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.

Air leaks: Stapling affects porcine lungs biomechanics

During thoracic operations, surgical staplers resect cancerous tumors and seal the spared lung. However, post-operative air leaks are undesirable clinical consequences: staple legs wound lung tissue. Subsequent to this trauma, air leaks from lung tissue into the pleural space. This affects the lung's physiology and patients' recovery. The objective is to biomechanically and visually characterize porcine lung tissue with and without staples in order to gain knowledge on air leakage following pulmonary resection. Therefore, a syringe pump filled with air inflates and deflates eleven porcine lungs cyclically without exceeding 10 cmH₂O of pressure. Cameras capture stereo-images of the deformed lung surface at regular intervals while a microcontroller simultaneously records the alveolar pressure and the volume of air pumped. The raw images are then used to compute tri-dimensional displacements and strains with the Digital Image Correlation method (DIC). Air bubbles originated at staple holes of inner row from exposed porcine lung tissue due to torn pleural on costal surface. Compared during inflation, left upper or lower lobe resections have similar compliance (slope of the pressure vs volume curve), which are 9% lower than healthy lung compliance. However, lower lobes statistically burst at lower pressures than upper lobes (p-value<0.046) in ex vivo conditions confirming previous clinical in vivo studies. In parallel, the lung deformed mostly in the vicinity of staple holes and presented maximum shear strain near the observed leak location. To conclude, a novel technique DIC provided concrete evidence of the post-operative air leaks biomechanics. Further studies could investigate causal relationships between the mechanical parameters and the development of an air leak.