1.
Stencil
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The stencil is both the resulting image or pattern and the intermediate object, the context in which stencil is used makes clear which meaning is intended. The key advantage of a stencil is that it can be reused to repeatedly and rapidly produce the same letters or design, although aerosol or painting stencils can be made for one-time use, typically they are made with the intention of being reused. To be reusable, they must remain intact after a design is produced, with some designs, this is done by connecting stencil islands to other parts of the stencil with bridges. Stencil technique in visual art is referred to as pochoir. A related technique is aerography, in which spray-painting is done around an object to create a negative of the object instead of a positive of a stencil design. This technique was used in paintings dating to 10,000 BC. The artist sprayed pigment around his hand by using a hollow bone, screen printing also uses a stencil process, as does mimeography. The masters from which mimeographed pages are printed are often called stencils, stencils can be made with one or many colour layers using different techniques, with most stencils designed to be applied as solid colours. During screen printing and mimeography the images for stenciling are broken down into color layers, multiple layers of stencils are used on the same surface to produce multi-colored images. Hand stencils, made by blowing pigment over a hand held against a wall, are found from over 35,000 years ago in Asia and Europe, after that stencilling has been used as a historic painting technique on all kinds of materials. In Europe, from about 1450 they were used to colour old master prints printed in black and white. This was especially the case with playing-cards, which continued to be coloured by stencil long after most other subjects for prints were left in black, stencils were used for mass publications, as the type did not have to be hand-written. Low wages contributed to the popularity of the highly labour-intensive process, when stencils are used in this way they are often called pochoir. In the pochoir process, a print with the outlines of the design was produced, to produce detail, a collotype could be produced which the colors were then stenciled over. Pochoir was frequently used to create prints of intense color, and is most often associated with Art Nouveau, a template is used to create an outline for the image. Stencils templates can be made any material which will hold its form, ranging from plain paper, cardboard, plastic sheets, metals. Stencils are frequently used by organizations, including the military, utility companies and governments, to quickly and clearly label objects, vehicles. Stencils for official application can be customized, or purchased as individual letters, numbers and this allows the user to arrange words, phrases and other labels from one set of templates, unique to the item being labeled
2.
Surgery
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An act of performing surgery may be called a surgical procedure, operation, or simply surgery. In this context, the verb means to perform surgery. The adjective surgical means pertaining to surgery, e. g. surgical instruments or surgical nurse, the patient or subject on which the surgery is performed can be a person or an animal. A surgeon is a person who practices surgery and an assistant is a person who practices surgical assistance. A surgical team is made up of surgeon, surgeons assistant, anesthesia provider, circulating nurse, Surgery usually spans minutes to hours, but it is typically not an ongoing or periodic type of treatment. The term surgery can also refer to the place where surgery is performed, or simply the office of a physician, dentist, Surgery is a technology consisting of a physical intervention on tissues. As a general rule, a procedure is considered surgical when it involves cutting of a patients tissues or closure of a previously sustained wound, surgical procedures are commonly categorized by urgency, type of procedure, body system involved, degree of invasiveness, and special instrumentation. Based on timing, Elective surgery is done to correct a condition, and is carried out at the patients request, subject to the surgeons. A semi-elective surgery is one that must be done to avoid permanent disability or death, emergency surgery is surgery which must be done promptly to save life, limb, or functional capacity. Based on purpose, Exploratory surgery is performed to aid or confirm a diagnosis, therapeutic surgery treats a previously diagnosed condition. Cosmetic surgery is done to improve the appearance of an otherwise normal structure. By type of procedure, Amputation involves cutting off a part, usually a limb or digit. Resection is the removal of all or part of an organ or part of the body. Replantation involves reattaching a severed body part, reconstructive surgery involves reconstruction of an injured, mutilated, or deformed part of the body. Excision is the cutting out or removal of an organ, tissue, transplant surgery is the replacement of an organ or body part by insertion of another from different human into the patient. Removing an organ or body part from a human or animal for use in transplant is also a type of surgery. By body part, When surgery is performed on one system or structure. Examples include cardiac surgery, gastrointestinal surgery, and orthopedic surgery, by contrast, an open surgical procedure such as a laparotomy requires a large incision to access the area of interest
3.
Utility knife
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A utility knife is a knife used for general or utility purposes. Craft knives are mostly used for crafts. Today, the utility knife also includes small folding or retractable-blade knives suited for use in the modern workplace or in the construction industry. There is also a utility knife for kitchen use which is between a chefs knife and paring knife in size, the fixed-blade utility knife was developed some 500,000 years ago, when human ancestors began to make knives made of stone. These knives were general-purpose tools, designed for cutting and shaping wooden implements, scraping hides, preparing food, by the 19th century the fixed-blade utility knife had evolved into a steel-bladed outdoors field knife capable of butchering game, cutting wood, and preparing campfires and meals. With the invention of the backspring, pocket-size utility knives were introduced with folding blades and other folding tools designed to increase the utility of the overall design. The folding pocketknife and utility tool is typified by the Camper or Boy Scout pocketknife, the U. S. folding utility knife, the Swiss Army Knife, the fixed or folding blade utility knife is popular for both indoor and outdoor use. One of the most popular types of utility knife is the retractable or folding utility knife. These types of utility knives are designed as cutting tools for use in a variety of trades. In British, Australian and New Zealand English, along with Dutch and Austrian German and this name is a genericised trademark named after Stanley Works, a manufacturer of such knives. In Israel and Switzerland, these knives are known as Japanese knives, in Brazil they are known as estiletes or cortadores Olfa. In Portugal and Canada they are known as X-Acto. In India, the Philippines, France, Italy, Egypt, in the Flemish region of Belgium it is called cuttermes. In Turkey, they are known as maket bıçağı, other names for the tool are box cutter or boxcutter, razor blade knife, razor knife, carpet knife, pen knife, stationery knife, sheetrock knife, or drywall knife. Utility knives may use fixed, folding, or retractable or replaceable blades, large fixed-blade utility knives are most often employed in an outdoors context, such as fishing, camping, or hunting. Outdoor utility knives typically feature sturdy blades from 100 to 150 millimetres in length, with edge geometry designed to resist chipping, the term utility knife may also refer to small fixed-blade knives used for crafts, model-making and other artisanal projects. These small knives feature light-duty blades best suited for cutting thin, the small, thin blade and specialized handle permit cuts requiring a high degree of precision and control. The largest construction or workplace utility knives typically feature retractable and replaceable blades, some use standard razor blades, others specialized double-ended utility blades
4.
Laser scalpel
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A laser scalpel is a scalpel for surgery, cutting or ablating living biological tissue by the energy of laser light. The laser scalpel was invented in 1964, in soft tissue laser surgery, a laser beam ablates or vaporizes the soft tissue with high water content. Diode, Nd, and Er, YAG, and CO2 lasers are used most commonly in soft tissue surgery, CO2 lasers are best for cutting soft tissue because their wavelength is most absorbed by water. The focused CO2 laser beam vaporizes tissue precisely, with little damage to surrounding tissues. The surgical outcome is thus safe and predictable, the CO2 laser is used in virtually all soft tissue procedures, including face lifts, tumor excision, and surgeries in the oral cavity. CO2 laser surgery is praised for minimized bleeding, less swelling and discomfort, reduced infection risk, applications include oral surgery, periodontal surgery, oncological surgery, among many others. In ophthalmology, excimer lasers are used for changing the shape of the cornea, procedures known as LASIK, other surgical fields where the use of a laser scalpel is common are circumcision, neurosurgery and vascular surgery. For research use in biology, special laser micro-scalpels can make cuts smaller than a single cell. Laser lancets, e. g. Lasette or LaserDoc, are used as a less painful alternative for drawing small amounts of capillary blood, an adjustable-power flashlamp or diode pumped pulsed Er, YAG laser is typically used. A150 mJ pulse can vaporize a 0.025 mm2 of skin to 0.5 mm depth. Today diode lasers, Nd, YAG and Er, YAG, and CO2 lasers are most commonly used, instruments used in general surgery Dental laser Laser surgery Soft-tissue laser surgery D. H. Sliney, S. L
5.
Dissection
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Dissection, is the dismembering of the body of a deceased animal or plant to study its anatomical structure. Autopsy is used in pathology and forensic medicine to determine the cause of death in humans and it is carried out by or demonstrated to biology and anatomy students in high school and medical school. Less advanced courses typically focus on subjects, such as small formaldehyde-preserved animals. Consequently, dissection is typically conducted in a morgue or in an anatomy lab, dissection has been used for centuries to explore anatomy. Objections to the use of cadavers have led to the use of alternatives including virtual dissection of computer models, plant and animal bodies are dissected to analyze the structure and function of its components. Dissection is practised by students in courses of biology, botany, zoology, and veterinary science, in medical schools, students dissect human cadavers to learn anatomy. Dissection is used to help to determine the cause of death in autopsy and is an part of forensic medicine. A key principle in the dissection of human cadavers is the prevention of disease to the dissector. Specimens are dissected in morgues or anatomy labs, when provided, they are evaluated for use as a fresh or prepared specimen. A fresh specimen may be dissected within some days, retaining the characteristics of a living specimen, a prepared specimen may be preserved in solutions such as formalin and pre-dissected by an experienced anatomist, sometimes with the help of a diener. This preparation is sometimes called prosection, most dissection involves the careful isolation and removal of individual organs, called the Virchow technique. An alterative more cumbersome technique involves the removal of the organ body. This technique allows a body to be sent to a director without waiting for the sometimes time-consuming dissection of individual organs. Dissection of individual organs involves accessing the area in which the organ is situated, for example, when removing the heart, connects such as the superior vena cava and inferior vena cava are separated. If pathological connections exist, such as a fibrous pericardium, then this may be deliberately dissected along with the organ, Human dissections were carried out by the Greek physicians Herophilus of Chalcedon and Erasistratus of Chios in the early part of the third century BC. During this period, the first exploration into full human anatomy was performed rather than a base knowledge gained from problem-solution delving, before and after this time investigators appeared to largely limit themselves to animals. While there was a taboo within the Greek culture concerning human dissection. For a time, Roman law forbade dissection and autopsy of the human body, Galen, for example, dissected the Barbary macaque and other primates, assuming their anatomy was basically the same as that of humans
6.
