▶ Impact of large ungulates on tree stands essential to make management decisions. ▶ Use of novel DNA-based method to analyse diet of herbivores. ▶ Habitat and supplementary feeding influence ...European bison diet. ▶ Proportion of woody material in bison diet increase with decreasing supplementary feeding. ▶ Browsed by bison tree species has low importance for forest management.
Large herbivores are keystone species in many forest areas, as they shape the structure, species diversity and functioning of those ecosystems. The European bison
Bison bonasus has been successfully restored after extinction in the wild at the beginning of 20th century. As free-ranging populations of the species were re-established mainly in forest habitats, knowledge of the impact by the largest European terrestrial mammal on tree stands is essential. This helps to make management and conservation decisions for viable population maintenance of the species in the wild. Using a novel DNA-based method of herbivore diet analysis, the
trnL approach (DNA-barcoding), we investigated the influence of different foraging conditions (access to supplementary fodder) on bison diet in winter and its potential impact on woody species. Faecal samples were collected from different bison treatment groups: (1) intensively fed; (2) less intensively fed; (3) non-fed utilising forest habitats; and (4) non-fed utilising agricultural areas surrounding the Forest. These were analysed to estimate the proportion of different plant groups consumed by bison. Bison groups differed significantly in their diet. The amount of woody materials (trees and shrubs) consumed by bison increased with decreasing access to supplementary fodder, ranging from 16% in intensively fed bison to 65% in non-fed bison utilising forest habitats. Inversely, the amount of herbs, grasses and sedges decreased from 82% in intensively fed bison to 32% in non fed bison utilising forest habitats. The species of trees mainly browsed by bison,
Carpinus/
Corylus,
Betula sp. and
Salix sp., were of lower economic importance for forest management. The impact of bison on tree species needs further investigation, however, we can predict that browsing by bison, mainly on
Carpinus/
Corylus, makes an insignificant impact on forestry due to the high and increasing representation of this species in the forest understory. Supplementary feeding has several negative effects on bison ecology and health, therefore reduced and distributed supplementary feeding should be applied as the management practice in the Białowieża Forest.
Blue phase liquid crystals (BPLCs) are chiral mesophases with 3D order, which makes them a promising template for doping nanoparticles (NPs), yielding tunable nanomaterials attractive for microlasers ...and numerous microsensor applications. However, doping NPs to BPLCs causes BP lattice extension, which translates to elongation of operating wavelengths of light reflection. Here, it is demonstrated that small (2.4 nm diameter) achiral gold (Au) NPs decorated with designed LC-like ligands can enhance the chiral twist of BPLCs (i.e., reduce cell size of the single BP unit up to ∼14% and ∼7% for BPI and BPII, respectively), translating to a blue-shift of Bragg reflection. Doping NPs also significantly increases the thermal stability of BPs from 5.5 °C (for undoped BPLC) up to 22.8 °C (for doped BPLC). In line with our expectations, both effects are saturated, and their magnitude depends on the concentration of investigated nanodopants as well the BP phase type. Our research highlights the critical role of functionalization of Au NPs on the phase sequence of BPLCs. We show that inappropriate selection of surface ligands can destabilize BPs. Our BPLC and Au NPs are photochemically stable and exhibit great miscibility, preventing NP aggregation in the BPLC matrix over the long term. We believe that our findings will improve the fabrication of advanced nanomaterials into 3D periodic soft photonic structures.
This paper presents the results of experimental studies and numerical simulations of the ratcheting for the PA6 aluminum. In the initial determination of the material hardening parameters, the ...samples were subjected to the symmetrical strain-controlled cyclic tension-compression test. The experimental stress-strain curve was compared with the numerical one obtained for non-linear Frederick-Armstrong and Voce models. For better fitting of both curves, the optimization procedure based on the least-square method and the fuzzy logic was applied. After establishing the hardening parameters, numerical simulations of the ratcheting were made. The boundary value problem was solved by means of discrete analysis. The data (force and displacement) obtained in numerical computations were used to control the ratchetting experiment. The results of experiments and numerical calculations were compared. Good convergence proves the reliability of the determination of material hardening data.
