Microstructure and wear behaviour of high alloyed hot-work tool steels 1.2343 and 1.2367 under thermo-mechanical loading

Tools and their maintenance costs in hot forging processes account for a considerable proportion of the total components' costs. Forging tools undergo extreme heating and subsequent cooling during the forging process and between the forging cycles, respectively. This cyclic heating and cooling of the tool surfaces leads to local changes in the tool microstructure which result in hardening or softening of the material in different regions of the tool and consequently influence the tool strength. Temperature in the tool areas experiencing high thermo-mechanical loadings can exceed the austenitic temperature. Hence, a strong cooling, for example by spraying or lubrication, can lead to formation of a martensitic layer in the boundary zone of the tool. Due to its higher hardness, martensitic layer has greater resistance to wear as compared to the basic or tempered materials. In the scope of this paper, the austenitisation behaviours of two high alloyed hot-work tool steels, 1.2343 and 1.2367, have been characterized by means of dilatometer tests to obtain time-temperature-austenitisation (TTA) diagrams for specimen under thermo-mechanical loads. Moreover, continuous-cooling-transformation (CCT) diagrams were recorded. Metallographic investigations were carried out to gather a detailed understanding of the microstructure behaviour and its resulting hardness. With the results of this works, it is aimed to gather a detailed and accurate insight into the arising hardening and softening effects. This would eventually lead to an optimisation of the numerical modelling for tool wear prediction

The proteolytic digestive activity and growth during ontogeny of Parachromis dovii larvae (Pisces: Cichlidae) using two feeding protocols

Se evaluó la actividad proteolítica digestiva y el crecimiento de larvas de Parachromis dovii durante la ontogenia en un sistema de recirculación utilizando dos estrategias de alimentación durante un período de 28 días. Las larvas se criaron utilizando dos protocolos de alimentación (tres réplicas cada uno): (A) Nauplios de Artemia (en saciedad), alimentados con alimentación exógena [8 días después de la eclosión (DAH)] hasta los 15 DAH seguido de sustitución de nauplios por pienso formulado (20% día -1) hasta los 20 DAH y luego pienso formulado hasta los 28 DAH; (B) pienso formulado (100% de peso corporal al día) desde la alimentación exógena hasta los 28 días. Se midieron los niveles de proteasas digestivas ácidas (tipo pepsina) y alcalinas, así como el crecimiento y la supervivencia de las larvas a lo largo del período de alimentación. La supervivencia fue alta y similar entre tratamientos: 98,9 ± 0,0 para Artemia, 97,3 ± 0,0% para pienso formulado. La tasa de crecimiento específico para la longitud y el peso fue mayor en las larvas alimentadas con nauplios de Artemia que en las larvas criadas con alimento formulado: 3.4 ± 0.1 versus 1.8 ± 0.1% día-1 para la longitud corporal (P = 0.009) y 12.2 ± 0.1 versus 6.5 ± 0,3% día-1 para el peso corporal (P = 0,002). La actividad proteolítica ácida y alcalina se detectó, en ambos tratamientos, desde el inicio del experimento, a las 8 DAD. La actividad enzimática total (U larva-1) para las proteasas ácidas y alcalinas fue mayor en las larvas criadas con Artemia después de 12 DAD, mientras que la actividad enzimática específica fue similar para ambos tipos de enzimas en los dos tratamientos. Los resultados sugieren que las larvas de P. dovii eran capaces de digerir dietas formuladas desde el comienzo de la alimentación exógena y que podían criarse con piensos formulados. Sin embargo, el pienso formulado utilizado debe mejorarse nutricionalmente debido al escaso crecimiento obtenido en esta investigación.The proteolytic digestive activity and growth of Parachromis dovii larvae during the ontogeny were evaluated in a recirculation system using two feeding strategies during a 28-day period. Larvae were reared using two feeding protocols (three replicates each): (A) Artemia nauplii (at satiation), fed from exogenous feeding [8 days after hatching (DAH)] until 15 DAH followed by nauplii substitution by formulated feed (20 % day-1) until 20 DAH and then formulated feed until 28 DAH; (B) formulated feed (100 % BW daily) from exogenous feeding until 28 DAH. Levels of acid (pepsin type) and alkaline digestive proteases as well as growth and survival of larvae were measured along the feeding period. Survival was high and similar between treatments: 98.9 ± 0.0 for Artemia, 97.3 ± 0.0 % for formulated feed. The specific growth rate for length and weight was higher in larvae fed with Artemia nauplii than in larvae reared with formulated feed: 3.4 ± 0.1 versus 1.8 ± 0.1 % day-1 for body length (P = 0.009) and 12.2 ± 0.1 versus 6.5 ± 0.3 % day-1 for body weight (P = 0.002). The acid and alkaline proteolytic activity was detected, in both treatments, from the beginning of the experiment, at 8 DAH. The total enzymatic activity (U larva-1) for acid and alkaline proteases was higher in larvae reared with Artemia after 12 DAH, whereas the specific enzymatic activity was similar for both enzyme types in the two treatments. The results suggest that P. dovii larvae were capable to digest formulated diets from the beginning of exogenous feeding and that they could be reared with formulated feeds. However, the formulated feed used should be nutritionally improved because of the poor growth obtained in this research.Universidad Nacional, Costa RicaEscuela de Ciencias Biológica

