Oxido-reductive process

Oxido-reduction processes may come into play, for example, by closing or opening a ring when disulfide bridges are present ... 

Conflicting data, due to studies performed on mixtures of compounds in which different oxidation states were present (oxido-reduction processes occur easily, especially in the presence of air657-659) are reported. 

Selective Oxido-Reductive Processes by Nucleophilic Radical Addition under Mild Conditions... 

The conclusion is thus that attention should be given to the local arrangement of limited numbers of atoms which permit the selective reaction and to mechanisms which maintain these structures intact in spite of the oxido-reduction process which continusouly tends to put this structure upside down. 

In this oxido-reduction process, aluminum metal is oxidized and the anodic reactions can be represented as ... 

It was found that the action of OH radicals on nitrobenzene or benzoic acid produced all the three isomeric phenolic compounds. OH radicals produced, for example, by reaction (1) can be used to generate other free radicals or atoms from inorganic or organic compounds. These reactions have been studied more recently by Kolthoff and Medalia (13), Merz and Waters (46), Stein and Weiss (45), and others. Reaction (1) also proved useful in the study of the so-called active oxalic acid (47). The free radical mechanism of hydrogen peroxide has been discussed also in connection with the mechanism of the action of the enzymes catalase and peroxydase, the prosthetic groups of which are iron porphyrin complexes which presumably also undergo oxido-reduction processes in the course of their catalytic activity (48). 

Relatively far from the present topic and well known, the on-line measurement of the physical and aggregate properties of wastewater does not present any problem. Conductivity, temperature, turbidity and oxido-reduction potential (ORP) are easily measured by well-designed sensors, because these parameters are also used for treatment process control. In practice, turbidity is more used for the treatment of natural water, and ORP for the biological treatment of wastewater. However, conductivity and temperature are often monitored at the same time as the other parameters in this section. 

Oxidoreductases comprise a large class of enzymes that catalyze biological oxidation/reduction reactions. Because so many chemical transformation processes involve oxidation/reduction processes, the idea of developing practical applications of oxidoreductase enzymes has been a very attractive, but quite elusive, goal for many years [83], Applications have been sought for the production of pharmaceuticals, synthesis and modification of polymers, and the development of biosensors for a variety of clinical and analytical applications [83], In recent years, the use of oxido-reductive enzymes to catalyze the removal of aromatic compounds from... 

In this scenario, the next key step was the discovery by early living organisms of alternative pathways to synthesize nucleoside triphosphates (stage 3 in Scheme 40), for instance by the introduction of an oxido-reduction metabolism. In the particular case of ATP, the increase in its concentration could have forced the chemical flux of the system to be reverted since the unstable adenylate anhydride was stabilized in the active site of the adenylate binding protein (E) allowing the activation of amino acids by ATP through the process that became predominant. 

Fig. 13. Schematic representation of the oxido-reduction steady-state process during a non-deactivated catalytic oxidation on M0O3,...

All these results are related to observations and measurements in the field as well as from oxalotrophic bacterial cultures in the laboratory (Braissant et al, 2004). There is no theoretical model available to explain the oxalate-carbonate transformation and its consequences on the soil solution properties, i.e. alkalinization facilitating precipitation of calcium carbonate (CaCOs) and CO2 release into the atmosphere. This kind of model should be able to explain the process of oxido-reduction reactions, pH regulation and the evolution of the various phase concentrations involved in the system, i.e. oxalate, carbonate, water and CO2. This is the aim of the next section. 

Electroless deposition can be defined as a deposition of solid phase of continuous coatings (films) or powders of metals, alloys, or compounds from aqueous or nonaqueous solutions or melts without an external current source. Based on this definition, electroless deposition is a purely chemical process, which involves oxido-reduction... 

The main differences between mobile and fixed types of carriers (see refs. 33, 37, 53, 60-63) have been well summarised in the context of electron and hydrogen transport through the respiratory chain by Chance et They compared the current flow and fluid flow models of Holton and Lunde-gardh with the normal kinetic oxido-reduction model, and pointed out that the latter consists of a series of bimolecular reactions, while the former is equivalent to a unimolecular process. Hence, in the fixed carrier model there is effectively a single chemical channel, whereas in the bimolecular or circulating mobile carrier model there are two chemical channels. 

These calculations must be accepted with caution. In fact they imply values which may in some cases only be approached rather than attained. For example the P/O ratio in the course of oxidative phosphorylations. Moreover they assume a perfect coupling between phosphorylations and oxido-reductions. In practice numerous factors bring about the uncoupling of these two processes, examples are dinitrophenol and thyroxine. There are good reasons to believe that even in a given species the eiEciency of coupling varies from one individual to another. 

The formation of acetyl lipoic acid-enzyme complex by internal oxido-reduction and rearrangement (see equation 3 on p. 36) is a process which is similar in principle to the enolase reaction. 

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