3,544 research outputs found

    Thermal performance and comfort condition analysis in a vernacular building with a glazed balcony

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    The increase in global environmental problems requires more environmentally efficient construction. Vernacular passive strategies can play an important role in helping reducing energy use and CO2 emissions related to buildings. This paper studies the use of glazed balconies in the North of Portugal as a strategy to capture solar gains and reduce heat losses. The purpose is understanding thermal performance and comfort conditions provided by this passive heating strategy. The methodology includes objective (short and long-term monitoring), to evaluate the different parameters affecting thermal comfort and air quality, and subjective assessments to assess occupants? perception regarding thermal sensation. The results show that the use of glazed balconies as a passive heating strategy in a climate with cold winters is viable. During the mid-seasons, the rooms with balcony have adequate comfort conditions. In the heating season, it is possible to achieve comfort conditions in sunny days while in the cooling season there is a risk of overheating. Regarding indoor air quality, carbon dioxide concentrations were low, but the average radon concentration measured was high when the building was unoccupied, rapidly decreasing to acceptable values, during occupation periods when a minimum ventilation rate was promoted. Occupants? actions were essential to improving building behavior.The authors would like to acknowledge the support granted by the FEDER funds through the Competitively and Internationalization Operational Programme (POCI) and by national funds through FCT (Foundation for Science and Technology) within the scope of the project with the reference POCI-01-0145-FEDER-029328, and of the Ph.D. grant with the reference PD/BD/113641/2015, that were fundamental for the development of this study

    Mechanical properties of Graphene Nanoribbons

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    Herein, we investigate the structural, electronic and mechanical properties of zigzag graphene nanoribbons upon the presence of stress applying Density Functional Theory within the GGA-PBE approximation. The uniaxial stress is applied along the periodic direction, allowing a unitary deformation in the range of +/- 0.02%. The mechanical properties show a linear-response within that range while the non-linear dependence is found for higher strain. The most relevant results indicate that Young's modulus is considerable higher than those determined for graphene and carbon nanotubes. The geometrical reconstruction of the C-C bonds at the edges hardness the nanostructure. Electronic structure features are not sensitive to strain in this linear elastic regime, being an additional promise for the using of carbon nanostructures in nano-electronic devices in the near future.Comment: 30 pages. J. Phys.: Condens. Matter (accepted

    Co-crystals of diflunisal and isomeric pyridinecarboxamides – a thermodynamics and crystal engineering contribution

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    Diflunisal is an anti-inflammatory, non-steroidal drug, class II of the Biopharmaceutical Classification System, which has recently been the subject of renewed interest due to its potential for use in the oral therapy of familial amyloid polyneuropathy. In this study, a thermodynamics based approach is used to investigate binary mixtures (diflunisal + picolinamide and diflunisal + isonicotinamide) in order to identify solid forms that are potentially useful to improve the biopharmaceutical performance of this active pharmaceutical ingredient. Special emphasis is placed on the research of co-crystals and on the influence of structural changes in the pyridinecarboxamide co-former molecules for co-crystal formation with diflunisal. The thermodynamics based methodology described by ter Horst et al. in 2010 indicates that the formation of co-crystals is thermodynamically feasible for both systems. The binary solid–liquid phase diagrams were built and allowed unequivocal identification of the formation of co-crystals of diflunisal with each of the two isomers and also their stoichiometry of 1 : 1, (diflunisal : co-former) in the case of pyridine-2-carboxamide (picolinamide) and (2 : 1) for pyridine-4-carboxamide (isonicotinamide). Two binary eutectic mixtures, potentially relevant for pharmaceutical application, were also identified. Infrared spectroscopy allowed the identification of the acid⋯N-pyridine heterosynthon in the three co-crystals formed by diflunisal with the isomeric pyridinecarboxamides. However, the results clearly differentiated pyridine-2-carboxamide from pyridine-3-carboxamide and pyridine-4-carboxamide, that share similar crystalline arrangements, at least with respect to the supramolecular synthons

    Surface superconductivity in multilayered rhombohedral graphene: Supercurrent

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    The supercurrent for the surface superconductivity of a flat-band multilayered rhombohedral graphene is calculated. Despite the absence of dispersion of the excitation spectrum, the supercurrent is finite. The critical current is proportional to the zero-temperature superconducting gap, i.e., to the superconducting critical temperature and to the size of the flat band in the momentum space

