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A super‐black wood with low reflectivity in the UV/Vis range is created by plasma modifying basswood surfaces. Here the super‐black wood is characterized, the process used to make it is described and its possible practical uses are discussed. Wood samples are exposed to oxygen glow‐discharge plasma. Transverse surfaces exposed to high‐energy plasma have a deep‐black velvety appearance. The reflectance of these surfaces is measured and compared with those of commercial super‐black materials. The reflectivity of samples over a narrower wavelength range is measured with a spectrophotometer and converted into lightness values. The microstructure and surface chemistry of super‐black wood are examined using SEM/X‐ray micro‐CT and FTIR spectroscopy, respectively. Transverse basswood samples modified with high‐energy plasma have reflectivity averaging 0.68% (300–700 nm). The super‐black color of plasma‐modified wood is retained when it is coated with gold/vanadium alloy indicating structural coloration. Plasma creates a low density, lignin‐enriched surface with deep pits, columns and tangled fibrils; features also found in synthetic super‐black materials. In conclusion, this method of creating a super‐black material by plasma‐modification of basswood does not require a lithography pre‐step, generates no liquid waste and, as is demonstrated here, can be used to prototype luxury consumer products. [ABSTRACT FROM AUTHOR]

Basswood samples were exposed to oxygen glow-discharge plasmas for 30 min, and etching of radial and tangential longitudinal surfaces was measured. It was hypothesized that there would be a positive correlation between etching and plasma energy, and differential etching of wood surfaces because of variation in the microstructure and chemical composition of different woody tissues. Etching at the surface of basswood samples was examined using profilometry. Light and scanning electron microscopy were used to examine the microstructure of samples exposed to plasma. There was a large effect of plasma energy on etching of basswood surfaces, and radial surfaces were etched to a greater extent than tangential surfaces. However, rays at radial surfaces were more resistant to etching than fibers, resulting in greater variation in the etching of radial versus tangential surfaces. The same phenomenon occurred at radial surfaces of balsa wood, jelutong and New Zealand white pine subjected to plasma etching. The possible reasons for the greater resistance of rays to plasma etching are explored, and it is suggested that such differential etching of wood surfaces may impose a limitation on the use of plasma to precisely etch functional patterns at wood surfaces (raised pillars, grooves), as has been done with other materials. [ABSTRACT FROM AUTHOR]

Transparent wood is a modern bio-renewable material with great potential for both science and industrial applications. However, the fire hazard of transparent wood is still almost unexplored. This study aims to investigate the impact of pristine basswood modification to epoxy-based transparent wood on the fire hazard and to train neural networks for the prediction of heat release rate from mass loss rate of pristine basswood, epoxy-based transparent wood, and epoxy resin. Transparent wood was prepared by lignin modification in pristine small-leaved basswood (Tilia cordata Mill.) and subsequent vacuum infiltration by epoxy resin. The fire hazard of the samples was determined by the cone calorimeter at four heat fluxes of 20–50 kW m−2. The fire hazard of investigated materials was compared based on the critical heat flux, ignition temperature, heat release rate, effective heat of combustion and time to flashover. Transparent wood showed higher resistance to ignition (higher critical heat flux and ignition temperature) than pristine wood. However, other parameters (heat release rate and effective heat of combustion) were higher (worse) and the time to flashover was lower (worse) for transparent wood than for pristine wood. Trained neural networks for predicting heat release rate from the mass loss rate of wood (both pristine and transparent) and epoxy resin showed coefficients of determination from 0.70 to 0.92. Trained neural networks with a coefficient of determinations above 0.90 are usable for low-cost heat release rate measurements in both science and industrial applications. [ABSTRACT FROM AUTHOR]

