Schott AG is an international manufacturing group of glass and glass-ceramics. The company is headquartered in Mainz and employs 15,100 people worldwide. All shares of Schott AG are held by the Carl Zeiss Foundation; the company reported sales worth 2.05 billion Euros in its fiscal year 2016/2017. In 1884, the glass chemist Otto Schott partnered with the congenial Ernst Abbe, Carl Zeiss and his son Roderich Zeiss, founded the Glastechnisches Laboratorium Schott & Genossen, which would become Jenaer Glaswerke Schott & Genossen and Schott AG. Schott developed and manufactured optical glasses for microscopes and binoculars. Around 1890 Schott developed borosilicate glass products featuring a low thermal expansion coefficient and high chemical resistance suitable for laboratory equipment, marketed under the DURAN brand until the equity carve-out of these products to the DURAN Group in 2005. Glass-ceramics with lower thermal expansion coefficient have been marketed since 1968 as Zerodur for telescope mirrors and other technical applications and Ceran for cooktops.
Erich Schott, the son of the company founder, took over the management of the plant in 1927. Chemist Marga Faulstich worked during this time for company Schott AG; the company suffered a severe blow at the end of World War II, when American troops brought its management and select experts over to West Germany. After the main production plant in Jena was expropriated by the communist government, Erich Schott opened a new plant in Mainz, the company's current headquarters, in 1952. During Germany's division, there were two independent companies: the VEB Jenaer Glaswerk at the historical site, which would be integrated into the combine VEB Carl Zeiss Jena, the glassworks in Mainz that traded under the name Jenaer Glaswerk Schott & Gen. After the close cooperation of the two glassworks in the first years following World War II was stopped by the GDR in 1953, a dispute arose over the use of the company's name and logo, a square with a circle and the words Jena Glass with the superscript "er"; the two parties reached an agreement in 1981, which allowed the West German company to use the name with the supercript and the square with a circle, while the East German company was permitted to use the term "Jenaer Glass."
After the fall of the inner German border in 1989, the company based in Mainz acquired the East German company in Jena. In 2008, Schott announced that it planned to produce crystalline photovoltaic cells and modules with a total of 450 MW annually, it planned to produce thin-film PV wafers with a capacity of 100 MW. In 2009, the company inaugurated a US$100 million solar manufacturing facility in Albuquerque, New Mexico, USA to build receivers for concentrated solar thermal power plants and 64 MW of photovoltaic modules, they had been making 15 MW of photovoltaics annually in Billerica, until the factory was closed in 2009. In June 2012, Schott announced that its Albuquerque plant would close down, laying off all photovoltaic cell manufacturing employees and ramping down the remaining employees over the rest of the summer; the company started operating in China with a large production. SCHOTT-Rohrglas GmbH Official company website
Soda–lime glass called soda–lime–silica glass, is the most prevalent type of glass, used for windowpanes and glass containers for beverages and some commodity items. Glass bakeware is made of borosilicate glass. Soda–lime glass accounts for about 90% of manufactured glass. Soda–lime glass is inexpensive, chemically stable, reasonably hard, workable; because it can be resoftened and remelted numerous times, it is ideal for glass recycling. It is used in preference to chemically-pure silica, silicon dioxide, otherwise known as fused quartz. Whereas pure silica has excellent resistance to thermal shock, being able to survive immersion in water while red hot, its high melting temperature and viscosity make it difficult to work with. Other substances are therefore added to simplify processing. One is sodium carbonate, which lowers the glass-transition temperature. However, the soda makes the glass water-soluble, undesirable. To provide for better chemical durability, the "lime" is added; this is calcium oxide obtained from limestone.
