1,721,001 research outputs found
AN ALTERNATIVE PROCEDURE FOR ESR IDENTIFICATION OF IRRADIATED CHICKEN DRUMSTICKS
No full textThe ESR spectroscopy is, at present, the most established technique for quantitative analysis of irradiated chicken bone using the additive dose method. In this paper we tried a different approach to the problem analyzing the ESR behavior of a batch of chicken bone samples coming randomly from the market. Using a suitable and standardized sample preparation technique and sample positioning in the microwave cavity, we obtained a coefficient of variation of about 30 % for the batch response. The calibration curve, obtained using the batch behavior up to 10 kGy, was used for a quantitative test on unknown samples
Moxel : a molar tooth voxel model for dosimetric studies
No full textStylized numerical models of the tooth are usually employed in qualification procedure related to
Electronic Paramagnetic Resonance in long-term accidental contamination dose reconstruction. In this
work a voxel model was developed from the microCT image data set of a human non contaminated molar
tooth. A stylized model, reproducing the characteristics of the voxel model, was also created in order to
investigate the level of accuracy that can be obtained in this kind of study
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Modulation of bovine serum amine oxidase activity by hydrogen peroxide
No full textBovine serum amine oxidase (BSAO), reduced by excess amine under limited turnover conditions, was over 80% inactivated by H2O2 upon oxygen exhaustion. The UV-Vis spectrum and the reduced reactivity with carbonyl reagents showed that the cofactor topaquinone (TPQ) was stabilized in reduced form. The protein large M-r (170 kDa) prevented the identification of modified residues by amino acid analyses. Minor changes of the Cu2+ EPR signal and the formation of a radical at g = 2.001, with intensity a few percent of that of the Cu2+ signal, unaffected by a temperature increase, suggest that Cu2+-bound histidines were not oxidized and the radical was not the Cu+-semi-quinolamine in equilibrium with Cu2+-aminoquinol. It may derive from the modification of a conserved residue in proximity of the active site, possibly the tyrosine at hydrogen-bonding distance of TPQ C-4 ionized hydroxyl, The inactivation reaction appears to be a general feature of copper-containing amine oxidases, It may be part of an autoregulatory process in vivo, possibly relevant to cell adhesion and redox signaling. (C) 2000 Academic Press
Effetti prodotti dall'irraggiamento gamma su microsfere di polilattidi-co-glicolidi contenentibupivacaina
No full textPulsed EPR analysis of tooth enamel samples exposed to UV and gamma-radiations
No full textThe electron paramagnetic resonance (EPR) spectroscopy is widely applied for retrospective dosimetric purposes by means of quantitative detection of radicals in tooth enamel and bone samples.
In this work we report a study by cw and pulsed EPR on two samples of human tooth enamel respectively irradiated by UV (254 nm) and gamma-exposed. The continuous wave (cw) EPR spectra have shown the usual presence in both samples of two types of CO_(2)^(-) radicals, with axial and orthorombic g tensors. We have obtained the electron spin echo detected EPR (ED-EPR) spectra at 80 K of the two samples, and we have shown that they are suitable to mark the difference between the effects produced by the different irradiations. At low temperature the contribution to the ED-EPR spectrum of the mobile radical with the axial g tensor is still present in the UV irradiated sample, but not in the gamma-irradiated one, where its dynamics is too slow to average the g tensor.
We have moreover studied the two-pulse electron spin echo decay on varying the microwave power, a well established method for measuring the Instantaneous Diffusion. We have found that the spectral diffusion parameter is almost the same for both radiation types, whereas the Instantaneous Diffusion is significantly larger for gamma-exposed samples than for UV irradiated ones. This difference is due to a higher local microscopic concentration of free radicals for samples irradiated with gamma photons
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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