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Compression wood has undesirable properties for structural timber and for paper production. Traditional methods of detecting it are often time consuming and subjective. This study aimed to rapidly and impartially detect compression wood through the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and diffuse reflectance near infrared (NIR) spectroscopy. Compression wood and non-compression wood samples were obtained from young Pinus radiata D. Don trees grown in New Zealand. Longitudinal dimensional changes were measured during drying or water saturation of the samples; lignin and galactose contents were determined using conventional analytical techniques. Chemical composition was here a more reliable discriminator between wood types than longitudinal dimensional changes. It was shown that partial least-squares regression (PLS-R) or discriminatory analysis (PLS-DA) could be used to build models on the training samples that could discriminate between wood types of the independently grown validation samples. Ultimately, both types of spectroscopies could be used to discriminate between compression wood and non-compression wood either through prediction or discriminatory analysis with equal success. Investigation into spectral differences between wood types, including sequential mixtures of wood types, showed that for the mid-IR region absorbance at a well-resolved lignin band could be used to discriminate compression wood from non-compression wood. For NIR, a similar investigation showed that absorbance values at four separate wavenumbers or the 6000-5600 [cm.sup.-1] region of the first derivative spectra were required for that discrimination. It is proposed that if there is a gradual change in the chemical composition of compression wood with its severity, then IR spectroscopy could feasibly be used to rapidly determine compression wood severity. Key words: compression wood, NIR, ATR-FTIR, Pinus radiata, lignin. Certaines proprietes du bois de compression le rendent indesirable pour le bois de charpente et la production de papier. En general, les methodes traditionnelles de detection prennent du temps et sont subjectives. Cette etude vise a detecter rapidement et objectivement le bois de compression au moyen de la spectroscopie infrarouge a transformee de Fourier par reflectance totale attenuee (IRTF-RTA) et de la spectroscopie dans le proche infrarouge (PIR) par reflectance diffuse. Des echantillons de bois de compression et de bois normal ont ete obtenus a partir de tiges de Pinus radiata D. Don croissant en Nouvelle-Zelande. Les variations dimensionnelles dans le sens longitudinal ont ete mesurees durant le sechage ou la saturation en humidite des echantillons; les teneurs en lignine et en galactose ont ete determinees en ayant recours aux techniques analytiques conventionnelles. La composition chimique permettait ici de distinguer de facon plus fiable les types de bois que les variations dimensionnelles dans le sens longitudinal. Il a ete demontre que la regression ou l'analyse discriminante par les moindres carres partiels pouvaient etre utilisees pour construire des modeles en utilisant les echantillons d'entrainement et que ces modeles pouvaient distinguer les differents types de bois des echantillons de validation cultives de facon independante. Ultimement, les deux types de spectroscopie pourraient etre utilises avec autant de succes pour distinguer le bois de compression du bois normal via l'analyse previsionnelle ou discriminante. L'etude des differences spectrales entre les differents types de bois, incluant des melanges sequentiels de types de bois, a montre que l'absorbance dans l'IR moyen d'une bande bien definie correspondant a la lignine pouvait etre utilisee pour distinguer le bois de compression du bois normal. Dans le cas du PIR, une etude similaire a montre que les valeurs d'absorbance a quatre longueurs d'onde differentes, ou la region comprise entre 6000 et 5600 [cm.sup.-1] des spectres en derivee premiere, etaient necessaires pour faire cette distinction. Si la composition chimique du bois de compression evolue graduellement avec la severite, il serait alors possible d'utiliser la spectroscopie IR pour determiner rapidement la severite du bois de compression. [Traduit par la Redaction] Mots-cles : bois de compression, PIR, IRTF-RTA, Pinus radiata, lignine., Introduction Compression wood is formed by gymnosperm (softwood) trees as a reaction to an external environmental stress (or stresses) (e.g., wind, snow, or weight overhang) that forces the stem or [...]

Rapid, simple microchannel prototyping is critical for the development of modern microfluidic devices and platforms. Laser cutting (ablation) using a commercially available continuous wave (CW) CO2 laser followed by thermal bonding is one of the most common approaches for prototyping in thermoplastics such as polymethyl methacrylate (PMMA). However, this technique suffers from poorly controlled channel quality, inconsistent results from solvent-based post-processing, and inconsistency of thermal bonding. We have overcome these challenges through a systematic study of channel ablation in PMMA using a CW CO2 laser. A new solvent treatment approach results in clearly improved microchannel quality and processing consistency, with negligible residual solvent. Thermal bonding of the processed material showed fourfold increase in bonding strength with full retention of PMMA's favourable optical clarity. As proof of concept, a high-quality three-layered microfluidic prototype is fabricated with this new method and its performance demonstrated. [ABSTRACT FROM AUTHOR]