Degradation of epoxy coatings under gamma irradiation

Epoxy networks based on Diglycidyl ether of bisphenol A (DGEBA) and cured with Jeffamines (POPA) or polyamidoamine (PAA) were gamma irradiated at 25 1C in air. Dose rates of 50, 200 or 2000 Gy h- 1 for doses up 100 kGy were used. Structural changes were monitored by IR spectrophotometry, DSC and sol–gel analysis. Both networks display some common features: for I Z 200 Gy h- 1, reaction products grow proportionally to time and the rate is a decreasing function of dose rate. The simplest explanation is that peroxy radicals are the main precursors of these products (in the dose rate domain under study), through a unimolecular rearrangement of which an hypothetical mechanism is proposed. DGEBA–POPA are more reactive then DGEBA–PAA networks (according to IR criteria), that can be attributed to the high reactivity of tertiary CH bands in polyoxypropylene segments. The oxidation of these sites leads to methyl ketones. A simple kinetic model in which methyl ketones result from rearrangements of tertiary peroxyls and from tertiary alkoxyls was proposed. It leads to an expression of the radiochemical yield of methyl ketones (G(MK)) of the form GðMKÞ¼ a þ bI-1=2 where a and b are parameters depending of elementary rate constants. Experimental G(MK) values are reasonably well fitted by this equation. In DGEBA–PAA networks, a wide variety of oxidation products, among which amides predominate, can be observed. In these networks, chain scissions predominate over crosslinking, whereas a slight predominance of crosslinking was observed, at least for the lowest dose rate, in DGEBA–POPA

Thermo-oxidative aging of epoxy coating systems

tThe thermo-oxidative behavior of unformulated (unfilled) samples of epoxy coatings has been studiedat five temperatures ranging from 70◦C to 150◦C. Two epoxy networks based on diglycidyl ether ofbisphenol A (DGEBA), respectively, cured by jeffamine (POPA) or polyamidoamine (PAA) were compared.Infrared spectrophotometry (IR), differential scanning (DSC) and sol–gel analysis (SGA) were used tomonitor structural changes.Thermal oxidation leads to carbonyl and amide formation in both systems. POPA systems appear moresensitive to oxidation than PAA ones. Thermal oxidation leads to predominant chain scission as evidencedby the decrease of glass transition temperatures (Tg) and increase of sol fraction

Transforming the Future Healthcare Workforce across Europe through Improvement Science Training: A Qualitative Approach

Healthcare improvement science (HIS) is the generation of knowledge to cultivate change towards improving health systems performance. Our purpose was to evaluate the experience of European nursing students after an intensive one-week summer program conducted in 2019 at the University of Alicante in Spain. The educational intervention combined theoretical and practical HIS contents, with students from different countries, educational programs, and health systems. The intervention was evaluated under a qualitative approach through the open discussion group technique based on the method of participatory action research (PAR), with a total of 25 students who reflected about their experiences and perceptions during the intervention. The responses were used to improve the program’s contents, its didactics, and organization. Nursing empowerment, professional recognition, and healthcare research were some of the seven main categories identified through the systematic content analysis method triangulated by three experienced researchers. According to the students’ replies, values like compassion, respect, or empathy were identified as key elements of care. Promoting international students’ networking emerged as the key to creating a positive provision for change and the generation of improvement initiatives. Building a HIS culture may potentially provide future healthcare professionals with critical thinking skills and the resources needed to improve their future work settings.The research was financed by the European Union-funded ERASMUS Lifelong Learning Project, ISTEW: Improvement Science Training for European Healthcare Workers (Project No. 539194-LLP-1-2013-1-UK-ERASMUS-EQR)

Skin and Non-Solid Cancer Incidence in Interventional Radiology using Biological and Physical Dosimetry Methods

Non

Dynamical replica theoretic analysis of CDMA detection dynamics

We investigate the detection dynamics of the Gibbs sampler for code-division multiple access (CDMA) multiuser detection. Our approach is based upon dynamical replica theory which allows an analytic approximation to the dynamics. We use this tool to investigate the basins of attraction when phase coexistence occurs and examine its efficacy via comparison with Monte Carlo simulations.Comment: 18 pages, 2 figure

Spectral Efficiency of Spectrum Pooling Systems

In this contribution, we investigate the idea of using cognitive radio to reuse locally unused spectrum to increase the total system capacity. We consider a multiband/wideband system in which the primary and cognitive users wish to communicate to different receivers, subject to mutual interference and assume that each user knows only his channel and the unused spectrum through adequate sensing. The basic idea under the proposed scheme is based on the notion of spectrum pooling. The idea is quite simple: a cognitive radio will listen to the channel and, if sensed idle, will transmit during the voids. It turns out that, although its simplicity, the proposed scheme showed very interesting features with respect to the spectral efficiency and the maximum number of possible pairwise cognitive communications. We impose the constraint that users successively transmit over available bands through selfish water filling. For the first time, our study has quantified the asymptotic (with respect to the band) achievable gain of using spectrum pooling in terms of spectral efficiency compared to classical radio systems. We then derive the total spectral efficiency as well as the maximum number of possible pairwise communications of such a spectrum pooling system

Aproximación al Abordaje Interdisciplinario Desarrollado por los Equipos Técnicos de Mediadores en Mediaciones Comunitarias y Familiares en el Centro de Mediación Comunitaria y Centro Judicial de Mediación

