Chlorine Content Research Articles

Persistence of Salmonella and Campylobacter on Whole Chicken Carcasses under the Different Chlorine Concentrations Used in the Chill Tank of Processing Plants in Sri Lanka.

The persistence of non-typhoidal Salmonella and Campylobacter in chicken meat is a considerable public health risk and a future challenge. This study aimed to determine the prevalence of Salmonella and Campylobacter in poultry processing lines where different chlorine concentrations were used in the chill tank. The samples were collected from four types of processing plants in Sri Lanka, considering the chlorine concentration used in the chill tank, which ranged from 2 ppm to 50 ppm. Salmonella and Campylobacter were isolated from whole carcass washings, neck skin, and cecal samples. Subsequently, an antimicrobial susceptibility test was performed for the isolates. The results revealed the overall prevalence of Salmonella and Campylobacter was 78.25% and 63.5%, respectively. Positive percentages of Salmonella and Campylobacter were high in the carcasses compared to the neck skin and ceca. The Campylobacter counts on the whole carcasses were significantly low (p < 0.001), at higher chlorine concentrations ranging from 20 to 30 ppm and 40 to 50 ppm. The pathogen prevalence in the whole carcasses was 84.7% Campylobacter coli, 39.1% Campylobacter jejuni, 71.1% Salmonella Typhimurium, and 28.8% Salmonella Infantis. The highest resistance was observed for tetracycline (63.8%) in Salmonella, while it was for gentamicin (87.8%) in Campylobacter. The prevalence percentage of multidrug-resistant Campylobacter was 51.2%, while it was 2.12% for Salmonella. The persistence of multidrug-resistant Salmonella and Campylobacter on the post-chill carcasses was highlighted in the present study as a significant public health threat that has to be addressed urgently.

Tunnel construction worker safety state prediction and management system based on AHP and anomaly detection algorithm model

Tunnels represent complex, high-risk, and technically demanding underground construction projects. The safety of construction workers in tunnels is influenced by various factors, including physiological indicators, tunnel dimensions, and internal environmental conditions. Analyzing safety based solely on static factors is inadequate for modern tunnel engineering safety management requirements. To address this challenge, this paper provides a comprehensive analysis of factors impacting safety and employs the Analytic Hierarchy Process (AHP) to identify seven significant factors with high importance: body temperature, heart rate, internal temperature, internal humidity, CO concentration, chlorine concentration, and the relative positioning of personnel. Considering these factors essential for assessing worker safety, we introduce a novel model named Tunnel-APH-AD. For training models aimed at anomaly detection, we performed data augmentation and utilized four distinct machine learning models. Additionally, ensemble learning techniques were applied to aggregate the predictions from individual models, thereby enhancing the effectiveness of detecting safety states for tunnel workers. We also evaluated the performance of these models on out-of-distribution (OOD) samples to test their robustness and generalizability. The experimental results indicate that, under similar ventilation and tunnel conditions, the ensemble learning model exhibits superior overall performance compared to individual models, underscoring the effectiveness of model combination in improving the accuracy and reliability of safety alerts. Through experimental validation, this study provides interpretable, scalable, and scientifically generalized applications of machine learning theories in systems for tunnel construction worker safety alerts. These findings contribute to advancing safety management practices in tunnel engineering, enabling proactive and effective measures to mitigate potential risks and ensure the well-being of workers.

Halide tuning in derivative organic–inorganic perovskites, MAPb(Br1-xClx)3 (x = 0–1): exploring structural, optical and vibrational characteristics