The results of experimental and numerical tests of a single corrugated sheet silo column’s buckling resistance are presented in this study. The experiments were performed in a real silo with and ...without bulk solid (wheat). A very positive impact of the bulk solid on the column buckling resistance occurred. The experimental results were first compared to the buckling resistance calculated by Eurocode 3 formulae. The comparison revealed that code formulae were overly conservative for the empty and pre-filled silo. The experiments were next simulated using the finite element method (FEM) with initial geometric imperfections, based on geodetic measurements or linear bifurcation analyses. The bulk solid’s behaviour was described by two different linear elastic approaches. For real geometric imperfections, the FE computations and experimental findings were in good agreement (particularly for an empty silo). For the pre-filled silo with the code elasticity of the bulk solid and the geodetic amplitude of geometric imperfection of the empty silo, the numerical buckling resistance was too low as compared to the experimental outcomes. In addition, the model tests were performed for a single column with a corrugated sheet at the laboratory scale.
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•Buckling resistance of a single corrugated sheet silo column was studied.•Experiments in a real silo were carried out.•Effect of bulk solid’s stiffness was taken into account.•Three-dimensional non-linear stability analyses were performed.
The paper describes experimental investigation results on wheat flow in a medium-size steel cylindrical flat bottom silo with horizontally corrugated walls and columns composed of open-sectional ...thin-walled profiles. Several experiments on silo filling and emptying with wheat were performed by inducing a different flow pattern. The following quantities were measured in the silo: horizontal wall pressures, wall frictional tractions and vertical reaction forces under columns. Horizontal wall pressures and wall frictional tractions were registered along the silo height and silo circumference in the lower silo region during three different flow patterns: mass flow, mixed mass-funnel flow and eccentric flow. Experimental results were compared with Eurocode 1. Some discrepancies between experiments and code formulae were observed.
Experimental set-up: storage silo ‘1’ and measuring silo ‘2’ Display omitted
•Experiments on wheat flow in a medium-size steel cylindrical silo were performed.•Novel cell loads were used to measure wall pressures.•Effect of the flow pattern on wall pressures was studied.•Experimental results were compared with Eurocode 1
miR393 molecules are believed to regulate the expression of the auxin receptors of the TAAR clade. Considering the central role of auxin in the induction of somatic embryogenesis (SE) in plant ...explants cultured in vitro, the involvement of miR393 in the embryogenic transition of somatic cells has been hypothesised. To verify this assumption, the reporter, overexpressor and mutant lines in genes encoded MIR393 and TIR1/AFB proteins of the F-box family were analysed during SE in Arabidopsis. Expression profiling of MIR393a and MIR393b, mature miR393 and the target genes (TIR1, AFB1, AFB2, AFB3) were investigated in explants undergoing SE. In addition, the embryogenic potential of various genotypes with a modified activity of the MIR393 and TIR1/AFB targets was evaluated. The distinct increase in the accumulation of miR393 that was coupled with a notable down-regulation of TIR1 and AFB2 targets was observed at the early phase of SE induction. Relevant to this observation, the GUS/GFP monitored expression of MIR393, TIR1 and AFB2 transcripts was localised in explant tissue undergoing SE induction. The results suggest the miR393-mediated regulation of TIR1 and AFB2 during embryogenic transition induced in Arabidopsis and a modification of the explant sensitivity to auxin treatment is proposed as underlying this regulatory pathway.
The presence of B chromosomes was reported in six species of the genus Apodemus (A. peninsulae, A. agrarius, A. sylvaticus, A. flavicollis, A. mystacinus, A. argenteus). High frequencies of Bs were ...recorded particularly in A. peninsulae and A. flavicollis. The origin of Bs in Apodemus seems to be rather ancient, and it is possible that the supernumerary elements, and/or a tendency for their appearance, were inherited from the common ancestor of the extant species. We have not found any correlated changes between frequencies of Bs and the level of protein polymorphism and/or heterozygosity assessed in electrophoretic studies. No measurable effect of Bs on overall genetic variability was thus revealed in studied populations. The pattern of evolutionary dynamics of Bs can be distinctly different between geographical populations, and both the parasitic and the heterotic models can be applied to explain the maintenance of Bs in different populations. Further studies are desirable to improve our understanding of the complicated evolutionary dynamics of Bs in the Apodemus species. An essential condition for success in this respect is much more detailed information on inheritance and the molecular structure of Bs.
