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Variation of wood density and relationship with the tree-ring width of mahogany trees, Swietenia macrophylla, from Amazonian tropical forest of Peru

ALVARADO, Jedi Rosero; TOMAZELLO FILHO, Mario; POLLITO, Percy Amilcar Zevallos; LOBAO, Moises Silveira
Fonte: IPEF-INST PESQUISAS ESTUDOS FLORESTAIS Publicador: IPEF-INST PESQUISAS ESTUDOS FLORESTAIS
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
36.06%
Mahogany trees, Swietenia macrophylla, occur in open rainforest, semi deciduous and deciduous and dense rainforest of Peruvian Amazonian tropical forest. They occur, preferentially, in areas with a defined dry season, with typical phenology and seasonal variation activity, forming distinct tree-rings. The present work had as aim to determine the wood density radial variation of 14 mahogany trees, of two populations of the Peruvian Amazonian tropical forest, through the X-ray densitometry and to evaluate their application as methodology, compared to the classic method of measurement table, for the determination of the treering width. The radial wood apparent density of the trees profiles rendered it possible to delimit the areas of juvenile-adult wood and of the heartwood-sapwood, relative to the anatomical structure and chemical composition differences, due to the extractives and the vessels obstruction by tyloses. The mean, minimum and maximum wood apparent density of the mahogany trees for the Populations A and B were of 0.70; 0.29; 1.01 g.cm(-3) and 0.81; 0.29; 1.19 g.cm(-3), respectively. The analysis of the variance and mean test indicate differences of mean wood density among the mahogany trees of each population, probably due to the age of the trees. There was no correlation between mean wood density of mahogany trees among the two populations...

Bone mineral apparent density in juvenile dermatomyositis: the role of lean body mass and glucocorticoid use

SANTIAGO, R. A.; SILVA, C. A. A.; CAPARBO, V. F.; SALLUM, A. M. E.; PEREIRA, R. M. R.
Fonte: TAYLOR & FRANCIS AS Publicador: TAYLOR & FRANCIS AS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.9%
Objective: To analyse bone mineral density (BMD) in juvenile dermatomyositis (JDM) and its possible association with body composition, disease activity, duration of disease, glucocorticoid (GC) use, and biochemical bone parameters, including osteoprotegerin (OPG) and receptor activator of nuclear factor B (RANKL). Methods: Twenty girls with JDM and 20 controls matched for gender and age were selected. Body composition and BMD were analysed by dual-energy X-ray absorptiometry (DXA) and bone mineral apparent density (BMAD) was calculated. Duration of disease, cumulative GC, and GC pulse therapy use were determined from medical records. Disease activity and muscle strength were measured by the Disease Activity Score (DAS), the Childhood Myositis Assessment Scale (CMAS), and the Manual Muscle Test (MMT). Inflammatory and bone metabolism parameters were also analysed. OPG and RANKL were measured in patients and controls using an enzyme-linked immunosorbent assay (ELISA). Results: A lower BMAD in the femoral neck (p< 0.001), total femur (p< 0.001), and whole body (p=0.005) was observed in JDM patients compared to controls. Body composition analysis showed a lower lean mass in JDM compared to controls (p=0.015), but no difference was observed with regard to fat mass. A trend of lower serum calcium was observed in JDM (p=0.05)...

Low bone mass in juvenile onset sclerosis systemic: the possible role for 25-hydroxyvitamin D insufficiency

