Permeability changes in heartwood of Picea abies and Abies alba induced by incubation with Physisporinus vitreus

The present study shows that isolates of P. vitreus have an extraordinary capacity to induce substantial permeability changes in heartwood of P. abies without causing significant losses in impact bending strength. The degradation of pit membranes by P. vitreus is an important aspect that could also have significant benefits in wood protection processes. Further studies are currently in progress with the objective of optimising the uniformity of wood colonisation and duration of incubation, so as to improve the permeability of water-borne wood preservatives or hydrophobic substances applied by brushing, dipping and impregnatio

Antimicrobial efficacy of silver nanoparticles in transparent wood coatings

Results on the antimicrobial efficacy of silver nanoparticles in transparent wood coatings for outdoor application are presented. The performance of different hydrophobic, transparent coating systems with and without silver was studied during 2years of natural weathering. In addition, laboratory efficacy tests were carried out on non-weathered and weathered specimens to assess the resistance of the coatings against mold, blue stain and algae. The protective effect of the tested silver containing coatings against common microorganisms was insufficient, even under initial, non-weathered conditions. Reasons for the failure are the inadequate initial silver concentrations below 50ppm in the coatings and the associated insufficient availability of free silver ions on the coating surface

Brominated Flame Retardants – Endocrine-Disrupting Chemicals in the Swiss Environment

Brominated flame retardants (BFR) are additives used to protect plastic materials and textiles against ignition. As some widely used BFR have chemical structures similar to well known endocrine disruptors such as polychlorinated biphenyls (PCB) or bisphenol A, adverse effects were also presumed for BFR. When the NRP50 programme started in 2001, the sparse knowledge on environmental behavior and toxicology of BFR did not allow a proper assessment of the risks associated with the widespread use of these chemicals. Therefore, we proposed to address questions such as the exposure of animals and humans, temporal trends in the environment as well as transformation and transport processes of BFR. Concentrations of BFR in wildlife and humans in Switzerland today pose no serious concerns for negative health effects according to the current knowledge on the toxicity of BFR. However, negative health effects cannot be ruled out in the future, since some BFR persist in the environment and their concentrations in freshwater lake sediments are increasing rapidly. The development of environmentally safe alternatives to these chemicals will be an important issue for the future

Influence of moisture on the vibro-mechanical properties of bio-engineered wood

In this study, changes in the vibro-mechanical properties of fungi-treated wood, during sorption and desorption at different humidity levels, were investigated. Norway spruce resonance wood (with uniform narrow annual rings and high tonal quality for musical instrument craftsmanship) was incubated with Physisporinus vitreus for 36weeks. Stiffness, internal friction, and tonal performance indices of control (untreated) and fungi-treated wood were compared after exposure to a stepwise variation of relative humidity. It was demonstrated that fungal treatment increased the internal friction and decreased the specific modulus of elasticity, during reduction of wood density. Internal friction of both control and fungi-treated wood significantly increased during dynamic sorption, especially during early stages (hours) of each humidity change step. Both specific modulus of elasticity and internal friction showed a hysteretic behavior during humidity variation cycles. Hysteresis was smaller in fungi-treated wood. Also, tonal performance indices were improved after fungal treatment and showed a reduced variation at different relative humidity conditions. Dynamic vapor sorption tests and FT-IR microscopy studies revealed changes in hygroscopicity and the supramolecular structure of wood, which may explain the observed vibrational behavior. Less dependency of wood vibrational properties to the variation of the ambient humidity is important for the acoustic performance of string instruments

L'educació creadora

Aquest treball està basat en un projecte d'investigació envers l'expressió lliure, a partir dels conceptes que ens proporciona l'educació creadora. El seu objectiu principal és donar a conèixer aquesta visió per tal d'afavorir la reflexió i el plantejament d'altres vies educatives. Per a fer-ho, he assistit a conferències, formacions i tallers que sustenten l'àmbit més teòric. En relació a la part empírica del treball, he realitzat un projecte en comú amb la facultat de comunicació audiovisual, el qual es desenvolupa a partir d'un documental que representa el resultat final de la recerca

Influence of incubation time on the vibration and mechanic properties of mycowood

