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In order to assess the moisture content of wood chips on an industrial scale, readily applicable techniques are required. Thus, near infrared (NIR) spectroscopy was used to estimate moisture in wood chips by means of partial least squares regressions. NIR spectra were obtained in spectrometer with an integrating sphere and optical fiber probe, on the longitudinal and transverse surface of Eucalyptus wood chips. The specimens had their masses and NIR spectra measured in 10 steps during drying from saturated to anhydrous condition. Principal Component Analysis was performed to explore the effect of moisture of wood chip on NIR signatures. The values of moisture content of chips were associated with the respective NIR spectra by Partial Least Squares Regression (PLS-R) and Partial Least Squares Discriminant Analysis (PLS-DA) to estimate the moisture content of wood chips and its moisture classes, respectively. Model developed from spectra recorded on the longitudinal face by the integrating sphere method presented statistics slightly better (R²cv = 0,96; RMSEcv = 7,15%) than model based on optical fiber probe (R²cv = 0,90; RMSEcv = 11,86%). This study suggests that for calibration of robust predictive model for estimating moisture content in chips the spectra should be recorded on the longitudinal surface of wood using the integrating sphere acquisition method. [ABSTRACT FROM AUTHOR]

Terahertz imaging has the potential to identify and decipher portions of ancient manuscripts, which may be unreadable at infrared and visible wavelengths. We use a scanning confocal terahertz microscope to scan a medieval parchment with music notes and pentagrams written with different inks. The microscope is based on a continuous-wave solid-state source at 0.3 THz, emitting in the free space with a horn antenna, and a high numerical-aperture ellipsoidal reflector. We present terahertz images with diffraction-limited lateral resolution of approximately 0.5 mm, where the different inks all give similar high contrast. Symbols written on the 'verso' side of the parchment, barely glimpsed in the near-infrared photograph, leave a clear imprint in the terahertz images. Artifacts due to imperfect flatness of the parchment are also briefly discussed. [ABSTRACT FROM AUTHOR]

Rice straw pulps produced under different conditions were subject to near infrared (NIR) spectroscopy. At the same time, samples from those pulps were used to make handsheets, whose mechanical properties were measured. These values and those of brightness were successfully fitted to the pulping variables. Relating them to the NIR spectra, we found valid correlations for all parameters except the burst index, concluding that NIR spectroscopy could be used as an economical, timesaving and non-intrusive way to predict the mechanical strength of pulps before the paper sheet is made. [ABSTRACT FROM AUTHOR]

Abstract:This review article introduces recent technical and scientific reports on near-infrared (NIR) spectroscopy in the wood and paper industry, which have increased during the last decade. Many researchers have reported that the NIR technique is useful for detection of both chemical and physical properties of wood materials and has been widely used in cases where the characteristic cellular structure of the material is retained. With regard to application of NIR spectroscopy to pulp and paper, many publications have reported its potential as an on-line measurement technique during paper-making process control. NIR spectroscopy is considered fundamental in applied research on wood and paper. Utilization of NIR spectroscopy in the wood and paper industry should take into account its applicability and limitations as a nondestructive technique. [ABSTRACT FROM PUBLISHER]

Abstract: The application of diffuse reflectance UV–VIS–NIR spectroscopy is proposed to differentiate 20 office paper samples, which had been deemed similar by a preliminary visual examination under several different lighting sources. The samples were firstly screened on the basis of the qualitative appearance of their spectra. A further discrimination was obtained by taking into account three parameters: the average reflectivity of the paper samples in the range 680–900nm, and the integrated intensity of the absorption peak in the UV range at 272nm and at 360nm. The homogeneity of these parameters on both sides of the paper sheets was assessed, detecting a very uniform distribution of the optical brighteners. A special focus was posed on the determination of the discriminative power, in order to give a quantitative parameter on the proposed procedure, which is important when reporting results to the Court. The remarkable achievement of differentiating all the examined samples was obtained by UV–VIS spectroscopy, a very less expensive technique which is readily available in practically all forensic laboratories. [Copyright &y& Elsevier]

Abstract: An accurate characterisation of the organic dyes used in artworks, especially those made of paper, is an important factor in designing safe conservation treatments. In the case of synthetic organic dyes used in modern works of art, for example, one frequently encountered difficulty is that some of these dyes are not still commercially available. Recognizing this problem, the authors of this paper present the results of an analysis of UV–Vis–NIR fibre optic reflectance spectra of 82 samples of dyed paper prepared with 41 dyes. The samples come from a historic book, The Dyeing of Paper in the Pulp, which was published by Interessen-Gemeinschaft (I.G.) Farbenindustrie in 1925. The dyes used in the paper pulp belong to the azo compounds, acridine, anthraquinone, azine, diphenylmethane, indigoid, methine, nitro, quinoline, thiazine, triphenylmethane, sulphur and xanthene classes. [Copyright &y& Elsevier]

Abstract: The diffusion process of deuterated water (D2O) in washi (Japanese traditional paper) was investigated by means of a deuterium exchange method and Fourier-transform near-infrared (FT-NIR) transmission spectroscopy. The samples were the modern (AD 2003) hand-made washi and those from an archival collection of cultural artifacts (AD 1791 and 1615). Four absorption bands were identified in the NIR spectral range from 7200 to 6000cm−1 which are due to OH groups in the amorphous, semi-crystalline and two types of crystalline regions of cellulose. The accessibility of D2O increased with decreasing state of order of cellulose, and the saturation accessibility increased with the age of the samples. It was suggested that during aging hemicellulose, which forms a composite with cellulose in paper, was progressively hydrolyzed, resulting in the expansion of inter-molecular distance between cellulose chains. The oldest sample showed a low diffusion rate compared with the others. SEM observation of the textile structures indicated that the oldest sample had two layers due to beating. It was estimated that the tight surface layer blocked the diffusant in the initial stage of the diffusion process. [Copyright &y& Elsevier]

This review article introduces recent technical and scientific reports in terms of near infrared (NIR) spectroscopy in the wood and paper science and industry, where interest has increased during the last couple decades. Many researchers reported the NIR technique was useful to detect multi information in both chemical and physical properties of wood materials, although it was widely used in a state where characteristic cellular structure was retained. In the case of application of NIR spectroscopy to pulp and paper, many publications have pointed out its high probability as online measurement techniques during paper‐making process control. Arguments referred to the importance of NIR spectroscopy as fundamental and applied research of wood and paper. [ABSTRACT FROM AUTHOR]