Chiral and achiral point groups, reflection groups.

Point groups can be classified into "chiral" (or purely rotational) groups and "achiral" groups. The chiral groups are subgroups of the special orthogonal group SO("d"): they contain only orientation-preserving orthogonal transformations, i.e., those of determinant +1. The achiral groups contain also transformations of determinant −1. In an achiral group, the orientation-preserving transformations form a (chiral) subgroup of index 2.  Finite Coxeter groups or "reflection groups" are those point groups that are generated purely by a set of reflectional mirrors passing through the same point. A rank "n" Coxeter group has "n" mirrors and is represented by a Coxeter-Dynkin diagram. Coxeter notation offers a bracketed notation equivalent to the Coxeter diagram, with markup symbols for rotational and other subsymmetry point groups. Reflection groups are necessarily achiral (except for the trivial group containing only the identity element).

List of point groups.

One dimension.

There are only two one-dimensional point groups, the identity group and the reflection group.

Two dimensions.

Point groups in two dimensions, sometimes called rosette groups.  They come in two infinite families: Applying the crystallographic restriction theorem restricts "n" to values 1, 2, 3, 4, and 6 for both families, yielding 10 groups.  The subset of pure reflectional point groups, defined by 1 or 2 mirrors, can also be given by their Coxeter group and related polygons. These include 5 crystallographic groups. The symmetry of the reflectional groups can be doubled by an isomorphism, mapping both mirrors onto each other by a bisecting mirror, doubling the symmetry order.

Three dimensions.

Point groups in three dimensions, sometimes called molecular point groups after their wide use in studying the symmetries of small molecules.  They come in 7 infinite families of axial or prismatic groups, and 7 additional polyhedral or Platonic groups. In Schönflies notation,* Applying the crystallographic restriction theorem to these groups yields 32 Crystallographic point groups.

Reflection groups.

The reflection point groups, defined by 1 to 3 mirror planes, can also be given by their Coxeter group and related polyhedra. The [3,3] group can be doubled, written as, mapping the first and last mirrors onto each other, doubling the symmetry to 48, and isomorphic to the [4,3] group.

Four dimensions.

The four-dimensional point groups (chiral as well as achiral) are listed in Conway and Smith, Section 4, Tables 4.1-4.3. The following list gives the four-dimensional reflection groups (excluding those that leave a subspace fixed and that are therefore lower-dimensional reflection groups). Each group is specified as a Coxeter group, and like the polyhedral groups of 3D, it can be named by its related convex regular 4-polytope. Related pure rotational groups exist for each with half the order, and can be represented by the bracket Coxeter notation with a '+' exponent, for example [3,3,3] has three 3-fold gyration points and symmetry order 60. Front-back symmetric groups like [3,3,3] and [3,4,3] can be doubled, shown as double brackets in Coxeter's notation, for example with its order doubled to 240.

Five dimensions.

The following table gives the five-dimensional reflection groups (excluding those that are lower-dimensional reflection groups), by listing them as Coxeter groups. Related chiral groups exist for each with half the order, and can be represented by the bracket Coxeter notation with a '+' exponent, for example [3,3,3,3] has four 3-fold gyration points and symmetry order 360.

Six dimensions.

The following table gives the six-dimensional reflection groups (excluding those that are lower-dimensional reflection groups), by listing them as Coxeter groups. Related pure rotational groups exist for each with half the order, and can be represented by the bracket Coxeter notation with a '+' exponent, for example [3,3,3,3,3] has five 3-fold gyration points and symmetry order 2520.

Seven dimensions.

The following table gives the seven-dimensional reflection groups (excluding those that are lower-dimensional reflection groups), by listing them as Coxeter groups. Related chiral groups exist for each with half the order, defined by an even number of reflections, and can be represented by the bracket Coxeter notation with a '+' exponent, for example [3,3,3,3,3,3] has six 3-fold gyration points and symmetry order 20160.

Eight dimensions.

The following table gives the eight-dimensional reflection groups (excluding those that are lower-dimensional reflection groups), by listing them as Coxeter groups. Related chiral groups exist for each with half the order, defined by an even number of reflections, and can be represented by the bracket Coxeter notation with a '+' exponent, for example [3,3,3,3,3,3,3] has seven 3-fold gyration points and symmetry order 181440.

In geometry, a point group is a group of geometric symmetries (isometries) that keep at least one point fixed. Point groups can exist in a Euclidean space with any dimension, and every point group in dimension "d" is a subgroup of the orthogonal group O("d"). Point groups can be realized as sets of orthogonal matrices "M" that transform point "x" into point "y":

Eine Punktgruppe ist ein spezieller Typus einer Symmetriegruppe der euklidischen Geometrie, der die Symmetrie eines endlichen Körpers beschreibt. Alle Punktgruppen zeichnen sich dadurch aus, dass es einen Punkt gibt, der durch alle Symmetrieoperationen der Punktgruppe wieder auf sich selbst abgebildet wird. Aufgrund des Neumannschen Prinzips bestimmt die Punktgruppe die makroskopischen Eigenschaften des Körpers. Weitere Aussagen lassen sich mit Hilfe der Darstellungstheorie gewinnen.


History.

The name "IJssel" (older "Isla", "Isala", from *"Īsalō"), is thought to derive from a Proto-Indo-European root "*eis-" "to move quickly" (Old Norse "eisa" "to race forward", Latin "ira" "anger"). Before the early Middle Ages, the Zuiderzee had not yet formed, and in its place there was an inland lake known as "Vlies" (Lat. "Flevo"), and the IJssel flowed through the surrounding lakelands. However, since the formation of the Zuiderzee and obstruction from the Afsluitdijk, the IJssel no longer flows into its estuary, the Vlie, now restricted in meaning and referring only to the strait separating the islands of Vlieland (itself named after the Vlie strait) and Terschelling. It is hypothesised that the now-poldered tidal inlets near Medemblik and the IJ (near Amsterdam) once were branches of river IJssel.  The river was a natural line of defence and in April 1945 had to be stormed by assault troops of the Allied armies liberating the Netherlands from the occupying forces of Nazi Germany. Canadian histories refer to the river in English as "Ijssel".

The IJssel as the lower part of the Oude IJssel.

The IJssel was the lower part of the small river Oude IJssel (lit. "Old IJssel", German "Issel"), that rises in Germany and is now a 70 km long tributary of the IJssel. The connection between Rhine and IJssel was probably artificial, allegedly dug by men under the Roman general Nero Claudius Drusus 12 BCE as a defence against Germanic tribes and to let Roman ships carry troops along it. The current Oude IJssel is now the second-largest contributor to the flow of the river, after the river Rhine.  The source of the Oude IJssel is near Borken in North Rhine-Westphalia, Germany. First it flows south-west until it nearly reaches the Rhine near Wesel; then it turns north-west. After passing through Isselburg it crosses the border with the Netherlands. The river, called Oude IJssel from here, then flows through Doetinchem and joins the IJssel at Doesburg.

Characteristics.

The average discharge of the IJssel can change significantly. The average discharge has been stated as 300 cubic meters per second. This can be as low as 140 and as high as 1800, depending on the Nederrijn locks west of Arnhem, which regulate the amount of water taken in by the Nederrijn and IJssel branches.  As a lowlands river, the IJssel has a lot of bends and naturally occurring dead branches (locally called "hank"); some bends have been cut off by man (most notably near Rheden and Doesburg), reducing the river's length from 146 km to 125 km, but not nearly as radically as with river Meuse. The naturally occurring phenomenon of sedimental island-forming in the outside of bends has been regulated to the point of non-occurrence since the late nineteenth century.

The IJssel as a Rhine distributary.

From the moment the connection between the Rhine and IJssel was dug, the Rhine became the largest contributor to the flow of the IJssel, although only a relatively small amount of the total Rhine flow makes its way into the IJssel system. Various tributaries can sometimes add a considerable volume of water to the total flow of the IJssel, such as the Berkel and Schipbeek streams. The IJssel river is the only branch of the Rhine delta that takes up tributary rivers rather than giving rise to distributaries.  Only in the last few miles of the river's run, near the city of Kampen, distributaries form, resulting in the relatively minor IJssel delta. Some of the branches have been dammed up to lower the risk of flooding; others have silted up. Several of the delta branches are, however, still connected without interruption. Most of the damming-up was done prior to 1932, when the Zuiderzee was turned into the freshwater IJsselmeer lake. The area had been prone to flooding in times of northwestern gales, pushing back the saline Zuiderzee water into the IJssel delta and preventing the water flowing from the mouths of the IJssel branches from discharging into the Zuiderzee.  The modern-day names of the delta branches are, west to east, Keteldiep, Kattendiep, Noorddiep, Ganzendiep and Goot. Of these, the Keteldiep and Kattendiep channels are the main navigational arteries; the Noorddiep has been closed off at both sides. Another branch, De Garste, had already completely silted up by the middle of the nineteenth century. Until the beginning of the twentieth century, the Ganzendiep branch up to the Goot fork was known as IJssel proper. due to it being the historical main channel, with the present-day main channel being called Regtediep or Rechterdiep until well into the twentieth century  The IJssel, although now technically "merely" a Rhine branch, has retained most of the character of a distinct river in its own right, in no small part due to the fact that it has its own tributaries and, in river Oude IJssel, even a former headstream.

Tributaries and connecting canals.

The following canals and tributary streams connect to the IJssel, in downstream order:

River crossings.

Road bridges.

Road bridges across river IJssel (with nearest places on the left and right bank):

Railroad bridges.

Railroad bridges (with nearest train station on the left and right bank):

Cable ferries.

Only those ferries capable of carrying motorised vehicles are included.

The river IJssel (,, ; ), sometimes called Gelderse IJssel (; "Gueldern IJssel") to avoid confusion with the Hollandse IJssel, is the branch of the Rhine in the Dutch provinces of Gelderland and Overijssel. The Romans knew the river as Isala. The IJssel flows from Westervoort, east of the city of Arnhem, until it discharges into the IJsselmeer ("Lake IJssel", known prior to the 1932 completion of the Afsluitdijk as the Zuiderzee, a North Sea inlet). The River IJssel is one of the three major distributary branches (along with the rivers Nederrijn and Waal) into which the Rhine divides shortly after crossing the German-Dutch border.