Organic–inorganic metal halide perovskites (OIMHP’s), particularly CH3NH3PbX3 (X = I, Br, Cl) and their derivatives shows favorable properties for energy harvesting such as high absorption coefficients, adjustable band gaps, and low charge recombination rate. The structure and hence nature of bonding between different atoms of these perovskites is known to affect their properties significantly. Tuning of band gap can be achieved in these systems with the help of compositional variation. These systems are studied extensively in the single halide compositions (MAPbI3, MAPbBr3 and MAPbCl3); while, their derivatives seem to have gained less attention though being important for various applications. So, in this work, halide tuning is achieved in derivative perovskite, MAPb(Br1-xClx)3 (x = 0 to 1) and further studied for structural and optical properties along with vibrational properties using X-ray diffraction (XRD), diffuse reflectance spectroscopy, and Raman spectroscopy techniques, respectively. A decrease in the lattice parameter is observed as the Chlorine content increases in the MAPb(Br1-xClx)3 (x = 0 to 1) perovskite. The substitution of Chlorine with Bromine also results in significant increase in the band gap value. In contrast to previous reports, it was clearly observed that the Urbach energy strongly depends on the composition. For the first time, appearance of two features for torsional mode of methylammonium (MA) is discussed even at room temperature, indicative of disorder. It is observed that although the band gap tuning is achieved with the help of halide mixing (Br and Cl), it is also found to introduce disorder in the intermediate compositions; while, the stability increases toward Chlorine compositions. Interestingly, the information of disorder is found to be contained in both the global as well as local measurements which opens up new pathways for studying these materials. This study will lay down a pathway for better understanding of key properties of these hybrid mix halide perovskites which are promising material for futuristic energy applications.

The effect of hypochlorous acid inhalation on the activity of antioxidant system enzymes in rats of different ages

Hypochlorous acid HOCl is an effective disinfectant with a broad spectrum and high rate of microbicidal action. Its use for air treatment can be an effective tool for the prevention and therapy of infectious diseases. In this work, the in vivo study was conducted on 110 Wistar Han rats (12 and 72 weeks old) on the effect of a single inhalation of air containing gaseous HOCl on the activity of antioxidant system enzymes. For this, a special installation was designed to uniformly maintain the concentration of HOCl in the air and regulate it over a wide range. Inhalation exposure was carried out for 4 h at total chlorine concentrations in the air of approximately 2.0 mg/m3 and 5.0 mg/m3, after which the animals were observed for 14 days. The effect of inhalation on the antioxidant system activity varied significantly in animals of different ages. Catalase activity in young rats increased approximately 2-fold on days 1-2 after inhalation, regardless of the HOCl concentration, while in old animals a sharp dose-dependent decrease was initially observed. The glutathione peroxidase activity in animals of both ages increased upon inhalation of air with 5.0 mg/m3 HOCl, and in old animals this was more pronounced; when the HOCl concentration decreased to 2.0 mg/m3, this indicator increased slightly in old rats and remained virtually unchanged in young ones. The glutathione reductase activity when exposed to 2.0 mg/m3 HOCl did not change for both age groups, and with increasing HOCl concentration it increased by 1.5-2.0 times in all animals.

Degradation of the protective layer on stainless steel by chlorine variation under high-temperature conditions

This study investigates the impact of various chlorine (Cl) content ratios on the degradation of 304 stainless steel during co-combustion of coal with solid recovered fuel (SRF) at a combustion temperature of 1250 °C. The research specifically focuses on the corrosion potential at 550 °C, which represents the temperature in the superheater area of a power plant. High-temperature corrosion experiments are conducted in a laboratory-scale drop tube furnace to observe initial corrosion during combustion. Analyses include visual examination, mineral analysis, microstructure-based metal analysis, and corrosion rate determination. The results show significant degradation at Cl contents higher than 0.09 wt%. The usual carbide formation at the grain boundaries in 304 stainless-steel does not occur in the short-term tests, as indicated by Cr content remaining above 12 % and Cl content less than 0.06 wt%. In addition, material degradation is due to the Cl reacting with alkali content, damaging the oxide layer and causing pits in the cross-section area of the probe material. This research provides insights into the critical role of Cl in metal degradation and identifies the optimum Cl amount suitable for coal blending in power plants.