Handicraft
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One of the worlds oldest handicraft is Dhokra, this is a sort of metal casting has been used in India for over 4,000 years and is still used. Collective terms for handicrafts include artisanry, handicrafting, crafting, many handicrafters use natural, even entirely indigenous, materials while others may prefer modern, non-traditional materials, and even upcycle industrial materials. The individual artisanship of an item is the paramount criterion. Most crafts require the development of skill and the application of patience, like folk art, handicraft output often has cultural and/or religious significance, and increasingly may have a political message as well, as in craftivism. The Arts and Crafts movement originated as a late 19th-century design reform and social movement principally in Europe, North America and Australia and this was held up in contrast to what was perceived to be the alienating effects of industrial labor. These activities were called crafts because originally many of them were professions under the guild system, adolescents were apprenticed to a master craftsman, and refined their skills over a period of years in exchange for low wages. Simple arts and crafts projects are an elementary and middle school activity in both mainstream and alternative education systems around the world. e. The use of traditional handicrafting techniques by professional fine artists, many community centers and schools run evening or day classes and workshops, for adults and children, offering to teach basic craft skills in a short period of time. If sold, they are sold in Direct sales, Gift shops, Public markets, in developing countries, handicrafts are sold to locals and as Souvenirs to tourists. Sellers tend to speak at least a few words of common tourist languages
7.
Tempered steel
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Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. The exact temperature determines the amount of hardness removed, and depends on both the composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy. The reduction in hardness is usually accompanied by an increase in ductility, tempering is usually performed after quenching, which is rapid cooling of the metal to put it in its hardest state. Tempering is accomplished by controlled heating of the quenched work-piece to a temperature below its critical temperature. Heating above this temperature is avoided, so as not to destroy the very-hard, quenched microstructure, precise control of time and temperature during the tempering process is crucial to achieve the desired balance of physical properties. Low tempering temperatures may only relieve the stresses, decreasing brittleness while maintaining a majority of the hardness. Higher tempering temperatures tend to produce a reduction in the hardness, sacrificing some yield strength. In carbon steels, tempering alters the size and distribution of carbides in the martensite, tempering is also performed on normalized steels and cast irons, to increase ductility, machinability, and impact strength. Tempering is an ancient heat-treating technique, the oldest known example of tempered martensite is a pick axe which was found in Galilee, dating from around 1200 to 1100 BC. The process was used throughout the ancient world, from Asia to Europe, tempering was often confused with quenching and, often, the term was used to describe both techniques. I shall employ the word tempering in the sense as softening. In metallurgy, one may encounter many terms that have specific meanings within the field. Terms such as hardness, impact resistance, toughness, and strength can carry many different connotations, some of the terms encountered, and their specific definitions are, Strength, also called rigidity, this is resistance to permanent deformation and tearing. Strength, in metallurgy, is still a vague term, so is usually divided into yield strength, tensile strength, shear strength. Toughness, Resistance to fracture, as measured by the Charpy test, toughness often increases as strength decreases, because a material that bends is less likely to break. Hardness, Hardness is often used to strength or rigidity but, in metallurgy. In conventional metal alloys, there is a relation between indentation hardness and tensile strength, which eases the measurement of the latter
8.
Stainless steel
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In metallurgy, stainless steel, also known as inox steel or inox from French inoxydable, is a steel alloy with a minimum of 10. 5% chromium content by mass. Stainless steel is notable for its resistance, and it is widely used for food handling. Stainless steel does not readily corrode, rust or stain with water as ordinary steel does, however, it is not fully stain-proof in low-oxygen, high-salinity, or poor air-circulation environments. There are various grades and surface finishes of stainless steel to suit the environment the alloy must endure, Stainless steel is used where both the properties of steel and corrosion resistance are required. Stainless steel differs from carbon steel by the amount of chromium present, unprotected carbon steel rusts readily when exposed to air and moisture. This iron oxide film is active and accelerates corrosion by making it easier for more iron oxide to form, since iron oxide has lower density than steel, the film expands and tends to flake and fall away. In comparison, stainless steels contain sufficient chromium to undergo passivation and this layer prevents further corrosion by blocking oxygen diffusion to the steel surface and stops corrosion from spreading into the bulk of the metal. Passivation occurs only if the proportion of chromium is high enough, Stainless steel’s resistance to corrosion and staining, low maintenance, and familiar lustre make it an ideal material for many applications. Storage tanks and tankers used to transport orange juice and other food are made of stainless steel. This also influences its use in kitchens and food processing plants, as it can be steam-cleaned and sterilized. High oxidation resistance in air at ambient temperature is achieved with addition of a minimum of 13% chromium. The chromium forms a layer of chromium oxide when exposed to oxygen. The layer is too thin to be visible, and the metal remains lustrous, the layer is impervious to water and air, protecting the metal beneath, and this layer quickly reforms when the surface is scratched. This phenomenon is called passivation and is seen in other metals, corrosion resistance can be adversely affected if the component is used in a non-oxygenated environment, a typical example being underwater keel bolts buried in timber. When stainless steel parts such as nuts and bolts are forced together, when forcibly disassembled, the welded material may be torn and pitted, a destructive effect known as galling. Galling can be avoided by the use of materials for the parts forced together, for example bronze and stainless steel. However, two different alloys electrically connected in a humid, even mildly acidic environment may act as a voltaic pile, nitronic alloys, made by selective alloying with manganese and nitrogen, may have a reduced tendency to gall. Additionally, threaded joints may be lubricated to provide a film between the two parts and prevent galling, low-temperature carburizing is another option that virtually eliminates galling and allows the use of similar materials without the risk of corrosion and the need for lubrication
9.
High carbon steel
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The term carbon steel may also be used in reference to steel which is not stainless steel, in this use carbon steel may include alloy steels. As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating, however, regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the carbon content lowers the melting point. Mild steel, also known as steel and Low carbon steel. It is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications, mild steel contains approximately 0. 05–0. 25% carbon making it malleable and ductile. Mild steel has a low tensile strength, but it is cheap and easy to form. It is often used large quantities of steel are needed. The density of steel is approximately 7.85 g/cm3. Low-carbon steels suffer from yield-point runout where the material has two yield points, the first yield point is higher than the second and the yield drops dramatically after the upper yield point. If a low-carbon steel is only stressed to some point between the upper and lower yield point then the surface develop Lüder bands, low-carbon steels contain less carbon than other steels and are easier to cold-form, making them easier to handle. Carbon steels which can successfully undergo heat-treatment have a content in the range of 0. 30–1. 70% by weight. Trace impurities of other elements can have a significant effect on the quality of the resulting steel. Trace amounts of sulfur in particular make the steel red-short, that is, brittle, low-alloy carbon steel, such as A36 grade, contains about 0. 05% sulfur and melts around 1, 426–1,538 °C. Manganese is often added to improve the hardenability of low-carbon steels and these additions turn the material into a low-alloy steel by some definitions, but AISIs definition of carbon steel allows up to 1. 65% manganese by weight. Carbon steel is broken down into four classes based on content,0.05 to 0. 25% carbon content. Balances ductility and strength and has good resistance, used for large parts, forging. Very strong, used for springs, swords, and high-strength wires, steels that can be tempered to great hardness. Used for special purposes like knives, axles or punches, most steels with more than 2. 5% carbon content are made using powder metallurgy
10.
Titanium
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Titanium is a chemical element with symbol Ti and atomic number 22. It is a transition metal with a silver color, low density. Titanium is resistant to corrosion in sea water, aqua regia, titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and it is named by Martin Heinrich Klaproth for the Titans of Greek mythology. The metal is extracted from its principal mineral ores by the Kroll, the most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride, a component of smoke screens and catalysts, and titanium trichloride, the two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, there are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant. Although they have the number of valence electrons and are in the same group in the periodic table. As a metal, titanium is recognized for its high strength-to-weight ratio and it is a strong metal with low density that is quite ductile, lustrous, and metallic-white in color. The relatively high melting point makes it useful as a refractory metal and it is paramagnetic and has fairly low electrical and thermal conductivity. Commercial grades of titanium have ultimate tensile strength of about 434 MPa, equal to that of common, low-grade steel alloys, titanium is 60% denser than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys achieve tensile strengths of over 1400 MPa, however, titanium loses strength when heated above 430 °C. Titanium is not as hard as some grades of heat-treated steel, it is non-magnetic, machining requires precautions, because the material might gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a limit that guarantees longevity in some applications. The metal is an allotrope of an hexagonal α form that changes into a body-centered cubic β form at 882 °C. The specific heat of the α form increases dramatically as it is heated to this transition temperature but then falls, similar to zirconium and hafnium, an additional omega phase exists, which is thermodynamically stable at high pressures, but metastable at ambient pressures. This phase is usually hexagonal or trigonal and can be considered to be due to a soft longitudinal acoustic phonon of the β phase causing collapse of planes of atoms, like aluminium and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air. Titanium readily reacts with oxygen at 1,200 °C in air and it is, however, slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation. When it first forms, this layer is only 1–2 nm thick but continues to grow slowly
11.
