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Cristina Prades - One of the best experts on this subject based on the ideXlab platform.

  • Application of VIS/NIR spectroscopy for estimating chemical, physical and mechanical properties of cork stoppers
    Wood Science and Technology, 2014
    Co-Authors: Cristina Prades, Florentino González-hernández, Isabel Gómez-sánchez, Juan García-olmo, J. R. Gonzalez-adrados
    Abstract:

    The aim of this study was to evaluate the potential of visible and near infrared spectroscopy (Vis/NIRS) in predicting the chemical, physical and mechanical behavior of single-piece natural corks stoppers used for sealing wine bottles. Two training sets of 90 and 150 cork stoppers were used to obtain four spectra per sample in different positions: two of the stopper bases (transversal Section) and two of the stopper sides (Tangential Section and radial Section). The samples were scanned in the range of 400–2,500 nm using a Foss-NIRSystems 6500 SY II spectrophotometer equipped with a remote reflectance fiber-optic probe. On each training set, two-thirds of the samples were used to develop modified partial least square (MPLS) calibration equations, and the remaining one-third of the sample for the external validation of these MPLS equations. The best equations were obtained for the transversal Section, which is the recommended one when applying Vis/NIRS technology to cork. The best results for the chemical composition were obtained for waxes and total polyphenols, showing coefficient of determination of the cross validation ( r _cv ^2 ) values of 0.64 and 0.56 and coefficient of determination of the external validation ( r _EV ^2 ) values of 0.53 and 0.55, respectively. The best equation for the physical and mechanical parameters was obtained for moisture content ( r _cv ^2  = 0.86 and r _EV ^2  = 0.85), with somewhat lower results for density, compression force and extraction force ( r _cv ^2  = 0.66, 0.72, 0.52 and r _EV ^2  = 0.52, 0.49, 0.51, respectively). The SECV (standard error of cross validation) and SEP (standard error of external validation) were similar for all the physical and mechanical parameters, thus confirming the robustness of the equations. MPLS model for moisture content fulfills the requirements for screening (RPD >2.5), but MPLS models obtained for waxes, total polyphenols, density, compression force and extraction force are not good enough for routine analysis or quality control. The results obtained from the MPLS models based on Vis/NIRS technology would permit the continuous quality control of humidity in the production line as well as obtaining information about certain chemical components (extractives contents) and some physical and mechanical parameters (density, extraction force and compression force).

  • application of vis nir spectroscopy for estimating chemical physical and mechanical properties of cork stoppers
    Wood Science and Technology, 2014
    Co-Authors: Cristina Prades, Florentino Gonzalezhernandez, Isabel Gomezsanchez, Juan Garciaolmo, J R Gonzalezadrados
    Abstract:

    The aim of this study was to evaluate the potential of visible and near infrared spectroscopy (Vis/NIRS) in predicting the chemical, physical and mechanical behavior of single-piece natural corks stoppers used for sealing wine bottles. Two training sets of 90 and 150 cork stoppers were used to obtain four spectra per sample in different positions: two of the stopper bases (transversal Section) and two of the stopper sides (Tangential Section and radial Section). The samples were scanned in the range of 400–2,500 nm using a Foss-NIRSystems 6500 SY II spectrophotometer equipped with a remote reflectance fiber-optic probe. On each training set, two-thirds of the samples were used to develop modified partial least square (MPLS) calibration equations, and the remaining one-third of the sample for the external validation of these MPLS equations. The best equations were obtained for the transversal Section, which is the recommended one when applying Vis/NIRS technology to cork. The best results for the chemical composition were obtained for waxes and total polyphenols, showing coefficient of determination of the cross validation (r cv 2 ) values of 0.64 and 0.56 and coefficient of determination of the external validation (r EV 2 ) values of 0.53 and 0.55, respectively. The best equation for the physical and mechanical parameters was obtained for moisture content (r cv 2 = 0.86 and r EV 2 = 0.85), with somewhat lower results for density, compression force and extraction force (r cv 2 = 0.66, 0.72, 0.52 and r EV 2 = 0.52, 0.49, 0.51, respectively). The SECV (standard error of cross validation) and SEP (standard error of external validation) were similar for all the physical and mechanical parameters, thus confirming the robustness of the equations. MPLS model for moisture content fulfills the requirements for screening (RPD >2.5), but MPLS models obtained for waxes, total polyphenols, density, compression force and extraction force are not good enough for routine analysis or quality control. The results obtained from the MPLS models based on Vis/NIRS technology would permit the continuous quality control of humidity in the production line as well as obtaining information about certain chemical components (extractives contents) and some physical and mechanical parameters (density, extraction force and compression force).