In addition, magnesium oxide and alumina, aluminium oxide, contribute to the durability. The resulting glass contains about 70 to 74% silica by weight; the manufacturing process for soda–lime glass consists in melting the raw materials, which are the silica, lime (in the form of, aluminium oxide. The temperature is only limited by the quality of the furnace structure material and by the glass composition. Inexpensive minerals such as trona and feldspar are used instead of pure chemicals. Green and brown bottles are obtained from raw materials containing iron oxide; the mix of raw materials is termed batch. Soda–lime glass is divided technically into glass used for windows, called flat glass, glass for containers, called container glass; the two types differ in the application, production method, chemical composition. Flat glass has a higher magnesium oxide and sodium oxide content than container glass, a lower silica, calcium oxide, aluminium oxide content. From the lower content of water-soluble ions in container glass comes its higher chemical durability against water, required for storage of beverages and food.
Soda–lime glass undergoes a steady increase in viscosity with decreasing temperature, permitting operations of increasing precision. The glass is formable into objects when it has a viscosity of 104 poises reached at a temperature around 900 °C; the glass is softened and undergoes steady deformation when viscosity is less than 108 poises, near 700 °C. Though hardened, soda–lime glass can nonetheless be annealed to remove internal stresses with about 15 minutes at 1014 poises, near 500 °C; the relationship between viscosity and temperature is logarithmic, with an Arrhenius equation dependent on the composition of the glass, but the activation energy increases at higher temperatures. The following table lists some physical properties of soda–lime glasses. Unless otherwise stated, the glass compositions and many experimentally determined properties are taken from one large study; those values marked in italic font have been interpolated from similar glass compositions due to the lack of experimental data.
Coefficient of restitution: 0.97 ± 0.01 Thermal conductivity: 0.7–1.3 W/ Hardness: 6 Knoop hardness: 585 kg/mm2 + 20 Glass batch calculation
Friedrich Otto Schott was a German chemist, glass technologist, the inventor of borosilicate glass. He was the son of Simon Schott. From 1870 to 1873 Schott studied chemical technology at the technical college in Aachen and at the universities of Würzburg and Leipzig, he attained a doctorate in glass chemistry at Friedrich Schiller University of Jena for his thesis “Contributions to the Theory and Practice of Glass Fabrication”. In 1879, Schott developed a new lithium-based glass. Schott shared this discovery with Dr Ernst Abbe, the catalyst for a long professional relationship between the two. In 1884, in association with Dr Ernst Abbe and Carl Zeiss, Otto founded Glastechnische Laboratorium Schott & Genossen in Jena, it was here, during the period 1887 through to 1893. Borosilicate glass is distinguished for its high tolerance to heat and a substantial resistance to thermal shock and resistance to degradation when exposed to chemicals. In 1926, Otto Schott retired from active work at Schott & Gen. Calculation of glass properties Works by or about Otto Schott at Internet Archive
The Middle East is a transcontinental region centered on Western Asia and Egypt. Saudi Arabia is geographically the largest Middle Eastern nation; the corresponding adjective is Middle Eastern and the derived noun is Middle Easterner. The term has come into wider usage as a replacement of the term Near East beginning in the early 20th century. Arabs, Persians and Azeris constitute the largest ethnic groups in the region by population. Arabs constitute the largest ethnic group in the region by a clear margin. Indigenous minorities of the Middle East include Jews, Assyrians, Copts, Lurs, Samaritans, Shabaks and Zazas. European ethnic groups that form a diaspora in the region include Albanians, Circassians, Crimean Tatars, Franco-Levantines, Italo-Levantines. Among other migrant populations are Chinese, Indians, Pakistanis, Pashtuns and sub-Saharan Africans; the history of the Middle East dates back to ancient times, with the importance of the region being recognized for millennia. Several major religions have their origins in the Middle East, including Judaism and Islam.
