Search Results (10)

Pharmaceutical preclinical tests using cell cultures are nowadays commonly automated. Incubator microbial contaminations impact such tests. Chlorine dioxide (ClO₂) is widely used in aqueous solutions. However, a gaseous form, such as chlorine dioxide gas (gClO₂), can effectively access unreachable spaces, such as closed cell culture incubators. Steam sterilization requires a temperature rise to at least 121 °C, thus limiting the possibility of automation elements for sensors and actuators. gClO₂ sterilization is an ambient-temperature sterilization method. This article aims to demonstrate that gClO₂ generated from solid powder tablets is efficient for sterilizing incubators and can be automated. We selected (i) Bacillus subtilis strain, (ii) Saccharomyces cerevisiae, and (iii) T7 phages as representatives for (i) bacteria, (ii) fungi, and (iii) viruses for each domain to evaluate the sterilization efficiency. This study demonstrated that gClO₂ can be generated inside the incubator from a solid powder tablet without specific equipment and can effectively fight biological proxies in 15 min. After 30 sterilization cycles, the actuators and sensors mounted inside the incubator were still operating. Our proposed sterilization method seems to be generally applicable for automated in situ sterilization of incubators and medical robots. Full article

Combinations of metal disinfectants (i.e., silver and copper) with chlorine in doses that meet the World Health Organization guidelines for drinking water operate synergistically to provide superior drinking water disinfection across a wide range of pathogens. Moreover, the combination of disinfectants allows for lower chlorine levels and a less objectionable taste and odor to the treated water (some people can taste or smell chlorine at concentrations as low as 300 μg/L). Towards chlorine-releasing materials for combination with silver- or copper-releasing materials in point-of-use water disinfection, N-chloramine containing polymer gels were developed and their potential for E. coli bacteria inactivation was assessed in deionized water that contained salts to simulate groundwater. Following the chlorination of gels containing chloramine precursors, these gels capably inactivated E. coli, achieving log₁₀ reductions—depending on the gel mass—ranging from 1.1 to 4.5. While chlorine released from the gels was not spectroscopically detected, free chlorine solutions inactivated E. coli in a concentration-dependent way, with 5 and 20 μg/L Cl₂ yielding log₁₀ reductions of 0.43 and 1.69, respectively, suggesting that low levels of chlorine, below both the limit of detection of spectroscopic assays (ca. 40 μg/L Cl₂) and levels known to create adverse taste and smell, are sufficient to inactivate bacteria. Unchlorinated gels or chlorinated control styrene gels (without chloramine precursor) did not inactivate bacteria, suggesting that disinfection did not come from the precursor or from chlorine trapped in the gels after chlorination. In addition, these gels were evaluated together with the MadiDrop (MD, a commercial silver-ceramic tablet) and a copper screen that release silver and copper disinfectants, respectively. Combinations of the gel and MD produced E. coli inactivation close to 2-log₁₀ reduction, with the combination, gels alone, and MD alone achieving 1.86-, 1.10-, and 0.69-log₁₀ reduction, respectively. When the gels were combined with the copper screen, however, neither an increase nor a decrease in bacterial reduction was observed compared to that achieved with the gels alone. The laboratory results in this study are promising and suggest the potential for chloramine-functionalized gels to serve as an alternative to existing commercial chlorine-based POU technologies and in combination with silver-based POU technologies. Full article

Individuals living near cholera patients have an increased risk of cholera infections. Case-area targeted interventions (CATIs) promoting improved water, sanitation, and hygiene (WASH) present a promising approach to reducing cholera for those residing near cholera cases. However, there is limited evidence on the effectiveness and implementation of this approach in increasing WASH behaviors. We conducted a mixed-methods program evaluation in rural and urban eastern Democratic Republic of the Congo. The quantitative component included household structured observations and spot checks in CATI and control areas to assess WASH conditions and behaviors. The qualitative component included semi-structured interviews with CATI recipients, non-recipients, and implementers to assess CATI implementation. A total of 399 participants were enrolled in the quantitative evaluation conducted within 1 month of CATI delivery. For the qualitative evaluation, 41 semi-structured interviews were conducted, 30 with individuals in CATI areas (recipients and non-recipients) and 11 with CATI implementers. Handwashing with soap was low among both CATI and control area participants (1% vs. 2%, p = 0.89). Significantly more CATI area households (75%) had chlorine tablets present compared to control area households (0%) (p < 0.0001); however, the percentage of households with stored water free chlorine concentrations > 0.2 mg/L was low for both CATI and control area households (11% vs. 6%, p = 0.45). Implementers reported an insufficient supply of soap for distribution to recipients and mistrust in the community of their activities. CATI recipients demonstrated low knowledge of the correct preparation and use of chlorine for water treatment. Recipients also indicated a need for CATI implementers to engage community leaders. As CATIs are part of cholera control plans in many cholera-endemic countries, it is important to evaluate existing programs and develop evidence-based approaches to deliver CATIs that are both tailored to the local context and engage affected communities to increase WASH behaviors to reduce the spread of cholera. Full article