J. R. Gonzalez-adrados - One of the best experts on this subject based on the ideXlab platform.

  • Application of VIS/NIR spectroscopy for estimating chemical, physical and mechanical properties of cork stoppers
    Wood Science and Technology, 2014
    Co-Authors: Cristina Prades, Florentino González-hernández, Isabel Gómez-sánchez, Juan García-olmo, J. R. Gonzalez-adrados
    Abstract:

    The aim of this study was to evaluate the potential of visible and near infrared spectroscopy (Vis/NIRS) in predicting the chemical, physical and mechanical behavior of single-piece natural corks stoppers used for sealing wine bottles. Two training sets of 90 and 150 cork stoppers were used to obtain four spectra per sample in different positions: two of the stopper bases (transversal Section) and two of the stopper sides (Tangential Section and radial Section). The samples were scanned in the range of 400–2,500 nm using a Foss-NIRSystems 6500 SY II spectrophotometer equipped with a remote reflectance fiber-optic probe. On each training set, two-thirds of the samples were used to develop modified partial least square (MPLS) calibration equations, and the remaining one-third of the sample for the external validation of these MPLS equations. The best equations were obtained for the transversal Section, which is the recommended one when applying Vis/NIRS technology to cork. The best results for the chemical composition were obtained for waxes and total polyphenols, showing coefficient of determination of the cross validation ( r _cv ^2 ) values of 0.64 and 0.56 and coefficient of determination of the external validation ( r _EV ^2 ) values of 0.53 and 0.55, respectively. The best equation for the physical and mechanical parameters was obtained for moisture content ( r _cv ^2  = 0.86 and r _EV ^2  = 0.85), with somewhat lower results for density, compression force and extraction force ( r _cv ^2  = 0.66, 0.72, 0.52 and r _EV ^2  = 0.52, 0.49, 0.51, respectively). The SECV (standard error of cross validation) and SEP (standard error of external validation) were similar for all the physical and mechanical parameters, thus confirming the robustness of the equations. MPLS model for moisture content fulfills the requirements for screening (RPD >2.5), but MPLS models obtained for waxes, total polyphenols, density, compression force and extraction force are not good enough for routine analysis or quality control. The results obtained from the MPLS models based on Vis/NIRS technology would permit the continuous quality control of humidity in the production line as well as obtaining information about certain chemical components (extractives contents) and some physical and mechanical parameters (density, extraction force and compression force).

  • Quality grading of cork planks with classification models based on defect characterisation
    European Journal of Wood and Wood Products, 2000
    Co-Authors: J. R. Gonzalez-adrados, Fernando Lopes, Helena Pereira
    Abstract:

    (F.) and Crematogaster scutellaris Ol.). A discriminant analysis was used to construct the classification model: the variable with the highest discriminant power was the total porosity in the transverse Section, and the other variables were transformations of the specific width in the Tangential Section and the aspect ratio in the transverse Section. The model classified two thirds of the samples in accordance with the manual classification currently used in the industry and all cases of disagreement referred to changes between contiguous quality classes.

J R Gonzalezadrados - One of the best experts on this subject based on the ideXlab platform.