Ceramic knife
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A ceramic knife is a knife made out of very hard and tough ceramic, often zirconium dioxide. These knives are produced by dry-pressing zirconia powder and firing them through solid-state sintering. The resultant blade is sharpened by grinding the edges with a grinding wheel. Zirconia is 8.5 on the Mohs scale of mineral hardness and this very hard edge significantly reduces the need for sharpening. Zirconium oxide is used due to its polymorphism and it exists in three phases, monoclinic, tetragonal and cubic. Cooling to the phase after sintering causes a large volume change. Additives such as magnesia, calcia and yttria are used in the manufacture of the material to stabilize the high-temperature phases. The highest strength and toughness is produced by the addition of 3 mol% yttrium oxide yielding partially stabilized zirconia and this material consists of a mixture of tetragonal and cubic phases with a bending strength of nearly 1,200 MPa. Small cracks allow phase transformations to occur, which close the cracks and prevent catastrophic failure, resulting in a relatively tough ceramic material. Ceramic knives are substantially harder than steel knives, will not corrode in harsh environments, are non-magnetic, since ceramics are brittle, blades may break if dropped on a hard surface although better manufacturing processes have reduced this risk. They are also unsuitable for chopping through bones, or frozen foods, or in applications which require prying. Several brands now offer either a black-coloured or a blade made through an additional hot isostatic pressing step. The inherent hardness of the material also makes it more difficult for the consumer to resharpen. Media related to Ceramic knives at Wikimedia Commons
12.
Diamond
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Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material and those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron, small amounts of defects or impurities color diamond blue, yellow, brown, green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers in the Earths mantle. Carbon-containing minerals provide the source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the Earths surface through deep volcanic eruptions by magma, Diamonds can also be produced synthetically in a HPHT method which approximately simulates the conditions in the Earths mantle. An alternative, and completely different growth technique is chemical vapor deposition, several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have developed to distinguish natural diamonds, synthetic diamonds. The word is from the ancient Greek ἀδάμας – adámas unbreakable, the name diamond is derived from the ancient Greek αδάμας, proper, unalterable, unbreakable, untamed, from ἀ-, un- + δαμάω, I overpower, I tame. Diamonds have been known in India for at least 3,000 years, Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history, later in 1797, the English chemist Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas, the most familiar uses of diamonds today are as gemstones used for adornment, a use which dates back into antiquity, and as industrial abrasives for cutting hard materials. The dispersion of light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology developed methods of grading diamonds, four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds, these are carat, cut, color, and clarity. A large, flawless diamond is known as a paragon and these conditions are met in two places on Earth, in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike. The conditions for diamond formation to happen in the mantle occur at considerable depth corresponding to the requirements of temperature and pressure
13.
Obsidian
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Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth, Obsidian is commonly found within the margins of rhyolitic lava flows known as obsidian flows, where the chemical composition induces a high viscosity and polymerization degree of the lava. The inhibition of atomic diffusion through this highly viscous and polymerized lava explains the lack of crystal growth. Obsidian is hard and brittle, it therefore fractures with very sharp edges, which were used in the past in cutting and piercing tools, among the various forms of glass we may reckon Obsidian glass, a substance very similar to the stone found by Obsidius in Ethiopia. Obsidian is the rock formed as a result of quickly cooled lava, tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now adhere to this hypothesis. Obsidian is mineral-like, but not a true mineral because as a glass it is not crystalline, in addition and it is sometimes classified as a mineraloid. Though obsidian is usually dark in color similar to mafic rocks such as basalt, Obsidian consists mainly of SiO2, usually 70% or more. Crystalline rocks with obsidians composition include granite and rhyolite, because obsidian is metastable at the Earths surface, no obsidian has been found that is older than Cretaceous age. This breakdown of obsidian is accelerated by the presence of water, having a low water content when newly formed, typically less than 1% water by weight, obsidian becomes progressively hydrated when exposed to groundwater, forming perlite. Pure obsidian is usually dark in appearance, though the color varies depending on the presence of impurities, iron and other transition elements may give the obsidian a dark brown to black color. Very few samples are nearly colorless, in some stones, the inclusion of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern. Obsidian may contain patterns of gas bubbles remaining from the lava flow and these bubbles can produce interesting effects such as a golden sheen. An iridescent, rainbow-like sheen is caused by inclusions of magnetite nanoparticles, Obsidian can be found in locations which have experienced rhyolitic eruptions. Obsidian can also be found in the eastern U. S. states of Virginia, as well as Pennsylvania, there are only four major deposit areas in the central Mediterranean, Lipari, Pantelleria, Palmarola and Monte Arci. Ancient sources in the Aegean were Milos and Gyali, acıgöl town and the Göllü Dağ volcano were the most important sources in central Anatolia, one of the more important source areas in the prehistoric Near East. Use of obsidian in pottery of the Neolithic in the area around Lipari was found to be less at a distance representing two weeks journeying. Anatolian sources of obsidian are known to have been the used in the Levant. The first attested civilized use is from excavations at Tell Brak dated the late fifth millennia, Obsidian was valued in Stone Age cultures because, like flint, it could be fractured to produce sharp blades or arrowheads
14.
Artifact (medical imaging)
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In natural science and signal processing, an artifact is any error in the perception or representation of any information introduced by the involved equipment or technique. In computer science, digital artifacts are introduced into digital signals as a result of digital processing. In microscopy, artifacts are introduced during the processing of samples into slide form. Such an artifact may be called a statistical artifact, physicians typically learn to recognize some of these artifacts to avoid mistaking them for actual pathology. In medical electrophysiological monitoring, artifacts are anomalous signals that originate from some other than the electrophysiological structure being studied. Offending artifacts may obscure, distort, or completely misrepresent the true underlying electrophysiological signal sought, in radar signal processing, some echoes can be related to fix targets, multipath returns, jamming, atmospheric effect, anomalous propagation, and many other effects. Visual artifact, in imaging, any unwanted visual alteration introduced by the imaging equipment, compression artifact, in computer graphics, distortion of media by the data compression
15.
Silver
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Silver is a metallic element with symbol Ag and atomic number 47. The symbol Ag stems from Latin argentum, derived from the Greek ὰργὀς, a soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earths crust in the pure, free form, as an alloy with gold and other metals. Most silver is produced as a byproduct of copper, gold, lead, Silver is more abundant than gold, but it is much less abundant as a native metal. Its purity is measured on a per mille basis, a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had a role in most human cultures. Silver has long valued as a precious metal. Silver metal is used in many premodern monetary systems in bullion coins, Silver is used in numerous applications other than currency, such as solar panels, water filtration, jewelry, ornaments, high-value tableware and utensils, and as an investment medium. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings, Silver compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings, catheters. Silver is similar in its physical and chemical properties to its two neighbours in group 11 of the periodic table, copper and gold. This distinctive electron configuration, with an electron in the highest occupied s subshell over a filled d subshell. Silver is a soft, ductile and malleable transition metal. Silver crystallizes in a cubic lattice with bulk coordination number 12. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak and this observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant white metallic luster that can take a polish. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm, at wavelengths shorter than 450 nm, silvers reflectivity is inferior to that of aluminium and drops to zero near 310 nm. The electrical conductivity of silver is the greatest of all metals, greater even than copper, during World War II in the US,13540 tons of silver were used in electromagnets for enriching uranium, mainly because of the wartime shortage of copper
16.
Cauterization
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Cauterization is a medical practice or technique of burning a part of a body to remove or close off a part of it. It destroys some tissue in an attempt to mitigate bleeding and damage, remove a growth, or minimize other potential medical harm. The practice was widespread for treatment of wounds. Actual cautery refers to the device, generally heated to a dull red glow, that a physician applies to produce blisters, to stop bleeding of a blood vessel. The main forms of cauterization used today in the first world are electrocautery and chemical cautery—both are, for example, cautery can also mean the branding of a human, either recreational or forced. Cauterization was used to heavy bleeding, especially during amputation. The procedure was simple, a piece of metal was heated over fire and this caused tissues and blood to heat rapidly to extreme temperatures, causing coagulation of the blood and thus controlling the bleeding, at the cost of extensive tissue damage. Cauterization was a treatment in the Middle Ages, sometimes unintentionally as with Saint Huberts Key. Cautery is described in the Hippocratic Corpus, the cautery was employed for almost every possible purpose in ancient times, as a counter-irritant, as a haemostatic, as a bloodless knife, as a means of destroying tumours, etc. Later, special medical instruments called cauters were used to cauterize arteries, the technique of ligature of the arteries as an alternative to cauterization was later improved and used more effectively by Ambroise Paré. Electrocauterization is the process of destroying tissue using heat conduction from a metal probe heated by electric current, the procedure stops bleeding from small vessels. Electrocautery applies high frequency alternating current by a unipolar or bipolar method and it can be a continuous waveform to cut tissue, or intermittent to coagulate tissue. In unipolar cauterization, the contacts the tissue with a single small electrode. The circuits exit point is a surface area, such as the buttocks. The amount of heat generated depends on size of area, power setting or frequency of current, duration of application. Constant waveform generates more heat than intermittent, frequency used in cutting the tissue is higher than in coagulation mode. Bipolar electrocautery passes the current between two tips of a forceps-like tool and it has the advantage of not disturbing other electrical body rhythms and also coagulates tissue by pressure. Lateral thermal injury is greater in unipolar than bipolar devices, electrocauterization is preferable to chemical cauterization, because chemicals can leach into neighbouring tissue and cauterize outside of intended boundaries
17.