    Acoustically Levitated Whispering-Gallery Mode Microlasers

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    Acoustic levitation has become a crucial technique for contactless manipulation in several fields, particularly in biological applications. However, its application in the photonics field remains largely unexplored. In this study, we implement an affordable and innovative phased-array levitator that enables stable trapping in the air of micrometer dye-doped droplets, thereby enabling the creation of microlasers. For the first time, this paper presents a detailed performance of the levitated microlaser cavity, supported by theoretical analysis concerning the hybrid technology based on the combination of whispering-gallery modes and acoustic fields. The pressure field distribution inside the acoustic cavity is numerically solved and qualitatively matched with the schlieren deflectometry technique. The optical lasing features of the levitated microlasers are highly comparable with those devices based On-a-Chip registering maximum Q-factors of ~ 105, and minimum lasing thresholds ~ 150 nJ cm−2. The emission comb is explained as a sum of multiple individual-supported whispering-gallery modes. The use of novel touchless micrometric lasers, produced with an acoustic levitator brings new technological opportunities based on photonic-acoustic technological platforms

    Preliminary analysis of the genetic variability of two natural beds of the Scallop Euvola ziczac (Linnaeus, 1758) in Brazil

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    Euvola ziczac (formerly Pecten ziczac), a simultaneous hermaphroditic scallop was heavily fished in Brazil between 1972 and 1980. The production peaked in 1980 with 8,800 tons and was followed by the total collapse of the resource. In order to investigate the possible loss of genetic variability of the stock associated to overfishing and self-fertilization, the polymorphism of phosphoglucomutase (PGM) and glucose phosphate isomerase (GPI) was analyzed by electrophoresis of the adductor muscle of scallops from São Francisco (26° 20.583S; 48° 16.507W) and Bom Abrigo (25° 28.735S; 47° 37.621W) beds; the southern and northern extremes of the scallop fishing ground, respectively. Animals from São Francisco showed a strong deficiency of heterozygosity for GPI and PGM. In addition, PGM showed *exclusive alleles for each bed. Such results coupled with other information about the species suggested the following hypothesis: a) the stock was a metapopulation with at least two populations; b) some reproductive isolation might be occurring which might be influenced by conditions of larval transport and by the extremely low densities of scallops; c) presently, the stock seemed to be mostly maintained through self-fertilization; d) São Francisco could constitute a source-area, contributing with larvae and recruits to Bom Abrigo and other areas; e) both beds were suffering a genetic homogenization more evident in São Francisco. Such hypothesis needed to be investigated in order to furnish guidelines for future programs of recovery and management of the resource.info:eu-repo/semantics/publishedVersio

    Interlayer hopping properties of electrons in layered metals

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    A formalism is proposed to study the electron tunneling between extended states, based on the spin-boson Hamiltonian previously used in two-level systems. It is applied to analyze the out--of--plane tunneling in layered metals considering different models. By studying the effects of in--plane interactions on the interlayer tunneling of electrons near the Fermi level, we establish the relation between departure from Fermi liquid behavior driven by electron correlations inside the layer and the out of plane coherence. Response functions, directly comparable with experimental data are obtained

    The Newly Synthesized Pyrazole Derivative 5-(1-(3 Fluorophenyl)-1H-Pyrazol-4-yl)-2H-Tetrazole Reduces Blood Pressure of Spontaneously Hypertensive Rats via NO/cGMO Pathway

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    The search for new antihypertensive drugs has grown in recent years because of high rate of morbidity among hypertensive patients and several side effects that are associated with the first-line medications. The current study sought to investigate the antihypertensive effect of a newly synthesized pyrazole derivative known as 5-(1-(3 fluorophenyl)-1H-pyrazol-4-yl)-2H-tetrazole (LQFM-21). Spontaneously hypertensive rats (SHR) were used to evaluate the effect of LQFM-21 on mean arterial pressure (MAP), heart rate (HR), renal vascular conductance (RVC), arterial vascular conductance (AVC), baroreflex sensitivity (BRS) index, and vascular reactivity. Acute intravenous (iv) administration of LQFM-21 (0.05, 0.1, 0.2, and 0.4 mg kg-1) reduced MAP and HR, and increased RVC and AVC. Chronic oral administration of LQFM-21 (15 mg kg-1) for 15 days reduced MAP without altering BRS. The blockade of muscarinic receptors and nitric oxide synthase by intravenous infusion of atropine and L-NAME, respectively, attenuated cardiovascular effects of LQFM-21. In addition, ex vivo experiments showed that LQFM-21 induced an endothelium-dependent relaxation in isolated aortic rings from SHR. This effect was blocked by guanylyl cyclase inhibitor (ODQ) and L-NAME. These findings suggest the involvement of muscarinic receptor and NO/cGMP pathway in the antihypertensive and vasodilator effects of LQFM-21

