Assessment of color changes and adverse effects of over-the-counter bleaching protocols: a systematic review and network meta-analysis.

OBJECTIVES: To assess color change efficacy and the adverse effects of varied over-the-counter (OTC) bleaching protocols. METHODOLOGY: The study included randomized clinical trials evaluating color changes from OTC bleaching agents. Nine databases were searched, including the partial capture of the grey literature. The RoB2 tool analyzed the individual risk of bias in the studies. Frequentist network meta-analyses compared treatments through common comparators (∆Eab* and ∆SGU color changes, and tooth sensitivity), integrating direct and indirect estimates and using the mean and risk differences as effect measures with respective 95% confidence intervals. The GRADE approach assessed the certainty of the evidence. RESULTS: Overall, 37 remaining studies constituted the qualitative analysis, and ten composed the meta-analyses. The total sample included 1,932 individuals. ∆Eab* was significantly higher in groups 6% hydrogen peroxide (HP) strips (≥ 14 h). ∆SGU was significantly higher in groups at-home 10% carbamide peroxide (CP) (≥ 14 h), followed by 6% HP strips (≥ 14 h) and 3% HP strips (≥ 14 h). At-home 10% CP (7-13 h) and placebo showed lower risks of tooth sensitivity without significant differences between these treatments. CONCLUSION: Considering the low level of evidence, OTC products presented satisfactory short-term effects on tooth bleaching compared to the placebo, with little to no impact on dentin hypersensitivity and gingival irritation. CLINICAL RELEVANCE: OTC products are proving to be practical alternatives for tooth whitening. However, patients should be advised about the possible risks of carrying out such procedures without professional supervision.

Cost-per-Response Analysis of Pure Hypochlorous Acid Among Patients with Chronic Venous Leg Ulcers: A Health Economic Analysis.

OBJECTIVE: To estimate the total cost-per-wound healing response (CPR) and the per-day CPR of patients with chronic leg ulcers treated with pure hypochlorous acid (pHA) as part of their overall would healing regimen. METHODS: The authors developed a deterministic decision-tree model to estimate the incremental CPR for pHA. The analysis was performed using clinical data from a published single-arm prospective study. The outcome of interest was re-epithelialization at 90 days. Economic data for pHA were based on public prices of pHA per dressing change from the wound care center perspective. The following time points were assessed: 90, 60, and 30 days. Dressing changes occurred every 2.5 days. Sensitivity analysis was performed to gauge the robustness of the results. RESULTS: A total of 31 patients (68% women) with 31 lesions (average age of wound, 29 months; range, 1-240 months) were included in the clinical study. Re-epithelialization occurred in 23 lesions (74%) at 90 days, 17 (55%) at 60 days, and 3 (10%) at 30 days. The total CPRs were $75.69, $68.27, and $193.44, and the per-day CPRs were $0.84, $1.13, and $6.45 at 90, 60, and 30 days, respectively. The sensitivity analysis revealed that CPRs ranged from $0.63 to $1.12 per day at 90 days. CONCLUSIONS: Incorporating pHA into standard wound healing protocols is a minimal added expense and may yield a substantial economic savings of $2,695 at 90 days.

Fabrication of a paper-based facile and low-cost microfluidic device and digital imaging technique for point-of-need monitoring of hypochlorite.

