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

Responsivity and Reproducibility of Sputum Inflammatory Biomarkers During COPD Exacerbation and Stable Phases - A Pilot Study

Introduction: There is a great interest to identify airway biomarkers to evaluate the potential and efficacy of anti-inflammatory therapeutic interventions. In this pilot study, we compared cytokine mRNA and protein levels of IL-6, IL-8, CCL2, CCL4, and TNF-α, as well as LTB-4 expression regarding their reproducibility and responsivity in induced sputum in COPD patients. Methods: We recruited a cohort of 17 patients with a moderate COPD exacerbation, necessitating antibiotics and/or oral corticosteroids. Patients were followed for two consecutive stable phase visits. Cytokine mRNA and protein levels were measured in induced sputum samples. Results: IL-6 and CCL4 protein levels decreased from exacerbation to stable phase, whereas their mRNA expression showed the same trend (not statistically significant). Coefficients of variation were overall lower (ie, more favorable for responsiveness) at protein levels compared to mRNA levels. No significant differences were observed in the reproducibility between cytokine mRNA expression and protein measurements. IL-6, IL-8, CCL2, and TNF-α gene expression levels yielded moderate to high intraclass correlation coefficients and/or Spearman correlation coefficients between both stable phase samples in contrast to their protein levels. Conclusion: Our findings suggest that several protein levels yield better responsivity with lower noise-to-signal ratios compared to their respective mRNA levels. In contrast, cytokine mRNA expression was more reproducible as it varied less in a stable state than proteins. Future studies are needed with a larger sample size to further evaluate the differences of responsivity and reproducibility between cytokine mRNA and protein measurements, not only during exacerbations

The Microbiome in Bronchial Biopsies from Smokers and Ex-Smokers with Stable COPD - A Metatranscriptomic Approach

Current knowledge about the respiratory microbiome is mainly based on 16S ribosomal RNA gene sequencing. Newer sequencing approaches, such as metatranscriptomics, offer the technical ability to measure the viable microbiome response to environmental conditions such as smoking as well as to explore its functional role by investigating host-microbiome interactions. However, knowledge about its feasibility in respiratory microbiome research, especially in lung biopsies, is still very limited. RNA sequencing was performed in bronchial biopsies from clinically stable smokers (n=5) and ex-smokers (n=6) with COPD not using (inhaled) steroids. The Trinity assembler was used to assemble non-human reads in order to allow unbiased taxonomical and microbial transcriptional analyses. Subsequently, host-microbiome interactions were analyzed based on associations with host transcriptomic data. Ultra-low levels of microbial mass (0.009%) were identified in the RNA-seq data. Overall, no differences were identified in microbiome diversity or transcriptional profiles of microbial communities or individual microbes between COPD smokers and ex-smokers in the initial test dataset as well as a larger replication dataset. We identified an upregulated host gene set, related to the simultaneous presence of Bradyrhizobium, Roseomonas, Brevibacterium.spp., which were related to PERK-mediated unfolded protein response (UPR) and expression of the microRNA-155-5p. Our results show that metatranscriptomic profiling in bronchial biopsy samples from stable COPD patients yields ultra-low levels of microbial mass. Further, this study illustrates the potential of using transcriptional profiling of the host and microbiome to gain more insight into their interaction in the airways

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