A flexible structure is formed by subjecting cellulose-based natural wood material to a chemical treatment that partially removes hemicellulose and lignin therefrom. The treated wood has a unique 3-D porous structure with numerous channels, excellent biodegradability and biocompatibility, and improved flexibility as compared to the natural wood. By further modifying the treated wood, the structure can be adapted to particular applications. For example, nanoparticles, nanowires, carbon nanotubes, or any other coating or material can be added to the treated wood to form a hybrid structure. In some embodiments, open lumina within the structure can be at least partially filled with a non-wood substance, such as a flexible polymer, or with entangled cellulose nanofibers. The unique architecture and superior properties of the flexible wood allow for its use in various applications, such as, but not limited to, structural materials, solar thermal devices, flexible electronics, tissue engineering, thermal management, and energy storage.

Highly transparent (up to 92% light transmittance) wood composites have been developed. The process of fabricating the transparent wood composites includes lignin removal followed by index-matching polymer infiltration resulted in fabrication of the transparent wood composites with preserved naturally aligned nanoscale fibers. The thickness of the transparent wood composite can be tailored by controlling the thickness of the initial wood substrate. The optical transmittance can be tailored by selecting infiltrating polymers with different refractive indices. The transparent wood composites have a range of applications in biodegradable electronics, optoelectronics, as well as structural and energy efficient building materials. By coating the transparent wood composite layer on the surface of GaAs thin film solar cell, an 18% enhancement in the overall energy conversion efficiency has been attained.

Highly transparent (up to 92% light transmittance) wood composites have been developed. The process of fabricating the transparent wood composites includes lignin removal followed by index-matching polymer infiltration resulted in fabrication of the transparent wood composites with preserved naturally aligned nanoscale fibers. The thickness of the transparent wood composite can be tailored by controlling the thickness of the initial wood substrate. The optical transmittance can be tailored by selecting infiltrating polymers with different refractive indices. The transparent wood composites have a range of applications in biodegradable electronics, optoelectronics, as well as structural and energy efficient building materials. By coating the transparent wood composite layer on the surface of GaAs thin film solar cell, an 18% enhancement in the overall energy conversion efficiency has been attained.

Wood template-supported phase change material (PCM) composite having thermal energy storage applications. A wood template-supported PCM may include a wood template that has had at least a portion of its xylan and/or lignin removed and saturated with a PCM. The PCM may be stabilized with a cross linkable network for improved infiltration into the wood template. The wood template-supported PCM composite may be formed by extracting xylan and/or lignin from the wood to create a wood template, densifying at least a portion of the wood template, and inserting a PCM into the wood template.

A super strong and tough densified wood structure is formed by subjecting a cellulose-based natural wood material to a chemical treatment that partially removes lignin therefrom. The treated wood retains lumina of the natural wood, with cellulose nanofibers of cell walls being aligned. The treated wood is then pressed in a direction crossing the direction in which the lumina extend, such that the lumina collapse and any residual fluid within the wood is removed. As a result, the cell walls become entangled and hydrogen bonds are formed between adjacent cellulose nanofibers, thereby improving the strength and toughness of the wood among other mechanical properties. By further modifying, manipulating, or machining the densified wood, it can be adapted to various applications.

A piece of plant material (e.g., wood) can have a lignin content in a range of 5-16 wt %, inclusive, and a microstructure including native lumina bounded by cellulose-based cell walls extending in a first direction. The piece of plant material can be pressed along a second direction crossing the first direction, such that the lumina collapse and facing portions of the collapsed lumina are brought into contact with each other. The piece of plant material prior to the pressing can have a first density. After the pressing, the piece of plant material can have a second density greater than the first density, for example, at least 1 g/cm.sup.3.

A rotary separation device deploys a drum with mesh like opening on the cylindrical surfaces and a removable cover or cap for filling in an upright position and removal of product or spent matter in an inverted position. When the drum is loaded with material, and the cover closed, it is rotatable to a horizontal position, and disposed in an outer container. The drum is rotated in the horizontal position to initiate the separation process. The outer container may be formed by the mating engagement at a common rim of an upper and lower vessel that form the sealed container.

Methods and systems for recovering terpenes and controlling the composition of terpenes collected from wood drying processes are provided. In particular, a sorbent having adsorbed materials, including terpenes, from a wood drying process can be desorbed in a desorber, resulting in a gaseous stream containing terpenes, which can be condensed and collected from the gaseous stream. The conditions of desorption can be controlled to ensure a desirable amount of alpha-pinene and beta-pinene relative to other terpenes, such as dipentene and camphene, in the collected terpenes.

Methods and systems for self-flowing treatment of wood, bamboo or other porous materials do not require external pressure or complicated equipment. Treatment liquid flows through these porous materials through use of capillary action, the use of absorbent sheets, and differences in pressure. The treatment solution is more evenly dispersed throughout the materials.