Dimensionally stable and durable wood by lignin impregnation.

Cracking, warping, and decaying stemming from wood's poor dimensional stability and durability are the most annoying issues of natural wood. There is an urgent need to address these issues, of which, sustainable and green chemical treatments are favorably welcomed. Herein, we developed a facile method through the incorporation of environmentally friendly biopolymer lignin into wood cells for wood dimensional stability and durability enhancement. Enzymatic hydrolysis lignin (EHL) was dissolved into various solvents followed by impregnation and drying to incorporate lignin into wood cells. Impregnation treatment was developed to incorporate into wood to improve its dimensional stability, durability, and micromechanics. The anti-swelling efficiency reached up to 99.4 %, the moisture absorption decreased down to 0.55 %, the mass loss after brown rot decay decreased to 7.22 %, and the cell wall elasticity as well as hardness increased 8.7 % and 10.3 %, respectively. Analyses acquired from scanning electron microscopy, fluorescent microscopy, and Raman imaging revealed that the EHL was successfully colonized in cell lumen as well as in cell walls, thus improved wood dimensional stability and durability. Moreover, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed EHL interaction with the cell wall components, thus the wood mechanical property was not impaired significantly, whereas nanoindentation data indicated even slight mechanical enhancement on the cell walls. This facile approach can improve the wood properties in multiple aspects and remarkably enhance the outdoor performance of modified wood products. In addition, using lignin as a natural modifying agent to improve wood performance will have a great positive impact on the environment.

Global optimisation of source and mask in inverse lithography via tabu search combined with genetic algorithm.

Source mask optimisation (SMO) is a resolution enhancement technology that is utilised in the advanced process node of optical lithography to achieve acceptable imaging quality and fidelity. It is crucial in enhancing the convergence performance and optimisation capability of pixel-based SMO. In this study, an SMO approach that employs a genetic algorithm (GA), combined with the tabu search method (TS), is proposed. GA-TS, a hybrid-type global optimisation algorithm, has an outperforming capacity to avoid local optima owing to the excellent local searching function of TS. Furthermore, an edge-optimisation strategy was implemented to optimise the mask for a low-complexity mask layout. The simulation results confirm that the proposed approach exhibits exceptional optimisation capability and convergence performance.

Stitching method based on dual quaternion for cylindrical mirrors.

In this study, a stitching method based on dual quaternion is proposed. The application of a dual quaternion in sub-aperture stitching interferometry is analyzed in detail, and a calculation method for sub-aperture stitching based on a dual quaternion is deduced. The experimental results demonstrate the accuracy of the stitching method proposed in this study (residuals of overlapping area approximately 0.22 nm RMS). Finally, the residual differences of 0.79 nm RMS between the figure errors are acquired with a stitching by parts algorithm based on the dual quaternion and long trace profiler (FSP at HEPS). The high-accuracy and high-efficiency stitching method proposed in this study will expand its application in the metrology and manufacture of long cylindrical mirrors.

Model-based optimization of gravity sagging for a horizontally mounted optical flat.

A practical and generalized model-based gravity sagging reconstruction method for a horizontally mounted optical flat is proposed. It is a practical and generalized approach based on the finite element method (FEM) model and real experiment results. Gravity sagging and misalignment parameters are retrieved by solving the multivariable unconstrained optimization problem with a least squares sense. Finally, the accurate true surface figure can be obtained by subtracting the optimized gravity sagging from the test result in the practical mounting state. A reasonable agreement with the outcomes of the FEM analysis and the real experiment is achieved through the proposed method. The effectiveness of the method was verified by comparison with the result measured by three-flat calibration. Experimental results demonstrated that this reverse optimization method can effectively reconstruct the sagging information due to gravity, is generalized, and is computationally efficient in practice.

Absolute measurement of optical flats based on basic iterative methods.

Generalized basic iterative methods for absolute measurement of optical flats are presented. They are based on iterative scheme and can be classified into block Jacobi Successive Over-relaxation (SOR) method and block SOR method. Both methods are effective for solving the three-flat problem with pixel-level spatial resolution, without the usage of a fitting procedure. Compared to the block Jacobi SOR method, the block SOR method with an inexpensive choosing of relaxation factor (such as ω = 1.5) converges much faster and saves more computational costs and memory space without reducing accuracy. It has been proved by both simulation results and experimental results. The proposed basic iterative methods are generalized; can correctly reconstruct absolute figures with pixel-level spatial resolution; are easy to understand and implement; and computationally efficient.