Search results for "oxides"

Spatial analysis of the relationship between mortality from cardiovascular and cerebrovascular disease and drinking water hardness

2004

Journal Article; Research Support, Non-U.S. Gov't; Reproduced with permission from Environmental Health Perspectives. Previously published scientific papers have reported a negative correlation between drinking water hardness and cardiovascular mortality. Some ecologic and case-control studies suggest the protective effect of calcium and magnesium concentration in drinking water. In this article we present an analysis of this protective relationship in 538 municipalities of Comunidad Valenciana (Spain) from 1991-1998. We used the Spanish version of the Rapid Inquiry Facility (RIF) developed under the European Environment and Health Information System (EUROHEIS) research project. The strateg…

Maintenance of GSH content in primary astrocyte cultures under oxidative stress conditions.

1993

Validation of brain extracellular glycerol as an indicator of cellular membrane damage due to free radical activity after traumatic brain injury.

2008

Following severe traumatic brain injury (TBI), increasing oxygen delivery to the brain has been advocated as a useful strategy to reverse mitochondrial dysfunction and improve neurological outcome. However, this might also promote overproduction of free radicals, responsible for lipid peroxidation and hence brain cell damage. Therefore, a method for monitoring this potential adverse effect in humans is desirable. Glycerol, an end product of phospholipid breakdown, easily detectable in the human brain by means of microdialysis, might represent a reliable indicator of free radical-induced cell membrane damage. Brain microdialysates were collected from 24 adult male Sprague-Dawley rats over a …

Synthesis of Highly Functionalized Fluorinated Cispentacin Derivatives

2012

Fluorinated highly functionalized cispentacin derivatives were synthetised starting from an unsaturated bicyclic b-lactam through C¼C bond functionalization via the dipolar cycloaddition of a nitrile oxide, isoxazoline opening, and fluorination by OH/F exchange.

Oxidation of melatonin by oxoferryl hemoglobin: A mechanistic study

2002

Reaction of melatonin with the hypervalent iron centre of oxoferryl hemoglobin, produced in aqueous solution from methemoglobin and H2O2, has been investigated at 37 degrees C and pH 7.4, by absorption spectroscopy. The reaction results in reduction of the oxoferryl moiety with formation of a heme-ferric containing hemoprotein. Stopped-flow spectrophotometric measurements provide evidence that the reduction of oxoferryl-Hb by melatonin is first-order in oxoferryl-Hb and first-order in melatonin. The bimolecular reaction constant at pH 7.4 and 37 degrees C is 112 +/- 1.0 M(-1) s(-1). Two major oxidation products from melatonin have been found by gas chromatography-mass spectroscopy: the cycl…

Host-Guest Complexes of C-Ethyl-2-methylresorcinarene and Aromatic N,N′-Dioxides

2017

The C‐ethyl‐2‐methylresorcinarene (1) forms 1:1 in‐cavity complexes with aromatic N,N′‐dioxides, only if each of the aromatic rings has an N−O group. The structurally different C‐shaped 2,2′‐bipyridine N,N′‐dioxide (2,2′‐BiPyNO) and the linear rod‐shaped 4,4′‐bipyridine N,N′‐dioxide (4,4′‐BiPyNO) both form 1:1 in‐cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host–guest interactions between the 1,3‐bis(4‐pyridyl)propane N,N′‐dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti‐gauche conformation. Contrary to the N,N′‐dioxide guests, the mono‐N‐oxide guest, 4‐phenylpyridine N‐oxide (4PhPyNO), does not form an…

Zn,Al hydrotalcites calcined at different temperatures: Preparation, characterization and photocatalytic activity in gas–solid regime

2011

Abstract Layered double hydroxides (LDH) containing zinc and aluminium within the brucite-like layers and carbonate as the interlayer anion have been used as precursors for the preparation of mixed metal oxides by calcination. Zinc oxide and the ZnAl 2 O 4 spinel were formed with different degree of crystallinity depending of two parameters, i.e., the Zn 2+ /Al 3+ molar ratio and the calcination temperature (500–800 °C) of the LDH precursor. A pure spinel phase was obtained to remove ZnO upon a basic post-treatment in NaOH solution of the samples calcined at 800 °C. All the samples were tested for the photodegradation of 2-propanol in gas–solid regime. All the samples resulted active as het…

Low-cost materials for boron adsorption from water

2012

[EN] Knowing the affinity of boron aqueous species for cis-diol organic groups, five different hybrid materials have been prepared by anchoring glucose groups onto the surface of silica matrices with a different surface topology: UVM-7 bimodal mesoporous silica, UVM-11 unimodal non-templated mesoporous silica, commercial silica fume and two silica xerogels with pores within the mesoporous range (13-50 nm). After optimizing the experimental conditions, a comparison was made of the boron adsorption capacities in water. The relationship of the structural and functionalization parameters is discussed and the importance of the surface topology in the final adsorption behaviour is revealed. Hence…

Improved Photocatalytic Activity of Polysiloxane TiO2 Composites by Thermally Induced Nanoparticle Bulk Clustering and Dye Adsorption

2021

Fine control of nanoparticle clustering within polymeric matrices can be tuned to enhance the physicochemical properties of the resulting composites, which are governed by the interplay of nanoparticle surface segregation and bulk clustering. To this aim, out-of-equilibrium strategies can be leveraged to program the multiscale organization of such systems. Here, we present experimental results indicating that bulk assembly of highly photoactive clusters of titanium dioxide nanoparticles within an in situ synthesized polysiloxane matrix can be thermally tuned. Remarkably, the controlled nanoparticle clustering results in improved degradation photocatalytic performances of the material under …

In-situ high-pressure x-ray diffraction study of zinc ferrite nanoparticles

2016

We have studied the high-pressure structural behavior of zinc ferrite (ZnFe2O4) nanoparticles by powder X-ray diffraction measurements up to 47 GPa. We found that the cubic spinel structure of ZnFe2O4 remains up to 33 GPa and a phase transition is induced beyond this pressure. The high-pressure phase is indexed to an orthorhombic CaMn2O4-type structure. Upon decompression the low- and high-pressure phases coexist. The compressibility of both structures was also investigated. We have observed that the lattice parameters of the high-pressure phase behave anisotropically upon compression. Further, we predict possible phase transition around 55 GPa. For comparison, we also studied the compressi…