Transverse Compression Behavior of Wood in Saturated Steam at 150-170°C

The transverse compression behavior of wood in high temperature (150, 160, and 170°C) and saturated steam conditions was studied. The effect of the temperature on the stress-strain response, nonlinear strain function, and relative density change was examined by a modified Hooke's law based on the load-compression behavior of flexible foams. The influence of environmental conditions during compression on the set recovery of the compression deformation was determined. It was found that temperature and moisture content affected the compression behavior of wood in saturated steam conditions. A small difference in moisture content of specimens compressed at 160 and 170°C caused approximately the same stress-strain and relative density curves with minimum temperature affect on the compression behavior. The compressive modulus of the wood and cell wall modulus were found to decrease with increasing temperature from 150 to 160°C with no change when increased to 170°C. The densification region was entered at notably lower stress levels at 160 and 170°C when compared with 150°C. The results established that temperature and moisture content did not affect the nonlinear strain function at strain levels lower than 0.63. Furthermore, it was found that the set recovery of compressive deformation decreased with increasing temperature of compression from 150 to 160°C. In addition, the results showed that compression at 160 and 170°C significantly lowered the equilibrium moisture content

Hamiltonicity of 3-arc graphs

An arc of a graph is an oriented edge and a 3-arc is a 4-tuple $(v,u,x,y)$ of vertices such that both $(v,u,x)$ and $(u,x,y)$ are paths of length two. The 3-arc graph of a graph $G$ is defined to have vertices the arcs of $G$ such that two arcs $uv, xy$ are adjacent if and only if $(v,u,x,y)$ is a 3-arc of $G$. In this paper we prove that any connected 3-arc graph is Hamiltonian, and all iterative 3-arc graphs of any connected graph of minimum degree at least three are Hamiltonian. As a consequence we obtain that if a vertex-transitive graph is isomorphic to the 3-arc graph of a connected arc-transitive graph of degree at least three, then it is Hamiltonian. This confirms the well known conjecture, that all vertex-transitive graphs with finitely many exceptions are Hamiltonian, for a large family of vertex-transitive graphs. We also prove that if a graph with at least four vertices is Hamilton-connected, then so are its iterative 3-arc graphs.Comment: in press Graphs and Combinatorics, 201

Influence of the thermo-hydro-mechanical treatments of wood on the performance against wood degrading fungi

Hybrid poplar (Populus deltoides × Populus trichocarpa) and Douglas-fir (Pseudotsuga menziesii) wood specimens were densified with three variations of Thermo-Hydro-Mechanical (THM) treatment. The THM treatments differed in the steam environment, including transient steam (TS), saturated steam (SS), and saturated steam with 1 minute post-heat-treatment at 200°C (SS+PHT). The bending properties, FTIR spectra, and color of the THM wood specimens were studied before and after exposure to two different wood decay fungi; brown rot Gloeophyllum trabeum and white rot Trametes versicolor. The results showed that the performance of densified hybrid poplar wood was considerably poorer than performance of Douglas-fir heartwood. The FTIR spectra measurements did not show changes in the densified hybrid poplar wood, while some changes were evident in densified Douglas-fir specimens. After fungal degradation the most prominent changes were observed on the SS+PHT specimens. Color is one of the most important parameter predominantly influenced by the wood species and the intensity of the densification process for both wood species, while after the fungal exposure the color of all densified Douglas-fir specimens became more or less of the same appearance and densified hybrid poplar specimens resulted in lighter color tones, indicating that the patterns of degradation of the densified and nondensified specimens are similar. The 3-point bending test results determined that the THM treatment significantly increased the modulus of rupture (MOR) and modulus of elasticity (MOE) of the densified wood specimens, while the fungal exposure decreased the MOE and MOR in hybrid poplar and Douglas-fir specimens.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/226.Keywords: Color, Wood decay, FTIR, Densification, Wood, TH

Horizon Europe-New European Bauhaus Nexus Report: Conclusions of the High-Level Workshop on ‘Research and Innovation for the New European Bauhaus’, jointly organised by DG Research and Innovation and the Joint Research Centre

The ‘Horizon Europe-New European Bauhaus Nexus Report’ (2022) is an independent expert report. The report offers a set of guiding principles that can shape the goals and ambitions of the New European Bauhaus initiative. The recommendations aim to support the New European Bauhaus core values – sustainability, inclusion, and aesthetics. The recommendations are based on the current and future organisational structures and timeframes of the Horizon Europe research and innovation framework programme. They consider opportunities for the funding period 20212022, mid-term goals for the period 2023-2024, and long-term actions beyond 2024 that reflect the transdisciplinary and trans-sectoral vision of the New European Bauhaus. The report also provides a roadmap with strategic priorities and associated benchmarks that describe a possible path forward for European society and its response to the climate crisis, together with the EU’s global partners

Microstructure of viscoelastic thermal compressed (VTC) wood using computed microtomography

The paper describes for the first time the analysis of the structure of compressed wood using computed tomography. The anatomical structures of Douglas-fir and hybrid poplar before and after densification with the Viscoelastic Thermal Compression (VTC) process were described by pore size distributions and mean pore sizes and compared. The compression of Douglas-fir mainly affected earlywood, while the compression of hybrid poplar mainly occurred in the vessels. In both wood species the densification resulted in a significant decrease in the pore volumes. The porosity decreased to less than the half of the original value for Douglas-fir earlywood and to approximately one quarter for the vessels in hybrid poplar. The relevant mean pore sizes also decreased dramatically down to about one quarter compared to the original values. In contrast, latewood in Douglas-fir and libriform fibers in hybrid poplar are quite stable under compression. Douglas-fir latewood retained its original structure after compression and did not show any reduction in pore size. The results confirmed that the anatomical structure of VTC densified wood can be described by pore size distributions and mean pore sizes. However, in the case of broad or bimodal distributions the mean pore sizes are of less significance.Keywords: Pore size distribution, Computed microtomography, Image analysis, VTC wood, Granulometry, PorosityKeywords: Pore size distribution, Computed microtomography, Image analysis, VTC wood, Granulometry, Porosit

Where is VALDO? VAscular Lesions Detection and segmentatiOn challenge at MICCAI 2021

Imaging markers of cerebral small vessel disease provide valuable information on brain health, but their manual assessment is time-consuming and hampered by substantial intra- and interrater variability. Automated rating may benefit biomedical research, as well as clinical assessment, but diagnostic reliability of existing algorithms is unknown. Here, we present the results of the VAscular Lesions DetectiOn and Segmentation (Where is VALDO?) challenge that was run as a satellite event at the international conference on Medical Image Computing and Computer Aided Intervention (MICCAI) 2021. This challenge aimed to promote the development of methods for automated detection and segmentation of small and sparse imaging markers of cerebral small vessel disease, namely enlarged perivascular spaces (EPVS) (Task 1), cerebral microbleeds (Task 2) and lacunes of presumed vascular origin (Task 3) while leveraging weak and noisy labels. Overall, 12 teams participated in the challenge proposing solutions for one or more tasks (4 for Task 1-EPVS, 9 for Task 2-Microbleeds and 6 for Task 3-Lacunes). Multi-cohort data was used in both training and evaluation. Results showed a large variability in performance both across teams and across tasks, with promising results notably for Task 1-EPVS and Task 2-Microbleeds and not practically useful results yet for Task 3-Lacunes. It also highlighted the performance inconsistency across cases that may deter use at an individual level, while still proving useful at a population level