    Characterization of the physical capacity in children of the Chilean national program of cystic fibrosis

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    Introduction: Cystic fibrosis (CF) is an inherited, progressive, multisystem disease. Better physical capacity may slow disease progression, thus improving prognosis and survival. The objective of this research was to evaluate the physical capacity of children admitted to the National CF Program of the Metropolitan Region, Chile. Patients and Method: A multicenter, cross-sectional study design was used. The inclusion criteria were children aged 6 to 12 years enrolled in the National CF Program; Tanner sexual maturity stage I, no respiratory exacerbations in the last 30 days, and no musculoskeletal pathologies. The maximum aerobic capacity was assessed through the peak oxygen uptake (VO2 peak) and determined with an incremental protocol in a magnetic cycle ergometer connected to an ergo-spirometer with which, at the same time, respiratory gases, oxygen consumption and carbon dioxide production values every 30 seconds, anaerobic threshold, and maximum workload were analyzed. The values of forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio, and forced expiratory flows between 25% and 75% of vital capacity were assessed through ergo-spirometry. At the beginning of the ergo-spirometry, arterial oxygen saturation, respiratory rate, heart rate, blood pressure, tidal volume and the perception of lower extremity fatigue and dyspnea were recorded using the modified Borg scale. The test lasted approximately 10 minutes. Results: The clinical records of 43 children collected from six health centers were reviewed. Out of these, 29 children met inclusion criteria, and 23 were recruited. Two children were unable to participate, reducing the final subject group to 21 (13 males, 8 females). The mean age was 8.8 ± 2 years; weight 30.5 ± 10.9 kg; height 1.32 ± 0.11 m; and body mass index 17.1 ± 3.5 (z-score 0.01 ± 1.34). More than half of the children (61%) had normal weight. The obtained VO2 peak was 43.7 ± 6.5 ml/min/kg (106.7 ± 19.8% of the predictive values). Only 10% of the children had values lower than those predicted by sex and age. No correlations were found between VO2 peak and anthropometric and pulmonary function variables. Conclusion: Most of the evaluated children (90%) had physical capacity similar to healthy subjects by sex and age

    Leukoencephalopathy resolution after atypical mycobacterial treatment: a case report

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    Abstract\ud \ud Background\ud Association of leukoencephalopathy and atypical mycobacteriosis has been rarely reported. We present a case that is relevant for its unusual presentation and because it may shed further light on the pathogenic mechanisms underlying reversible encephalopathies.\ud \ud \ud Case report\ud We report the case of a Hispanic 64-year-old woman with cognitive decline and extensive leukoencephalopathy. Magnetic resonance imaging revealed white-matter lesions with increased water diffusivity, without blood–brain-barrier disruption. Brain biopsy showed tissue rarefaction with vacuolation, mild inflammation, few reactive astrocytes and decreased aquaporin water-channel expression in the lesions. Six months later, she was diagnosed with atypical mycobacterial pulmonary infection. Brain lesions resolved after antimycobacterial treatment.\ud \ud \ud Conclusion\ud We hypothesize leukoencephalopathic changes and vasogenic edema were associated with decreased aquaporin expression. Further studies should clarify if reversible leukoencephalopathy has a causal relationship with decreased aquaporin expression and atypical mycobacterial infection, and mechanisms underlying leukoencephalopathy resolution after antimycobacterial treatment. This article may contribute to the understanding of pathogenic mechanisms underlying magnetic resonance imaging subcortical lesions and edema, which remain incompletely understood.Ministry of Education, Culture, Sports, Science and Technology (MEXT) of JapanHealth and Labor Sciences Research Grant on Intractable Diseases\ud (Neuroimmunological Diseases) from the Ministry of Health, Labor and\ud Welfare of Japa
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