Stability Of Peroxide Research Articles

Evaluating chemi-mechanical pulping processes of agricultural residues: High-yield pulps from wheat straw for fiber-based bioproducts

This work evaluates the feasibility of APMP (alkaline peroxide mechanical pulping) and CTMP (chemi-thermomechanical pulping) of wheat straw as small-scale, low-capital expenditure pulping process to produce high-yield pulps for fiber-based bioproducts. APMP and CTMP wheat straw pulps were characterized in terms of pulping yield, freeness, ISO brightness, and fiber morphology. Additionally, both pulps were evaluated for tissue paper applications and benchmarked against BEK (bleached eucalyptus kraft) market pulp. APMP wheat straw pulps presented higher yield (75.2 – 79.8 %) compared to CTMP (69.1 – 80.6 %), depending on cooking chemicals and chemical charge during the chemical impregnation stage. The final brightness of APMP pulps varied from 36.4 % to 37.8 % ISO when sodium hydroxide and hydrogen peroxide were used as pulping agents without additional chemical additives. However, the brightness of APMP pulps can be increased up to 49.7 % ISO by using additional chemical additives such as EDTA (chelating agent), sodium silicate (peroxide stabilizer), or by employing a multi-stage chemical impregnation strategy. Both pulps produced fibers with similar morphological properties. A comparison of tissue-making properties showed that APMP pulps produced bulkier handsheets with higher water absorption capacity and better softness than CTMP pulps. However, CTMP pulps exhibited a higher tensile index than APMP pulps for a given pulp freeness. The results indicate that non-wood fibers, such as those derived from wheat straw, could be a promising alternative for use in fiber-based bioproducts such as hygiene tissue.

Preparation and evaluation of functional cocoa-free spread alternatives from different sources.

Spread products have an important market share as they have high nutritional value and they are increasingly consumed, especially by children as a source of energy. The purpose of this work was to evaluate the potential use of powdered chickpea, black rice, carob, doum, date seeds, and beetroot to produce novel functional spreadable products as cocoa-free alternatives. Additionally, to avoid the side effects of cocoa-based products and to assess the cocoa replacement effects on the sensory properties, chemical composition, texture analysis, viscosity, antioxidant, peroxide stability, and microbial quality during storage periods were compared to the ones of cocoa spread. Sensory evaluation revealed that most formulated spreads were accepted as chocolate spread alternatives since there was no significant difference in overall acceptability among cocoa, chickpea, black rice, carob, and doum, while date seeds and beetroot spreads were significantly less acceptable. A variation was observed in the proximate chemical analysis of the produced functional spreads, as the alternative spreads had different characteristics to each other in their physicochemical, texture, and rheological properties. Results indicated a wide variation in the total phenolic content (TPC) of the different spread extracts. The highest amount of TPC was obtained for beetroot spread (455.84 mg GAE/100 g) followed by black rice spread (436.08 mg GAE/100 g). The obtained results indicated that the antioxidant activity of different spreads was significantly different (p < .05) while based on their microbiological analysis, they could have a shelf life of up to 9 months. According to the results, chickpea, carob, doum, black rice, date seeds, and beetroot powders could be used for the production of cocoa-free alternatives as they were highly acceptable and they showed antioxidant and antimicrobial activity.

Fabrication of caffeoylquinic acid-loaded burdock polysaccharide nanoparticles and their antioxidant activity in hydrogen peroxide-damaged HepaRG cells

Herein, burdock polysaccharide (BP) and modified burdock polysaccharide (MBP) were prepared, followed by the fabrication of chlorogenic acid (CA)-BP, CA-MBP, isochlorogenic acid A (ICA)-BP, and ICA-MBP nanoparticles. Afterward, the structural characteristics, physical stability, digestive characteristics, and antioxidant activity of hydrogen peroxide (H2O2)-damaged HepaRG cells were evaluated. The result indicated that the loading capacities of CA in BP-CA and MBP-CA were 0.14 and 0.53 μg/mg, respectively. Conversely, the loading capacities of ICA in BP-ICA and MBP-ICA were 0.36 and 0.60 μg/mg, respectively. Four complex nanoparticles exhibited excellent physical stability under different pH values, temperatures, and ionic concentrations, especially MBP-CA and MBP-ICA. Moreover, four complex nanoparticles could protect caffeoylquinic acid from being released in gastric fluid. All six samples exhibited high antioxidant activity in H2O2-induced HepaRG cells, especially BP and MBP-CA. These findings indicated that caffeoylquinic acid–polysaccharide complexes were successfully prepared and highlighted the potential of polysaccharides as natural carriers for hydrophobic bioactive molecules.