El presente trabajo describe los resultados obtenidos en relación al abordaje interdisciplinario y los aportes de la psicología en mediaciones comunitarias y familiares, en el marco de las prácticas Pre-Profesionales del Contexto Jurídico de la Facultad de Psicología de la Universidad Nacional de Córdoba, realizadas por primera vez en el Centro de Mediación Comunitaria y el Centro Judicial de Mediación en el año 2015, no hallándose antecedentes previos a este tipo de estudio. Objetivos. Describir el abordaje interdisciplinario desarrollado por los equipos técnicos de mediadores, en mediaciones comunitarias y familiares. Reconocer los aportes de la Psicología en mediaciones familiares y comunitarias. Metodología. Estudio de tipo descriptivo cualitativo, con diseño transversal, con técnicas de observación no participante, siendo los instrumentos las entrevistas semidirigidas y libres, la búsqueda documental y el cuaderno de campo. La población estuvo compuesta por las partes asistentes a las audiencias de mediación entre mayo y octubre del año 2015 en el Centro Judicial de Mediación y el Centro de Mediación Comunitaria. Resultados. De los datos obtenidos se puede afirmar que tanto la interdisciplina como los aportes de la psicología son importantes en la práctica de mediación, siendo éste un método que se posiciona desde un enfoque de derechos en cuanto apunta a la prevención de la violencia. Discusión. La mediación, al trabajar con conflictos, pone en juego problemas de salud mental. Los principios que guían el actuar del psicólogo son parte y garantía del éxito del proceso de mediación y las ciencias psicológicas atraviesan transversalmente dicho proceso, realizando aportes tanto a nivel teórico como práctico

Second-generation antihistamines: a study of poisoning in children

The toxicity of second-generation antihistamines after an overdose by a child is still unknown. The objective of this study is to use data from Poisons Centres in France to describe the toxicity profile of second-generation antihistamines for children and to compare the severity of poisoning observed from these with a first-generation antihistamine. This was a retrospective, multi-centre and observational study focusing on human cases of single-substance exposure to a second-generation antihistamine and to mequitazine, reported between 1 January 2001 and 31 December 2016 in Poisons Centres in France. From a total of 9403 children included, 5980 were exposed to a second-generation antihistamine and 3423 were exposed to mequitazine. The severity of exposure to second-generation antihistamines in children is low: among the children followed until a known outcome, 9% of children were symptomatic and in 97% of cases, the symptoms shown were of a minor-level severity (primarily drowsiness or restlessness). Depending on the substance, children who ingested doses 16 to 69 times the maximum recommended therapeutic dose remained asymptomatic. No deaths or severe symptoms were observed. No cases of lengthening of the QT interval or arrhythmias were identified. Mequitazine led to more symptoms than other substances (14.8% symptomatic children vs. 7.5%, Odd ratio (OR): 2.3 (2.0-2.6), p < 0.0001), more symptoms of moderate intensity (1.4 vs. 0.2%, OR: 8.3 (4.1-18.5), p < 0.0001) and more hospitalisation (19.1 vs. 8.7%, OR: 2.5, 95% CI: (2.2-2.8), p < 0.0001). The severity of poisoning from second-generation antihistamines appears to be low among children and considerably lower than poisoning caused by mequitazine

Synthesis of pillared clays from metallic salts as pigments for thermosolar absorptive coatings

[EN] A general procedure for developing stable solar absorptive coatings at both high temperature and a high solar radiation concentration is presented. In order to generally improve thermal efficiency, a coating with high solar absorptance is applied all over the surface of receiver tubes that is subjected to extreme working conditions. Consequently, a durable coating with high absorptivity for sunlight is needed. An alternative paint formulation research and development line to Pyromark-2500, the paint currently used in many commercial solar thermal power plants (CSP) is proposed. Pigment synthesis is developed by intercalating metallic salts into laminar or tubular clay structures. Metallic pxides, which provide paint with its color properties, are obtained by a calcination process. Addition of silane or surfactants during the pigment synthesis is also optimized. Once dried and ground to a precise size, pigments are mixed with a commercial binder and applied to a metallic substrate to study their properties. Thermal stability to high temperature is studied with different tests. The results showed that laminar structure was preferred to intercalate larger amounts of metallic salt into the clay structure, and no significant differences were found when using silane or surfactant modifiers. Although the highest absorptivity value was 85% after 24 h at 600 degrees C, samples presented very good adherence to the metallic substrate. Addition of a small quantity of commercial black pigment to the paint composition could improve the absorptivity and maintain the excellent adhesion shown. Furthermore, montmorillonite clay, modified with a surfactant before adding metallic salt, and without silane, resulted in a black pigment in a powder form. This pillared clay could be used in future paint formulations. (C) 2017 Elsevier Ltd. All rights reserved.The research that has led to these results was funded by Abengoa Solar New Technologies S.A. by a private contract with the Colour and Vision Group of the University of Alicante.Micó Vicent, B.; López-Herraiz, M.; Bello, A.; Martínez, N.; Martinez-Verdu, FM. (2017). Synthesis of pillared clays from metallic salts as pigments for thermosolar absorptive coatings. Solar Energy. 155:314-322. doi:10.1016/j.solener.2017.06.034S31432215