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Elemental concentrations of light and medium weight elements ranging from about 0.2% to less than 1ppm were determined by thick target PIXE in a variety of South African woods from different localities. Correspondence analysis, using the measured contents of K, Ca, Mn, Fe, Cu, Zn, and Rb, resulted in groupings which were type-dependent and locality-dependent. The possibility of substituting one variety for another in the same group, for paper production, is discussed.

A fundamental investigation of the PIXE method applied to the measurement of trace elements in wood samples, is described in this work. Yields of the elements added to a sugi (Cryptomeria japonica D. Don) specimen, were almost constant after they were bombarded with radiation up to 600µC. Yields of certain elements in the early wood and the late wood in the same annual ring of the sugi were compared. The yields of Ca, Cu, Zn, Rb and Sr in the late wood were the same or slightly higher than those in the early wood, but Fe and Mn yields in the late wood were higher than those in the early wood. The concentration profiles of Ca, Mn, Fe, Zn and Sr along a radial direction in the stem of the sugi were also determined.

This paper investigates the reorientation of fibres and local mechanisms of deformation in a composite material inspired by the mechanics and structure of wood cell-walls. The mechanical response of the material is calculated under tensile loading conditions by means of the computational homogenisation of a two-dimensional representative volume element (RVE) of material. Here, the fibres are represented by a periodic alternation of alumina and magnesium alloy fractions, embedded in a soft epoxy matrix. In order to validate the present multi-scale framework, we compare our numerical prediction for the reorientation of fibres in the wood cell-wall composite with experimental data, finding a good agreement for a wide range of strains. Numerical simulations show that the model is able to describe the reorientation of fibres and the different stages of local deformation and failure in the proposed wood-inspired material. Furthermore, we assess a simple expression to calculate the reorientation of fibres and the in-plane Poisson's ratio of the present composite.

The sun is the only source of renewable energy available to us, if geothermal energy is not taken into account. In the form of radiation (UV light, visible light, infrared light, Section 1.1) it sends us annually 178,000 terawatts (1 TW = 10¹² W; unit of power 1 W = 1 J s^–1 = 859.85 calories per hour), that is to say 15,000 times the energy consumed annually by humanity. Only 0.1% of the solar energy received by planet Earth is converted into plant biomass, i.e. 100 × 10⁹ tons per year which corresponds to ca. 180 × 10⁹ tons per year of CO₂ captured from the atmosphere. This CO₂ returns to the biosphere after the death of the plants. Consumption of fossil carbon emits ca. 35 × 10⁹ tons of CO₂ yearly. Biomass is the material produced by all living organisms (plants, animals, microorganisms, fungi)…

Microwave-vacuum (MV) drying characteristic of plantation Masson Pine were studied experimentally for various levels of microwave radiation time, initial moisture content (MC) and wood thickness. The results show that the process of MV drying for wood can be significantly divided into a short accelerating rate drying period, a long constant rate drying period and falling rate drying period, and the second drying period can extend to levels of mean moisture content below the fiber saturation point; With the increase of initial MC and microwave radiation time, the drying rate of wood increases significantly; Within the range of 2cm to 6cm, the effects of sample thickness on the drying rate can be negligible.

Based on the mechanism of moisture and heat transfer in wood during microwave-vacuum drying (MVD), a one-dimensional mathematical model to describe the process of wood MVD was established and verified by experiments in this research. The results showed that the process of MVD of wood experienced three distinct periods: (1) accelerating rate with rapid warming-up drying period, (2) a constant temperature and constant rate drying period, and (3) a heating-up with falling rate drying period; The predicted temperature and moisture content in wood match well with the experimental data, the square of the relevant coefficient of the values of simulation and test is above 0.9, and the simulation precision of the change rule of the moisture is higher than that of the temperature.

Stochastic finite element method (FEM) is introduced into wood fracture mechanics in this paper. Constitutive equations with the simplified penalty functions are used to develop the power-law nonlinear stochastic finite element method. Considering the randomness of crack size, J-integral is calculated and analyzed. According to the variation ratio of J-integral and the J-K relationship, the change curve of wood strength factor is given. To prove the validity of numerical results, test species machined from Maor Mountain larch is tightened and the testing curve of wood strength factor is got. The two curves have the same change trend, and errors between them are within a standard deviation. It is concluded that adopting stochastic finite element method to analyze and predict the wood fracture performance is feasible and practical.

Nanoindentation has been increasingly developed as an important testing method for measuring the micro-mechanical properties of material, and emerged as a powerful tool for measuring the mechanical properties of wood cell wall. The nanoindentation technology and its working principle were briefly introduced in this paper, and the domestic and international progress of using nanoindentation for determining the mechanical properties of wood cell wall in recent years and the problems faced were discussed. The potential research direction of nanoindentation in wood research was proposed. The study was aimed at providing references for the basic research in mechanical properties of wood cell wall and the scientific utilization of wood material.