Cobalt

In the third quarter of 2003 Sun discountinued their Cobalt line in favor of the AMD based Sun Fire line. A good example of a shoulder-cock crossbow is the FX-II crossbow. Previously known as Cobalt Systems, this Internet appliance company was acquired by Sun in 2000. The average draw force for the shoulder-cock crossbow is 100 lbf (400 N), which is low compared to other crossbows. Cobalt was also the name of Sun Microsystems' mainly rack-mounted, Intel and Linux based, server appliance line. Using a shoulder-cock, a good crossbowman could reload in under 7 seconds. This process is referred to as irradiation. The shoulder-cock is extremely easy to use and has a fast loading time.

Nevertheless, the gamma radiation emitted from cobalt-60 is used to kill bacteria on fruit and vegetables thus increasing their shelf life. One of the newest developments in crossbow technology is the use of the shoulder-cock. The risk in the absence of a nuclear war comes from improper handling (or theft) of medical radiotherapeutic units. They are made of the same composite materials as modern bows. Some nuclear weapon designs could intentionally increase the amount of Cobalt-60 dispersed as nuclear fallout – this is sometimes called a dirty bomb or cobalt bomb, once predicted by a leading scientist as being capable of wiping out all life on earth. Modern crossbows are still used for target shooting and in some places for hunting. Cobalt-60 is a risk factor in a nuclear confrontation because neutron emissions will convert iron into this isotope. Early guns had slower rates of fire and much worse accuracy than contemporary crossbows.

Ingestion of ⁶⁰Co will lead to incorporation of some cobalt into tissues, which is released very slowly. Crossbows were eventually replaced in warfare by gunpowder weapons. Cobalt-60 is a powerful gamma ray emitter and exposure to ⁶⁰Co is therefore a cancer risk. Given the great accuracy of the crossbow, it filled many duties that sniper rifles have today. Cobalt compounds should be handled with care due to cobalt's slight toxicity. However, their effectiveness made them an "evil" no one could afford to be without, often in the form of hired foreign mercenaries. Powdered cobalt in metal form is a fire hazard. The crossbow was seen as unchivalrous and as a threat to social order, since a peasant could kill a noble anonymously; crossbow mercenaries were usually killed immediately on capture, unlike others who might have been ransomed or set free.

The primary decay products before ⁵⁹Co are element 26 (iron) isotopes and the primary products after are element 28 (nickel) isotopes. Pope Urban II banned the use of crossbow against Christians in 1097, and the Second Lateran Council did the same for arbalests in 1139. The primary decay mode before the most abundant stable isotope, ⁵⁹Co, is electron capture and the primary mode after is beta decay. Due to the long time required to reload a crossbow, users would sometimes make use of a pavise. The isotopes of cobalt range in atomic weight from 50 amu (⁵⁰Co) to 73 amu (⁷³Co). Moreover, crossbows could be kept cocked and ready to shoot for some time with little effort, allowing crossbowmen to aim better and to "cover" a target area, while archers could not keep their powerful bows pulled for long periods of time. This element also has 4 meta states, all of which have half lives less than 15 minutes. In the later years of the crossbow it had enough kinetic energy to penetrate the armor of a knight with ease: some reached a draw force of nearly 350 lbf (1600 N), compared to the 60-180lbf (300-900 N) draw force for a longbow.

All of the remaining radioactive isotopes have half-lifes that are less than 18 hours and the majority of these have half lives that are less than 1 second. The use of winches allowed soldiers to use and fire weapons with a draw force far in excess of what they could have handled with a bow. 22 radioisotopes have been characterized with the most stable being ⁶⁰Co with a half-life of 5.2714 years, 57-Co (⁵⁷Co) with a half-life of 271.79 days, and 56-Co (⁵⁶Co) with a half-life of 77.27 days, and 58-Co (⁵⁸Co) with a half life of 70.86 days. An expertly handled longbow had greater range, better accuracy (the "arbalest" or siege crossbow being the exception here), and a much faster rate of fire than an average crossbow, but the value of the crossbow came in its simplicity: it could be used effectively after a week of training, while a comparable single-shot skill with a longbow could take years. Naturally occurring cobalt is composed of 1 stable isotope, 59-Co (⁵⁹Co). They supplanted bows in many European armies for a number of reasons. Oxides are antiferromagnetic at low temperature CoO (Neel temperature: 291 K) and Co₃O₄ (Neel temperature: 40 K). Crossbows were actively being used in European warfare from 800 to 1500 A.D.