Influence of Hyperconjugation on the Stability and Stable Conformation of Ethane, Hydrazine, and Hydrogen Peroxide

Influence of Hyperconjugation on the Stability and Stable Conformation of Ethane, Hydrazine, and Hydrogen Peroxide

Improving hydrogen peroxide stability of a dye-decolorising peroxidase from Irpex lacteus F17 by site-directed mutagenesis

Il-DyP4, a dye-decolorizing peroxidase (DyP) from Irpex lacteus F17, has a strong ability to oxidise harmful aromatic compounds, implying application potential in the field of environmental protection. However, the low H2O2 stability of Il-DyP4 hinders its practical application. To improve the H2O2 stability of Il-DyP4, oxidation-sensitive amino acids including three Met, one Cys and ten Tyr residues were mutated to less easily oxidizable residues such as Leu, Val and Phe by site-specific mutagenesis. Mutation of the M207 site, located on the surface of the enzyme and far away from the haem group, improved H2O2 stability by 5.3-fold or more. In addition, Y234, also on the enzyme surface, was replaced with Phe and the Y234F mutant displayed 7.3-fold increased H2O2 stability. Furthermore, mutants M207V and Y234F were selected for the decolorization of various types of synthetic dyes, revealing high decolorization activities, especially for M207V with enhanced catalytic activity. The stable DyP mutant M207V has the potential for decolorization of industrial dye wastewater.

Effect of interfacially-engineered nanoemulsions of linoleic acid stabilized by mixed surfactant systems and curcumin on their physicochemical properties, induction times, and peroxidation stability

Nanoemulsions have become the best candidates for loading hydrophobic bioactive molecules and enhancing their shelf-life and bioavailability in the food, pharmaceutical and cosmetic industries. Mixture of different surfactants modulates their interfacial characteristics, thereby imposing a direct effect in improving their physicochemical and nutritional characteristics. Herein, we report the formulation of oil-in-water nanoemulsions stabilized with either single or mixture of surfactants having different electric charges like Tween 20 (T20, nonionic), sodium salt of Lauroyl Sarcosine (LS, anionic) and 3-(N,N-dimethylmyristylammonio)propanesulfonate (DPS, zwitterionic) to control the peroxidation of linoleic acid by using curcumin as the potential antioxidant. The distribution of H+ ions at the interface and the variation in the values of observed rate constant (kobs) is assessed by employing the novel Chemical Kinetic method based on the reaction between arenediazonium ions and the antioxidant. For single-surfactant systems, nanoemulsions containing pure T20 or LS showed good oxidative stability whereas for mixed-surfactant systems, the oxidative stability increases with increasing concentration of LS and decreasing concentration of DPS. This could be explained on the basis of physicochemical characterization of nanoemulsions, interfacial H+ ion concentration, and solubility characteristics of curcumin. The study shows great promise of such mixed surfactant systems, ignored so far, for providing a novel and tailored formulation of nanoemulsions for improving the oxidative stability of linoleic acid.

