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Starch

Starch

Starch is a complex carbohydrate which is insoluble in water. Starch (in particular cornstarch) is used in cooking for thickening sauces. In industry, it is used in the manufacture of adhesives, paper, and textiles. It is a white powder, and is tasteless and odorless.

Biochemistry

Biochemically, starch is a combination of two polymeric carbohydrates (polysaccharides) called amylose and amylopectin. Amylose is constituted by glucose monomer units joined to one another head-to-tail forming alpha-1,4 linkages. Amylopectin differs from amylose in that branching occurs, with an alpha-1,6 linkage every 24-30 glucose monomer units. The overall structure of amylopectin is not that of a linear polysaccharide chain since two glucose units frequently form a branch point, so the result is the coiled molecule most suitable for storage in starch grains. Both amylopectin and amylose are polymers of glucose, and a typical starch polymer chain consists of around 2500 glucose molecules in their varied forms of polymerisation. In general, starches have the formula (C₆H₁₀O₅)_n, where "n" denotes the total number of glucose monomer units. Structurally, the starch forms clusters of linked linear polymers, where the alpha-1,4 linked chains form columns of glucose units which branch regularly at the alpha-1,6 links. The relative content of amylose and amylopectin varies between species, and between different cultivars of the same species. For example, high-amylose corn (maize) has starch consisting of about 85% amylose, which is the linear constituent of starch, while waxy corn starch is more than 99% amylopectin, or branched starch. The primary function of starch in plants, is to act as an energy storage molecule for the organism. In plants simple sugars are linked into starch molecules by specialized cellular organs called amyloplasts. Starches are insoluble in water. They can be digested by hydrolysis, catalyzed by enzymes called amylases, which can break the glycosidic bonds between the 'alpha-glucose' components of the starch polysaccharide. Humans and other animals have amylases, so they can digest starch. Digestion of starches consists of the process of the cleavage of the starch molecules back into their constituent simple sugar units by the action of the amylases. The resulting sugars are then processed by further enzymes (such as maltase) in the body, in the same manner as other sugars in the diet.

Starches as food

Starch is often found in the fruit, seeds, and Rhizomes or tubers of plants. The four major resources for starch production and consumption in the USA are corn, potatoes, rice, and wheat. Pasta is an important dietary source of starch which is commonly prepared from wheat, rice or beans. Bread is another important source of starch and is commonly prepared from wheat. As an additive for food processing, arrowroot, guar gum, locust bean, and tapioca are commonly used as well. Commonly used starches around the world are: arracacha, buckwheat, banana, barley, cassava, konjac, kudzu, oca, sago, sorghum, sweet potato, taro and yams. Edible beans, such as favas, lentils and peas, are also rich in starch. When starch is used dietetically it is normally cooked or prepared with ingredients such as lemon, tomato, vinegar, hot pepper, onion or garlic to change its characteristic 'starchiness.' An example of this would be the use of ketchup or vinegar in the presentation of french fries or chips. When a starch is pre-cooked it can then be used to thicken chilled foods. This is referred to on packaging as modified food starch. Agar, carrageenan, gelatins and pectins are used in very much the same way.

Household

Clothing starch or laundry starch is a liquid that is prepared by mixing a vegetable starch in water (earlier preparations also had to be boiled), and is used in the laundering of clothes. During the 19th century and early 20th century, it was stylish to stiffen the collars and sleeves of men's shirts and the ruffles of girls' petticoats by applying starch to them as the clean clothes were being ironed. Aside from the smooth, crisp edges it gave to clothing, it served a practical purpose as well. Dirt and sweat from a person's neck and wrists would stick to the starch rather than fibers of the clothing, and would easily wash away along with the starch. Then, after each laundering, the starch would be reapplied.

Tests

Starch solution is used to test for elemental iodine. Distinct blue color indicates the presence of iodine in solution. The details of this reaction are not yet fully known, but it is thought that the iodine (I₃^- and I₅^- ions) fits inside the coils of amylose, the charge transfers between the iodine and the starch, and the energy level spacings in the resulting complex correspond to the absorption spectrum in the visible light region. A 0.4% w/w solution is the standard concentration for a dilute starch indicator solution. It is made by adding 4 grams of soluble starch to 1 litre of heated water; the solution is cooled before use (starch-iodine complex becomes unstable at temperatures above 35°C). This complex is often used in redox titrations: in presence of an oxidizing agent the solution turns blue, in presence of reducing agent blue color disappears because I₅^- ions break up into iodine and iodide. Under the microscope, starch grains show a distinctive Maltese Cross effect (also known as 'extinction cross') under polarised light.

Livestock

Animal starch is the common name of glycogen. It is not the same as ordinary starch.

Starch derivatives

Starch can be hydrolyzed into simpler carbohydrates by acids, various enzymes, or a combination of the two. The extent of conversion is typically quantified by dextrose equivalent (DE), which is roughly the fraction of the glycoside bonds in starch that have been broken. Food products made in this way include
- Maltodextrin, a lightly hydrolyzed (DE 10–20) starch product used as a bland-tasting filler and thickener.
- Various corn syrups (DE 30–70), viscous solutions used as sweeteners and thickeners in many kinds of processed foods.
- Dextrose (DE 100), commercial glucose, prepared by the complete hydrolysis of starch.
- High fructose syrup, made by treating dextrose solutions to the enzyme glucose isomerase, until a substantial fraction of the glucose has been converted to fructose. In the United States, high fructose corn syrup is the principal sweetener used in sweetened beverages.

External link

- Jones, Orlando, "[http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=2,000.WKU.&OS=PN/2,000&RS=PN/2,000 US2000 Improvement in the manufacture of starch]". (Class: 127/68; 48/119; 127/69). Middlesex, England, USPTO. Category:Nutrition Category:Polysaccharides ms:Kanji ja:デンプン

Carbohydrate

Carbohydrates are chemical compounds that contain oxygen, hydrogen, and carbon atoms. They consist of monosaccharide sugars of varying chain lengths and that have the general chemical formula C_n(H₂O)_n or are derivatives of such. Certain carbohydrates are an important storage and transport form of energy in most organisms, including plants and animals. Carbohydrates are classified by the number of sugar units into monosacchharides (such as glucose), disaccharides (such as saccharose), oligosaccharides, and polysaccharides (such as starch, glycogen, and cellulose).

Structure

cellulose)]] cellulose)]] Pure carbohydrates contain carbon, hydrogen, and oxygen atoms, in a 1:2:1 molar ratio, giving the general formula C_n(H₂O)_n. (This applies only to monosaccharides, see below, although all carbohydrates have the more general formula C_n(H₂O)_m.) However, many important "carbohydrates" deviate from this, such as deoxyribose and glycerol, although they are not, in the strict sense, carbohydrates. Sometimes compounds containing other elements are also counted as carbohydrates (e.g. chitin, which contains nitrogen). The simplest carbohydrates are monosaccharides, which are small straight-chain aldehydes and ketones with many hydroxyl groups added, usually one on each carbon except the functional group. Other carbohydrates are composed of monosaccharide units and break down under hydrolysis. These may be classified as disaccharides, oligosaccharides, or polysaccharides, depending on whether they have two, several, or many monosaccharide units..