Die IJssel ([], deutsch "Ijssel" oder "Issel" geschrieben und "Eissel" ausgesprochen) ist der nördlichste Mündungsarm des Rheins in die Nordsee. Sie zweigt bei Westervoort in der Nähe von Arnheim vom Nederrijn ab und mündet bei Kampen in das IJsselmeer, den größten See der Niederlande (vormals die Zuiderzee, eine Bucht der Nordsee).


History and traditional usage.

Malted grains have probably been used as an ingredient of beer since ancient times, for example in Egypt (Ancient Egyptian cuisine), Sumer, and China.  In Persian countries, a sweet paste made entirely from germinated wheat is called Samanū () in Iran, Samanak (), (); () or Sümölök (), which is prepared for Nowruz (Persian new year celebration) in a large pot (like a kazan). A plate or bowl of Samanu is a traditional component of the Haft sin table symbolising affluence. Traditionally, women have a special party to prepare it during the night, and cook it from late in the evening till the daylight, singing related songs. In Tajikistan and Afghanistan they sing: "Samanak dar Jūsh u mā Kafcha zanēm - Dīgarān dar Khwāb u mā Dafcha zanēm". (Meaning: ""Samanak is boiling and we are stirring it, others are asleep and we are playing daf""). In modern times, making samanu can be a family gathering. It originally comes from the Great Persian Empire.  Mämmi, or Easter Porridge, is a traditional Finnish Lenten food. Cooked from rye malt and flour, mämmi has a great resemblance (in recipe, color, and taste) to Samanū. Today, this product is available in shops from February until Easter. A (non-representative) survey in 2013 showed that almost no one cooks mämmi at home in modern-day Finland.

Malting.

Malting is the process of converting barley or other cereal grains into malt for use in brewing, distilling, or in foods and takes place in a maltings, sometimes called a malthouse, or a malting floor. The cereal is spread out on the malting floor in a layer of depth.  A "maltings" is typically a long, single-story building with a floor that slopes slightly from one end of the building to the other. Floor maltings began to be phased out in the 1940s in favor of "pneumatic plants" where large industrial fans are used to blow air through the germinating grain beds and to pass hot air through the malt being kilned. Like floor maltings, these pneumatic plants use batch processes, but of considerably greater size, typically 100 ton batches compared with 20 ton batches floor maltings. , the largest malting operation in the world was Malteurop, which operates in 14 countries.

Production.

Barley is the most commonly malted grain, in part because of its high content of enzymes, though wheat, rye, oats, rice, and corn are also used. Also very important is the retention of the grain's husk, even after threshing, unlike the bare seeds of threshed wheat or rye. This protects the growing acrospire (developing plant embryo) from damage during malting, which can easily lead to mold growth; it also allows the mash of converted grain to create a filter bed during lautering (see brewing).

Malts.

Diastatic and nondiastatic.

As all grains sprout, natural enzymes within the grain break down the starch the grain is composed of into simpler sugars which taste sweet and are easier for yeast to use as growth food. Malt with active enzymes is called "diastatic malt". Malt with inactive enzymes is called "nondiastatic malt". The enzymes are deactivated by heating the malt.

Base and specialty.

Malt is often divided into two categories by brewers: base malts and specialty malts.  Base malts have enough diastatic power to convert their own starch and usually that of some amount of starch from unmalted grain, called adjuncts.  Specialty malts have little diastatic power, but provide flavor, color, or "body" (viscosity) to the finished beer. Specialty caramel or crystal malts have been subjected to heat treatment to convert their starches to sugars nonenzymatically. Within these categories is a variety of types distinguished largely by the kilning temperature (see mash ingredients).

Two-row and six-row.

In addition, malts are distinguished by the two major cultivar types of barley used for malting, two-row and six-row. The most common varieties of barley used for malting in the United States from 2009 to 2013 are two-row AC Metcalfe and Conrad and six-row Tradition and Lacey cultivars.

Malt extract.

Malt extract, also known as extract of malt, is a sweet, treacly substance used as a dietary supplement. It was popular in the first half of the 20th century as a nutritional enhancer for the children of the British urban working class, whose diet was often deficient in vitamins and minerals. Children were given cod liver oil for the same reason, but it proved so unpalatable that it was combined with extract of malt to produce "Malt and Cod-Liver Oil."  The 1907 "British Pharmaceutical Codex"'s instructions for making nutritional extract of malt do not include a mashout at the end of extraction, and include the use of lower mash temperatures than is typical with modern beer-brewing practices. The "Codex" indicates that diastatic activity is to be preserved by the use of temperatures not exceeding.

Malt extract production.

Malt extract is frequently used in the brewing of beer. Its production begins by germinating barley grain in a process known as "malting", immersing barley in water to encourage the grain to sprout, then drying the barley to halt the progress when the sprouting begins. The drying step stops the sprouting, but the enzymes remain active due to the low temperatures used in base malt production. In one before-and-after comparison, malting decreased barley's extractable starch content by about 7% on a dry matter basis and turned that portion into various other carbohydrates. In the next step, brewers use a process called mashing to extract the sugars. Brewers warm cracked malt in temperature-modulated water, activating the enzymes, which cleave more of the malt's remaining starch into various sugars, the largest percentage of which is maltose. Modern beer mashing practices typically include high enough temperatures at mash-out to deactivate remaining enzymes, thus it is no longer diastatic. The liquid produced from this, wort, is then concentrated by using heat or a vacuum procedure to evaporate water from the mixture. The concentrated wort is called malt extract.  Liquid malt extract (LME) is a thick syrup and is used for a variety of purposes, such as baking and brewing. It is also sold in jars as a consumer product.  The LME may be further dried to produce dry malt extract (DME), which is crystalline in form similar to common sugar.  Brewers have the option of using a liquid (LME) or dry (DME) form of it. Each has its pros and cons, so the choice is dependent solely on the individual brewer's preferences. Some brewers choose to work only with LME because they feel it works best for the result they wish to achieve. Also, it requires one fewer processing step, so it is appealing to those favoring the purest form of product available. However, it is very sticky and, therefore, messier to work with and has a shorter shelf life. Some feel the results are just as good with DME.  A new encapsulating technology permits the production of malt granules. Malt granules are the dried liquid extract from malt used in the brewing or distilling process.

Research.

Scientists aim to discover what happens inside barley grains as they become malted to help plant breeders produce better malting barley for food and beverage products. The United States Agricultural Research Service scientists are interested in specialized enzymes called serine-class proteases that digest beta-amylases, which convert carbohydrates into "simple sugars" during the sprouting process. The enzyme also breaks down stored proteins into their amino acid derivatives. The balance of proteins and carbohydrates broken down by the enzyme affect the malt's flavor.

Malt is germinated cereal grain that has been dried in a process known as "malting". The grain is made to germinate by soaking in water and is then halted from germinating further by drying with hot air.

Malz (Mälzung) ist kurz gekeimtes und wieder getrocknetes Getreide (Gerste, Weizen, Roggen, Dinkel, Mais o. a.). Dieser Vorgang bildet und aktiviert Enzyme im Getreide, die z. B. für das Bierbrauen notwendig sind. Ein Teil der Stärke wird dabei in kleinere Moleküle (Mehrfachzucker, besonders Disaccharide wie Maltose) zerlegt.


Description.

In the wild, "Picea pungens" grows to about, but when planted in parks and gardens it seldom exceeds tall by wide. It is a columnar or conical evergreen conifer with densely growing horizontal branches. It has scaly grey bark on the trunk with yellowish-brown branches.  Waxy gray-green leaves, up to long, are arranged radially on the shoots which curve upwards. The pale brown cones are up to long.  The specific epithet "pungens" means "sharply pointed", referring to the leaves.  The blue spruce is the State Tree of Colorado.

Cultivation.

"Picea pungens" and its many cultivars are often grown as ornamental trees in gardens and parks. It is also grown for the Christmas tree industry.

Pests and diseases.

The blue spruce is attacked by two species of "Adelges", an aphid-like insect that causes galls to form. Nymphs of the pineapple gall adelgid form galls at the base of twigs which resemble miniature pineapples and those of the Cooley's spruce gall adelgid cause cone-shaped galls at the tips of branches. The larva of the spruce budworm eat the buds and growing shoots while the spruce needle miner hollows out the needles and makes them coalesce in a webbed mass. An elongated white scale insect, the pine needle scale feeds on the needles causing fluffy white patches on the twigs and aphids also suck sap from the needles and may cause them to fall and possibly dieback. Mites can also infest the blue spruce, especially in a dry summer, causing yellowing of the oldest needles. Another insect pest is the spruce beetle ("Dendroctonus rufipennis") which bores under the bark. It often first attacks trees which have blown over by the wind and when the larvae mature two years afterwards, a major outbreak occurs and vast numbers of beetles attack nearby standing trees.  The blue spruce is susceptible to several needle casting diseases which cause the needles to turn yellow, mottled or brown before they fall off. Various rust diseases also affect the tree causing yellowing of the needles as well as needle fall. Canker caused by "Cytospora" attacks one of the lower branches first and progressively makes its way higher up the tree. The first symptom is the needles turning reddish-brown and falling off. Meanwhile, patches of white resin appear on the bark and the branch eventually dies.

Rooting Habits.

Blue spruce seedlings are shallow roots that penetrate only 6.4 cm (2.5 inches) of soil during the first year. Although freezing can’t damage much in blue spruce, frost will cause seedling loss. Shadows in late spring and early autumn minimize this frost heaving loss. Despite the shallow roots, blue spruce is able to resist strong winds. Five years before transplanting, the total root surface area of 2-meter-high trees was doubled by pruning the roots of blue spruce. It also increases the root concentration in drip irrigation pipeline from 40% to 60%, which is an advantage in landscape greening.

Cultivars.

Common cultivars (those marked have gained the Royal Horticultural Society's Award of Garden Merit):

Uses.

The Navajo and Keres Native Americans used this tree as a traditional medicinal plant and a ceremonial item, and twigs are given as gifts to bring good fortune. In traditional medicine, an infusion of the needles is used to treat colds and settle the stomach. This liquid is also used externally for rheumatic pains. Early people used their wood for building.