Due to the various oxidation states, there is an abundant number of compounds.
. It is also produced in the town of Cobalt, Ontario as a byproduct of the silver mining. Some Belgian designs were as polished as those of modern Olympic rifles. It is also found in Finland, Azerbaijan, and Kazakhstan. Makers of crossbows (arbalistmeisters) were making quite beautiful crossbow stocks by 1600. The world's major producers of cobalt are the Democratic Republic of the Congo, mainland China, Zambia, Russia and Australia. By 1650, the cross bow looked like it had a rifle stock, and was used in a similar way (what you see on a rifle has probably already been done on a crossbow).

The main ores of cobalt are cobaltite, erythrite, glaucodot, and skutterudite. About 1400 the use of the crossbow changed, with the butt end of the stock being placed on the shoulder for accuracy. Cobalt is usually not mined alone, and tends to be produced as a by-product of nickel and copper mining activities. A crossbow prod was made out of spring steel, steel prods being very common by the early 1500s as their performance was more uniform, except in very cold weather. Cobalt is not found as a free metal and is generally found in the form of ores. In the later 1400s, steel manufacturing advanced significantly, and was more commonly used in spring production. Cobalt is a central component of the vitamin cobalamin, or vitamin B-12. It was not uncommon for six months up to a year to be spent in ensuring a bow was dried properly.

Having 0.13 to 0.30 mg/kg of cobalt in soils markedly improves the health of grazing animals. The strongest glues naturally took longer to dry. Cobalt in small amounts is essential to many living organisms, including humans. Since composite prods involved gluing material together which would have to withstand a great deal of stress, a slow drying time was essential. Some also think the name may derive from Greek kobalos, which means 'mine', and which may have common roots with kobold, goblin, and cobalt. It is the high launch force of a crossbow that made it a formidable weapon in warfare. Other sources cite the origin as stemming from silver miners' belief that cobalt had been placed by kobolds who had stolen the silver. Since the draw force can be much more than a soldier might be able to pull, these crossbows generally include a winch device to cock them.

The word cobalt comes from the German kobalt or kobold, meaning evil spirit, the metal being so called by miners, because it was poisonous and troublesome (it polluted and degraded the other mined elements, like nickel). The draw force is the tension that the string is under when the bow is engaged. In 1938, John Livingood and Glenn Seaborg discovered cobalt-60. Composite prods were made of horn, sinew and wood, and produced much larger draw forces. During the 19th century, cobalt blue was produced at the Norwegian Blaafarveværket (70-80 % of world production), led by the Prussian industrialist Benjamin Wegner. The advantage of a simple wooden prod is that the bow as a whole was lighter in weight, easier to span (even by hand), and quicker to discharge. He was able to show that cobalt was the source of the blue color in glasses, which previously had been attributed to the bismuth found with cobalt. The prod of a crossbow was made of wood or composite materials until the middle of the 15th century.

The date of discovery varies depending on the source, but is between 1730 and 1737. Roman bows tended to be ornate and well engineered, yet western European bowstocks that were produced 600 years later appeared to be nothing more than rough hewn slabs of wood. George Brandt (1694-1768) is credited with the discovery of cobalt. One of the most distinctive Chinese inventions on crossbows was the repeating crossbow (Chu-ko-nu), invented in 2nd Century AD which was used as late as China-Japan war of 1894-1895 by Manchurian troops. Cobalt was known in ancient times through its compounds, which would color glass a rich blue. Some linguistic evidence also seems to indicate a Southeast Asian origin ^[3]. The second machine is out beside the walkway into the Centre. Crossbows have been found among the soldiers of the Terracotta Army in the tomb of emperor Qin Shi Huang (260-210 BCE) ^[2].

