Search results for "birch"
showing 10 items of 27 documents
Influence of Welding Time on Tensile-Shear Strength of Linear Friction Welded Birch (Betula pendula L.) Wood
2015
Linear friction welding of wood is a bonding process applied to wood and during which a stiff bond line is formed by the softening and rehardening of wood components to form a composite material composed mainly of wood fibres embedded in a modified lignin matrix. Unfortunately, the bonds tend to spontaneously delaminate or lose their strength when exposed to moist conditions. Some approaches were previously applied to overcome this problem, but so far a suitable solution has not been found. This paper presents results of applying post-welding thermal modification to reduce the moisture sensitivity of welded wood. The experiments included welding of birch wood, thermal modification under sup…
CHARACTERIZATION OF ANTIOXIDANT ACTIVITY AND TOTAL PHENOLIC COMPOUND CONTENT OF BIRCH OUTER BARK EXTRACTS USING MICRO PLATE ASSAY
2017
In modern plants, 2.7 to 2.8 m3 of solid volume veneer blocks are consumed to produce 1 m3 of plywood. After the hydrothermal treatment and debarking of blocks, waste bark is obtained, which makes up 12.5% of the wood mass, while 16-20% of bark is composed of birch outer bark (BOB). Recalculating, BOB makes up 2.0-3.4% of the veneer log mass. Bark is currently burned in boiler houses that is not rational. BOB contains large amount of valuable extractives (up to 34% from o.d. BOB) consisting of various secondary metabolites such as terpenes, flavonoids, hydrocarbons, polyphenols, tannins etc. BOB extractives exhibit antioxidant properties as well as wound-healing and anti-inflammatory activi…
Statistical modelling of non-stationary processes of atmospheric pollution from natural sources: example of birch pollen
2016
Abstract A statistical model for predicting daily mean pollen concentrations during the flowering season is constructed and its parameterization and application to birch pollen in Riga (Latvia) are discussed. The model involves several steps of transformations of both meteorological data and pollen observations, aiming at a normally distributed homogeneous stationary dataset with linearized dependencies between the transformed meteorological predictors and pollen concentrations. The data transformation includes normalization of daily mean birch pollen concentrations, a switch of the independent axis from time to heat sum, a projection of governing parameters to pollen concentrations, and a …
Characterization of pre-treatments on wood chips prior to delignification by near infrared spectroscopy
2017
A near infrared (NIR) spectroscopy-based method for predicting yields and lignin contents of differently pre-treated silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips was developed. The approach was to create multivariate calibration models from the NIR data by the partial least squares (PLS) method. Both parameters are important factors when adjusting adequate conditions for pre-treatments either with hot-water (HW) as such and slightly acidified HW (collectively referred to as autohydrolysis) or dilute alkaline aqueous solutions prior to alkaline pulping. Pre-treatment conditions were varied with respect to temperature (130 °C and 150 °C) and treatme…
Unravelling Radicals Reactivity Towards Carbon Nanotubes Manipulation/Functionalization
2016
Carbon Nanotubes (CNTs) chemistry is under constant evolution, as a consequence of the deep interest of the scientific community in finding new applications for these versatile materials. New and old synthetic protocols are used for improving the control of the functionalization degree of the final materials and for offering to scientists the possibility to fine-tune their final properties. In this Review, we focus the attention on radical reactions, a class of protocols characterized by small number of steps, different degrees of functionalization and enhanced solubility of the final modified CNTs, in the desired environment. The most well-known protocols are analysed providing some releva…
Airborne birch pollen in Poland and Latvia in the light of data obtained from aerobiological monitoring and tauber traps in relation to mean air temp…
2012
Birch pollen contains allergens belonging to those with the strongest allergenic properties. In order to trace pollen season patterns of this taxon and pollen annual sums at a wider regional scale, cooperation was established with the University of Latvia in Riga (Latvia). A comparison of the results obtained in the years 2003-2008 in Lublin and in Riga, using volumetric samplers, shows that there was a similar trend in the abundance of birch pollen. The highest sums were noted at both sites in 2003. In all the study years, more birch pollen grains were recorded in Lublin than in Riga, on the average by 7110. The birch pollen seasons started earlier in Lublin than in Riga, on the average by…
Reactivity of cellulose during hydrothermal carbonization of lignocellulosic biomass
2020
Abstract Hydrothermal carbonization (HTC) of pure cellulose (CE) and birchwood (BW) samples was carried out at temperatures between 160 and 280 °C, 0.5 h residence time and biomass-to-water ratio 1:5, to investigate the reactivity of cellulose in lignocellulosic biomass. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) showed that the CE samples remained unaltered at temperatures up to 220 °C, but were significantly decomposed at 230 °C producing a thermal recalcitrant aromatic and high energy-dense material. FTIR showed that dehydration and aromatization reactions occurred at temperature equal or higher than 230 °C for the CE samples while a similar incre…
Thermal conductivity measurement of insulating innovative building materials by hot plate and heat flow meter devices: A Round Robin Test
2019
Abstract The characterization of thermal insulation properties of construction materials represents a fundamental step on the building insulation assessment. In recent years innovative materials have been introduced in the market to fulfill the continuously growing requirements of energy saving and sustainability, and their performance is not so reliable and mature as it happens for traditional insulators. The work presents a Round Robin Test realised among six European laboratories hosting hot plates devices to measure the thermal conductivity of four different materials: aerogel, vacuum insulation panels, polystyrene and birch wood fibre insulation boards. After the definition of the comm…
Microbial community dynamics induced by rewetting dry soil: summer precipitation matters
2015
The massive soil CO2 efflux associated with rewetting dry soils after the dry summer period significantly contributes to the annual carbon budget of Mediterranean grasslands. Rapid reactivation of soil heterotrophic activity and available carbon are both required to fuel the CO2 pulse. Better understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting future changes in carbon cycling. We investigated the effects of a controlled rewetting event on the soil CO2 efflux pulse and on the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in intact soil cores previously s…
Wet-up response of the microbial community is shaped by soil dry-down patterns
2015
Background/Question/Methods The massive soil CO2 efflux associated with rewetting dry soils after the dry summer period significantly contributes to the annual carbon budget of Mediterranean grasslands. Rapid reactivation of soil heterotrophic activity and available carbon are both required to fuel the CO2 pulse. Better understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting future changes in carbon cycling. We investigated the effects of a controlled rewetting event on the soil CO2efflux pulse and on the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in int…