Vinicius Resende de Castro

VARIAÇÃO DA RETRATIBILIDADE DA MADEIRA DE Eucalyptus grandis Hill ex. Maiden, EM FUNÇÃO DA IDADE E DA POSIÇÃO RADIAL NO TRONCO 1

The objective of this work was to study the linear and volumetric shrinkage variation of the Eucalyptus grandis wood, along the radial plane at four different ages (10, 14, 20 and 25 years), from commercial stands. The samples were removed from the diametrical board of each of the sixteen trees (four from each age), taken from four equidistant positions (0, 33, 66 and 100%), in the pith -bark direction. The species, as a whole, showed a high dimensional stability, with mean values of volumetric shrinkage of 18.11% and radial, tangential and longitudinal shrinkage of 6.09%, 10.44% and 0.45%, respectively; and tangential/ radial ratio of 1.71. Except for the longitudinal shrinkage and the tangential/radial ratio, all of the parameters showed a tendency to increase with age and radial direction, from pith-to-bark.

EFEITO DA DISPONIBILIDADE HÍDRICA E DA APLICAÇÃO DE POTÁSSIO E SÓDIO NAS CARACTERÍSTICAS ANATÔMICAS DO LENHO JUVENIL DE Eucalyptus grandis

A disponibilidade de agua e de fertilizantes em povoamentos florestais promove estimulos na atividade do meristema cambial das arvores, causando significativas alteracoes nas caracteristicas anatomicas e na formacao do lenho. O estudo teve como objetivo avaliar as caracteristicas anatomicas do lenho de arvores de Eucalyptus grandis com 24 e 36 meses de idade submetidas a reducao das chuvas e a nutricao de K e Na. Os tratamentos foram definidos por dois regimes hidricos (100% e 66% das chuvas, com reducao artificial com lonas de polietileno) e tres tipos de nutricao: K (4,5 kmol/ha), Na (4,5 kmol/ha) e controle. Foram selecionadas tres arvores por tratamento e por idade, totalizando 36 arvores amostradas, sendo seccionados Discos de lenho a 1,3 m de altura (DAP) para a avaliacao das caracteristicas anatomicas. Os resultados indicaram que os tratamentos de nutricao x disponibilidade hidrica induziram alteracoes na largura total, diâmetro do lume e espessura da parede da fibra aos 24 meses e nao alteraram as dimensoes dos vasos no lenho do E. grandis. A aplicacao isolada do K e do Na nao influenciou as caracteristicas anatomicas do lenho, exceto para a largura, diâmetro do lume e espessura da parede da fibra aos 24 meses. A reducao dos niveis de precipitacao, pela instalacao de faixas de lonas de polietileno, nao influenciou significativamente as dimensoes das fibras e dos vasos no lenho das arvores de eucalipto. Os resultados poderao ser utilizados como subsidios para a adocao de praticas silviculturais nas plantacoes florestais em areas com estresse hidrico, bem como a substituicao parcial de K por Na.

EFEITO DA APLICAÇÃO DO POTÁSSIO, DO SÓDIO E DA DISPONIBILIDADE HÍDRICA NA DENSIDADE APARENTE A 12% DE UMIDADE DO LENHO JUVENIL DE ÁRVORES DE Eucalyptus grandis

Expressive area of forest plantations fast-growing of eucalyptus in Brazil and in other regions of the world is under the influence of climate change, water stress and low soil fertility, affecting the growth and the quality of the wood from the trees. This study aimed to evaluate the apparent density at 12% relative humidity of the wood of Eucalyptus grandis trees with 12, 24 and 36 months, with reduced rainfall and nutrition K and Na. The treatments were defined by two water regimes (100% and 66% of rainfall, with artificial reduction with polyethylene sheeting) and three types of nutrition: K (K - 4.5 kmol/ha), N (Na - 4.5 kmol/ha) and control. The apparent density of the samples of diameter at breast height was determined by densitometry profile from digital images of rays X. The results indicated a significant difference in nutrition treatments and water availability in relation to the density of the wood. The radial apparent density profiles showed higher differences in the wood from the third year of evaluation. Digital images of the wood obtained by X-rays allowed to analyze the variation of the apparent density of the wood. Work results may be used as subsidies for the adoption of silvicultural practices in forest plantations in areas with water stress and/or affected by climate change as well as the partial replacement of K by Na.

Roth Spots in Ocular Toxoplasmosis

Abstract Purpose: To report a case with unilateral preexisting ocular toxoplasmosis (OT) and newly occurred active retinochoroidal inflammation associated with white-centered retinal hemorrhages (Roth spots) in the healthy eye. Design: Case report. Methods: A 20 year-old man presented with a decrease of visual acuity in his right eye associated with 2+ cells in the anterior chamber. Ophthalmoscopy revealed an active retinochoroidal lesion on the upper nasal border of the optic disc associated with local hemorrhage and vitritis. The posterior pole presented white-centered flame-shaped retinal hemorrhages. Results: Toxoplasmosis serology showed an IgG titer >300IU/ml and a negative IgM titer. A complete blood count revealed no abnormalities; other serologies were negative. After 2 weeks of treatment with sulfadiazine, pyrimethamine, folinic acid and prednisone, although the peripapillary lesion was still active, the Roth spots disappeared. Conclusion: OT may be one differential diagnosis of patients suffering Roth spots in association with retinochoroidal inflammation.

Relação entre perfil de densidade e ligação interna de painéis OSB de Pinus spp

This study aimed to determine the density, by gravimetric method and X-ray densitometry, of Oriented Strand Boards (OSB) produced with Pinus taeda and Pinus elliottii var. elliottii x Pinus caribaea var. hondurensis, to obtain densitometric profiles and observe their correlation with the internal bond. The average density of the panels produced was determined by the methodology of X-ray densitometry and the gravimetric method, using 3 specimens (50 × 50 mm) per treatment. After apparent density measurement, the 24 specimens were subjected to the internal bond test. The gravimetric method applied for the determination of apparent density of the panels presented significantly higher results compared with the densitometric method. It was possible to observe that the minimum density of the board, obtained by the method of X-ray densitometry, has a strong influence on its average density. Correlation was observed between the apparent densities of the panels and the results of internal bond.

Relação entre Perfil de Densidade e Ligação Interna de Painéis OSB de Pinus spp / Relationship between Density Profile and Internal Bond of Pinus spp. OSB panels

This study aimed to determine the density, by gravimetric method and X-ray densitometry, of Oriented Strand Boards (OSB) produced with Pinus taeda and Pinus elliottii var. elliottii x Pinus caribaea var. hondurensis, to obtain densitometric profiles and observe their correlation with the internal bond. The average density of the panels produced was determined by the methodology of X-ray densitometry and the gravimetric method, using 3 specimens (50 × 50 mm) per treatment. After apparent density measurement, the 24 specimens were subjected to the internal bond test. The gravimetric method applied for the determination of apparent density of the panels presented significantly higher results compared with the densitometric method. It was possible to observe that the minimum density of the board, obtained by the method of X-ray densitometry, has a strong influence on its average density. Correlation was observed between the apparent densities of the panels and the results of internal bond.