Lab-on-a-paper-based devices are promising alternatives to the existing arduous techniques for point-of-need monitoring. The present work reports an instant and facile method to produce a microfluidic paper-based analytical device (µPAD). The fabricated µPAD has been used to detect hypochlorite (OCl-) by incorporating newly synthesized chromo-fluorogenic ratiometric probes 1 and 2 into the sample reception zone. The probes showed high selectivity and fast response (<10 s) toward OCl- with an excellent linear relationship in the concentration range of 0-100 µM. The concentration-dependent fluorometric change driven by the reaction of 1@µPAD with OCl- has been monitored using gel-doc imaging systems, which is unprecedented. Digitizing the intensity of the colour solution with different mathematical models of colour has developed a straightforward method for monitoring OCl- without any interference from its competitors. 1@µPAD can detect OCl- at ∼10 times lower than the WHO recommended limit. The detection limit of 1@µPAD via a digital camera-based fluorescence technique was found to be better over digital camera-based cuvette assays. Therefore, 1@µPAD has been successfully utilized to monitor OCl- in actual environmental water samples with portability, ease of use, and sensitivity. The analytical RSD was found to be ≤3% based on fluorimetric detection using 1@µPAD. The chemodosimetric reaction between OCl- and the probe was evidenced by UV-vis and fluorescence spectroscopy, 1H NMR, and ESI-MS. The rapid response time, biocompatibility, low cytotoxicity, 100% aqueous solubility, ratiometric feature, and exclusive OCl- selectivity over other competitive ROS/RNS successfully lead to the application of the probes for bioimaging of exogenous as well as endogenous OCl- in normal cells (HEK293) and cancerous cells (HeLa).

Detecting Unique Analyte-Specific Radio Frequency Spectral Responses in Liquid Solutions-Implications for Non-Invasive Physiologic Monitoring.

With rising healthcare costs and the rapid increase in remote physiologic monitoring and care delivery, there is an increasing need for economical, accurate, and non-invasive continuous measures of blood analytes. Based on radio frequency identification (RFID), a novel electromagnetic technology (the Bio-RFID sensor) was developed to non-invasively penetrate inanimate surfaces, capture data from individual radio frequencies, and convert those data into physiologically meaningful information and insights. Here, we describe groundbreaking proof-of-principle studies using Bio-RFID to accurately measure various concentrations of analytes in deionized water. In particular, we tested the hypothesis that the Bio-RFID sensor is able to precisely and non-invasively measure and identify a variety of analytes in vitro. For this assessment, varying solutions of (1) water in isopropyl alcohol; (2) salt in water, and (3) commercial bleach in water were tested, using a randomized double-blind trial design, as proxies for biochemical solutions in general. The Bio-RFID technology was able to detect concentrations of 2000 parts per million (ppm), with evidence suggesting the ability to detect considerably smaller concentration differences.

Comparison of pre-treatments mediated by endoglucanase and TEMPO oxidation for eco-friendly low-cost energy production of cellulose nanofibrils.

Specific kinds of enzymes have been used as an eco-friendly pre-treatment for mechanical extraction of cellulose nanofibrils (CNFs) from vegetal pulps. Another well-established pre-treatment is the 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-mediated oxidation, which has gained considerable attention. Pre-treatments assist in fiber swelling, facilitating mechanical fibrillation, and reducing energy consumption; however, some of these methods are extremely expensive. This work aimed to evaluate the influence of enzymatic pre-treatment with endoglucanase on the energy consumption during mechanical fibrillation of cellulose pulps. Bleached pulps from Eucalyptus sp. and Pinus sp. were pre-treated with endoglucanase enzyme compared to TEMPO-meditated oxidation. Average diameters of CNFs pre-treated with enzymes were close to that found for TEMPO-oxidized nanofibrils (TOCNFs). Results showed that enzymatic pre-treatment did not significantly modify the pulp chemical and morphological characteristics with efficient stabilization of the CNFs suspension at higher supernatant turbidity. Energy consumption of pulps treated with endoglucanase enzymes was lower than that shown by pulps treated with TEMPO, reaching up to 58% of energy savings. The enzyme studied in the pulp treatment showed high efficiency in reducing energy consumption during mechanical fibrillation and production of films with high mechanical quality, being an eco-friendly option for pulp treatment.

The Assessment of Activity of Antiseptic Agents against Biofilm of Staphylococcus aureus Measured with the Use of Processed Microscopic Images.