Monosaccharides

Monosaccharides may be divided into aldoses, which have an aldehyde group on the first carbon atom, and ketoses, which typically have a ketone group on the second. They may also be divided into trioses, tetroses, pentoses, hexoses, and so forth, depending on how many carbon atoms they contain. For instance, glucose is an aldohexose, fructose a ketohexose, and ribose an aldopentose. Further, each carbon atom that supports a hydroxyl group (except for the first and last) is optically active, allowing a number of different carbohydrates with the same basic structure. For instance, galactose is an aldohexose but has different properties from glucose because the atoms are arranged differently. galactose) ]] The straight-chain structure described here is only one of the forms a monosaccharide may take. The aldehyde or ketone group may react with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, in which case there is an oxygen bridge between the two carbon atoms, forming a heterocyclic ring. Rings with five and six atoms are called furanose and pyranose forms and exist in equilibrium with the straight-chain form. It should be noted that the ring form has one more optically active carbon than the straight-chain form, and so has both an alpha and a beta form, which interconvert in equilibrium. However, the carbohydrate may further react with an alcohol to form an acetal or ketal, in which case the two forms become distinct. This is the basic type of link between the monosaccharide units of larger carbohydrates.

Disaccharides

Disaccharides are composed of two monosaccharide units bound together by a covalent glycosidic bond. The binding between the two sugars results in the loss of a hydrogen atom (H) from one molecule and a hydroxyl group (OH) from the other. The most common disaccharides are sucrose (cane or beet sugar - made from one glucose and one fructose), lactose (milk sugar - made from one glucose and one galactose) and maltose (made of two glucoses). The formula of these disaccharides is C₁₂H₂₂O₁₁.

Oligosaccharides and polysaccharides

Oligosaccharides and polysaccharides are composed of longer chains of monosaccharide units bound together by glycosidic bonds. The distinction between the two is based upon the number of monosaccharide units present in the chain. Oligosaccharides typically contain between three and nine monosaccharide units, and polysaccharides contain greater than ten monosaccharide units. Definitions of how large a carbohydrate must be to fall into each category vary however. Oligosaccharides are found as a common form of protein posttranslational modification. Polysaccharides represent an important class of biological polymer. Examples include starch, cellulose and chitin. Table and powdered sugar are some of the foods you find disaccharides in.

Nutrition

chitin Strictly speaking, carbohydrates are not necessary for human nutrition because proteins can be converted to carbohydrates—the traditional diet of some peoples consists of virtually no carbohydrate, and they are perfectly healthy. However, carbohydrates require less water to digest than proteins or fats and are an important source of energy. The (very) low carbohydrate diet is infamous for producing temporary “brain fog” because your brain and central nervous system function almost exclusively on glucose. Some problems have been cited for the long term effects of a no-carbohydrate diet for some individuals. Athletes, for instance, or those that participate in high intensity activities, will have a considerable reduction in performance, due to having little to no glycogen supplies stored in muscle tissue. Additionally, nephrotoxicity may occur, particularly in persons that are not very well hydrated. Some examples of different carbohydrate rich foods are beans, bread and pasta.

Catabolism

There are three major metabolic pathways of carbohydrate catabolism: # Glycolysis # Citric acid cycle

External links

- [http://www.chem.qmw.ac.uk/iupac/2carb/ IUPAC-IUBMB Joint Commission on Biochemical Nomenclature (JCBN): Carbohydrate Nomenclature]
- [http://www.cem.msu.edu/~reusch/VirtualText/carbhyd.htm Carbohydrates detailed]
- [http://www.carbohydrate-counter.org/about-carbohydrates.php Carbohydrates Overview]
- [http://www.biochemweb.org/carbohydrates.shtml Carbohydrates and Glycosylation - The Virtual Library of Biochemistry and Cell Biology]
- [http://www.functionalglycomics.org/static/consortium/ Consortium for Functional Glycomics] Category:Carbohydrates Category:Nutrition ko:탄수화물 ja:炭水化物 th:คาร์โบไฮเดรต

Insoluble

A substance is soluble in a fluid if it dissolves in that fluid. The dissolved substance is called the solute and the dissolving fluid (usually present in excess) is called the solvent, which together form a solution. The process of dissolving is called solvation, or hydration if the solvent is water. A solution at equilibrium cannot hold any more solute and is said to be saturated. Solutions may, under special conditions, hold more solute than the solvent can normally dissolve. This is called supersaturation. The maximum equilibrium amount of solute which can normally dissolve per amount of solvent (or solution) is the solubility of that solute in that solvent. It is often expressed as a maximum concentration of a saturated solution. The solubility of one substance dissolving in another is determined by the intermolecular forces between the solvent and solute, temperature, the entropy change that accompanies the solvation, the presence and amount of other substances, and sometimes pressure or partial pressure of a solute gas. For salts, solubility in aqueous solutions is often dependent on a solubility constant. The solubility constant is a special case of an equilibrium constant for the reaction of dissolving the salt in question, with the concentration of undissolved compound not in the expression because it is not in the aqueous phase. The solubility constant is also "applicable" (i. e. useful) to precipitation, the reverse of the dissolving reaction. As with other equilibrium constants, temperature can affect the numerical value of solubility constant. Solvents are normally characterized as polar or nonpolar. Polar solvents will dissolve ionic compounds and covalent compounds which ionize, while nonpolar solvents will dissolve nonpolar covalent compounds. For example, ordinary table salt, an ionic compound, will dissolve in water, but not in ethanol. Common solvents used in organic chemistry include acetone, ethanol, water, and benzene. Water and nonpolar solvents are immiscible; they do not form homogeneous mixtures but separate into two distinct phases or form milky emulsions. While solutions are typically thought of as solids being mixed into liquids, any two states of matter can be mixed and be called a solution. Carbonated water is a solution of a gas in a liquid, hydrogen (a gas) can dissolve in palladium (a solid), and stainless steel is a solution of a solid in a solid (called an alloy).

Solubility of bonding type in water

Bonding type	Solubility in water	Example
ionic	most soluble	See below
metallic	insoluble	Fe
metallic	unless they react with water	K
polar covalent	soluble if it H bonds	glucose
	soluble by reaction	HCl
	insoluble otherwise	ether
non-polar covalent	most insoluble	benzene
non-polar covalent	some slightly soluble	O₂
covalent lattice	insoluble	diamond

Solubility of ionic compounds

Soluble	Insoluble
Group 1 and NH₄⁺ compounds	carbonates (except Group 1 and NH₄⁺ compounds)
nitrates	sulfites (except Group 1 and NH₄⁺ compounds)
acetates (ethanoates)	phosphates (except Group 1 and NH₄⁺ compounds)
chlorides, bromides and iodides (except Ag⁺, Pb²⁺, Cu⁺ and Hg₂²⁺)	hydroxides and oxides (except Group 1, NH₄⁺, Ba²⁺, Sr²⁺ and Ca²⁺)
sulfates (except Ag⁺, Pb²⁺, Ba²⁺, Sr²⁺ and Ca²⁺)	sulfides (except Group 1, Group 2 and NH₄⁺ compounds)

Software tools for prediction of solution

One of the most recent and prominent solution (solubility) prediction technologies is applied in [http://www.q-pharm.com/home/contents/drug_d/soft/ Quantum 3.1] that is a suite of Molecular Modeling software for Linux and Windows. The software calculates the solvation energy and solubility for a molecule or a library of molecules in a number of solvents (e.g. water and DMSO). The Quantum 3.1 [http://www.q-pharm.com/home developer] is also a service provider.

