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[en] A radiological or nuclear incident could be characterized by high activity doses and high number of persons exposed. It is necessary to give a prompt response in order to know the number of exposed to internal contamination, to evaluate the contamination levels in each person and even to identify the radionuclides involved.In vitro laboratories routine monitoring measurements employed to quantify alpha and betta emitters in urine require radiochemical separation and long counting time, which implies a minimum of 1 or 2 weeks to obtain the results. In this work, rapid radiochemical separation method applied directly to urine is presented. Pu isotopes, Am and Cm isotopes, Uranium isotopes, Thorium isotopes, 90Sr, Tritium, 14C and 35S are isolated, measured by alpha spectrometry and liquid scintillation counting and quantify their activities. Finally, results of the participation in European Radiation Dosimetry Group intercomparison on Emergency Bioassay, Bundesamt für Strahlenschutz exercise and the Global Health Security Initiative / Radio-Nuclear Threats Working Group emergency intercomparison exercise validate the accuracy of this procedure
[es]Una emergencia radiológica o nuclear se puede caracterizar por dosis altas de actividad y un elevado número de personas afectadas. Una respuesta rápida y eficiente es imprescindible para conocer el alcance en la población afectada e incluso, para identificar los radionucleidos involucrados en la posible contaminación interna. Los laboratorios de medidas in vitro de los servicios de Dosimetría Interna emplean programas de monitorización en rutina para la cuantificación de actividad de emisores alfa y beta en muestras biológicas (bioensayos) aplicando protocolos de separación radioquímica y técnicas de medida con largos tiempos de contaje. Su aplicación permite alcanzar muy bajos niveles de detección, pero el largo periodo de procesamiento de la muestra hasta la obtención de resultados hace que este tipo de protocolos sean, a priori, incompatibles con la situación de emergencia previamente planteada. Se presenta en este trabajo, un procedimiento radioquímico rápido y secuencial aplicado a muestras de orina, que permite en un solo día separar en la misma muestra los siguientes radionucleidos: isótopos de Pu, Am, Cm, U, Th, 90Sr, 3H, 14C y 35S. Sobre las fracciones de muestra aisladas se aplican las técnicas de medida de espectrometría alfa y espectrometría de centello en fase líquida y espectrometría de masas, obteniéndose resultados de actividad en un tiempo inferior a los dos días. Este procedimiento ha sido validado mediante la participación en los ejercicios de intercomparación internacional para bioensayos en situaciones de emergencia organizados por Eurados (European Radiation Dosimetry Group), BfS (Bundesamt für Strahlenschutz –organismo regulador alemán–) y por la Iniciativa Global de Seguridad Sanitaria (GHSI) en colaboración con WHO y el OIEA comprobándose el grado de exactitud y precisión de los excelentes resultados obtenidos así como la capacidad de análisis, los tiempos de contaje, la actividad mínima detectable, el número de muestras a tratar simultáneamente o el tiempo de respuesta global.
[en] In the paper the investigation method of dynamic change of the concentration level of radioactive pollutant elements with half-lifeT1/2> 1 year on the land depended on year season has been considered. The method of variance mathematical analysis has been considered for study of dynamic of the oscillation of measured values.
[en] A re-usable in-situ-SQUID electrochemical cell for magnetisation studies during electrochemical cycling is presented. The proof of function is demonstrated by recording reversible magnetisation changes in LiFeO nanoparticles upon electrochemical cycling. The data imply the transition from inverse spinel structure (x=0) to a rocksalt phase (x=2). In addition, the setup is utilised to study the effect of lithiation on the Mott-Hubbard transition in VO.
[en] Topological descriptors are numerical parameters of a graph that characterize its topology and are usually graph invariant. In a QSAR/QSPR study, physicochemical properties and topological indices such as Randic, atom-bond connectivity, and geometric-arithmetic are used to predict the bioactivity of different chemical compounds. There are certain types of topological descriptors such as degree-based topological indices, distance-based topological indices, counting-related topological indices, etc. Among degree-based topological indices, the so-called atom-bond connectivity and geometric-arithmetic are of vital importance. These topological indices correlate certain physicochemical properties such as boiling point, stability, strain energy, etc., of chemical compounds. In this paper, analytical closed formulas for Zagreb indices, multiplicative Zagreb indices, harmonic index, and sum-connectivity index of the strong product of graphs are determined. (author)
[en] Radicals are part of the chemistry of life, and ionizing radiation chemistry serves as an indispensable research tool for elucidation of the mechanism(s) underlying their reactions. The ever-increasing understanding of their involvement in diverse physiological and pathological processes has expanded the search for compounds that can diminish radical-induced damage. This review surveys the areas of research focusing on radical reactions and particularly with stable cyclic nitroxide radicals, which demonstrate unique antioxidative activities. Unlike common antioxidants that are progressively depleted under oxidative stress and yield secondary radicals, nitroxides are efficient radical scavengers yielding in most cases their respective oxoammonium cations, which are readily reduced back in the tissue to the nitroxide thus continuously being recycled. Nitroxides, which not only protect enzymes, cells, and laboratory animals from diverse kinds of biological injury, but also modify the catalytic activity of heme enzymes, could be utilized in chemical and biological systems serving as a research tool for elucidating mechanisms underlying complex chemical and biochemical processes.
