Search results for "ESr"

Fluidity of liposome membranes doped with metalloporphyrins: An ESR study

2008

Changes in membrane fluidity of porphyrin-doped liposomes have been investigated to assess the kinetics of the fluidization process. Metal complexes of tert-butylphenyl mesosubstituted porphyrin, containing ions of Mg, Mn, Fe, Co, Ni and Cu, were used as dopants. Liposomes were obtained by sonication of hen egg yolk lecithin (EYL). Electron paramagnetic resonance (ESR) was applied using two spin probes, TEMPO (2,2,6,6-tetramethylpiperidine- 1-oxyl) and 16-DOXYL-stearic acid [2-ethyl-2-(15-methoxy-15-oxopentadecyl)-4,4- dimethyl-3-oxazolidinyloxyl], localized at different sites within the membrane to determine the spectroscopic parameters: partition (F) and rotation correlation time (τ), rel…

Dynamics of surface of lipid membranes: theoretical considerations and the ESR experiment.

2016

The effect of the surface layer of model membranes on their physical properties was discussed in this paper. The research involved a physical ESR experiment with the use of spin probes and computer simulation based on the Monte Carlo technique. Liposomes formed during the process of sonication of lecithin were scanned in an ESR spectrometer. The membrane surface layer model, represented by the system of electric dipoles arranged in rectangular or hexagonal matrices, was studied. The final states of computer simulations were presented as textures. It was found that in the gel phase some ordered domain structures are formed, while in the liquid–crystal phase we got complex textures comprising…

Characterization of phenolic pellets for ESR dosimetry in photon beam radiotherapy

2017

This work deals with the dosimetric features of a particular phenolic compound (IRGANOX 1076 ® ) for dosimetry of clinical photon beams by using electron spin resonance (ESR) spectroscopy. After the optimization of the ESR readout parameters (namely modulation amplitude and microwave power) to maximise the signal without excessive spectrum distortions, basic dosimetric properties of laboratory-made phenolic dosimeters in pellet form, such as reproducibility, dose–response, sensitivity, linearity and dose rate dependence were investigated. The dosimeters were tested by measuring the depth dose profile of a 6 MV photon beam. A satisfactory intra-batch reproducibility of the ESR signal of the …

Synthesis, molecular and electronic structures of a paramagnetic trimetallic cluster containing an unusual Mo3(μ3-Se)2(μ-Se)3 core

2014

Abstract The electron precise [Mo3(μ3-Se)(μ-Se)3(dppe)3Br3]+ incomplete cuboidal complex, with six cluster skeletal electrons (CSE), was converted into the paramagnetic bicapped [Mo3(μ3-Se)2(μ-Se)3(dppe)3]+ cluster (1+), with an unusual seven metal electron population, by treatment with elemental Ga. The cluster core consists of an almost equilateral Mo3 triangle (Mo–Mo distances are in the range 2.7583(7)–2.7748(7) A with an average value of 2.77(3) A), capped by two selenide ligands. The remaining selenium atoms bridge adjacent metal atoms, defining a virtually planar Mo3(μ-Se)3 unit, with the capping Se atoms positioned above and below this plane. The new complex possesses a doublet grou…

Caos y gobernación del mundo

2004

Competid malditos!

1998

La mundialización del crimen

1997

Fullerene as a Platform for Recyclable TEMPO Organocatalysts for the Oxidation of Alcohols

2014

[60]Fullerene has been employed successfully as a molecular platform to anchor 12 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties. Such an octahedrally substituted C60-derivative has been employed as an organocatalyst for the oxidation of primary and secondary alcohols using the Anelli protocol. The reaction showed a general applicability to various alcohols, and the catalyst was recovered easily and could be recycled for at least seven cycles with no loss in catalytic activity. EPR spectroscopy studies revealed that the amount of radicals decreases during the catalytic cycles, even if the recovered material still displays unchanged catalytic activity. This new approach paves the way …

Inflammation is an amplifier of lung congestion by high lv filling pressure in hemodialysis patients: a longitudinal study

2019

Introduction Since infammation alters vascular permeability, including vascular permeability in the lung, we hypothesized that it can be an amplifer of lung congestion in a category of patients at high risk for pulmonary oedema like end stage kidney disease (ESKD) patients. Objective and methods We investigated the efect modifcation by systemic infammation (serum CRP) on the relationship between a surrogate of the flling pressure of the LV [left atrial volume indexed to the body surface area (LAVI)] and lung water in a series of 220 ESKD patients. Lung water was quantifed by the number of ultrasound B lines (US-B) on lung US. Six-hundred and three recordings were performed during a 2-year f…

CHARACTERIZATION OF THE GAMMA DOSE COMPONENT IN THE NEUTRON FIELD OF A BNCT IRRADIATION FACILITY

2017

At the University of Pavia, a neutron irradiation facility has been constructed for preclinical in vitro and in vivo studies for BNCT. The facility is a wide channel (40 x 20 x 100 cm3) inside the graphite Thermal Column of the 250 KW research reactor TRIGA Mark II. The neutron field consists in a thermal component ranging from about 1010 and 109 cm-2s-1 along the longitudinal axis of the channel and it is uniform within 10% along the transversal axes. The fast neutron contamination (En > 1.58 keV) is more than 2 orders of magnitude lower. The gamma background coming from the core has been reduced with a 20 cm thick bismuth shield, however in the facility a gamma component is still prese…