Cornstarch

Cornstarch, or cornflour, is the starch of the maize grain, commonly known as corn. It has a distinctive appearance and feel when mixed raw with water or milk, giving easily to gentle pressure but resisting sudden pressure. It is usually included as an anti-caking agent in powdered sugar (10X or confectioner's sugar). For this reason, recipes calling for powdered sugar often call for at least light cooking to remove the raw cornstarch taste. Cornstarch is often used as a binder in puddings and similar foods. Most of the packaged pudding mixes available in grocery stores include cornstarch. Cornstarch puddings may be easily made at home, benefitting from the use of a double boiler. The most basic such pudding may be made only from milk, sugar, cornstarch and a flavoring agent. It is also used as a thickener in many Chinese recipes and French sauces, although in the latter case it is generally used as a time-saver to replace more traditional, time-consuming methods. Cornstarch also has many uses in the manufacturing of environmentally-friendly products. For example, in 2004, the Japanese company Pioneer announced a biodegradable Blu-Ray disc made out of cornstarch. A mixture of equal volumes cornstarch and water (sometimes called oobleck) is a popular classroom demonstration of a dilatant (shear-thickening) fluid. When struck, cut with a knife, or worked vigorously in the hands, it behaves like a pliable solid, but if allowed to sit for a few seconds, it flows as a viscous liquid. In Britain, this substance is known as cornflour.

External links

- [http://www.youtube.com/watch.php?v=CH6-2UizHfI&search=science A video of the unusual behavior of cornstarch mixed with water] Category:Edible thickening agents

Sauce

: For the computer protocol, see SAUCE In cooking, a sauce is a liquid served on or used in the preparation of food. Sauces are not consumed by themselves; they add flavour, moisture, and visual appeal to another dish. Sauce is a French word taken from the Latin salsus, meaning salted. Sauces may be prepared sauces, such as soy sauce, which are usually bought, not made, by the cook; or cooked sauces, such as Béchamel sauce, which are generally made just before serving. Sauces for salads are called salad dressing. Sauces are an essential element in cuisines all over the world.

Sauces in French cuisine

Sauces in French cuisine date back to Medieval times. There were hundreds of sauces in the lore. In 'classic' French cooking (19th and 20th century until nouvelle cuisine), sauces were a major defining characteristic of French cuisine. In the 19th century, the chef Antoine Carême classified sauces into four families, each of which was based on a mother sauce. Carême's four mother sauces were:
- Allemande
- Béchamel is based on flour and milk
- Espagnole is based on brown stock, beef etc.
- Velouté is based on a light broth, fish, chicken or veal. In the early 20th century, the chef Auguste Escoffier updated the classification, replacing sauce Allemande with egg-based emulsions (Hollandaise and mayonnaise), and adding tomate. Escoffier's schema is still taught to chefs today:
- Béchamel
- Espagnole
- Hollandaise
- Mayonnaise
- Tomato sauce
- Velouté

Sauces in other cuisines

Sauces and condiments also play an important role in other cuisines:
- British cooking: Gravy is a traditional sauce used on roast dinner, comprising roast potatoes, roast meat, boiled vegetables and optional Yorkshire puddings. Apple sauce and mint sauce are also used on meat. Salad cream is used on salads. Ketchup and brown sauce are used on more fast-food type dishes. Strong English mustard (as well as French or American mustard) are also used on various foods, as is Worcestershire sauce. Custard is a popular dessert sauce. Some of these sauce traditions have been exported to ex-colonies such as the USA.
- Japanese cuisine uses ponzu, yakitori, tonkatsu, and yakisoba sauces.
- Chinese cuisine is known for prepared sauces based on fermented soy beans (soy sauce, black bean sauce, hoisin sauce) as well as many others such as chili sauces and oyster sauce.
- Southeast Asian cuisines, such as Thai and Vietnamese cuisine, often use fish sauce, made from fermented fish. Asian prepared sauces are not thick as they do not contain thickening agents such as flour. The thickening occurs in the last minutes of cooking when thickeners like corn starch or arrowroot are added.

Sauce variations

There are also many sauces based on tomato (such as tomato ketchup and tomato sauce), other vegetables and various spices. Although the word 'ketchup' by itself usually refers to tomato ketchup, other vegetables or fruits may be used to prepare ketchups. Sauces can also be sweet, and used either hot or cold to accompany and garnish a dessert. Another kind of sauce is made from stewed fruit, usually strained to remove skin and fibers and often sweetened. Such sauces, including applesauce and cranberry sauce, are often eaten with specific other foods (apple sauce with pork or ham; cranberry sauce with poultry) or served as desserts.

Examples of sauces

White sauces
- Mushroom sauce
- Sauce Allemande
- Sauce Américaine
- Sauce Suprême
- Velouté Brown sauces
- Bordelaise sauce
- Bourguignonne sauce
- Chateaubriand sauce
- Sauce Africaine
- Sauce Robert Béchamel family
- Béchamel sauce
- Mornay sauce Emulsified sauces
- Béarnaise sauce
- Hollandaise sauce
- Mayonnaise
- Tartar sauce
- Salad cream Butter sauces
- Beurre blanc
- Café de Paris Sweet sauces
- Butterscotch sauce
- Chocolate or fudge sauce
- Custard
- Crème anglaise
- Hard sauce -- not liquid, but called a sauce nonetheless
- Fruit sauces
- Applesauce
- Cranberry sauce Sauces made of chopped fresh ingredients
- Latin American Salsa cruda of various kinds
- Salsa verde Hot sauces
- Datil Pepper Sauce
- Chili sauce
- Tabasco sauce East Asian sauces
- Prepared sauces
- Black bean sauce
- Duck sauce, or Plum sauce
- Hoisin sauce
- Oyster sauce
- Soy sauce
- Cooked sauces
- Lobster sauce
- Sweet and sour sauce
- Teriyaki - a way of cooking in Japan, a branch of sauces in North America. Southeast Asian sauces
- Fish sauce
- Sambal Other sauces
- Barbecue sauce
- Mole
- Tomato sauce
- Tzatziki

References

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- ja:ソース

Adhesive

An adhesive is a compound that adheres or bonds two items together. Adhesives may come from either natural or synthetic sources. Some modern adhesives are extremely strong, and are becoming increasingly important in modern construction and industry.

History

The first adhesives were gums and other plant resins. Archaeologists have found 6000-year-old ceramic vessels that had broken and been repaired using plant resin. Most early adhesives were animal glues made by rendering animal products such as the Native American use of buffalo hooves. Native Americans in what is now the eastern United States used a mixture of spruce gum and fat as adhesives and as caulk to waterproof seams in their birchbark canoes.

Categories of adhesives

Drying adhesives

These adhesives are a mixture of ingredients (typically polymers) dissolved in a solvent. Glues and rubber cements are members of the drying adhesive family. As the solvent evaporates, the adhesive hardens. Depending on the chemical composition of the adhesive, they will adhere to different materials to greater or lesser degrees. These adhesives are typically weak and are used for household applications. Some intended for small children are now made non-toxic.

Hot adhesives

polymers Also known as "hot melt" adhesives, these adhesives are applied hot and simply allowed to harden as they cool. These adhesives have become popular for crafts because of their ease of use and the wide range of common materials to which they can adhere. A glue gun, pictured right, is one method of applying a hot adhesive. The glue gun melts the solid adhesive and then allowing it to pass through the "barrel" of the gun onto the material where it solidifies.