Staphylococcal biofilms are major causative factors of non-healing wound infections. Their treatment algorithms recommend the use of locally applied antiseptic agents to counteract the spread of infection. The efficacy of antiseptics against biofilm is assessed in vitro by a set of standard quantitative and semi-quantitative methods. The development of software for image processing additionally allowed for the obtainment of quantitative data from microscopic images of biofilm dyed with propidium iodine and SYTO-9 reagents, differentiating dead cells from live ones. In this work, the method of assessment of the impact of antiseptic agents on staphylococcal biofilm in vitro, based on biofilms' processed images, was proposed and scrutinized with regard to clinically relevant antiseptics, polyhexanide, povidone-iodine and hypochlorite. The standard quantitative culturing method was applied to validate the obtained data from processed images. The results indicated significantly higher activity of polyhexanide and povidone-iodine than hypochlorite against staphylococcal biofilm. Taking into account the fact that in vitro results of the efficacy of antiseptic agents against staphylococcal biofilm are frequently applied to back up their use in hospitals and ambulatory units, our work should be considered an important tool; providing reliable, quantitative data in this regard.

The Lesson Learned from the COVID-19 Pandemic: Can an Active Chemical Be Effective, Safe, Harmless-for-Humans and Low-Cost at a Time? Evidence on Aerosolized Hypochlorous Acid.

The COVID-19 pandemic has underlined the importance of disinfectants as tools to prevent and fight against coronavirus spreading. An ideal disinfectant and sanitizer must be nontoxic to surface contact, noncorrosive, effective, and relatively inexpensive as it is hypochlorous acid (HOCl). The present work intended to evaluate, on different surfaces, the bactericidal and virucidal effectiveness of nebulized HOCl and test its safety usage in 2D and 3D skin and lung models. Our data showed that HOCl at the dose of 300 ppm did not affect cellular and tissue viability, not their morphology. The HOCl bactericidal properties varies with the surface analyzed: 69% for semi-porous, 96-99.9% for flat and porous. This discrepancy was not noticed for the virucidal properties. Overall, this study showed that nebulized HOCl can prevent virus and bacteria growth without affecting lung and skin tissues, making this compound a perfect candidate to sanitize indoor environments.

Túneles de desinfección peatonal pulverizadores de ozono y otros desinfectantes para disminuir la propagación del SARS-CoV-2 / Pedestrian disinfection tunnels, ozone sprays and other disinfectants to reduce the spread of SARS-CoV-2