  • application of vis nir spectroscopy for estimating chemical physical and mechanical properties of cork stoppers
    Wood Science and Technology, 2014
    Co-Authors: Cristina Prades, Florentino Gonzalezhernandez, Isabel Gomezsanchez, Juan Garciaolmo, J R Gonzalezadrados
    Abstract:

    The aim of this study was to evaluate the potential of visible and near infrared spectroscopy (Vis/NIRS) in predicting the chemical, physical and mechanical behavior of single-piece natural corks stoppers used for sealing wine bottles. Two training sets of 90 and 150 cork stoppers were used to obtain four spectra per sample in different positions: two of the stopper bases (transversal Section) and two of the stopper sides (Tangential Section and radial Section). The samples were scanned in the range of 400–2,500 nm using a Foss-NIRSystems 6500 SY II spectrophotometer equipped with a remote reflectance fiber-optic probe. On each training set, two-thirds of the samples were used to develop modified partial least square (MPLS) calibration equations, and the remaining one-third of the sample for the external validation of these MPLS equations. The best equations were obtained for the transversal Section, which is the recommended one when applying Vis/NIRS technology to cork. The best results for the chemical composition were obtained for waxes and total polyphenols, showing coefficient of determination of the cross validation (r cv 2 ) values of 0.64 and 0.56 and coefficient of determination of the external validation (r EV 2 ) values of 0.53 and 0.55, respectively. The best equation for the physical and mechanical parameters was obtained for moisture content (r cv 2 = 0.86 and r EV 2 = 0.85), with somewhat lower results for density, compression force and extraction force (r cv 2 = 0.66, 0.72, 0.52 and r EV 2 = 0.52, 0.49, 0.51, respectively). The SECV (standard error of cross validation) and SEP (standard error of external validation) were similar for all the physical and mechanical parameters, thus confirming the robustness of the equations. MPLS model for moisture content fulfills the requirements for screening (RPD >2.5), but MPLS models obtained for waxes, total polyphenols, density, compression force and extraction force are not good enough for routine analysis or quality control. The results obtained from the MPLS models based on Vis/NIRS technology would permit the continuous quality control of humidity in the production line as well as obtaining information about certain chemical components (extractives contents) and some physical and mechanical parameters (density, extraction force and compression force).

Paul Blake - One of the best experts on this subject based on the ideXlab platform.

  • Early Carboniferous lignophyte tree diversity in Australia: Woods from the Drummond and Yarrol basins, Queensland
    Review of Palaeobotany and Palynology, 2019
    Co-Authors: Anne-laure Decombeix, Jean Galtier, Stephen Mcloughlin, Brigitte Meyer-berthaud, Gregory Webb, Paul Blake
    Abstract:

    Early Carboniferous (Mississippian) permineralized woods from Australia with multiseriate rays have been customarily assigned or compared to the European genus Pitus, despite the absence of information on their primary vascular anatomy. In the context of continuing work on the diversity of Late Devonian and Mississippian floras of Gondwana, we studied new silicified woods with secondary xylem similar to that of Pitus (multiseriate rays, araucarioid radial pitting) from two sedimentary basins of Queensland, Australia. In the Drummond Basin, three morphotypes of wood of Viséan age can be distinguished based on ray size in Tangential Section. Although this variation is similar to that observed between the various European species of Pitus, information on the primary vascular anatomy of the trees provided by three incomplete specimens excludes an affinity with Pitus for at least two taxa. In the Yarrol Basin, two well-preserved late Viséan trunks also have characters similar to Pitus but can be distinguished from that genus and other previously described Mississippian trees, in particular by the anatomy of their primary vascular system and departing leaf traces. They are assigned to a new genus, Ninsaria. Collectively, the new specimens from Queensland show that wood traditionally referred to “Pitus” from Australia actually belongs to several other types of trees that are not known from Europe or North America, indicating probable floristic provincialism between the Northern and Southern hemisphere floras at this time. These new fossils corroborate the existence of a global Mississippian diversification of (pro)gymnosperm trees already noted in Laurussia. They also indicate that the Mississippian floras of Australia were more diverse and complex than traditionally inferred.

Loïc Brancheriau - One of the best experts on this subject based on the ideXlab platform.

