720 research outputs found

    Low-Tip-Speed High-Torque Proprotor Noise Approximation for Design Cycle Analysis

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    Noise reduction in aviation would enable urban missions that cannot be own with current generation helicopters because of their noisiness. This goal can be achieved by using electric motors as they are quieter and can produce higher torque at lower RPMs. Therefore, a proprotor system can be designed to exploit this characteristic potentially abating noise levels. This research performed noise approximations included with rotor aerodynamics for a single, electric-driven, hovering proprotor by creating a code meant to be used in design cycle analysis. The approximation was based on geometry by using the blade element momentum theory, and calculating the pressure distribution along the blade surface using Drela\u27s Xfoil (2001). The noise approximation, performed using Brentner\u27s PSU-WOPWOPv3 (2017), was validated with known data obtained from previous published experimental results. These were within acceptable range of error, demonstrating the feasibility of the tool to be used in a design environment. Two rotors were analyzed, concluding that a custom designed proprotor for eVTOL applications is quieter than conventional rotor

    “Education Network” a new way to teach Chemistry

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    The complexity of chemistry has implications for the teaching of chemistry. That chemistry is a very complex subject. The majority of the students at University think that chemistry is a difficult discipline and they have difficulty in understanding the concepts. Moreover, students' interest in chemistry decreases the first year at university. The reason for this decrease might be that the contents of chemistry laboratory classes are boring, out of date and lacking of dynamism that students experience through visual media tools. For these reasons, new programs and methodologies should be developed. Those are based on making chemistry relevant through problem solving and collaborative learning hold promise for reforming chemistry education. It is about an education according to circumstances, which is adapted to context and virtual behaviour of people. It's time to CRUSH boredom by transforming your classroom into an Escape Room adventure. School-based escape games are a great teaching tool. The students while playing, learn. The most important point is that they won’t realize they’re doing both at the same time. In this work, an educational gamification experience based on the escape room concept was developed. The first (Do It Yourself) DIY Escape Room was built the year before at Mechanical Engineer Degree started, that took more than three weeks of work. It was presented to other professors to the same subject at different degrees. That DIY Escape Room was modified and adapted to each group. Each professor changed the clues, problems and so on in order to orientate the topic as much as possible to their students.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Multiscale understanding of tricalcium silicate hydration reactions

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    Tricalcium silicate, the main constituent of Portland cement, hydrates to produce crystalline calcium hydroxide and calcium-silicate-hydrates (C-S-H) nanocrystalline gel. This hydration reaction is poorly understood at the nanoscale. The understanding of atomic arrangement in nanocrystalline phases is intrinsically complicated and this challenge is exacerbated by the presence of additional crystalline phase(s). Here, we use calorimetry and synchrotron X-ray powder diffraction to quantitatively follow tricalcium silicate hydration process: i) its dissolution, ii) portlandite crystallization and iii) C-S-H gel precipitation. Chiefly, synchrotron pair distribution function (PDF) allows to identify a defective clinotobermorite, Ca11Si9O28(OH)2.8.5H2O, as the nanocrystalline component of C-S-H. Furthermore, PDF analysis also indicates that C-S-H gel contains monolayer calcium hydroxide which is stretched as recently predicted by first principles calculations. These outcomes, plus additional laboratory characterization, yielded a multiscale picture for C-S-H nanocomposite gel which explains the observed densities and Ca/Si atomic ratios at the nano- and meso- scales.This work has been supported by Spanish MINECO through BIA2014-57658-C2-2-R, which is co-funded by FEDER, BIA2014-57658-C2-1-R and I3 (IEDI-2016-0079) grants. We also thank CELLS-ALBA (Barcelona, Spain) for providing synchrotron beam time at BL04-MSPD beamline

    Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Technique sensitivity analysis

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    A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the Polar Operational Environmental Satellites (POES) spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conjunction events with the Van Allen Probes. These amplitudes are calculated with different input models of the plasma density, wave frequency spectrum, and electron energy spectrum, and the results are compared to the wave observations from the twin Van Allen Probes. Only one parameter is varied at a time in order to isolate its effect on the output, while the two other inputs are set to the values observed by the Van Allen Probes. The results show that the predicted hiss amplitudes are most sensitive to the adopted frequency spectrum, followed by the plasma density, but they are not very sensitive to the electron energy spectrum. Moreover, the standard Gaussian representation of the wave frequency spectrum (centered at 550 Hz) peaks at frequencies that are much higher than those observed in individual cases as well as in statistical wave distributions, which produces large overestimates of the hiss wave amplitude. For this reason, a realistic statistical model of the wave frequency spectrum should be used in the POES technique to infer the plasmaspheric hiss wave intensity rather than a standard Gaussian distribution, since the former better reproduces the observed plasmaspheric hiss wave amplitudes