Distributed soil types and Topography.

Blue spruce generally exists on gentle uplands and sub irrigated slopes, in well-watered tributary drainage, extending down intermittent streams, and on lower northerly slopes.  Blue spruce always grow naturally in the soils which are in the order Mollisols, and the soil will also be in the orders histosols and inceptisols in a lesser extent.  Blue spruce is considered as a pioneer tree species in moist soil in Utah.

Climate.

Blue spruce usually grows in cool and humid climatic zones where the annual precipitation mainly occurs in the summer.  Blue spruce is most common in Colorado and the Southwest. The annual average temperature ranges from 3.9 to 6.1 degrees C (39 to 43 degrees F). And ranges from - 3.9 to - 2.8 degrees C (25 to 27 degrees F) in January. In July, the average temperature ranges from 13.9 to 15.0 degrees C (57 to 59 degrees F). The average minimum temperature in January ranges from - 11.1 to 8.9 degrees C (12 to 16 degrees F), and the average maximum temperature in July ranges from 21.1 to 22.2 C (70 to 72 degrees F). There is a frost-free period of about 55 to 60 days from June to August.  Annual mean precipitation generally vary from 460 to 610 mm (18 to 24 in). Winter is the season with the poorest rainfall, the precipitation is usually less than 20 percent of the annual moisture falling from December to March. And fifth percent of the annual precipitation occurs during the growing season of the plants.  Blue spruce is generally considered to grow best with abundant moisture. Nevertheless, this species can withstand drought better than any other spruce. It can withstand extremely low temperatures (-40 degrees C) as well. Furthermore, this species is more resistant to high insolation and frost damage compared to other associated species.

The blue spruce, green spruce, white spruce, Colorado spruce, or Colorado blue spruce, with the Latin (scientific) name Picea pungens, is a species of spruce tree. It is native to North America, and is found in growing zones 1 through 7. Its natural range extends from northern New Mexico through Colorado and Utah to Wyoming and into Alberta and British Columbia, but it has been widely introduced elsewhere and is used as an ornamental tree in many places far beyond its native range. The blue spruce has blue-green coloured needles and is a coniferous tree.

Die Stech-Fichte ("Picea pungens", Syn.: "Picea parryana" ), umgangssprachlich auch Blau-Fichte genannt, ist eine immergrüne Pflanzenart aus der Gattung der Fichten ("Picea"). Die Stech-Fichte ist der Staatsbaum der US-amerikanischen Bundesstaaten Colorado und Utah.


Physical basis.

Electrophoresis is a process which enables the sorting of molecules based on size. Using an electric field, molecules (such as DNA) can be made to move through a gel made of agarose or polyacrylamide. The electric field consists of a negative charge at one end which pushes the molecules through the gel, and a positive charge at the other end that pulls the molecules through the gel. The molecules being sorted are dispensed into a well in the gel material. The gel is placed in an electrophoresis chamber, which is then connected to a power source. When the electric current is applied, the larger molecules move more slowly through the gel while the smaller molecules move faster. The different sized molecules form distinct bands on the gel.  The term "gel" in this instance refers to the matrix used to contain, then separate the target molecules. In most cases, the gel is a crosslinked polymer whose composition and porosity are chosen based on the specific weight and composition of the target to be analyzed. When separating proteins or small nucleic acids (DNA, RNA, or oligonucleotides) the gel is usually composed of different concentrations of acrylamide and a cross-linker, producing different sized mesh networks of polyacrylamide. When separating larger nucleic acids (greater than a few hundred bases), the preferred matrix is purified agarose. In both cases, the gel forms a solid, yet porous matrix. Acrylamide, in contrast to polyacrylamide, is a neurotoxin and must be handled using appropriate safety precautions to avoid poisoning. Agarose is composed of long unbranched chains of uncharged carbohydrate without cross-links resulting in a gel with large pores allowing for the separation of macromolecules and macromolecular complexes.  Electrophoresis refers to the electromotive force (EMF) that is used to move the molecules through the gel matrix. By placing the molecules in wells in the gel and applying an electric field, the molecules will move through the matrix at different rates, determined largely by their mass when the charge-to-mass ratio (Z) of all species is uniform. However, when charges are not all uniform the electrical field generated by the electrophoresis procedure will cause the molecules to migrate differentially according to charge. Species that are net positively charged will migrate towards the cathode which is negatively charged (because this is an electrolytic rather than galvanic cell), whereas species that are net negatively charged will migrate towards the positively charged anode. Mass remains a factor in the speed with which these non-uniformly charged molecules migrate through the matrix toward their respective electrodes.  If several samples have been loaded into adjacent wells in the gel, they will run parallel in individual lanes. Depending on the number of different molecules, each lane shows the separation of the components from the original mixture as one or more distinct bands, one band per component. Incomplete separation of the components can lead to overlapping bands, or indistinguishable smears representing multiple unresolved components. Bands in different lanes that end up at the same distance from the top contain molecules that passed through the gel at the same speed, which usually means they are approximately the same size. There are molecular weight size markers available that contain a mixture of molecules of known sizes. If such a marker was run on one lane in the gel parallel to the unknown samples, the bands observed can be compared to those of the unknown to determine their size. The distance a band travels is approximately inversely proportional to the logarithm of the size of the molecule.  There are limits to electrophoretic techniques. Since passing a current through a gel causes heating, gels may melt during electrophoresis. Electrophoresis is performed in buffer solutions to reduce pH changes due to the electric field, which is important because the charge of DNA and RNA depends on pH, but running for too long can exhaust the buffering capacity of the solution. There are also limitations in determining the molecular weight by SDS-PAGE, especially when trying to find the MW of an unknown protein. Certain biological variables are difficult or impossible to minimize and can affect the electrophoretic migration. Such factors include protein structure, post-translational modifications, and amino acid composition. For example, tropomyosin is an acidic protein that migrates abnormally on SDS-PAGE gels. This is because the acidic residues are repelled by the negatively charged SDS, leading to an inaccurate mass-to-charge ratio and migration. Further, different preparations of genetic material may not migrate consistently with each other, for morphological or other reasons.

Types of gel.

The types of gel most typically used are agarose and polyacrylamide gels. Each type of gel is well-suited to different types and sizes of the analyte. Polyacrylamide gels are usually used for proteins and have very high resolving power for small fragments of DNA (5-500 bp). Agarose gels, on the other hand, have lower resolving power for DNA but have a greater range of separation, and are therefore used for DNA fragments of usually 50-20,000 bp in size, but the resolution of over 6 Mb is possible with pulsed field gel electrophoresis (PFGE). Polyacrylamide gels are run in a vertical configuration while agarose gels are typically run horizontally in a submarine mode. They also differ in their casting methodology, as agarose sets thermally, while polyacrylamide forms in a chemical polymerization reaction.

Agarose.

Agarose gels are made from the natural polysaccharide polymers extracted from seaweed. Agarose gels are easily cast and handled compared to other matrices because the gel setting is a physical rather than chemical change. Samples are also easily recovered. After the experiment is finished, the resulting gel can be stored in a plastic bag in a refrigerator.  Agarose gels do not have a uniform pore size, but are optimal for electrophoresis of proteins that are larger than 200 kDa. Agarose gel electrophoresis can also be used for the separation of DNA fragments ranging from 50 base pair to several megabases (millions of bases), the largest of which require specialized apparatus. The distance between DNA bands of different lengths is influenced by the percent agarose in the gel, with higher percentages requiring longer run times, sometimes days. Instead high percentage agarose gels should be run with a pulsed field electrophoresis (PFE), or field inversion electrophoresis.  "Most agarose gels are made with between 0.7% (good separation or resolution of large 5–10kb DNA fragments) and 2% (good resolution for small 0.2–1kb fragments) agarose dissolved in electrophoresis buffer. Up to 3% can be used for separating very tiny fragments but a vertical polyacrylamide gel is more appropriate in this case. Low percentage gels are very weak and may break when you try to lift them. High percentage gels are often brittle and do not set evenly. 1% gels are common for many applications."

Polyacrylamide.

Polyacrylamide gel electrophoresis (PAGE) is used for separating proteins ranging in size from 5 to 2,000 kDa due to the uniform pore size provided by the polyacrylamide gel. Pore size is controlled by modulating the concentrations of acrylamide and bis-acrylamide powder used in creating a gel. Care must be used when creating this type of gel, as acrylamide is a potent neurotoxin in its liquid and powdered forms.  Traditional DNA sequencing techniques such as Maxam-Gilbert or Sanger methods used polyacrylamide gels to separate DNA fragments differing by a single base-pair in length so the sequence could be read. Most modern DNA separation methods now use agarose gels, except for particularly small DNA fragments. It is currently most often used in the field of immunology and protein analysis, often used to separate different proteins or isoforms of the same protein into separate bands. These can be transferred onto a nitrocellulose or PVDF membrane to be probed with antibodies and corresponding markers, such as in a western blot.  Typically resolving gels are made in 6%, 8%, 10%, 12% or 15%. Stacking gel (5%) is poured on top of the resolving gel and a gel comb (which forms the wells and defines the lanes where proteins, sample buffer, and ladders will be placed) is inserted. The percentage chosen depends on the size of the protein that one wishes to identify or probe in the sample. The smaller the known weight, the higher the percentage that should be used. Changes on the buffer system of the gel can help to further resolve proteins of very small sizes.

Starch.

Partially hydrolysed potato starch makes for another non-toxic medium for protein electrophoresis. The gels are slightly more opaque than acrylamide or agarose. Non-denatured proteins can be separated according to charge and size. They are visualised using Napthal Black or Amido Black staining. Typical starch gel concentrations are 5% to 10%.

Gel conditions.

Denaturing.