Reactive adhesives

Epoxy resins are the most common example of this kind of adhesive. Reactive adhesives generally come in two separate containers. The two ingredients of the adhesive must be mixed in certain proportions immediately before application. Generally one ingredient is a monomer, or resin, and the second is a reaction initialiser. When the two are mixed together, a polymerisation reaction occurs which solidifies the adhesive. Reaction adhesives may also react with the surface of the materials to be stuck together. This process is called bonding, in which the adhesive forms chemical bonds with the material, and is distinct from sticking, the action of common glues. A special case of this kind of adhesive is cyanoacrylate (more commonly known by the brand name "super glue") which reacts with trace moisture on the surfaces being bonded and therefore does not need any mixing before application. Reactive adhesives are very strong and are used for high-stress applications such as attaching wings to aircraft. Because the strength of a reactive adhesive is a result of chemical bonding with the surface material, reactive adhesives are applied in thin films. Reactive adhesives are less effective when there is a secondary goal of filling gaps between the surfaces.. Such adhesives are frequently used to prevent loosening of bolts and screws in rapidly moving assemblies, such as automobile engines. They are largely responsible for the quieter running modern car engines.

Temporary adhesives

Temporary adhesives are designed to repeatedly or easily stick and unstick. They have low adhesion and generally can not support much weight. They are commonly used on paper, but can be used on many other things. They have common applications such as as bookmarks, informal notes, and office supplies. Brands include Blu-Tack, a gum-like adhesive (a.k.a. "sticky tak"), adhesive bandages, and the pressure-activated adhesive applied to the back of 3M's Post-It notes. The adhesives on items such as duct tape can generally adhere longer than these other products. Also see adhesive tape and gaffer tape.

Adhesive failure

Adhesives may fail in one of two ways: Adhesive failure is the failure of the adhesive to stick or bond with the material to be adhered (also known as the substrate or adherend). Cohesive failure is structural failure of the adhesive. Adhesive remains on both substrate surfaces, but the two items separate. Two substrates can also separate through structural failure of one of the substrates; this is not a failure of the adhesive. In this case the adhesive remains intact and is still bonded to one substrate and the remnants of the other. For example, when one removes a price label, adhesive usually remains on the label and the surface. This is cohesive failure. If, however, a layer of paper remains stuck to the surface, the adhesive has not failed. As another example, children often try to pull apart Oreo cookies with the filling all on one side. The goal is an adhesive failure, rather than a cohesive failure. ja:接着剤

Textile

:This article is about the type of material. Textile is also a jargon term used by naturists or nudists to describe a person who wears clothes. Textile is also a kind of ReStructured Text. A textile is any type of material made from fibers or other extended linear materials such as thread or yarn (1). Classes of textiles include woven, crochet, knitted, knotted (as in macrame) or tufted cloth, and non-woven fabrics such as felt. Materials such as fiberglass, which are made from fibers dispersed in a matrix of another material are considered composite materials rather than textiles. The production of textiles is an ancient craft, whose speed and scale of production has been altered almost beyond recognition by mass-production and the introduction of modern manufacturing techniques. However, a Roman weaver would have no problem recognizing modern plain weave, twill or satin. Many textiles have been in use for millennia, while others use artificial fibers and are recent inventions. The range of fibers has increased in the last 100 years. The first synthetics were made in the 1920s and 1930s.

Sources and types

Textiles can be made from a variety of materials. The following is a partial list of the materials that can be used to make textiles.

Animal origin

- Alpaca
- Thread
- Angora rabbit hair
- Camel hair
- Cashmere
- Mohair
- Silk
- Vicuña hair
- Wool: divided into woollen and worsted

Vegetable

- Bark cloth has various uses, and is used in sheets.
- Coir: the fibre from coconuts.
- Cotton
- Grass, rush and straw
- Hemp (mostly used in rope making)
- Jute
- Kapok
- Linen, made from flax
- Nettle: processed in a similar manner to flax.
- Ramie
- Seaweed: a water soluble fibre (alginate) is produced. This is used as a holding fibre in the production of certain textiles: when the cloth is finished the alginate is dissolved, leaving an open area.
- Sisal

Derived from plant products

- Paper
- Rayon
- Modal

Mineral

- Asbestos
- Glass fibres can be used in the manufacture of textiles for insulation and other purposes.
- Metal fibre, metal wire and metal foil have some uses in textiles, either on their own or with other materials (see, for example, goldwork embroidery).

Synthetic

- Acrylic fiber
- Lurex
- Spandex, tactel, lycra and other 'stretch' fabrics
- Nylon fiber
- Polyester fiber
- Polypropylene (comes under various common trade names such as Olefin or Herculon)

Production methods

- Braiding/Plaiting
- Crochet – usually by hand.
- Felt – fibres are matted together to produce a cloth.
- Knitting – by hand or on knitting machines (see stocking frame).
- Knotting, including macrame: used in making nets.
- Lace – again both hand made and machine made.
- Pile fabrics – carpets and some rugs
- Velvet, velveteen, plush fabrics and similar have a secondary set of yarns which provide a pile.
- Weaving – the cloth is prepared on a loom, of which there are a number of types. Some weaving is still done by hand, but the vast majority is mechanised.

Processes

- Carding
- Bleaching – where the natural or original colour of the textile is removed by chemicals or exposure to sunlight.
- Dyeing – adding colour to textiles: there is a vast range of dyes, natural and synthetic, some of which require mordants.
- Textile printing
- Embroidery – threads which are added to the surface of a finished textile for ornamentation.
- Starching
- Waterproofing and other finishings.

Uses

Textiles have been used in almost every possible context where their properties are useful. In cleaning
- Bags and other means of carrying objects
- Balloons, kites, sails, parachutes and other transport use. Early airplanes used cloth as part of the construction.
- Clothing
- Flags
- Furnishings, including towels and table cloths
- Geotextiles
- Industrial and scientific uses, including filtering
- Nets
- Rugs and carpets
- Tents
- Towels

External links

- [http://www.ianr.unl.edu/pubs/homefurnish/g1316.htm Carpet construction and texture]
- [http://www.cs.arizona.edu/patterns/weaving/weavedocs.html Weaving document archive]
- [http://realmofvenus.renaissancewoman.net/seamstress/fabricglossary.htm A Glossary of Fabrics in sixteenth-Century Italy]
- [http://ozhanozturk.com/content/view/398/1/ The Anatolian art of hand-printed textiles ]

Reference

- [http://www.textilemuseum.org/PDFs/TextileTerms.pdf (1) glossary from the Textile Museum]
- [http://www.spacentime.net (2) Textile Machinery Consultant & Advisers]
- [http://www.hhtraders.com (3) Textile Machinery Dealer]
- ja:織物

Taste

Taste is one of the most common and fundamental of the senses of animals. It is the direct detection of chemical composition, usually through contact with chemoreceptor cells. Taste is very similar to olfaction (the sense of smell), in which the chemical composition of an organism's ambient medium is detected by chemoreceptors. In a liquid medium, taste is often used to describe this act as well. :Main article: Gustatory system. In humans, the sense of taste is transduced by taste buds and is conveyed via three of the twelve cranial nerves. The facial nerve (VII) carries taste sensations from the anterior two thirds of the tongue, the glossopharyngeal nerve (IX) carries taste sensations from the posterior one third of the tongue while a branch of the vagus nerve (X) carries some taste sensations from the back of the oral cavity. Information from these cranial nerves is processed by the gustatory system. :Main article:Basic taste. As a general rule, taste is a holistic assessment of the interaction of the fundamental taste systems of sweetness, sour, bitter, salty, and umami ("savouriness"). Location of the stimulus on the tongue is not important, despite the common misperception of a "taste map" of sensitivity to different tastes thought to correspond to specific areas of the tongue [http://www.med-rz.uni-sb.de/med_fak/physiol1/LDM/chemotopic_1.htm]. The "mouth map" is a myth. It is a misinterperatation of a German medical paper by a Harvard psychology student in 1901 . In reality, the separate populations of taste buds sensing each of the basic tastes are distributed across the tongue. If half of the tongue is blocked from sending information to the brain, people will report that a doubling of psychological perception has occurred for sweet, sour, salty, and bitter. See also Flavor