The goal of the current study was to investigate the physical and mechanical properties of mycowood as a high quality tone-wood, obtained from Norway spruce by treatment of the white rot fungus Physisporinus vitreus as a function of the treatment time. In focus was the stiffness to weight ratio, which is often considered a main criterion for tone-wood selection. The vibro-mechanical properties were tested by non-destructive methods. The change of color and density were also measured after 4-12 months of fungal incubation. Density decreased up to 5% after 12 months of fungal treatment. Sound velocity was measured in small size specimens by means of the free-free vibration approach, while in large specimens the air-coupled ultrasound method was applied. The two techniques gave similar results and indicated that the sound velocity decreased in mycowood. Internal damping was increased in mycowood to a higher extent than the reduction in the specific modulus of elasticity (E/ρ) and thus the sound velocity in the material. The sound velocity was decreasing with increasing incubation times and scattering of data with this regard was larger in the transversal than in the longitudinal direction. The sound radiation coefficient and the characteristic impedance were enhanced in mycowood and its color was more brownish and richer in tone

Evolution of chlorinated paraffin and olefin fingerprints in sewage sludge from 1993 to 2020 of a Swiss municipal wastewater treatment plant

Exposure of humans to chlorinated paraffins (CPs) and chlorinated olefins (COs) can occur via contact with CP-containing plastic materials. Such plastic materials can contain short-chain CPs (SCCPs), which are regulated as persistent organic pollutants (POPs) under the Stockholm Convention since 2017. Municipal wastewater treatment plants (WWTP) collect effluents of thousands of households and their sludge is a marker for CP exposure. We investigated digested sewage sludge collected in the years 1993, 2002, 2007, 2012, and 2020 from a Swiss WWTP serving between 20000 and 23000 inhabitants. A liquid chromatography mass spectrometry (R > 100000) method, in combination with an atmospheric pressure chemical ionization source (LC-APCI-MS), was used to detect mass spectra of CPs and olefinic side products. A R-based automated spectra evaluation routine (RASER) was applied to search for ∼23000 ions whereof ∼6000 ions could be assigned to CPs, chlorinated mono- (COs), di- (CdiOs) and tri-olefins (CtriOs). Up to 230 CP-, 120 CO-, 50 CdiO- and 20 CtriO-homologues could be identified in sludge. Characteristic fingerprints were deduced describing C- and Cl-homologue distributions, chlorine- (nCl) and carbon- (nC) numbers of CPs and COs. In addition, proportions of saturated and unsaturated material were determined together with proportions of different chain length classes including short- (SC), medium- (MC), long- (LC) and very long-chain (vLC) material. A substantial reduction of SCCPs of 84% was observed from 1993 to 2020. Respective levels of MCCPs, LCCPs and vLCCPs decreased by 61, 69 and 58%. These trends confirm that banned SCCPs and non-regulated CPs are present in WWTP sludge and higher-chlorinated SCCPs were replaced by lower chlorinated MCCPs. Combining high-resolution mass spectrometry with a selective and fast data evaluation method can produce characteristic fingerprints of sewage sludge describing the long-term trends in a WWTP catchment area

Influence of moisture on the vibro-mechanical properties of bio-engineered wood

In this study, changes in the vibro-mechanical properties of fungi-treated wood, during sorption and desorption at different humidity levels, were investigated. Norway spruce resonance wood (with uniform narrow annual rings and high tonal quality for musical instrument craftsmanship) was incubated with Physisporinus vitreus for 36 weeks. Stiffness, internal friction, and tonal performance indices of control (untreated) and fungi-treated wood were compared after exposure to a stepwise variation of relative humidity. It was demonstrated that fungal treatment increased the internal friction and decreased the specific modulus of elasticity, during reduction of wood density. Internal friction of both control and fungi-treated wood significantly increased during dynamic sorption, especially during early stages (hours) of each humidity change step. Both specific modulus of elasticity and internal friction showed a hysteretic behavior during humidity variation cycles. Hysteresis was smaller in fungi-treated wood. Also, tonal performance indices were improved after fungal treatment and showed a reduced variation at different relative humidity conditions. Dynamic vapor sorption tests and FT-IR microscopy studies revealed changes in hygroscopicity and the supramolecular structure of wood, which may explain the observed vibrational behavior. Less dependency of wood vibrational properties to the variation of the ambient humidity is important for the acoustic performance of string instruments.ISSN:0022-2461ISSN:1573-480