A tree typically has many secondary branches supported clear of the ground by the trunk. This trunk typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark which serves as a protective barrier. Trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from the…
The Runaway Bus
A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker rigid bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are used for longer distance services. Bus manufacturing is increasingly globalised, with the same design appearing around the world. Buses may be…
Ships & Boats
In modern parlance a ship has been any large buoyant watercraft. Ships are generally distinguished from boats based on size, shape and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing, entertainment, public safety, and warfare. Historically, a “ship” was a sailing vessel with at least three square-rigged masts and a full bowsprit. Ships and…
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Around the World
Military pilots fly with the armed forces of a government or nation-state. Their tasks involve combat and non-combat operations, including direct hostile engagements and support operations. Military pilots undergo specialized training, often with weapons. Examples of military pilots include fighter pilots, bomber pilots, transport pilots, test pilots and astronauts. Military pilots also serve as flight crews on aircraft for government personnel…
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A Night in the Forest
The roots of a tree serve to anchor it to the ground and gather water and nutrients to transfer to all parts of the tree, and for reproduction defense, survival, energy storage and many other purposes. The first root produced by a newly germinated seedling is a taproot which goes straight downwards. Within a few weeks lateral roots branch out of the side of this and grow horizontally through the upper layers…
Chemistry of Wood
Aside from water, wood has three main components. Cellulose, a crystalline polymer derived from glucose, constitutes about 41–43%. Next in abundance is hemicellulose, which is around 20% in deciduous trees but near 30% in conifers. It is mainly five-carbon sugars that are linked in an irregular manner, in contrast to the cellulose. Lignin is the third component at around 27% in coniferous wood vs 23% in deciduous trees. Lignin confers the hydrophobic…