Terms for disorders of taste

- ageusia (complete loss)
- hypogeusia (partial loss)
- parageusia (unpleasant taste)
- dysgeusia (inaccurate taste)

Taste in aesthetics

:Main article Taste (aesthetics). Taste can also refer to appreciation for aesthetic quality, significantly applying the purely physical term to an intellectual quality. In such contexts Taste begins to be used in a metaphorical sense to refer to certain degrees of cultural competence, closely related to the concept of discrimination; it can set distinctions between "tasteful" and "tasteless" or the embodiments of "good taste" or "bad taste", thus providing categories for social division and reinforcing cultural hierarchy. The modern concept of "taste" is a product of the 16th century Italian Mannerism: the idea of "taste" as a quality that is independent of the style that is simply its vehicle — though the style might be designated a taste, such as "the Antique taste"— was born in the circle of Pope Julius III and first realized at the Villa Giulia he built on the edge of Rome in 1551 - 1555. To the Enlightenment, "taste" was still a universal character, which could be recognized by what pleased any cultured sensibility. With the shift in perspective that Romanticism brought, it began to be thought that, to the contrary, "Beauty is in the eye of the beholder" and could be individually interpreted, with results that might be of equivalent aesthetic value.

Taste as a metaphor for experience or knowledge

To taste is also used metaphorically to describe having a small amount of experience with something that gives a sense of its quality as a whole. For example: "they had not yet tasted the sweetness of freedom" (Livy) or "I tasted in her arms the delights of paradise" (Voltaire). The word is often used as a noun in this sense, typically in such expressions as "I got a taste of it" or "It left a bad taste in my mouth."

Polymer

Polymer is a generic term used to describe a very long molecule consisting of structural units and repeating units connected by covalent chemical bonds. The key feature that distinguishes polymers from other molecules is the repetition of many identical, similar, or complementary molecular subunits in these chains. These subunits, the monomers, are small molecules of low to moderate molecular weight, and are linked to each other during a chemical reaction called polymerization. Instead of being identical, similar monomers can have varying chemical substituents. The differences between monomers can affect properties such as solubility, flexibility, and strength. In proteins, these differences give the polymer the ability to adopt a biologically-active conformation in preference to others. (See self-assembly.) Identical monomers with nonreactive side groups result in a polymer chain that will tend to adopt a random coil conformation, as described by an ideal chain mathematical model. Although most polymers are organic, with carbon-based monomers, there are also inorganic polymers; for example, the silicones, with a backbone of alternating silicon and oxygen atoms. Polymers are typically classified according to three main groups:
- thermoplastics (linear or branched chains)
- thermosets (crosslinked chains)
- elastomers The term polymer covers a large, diverse group of molecules, including substances from proteins to stiff, high-strength Kevlar fibres. For example, the formation of polyethene (also called polyethylene) involves thousands of ethene molecules bonded together to form a straight (or branched) chain of repeating -CH₂-CH₂- units (with a -CH₃ at each terminal): image:example_polymerization.png Polymers are often named in terms of the monomer from which they are made. Because it is synthesized from ethene in a process during which all the double bonds in the vinyl monomers are lost, polyethene has the unsaturated structure: image:polyethene_monomer.png If it were named according to its final structure, it would have the alkane designation "polyethane". Because synthetic polymer formation is governed by random assembly from the constituent monomers, polymer chains within a solution or substance are generally not of equal length. This is unlike basic, smaller molecules in which every atom is stoichiometrically accounted for, and each molecule has a set molecular mass. An ensemble of differing chain lengths, often obeying a normal (Gaussian) distribution, occurs because polymer chains terminate during polymerization after random amounts of chain lengthening (propagation). Proteins are polymers of amino acids. Typically, hundreds of the (nominally) twenty different amino acid monomers make up a protein chain, and the sequence of monomers determines its shape and biological function. (There are also shorter oligopeptides which function as hormones.) But there are active regions, surrounded by, as is believed now (Aug 2003), structural regions, whose sole role is to expose the active regions. (There may be more than one on a given protein.) So the exact sequence of amino acids in certain parts of the chains can vary from species to species, and even given mutations within a species, so long as the active sites are properly accessible. Also, whereas the formation of polyethylene occurs spontaneously under the right conditions, the synthesis of biopolymers such as proteins and nucleic acids requires the help of enzyme catalysts, substances that facilitate and accelerate reactions. Unlike synthetic polymers, these biopolymers have exact sequences and lengths. (This does not include the carbohydrates.) Since the 1950s, catalysts have also revolutionised the development of synthetic polymers. By allowing more careful control over polymerization reactions, polymers with new properties, such as the ability to emit coloured light, have been manufactured. The characterization of a polymer requires several parameters which need to be specified. This is because a polymer actually consists of a statistical distribution of chains of varying lengths, and each chain consists of monomer residues which affect its properties. Some of these parameters are described below.

Physical properties of polymers

Physical properties of polymers include the degree of polymerization, molar mass distribution, crystallinity, as well as the thermal phase transitions:
- T_g, glass transition temperature
- T_m, melting point (for thermoplastics).

Branching

During the propagation of polymer chains, branching can occur. In free-radical polymerization, this occurs when a chain curls back and bonds to an earlier part of the chain. When this curl breaks, it leaves small chains sprouting from the main carbon backbone. Branched carbon chains cannot line up as close to each other as unbranched chains can. This causes less contact between atoms of different chains, and fewer opportunities for induced or permanent dipoles to occur. A low density results from the chains being further apart. Lower melting points and tensile strengths are evident, because the intermolecular bonds are weaker and require less energy to break. Besides branching, polymers can have other topologies: linear, network (cross-linked 3D structure), IPN (integrated polymer network), comb, or star as well as dendrimer and hyperbranched structures.

Stereoregularity

Stereoregularity or tacticity describes the isomeric arrangement of functional groups on the backbone of carbon chains. Isotactic chains are defined as having substituent groups aligned in one direction. This enables them to line up close to each other, creating crystalline areas and resulting in highly rigid polymers. In contrast, atactic chains have randomly aligned substituent groups. The chains do not fit together well and the intermolecular forces are low. This leads to a low density and tensile strength, but a high degree of flexibility. Syndiotactic substituent groups alternate regularly in opposite directions. Because of this regularity, syndiotactic chains can position themselves close to each other, though not as close as isotactic polymers. Syndiotactic polymers have better impact strength than isotactic polymers because of the higher flexibility resulting from their weaker intermolecular forces.