Laser
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A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term laser originated as an acronym for light amplification by stimulated emission of radiation, the first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light coherently, spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances, Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum, i. e. they can emit a single color of light. Temporal coherence can be used to produce pulses of light as short as a femtosecond, Lasers are distinguished from other light sources by their coherence. Spatial coherence is typically expressed through the output being a narrow beam, Laser beams can be focused to very tiny spots, achieving a very high irradiance, or they can have very low divergence in order to concentrate their power at a great distance. Temporal coherence implies a polarized wave at a single frequency whose phase is correlated over a great distance along the beam. A beam produced by a thermal or other incoherent light source has an amplitude and phase that vary randomly with respect to time and position. Lasers are characterized according to their wavelength in a vacuum, most single wavelength lasers actually produce radiation in several modes having slightly differing frequencies, often not in a single polarization. Although temporal coherence implies monochromaticity, there are lasers that emit a broad spectrum of light or emit different wavelengths of light simultaneously, there are some lasers that are not single spatial mode and consequently have light beams that diverge more than is required by the diffraction limit. However, all devices are classified as lasers based on their method of producing light. Lasers are employed in applications where light of the spatial or temporal coherence could not be produced using simpler technologies. The word laser started as an acronym for light amplification by stimulated emission of radiation, in the early technical literature, especially at Bell Telephone Laboratories, the laser was called an optical maser, this term is now obsolete. A laser that produces light by itself is technically an optical rather than an optical amplifier as suggested by the acronym. It has been noted that the acronym LOSER, for light oscillation by stimulated emission of radiation. With the widespread use of the acronym as a common noun, optical amplifiers have come to be referred to as laser amplifiers. The back-formed verb to lase is frequently used in the field, meaning to produce light, especially in reference to the gain medium of a laser. Further use of the laser and maser in an extended sense, not referring to laser technology or devices, can be seen in usages such as astrophysical maser
18.
General surgery
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General surgery is a surgical specialty that focuses on abdominal contents including esophagus, stomach, small bowel, colon, liver, pancreas, gallbladder and bile ducts, and often the thyroid gland. They also deal with diseases involving the skin, breast, soft tissue, trauma, peripheral vascular surgery, some general surgeons obtain advanced training in this field and specialty certification surgical critical care. General surgeons must be able to deal initially with almost any surgical emergency and they are also called upon to staff surgical intensive care units or trauma intensive care units. All general surgeons are trained in emergency surgery, bleeding, infections, bowel obstructions and organ perforations are the main problems they deal with. Cholecystectomy, the removal of the gallbladder, is one of the most common surgical procedures done worldwide. This is most often done electively, but the gallbladder can become acutely inflamed, ruptures of the appendix and small bowel obstructions are other common emergencies. This is a new specialty dealing with minimal access techniques using cameras. Robotic surgery is now evolving from this concept, gallbladders, appendices, and colons can all be removed with this technique. Hernias are now repaired mostly laparoscopically, most bariatric surgery is performed laparoscopically. General surgeons that are trained today are expected to be proficient in laparoscopic procedures, General surgeons perform a majority of all non-cosmetic breast surgery from lumpectomy to mastectomy, especially pertaining to the evaluation and diagnosis, of breast cancer. General surgeons can perform vascular surgery if they receive special training, otherwise, these procedures are performed by vascular surgery specialists. However, general surgeons are capable of treating minor vascular disorders, General surgeons are trained to remove all or part of the thyroid and parathyroid glands in the neck and the adrenal glands just above each kidney in the abdomen. In many communities, they are the only trained to do this. In communities that have a number of subspecialists, other subspecialty surgeons may assume responsibility for these procedures, responsible for all aspects of pre-operative, operative, and post-operative care of abdominal organ transplant patients. Transplanted organs include liver, kidney, pancreas, and more rarely small bowel, Surgical oncologist refers to a general surgical oncologist, but thoracic surgical oncologists, gynecologist and so forth can all be considered surgeons who specialize in treating cancer patients. e. The more cancer cases a surgeon treats, the more proficient he or she becomes and this is particularly true of complex cancer resections such as pancreaticoduodenectomy for pancreatic cancer, and gastrectomy with extended lymphadenectomy for gastric cancer. Most cardiothoracic surgeons in the U. S. first complete a general surgery residency, pediatric surgery is a subspecialty of general surgery. Pediatric surgeons do surgery on patients age lower than 18, pediatric surgery is 5–7 years of residency and a 2-3 year fellowship
19.
Graphic design
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Graphic design is the process of visual communication and problem-solving using one or more of typography, photography and illustration. The field is considered a subset of visual communication and communication design, Graphic designers create and combine symbols, images and text to form visual representations of ideas and messages. They use typography, visual arts and page layout techniques to create visual compositions, common uses of graphic design include corporate design, editorial design, wayfinding or environmental design, advertising, web design, communication design, product packaging and signage. The term graphic design was coined by William Addison Dwiggins in 1922, however, graphic design-like activities span human existence, from the caves of Lascaux, to Romes Trajans Column to the illuminated manuscripts of the Middle Ages, to the neon lights of Ginza, Tokyo. In Babylon, artisans pressed cuneiform inscriptions into clay bricks or tablets which were used for construction, the bricks gave information such as the name of the reigning monarch, the builder, or some other dignitary. This was the first known road sign announcing the name of the governor of a state or mayor of the city, the Egyptians developed communication by hieroglyphics that used picture symbols dating as far back as 136 B. C. found on the Rosetta Stone. During the Dark Ages, from 500 AD to 1450 AD, monks created elaborate and they share many elements, theories, principles, practices, languages and sometimes the same benefactor or client. In advertising, the objective is the sale of goods. In graphic design, the essence is to order to information, form to ideas, expression. Graphic design in the United States began with Benjamin Franklin who used his newspaper The Pennsylvania Gazette, to master the art of publicity to promote his own books and his invention is still sold today and is known as the Franklin stove. American advertising initially imitated British newspapers and magazines, advertisements were printed in scrambled type and uneven lines that made it difficult to read. Franklin better organized this by adding 14-point type for the first line of the advertisement, although later shortened and centered it, Franklin added illustrations, something that London printers had not attempted. Franklin was the first to utilize logos, which were early symbols that announced such services as opticians by displaying golden spectacles, Franklin taught advertisers that the use of detail was important in marketing their products. Some advertisements ran for 10-20 lines, including color, names, varieties, during the Tang Dynasty wood blocks were cut to print on textiles and later to reproduce Buddhist texts. A Buddhist scripture printed in 868 is the earliest known printed book, beginning in the 11th century, longer scrolls and books were produced using movable type printing, making books widely available during the Song dynasty. During the 17th-18th century movable type was used for handbills or trade cards which were printed from wood or copper engravings and these documents announced a business and its location. English painter William Hogarth used his skill in engraving was one of the first to design for business trade, in Mainz Germany, in 1448, Johann Gutenberg introduced movable type using a new metal alloy for use in a printing press and opened a new era of commerce. Previously, most advertising was word of mouth, in France and England, for example, criers announced products for sale just as ancient Romans had done
20.
Knurling
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Knurling is a manufacturing process, typically conducted on a lathe, whereby a pattern of straight, angled or crossed lines is cut or rolled into the material. The operation is performed for producing indentations on a part of a workpiece, Knurling allows hands or fingers to get a better grip on the knurled object than would be provided by the originally smooth metal surface. Occasionally, the pattern is a series of straight ridges or a helix of straight ridges rather than the more-usual criss-cross pattern. Knurling may also be used as a method, because a rolled-in knurled surface has raised-up areas surrounding the depressed areas. As auto parts have become less expensive, knurling has become less prevalent than it once was, Knurling can also be used when a component will be assembled into a low precision component, for example a metal pin into a plastic molding. The outer surface of the pin is knurled so that the raised detail bites into the plastic irrespective of whether the size of the hole in the plastic closely matches the diameter of the pin. Tool handles, mechanical pencils, barbell bars, and the knobs on electronic equipment are frequently knurled. Knurling is also used on the grips of darts and the footpegs of BMX bicycles, aside from adding functionality to an object, knurling also adds a decorative pattern to the material. The knurled nut is one application, which uses a knurled finish instead of hexagonal or square edges which helps in tightening or loosening the nut without the use of a tool. The knurled surfaces provide enough grip to hold the nut between the thumb and forefinger, hence it is also called a thumb nut. It is mainly used on small diameter bolts, knurled nuts are typically used in electrical components, musical instruments and in automobiles. More common than knurl cutting, knurl rolling is usually accomplished using one or more very hard rollers that contain the reverse of the pattern to be imposed. It is possible for a straight knurl to be pressed with a roller, however the material needs to be supported adequately to avoid deformation. A criss-cross pattern can be accomplished using any of, A single roller that contains the reverse of the desired pattern. The integer number of knurls for any given diameter typically varies by three repetitions from the bottom to the top of the pattern. By comparison, for cut knurls, the spacing of the cuts is not preset and these resemble pipecutters but contain knurling wheels rather than cutting wheels. Usually, three wheels are carried by the tool, two left-handed wheels and one right-handed wheel or vice versa, Annular rings Frequently used when the mating part is plastic. Rings allow for easy mating but ridges make it difficult to pull the components apart, Linear knurl Used with mating plastic pieces, the Linear Knurl allows greater torsion between components
21.
X-Acto
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X-Acto is a brand name for a variety of cutting tools and office products owned by Elmers Products, Inc. Cutting tools include hobby and utility knives, saws, carving tools and many small-scale precision knives used for crafts, an X-Acto knife may be called a utility knife, precision knife or hobby knife. It is a blade mounted on an aluminium body, used for crafting and hobbies. A knurled collar loosens and tightens an aluminium collet with one slot, there are numerous other knives on the market with very similar designs. Blades are typically interchangeable between different brands, the original knife was invented in the 1930s by Sundel Doniger, a Jewish Polish immigrant to the United States. He had planned to sell it to surgeons as a scalpel but it was not acceptable and his brother-in-law, Daniel Glück, suggested that it might be a good craft tool. In addition to knives, blades and tools, X-Acto produces office supplies including pencil sharpeners, paper trimmers, staplers, X-Acto sharpeners are electric, battery or manual. X-Acto has three types of trimmers, razor, rotary, and guillotine, through 2012, X-Acto sold ceramic and convection space heaters and fans under the Boston brand name. Knife Scalpel Arts and crafts Wood carving Office supplies Olfa Official website X-Acto on Facebook
22.