A fuzzy rough-interval linear programming model for booster optimization in water distribution systems

In this article, a fuzzy rough-interval linear programming (FRILP) approach is proposed to deal with the uncertainty expressed by the fuzzy rough set in the optimization of booster cost under uncertainty. The FRILP model was applied to two cases to verify its effectiveness in booster optimization under uncertainty. The optimal upper and lower approximation intervals of the injection mass and booster cost in the fuzzy rough set were obtained and the effects of booster number and location were analysed. The results indicated that with an increase in booster number, the injection mass generally decreased, and booster cost decreased or increased. The nodal chlorine concentration also decreased and was distributed uniformly under a scenario with more boosters. Locating the booster far from the source resulted in more uniform chlorine distribution. The results could help managers design booster schemes with consideration of technical and economic factors comprehensively under uncertainty.

Changes in combined toxicity of benzophenone-3 and humic acid on Daphnia magna and zebrafish during chlorination disinfection process

Conventional wastewater treatment methods cannot completely remove the ultraviolet (UV) filters or dissolved organic matter. The transformation characteristics of these substances during chlorination disinfection and the varying species-specific toxicities of their combinations remain unclear. Here, Daphnia magna and zebrafish were exposed to benzophenone-3 (BP-3) and humic acid (HA) before and after chlorination disinfection. The results from chemical indicators showed that chlorination treatment decreased UV254 values and changed the intensity of parallel factors in three-dimensional fluorescence. Based on chemical analysis, the chlorine concentration and chlorination time for the toxicity experiments were set at 5 mg/L and 6 h, respectively. Exposure to HA and BP-3 before and after chlorination decreased the heart rate (by 1.37–28.12 %) in both species. However, species-specific responses, including survival rate, swimming distance, and expression of genes related to neurodevelopment, growth, and oxidative stress, were induced by chlorination. Chlorination reduced the impact of HA exposure but worsened the effects of HA and BP-3 co-exposure on D. magna. However, in zebrafish, the toxic effects intensified in most of the exposure groups after chlorination. Correlation analysis showed that the parallel factors of three-dimensional fluorescence were correlated with toxic effects on zebrafish, whereas UV254 was more significantly correlated with toxic effects on D. magna. This study provides insights into the combined toxicity of UV filters and dissolved organic matter in different aquatic organisms during chlorination, which is useful for risk control and optimization of the chlorination process.

Design and Construction and Energy Consumption Study of a New Electrolyzed Water Cell Generator Prototype for Food Disinfection

This study explores the feasibility of producing electrolyzed water (EW) for post-harvest treatment of fruits and vegetables as a new substitute for current chemical products. A prototype generator using tap water and NaCl solution was tested for EW’s sanitization efficiency, energy, and economic costs. In vitro tests on Penicillium e., Aspergillus n., Botrytis c., and Alternaria a. assessed EW pH, chlorine concentration, electro-oxidative potential, pathogen contact time, and energy consumption. Optimal results were achieved with a pH of 4.6, electro-oxidative potential of 188 mV, active chlorine concentration of 3.4 mg/L, and a contact time of 1–2 min. The prototype produced 10.0 L of EW in 1 h, consuming 0.11 kWh of electricity. Real-scale energy consumption was 545 kWh/m3 EW, costing 12.51 euro/m3. The study concludes that optimizing EW production can reduce energy consumption, making it a viable alternative for industrial sanitization of fruits and vegetables.

Highly efficient blue light-emitting diodes based on mixed-halide perovskites with reduced chlorine defects.

Perovskite light-emitting diodes (PeLEDs) provide excellent opportunities for low-cost, color-saturated, and large-area displays. However, the performance of blue PeLEDs lags far behind that of their green and red counterparts. Here, we show that the external quantum efficiencies (EQEs) of blue PeLEDs scale linearly with the photoluminescence quantum yields (PL QYs) of CsPb(BrxCl1-x)3 nanocrystals emitting at 460 to 480 nm. The recombination efficiency of carriers is highly sensitive to the chlorine content and the related deep-level defects in nanocrystals, causing notable EQE drops even with minor increases in chlorine defects. Minor adjustments of chlorine content through rubidium compensation on the A-site effectively suppress the formation of nonradiative defects, improving PL QYs while retaining desirable bandgaps for blue-emitting nanocrystals. Our PeLEDs with record-high efficiencies span the blue spectrum, achieving peak EQEs of 12.0% (460 nm), 16.7% (465 nm), 21.3% (470 nm), 24.3% (475 nm), and 26.4% (480 nm). This work exemplifies chlorine-defect control as a key design principle for high-efficiency blue PeLEDs.