Denaturing gels are run under conditions that disrupt the natural structure of the analyte, causing it to unfold into a linear chain. Thus, the mobility of each macromolecule depends only on its linear length and its mass-to-charge ratio. Thus, the secondary, tertiary, and quaternary levels of biomolecular structure are disrupted, leaving only the primary structure to be analyzed.  Nucleic acids are often denatured by including urea in the buffer, while proteins are denatured using sodium dodecyl sulfate, usually as part of the SDS-PAGE process. For full denaturation of proteins, it is also necessary to reduce the covalent disulfide bonds that stabilize their tertiary and quaternary structure, a method called reducing PAGE. Reducing conditions are usually maintained by the addition of beta-mercaptoethanol or dithiothreitol. For a general analysis of protein samples, reducing PAGE is the most common form of protein electrophoresis.  Denaturing conditions are necessary for proper estimation of molecular weight of RNA. RNA is able to form more intramolecular interactions than DNA which may result in change of its electrophoretic mobility. Urea, DMSO and glyoxal are the most often used denaturing agents to disrupt RNA structure. Originally, highly toxic methylmercury hydroxide was often used in denaturing RNA electrophoresis, but it may be method of choice for some samples.  Denaturing gel electrophoresis is used in the DNA and RNA banding pattern-based methods temperature gradient gel electrophoresis (TGGE) and denaturing gradient gel electrophoresis (DGGE).

Native.

Native gels are run in non-denaturing conditions so that the analyte's natural structure is maintained. This allows the physical size of the folded or assembled complex to affect the mobility, allowing for analysis of all four levels of the biomolecular structure. For biological samples, detergents are used only to the extent that they are necessary to lyse lipid membranes in the cell. Complexes remain—for the most part—associated and folded as they would be in the cell. One downside, however, is that complexes may not separate cleanly or predictably, as it is difficult to predict how the molecule's shape and size will affect its mobility. Addressing and solving this problem is a major aim of quantitative native PAGE.  Unlike denaturing methods, native gel electrophoresis does not use a charged denaturing agent. The molecules being separated (usually proteins or nucleic acids) therefore differ not only in molecular mass and intrinsic charge, but also the cross-sectional area, and thus experience different electrophoretic forces dependent on the shape of the overall structure. For proteins, since they remain in the native state they may be visualized not only by general protein staining reagents but also by specific enzyme-linked staining.  A specific experiment example of an application of native gel electrophoresis is to check for enzymatic activity to verify the presence of the enzyme in the sample during protein purification. For example, for the protein alkaline phosphatase, the staining solution is a mixture of 4-chloro-2-2methylbenzenediazonium salt with 3-phospho-2-naphthoic acid-2’-4’-dimethyl aniline in Tris buffer. This stain is commercially sold as a kit for staining gels. If the protein is present, the mechanism of the reaction takes place in the following order: it starts with the de-phosphorylation of 3-phospho-2-naphthoic acid-2’-4’-dimethyl aniline by alkaline phosphatase (water is needed for the reaction). The phosphate group is released and replaced by an alcohol group from water. The electrophile 4- chloro-2-2 methylbenzenediazonium (Fast Red TR Diazonium salt) displaces the alcohol group forming the final product Red Azo dye. As its name implies, this is the final visible-red product of the reaction. In undergraduate academic experimentation of protein purification, the gel is usually run next to commercial purified samples to visualize the results and conclude whether or not purification was successful.  Native gel electrophoresis is typically used in proteomics and metallomics. However, native PAGE is also used to scan genes (DNA) for unknown mutations as in Single-strand conformation polymorphism.

Buffers.

Buffers in gel electrophoresis are used to provide ions that carry a current and to maintain the pH at a relatively constant value. These buffers have plenty of ions in them, which is necessary for the passage of electricity through them. Something like distilled water or benzene contains few ions, which is not ideal for the use in electrophoresis. There are a number of buffers used for electrophoresis. The most common being, for nucleic acids Tris/Acetate/EDTA (TAE), Tris/Borate/EDTA (TBE). Many other buffers have been proposed, e.g. lithium borate, which is rarely used, based on Pubmed citations (LB), isoelectric histidine, pK matched goods buffers, etc.; in most cases the purported rationale is lower current (less heat) matched ion mobilities, which leads to longer buffer life. Borate is problematic; Borate can polymerize, or interact with cis diols such as those found in RNA. TAE has the lowest buffering capacity but provides the best resolution for larger DNA. This means a lower voltage and more time, but a better product. LB is relatively new and is ineffective in resolving fragments larger than 5 kbp; However, with its low conductivity, a much higher voltage could be used (up to 35 V/cm), which means a shorter analysis time for routine electrophoresis. As low as one base pair size difference could be resolved in 3% agarose gel with an extremely low conductivity medium (1 mM Lithium borate).  Most SDS-PAGE protein separations are performed using a "discontinuous" (or DISC) buffer system that significantly enhances the sharpness of the bands within the gel. During electrophoresis in a discontinuous gel system, an ion gradient is formed in the early stage of electrophoresis that causes all of the proteins to focus on a single sharp band in a process called isotachophoresis. Separation of the proteins by size is achieved in the lower, "resolving" region of the gel. The resolving gel typically has a much smaller pore size, which leads to a sieving effect that now determines the electrophoretic mobility of the proteins.

Visualization.

After the electrophoresis is complete, the molecules in the gel can be stained to make them visible. DNA may be visualized using ethidium bromide which, when intercalated into DNA, fluoresce under ultraviolet light, while protein may be visualised using silver stain or Coomassie Brilliant Blue dye. Other methods may also be used to visualize the separation of the mixture's components on the gel. If the molecules to be separated contain radioactivity, for example in a DNA sequencing gel, an autoradiogram can be recorded of the gel. Photographs can be taken of gels, often using a Gel Doc system.

Downstream processing.

After separation, an additional separation method may then be used, such as isoelectric focusing or SDS-PAGE. The gel will then be physically cut, and the protein complexes extracted from each portion separately. Each extract may then be analysed, such as by peptide mass fingerprinting or de novo peptide sequencing after in-gel digestion. This can provide a great deal of information about the identities of the proteins in a complex.

Applications.

Gel electrophoresis is used in forensics, molecular biology, genetics, microbiology and biochemistry. The results can be analyzed quantitatively by visualizing the gel with UV light and a gel imaging device. The image is recorded with a computer operated camera, and the intensity of the band or spot of interest is measured and compared against standard or markers loaded on the same gel. The measurement and analysis are mostly done with specialized software.  Depending on the type of analysis being performed, other techniques are often implemented in conjunction with the results of gel electrophoresis, providing a wide range of field-specific applications.

Nucleic acids.

In the case of nucleic acids, the direction of migration, from negative to positive electrodes, is due to the naturally occurring negative charge carried by their sugar-phosphate backbone.  Double-stranded DNA fragments naturally behave as long rods, so their migration through the gel is relative to their size or, for cyclic fragments, they're radius of gyration. Circular DNA such as plasmids, however, may show multiple bands, the speed of migration may depend on whether it is relaxed or supercoiled. Single-stranded DNA or RNA tends to fold up into molecules with complex shapes and migrate through the gel in a complicated manner based on their tertiary structure. Therefore, agents that disrupt the hydrogen bonds, such as sodium hydroxide or formamide, are used to denature the nucleic acids and cause them to behave as long rods again.  Gel electrophoresis of large DNA or RNA is usually done by agarose gel electrophoresis. See the "Chain termination method" page for an example of a polyacrylamide DNA sequencing gel. Characterization through ligand interaction of nucleic acids or fragments may be performed by mobility shift affinity electrophoresis.  Electrophoresis of RNA samples can be used to check for genomic DNA contamination and also for RNA degradation. RNA from eukaryotic organisms shows distinct bands of 28s and 18s rRNA, the 28s band being approximately twice as intense as the 18s band. Degraded RNA has less sharply defined bands, has a smeared appearance, and intensity ratio is less than 2:1.

Proteins.

Proteins, unlike nucleic acids, can have varying charges and complex shapes, therefore they may not migrate into the polyacrylamide gel at similar rates, or all when placing a negative to positive EMF on the sample. Proteins therefore, are usually denatured in the presence of a detergent such as sodium dodecyl sulfate (SDS) that coats the proteins with a negative charge. Generally, the amount of SDS bound is relative to the size of the protein (usually 1.4g SDS per gram of protein), so that the resulting denatured proteins have an overall negative charge, and all the proteins have a similar charge-to-mass ratio. Since denatured proteins act like long rods instead of having a complex tertiary shape, the rate at which the resulting SDS coated proteins migrate in the gel is relative only to its size and not its charge or shape.  Proteins are usually analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), by native gel electrophoresis, by preparative gel electrophoresis (QPNC-PAGE), or by 2-D electrophoresis.  Characterization through ligand interaction may be performed by electroblotting or by affinity electrophoresis in agarose or by capillary electrophoresis as for estimation of binding constants and determination of structural features like glycan content through lectin binding.

Nanoparticles.

A novel application for the gel electrophoresis is to separate or characterize metal or metal oxide nanoparticles (e.g. Au, Ag, ZnO, SiO2) regarding the size, shape, or surface chemistry of the nanoparticles. The scope is to obtain a more homogeneous sample (e.g. narrower particle size distribution), which than can be used in further products/processes (e.g. self-assembly processes). For the separation of nanoparticles within a gel, the particle size about the mesh size is the key parameter, whereby two migration mechanisms where identified: the unrestricted mechanism, where the particle size « mesh size, and the restricted mechanism, where particle size is similar to mesh size.

History.

A 1959 book on electrophoresis by Milan Bier cites references from the 1800s. However, Oliver Smithies made significant contributions. Bier states: "The method of Smithies... is finding wide application because of its unique separatory power." Taken in context, Bier clearly implies that Smithies' method is an improvement.

Gel electrophoresis is a method for separation and analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on their size and charge. It is used in clinical chemistry to separate proteins by charge or size (IEF agarose, essentially size independent) and in biochemistry and molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge.

Gelelektrophorese (Wortteile: Gel|elektro|phorese – letzterer abgeleitet von "pherein" ‚tragen‘) ist eine analytische Methode der Chemie und Molekularbiologie, um verschiedene Arten von Molekülen zu trennen.


Name.

Some sources offer that the city was named after its near-legendary founder, "Kharko"

History.

Cultural artifacts date back to the Bronze Age, as well as those of later Scythian and Sarmatian settlers. There is also evidence that the Chernyakhov culture flourished in the area from the second to the sixth centuries.

Establishment.

