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Abstract Nowadays, the experiments related to High Energy Physics and others fields demand the use of detectors with greater radiation resistance, and the novel material GaAs:Cr has demonstrated excellent radiation hardness compared with other semiconductors. On the basis of evidence obtained in the JINR experiment with the use of 22 MeV electrons beam generated by the LINAC-800 accelerator, an analysis of electron radiation effects on GaAs:Cr and Si detectors is presented. The measured I-V characteristics showed a dark current increase with dose, and an asymmetry between the two branches of behaviors for all detectors. Analyzing the MIP spectra and CCE dose dependence measurements a deterioration process of detectors collection capacity with dose increase was found, although behaviors are somewhat different according to the detector type. The detailed explanation of these effects from the microscopic point of view appears in the text, and are generally linked to the generation of atomic displacement, vacancies and other radiation defects, modifying the energy levels structure of the target material. These changes affect the lifetime and concentration of the charge carriers, and other characteristics of the target material.

Resumen Actualmente, los experimentos relacionados con la física de altas energías y otros campos, demandan el uso de detectores con mayor resistencia a las radiaciones y el novedoso material GaAs:Cr ha demostrado poseer una excelente fortaleza comparado con otros semiconductores. En base a las evidencias obtenidas en el experimento del IUIN con el uso de un haz de electrones de 22 MeV generado por el acelerador LINAC-800, se presenta un análisis de los efectos de la radiación en detectores de Si y GaAs:Cr. Las características I-V medidas mostraron un incremento de la corriente de fuga con la dosis y una asimetría entre las dos ramas de estos comportamientos para todos los detectores. Analizando las mediciones de los espectros MIP y la dependencia de la CCE con la dosis, fue encontrado un proceso de deterioro de la capacidad de detección de los detectores con el aumento de la dosis, sin embargo, los comportamientos son diferentes de acuerdo al tipo de detector. La explicación detallada de estos efectos desde el punto de vista microscópico aparece en el texto, los cuales están relacionados generalmente con la generación de desplazamientos atómicos, vacancias y otros defectos producto de la radiación, modificando la estructura de los niveles energéticos en el material sensor. Estos cambios afectan el tiempo de vida y la concentración de los portadores de carga, así como otras características del material.

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Several studies have reported that lactic acid bacteria may increase the production of free fatty acids by lipolysis of milk fat, though no studies have been found in the literature showing the effect of kefir grains on the composition of fatty acids in milk. In this study the influence of kefir grains from different origins [Rio de Janeiro (AR), Viçosa (AV) e Lavras (AD)], different time of storage, and different fat content on the fatty acid content of cow milk after fermentation was investigated. Fatty acid composition was determined by gas chromatography. Values were considered significantly different when p<0.05. The highest palmitic acid content, which is antimutagenic compost, was seen in AV grain (36.6g/100g fatty acids), which may have contributed to increasing the antimutagenic potential in fermented milk. Higher monounsaturated fatty acid (25.8 g/100g fatty acids) and lower saturated fatty acid (72.7 g/100g fatty acids) contents were observed in AV, when compared to other grains, due to higher Δ9-desaturase activity (0.31) that improves the nutritional quality of lipids. Higher oleic acid (25.0 g/100g fatty acids) and monounsaturated fatty acid (28.2g/100g fatty acids) and lower saturated fatty acid (67.2g/100g fatty acids) contents were found in stored kefir relatively to fermented kefir leading to possible increase of antimutagenic and anticarcinogenic potential and improvement of nutritional quality of lipids in storage milk. Only high-lipidic matrix displayed increase polyunsaturated fatty acids after fermentation. These findings open up new areas of study related to optimizing desaturase activity during fermentation in order to obtaining a fermented product with higher nutritional lipid quality.

