; a Brief Report

Introduction

On March 6^th,2020, chlorine gas leak was reported at Engro Polymer & Chemicals Plant in Karachi City, Pakistan. This study aimed to evaluate the clinical features and outcomes of patients who presented to emergency department (ED) following this event.

Methods

This retrospective cross-sectional study, evaluated the clinical features and outcomes (length of hospital stay, complications, and mechanical ventilation requirement) of patients presenting to ED of Aga Khan University Hospital, Karachi, Pakistan, with history of chlorine gas exposure at the Engro Plant from 6^th March to 14^th March 2020.

Results

38 patients with mean age of 33.1 ± 8.1 years presented to ED with history of chlorine gas exposure (100% male). 4 (10.5%) cases had comorbid diseases. Most common presenting symptom was dyspnea, observed in 33 (86.8%) cases, followed by cough, seen in 27 (71.1%) subjects. 13.2% (5/38) patients had infiltration on chest x-ray and 33 (86.8 %) required hospitalization. 6 (15.8%) patients had repeat presentation requiring hospitalization or ED visit. 18 (47.4%) were managed with high flow oxygen therapy, 9 (23.7%) required non-invasive ventilation and one patient was intubated due to development of pneumo-mediastinum. Mean length of stay was 1.55 ± 1.58 days and no patients died. Presence of tachycardia was the only finding significantly associated with need for oxygen (p = 0.033) and non-invasive ventilation (p = 0.012).

Conclusion

The majority of patients presenting with acute chlorine gas exposure showed good clinical outcomes and rapid recovery, however, a high index of suspicion and vigilance should be maintained for complications such as pneumomediastinum and acute respiratory distress syndrome in these patients.

Formation of Oleic Acid Chlorohydrins in Vegetables during Postharvest Chlorine Disinfection

High chlorine doses (50-200 mg/L) are used in postharvest washing facilities to control foodborne pathogen outbreaks. However, chlorine can react with biopolymers (e.g., lipids) within the produce to form chlorinated byproducts that remain in the food. During chlorination of micelles of oleic acid, an 18-carbon alkene fatty acid, chlorine added rapidly across the double bond to form the two 9,10-chlorohydrin isomers at a 100% yield. The molar conversion of lipid-bound oleic acid to 9,10-chlorohydrins in chlorine-treated glyceryl trioleate and produce was much lower, reflecting the restricted access of chlorine to lipids. Yields from spinach treated with 100 mg/L chlorine at 7.5 °C for 2 min increased from 0.05% (0.9 nmol/g-spinach) for whole leaf spinach to 0.11% (2 nmol/g) when shredding increased chlorine access. Increasing temperature (21 °C) and chlorine contact time (15 min) increased yields from shredded spinach to 0.83% (22 nmol/g) at 100 mg/L chlorine and to 1.8% (53 nmol/g) for 200 mg/L chlorine. Oleic acid 9,10-chlorohydrin concentrations were 2.4-2.7 nmol/g for chlorine-treated (100 mg/L chlorine at 7.5 °C for 2 min) broccoli, carrots, and butterhead lettuce, but 0.5-1 nmol/g for cabbage, kale, and red leaf lettuce. Protein-bound chlorotyrosine formation was higher in the same vegetables (5-32 nmol/g). The Chinese hamster ovary cell chronic cytotoxicity LC₅₀ value for oleic acid 9,10-chlorohydrins was 0.106 mM. The cytotoxicity associated with the chlorohydrins and chlorotyrosines in low masses (9-52 g) of chlorine-washed vegetables would be comparable to that associated with trihalomethanes and haloacetic acids at levels of regulatory concern in drinking water.