SHINJO, Samuel Katsuyuki; BONFA, Eloisa; CAPARBO, Valeria de Falco; PEREIRA, Rosa Maria Rodrigues
Fonte: SPRINGER HEIDELBERG Publicador: SPRINGER HEIDELBERG
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.97%
Juvenile onset systemic sclerosis (JoSSc) is a rare disease, and there are no studies focusing in bone mineral density and biochemical bone parameters. Ten consecutive patients with JoSSc and 10 controls gender, age, menarche age, and physical activity matched were selected. Clinical data were obtained at the medical visit and chart review. Laboratorial analysis included autoantibodies, 25-hydroxyvitamin D (25OHD), intact parathyroid hormone, calcium, phosphorus, alkaline phosphatase and albumin sera levels. Bone mineral density was analyzed by dual-energy X-ray absorptiometry, and bone mineral apparent density (BMAD) was calculated. A lower BMAD in femoral neck (0.294 +/- A 0.060 vs. 0.395 +/- A 0.048 g/cm(3), P = 0.001) and total femur (0.134 +/- A 0.021 vs. 0.171 +/- A 0.022 g/cm(3), P = 0.002) was observed in JoSSc compared to controls. Likewise, a trend to lower BMAD in lumbar spine (0.117 +/- A 0.013 vs. 0.119 +/- A 0.012 g/cm(3), P = 0.06) was also found in these patients. Serum levels of 25OHD were significantly lower in JoSSc compared to controls (18.1 +/- A 6.4 vs. 25.1 +/- A 6.6 ng/mL, P = 0.04), and all patients had vitamin D insufficiency (< 20 ng/mL) compared to 40% of controls (P = 0.01). All other biochemical parameters were within normal range and alike in both groups. BMAD in femoral neck and total femur was correlated with 25OHD levels in JoSSc (r = 0.82...

Tomografia de impulso para estimativa da densidade da madeira; Impulse tomography for wood density estimate

Rollo, Luciana Cavalcante Pereira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/02/2010 PT
Relevância na Pesquisa
46.08%
Há diversas técnicas que utilizam a passagem de ondas através da madeira para obtenção de informações. Dentre elas destaca-se a tomografia de árvores que reconstrói seções transversais de tronco e galhos. A tomografia de impulso, por sua vez, se baseia na cronometragem da viajem de ondas mecânicas sonoras entre sensores anexados em uma seção transversal da árvore, para cálculo da velocidade da onda e construção da imagem tomográfica. Sabe-se que a velocidade de passagem das ondas mecânicas é determinada pelas propriedades físico-mecânicas da madeira. Em especial: o módulo de elasticidade, a densidade e a umidade. Até o momento, há diversos estudos sobre a correlação entre a velocidade de onda (principalmente ultrassom) e o módulo de elasticidade. Os estudos apresentados a seguir se destacam por avaliar a correlação entre a velocidade de onda mecânica, obtida por tomografia de impulso, e a densidade da madeira, com vistas em utilizá-la como ferramenta na estimativa da densidade. Os diversos métodos consagrados para a determinação da densidade se caracterizam por utilizar amostras de madeira, que em muitos casos são de difícil obtenção. Além de serem executados procedimentos laboratoriais que podem levam até semanas. Dessa forma...

Influência da variabilidade dimensional e da densidade da madeira de Eucalyptus sp. e Corymbia sp. na qualidade do carvão; Influence of dimensional variability and density of Eucalyptus sp. and Corymbia sp. in the coal quality

Moutinho, Victor Hugo Pereira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 23/11/2012 PT
Relevância na Pesquisa
45.85%
O presente trabalho objetivou a determinação e análise comparativa das propriedades físicas da madeira e do respectivo carvão vegetal, ao longo da direção radial e longitudinal do lenho de árvores de dez clones de alta produtividade de Eucalyptus e Corymbia. Para tanto, discos de diferentes alturas do tronco foram coletados de árvores das espécies, no município de Capelinha-MG, obtendo-se amostras para a determinação da densidade básica, contração linear e volumétrica, coeficiente de anisotropia e umidade inicial. Na sequência, os corpos de prova foram carbonizados, visando a determinação da densidade aparente, degradação linear e volumétrica, rendimento gravimétrico e resistência mecânica à compressão. Na avaliação do experimento, utilizou-se a análise de variância, segundo delineamento inteiramente casualizado e as análises de componentes principais (ACP), dissimilaridade e multivariada (correlação canônica) na avaliação comparativa entre as propriedades físicas da madeira e do carvão. Como resultados, verificou-se uma alta heterogeneidade entre as espécies estudadas, as quais dividiram-se em 4 grupos distintos, sendo que as contrações lineares e volumétricas mostraram-se independentes da densidade e com correlações significativas entre si. Após a carbonização...