Two sorts of tablets were manufactured from ball-milled powder (aluminum scrap and copper) by cold pressing and spark plasma sintering. Their microstructure, phase, and elemental compositions were investigated via scanning electron microscopy, X-ray diffraction analysis, and energy-dispersive X-ray spectroscopy. New phases, Al₂Cu and MgCuAl₂, were detected in the samples. Their microstructure was formed by welded scrap particles, the intermetallides, and Cu-rich regions located majorly along ‘interparticle boundaries’ and, to a lesser extent, within small, micro- and nanosized ‘intraparticle spots’. The tablets were sealed with adhesive, so only the top surface was exposed to the environment, and tested in a chlorine aqueous solution for hydrogen generation performance. For both sample sorts, hydrogen yields of nearly 100% were achieved. The sintered tablets reacted faster than the cold-pressed ones: at 60, 70, and 80 °C, their entire ‘conversion into hydrogen’ took ~80, 40, and 30 min. vs. ~220, 100, and 70 min. The experimental kinetic curves were fitted with a contracting geometry equation, and those for the sintered samples were approximated with higher precision. The key effect of the additive was to enhance hydrogen evolution through the galvanic corrosion of Al in the regions adjacent to the intermetallic inclusions and Cu-rich spots. Full article

Compared to the general public, household members of cholera patients are at a 100 times higher risk of contracting cholera during the 7-day high-risk period after a cholera patient has been admitted to a health facility for treatment. The Preventative-Intervention-for-Cholera-for-7-days (PICHA7) program aims to reduce household transmission of cholera during this 7-day high-risk period through a health facility-initiated water, sanitation, and hygiene (WASH) program promoting handwashing with soap, water treatment, and safe water storage. The PICHA7 program is delivered to cholera patient households through: (1) a pictorial flipbook delivered by a health promoter; (2) a cholera prevention package (handwashing station, drinking water vessel with lid and tap, and chlorine tablets); and (3) weekly WASH mobile messages sent to patient households in the Democratic Republic of the Congo (DRC). The objectives of this study were to conduct formative research to identify facilitators and barriers of the promoted WASH behaviors for cholera patient households and to tailor the PICHA7 program to target these facilitators and barriers. Formative research included 93 semi-structured interviews with diarrhea patient households and healthcare workers during exploratory research and a pilot study of 518 participants. Barriers to the promoted WASH behaviors identified during exploratory and pilot study interviews included: (1) low awareness of cholera transmission and prevention; (2) unaffordability of soap for handwashing; and (3) intermittent access to water limiting water for handwashing. For intervention development, narratives of the lived experiences of patient households in our study were presented by health promoters to describe cholera transmission and prevention, and soapy water and ash were promoted in the program flipbook and mobile messages to address the affordability of soap for handwashing. A jerry can was provided to allow for additional water storage, and a tap with a slower flow rate was attached to the handwashing station to reduce the amount of water required for handwashing. The pilot findings indicate that the PICHA7 program has high user acceptability and is feasible to deliver to cholera patients that present at health facilities for treatment in our study setting. Formative research allowed for tailoring this targeted WASH program for cholera patient households in the DRC. Full article

Ultraviolet photolysis (UVC, 254 nm) was coupled with an electrochemical oxidation process to degrade three kinds of veterinary sulfonamide (sulfamethazine [SMZ] tablets, sulfamonomethoxine [SMM] tablets, and compound sulfamethoxazole [SMX] tablets). The treatment was applied using a flat ceramic microfiltration membrane to study the effects of photocatalysts. The effectiveness of degradation of the three sulfonamides was evaluated under different conditions. Dissolved oxygen was provided via aeration, but this resulted in a large decrease in the degradation effectiveness due to the inhibition of free chlorine electrogeneration. The photocatalysts had no promotional effect on sulfonamide removal from wastewater due to reduced UV penetration. Because of the different distribution coefficients of sulfonamides, UV irradiation had different effects on different sulfonamide species. For SMZ and SMM, anionic species exhibited a higher degradation rate, whereas for SMX, degradation was most effective for neutral species. In addition, the free chlorine yield increased as the pH increased. Free chlorine conversion reactions occurred under UV irradiation, with the reactions possibly restrained by sulfonamides. Reactive chlorine species promoted SMM degradation. Compared to UV irradiation or electrochemical oxidation alone, the UV/in-situ electrochemical oxidation process was more effective and is suitable for treating real wastewater under various environmental pH levels. Full article

