Search results for "hydrogen peroxide"
showing 10 items of 321 documents
Prevention of fungal infestation of rainbow trout (Oncorhynchus mykiss) eggs using UV irradiation of the hatching water
2013
Abstract Fungal infestation by water mold Saprolegnia spp. causes great losses in aquaculture and fish egg hatching. To find a safe and effective alternative for the fungal prevention, we studied continuous disinfection of the inlet water by UV irradiation and ozonation combined with low concentration hydrogen peroxide (H 2 O 2 ) treatments in a rainbow trout ( Oncorhynchus mykiss ) egg hatching system. High dose of UV irradiation (400 mWs/cm 2 ) of the inlet water decreased the mortality of rainbow trout eggs from the 77.3% to 14.3% in a 28 day trial. UV irradiation did not modify water quality parameters, while combination of UV irradiation and H 2 O 2 caused up to fivefold increase in th…
Blanqueamiento vital domiciliario: comparación de tratamientos con peróxido de hidrógeno y peróxido de carbamida
2006
El blanqueamiento de los dientes vitales que realiza el/la paciente domiciliariamente con férulas bajo supervisión del/de la dentista es una alternativa interesante entre las que integran este tipo de terapéutica odontológica, ya sea, de forma aislada o combinada con alguna de las modalidades de tratamiento en la consulta. En este procedimiento blanqueador se usan peróxidos de baja concentración que se aplican sobre el esmalte dentario mediante una cubeta individualizada especialmente diseñada para ello. El objetivo del presente trabajo es analizar y comparar dos productos blanqueadores comerciales de diferente concentración indicados para esta técnica, VivaStyle (Vivadent) y FKD (Kin); el …
Effect of pressure on the electrochemical generation of hydrogen peroxide in undivided cells on carbon felt electrodes
2017
The electrochemical generation of H2O2can be performed in aqueous solutions by cathodic reduction at carbonaceous cathodes of oxygen coming from air. The performances of the process in terms of concentration of H2O2and current efficiency (CE) are limited by the low solubility of oxygen in water at atmospheric pressure. However, the solubility of oxygen can be increased upon enhancing the air pressure. The effect of pressure on the electrochemical generation of hydrogen peroxide was studied in undivided cells changing the pressure from 0 to 30 relative bar and the current density from 1 to 100Â mAÂ cmâ2. Simple carbon felt and compact graphite cathodes were first used. A dramatic effect of…
The catalytic-thermometric determination of molybdenum in steels based on the hydrogen peroxide-iodide indicator reaction
1990
Abstract The Mo VI -catalysed hydrogen peroxide-iodide reaction has been optimised for thermometry in an HCl medium using the initial slope method. The substitution of sodium perborate by H 2 O 2 and the conversion of the reaction to a process showing a Landolt effect are considered and discussed. The linear range extended from 0.2 μg Mo VI ml −1 to 1.2 μg Mo VI ml −1 with a detection limit of 0.06 μg Mo VI ml −1 . Interferences were also studied. The optimised procedure was applied to the evaluation of molybdenum in steels after extraction with α-benzoinoxime in chloroform.
Electrocatalytic Properties of Carbosilane‐Based Hyperbranched Polymers Functionalized with Interacting Ferrocenyl Units
2012
Two types of hyperbranched ferrocene-containing polycarbosilanes were obtained by hydrosilylation of polydiallylmethylsilane (hb-PDAMS) and polymethyldiundecenylsilane (hb-PMDUS) with diferrocenylmethylsilane. The redox properties of both polymers have been investigated both in solution and confined onto platinum electrodes. The electrocatalytic activity of polymer-modified electrodes toward the reduction of oxygen as well as the electrochemical reduction and oxidation of hydrogen peroxide has been examined.
Functional Enzyme Mimics for Oxidative Halogenation Reactions that Combat Biofilm Formation
2017
Transition-metal oxide nanoparticles and molecular coordination compounds are highlighted as functional mimics of halogenating enzymes. These enzymes are involved in halometabolite biosynthesis. Their activity is based upon the formation of hypohalous acids from halides and hydrogen peroxide or oxygen, which form bioactive secondary metabolites of microbial origin with strong antibacterial and antifungal activities in follow-up reactions. Therefore, enzyme mimics and halogenating enzymes may be valuable tools to combat biofilm formation. Here, halogenating enzyme models are briefly described, enzyme mimics are classified according to their catalytic functions, and current knowledge about th…
Virucidal effect of high power ultrasound combined with a chemical sanitizer containing peroxyacetic acid for water reconditioning in the fresh-cut i…
2015
The use of chlorine-based sanitizers is widespread throughout the fresh produce industry in the process water to maintain microbial safety of produce, avoid cross-contamination and recycle water. In this study, alternative disinfection technologies were investigated due to the negative reports showing chlorine instability in the presence of organic matter and the undesirable by-product residues. Tsunami ® (15.2% peroxyacetic acid and 11.2% hydrogen peroxide) and high-power ultrasound (HPU, 0.56 kW/l, 20 kHz), alone or in combination, were evaluated in lettuce process water analyzing their ability to reduce MNV during either produce washing or water recycling. PAA concentrations of 6.4, 12.8…
The immunosuppressive enzyme IL4I1 promotes FoxP3+regulatory T lymphocyte differentiation
2015
Abstract IL4I1 (interleukin-4-induced gene 1) is a phenylalanine oxidase produced mainly by APCs of myeloid origin, and converts phenylalanine (Phe) to phenylpyruvate, hydrogen peroxide, and ammonia. We have previously shown that IL4I1 is highly expressed by tumor-associated macrophages from various human cancers and facilitates immune evasion from the cytotoxic response in a murine tumor model. Indeed, IL4I1 inhibits T-cell proliferation via hydrogen peroxide toxicity on effector/memory T cells. Here, we explored the effect of IL4I1 on naive CD4(+) T-cell differentiation. We show that IL4I1 stimulates the generation of Foxp3(+) regulatory T (Treg) cells in vitro from human and mouse T cell…
Chemoenzymatic synthesis of a poly(hydroquinone)
1999
Chemoenzymatic synthesis of a poly(hydroquinone) was achieved by enzymatic oxidative polymerization of 4-hydroxyphenyl benzoate, followed by alkaline hydrolysis of the resulting polymer. The polymerization of 4-hydroxyphenyl benzoate was performed using a peroxidase and hydrogen peroxide as catalyst and oxidizing agent, respectively, in an aqueous organic solvent. Soybean peroxidase afforded the polymer in good yields. IR analysis of the polymer showed the formation of the polymer consisting of a mixture of phenylene and oxyphenylene units. By alkaline hydrolysis of the resulting polymer, benzoate moiety was completely removed to give poly(hydroquinone).
Electrochemical sensor for evaluating oxidative stress in airway epithelial cells
2021
Cigarette smoke exposure induces oxidative stress within the airways. Increased oxidative burden contributes to the pathogenesis of chronic lung disorders and is associated with aging and chronic inflammation. Airway epithelial cells highly contribute to Reactive Oxygen Species (ROS) generation within injured and inflamed lung tissues. Among ROS, hydrogen peroxide (H2O2) can be monitored in the extracellular space. Herein, we present an amperometric/voltammetric sensor based on gold nanoparticles and graphene oxide able to detect H2O2 with good sensitivity and selectivity. Using this sensor, H2O2 release was measured in conditioned medium from primary bronchial epithelial cells (PBEC), bron…