Surviving chlorinated waters: bleaching sensitivity and persistence of free-living amoebae.

Recent advancements in membrane technologies and disinfection methods have enhanced drinking water quality significantly. However, microorganisms, including free-living amoebae (FLA), persist and pose potential threats to humans. FLA are linked to severe neuro-ophthalmic infections and serve as hosts of pathogenic bacteria. This study examined FLA presence in chlorinated and ultrafiltration drinking water and evaluated chlorine's disinfectant. Of 115 water samples, 21 tested positive for Acanthamoeba sp., Allovahlkampfia sp., and Vermamoeba vermiformis, originating from chlorinated sources. FLA trophozoites withstand temperatures up to 37°C, while the cysts tolerate heat shocks of 60-70°C. Trophozoites are susceptible to 5mg L-1 chlorine, but cysts remain viable at concentrations up to 10mg L-1. FLAs' survival in chlorinated waters is attributed to high cyst tolerance and lower residual chlorine concentrations. These findings highlight the need for ultrafiltration or enhanced chlorination protocols to ensure safer drinking water.

Influence of Feedstock Particle Size on the Certain Determination of Chlorine and Bromine in Pyrolysis Oils from Waste Electrical and Electronic Equipment Plastics.

Rejected streams emerging from waste sorting and recycling plants are still capable of being valorized by unconventional recycling routes. This is the case of the plastic-rich fraction generated after the treatment of waste electrical and electronic equipment (WEEE). However, the material complexity of this stream supposes a handicap when it comes to obtaining repetitive results in laboratory-scale recycling processes. This work aims to highlight the influence that the pretreatment (mainly particle size reduction) of a real WEEE plastic-rich stream has on the variability of the concentration of halogens (representative pollutants) in the oils obtained from its recycling via pyrolysis. The pretreatment steps were based on the standards of the European Committee for Standardization (ECN) for the analysis of waste samples. Four samples were studied: the WEEE plastics as received; two milled samples (2 and 1 mm particle size) derived from the original one; and a simulated sample composed of virgin polymers. All the samples were treated under the same conditions: 500 °C reaction temperature, 15 °C min-1 heating rate, 30 min dwell time, and a 1 L min-1 nitrogen purge flow. The oils obtained in, at least, two pyrolysis tests performed on the same sample were deeply characterized, and the results were compared. The oils derived from the "as-received" sample showed an unacceptable relative standard deviation (RSD, ∼42%) in the chlorine concentration. The sample milled to 2 mm reduced the RSD on the concentration of chlorine in the oils down to 8%, while no enhancement in the results was observed for the further milled sample. The other two major pyrolysis fractions were also characterized, showing an overall enhancement in the RSD of the analysis of the main components of the gases, while no improvement in the solids pollutants' characterization was achieved.

Oxygen Measurement in Cuprate Superconductors Using the Dissolved Oxygen/Chlorine Method

We have developed a dissolved oxygen (DO) method with differential equation (DE) correction. We measured the oxygen content in La-based and Y-based superconductors, and succeeded in measuring the oxygen content simply in one-third of the time required by the iodometric titration method. However, there was a problem with Bi-based superconductors where the measured oxygen content was smaller compared to the iodometric titration method. We hypothesized that not only O2 but also Cl2 gas is generated when dissolving Bi-based superconductors and developed a dissolved oxygen/chlorine (DO/Cl) method with DE correction. This method uses only a dissolved oxygen sensor and a dissolved chlorine sensor to measure the dissolved oxygen and dissolved chlorine content in Bi2Sr2−xLaxCuOy, allowing for the calculation of copper valence and oxygen content. The results from the DO/Cl method with DE correction show that the measured copper valence and oxygen content differ very little from those obtained using the iodometric titration method, with discrepancies within 0.016 and 0.008, respectively. Additionally, this method reduces the measurement time by one-third compared to the iodometric titration method. The results demonstrate that the DO/Cl method with DE correction can effectively measure the copper valence and oxygen content in cuprate superconductors, and using hydrochloric acid as the experimental solution is superior to sulfuric acid and nitric acid.