The Effects of Acid and Hydrogen Peroxide Stabilizer on the Thermal Hazard of Adipic Acid Green Synthesis

The synthesis of adipic acid, which is formed by the reaction of cyclohexene oxidized by hydrogen peroxide (H2O2), is hazardous because of the highly exothermic nature of this reaction and H2O2 decomposition. The objective of this comprehensive study was to investigate and illustrate the effects of sulfuric acid (H2SO4) and H2O2 stabilizer (EDTA) on the thermal hazard of H2O2 decomposition and the green synthesis of adipic acid, which also provided a reference to reduce the risk of the reactions. Various calorimetry techniques were carried out to characterize the exothermic behavior of the reactions. An HPLC device was used to characterize the yield of adipic acid and the conversion rate of the raw materials, cyclohexene and H2O2. Meanwhile, density functional theory calculations were performed to understand the reaction mechanism and the associated energies of H2O2 decomposition catalyzed by sodium tungstate dihydrate (Na2WO4·2H2O). Finally, combined with the calorimetry results, the risk of the adipic acid synthesis reaction was assessed using the intrinsic control index method (ITHI). The results show that the addition of H2SO4 and EDTA can reduce the exothermic heat of the H2O2 decomposition reaction and the green synthesis reaction of adipic acid. The yield of adipic acid was also increased. The hazard level of stage A was IV, and to remove more reaction heat, it was recommended to enhance the reflux cooling of stage A. The hazard level of stage B was I, which was very low and no further measures could be taken.

Qualidade físico-química e microbiológica de leite bovino cru refrigerado comercializado em Presidente Médici, estado de Rondônia, Amazônia Ocidental, Brasil

The aimed was to evaluate the quality of raw milk from some suppliers in rural and urban areas and test the hypothesis that they are not safe for immediate consumption. The study was conducted with suppliers in rural and urban areas in Presidente Médici municipality, Rondônia state. The method of the Ministério da Agricultura, Pecuária e Abastecimento (MAPA), was used, which consists of titrating a portion of the sample with a sodium hydroxide solution of known concentration, using phenolphthalein as an indicator. According to Brazilian legislation and literature, stability of Alizarol, foreign substances, Chloride, Hypochlorite, Hydrogen Peroxide and Colostrum were analyzed. Microbiological analysis, standard plate count (SPC) and quantification of thermotolerant coliforms were also performed using the most probable number (MPN) technique. Values ​​above the limits established by legislation were found, mainly for temperature and titratable acidity, in addition to stability results against Alizarol and the presence of colostrum. There were high microbial contents with regard to SPC, and, in this case, the presence of pathogenic microorganisms cannot be disregarded. The presence of thermotolerant coliforms may indicate probable contact of milk with feces. Therefore, it is considered that the samples analyzed here are not safe for ingestion in the raw form.

Inhibition of Phytophthora cinnamomi mycelial growth with stabilised hydrogen peroxide

The efficacy of hydrogen peroxide (H2O2) was evaluated for the inhibition of mycelial growth of Phytophthora cinnamomi in vitro. Phytophthora cinnamomi infects many crops globally causing root, collar and crown rot, resulting in significant economic losses for producers. Two 30% (w/v) H2O2 products, each stabilised with a different concentration of 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) (3% versus 0.003% w/v) were compared to determine the most efficacious H2O2 concentration as well as potential interactive effects of the stabilising compound. Inhibition of P. cinnamomi growth was evaluated by amending potato dextrose agar media (PDA) with a range of concentrations of the test solutions. The biocidal activity of H2O2 was enhanced by a higher concentration of HEDP. Concentrations from 6.25 mL/L of the H2O2 product with 3% HEDP provided 100% inhibition of mycelial growth in vitro. Neither the product with 0.003% HEDP, nor HEDP stabiliser without H2O2, achieved comparable inhibition. Our results highlight an opportunity to expand the use of stabilised H2O2 products developed for cleaning of drip irrigation emitters to include the control of Phytophthora spp. and potentially other waterborne plant pathogens.

Validating Methods To Eradicate Plant-Pathogenic Ralstonia Strains Reveals that Growth In Planta Increases Bacterial Stress Tolerance.

