scholarly journals New donor–acceptor conjugates based on a trifluorenylporphyrin linked to a redox–switchable ruthenium unit

2015 ◽  
Vol 44 (20) ◽  
pp. 9470-9485 ◽  
Author(s):  
Areej Merhi ◽  
Xu Zhang ◽  
Dandan Yao ◽  
Samuel Drouet ◽  
Olivier Mongin ◽  
...  
Keyword(s):  
Oxidation Process ◽  
Redox States ◽  
Reduction Processes ◽  
Donor Acceptor

Spectroelectrochemical studies show four accessible redox states on dyad 3 with the first oxidation process taking place at the Ru(ii) centre and the second oxidation and first reduction processes at the porphyrin centre.

scholarly journals THE FORMATION OF METHEMOGLOBIN BY STREPTOCOCCUS VIRIDANS

1916 ◽  
Vol 24 (4) ◽  
pp. 315-327 ◽  
Author(s):  
Francis G. Blake
Keyword(s):  
Blood Cells ◽  
Chemical Nature ◽  
Oxidation Process ◽  
Streptococcus Viridans ◽  
Bacterial Cells ◽  
Active Oxidation ◽  
Oxidation Processes ◽  
Reduction Processes ◽  
Methemoglobin Formation ◽  
Metabolic Activities

Cultures of Streptococcus viridans when brought into contact with red blood corpuscles have the power of transforming oxyhemoglobin into methemoglobin. The reaction occurs only in the presence of living streptococci when they are able to carry on their metabolic activities. The intensity of the reaction runs roughly parallel with the period of growth and multiplication of the bacteria and gradually diminishes and disappears as growth ceases. There is no apparent relation between the activity of a given strain of Streptococcus viridans in producing methemoglobin and its source or virulence. If the streptococci are suspended in salt solution they are unable to change oxyhemoglobin into methemoglobin unless some nutrient substance is present. Of the various nutrient substances tested dextrose is the most efficient in enabling the organisms to bring about the reaction. The reaction does not occur in the absence of oxygen, and is retarded by an excess of oxygen. Substances which tend to reduce the metabolic activities of the bacteria to a minimum exert an inhibitory action on methemoglobin formation. While not definitely proving it to be so, the results obtained in the above experiments strongly support the supposition that the reaction is not due to injurious substances produced by the bacteria or to products arising from the decomposition of the nutrient material present, but rather to the metabolic activities of the bacteria themselves when they are surrounded by environmental conditions which render growth and multiplication possible. The exact chemical nature of the change of oxyhemoglobin to methemoglobin is not known, but it is probably an oxidation process or a combination of reduction and oxidation processes, as pointed out by Heubner. As Cole has shown, the action of aminophenol is of great interest in this connection, in that it acts like a catalytic agent in being able to transform much more hemoglobin into methemoglobin than would be possible if the reaction were a simple molecular one. The metabolic activities of bacteria are largely in the nature of oxidation and reduction processes. The transformation of oxyhemoglobin into methemoglobin by streptococci of the viridans type, therefore, may be analogous to the action of such substances as aminophenol, and the reaction may be due to the active oxidation and reduction processes occurring in the neighborhood of the bacterial cells. The failure of the reaction to occur in the absence of oxygen and its retardation in the presence of an excess of oxygen, both with streptococci and with pneumococci (Cole) would seem to support this theory. Such results, however, may be due to the abnormal conditions surrounding the bacteria with consequent inhibition of their metabolic activities. Cole concluded as the result of his study of methemoglobin formation by pneumococci that since bacteria may injure red blood cells apparently by disturbances in oxidation in the immediate neighborhood of the organisms rather than by the production of a definite toxin, it is possible that bacteria may injure other tissue cells in a like manner and that the pathological effects produced by these bacteria may be explained on this basis. The experimental results recorded above have shown that the formation of methemoglobin by Streptococcus viridans in no way differs from its formation by pneumococci, and they lend support to the theory that bacteria may be injurious to tissues because of the disturbances in oxidation brought about by the metabolic activities of the organisms, especially those associated with growth and multiplication. It is believed that this theory may be particularly applicable to the pathological effects caused by Streptococcus vindans because the lesions produced by it, whether single or multiple, both in man and in experimental animals, are prone to be localized and associated with the actual presence of the streptococci in the lesions.

scholarly journals Three Redox States of a Diradical Acceptor–Donor–Acceptor Triad: Gating the Magnetic Coupling and the Electron Delocalization

2016 ◽  
Vol 7 (12) ◽  
pp. 2234-2239 ◽  
Author(s):  
Manuel Souto ◽  
Vega Lloveras ◽  
Sergi Vela ◽  
Maria Fumanal ◽  
Imma Ratera ◽  
...  
Keyword(s):  
Magnetic Coupling ◽  
Electron Delocalization ◽  
Redox States ◽  
Donor Acceptor

Multiple Redox States and Multielectrochromism of Donor–Acceptor Conjugated Polymers with Aromatic Diimide Pendant Groups

2019 ◽  
Vol 52 (21) ◽  
pp. 8453-8465 ◽  
Author(s):  
Anna Drewniak ◽  
Mateusz D. Tomczyk ◽  
Karol Knop ◽  
Krzysztof Z. Walczak ◽  
Przemyslaw Ledwon
Keyword(s):  
Conjugated Polymers ◽  
Redox States ◽  
Donor Acceptor

scholarly journals Redox tunable viologen-based porous organic polymers

2016 ◽  
Vol 4 (13) ◽  
pp. 2535-2544 ◽  
Author(s):  
Carol Hua ◽  
Bun Chan ◽  
Aditya Rawal ◽  
Floriana Tuna ◽  
David Collison ◽  
...  
Keyword(s):  
Organic Polymers ◽  
Porous Organic Polymers ◽  
Redox States ◽  
Donor Acceptor

The interplay between the electronic, spectral and host–guest properties of a donor–acceptor polymer in its different redox states is demonstrated.