Influence of Lateral Length and Residual Chlorine Concentration on Soil Nitrogen and Soil Enzyme Activities under Drip Irrigation with Secondary Sewage Effluent

Chlorination has been demonstrated to be an effective method for the prevention and reduction in emitter biological blockage in drip irrigation systems. The injected chlorine dose is generally determined by chlorine concentration at the terminal of the laterals which may lead to a high concentration of residual chlorine at the front of the system and bring detrimental impact to the soil environment and growth of crops, especially in large irrigation units with long laterals. A two-season experiment was undertaken to determine the effects of chlorine disinfection and lateral length on soil NO3-N, enzyme activities, and maize yield under wastewater drip irrigation. The experiments were constructed with lateral lengths ranging from 20 to 80 m and injection chlorine concentrations at the end of laterals ranging from 2 to 6 mg L−1. Lateral length had a major impact on enzyme activities in the partial growth stage, although the effects of lateral length and chlorine concentration on soil nitrogen content and maize yield were negligible. Enzyme activity and soil nitrogen concentration decreased throughout the lateral length as a result of chlorination. A higher detrimental impact on soil characteristics and maize yield is probably going to result from a high concentration of chlorine and a long lateral length mode. The maize yield peaked at L80 with a concentration of 2 mg L−1 chlorine, while it peaked at L40 with 6 mg L−1 chlorine concentration. A chlorination scheme with long lateral length and low chlorine concentration is recommended in consideration of maize yield and minimizing potential negative effects on the soil environment.

Hydration of mafic crustal rocks at high temperature during brittle‐viscous deformation along a strike‐slip plate boundary

AbstractThe Poroshiri ophiolite (Hidaka metamorphic belt, Japan) occurs within a crustal‐scale network of high‐temperature, dextral shear zones that accommodated hundreds of kilometres of displacement due to the opening of the Japan Sea in the Neogene. The opholitic rocks comprise ultramafic, mafic and sedimentary protoliths that have been variably hydrated and metamorphosed. This work investigates the mechanisms and timing of fluid influx relative to viscous deformation in metagabbros and amphibolites deformed during exhumation from granulite‐ to amphibolite‐facies conditions. We consider a range of microstructures, from low strain domains and 1–2 mm thick shear bands to mylonites with a thickness of a few meters. Low strain domains of metagabbros exhibit corona textures with symplectites consisting of pargasitic amphibole (Ed0.7) ‐ anorthitic plagioclase (An80–92) ± orthopyroxene ± clinopyroxene forming around olivine and igneous pyroxene and with similar plagioclase–amphibole‐orthopyroxene ± clinopyroxene granoblastic aggregates in micrometric‐thick fractures. These textures result from hydration under low fluid‐rock ratio, with elevated H2O content only occurring locally (H2O &gt; 1–1.2 wt%). Igneous mineral replacement leads to grain size reduction from 1 mm to ~10 μm. Amphibole exhibits a strong core‐rim zonation primarily controlled by the high diffusivity of Fe, Mg and OH and the low diffusivity of Al. Mineral compositional equilibrium is achieved at the scale of 100–200 μm. In mm‐thick localized shear bands and in metric‐scale mylonitic amphibolites, the heterogeneous mineral composition of amphibole (Ed0.2–0.5) and plagioclase (An40−An80) indicates only partial re‐equilibration (at the scale of 200–500 μm) despite higher fluid‐rock ratios and more pervasive fluid percolation than in metagabbros. Plagioclase–amphibole thermometry and equilibrium phase diagrams indicate that the initial fluid infiltration and corona formation occurred at 800–850°C by fracturing and percolation along grain boundaries. This was followed by the main fluid percolation and mylonitization event, which occurred during exhumation and cooling at conditions of 720–580°C, ~4 kbar. Continuous hydration during retrogression was achieved by the influx of dominantly seawater‐derived fluid, as attested by the high chlorine (Cl) contents (&gt;300–400 ppm) of amphiboles in fractures. The heterogeneous distribution of fractures controls the distribution of fluid from the earliest stages of hydration, creating positive feedback where the growth of hydrous minerals as amphibole (up to +300 vol% of amphibole in high strain areas relative to the low‐strain ones) and the formation of fine‐grained mixed domains that led to further localization of viscous strain and mass transfer (variations of ± 30–40% in major elements). The Poroshiri ophiolite therefore represents a good fossil example of a former transpressional plate boundary where coupled metamorphic and deformation processes were triggered by seawater‐derived fluid that percolated to depths of ~15 km.

