Dimensionamento de revestimentos definitivos em túneis de adução

Tese de mestrado integrado. Engenharia Civil. Área de Especialização de Estruturas. Faculdade de Engenharia. Universidade do Porto. 201

Caracterização estrutural da lignina da parede celular de Euterpe oleracea

This paper aimed to characterize the lignin in the cell wall of Euterpe oleracea Mart. Samples from two regions of the base of the palm were acquired: outer and inner regions (OR and IR, respectively). The extraction with organic solvents and the treatment with 1% NaOH were carried out. Holocellulose, α-cellulose and lignin content were quantified, the latter also isolated by the Björkman method for the structural characterization using 1H and 13C NMR in the liquid state, as well as spectroscopic (FTIR) and chromatographic analysis. The extracted stem had 10.33% (OR) and 15.66% (IR) of the lignin. After the treatment with 1% NaOH, a reduction in these values was observed, and it was also possible to confirm this result through the decrease in the intensities of the signals referring to the functional groups linked to lignin and hemicellulose. The spectroscopic and chromatographic analyzes revealed GS-type lignin incorporated with p-hydroxybenzoic and protocatechuic acid in both samples. The main structural units present in the lignin were also observed, such as β-O-4 bond, β-O-4’ ϒ-acetyl bond, guaiacyl unit, syringyl unit and p-hydroxybenzoate.Este trabalho teve como objetivo caracterizar a lignina na parede celular de Euterpe oleracea Mart. Foram adquiridas amostras de duas regiões da base da palmeira: região externa e região interna (OR e IR, respectivamente). A extração com solventes orgânicos e o tratamento com NaOH 1% foram realizados. O conteúdo de holocelulose, α-celulose e lignina foi quantificado, esta última também isolada pelo método de Björkman para a caracterização estrutural utilizando RMN de 1H e 13C no estado líquido, assim como análises espectroscópicas (FTIR) e cromatográficas. O caule extraído apresentou 10,33% (OR) e 15,66% (IR) de lignina. Após tratamento com NaOH 1%, observou-se uma redução desses valores, e foi possível confirmar esse resultado também através da diminuição nas intensidades dos sinais referentes aos grupos funcionais ligados à lignina e hemicelulose. As análises espectroscópicas e cromatográficas revelaram lignina do tipo GS incorporada com ácido p-hidroxibenzoico e protocatecuico em ambas as amostras. Também foram observadas as principais unidades estruturais presentes na lignina como ligação β-O-4, β-O-4’ ϒ-acetiladas, spiro-dienona, unidade guaiacila, unidade siringila e p-hidroxibenzoato

AGRUPAMENTO RADIAL DE TÁBUAS DE Eucalyptus grandis SUBMETIDAS AO PROCESSO DE SECAGEM CONVENCIONAL

O gênero Eucalyptus sp. apresenta defeitos naturais, de desdobro e secagem que acarretam perdas significativas de madeira. Por isso, conhecer a região de ocorrência dos defeitos pode ser uma ferramenta útil para quem beneficia madeira. Sendo assim, este trabalho objetivou agrupar radialmente tábuas de Eucalyptus grandis com base nos defeitos naturais e de secagem. Seis árvores foram desdobradas em tábuas e separadas em duas regiões: central (C) e externa (E). As tábuas centrais (C) apresentavam maior proporção de madeira da região próxima à medula; e as externas (E), maior proporção de madeira da região próxima à casca. Os defeitos ocorridos nas tábuas secas em estufa convencional, a 10 % de umidade foram avaliados por meio de análise multivariada e variaram no sentido medula-casca. A análise de agrupamento separou a madeira em duas regiões (central e externa) e a análise de componentes principais destacou quais defeitos foram dominantes para cada região. As tábuas externas (E) apresentram maior intensidade de encurvanento e encanoamento. As centrais (C) apresentaram maior intensidade de arqueamento, nós, bolsas de resina ou kino, colapso e rachaduras superficiais. Essas informações podem ser importantes para quem industrializa madeira, pois, sabendo em qual região o defeito mais ocorre, uma peça de madeira pode deixar de ser utilizada. No entanto, o fator operacional deve ser levado em consideração, pois características da madeira, o tipo e condições do equipamento de corte, método de desdobro, layout da serraria, pode inviabilizar a separação da tora em duas regiões.The Eucalyptus sp. genus presents natural debarking and drying defects that lead to significant wood losses. For this reason, knowing the region where the defects occur may be a useful tool for those who process wood. Thus, this work aimed to radially group Eucalyptus grandis boards based on natural and drying defects. Six trees were split into boards and separated into two regions: central (C) and external (E). The central boards (C) had a higher proportion of wood from the region near the pith; and the external boards (E) had a higher proportion of wood from the region near the bark. The defects occurring in the boards dried in conventional kiln at 10% humidity were evaluated using multivariate analysis and varied in the pith-to-bark direction. The Cluster analysis separated the wood into two regions (central and external) and the principal components analysis highlighted which defects were dominant for each region. The external boards (E) presented higher bow and cupped  intensity. The central boards (C) presented higher crook intensity, knots, gum or kino bags, collapse, and superficial cracks. This information may be important for those who industrialize wood, because by knowing in which region the defect most occurs, a piece of wood may no longer be used. However, the operational factor should be taken into account, because wood characteristics, the type and conditions of the cutting equipment, pitsawing method, and sawmill layout may make it unfeasible to separate the log into two regions