The Middle East has a hot, arid climate, with several major rivers providing irrigation to support agriculture in limited areas such as the Nile Delta in Egypt, the Tigris and Euphrates watersheds of Mesopotamia, most of what is known as the Fertile Crescent. Most of the countries that border the Persian Gulf have vast reserves of crude oil, with monarchs of the Arabian Peninsula in particular benefiting economically from petroleum exports; the term "Middle East" may have originated in the 1850s in the British India Office. However, it became more known when American naval strategist Alfred Thayer Mahan used the term in 1902 to "designate the area between Arabia and India". During this time the British and Russian Empires were vying for influence in Central Asia, a rivalry which would become known as The Great Game. Mahan realized not only the strategic importance of the region, but of its center, the Persian Gulf, he labeled the area surrounding the Persian Gulf as the Middle East, said that after Egypt's Suez Canal, it was the most important passage for Britain to control in order to keep the Russians from advancing towards British India.
Mahan first used the term in his article "The Persian Gulf and International Relations", published in September 1902 in the National Review, a British journal. The Middle East, if I may adopt a term which I have not seen, will some day need its Malta, as well as its Gibraltar. Naval force has the quality of mobility; the British Navy should have the facility to concentrate in force if occasion arise, about Aden and the Persian Gulf. Mahan's article was reprinted in The Times and followed in October by a 20-article series entitled "The Middle Eastern Question," written by Sir Ignatius Valentine Chirol. During this series, Sir Ignatius expanded the definition of Middle East to include "those regions of Asia which extend to the borders of India or command the approaches to India." After the series ended in 1903, The Times removed quotation marks from subsequent uses of the term. Until World War II, it was customary to refer to areas centered around Turkey and the eastern shore of the Mediterranean as the "Near East", while the "Far East" centered on China, the Middle East meant the area from Mesopotamia to Burma, namely the area between the Near East and the Far East.
In the late 1930s, the British established the Middle East Command, based in Cairo, for its military forces in the region. After that time, the term "Middle East" gained broader usage in Europe and the United States, with the Middle East Institute founded in Washington, D. C. in 1946, among other usage. The description Middle has led to some confusion over changing definitions. Before the First World War, "Near East" was used in English to refer to the Balkans and the Ottoman Empire, while "Middle East" referred to Iran, the Caucasus, Central Asia, Turkestan. In contrast, "Far East" referred to the countries of East Asia With the disappearance of the Ottoman Empire in 1918, "Near East" fell out of common use in English, while "Middle East" came to be applied to the re-emerging countries of the Islamic world. However, the usage "Near East" was retained by a variety of academic disciplines, including archaeology and ancient history, where it describes an area identical to the term Middle East, not used by these disciplines.
The first official use of the term "Middle East" by the United States government was in the 1957 Eisenhower Doctrine, which pertained to the Suez Crisis. Secretary of State John Foster Dulles defined the Middle East as "the area lying between and including Libya on the west and Pakistan on the east and Iraq on the North and the Arabian peninsula to the south, plus the Sudan and Ethiopia." In 1958, the State Department explained that the terms "Near East" and "Middle East" were interchangeable, defined the region as including only Egypt, Israel, Jordan, Saudi Arabia, Kuwait and Qatar. The Associated Press Styleboo
Leipzig is the most populous city in the federal state of Saxony, Germany. With a population of 581,980 inhabitants as of 2017, it is Germany's tenth most populous city. Leipzig is located about 160 kilometres southwest of Berlin at the confluence of the White Elster, Pleiße and Parthe rivers at the southern end of the North German Plain. Leipzig has been a trade city since at least the time of the Holy Roman Empire; the city sits at the intersection of the Via Regia and the Via Imperii, two important medieval trade routes. Leipzig was once one of the major European centers of learning and culture in fields such as music and publishing. Leipzig became a major urban center within the German Democratic Republic after the Second World War, but its cultural and economic importance declined. Events in Leipzig in 1989 played a significant role in precipitating the fall of communism in Central and Eastern Europe through demonstrations starting from St. Nicholas Church. Since the reunification of Germany, Leipzig has undergone significant change with the restoration of some historical buildings, the demolition of others, the development of a modern transport infrastructure.
