We are building the Schenberg gravitational wave detector at the Physics Institute of the University of São Paulo as programmed by the Brazilian Graviton Project. The antenna and its vibration isolation system are already built, and we have made a first cryogenic run for an overall test, in which we measured the antenna mechanical Q (figure of merit). We also have built a 10.21 GHz oscillator with phase noise performance better than −120 dBc at 3.2 kHz to pump an initial CuAl6% two-mode transducer. We plan to prepare this spherical antenna for a first operational run at 4.2 K with a single transducer and an initial target sensitivity of h ∼ 2 × 10−21 Hz−1/2 in a 50 Hz bandwidth around 3.2 kHz soon. Here we present details of this plan and some recent results of the development of this project.
Interest in cellulose nanocrystals obtained from natural resources has grown mainly because of features that such materials provide when inserted into polymeric matrices. The present study aimed to evaluate the effect of cellulose nanocrystals addition on mechanical properties of biofilms made from hypromellose (or hydroxypropyl methylcellulose - HPMC) and cassava starch blends (CS). The cellulose nanocrystals were produced by acid hydrolysis and characterized by optical microscopy (OM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetry (TG). Films were made with pure CS, pure hypromellose and also with blends of CS and hypromellose by casting. Then cellulose nanocrystals were added to the blends in the concentrations of 1, 3 and 10% (m/m). Evaluations of the films included tensile performance and fracture surface by scanning electron microscopy (SEM). It was observed that the reinforcement with nanocrystals improved the mechanical properties of the films, and their fracture surface showed that cellulose nanocrystals promoted an improvement in the cohesion of the hypromellose and starch molecules in the blend, and created a more homogeneous surface.
The effect of planting density on the anatomical characteristics of wood is still matter of debate. The aim of the study was to investigate the influence of planting density on the variation of wood anatomical elements in Eucalyptus and Acacia trees cultivated in areas of high planting density (monospecific) and low planting density (mixed) stands. The fiber length, fiber width, fiber lumen diameter, cell wall thickness, vessel diameter and vessel frequency were evaluated. The measurements were made from wood discs taken from five Eucalyptus urophylla x E. grandis trees and five Acacia mangium trees grown in high planting density (monospecific plantations, 1667 trees/ha) and in low planting density (mixed stands, 500 trees/ha), totalizing 20 trees at 4.5 years old. Eucalyptus and Acacia produced wood with shorter fibers and smaller vessels in high density stands, when compared to its equivalent in low density. Acacia presented more frequent vessels and fibers with walls thicker than its equivalent in low planting density. Eucalyptus presented longer and thinner fibers and vessels more frequent than Acacia, regardless of planting density. On the other hand, in high planting density, Acacia presented fibers with walls thicker than Eucalyptus and in low density of planting their vessels were larger.
Esse trabalho teve como objetivo delimitar a idade de transição entre o lenho juvenil e o adulto de Eucalyptus pilularis, Eucalyptus saligna, Eucalyptus cloeziana e Corymbia maculata com 37 anos de idade, a partir da análise das variações no sentido medula-casca do comprimento das fibras e do ângulo microfibrilar. Duas árvores de cada espécie foram selecionadas, abatidas e tiveram discos cortados na base do tronco. Amostras foram retiradas do disco no sentido medula-casca para a determinação do ângulo das microfibrilas e do comprimento das fibras. O E. saligna apresentou o maior comprimento médio das fibras e a menor média do ângulo microfibrilar. As idades de transição estimadas pela análise da variação do comprimento das fibras foram menores do que aquelas estimadas pela análise da variação do ângulo microfibrilar. A análise de regressão linear response plateau permitiu estimar o ponto em que ocorre a estabilização do comprimento das fibras e do ângulo microfibrilar para as espécies avaliadas.
A escassez de informações sobre as características das madeiras de mogno africano e de sua trabalhabilidade limitam sua utilização e introdução no mercado madeireiro. Os objetivos foram avaliar a qualidade da superfície usinada e comparar o consumo de energia específica de corte entre as espécies das madeiras de Khaya ivorensis e Khaya senegalensis com diferentes padrões de usinagem. Para avaliar a qualidade da superfície usinada, foi utilizada uma desempenadeira com rotações de 2400, 3600 e 4000 min-1 e velocidade de avanço de 6 e 15 m*min-1. A qualidade da superfície foi avaliada por meio do avanço por dente (fz), avaliação visual e rugosidade. Cortes longitudinais e transversais foram realizados por serra circular com rotações de 2500, 3000 e 3500 min-1 para obtenção da energia de corte específica, por meio de um inversor de frequência. A espécie K. senegalensis apresentou consumo de energia de corte 10% superior a K. ivorensis, já no corte transversal houve maior consumo de 36% da K. senegalensis. Pela qualificação visual as melhores superfícies usinadas foram provenientes da velocidade de avanço de 6 m*min-1. A rugosidade não variou em função dos diferentes parâmetros de usinagem e nem entre as duas espécies.
b A new method for the rapid identification of cellulose derivatives in molding mixtures or commercial goods is described. Cellulose acetate, cellulose acetate-butyrate, cellulose nitrate, methylcellulose, ethylcellulose, hydroxyethylcellulose, c a r~o x y m e~~y l c~~~u l o s e , and cellulose were investigated. All except methyl-and hydroxyethylcellulose, which react similarly in all tests, can be distinguished easily.No special reagents or eqwiprnent are required and the meihod can be applied to the ~~~e~~~l~ as received without the need for prior purification. The method is rapi chromatography required for the identification of the acetate grsu independentiy of any other graup can be done in about 2 hours.
Background:The aim of this study was to investigate near infrared (NIR) spectroscopy ability to estimate nanofibril concentration, physical and mechanical properties of Kraft paper reinforced with cellulose nanofibrils (CNF). For this purpose, paper sheets were prepared by mixing unbleached Eucalyptus fibers and cellulose nanofibrils. Twelve treatments result from the combination of the nominal grammages 75, 85, 95 and 105 g m -2 with the nanofibril concentrations of 1, 5 and 10wt%, with 7 sheets per treatment. NIR spectra measured directly on paper specimens were correlated with physical and mechanical properties values obtained through conventional laboratory analyzes.Results: Principal component analysis (PCA) revealed no separation among specimens related to nanofibril content. Partial least squares regression (PLS-R) models for estimating nanofibril content, tensile index, stretch and resistance to air passage yielded R²cv ranging from 0.73 to 0.98. Partial least squares -discriminant analysis (PLS-DA) correctly classified up to 93% of the paper specimens both by grammage and nanofibril content using NIR spectra. Conclusion:This approach appears to be suitable for predicting physical and mechanical properties of Kraft papers and can detect cellulose nanofibril content in the cellulose handsheets.
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