Numerical model to evaluate the protected and unprotected wooden slabs under fire

The main goal of this study is to evaluate the thermal behaviour of wooden cellular slabs exposed to fire conditions, according the standard ISO 843 curve. Different numerical simulations for nonlinear thermal and transient analysis will be obtained, using the finite element method. The importance of this study relies on its contribution to an alternative numerical methodology, which allows to determine the safety and fire resistance levels in wooden cellular slabs, with or without insulation materials.info:eu-repo/semantics/publishedVersio

Análise térmica de lajes em madeira com e sem proteção

Mestrado com dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáA madeira tem sido amplamente utilizada como material de construção devido à sua disponibilidade na natureza, variedade de espécies, leveza e características físicas, químicas e mecânicas. Este material é utilizado em muitas aplicações da construção civil, nomeadamente em pavimentos, paredes e soalhos. Em condições de trabalho adversas, como exposição ao fogo, suas propriedades sofrem degradação, comprometendo o seu desempenho e a segurança no local. Este trabalho tem como principal objetivo analisar o comportamento de lajes celulares de madeira quando expostas em uma situação de incêndio, de acordo com a utilização da curva ISO 834, através de simulações numéricas para análise térmica não-linear em regime transiente, utilizando o método dos elementos finitos. Foram consideradas as propriedades da madeira Abeto, com massa volúmica de 341 [kg/m³] e um teor de humidade a 11%. As propriedades térmicas foram utilizadas de acordo com as recomendações do Eurocódigo 5. A validação do modelo térmico utilizado foi realizada através da comparação entre velocidade de carbonização calculada para todos os modelos propostos e os valores prescritos no Eurocódigo. Verificou-se o aumento da resistência ao fogo com a utilização de materiais isolantes de diferentes espessuras e densidades, onde a fibra de vidro de 145 [mm] de espessura apresentou melhor desempenho para cavidades em condições adiabáticas. Posteriormente, uma malha de elementos finitos com as propriedades do ar foi inserida nas simulações, influenciando significativamente no comportamento térmico dos materiais, sendo que para esta situação a lã de rocha de 60 [mm] obteve melhor desempenho. A realização deste estudo foi importante, pois permitiu verificar a influéncia da espessura e densidade dos materiais isolantes e a presença do ar nas simulações. Em geral, a análise térmica baseada em simulação numérica contribui para o aumento nos níveis de segurança e de resistência ao fogo em lajes celulares de madeira com e sem isolamento.Wood has been widely used as a building material because of its availability in nature, variety of species, lightness and physical, chemical and mechanical characteris-tics. This material is used in many civil construction, floor and wall applications. With adverse working conditions such as fire exposure, their properties suffer degradation, compromising their performance and safety in place. The main objective of this work is to analyze the behavior of wood slabs exposed to the fire situation, according to the use of the ISO 843 curve, performing numerical simulations for transient and nonlinear thermal analysis with the finite element method. The properties of Spruce with a density of 341 [kg/m³] and a moisture content of 11% were considered. The thermal properties were used in accordance with Eurocode 5. The validation of the thermal model was per-formed by comparing the obtained charring rate with the values prescribed in the litera-ture. The increase in fire resistance was verified with the use of insulating materials with different thicknesses and densities, where 145 [mm] thick glass fiber showed better performance under adiabatic conditions. Afterwards, the air effect was considered in the simulations, influencing the thermal behavior of the slab, where the rock wool of 60 [mm] obtained the better performance. This study was important because it allowed to verify the effect of the insulation thickness, the density and the air modelling effect in the numerical simulations. In general, thermal analysis based on numerical simulation contributes to the increase in levels of safety and fire resistance in wodden cellular slabs with and without insulation