Family Characteristics and Children’s Receipt of Autism Services in Low-Resourced Families

OBJECTIVES: Parents of children with autism spectrum disorder (ASD) face competing demands when caring for their child and fulfilling family commitments. It remains unknown whether family obligations and parental stress might decrease the use of intervention services for young children with ASD. METHODS: The current study is a secondary analysis of baseline date from a published randomized control trial with 147 low-resourced caregiver-child dyads. Demographic information, data on service use, maternal employment, parent’s perception of their child’s development, and parental stress were collected for primary caregivers of 2- to 5-year-old children with ASD from 5 sites. Multiple logistic regressions of accessing any intervention services or more than 1 services on familial characteristics were performed, controlling for demographic and contextual variables. RESULTS: Twenty-five percent of children were receiving no intervention service; 26% were receiving 1 service; and 49% were receiving 2 or more services. Perceived developmental delay and not having a sibling in the home were associated with higher odds of receiving intervention services. Children were more likely to receive more than 1 service if their parents had at least a college education and low levels of stress. CONCLUSIONS: Factors including perceived developmental level, parental stress, and caring for siblings may play a role in accessing services for children with ASD. Results reveal that competing family needs may be barriers to service use. Mothers of children with ASD with multiple children in the home, low levels of education, and high levels of stress may need additional supports or alternative service delivery models. </jats:sec

The road to Ithaca: a mentee’s and mentor’s journey

In this article a teacher/researcher and an academic mentor explore the potency, possibilities and tensions of the mentoring relationship from personal perspectives. The concept of mentoring as described in this article uses the model of mentor/mentee relationship as portrayed in Homer's epic narrative the Odyssey. In the examination of the experience of the mentoring process, as it was interpreted and implemented by Genie Gabel-Dunk and Anna Craft, significant elements emerge as tools for professional development: Being a Teacher to a Teacher; Being a Role Model; Being a Counsellor; Being a Facilitator; Being a Supportive Protector; and Being a Guide. The concept of mentorship is critical to quality education in that it fosters the creativity, professional development and growth of individuals and is a facilitator in the passing on of skills and professional standards. The authors believe that if as educators we value individuality, then we must work diligently to preserve the concept and practice of mentorship within the current context of the economic rationalisation of teaching resources

Ontogenia del Sistema Digestivo del Guapote Lagunero Parachromis dovii durante el Periodo Larval y Selección de Ingredientes para su Alimentación

Avances En Nutrición Acuicola. Cruz-Suárez, L.E., Ricque-Marie, D., Tapia-Salazar, M., Nieto-López, M.G., Villarreal-Cavazos, D. A., Gamboa-Delgado, J., Alvarez-González, C. (Eds), Contribuciones Recientes en Alimentación y Nutrición Acuícola, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, México. 320-355El guapote lagunero, Parachromis dovii, es un cíclido nativo de Costa Rica muy apreciado por su tamaño y calidad de su carne. Esta especie posee la ventaja de aceptar el alimento formulado desde el inicio de la alimentación exógena; sin embargo, su uso exclusivo produce un crecimiento muy lento. Debido a lo anterior, surgió la necesidad de investigar la ontogenia del sistema digestivo y sus enzimas y la evaluación in vitro de ingredientes dietarios; con el fin de generar información que permita formular alimentos inertes que mejoren el crecimiento larval. Se encontró que esta especie tiene un patrón de desarrollo similar al de otros cíclidos neotropicales, con la aparición muy precoz del estómago y las enzimas digestivas. Además, el crecimiento de las larvas alimentadas inicialmente con nauplios de Artemia fue de 12.25% PCd-1, mientras que en las alimentadas con una dieta formulada fue de 6.53% PCd-1. De las 7 harinas de origen vegetal evaluadas, las que produjeron la menor inhibición de las proteasas digestivas fueron la harina de trigo (59.08%) y puntilla de arroz (58.21%). Con respecto a los ensayos de digestibilidad alcalina in vitro, de las 6 harinas evaluadas, las que presentaron los valores más altos fueron la de carne y hueso (113.92%) y la de pescado (74.92%).The lagoon guapote, Parachromis dovii, is a cichlid native to Costa Rica highly appreciated for its size and quality of its meat. This species has the advantage of accepting formulated food from the beginning of exogenous feeding; However, its exclusive use produces very slow growth. Due to the above, the need arose to investigate the ontogeny of the digestive system and its enzymes and the in vitro evaluation of dietary ingredients; in order to generate information that allows formulating inert foods that improve larval growth. It was found that this species has a development pattern similar to that of other Neotropical cichlids, with the very early appearance of the stomach and digestive enzymes. Furthermore, the growth of larvae initially fed with Artemia nauplii was 12.25% PCd-1, while in those fed with a formulated diet it was 6.53% PCd-1. Of the 7 flours of plant origin evaluated, those that produced the least inhibition of digestive proteases were wheat flour (59.08%) and rice flour (58.21%). Regarding the in vitro alkaline digestibility tests, of the 6 flours evaluated, those that presented the highest values ​​were meat and bone flour (113.92%) and fish flour (74.92%).Universidad Nacional, Costa RicaUniversidad Autónoma de Nuevo León, MéxicoEscuela de Ciencias Biológica