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Shakes (timber)
Shakes are cracks in timber. Arising in cut timber they generally cause a reduction in strength. When found in a log they can result in a significant amount of waste, when a log is converted to lumber. Apart from heart shakes, often found in trees felled past their best, shakes in a log have no effect on the strength of shake free lumber obtained therefrom. They are often seen in oak-framed buildings, which are constructed of oak which has not been dried and thus cracks while drying. Due to the immense strength of the oak beams, they are not a cause for concern in a properly engineered building, and are considered part of the charm of the style. In the majority of cases of shake, the underlying cause is a weakening of the wood due to action by anaerobic bacteria which have entered the tree stem through the root system. researchers have isolated anaerobic and facultative anaerobic bacteria from shake surfaces, in particular anaerobic Clostridium species. Research suggests th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fraxinus Excelsior Crosssection
''Fraxinus'' (), commonly called ash, is a genus of plants in the olive and lilac family, Oleaceae, and comprises 45–65 species of usually medium-to-large trees, most of which are deciduous trees, although some subtropical species are evergreen trees. The genus is widespread throughout much of Europe, Asia, and North America. The leaves are opposite (rarely in whorls of three), and mostly pinnately compound, though simple in a few species. The seeds, popularly known as "keys" or "helicopter seeds", are a type of fruit known as a samara. Some ''Fraxinus'' species are dioecious, having male and female flowers on separate plants but sex in ash is expressed as a continuum between male and female individuals, dominated by unisexual trees. With age, ash may change their sexual function from predominantly male and hermaphrodite towards femaleness; if grown as an ornamental and both sexes are present, ashes can cause a considerable litter problem with their seeds. Rowans, or mounta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clostridium
''Clostridium'' is a genus of anaerobic, Gram-positive bacteria. Species of ''Clostridium'' inhabit soils and the intestinal tracts of animals, including humans. This genus includes several significant human pathogens, including the causative agents of botulism and tetanus. It also formerly included an important cause of diarrhea, '' Clostridioides difficile'', which was reclassified into the '' Clostridioides'' genus in 2016. History In the late 1700s, Germany experienced several outbreaks of an illness connected to eating specific sausages. In 1817, the German neurologist Justinus Kerner detected rod-shaped cells in his investigations into this so-called sausage poisoning. In 1897, the Belgian biology professor Emile van Ermengem published his finding of an endospore-forming organism he isolated from spoiled ham. Biologists classified van Ermengem's discovery along with other known gram-positive spore formers in the genus ''Bacillus''. This classification presented proble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medullary Ray (botany)
Medullary rays, also known as vascular rays or pith rays, are cellular structures found in some species of wood. They appear as radial planar structures, perpendicular to the growth rings, which are visible to the naked eye. In a transverse section they appear as radiating lines from the centre of the log. In an axial section they may appear as a variety of transverse markings, depending on how close the section is to the plane of the ray. In a tangential section they may be hard to see at all. They are formed by the activity of vascular cambium. During the process of the division of cambium, the cambium cuts out cells on both the outer and inner side. These cells are parenchymatous. Most of these cells transform into xylem and phloem. But certain cells don't transform into xylem and phloem and remain as such. These cells cut out by the cambium towards the periphery are phloem parenchyma while those towards the pith are xylem parenchyma. Both of these cells together work as secon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Rot
Dry rot is wood decay caused by one of several species of fungi that digest parts of wood which give it strength and stiffness. It was previously used to describe any decay of cured wood in ships and buildings by a fungus which resulted in a darkly colored deteriorated and cracked condition. The life-cycle of dry rot can be broken down into four main stages. Dry rot begins as a microscopic spore which, in high enough concentrations, can resemble a fine orange dust. If the spores are subjected to sufficient moisture, they will germinate and begin to grow fine white strands known as hyphae. As the hyphae grow they will eventually form a large mass known as mycelium. The final stage is a fruiting body which pumps new spores out into the surrounding air. In other fields, the term has been applied to the decay of crop plants by fungi. In health and safety, the term is used to describe the deterioration of rubber, for example the cracking of rubber hoses. Discussion ''Dry rot'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knots (wood)
Wood is a structural tissue/material found as xylem in the Plant stem, stems and roots of trees and other woody plants. It is an organic materiala natural composite material, composite of cellulose, cellulosic fibers that are strong in tension and embedded in a :wikt:matrix, matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or more broadly to include the same type of tissue elsewhere, such as in the roots of trees or shrubs. In a living tree, it performs a mechanical-support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients among the leaf, leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, woodchips, or fibers. Wood has been used for thousands of years for fuel, as a construction material, for making tools and weapons, furniture and paper. Mor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wandering Heart
Wandering heart is a fault in timber, where the heart of the tree wanders from side to side, rather than remaining central. This is usually caused by sustained winds. The resulting boards are twisted and short grained, and not suitable for construction due to their tendency to warp, and their weakness. See also * Shakes (timber) Shakes are cracks in timber. Arising in cut timber they generally cause a reduction in strength. When found in a log they can result in a significant amount of waste, when a log is converted to lumber. Apart from heart shakes, often found in ... References Forestry {{tree-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wood Drying
Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method. There are two main reasons for drying wood: ; Woodworking:When wood is used as a construction material, whether as a structural support in a building or in woodworking objects, it will absorb or expel moisture until it is in equilibrium with its surroundings. Equilibration (usually drying) causes unequal shrinkage in the wood, and can cause damage to the wood if equilibration occurs too rapidly. The equilibration must be controlled to prevent damage to the wood. ; Wood burning: When wood is burned (firewood), it is usually best to dry it first. Damage from shrinkage is not a problem here, as it may be in the case of drying for woodworking purposes. Moisture affects the burning process, with unburnt hydrocarbons going up the chimney. If a 5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