Nutraceuticals in Bulk and Dosage Forms: Analysis by 35Cl and 14N Solid-State NMR and DFT Calculations

This study uses ³⁵Cl and ¹⁴N solid-state NMR (SSNMR) spectroscopy and dispersion-corrected plane-wave density functional theory (DFT) calculations for the structural characterization of chloride salts of nutraceuticals in their bulk and dosage forms. For eight nutraceuticals, we measure the ³⁵Cl EFG tensor parameters of the chloride ions and use plane-wave DFT calculations to elucidate relationships between NMR parameters and molecular-level structure, which provide rapid NMR crystallographic assessments of structural features. We employ both ³⁵Cl direct excitation and ¹H→³⁵Cl cross-polarization methods to characterize a dosage form containing α-d-glucosamine HCl, observe possible impurity and/or adulterant phases, and quantify the weight percent of the active ingredient. To complement this, we also investigate ¹⁴N SSNMR spectroscopy and DFT calculations to characterize nitrogen atoms in the nutraceuticals. This includes a discussion of targeted acquisition experimental protocols (i.e., acquiring a select region of the overall pattern that features key discontinuities) that allow ultrawideline spectra to be acquired rapidly, even for unreceptive samples (i.e., those with long values of T₁(¹⁴N), short values of T₂^eff(¹⁴N), or very broad patterns). It is hoped that these experimental and computational protocols will be useful for the characterization of various solid forms of nutraceuticals (i.e., salts, polymorphs, hydrates, solvates, cocrystals, amorphous solid dispersions, etc.), help detect impurity and counterfeit solid phases in dosage forms, and serve as a foundation for future NMR crystallographic studies of nutraceutical solid forms, including studies using ab initio crystal structure prediction algorithms.

Susceptibility of Dental Caries Microcosm Biofilms to Photodynamic Therapy Mediated by Fotoenticine

Photodynamic therapy (PDT) mediated by Fotoenticine^® (FTC), a new photosensitizer derived from chlorin e-6, has shown in vitro inhibitory activity against the cariogenic bacterium Streptococcus mutans. However, its antimicrobial effects must be investigated on biofilm models that represent the microbial complexity of caries. Thus, we evaluated the efficacy of FTC-mediated PDT on microcosm biofilms of dental caries. Decayed dentin samples were collected from different patients to form in vitro biofilms. Biofilms were treated with FTC associated with LED irradiation and analyzed by counting the colony forming units (log10 CFU) in selective and non-selective culture media. Furthermore, the biofilm structure and acid production by microorganisms were analyzed using microscopic and spectrophotometric analysis, respectively. The biofilms from different patients showed variations in microbial composition, being formed by streptococci, lactobacilli and yeasts. Altogether, PDT decreased up to 3.7 log10 CFU of total microorganisms, 2.8 log10 CFU of streptococci, 3.2 log10 CFU of lactobacilli and 3.2 log10 CFU of yeasts, and reached eradication of mutans streptococci. PDT was also capable of disaggregating the biofilms and reducing acid concentration in 1.1 to 1.9 mmol lactate/L. It was concluded that FTC was effective in PDT against the heterogeneous biofilms of dental caries.

Differential Regulation of the Asthmatic Phenotype by the Aryl Hydrocarbon Receptor

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates the metabolism of xenobiotics. There is growing evidence that the AhR is implicated in physiological processes such proliferation, differentiation, and immune responses. Recently, a role of the AhR in regulating allergic asthma has been suggested, but whether the AhR also regulates other type of asthma, particularly occupational/irritant-induced asthma, remains unknown. Using AhR-deficient (Ahr^−/−) mice, we compared the function of the AhR in the response to ovalbumin (OVA; allergic asthma) vs. chlorine (Cl₂; irritant-induced asthma) exposure. Lung inflammation and airway hyperresponsiveness were assessed 24h after exposure to Cl₂ or OVA challenge in Ahr^−/− and heterozygous (Ahr^+/−) mice. After OVA challenge, absence of AhR was associated with significantly enhanced eosinophilia and lymphocyte influx into the airways of Ahr^−/− mice. There were also increased levels of interleukin-4 (IL-4) and IL-5 in the airways. However, OVA-induced airway hyperresponsiveness was not affected. In the irritant-induced asthma model caused by exposure to Cl₂, the AhR did not regulate the inflammatory response. However, absence of AhR reduced Cl₂-induced airway hyperresponsiveness. Collectively, these results support a differential role for the AhR in regulating asthma outcomes in response to diverse etiological agents.