Plant-pathogenic bacteria in the Ralstonia solanacearum species complex (RSSC) cause highly destructive bacterial wilt disease of diverse crops. Wilt disease prevention and management is difficult because RSSC persists in soil, water, and plant material. Growers need practical methods to kill these pathogens in irrigation water, a common source of disease outbreaks. Additionally, the R. solanacearum race 3 biovar 2 (R3bv2) subgroup is a quarantine pest in many countries and a highly regulated select agent pathogen in the United States. Plant protection officials and researchers need validated protocols to eradicate R3bv2 for regulatory compliance. To meet these needs, we measured the survival of four R3bv2 and three phylotype I RSSC strains following treatment with hydrogen peroxide, stabilized hydrogen peroxide (Huwa-San), active chlorine, heat, UV radiation, and desiccation. No surviving RSSC cells were detected after cultured bacteria were exposed for 10 min to 400 ppm hydrogen peroxide, 50 ppm Huwa-San, 50 ppm active chlorine, or temperatures above 50°C. RSSC cells on agar plates were eradicated by 30s of UV irradiation and killed by desiccation on most biotic and all abiotic surfaces tested. RSSC bacteria did not survive the cell lysis steps of four nucleic acid extraction protocols. However, bacteria in planta were more difficult to kill. Stems of infected tomato plants contained a subpopulation of bacteria with increased tolerance of heat and UV light, but not oxidative stress. This result has significant management implications. We demonstrate the utility of these protocols for compliance with select agent research regulations and for management of a bacterial wilt outbreak in the field. IMPORTANCE Bacteria in the Ralstonia solanacearum species complex (RSSC) are globally distributed and cause destructive vascular wilt diseases of many high-value crops. These aggressive pathogens spread in diseased plant material and via contaminated soil, tools, and irrigation water. A subgroup of the RSSC, race 3 biovar 2, is a European and Canadian quarantine pathogen and a U.S. select agent subject to stringent and constantly evolving regulations intended to prevent pathogen introduction or release. We validated eradication and inactivation methods that can be used by (i) growers seeking to disinfest water and manage bacterial wilt disease outbreaks, (ii) researchers who must remain in compliance with regulations, and (iii) regulators who are expected to define containment practices. Relevant to all these stakeholders, we show that while cultured RSSC cells are sensitive to relatively low levels of oxidative chemicals, desiccation, and heat, more aggressive treatment, such as autoclaving or incineration, is required to eradicate plant-pathogenic Ralstonia growing inside plant material.

Structural Characterization and Peroxidation Stability of Palm Oil-Based Oleogel Made with Different Concentrations of Carnauba Wax and Processed with Ultrasonication.

The effect of ultrasonication (25 kHz for 10 min) on physical, thermal, and structural properties and storage stability of palm oil-based oleogels prepared using different concentrations of carnauba wax (CW) (5% or 10%) were investigated and compared with oleogels prepared with a homogenizer (2000 rpm for 10 min). Overall, this study found that applying an ultrasonication process with higher CW concentration (10%) effectively improved the properties and stability of palm oil-based oleogel (p &lt; 0.05). Oleogels processed with ultrasonication had higher lightness (L*), higher yellowness (b*), and lower redness (a*) than those processed with homogenizer (p &lt; 0.05), irrespective of CW concentrations. However, a higher CW concentration (10%) increased the textural properties of oleogels such as hardness, stickiness, and tackiness as compared to oleogels with a lower CW concentration (5%) (p &lt; 0.05). Thermal properties including melting onset temperature, melting peak temperature, and melting enthalpy were found to be significantly higher in ultrasonication-processed oleogels with high CW concentration (p &lt; 0.05). Furthermore, the microscopic examination of the oleogels exhibited a strong gel network when prepared using a high concentration of CW and processed with ultrasonication. Fourier Transform Infrared (FTIR) spectra of oleogels revealed that strong intra- and intermolecular interactions were formed by hydrogen bonding between CW and palm oil. X-ray diffraction (XRD) showed a smooth and fine structural network of oleogels and proved that ultrasonication increased the structural properties of oleogel. Moreover, oil loss and peroxide value of oleogels were increased during 90 days of storage (p &lt; 0.05). However, oleogels processed with the ultrasonication had reduced oil loss and increased peroxidation stability during storage (p &lt; 0.05). Overall, this study showed that application of ultrasonication with a higher CW concentration could improve properties and storage stability of palm oil-based oleogel.

