Maize (called corn in some countries) is a member of the grass family Poaceae. It is a cereal grain that was first grown by people in ancient Central America. It is now the third most important cereal crop in the world.
Maize is a leafy stalk whose kernels have seeds inside. It is an angiosperm, which means that its seeds are enclosed inside a fruit or shell. It is used as a food staple by many people in Mexico, Central and South America and parts of Africa. In Europe and the rest of North America, maize is grown mostly for use as animal feed. In Canada and the United States, maize is commonly referred to as "corn". In recent years corn has become an important part in a majority of American foods through the use of corn starch.
Maize has been a fruitful model organism for research in genetics for many years: see Barbara McClintock. Research has shown that artificial selection developed maize from a Mexican plant called Teosinte.
A nitrogen-containing substance normally cleared from the blood by the kidney into the urine. Diseases that compromise the function of the kidney often lead to increased blood levels of urea, as measured by the blood urea nitrogen (BUN) test.
Urea is of major historical significance. It was the first organic chemical compound ever synthesized. The German chemist Friedrich Wohler in 1828 attempted to make ammonium cyanate from silver cyanide and ammonium chloride and, in the process, accidentally made urea. Wohler wrote his mentor Jons Berzelius, "I must tell you that I can make urea without the use of kidneys, either man or dog. Ammonium cyanate is urea."
This pioneering experiment disproved the theory of vitalism, the concept that organic chemicals could only be modified chemically, but that living plants or animals were needed to produce them.
Wohler had also discovered that urea and ammonium cyanate had the same chemical formula but very different chemical properties. This was due to isomerism, the phenomenon in which two or more chemical compounds have the same number and type of atoms but, because those atoms are arranged differently, each compound has different chemical properties.
Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout. It was developed from other types of hydraulic lime in England in the mid 19th century and usually originates from limestone. It is a fine powder produced by heating materials in a kiln to form what is called clinker, grinding the clinker, and adding small amounts of other materials. Several types of Portland cement are available with the most common being called ordinary Portland cement (OPC) which is grey in color, but a white Portland cement is also available.
Portland cement is caustic, so it can cause chemical burns, the powder can cause irritation or with severe exposure lung cancer, and can contain some hazardous components such as crystalline silica and hexavalent chromium. Environmental concerns are the high energy consumption required to mine, manufacture, and transport the cement and the related air pollution including the release of greenhouse gases (e.g., carbon dioxide), dioxin, NOx, SO2, and particulates.
The low cost and widespread availability of the limestone, shales, and other naturally occurring materials used in Portland cement make it one of the lowest-cost materials widely used over the last century throughout the world. Concrete produced from Portland cement is one of the most versatile construction materials available in the world.
Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite (Fe3O4, 72.4%Fe), hematite (Fe
2O3, 69.9% Fe), goethite (FeO(OH), 62.9% Fe),limonite (FeO(OH).n(H2O))or siderite (FeCO3, 48.2% Fe).
Ores containing very high quantities of hematite or magnetite (greater than ~60% iron) are known as "natural ore" or "direct shipping ore", meaning they can be fed directly into iron-making blast furnaces. Iron ore is the raw material used to make pig iron, which is one of the main raw materials to make steel. 98% of the mined iron ore is used to make steel. Indeed, it has been argued that iron ore is "more integral to the global economy than any other commodity, except perhaps oil".
ICUMSA is a world-wide body which brings together the activities of the National Committees for Sugar Analysis in more than thirty member countries. Work is carried out under various Subject headings, each headed by a Referee.
Methods are recommended for tentative approval by ICUMSA in the first instance. Upon meeting all of the Commission's requirements, methods are accorded official status. Methods which are demonstrably useful and have found an established application, or which do not lend themselves to collaborative testing are given an Accepted status"
An ICUMSA rating is an international unit for expressing the purity of the sugar in solution, and is directly related to the colour of the sugar. Be aware that there are different types of ICUMSA units. For Brazilian sugar, the lower the ICUMSA figure the whiter the sugar. However, this is not the case in the E.U. for some unknown reason, which has been the subject of much discussion.
SGS of Sao Paulo has published specifications for ICUMSA numbers for E.U. product which run contrary to the Brazilian specifications; for example, in Brazil SGS has an ICUMSA rating of 45 rbu for refined, indicating the highest quality, with other grades of lower quality (such as Special Extra Crystal) having a higher ICUMSA of 150 and so forth. This rating method is confirmed by the Institute of Sugar and Alcohol in Brazil.
The TU is heavily dependent upon "ash points", which are defined as "Conductivity ash, % , expressed to three decimal places" (British Sugar Corp., Central Laboratory, ICUMSA Headquarters). Further used to weight the TU is "reflectance Grade Colour" and "Solution Colour" or "Filtered Colour" as it is referred to, which have formulas for determination equally confusing as the one for "Ash Points". Thus, as you see, this is not easily understood by the novice.
Coal (from the Old English term col, which has meant "mineral of fossilized carbon" since the 13th century) is a combustible black or brownish-black sedimentary rockusually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rockbecause of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen,sulfur, oxygen, and nitrogen.
Throughout history, coal has been used as an energy resource, primarily burned for the production of electricity and/or heat, and is also used for industrial purposes, such as refining metals. A fossil fuel, coal forms when dead plant matter is converted into peat, which in turn is converted into lignite, then sub-bituminous coal, after thatbituminous coal, and lastly anthracite. This involves biological and geological processes that take place over a long period. The United States Energy Information Administration estimates coal reserves at 948×109 short tons (860 Gt). One estimate for resources is 18,000 Gt.
Coal is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide anthropogenic sources of carbon dioxide releases. In 1999, world gross carbon dioxide emissions from coal usage were 8,666 million tonnes of carbon dioxide. In 2011, world gross emissions from coal usage were 14,416 million tonnes. Coal-fired electric power generation emits around 2,000 pounds of carbon dioxide for every megawatt-hour generated, which is almost double the approximately 1100 pounds of carbon dioxide released by a natural gas-fired electric plant per megawatt-hour generated. Because of this higher carbon efficiency of natural gas generation, as the market in the United States has changed to reduce coal and increase natural gas generation, carbon dioxide emissions may have fallen. Those measured in the first quarter of 2012 were the lowest of any recorded for the first quarter of any year since 1992. In 2013, the head of the UN climate agency advised that most of the world's coal reserves should be left in the ground to avoid catastrophic global warming.
Coal is extracted from the ground by coal mining, either underground by shaft mining, or at ground level by open pit mining extraction. Since 1983 the world top coal producer has been China. In 2011 China produced 3,520 million tonnes of coal – 49.5% of 7,695 million tonnes world coal production. In 2011 other large producers were United States (993 million tonnes), India (589), European Union (576) and Australia (416). In 2010 the largest exporters were Australia with 328 million tonnes (27.1% of world coal export) and Indonesia with 316 million tonnes (26.1%), while the largest importers were Japan with 207 million tonnes (17.5% of world coal import), China with 195 million tonnes (16.6%) and South Korea with 126 million tonnes (10.7%).
The extraction of coal, its use in energy production and its byproducts are all associated with severe environmental and health effects. Globally, the use of coal is responsible for 44 per cent of the world's total carbon dioxide emissions.