The Survival and Treatment of Fusarium oxysporum f. sp. cubense in Water

Fusarium oxysporum f. sp cubense (Foc), the causal agent of Fusarium wilt, is one of the most devastating constraints to banana production worldwide. The spread of Foc in water is particularly concerning, as infested water can rapidly contaminate disease-free areas. The objectives of this study were to investigate the survival of Foc in water and to test the effectiveness of water treatment with chlorine, ozone, UV, and peracetic acid. The study indicated that Foc spores can survive in water for more than 120 days, but that viability was reduced in stagnant water, probably due to anaerobic conditions when spores settled at the bottom. It is therefore recommended that surface water be extracted and treated before it is used for irrigation. The efficacy of all water treatments was reduced in the presence of soil, implying that water needs to be soil-free before treatment. The use of peracetic acid is recommended to treat Foc-contaminated water, as it is safe for use and does not require installation costs although it is effective at treating Foc-contaminated water, ozone would require significant input costs and chlorine can produce harmful disinfection by-products. UV would be impractical for field application because of the high doses required to eliminate Foc.

Mapping the Terrain for Pathogen Persistence and Proliferation in Non-potable Reuse Distribution Systems: Interactive Effects of Biofiltration, Disinfection, and Water Age

Diverse pathogens can potentially persist and proliferate in reclaimed water distribution systems (RWDSs). The goal of this study was to evaluate interactive effects of reclaimed water treatments and water age on persistence and proliferation of multiple fecal (e.g., Klebsiella, Enterobacter) and non-fecal (e.g., Legionella, mycobacteria) gene markers in RWDSs. Six laboratory-scale RWDSs were operated in parallel receiving the influent with or without biologically active carbon (BAC) filtration + chlorination, chloramination, or no disinfectant residual. After 3 years of operation, the RWDSs were subject to sacrificial sampling and shotgun metagenomic sequencing. We developed an in-house metagenome-derived pathogen quantification pipeline, validated by quantitative polymerase chain reaction and mock community analysis, to estimate changes in abundance of ∼30 genera containing waterborne pathogens. Microbial community composition in the RWDS bulk water, biofilm, and sediments was clearly shaped by BAC filtration, disinfectant conditions, and water age. Key commonalities were noted in the ecological niches occupied by fecal pathogen markers in the RWDSs, while non-fecal pathogen markers were more varied in their distribution. BAC-filtration + chlorine was found to most effectively control the widest range of target genera. However, filtration alone or chlorine secondary disinfection alone resulted in proliferation of some of these genera containing waterborne pathogens.

First Aid for Pool Chemical Exposure: A Narrative Review

Over 4500 visits to emergency departments related to pool chemical exposures occur annually in the United States, and it is likely that many more go unreported. Injury can occur due to sensitivity to standard chemical concentrations in pools (such as with opening one’s eyes underwater), accidental exposure to super-concentrated chemicals (such as malfunction of a pool chlorinator), or accidental inhalation of fumes while opening the storage container for chlorination tablets. Therefore, first aid care has the potential to significantly limit morbidity. 

A literature review was undertaken to determine the appropriate first aid for pool chemical exposures. This literature search revealed 25 pertinent articles, of which none were systematic reviews or studies directly related to the first aid treatment of pool chemical exposures. However, five articles were included as indirect evidence, and a hand search of references revealed five additional articles for inclusion. Treatment recommendations were extrapolated from the treatment of chemical exposures from other incidents.

Symptoms of pool chemical exposure reflect irritation secondary to the caustic chemicals involved. Patients may report irritation of the skin, eyes, nose, or throat; cough; chest tightness; and difficulty breathing. Following any exposure to pool chemicals, the victim should be removed from the source, taken to an area with fresh air, and contaminated materials (e.g. clothing, contact lenses) should be removed. Irrigation of the exposed area should take place immediately with uncontaminated fresh water for at least 15 minutes. It is anticipated that an exposed person will be symptomatically improved by leaving the area of exposure, removing their contaminated clothing items, and irrigating the contaminated body parts. However, if symptoms do not resolve during that time or if symptoms are worsening, the victim should be evaluated by trained medical personnel.