VHCF Response of H13 Steels Produced with Different Manufacturing Processes

Experimental results have recently shown that failures at stress amplitude below the conventional fatigue limit and at Very High Cycle Fatigue (VHCF) are possible. In case of high-strength steels, VHCF failures generally originate from defects/inclusions present within the material and, consequently, the defect population properties (size and quantity) significantly affect the VHCF response of high-strength steels. Different refinement processes are commonly adopted in order to improve steel cleanliness: among the other, the ElectroSlag Remelting (ESR) process allows to obtain very clean high-strength steels, thus possibly inducing a significant enhancement of the VHCF response. The present paper aims at investigating the actual effect of the ESR process on the VHCF behavior of an AISI H13 steel. Fully reversed ultrasonic tension-compression tests are carried out on hourglass specimens manufactured with and without the ESR process. The estimated P-S-N curves highlight the positive effects of the ESR process on the VHCF response of the investigated H13 steel

Investigación – acción en el aula de ciencias. Evolución del conocimiento infantil sobre células

La investigación tuvo como objetivo analizar la evolución de las representaciones mentales de los alumnos de séptimo grado de escuela primaria sobre el contenido célula. Se adoptó el método de investigación - acción sobre la propia praxis, según el modelo de Elliot (1991) y Stenhouse (1993). En la estrategia metodológica para la enseñanza del contenido se planificaron actividades que incluyeron, entre otras, la utilización de un libro de texto de nivel secundario. Los resultados muestran cuatro momentos en la evolución de las representaciones mentales de los alumnos: al inicio se representó a la célula como objeto plano, luego la reconocieron con un cuerpo tridimensional; en el tercer momento, relacionaron estructura – función y por último, integraron células – órganos – sistemas – ser vivo; esta secuencia evidencia una mayor complejización del conocimiento infantil

Impacto do manejo da palhada sobre sua decomposição em área cultivada com cana-de-açúcar no município de Guaíra-SP.

O presente trabalho tem como objetivo acompanhar a dinâmica e as taxas finais de decomposição de diferentes quantidades de palhada de cana-de-açúcar, sob condições de Guaíra-SP. Para isto foi conduzido um experimento em área comercial de cana-de-açúcar, variedade RB 86-7515 na safra 2012-2013, em primeira soca. Como tratamentos foram testados os níveis T(25%), T(50%), T(75%) e T(100%), correspondentes a 4,7; 9,4; 14,1 e 18,8 t ha-1, distribuídos em blocos ao acaso, em quatro repetições. Para o acompanhamento da decomposição avaliou-se a quantidade (t ha-1) e a taxa (%) da massa seca remanescente no solo em coletas realizadas aos: 0, 63, 125, 189, 230, 285 e 328 dias após a instalação; utilizando-se de sacos de serapilheira ("litter bags") nas dimensões 0,50 x 0,75 com 15 mm de abertura. O tratamento estatístico foi feito por análise de variância, regressão e equações de cinética para ajuste do comportamento da decomposição da palhada. Os resultados permitiram concluir que os níveis de palhada alteram a dinâmica da decomposição deste resíduo, sendo o coeficiente de decomposição (K) significativamente superior para os níveis 100% e 75%. As maiores taxas de decomposição ocorrem até os 189 dias do ciclo, sendo mais lenta a partir deste ponto; com média de 41% de massa remanescente aos 328 dias, independente do nível de palhada. Abstract: The project aims to evaluate decomposition dynamic of different inputs of sugarcane straw under conditions of Guaira-SP. The experiment was conducted in a first ratoon commercial area of sugarcane, variety RB 86-7515, in 2012-2013. The treatments were tested by the levels of (25%), T(50%), T(75%) and T(100%), corresponding to 4,7; 9,4; 14,1 and 18,8 t ha -1 , arranged in a randomized block design, with four replications. The development of decomposition was evaluated using the quantity (kg ha -1 ) and the rate (%) remaining of dry matter, evaluated at: 0, 63, 125, 189, 230, 285, 328 days after installation by the use of litter bags (0,75m x 0,50m x 0,015m). The data were analyzed by variance, regression and kinetic equations for adjust the residues decomposition behavior. The results show that the levels of straw can modify the dynamics of this residue decomposition; the decomposition coefficient (K) was significantly higher for the levels of 100% and 75%. The highest rates of decomposition occur until 189 days of the cycle, being slower from this point; averaging 41% to the 328 days (harvest), regardless of the level of straw

Avaliação da qualidade dos produtos, infraestrutura e serviços em feiras e mercados orgânicos localizados em Brasília ? DF.