INTRODUCCIÓN: Queda mucho por aprender sobre el nuevo coronavirus (SARS-CoV-2) que causa la enfermedad por coronavirus 2019 (COVID-19). Según lo que se sabe actualmente sobre el virus y sobre coronavirus similares que causan SARS y MERS, la propagación de persona a persona ocurre con mayor frecuencia entre contactos cercanos (dentro de aproximadamente 2 metros) a través de gotitas respiratorias generadas por una persona infectada al toser o estornudar (CDC 2020). La transmisión también puede ocurrir de forma indirecta por contacto con superficies que se encuentran en el entorno inmediato de una persona infectada o con objetos que esta haya utilizado (OMS 2020b). La transmisión del coronavirus en general ocurre mucho más comúnmente a través de gotitas respiratorias que a través de fómites (CDC 2020). Por otro lado, se ha reportado que el SARS-CoV-2 puede permanecer viable durante horas o días en superficies hechas de una variedad de materiales. En ese sentido, la desinfección de superficies es considerada una buena práctica para la prevención de COVID-19 y otras enfermedades respiratorias virales en entornos comunitarios (CDC 2020). Sin embargo, en países como China, México y Argentina se han visto imágenes en donde los desinfectantes son rociados directamente a las personas cuando estas pasan a través de túneles instalados en lugares públicos de alto tránsito, como entradas a mercados, edificios administrativos u hospitales. Esta medida ha sido cuestionada ya que el desinfectante usado en estos túneles puede causar irritación en las personas, así como daño en la piel y los ojos (Neustaeter 2020). El túnel de desinfección peatonal consiste en un sistema de aspersores que rocían al peatón un desinfectante con el fin de desinfectar la ropa. Cada persona debe permanecer en el interior del túnel unos pocos segundos con las manos en alto para permitir que la mezcla sanitizante llegue a la mayoría de las partes del cuerpo (Infobae 2020). Dentro de los desinfectantes utilizados se encuentran el amonio cuaternario, el ozono, el ácido hipocloroso, el alcohol, soluciones de hipoclorito, catalizadores orgánicos, entre otros (Minsalud 2020). El uso de esta innovación tecnológica ha sido propuesto por algunas personas como una medida sanitaria adicional a las ya establecidas (distanciamiento físico, uso de mascarillas, lavado de mano) para reducir el contagio del SARS-CoV-2 en lugares públicos de alta concurrencia. Actualmente, esta propuesta se ha difundido de manera mediática captando el interés de diversas instituciones para su posible incorporación. Al respecto, la Dirección General de Salud Ambiental del Perú (DIGESA), con fecha 16 de abril de 2020, realizó un pronunciamiento desalentando el uso de túneles desinfectantes para evitar la transmisión de COVID-19. En esta nota se enfatiza que no existe evidencia científica de que los túneles desinfectantes sean efectivos para impedir la transmisión del virus, y que por el contrario, los desinfectantes dispersados sobre los peatones podrían ser dañinos para la salud e incluso aumentar el riesgo de dispersión del SARS-CoV-2. También se señala que toda desinfección para evitar la transmisión de COVID-19 se debe realizar sobre superficies inertes como mesas, pisos o estantes, y no sobre personas (DIGESA 2020). A pesar del pronunciamiento por parte de la DIGESA, el IETSI ha recibido solicitudes de evaluación, en donde se plantea el uso de túneles de desinfección generales y, específicamente, los de ozono. Así, surge la necesidad de conocer el funcionamiento de los túneles de desinfección peatonal pulverizadores de ozono y de otros desinfectantes, así como revisar la literatura pertinente a esta tecnología para evaluar su efectividad y seguridad para disminuir la propagación del SARS-CoV-2. MÉTODOS: Primero, se realizó una búsqueda manual de guías, reportes técnicos o recomendaciones para la desinfección en el contexto del COVID-19, en las páginas web de diversas sociedades y gobiernos alrededor del mundo, tales como World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), European Centre for Disease Prevention and Control (ECDC), el Gobierno de Canadá, el Gobierno de Reino Unido, el Gobierno de Australia, el Gobierno de España, el Gobierno de Colombia, entre otros. Segundo, se realizó una búsqueda sistemática de guías o revisiones que brindaran recomendaciones con relación a la tecnología de interés utilizando la base de datos MEDLINE vía PubMed. La estrategia de búsqueda fue la siguiente: (sanitation[tiab] OR disinfect*[tiab]) AND (COVID-19 OR SARS-CoV-2 OR Coronavirus OR SARS) (144 ítems). Tercero, se realizó una búsqueda sistemática de estudios que evaluaran la efectividad y seguridad de los túneles de desinfección peatonal de ozono utilizando la base de datos MEDLINE vía PubMed, utilizando la siguiente estrategia de búsqueda: ozone AND (COVID-19 OR SARS-CoV-2 OR Coronavirus OR SARS) (10 ítems). Finalmente, se buscaron estudios adicionales que pudiesen haber escapado a las búsquedas con una estrategia de bola de nieve mediante la revisión de las listas de referencias de las publicaciones que sean de relevancia. RESULTADOS: Se identificó una guía técnica elaborada por el Ministerio de Salud y Protección de Colombia que evaluó el uso de sistemas de aspersión de productos desinfectantes sobre personas para la prevención de la trasmisión de COVID-19. También se identificó recomendaciones relacionadas al tema en las páginas web de la OMS y la EPA. CONCLUSIONES: No se recomienda el uso de túneles de desinfección peatonal pulverizadores de ozono u de otros desinfectantes ya que no se cuenta con evidencia científica sobre su efectividad para disminuir la propagación del COVID-19. Además, el uso de estos sistemas podría causar potenciales daños en la salud de las personas, como irritación de los ojos y de las vías respiratorias. De acuerdo a la información publicada por agencias regulatorias internacionales como la EPA, aún si el ozono se utilizara en concentraciones que no excedieran los estándares de salud pública, estos no eliminarían eficazmente los virus. Para el caso de túneles que utilizan otros agentes desinfectantes como soluciones de hipoclorito de sodio o alcohol, algunas instituciones ya han emitido pronunciamientos en contra del uso de estas tecnologías debido a la falta de evidencia que sustente su uso y al elevado riesgo de daño al peatón. Otros expertos señalan que el uso de túneles de desinfección podría tener un efecto opuesto al esperado, ya que la falsa sensación de seguridad por parte de los peatones podría hacer que estos disminuyan las medidas eficaces para disminuir el contagio del COVID19 como el distanciamiento social y el lavado de manos. Finalmente, a nivel mundial, el ozono y demás desinfectantes no están autorizados por ninguna autoridad de salud para su aplicación directa sobre humanos.