Straightedge
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A straightedge is a tool with an edge free from curves, or straight, used for transcribing straight lines, or checking the straightness of lines. If it has equally spaced markings along its length, it is called a ruler. Straightedges are used in the service and machining industry to check the flatness of machined mating surfaces. A pair of straightedges called winding sticks are used in woodworking to amplify twist in pieces of wood, an idealized straightedge is used in compass-and-straightedge constructions in plane geometry. It may be used, Given two points, to draw the line connecting them, Given a point and a circle, to draw either tangent. Given two circles, to any of their common tangents. It may not be marked or used together with the compass so as to transfer the length of one segment to another and it is possible to do all compass and straightedge constructions without the straightedge. That is, it is possible, using only a compass and it is not, however, possible to do all constructions using only a straightedge. It is possible to do them with straightedge alone given one circle, chalk line Geometrography Wayne R. Moore, Foundations of Mechanical Accuracy, Moore Special Tool Company, Bridgeport, CT Making Accurate Straight-Edges from Scratch
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Wood carving
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The phrase may also refer to the finished product, from individual sculptures to hand-worked mouldings composing part of a tracery. It therefore forms an important hidden element in the art history of many cultures, outdoor wood sculptures do not last long in most parts of the world, so it is still unknown how the totem pole tradition developed. Many of the most important sculptures of China and Japan in particular are in wood, and so are the majority of African sculpture. Wood is light and can take very fine detail so it is suitable for masks. It is also easier to work on than stone. Some of the finest extant examples of early European wood carving are from the Middle Ages in Germany, Russia, Italy and France, in England, many complete examples remain from the 16th and 17th century, where oak was the preferred medium. The gouge, a tool with a cutting edge used in a variety of forms and sizes for carving hollows, rounds. The coping saw, a saw that is used to cut off chunks of wood at once. The chisel, large and small, whose straight cutting edge is used for lines, the V-tool, used for parting, and in certain classes of flat work for emphasizing lines. The U-Gauge, a deep gouge with a U-shaped cutting edge. Sharpening equipment, such as stones and a strop, necessary for maintaining edges. The nature of the wood being carved limits the scope of the carver in wood is not equally strong in all directions. The direction in which wood is strongest is called grain and it is smart to arrange the more delicate parts of a design along the grain instead of across it. Less commonly, this principle is used in solid pieces of wood. Probably the two most common used for carving in North America are basswood and tupelo, both are hardwoods that are relatively easy to work with. Chestnut, butternut, oak, American walnut, mahogany and teak are also very good woods, while for fine work Italian walnut, sycamore maple, apple, pear, box or plum, are usually chosen. Decoration that is to be painted and of not too delicate a nature is often carved in pine, the type of wood is important. Hardwoods are more difficult to shape but have greater luster and longevity, softer woods may be easier to carve but are more prone to damage
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India
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India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and it is bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast. It shares land borders with Pakistan to the west, China, Nepal, and Bhutan to the northeast, in the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives. Indias Andaman and Nicobar Islands share a border with Thailand. The Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE, in the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, early political consolidations took place under the Maurya and Gupta empires, the later peninsular Middle Kingdoms influenced cultures as far as southeast Asia. In the medieval era, Judaism, Zoroastrianism, Christianity, and Islam arrived, much of the north fell to the Delhi sultanate, the south was united under the Vijayanagara Empire. The economy expanded in the 17th century in the Mughal empire, in the mid-18th century, the subcontinent came under British East India Company rule, and in the mid-19th under British crown rule. A nationalist movement emerged in the late 19th century, which later, under Mahatma Gandhi, was noted for nonviolent resistance, in 2015, the Indian economy was the worlds seventh largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption, malnutrition, a nuclear weapons state and regional power, it has the third largest standing army in the world and ranks sixth in military expenditure among nations. India is a constitutional republic governed under a parliamentary system. It is a pluralistic, multilingual and multi-ethnic society and is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindu, the latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River. The ancient Greeks referred to the Indians as Indoi, which translates as The people of the Indus, the geographical term Bharat, which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. Scholars believe it to be named after the Vedic tribe of Bharatas in the second millennium B. C. E and it is also traditionally associated with the rule of the legendary emperor Bharata. Gaṇarājya is the Sanskrit/Hindi term for republic dating back to the ancient times, hindustan is a Persian name for India dating back to the 3rd century B. C. E. It was introduced into India by the Mughals and widely used since then and its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety
25.
Ancient Egyptian medicine
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The medicine of the ancient Egyptians is some of the oldest documented. Egyptian medical thought influenced later traditions, including the Greeks, until the 19th century, the main sources of information about ancient Egyptian medicine were writings from later in antiquity. The Greek historian Herodotus visited Egypt around 440 BC and wrote extensively of his observations of their medicinal practice, pliny the Elder also wrote favourably of them in historical review. Hippocrates, Herophilos, Erasistratus and later Galen studied at the temple of Amenhotep, in 1822, the translation of the Rosetta stone finally allowed the translation of ancient Egyptian hieroglyphic inscriptions and papyri, including many related to medical matters. The Edwin Smith Papyrus is a textbook on surgery and details anatomical observations and the examination, diagnosis, treatment and it was probably written around 1600 BC, but is regarded as a copy of several earlier texts. Medical information in it dates from as early as 3000 BC and it is thus viewed as a learning manual. Treatments consisted of ointments made from animal, vegetable or fruit substances or minerals, the earliest known surgery to be performed in Egypt occurred around 2750 BC. The Ebers papyrus c.1550 BC is full of incantations and foul applications meant to turn away disease-causing demons and it may also contain the earliest documented awareness of tumors, if the poorly understood ancient medical terminology has been correctly interpreted. The Kahun Gynaecological Papyrus treats womens complaints, including problems with conception, thirty four cases detailing diagnosis and treatment survive, some of them fragmentarily. Dating to 1800 BC, it is the oldest surviving text of any kind. Other documents such as the Hearst papyrus, and Berlin Papyrus also provide insight into ancient Egyptian medicine. Other information comes from the images that often adorn the walls of Egyptian tombs, advances in modern medical technology also contributed to the understanding of ancient Egyptian medicine. Paleopathologists were able to use X-Rays and later CAT Scans to view the bones, electron microscopes, mass spectrometry and various forensic techniques allowed scientists unique glimpses of the state of health in Egypt 4000 years ago. The ancient Egyptians were at least partially aware of the importance of diet, owing to Egypts great endowment of fertile land, food production was never a major issue although of course no matter how bountiful the land, paupers and starvation still exist. The main crops for most of ancient Egyptian history were emmer wheat, barley was also used in beer. Vegetables and fruits of many types were widely grown, oil was produced from the linseed plant and there was a limited selection of spices and herbs. Offerings to King Unas were recorded as and it is clear that the Egyptian diet was not lacking for the upper classes and that even the lower classes may have had some selection. Like many civilizations in the past the ancient Egyptians amply discovered the properties of the plant life around them
26.
Medicine in ancient Rome
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Medicine in ancient Rome combined various techniques using different tools. Ancient Roman medicine was divided into such as ophthalmology and urology. A variety of procedures were carried out using many different instruments including forceps, scalpels. The Roman Empire was a complex and vigorous combination of Greek, later Latin authors, notably Cato and Pliny believed in a specifically Roman type of healing based on herbs, chants, prayers and charms easily available to any head of a household. It was not until the establishment and development of military and political contacts between Greece that Greek medicine made its entry into Italy. However, It was not until the introduction of the healing god Asclepius in 291 BC and this was particularly important from the perspective of the Roman army. Within the scope of the Roman military, there were many medical advancements, Roman medicine was highly influenced by the Greek medical tradition. Similar to Greek physicians, Roman physicians relied on observations to heal the sick rather than spiritual rituals. Tragic famines and plagues were often attributed to divine punishment and appeasement to the deities through rituals was believed to alleviate such events, miasma was perceived to be the root cause of many diseases, whether caused by famine, wars, or plague. The concept of contagion was formulated, resulting in practices of quarantine, one of the first prominent doctors to appear in ancient Rome was Galen. He became an expert on the human anatomy from dissecting animals, due to his prominence and expertise in ancient Rome, Galen became Emperor Marcus Aurelius personal physician. The Romans also conquered the city of Alexandria, which was famous for its comprehensive libraries, in ancient times, Alexandria was an important center for learning, and its Great Library held countless volumes of ancient Greek medical information. The ancient Romans adopted many of the practices and procedures they found in the Great Library into their medical practices, additionally, Greek symbols and gods greatly influenced ancient Roman medicine. The caduceus, pictured right, was associated with the Greek god. Hermes was the Greek God of commerce and he carried a staff wrapped with two snakes, known as the caduceus. This symbol later became associated with the Roman God, Mercury, later during the 7th century, the caduceus became associated with health and medicine due to its association with the Azoth, the alchemical universal solvent. Many Roman doctors came from Greece and strongly believed in achieving the right balance of the four humors, Pedanius Dioscorides, was a Greek botanist, pharmacologist and physician who practised in Rome during the reign of Nero. He became a famous Roman Army doctor, Dioscorides wrote a 5-volume encyclopedia - De Materia Medica - which listed over 600 herbal cures, forming an influential and long-lasting pharmacopeia
27.
