Search results for "OXIDATION"
showing 10 items of 1913 documents
Opportunity of metallic interconnects for ITSOFC : Reactivity and electrical property.
2006
International audience; Iron-base alloys (Fe-Cr) are proposed hereafter as materials for interconnect of planar-type intermediate temperature solid oxide fuel cell (ITSOFC); they are an alternative solution instead of the use of ceramic interconnects. These steels form an oxide layer (chrornia) which protects the interconnect from the exterior environment, but is an electrical insulator. One solution envisaged in this work is the deposition of a reactive element oxide coating, that slows down the formation of the oxide layer and that increases its electric conductivity. The oxide layer, formed at high temperature on the uncoated alloys, is mainly composed of chromia; it grows in accordance …
Methods for Enhancing the Thermal Durability of High-Temperature Thermoelectric Materials
2013
Author's version of an article in the journal: Journal of Electronic Materials. Also available from the publisher at: http://dx.doi.org/10.1007/s11664-013-2917-0 Thermoelectric materials, for example skutterudites and magnesium silicides, are being investigated as promising materials for medium-to-high-temperature waste heat recovery in transport and in industry. A crucial aspect of the success of a thermoelectric material is its stability over time when exposed to rapid heating and cooling. In this work different aspects of the degradation of these thermoelectric materials at high temperature were examined. Initial thermal durability was studied, and several candidate coatings were evaluat…
Effect of Pulse Current Mode on Microstructure, Composition and Corrosion Performance of the Coatings Produced by Plasma Electrolytic Oxidation on AZ…
2019
Plasma electrolytic oxidation (PEO) coatings were grown on AZ31 Mg alloy in a silicate-based electrolyte containing KF using unipolar and bipolar (usual and soft-sparking) waveforms. The coatings were dual-layered consisting of MgO, MgF2 and Mg2SiO4 phases. Surface morphology of the coatings was a net-like (scaffold) containing a micro-pores network, micro-cracks and granules of oxide compounds. Deep pores were observed in the coating produced by unipolar and usual bipolar waveforms. The soft-sparking eliminated the deep pores and produced the lowest porosity in the coatings. It was found that the corrosion performance of the coatings evaluated using EIS in 3.5 wt. % NaCl solution is mostly…
CO2 reduction by C3N4-TiO2 Nafion photocatalytic membrane reactor as a promising environmental pathway to solar fuels
2019
Abstract We investigated CO2 photocatalytic reduction coupling, for the first time in literature, the assets offered by the continuous operating mode using C3N4-TiO2 photo-catalyst embedded in a dense Nafion matrix. The reactor performance was analyzed under UV–vis light in terms of productivity, selectivity and converted carbon. Reaction pressure was specifically investigated for its effect as a “driver” in determining reactor performance, modulating products removal from the reaction volume. In addition, the membrane reactor performance was explored as a function of H2O/CO2 feed molar ratio and contact time. The higher feed pressure (5 bar) led to a lesser MeOH production and a greater am…
Essential oils as natural additives to prevent oxidation reactions in meat and meat products: A review
2018
Oxidation reactions during manufacturing, distribution, and storage of meat and meat products result in undesirable physicochemical changes and aromas, which leads to detrimental effects on the product quality. This could be translated into the consumer dissatisfaction and economic loss. One of the most common practices to overcome this issue is the incorporation of synthetic antioxidants. However, the increasing health-consciousness of consumers and their preference for natural additives leads to the search of natural alternatives to synthetic antioxidants. A number of essential oils have strong antioxidant properties and are explored as potential alternatives to chemical antioxidants in t…
Active packaging films with natural antioxidants to be used in meat industry: A review.
2018
Spoilage of meat products during processing, distribution and exposure in the markets have an important negative impact on meat industry from an economic point of view. Two of the main problems of meat and products during processing and subsequent storage are lipid oxidation and deterioration due to microorganism growth. In this context, several packaging alternatives have been developed by meat industry in order to limit these losses and to extend the meat products´ shelf life. Over the last years, the use of active packaging has been proposed as an alternative to traditional packaging. The principle of active packaging, particularly antioxidant active packaging, consists of including acti…
Self-assembly of catalytically-active supramolecular coordination compounds within metal-organic frameworks
2019
[EN] Supramolecular coordination compounds (SCCs) represent the power of coordination chemistry methodologies to self-assemble discrete architectures with targeted properties. SCCs are generally synthesized in solution, with isolated fully coordinated metal atoms as structural nodes, thus severely limited as metal-based catalysts. Metal-organic frameworks (MOFs) show unique features to act as chemical nanoreactors for the in situ synthesis and stabilization of otherwise not accessible functional species. Here, we present the self-assembly of Pd-II SCCs within the confined space of a pre-formed MOF (SCCs@MOF) and its post-assembly metalation to give a Pd-II-Au-III supra molecular assembly, c…
Anti-proliferative and pro-apoptotic activities of hydroxytyrosol on different tumour cells: the role of extracellular production of hydrogen peroxide
2011
Several recently published data suggest that the anti-proliferative and pro-apoptotic properties of hydroxytyrosol [3,4-dihydroxyphenyl ethanol (3,4-DHPEA)] on HL60 cells may be mediated by the accumulation of hydrogen peroxide (H2O2) in the culture medium. The aim of this study was to clarify the role played by H2O2 in the chemopreventive activities of 3,4-DHPEA on breast (MDA and MCF-7), prostate (LNCap and PC3) and colon (SW480 and HCT116) cancer cell lines and to investigate the effects of cell culture medium components and the possible mechanisms at the basis of the H2O2-producing properties of 3,4-DHPEA. The proliferation was measured by the MTT assay and the apoptosis by both fluores…
Protective effect of melatonin against cytotoxic actions of malondialdehyde: an in vitro study on human erythrocytes
2002
Malondialdehyde (MDA), a by-product of the oxidation of polyunsaturated fatty acids, is strongly cytotoxic. Here we report the in vitro ability of melatonin to protect intact human erythrocytes against the damage induced by the exposure to MDA. MDA at 20 microM caused marked variations in the red blood cell (RBC) membrane. High molecular weight fluorescent adducts were formed within minutes with membrane proteins. A 6-hr incubation led to the oxidation of membrane lipids, as reflected by the formation of conjugated diene (CD) lipid hydroperoxides and oxidation of vitamin E, and to an increase of the high molecular weight fluorescent adducts, which were an indication of MDA finally generated…
Protective effect of bioaccessible fractions of citrus fruit pulps against H2O2-induced oxidative stress in Caco-2 cells
2017
Fruit pulps from Navel (N) and Cara Cara (CC) oranges, and Clementine mandarin freshly harvested (M) and refrigerated stored (M12) were used to evaluate the cytoprotective effect of their bioaccessible fractions (BF) against H2O2-induced oxidative stress in Caco-2 cells. BF of samples preserved viability vs. H2O2 treated cells, reaching values similar to controls. Lipid peroxidation was reduced to levels of control cells, but M did not reach control values. ROS and mitochondrial membrane potential changes (Δψm) values were reduced compared with H2O2 treated cells, but without achieving control levels. A significant reduction in cell proportions in G1 phase and a significant increase in sub-…