A real-time-based in vitro assessment of the oxidative antimicrobial mechanisms of the myeloperoxidase-hydrogen peroxide-halide system.

Mammals have evolved a special cellular mechanism for killing invading microbes, which is called the phagocytosis. Neutrophils are the first phagocytosing cells that migrate into the site of infection. In these cells, hypochlorite (HOCl) and other hypohalites, generated in the myeloperoxidase (MPO)-hydrogen peroxide (H2O2)-halide system is primarily responsible for oxidative killing. Here, we present a method for assessing these oxidative mechanisms in an in vitro cell-free system in a kinetical real-time-based manner by utilizing a bioluminescent bacterial probe called Escherichia coli-lux. The E. coli-lux method provides a practical tool for assessing the effects of various elementary factors in the MPO-H2O2-halide system. Due to the reported versatile intracellular pH and halide concentration during the formation of the phagolysosome and respiratory burst, the antimicrobial activity of the MPO-H2O2-halide system undergoes extensive alterations. Here, we show that at a physiological pH or lower, the antimicrobial activity of MPO is high, and the system effectively enhances the H2O2-dependent oxidative killing of E. coli by chlorination. The HOCl formed in this reaction is a prominent microbe killer. During the respiratory burst, there is a shift to a more alkaline environment. At pH 7.8, the chlorinating activity of MPO was shown to be absent, and the activity of the HOCl decreased. At this higher pH, the activity of H2O2 is enhanced and high enough to kill E. coli without the participation of MPO, and the lowered chloride concentration seemed still to enhance the H2O2-dependent killing capacity.

Quantitative assessment of cyanide in cystic fibrosis sputum and its oxidative catabolism by hypochlorous acid.

RATIONALE: Cystic fibrosis (CF) patients are known to produce cyanide (CN-) although challenges exist in determinations of total levels, the precise bioactive levels, and specificity of its production by CF microflora, especially P. aeruginosa. Our objective was to measure total CN- levels in CF sputa by a simple and novel technique in P. aeruginosa positive and negative adult patients, to review respiratory tract (RT) mechanisms for the production and degradation of CN-, and to interrogate sputa for post-translational protein modification by CN- metabolites. METHODS: Sputa CN- concentrations were determined by using a commercially available CN- electrode, measuring levels before and after addition of cobinamide, a compound with extremely high affinity for CN-. Detection of protein carbamoylation was measured by Western blot. MEASUREMENTS AND MAIN RESULTS: The commercial CN- electrode was found to overestimate CN- levels in CF sputum in a highly variable manner; cobinamide addition rectified this analytical issue. Although P. aeruginosa positive patients tended to have higher total CN- values, no significant differences in CN- levels were found between positive and negative sputa. The inflammatory oxidant hypochlorous acid (HOCl) was shown to rapidly decompose CN-, forming cyanogen chloride (CNCl) and the carbamoylating species cyanate (NCO-). Carbamoylated proteins were found in CF sputa, analogous to reported findings in asthma. CONCLUSIONS: Our studies indicate that CN- is a transient species in the inflamed CF airway due to multiple biosynthetic and metabolic processes. Stable metabolites of CN-, such as cyanate, or carbamoylated proteins, may be suitable biomarkers of overall CN- production in CF airways.