Ayurveda
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Ayurveda, or Ayurveda medicine, is a system of medicine with historical roots in the Indian subcontinent. Globalized and modernized practices derived from Ayurveda traditions are a type of complementary or alternative medicine, in the Western world, Ayurveda therapies and practices have been integrated in general wellness applications and as well in some cases in medical use. The main classical Ayurveda texts begin with accounts of the transmission of knowledge from the Gods to sages. In Sushruta Samhita, Sushruta wrote that Dhanvantari, Hindu god of Ayurveda, incarnated himself as a king of Varanasi and taught medicine to a group of physicians, Ayurveda therapies have varied and evolved over more than two millennia. Therapies are typically based on complex compounds, minerals and metal substances. Ancient Ayurveda texts also taught surgical techniques, including rhinoplasty, kidney stone extractions, sutures, other researchers consider it a protoscience, or trans-science system instead. Close to 21% of Ayurveda U. S. and Indian-manufactured patent medicines sold through the Internet were found to contain levels of heavy metals, specifically lead, mercury. The public health implications of such metallic contaminants in India are unknown, some scholars assert that Ayurveda originated in prehistoric times, and that some of the concepts of Ayurveda have existed from the time of the Indus Valley Civilization or even earlier. Humoral balance is emphasized, and suppressing natural urges is considered unhealthy, Ayurveda names three elemental substances, the doshas, and states that a balance of the doshas results in health, while imbalance results in disease. Ayurveda has eight components, which are derived from classical Sanskrit literature. Ayurveda practitioners had developed various medicinal preparations and surgical procedures by the medieval period, the earliest classical Sanskrit works on Ayurveda describe medical science as being divided into eight components. This characterization of the art, the medicine that has eight components, is first found in the Sanskrit epic the Mahābhārata. The central theoretical ideas of Ayurveda developed in the mid-first millennium BCE, balance is emphasized, and suppressing natural urges is considered unhealthy and claimed to lead to illness. For example, to suppress sneezing is said to give rise to shoulder pain. However, people are also cautioned to stay within the limits of reasonable balance, for example, emphasis is placed on moderation of food intake, sleep, and sexual intercourse. Ayurveda names seven basic tissues, which are plasma, blood, muscles, fat, bone, marrow, like the medicine of classical antiquity, Ayurveda has historically divided bodily substances into five classical elements eliminates toxic elements from the body. Panchakarma includes Vamana, Virechana, Basti, Nasya and Raktamokshana and it is preceded by Poorvakarma as a preparatory step, and is followed by Paschatkarma and Peyadikarma. Based on the World Health Assembly resolution on traditional medicine, the WHO has established a traditional medicine strategy, the first previous global strategy was published in 2002 and dealt especially with herbal medicines
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Bamboo
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The bamboos /bæmˈbuː/ are evergreen perennial flowering plants in the subfamily Bambusoideae of the grass family Poaceae. The dicotyledonous woody xylem is also absent, the absence of secondary growth wood causes the stems of monocots, including the palms and large bamboos, to be columnar rather than tapering. Bamboos include some of the plants in the world, due to a unique rhizome-dependent system. Certain species of bamboo can grow 91 cm within a 24-hour period, giant bamboos are the largest members of the grass family. Bamboos are of economic and cultural significance in South Asia, Southeast Asia and East Asia, being used for building materials, as a food source. Bamboo has a higher compressive strength than wood, brick, or concrete. The word bamboo comes from the Kannada term bambu, which was introduced to English through Indonesian, the subfamily in its current sense belongs to the BOP clade of grasses, where it is sister to the Pooideae. The woody bamboos do not form a group, instead. Altogether, more than 1,400 species are placed in 115 genera, most bamboo are native to warm and moist tropical and warm temperate climates. However, many species are found in climates, from hot tropical regions to cool mountainous regions. In the Asia-Pacific region they occur across East Asia, from 50°N latitude in Sakhalin south to Northern Australia, and west to India, China, Japan, Korea, India, and Australia, all have several endemic populations. They also occur in numbers in sub-Saharan Africa, confined to tropical areas, from southern Senegal in the north to southern Mozambique. Bamboo is also native through Central America and Mexico, northward into the Southeastern United States, canada and continental Europe is not known to have any native species of bamboo. Recently, some attempts have been made to grow bamboo on a basis in the Great Lakes region of east-central Africa. In the United States, several companies are growing, harvesting, bamboos include some of the fastest-growing plants on Earth, with reported growth rates up to 91 cm in 24 hours. Primarily growing in regions of warmer climates during the late Cretaceous period, some of the largest timber bamboo can grow over 30 m tall, and be as large as 25–30 cm in diameter. However, the range for mature bamboo is species-dependent, with the smallest bamboos reaching only several inches high at maturity. A typical height range that would cover many of the common bamboos grown in the United States is 4. 6–12 m, depending on species
29.
Hypodermic needle
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A hypodermic needle, also called a sharp, is a very thin, hollow tube with a sharp tip which contains a small opening at the pointed end. It is commonly used with a syringe, a device with a plunger. They are used to take samples from the body, for example taking blood from a vein in venipuncture. Large bore hypodermic intervention is useful in catastrophic blood loss or treating shock. A hypodermic needle is used for delivery of liquids, or when the injected substance cannot be ingested, either because it would not be absorbed. There are many routes for an injection, with the arm being a common location. The hypodermic needle also serves an important role in research environments where sterile conditions are required, the hypodermic needle significantly reduces contamination during inoculation of a sterile substrate. The ancient Greeks and Romans knew injection as a method of delivery from observations of snakebites. There are also references to anointing and inunction in the Old Testament as well as the works of Homer, christopher Wren performed the earliest confirmed experiments with crude hypodermic needles, performing intravenous injection into dogs in 1656. These experiments consisted of using animal bladders and goose quills to administer drugs such as opium intravenously to dogs, Wren and others’ main interest was to learn if medicines traditionally administered orally would be effective intravenously. Elsholtz of Berlin were the first to experiment with injections in humans and these early experiments were generally ineffective and in some cases fatal. Injection fell out of favor for two centuries, the 19th century saw the development of medicines that were effective in small doses, such as opiates and strychnine. This spurred a renewed interest in direct, controlled application of medicine, some controversy surrounds the question of priority in hypodermic medication. Dr. Francis Rynd is generally credited with the first successful injection in 1844, Dr. Alexander Wood’s main contribution was the all-glass syringe in 1851, which allowed the user to estimate dosage based on the levels of liquid observed through the glass. Wood used hypodermic needles and syringes primarily for the application of localized, subcutaneous injection, simultaneous to Wood’s work in Edinburgh, Dr. Charles Pravaz of Lyon also experimented with sub-dermal injections in sheep using a syringe of his own design. Pravaz designed a syringe measuring 3 cm long and 5 mm in diameter, Dr. Charles Hunter, a London surgeon, is credited with the coining of the term hypodermic to describe subcutaneous injection in 1858. The name originates from two Greek words, hypo, under, and derma, skin, Hunter and Wood were involved in lengthy legal disputes over not only the origin of the modern hypodermic needle, but also because of their disagreement to the medicine’s effect once administered. Dr. Wood can be credited with the popularization and acceptance of injection as a medical technique, as well as the widespread use
30.
Centers for Disease Control and Prevention
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The Centers for Disease Control and Prevention is the leading national public health institute of the United States. The CDC is a United States federal agency under the Department of Health and Human Services, headquartered near Atlanta and its main goal is to protect public health and safety through the control and prevention of disease, injury, and disability in the US and internationally. The CDC focuses national attention on developing and applying disease control, the Communicable Disease Center was founded July 1,1946, as the successor to the World War II Malaria Control in War Areas program of the Office of National Defense Malaria Control Activities. Preceding its founding, organizations with global influence in malaria control were the Malaria Commission of the League of Nations, the Rockefeller Foundation greatly supported malaria control, sought to have the governments take over some of its efforts, and collaborated with the agency. The new agency was a branch of the U. S, Public Health Service and Atlanta was chosen as the location because malaria was endemic in the Southern United States. The agency changed names before adopting the name Communicable Disease Center in 1946, Offices were located on the sixth floor of the Volunteer Building on Peachtree Street. Among its 369 employees, the jobs at CDC were originally entomology. In CDCs initial years, more than six and a million homes were sprayed. In 1946, there were only seven officers on duty. Under Joseph Walter Mountin, the CDC continued to advocate for health issues. In 1947, the CDC made a payment of $10 to Emory University for 15 acres of land on Clifton Road in DeKalb County. CDC employees collected the money to make the purchase, the benefactor behind the “gift” was Robert W. Woodruff, chairman of the board of The Coca-Cola Company. Woodruff had a long-time interest in control, which had been a problem in areas where he went hunting. The same year, the PHS transferred its San Francisco based plague laboratory into the CDC as the Epidemiology Division, the mission of CDC expanded beyond its original focus on malaria to include sexually transmitted diseases when the Venereal Disease Division of the U. S. Public Health Service was transferred to the CDC in 1957, shortly thereafter, Tuberculosis Control was transferred to the CDC from PHS, and then in 1963 the Immunization program was established. It became the National Communicable Disease Center effective July 1,1967, the organization was renamed the Center for Disease Control on June 24,1970, and Centers for Disease Control effective October 14,1980. An act of the United States Congress appended the words and Prevention to the name effective October 27,1992, however, Congress directed that the initialism CDC be retained because of its name recognition. Currently the CDC focus has broadened to include chronic diseases, disabilities, injury control, workplace hazards, environmental health threats, and terrorism preparedness
31.