Premise of research. Tree species typically have high levels of genetic and morphological variation that make the detection of species boundaries difficult. The genus Tilia in eastern North America and Mexico is known for its morphological variation and uncertain species boundaries. We summarized the extent of morphological variation in North American Tilia and assessed previously proposed two- and four-species classifications. Methodology. Samples were collected from 566 individual trees, and 12 morphological characters were measured or calculated. Descriptive statistics were generated range-wide and by morphospecies, geographic range, and chloroplast DNA (cpDNA) lineage. Correlations among morphological variables and with latitude and longitude were calculated. Principal coordinates analysis was performed to detect morphological clusters and their correspondence to defined subgroups. In addition, the degree of variation within individuals was assessed. Pivotal results. Morphology is highly variable across the range of Tilia. Morphological characters do not delineate the four morphospecies identified by past workers, supporting the lack of species boundaries within North American Tilia. Two cpDNA lineages, in Mexico and in the United States, also cannot be separated by any morphological character. Twig and leaf trichome density are moderately negatively correlated with latitude. There is a smaller degree of intraindividual morphological variation than expected. Conclusions. Morphological data do not provide support for the existence of two or four species of Tilia within North America. The high degree of morphological variation without distinct gaps in characters supports the recognition of a single species, Tilia americana s.l. [ABSTRACT FROM AUTHOR]

Aim The dominant role of Tilia in primeval forests of Scandinavia has long been recognized, but the timing and mechanisms for its decline have not been completely unravelled. A particular uncertainty involves the balance between climate and human activities as the drivers of the change. One reason for the uncertainty is the challenge in evaluating the past cover of the genus owing to its poorly dispersed pollen; another is that a multi-site study would be required to trace subregional differences. To overcome these obstacles, we here apply two different analytical methods to pollen data from 42 sites in two distinct vegetation zones of Sweden. Location Temperate and hemi-boreal vegetation zones of southern Sweden. Methods Generalized additive mixed models (GAMM) were used to model the development of Tilia and cereal pollen percentages over time. Twelve sites were used for reconstruction of local cover of Tilia using the landscape reconstruction algorithm (LRA). Results Before 4000 cal. bp the Tilia mean pollen percentages were similar in the two vegetation zones. Thereafter, values in the hemi-boreal zone declined, with less Tilia since around 3000 cal. bp. In contrast, Tilia did not decrease in the temperate zone until this past millennium. The LRA application revealed that in some forests a large cover of Tilia remained considerably longer than has traditionally been estimated by pollen percentages alone. Main conclusions By using a large coherent dataset we found significant differences in how the abundance and distribution of Tilia changed through time between two adjacent vegetation zones. We interpret the initial decline in the northern hemi-boreal zone to be driven by cooling climate, and the later decline in the southern temperate zone to be driven more by human land-use. [ABSTRACT FROM AUTHOR]

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This article discusses a mathematical model depicting pretreatment methods used to homogenize the biomass from which ethanol is derived for fuel purposes. Acid hydrolysis data from single hardwood tree species were combined and used as the basis for this model. The predictions relating to the hydrolysis of woody biomass species with a dilute acid were tested. While the hardwoods tested did not show any synergistic qualities hydrolysis, neither did they display any significant differences in that process. This hydrolysis produces a five carbon sugar known as xylose for fermentation.

Optically transparent wood is a type of composite material, combining wood as a renewable resource with the optical and mechanical properties of synthetic polymers. During this study, the effect of monochromatic UV-C (λ—250 nm) radiation on transparent wood was evaluated. Samples of basswood were treated using a lignin modification method, to preserve most of the lignin, and subsequently impregnated with refractive-index-matched types of acrylic polymers (methyl methacrylate, 2-hydroxyethyl methacrylate). Optical (transmittance, colour) and mechanical (shore D hardness) properties were measured to describe the degradation process over 35 days. The transmittance of the samples was significantly decreased during the first seven days (12% EMA, 15% MMA). The average lightness of both materials decreased by 10% (EMA) and 17% (MMA), and the colour shifted towards a red and yellow area of CIE L*a*b* space coordinates. The influence of UV-C radiation on the hardness of the samples was statistically insignificant (W+MMA 84.98 ± 2.05; W+EMA 84.89 ± 2.46), therefore the hardness mainly depends on the hardness of used acrylic polymer. The obtained results can be used to assess the effect of disinfection of transparent wood surfaces with UV-C radiation (e.g., due to inactivation of SARS-CoV-2 virus) on the change of its aesthetic and mechanical properties. [ABSTRACT FROM AUTHOR]