Chemical and ultrastructural changes in compound middle lamella (CML) regions of softwoods thermally modified by the Termovuoto process

Silver fir and Norway spruce wood have been thermally modified (TMW) for 3-4 h at 160 degrees C, 180 degrees C, 200 degrees C, and 220 degrees C by means of the thermovacuum process (Termovuoto), and the ultrastructural and chemical changes in the compound middle lamella (CML), including the middle lamella cell corner (MLcc) regions (CMLcc), were investigated. Severe anatomical and histochemical changes were prominent above treatment temperatures of 200 degrees C; thus, woods treated at 220 degrees C for 4 h were in focus. Immunocytochemical studies showed that noncellulosic polysaccharides, such as pectin, xyloglucan, xylan, and mannan, were significantly degraded in CMLcc regions of TMWs. After treatment, the CMLcc regions were composed almost entirely of modified lignin with increased amounts of acidic groups. With cytochemical staining for lignin, many electron dense particulates were detected in the CMLcc regions of TMWs, indicating early degradation/alteration by the Termovuoto treatment

Nonsymmetrical drying tests—Experimental and numerical results for free and constrained spruce samples

International audienceThe paper brings new insights into nonsymmetrical convective drying, a configuration in whichstresses induce a global change of the section shape of a wooden board with five insulated faces.Two experimental devices that allow to test simultaneously “twin” wooden boards have beendeveloped: the first board is free and its curvature is collected vs. time; the second one isconstrained and the force required to keep it flat is collected vs. time. Convective drying tests havebeen performed on radial specimens of spruce, 5 and 15 mm thick at 45 and 65°C. The results arecommented and compared with simulation runs. For this purpose, a 1-D mechanical formulation isembedded in the computational code of heat and mass transfer TransPore. The objective of thecomparison between numerical and experimental results is a better understanding of the coupledphenomena and the identification of some transfer and mechanical parameters

Measurement of internal stress in Radiata pine sapwood during drying using an improved online sensor

Internal stress in wood as a result of kiln drying is an important factor that affects the quality of the final product. Internal stress is inherently difficult to measure and it is usually either assessed through destructive sample evaluation after drying, or is predictively modelled using extensive material property relations which require much effort to obtain. This study describes improvements of the design, accuracy, and precision of a previously constructed stress sensor for the direct measurement of internal stress in wood during drying. The sensor is designed to be placed directly into a wood block and it records online internal uniaxial stress. Lurethane® was found to be the best material for transmitting internal stress to the sensor because reduced creep was observed, compared with Teflon® which was originally used. Stress modelling showed that a linear relation could be theoretically obtained between the stress from the sensor and the actual primary axis stress that is likely to occur in an intact wood block. Accordingly, the response of a sensor placed in a certain area could be successfully calibrated. However, rotation of the sensor away from the primary stress axis caused a decrease in recorded stress but did not affect stress trends during drying, provided the angle remained constant. Finally, stress results from drying Pinus radiata D. Don at 70°C are also described and discussed

Thermo-Vacuum Modification of Teak Wood from Fast-Growth Plantation

Sawnwood of teak (Tectona grandis L. f.) from a Costa Rica plantation was thermally treated at different process conditions using thermo-vacuum technology. The main objectives of the study were to find the optimal combination of the process parameters, i.e. temperature (T), and duration (t), in order to minimise the colorimetric difference between sapwood and heartwood, and to evaluate the influence of the treatment on the modification pattern of physical properties of the material. The resulting mass loss (ML), hygroscopicity (H), dimensional stability (ASE), and lightness (L) were measured and compared. As expected, the temperature (T) is the main parameter influencing the extent of modification. The measured ML values turned out to be moderate even at high T values if compared with other hardwoods. The temperature range between 180 °C and 190 °C minimizes the colorimetric difference between treated sapwood and not treated heartwood

THERMO-VACUUM MODIFICATION OF SPRUCE (PICEA ABIES KARST.) AND FIR (ABIES ALBA MILL.) WOOD

The study presents results of the characterization of Norway spruce (Picea abies Karst.) and fir (Abies alba Mill.) wood thermally modified by TERMOVUOTO® technology at temperatures in the range of 160 to 220°C in vacuum conditions. Sixteen thermo-vacuum treatment tests were carried out using a pilot laboratory unit on 30-mm-thick spruce and fir boards in various combinations of the process parameters, i.e. temperature (T), duration (t), and pressure (p). The treated material was characterized to reveal the changes of the physical-mechanical properties including color and durability. The treated wood showed an improved performance with relation to the dimensional stability and durability. The measured mechanical properties did not show any significant decrease. Analytical models, based on the existing correlations between wood properties and process parameters, were assessed, thus allowing the control of the process

Molle all’altezza di cinque principesse Un approccio multidisciplinare al recupero di una problematica tavola dipinta del ‘500

Il dipinto, eseguito nel 1534, è un’opera di particolare rilievo delle collezioni museali del Castello del Buonconsiglio in Trento. Eseguita su un supporto ligneo molto sottile di tavole di pero, l’opera ha subito, nel corso dei secoli, vari interventi che ne hanno irrigidito la struttura provocando la formazione di fessurazioni delle tavole con conseguenti sollevamenti e cadute del colore. L’intervento di restauro [1]è stato condotto, fin dalla progettazione, accompagnando ogni fase con indagini di controllo e monitoraggio, con un’azione sinergica tra esperti di diverse discipline coinvolti a vario titolo nello studio dello stato conservativo e delle migliori soluzioni per il restauro dell’opera

Comparative Analysis of Volatile Organic Compound Purification Techniques in Complex Cooking Emissions: Adsorption, Photocatalysis and Combined Systems

Volatile organic compounds (VOCs) are molecules present in our everyday life, and they can be positive, such as in the formation of odour and food flavour, or harmful to the environment and humans, and research is focusing on limiting their emissions. Various methods have been used to achieve this purpose. Firstly, we review three main degradation methods: activated carbon, photocatalysis and a synergetic system. We provide a general overview of the operative conditions and report the possibility of VOC abatement during cooking. Within the literature, none of these systems has ever been tested in the presence of complex matrices, such as during cooking processes. The aim of this study is to compare the three methods in order to understand the behaviour of filter systems in the case of realistically complex gas mixtures. Proton transfer reaction–mass spectrometry (PTR-MS) has been used in the real-time monitoring of volatilome. Due to the fact that VOC emissions are highly dependent on the composition of the food cooked, we evaluated the degradation capacity of the three systems for different burger types (meat, greens, and fish). We demonstrate the pros and cons of photocatalysis and adsorption and how a combined approach can mitigate the drawbacks of photocatalysis

Dataset_Comparative Analysis of VOC Purification techinques in Complex Cooking Emissions: adsorption, photocatalysis and combined system

Dataset of the article "Comparative Analysis of VOC Purification techinques in Complex Cooking Emissions: adsorption, photocatalysis and combined system