Reduction equivalent

Reductant equivalent weights of, 847 Reduction 409 by chromium(II) salts, 409 by hydrogen sulphide, 416 by Jones reductor (zinc amalgam), 410 by liquid amalgams, 412 by silver reductor, 414 by sulphurous acid, 416 by tin(II) chloride, 415 by titanium(II[), 410 by vanadium(II), 410 see also Iron(III), reduction of Reduction potentials 66 Reference electrodes potentials, (T) 554 Relative atomic masses (T) 819 Relative error 134 mean deviation, 134... 

A polymer of the polyacrylamide type was injected as a 0.5% solution from an axially-placed nozzle at the bellmouth entrance. The experiments showed that the central thread provided drag reduction almost equivalent to premixed solutions of the same total polymer concentration flowing in the pipe. Overall concentrations of 1, 2, 4, and 20 ppm were used. Moreover, the effects were additive 2 ppm thread overall concentration plus 2 ppm premixed gave drag reductions equivalent to 4 ppm of either type. Reynolds numbers of up to 300,000 were investigated. In other experiments, a number of different polymer fluids were injected on the centerline of a water pipe-flow facility [857]. Two distinct flow regions were identified ... 

The oxidative formation of pyrite from iron and hydrogen sulphide supplied the reduction equivalents vital for the fixation of the carbon to be used in the synthesis of key molecules from simple building blocks (such as CO or CO2). 

A fundamental question for all reactions which could have been involved in the early phase of chemical evolution is that of the origin of the reduction equivalents necessary for the autotrophic synthesis. For example, the synthesis of one molecule of glucose from carbon dioxide requires 24 electrons, while the synthesis of the amino acid cysteine requires as many as 26 electrons per molecule of amino acid ... 

A carrier molecule containing four carbon atoms (the C4 unit) takes up a C2 unit (the activated acetic acid ), which is introduced into the cycle. The product is a six-carbon molecule (the C6 unit), citric acid, or its salt, citrate. CO2 is cleaved off in a cyclic process, so that a C5 unit is left this loses a further molecule of CO2 to give the C4 unit, oxalacetate. In the living cell, this process involves ten steps, which are catalysed by eight enzymes. However, the purpose of the TCA cycle is not the elimination of CO2, but the provision of reduction equivalents, i.e., of electrons, and... 

This overall reaction equation points to the fact that copper phthalocyanine formation formally requires two reduction equivalents. 

In redox reactions, protons (H" ) are often transferred along with electrons (e ), or protons may be released. The combinations of electrons and protons that occur in redox processes are summed up in the term reduction equivalents. For example, the combination 1 e /l corresponds to a hydrogen atom, while 2 e and 2 together produce a hydrogen molecule. However, this does not mean that atomic or molecular hydrogen is actually transferred from one molecule to the... 

In the next reaction, the OH group at C-3 is oxidized to a carbonyl group dehydrogenation). This gives rise to p-ketoacyl CoA, and the reduction equivalents are transferred to NAD"", which also passes them on to the respiratory chain. 

The replenishment of the vacancy can be directly from the gas phase or indirectly from the catalyst. In the latter case, the oxygen mobility within the catalyst is so large that bulk oxygen can diffuse to the vacancy. Then oxygen from the gas phase reoxidizes the lattice on sites which differ from hydrocarbon reaction sites. In a steady state, the rate of catalyst oxidation will be equal to the rate of reduction by the substrate. The steady state degree of reduction, equivalent to the surface coverage with oxygen, is determined by the ratio of these two rates. Kinetic models based on these principles are called redox models, for which the simplest mathematical expression is... 

The hydroperoxide (two isomers) is formed in high yield under these conditions (the nature of the reduction equivalent that is required for this process is as yet not known), and subsequent treatment with a base gives rise to glycolic acid and the base propenal [Grob fragmentation reaction (292) yields near 90%]. 

In the presence of GSH, 5 -d(T4AT7) and 5 -d(T4A) are formed [reactions (20) and (21)]. In the presence of 02, the primary radical is trapped by 02. In a subsequent step, the C(4 ) peroxyl radical is reduced to the corresponding hydroperoxide (the source of the reduction equivalent is as yet unknown potentially 02 generated in side reactions), and treatment with NH3 increases the yield of the glycolate which is also formed upon the bimolecular decay of the peroxyl radial [reactions (23)-(25)]. 

The PPC allows the generation of NADPH reduction equivalents required for cell anabolism, and ribose 5-phosphate molecules for the synthesis of nucleic acids. Alternatively, ribose 5-phosphate can also be generated or transformed into fructose 6-phosphate or glyceraldehyde 3-phosphate, providing metabolic flexibility to the cell, in order to balance the fluxes through these pathways. The flux through the PPC is related to the nucleic acid requirements for DNA duplication or RNA transcription, and could probably be controlled by the cell cycle (Wagner, 1997). 

Cu(II) ions were reduced and fully reoxidized within 1—2 sec, although under these conditions no more than a single reduction equivalent may be in those molecules. This is not the case when reduction of these sites take place anaerobically by, for example, the C02" radical ion. 

In the presence of molecular oxygen, and only then, the type 1 copper is reoxidized in a first-order process. The type 1 copper is generally thought to be deeply embedded inside the protein, therefore a direct interaction between oxygen and this copper site is improbable. This, together with the fact that no laccase molecule contained more than one reduction equivalent suggests the following ... 

The reduction equivalents required for conversion of N2 to NH3 are obtained from the carbanionic phenyl groups bonded to nickel in 14 (biphenyl formation). The Ni atoms, which are still present as Ni(0), i.e., in the form of metallic nickel after hydrolysis, only function as agents for the transfer of electrons from C6H5 to N2. In this respect, the hydrolysis of... 

Natural photosystems have been extensively studied and the machinery of photosynthesis found to be highly modular, organized on multiple scale levels and compartmentalized.32 Importandy, all natural photosystems are molecule-based and their function can be understood both at the schematic level and, in many cases, at the molecular-level. Highly specialized components interact in controlled manner to ultimately deliver a product (reduction equivalents) and to effectively deal with waste (oxidation equivalents). 

---