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Lignum Vitae
Lignum vitae () is a wood, also called guayacan or guaiacum, and in parts of Europe known as Pockholz or pokhout, from trees of the genus ''Guaiacum''. The trees are indigenous to the Caribbean and the northern coast of South America (e.g: Colombia and Venezuela) and have been an important export crop to Europe since the beginning of the 16th century. The wood was once very important for applications requiring a material with its extraordinary combination of strength, toughness, and density. It is also the national tree of the Bahamas, and the Jamaican national flower. The wood is obtained chiefly from ''Guaiacum officinale'' and ''Guaiacum sanctum'', both small, slow-growing trees. All species of the genus ''Guaiacum'' are now listed in Appendix II of CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) as potentially endangered species. ''G. sanctum'' is listed as Near Threatened by the IUCN Red List. Demand for the wood has been reduc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals. The term "polymer" derives from the Greek word πολύς (''polus'', meaning "many, much") and μέρος (''meros'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hickory
Hickory is a common name for trees composing the genus ''Carya'', which includes around 18 species. Five or six species are native to China, Indochina, and India (Assam), as many as twelve are native to the United States, four are found in Mexico, and two to four are native to Canada. A number of hickory species are used for products like edible nuts or wood. Hickories are temperate forest trees with pinnately compound leaves and large nuts. Hickory flowers are small, yellow-green catkins produced in spring. They are wind-pollinated and self-incompatible. The fruit is a globose or oval nut, long and diameter, enclosed in a four-valved husk, which splits open at maturity. The nut shell is thick and bony in most species, and thin in a few, notably the pecan (''C. illinoinensis''); it is divided into two halves, which split apart when the seed germinates. Etymology The name "hickory" derives from a Native American word in an Algonquian language (perhaps Powhatan). It is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
African Blackwood
''Dalbergia melanoxylon'' (African blackwood, grenadilla, or mpingo) is a flowering plant in the family Fabaceae, native to seasonally dry regions of Africa from Senegal east to Eritrea and south to the north-eastern parts of South Africa. The tree is an important timber species in its native areas; it is used in the manufacture of musical instruments and fine furniture. Populations and genomic resources for genetic biodiversity maintenance in parts of its native range are threatened by overharvesting due to poor or absent conservation planning and by the species' low germination rates. It is a small tree, reaching 4–15 m tall, with grey bark and spiny shoots. The leaves are deciduous in the dry season, alternate, 6–22 cm long, pinnately compound, with 6–9 alternately arranged leaflets. The flowers are white and produced in dense clusters. The fruit is a pod 3–7 cm long, containing one to two seeds. Uses The dense, lustrous wood ranges in colour from redd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olneya
''Olneya tesota'' is a perennial flowering tree of the family Fabaceae, legumes (peas, beans, etc.), which is commonly known as ironwood, desert ironwood, or palo fierro in Spanish. It is the only species in the monotypic genus ''Olneya''. This tree is part of the western Sonoran Desert complex in the Southwestern United States. Description The desert ironwood grows as a bush or tree, reaching heights of about and average trunk diameters of about . Exceptionally, in larger protected washes it can reach greater height and a more massive trunk. In younger trees, the bark is gray, shiny, and smooth; in older trees the bark is broken open. The tree is evergreen, but can lose its leaves if temperatures fall below . In continual drought conditions the leaves will be lost. The leaves are bluish-green and pinnately compound. They are arranged on a petiole, long, with 6–9 leaflets (or variously up to 15, with 7 opposite and one terminal), each measuring . At the base of each pinna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Janka Hardness Test
The Janka hardness test (; ), created by Austrian-born American researcher Gabriel Janka (1864–1932), measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an steel ball halfway into a sample of wood. (The diameter was chosen to produce a circle with an area of 100 square millimeters ne square centimeter) A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring. For hardwood flooring, the test usually requires a sample with a thickness of at least 6–8 mm, and the most commonly used test is the ASTM D1037. When testing wood in lumber form, the Janka test is always carried out on wood from the tree trunk (known as the heartwood), and the standard sample (according to ASTM D143) is at 12% moisture content and clear of knots. The hardness of wood varies with the direction of the wood grain. Testing on the surface of a plank, perpendicular to the grain, is said to be of "side h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ironwood