The city was founded by re-settlers who were running away from the war that engulfed Right-bank Ukraine in 1654 (see Khmelnytsky Uprising). The years before the region was a sparsely populated part of the Cossack Hetmanate. The group of people came onto the banks of Lopan and Kharkiv rivers where an abandoned settlement stood. According to archive documents, the leader of the re-settlers was otaman Ivan Kryvoshlyk.  At first the settlement was self-governed under the jurisdiction of a voivode from Chuhuiv that is to the east. The first appointed voivode from Moscow was Voyin Selifontov in 1656 who started to build a local ostrog (fort). At that time the population of Kharkiv was just over 1000, half of whom were local cossacks, while Selifontov brought along a Moscow garrison of another 70 servicemen. The first Kharkiv voivode

Kharkiv Fortress.

The Kharkiv Fortress was erected around the Assumption Cathedral and its castle was at University Hill. It was between today's streets: vulytsia Kvitky-Osnovianenko, Constitution Square, Rose Luxemburg Square, Proletarian Square, and Cathedral Descent. The fortress had 10 towers: Chuhuivska Tower, Moskovska Tower, Vestovska Tower, Tainytska Tower, Lopanska Corner Tower, Kharkivska Corner Tower and others. The tallest

In the Russian Empire.

In the course of the administrative reform carried out in 1708 by Peter the Great, the area was included into Kiev Governorate. Kharkiv is specifically mentioned as one of the towns making a part of the governorate. In 1727, Belgorod Governorate was split off, and Kharkiv moved to Belgorod Governorate. It was the center of a separate administrative unit, Kharkiv Sloboda Cossack regiment. The regiment at some point was detached from Belgorod Governorate, then attached to it again, until in 1765, Sloboda Ukraine Governorate was established with the seat in Kharkiv.  Kharkiv University was established in 1805 in the Palace of Governorate-General. Alexander Mikolajewicz Mickiewicz, brother of Adam Mickiewicz was a professor of law in the university, another celebrity Goethe searched for instructors for the school. In 1906 Ivan Franko received a doctorate in Russian linguistics here.  The streets were first cobbled in the city centre in 1830. In 1844 the tall Alexander Bell Tower was built next to the first Assumption Cathedral,

The Red October and the Soviet period.

Bolshevik Baltin in the "Chronicle of the Revolution" () noted that during the World War I in December 1914 Kharkiv experienced the most eerie Russian chauvinism (see, Great Russian chauvinism) which knew no limits when Russian ultra-nationalist Black Hundreds were assisted by a local police. Baltin also stated that at that time the Kharkiv Locomotive Factory (employing 6,000 workers) was considered a "citadel of revolutionary movement" yet due to pressure of the local police and the Russian nationalists the revolutionary life was completely suppressed. In January 1915 the Kharkiv Bolshevik organization was accounted of no more than 10 people. The Bolshevik organization in Kharkiv was revived after arrival of Aleksei Medvedev, Nikolay Lyakhin (Petrograd Bolsheviks) and Maksimov and Maria Skobeeva (Moscow Bolsheviks). Following the Russian defeat during Gorlice–Tarnów Offensive and start of the Great Retreat,

German occupation.

During World War II, Kharkiv was the site of several military engagements (see below). The city was captured and recaptured by Nazi Germany on 24 October 1941; there was a disastrous Red Army offensive that failed to capture the city in May 1942; the city was successfully retaken by the Soviets on 16 February 1943, captured for a second time by the Germans on 15 March 1943 and then finally retaken on 23 August 1943. Seventy percent of the city was destroyed and tens of thousands of the inhabitants were killed. Kharkiv, the third largest city in the Soviet Union, was the most populous city in the Soviet Union captured by the

Post-World War II.

In the post-World War II period, many of the destroyed homes and factories were rebuilt. The city was planned to be rebuilt in the style

In independent Ukraine.

By its territorial expansion on September 6, 2012 the city increased its area from about.  A well-known landmark of Kharkiv is the Freedom Square ("Ploshcha Svobody" formerly known as "Dzerzhinsky Square"), which is the ninth largest city square in Europe, and the 28th largest square in the world.  There is an underground rapid-transit system (metro) with about of track and 30 stations. The newest underground station, Peremoha, was opened on 19 August 2016. All the underground stations have very distinctive architecture.  Kharkiv was a host city for UEFA Euro 2012, and hosted three group soccer matches at the reconstructed Metalist Stadium.  A large number of Orthodox cathedrals were built in Kharkiv in the 1990s and 2000s. For example, the Myrrh Bringing Wives Orthodox cathedral,

Geography.

Kharkiv is located at the banks of the Kharkiv, Lopan, and Udy rivers, where they flow into the Seversky Donets watershed in the north-eastern region of Ukraine.  Historically, Kharkiv lies in the Sloboda Ukraine region ("Slobozhanshchyna" also known as "Slobidshchyna") in Ukraine, in which it is considered to be the main city.  The approximate dimensions of city of Kharkiv are: from the North to the South — 24.3 km; from the West to the East — 25.2 km.  Based on Kharkiv's topography, the city can be conditionally divided into four lower districts and four higher districts.  The highest point above sea level in Pyatikhatky in Kharkiv is 202m, the lowest point above sea level in Novoselivka in Kharkiv is 94m.  Kharkiv lies in the large valley of rivers of Kharkiv, Lopan', Udy, and Nemyshlya. This valley lies from the North West to the South East between the Mid Russian highland and Donetsk lowland. All the rivers interconnect in Kharkiv and flow into the river of Northern Donets. A special system of concrete and metal dams was designed and built by engineers to regulate the water level in the rivers in Kharkiv.  Kharkiv has a large number of green city parks with a long history of more than 100 years with very old oak trees and many flowers. Gorky park, or Maxim Gorky Central Park for Culture and Recreation, is Kharkiv's largest public garden. The park has nine areas: children, extreme sports, family entertainment, a medieval area, entertainment center, French park, cable car, sports grounds, retro park.

Climate.

Kharkiv's climate is humid continental (Köppen climate classification "Dfb") with cold, snowy winters and dry and hot summers.  The city has rather sunny, warm summers which, however, are relatively

Governance.

Legal status and local government.

The Mayor of Kharkiv and the City Council govern all the business and administrative affairs in the City of Kharkiv.  The Mayor of Kharkiv has the executive powers; the City Council has the administrative powers as far as the government issues are concerned.

Politics.

The 2014 pro-Russian unrest in Ukraine affected Kharkiv but to a lesser extent than in neighbouring Donbass, where tensions led to armed conflict. On 2 March 2014, a Russian "tourist" from Moscow replaced the Ukrainian flag with a Russian flag on the Kharkiv regional state administration building. Five days later, pro-Russian protestors occupied the building and unilaterally declared independence from Ukraine as the "Kharkov People's Republic". The next day, the building was retaken by Ukrainian special forces. Doubts arose about the local origin of the protestors after they initially stormed an opera and ballet theatre believing it was the city hall. On 13 April, some pro-Russian protesters again made it inside the Kharkiv regional state administration building. Later on 13 April, the building permanently returned to full Ukrainian control. Violent clashes resulted in the severe beating of at least 50 pro-Ukrainian protesters in attacks by pro-Russian protesters.  Kharkiv returned to relative calm by 30 April. Relatively peaceful demonstrations continued to be held, with "pro-Russian" rallies gradually diminishing and "pro-Ukrainian unity" demonstrations growing in numbers. On 28 September, activists dismantled Ukraine's largest

Administrative divisions.

While Kharkiv is the administrative centre of the Kharkiv Oblast (province), the city affairs are managed by the Kharkiv Municipality. Kharkiv is a city of oblast subordinance.  The territory of Kharkiv is divided into 9 administrative

Demographics.

According to the 1989 Soviet Union Census, the population of the city was 1,593,970. In 1991, it decreased to 1,510,200, including 1,494,200 permanent residents. Kharkiv is the second-largest city in Ukraine after the

Religion.

Kharkiv is an important religious center in Eastern Ukraine.  There are many old and new cathedrals, associated with various churches in Kharkiv.  The St. Assumption Orthodox Cathedral was built in Kharkiv in the 1680s and re-built in 1820s-1830s.  The St. Pokrovsky Orthodox Monastery Cathedral was created in Kharkiv in 1689–1729.  The St. Annunciation Orthodox Cathedral is one of the tallest Orthodox churches in the world. It was completed in Kharkiv on October 2,

Economy.

The 2016–2020 economic development strategy: "Kharkiv Success Strategy", is created in Kharkiv.

International Economic Forum.

The International Economic Forum: Innovations. Investments. Kharkiv Innitiatives! is being conducted in Kharkiv every year.  In 2015, the International Economic Forum: Innovations. Investments. Kharkiv Innitiatives! was attended by the diplomatic corps representatives from 17 world countries, working in Ukraine together with top-management of trans-national corporations and investment funds; plus Ukrainian People's Deputies; plus Ukrainian Central government officials, who determine the national economic development strategy; plus local government managers, who perform practical steps in implementing that strategy; plus managers of technical assistance to Ukraine;

International Industrial Exhibitions.

The international industrial exhibitions are usually

Industrial corporations.

During the Soviet era, Kharkiv was the capital of industrial production in Ukraine and the third largest centre of industry and commerce in the USSR. After the collapse of the Soviet Union the largely defence-systems-oriented industrial production of the city decreased significantly. In the early 2000s, the industry started to recover and adapt to market economy needs. Now

IT industry.

As of April 2018, there were 25,000 specialists in IT industry of the Kharkiv region, 76% of them were related to computer programming. Thus, Kharkiv accounts for 14% of all IT specialists in Ukraine and makes the second largest IT location in the country, right after the capital Kyiv.  Also, the number of active IT companies in the region to be 445, five of them employing more than 601 people. Besides, there

Finance industry.

Kharkiv is also the headquarters of one of the largest

Trade industry.

There are many large modern shopping malls

Science and education.

Higher education.

The Vasyl N. Karazin Kharkiv National University is the most prestigious reputable classic university, which was founded due to the efforts by Vasily Karazin in Kharkiv in 1804–1805. On, the Decree on the Opening of the Imperial University in Kharkiv came into force.  The Roentgen Institute opened in 1931. It was a specialist cancer treatment facility with 87 research workers, 20 professors, and specialist medical staff.