A facile photoelectrochemical sensor for high sensitive ROS and AA detection based on graphitic carbon nitride nanosheets.

Photoactive material is one of the main challenges for fabrication of sensitive and selective photoelectrochemical (PEC) sensor. Herein, a facile PEC sensor is constructed using graphitic carbon nitride nanosheets (g-C3N4 NSs) coated on the surface of ITO electrode, where electron donor properties of potassium ferrocyanide and ascorbic acid is utilized for the tracing of hydrogen peroxide (H2O2), hypochlorite (ClO-), and ascorbic acid (AA). Our designed PEC sensor exhibits a good linear range to H2O2 concentrations from 12.5 to 875 µM in pH = 7.4 and 2.5-400 µM in pH = 10, while that for AA is in the range from 0.25 to 100 µM in pH = 7.4, and with the same pH for ClO- concentrations in the range from 0.5 to 19 × 10-3% (V/V) in a bleach sample. Owing to the good responses towards the traces of H2O2, AA, and ClO-, our designed system may be used as H2O2, ClO-, and AA sensor for outdoor applications with high specificity, long-time stability and good reproducibility.

Control of Salmonella Cross-Contamination between Green Round Tomatoes in a Model Flume System.

Tomato Best Management Practices require Florida packers to treat tomatoes in a flume system containing at least 150 ppm of free chlorine or other approved sanitizer. However, research is needed to determine the ability of these sanitizers to prevent the transfer of pathogens from contaminated to uncontaminated tomatoes, particularly under realistic packinghouse conditions. The goal of this research was to assess the minimum levels of sanitizer needed to prevent Salmonella cross-contamination between tomatoes in a model flume system under clean conditions and conditions where organic matter was added. Inoculated tomatoes (ca. 8.3 log CFU per tomato) were treated along with uninoculated tomatoes in a model flume system containing 0, 10, or 25 ppm of hypochlorous acid (HOCl) under organic loading conditions of 0, 500, or 4,000 ppm of chemical oxygen demand (COD). In the absence of HOCl, uninoculated tomatoes were highly contaminated (ca. 5 log CFU per tomato) by 15 s. No contamination was detectable (<2 log CFU per tomato) on uninoculated tomatoes when HOCl was present, except with 10 ppm at 4,000 ppm of COD, suggesting failure of 10 ppm of HOCl as a sanitizer under very high organic loading conditions. In the presence of HOCl or peroxyacetic acid, Salmonella was undetectable (<1 log CFU/ml) in the model flume water samples after 2 and 30 s, respectively. Upon enrichment, none of the uninoculated tomatoes treated with 25 ppm of HOCl for 120 s were positive for Salmonella, even in the presence of organic loading at 500 ppm of COD. Based on these findings, 25 ppm of HOCl may be adequate to prevent cross-contamination when the concentration is properly maintained, COD does not exceed 500 ppm, and tomatoes are treated for at least 120 s. Further validation in a larger commercial setting and using higher organic loading levels is necessary because managing HOCl at this low concentration is difficult, especially in a recirculating system. The use of less sanitizer by packers could reduce chemical and disposal costs.

Microbial community-based polyhydroxyalkanoates (PHAs) production from wastewater: Techno-economic analysis and ex-ante environmental assessment.

This work investigates the potential for polyhydroxybutyrate (PHB) production from wastewater, from a techno-economic and an environmental perspective, examining scale-up opportunities and bottlenecks prior to commercialisation. Conceptual process design, economic, environmental impacts and sensitivity analysis are developed for one fermentation process and three downstream processing routes, based on alkali, surfactant-hypochlorite and solvent treatments. Environmentally and cost-wise, the alkali treatment is the most favourable with production costs of 1.40€/kg PHB, global warming potential of 2.4kgCO2-eq/kg PHB and non-renewable energy use of 106MJ/kg PHB. The solvent-based process yields the highest costs and environmental burdens: 1.95€/kg PHB, 4.30kgCO2-eq/kg PHB and 156MJ/kg PHB. The production of PHB from wastewater is identified as an interesting alternative to pure culture-polyhydroxyalkanoates production from sugars. However, these results are not yet competitive with those for the petrochemical counterparts. Additional performance improvements may be possible, through process integration and optimisation.