Reusing greywater (GW) can lower domestic water consumption. However, the GW must be treated and disinfected for securing user health. This research studied at the laboratory scale, and in flow-through setups, which are generally used in full-scale GW treatment the disinfection efficiency of the two commonly used technologies (a) chlorination and (b) low-pressure UV irradiation. The disinfection methods were studied under a commonly found range of total suspended solids (TSS; 3.9–233 mg/L) and 5-d biochemical oxygen demand (BOD₅) concentrations (0–107 mg/L) as a representative/proxy of bioavailable organic matter. The negative effect of TSS began even at low concentrations (<20 mg/L) and increased consistently with increasing TSS concentrations across all the concentrations tested. On the other hand, the negative effect of BOD₅ on FC inactivation was observed only when its concentration was higher than 50 mg/L. Multiple linear regression models were developed following the laboratory results, establishing a correlation between FC inactivation by either chlorination or UV irradiation and initial FC, TSS, and BOD₅ concentrations. The models were validated against the results from the flow-through reactors and explained the majority of the variability in the measured FC inactivation. Conversion factors between the laboratory scales and the flow-through reactor experiments were established. These enable the prediction of the required residual chlorine concentration or the UV dose needed for an on-site flow-through reactor. This approach is valuable from both operational and research perspectives. Full article

Water chlorination is widely used in emergency responses to reduce diarrheal diseases, although communities with no prior exposure to chlorinated drinking water can have low acceptability. To better inform water treatment interventions, the study explored acceptability, barriers, and motivating-factors of a piped water chlorination program, and household level chlorine-tablet distribution, in place for four months in Rohingya refugee camps, Cox’s Bazar, Bangladesh. We collected data from June to August 2018 from four purposively selected refugee camps using structured observation, key-informant-interviews, transect-walks, group discussions, focus-group discussions, and in-depth-interviews with males, females, adolescent girls, and community leaders. Smell and taste of chlorinated water were commonly reported barriers among the population that had previously consumed groundwater. Poor quality source-water and suboptimal resultant treated-water, and long-queues for water collection were common complaints. Chlorine-tablet users reported inadequate and interrupted tablet supply, and inconsistent information delivered by different organisations caused confusion. Respondents reported fear of adverse-effects of "chemicals/medicine" used to treat water, especially fear of religious conversion. Water treatment options were reported as easy-to-use, and perceived health-benefits were motivating-factors. In vulnerable refugee communities, community and religious-leaders can formulate and deliver messages to address water taste and smell, instil trust, allay fears, and address rumours/misinformation to maximise early uptake. Full article

Metal phthalocyanines are well-known sensing phases with applications in different scientific fields due to their interesting properties. Detailed characterization by Raman spectroscopy was performed in order to study the shifting of the vibrational bands related to the coordination sphere of each metal phthalocyanine. In this work, a study involving the use of screen-printed electrodes (SPEs) with various metal phthalocyanines to electrochemically detect and quantify chlorine (Cl₂) gas is presented. The Cl₂ gas was generated in-situ via oxidation of the chloride present in form of aqueous salt solutions. The developed method offers not only the possibility to quantify chlorine, but also to discriminate among several chlorinated species due to the changes observed in the voltammetric profiles associated with the interaction between the specie assayed and the phthalocyanine metallic center. Optimization of detecting parameters was also performed to apply this procedure for the quantification of chlorine generated from commercial chlorine tablets. The development of this proof of concept shows interesting possibilities and easy-to-use applications with novel on metal phthalocyanines based SPE sensors. Full article

Chlorine tablets are commonly distributed for household water treatment in emergencies. However, confirmed use after distribution ranges widely (from 7–87%), which raises concerns about chlorine tablet effectiveness, as measured by acceptance and appropriate use. To investigate chlorine tablet effectiveness, we conducted nine key informant interviews (KIIs) on tablet distribution in emergencies in general, five KIIs on chlorine taste and odor acceptance and rejection specifically, and a literature review on chlorine taste and odor concerns. We found: (1) chlorine tablets are regarded as one of the most effective water treatment methods and are often considered appropriate in emergency response, (2) dosing confusion and taste and odor rejection are perceived as the main problems limiting effectiveness, and (3) the primary solutions suggested for these problems were social and behavioral. We recommend that social and behavioral scientists are routinely integrated into chlorine tablet programming to improve user feedback and behavioral interventions for chlorine tablet promotion in emergencies. We also suggest that more research is conducted on chlorine taste and odor rejection in vulnerable populations, and that improved guidance is developed to facilitate intra-agency coordination and select, promote, and monitor tablets appropriate for each context. Full article