Astrophysics from data analysis of spherical gravitational wave detectors

The direct detection of gravitational waves will provide valuable astrophysical information about many celestial objects. Also, it will be an important test to general relativity and other theories of gravitation. The gravitational wave detector SCHENBERG has recently undergone its first test run. It is expected to have its first scientific run soon. In this work the data analysis system of this spherical, resonant mass detector is tested through the simulation of the detection of gravitational waves generated during the inspiralling phase of a binary system. It is shown from the simulated data that it is not necessary to have all six transducers operational in order to determine the source's direction and the wave's amplitudes.Comment: 8 pages and 3 figure

Metodologia participativa sobre a avaliação do comportamento ao fogo de lajes em madeira como contributo na segurança

• A madeira é um material de construção muito utilizado, tanto em Portugal como no Brasil, nomeadamente em pavimentos, paredes e soalhos. • A madeira é um recurso renovável. • A madeira possui excelentes características arquitetônicas, térmicas e acústicas, permitindo a assemblagem fácil de conjuntos. • A madeira quando exposta a ações acidentais, tais como condições de incêndio, apresenta a formação de uma camada de carbono na superfície. • No entanto, esta camada pode atrasar o processo de aquecimento para a secção de núcleo, atuando como um isolante. • O complexo comportamento ao fogo é o alvo de estudo deste trabalho.info:eu-repo/semantics/publishedVersio

PARÂMETROS MORFOMÉTRICOS DE DRENAGEM NA BACIA DO RIO MACAÉ (RJ): CONTRIBUIÇÃO PARA ABORDAGEM MORFOTECTÔNICA.

A aplicação de parâmetros morfométricos em bacias de drenagem é uma importante ferramenta na compreensão do sistema fluvial. O objetivo da pesquisa foi analisar os índices RDE, FABD, FSTT e Perfil Longitudinal nos rios Sana e Dantas. No rio Sana há migração preferencial do canal em direção à margem esquerda e no rio Dantas o canal se mantém próximo ao eixo central da bacia. Necessita-se de investigação detalhada na bacia aplicando metodologias voltadas a questão da morfotectônica regional

Phytoestrogen agathisflavone ameliorates neuroinflammation-induced by LPS and IL-1β and protects neurons in cocultures of glia/neurons

Inflammation and oxidative stress are common aspects of most neurodegenerative diseases in the central nervous system. In this context, microglia and astrocytes are central to mediating the balance between neuroprotective and neurodestructive mechanisms. Flavonoids have potent anti-inflammatory and antioxidant properties. Here, we have examined the anti-inflammatory and neuroprotective potential of the flavonoid agathisflavone (FAB), which is derived from the Brazilian plant Poincianella pyramidalis, in in vitro models of neuroinflammation. Cocultures of neurons/glial cells were exposed to lipopolysaccharide (LPS, 1 µg/mL) or interleukin (IL)-1β (10 ng/mL) for 24 h and treated with FAB (0.1 and 1 µM, 24 h). FAB displayed a significant neuroprotective effect, as measured by nitric oxide (NO) production, Fluoro-Jade B (FJ-B) staining, and immunocytochemistry (ICC) for the neuronal marker β-tubulin and the cell death marker caspase-3, preserving neuronal soma and increasing neurite outgrowth. FAB significantly decreased the LPS-induced microglial proliferation, identified by ICC for Iba-1/bromodeoxyuridine (BrdU) and CD68 (microglia M1 profile marker). In contrast, FAB had no apparent effect on astrocytes, as determined by ICC for glial fibrillary acidic protein (GFAP). Furthermore, FAB protected against the cytodestructive and proinflammatory effects of IL-1β, a key cytokine that is released by activated microglia and astrocytes, and ICC showed that combined treatment of FAB with α and β estrogen receptor antagonists did not affect NF-κB expression. In addition, qPCR analysis demonstrated that FAB decreased the expression of proinflammatory molecules TNF-α, IL-1β, and connexins CCL5 and CCL2, as well as increased the expression of the regulatory molecule IL-10. Together, these findings indicate that FAB has a significant neuroprotective and anti-inflammatory effect in vitro, which may be considered as an adjuvant for the treatment of neurodegenerative diseases