Five-year longitudinal assessment (2008 to 2012) of E-101 solution activity against clinical target and antimicrobial-resistant pathogens.

This study summarizes the topical E-101 solution susceptibility testing results for 760 Gram-positive and Gram-negative target pathogens collected from 75 U.S. sites between 2008 and 2012 and 103 ESKAPE pathogens. E-101 solution maintained potent activity against all bacterial species studied for each year tested, with MICs ranging from <0.008 to 0.25 µg porcine myeloperoxidase (pMPO)/ml. These results confirm that E-101 solution retains its potent broad-spectrum activity against U.S. clinical isolates and organisms with challenging resistance phenotypes.

Rapid and ratiometric detection of hypochlorite with real application in tap water: molecules to low cost devices (TLC sticks).

We have designed a chemodosimeter DPNO (weak fluorescence) which can be oxidized to HPNO (strong blue fluorescence) by OCl(-) with high selectivity and sensitivity in a ratiometric approach with a noticeably lower detection limit. The sensor could be useful for the detection of hypochlorites in tap water.

Reusability of iron sludge as an iron source for the electrochemical Fenton-type process using Fe²+/HOCl system.

This paper reports on the reusability and the optimal reuse of iron-rich sludge for an electrochemical Fenton-type process using sequencing batch mode and separation batch mode reuse models. In the sequencing batch mode, processes of electrochemical treatment, neutralization, sedimentation, and re-dissolution of iron sludge were all performed in the same reactor, whereas the neutralization and sedimentation of iron sludge in the separation batch mode was carried out in an iron recovery tank separated from the electrochemical reactor. The effects of iron speciation at different pH levels were discussed. It was found that ferric ions at a pH ≤2.5 were suitable for this electrochemical Fenton-type process where ferrous ions acted as hydroxyl radical scavengers, generating brownish deposits on the cathode at pH 3. When the sequencing batch mode was applied, the current efficiency in the Fenton-type process after the iron recovery declined due to the formation of insoluble deposits on the electrodes, which decreased at lower pH. The deposits were mainly formed during the neutralization and sedimentation steps after the electrochemical process. Fortunately, iron from the sludge could be reused for the electrochemical process when the separation batch mode was used, with 100% iron recovery and no decline in current efficiency.

The real-time-based assessment of the microbial killing by the antimicrobial compounds of neutrophils.

A recombinant Escherichia coli K-12 strain, transformed with a modified bacterial luciferase gene (luxABCDE) from Photorhabdus luminescens, was constructed in order to monitor the activity of various antimicrobial agents on a real-time basis. This E. coli-lux emitted, without any addition of substrate, constitutive bioluminescence (BL), which correlated to the number of viable bacterial cells. The decrease in BL signal correlated to the number of killed bacterial cells. Antimicrobial activity of hydrogen peroxide (H(2)O(2)) and myeloperoxidase (MPO) was assessed. In high concentrations, H(2)O(2) alone had a bacteriocidic function and MPO enhanced this killing by forming hypochlorous acid (HOCl). Taurine, the known HOCl scavenger, blocked the killing by MPO. When E. coli-lux was incubated with neutrophils, similar killing kinetics was recorded as in H(2)O(2)/MPO experiments. The opsonization of bacteria enhanced the killing, and the maximum rate of the MPO release from lysosomes coincided with the onset of the killing.

Development and validation of a screening procedure for the assessment of inhibition using a recombinant enzyme.