Hydrothermal dechlorination strategy for high-quality oil recovery from polyvinyl chloride

The global production of PVC is around 3.5 million tons each year. Unfortunately, the disposal of PVC waste releases toxic substances such as hydrochloric acid, polychlorinated dioxins, and furans, which can harm the environment. Therefore, there is an urgent need for a safe and environmentally friendly thermochemical treatment method that reduces the damage caused by HCl gas produced during PVC pyrolysis and improves the quality of pyrolysis oil. Hydrothermal treatment technology is one of the potential dechlorination strategies for PVC. However, its efficiency is reduced in the supercritical region, while the additives used result in secondary pollution and increased operating costs. This study is pioneering in its approach, aiming to produce high-quality oil with reduced chlorine through low-temperature hydrothermal treatment of PVC, all without additives. The results are promising, indicating that by administering steam at 250 °C with a 2.0–3.0 g-steam/g-feed ratio, we can significantly reduce chlorine content to 0.13 % while achieving an oil yield of up to 14.9 % from PVC. The hydrothermal process can reduce CO2 emissions by 15–43 % compared to pyrolysis methods, providing a simultaneous opportunity for carbon neutrality and resource recovery.

Failure analysis and preventative measures on cracking of tube-to-tubesheet joints of the large-scale heat exchanger

A large-scale heat exchanger in an EO/EG plant suffered a severe leakage failure after 3 years of service, and numerous fractures and cracks were found in the tube-to-tubesheet joints. A series of failure investigations, including macroscopic and microscopic inspection, physicochemical analysis, metallographic examination, and stress analysis, have been used to clarify the causes of cracking of tube-to-tubesheet joints. The macroscopic inspection revealed that the cracking of the joints occurred on the tube inlet side, and the fracture exhibited circumferential cracking. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) presented that the fracture is a mixture of transgranular and intergranular cracking (predominantly intergranular), and the surface of the fracture is covered by corrosion products with chlorine, oxygen, and copper content. Furthermore, the stress analysis concluded that the joints were subjected to residual stresses, tensile stresses, and thermal stresses. Therefore, the cracking of the tube-to-tubesheet joints was caused by stress corrosion cracking (SCC), which originated from crevice corrosion and intergranular corrosion. Then, the corrosion mechanism involved in this failure was discussed in detail, and corresponding preventive measures were proposed. Achievements in this paper may supplement the failure database of tube-to-tubesheet joints in large-scale heat exchangers and reduce similar failures through engineering practices.