Treatment of the red tide dinoflagellate Karenia brevis and brevetoxins using USEPA-registered algaecides

The effectiveness of USEPA-registered algaecides for managing algae in lakes and reservoirs has been extensively evaluated in laboratory studies, mesocosm studies and in situ treatment. However, the use of these algaecides in marine environments for the management of dinoflagellates and associated toxins remains largely unknown. Karenia brevis is a toxic dinoflagellate that causes red tides in the Gulf of Mexico. In this study, we investigated the efficacy of six USEPA-registered algaecides, three copper-based and three peroxide-based, on treating toxic K. brevis with a natural bloom density (1.79 × 107 cells/L). Our results indicate that the application of as low as 0.31–0.34 mg Cu/L led to a significant decrease of K. brevis cells within 24 h after treatment, while peroxide-based algaecides required a relatively higher concentration for the effective removal of K. brevis cells (4.89–7.08 mg H2O2/L), but still lower than maximum label rate. Total brevetoxin levels 72 h after treatment revealed that 1.00 mg Cu/L for Algimycin® PWF, 6.48 mg H2O2/L for PAK® 27 and 7.08 mg H2O2/L for Oximycin® P5 had the greatest impact on decreasing toxin levels. The correlation analysis showed that brevetoxin reduction rate was significantly positively related with the peroxide-based algaecide exposure concentration, which is caused by the oxidation of hydroxyl radicals produced by hydrogen peroxide. The degradation dynamics of the three peroxide-based algaecides revealed that salinity, microorganisms and organic matter (≥ 0.2 μm) impact the stability of hydrogen peroxide, and Oximycin® P5 showed the highest stability among tested peroxide-based algaecides with a degradation rate of 0.467 mg/d in natural seawater. Hence, our laboratory work provided new insights into potential emergency treatment methods for immediate mitigation of K. brevis and brevetoxins. More work on the fate and persistence of algaecide active ingredients and phycotoxins, effects of site characteristics, and pilot studies on marine non-targets are still needed before safe application of this method for HABs in marine systems.

A tumor pH-responsive autocatalytic nanoreactor as a H2O2 and O2 self-supplying depot for enhanced ROS-based chemo/photodynamic therapy

Combining the internal force-driven chemodynamic therapy (CDT) and the external energy-triggered photodynamic therapy (PDT) holds great promise to achieve an advanced anticancer effect based on reactive oxygen species (ROS). However, the insufficient oxy-substrates supply in tumor microenvironment, like hydrogen peroxide (H2O2) and oxygen (O2), is the Achilles heel that greatly restricts the efficacy of this ROS-based treatment. Herein, the construction of a copper peroxide-based tumor pH-responsive autocatalytic nanoreactor (CESAR), via an albumin-mediated biomimetic mineralization strategy is described. The decoration of human serum albumin endows the nanoreactor good hydrophilicity and biocompatibility, which is highly desired for the metal-based materials. Upon exposure to acidic tumor microenvironment, CESAR presents a pH-triggered disintegration with Cu2+, H2O2 and O2 generated instantly. The generated H2O2 complements the hyperoxide deficiency and initiates a localized Fenton-like reaction with the assistance of Cu2+ for highly toxic hydroxyl radicals (•OH) production for improving CDT. The evolved O2 gas enables hypoxia relief for enhanced Ce6-mediated PDT. This H2O2/O2 self-supplying strategy significantly amplifies the tumor oxidative damage and gains an optimal treatment outcome, which offers a new paradigm for optimizing the tumor therapeutic options limited by oxide or hyperoxide deficiency, not only for CDT/PDT, but also other oxy-substrates involved strategies. Statement of significanceThe shortage of oxy-substrates in the tumor microenvironment remains a great challenge for ROS-based cancer therapy. Herein, we introduce human serum albumin as a scaffold to stabilize copper peroxide nanomaterials for constant production of H2O2 and O2 to enhance chemodynamic/photodynamic therapy. The tumor pH-triggered H2O2/O2 production and Cu2+ release are confirmed, assuring the strategy of a highly precise, effective way to destroy tumor without any side effects. This work lends new and exciting insights into the engineering design of autocatalytic oxy-substrates self-supply nanoreactor for overcoming the bottlenecks, like the oxy-substrates deficiency of CDT/PDT and the poor stability of metal peroxides, to achieve highly effective chemodynamic/photodynamic therapy.

