Search results for "Redox"

The oxidation state of iron in silicic melt at 500 MPa water pressure

2002

Abstract The dependence of the ferric–ferrous ratio in silicate melts on oxygen fugacity was studied in the system SiO2(Qz)–NaAlSi3O8(Ab)–CaAl2Si2O8(An)–H2O using Mossbauer spectroscopy. Experiments were performed under water-saturated conditions at 500 MPa, and at temperatures of 850 and 950 °C, covering a range typical for magmatic processes. The oxygen fugacity was varied in the fO2 range from Cu–Cu2O buffer to slightly more reducing conditions than the wustite–magnetite buffer. The iron redox ratio was determined by analyzing the Mossbauer parameter distribution that was modeled based on experimental spectra collected at room temperature on the quenched samples. The obtained iron redox …

Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex

2019

Abstract Photoactive metal complexes employing Earth‐abundant metal ions are a key to sustainable photophysical and photochemical applications. We exploit the effects of an inversion center and ligand non‐innocence to tune the luminescence and photochemistry of the excited state of the [CrN6] chromophore [Cr(tpe)2]3+ with close to octahedral symmetry (tpe=1,1,1‐tris(pyrid‐2‐yl)ethane). [Cr(tpe)2]3+ exhibits the longest luminescence lifetime (τ=4500 μs) reported up to date for a molecular polypyridyl chromium(III) complex together with a very high luminescence quantum yield of Φ=8.2 % at room temperature in fluid solution. Furthermore, the tpe ligands in [Cr(tpe)2]3+ are redox non‐innocent, …

Highlight on transient activation of red/ox-dependent survival signals involving MEK/ERK and PI3/Akt signaling pathways in 27-hydroxycholesterol trea…

2014

Mitochondrial and redox dysfunction in post-menopause as risk factor of neurodegenerative disease: a pilot study testing the role of a validated Japa…

2020

During the menopause women may experience increased oxidative stress and decreased antioxidant capacity and, together with the decline of neurosteroids, this represents a risk factor for Alzheimer's disease. The aim of the present study was to test a functional food (FPP-ORI, Osato Research Institute, Gifu, Japan) on redox and mitochondrial efficiency in post-menopausal women. The study population consisting of 69 untreated post-menopausal women were given supplements as follows: Group A was given a multivitamin (MV) 1c 2 times a day, and group B was given FPP 4.5 g 2 times a day. Group C consisted of 23 fertile premenopausal women as the control group. The tests carried out on entry, and a…

Breathing-Dependent Redox Activity in a Tetrathiafulvalene-Based Metal–Organic Framework

2018

"Breathing" metal-organic frameworks (MOFs) that involve changes in their structural and physical properties upon an external stimulus are an interesting class of crystalline materials due to their range of potential applications including chemical sensors. The addition of redox activity opens up a new pathway for multifunctional "breathing" frameworks. Herein, we report the continuous breathing behavior of a tetrathiafulvalene (TTF)-based MOF, namely MUV-2, showing a reversible swelling (up to ca. 40% of the volume cell) upon solvent adsorption. Importantly, the planarity of the TTF linkers is influenced by the breathing behavior of the MOF, directly impacting on its electrochemical proper…

Combined action of redox potential and pH on heat resistance and growth recovery of sublethally heat-damaged Escherichia coli

2000

International audience; The combined effect of redox potential (RP) (from -200 to 500 mV) and pH (from 5.0 to 7.0) on the heat resistance and growth recovery after heat treatment of Escherichia coli was tested. The effect of RP on heat resistance was very different depending on the pH. At pH 6.0, there was no significant difference, whereas at pH 5.0 and 7.0 maximum resistance was found in oxidizing conditions while it fell in reducing ones. In sub-lethally heat-damaged cells, low reducing and acid conditions allowed growth ability to be rapidly regained, but a decrease in the redox potential and pH brought about a longer lag phase and a slower exponential growth rate, and even led to growt…

Hydrogen emissions from Erebus volcano, Antarctica

2012

International audience; The continuous measurement of molecular hydrogen (H2) emissions from passively degassing volcanoes has recently been made possible using a new generation of low-cost electrochemical sensors. We have used such sensors to measure H2, along with SO2, H2O and CO2, in the gas and aerosol plume emitted from the phonolite lava lake at Erebus volcano, Antarctica. The measurements were made at the crater rim between December 2010 and January 2011. Combined with measurements of the long-term SO2 emission rate for Erebus, they indicate a characteristic H2 flux of 0.03 kg s-1 (2.8 Mg day-1). The observed H2 content in the plume is consistent with previous estimates of redox cond…

Electropolymerization of non-substituted Mg(II) porphine: Effects of proton acceptor addition

2015

Abstract Electropolymerization of unsubstituted magnesium porphine in acetonitrile solutions possessing various proton-accepting properties has been studied. The overall rate of the polymer-product accumulation on the electrode surface has been established to be limited by the deprotonation step of intermediate species. This conclusion is based on the observed influence of proton-accepting additives, water or 2,6-dimethylpyridine (lutidine), on the Mg-porphine electrooxidation process. Lutidine addition into the polymerization bath enables one to enhance strongly the rate of the film growth and the efficiency of this process increases more than by a factor of two, redox, electric conductivi…

Two-dimensional 1 H NMR spectra of ferricytochrome c 551 from Pseudomonas aeruginosa

1993

AbstractThe full assignment of 1H NMR signals of heme proton resonances of ferricytochrome c551 from Pseudomonas aeruginosa has been performed by means of 2D NMR experiments. This technique allows the complete and unequivocal assignment of all heme resonances, including methylene resonances of the propionic groups, directly implicated in the pH dependence of the redox properties of cytochrome c551.

The Effectiveness of Glutathione Redox Status as a Possible Tumor Marker in Colorectal Cancer

2021

The role of oxidative stress (OS) in cancer is a matter of great interest due to the implication of reactive oxygen species (ROS) and their oxidation products in the initiation of tumorigenesis, its progression, and metastatic dissemination. Great efforts have been made to identify the mechanisms of ROS-induced carcinogenesis