DeRoyal
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DeRoyal Industries is a vertically integrated manufacturer and marketer of health care products. As of 2017, DeRoyal reported having approximately 1900 employees, the company also offers Original Equipment Manufacturer services, including electronics, plastics, textiles, converting, sterilization, metals fabrication, packaging and assembly, and distribution. As of 2010, DeRoyal reported that it more than 70 U. S. patents. The company traces its origin to 1973, when founder Autry O. V. Pete DeBusk started producing a protective boot he had invented to protect orthopedic casts from dirt and damage. The company quickly expanded during the 1970s to include divisions in patient care, surgical, DeRoyal continued to expand its domestic manufacturing operations throughout the 1980s via construction and acquisition. During this period, the company pioneered systems for producing custom surgical procedure trays on a just-in-time basis, in the 1990s, DeRoyal opened a Wound Care division, and continued to introduce new products and systems, such as the TraceCart case-cart-to-waste-cart delivery program. The company also opened new manufacturing facilities in the U. S
32.
Swann Morton
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Swann Morton Ltd. is a British manufacturer of scalpel handles, blades and other surgical equipment. It was founded in 1932 by Walter R. Swann, J. A. Morton and D. Fairweather to make and sell razor blades. Before they began trading, the founders drew up a list of four founding principles, Claims of individuals producing in an industry came first, before anything else and they are the human beings on which everything is built. If the industry cannot pay the reward of labour then a new policy is required on the part of the management to make it do so. If the management cant do the job, then a new management is required, individuals in any industry have a perfect right to demand and see that this objective is reached, because they produce the goods. These four statements, written in W. R. Swanns handwriting, are displayed at Swann-Mortons head office, when the Bard-Parker patent for a 2 piece scalpel ran out in 1935, Swann-Morton expanded its product range in this direction. The company moved to its current site in the 1940s, Morton left the company around this time. The remaining directors took the decision to put the company in a trust where 50% was shared with the employees and it was one of the first commercial plants of its kind in the world and enabled Swann-Morton to be completely self-sufficient for all its sterilisation requirements. Today the irradiation and microbiological facilities are offered under contract to other manufacturers from Swann-Morton Limited
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Occupational Safety and Health Administration
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The Occupational Safety and Health Administration is an agency of the United States Department of Labor. Congress established the agency under the Occupational Safety and Health Act, OSHAs mission is to assure safe and healthful working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education and assistance. The agency is charged with enforcing a variety of whistleblower statutes. OSHA is currently headed by Assistant Secretary of Labor David Michaels, OSHAs workplace safety inspections have been shown to reduce injury rates and injury costs without adverse effects to employment, sales, credit ratings, or firm survival. OSHA officially formed on April 28,1971, the date that the OSH Act became effective, george Guenther was appointed as the agencys first director. OSHA has a number of training, compliance assistance, and health, the OSHA Training Institute, which trains government and private sector health and safety personnel, began in 1972. In 1978, the agency began a program, now called the Susan Harwood Training Grant Program. OSHA started the Voluntary Protection Programs in 1982, which allow employers to apply as model workplaces to achieve special designation if they meet certain requirements. OSHA covers most private sector employers in all 50 states, the District of Columbia, state plans are OSHA-approved job safety and health programs operated by individual states instead of federal OSHA. Federal OSHA approves and monitors all state plans and provides as much as fifty percent of the funding for each program, state-run safety and health programs are required to be at least as effective as the federal OSHA program. Federal OSHA provides coverage to certain workplaces specifically excluded from a state’s plan — for example, workers at state and local government agencies are not covered by federal OSHA, but have OSH Act protections if they work in those states that have an OSHA-approved state program. OSHA rules also permit states and territories to develop plans that only public sector workers. In these cases, private sector workers and employers remain under federal OSHA jurisdiction. Five additional states and one U. S. territory have OSHA approved state plans that cover public sector only, Connecticut, Illinois, Maine, New Jersey, New York. OSHA’s protection applies to all federal agencies, section 19 of the OSH Act makes federal agency heads responsible for providing safe and healthful working conditions for their workers. OSHA conducts inspections of facilities in response to workers’ reports of hazards. Federal agencies must have a safety and health program that meets the standards as private employers. Under a 1998 amendment, the OSHA Act covers the U. S. Postal Service the same as any private sector employer, the self-employed, immediate family members of farm employers, and workplace hazards regulated by another federal agency
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PubMed Identifier
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PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine at the National Institutes of Health maintains the database as part of the Entrez system of information retrieval, from 1971 to 1997, MEDLINE online access to the MEDLARS Online computerized database primarily had been through institutional facilities, such as university libraries. PubMed, first released in January 1996, ushered in the era of private, free, home-, the PubMed system was offered free to the public in June 1997, when MEDLINE searches via the Web were demonstrated, in a ceremony, by Vice President Al Gore. Information about the journals indexed in MEDLINE, and available through PubMed, is found in the NLM Catalog. As of 5 January 2017, PubMed has more than 26.8 million records going back to 1966, selectively to the year 1865, and very selectively to 1809, about 500,000 new records are added each year. As of the date,13.1 million of PubMeds records are listed with their abstracts. In 2016, NLM changed the system so that publishers will be able to directly correct typos. Simple searches on PubMed can be carried out by entering key aspects of a subject into PubMeds search window, when a journal article is indexed, numerous article parameters are extracted and stored as structured information. Such parameters are, Article Type, Secondary identifiers, Language, publication type parameter enables many special features. As these clinical girish can generate small sets of robust studies with considerable precision, since July 2005, the MEDLINE article indexing process extracts important identifiers from the article abstract and puts those in a field called Secondary Identifier. The secondary identifier field is to store numbers to various databases of molecular sequence data, gene expression or chemical compounds. For clinical trials, PubMed extracts trial IDs for the two largest trial registries, ClinicalTrials. gov and the International Standard Randomized Controlled Trial Number Register, a reference which is judged particularly relevant can be marked and related articles can be identified. If relevant, several studies can be selected and related articles to all of them can be generated using the Find related data option, the related articles are then listed in order of relatedness. To create these lists of related articles, PubMed compares words from the title and abstract of each citation, as well as the MeSH headings assigned, using a powerful word-weighted algorithm. The related articles function has been judged to be so precise that some researchers suggest it can be used instead of a full search, a strong feature of PubMed is its ability to automatically link to MeSH terms and subheadings. Examples would be, bad breath links to halitosis, heart attack to myocardial infarction, where appropriate, these MeSH terms are automatically expanded, that is, include more specific terms. Terms like nursing are automatically linked to Nursing or Nursing and this important feature makes PubMed searches automatically more sensitive and avoids false-negative hits by compensating for the diversity of medical terminology. The My NCBI area can be accessed from any computer with web-access, an earlier version of My NCBI was called PubMed Cubby
35.
International Standard Serial Number
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An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication. The ISSN is especially helpful in distinguishing between serials with the same title, ISSN are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an International Organization for Standardization international standard in 1971, ISO subcommittee TC 46/SC9 is responsible for maintaining the standard. When a serial with the content is published in more than one media type. For example, many serials are published both in print and electronic media, the ISSN system refers to these types as print ISSN and electronic ISSN, respectively. The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers, as an integer number, it can be represented by the first seven digits. The last code digit, which may be 0-9 or an X, is a check digit. Formally, the form of the ISSN code can be expressed as follows, NNNN-NNNC where N is in the set, a digit character. The ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, for calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, the modulus 11 of the sum must be 0. There is an online ISSN checker that can validate an ISSN, ISSN codes are assigned by a network of ISSN National Centres, usually located at national libraries and coordinated by the ISSN International Centre based in Paris. The International Centre is an organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, at the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept, where ISBNs are assigned to individual books, an ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an identifier associated with a serial title. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change, separate ISSNs are needed for serials in different media. Thus, the print and electronic versions of a serial need separate ISSNs. Also, a CD-ROM version and a web version of a serial require different ISSNs since two different media are involved, however, the same ISSN can be used for different file formats of the same online serial
36.
Cutting
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Cutting is the separation of a physical object, into two or more portions, through the application of an acutely directed force. Implements commonly used for cutting are the knife and saw, or in medicine and science the scalpel, however, any sufficiently sharp object is capable of cutting if it has a hardness sufficiently larger than the object being cut, and if it is applied with sufficient force. Even liquids can be used to cut things when applied with sufficient force, cutting is a compressive and shearing phenomenon, and occurs only when the total stress generated by the cutting implement exceeds the ultimate strength of the material of the object being cut. Hence, the smaller the area, the force is needed to cut something. It is generally seen that cutting edges are thinner for cutting soft materials and this progression is seen from kitchen knife, to cleaver, to axe, and is a balance between the easy cutting action of a thin blade vs strength and edge durability of a thicker blade. Cutting has been at the core of manufacturing throughout history, for metals many methods are used and can be grouped by the physical phenomenon used. Chip forming - sawing, drilling, milling, turning etc, abrading - grinding, lapping, polishing, water-jet. Heat - flame cutting, plasma cutting, laser cutting, electrochemical - etching, electrical discharge machining. Every method has its limitations in accuracy, cost, and effect on the material, for example, heat may damage the quality of heat treated alloys, and laser cutting is less suitable for highly reflective materials such as aluminum. Laser cutting sheet metal produces flat parts and etches and engraves parts from complex or simple designs and it is used over other cutting options for its quick process and customizable abilities
37.