Avaliação do crescimento e da qualidade do lenho de árvores de Eucalyptus urophylla, de 8 anos, de teste de progênies, visando a produção de carvão vegetal; Growth and wood quality evaluation of 8 years Eucalyptus urophylla trees, of progeny tests, in order to produce charcoal

Almonacid, Marco Aurelio Arizapana
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 08/03/2013 PT
Relevância na Pesquisa
36.04%
As metodologias de análise da qualidade do lenho e dos anéis de crescimento das árvores de eucalipto são importantes para a determinação do incremento anual do seu tronco, da densidade básica e aparente do lenho, dentre outros, visando os programas de melhoramento, como a seleção precoce de árvores geneticamente superiores para a qualidade da madeira, produção de carvão vegetal, etc. Pelo exposto, o presente trabalho avaliou a qualidade do lenho das árvores de Eucalyptus urophylla, de 8 anos,de um teste de progênie, visando a produção de carvão vegetal, instalado em novembro de 2003, no município de Itamarandiba, MG. Foram mensuradas a altura e o DAP de 6 árvores de E. urophylla, das parcelas lineares de 8 árvores, aos 13º, 21º, 38º, 60º e 82º meses, para a determinação do incremento corrente e acumulado do tronco.A qualidade do lenho das árvores em pé foi realizada em novembro de 2008, determinando a resistência do lenho com o equipamento Pilodyn.Em seguida, foram selecionadas, cortadas e desramadas 4 árvores dos blocos 1, 3, e 5, em um total de 312 árvores e cortados cilindros do lenho na base, DAP, 25, 50, 75 e 100% da altura comercial do tronco.Na seção transversal dos discos de lenho foi feita a caracterização macroscópica e a determinação da largura dos anéis de crescimento anuais do lenho. Na aferição da anuidade da formação dos anéis de crescimento foram analisadas as cicatrizes das injúrias da retirada de placa da casca e aplicação da agulha do pilodyn (novembro de 2008...

Avaliação da estrutura anatômica e da densidade aparente do lenho e do carvão de árvores de Eucalyptus sp. e de Corymbia sp.; Evaluation of the anatomical structure and apparent density of the wood and charcoal from Eucalyptus sp. and Corymbia sp. trees

Ferreira, Angel Thiane Boschiero
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/11/2013 PT
Relevância na Pesquisa
46.09%
A madeira é considerada como estratégica como produto base para inúmeros setores e segmentos da economia mundial e nacional, para a produção de móveis, pisos, construção, celulose, papel e outros produtos e, ainda, no setor energético, para a produção de álcool, e, em especial no Brasil, para o carvão vegetal, em siderúrgicas. O carvão da madeira de florestas plantadas de eucaliptos traz um maior benefício ao país, pela redução da pressão da exploração da madeira das florestas nativas. A transformação da madeira em carvão ocorre através de tratamento térmico, compreendendo diversas fases de aquecimento, com consequente alteração da madeira, como a perda de água, contração, degradação e ruptura da parede celular dos seus elementos anatômicos. Neste aspecto, são incipientes os estudos das alterações da anatomia da madeira dos eucaliptos resultantes do processo de carbonização e sua aplicação na melhoria da estrutura e da qualidade do carvão. Pelo exposto, o presente trabalho tem como objetivo estudar as alterações da estrutura anatômica, densidade aparente e variação dimensional da madeira e do carvão de árvores de 19 clones/espécies/híbridos de Eucalyptus e Corymbia, de plantações da Aperam Bioenergia Jequitinhonha...

Caracterização anatômica e física - por densitometria de raios X - de colmos de Dendrocalamus asper Backer, Dendrocalamus latiflorus Munro e Guadua angustifolia Kunth; Anatomical and physical characterization - by X-ray densitometry - of culms of Dendrocalamus asper Backer, Dendrocalamus latiflorus Munro and Guadua angustifolia Kunth