ANALYSIS OF THE EFFICIENCY OF TRADITIONAL TECHNOLOGIES OF WATER PREPARATION OF THE KREMENCHUK RESERVOIR OF THE DNIPRO RIVER TO ENSURE DRINKING NEEDS

An analysis of the efficiency of the surface water treatment systems of the Dnipro reservoirs when their quality is changed to ensure the normative indicators of the quality of drinking water were carried out. The study of the effectiveness of traditional water treatment technologies was carried out by analyzing the results of laboratory studies of source and drinking water at the Dnipro water treatment plant with water intake from the Kremenchuk Reservoir (data from the Svitlovodsk Water and Sewage Services (SWS) of the Regional Municipal Production Enterprise (RMPE) of the Dnipro-Kirovograd), establishing correlations of quality indicators and assessing the state of water resources by the requirements of water legislation. The treatment plants of the Dnipro water supply station are not designed to treat water with a high content of biogenic substances during active phytoplankton vegetation, and under such conditions, increased doses of preliminary chlorination are used. As a result, water is polluted with residual chlorine and organochlorine. An increase in the dose of aluminum-containing coagulants in the corresponding period leads to an increase in the aluminum content in drinking water to the limit of the normative value (0,5 mg/dm3). According to the results of research in drinking water, turbidity was found to be 1,4 higher and permanganate oxidizability 1,3 higher than the standard content; excesses of color, iron, and residual chlorine content were found only sporadically and were on average within the upper limits of normative values. Correlation analysis (Pearson and Spearman correlations methods) of the influence of temperature on the following hydrometric, chemical, and physical factors was carried out: changes in turbidity, color, and changes in the concentration of total iron and ammonia. The analysis confirmed the visual connection of oxygen with temperature and water level and the influence of factors on oxygen concentration. The practical aspects of phytoplankton extraction during water intake from Dnipro reservoirs and water treatment at stations have gained further scientific justification.

Selectively Isolation and Molecular Identification by dnaJ Gene of Legionella pneumophila Found in Various Water Sources in Dhaka, Bangladesh

Abstract BACKGROUND: Legionella spp. are the etiological agents of Legionnaires’ disease, often severe pneumonia. After the first severe outbreak of Legionella spp., it was found widely dispersed in natural water sources and humid environments and has become a concern for these sources’ water quality and safety. The fecal indicators used for water quality assessment do not predict the presence of these pathogens; thus, in the absence of targeted analysis, the risk is unobserved until the emergence of infections. There is no study on the presence of Legionella in unattended water bodies in Bangladesh, such as swimming pools, air-conditioned cooling water, and stagnant circulatory water systems. METHODS: A total of 42 water samples were collected from 12 different sites in Dhaka, Bangladesh. Acid, heat, and chlorine treatment were applied to reduce the load of non-Legionellae in water samples. Chlorine treatment was used to kill unwanted organisms in water samples. After successful pretreatment, samples were cultured on buffered charcoal yeast extract agar (BCYE) media. Optimum pH, concentrations of chlorine, and temperature were set up by extensive trial and error culturing of Legionella on BCYE media to minimize other bacterial growth and maximize Legionella growth. Isolated colonies were confirmed primarily by morphological characteristics on BCYE media. Isolates were then confirmed by polymerase chain reaction and gel electrophoresis techniques. We detected the presence of 16S rDNA for Legionella spp. and the dnaJ gene for Legionella pneumophila species identification. Antibiotic sensitivity tests (minimum inhibitory concentration) were also conducted to see if it was alarming for our community’s health. RESULTS: Most of the Legionella spp. could grow at various temperatures, such as 45°C, 50°C, and 55°C, and they could also survive at the normal levels of chlorination, such as 0.25 mg/L and 0.5 mg/L. We have found that, out of 12 different sites, 4 out of 5 (80%) isolates from cooling tower water, 1 out of 4 (25%) from the swimming pool, and 1 out of 3 (33%) household stagnant water are contaminated with Legionella. However, 3 out of 5 isolates found are L. pneumophila from cooling water sites. Furthermore, strains of Legionella spp. were resistant to many antibiotics, such as ciprofloxacin, azithromycin, and tetracycline. CONCLUSIONS: Serious and fatal Legionella spp. (L. pneumophila) infections may be transmitted because of the widespread presence of these water sources and the large number of users in the community. This threat is worsened by the survival of Legionella under various commonly used antibiotic conditions and further exacerbated by their antibiotic resistance. Health-care professionals may face great challenges due to the lack of studies about its prevalence and treatment procedures.

