Ten Essential Oils for Beech Wood Protection - Efficacy Against Wood-destroying Fungi and Moulds, and Effect on Wood Discoloration
This work analyses the anti-fungal efficacy and stability of 10 essential oils, as well as their colour stability, in wood. The efficacy of oils against the decay fungi Coniophora puteana and Trametes versicolor as well as the moulds Aspergillus niger and Penicillium brevicompactum was evaluated first on filter papers treated with 1, 3.5, 10%, or 100% concentrate, and then on beech wood treated with 10% solutions. Accelerated ageing of treated beech samples was done before mycological tests and consisted of heating, leaching followed by heating, and Xenotest followed by heating. The highest growth inhibition of moulds and C. puteana was caused by thyme, oregano, sweet flag, and clove oils, while the savory and birch oils were less effective. These oils are potentially useful for wood protection against brown-rot fungi and moulds, mostly in interior conditions. The essential oils had only a negligible effect against the white-rot fungus T. versicolor, which was more apparent after previous ageing of wood. Some essential oils with a yellow tone (birch, oregano, sweet flag, savory, and tea tree oils) significantly changed (p<0.05) the natural colour of beech wood, but the new colours were relatively stable and underwent only mild changes after accelerated ageing in Xenotest.
Activity prediction of Schiff base compounds using improved QSAR models of cinnamaldehyde analogues and derivatives
In past work, QSAR (quantitative structure-activity relationship) models of cinnamaldehyde analogues and derivatives (CADs) have been used to predict the activities of new chemicals based on their mass concentrations, but these approaches are not without shortcomings. Therefore, molar concentrations were used instead of mass concentrations to determine antifungal activity. New QSAR models of CADs against Aspergillus niger and Penicillium citrinum were established, and the molecular design of new CADs was performed. The antifungal properties of the designed CADs were tested, and the experimental Log AR values were in agreement with the predicted Log AR values. The results indicate that the improved QSAR models are more reliable and can be effectively used for CADs molecular design and prediction of the activity of CADs. These findings provide new insight into the development and utilization of cinnamaldehyde compounds.
Glycidyl‐Methacrylate‐Based Electrospun Mats and Catalytic Silver Nanoparticles
P(AN-GMA) and PGMA fibers coated with monodisperse silver nanoparticles have been prepared by a combination of electrospinning and electroless plating. The morphology of the electrospun fibers remains unchanged after surface hydrazination. Oxidation of hydrazine in an ammoniacal solution of AgNO 3 reduces and deposits silver atoms along the fiber surface, which then coalesce to Ag particles. The size of the silver nanoparticles is varied between 20-60 nm. Since the density of the active sites for silver reduction is lower in P(AN-GMA), a smaller particle size could be obtained. The catalytic activity of the silver nanoparticles has been confirmed.