Constitution of polymers

Copolymers

Copolymerization with two or more different monomers results in chains with varied properties. There are twenty amino acid monomers whose sequence results in different shapes and functions of protein chains. Copolymerising ethene with small amounts of 1-hexene (or 4-methyl-1-pentene) is one way to form linear low-density polyethene (LLDPE). (See polyethylene.) The C₄ branches resulting from the hexene lower the density and prevent large crystalline regions from forming within the polymer, as they do in HDPE. This means that LLDPE can withstand strong tearing forces whilst remaining flexible. A block copolymer is formed when the reaction is carried out in a stepwise manner, leading to a structure with long sequences or blocks of one monomer alternating with long sequences of the other. There are also graft copolymers, in which entire chains of one kind (e.g., polystyrene) are made to grow out of the sides of chains of another kind (e.g., polybutadiene), resulting in a product that is less brittle and more impact-resistant. Thus, block and graft copolymers can combine the useful properties of both constituents and often behave as quasi-two-phase systems. The following is an example of step-growth polymerization, or condensation polymerization, in which a molecule of water is given off and nylon is formed. The properties of the nylon are determined by the R and R' groups in the monomers used. nylon The first commercially successful, completely synthetic polymer was nylon 6,6, with alkane chains R = 4C (adipic acid) and R' = 6C (hexamethylene diamine). Including the two carboxyl carbons, each monomer donates 6 carbons; hence the name. In naming nylons, the number of carbons from the diamine is given first and the number from the diacid second. Kevlar is an aromatic nylon in which both R and R' are benzene rings. Copolymers illustrate the point that the repeating unit in a polymer, such as a nylon, polyester or polyurethane, is often made up of two (or more) monomers.

Chemical properties of polymers

Intermolecular forces

The attractive forces between polymer chains play a large part in determining a polymer's properties. Because polymer chains are so long, these interchain forces are amplified far beyond the attractions between conventional molecules. Also, longer chains are more amorphous (randomly oriented). Polymers can be visualised as tangled spaghetti chains - pulling any one spaghetti strand out is a lot harder the more tangled the chains are. These stronger forces typically result in high tensile strength and melting points. The intermolecular forces in polymers are determined by dipoles in the monomer units. Polymers containing amide groups can form hydrogen bonds between adjacent chains; the positive hydrogen atoms in N-H groups of one chain are strongly attracted to the oxygen atoms in C=O groups on another. These strong hydrogen bonds result in, for example, the high tensile strength and melting point of kevlar. Polyesters have dipole-dipole bonding between the oxygen atoms in C=O groups and the hydrogen atoms in H-C groups. Dipole bonding is not as strong as hydrogen bonding, so ethene's melting point and strength are lower than kevlar's, but polyesters have greater flexibility. Ethene, however, has no permanent dipole. The attractive forces between polyethene chains arise from weak van der Waals forces. Molecules can be thought of as being surrounded by a cloud of negative electrons. As two polymer chains approach, their electron clouds repel one another. This has the effect of lowering the electron density on one side of a polymer chain, creating a slight positive dipole on this side. This charge is enough to actually attract the second polymer chain. Van der Waals forces are quite weak, however, so polyethene melts at low temperatures.

Polymer characterization

A variety of lab techniques are used to determine the properties of polymers. Techniques such as wide angle X-ray scattering, small angle X-ray scattering, and small angle neutron scattering are used to determine the crystalline structure of polymers. Gel permeation chromatography is used to determine the number average molecular weight, weight average molecular weight, and polydispersity. FTIR is used to determine composition. Thermal properties such as the glass transition temperature and melting point can be determined by differential scanning calorimetry and dynamic mechanical analysis. Pyrolysis followed by analysis of the fragments is one more technique for determining the possible structure of the polymer. Polymer known as polymer substrate is used for everyday banknotes in Australia and New Zealand, and is also used in commemorative notes in other countries. See also: Polymerization -- Biopolymer -- Condensation polymer -- Addition polymer -- Synthetic polymer -- Glass transition temperature -- Polymer physics -- Important publications in polymer chemistry

External links

- [http://www.borealisgroup.com/public/dictionary/Dictionary.jsp Polymer dictionary]
- [http://www.vivamer.com/ Responsive Biopolymers for Drug Delivery and Imaging]
- [http://web.umr.edu/~wlf/ Polymer Chemistry Hypertext, Educational resource]
- [http://www.polychemistry.com/ Polymer Chemistry Innovations]
- [http://www.odcad.com/html/organicdevice_appearance1.HTM Materials for Organic devices]
- [http://www.pslc.ws/macrog/index.htm The Macrogalleria - a cyberwonderland of polymer fun!] Category:Polymers Category:Polymer chemistry ko:중합체 ms:Polimer ja:重合体 th:โพลีเมอร์

Polysaccharide

Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. They are polymers made up of many monosaccharides joined together by glycosidic linkages. They are therefore very large, often branched, molecules. They tend to be amorphous, insoluble in water, and have no sweet taste. When all the constituent monosaccharides are of the same type they are termed homopolysaccharides; when more than one type of monosaccharide is present they are termed heteropolysaccharides. Examples include storage polysaccharides such as starch and glycogen and structural polysaccharides such as cellulose and chitin. Polysaccharides have a general formula of C_n(H₂O)_n-1 where n is usually a large number between 200 and 500.

Starches

Starches are polymers of glucose in which glucopyranose units are bonded by alpha-linkages. Amylose consists of a linear chain of several hundred glucose molecules. Amylopectine is a branched molecule made of several thousand of glucose units.
Starches are insoluble in water. They can be digested by hydrolysis catalyzed by enzymes called amylases, which can break the alpha-linkages. Humans and other animals have amylases, so they can digest starches. Potato, rice, wheat, and maize are major sources of starch in the human diet.

Glycogen

Glycogen is the storage form of glucose in animals. It is a branched polymer of glucose. Glycogen can be broken down to form substrates for respiration, through the process of glycogenolysis. This involves the breaking of most of the C-O-C bonds between the glucose molecules by the addition of a phosphate, rather than a water as in hydrolysis. This process yields phosphorylated glucose molecules, which can be metabolized with a saving of one ATP molecule.

Cellulose

The structural components of plants are formed primarily from cellulose. Wood is largely cellulose and lignin, while paper and cotton are nearly pure cellulose. Cellulose is a polymer made with repeated glucose units bonded together by beta-linkages. Humans and many other animals lack an enzyme to break the beta-linkages, so they do not digest cellulose. Certain animals can digest cellulose, because bacteria possessing the enzyme are present in their gut. The classic example is the termite.

Acidic polysaccharides

Acidic polysaccharides are polysaccharides that contain carboxyl groups, phosphate groups and/or sulfuric ester groups.

Bacterial Capsule Polysaccharides

Pathogenic bacteria commonly produce a thick, mucous-like, layer of polysaccharide. This "capsule" cloaks antigenic proteins on the bacterial surface which would otherwise provoke an immune response, thereby leading to the destruction of the bacteria. Capsular polysaccharides are water soluble, commonly acidic, and have molecular weights on the order of 100 - 1000 kDa. They are linear and consist of regularly repeating subunits of one ~ six monosaccharides. There is enormous structural diversity; nearly two hundred different polysaccharides are produced by E. coli alone. Mixtures of capsular polysaccharides, either conjugated or native are used as vaccines. Category:Organic polymers Category:Polysaccharides ja:多糖

Amylopectin

Amylopectin (CAS# 9037-22-3) is a highly branched polymer of glucose found in plants. It is one of the two components of starch, the other being amylose. Glucose units are linked in a linear way with α(1→4) bonds. Branching takes place with α(1→6) bonds occurring every 24 to 30 glucose units. Its counterpart in animals is glycogen which has the same composition and structure, but with more extensive branching that occurs every 8 to 12 glucose units. Category:Polysaccharides ja:アミロペクチン

Maize

:This article is about the cereal. For the town, see Maize, Kansas. Maize (Zea mays ssp. mays) is a cereal grain that was domesticated in Mesoamerica. It is called corn in the United States, Canada, and Australia but there are further regional differences in terminology. While some maize varieties grow 7 m (23 ft) tall at certain locations, commercial maize has been bred for a high-end height of 2.5 m (9 ft). Sweet corn is usually shorter than field corn varieties.