DETERMINATION OF THE FEATURES OF THERMAL DECOMPOSITION OF SUNFLOWER HUSK IN A FLUIDIZED BED

Sunflower husk (SH) is a plant waste fuel. The carbon content in different samples of SH ranges from 40.5% to 54.5% in an operating state, with ash content ranging from 1.5% to 8.5%, moisture content ranging from 6.9% to 9.5%, chlorine content ranging from 0.05% to 0.3%, and lower heating value ranging from 14.5 MJ/kg to 20.5 MJ/kg. These characteristics make it a suitable substitute for fossil fuels in power boilers. Waste-to-energy (WTE) technologies are rapidly developing worldwide, offering the potential for generating renewable energy from waste, including agricultural and food industry waste such as SH. According to our estimates, Ukraine has an annual energy potential of approximately 3.4 million tons of SH or about two million tons of fuel equivalent. Approximately half of this volume is currently being burned in oil extraction plants' boilers; however, up to one million tons of SH end up in landfills annually, resulting in significant energy losses. To develop new and improve existing WTE technologies that utilize SH as a fuel source, it's essential to understand the thermal processing characteristics of SH under conditions similar to those found in different zones within real power boilers - specifically the heating of fuel particles at rates up to 500 °C/s over a temperature range of 500–1000 °C. In this study, we aimed to investigate the thermal processing characteristics by subjecting SH particles within a laboratory fluidized bed reactor to high-speed heating within the aforementioned temperature range. During rapid heating between 500–1000 °C temperatures range, SH particles undergo conversion into volatile compounds and solid carbon residue. Two distinct stages can be observed on the dynamic yield curves for volatiles. The release and burnout of volatiles occurs during the first stage while the second stage involves coke ash residue burnout. We obtained empirical temperature-dependents for total heat treatment time and carbon residue burnout time under fast heating conditions in the investigated temperature range. The stage of carbon residue combustion is the most enduring and determines the overall duration of thermal treatment. This stage determines the degree of fuel transformation, especially in cases where low-reactivity carbon residue enters the low-temperature combustion chamber area of the boiler. The obtained regularities have practical significance in designing combustion chambers for thermal processing of sunflower husk.

Fabrication of multifunctional cotton fabrics with quaternized N-halamine endowing the synergetic rechargeable antibacterial, wound healing and self-cleaning performances

Cotton has attracted considerable attention due to its functional characteristics. The focus of research on cotton has shifted in recent years towards designing multi-functional and modified media for cotton fibers, which can be firmly combined with textiles, giving them reusability and extending their service life. This study constructed a synergistic antibacterial layer of quaternary ammonium compounds (QACs) and N-halamine (Hals) using an in-situ free radical copolymerization method in water, named QACs/Hals@cotton-Cl. The route significantly increases the number of antibacterial active centers. FTIR, XPS, and SEM were used to systematically analyze the product's chemical structure, surface morphology, and other characteristics. The modified fabric's antibacterial efficiency, wound healing, renewability, and durability were also evaluated. The chlorinated modified cotton fabric could completely eradicate S. aureus and E. coli within 10 min. Compared with pure cotton, it notably promoted the healing rate of infected wounds in mice. The modification method imparted excellent hydrophobicity to the cotton fabric, with a contact angle exceeding 130°, making it easy to remove surface stains. After 30 days of regular storage and 24 h of UV irradiation, the active chlorine concentration (Cl+%) only decreased by 25 % and 39 %, respectively, and the reduced Cl+% was effectively recharged via simple re-chlorination. The hydrophobicity and antimicrobial properties of QACs/Hals@cotton-Cl remained stable even after 20 cycles of friction. This simple synthesis technique provides a convenient approach for the scalable fabrication of multifunctional and rechargeable antibacterial textiles, with potential applications in medical devices and personal hygiene protection.