    Slugs control methods (deroceras sp. mĂŒller) in lettuce and broccoli crops

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    At the Botana experimental farm of Universidad de Narino, the effect of different management practices of slugs was evaluated, using a randomized block design with five treatments (beer traps, milk traps, sisal bags, metaldehyde, and a control) and six repetitions. The evaluated variables were: captured individuals, affected plants and damage index that were estimated by analysis of variance and Tukey comparison tests. The results show highly significant differences between treatments in different phenological crops stages, the most effective were the metaldehyde and the beer trap with a caught individual number of 89 for lettuce and 126 for broccoli, being the treatments with lower percentages of affected plants. The damage index was evaluated based on percentages and proposed scales to observed crops damage, considering that the treatments described above stood out with mild damage index. This allows involved the beer treatment in an integrated management program for slugs as an alternative for reducing the pest population

    ANALYSIS OF BUILDING MATERIALS BY SYNCHROTRON X-RAY IMAGING

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    Building materials have complex hierarchical microstructures. The largest components are coarse aggregates with dimensions larger than a few centimetres and the smallest ones are the calcium silicate hydrate (C-S-H) gel nanoparticles with sizes smaller than 5 nm. To fully understand the main properties of cement binders and optimize their performances, a sound description of their spatially-resolved contents is compulsory. Furthermore, cement manufacturing is responsible for about 7% of the anthropogenic CO2 emissions and hence, to decrease the CO2 footprint, in a sustainable and cost-effective way, is a top priority. To gain a deeper insight into the microstructures of building materials, synchrotron X-ray ptychographic nanotomography and absorption-based microtomography have been employed. Here we will present three examples of our approach blending quantitative powder diffraction with synchrotron X-ray imaging. Firstly, we will show our comparative work on belite and Portland cement pastes cured at varying temperatures [1]. Synchrotron tomographic data taken at TOMCAT allowed understanding the different hydrating behaviour of both cements. Secondly, ptychographic nanotomographic data taken at cSAXS showed the hydration of CaAl2O4 with curing temperature [2]. Ptychographic data have permitted to characterise the conversion of the aluminate hydrates which is key for durability. The very good contrast in the electron density tomograms will be discussed as well as the porosity induced after the conversion reactions. Finally, we will report our work on Portland cements [3]. The densities and spatial distribution of calcium silicate hydrate (C-S-H) gel and amorphous iron-siliceous hydrogarnet components will be described.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂ­a Tech. BIA2017-82391-R UMA18-FEDERJA-09

    Resultados de urocultivos en adultos realizados por el laboratorio de microbiología del Hospital de Clínicas - San Lorenzo de enero del 2015 a agosto de 2016 y métodos de estudio de las infecciones urinarias disponibles en la institución

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    IntroducciĂłn: Los objetivos de este trabajo son: presentar los mĂ©todos de estudio de las infecciones urinarias actualmente disponibles en el Laboratorio de MicrobiologĂ­a del Hospital de ClĂ­nicas y mostrar los datos de los urocultivos evaluados en forma retrospectiva. Materiales y MĂ©todos: Para estudiar los mĂ©todos de estudio de los urocultivos disponibles en el Laboratorio hemos recurrido al archivo del Laboratorio cuyos datos fueron consecutivamente cargados en una planilla de procesamiento de datos Excel de Microsoft Office Âź. Los resultados de los urocultivos fueron evaluados de enero de 2015 a agosto de 2016, en forma retrospectiva, observacional, en corte transverso, de los adultos de ambos sexos. Las muestras para urocultivo son recibidas y procesadas en el laboratorio, siguiendo pasos preestablecidos. Resultados: El microorganismo preponderante de los urocultivos fue Escherichia coli (60% de las mujeres y 32% de los varones) seguido por Klebsiella pneumoniae (19% de los varones, 14% de las mujeres). Otros microorganismos aislados fueron Candida sp., Enterococcus faecalis, Enterobacter cloacae, Pseudomona aeruginosa, Proteus mirabilis, Staphylococcus aureus, Acinetobacter baumanii. La resistencia de Escherichia Coli a nitrofurantoĂ­na fue del 6% en los varones y 1% en las mujeres. La resistencia de E.Coli a meropenen fue tambiĂ©n escasa. En cuanto a Klebsiella pneumoniae en las mujeres, la resistencia fue del 3%. En los hombres, los antibiĂłticos testados para Klebsiella pneumoniae mostraron una resistencia superior al 30%, con excepciĂłn del meropenem. UropatĂłgenos productores de betalactamas de espectro extentido (BLEE) y de carbapenemasas fueron detectados en el presente estudio. DiscusiĂłn: La toma de la orina para el urocultivo se efectĂșa siguiendo pautas claras, emanadas del laboratorio. Con la utilizaciĂłn de medios actualmente disponibles en el laboratorio, es posible tipificar el gĂ©nero y la especie tanto de bacterias Gram negativas y positivas como de hongos. ConclusiĂłn: La estructura del Laboratorio de MicrobiologĂ­a ha tenido avances que permiten la identificaciĂłn precisa de los gĂ©rmenes de los urocultivos, asĂ­ como la prevalencia y la resistencia que presentan a ciertos antibiĂłticos. Estos aportes son particularmente Ăștiles para los casos de Escherichia coli y Klebsiella pneumoniae debido a su alta prevalencia. TambiĂ©n fue factible constatar la emergencia de gĂ©rmenes productores de betalactamasas de espectro extendido (BLEE) y carbapenemasas