Maize physiology

The stems look like bamboo cane and the joints (nodes) are about 40–50 cm (16–20 inches) apart. Maize has a very distinct growth form, the lower leaves being like broad flags, 50–100 cm long and 5–10 cm wide (2–4 feet by 2–4 inches); the stems are erect, from 2–3 m (7–10 feet) in height, with many nodes, casting off flag-leaves at every node. Under these leaves and close to the stem grows the corn, covered over by several layers of leaves, and so closed in by them to the stem, that it does not show itself easily till there bursts out at the end of the ear a number of strings, called silk, that look like tufts of horsehair, at first green, and afterwards red or yellow. The top of the stem ends in a flower, called the tassle. For each silk on which pollen from the tassle lands, one kernel of corn is produced. Young ears can be consumed raw, cob, silk, and all; as the plant matures (usually during the summer months) the cob toughens and the silk dries to inedibility. By late August the kernels have dried out and become difficult to chew without cooking them tender first in boiling water. The kernel of corn has a pericarp of the fruit fused with the seed coat, typical of the grasses. It is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows round a white pithy substance, which forms the ear. An ear contains from two to four hundred grains, and is from 10–25 cm (4–10 inches) in length. They are of various colors, blackish, red, white and yellow. When ground into flour, it yields more flour, with much less bran, than wheat does. However, it lacks the protein gluten, and therefore makes baked goods with poor raising capability.

Genetics

Maize has 10 chromosomes (n=10). The combined length of the chromosomes is 1500 cM. Some of the maize chromosomes have what are know as "chromosomal knobs". They are highly repetitive heterochromatic domains that stain darkly. Individual knobs are polymorphic among strains of both maize and teosinte. Barbara McClintock used these knob markers to prove her transposon theory of "jumping genes".

Origin of maize

transposon Maize is a direct domesticate of the teosinte Zea mays ssp. parviglumis, native to the Balsas River Valley of southern Mexico, with up to 12% of its genetic material obtained from Zea mays ssp. mexicana through introgression. The term teosinte describes all species in the genus Zea, excluding Zea mays ssp. mays. Maize development is thought to have started from 7,500 to 12,000 years ago. The domestication of maize is of particular interest to researchers. It is unknown what precipitated its domestication, because the edible portion of the wild variety is too small to be worth cultivating. It would have taken many generations of selective breeding in order to produce a plant with cobs large enough to eat. Archaeological remains of the earliest maize cob, found at Guila Naquitz Cave in the Oaxaca Valley of Mexico, date back roughly 6,250 years. Maize was the staple food, or a major staple, of all the pre-Columbian Mesoamerican civilizations. During the 1st millenium CE, maize cultivation spread from Mexico across North America, transforming the landscape as Native Americans cleared large forest and grassland areas for the new crop. In the late 1930s, Paul Mangelsdorf suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and Tripsacum. However, the proposed role of the related genus Tripsacum in the origins of maize has been refuted by modern genetic analysis.

Cultivation

Paul Mangelsdorf] Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. While the United States produces almost half of the world's harvest, other top producing countries are as widespread as China, India, Brazil, France, Indonesia, and South Africa. Worldwide production was over 600 million metric tons in 2003, just slightly more than rice or wheat. Maize is planted in the spring to take advantage of spring rains. Its root system is shallow and the plant is dependent on steady rain or irrigation. In the United States, a good harvest was predicted traditionally if the corn was "knee-high by the Fourth of July", although modern hybrids often exceed this growth rate. Maize used as silage is harvested while the plant is green and the fruit unmatured. Otherwise, maize is left in the field very late in the autumn in order to dry thoroughly. In fact, it is sometimes not harvested until winter or even early spring. The importance of regular rain is shown in many parts of Africa, where periodic drought regularly causes famine by causing maize crop failure; the older traditional African native millet (which is however less palatable than maize, and much less productive in good years) would have survived and produced a small crop in these conditions. millet] Maize was planted by the Native Americans in hills, in a complex system known to some as the Three Sisters: beans used the corn plant for support, and squashes provided ground cover to stop weeds. This method was replaced by single species hill planting where each hill 60–120 cm (2–4 feet) apart was planted with 3 or 4 seeds, a method still used by the home gardener. A later technique was checked corn where hills were placed 40 inches apart in each direction, allowing cultivators to run through the field in two directions. In more arid lands this was altered and seed were planted in the bottom of 10–12 cm (4–5 inch) deep furrows to collect water. Modern technique plants maize in rows which allows for cultivation while the plant is young. In North America, fields are often planted in a two-crop rotation with a nitrogen-fixing crop, often soybeans. Sometimes a third crop, winter wheat, is added to the rotation. Fields are usually plowed each year, although no-till farming is increasing in use. Before about World War II, most maize was harvested by hand. This often involved large numbers of workers and associated social events. Some one- and two-row mechanical pickers were in use but the corn combine did not get adopted until after the War. By hand or mechanical picker, the entire ear is harvested which then requires a separate operation of a corn sheller to remove the kernels from the ear. Whole ears of corn were often stored in corn cribs which is a sufficient form for some livestock use. Some modern farms store maize in this manner and later shell it for sale in the off-season to capture better prices. The combine with a corn head (with points and snap rolls instead of a reel) cuts the stalk near the base and then separates the ear of corn from the stalk so that only the ear and husk enter the machinery. The combine separates the husk and the cob, keeping only the kernels.

Pests of maize

Insect pests

combine
- Corn earworm (Heliothis zea)
- Fall armyworm (Spodoptera frugiperda)
- Common armyworm (Pseudaletia unipuncta)
- Stalk borer (Papaipema nebris)
- Corn leaf aphid (Rhopalosiphum maidis)
- European corn borer (Ostrinia nubilalis) (ECB)
- Corn silkfly (Euxesta stigmatis)
- Lesser cornstalk borer (Elasmopalpus lignosellus)
- Corn delphacid (Peregrinus maidis) The susceptibility of maize to the European corn borer, and the resulting large crop losses, led to the development of transgenic corn expressing the Bacillus thuringiensis (Bt) toxin. Bt corn is widely grown in the United States and has been approved for release in Europe.