Assessing uncertainties in estimating surface energy fluxes from remote sensing over natural grasslands in Brazil

Evapotranspiration (ET) is one of the main fluxes in the global water cycle. As the Brazilian Pampa biome carries a rich biodiversity, accurate information on the ET dynamics is essential to support its proper monitoring and establish conservation strategies. In this context, we assessed an operational methodology based on the Simplified Surface Energy Balance Index (S-SEBI) model to estimate energy fluxes over the natural grasslands of the Pampa between 2014 and 2019. The S-SEBI is an ET model that requires a minimum of meteorological inputs and has demonstrated reasonable accuracy worldwide. Therefore, we investigated the model performance considering radiation data from both ERA5 reanalysis and Eddy Covariance measurements from a flux tower. Furthermore, comparisons from satellite-based estimates with in situ measurements were performed with and without energy balance closure (EBC). Results indicated that the meteorological inputs have low sensitivity on daily ET estimates from the S-SEBI model. In contrast, the instantaneous energy balance components are more affected. The strong seasonality impacts the evaporative fraction, which is more evident in late summer and autumn and may compromise the performance of the model in the biome. The effects in the daily ET are lower when in situ data without EBC are considered as ground truth. However, they are less correlated with the remote sensing-based estimates. These insights are useful to monitor water and energy fluxes from local to regional scale and provide the opportunity to capture ET trends over the natural grasslands of the Pampa

Species Composition and Diversity in two Selected Lowland Tropical Rainforests in Sri Lanka and their Relationships to Temperature and Precipitation

Tropical rainforests are characterised by high species diversity, which may be due to a range of factors such as climate, topography, soil properties and the level of disturbance, both natural and anthropogenic. This study focused on investigating the species composition, richness, diversity and their conservation status in lowland tropical rainforests at two selected locations in Sri Lanka and determining their relationships to temperature and precipitation. Two permanent one-hectare sampling plots each were established at the Kanneliya (KDN1 and KDN2) and Pitadeniya-Sinharaja (PTD1 and PTD2) Forest Reserves. All trees with dbh≥10 cm were enumerated. A total of 3,303 trees were recorded, representing 158 species from 91 genera and 53 families, with a total basal area of 196.26 m2. Most abundant plant species were Alstonia macrophylla in KDN1 (11.7% of trees with dbh≥10 cm), Syzygium grande in KDN2 (9.8%), Shorea affinis in PTD1 (15.8%) Mesua thwaitesii in PTD2 (17.5%). Cullenia rosayroana (7.2%) is the most abundant species within the whole study area. While 25 species were recorded in all four plots, 70 species were found in only one location. Genus Shorea (18.6%) is the most common including 12 different species and Dipterocarpaceae (21.9%) is the most common family including 19 species. KDN1 recorded 1,011 plants from 108 species, with 74.3% endemic, 12.8% native and 11.9% exotic species. Other study sites recorded only endemic (88% at KDN2, 83.7% at PTD1 and 82.3% at PTD2) and native species. In comparison to PTD, KDN recorded higher numbers of trees with dbh≥10 cm (Chi-square p<0.0001), species (p<0.0001) and genera (p=0.0091). KDN also recorded a higher number of families but the difference was not significant (p=0.358). All indices of species diversity (Shannon index, H and Simpson index, D), evenness (J) and richness (R) are higher at KDN. However, only the difference in D was statistically-significant at p=0.05. Multiple regression analysis using the stepwise procedure showed that the number of trees with dbh≥10 cm and the species number increased with increasing average annual air temperature (T) but decreased with annual total precipitation (P). On the other hand, the numbers of genera and families increased with decreasing P with T not having a significant influence. The two diversity indices, H and D, increased with decreasing P and increasing T. In contrast, increasing P decreased J and R whereas variation in T did not have a significant influence. These findings provide important insights in to dynamics plant diversity in response to environmental changes.Keywords: Species composition, Species diversity, Tropical rainforest