In fact the first machine is on display in the Saskatoon Cancer Centre – look up when entering the lobby. By the 200s BC, the crossbow (nǔ, 弩) was well developed and quite widely used in China^[1]. The first ⁶⁰Co therapy machine (the "cobalt bomb") was built and first used in Canada. This prevents them from snagging on the crossbow nut as they are shot. The ⁶⁰Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where linacs are common. They also typically only have two fletches per bolt instead of three commonly seen on arrows. The metal has the unfortunate habit of producing a fine dust, causing problems with radiation protection. Crossbow bolts are lighter than arrows, but must be sealed with a varnish to ensure their consistent weight.

The ⁶⁰Co source is about 2 cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. Leonardo da Vinci designed many complicated triggers for crossbows, ultimately producing a "hair trigger" that could be shot with very little finger strength. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. Triggers are known to have been used on crossbows from the early 1400s. Cobalt-60 (Co-60 or ⁶⁰Co) is a radioactive metal that is used in radiotherapy. The crossbow also includes a trigger, which was later incorporated into rifles, muskets and other firearms. Co-60 is useful as a gamma ray source partially because it can be produced - in known quantity, and very large amounts - by simply exposing natural cobalt to neutrons in a reactor for a given time. In wet, twisted mulberry root was occasionally used.

Common oxidation states of cobalt include +2, and +3, though +1 is also seen. Even cotton was tried with some success. Metallic cobalt commonly presents a mixture of two crystallographic structures hcp and fcc with a transition temperature hcp→fcc of 722 K. Patternson, whipcord was very common; however linen, hemp, and sinew were used as well. Cobalt has a relative permeability two thirds that of iron. F. Cobalt-60, an artificially produced radioactive isotope of cobalt, is an important radioactive tracer and cancer-treatment agent. According to W.

Mammals require small amounts of cobalt salts. The strings for a crossbow are typically made of strong fibers that would not tend to fray. It is frequently associated with nickel, and both are characteristic ingredients of meteoric iron. The crossbow shelf is a flat section above the stock with a straight groove for the bolt to rest upon and travel along as it is shot. The Curie temperature is of 1388 K with 1.6~1.7 Bohr magnetons per atom. The draw weight of a modern crossbow can be up to 300lbs. Cobalt is a hard ferromagnetic silver-white element. This makes crossbows inefficient at storing energy, which is why they must have very heavy draw weights.

. The prod is very short compared to bows, thus resulting in a short draw length. Cobalt is a chemical element in the periodic table that has the symbol Co and atomic number 27. Much as a horse's bridle, it tends to loosen over time, and must be carefully respliced when appropriate. London celebrates 50 years of Cobalt-60 Radiotherapy. This cording is called the bridle of the crossbow. WebElements.com – Cobalt. The prod (also called lath in England) is attached to the stock with hemp rope, linen, whipcord, or other strong cording.

National Pollutant Inventory - Cobalt fact sheet. The central European bows were rather exotic as they were constructed of inlays as well as specialized woods. Cobalt is the name of a current line of cars from Chevrolet. The prod ("bow") and stock of a crossbow were made of good hardwood, such as oak or hard maple. Los Alamos National Laboratory - Cobalt. Typically, the nut is at the end of the shelf (also called the bolt rest). It is used in industrial radiography to detect structural flaws in metal parts. A crossbow contains a string which is held in place by a nut when the bolt is loaded and the cross bow is engaged (referred to as at full draw).

It is used in radiation treatment of foods for sterilization (cold pasteurization). This consistent performance was part of what made the crossbow historically a significant force in warfare. It is used in radiotherapy. Crossbow bolts must be made to have consistent weights as the mechanical process of engaging a bolt forces a more uniform process than that of using a bow and arrow. Cobalt-60 has multiple uses as a gamma ray source: