Mayara Elita Carneiro

Near infrared spectroscopy and chemometrics for predicting specific gravity and flexural modulus of elasticity of Pinus spp. veneers

In the plywood industry, the assessment of the flexural static modulus of elasticity (MOE) and specific gravity (SG) of veneers is important for quality control. The rapid assessment of these properties by near infrared (NIR) spectroscopy was examined using 312 Pinus spp solid wood veneers collected from a Brazilian plywood plant. Partial least squares (PLS) regression calibrations (based on 75% of the samples) for MOE and SG were obtained using all available wavelengths (PLS) and only statistically significant wavelengths [jack-knifing PLS (j-kPLS)]. Correlation coefficients (r) for the calibrations ranged from 0.80 to 0.83, while the ratios of performance to deviation ranged from 1.67 to 1.78. When applied to a separate test set (25% of the samples), statistics similar to those reported for the calibrations were obtained. For both MOE and SG, the j-kPLS calibrations performed marginally better than calibrations based on the full spectrum. The models constructed with only statistically significant wavelengths may be more robust as wavelength selection avoids any unnecessary information for the prediction of MOE and SG. This study demonstrates that NIR spectroscopy could potentially be used for in-line assessment of the MOE and SG of pine veneers.

Wood and charcoal identification of five species from the miscellaneous group known in Brazil as “Angelim” by Near-IR and wood anatomy

Samples of wood sold as “angelim” in Brazil were studied. Disks from the trunks of Diplotropis purpurea, Hymenolobium petraeum, Parkia pendula, Vatairea guianensis and Vatairea paraensis were obtained from Mato Grosso state. Samples from pith to bark of each species were obtained, oriented in the three anatomical planes. Each sample was wrapped in aluminum foil and carbonized in a muffle furnace, with a final temperature of 450 °C and a heating rate of 1,66 °C min-1. The description of the anatomical elements of wood and charcoal samples followed the orientations of the International Association of Wood Anatomists, on the basis of 25 readings regarding frequency and tangential diameter of the vessels and height and width of the rays in micrometers. Infrared analyses were performed with a Bruker Tensor 37 spectrophotometer equipped with an integrating sphere and operating in reflectance mode, with resolution of 4 cm-1 and a spectral range of 10000-4000 cm-1. The wood and charcoal samples were placed on top of integrating sphere and one spectrum was obtained from each surface, resulting in six spectra for each physical sample. The results of anatomical analysis showed that the qualitative characteristics of wood remained in charcoal, so the method can be applied for species discrimination. When comparing cell dimensions, we observed different behavior between species in the same carbonization process in function of cell wall thickness and parenchyma distribution. In infrared analysis, pretreatment influenced adequate discrimination of “angelim” species in wood and charcoal. Linear discriminant analysis based on PCA scores and the region between 4000-6200 cm-1 was more efficient. Near infrared analysis can be used for differentiation of wood and charcoal of “angelim” species.

Preparation and Characterization of Nano Silica from Equisetum arvenses

With the progress of nanotechnology and increase in demand, several silica processing industries have started producing silica nanoparticles. As a result, the search for new sources capable of producing this material has been attracting the interest of many researchers. With this background, a study was carried out to obtain silica nano particles from the Equisetum arvenses, a plant that possesses one of the highest amounts of silicon. This paper presents the preparation of nano silica particles with different combinations of acid washing and calcination at varying temperatures between 773 K and 873 K. The nanoparticles produced were characterized for nitrogen adsorption, morphology using transmission electron microscope and structural analysis by X-ray fluorescence and diffraction. It was found that nanoparticles produced by two cycles of acid washing and calcination at 773 K gave the best results, producing a material with white color, the highest specific surface area of about 330 m²/g with diameter of about 8 nm, and 93.5% of amorphous silica. The nanoparticles obtained can be potential industrial raw material for many applications.

