Neutron spectra from Neutron Standards Laboratory (LPN/CIEMAT) sources with two Bonner sphere spectrometers

The Neutron Standards Laboratory (LPN: Laboratorio de Patrones Neutrónicos) of the Ionizing Radiation Metrology Laboratory (LMRI) of the CIEMAT (Centro de Investigaciones Energéticas Medioambientales y Tecnológicas) has two calibration neutron sources, 241Am-Be and 252Cf. Studies to verify the shielding of the facility and to characterize the neutron field in the irradiation room have been carried out using Monte Carlo methods. However, spectral measurements were not performed yet. In this study, we measured the total and direct neutron spectra of both calibration neutron sources. Two different Bonner Sphere Spectrometers (BSS) systems were allocated to 115 cm from the sources, on the calibration bench, with and without the shadow cones (SC). From the count rates obtained with both BSS systems (BSS-6LiI and BSS-3He), the total neutron spectrum and direct neutron spectrum were unfolded. Total and direct spectra obtained for the 241Am-Be and 252Cf sources with the MCNPX and different BSS systems, unfold codes and response matrices presented similar shape and are consistent with each other

A 222 Energy Bins Response Matrix fora 6LiI Scintillator BSS system

A new response matrix was calculated for a Bonner Sphere Spectrometer (BSS) with a 6LiI(Eu) scintillator. We utilized the Monte Carlo N-Particle radiation transport code MCNPX, version 2.7.0, with ENDF/B-VII.0 nuclear data library to calculate the responses for 6 spheres and the bare detector, for energies varying from 9.441E(-10) MeV to 105.9 MeV, with 20 equal-log(E)-width bins per energy decade, totalizing 222 energy groups. A BSS, like the modeled in this work, was utilized to measure the neutron spectrum generated by the 241AmBe source of the Universidad Politécnica de Madrid (UPM). From the count rates obtained with this BSS system we unfolded neutron spectrum utilizing the BUNKIUT code for 31 energy bins (UTA4 response matrix) and the MAXED code with the new calculated response functions. We compared spectra obtained with these BSS system / unfold codes with that obtained from measurements performed with a BSS system constituted of 12 spheres with a spherical 3He SP9 counter (Centronic Ltd., UK) and MAXED code with the system-specific response functions (BSS-CIEMAT). A relatively good agreement was observed between our response matrix and that calculatedby other authors. In general, we observed an improvement in the agreement as the energy increases. However, higher discrepancies were observed for energies close to 1E(-8) MeV and, mainly, for energies above 20 MeV. These discrepancies were mainly attributed to the differences in cross-section libraries employed. The ambient dose equivalent (H*(10)) calculated with the 6LiI-MAXED showed a good agreement with values measured with the neutron area monitor Berthold LB 6411 and within 12% the value obtained with another BSS system (BSS-CIEMAT). The response matrix calculated in this work can be utilized together with the MAXED code to generate neutron spectra with a good energy resolution up to 20 MeV. Some additional tests are being done to validate this response matrix and improve the results for energies higher than 20 MeV

The effects of heat-moisture treatment on avocado starch granules: thermoanalytical and structural analysis

The avocado (Persea americana, Miller) is a very popular tree worldwide. It is native to Central/North America (Mexico) and its fruit is healthy and is consumed in large quantities worldwide. Several studies revealed that a diet enriched with avocado fruit lowers total cholesterol and low-density lipoproteins levels without changing high density lipoprotein levels. The seeds of the avocado constitute a high percentage of the fruit's mass and they are often discarded as industrial waste. These seeds contain an important amount of starch and there is lack of study regarding the physicochemical properties of this biopolymer. Heat-moisture treatment (HMT) of starch is a physical method considered to be natural; it consists of heating starch at a temperature above its gelatinisation point, with insufficient moisture (< 35 %) to cause gelatinisation. Stoichiometrically distilled water (up to 10, 20 and 30 %, w/w) was added to untreated samples of avocado starch (moisture around 9 %) and then each sample was homogenised and sealed into 100 mL pressure flasks, sealed tightly with a cap and maintained in an autoclave at 120 A degrees C for 60 min. After this time, each sample was investigated using the following techniques: simultaneous thermogravimetry-differential thermal analysis; differential scanning calorimetry; non-contact atomic force microscopy; rapid viscoamylographic analysis; atomic force microscopy; and X-ray powder pattern diffractometry.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Thermal analysis as a screening technique for the characterization of babassu flour and its solid fractions after acid and enzymatic hydrolysis