Ironwood is a common name for many woods or plants that have a reputation for hardness, or specifically a wood density that is heavier than water (approximately 1000 kg/m3, or 62 pounds per cubic foot), although usage of the name ironwood in English may or may not indicate a tree that yields such heavy wood. Some of the species with their common name * ''Acacia aulacocarpa'' (Brush ironwood) * ''Acacia estrophiolata'' (Southern ironwood), central Australia * ''Acacia excelsa'' (Ironwood) * '' Acacia melanoxylon'' (Ironwood) * ''Acacia stenophylla'' (Ironwood), Australia * ''Aegiphila martinicensis'' (Ironwood) * ''Afzelia africana'' (Ironwood) * ''Androstachys johnsonii'' (Lebombo ironwood), southeastern Africa and Madagascar * ''Allagoptera caudescens'', ''Borassus flabellifer'', '' Caryota urens'', ''Iriartea deltoidea'' Black Palm, Palmira wood (Black ironwood) * ''Argania spinosa'' (Morocco ironwood, Thorny, Prickly ironwood) * ''Astronium fraxinifolium'', ''Astronium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Woodturning
Woodturning is the craft of using a wood lathe with hand-held tools to cut a shape that is symmetrical around the axis of rotation. Like the potter's wheel, the wood lathe is a simple mechanism that can generate a variety of forms. The operator is known as a turner, and the skills needed to use the tools were traditionally known as turnery. In pre-industrial England, these skills were sufficiently difficult to be known as 'the misterie' of the turners guild. The skills to use the tools by hand, without a fixed point of contact with the wood, distinguish woodturning and the wood lathe from the machinist's lathe, or metal-working lathe. Items made on the lathe include tool handles, candlesticks, egg cups, knobs, lamps, rolling pins, cylindrical boxes, Christmas ornaments, bodkins, knitting needles, needle cases, thimbles, pens, chessmen, spinning tops; legs, spindles, and pegs for furniture; balusters and newel A newel, also called a central pole or support column, is the cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorocardium Rodiei
''Chlorocardium rodiei'' (greenheart) is a species of flowering plant in the family Lauraceae. It is one of two species in the genus ''Chlorocardium''. It is native to Guyana and Suriname in South America. Other common names include cogwood, demerara greenheart, greenhart, ''ispingo moena'', ''sipiri'', ''bebeeru'' and ''bibiru''. It is an evergreen tree growing 15 to 30 m tall with a trunk diameter of 35 to 60 cm. The leaf, leaves are oppositely arranged and simple with smooth edges. The fruit is a drupe containing a single seed. The cyclic bisbenzylisoquinoline alkaloid rodiasine was first isolated from this species. The wood is extremely hard and strong, so hard that it cannot be worked with standard tools. It is durable in marine conditions, so it is used to build docks and other structures, and it was an early choice for fly fishing, fly fishing rods. An estimated 15 to 28% of the original population has been harvested. The species' use as a commercial timber began in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthritis
Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In some types of arthritis, other organs are also affected. Onset can be gradual or sudden. There are over 100 types of arthritis. The most common forms are osteoarthritis (degenerative joint disease) and rheumatoid arthritis. Osteoarthritis usually occurs with age and affects the fingers, knees, and hips. Rheumatoid arthritis is an autoimmune disorder that often affects the hands and feet. Other types include gout, lupus, fibromyalgia, and septic arthritis. They are all types of rheumatic disease. Treatment may include resting the joint and alternating between applying ice and heat. Weight loss and exercise may also be useful. Recommended medications may depend on the form of arthritis. These may include pain medications such as ibuprofen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cough
A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three phases: an inhalation, a forced exhalation against a closed glottis, and a violent release of air from the lungs following opening of the glottis, usually accompanied by a distinctive sound. Frequent coughing usually indicates the presence of a disease. Many viruses and bacteria benefit, from an evolutionary perspective, by causing the host to cough, which helps to spread the disease to new hosts. Most of the time, irregular coughing is caused by a respiratory tract infection but can also be triggered by choking, smoking, air pollution, asthma, gastroesophageal reflux disease, post-nasal drip, chronic bronchitis, lung tumors, heart failure and medications such as angiotensin-converting-enzyme inhibitors (ACE inhibitors). Treatment should t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