PHYSICAL-MECHANICAL WOOD PROPERTIES FROM INVASIVE EXOTIC SPECIES OF ATLANTIC FOREST

Invasive exotic tree species cause several problems to the world biota. Removing these trees is important for restoring ecosystem balance. However, after the removal, there is a concern regarding the proper destination of the generated materials. The lack of knowledge about the wood characteristics makes it difficult to recommend for the most appropriate uses, which leads to a low added value of the product. The aim of the study was to assess the physical and mechanical wood properties and indicate the alternatives for using wood from exotic invasive species at the Fiocruz Mata Atlântica Biological Station, Rio de Janeiro - RJ. The three species studied were Artocarpus heterophyllus Lamarck (Jackfruit), Syzygium cumini (L.) Skeels (Java plum) and Clitoria fairchildiana R.A. Howard (Sombreiro). The physical and mechanical wood properties were determined in three distinct regions, denominated central, intermediate and external, ranging from pith-bark direction. The wood of Artocarpus heterophyllus had low basic density, retractions were lower in the central region, and the intermediate region had the highest mechanical resistance. The Syzygium cumini wood had medium density, the mechanical properties increased in the pith-bark direction, and the radial and volumetric retractions were lower in the central region. Clitoria fairchildiana wood had medium density and had the lowest mechanical resistance from the species evaluated. The three species have appropriate physical properties for the furniture sector, and the Syzygium cumini wood presented adequate mechanical resistance for civil construction

Yttria/ceria stabilized zirconia composites: evaluation of microstructural, mechanical and color properties for biomedical applications

[Excerpt] 3-mol% Yttria-Stabilized Tetragonal Zirconia Polycrystal (3Y-TZP), a ceramic biomaterial, has been widely used in the dentistry field due to its biocompatibility, tooth-like color and mechanical properties [1]. Despite these advantages, its physical and mechanical properties tend to degrade as a result of a low-temperature aging process induced by its sensitivity to low-temperature degradation (LTD) when it is in contact with water that is already at human body temperature [2]. Because of this, many studies have been performed aiming at avoiding this phenomenon by replacing 3Y-TZP by 12 mol% ceria stabilized tetragonal zirconia polycrystal (12Ce-TZP). Nevertheless, compared to 3Y-TZP, 12Ce-TZP has lower strength which is partly related to its larger grain size [3]. [...]This work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020. Additionally, this work was also supported by FCT through the grant SFRH/BD/146324/2019

Study of the relationship between the degree of tinnitus annoyance the presence of hyperacusis✩✩Please cite this article as: Guimarães AC, Carvalho GM, Voltolini MM, Zappelini CE, Mezzalira R, Stoler G, et al. Study of the relationship between the degree of tinnitus annoyance and the presence of hyperacusis. Braz J Otorhinolaryngol. 2014;80:24-8.

AbstractIntroductionHyperacusis can be defined as a manifestation of an increased of central auditory pathways gain and can be considered a pre-tinnitus state. In some cases tinnitus can be caused by such increased gain.AimTo evaluate the prevalence of hyperacusis in patients with tinnitus and its relation to the annoyance of tinnitus.Materials and methodsRetrospective study with patients from the neurotology service complaining of tinnitus in the first consultation were submitted to clinical evaluation, a questionnaire and audiological evaluation of tinnitus and hyperacusis. The degree of annoyance of tinnitus and hyperacusis was measured using a visual analog scale.ResultsWe analyzed medical records of 309 patients, 169 (54.7%) females and 140 (45.3%) males. The mean age was 53 years. The median degree of tinnitus annoyance was 7. Hyperacusis was present in 57 (18.4%) patients, with a median degree of 5. The degree of annoyance due to tinnitus patients with hyperacusis was similar to that of patients without hyperacusis.ConclusionHyperacusis was present in 18.4% of patients with tinnitus. The degree of annoyance due to tinnitus had no correlation with the presence of hyperacusis.© 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved

INFLUENCE OF VAPORIZATION AND IMPREGNATION OF SILVER NANOPARTICLES ON THE DRYING RATE OF Eucalyptus pellita F. MUELL.

The aim of this study was to evaluate the effect of vaporization and impregnation of silver nanoparticles on the Eucalyptus pellita wood properties. For that, samples of three radial regions of the wood from three trees were vaporized for 12 and 24 hours and later on, they were immersed in solution of silver nanoparticles with and without application of vacuum (750 mm.Hg). Anatomical, physical and chemical analyzes of the wood were carried out in order to evaluate the effect of the treatments. The drying rate of the wood was determined in moisture bands before and after the fiber saturation point. Generally, the treatments did not modify the anatomical characteristics, permeability, and wood density in the three radial regions; however, the vaporization for 24h reduced the total extractive content in the wood. These results contributed in obtaining gains in the drying rate before and after the fiber saturation point. The effect of impregnation of nanoparticles with vacuum preceded by two periods of vaporization resulted in higher drying rates and the time of 24h stood out, resulting in the best averages among all treatments. The impregnation of nanoparticles had positive effects on the drying rate