ABSTRACT This study aimed to evaluate the effect of different levels of omega-3 polyunsaturated fatty acids (n-3 PUFA) in the diet of Sardinella brasiliensis on their hematological parameters. A total of 375 fish were distributed in 15 experimental units to evaluate the effects of the diet on their blood for 45 days. The levels of n-3 PUFA added in the diet were 0, 0.3, 0.6, 0.9, and 1.2% of the lipid fraction. These values represent the total percentage of n-3 PUFA in the lipid fraction of the diet, and 0% n-3 PUFA was used as the negative control. Five fish from each experimental unit were sampled at the end of the experiment for hematological analysis, and the parameters measured include the total number of erythrocytes, hematocrit percentage, hemoglobin and glucose concentration and differential leukocyte count. Higher numbers of circulating eosinophils were observed in fish fed 0.3% and 1.2% n-3 PUFA. Although no significant differences were observed in several of the parameters, the results demonstrate that the health of the sardines was not affected by the addition of n-3 PUFA in their diet. It should be emphasized that this is the first study with emphasis on the blood analysis of S. brasiliensis. omega3 omega 3 omega- n3 n (n- 37 1 4 days n- 0 03 0.3 06 6 0.6 09 9 0.9 12 2 1.2 control erythrocytes count S (n 0. 1.

RESUMO O objetivo deste estudo foi avaliar o efeito de diferentes níveis de ácidos graxos poli-insaturados ômega-3 (PUFA n-3) na dieta de Sardinella brasiliensis sobre seus parâmetros hematológicos. Um total de 375 peixes foi distribuído em 15 unidades experimentais para avaliar os efeitos da dieta em seu sangue durante 45 dias. Os níveis de PUFA n-3 adicionados à dieta foram 0, 0,3, 0,6, 0,9 e 1,2% da fração lipídica. Esses valores representam a porcentagem total de PUFA n-3 na fração lipídica da dieta, e 0% de PUFA n-3 foi usado como controle negativo. Cinco peixes de cada unidade experimental foram amostrados no final do experimento para análise hematológica, e os parâmetros medidos incluem o número total de eritrócitos, a porcentagem de hematócrito, a concentração de hemoglobina e glicose e a contagem diferencial de leucócitos. Foram observados números mais altos de eosinófilos circulantes em peixes alimentados com 0,3% e 1,2% de PUFA n-3. Embora não tenham sido observadas diferenças significativas em vários dos parâmetros, os resultados demonstram que a saúde das sardinhas não foi afetada pela adição de PUFA n-3 em sua dieta. Deve ser enfatizado que este é o primeiro estudo realizado com ênfase na análise sanguínea de S. brasiliensis. poliinsaturados poli insaturados ômega3 ômega 3 ômega- n3 n hematológicos 37 1 4 dias n- 0 03 0,3 06 6 0,6 09 9 12 2 1,2 negativo hematológica eritrócitos hematócrito leucócitos n3. 3. S 1,

AISI 420 steel samples were subjected to three heat treatment conditions: annealed, hardened, and tempered at 400°C, followed by low-temperature nitriding using N2, H2, and varying Ar proportions in a pulsed DC glow discharge. The study aimed to investigate the impact of varying Ar content (10–50 vol.%) on glow discharge characteristics and surface properties of nitrided samples, using an 80% N2 + 20% H2 base gas mixture. The samples underwent characterization including optical microscopy, X-ray diffractometry, microhardness, and roughness measurements. Plasma characterization was conducted using optical emission spectroscopy. The results indicated that higher Ar concentrations led to increased thickness of the nitrided layer (up to 67%), as well as hardness (up to 14%) and surface roughness (up to 50%). These improvements stemmed from increased Ar-based species bombardment on the surface, enhancing the cleaning effect of surface oxides. This facilitated nitrogen adsorption onto the steel surface, increasing the atomic nitrogen concentration in the outermost layer of the steel. The increased nitrogen concentration facilitated diffusion, resulting in significant physical-chemical reactions at the surface-plasma interface. These reactions, including sputtering, molecule dissociation, and recombination, led to enhanced high-diffusivity pathways within the martensitic microstructures of both the as-hardened and 400°C-tempered samples. 42 conditions annealed hardened 400C C 400 400°C lowtemperature low temperature N H 10–50 1050 10 50 (10–5 vol.% vol 80 20 mixture microscopy Xray X ray diffractometry microhardness measurements spectroscopy up 67%, 67 67% , 67%) 14% 14 50%. 50% . 50%) Arbased based oxides diffusion physicalchemical physical chemical surfaceplasma plasma interface sputtering dissociation recombination highdiffusivity high diffusivity ashardened 400°Ctempered 400Ctempered Ctempered 4 40 10–5 105 1 5 (10– vol. 8 2 6 10– (10 (1 (

