2,103 research outputs found

    High-Chromium (9-12Cr) Steels: Creep Enhancement by Conventional Thermomechanical Treatments

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    There is a worldwide need to develop materials for advanced power plants with steam temperatures of 700°C and above which have the capacity to achieve high efficiency and low CO2 emissions. This request involves the development of new grades of 9-12Cr heat-resistant steels, with a nanostructured martensite, mainly focusing on the long-term creep rupture strength of base metal and welded joints, creep-fatigue properties, and microstructure evolution during exposure at such elevated temperatures. The main shortcomings of actual 9-12Cr high-chromium steels are that the creep resistance is not enough to fulfill the engineering requirements at temperatures higher than 600°C and the material undergoes a cyclic softening. Creep strength at high temperature could be improved by a microstructural optimization through nano-precipitation, guided by computational thermodynamics, and thermomechanical control process optimization

    Cardiovascular risk and obesity

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    La obesidad es una enfermedad crónica de carácter multifactorial que ha alcanzado proporciones epidémicas a nivel global, representando una compleja condición médica con serias consecuencias sociales y psicológicas. El exceso de la adiposidad visceral se encuentra asociado con una plétora de disfunciones metabólicas (resistencia a la insulina, dislipidemia aterogénica, hipertensión arterial, disminución de la fibrinólisis, aumento del riesgo de trombosis, inflamación endotelial) que incrementan el riesgo de enfermedad cardiovascular. Las estrategias planteadas para su correcto abordaje terapéutico deben estar acorde con la gravedad del sobrepeso, la presencia de enfermedades crónicas coexistentes y las limitaciones funcionales de cada individuo.Obesity is a chronic multifactorial disease that has reached global epidemic proportions, representing a complex medical condition with serious social and psychological consequences. The excess of visceral adiposity is associated with a plethora of metabolic dysfunctions (insulin resistance, atherogenic dyslipidemia, hypertension, decreased fibrinolysis, increased risk of thrombosis, endothelial inflammation) that increase the risk of cardiovascular disease. The strategies proposed for the correct therapeutic approach must be in accordance with the severity of overweight, the presence of chronic coexisting diseases and the functional limitations of each individual

    Product shape change by internal stresses

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    The design of a product component may require complex processing steps such as metal forming followed by a thermal treatment. The thermal treatment may improve the functional performance of the material itself, but may result in rather unwanted changes in the shape of the product. Here it is shown that Finite Element modeling of the various processes can assist in the design of a robust and accurate production process. The modeling approach presented allows a coupling between various complex material models, in such a way that full cold forming and thermal treatment processes are calculated. This coupling of material models is key for the design and concerns the novelty of the proposed approach. Cold forming by deep drawing is calculated whereby planar anisotropy is implemented. The thermal hardening treatment consists of three contributions: creep, thermal expansion and phase transformation. All models are based on experimental data, acquired from tensile and dilatometer tests, and are implemented into the material model either directly or by a simple fit. It is shown that the effects of a complete forming and heat treatment of a cup could be successfully calculated. The predicted cup shape change was compared to experiments, and shows excellent agreement.This research was carried out under the project number T63.3.12480 in the framework of the research program of the Materials innovation institute M2i, Delft, the Netherlands; and has been part of Press Perfect project, RFSR-CT-2012-00021 funded by the Research Fund for Coal & Steel.Peer Reviewe

    A key role for stimulus-specific updating of the sensory cortices in the learning of stimulus-reward associations

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    Successful adaptive behavior requires the learning of associations between stimulus-specific choices and rewarding outcomes. Most research on the mechanisms underlying such processes has focused on subcortical reward-processing regions, in conjunction with frontal circuits. Given the extensive stimulus-specific coding in the sensory cortices, we hypothesized they would play a key role in the learning of stimulus-specific reward associations. We recorded electrical brain activity (EEG) during a learning-based, decision-making, gambling task where, on each trial, participants chose between a face and a house and then received feedback (gain or loss). Within each 20-trial set, either faces or houses were more likely to predict a gain. Results showed that early feedback processing (~200-1200ms) was independent of the choice made. In contrast, later feedback processing (~1400-1800ms) was stimulus-specific, reflected by decreased alpha power (reflecting increased cortical activity) over face-selective regions. For winning-versus-losing after a face choice, but not after a house choice. Finally, as the reward association was learned in a set, there was increasingly stronger attentional bias towards the more likely winning stimulus, reflected by increasing attentional-orienting-related brain activity and increasing likelihood of choosing that stimulus. These results delineate the processes underlying the updating of stimulus-reward associations during feedback-guided learning, which then guides future attentional allocation and decision making

    Do Students Value On-Campus Field-Based Education? A Case Study of Science Educational Initiatives in the Jock Marshall Reserve