É notório que o interesse em formas de produção consideradas alternativas se intensificou, visando atender à crescente demanda pelos produtos saudáveis e sustentáveis. O presente estudo tem como eixo principal as feiras locais e um mercado de produtos orgânicos. O objetivo foi avaliar a percepção dos feirantes e produtores sobre a qualidade dos produtos, a infraestrutura e os serviços prestados por estes estabelecimentos em Brasília-DF. Para obtenção dos dados foram realizadas entrevistas com feirantes guiadas pelo uso de questionário. Verificou-se que a maioria dos feirantes tem renda exclusivamente da venda da produção orgânica. Quanto à qualidade do produto, esses profissionais julgam importante a higienização e cuidados para manter a boa aparência do alimento. Atenção e cordialidade foram consideradas atributos muito importantes, na percepção dos feirantes, na relação dos mesmos com a clientela para manter a fidelidade. Abstract: It?s well known that the interest in alternative forms of production have intensified, in order to attend the growing market demand for healthier and sustainable products. As the main axis of this study, local fairs and organic market were considered. The objective was to evaluate those fair workers and producer?s perception towards the product?s quality, the local infrastructure and the establishment?s services. Data collection was performed by interviews guided by a questionnaire application. The results show that the majority of workers have incomes exclusively from the sale of organic production. Regarding product?s quality, these professionals consider as important the product?s sanitization and the care to maintain the product?s good appearance. Attention and cordiality were considered very important for fair workers in their relationship with consumers to maintain fidelity

Effects of the Environment on the Properties of Seyfert Galaxies

We identify 175 Seyfert galaxies from the Southern Sky Redshift Survey - SSRS2. We use the entire SSRS2 catalog to investigate the correlation between the presence of AGN with host environment. The AGN phenomenon is more strongly correlated with the internal host properties, than with the external environment. In particular, we find that Seyferts reside in more luminous galaxies, and are twice as frequent in barred galaxies and systems showing sign of advanced merger condition, when compared to a control sample.Comment: 4 pages, 3 figs, 1 tables, to appear in the proceedings of "The Interplay among Black Holes, Stars and ISM in Galactic Nuclei", IAU 222, eds. T. Storchi Bergmann, L.C. Ho, and H.R. Schmit

VHCF response of heat-treated SLM Ti6Al4V Gaussian specimens with large loaded volume

Abstract Among the materials used for the production of components through Additive Manufacturing (AM) processes, the Selective-Laser-Melting (SLM) Ti6Al4V alloy is widely employed in aerospace applications for its high specific strength and in biomedical applications for its good biocompatibility. Actual structural applications are generally limited to static loading conditions where the large defects originating during the SLM process do not play a significant role for the static failure. On the contrary, the same defects strongly affect the fatigue response of the parts since they act as crack initiation sites that rapidly lead to fatigue failure. In the literature, a lot of research has been carried out to investigate the quasi-static and the High-Cycle Fatigue properties of the SLM Ti6Al4V alloy but there are still few studies on its Very-High-Cycle Fatigue (VHCF) response. In the paper, the VHCF response of Ti6Al4V specimens, which are vertically orientated during the SLM building and then subjected to a conventional heat treatment (2 hours heating in vacuum at 850°C), is experimentally assessed. Ultrasonic VHCF tests are carried out on Gaussian specimens with a large risk-volume (2300 mm3). Fracture surfaces are investigated for revealing the defect originating the fatigue failure. The Stress Intensity Factor Threshold associated to the experimental failures is finally estimated

Prevalence of foodborne pathogens in rural pigs and in derived cold pork meats - preliminary report

The rural breeding of one or two pigs and their domestic slaughtering is a significance reality in the Veneto Region, as a consequence of an ancient tradition still surviving in this countryside. In the eastern part of the Venice Province, about 2,500 rural pigs are bred and slaughtered ever year in the period between November and February. Many data are available on mdustnal breeding and processing, whereas very little is known about the prevalence of foodborne pathogens both in live ammals and in denved food, mainly sausage, salami and cold pork meats

Cerebral blood flow and cerebrovascular reactivity correlate with severity of motor symptoms in Parkinson’s disease

Background: Parkinson\u2019s disease (PD) is a progressive neurodegenerative disorder that is mainly characterized by movement dysfunction. Neurovascular unit (NVU) disruption has been proposed to be involved in the disease, but its role in PD neurodegenerative mechanisms is still unclear. The aim of this study was to investigate cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) within the regions belonging to the motor network, in patients with mild to moderate stages of PD. Methods: Twenty-eight PD patients (66.6 \ub1 8.6 years, 22 males, median [interquartile range, IQR] Hoehn & Yahr = 1.5 [1\u20131.9]) and 32 age- and sex-matched healthy controls (HCs) were scanned with arterial spin labeling (ASL) magnetic resonance imaging (MRI) for CBF assessment. ASL MRI was also acquired in hypercapnic conditions to induce vasodilation and subsequently allow for CVR measurement in a subgroup of 13 PD patients and 13 HCs. Median CBF and CVR were extracted from cortical and subcortical regions belonging to the motor network and compared between PD patients and HCs. In addition, the correlation between these parameters and the severity of PD motor symptoms [quantified with Unified Parkinson\u2019s Disease Rating Scale part III (UPDRS III)] was assessed. The false discovery rate (FDR) method was used to correct for multiple comparisons. Results: No significant differences in terms of CBF and CVR were found between PD patients and HCs. Positive significant correlations were observed between CBF and UPDRS III within the precentral gyrus, postcentral gyrus, supplementary motor area, striatum, pallidum, thalamus, red nucleus, and substantia nigra (pFDR < 0.05). Conversely, significant negative correlation between CVR and UPDRS III was found in the corpus striatum (pFDR < 0.05). Conclusion: CBF and CVR assessment provides information about NVU integrity in an indirect and noninvasive way. Our findings support the hypothesis of NVU involvement at the mild to moderate stages of PD, suggesting that CBF and CVR within the motor network might be used as either diagnostic or prognostic markers for PD