Diseases

- Corn smut or common smut (Ustilago maydis): a fungal disease, known in Mexico as huitlacoche, which is prized by some as a gourmet delicacy in itself.
- Maize Dwarf Mosaic Virus
- Stewart's Wilt (Pantoea stewartii)
- Common Rust (Puccinia sorghi)

Uses for maize

The primary use for corn (seed) in United States and Canada, is as a feed for livestock, while some is for the production of corn sweeteners like corn syrup, and the production of ethanol. Ethanol, a type of alcohol, is mostly used as an additive in gasoline to increase the octane rating. It is also used for making Bourbon whiskey. Bourbon whiskey Human consumption of corn and corn meal constitutes a staple food in many regions of the world. It is the main ingredient for tortilla and many other dishes of Mexican food. Maize can also be prepared as hominy, in which the kernels are bleached with lye; or grits, which are simply coarsely ground corn. These are commonly eaten in U.S. Southern States, foods handed down from Native Americans. Another common food made from maize is corn flakes. The flour of maize (cornflour or masa) is used to make cornbread and Mexican tortillas. Teosinte is used as fodder, and can also be popped as popcorn. As a food, maize (Zea mays ssp. mays) is used in various forms, with several major Cultivar Groups. The most important Cultivar Groups are:
- Flour corn - Zea mays L. subsp. mays Amylacea Group
- Popcorn - Zea mays L. subsp. mays Everta Group
- Dent corn - Zea mays L. subsp. mays Indentata Group
- Flint corn - Zea mays L. subsp. mays Indurata Group
- Sweetcorn - Zea mays L. subsp. mays Saccharata Group
- Pod corn - Zea mays L. var. tunicata Larrañaga ex A. St. Hil Many scientists speculate that fuel ethanol will mostly be produced from switchgrass and other biomass sources in the future. Corn cobs are also used as a biomass fuel source. Maize is relatively cheap and home heating furnaces have been developed which uses maize kernels as a fuel. They feature a large hopper which feeds the uniformly sized corn kernels (or wood pellets or cherry pits) into the fire. Some forms of the plant are occasionally grown for ornamental use in the garden. For this purpose, variegated and coloured leaf forms, as well as those with colourful cobs are used. Corncobs can be hollowed out and treated to make inexpensive smoking pipes, first manufactured in the United States in 1869. In 1983, Barbara McClintock received the Nobel Prize in Medicine for discovery of transposons while studying maize. Maize is still an imporant model organism for genetics and developmental biology today. In 2005, research by the USDA Forest Service indicated that the rise in maize cultivation 500 to 1,000 years ago in the southeastern United States contributed to the decline of freshwater mussels, which are very sensitive to environmental changes. [http://www.srs.fs.usda.gov/about/newsrelease/nr_2005-06-06-mussels.htm] An unusual use for maize prior to harvest is for a maze. In the U.S., these are called "corn mazes" and are popular in many farming communities. The first modern corn maze was designed by Adrian Fisher, who is in the Guiness Book of World Records for several of his maze designs. Mr. Fisher currently operates a company [http://www.mazemaker.com/ Adrian Fisher Mazes, Ltd.], specializing in mazes, including maize mazes.

References

- Ferro, D.N. and Weber, D.C. [http://www.eap.mcgill.ca/CPMP_1.htm Managing Sweet Corn Pests in Massachusetts]
- [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=42268 ITIS 42268] as of 2002-09-22
- [http://www.plantnames.unimelb.edu.au/Sorting/Zea.html Sorting Zea names]

External links

- [http://www.ncga.com/WorldOfCorn/main/index.htm NCGA Corn Industry Statistics]
- [http://caliban.mpiz-koeln.mpg.de/~stueber/thome/band1/tafel_088.html Image of Zea mays from Flora von Deutschland Österreich und der Schweiz]
- [http://www.pfaf.org/database/plants.php?Zea+mays&CAN=WIKPEDIA Zea mays at Plants For A Future]
- [http://www.iowacorn.org/cornuse/cornuse_3.html Usage of Iowa and U.S. Corn Crop]
- [http://www.kallipolis.com/diet/food.php?id=11168&w=3 Corn nutrition information]
- [http://maize.agron.iastate.edu/corngrows.html How a Corn Plant Develops]
- [http://www.maizegdb.org/ Maize Genetics/Genomics Database project]
- [http://www.cimmyt.org/ International Maize and Wheat Improvement Center]
- [http://www.howtocookcornonthecob.com How to cook corn on the cob]
- [http://www.milpa.nl Maize of Guatemala]

Food | List of fruits | List of vegetables Category:Vegetables Category:Cereals Category:Grains Category:Grasses Category:Fruits and vegetables of Mexico ms:Jagung ja:トウモロコシ zh-min-nan:Hoan-be̍h

Amyloplast

Amyloplasts (are a form of leucoplasts) are non-pigmented organelles found in plant cells responsible for the storage of starch through the polymerisation of glucose. Large numbers of amyloplasts can be found in underground storage tissues of some plants, such as potato. Amyloplasts are derived from plastids, which are a specialized class of cellular organs. The plastids carry their own genome and are believed to be descendants of cyanobacteria (blue-green algae) which formed a symbiotic relationship with the eucaryotic cell. Amyloplasts also hold statolyths, which are starch particles, and are responsible for the plant sensing gravity. In the root cap (a tissue at the tip of the root) some specialized amyloplasts are tought to be involved in the perception of gravity by the plant (gravitropism). This specialised amyloplasts can sediment according to the gravity vector and are called statoliths. Category:Organelles Category:Cell biology Category:Plant Physiology

Water

:This article focuses on water as it is experienced in everyday life. See water (molecule) for information on the chemical and physical properties of pure water (H₂O, hydrogen oxide). Water (from the Old English word wæter; c.f German "Wasser", from PIE
- wod-or, "water") is a tasteless, odorless, and nearly colorless (it has a slight hint of blue) substance in its pure form that is essential to all known forms of life and is known also as the most universal solvent. Water is an abundant substance on Earth. It exists in many places and forms. It appears mostly in the oceans and polar ice caps, but also as clouds, rain water, rivers, freshwater aquifers, and sea ice. On the planet, water is continuously moving through the cycle involving evaporation, precipitation, and runoff to the sea. Water fit for human consumption is called potable water. This natural resource is becoming more scarce in certain places as human population in those places increases, and its availability is a major social and economic concern.

Molecular properties

Forms of water

potable water] Water takes many different shapes on earth: water vapor and clouds in the sky, waves and icebergs in the sea, glaciers in the mountain, aquifers in the ground, to name but a few. Through evaporation, precipitation, and runoff, water is continuously flowing from one form to another, in what is called the water cycle. Because of the importance of precipitation to agriculture, and to mankind in general, different names are given to its various forms: while rain is common in most countries, other phenomena are quite surprising when seen for the first time. Hail, snow, fog or dew are examples. When appropriately lit, water drops in the air can refract sunlight to produce rainbows. Similarly, water runoffs have played major roles in human history as rivers and irrigation brought the water needed for agriculture. Rivers and seas offered opportunity for travel and commerce. Through erosion, runoffs played a major part in shaping the environment providing river valleys and deltas which provide rich soil and level ground for the establishment of population centers. Water also infiltrates the ground and goes into aquifers. This groundwater later flows back to the surface in springs, or more spectacularly in hot springs and geysers. Groundwater is also extracted artificially in wells. Because water can contain many different substances, it can taste or smell very differently. In fact, humans and other animals have developed their senses to be able to evaluate the drinkability of water: animals generally dislike the taste of salty sea water and the putrid swamps and favor the purer water of a mountain spring or aquifer.

Water in biology

From a biological standpoint, water has many distinct properties that are critical for the proliferation of life that set it apart from other substances. Water carries out this role by allowing organic compounds to react in ways that ultimately allows replication. It is a good solvent and has a high surface tension, and thus allows organic compounds and living things to be transported in it. Fresh water has its greatest density at 4°C, then becoming less dense as it freezes or heats up from this point. As a stable, polar molecule prevalent in the atmosphere, it plays an important atmospheric role as an absorber of infrared radiation, crucial in the atmospheric greenhouse effec