Study on Long-Term Decomposition Conditions of Hydrogen Peroxide for Oxygen Supply to Pemfcs

Hydrogen that has high energy density is one of the main energy sources for the next generation. Polymer electrolyte membrane fuel cells (PEMFCs), which can utilize hydrogen's high energy storage density, are a very useful power source. The development of oxygen supply and storage technologies is essential for PEMFCs. Hydrogen peroxide, which has a high oxygen storage density, is present in an aqueous state at room temperature, making it easier to transport and storage in sparse oxygen environments. However, decomposition of hydrogen peroxide by catalyst has some problems. In order to reserve hydrogen peroxide, it is necessary to add stabilizers, but this causes degradation of the catalyst. We identified the effect of hydrogen peroxide stabilizers on the catalyst in the long-time decomposition reaction. The activation time of the catalyst depends not only on the materials of catalyst but also on the reactor design, and on the decomposition conditions. The effect of these variables on activation time were analyzed. As a result, the possibility of using hydrogen peroxide for long-term oxygen supply to PEMFCs was verified. We observed an improved activation time of 23 hours while maintaining an 1.6L/min oxygen flow rate. Figure 1

P332 Evaluation of the efficacy of fumigation practices on the mycological flora in the Orthopedic Operation theatre environment of a tertiary care hospital

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM ObjectivesTo determine the pre and post-fumigation prevalence of fungi in the Orthopedic Operation Theatre of a tertiary care hospital and characterization of fungal isolates.MethodThis is a prospective environmental, analytical study conducted from July 2021 to January 2022. Pre- and post-fumigation samples were taken from Ultra and Modular OT of Orthopedic department every week by passive methods of air sampling using Gravity sedimentation method (1/1/1 scheme) on SDA and also by surface sampling using swabs. The fungal load of air was measured by calculating the number of CFU per cubic meter (CFU/m3) of air by Omeliansky formula. Fumigation of OT was done with a complex formulation of stabilized hydrogen peroxide 11% w/v with silver nitrate solution 0.01% (Baccishield®).All surface samples were inoculated on SDA with chloramphenicol and all plates were incubated at 22°C and 37°C. The isolates were identified by using standard mycological procedures. Statistical analysis was done using a T-test.ResultsOut of 19 surface sampling, fumigation was found to be 100% effective only on 3 occasions (15.79%) in Ultra OT and on 7 occasions (36.84%) in Modular OT. In air sampling ≥50% reduction was found in only 4 samplings (21.05%) in Ultra OT and 10 samplings (52.63%) in Modular OT. The counts were much more than the WHO OT permissible limits. A total of 16 species of fungi were isolated belonging to 11 genera.The most common isolate was Aspergillus niger, followed by sterile hyalohyphomycetes, A. flavus, Cladosporium spp., Curvularia spp., Bipolaris spicifera, A. fumigatus, etc. in both Ultra and Modular OT.Additionally, Exophiala spp. and Fonsecaea spp. were isolated in Ultra OT.The concentrations of fungi in Ultra OT before and after fumigation were in the range 22.11-58.97 CFU/m3 and 7.37-51.59 CFU/m3, respectively. Whereas, in Modular OT, the range was 14.74-36.86 CFU/m3 and 7.37-29.48 CFU/m3, respectively. Percentage reduction of fungi following fumigation with Baccishield varied from 0% to 75% both in Ultra OT and Modular OT. The statistically correlated P-value from pre- and post-fungal concentrations in Ultra and Modular OT were found to be .002 and .0002 respectively which was found significant by T-test, albeit ineffective as per standards.ConclusionIn corroboration with our findings, Baccishield has been reported to be less effective even by other researchers. Hence, this needs to be replaced by more effective fumigants. The ineffectiveness of fumigation in Ultra OT was most probably due to the lack of HEPA filters and not strictly following up of aseptic protocols. In Modular OT improper maintenance of ACs and lack of periodic cleaning up of HEPA filters may be contributing factors.Hence, implementing more stringent, frequent, and comprehensive disinfection and cleaning procedures, educating and motivating the health care personnel can help to improve the air quality of OTs that may aid in reducing post-operative infections.