Scientific research.

The city has a high concentration of research institutions, which are independent or loosely connected with the universities. Among them are three national science centres: Kharkiv Institute of Physics and Technology, Institute of Meteorology, Institute for Experimental and Clinical Veterinary Medicine and 20 national research institutions of the National Academy of Science of Ukraine, such as the B Verkin Institute for Low Temperature Physics and Engineering,

Public libraries.

In addition to the libraries affiliated with the various universities

Secondary schools.

Kharkiv has 212 (secondary education)

Education centers.

There is the educational "Landau Center", which

Culture.

Kharkiv is one of the main cultural centres in Ukraine. It is home to 20 museums, over 10 theatres and a number of art galleries. Large music and cinema festivals are hosted in Kharkiv almost every year.

Theatres.

The Kharkiv National Academic Opera and Ballet Theatre named after N. V. Lysenko is the biggest theatre in Kharkiv.  Kharkiv Ukrainian Drama Theatre named after T. G. Shevchenko is popular among Ukrainian speaking people  The Kharkiv Academic Russian Drama Theatre named after A.S. Pushkin was recently renovated, and it

Literature.

In the 1930s Kharkiv was referred to as a Literary Klondike. It was the centre for the work of literary figures such as: Les Kurbas, Mykola Kulish, Mykola Khvylovy, Mykola Zerov, Valerian Pidmohylny, Pavlo Filipovych, Marko Voronny, Oleksa Slisarenko. Over 100 of these writers were repressed during the Stalinist purges of the 1930s. This tragic event in Ukrainian history is

Music.

There is the Kharkiv Philharmonic Society in the city. The leading group active in the Philharmonic is the Academic Symphony Orchestra. It has 100 musicians of a high professional level, many of whom are prize-winners in international and national competitions.  There is the Organ Music Hall in the city. The Organ Music Hall is situated at the Assumption Cathedral presently. The Rieger–Kloss organ was installed in the building of the Organ Music

Movies.

From 1907 to 2008, at least 86 feature films were shot in the city's territory and its region. The most

Movies festival.

The Kharkiv Lilacs international movie festival is very popular among movie stars, makers and producers in Ukraine, Eastern Europe, Western

Visual arts.

Kharkiv has been a home for many famous painters, including Ilya Repin, Zinaida Serebryakova, Henryk Siemiradzki, and Vasyl Yermilov. There are many modern

Museums.

There is the M. F. Sumtsov Kharkiv Historical Museum in the city.  The Natural History Museum at V. N. Karazin Kharkiv National University was founded in Kharkiv on April 2, 1807. The museum is visited by 40000 visitors every year.  The V. N. Karazin Kharkiv National University History Museum was established in Kharkiv in 1972.  The V. N. Karazin Kharkiv National University Archeology Museum was founded in Kharkiv on March 20,

Landmarks.

Of the many attractions of the Kharkiv city are the: Dormition Cathedral, Annunciation Cathedral, Derzhprom building, Freedom Square, Taras Shevchenko Monument, Mirror Stream, Historical Museum, Choral Synagogue,

Media.

There are a large number of broadcast and internet

Transport.

The city of Kharkiv is one of the largest transportation centers in Ukraine, which is connected to numerous cities of the world by air, rail and road traffic. The city has many transportation methods, including: public transport, taxis, railways, and air traffic. There are about 250 thousand cars in the city.

Local transport.

Being an important transportation centre of Ukraine, many different means of transportation are available in Kharkiv. Kharkiv's Metro is the city's rapid transit system operating since 1975. It

Railways.

The first railway connection of Kharkiv was opened in 1869. The first train to arrive in Kharkiv came from the north on 22 May 1869, and on 6 June 1869, traffic was opened on the Kursk–Kharkiv–Azov line.

Air.

Kharkiv is served by Kharkiv International Airport has been granted international status. Charter flights are also available. The former largest carrier

Recreation.

Kharkiv contains numerous parks and gardens such as the Gor'ky park, Shevchenko park, Hydro park, Strelka park, Sarzhyn Yar and Feldman ecopark. The Gor'ky park is a common place for recreation activities among visitors and local people. The Shevchenko park is situated in close proximity to the V.N. Karazin National University. It is

Sport.

Kharkiv International Marathon.

The Kharkiv International Marathon is considered as a prime international sportive event, attracting many

Football (soccer).

The most popular sport is football. The city has several football clubs playing in the Ukrainian national competitions. The most successful is "FC Dynamo Kharkiv" that won eight national

Other sports.

Kharkiv also had some ice hockey clubs, MHC Dynamo Kharkiv, Vityaz Kharkiv, Yunost Kharkiv, HC Kharkiv, who competed in the Ukrainian Hockey Championship.  Avangard Budy is a bandy club from Kharkiv, which won the Ukrainian championship in 2013.  There are a men's volleyball teams, Lokomotyv Kharkiv and Yurydychna Akademіya Kharkiv, which performed in Ukraine and in European competitions.  RC Olymp is the city's rugby union

Twin towns – sister cities.

Kharkiv is twinned with:

Kharkiv (, ), also known as Kharkov ( ) is the second largest city in Ukraine. In the northeast of the country, it is the largest city of the Slobozhanshchyna historical region. Kharkiv is the administrative centre of Kharkiv Oblast and of the surrounding Kharkiv Raion, though administratively it is incorporated as a city of oblast significance and does not belong to the raion.

Charkiw (; ) ist nach Kiew mit rund 1,5 Millionen Einwohnern (2019) die zweitgrößte Stadt der Ukraine und mit 42 Universitäten und Hochschulen das nach Kiew bedeutendste Wissenschafts- und Bildungszentrum des Landes.


Classification.

Tamil belongs to the southern branch of the Dravidian languages, a family of around 26 languages native to the Indian subcontinent. It is also classified as being part of a Tamil language family that, alongside Tamil proper, includes the languages of about 35 ethno-linguistic groups such as the Irula and Yerukula languages (see SIL Ethnologue).  The closest major relative of Tamil is Malayalam; the two began diverging around the 9th century AD. Although many of the differences between Tamil and Malayalam demonstrate a pre-historic split of the western dialect, the process of separation into a distinct language, Malayalam, was not completed until sometime in the 13th or 14th century.

History.

According to linguists like Bhadriraju Krishnamurti, Tamil, as a Dravidian language, descends from Proto-Dravidian, a proto-language. Linguistic reconstruction suggests that Proto-Dravidian was spoken around the third millennium BC, possibly in the region around the lower Godavari river basin in peninsular India. The material evidence suggests that the speakers of Proto-Dravidian were of the culture associated with the Neolithic complexes of South India. The earliest epigraphic attestations of Tamil are generally taken to have been written from the 2nd century BC.  Among Indian languages, Tamil has the most ancient non-Sanskritic Indian literature. Scholars categorise the attested history of the language into three periods: Old Tamil (300 BC–AD 700), Middle Tamil (700–1600) and Modern Tamil (1600–present). In November 2007, an excavation at Quseir-al-Qadim revealed Egyptian pottery dating back to first century BC with ancient Tamil Brahmi inscriptions. John Guy states that Tamil was the lingua franca for early maritime traders from India.

Legend.

According to Hindu legend, Tamil or in personification form Tamil Thāi (Mother Tamil) was created by Lord Shiva. Murugan, revered as the Tamil God, along with sage Agastya, brought it to the people.

Etymology.

The earliest extant Tamil literary works and their commentaries celebrate the Pandiyan Kings for the organization of long-termed Tamil Sangams, which researched, developed and made amendments in Tamil language. Even though the name of the language which was developed by these Tamil Sangams is mentioned as Tamil, the period when the name "Tamil" came to be applied to the language is unclear, as is the precise etymology of the name. The earliest attested use of the name is found in Tholkappiyam, which is dated as early as 1st century BC. Southworth suggests that the name comes from > "self-speak", or "one's own speech". Kamil Zvelebil suggests an etymology of, with meaning "self" or "one's self", and "" having the connotation of "unfolding sound". Alternatively, he suggests a derivation of < < * < *, meaning in origin "the proper process (of speaking)".  The Tamil Lexicon of University of Madras defines the word "Tamil" as "sweetness". S. V. Subramanian suggests the meaning "sweet sound", from "tam" — "sweet" and "il" — "sound".

Old Tamil.

Old Tamil is the period of the Tamil language spanning the 3rd century BC to the 8th century AD. The earliest records in Old Tamil are short inscriptions from between the 3rd and 2nd century BC in caves and on pottery. These inscriptions are written in a variant of the Brahmi script called Tamil-Brahmi. The earliest long text in Old Tamil is the "Tolkāppiyam", an early work on Tamil grammar and poetics, whose oldest layers could be as old as the 1st century BC. Many literary works in Old Tamil have also survived. These include a corpus of 2,381 poems collectively known as Sangam literature. These poems are usually dated to between the 1st and 5th centuries AD.

Middle Tamil.

The evolution of Old Tamil into Middle Tamil, which is generally taken to have been completed by the 8th century, was characterised by a number of phonological and grammatical changes. In phonological terms, the most important shifts were the virtual disappearance of the aytam (ஃ), an old phoneme, the coalescence of the alveolar and dental nasals, and the transformation of the alveolar plosive into a rhotic. In grammar, the most important change was the emergence of the present tense. The present tense evolved out of the verb'(), meaning "to be possible" or "to befall". In Old Tamil, this verb was used as an aspect marker to indicate that an action was micro-durative, non-sustained or non-lasting, usually in combination with a time marker such as'(). In Middle Tamil, this usage evolved into a present tense marker – "" () – which combined the old aspect and time markers.

Modern Tamil.

