Comportamento De Almofadas De Argamassa Modificada Na Transferência De Tensões De Compressão

This research aims to analyze the compressive stress transfer between precast concrete elements using cement mortar pads modified with polypropylene fibers, styrene-butadiene latex and heat-expanded vermiculite. The stress transfer analyses are performed interleaving a cementbearing pad between two concrete blocks, subjecting the entire specimen to different compressive load tests. The parameters analyzed in the tests are: surface roughness (using bosses on the bonded phase of different thicknesses), compressive strength with monotonic and cyclic loadings. The main results obtained in this study are: a) the presence of pad increased the strength in 24% for thicknesses of imperfections of 0.5 mm and approximately 12% for smooth faces blocks; b) gain of effectiveness of the bearing pad when the concrete strength was reduced; c) for cyclic loading, the bearing pad increased in 48% the connections strength.9341443

Comportamento de almofadas de argamassa modificada na transferência de tensões de compressão

This research aims to analyze the compressive stress transfer between precast concrete elements using cement mortar pads modified with polypropylene fibers, styrene-butadiene latex and heat-expanded vermiculite. The stress transfer analyses are performed interleaving a cementbearing pad between two concrete blocks, subjecting the entire specimen to different compressive load tests. The parameters analyzed in the tests are: surface roughness (using bosses on the bonded phase of different thicknesses), compressive strength with monotonic and cyclic loadings. The main results obtained in this study are: a) the presence of pad increased the strength in 24% for thicknesses of imperfections of 0.5 mm and approximately 12% for smooth faces blocks; b) gain of effectiveness of the bearing pad when the concrete strength was reduced; c) for cyclic loading, the bearing pad increased in 48% the connections strength.O objetivo deste trabalho é analisar a transferência de tensões de compressão entre elementos de concreto pré-moldado através de almofadas de argamassa modificadas com fibras de polipropileno, látex estireno-butadieno e vermiculita termo-expandida. As análises de transferência de tensões foram realizadas intercalando uma almofada entre dois blocos de concreto e submetendo o corpo de prova a ensaios de compressão. Os parâmetros variados foram: rugosidade superficial (saliências na face ligada de diferentes espessuras), resistência à compressão do concreto dos blocos e carregamento monotônico e cíclico. Os principais resultados dos ensaios de ligação foram: a) a presença da almofada aumentou a resistência em 24% para espessuras de saliências de 0,5 mm e cerca de 12% para blocos com faces ligadas lisas; b) a efetividade da almofada aumentou à medida que se reduziu a resistência à compressão do concreto; c) para carregamento cíclico, a almofada de apoio aumentou em 48% a resistência da ligação.9341443

Cholinergic neuroplasticity in asthma driven by TrkB signaling

Parasympathetic neurons in the airways control bronchomotor tone. Increased activity of cholinergic neurons are mediators of airway hyperresponsiveness (AHR) in asthma, however, mechanisms are not elucidated. We describe remodeling of the cholinergic neuronal network in asthmatic airways driven by brain-derived neurotrophic factor (BDNF) and Tropomyosin receptor kinase B (TrkB). Human bronchial biopsies were stained for cholinergic marker vesicular acetylcholine transporter (VAChT). Human lung gene expression and single nucleotide polymorphisms (SNP) in neuroplasticity-related genes were compared between asthma and healthy patients. Wild-type (WT) and mutated TrkB knock-in mice (Ntrk2tm1Ddg/J) with impaired BDNF signaling were chronically exposed to ovalbumin (OVA). Neuronal VAChT staining and airway narrowing in response to electrical field stimulation in precision cut lung slices (PCLS) were assessed. Increased cholinergic fibers in asthmatic airway biopsies was found, paralleled by increased TrkB gene expression in human lung tissue, and SNPs in the NTRK2 [TrkB] and BDNF genes linked to asthma. Chronic allergen exposure in mice resulted in increased density of cholinergic nerves, which was prevented by inhibiting TrkB. Increased nerve density resulted in AHR in vivo and in increased nerve-dependent airway reactivity in lung slices mediated via TrkB. These findings show cholinergic neuroplasticity in asthma driven by TrkB signaling and suggest that the BDNF-TrkB pathway may be a potential target

Nachweis und Bestimmung der Halogensauerstoffverbindungen

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The Amazon Tall Tower Observatory (ATTO): Overview of pilot measurements on ecosystem ecology, meteorology, trace gases, and aerosols

The Amazon Basin plays key roles in the carbon and water cycles, climate change, atmospheric chemistry, and biodiversity. It has already been changed significantly by human activities, and more pervasive change is expected to occur in the coming decades. It is therefore essential to establish long-term measurement sites that provide a baseline record of present-day climatic, biogeochemical, and atmospheric conditions and that will be operated over coming decades to monitor change in the Amazon region, as human perturbations increase in the future. The Amazon Tall Tower Observatory (ATTO) has been set up in a pristine rain forest region in the central Amazon Basin, about 150 km northeast of the city of Manaus. Two 80 m towers have been operated at the site since 2012, and a 325 m tower is nearing completion in mid-2015. An ecological survey including a biodiversity assessment has been conducted in the forest region surrounding the site. Measurements of micrometeorological and atmospheric chemical variables were initiated in 2012, and their range has continued to broaden over the last few years. The meteorological and micrometeorological measurements include temperature and wind profiles, precipitation, water and energy fluxes, turbulence components, soil temperature profiles and soil heat fluxes, radiation fluxes, and visibility. A tree has been instrumented to measure stem profiles of temperature, light intensity, and water content in cryptogamic covers. The trace gas measurements comprise continuous monitoring of carbon dioxide, carbon monoxide, methane, and ozone at five to eight different heights, complemented by a variety of additional species measured during intensive campaigns (e.g., VOC, NO, NO2, and OH reactivity). Aerosol optical, microphysical, and chemical measurements are being made above the canopy as well as in the canopy space. They include aerosol light scattering and absorption, fluorescence, number and volume size distributions, chemical composition, cloud condensation nuclei (CCN) concentrations, and hygroscopicity. In this paper, we discuss the scientific context of the ATTO observatory and present an overview of results from ecological, meteorological, and chemical pilot studies at the ATTO site. © Author(s) 2015