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This process is known as secondary growth; it is the result of cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells. These cells then go on to form thickened secondary cell walls, composed mainly of cellulose, hemicellulose and lignin. Where the differences between the seasons are distinct, e.g.
Wood is a hygroscopic material, which means it naturally absorbs and releases water to balance its internal moisture content with the surrounding environment. The moisture content of wood is measured by the weight of water as a percentage of the oven-dry weight of the wood fiber. The key to controlling decay is controlling moisture.
In North America, virgin (non-recycled) wood fibre is primarily extracted from hardwood (deciduous) trees and softwood (coniferous) trees. The wood fibre can be extracted as a primary product, or collected during the milling of lumber. [1] Wood fibres can also be recycled from used paper materials. [2]
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. [1] Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors. [2]
Composite materials are also becoming more common in the realm of orthopedic surgery, [42] and it is the most common hockey stick material. Carbon composite is a key material in today's launch vehicles and heat shields for the re-entry phase of spacecraft. It is widely used in solar panel substrates, antenna reflectors and yokes of spacecraft.
Food poisoning, also known as foodborne illness, is a common sickness caused by swallowing food or liquids that contain harmful bacteria, viruses or parasites, and sometimes even chemicals.
Cross-laminated timber (CLT) is a subcategory of engineered wood [1] panel product made from gluing together at least three layers [2] of solid-sawn lumber (i.e. lumber cut from a single log). [3] Each layer of boards is usually oriented perpendicular to adjacent layers and glued on the wide faces of each board, usually in a symmetric way so ...
As mentioned above, the phase-out of PFOA didn't go into effect until 2013, which means that if you bought an item produced any earlier than that, it is coated with the known toxic chemical.