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The aim of this study was to determine the selection of bedding material by broiler chickens during the rearing period and whether the choice was determinant to their performing a specific behavior. To achieve this objective, a choice test was designed. A choice pen was constructed where birds could move freely around the four selected materials (straw, wood shavings, rice hulls and sand). Chickens were introduced in this pen in four groups of eight birds, three days a week for one hour per day and group, for four weeks. The location and the activity performed by each broiler were recorded every five minutes. Results showed a preference for sand compared with the other three substrates. However, differences between the behaviors performed in each bedding material were shown mainly for resting (preferably performed on wood shavings and straw), dust bathing (on sand), pecking and scratching (on rice hulls). Other factors, such as the time of day, were also found to have effects on fighting and drinking, and changes in behavioral patterns (resting, preening, eating, standing and pecking) were also detected as broilers grew older.(AU)

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The hydrolysis of effluent from a poultry slaughterhouse containing 800 mg oil and grease (O&G)/L was conducted with 1% (w/v) of an enzymatic pool obtained by solid-state fermentation with the fungus Penicillium restrictum. The chromatographic evaluation of the lipid profile during hydrolysis indicated a higher concentration of acids after 4h of reaction (2954 mg/L), with a predominance of oleic, palmitic, and linoleic acids. Effluent aliquots were collected after 4, 8, and 24h of hydrolysis and tested for anaerobic biodegradation in sequential batches. An adaptation of the biomass was observed, both in the control experiment (with non-hydrolyzed raw effluent) and in the experiments with enzymatically pre-treated effluent. The specific methane production in the control experiment was 0.248 L CH(4)/g COD(consumed), and in the experiment with effluent pre-treated for 4h, this production was 0.393 L CH(4)/g COD(consumed), indicating a higher methane production after enzymatic hydrolysis.

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Variation in the mtDNA 16S ribosomal RNA gene in populations of Triatoma infestans (Klug) was surveyed. DNA sequence comparisons yielded 18 haplotypes among 130 individuals from 16 localities that represent a large proportion of the range of T. infestans in Argentina. The most common genotype in all populations was found in 76.9% of individuals and two other haplotypes were shared among different populations. The remaining 15 haplotypes were present exclusively in one of the populations, suggesting currently low levels of genetic exchange. Analysis of mtDNA 16S sequences uncovered substantial genetic variation among T. infestans populations. Haplotype and nucleotide diversities varied among populations, from 0% to 0.84% and 0% to 0.29%, respectively. It appears that this locus has a low mutation rate. Uncorrected pairwise differences of T. infestans haplotypes ranged from 0% to 1.2%. The molecular phylogeny supported the monophyly of T. infestans haplotypes and clustered two different pairs of haplotypes with a moderate degree of bootstrap support (approximately 60%). Mitochondrial DNA phylogeographic differentiation was not evident, suggesting a recent rapid spread of the species. Analysis of molecular variance showed hierarchical structure in the data. Considerably less variation was found among T. infestans populations from the northwest and northeast regions than among those belonging to the central area. Such a lack of variation may be indicative of one or more past population bottlenecks.

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Placental transfer of the long-chain polyunsaturated fatty acids (LCPUFA) arachidonic (AA) and docosahexaenoic (DHA) acids is selectively high to maintain accretion to fetal tissues, especially the brain. The objectives of the present study were to investigate the essential fatty acid (EFA) and LCPUFA status at birth of preterm and term Brazilian infants and their mothers, from a population of characteristically low intake of n-3 LCPUFA, and to evaluate the association between fetal and maternal status, by the determination of the fatty acid composition of the erythrocyte membrane. Blood samples from umbilical cord of preterm (26-36 weeks of gestation; n = 30) and term (37-42 weeks of gestation; n = 30) infants and the corresponding maternal venous blood were collected at delivery. The LCPUFA composition of the erythrocyte membrane and DHA status were similar for mothers of preterm and term infants. Neonatal AA was higher (P < 0.01) whereas its precursor 18:2n-6 was lower (P < 0.01) than maternal levels, as expected. There was no difference in LCPUFA erythrocyte composition between preterm and term infants, except for DHA. Term infants presented a worse DHA status than preterm infants (P < 0.01) and than their mothers (P < 0.01) at delivery. There was a negative correlation of neonatal DHA with maternal AA and a positive correlation between neonatal AA and maternal AA and 18:2n-6 only at term. These results suggest that the persistent low DHA maternal status, together with the comparatively better AA and 18:2n-6 status, might have affected maternal-fetal transfer of DHA when gestation was completed up to term, and possibly contributed to the worse DHA status of term neonates compared with the preterm neonates.

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