Abstract This work reports an experimental investigation on the thermodynamic and kinetic view-point of the nitrided layer growth behavior, carried out separately at ferrite and austenite phase grains, for the UNS S32750 super duplex stainless steel (SDSS). For this purpose, and motivated by the DSSs distinct behavior showing formation of two- or single-phase nitrided layers, which apparently depend on the steel substrate chemical composition, two series of treatment were studied here, one varying the nitriding temperature on the 300-450 °C range for 4 h time, and other one varying the time on the 2-8 h range at 350 °C. Microstructural characterization of studied layers by means of SEM and EDS analysis, XRD and microhardness measurements showed precipitation-free nitrogen-expanded austenite layer formation on both steel phases for all samples treated up to 400 °C. The nitriding kinetics study showed that the layer thickness on both steel phases is proportional to the square root of the treatment time and follows an Arrhenius law for the studied treatment temperatures. The nitrogen diffusion activation energy, separately determined from the layer growth on each steel phase, was 115±3.2 and 120±5.4 kJmol-1, for austenite and ferrite grains, respectively.

Abstract In the present work, the influence of the pulse voltage and pressure on the treatment glow discharge characteristics and consequently on the surface properties obtained for low temperature plasma carburized AISI 420 martensitic stainless steel was investigated. Two distinct sets of samples were carburized at 450 °C, for 8 h, one aiming to study the applied pulse voltage effects, which was varied for 500, 600 and 700 V, at a fixed pressure of 400 Pa, and the other aiming to study the pressure effects, which was varied for 200, 400, and 800 Pa, at a fixed pulse voltage of 700 V. Treated samples were characterized by means of confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD) analysis, microhardness and roughness measurements. The glow discharge (plasma) was characterized by optical emission spectroscopy (OES) and current measurements. Results show that the edge effect, surface roughness, hardness and outer layer growth kinetics are dependent on the studied plasma parameters. OES analyses showed that the pulse voltage parameter does not promote significant changes on the plasma chemistry, but confirmed that the molecular H2 gas dissociation rate tends to be significantly affected by the pressure parameter giving important support for the results obtained here.

We present a case study of the conceptions teachers and parents hold about the children’s learning of writing, in educational communities in middle and excluded sociocultural environments in Bariloche, Argentina. In particular, their ideas about the following issues are described: how children learn to write, what children do when they learn, how children realize they learn, how teachers and parents realize children learn. Data collection consisted in individual interviews. Verbal responses were analysed with the lexicometric method, allowing to distinguish three groups, by associating characteristic words and modalities of the combined variable educational position (teacher vs. parent) - sociocultural environment (middle vs. excluded). On this basis, we described three conceptions of learning and teaching of writing: a) learning based on teacher’s verification of learning results, and teaching based on the impression of knowledge (characteristic of teachers working in excluded environments); b) learning based on the activation and connection of prior knowledge, and teaching based on channelling and enlarging prior knowledge (teachers working in middle sociocultural environments) and c) learning based on children’s natural orientation to learn, and teaching based on the provision of models and on the response to children’s demands (parents from both environments). We propose that the first conception is related to a direct or copy theory of mind, whereas the other two are versions of an interpretative theory of mind. Educational implications are discussed.

Se presenta un estudio de casos de las concepciones de padres y maestros de comunidades educativas en entornos socioculturales medios y marginados en Bariloche, Argentina, acerca de cómo los niños aprenden a escribir. En particular, se describe y analiza cómo suponen que los niños aprenden a escribir, qué hacen cuando aprenden, cómo los niños se dan cuenta de sus aprendizajes y cómo padres y maestros se dan cuenta de los aprendizajes de los niños. El relevamiento de los datos se llevó a cabo mediante entrevistas individuales. Las respuestas verbales de los sujetos se analizaron mediante el método lexicométrico o análisis de datos textuales, que diferenció tres grupos que asocian palabras características y modalidades de la variable combinada posición educativa (padre/maestro) - sector sociocultural (medio/marginado). Sobre esta base, describimos tres concepciones de aprendizaje y de enseñanza de la escritura: a) aprendizaje basado en la verificación de lo aprendido por parte del maestro y enseñanza basada en la impresión de conocimientos (característica de maestros de sectores marginados); b) aprendizaje basado en la activación y conexión de los conocimientos previos y enseñanza basada en el encauzamiento y ampliación de los conocimientos previos (maestros de sectores medios); c) aprendizaje basado en la "natural" orientación de los niños hacia el aprendizaje y enseñanza basada en provisión de modelos y respuesta a demandas de los niños (padres de ambos sectores). Se plantea que la primera concepción se vincula con una teoría directa o de la copia de la mente del aprendiz, en tanto las otras dos serían versiones de una teoría interpretativa de la mente. Se discuten las implicancias educativas de esta situación.