Search results for "Redox"
showing 10 items of 619 documents
Description of Solid-to-Solid Redox Processes Based on the Voltammetry of Immobilized Particles Methodology: A Logistic Approximation
2022
A semiempirical model to describe the voltammetry of nontopotactic solid-to-solid redox processes occurring in the voltammetry of immobilized particles (VIMP) electrochemistry is described. It is applied to the reduction of solid metal compounds to the corresponding metal in contact with suitable electrolytes. The model is based on the assumption that the transferred charge is a logistic function of the applied potential, a situation that applies for reversible redox processes involving strongly adsorbed reactants. The model satisfactorily applies to reproduce linear potential scan curves recorded for graphite electrodes modified with different lead compounds (PbO, PbCl2·2H2O, lead-tin yell…
Redox-Responsive Host-Guest Chemistry of a Flexible Cage with Naphthalene Walls
2020
“Naphthocage”, a naphthalene-based organic cage, reveals very strong binding (up to 1010 M–1) to aromatic (di)cationic guests, i.e., the tetrathiafulvalene mono- and dication and methyl viologen. Intercalation of the guests between two naphthalene walls is mediated by C–H···O, C–H···π, and cation···π interactions. The guests can be switched into and out of the cage by redox processes with high binding selectivity. Oxidation of the flexible cage itself in the absence of a guest leads to a stable radical cation with the oxidized naphthalene intercalated between and stabilized by the other two. Encapsulated guest cations are released from the cavity upon cage oxidation, paving the way to futur…
Autophagy
2012
Klionsky, Daniel J. et al.
Generation of a proton potential by succinate dehydrogenase of Bacillus subtilis functioning as a fumarate reductase
2001
The membrane fraction of Bacillus subtilis catalyzes the reduction of fumarate to succinate by NADH. The activity is inhibited by low concentrations of 2-(heptyl)-4-hydroxyquinoline-N-oxide (HOQNO), an inhibitor of succinate: quinone reductase. In sdh or aro mutant strains, which lack succinate dehydrogenase or menaquinone, respectively, the activity of fumarate reduction by NADH was missing. In resting cells fumarate reduction required glycerol or glucose as the electron donor, which presumably supply NADH for fumarate reduction. Thus in the bacteria, fumarate reduction by NADH is catalyzed by an electron transport chain consisting of NADH dehydrogenase (NADH:menaquinone reductase), menaqu…
Metallomacrocycles with metalmetal bonds: synthesis, characterization and electrochemistry of [(P)SnRe(CO)5]BF4 and [{(P)Sn}2Re(CO)4]BF4 derivatives…
1996
Abstract The synthesis and characterization of bimetallic and trimetallic porphyrins of the type [(P)SnRe(CO) 5 ]BF 4 and [{(P)Sn} 2 Re(CO) 4 ]BF 4 are reported where P is the dianion of tetra- p -tolyporphyrin (TpTP) or tetra- m -tolyporphyrin (TmTP). These metal-metal bonded complexes were synthesized by reaction of Re 2 (CO) 10 with the corresponding (P)SnCl 2 derivatives in 1,2-dichlorobenzene followed by a reaction with NaBF 4 or TBABF 4 in toluene to give the BF − 4 salt. Each compound was characterized by a variety of spectroscopic and electrochemical techniques while the structures were assigned on the basis of FAB mass spectral data and by comparison of their physicochemical proper…
Selenium: A Cure for Autoimmune Thyroiditis.
2021
Autoimmune thyroiditis (AT) is a disease whose incidence has increased dramatically over the past few decades. In iodine sufficient areas, this pathological condition affects up to 5% of the general population. The higher incidence of AT observed in areas of the world with low-selenium (Se) soils apperas to be the consequence of a reduced activity of the intracellular Sedependent glutathione peroxidase activity. Se is involved, through selenoproteins, in the regulation of intracellular antioxidant, redox and anti-inflammatory processes. As a component of selenoproteins, Se exerts various structural and enzymatic functions. A low Se/high fat diet can cause selenoprotein changes and promote t…
New synthetic methodologies to functionalize 3,4-dihydroquinoxalin-2-ones and 3,4-dihydro-1,4-benzoxazin-2-ones using visible-light photocatalysis
2022
En aquesta tesi, es presenten diversos enfocaments sintètics per a la funcionalització en C-3 de 3,4-dihidroquinoxalin-2-ones i 3,4-dihidro-1,4-benzoxazin-2-ones mitjançant catàlisi fotoredox amb llum visible. La tesi es divideix en tres parts diferenciades, sent la primera una introducció general i els objectius principals. A continuació, en la segona part, es descriuen els esforços en la funcionalització nucleòfila de 3,4-dihidroquinoxalina-2-ones i 3,4-dihidro-1,4-benzoxazin-2-ones. Concretament, hem desenvolupat protocols sintètics per a la reacció de Friedel-Crafts entre 3,4-dihidroquinoxalin-2-ones i 3,4-dihidro-1,4-benzoxazin-2-ones amb indols i altres arenes rics en electrons (capít…
In vitro effects of extracts from leaves and rhizomes of P.oceanica on HepG2 tumor cells
2023
Uptake of actinides by calcium silicate hydrate (C-S-H) phases
2018
Abstract The sorption of actinides (Th, U – Am) was studied in dependence of the solid-to-liquid (S/L) ratio (0.5–20.0 g/L) and the calcium-to-silicon (C:S) ratio. The C:S ratio was varied between 1.80 and 0.70 to simulate the changing composition of the C-S-H phases during cement degradation from high to low C:S ratios. The decrease of the calcium content in the C-S-H phases by time is accompanied by a decrease in pH in the corresponding suspensions from 12.6 to 10.2. X-ray photoelectron spectroscopy (XPS) of the C-S-H phases showed an increasing depletion of Ca on the surface with increasing C:S ratio in comparison to the composition of the solid phase as a whole. The sorption experiments…
First Highly Diastereoselective Synthesis of syn α-Methyl β-Fluoroalkyl β-Amino Esters
1999
A new two-step approach for the diastereoselective synthesis of the syn α-methyl β-fluoroalkyl β-amino esters 4 has been developed. This approach is based on the chemical reduction of the fluorinated β-enamino esters 3, which have been previously obtained from imidoyl chlorides 1 and lithium ester enolates, with ZnI2/NaBH4 as the reducing agent. The process takes place with high syn diastereoselectivity and good to excellent yields. A metal-chelated six-membered model has been suggested to explain the stereochemical outcome of the reduction reaction.