This article presents a new efficient method of determining values of gas flow parameters (e.g. axial dispersion coefficient, DL and Pèclet number, Pe). A simple and very fast technique based on the ...pulse tracer response is proposed. It is a method which combines the benefits of a transfer function, numerical inversion of the Laplace transform and optimization allows estimation of missing coefficients. The study focuses on the simplicity and flexibility of the method. Calculations were performed with the use of the CAS-type program (Maple®). The correctness of the results obtained is confirmed by good agreement between the theory and experimental data for different pressures and temperature. The CAS-type program is very helpful both for mathematical manipulations as a symbolic computing environment (mathematical formulas of Laplace-domain model are rather sophisticated) and for numerical calculations. The method of investigations of gas flow motion is original. The method is competitive with earlier methods.
•European bison fed on 105 plant taxa during growing season in Białowieża Forest.•Woody species (59.4% of DNA sequences) and forbs (33.6%) dominated in bison diet.•The diversity of plants eaten by ...bison increased with increasing food availability.•Bison continuously adjusts its diet with seasonal availability of non-grass vegetation.•Diet plasticity and use of forest openings allow bison to persist in sheltering forest habitats.
Large herbivores that survived the Pleistocene/Holocene transition are hypothesized to have been forced to take refuge, as a result of environmental changes and human pressure, into forest habitats. Today, there is an open question of the degree to which extant large herbivores are well adapted to the forests that allowed for the herbivores’ persistence. We studied the diet of European bison (Bison bonasus), the largest terrestrial mammal in Europe, to gain insight into the foraging behaviour of a large herbivore, that appears to be primarily adapted to grazing but has been restored to forested habitats. The study population resided in the Białowieża Primeval Forests, Poland. DNA-based analysis of faecal samples revealed strong seasonal and spatial patterns in bison foraging, consistent between sexes. Bison fed on at least 105 different plant taxa. Woody species constituted 59.4% of DNA sequences, and forbs 33.6%. The two most abundant taxa were raspberry (Rubus idaeus) and European hornbeam (Carpinus betulus), which together comprised 31.0% of the dietary sequences and occurred in over 80% of faecal samples. Seasonally, the diversity of plants eaten by bison increased with increasing food availability. During high plant biomass in summer, bison consumed up to 40 different plant taxa. There was little overlap in the composition of the diet from month to month, reflecting the strong seasonality of vegetation abundance and/or its dietary quality. The results indicate high plasticity in bison foraging strategies and response to seasonal changes in biomass and the species composition of plants. Bison are browsers which continuously adjusts their diet with seasonal availability of easily digestible non-grass vegetation. We propose that dietary plasticity and micro-selection for open habitats (gaps and river valleys) within a forested landscape allowed bison to persist in sheltering forest habitats during the Holocene and accommodate to forest environments during species restoration.
For the first time, application of a membrane composed of gold nanoparticles decorated with complexing ligand for potentiometric sensing is shown. Gold nanoparticles drop cast from a solution form a ...porous structure on a substrate electrode surface. Sample cations can penetrate the gold nanoparticles layer and interact with ligand acting as a charged ionophore, resulting in Nernstian potentiometric responses. Anchoring of complexing ligand on the gold surface abolishes the necessity of ionophore application. Moreover, it opens the possibility of preparation of potentiometric sensors using chelators of significantly different selectivity patterns further enhanced by the absence of polymeric membrane matrix. This was clearly seen, for example, for gold nanoparticles stabilizing the applied ligand–dithizone–thiol conformation leading to a high potentiometric selectivity toward copper ions, much higher than that of ionophores typically used to induce selectivity for polymeric ion-selective membranes.
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