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  • Author or Editor: A. Gutiérrez x
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Abstract  

The establishment of a quality management system is the best way to comply with international requirements concerning the achievement of confident and traceable analytical results. Some important points dealing with the technical factors of quality management in gamma-ray spectrometry of environmental samples are discussed. The experience obtained from analytical procedure validation is presented. Results of the application of standardized procedures to the analysis of ALMERA intercomparison samples, as well as the outcome of the utilization of certified reference materials for the quality control of measurement are presented. In fact, the implantation of simple technical principles reports reliable results and allows to elevate the quality of the measurements at a cost relatively low according to the real possibilities of the small laboratories, even in developing countries.

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Abstract  

A great variety in retention properties occurs as a result of different methods of preparation of the sorbents. Specific surfaces and porosities, which are mostly connected with the sorption activities, may vary widely. The activation of Al2O3, SnO2 and silica gel, to produce highly active sorbents occurs only if the oxide is contacted with acid immediately after thermal treatment. The efficiency of the separation scheme has been tested using uranium and fission products under static conditions from strongly alkaline aqueous solutions.

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Journal of Thermal Analysis and Calorimetry
Authors: C. Pico, A. Jerez, M. L. Veiga, and E. Gutierrez-Rios

The processes involved in the isothermal dehydration of hexaoxytelluric acid, Te(OH)6, are studied and the kinetic equations and activation energies corresponding to these processes are determined. The results are in agreement with a previously proposed structural model.

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Journal of Thermal Analysis and Calorimetry
Authors: C. González, J. I Gutiérrez, J. R. González-Velasco, A. Cid, A. Arranz, and J. F. Arranz

Thermal decomposition of various synthetic manganese oxides (MnO, Mn3O4, Mn2O3, MnOOH) and a natural manganese dioxide (MnO2) from Gabon was studied with the help of termogravimetry in inert, oxidizing and reducing atmospheres. The compounds were characterized by XRD and electrochemical activity was tested by cyclic voltammetry using a carbon paste electrode. The natural manganese dioxide showed the best oxidizing and reducing capacity, confirmed by the lower temperatures of the transitions, the extent of the reactions and electrochemical performance in cyclic voltammograms.

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Abstract  

Trace metal advection and diffusion in natural porous and fractured materials have been investigated by using radiotracers. Three case studies are presented: 1) Se infiltration in granite cores in the presence of pyrite, 2) Co advection in quartz sand columns containing a layer of MnO2, and 3) Cr diffusion in clay. It is shown that the migration processes are controlled by surface mediated redox transformations.

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Summary Non-isothermal thermogravimetric data were used to evaluate the Arrhenius parameters (activation energy and the pre-exponential factor) of the combustion of two carbonaceous materials, selected as diesel soot surrogates. The paper reports on the application of model-free isoconversional methods (Flynn-Wall-Ozawa and Kissinger methods) for evaluating the activation energy of the combustion process. On the other hand, by means of the compensation relation between E and lnA, which was established by the model-dependent Coats-Redfern method, the value of the pre-exponential factor was estimated from the known value of the model-independent activation energy.

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The best alternative for reducing citrus production costs is mechanization. Machine vision is a reliable technology for the automatic inspection of fresh fruits and vegetables that can be adapted to harvesting machines. In these, fruits can be inspected before sending them to the packinghouse and machine vision provides important information for subsequent processing and avoids spending further resources in non-marketable fruit. The present work describes a computer vision system installed on a harvesting machine developed jointly by IVIA and a Spanish enterprise. In this machine, hand pickers directly drop the fruit as they collect it, which results in an important increase of productivity. The machine vision system is placed over rollers in order to inspect the produce, and separate those that can be directly sent to the fresh market from those that do not meet minimal quality requirements but can be used by the processing industry, based on color, size and the presence of surface damages. The system was tested under field conditions.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: A. Perera, C. Perez, M. Torres, A. Henandez, F. Heres, T. Moreira, A. Gutierrez, A. Gigato, I. Hernandez, L. Alberti, O. Marrero, L. Martinez, J. Sanfiz, E. Sanchez, J. Rodriguez, L. Marrero, and G. Parra

Abstract  

The aim of this work was to obtain a freeze-dried kit for direct99mTc-labeling of human polyclonal IgG. The labeling procedure was carried out by Schwarz's method. The best yields of99mTc-IgG were obtained by using sodium pyrophosphate decahydrate as a weak chelating agent. Performed tests showed the stability of the radiopharmaceutical up to 24 hours. Plasma clearance in rats was fitted to a biexponential curve withT 1/2α=(0.1 ±0.9) h andT 1/2β=(10±3) h. The organs with higher uptake of radiopharmaceutical were lung, kidneys and blood. In a rabbit model the abscess target/background ratio was 3–6 according to time of the scintigraphic images. Thirty patients with musculoskeletal infection were studied. Twenty-one lesions were detected and confirmed by culture/biopsy.

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