Electrochemical Behavior of (Zn, Mn)-Al Nitrated Hydrotalcites

2012 ◽  
Vol 15 (4) ◽  
pp. 301-306 ◽  
Author(s):  
Alvaro Sampieri ◽  
Jorge Vázquez-Arenas ◽  
Ignacio González ◽  
Geolar Fetter ◽  
Heriberto Pfeiffer ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Lamellar Structure ◽  
Oxidation Process ◽  
Reduction Process ◽  
The Other ◽  
Oxidation Processes ◽  
Reduction Processes ◽  
Oxidation Reduction ◽  
Alkaline Conditions ◽  
Continuous Oxidation

The electrochemical behavior of synthetic binary, Zn-Al and Mn-Al, and ternary (Zn-Mn)-Al hydrotalcites (HT) was studied by cyclic voltammetry in alkaline conditions (pH≡12). The Zn-Al HT characterization revealed two irreversible and continuous oxidation processes: i) Zn0|Zn2+ and ii) Zn0|ZnO. On the other hand, the binary HT containing Mn presented a reversible behavior for the oxidation-reduction process Mn4+|Mn3+. The same oxidation-reduction processes were observed in the ternary HT. However, variations in the reduction-oxidation process were detected by XRD for the ternary HT as a result of spinel formation. These results could also be influenced due to a higher accessibility of manganese in HT since the morphology of hydrotalcite (lamellar structure) provides a regular distribution of Mn atoms interacting with Zn atoms through hydroxyl bridges.

Spectroscopic and DFT studies of donor-acceptor molecules containing phenylquinoline and phenothiazine moieties in various redox states

2005 ◽  
Vol 104 (5) ◽  
pp. 635-644 ◽  
Author(s):  
R. Ponce Ortiz ◽  
R. Malavé Osuna ◽  
M. C. Ruiz Delgado ◽  
J. Casado ◽  
S. A. Jenekhe ◽  
...  
Keyword(s):  
Dft Studies ◽  
Redox States ◽  
Donor Acceptor ◽  
Acceptor Molecules

Pyridine‐Containing Donor‐Acceptor Diarylnitroxides: Noncovalent Stabilization of the Redox States

ChemPlusChem ◽  
2021 ◽  
Author(s):  
Tatiana Magdesieva ◽  
Oleg A. Levitskiy ◽  
Alexey V. Bogdanov ◽  
Ivan A. Klimchuk
Keyword(s):  
Redox States ◽  
Donor Acceptor

Control of Metal Alloy Oxidation with Electric Fields

1973 ◽  
Vol 31 ◽  
pp. 164-165
Author(s):  
R. R. Dils ◽  
P. S. Follansbee
Keyword(s):  
Electric Fields ◽  
Oxidation Process ◽  
Base Alloy ◽  
Oxide Surface ◽  
Platinum Electrodes ◽  
Insulating Layer ◽  
Iron Base Alloy ◽  
Alloy Oxidation ◽  
Aluminum Oxide Layer ◽  
And Control

Electric fields have been applied across oxides growing on a high temperature alloy and control of the oxidation of the material has been demonstrated. At present, three-fold increases in the oxidation rate have been measured in accelerating fields and the oxidation process has been completely stopped in a retarding field.The experiments have been conducted with an iron-base alloy, Pe 25Cr 5A1 0.1Y, although, in principle, any alloy capable of forming an adherent aluminum oxide layer during oxidation can be used. A specimen is polished and oxidized to produce a thin, uniform insulating layer on one surface. Three platinum electrodes are sputtered on the oxide surface and the specimen is reoxidized.

Structural Imperfections in thin Oxide Films Formed on Some Fe- and Ni-Base Alloys

1970 ◽  
Vol 28 ◽  
pp. 510-511
Author(s):  
L. P. Lemaire ◽  
D. E. Fornwalt ◽  
F. S. Pettit ◽  
B. H. Kear
Keyword(s):  
Oxide Scale ◽  
Oxidation Process ◽  
Short Circuit ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Thin Oxide Films ◽  
Diffusion Paths ◽  
Oxidation Resistant ◽  
Structural Imperfections ◽  
Short Circuit Diffusion

Oxidation resistant alloys depend on the formation of a continuous layer of protective oxide scale during the oxidation process. The initial stages of oxidation of multi-component alloys can be quite complex, since numerous metal oxides can be formed. For oxidation resistance, the composition is adjusted so that selective oxidation occurs of that element whose oxide affords the most protection. Ideally, the protective oxide scale should be i) structurally perfect, so as to avoid short-circuit diffusion paths, and ii) strongly adherent to the alloy substrate, which minimizes spalling in response to thermal cycling. Small concentrations (∼ 0.1%) of certain reactive elements, such as yttrium, markedly improve the adherence of oxide scales in many alloy systems.

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