Classificação de lâminas de madeira de Pinus spp. contaminadas por fungos manchadores

A busca por novas tecnologias que garantam a uniformidade da qualidade dos produtos tem se tornado constante, assim este trabalho teve como objetivo estudar a potencialidade de medidas espectroscopicas combinadas a ferramentas estatisticas para classificacao de lâminas de madeiras de Pinus spp. contaminadas por fungos manchadores. As amostras foram coletadas em processo industrial, e observou-se que algumas lâminas estavam contaminadas por fungos manchadores. Assim, utilizou-se este material para investigar a influencia dessa mancha azul em metodologias espectroscopicas e a possibilidade de discriminacao dessa contaminacao. Desse material contaminado foram capturados os espectros, na faixa de 400 a 1000 nm. Com esses dados, realizou-se uma analise exploratoria por Componentes Principais (PCA) e classificacao via SIMCA, em que se verificou a discriminacao eficiente em dois grupos, madeiras sadias e contaminadas. Observou-se que a tecnica de espectroscopia optica preenche os requisitos necessarios para uma possivel aplicacao na classificacao de lâminas no processo produtivo.

Fundamentos e estado da arte da espectroscopia no infravermelho próximo no setor de base florestal

O conhecimento das propriedades da madeira e de fundamental importância para indicacao dos potenciais de utilizacao final deste material. Na busca por novas alternativas para caracterizacao rapida, simples e confiavel, destacam-se as avaliacoes nao destrutivas da madeira. A espectroscopia no infravermelho proximo (NIRS) vem sendo utilizada como metodo nao destrutivo que permite obter informacoes qualitativas e quantitativas dos constituintes da biomassa atraves da interacao das ondas eletromagneticas do infravermelho proximo com a amostra. Este trabalho tem como objetivo fornecer uma revisao sobre a tecnica da espectroscopia no infravermelho proximo e sua aplicacao no setor florestal. A tecnica esta presente em praticamente todas as areas, devido ao nivel de desenvolvimento que esta tecnologia atingiu nos ultimos anos. A espectroscopia NIR tem se mostrado uma ferramenta rapida e eficiente para substituicao dos diversos ensaios que determinam a qualidade da madeira.

Potential use of visible and near-infrared spectroscopy for pine species discrimination by examination of needles

The correct identification of pine species is necessary for proper application of wood in forest‑based industries, since the quality of each species’ wood depends on factors intrinsic to the material. The aim of this study was to evaluate the potential use of near‑infrared and visible spectroscopy in the discrimination of pine species planted in southern Brazil. Needles of Pinus clausa, P. glabra, P. kesiya, P. oocarpa, P. palustris, P. pseudostrobus, P. rigida, P. roxburghii and P. serotina were collected from experimental plantations located in the region of Rio Negro, Paraná, Brazil. The needles were dried and milled for analysis. The evaluation was performed with a spectral range of 400–750 nm (visible) and 1 000–2 500 nm (near‑infrared). Analysis using the visible spectra resulted in two principal components explaining 95% of the variation between the needle samples. In the near‑infrared analysis, it was possible to discriminate between all nine pine species studied using only two principal components, where the first explained 99% of the variation between species. Spectroscopy based on needles can be used for pine species discrimination, using the original data without mathematical treatment, in southern Brazil.

NIR SPECTROSCOPY CAN EVALUATE THE CRYSTALLINITY AND THE TENSILE AND BURST STRENGTHS OF NANOCELLULOSIC FILMS

The near infrared (NIR) spectroscopy presents itself as an interesting non-destructive test tool as it enables a fast, simple and reliable way for characterizing large samplings of biological materials in a short period of time. This work aimed to establish multivariate models to estimate the crystallinity indices and tensile and burst strength of cellulosic and nanocellulosic films through NIR spectroscopy. NIR spectra were recorded from the films before tensile and bursting strength, and crystallinity tests. Spectral information were correlated with reference values obtained by laboratory procedures through partial least square regression (PLS-R). The PLS-R model for estimating the crystallinity index presented a coefficient of determination in cross-validation (R2cv) of 0,94 and the ratio of performance to deviation (RPD) was 3,77. The mechanical properties of the films presented a high correlation with the NIR spectra: R2p = 0,85 (RPD = 2,23) for tensile and R2p = 0,93 (RPD = 3,40) for burst strength. The statistics associated to the models presented have shown that the NIR spectroscopy has the potential to estimate the crystallinity index and resistance properties of cellulose and nanocellulose films on in-line monitoring systems.