Peroxide stabilizers remarkably increase the longevity of thermally activated peroxydisulfate for enhanced ISCO remediation

Thermally activated peroxydisulfate In Situ Chemical Oxidation (TAP-ISCO) is often applied for the remediation of soil-sorbed hydrophobic organic contaminants (HOCs) and nonaqueous phase liquids (NAPLs), which act as long-term sources of groundwater contamination. TAP-ISCO benefits from improved desorption/dissolution of organic contaminants into the aqueous phase and efficient activation of peroxydisulfate at elevated temperatures, but the primary limitation of TAP-ISCO is the short lifetime of peroxydisulfate (therefore the availability of reactive radical species). To resolve this problem, coupling of peroxide stabilizers with TAP were tested. The compatibility of seven representative commercial organic and inorganic peroxide stabilizers, including sodium stannate, trisodium phosphate, sodium pyrophosphate, sodium silicate, sodium citrate, ethylene diamine tetra methylene phosphonic acid and ethylenediaminetetraacetic acid disodium salt, with TAP in aqueous solutions and solutions containing goethite or soil particles were first studied. The effects of stabilizers on the formation, distribution and reactivity of reactive oxygen species were then investigated through electron paramagnetic resonance (EPR) spin-trapping experiments using 5,5-dimethyl-1-pyrroline-N-oxide, chemical probe experiments using anisole, nitrobenzene and hexachloroethane, and biphasic trichloroethylene (TCE) dense nonaqueous phase liquids (DNAPLs) TAP-ISCO mimicking experiments. The results indicate that organic stabilizers significantly accelerate peroxydisulfate decomposition at both ambient and elevated temperatures. In contrast, inorganic stabilizers can markedly increase peroxydisulfate longevity by suppressing the acid-catalyzed peroxydisulfate decomposition, quenching radical-chain acceleration, and sequestering transition metal species. In addition, TAP systems containing inorganic stabilizers can effectively generate a variety of reactive radical species, including SO4•−, HO•, and O2•−, and improve the oxidation of anisole and nitrobenzene, though suppressing the reduction of hexachloroethane to some extent. Especially, suitable inorganic stabilizers (e.g., trisodium phosphate) can effectively improve TAP oxidation of TCE DNAPL while suppressing peroxydisulfate decomposition. Overall, this study provides the fundamental basis of coupling TAP-ISCO with peroxide stabilizers.

The efficacy of commercial decontamination agents differs between standardised test settings and research laboratory usage for a variety of bacterial species.

Decontamination of surfaces and items plays an important role in reducing the spread of infectious microorganisms in many settings including hospitals and research institutes. Regardless of the location, appropriate decontamination procedures are required for maintaining biosafety and biosecurity. For example, effective decontamination of microbial cultures is essential to ensure proper biocontainment and safety within microbiological laboratories. To this end, many commercial decontamination agents are available which have been tested to a prescribed standard to substantiate their efficacy. However, these standardised tests are unlikely to accurately reflect many conditions encountered in medical and biomedical research. Despite this, laboratory workers and other users of decontamination agents may assume that all decontamination agents will work in all situations. We tested commonly used commercial decontamination agents against a range of bacterial species to determine their efficacy under real-world research laboratory conditions. As each decontamination agent has a different recommended dilution for use, to compare their efficacy we calculated their ‘effective ratio’ which reflects the difference between the manufacturer-recommended dilution and the dilution needed to achieve decontamination under real-world research laboratory conditions. Effective ratios above one indicate that the agent was effective at a dilution more dilute than recommended whereas effective ratios lower than one indicate that the agent required a higher concentration than recommended. Our results show that the quaternary ammonium agents TriGene Advance and Chemgene HLD4L were the most effective out of the agents tested, with biocidal activity measured at up to 64 times the recommended dilution. In contrast, hypochlorite (bleach) and Prevail™ (stabilised hydrogen peroxide) had the lowest effective ratios amongst the tested agents. In conclusion, our data suggests that not all decontamination agents will work at the recommended dilutions under real-world research laboratory conditions. We recommend that the protocols for the use of decontamination agents are verified under the specific conditions required to ensure they are fit for purpose.