Neuroimmunomodulatory and neuroprotective effects of the flavonoid apigenin in in vitro models of neuroinflammation associated with Alzheimer's disease

Neurodegenerative disorders (ND) are characterized by the progressive and irreversible loss of neurons. Alzheimer’s Disease (AD) is the most incident age-related ND, in which the presence of a chronic inflammatory compound seems to be related to its pathogenesis. Different stimuli in the central nervous system (CNS) can induce activation, proliferation, and changes in phenotype and glial function, which can be modulated by anti-inflammatory agents. Apigenin (4,5,7–trihydroxyflavone) is a flavonoid found in abundance in many fruits and vegetables, that has shown important effects upon controlling the inflammatory response. This study evaluated the neuroprotective and neuroimmunomodulatory potential of apigenin using in vitro models of neuroinflammation associated with AD. Co-cultures of neurons and glial cells were obtained from the cortex of newborn and embryonic Wistar rats. After 26 days in vitro, cultures were exposed to lipopolysaccharide (LPS; 1 μg/ml), or IL-1β (10 ng/ml) for 24 h, or to Aβ oligomers (500 nM) for 4 h, and then treated with apigenin (1 μM) for further 24 h. It was observed that the treatment with apigenin preserved neurons and astrocytes integrity, determined by Rosenfeld’s staining and immunocytochemistry for β-tubulin III and GFAP, respectively. Moreover, it was observed by Fluoro-Jade-B and caspase-3 immunostaining that apigenin was not neurotoxic and has a neuroprotective effect against inflammatory damage. Additionally, apigenin reduced microglial activation, characterized by inhibition of proliferation (BrdU+ cells) and modulation of microglia morphology (Iba-1 + cells), and decreased the expression of the M1 inflammatory marker CD68. Moreover, as determined by RT-qPCR, inflammatory stimuli induced by IL-1β increased the mRNA expression of IL-6, IL-1β, and CCL5, and decreased the mRNA expression of IL-10. Contrary, after treatment with apigenin in inflammatory stimuli (IL-1β or LPS) there was a modulation of the mRNA expression of inflammatory cytokines, and reduced expression of OX42, IL-6 and gp130. Moreover, apigenin alone and after an inflammatory stimulus with IL-1β also induced the increase in the expression of brain-derived neurotrophic factor (BDNF), an effect that may be associated with anti-inflammatory and neuroprotective effects. Together these data demonstrate that apigenin presents neuroprotective and anti-inflammatory effects in vitro and might represent an important neuroimmunomodulatory agent for the treatment of neurodegenerative conditions

Hadean geodynamics inferred from time-varying 142Nd/144Nd in the early Earth rock record

Tracking the secular evolution of 142Nd/144Nd anomalies is important towards understanding the crust-mantle dynamics in the early Earth. Excessive scatter in the published data, however, precludes identifying the fine structure of 142Nd/144Nd evolution as the expected variability is on the order of few parts per million. We report ultra-high precision 142Nd/144Nd data for Eoarchean and Palaeoarchean rocks from the Isua Supracrustal Belt (SW Greenland) that show a well-resolved 142Nd/144Nd temporal variability suggesting progressive convective homogenisation of the Hadean Isua depleted mantle. This temporally decreasing 142Nd/144Nd signal provides a direct measure of early mantle dynamics, defining a stirring timescale of <250 Myr consistent with vigorous convective stirring in the early mantle. The 142Nd/144Nd evolution suggests protracted crustal residence times of ~1000-2000 Myr, inconsistent with modern-style plate tectonics in the Archean. In contrast, a stagnant-lid regime punctuated by episodes of mantle overturns accounts for the long life-time estimated here for the Hadean proto-crust