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    Fieldwork, known for fostering more engaging and authentic learning experiences, is an established tradition in higher education which is changing; increasingly run on-campus for financial and logistical reasons and enhanced through education technologies to reflect industry practices. Here we examine student perceptions of on-campus fieldwork with the aim of understanding if on-campus fieldwork was valued and why, to be able to compare against literature on off-campus fieldwork. We explore student views on activities at the Jock Marshall Reserve, an on-campus nature reserve of Monash University, Australia using mixed-methods approach. An online survey targeted students undertaking four subjects across first to third year and received 116 responses. In alignment with off-campus fieldwork studies, we found that overwhelmingly respondents highly valued fieldwork with dominant reasons being; 1) developed skills relevant to ‘real-world’ science, 2) reinforced theoretical learning, and 3) was more engaging than traditional study, with some benefits to their wellbeing. The novel perceptions related to increased convenience and authenticity. Since a majority of respondents wished to undertake on-campus fieldwork more frequently, this study suggests that the inclusion of on-campus fieldwork should be considered within science curriculum in higher education

    Efectos del nivel de infestación de malezas y la densidad de siembra sobre dos cultivares del sorgo granifero (Sorghum bicolor)

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    Se analizó la respuesta de dos cultivares ACA 550 y MS 3 Morgan de sorgo granífero (Sorghum bicolor), sembrados en dos densidades (115.400 y 192.300 plantas/ha), frente a la competencia de malezas en dos niveles de infestación. A los 21 y 42 días de la emergencia del cultivo se calcularon índices de agresividad. Estos datos demostraron que el cv. ACA 550 fue más competitivo que el MS 3 Morgan, ello independientemente del nivel de infestación de malezas y de la densidad de siembra. Sin embargo, esa característica inicial de mayor competitividad del ev ACA 550 no se manifestó en términos de rendimiento de grano, donde las diferencias entre ambos híbridos resultaron no significativas (p = 0,05) y con una ligera tendencia a mayor producción por parte del cv. MS 3 Morgan. La competencia de malezas, principalmente gramíneas, provocó una pérdida de rendimiento de grano del 1,1 %, debida principalmente a la disminución del número de panojas y en menor medida al tamaño de las mismas. Sobre esa producción no tuvo efecto alguno la densidad de siembra. No pudo comprobarse la hipótesis de diferencias en las habilidades competitivas de los dos cultivares en la variable rendimiento de grano, ni aún en los dos niveles de infestación de malezas. Se asume que diferencias de comportamiento entre híbridos y densidades de siembra podrían ocurrir en niveles de infestación de malezas mucho menores a dos considerados en este experimento

    THE HIGH CADENCE TRANSIENT SURVEY (HITS). I. SURVEY DESIGN AND SUPERNOVA SHOCK BREAKOUT CONSTRAINTS

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    Indexación: Web of Science; Scopus.We present the first results of the High Cadence Transient Survey (HiTS), a survey for which the objective is to detect and follow-up optical transients with characteristic timescales from hours to days, especially the earliest hours of supernova (SN) explosions. HiTS uses the Dark Energy Camera and a custom pipeline for image subtraction, candidate filtering and candidate visualization, which runs in real-time to be able to react rapidly to the new transients. We discuss the survey design, the technical challenges associated with the real-time analysis of these large volumes of data and our first results. In our 2013, 2014, and 2015 campaigns, we detected more than 120 young SN candidates, but we did not find a clear signature from the short-lived SN shock breakouts (SBOs) originating after the core collapse of red supergiant stars, which was the initial science aim of this survey. Using the empirical distribution of limiting magnitudes from our observational campaigns, we measured the expected recovery fraction of randomly injected SN light curves, which included SBO optical peaks produced with models from Tominaga et al. (2011) and Nakar & Sari (2010). From this analysis, we cannot rule out the models from Tominaga et al. (2011) under any reasonable distributions of progenitor masses, but we can marginally rule out the brighter and longer-lived SBO models from Nakar & Sari (2010) under our best-guess distribution of progenitor masses. Finally, we highlight the implications of this work for future massive data sets produced by astronomical observatories, such as LSST.http://iopscience.iop.org/article/10.3847/0004-637X/832/2/155/meta;jsessionid=76BDFFFE378003616F6DBA56A9225673.c4.iopscience.cld.iop.or

    BatNet: a 6LoWPAN-based sensors and actuators network

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    Improving energy efficiency in buildings is one of the goals of the Smart City initiatives and a challenge for the European Union. This paper presents a 6LoWPAN wireless transducer network (BatNet) as part of an open energy management system. This network has been designed to operate in buildings, to collect environmental information (temperature, humidity, illumination and presence) and electrical consumption in real time (voltage, current and power factor). The system has been implemented and tested in the Energy Efficiency Research Facility at CeDInt-UPM

    Insights into the cell‐wall dynamics in grapevine berries during ripening and in response to biotic and abiotic stresses

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    The cell wall (CW) is the dynamic structure of a plant cell, acting as a barrier against biotic and abiotic stresses. In grape berries, the modifications of pulp and skin CW during softening ensure flexibility during cell expansion and determine the final berry texture. In addition, the CW of grape berry skin is of fundamental importance for winemaking, controlling secondary metabolite extractability. Grapevine varieties with contrasting CW characteristics generally respond differently to biotic and abiotic stresses. In the context of climate change, it is important to investigate the CW dynamics occurring upon different stresses, to define new adaptation strategies. This review summarizes the molecular mechanisms underlying CW modifications during grapevine berry fruit ripening, plant-pathogen interaction, or in response to environmental stresses, also considering the most recently published transcriptomic data. Furthermore, perspectives of new biotechnological approaches aiming at modifying the CW properties based on other crops’ examples are also presente
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