The Nannul remains the standard normative grammar for modern literary Tamil, which therefore continues to be based on Middle Tamil of the 13th century rather than on Modern Tamil. Colloquial spoken Tamil, in contrast, shows a number of changes. The negative conjugation of verbs, for example, has fallen out of use in Modern Tamil – instead, negation is expressed either morphologically or syntactically. Modern spoken Tamil also shows a number of sound changes, in particular, a tendency to lower high vowels in initial and medial positions, and the disappearance of vowels between plosives and between a plosive and rhotic.  Contact with European languages affected written and spoken Tamil. Changes in written Tamil include the use of European-style punctuation and the use of consonant clusters that were not permitted in Middle Tamil. The syntax of written Tamil has also changed, with the introduction of new aspectual auxiliaries and more complex sentence structures, and with the emergence of a more rigid word order that resembles the syntactic argument structure of English. Simultaneously, a strong strain of linguistic purism emerged in the early 20th century, culminating in the Pure Tamil Movement which called for removal of all Sanskritic elements from Tamil. It received some support from Dravidian parties. This led to the replacement of a significant number of Sanskrit loanwords by Tamil equivalents, though many others remain.

Geographic distribution.

Tamil is the primary language of the majority of the people residing in Tamil Nadu, Puducherry, (in India) and in Northern Province, Eastern Province (Sri Lanka). The language is spoken among small minority groups in other states of India which include Karnataka, Andhra Pradesh, Kerala, Maharashtra and in certain regions of Sri Lanka such as Colombo and the hill country. Tamil or dialects of it were used widely in the state of Kerala as the major language of administration, literature and common usage until the 12th century AD. Tamil was also used widely in inscriptions found in southern Andhra Pradesh districts of Chittoor and Nellore until the 12th century AD. Tamil was used for inscriptions from the 10th through 14th centuries in southern Karnataka districts such as Kolar, Mysore, Mandya and Bangalore.  There are currently sizeable Tamil-speaking populations descended from colonial-era migrants in Malaysia, Singapore, Philippines, Mauritius, South Africa, Indonesia, Thailand, Burma, and Vietnam. A large community of Pakistani Tamils speakers exists in Karachi, Pakistan, which includes Tamil-speaking Hindus as well as Christians and Muslims – including some Tamil-speaking Muslim refugees from Sri Lanka. There are about 100 Tamil Hindu families in Madrasi Para colony in Karachi.They speak impeccable Tamil along with Urdu, Punjabi and Sindhi. Many in Réunion, Guyana, Fiji, Suriname, and Trinidad and Tobago have Tamil origins, but only a small number speak the language. In Reunion where the Tamil language was forbidden to be learnt and used in public space by France it is now being relearnt by students and adults. Tamil is also spoken by migrants from Sri Lanka and India in Canada, the United States (especially New Jersey and New York City), Australia, the United Kingdom, South Africa, and many other European and Middle Eastern countries.

Legal status.

Tamil is the official language of the Indian state of Tamil Nadu and one of the 22 languages under schedule 8 of the constitution of India. It is one of the official languages of the union territories of Puducherry and the Andaman and Nicobar Islands. Tamil is also one of the official languages of Singapore. Tamil is one of the official and national languages of Sri Lanka, along with Sinhala. It was once given nominal official status in the Indian state of Haryana, purportedly as a rebuff to Punjab, though there was no attested Tamil-speaking population in the state, and was later replaced by Punjabi, in 2010. In Malaysia, 543 primary education government schools are available fully in Tamil medium. The establishment of Tamil medium schools has been in process in Myanmar to provide education completely in Tamil language by the Tamils who settled there 200 years ago. Tamil is taught in Canada for the local Tamil minority populations and the month of January has been declared "Tamil Heritage Month" by the Parliament of Canada. Tamil enjoys a special status of protection under Article 6(b), Chapter 1 of the Constitution of South Africa and is taught as a subject in schools in KwaZulu-Natal province. Recently, it has been rolled out as a subject of study in schools in the French overseas department of Réunion.  In addition, with the creation in October 2004 of a legal status for classical languages by the Government of India and following a political campaign supported by several Tamil associations, Tamil became the first legally recognised Classical language of India. The recognition was announced by the contemporaneous President of India, Abdul Kalam, in a joint sitting of both houses of the Indian Parliament on 6 June 2004.

Dialects.

Region-specific variations.

The socio-linguistic situation of Tamil is characterised by diglossia: there are two separate registers varying by socioeconomic status, a high register and a low one. Tamil dialects are primarily differentiated from each other by the fact that they have undergone different phonological changes and sound shifts in evolving from Old Tamil. For example, the word for "here"—' in "Centamil" (the classic variety)—has evolved into'in the Kongu dialect of Coimbatore, "inga" in the dialect of Thanjavur, and'in some dialects of Sri Lanka. Old Tamil's'(where'means place) is the source of'in the dialect of Tirunelveli, Old Tamil'is the source of'in the dialect of Madurai, and "" in some northern dialects. Even now, in the Coimbatore area, it is common to hear "" meaning "that place". Although Tamil dialects do not differ significantly in their vocabulary, there are a few exceptions. The dialects spoken in Sri Lanka retain many words and grammatical forms that are not in everyday use in India, and use many other words slightly differently. Tamil dialects include Central Tamil dialect, Kongu Tamil, Madras Bashai, Madurai Tamil, Nellai Tamil, Kumari tamil in India and Batticaloa Tamil dialect, Jaffna Tamil dialect, Negombo Tamil dialect in Sri Lanka. Sankethi dialect in Karnataka has been heavily influenced by Kannada.

Loanword variations.

The dialect of the district of Palakkad in Kerala has many Malayalam loanwords, has been influenced by Malayalam's syntax, and has a distinctive Malayalam accent. Similarly, Tamil spoken in Kanyakumari District has more unique words and phonetic style than Tamil spoken at other parts of Tamil Nadu. The words and phonetics are so different that a person from Kanyakumari district is easily identifiable by their spoken Tamil. Hebbar and Mandyam dialects, spoken by groups of Tamil Vaishnavites who migrated to Karnataka in the 11th century, retain many features of the "Vaishnava paribasai", a special form of Tamil developed in the 9th and 10th centuries that reflect Vaishnavite religious and spiritual values. Several castes have their own sociolects which most members of that caste traditionally used regardless of where they come from. It is often possible to identify a person's caste by their speech. Tamil in Sri Lanka incorporates loan words from Portuguese, Dutch, and English.

Spoken and literary variants.

In addition to its dialects, Tamil exhibits different forms: a classical literary style modelled on the ancient language ('), a modern literary and formal style ('), and a modern colloquial form ('). These styles shade into each other, forming a stylistic continuum. For example, it is possible to write'with a vocabulary drawn from ', or to use forms associated with one of the other variants while speaking '.  In modern times,'is generally used in formal writing and speech. For instance, it is the language of textbooks, of much of Tamil literature and of public speaking and debate. In recent times, however,'has been making inroads into areas that have traditionally been considered the province of '. Most contemporary cinema, theatre and popular entertainment on television and radio, for example, is in ', and many politicians use it to bring themselves closer to their audience. The increasing use of'in modern times has led to the emergence of unofficial ‘standard' spoken dialects. In India, the ‘standard' ', rather than on any one dialect, but has been significantly influenced by the dialects of Thanjavur and Madurai. In Sri Lanka, the standard is based on the dialect of Jaffna.

Writing system.

After Tamil Brahmi fell out of use, Tamil was written using a script called amongst others such as Grantha and Pallava. The current Tamil script consists of 12 vowels, 18 consonants and one special character, the "āytam". The vowels and consonants combine to form 216 compound characters, giving a total of 247 characters (12 + 18 + 1 + (12 x 18)). All consonants have an inherent vowel "a", as with other Indic scripts. This inherent vowel is removed by adding a tittle called a "", to the consonantal sign. For example, is "ṉa" (with the inherent "a") and is "ṉ" (without a vowel). Many Indic scripts have a similar sign, generically called virama, but the Tamil script is somewhat different in that it nearly always uses a visible "puḷḷi" to indicate a 'dead consonant' (a consonant without a vowel). In other Indic scripts, it is generally preferred to use a ligature or a half form to write a syllable or a cluster containing a dead consonant, although writing it with a visible virama is also possible. The Tamil script does not differentiate voiced and unvoiced plosives. Instead, plosives are articulated with voice depending on their position in a word, in accordance with the rules of Tamil phonology.  In addition to the standard characters, six characters taken from the Grantha script, which was used in the Tamil region to write Sanskrit, are sometimes used to represent sounds not native to Tamil, that is, words adopted from Sanskrit, Prakrit and other languages. The traditional system prescribed by classical grammars for writing loan-words, which involves respelling them in accordance with Tamil phonology, remains, but is not always consistently applied. ISO 15919 is an international standard for the transliteration of Tamil and other Indic scripts into Latin characters. It uses diacritics to map the much larger set of Brahmic consonants and vowels to the Latin script. Tamil can be transliterated into English by using ISO 15919, since English language uses the Latin script for writing.

Numerals and symbols.

Apart from the usual numerals, Tamil has numerals for 10, 100 and 1000. Symbols for day, month, year, debit, credit, as above, rupee, and numeral are present as well. Tamil also uses several historical fractional signs.

Phonology.

Tamil phonology is characterised by the presence of retroflex consonants and multiple rhotics. Tamil does not distinguish phonologically between voiced and unvoiced consonants; phonetically, voice is assigned depending on a consonant's position in a word. Tamil phonology permits few consonant clusters, which can never be word initial. Native grammarians classify Tamil phonemes into vowels, consonants, and a "secondary character", the āytam.

Vowels.

Tamil has five vowel qualities, namely,,, and. Each may be long or short. There are two diphthongs, and. Long vowels are about twice as long as short vowels. The diphthongs are usually pronounced about 1.5 times as long as short vowels. Most grammatical texts place them with the long vowels.

Consonants.

Tamil consonants are presented as hard, soft and medial in some grammars which roughly corresponds to plosives, nasals and approximants. Unlike most Indian languages, Tamil does not distinguish aspirated and unaspirated consonants. In addition, the voicing of plosives is governed by strict rules in "". Plosives are unvoiced if they occur word-initially or doubled. Elsewhere they are voiced, with a few becoming fricatives intervocalically, which means that voicing is not a phonological trait for plosives. Nasals and approximants are always voiced.  Tamil is characterised by its use of more than one type of coronal consonants: like many of the other languages of India, it contains a series of retroflex consonants. Notably, the Tamil retroflex series includes the retroflex approximant () (example Tamil; often transcribed 'zh'), which is rare in the Indo-Aryan languages. Among the other Dravidian languages, the retroflex approximant also occurs in Malayalam (for example in 'Kozhikode'), disappeared from spoken Kannada around 1000 AD (although the character is still written, and exists in Unicode, ೞ as in ಕೊೞೆ), and was never present in Telugu. In many dialects of colloquial Tamil, this consonant is seen as disappearing and shifting to the alveolar lateral approximant. Dental and alveolar consonants also historically contrasted with each other, a typically Dravidian trait not found in the neighbouring Indo-Aryan languages. While this distinction can still be seen in the written language, it has been largely lost in colloquial spoken Tamil, and even in literary usage the letters (dental) and (alveolar) may be seen as allophonic. Likewise, the historical alveolar stop has transformed into a trill consonant in many modern dialects.  A chart of the Tamil consonant phonemes in the follows:  The plosives have voiced allophones after nasals. The sounds and are peripheral to the phonology of Tamil, being found only in loanwords and frequently replaced by native sounds. There are well-defined rules for elision in Tamil categorised into classes based on the phoneme which undergoes elision.

Āytam.

Classical Tamil had a phoneme called the "āytam", written as ‘'. Tamil grammarians of the time classified it as a dependent phoneme (or restricted phoneme) (""), but it is very rare in modern Tamil. The rules of pronunciation given in the "Tolkāppiyam", a text on the grammar of Classical Tamil, suggest that the "āytam" could have glottalised the sounds it was combined with. It has also been suggested that the "āytam" was used to represent the voiced implosive (or closing part or the first half) of geminated voiced plosives inside a word. The āytam, in modern Tamil, is also used to convert "p" to "f" when writing English words using the Tamil script.

Grammar.

Tamil employs agglutinative grammar, where suffixes are used to mark noun class, number, and case, verb tense and other grammatical categories. Tamil's standard metalinguistic terminology and scholarly vocabulary is itself Tamil, as opposed to the Sanskrit that is standard for most Aryan languages.  Much of Tamil grammar is extensively described in the oldest known grammar book for Tamil, the "Tolkāppiyam". Modern Tamil writing is largely based on the 13th century grammar'which restated and clarified the rules of the "Tolkāppiyam", with some modifications. Traditional Tamil grammar consists of five parts, namely ', "sol", ', "yāppu", '. Of these, the last two are mostly applied in poetry.  Tamil words consist of a lexical root to which one or more affixes are attached. Most Tamil affixes are suffixes. Tamil suffixes can be derivational suffixes, which either change the part of speech of the word or its meaning, or inflectional suffixes, which mark categories such as person, number, mood, tense, etc. There is no absolute limit on the length and extent of agglutination, which can lead to long words with many suffixes, which would require several words or a sentence in English. To give an example, the word "pōkamuṭiyātavarkaḷukkāka" (போகமுடியாதவர்களுக்காக) means "for the sake of those who cannot go" and consists of the following morphemes:

Morphology.

Tamil nouns (and pronouns) are classified into two super-classes (')—the "rational" ('), and the "irrational" ("")—which include a total of five classes ("pāl", which literally means "gender"). Humans and deities are classified as "rational", and all other nouns (animals, objects, abstract nouns) are classified as irrational. The "rational" nouns and pronouns belong to one of three classes ("pāl")—masculine singular, feminine singular, and rational plural. The "irrational" nouns and pronouns belong to one of two classes: irrational singular and irrational plural. The "pāl" is often indicated through suffixes. The plural form for rational nouns may be used as an honorific, gender-neutral, singular form.  Suffixes are used to perform the functions of cases or postpositions. Traditional grammarians tried to group the various suffixes into eight cases corresponding to the cases used in Sanskrit. These were the nominative, accusative, dative, sociative, genitive, instrumental, locative, and ablative. Modern grammarians argue that this classification is artificial, and that Tamil usage is best understood if each suffix or combination of suffixes is seen as marking a separate case. Tamil nouns can take one of four prefixes: "i", "a", "u", and "e" which are functionally equivalent to the demonstratives in English. For example, the word "vazhi" (வழி) meaning "way" can take these to produce "ivvazhi" (இவ்வழி) "this way", "avvazhi" (அவ்வழி) "that way", "uvvazhi" (உவ்வழி) "the medial way" and "evvazhi" (எவ்வழி) "which way".  Tamil verbs are also inflected through the use of suffixes. A typical Tamil verb form will have a number of suffixes, which show person, number, mood, tense, and voice.  Traditional grammars of Tamil do not distinguish between adjectives and adverbs, including both of them under the category "uriccol", although modern grammarians tend to distinguish between them on morphological and syntactical grounds. Tamil has many ideophones that act as adverbs indicating the way the object in a given state "says" or "sounds".  Tamil does not have articles. Definiteness and indefiniteness are either indicated by special grammatical devices, such as using the number "one" as an indefinite article, or by the context. In the first person plural, Tamil makes a distinction between inclusive pronouns'(we),'(our) that include the addressee and exclusive pronouns'(we),'(our) that do not.

Syntax.

Tamil is a consistently head-final language. The verb comes at the end of the clause, with a typical word order of subject–object–verb (SOV). However, word order in Tamil is also flexible, so that surface permutations of the SOV order are possible with different pragmatic effects. Tamil has postpositions rather than prepositions. Demonstratives and modifiers precede the noun within the noun phrase. Subordinate clauses precede the verb of the matrix clause.  Tamil is a null-subject language. Not all Tamil sentences have subjects, verbs, and objects. It is possible to construct grammatically valid and meaningful sentences which lack one or more of the three. For example, a sentence may only have a verb—such as'("completed")—or only a subject and object, without a verb such as'("That [is] my house"). Tamil does not have a copula (a linking verb equivalent to the word "is"). The word is included in the translations only to convey the meaning more easily.

Vocabulary.

The vocabulary of Tamil is mainly Dravidian. A strong sense of linguistic purism is found in Modern Tamil, which opposes the use of foreign loanwords. Nonetheless, a number of words used in classical and modern Tamil are loanwords from the languages of neighbouring groups, or with whom the Tamils had trading links, including Munda (for example, "frog" from Munda ), Malay (e.g. "sago" from Malay ), Chinese (for example, "skiff" from Chinese san-pan) and Greek (for example, from Greek ὥρα). In more modern times, Tamil has imported words from Urdu and Marathi, reflecting groups that have influenced the Tamil area at times, and from neighbouring languages such as Telugu, Kannada, and Sinhala. During the modern period, words have also been adapted from European languages, such as Portuguese, French, and English.  The strongest impact of purism in Tamil has been on words taken from Sanskrit. During its history, Tamil, along with other Dravidian languages like Telugu, Kannada, Malayalam etc., was influenced by Sanskrit in terms of vocabulary, grammar and literary styles, reflecting the increased trend of Sanskritisation in the Tamil country. Tamil vocabulary never became quite as heavily Sanskritised as that of the other Dravidian languages, and unlike in those languages, it was and remains possible to express complex ideas (including in science, art, religion and law) without the use of Sanskrit loan words. In addition, Sanskritisation was actively resisted by a number of authors of the late medieval period, culminating in the 20th century in a movement called "" (meaning "pure Tamil movement"), led by Parithimaar Kalaignar and Maraimalai Adigal, which sought to remove the accumulated influence of Sanskrit on Tamil. As a result of this, Tamil in formal documents, literature and public speeches has seen a marked decline in the use Sanskrit loan words in the past few decades, under some estimates having fallen from 40–50% to about 20%. As a result, the Prakrit and Sanskrit loan words used in modern Tamil are, unlike in some other Dravidian languages, restricted mainly to some spiritual terminology and abstract nouns.  In the 20th century, institutions and learned bodies have, with government support, generated technical dictionaries for Tamil containing neologisms and words derived from Tamil roots to replace loan words from English and other languages. As of 2019, the language had a listed vocabulary of over 470,000 unique words, including those from old literary sources. In November 2019, the state government issued an order to add 9,000 new words to the vocabulary.

Influence.

Words of Tamil origin occur in other languages. A notable example of a word in worldwide use with Dravidian (not specifically Tamil) etymology is "orange", via Sanskrit'from a Dravidian predecessor of Tamil "nartaṅkāy" "fragrant fruit". One suggestion as to the origin of the word "anaconda" is the Tamil "anaikkonda," "having killed an elephant". Examples in English include "cheroot" (' meaning "rolled up"), "mango" (from "māngāi"), "mulligatawny" (from ', "pepper water"), "pariah" (from "paraiyan"), "curry" (from "kari"), "catamaran" (from ', "bundled logs"), and "congee" (from "kanji" – rice porridge or gruel).

Sample text.

The following is a sample text in literary Tamil of Article 1 of the Universal Declaration of Human Rights:  Tamil in the Tamil script: Romanized Tamil: Tamil in the International Phonetic Alphabet: Gloss: Translation:

Tamil (; "", ) is a Dravidian language predominantly spoken by the Tamil people of India and Sri Lanka, and by the Tamil diaspora and Sri Lankan Moors. Tamil is an official language in three countries: India, Sri Lanka and Singapore. In India, it is the official language of the Indian state of Tamil Nadu and the Union Territory of Puducherry. Furthermore, Tamil is used as one of the languages of education in Malaysia, along with English, Malay and Mandarin. Tamil is spoken by significant minorities in the four other South Indian states of Kerala, Karnataka, Andhra Pradesh and Telangana and the Union Territory of the Andaman and Nicobar Islands. It is one of the 22 scheduled languages of India.

Tamil ( "tamiḻ" [], auch "Tamilisch") ist eine Sprache aus der dravidischen Sprachfamilie. Sie wird von 85,2 Millionen Angehörigen des Volks der Tamilen vor allem im südindischen Bundesstaat Tamil Nadu und in Sri Lanka als Muttersprache gesprochen. Tamil ist weniger stark vom Sanskrit beeinflusst worden als die übrigen dravidischen Literatursprachen. Mit einer eigenständigen Literaturgeschichte von über 2000 Jahren hat das Tamil die längste durchgängige Tradition aller modernen indischen Sprachen und ist in Indien als klassische Sprache anerkannt. Im modernen Tamil herrscht eine Situation der Diglossie, das heißt, die am klassischen Tamil angelehnte Schriftsprache unterscheidet sich stark von der Umgangssprache.