Abrasive
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An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, in short, the Ceramics which are used to cut, grind and polish other softer materials are known as Abrasives. Abrasives are extremely commonplace and are used extensively in a wide variety of industrial, domestic. This gives rise to a variation in the physical and chemical composition of abrasives as well as the shape of the abrasive. Common uses for abrasives include grinding, polishing, buffing, honing, cutting, drilling, sharpening, lapping, and sanding. Files are not abrasives, they remove material not by scratching or rubbing, however, diamond files are a form of coated abrasive. Abrasives generally rely upon a difference in hardness between the abrasive and the material being worked upon, the abrasive being the harder of the two substances. Diamond, an abrasive, for instance occurs both naturally and is industrially produced, as is corundum which occurs naturally but which is nowadays more commonly manufactured from bauxite. However, even softer minerals like calcium carbonate are used as abrasives and these minerals are either crushed or are already of a sufficiently small size to permit their use as an abrasive. These grains, commonly called grit, have rough edges, often terminating in points which will decrease the area in contact. The abrasive and the material to be worked are brought into contact while in motion to each other. Abrasives may be classified as natural or synthetic. When discussing sharpening stones, natural stones have long been considered superior, many synthetic abrasives are effectively identical to a natural mineral, differing only in that the synthetic mineral has been manufactured rather than been mined. Impurities in the mineral may make it less effective. Natural abrasives are often sold as dressed stones, usually in the form of a rectangular block, a bonded abrasive is composed of an abrasive material contained within a matrix, although very fine aluminium oxide abrasive may comprise sintered material. This matrix is called a binder and is often a clay, a resin and this mixture of binder and abrasive is typically shaped into blocks, sticks, or wheels. The most usual abrasive used is aluminium oxide, also common are silicon carbide, tungsten carbide and garnet. Artificial sharpening stones are often a bonded abrasive and are available as a two sided block, each side being a different grade of grit
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Abrasive saw
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An abrasive saw, also known as a cut-off saw or chop saw, is a power tool which is typically used to cut hard materials, such as metals, tile, and concrete. The cutting action is performed by a disc, similar to a thin grinding wheel. Technically speaking this is not a saw, as it not use regularly shaped edges for cutting. These saws are available in a number of configurations, including top, free hand. In the table top models, which are used to cut tile and metal. Table top saws are often electrically powered and generally have a built-in vise or other clamping arrangement, the free hand designs are typically used to cut concrete, asphalt, and pipe on construction sites. They are designed with the handles and motor near the operator, free hand saws do not feature a vise, because the materials being cut are larger and heavier. Walk-behind models, sometimes called flat saws are larger saws which use a stand or cart to cut into concrete floors as well as asphalt, abrasive saws typically use composite friction disk blades to abrasively cut through the steel. The disks are consumable items as they wear throughout the cut, the abrasive disks for these saws are typically 14 in in diameter and 7⁄64 in thick. Larger saws use 410 mm diameter blades, disks are available for steel and stainless steel. Abrasive saws can also use superabrasive blades, which last longer than conventional abrasive materials, superabrasive materials are more commonly used when cutting concrete, asphalt, and tile, however, they are also suitable for cutting ferrous metals. Since their introduction, portable cut-off saws have made many building site jobs easier, with these saws, lightweight steel fabrication previously performed in workshops using stationary power bandsaws or cold saws can be done on-site. Abrasive saws have replaced expensive and hazardous acetylene torches in many applications. In addition, these saws allow construction workers to cut concrete, asphalt. Angle grinder Cold saw Miter box Ring saw Madsen, David A, print Reading for Engineering and Manufacturing Technology
39.
Axe
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An axe is an implement that has been used for millennia to shape, split and cut wood, to harvest timber, as a weapon, and as a ceremonial or heraldic symbol. The axe has many forms and specialised uses but generally consists of an axe head with a handle, before the modern axe, the stone-age hand axe was used from 1.5 million years BP without a handle. It was later fastened to a wooden handle, the earliest examples of handled axes have heads of stone with some form of wooden handle attached in a method to suit the available materials and use. Axes made of copper, bronze, iron, and steel appeared as these technologies developed, axes are usually composed of a head and a handle. The axe is an example of a machine, as it is a type of wedge. This reduces the effort needed by the wood chopper and it splits the wood into two parts by the pressure concentration at the blade. The handle of the axe also acts as a lever allowing the user to increase the force at the cutting edge—not using the length of the handle is known as choking the axe. For fine chopping using an axe this sometimes is a positive effect. Generally, cutting axes have a shallow angle, whereas splitting axes have a deeper angle. Most axes are double bevelled, i. e, less common today, they were once an integral part of a joiner and carpenters tool kit, not just a tool for use in forestry. A tool of similar origin is the billhook, however, in France and Holland the billhook often replaced the axe as a joiners bench tool. Most modern axes have heads and wooden handles, typically hickory in the US and ash in Europe and Asia. Modern axes are specialised by use, size, and form, hafted axes with short handles designed for use with one hand are often called hand axes but the term hand axe refers to axes without handles as well. Hatchets tend to be small hafted axes often with a hammer on the back side, as easy-to-make weapons, axes have frequently been used in combat. Initially axes were tools of stone called hand axes, used without handles, axes made with ground cutting edges are known since the Neolithic period ending 4,000 to 2,000 BC. The first true hafted axes are known from the Mesolithic period, few wooden hafts have been found from this period, but it seems that the axe was normally hafted by wedging. Birch-tar and raw-hide lashings were used to fix the blade, the antler was hollowed out at one end to create a socket for the axehead. The antler sheath was then either perforated and a handle inserted into it or set in a made in the handle instead
40.
Blade
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A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. A blade may be made from a stone, such as flint, metal, ceramic. Blades are one of humanitys oldest tools, and continue to be used for combat, food preparation, during food preparation, knives are mainly used for slicing, chopping, and piercing. In combat, a blade may be used to slash or puncture, the function is to sever a nerve, muscle or tendon fibers, or blood vessel to disable or kill the adversary. Severing a major blood vessel typically leads to death due to exsanguination, shrapnel causes wounds via the fragments blade-like nature. Blades may be used to scrape, moving the blade sideways across a surface, a simple blade intended for cutting has two faces that meet at an edge. Ideally this edge would have no roundness but in practice all edges can be seen to be rounded to some degree under magnification either optically or with an electron microscope, force is applied to the blade, either from the handle or pressing on the back of the blade. The handle or back of the blade has a large area compared to the fine edge and this concentration of applied force onto the small edge area increases the pressure exerted by the edge. It is this pressure that allows a blade to cut through a material by breaking the bonds between the molecules/crystals/fibres/etc. in the material. This necessitates the blade being strong enough to resist breaking before the material gives way. The angle at which the meet is important as a larger angle will make for a duller blade while making the edge stronger. A stronger edge is likely to dull from fracture or from having the edge roll out of shape. The shape of the blade is also important, a thicker blade will be heavier and stronger and stiffer than a thinner one of similar design while also making it experience more drag while slicing or piercing. A splitting maul has a section to avoid getting stuck in wood where chopping axes can be flat or even concave. Similarly, pushing on a rope tends to squash the rope while drawing serrations across it sheers the rope fibres, drawing a smooth blade is less effective as the blade is parallel to the direction draw but the serrations of a serrated blade are at an angle to the fibres. Saw blade serrations, for wood and metal, are typically asymmetrical so that they cut while moving in only one direction. Fullers are longitudinal channels either forged into the blade or later machined/milled out of the blade though the process is less desirable. This loss of material necessarily weakens the blade but serves to make the lighter without sacrificing stiffness
41.
Bandsaw
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A bandsaw is a saw with a long sharp blade consisting of a continuous band of toothed metal stretched between two or more wheels to cut material. They are used principally in woodworking, metalworking, and lumbering, advantages include uniform cutting action as a result of an evenly distributed tooth load, and the ability to cut irregular or curved shapes like a jigsaw. The minimum radius of a curve is determined by the width of the band, most bandsaws have two wheels rotating in the same plane, one of which is powered, although some may have three or four to distribute the load. The blade itself can come in a variety of size and tooth pitch which enables the machine to be versatile and able to cut a wide variety of materials including wood, metal. Almost all bandsaws today are powered by an electric motor, line shaft versions were once common but are now antiques. Constant flexing of the blade over the wheels caused either the material or the joint welding it into a loop to fail, nearly 40 years passed before Frenchwoman Anne Paulin Crepin devised a welding technique overcoming this hurdle. She applied for a patent in 1846, and soon sold the right to employ it to manufacturer A. Perin & Company of Paris. Combining this method with new alloys and advanced tempering techniques allowed Perin to create the first modern band saw blade. The first American band saw patent was granted to Benjamin Barker of Ellsworth, Maine, the first factory produced and commercially available band saw in the U. S. was by a design of Paul Prybil. Power hacksaws were once common in the industries, but bandsaws. Many workshops in residential garages or basements and in light industry contain small or medium-sized bandsaws that can cut wood, metal, often a general-purpose blade is left in place, although blades optimized for wood or metal can be switched out when volume of use warrants. Most residential and commercial bandsaws are of the vertical type mounted on a bench or a cabinet stand, Portable power tool versions, including cordless models, are also common in recent decades, allowing building contractors to bring them along on the truck to the jobsite. Saws for cutting meat are typically of all steel construction with easy to clean features. The blades either have fine teeth with heat treated tips, or have plain or scalloped knife edges, bandsaws dedicated to industrial metal-cutting use, such as for structural steel in fabrication shops and for bar stock in machine shops, are available in vertical and horizontal designs. Typical band speeds range from 40 feet per minute to 5,000 feet per minute, although specialized bandsaws are built for friction cutting of hard metals, metal-cutting bandsaws are usually equipped with brushes or brushwheels to prevent chips from becoming stuck in between the blades teeth. Systems which cool the blade with cutting fluid are also common equipment on metal-cutting bandsaws, the coolant washes away swarf and keeps the blade cool and lubricated. Horizontal bandsaws hold the workpiece stationary while the blade swings down through the cut and this configuration is used to cut long materials such as pipe or bar stock to length. Thus it is an important part of the facilities in most machine shops, the horizontal design is not useful for cutting curves or complicated shapes
. PMID 19876423.