[en] This paper investigates the influence of the cell compression of a PEM water electrolysis cell. A small single cell is therefore electrochemically analyzed by means of polarization behavior and impedance spectroscopy throughout a range of currents (0.01 A cm−2 to 2.0 A cm−2) at two temperatures ( and ) and eight compressions (0.77 MPa–3.45 MPa). Additionally, a computational model is utilized to support the analysis. The main findings are that cell compression has a positive effect on overall cell performance due to decreased contact resistances, but is subject to optimization. In this case, no signs of severe mass transport problems due to crushed transport layers are visible in either polarization curves or impedance plots, even at high currents. However, a Tafel plot analysis revealed more than one slope throughout the current range. The change in the Tafel slope is therefore discussed and connected to the electrochemical reaction or an ohmic contribution from a non-electrode component.
[en] In the present study, an electrochemical behavior, the charge (Q) estimated from reductive desorption voltammograms, of the binary self-assembled monolayer (SAMs) prepared by immersing the primary 4-pyridineethanethiol (PET-SAM) into the solution of 2-aminoethanethiol (AET) was investigated for enhancing the sensitivity of Hg(II) detection. The optimized conditions was selected to be 20 minutes for immersion in the concentration of 0.1 mM AET solution to reach the maximum peak current (ipHg) obtained by differential pulse voltammetry for detection of Hg(II). Interestingly, the variation of Q by these factors was similar with that of ipHg, indicating the role of the introduction of the second component, AET, in kinetic formation of the binary SAMs for enhancing sensitivity of Hg(II) detection at ultra trace level. (author)
[en] Highlights: • Two new dibromo 7-hydroxycoumarins have been synthesized and their complexes with Cu(II) were obtained. • Geometry of two new Cu(II) complexes of 6/8-acetyl-3,6/8-dibromo-7-hydroxy-4-metylocoumarin in have been determined. • Molecular structure of the complexes have been studied for non-crystalline form using methodology based on XFAS. - Abstract: Two new copper(II) complexes based on 6/8-acetyl-3,8/6-dibromo-7-hydroxy-4-methylcoumarin have been synthesized and structurally characterized. The electrochemical synthesis has been applied to enforce the complexation reaction. Characterization of non-crystalline product have been performed using methodology based on X-ray absorption spectroscopy. Both compounds have square planar geometry with four oxygen atoms in the nearest distance to the copper(II) ion. The hydroxycoumarin ligands coordinate to the cooper(II) either in bidentate or monodentate manner depending on the acetyl group position in the coumarin ring. The complexes have been evaluated from microbiological and cytotoxic point of view, but no significant activity has been found.
[en] With the recent growing interest for soft actuation, many new types of ionic polymers working in air have been developed. Due to the interrelated mechanical, electrical, and chemical properties which greatly influence the characteristics of such actuators, their behavior is complex and difficult to understand, predict and optimize. In light of this challenge, an original linear multiphysics finite difference bond graph model was derived to characterize this ionic actuation. This finite difference scheme was divided into two coupled subparts, each related to a specific physical, electrochemical or mechanical domain, and then converted into a bond graph model as this language is particularly suited for systems from multiple energy domains. Simulations were then conducted and a good agreement with the experimental results was obtained. Furthermore, an analysis of the power efficiency of such actuators as a function of space and time was proposed and allowed to evaluate their performance. (paper)
[en] The electrochemical behavior of a new type of stable diarylnitroxide radicals with bulky substituent in the ortho-position of one of the phenyl rings is described. The presence of the substituent results in broken conjugation of one of the phenyl rings with the NO moiety (the other ring stays conjugated) giving rise to so called “twisted nitroxides”. New diphenylnitroxides with t-Bu and/or CF3 substituents were synthesized and are the first examples of diarylnitroxides which are extremely stable in solution and form both stable oxidized and reduced forms (oxoammonium cations and aminoxyl anions). These compounds exhibit fast ET kinetics and reversible electrochemical oxidation and reduction. Varying the torsion angle θ shifts Eox and Ered values in the opposite directions thus increasing the electrochemical potential gap, contrary to the traditional effects of substituents that commonly shift both potential values in the same direction. The electronic effect of the substituents in the ortho-position as well as the total electronic effect of both rings on the electrochemical potential values was estimated using the linear fit for the relationship between vs. the sum of Hammett constants (σp + σo·cosθ). The ρ value (the slope in the linear fit) is 0.501 indicating significant sensitivity of the potential values to the electronic effects and wide possibilities for tuning. The results obtained shed light on the efficient principles of molecular design for stable electroactive nitroxide-based materials.