The babassu (Orbignya phalerata) is a native tree found in northern Brazil. Extracts of the babassu coconut have been widely used in industry. Babassu flour has about 60% starch, thus, besides nourishment it can be used as an alternative biofuel source. However, the properties of this starch lack of study and understanding. The main purpose of this study was to investigate the thermal behavior of raw babassu flour and its solid hydrolyzed fraction. The analyses were carried out using SHIMADZU DSC and TG thermic analyzers. The results demonstrated a reduction in thermal stability of the solid hydrolyzed fraction compared to raw matter. The kinetic parameters were investigated using non-isothermal methods and the parameters obtained for its decomposition process were an E(a) of 166.86 kJ mol(-1) and a frequency factor (beta) of 6.283 x 1014 min(-1); this was determined to be a first order reaction (n = 1). (C) 2011 Elsevier B.V. All rights reserved

An Intron 9 CYP19 Gene Variant (IVS9+5G>A), Present in an Aromatase-Deficient Girl, Affects Normal Splicing and Is Also Present in Normal Human Steroidogenic Tissues

Background/Aims: Splicing CYP19 gene variants causingaromatase deficiency in 46,XX disorder of sexual development(DSD) patients have been reported in a few cases. Amisbalance between normal and aberrant splicing variants was proposed to explain spontaneous pubertal breast developmentbut an incomplete sex maturation progress. Theaim of this study was to functionally characterize a novelCYP19A1 intronic homozygote mutation (IVS9+5G>A) in a46,XX DSD girl presenting spontaneous breast developmentand primary amenorrhea, and to evaluate similar splicing variant expression in normal steroidogenic tissues. Methods:Genomic DNA analysis, splicing prediction programs,splicing assays, and in vitro protein expression and enzymeactivity analyses were carried out. CYP19A1 mRNA expressionin human steroidogenic tissues was also studied. Results:A novel IVS9+5G>A homozygote mutation was found.In silico analysis predicts the disappearance of the splicingdonor site in intron 9, confirmed by patient peripheral leukocytecP450arom and in vitro studies. Protein analysisshowed a shorter and inactive protein. The intron 9 transcriptvariant was also found in human steroidogenic tissues.Conclusions: The mutation IVS9+5G>A generates a splicingvariant that includes intron 9 which is also present in normalhuman steroidogenic tissues, suggesting that a misbalancebetween normal and aberrant splicing variants might occurin target tissues, explaining the clinical phenotype in the affectedpatient.Fil: Saraco, Nora Isabel. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nesi Franca, Suzana. Universidade Federal do Paraná; BrasilFil: Sainz, Romina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; ArgentinaFil: Marino, Roxana Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; ArgentinaFil: Marques Pereira, Rosana. Universidade Federal do Paraná; BrasilFil: La Pastina, Julia. Universidade Federal do Paraná; BrasilFil: Perez Garrido, Natalia. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; ArgentinaFil: Sandrini, Romolo. Universidade Federal do Paraná; BrasilFil: Rivarola, Marco Aurelio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; ArgentinaFil: Lacerda, Luiz de. Universidade Federal do Paraná; BrasilFil: Belgorosky, Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría ; Argentin

Espectrometría y Dosimetría Neutrónica con Redes Neuronales y Esferas Bonner: Un Estudio para Reducir el Número de Esferas

Para la espectrometría y dosimetría de neutrones el Sistema Espectrométrico de Esferas Bonner ha sido el sistema más usado, sin embargo, el número, tamaño y peso de las esferas que componen al sistema, la necesidad de utilizar un código de reconstrucción y los largos periodos de tiempo empleados para realizar las mediciones, son algunos de los inconvenientes que este sistema presenta. Para la reconstrucción de los espectros se han usado diferentes técnicas como las redes neuronales artificiales de propagación inversa. El objetivo de este trabajo fue reducir el número de esferas Bonner y usar las rapideces de conteo en una red neuronal de propagación inversa, optimizada por medio de la metodología de diseño robusto, para reconstruir los espectros de neutrones. Para el diseño de la red neuronal (RN) se usaron los espectros de neutrones del OIEA y la matriz de respuesta de las esferas Bonner con detector de 6 LiI(Eu). Se comparó el desempeño de la red usando 7 esferas Bonner que se comparó con el caso donde solo se usan 2 esferas y 1 esfera. Las topologías de red se entrenaron 36 veces para cada caso manteniendo constante el error objetivo (1E(-3)), el algoritmo de entrenamiento fue trainscg y la metodología de diseño robusto para determinar las mejores arquitecturas de red. Con éstas, se compararon los mejores y peores resultados. Se encontró que los resultados que se obtienen usando 7 esferas son semejantes a los obtenidos con la esfera de 5 in, sin embargo aún se encuentra en una etapa de análisis de información