  • RADIAL VARIATION OF MICROFIBRIL ANGLE AND WOOD DENSITY AND THEIR RELATIONSHIPS IN 14-YEAR-OLD Eucalyptus urophylla S.T. BLAKE WOOD
    Bioresources, 2011
    Co-Authors: Paulo Ricardo Gherardi Hein, Loïc Brancheriau
    Abstract:

    The orientation of cellulose microfibrils in the cell wall along the stem axis has major effects on stiffness and longitudinal shrinkage and is of key importance in wood quality. The aim of this study was to investigate the radial variability of MFA and wood density (ρ) and their relationships in Eucalyptus urophylla wood. Three MFA values were estimated by X-ray diffraction at three points of each one of the 175 Tangential Sections, and the basic density was measured. A decrease of microfibril angles from pith to bark can be observed in most samples; however, some radial strips presented different patterns of variation. For basic density, a linear significant increase from pith to bark was confirmed. There was no significant correlation between microfibril angle and density. The relationships among the three MFA estimated on Tangential Sections of wood were strong. The “curvature effect” due to the growth rings had a negligible effect on the three measurements of Tangential Sections cut near to the pith. This study showed that a single T value measurement by X-ray diffraction, preferably at the centre of the Tangential Section, is precisely sufficient to estimate the mean MFA of Eucalyptus urophylla wood.

  • NIRS CAN PREDICT MICROFIBRIL ANGLE IN Eucalyptus WOOD EVEN USING SPECTRA FROM DIFFERENT WOOD FACES, AND SURFACE QUALITIES
    2010
    Co-Authors: Paulo Ricardo, Gherardi Hein, Bruno Clair, Loïc Brancheriau
    Abstract:

    The microfibril angle (MFA) of crystalline cellulose in the wood cell wall along the stem axis has major effects on stiffness and longitudinal shrinkage of wood and is of key importance to timber quality. The aims of this study were: (i) to develop partial least square (PLS) regression models for microfibril angle (measured on Tangential Sections by X- ray diffraction) based on NIR spectra measured on Tangential and on radial surfaces; ii) to develop PLS regression models for such wood trait based on radial NIR spectra collected from wood surfaces of different quality; and (iii) to verify the reliability of these PLS-R models by external validations. T values were recorded by X-ray diffraction on Tangential Section while NIR spectra were taken on Tangential and radial wood surfaces. PLS-R calibrations for MFA based on Tangential NIR spectra were better (R²p=0.72) than those using radial NIR spectra (R²p=0.64). The key role of the chemical components and the effect of surface quality of wood on NIRS calibrations are discussed. Considering the differences between experimental conditions, these findings showed the robustness of the NIR-based models for predicting MFA in Eucalyptus wood, even using spectra taken from different wood faces, and surface qualities.

  • Predicting microfibril angle in Eucalyptus wood from different wood faces and surface qualities using near infrared spectra
    Journal of Near Infrared Spectroscopy, 2010
    Co-Authors: Paulo Ricardo Gherardi Hein, Loïc Brancheriau, Bruno Clair, Gilles Chaix
    Abstract:

    The microfibril angle (MFA) of crystalline cellulose in the wood cell wall along the stem axis has major effects on stiffness and longitudinal shrinkage of wood and is of key importance to timber quality. The aims of this study were: (i) to develop partial least square (PLS) regression models for microfibril angle (measured on Tangential Sections by Xray diffraction) based on NIR spectra measured on Tangential and on radial surfaces; ii) to develop PLS regression models for such wood trait based on radial NIR spectra collected from wood surfaces of different quality; and (iii) to verify the reliability of these PLS-R models by external validations. T values were recorded by X-ray diffraction on Tangential Section while NIR spectra were taken on Tangential and radial wood surfaces. PLS-R calibrations for MFA based on Tangential NIR spectra were better (R²p=0.72) than those using radial NIR spectra (R²p=0.64). The key role of the chemical components and the effect of surface quality of wood on NIRS calibrations are discussed. Considering the differences between experimental conditions, these findings showed the robustness of the NIR-based models for predicting MFA in Eucalyptus wood, even using spectra taken from different wood faces, and surface qualities.