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Characteristics and Behavior of Fire
Published in Peter M. Bochnak, Fire Loss Control, 2020
The chemistry of fire involves the combining of a combustible material with oxygen, called oxidation. The rusting of iron and steel is an example of a very slow form of oxidation. Fire or combustion is the rapid oxidation of a material accompanied by heat and usually light. The oxidation reaction involved is exothermic, which means that energy is being released in the form of heat, as opposed to an endothermic reaction, in which energy is absorbed. To have this rapid oxidation, called fire or combustion, certain elements must be present: A combustible material, also called fuel.An oxidizing agent; in most cases, oxygen in our atmosphere.A specific temperature; fuel must be raised to this temperature so that the heat input will be sufficient to sustain combustion.
Contact Design and Attachment
Published in Paul G. Slade, Electrical Contacts, 2017
Gerald J. Witter, Guenther Horn
For larger quantity brazed contact assemblies, a continuous brazing process can be used, called “Toplay.” This brazing process is popular for making contact assemblies for small contactors and definite purpose relays. In this process the contact material in strip form and the copper carrier strip are fed into a small tube furnace with or without a brazing filler material. The furnace is designed to apply induction or resistance heating to the strip sandwich and also applies a force pushing the laminations together as the metal interface melts while moving through the tube furnace. A protective atmosphere can also be used to prevent oxidation. For example, with this process it is possible to braze small width silver metal oxide strips which have a silver backing directly onto copper strip by heating and applying pressure to the interface joint, forming a low melting silver–copper eutectic alloy at the interface, and cooling the interface in the last zone of the furnace while it is still under pressure. This results in a high percentage bond area which is almost void free. After the bonding step of this process the toplay laminated strip can be profile rolled to adjust the assembly thickness and restore some hardness to the materials. The last step in the process is to form the individual contact assemblies by stamping them in a progressive forming die.
Monitoring and Analysis
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
In oxidation-reduction reactions, the substances involved gain or lose electrons and show different electron configurations before and after the reaction. Oxidation is the overall process by which a specie in a chemical reaction loses one or more electrons and increases its state of oxidation. An oxidant is a substance capable of oxidizing a chemical specie; it acquires the electron or electrons lost by the specie and is itself reduced in the overall process. Reduction is the overall process in which a specie in a chemical reaction gains one or more electrons and decreases its state of oxidation. A reductant is a substance capable of reducing a chemical specie; it loses the electrons gained by the specie and is itself oxidized in the overall process.
Orange slice drying enhancement by intervention of control atmosphere coupled with vacuum condition—A new design and optimization strategy
Published in Drying Technology, 2023
Hamed Homayounfar, Reza Amiri Chayjan, Hassan Sarikhani
The color, taste, nutritional properties, and even texture of food products change by oxidation.[9,10] This process is one of the most important agents for food quality reduction during drying because of oxygen abundance in the dryer chamber.[7,11] Although the vacuum dryer reduces the oxygen density around the sample, there would be sufficient oxygen molecules in the dryer chamber to carry out the oxidation reaction.[12] In this regard, some advanced air drying technologies and apparatuses have been developed to compensate for some limitations in operating conventional dryers. The advantages of these tools are improved and upgraded rather than making remarkable changes. One solution to avoid adverse oxidation reactions is to inject N2 gas into the drying chamber instead of air.[8,9,13,14] This method improves some qualitative properties to reduce adverse reactions.[15–17]
Production of biodiesel by electrolysis method from waste cooking oil using heterogeneous MgO-NaOH nano catalyst
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Atlas Rafati, Kambiz Tahvildari, Maryam Nozari
Iodine number represents the unsaturated bonds in the fuel composition. The degree of saturation, determined by measuring the iodine number, is one of the important characteristics for the selection of methyl esters. The presence of unsaturated bonds in biodiesel is necessary to prevent freezing. Unsaturation degree of over the limit reduces cetane number, lowers resistance to oxidation, polymerization, and decreases freezing point. Antioxidants can be used to prevent oxidation. The iodine number of the biodiesel prepared in this work (81) found using Equation 2, is within the limits of EN standards.
Syntheses, X-ray crystal structures and catalytic epoxidation of oxidovanadium(V) and dioxidomolybdenum(VI) complexes derived from N′-(4-Bromo-2-hydroxybenzylidene)benzohydrazide
Published in Inorganic and Nano-Metal Chemistry, 2021
Qian Wang, Zhong-Duo Xiong, Liu Liu, Ya-Jun Cai
Oxidation of organic compounds is an important reaction in the chemical industry. Oxidation reactions are essential for the production of oxygenated species which allow access to a variety of organic compounds. In general, most oxidation reactions are very slow in the absence of catalysts, the catalytic oxidation of organic substrates by transition metal complexes has become an important research area in organic synthesis and bioinorganic modeling of oxygen transfer metalloenzymes.[1] A number of complexes with various ligands have been used as homogenous or heterogeneous catalysts in various oxidation systems.[2–5] Among the complexes, those derived from Schiff bases are of particular interest because of their facile synthesis and potential biological, catalytic and magnetic applications.[6–12] Catalytic epoxidation of olefins is an important type of reactions in oily and industrial chemistry. Increasing catalytic activity and selectivity is one of the challenges in chemical science and it has attracted considerable attention in recent decades. In recent years, vanadium and molybdenum complexes have received much attention because of their effective catalytic ability in the oxidation of olefins and sulfides.[13–18] Vanadium and molybdenum complexes with hydrazone ligands are reported to have catalytic properties. In order to explore new and efficient catalysts for the epoxidation of olefins, and to study the catalytic property of the vanadium and molybdenum complexes derived from the same ligand, in this paper, a new oxidovanadium(V) complex and a new dioxidomolybdenum(VI) complex [VOL(OCH3)(CH3OH)] (1) and [MoO2L(CH3OH)] (2), derived from N′-(4-bromo-2-hydroxybenzylidene)benzohydrazide (H2L, Scheme 1) are presented.