    Quality of Work Life and Mental Health in Primary Care Physicians

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    AbstractThe aim of this study was to find the relationship between the perception of Quality of Work Life (QWL) and the mental health of primary care physicians of a public health institution in Guadalajara, Mexico. The study was analytical and was carried out with a universe of 818 doctors from 92 health units and the probability sample of 154 people. In all of them, CVT-GOHISALO and Goldberg GHQ-28 questionnaires were applied in order to measure their perception of QWL and the risk of mental illness respectively. Both instruments were selected because of their high reliability. We measured the satisfaction of the people interviewed for each one of the seven dimensions of CVT-GOHISALO and related to the points assigned to GHQ-28 case or not to consider the case of mental illness. The percentages of dissatisfaction with the QWL were greater than 12% in all dimensions of the instrument, being the highest value of 20.5% dissatisfaction for the job satisfaction dimension. In the classification of the case or not according to the GHQ-28, 22% were considered cases and 78% non-cases. We sought correspondence of satisfaction with the QWL by dimensions and non-case of Goldberg's, as well as dissatisfaction with the QWL and Goldberg's case, finding a clear link between being satisfied and having mental health. All dimensions have a correspondence that goes from 79.7% to 82.3% between satisfaction and non-case, being in all the statistical significance value less than 0.05 For primary care physicians in the studied institution, there is a clear relationship between being satisfied with the QWL and present less risk of mental illness. It is alarming that the medical staff presents high rates of dissatisfaction with the QWL and risk of mental illness. It is necessary to provide preventive programs among health care workers in order to improve their QWL and mental health

    In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction

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    Eco-friendly belite calcium sulfoaluminate (BCSA) cement hydration behavior is not yet well understood. Here,we report an in-situ synchrotron X-ray powder diffraction study for the first hours of hydration of BCSA cements. Rietveld quantitative phase analysis has been used to establish the degree of reaction (α). The hydration of a mixture of ye'elimite and gypsum revealed that ettringite formation (α ~70% at 50 h) is limited by ye'elimite dissolution. Two laboratory-prepared BCSA cements were also studied: non-active-BCSA and active-BCSA cements, with ÎČ- and αâ€ČH-belite as main phases, respectively. Ye'elimite, in the non-active-BCSA system, dissolves at higher pace (α ~25% at 1 h) than in the active-BCSA one (α ~10% at 1 h),with differences in the crystallization of ettringite (α ~30% and α ~5%, respectively). This behavior has strongly affected subsequent belite and ferrite reactivities, yielding stratlingite and other layered phases in non-active-BCSA. The dissolution and crystallization processes are reported and discussed in detail.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂ­a Tech

    X-ray near-field ptychographic nanoimaging of cement pastes

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    The hydration processes of Portland cements (PC) and blends are complicated as there are many components with great heterogeneity at different length scales. Thus, 3D nanoimaging techniques with high spatial resolution and scanning large fields of view are needed. Here, synchrotron X-ray near-field ptychographic tomography is used to investigate four pastes within 0.2 mm thick capillaries: PC with CaCl2, PC hydration enhanced by C-S-H nucleation seeding, PC partly substituted with metakaolin, and PC partly substituted with metakaolin and limestone. Data analysis emphasis has been placed on the characterization of amorphous components: (i) C-S-H and C-A-S-H gels; (ii) iron aluminium siliceous hydrogarnets; (iii) metakaolin; and (iv) aluminium carboaluminate, AFm-like. Synchrotron ptychotomography yields electron density and absorption coefficient tomograms and the resulting bivariate plots are instrumental for characterising these amorphous components. The attained spatial resolution, ∌220 nm, with very good contrast allowed us to determine nanofeatures including mass densities and spatial distributions of amorphous components. For instance, the C-S-H gel mass density differences between the two type of accelerated pastes are detailed.Funding for open access charge: Universidad de MĂĄlaga / CBUA. This research has been partly supported by the research grant PID2019-104378RJ-I00 which is co-funded by ERDF. We acknowledge the Paul Scherrer Institut, Villigen, Switzerland for provision of synchrotron radiation beamtime at cSAXS beamline of the SLS, proposal number 20210147
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