Search results for " H2O"

Lower mantle hydrogen partitioning between periclase and perovskite : a quantum chemical modelling

2016

Abstract Partitioning of hydrogen (often referred to as H2O) between periclase (pe) and perovskite (pvk) at lower mantle conditions (24–80 GPa) was investigated using quantum mechanics, equilibrium reaction thermodynamics and by monitoring two H-incorporation models. One of these (MSWV) was based on replacements provided by Mg2+ ↔ 2H+ and Si4+ ↔ 4H+; while the other (MSWA) relied upon substitutions in 2Mg2+ ↔ Al3+ + H+ and Si4+ ↔ Al3+ + H+. H2O partitioning in these phases was considered in the light of homogeneous (Bulk Silicate Earth; pvk: 75%–pe:16% model contents) and heterogeneous (Layered Mantle; pvk:78%–pe:14% modal contents) mantle geochemical models, which were configured for lower…

Shrinkage Bubbles: The C–O–H–S Magmatic Fluid System at San Cristóbal Volcano

2018

New analytical results for the composition of shrinkage bubbles (09-70 vol. %) in olivine-hosted (Fo <80%) primary melt inclusions (MIs) have been incorporated into a novel geochemical model for San Cristó bal volcano, Nicaragua. The vapour, liquid, and mineral components found inside shrinkage bubbles may represent relics of early C-O-H-S fluids exsolved from a magmatichydrothermal system. This conclusion is supported by high-resolution Raman microspectroscopy revealing: (1) gaseous CO2 (d=0·17-0·31 g/cm3 in 31 samples) coexisting with liquid H2O (in seven samples) at ambient temperature (<22°C) inside the shrinkage bubbles of naturally quenched inclusions; (2) several mineral phases (i.e.…

Volatiles in pantellerite magmas: A case study of the Green Tuff Plinian eruption (Island of Pantelleria, Italy)

2013

Abstract The Green Tuff (GT) Plinian eruption, the largest in magnitude at Pantelleria, erupted 3 to 7 km3 DRE of pantellerite magma and a small volume of trachyte. Fifty-nine anorthoclase-hosted melt inclusions from the two basal pumice members were analyzed by FT-IR spectroscopy in order to assess the pre-eruptive H2O content in the pantellerite melt. Microanalytical methods were used to determine major element, Cl, F and S contents. Melt inclusions and glassy groundmasses have a nearly homogeneous pantelleritic composition (peralkaline index = 1.9-2.2) and variable water contents ranging from 1.4 to as high as 4.2 wt %, i.e. much higher than the 1.4 wt % of earlier published studies. The…

[Cu(tn)]3[Cr(CN)6]2·3H2O: A unique two-dimensional Cu-Cr cyano-bridged ferromagnet (tn = 1,3-diaminopropane)

2002

Reaction of the two-coordinate ‘assembling complex-ligand’ [Cu(tn)]2+ with the building block [Cr(CN)6]32 leads to a unique two-dimensional Cu–Cr cyano-bridged ferromagnet with unusual m3- and m4-bridging [Cu(tn)]2+ units. Gomez Garcia, Carlos Jose, Carlos.Gomez@uv.es

Effects of H2O2 on mesoangioblast stem cells: survival and cell death

2009

H2O2 INDUCES NECROPTOSIS IN MESOANGIOBLAST STEM CELLS

2018

Stem cells are used in regenerative medicine, but their therapeutic efficacy is compromised by their huge death during the first days post-transplantation. Indeed, the microenvironment within damaged tissues is hostile for stem cell survival mainly due to oxidative stress. H2O2 may play a relevant role in inducing death of the injected cells. The aim of our study was to determine the mechanism of mesoangioblast (A6) cell death after an H2O2 treatment. FACS analysis with annV/PI showed that H2O2 induced a dose and time-dependent decrement in A6 viability. We have also found an increase in caspases 8, 9 and 3 activity after the treatment. To assess their involvement in cell death, the pan cas…

Nanowire Ordered Arrays for Electrochemical Sensing of H2O2

2016

Today, electrochemical sensors are considered very interesting in comparison to conventional techniques because they are very adaptable, cheap, have very low limit of detection and low detection time. The most used electrochemical technique is the amperometry . In amperometric sensors, a fixed potential is applied to the electrochemical cell, and a corresponding current, due to a reduction or oxidation reaction, is then obtained. This current it can be correlated with the bulk concentration of the detecting species (the solute) such as H2O2. Hydrogen peroxide is an essential mediator in food, pharmaceutical, clinical, industrial, and environmental analyses therefore, it is of great importan…

Pd-NWs ordered arrays for electrochemical sensing of H2O2

2016

In this work, we present the performance of nanostructured array of Pd (Pd-NWs) for electrochemical sensors of hydrogen peroxide. Hydrogen peroxide is widely used in several fields, because to its oxidizing and reducing properties, like for treatment of waste water, paper and contaminated soils, as reagent in many chemical industries or like rocket propellant [1]. Furthermore, its presence or absence may be connected with many neurological deseases or/and with cancer [2].Today the most used methods for detection of that chemical are IR spectroscopy, spectrophotometry, fluorimetry, chemioluminescence and redox titration. However these methods are often uneconomical, have very high detection …

Nanowire ordered Arrays for electrochemical sensing of H2O2

2016

In this work, we present the performance of nanostructured array of Cu for electrochemical sensors of hydrogen peroxide. Nanostructured sensors are obtained by template synthesis in commercial polycarbonate membranes. Arrays of Cu nanowires were fabricated through a displacement deposition reaction that permits to obtain nanostructures directly and without the use of an external power supply. To test the performance of nanostructured sensors, electrochemical experiments were carried out in an aqueous solution with different amounts of hydrogen peroxide. In order to obtain sensors with stable performance, we found that it is essential to increase wettability of the nanostructures through add…