The use of hides and skins‚ tanned or untanned‚ as useful articles has been with us for thousands of years. The Oxford Dictionary refers to leather as "material made from the hide or skin of an animal by tanning". Tanning‚ in simple terms‚ refers to the treatment of raw hides and skins with tanning substances to render the material immune to bacterial attack‚ ie to produce leather. Additional changes introduced in the process of tanning are secondary and are related to the tanning and retanning chemicals
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which probably referred instead at the time to lapis lazuli) is a gemstone variety of the mineral corundum‚ an aluminum oxide (α-Al2O3). Trace amounts of other elements such as iron‚ titanium‚ chromium‚ copper‚ or magnesium can give corundum blue‚ yellow‚ pink‚ purple‚ orange‚ or a greenish color. Chromium impurities in corundum yield a red tint‚ and the resultant gemstone is called a ruby. Commonly‚ sapphires are worn in jewelry. Sapphires may be found
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Stainless Steel Association (BSSA) www.bssa.org.uk Cedinox www.cedinox.es Centro Inox www.centroinox.it Informationsstelle Edelstahl Rostfrei www.edelstahl-rostfrei.de Institut de Développement de l’Inox (I.D.-Inox) www.idinox.com International Chromium Development Association (ICDA) www.icdachromium.com International Molybdenum Association (IMOA) www.imoa.info Nickel Institute www.nickelinstitute.org Polska Unia Dystrybutorów Stali (PUDS) www.puds.com.pl SWISS INOX
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Major sources of vitamin C are citric fruits such as orange and grapefruit‚ but it’s also found in sweet fruits like papaya‚ mango‚ strawberries‚ and cantaloupes. Explain the function of the following: Zinc‚ Iodine‚ Iron‚ Magnesium‚ Calcium and Chromium. Zinc is an essential mineral found in cells throughout the body. It plays an important role in the immune system‚ wound healing‚ and the breakdown of carbohydrates and lipids. Its main functions are the DNA synthesis‚ metabolism of protein‚ development
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An early observation of fluorescence was described in 1560 byBernardino de Sahagún and in 1565 by Nicolás Monardes in theinfusion known as lignum nephriticum (Latin for "kidney wood"). It was derived from the wood of two tree species‚ Pterocarpus indicus andEysenhardtia polystachya.[2][3][4][5] The chemical compound responsible for this fluorescence is matlaline‚ which is the oxidation product of one of the flavonoids found in this wood.[2] In 1819 Edward D. Clarke[6] and in 1822 René Just Haüy[7] described
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and in everyday objects and occurrences. When heavy metals enter the air from factories emissions and smoke‚ it is exposed to the body‚ which mostly affect your skin and lungs such as Cadmium and Arsenic. Common water contaminates are Chromium and Thallium‚ Chromium can enter the water source usually through spills and leaks from power plants. Thallium like other metals occurs naturally in water but some areas can contain elevated levels. Mercury is in water as well and many older fish have the ability
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Air Quality Issues in Los Angeles Andrew Penn Humanities 120 Scott Meyers It is a beautiful‚ sunny morning‚ so your walk to work is something you are actually looking forward to today. After breakfast you get on your way and notice how truly warm it is‚ then you notice something else; your eyes are burning and you are struggling to gasp for another breath. Such is the life for the average Los Angeles resident. A city dominated by warm climate‚ show business‚ and extravagant lifestyles has been
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TRANSDUCERS Transducers are electric or electronic devices that transform energy from one form to another. A transducer is a device that converts one form of energy to other form. It converts the measureand to a usable electrical signal. In other word it is a device that is capable of converting the physical quantity into a proportional electrical quantity such as voltage or current. Industrial uses of transducers - Temperature‚ force‚ strain‚ liquid level‚ flow rate‚ electrical conductivity
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------------------------------------------------- Alloy Steel is a metal alloy whose major component is iron‚ with carbon content between 0.02% and 2.14% by mass. An alloy is a metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure‚ while partial solutions give two or more phases that may or may not be homogeneous in distribution‚ depending on thermal (heat treatment) history. Alloys usually have different properties from those
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The ruby laser‚ first invented in 1960‚ was the world’s first laser. Created by Theodore Maiman‚ the ruby laser is composed of aluminium oxide where some of the aluminium ions have been replaced with chromium ions. These chromium ions are what gives the ruby laser its red color. Its gain medium is a cylindrical crystal. A fully reflecting mirror and a partially reflecting mirror are placed at both ends of the cylindrical crystal. A high intensity lamp is spiraled around the cylinder to produce a
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