Geroto, Priscila Garcia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/05/2014 PT
Relevância na Pesquisa
46.14%
A viabilidade da produção, do manejo e da utilização dos colmos de bambu no Brasil, em relação às árvores de espécies florestais de eucaliptos e pinus, entre outras, foi a principal motivadora do presente trabalho. Com esse objetivo foram caracterizados os colmos de 3 espécies de bambu, consideradas prioritárias pelo INBAR, a saber Dendrocalamus asper, D. latiflorus e Guadua angustifolia da Coleção de Bambus da Área Experimental Agrícola do Departamento de Engenharia Mecânica, Campus da UNESP, Bauru, SP. Amostras dos colmos das 3 espécies, coletadas através de método não destrutivo, foram caracterizadas em relação à estrutura anatômica macro e microscópica. Por meio da técnica de densitometria de raios X , a densidade aparente ao longo da espessura dos colmos foi determinada, e os perfis de densidade radial foram plotados em gráficos. Os resultados das análises laboratoriais evidenciaram que (i) as 3 espécies apresentam uma estrutura anatômica macro e microscópica que permite a sua identificação taxonômica e caracterização tecnológica, em relação aos tecidos de parênquima, feixes vasculares e bainha de fibras; (ii) a variação da estrutura anatômica e da densidade aparente ao longo da espessura dos colmos...

Rehydration and shrinkage behaviour of dried pineapple

Nicoleti, J. F.; Telis-Romero, J.; Telis, VRN; Waliszewski, K. N.
Fonte: Isnt Tecnologico Veracruz Publicador: Isnt Tecnologico Veracruz
Tipo: Conferência ou Objeto de Conferência Formato: 253-262
ENG
Relevância na Pesquisa
45.92%
The shrinking behavior, apparent densities and rehydration indexes of fresh and osmotically pre-treated pineapple slices during air-drying were obtained. The air drying velocity varied from 1.5 to 2.5 m/s and the air temperature from 40 to 70 degreesC. By means of automatic control, it was possible to obtain drying curves under conditions of constant product temperature. Volumetric shrinkage of fresh samples was temperature independent for drying at high air velocities but, at lower velocities, increased with decreasing drying temperature. Osmotically pre-treating the material resulted in reduced shrinkage, as well as drying with product temperature controlled, due to lower drying times needed that led to shorter high temperature exposition. Moisture dependence of apparent density was highly non-linear and could be fitted by an empirical model. Fresh sample rehydration indexes were higher than osmosed ones and increased with increasing temperature, except for pre-treated samples dried at 70 degreesC, probably due to superficial sugar caramelization, which reduced surface water permeability.

Influência da granulometria de grânulos de amido sobre a densidade aparente de extratos atomizados

Daiuto, Érica Regina; Cereda, M. P.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 51-56
POR
Relevância na Pesquisa
46.11%
Starches and modified starch derivations are used as carriers in the spray drying processing where apparent density is an important characteristic and should be controlled in dehydrated products for pharmaceutical use. In Brazil, the commercial starches are made from corn and cassava, but there are others with potential for extraction. The canna and taro starches were selected because they represent the extremes of granule size and thus allow the effect of this size on the apparent density of spray dried products to be tested. For comparison, commercial cassava and corn starches which are used in spray-drying and have granules of intermediate size, were also tested. The spray-drying process was carried out with a LabPlant SD 04 Spray Dryer, operating at a pressure of 6 lb/in2, air of 7,6 mL/minute, and 1 cm atomizing nozzle. The air inlet temperature was set at 200°C this model does not allow regulating outlet temperature. The spray-dryer products had boldo leaf extract as base, using the four starches as carrier. The dry product was evaluated for humidity, water activity (Aw), granulometry and apparent density. The results showed that the size of the particles, which was a consequence of the size of the starch granules, influenced the apparent density of the spray dried products...

Conversion between basic density and apparent density at any moisture content in Eucalyptus grandis

Costa, Vladimir Eliodoro; Rezende, Marcos Antonio de; Rodrigues, Valdemir Antonio
Fonte: Walter De Gruyter Gmbh Publicador: Walter De Gruyter Gmbh
Tipo: Artigo de Revista Científica Formato: 981-986
ENG
Relevância na Pesquisa
66.05%
Wood basic density (BD) is related to other wood characteristics and its determination is important in forest inventory, though BD must be differentiated from the apparent density (AD), which relates to the moisture content (MC) of wood. The aim of this study is to demonstrate a reliable conversion from BD to AD for any MC of Eucalyptus grandis wood based on two exponential and linear models that relate volumetric shrinkage to MC. To this end, wood specimens were submitted to drying and the volumetric shrinkage was determined as a function of MC. The two models proved to be efficient in the conversion of BD to AD and vice versa.

Variation in the apparent density of human mandibular bone with age and dental status

KINGSMILL, V. J. ; BOYDE, A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1998 EN
Relevância na Pesquisa
46.12%
This study examines the variability in the anatomy of mandibles of differing ages and different stages of tooth loss. Mandibles from individuals between 19 and 96 y were sectioned into 2 mm thick vertical plane-parallel slices and cleaned of marrow and periosteum. The apparent density (mass per unit volume in g/ml) from midline (MID) and mental foramen region (MF) sites was determined by weighing the slices and dividing by a volume calculated as the product of section thickness and the mean area of the 2 sides of the section. The cortical thickness of the inferior border and the basal and alveolar bone heights were measured in radiographs of the slices. Mandibular apparent density was negatively correlated with the cross sectional area (midline r=−0.48, mental foramen r=−0.45), and at the midline was significantly greater in edentulous than in dentate individuals (means (± s.e.m.) edentulous n=13: 1.43 (±0.07) g/ml; dentate n=17: 1.27 (±0.04) g/ml, P<0.05). Where a large enough age range was available, mandibular apparent bone density showed a significant increase with age (midline males: r=0.53, n=18) especially for dentate individuals (r=0.91, n=8). There was a correlation between the apparent densities at the two sites in the same mandible (r=0.64)...

Apparent density patterns in subchondral bone of the sloth and anteater forelimb

Patel, Biren A; Carlson, Kristian J
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.13%
Vertebrate morphologists often are interested in inferring limb-loading patterns in animals characterized by different locomotor repertoires. Because bone apparent density (i.e. mass per unit volume of bone inclusive of porosities) is a determinant of compressive strength, and thus indicative of compressive loading, recent comparative studies in primates have proposed a structure–function relationship between apparent density of subchondral bone and locomotor behaviours that vary in compressive loading. If such patterns are found in other mammals, then these relationships would be strengthened further. Here, we examine the distal radius of suspensory sloths that generally load their forelimbs (FLs) in tension and of quadrupedal anteaters that generally load their FLs in compression. Computed tomography osteoabsorptiometry was used to visualize the patterns in subchondral apparent density. Suspensory sloths exhibit relatively smaller areas of high apparent density than quadrupedal anteaters. This locomotor-based pattern is analogous to the pattern observed in suspensory and quadrupedal primates. Similarity between xenarthran and primate trends suggests broad-scale applicability for analysing subchondral bone apparent density and supports the idea that bone functionally alters its material properties in response to locomotor behaviours.

Elastic properties and apparent density of human edentulous maxilla and mandible

Seong, Wook-Jin; Kim, Uk-Kyu; Swift, James Q.; Heo, Young-Cheul; Hodges, James S.; Ko, Ching-Chang
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.04%
The aim of this study aim was to determine whether elastic properties and apparent density of bone differ in different anatomical regions of the maxilla and mandible. Additional analyses assessed how elastic properties and apparent density were related. Four pairs of edentulous maxilla and mandibles were retrieved from fresh human cadavers. Bone samples from four anatomical regions (maxillary anterior, maxillary posterior, mandibular anterior, mandibular posterior) were obtained. Elastic modulus (EM) and hardness (H) were measured using the nano-indentation technique. Bone samples containing cortical and trabecular bone were used to measure composite apparent density (cAD) using Archimedes’ principle. Statistical analyses used repeated measures ANOVA and Pearson correlations. Bone physical properties differed between regions of the maxilla and mandible. Generally, mandible had higher physical property measurements than maxilla. EM and H were higher in posterior than in anterior regions; the reverse was true for cAD. Posterior maxillary cAD was significantly lower than that in the three other regions.

Diurnal and seasonal trends in the apparent density of ambient fine and coarse particles in Los Angeles

Hasheminassab, Sina; Pakbin, Payam; Delfino, Ralph J.; Schauer, James J.; Sioutas, Constantinos
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.07%
Diurnal and seasonal variations in the apparent density of ambient fine and coarse particulate matter (PM2.5 and CPM [PM2.5-10], respectively) were investigated in a location near downtown Los Angeles. The apparent densities, determined by particle mass-to-volume ratios, showed strong diurnal and seasonal variations, with higher values during the warm phase (June to August 2013) compared to cold phase (November 2012 to February 2013). PM2.5 apparent density showed minima during the morning and afternoon rush hours of the cold phase (1.20 g cm−3), mainly due to the increased contribution of traffic-emitted soot particles, and highest values were found during the midday in the warm phase (2.38 g cm−3). The lowest CPM apparent density was observed during the morning rush hours of the cold phase (1.41 g cm−3), while highest in early afternoon during the warm phase (2.91 g cm−3), most likely due to the increased wind-induced resuspension of road dust.

Compressive axial mechanical properties of rat bone as functions of bone volume fraction, apparent density and micro-ct based mineral density

Cory, Esther; Nazarian, Ara; Entezari, Vahid; Vartanians, Vartan; Müller, Ralph; Snyder, Brian D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.95%
Mechanical testing has been regarded as the gold standard to investigate the effects of pathologies on the structure–function properties of the skeleton. With recent advances in computing power of personal computers, virtual alternatives to mechanical testing are gaining acceptance and use. We have previously introduced such a technique called structural rigidity analysis to assess mechanical strength of skeletal tissue with defects. The application of this technique is predicated upon the use of relationships defining the strength of bone as a function of its density for a given loading mode. We are to apply this technique in rat models to assess their compressive skeletal response subjected to a host of biological and pharmaceutical stimulations. Therefore, the aim of this study is to derive a relationship expressing axial compressive mechanical properties of rat cortical and cancellous bone as a function of equivalent bone mineral density, bone volume fraction or apparent density over a range of normal and pathologic bones.

Propriedades físicas da madeira de Araucaria angustifolia (Bert.) O. Kuntze em função da posição no fuste para diferentes idades; Physical properties of wood from Araucaria angustifolia (Bert.) O. Kuntze as a function of position in the stem at different ages

Fonte: UFLA - Universidade Federal de Lavras Publicador: UFLA - Universidade Federal de Lavras
Tipo: Artigo de Revista Científica Formato: text/html
PT
Relevância na Pesquisa
46.13%
The objective of this work was to study the physical properties of wood from Araucaria (Araucaria angustifolia). Parameters included apparent density and dimensional stability of trees at different ages and at different positions along the stem. Data were analyzed as a function of age and height along the tree stem, and then correlated with each other and with other dendrometric variables. A variation was observed in the apparent density between ages, yet it was not possible to determine a variation pattern. A variation was found in the apparent density along the stem, decreasing with increasing heights for all ages. Wood obtained from the lower portion of the stem was more unstable dimensionally. Linear equations are provided of the sum of radial and tangential shrinkage as a function of the apparent density. Equations reveal that more than 40% of the shrinkage was explained by the variation in apparent density.; Conduziu-se este trabalho, com o objetivo de estudar as propriedades físicas da madeira de Araucária (Araucaria angustifolia). Determinaram-se a massa específica aparente e a estabilidade dimensional de árvores de diferentes idades e em diferentes posições ao longo do fuste. A análise dos dados foi realizada em função da idade e da altura no fuste da árvore...

Variação radial e longitudinal da densidade aparente e estimativa de massa de Toona ciliata; Longitudinal and radial variation of apparent density and mass estimation of Toona ciliata

Silva, Tatiane Antunes da
Fonte: Universidade Federal de Lavras; Programa de Pós-Graduação em Ciência e Tecnologia da Madeira; UFLA; brasil; Departamento de Ciências Florestais Publicador: Universidade Federal de Lavras; Programa de Pós-Graduação em Ciência e Tecnologia da Madeira; UFLA; brasil; Departamento de Ciências Florestais
Tipo: Dissertação
Publicado em 22/12/2015 POR
Relevância na Pesquisa
66.17%
Australian Cedar (Toona ciliata), belongs to the Meliaceae family and has been cultivated in many Brazilian sites. When compared to natural forest species it has fast growth and has been used as an option to substitute native woods, such as mahogany (Swietenia macrophylla) and cedar (Cedrella odorata). The main purpose of this work was to evaluate the variation in apparent density and propose a model for stem mass estimation this study used trees with 52 months old, from plantation areas, in Campo Belo county, Minas Gerais state, Brazil. Two distinct progenies were chosen and had wood discs removed in the following positions from the tree base: 0.15 m, 0.70 m, 1.30 m and 30%, 50%, 70% and 85% of the total height. Wood samples from the disks were collected in order to conduct X-ray densitometry. The X-ray densitometry allowed us to know density variation from pit to bark and from base to top of trees. The density increases from pit to bark. From base to top of the tree, the density decreases up to DBH position and, after that, increases until the top of the tree. The estimated value for mean apparent density was 0.422 g/cm³. Based on the longitudinal variation of apparent density it was possible to propose a model for mass estimation. The model...

Analysis of wood density and shrinkage of Tectona grandis wood in axial and radial direction of the tree trunk; ANÁLISE DA MASSA ESPECÍFICA E DA RETRATIBILIDADE DA MADEIRA DE Tectona grandis NOS SENTIDOS AXIAL E RADIAL DO TRONCO

Bonduelle, Ghislaine Miranda; Universidade Federal do Paraná; Iwakiri, Setsuo; Universidade Federal do Paraná; Trianoski, Rosilani; Universidade Federal do Paraná; Prata, José Guilherme; Unviersidade Federal do Paraná; Rocha, Vinicius Yurk; Univesida
Fonte: FUPEF DO PARANÁ Publicador: FUPEF DO PARANÁ
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 29/03/2015 POR
Relevância na Pesquisa
36%
O objetivo deste trabalho foi avaliar a massa específica e a retratibilidade da madeira nos sentidos axial e radial do tronco. Foram coletadas cinco árvores com 18 anos, provenientes do município de Brasnorte, MT, as quais foram seccionadas nas posições da base, meio e topo, para avaliação das propriedades no sentido axial. Da parte diametral das toras foram obtidos pranchões onde foram controladas as posições radiais. A avaliação da massa específica e da retratibilidade da madeira seguiu as recomendações da norma panamericana. Os resultados demonstraram que a teca possui massa específica aparente a 12% de 0,606 g.cm-3, massa especifica básica de 0,524 g.cm-3 e fator anisotrópico de 2,271. Não foram observadas grandes variações de propriedades tanto no sentido axial quanto no radial. As propriedades físicas demonstram que a madeira possui média estabilidade dimensional, podendo ser indicada para aplicações em laminação, lambris, portas, decoração e movelaria. AbstractAnalysis of wood density and shrinkage of Tectona grandis wood in axial and radial direction of the tree trunk. This research aimed to evaluate density and shrinkage of wood in axial and radial directions of the tree. We collected five trees aged 18...

Relationship between particle size and manufacturing processing and sintered characteristics of iron powders

Sánchez,F.; Bolarín,A. M.; Molera,P.; Mendoza,J. E.; Ocampo,M.
Fonte: Universidad Simón Bolívar; ; Publicador: Universidad Simón Bolívar; ;
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 EN
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Abstract The effect of particle size distribution on physical properties of powder mixtures, of green compacts and of sintered samples has been studied. In the case of powder mixtures, the evaluated properties were flowability, apparent density, specific surface and compressibility. In green compacts porosity, roughness and green strength were evaluated, and in sintered samples grain size and transverse rupture strength were measured. In order to obtain samples with different average particle size, water atomized iron powders were sieved and separating it with sieves ranging from +44 to -150 m m. Flowability and compressibility decrease as average particle size does. On the opposite side, green strength and transverse rupture strength (TRS) increase as particle size diminishes. These effects were associated with changes in morphology and specific surface of the studied powder mixtures. Mathematical expressions relating average particle size with green strength, roughness and ultimate tensile strength were deduced from the experimental results. The results show that an appropriate selection of average particle size for the preparation of the powder mixture is useful in order to obtain samples with suitable physical properties.