Myeloperoxidase (MPO, E.C. 1.1.11.7) is a heme-containing enzyme that catalyses the synthesis of hypochlorous acid (HOCl) in the presence of hydrogen peroxide (H2O2) and chlorine anions. The production of HOCl is kept under strict control of neutrophils. However, in several pathological conditions, MPO is leaked in the extracellular fluid, which involves an over-production of reactive oxygen species like HOCl and promotes the damages caused by neutrophils. As a consequence, the inhibition of MPO by various agents has been investigated and a variety of molecules have been evaluated for this activity in different models. The present study aims to describe and validate a rapid screening method based on the taurine assay and using a recombinant MPO. After validation of the stock solutions used during the experiments, the amount of MPO for the completion of the reaction was measured and fixed to an optimal value. The inhibiting concentration at 50% of flufenamic acid (taken as a reference molecule) was then assessed in both a simple tube test and a microplate test and delivered similar results (1.3+/-0.2 microM vs 1.4+/-0.2 microM, P=0.2). Finally, different molecules able to inhibit MPO were evaluated in this rapid assay system providing results comparable to literature. The high throughput screening is undoubtedly a first line assessment method which affords the selection of inhibitors and permits to reduce the number of candidates for a further elucidation of the mechanism of MPO inhibition.

Assessment of water pollution in different bleaching based paper manufacturing and textile dyeing industries in India.

Paper industries using different raw materials such as hard wood, bamboo, baggase, rice-straw and waste papers and bleaching chemicals like chlorine, hypochlorite, chlorine dioxide, hydrogen peroxide, sulphite and oxygen were studied to estimate organic pollution load and Adsorbable Organic Halides (AOX) per ton of production. The hard wood based paper industries generate higher Chemical Oxygen Demand (COD) loads (105-182 kg t(-1)) and Biochemical Oxygen Demand (BOD) loads (32.0-72 kg t(-1)) compared to the agro and waste paper based industrial effluents. The bleaching sequences such as C-EP-H-H, C-E-H-H, C-E-Do-D1 and O-Do-EOP-D1 are adopted in the paper industries and the molecular elemental chlorine free bleaching sequence discharges low AOX in the effluent. The range of AOX concentration in the final effluent from the paper industries was 0.08-0.99 kg t(-1) of production. Water consumption was in the range of 100-130 m(3) t(-1) of paper production for wood based industries and 30-50 m(3) for the waste paper based industries. Paper machine effluents are partially recycled after treatment and pulp mill black liquor are subject to chemical recovery after evaporation to reduce the water consumption and the total pollution loads. Hypochlorite bleaching units of textile bleaching processes generate more AOX (17.2-18.3 mg l(-1)) and are consuming more water (45-80 l kg(-1)) whereas alkali peroxide bleaching hardly generates the AOX in the effluents and water consumption was also comparatively less (40 l kg(-1) of yarn/cloth).

A preliminary assessment of Bacillus anthracis spore inactivation using an electrochemically activated solution (ECASOL).

AIM: To evaluate the efficacy of electrochemically activated solution (ECASOL) in decontaminating Bacillus anthracis Ames and Vollum 1B spores, with and without changing the source water hardness and final ECASOL pH. METHODS AND RESULTS: Five different ECASOL formulations were generated, in which the source water hardness and final ECASOL pH were varied, resulting in cases where significant changes in free available chlorine (FAC) and oxidative-reduction potential (ORP) were observed. B. anthracis Ames and Vollum 1B spores were suspended in the various ECASOL formulations for 30 min, and decontamination efficacy was determined; calcium hypochlorite [5% high-test hypochlorite (HTH)] was used as a positive control. The five different ECASOL formulations yielded mean FAC levels ranging from 305 to 464 ppm, and mean ORP levels ranging from +826 to +1000 mV. Exposure to all the ECASOL formulations and 5% HTH resulted in >or=7.0 log reductions in both B. anthracis Ames and Vollum 1B spores. CONCLUSIONS: The present testing demonstrated that ECASOL with a minimum of c. 300-ppm FAC levels and +800-mV ORP inactivated the B. anthracis spores in suspension, similar to 5% HTH. SIGNIFICANCE AND IMPACT OF THE STUDY: These results provide information for decontaminating B. anthracis Ames and Vollum 1B spores in suspension using ECASOL.