2,700 research outputs found

    Sustainable Conversion of historic buildings in Cuba: the case of Santo Domingo de Atares Castle, Havana

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    Recently, in the Cuban capital of Havana, a number of fortresses were given away by the Army for refurbishment and conversion to public functions. In the last two decades, there have been examples of refurbishment and conversions of fortifications in museums, some of them with dire consequences for the collections and the structures. In this type of structure every architectonical element has historic value and very few interventions are allowed. However, the accommodation of modern functions and the preservation of the structure heavily rely upon the balance between various environmental parameters of the interior spaces. This study explores the challenges and opportunities of an environmentally driven conservation approach to the refurbishment of one of Havana’s most iconic XVIII century’s defensive structures, Santo Domingo of Atares Castle. The paper illustrates the development of an architectural proposal for the conversion of the castle into a museum and associated energy and environmental strategies. The museum function is particularly demanding due to the rigorous standards for the preservation of the collections, generally accomplished by mechanical equipment. Recently, however, there has been a major concern in the conservation scene about energy consumption and sustainable practices in this type of buildings. Therefore, the work identifyies the characteristics of the existing climatic and environmental conditions affecting the interior spaces of the thermally heavyweight fortress. This has led to an analysis of the requirements of the collection in a hot-humid climate in conjunction with the parameters for human comfort, in order to identify to what extent the original conditions can be passively modified to adapt the building to the conversion. Finally, with the help of computational dynamic simulations, passive strategies and zoning options were tested for the achievement of suitable interior environmental conditions and subsequent energy savings

    Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy

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    Spin-polarized low-energy electron microscopy was used to image a magnetite crystal with (100) surface orientation. Sets of spin-dependent images of magnetic domain patterns observed in this surface were used to map the direction of the magnetization vector with high spatial and angular resolution. We find that domains are magnetized along the surface [110] directions, and domain wall structures include 90{\deg} and 180{\deg} walls. A type of unusually curved domain walls are interpreted as N\'eel-capped surface terminations of 180{\deg} Bloch walls.Comment: 17 pages, 4 figures. Presented at the LEEM-PEEM 8 conferenc

    Analytical and Experimental Investigation of a Scroll Compressor Lubrication System

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    Theory and simulation of the dynamics, deformation, and breakup of a chain of superparamagnetic beads under a rotating magnetic field

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    In this work, an analytical model for the behavior of superparamagnetic chains under the effect of a rotating magnetic field is presented. It is postulated that the relevant mechanisms for describing the shape and breakup of the chains into smaller fragments are the induced dipole-dipole magnetic force on the external beads, their translational and rotational drag forces, and the tangential lubrication between particles. Under this assumption, the characteristic S-shape of the chain can be qualitatively understood. Furthermore, based on a straight chain approximation, a novel analytical expression for the critical frequency for the chain breakup is obtained. In order to validate the model, the analytical expressions are compared with full three-dimensional smoothed particle hydrodynamics simulations of magnetic beads showing excellent agreement. Comparison with previous theoretical results and experimental data is also reported

    Determination of the cosmic-ray-induced neutron flux and ambient dose equivalent at flight altitude

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    Journal of Physics: Conference Series, Volumen 630There is interest in modeling the atmosphere in the South Atlantic Magnetic Anomaly in order to obtain information about the cosmic-ray induced neutron spectrum and angular distribution as functions of altitude. In this work we use the Monte Carlo codes MCNPX and Geant4 to determine the cosmic-ray-induced neutron flux in the atmosphere produced by the cosmic ray protons incident on the top of the atmosphere and to estimate the ambient dose equivalent rate as function of altitude. The results present a reasonable conformity to other codes (QARM and EXPACS) based on other parameterizations

    Anion transport and supramolecular medicinal chemistry

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    New approaches to the transmembrane transport of anions are discussed in this review. Advances in the design of small molecule anion carriers are reviewed in addition to advances in the design of synthetic anion channels. The application of anion transporters to the potential future treatment of disease is discussed in the context of recent findings on the selectivity of anion transporters.University of Sydney and the Australian Research Council (DP170100118) for funding. JTD thanks the Office of Basic Energy Sciences, U.S. Department of Energy (DE-FG02-98ER14888) for funding. RQ thanks Consejerı´a de Educacio´n de la Junta de Castilla y Leo´n (BU340U13 and BU092U16) and La Marato´ de TV3 Foundation (20132730

    Hydrogen-induced reversible spin-reorientation transition and magnetic stripe domain phase in bilayer Co on Ru(0001)

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    Imaging the change in the magnetization vector in real time by spin-polarized low-energy electron microscopy, we observed a hydrogen-induced, reversible spin-reorientation transition in a cobalt bilayer on Ru(0001). Initially, hydrogen sorption reduces the size of out-of-plane magnetic domains and leads to the formation of a magnetic stripe domain pattern, which can be understood as a consequence of reducing the out-of-plane magnetic anisotropy. Further hydrogen sorption induces a transition to an in-plane easy-axis. Desorbing the hydrogen by heating the film to 400 K recovers the original out-of-plane magnetization. By means of ab-initio calculations we determine that the origin of the transition is the local effect of the hybridization of the hydrogen orbital and the orbitals of the Co atoms bonded to the absorbed hydrogen.Comment: 5 figure

    Autoimmune rheumatic diseases : An update on the role of atherogenic electronegative ldl and potential therapeutic strategies

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    Altres ajuts: Vascular and Medicinal Research Fund, Texas Heart Institute (#765-64050), Houston, TX, USA; Ministry of Science and Technology (Taiwana grant MOST 107-2314-B-039-053-MY3); Ministerio de Sanidad, Spain (co-financed by Fondo Europeo de Desarrollo Regional (FEDER)).Atherosclerosis has been linked with an increased risk of atherosclerotic cardiovascular disease (ASCVD). Autoimmune rheumatic diseases (AIRDs) are associated with accelerated atherosclerosis and ASCVD. However, the mechanisms underlying the high ASCVD burden in patients with AIRDs cannot be explained only by conventional risk factors despite disease-specific factors and chronic inflammation. Nevertheless, the normal levels of plasma low-density lipoprotein (LDL) cholesterol observed in most patients with AIRDs do not exclude the possibility of increased LDL atherogenicity. By using anion-exchange chromatography, human LDL can be divided into five increasingly electronegative subfractions, L1 to L5, or into electropositive and electronegative counterparts, LDL (+) and LDL (−). Electronegative L5 and LDL (−) have similar chemical composi-tions and can induce adverse inflammatory reactions in vascular cells. Notably, the percentage of L5 or LDL (−) in total LDL is increased in normolipidemic patients with AIRDs. Electronegative L5 and LDL (−) are not recognized by the normal LDL receptor but instead signal through the lectin-like oxidized LDL receptor 1 (LOX-1) to activate inflammasomes involving interleukin 1β (IL-1β). Here, we describe the detailed mechanisms of AIRD-related ASCVD mediated by L5 or LDL (−) and discuss the potential targeting of LOX-1 or IL-1β signaling as new therapeutic modalities for these diseases
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