Formulations of selected Energy beverages promote pro-oxidant effects of ascorbic acid and long-term stability of hydrogen peroxide

Recently, autoxidation mediated by ascorbic acid (AA) and other ingredients, has been implicated in generation of hydrogen peroxide (H2O2) in so-called Energy beverages. Here, we report the use of cyclic voltammetry and the FOX assay to monitor at short and long incubation times, respectively, the production and stability of H2O2 generated by AA and redox-active ingredients. Levels of H2O2 in Energy drinks (36.5 ± 4.0 µM at 4 °C and 64.2 ± 7.6 µM at 20 °C) were found to be stable or increased (p < 0.05) upon vessel opening. A predictive model for the production of H2O2 as a function of AA concentration, temperature and incubation time, and depending on ingredients present, indicated that H2O2 peaked at 91–726 µM after 1 day and declined to ∼ 42–60 µM (4 °C) or zero after ∼10 days. The research supports that levels of H2O2 in beverages containing anti-oxidant mixtures and dissolved oxygen should be monitored and formulations modified to avoid AA autoxidation.

Aqueous decomposition behavior of solid peroxides: Effect of pH and buffer composition on oxygen and hydrogen peroxide formation

The ability of solid peroxides to provide sustained release of both oxygen and hydrogen peroxide makes them potentially suitable for oxygen release or antibacterial applications. Most recent reports using solid peroxides to augment oxygen levels do so by compounding solid peroxide powders in polymers to retard the aqueous decomposition. Compounds with peroxidase activity may be added to reduce hydrogen peroxide toxicity. Peroxides are rarely pure and are mixed with oxide and themselves decompose to form hydroxides in water. Therefore, even if buffering strategies are used, locally the pH at the surface of aqueously immersed peroxide particles is inevitably alkaline. Since pH affects the decomposition of peroxides and hydrogen peroxide stability, this study compared for the first-time the aqueous decomposition products of hydrogen and inorganic peroxides that are in use or have been used for medical applications of have been evaluated preclinically; calcium peroxide (CaO2), magnesium peroxide (MgO2), zinc peroxide (ZnO2), sodium percarbonate (Na2CO3.1.5H2O2) and hydrogen peroxide (H2O2). Since plasma can be approximated to be carbonate buffered phosphate solution, we maintained pH using carbonate and phosphate buffers and compared results with citrate buffers. For a given peroxide compound, we identified not only a strong effect of pH but also of buffer composition on the extent to which oxygen and hydrogen peroxide formation occurred. The influence of buffer composition was not previously appreciated, thereby establishing in vitro parameters for better design of intentional release of specific decomposition species. Statement of significanceThis paper compares for the first time the aqueous decomposition products oxygen and hydrogen peroxide of solid peroxy compounds of metal cations, (calcium, magnesium, sodium and zinc) across a pH range that could feasibly be found in the body, (pH 5,7, 9) either physiologically or pathologically. We find that in addition to pH, buffer composition is also a critically important factor, making translation from in vitro models challenging. Cytotoxicity was related to hydrogen peroxide release, alkalinity and in the case of zinc peroxide to the cation itself. In vitro and preclinical studies generally report release data from polymer-peroxide composites and rarely compare peroxides with one another. Together our data provide guidance for oxygen and ROS delivery from these inorganic materials.

On the stabilization of organic peroxides by plasticizers: Quantum chemical study on interactions of 2,2-dihydroperoxybutane with dimethyl Phthalate

In this paper we would present our studies how organic peroxides are being stabilized by plasticizers used in manufacturing of organic peroxides as polymerization initiators etc. As an exemplary system, interactions between 2,2-dihydroperoxybutane and dimethyl phthalate (system already approved for commercial use) has been studied. The quantum chemical study protocol was to investigate for the first time the interactions between a plasticizer and the peroxide – indicating that the interaction energy of about -15 kcal/mol favors the formation of a supramolecular system.