Leipzig today is an economic centre, the most livable city in Germany, according to the GfK marketing research institution and has the second-best future prospects of all cities in Germany, according to HWWI and Berenberg Bank. Leipzig Zoo is one of the most modern zoos in Europe and ranks first in Germany and second in Europe according to Anthony Sheridan. Since the opening of the Leipzig City Tunnel in 2013, Leipzig forms the centrepiece of the S-Bahn Mitteldeutschland public transit system. Leipzig is listed as a Gamma World City, Germany's "Boomtown" and as the European City of the Year 2019. Leipzig has long been a major center for music, both classical as well as modern "dark alternative music" or darkwave genres; the Oper Leipzig is one of the most prominent opera houses in Germany. It was founded in 1693, making it the third oldest opera venue in Europe after La Fenice and the Hamburg State Opera. Leipzig is home to the University of Music and Theatre "Felix Mendelssohn Bartholdy", it was during a stay in this city that Friedrich Schiller wrote his poem "Ode to Joy".
The Leipzig Gewandhaus Orchestra, established in 1743, is one of the oldest symphony orchestras in the world. Johann Sebastian Bach is one among many major composers who lived in Leipzig; the name Leipzig is derived from the Slavic word Lipsk, which means "settlement where the linden trees stand". An older spelling of the name in English is Leipsic; the Latin name Lipsia was used. The name is cognate with Lipetsk in Liepāja in Latvia. In 1937 the Nazi government renamed the city Reichsmessestadt Leipzig. Since 1989 Leipzig has been informally dubbed "Hero City", in recognition of the role that the Monday demonstrations there played in the fall of the East German regime – the name alludes to the honorary title awarded in the former Soviet Union to certain cities that played a key role in the victory of the Allies during the Second World War; the common usage of this nickname for Leipzig up until the present is reflected, for example, in the name of a popular blog for local arts and culture, Heldenstadt.de.
More the city has sometimes been nicknamed the "Boomtown of eastern Germany", "Hypezig" or "The better Berlin" for being celebrated by the media as a hip urban centre for the vital lifestyle and creative scene with many startups. Leipzig was first documented in 1015 in the chronicles of Bishop Thietmar of Merseburg as urbs Libzi and endowed with city and market privileges in 1165 by Otto the Rich. Leipzig Trade Fair, started in the Middle Ages, has become an event of international importance and is the oldest surviving trade fair in the world. There are records of commercial fishing operations on the river Pleiße in Leipzig dating back to 1305, when the Margrave Dietrich the Younger granted the fishing rights to the church and convent of St Thomas. There were a number of monasteries in and around the city, including a Franciscan monastery after which the Barfußgäßchen is named and a monastery of Irish monks near the present day Ranstädter Steinweg; the foundation of the University of Leipzig in 1409 initiated the city's development into a centre of German law and the publishing industry, towards being the location of the Reichsgericht and the German National Library.
During the Thirty Years' War, two battles took place in Breitenfeld, about 8 kilometres outside Leipzig city walls. The first Battle of Breitenfeld took place in 1631 and the second in 1642. Both battles resulted in victories for the Swedish-led side. On 24 December 1701, an oil-fueled street lighting system was introduced; the city employed light guards who had to follow a specific schedule to ensure the punctual lighting of the 700 lanterns. The Leipzig region was the arena of the 1813 Battle of Leipzig between Napoleonic France and an allied coalition of Prussia, Russia and Sweden, it was the largest battle in Europe before the First World War and the coalition victory ended Napoleon's presence in Germany and would lead to his first exile on Elba. The Monument to the Battle of the Nations celebrating the centenary of this event was completed in 1913. In addition to stimulating German nationalism, the war had a major impact in mobilizing a civic spirit in numerous volunteer activities. Many volunteer militi
Potassium is a chemical element with symbol K and atomic number 19. It was first isolated from the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals. All of the alkali metals have a single valence electron in the outer electron shell, removed to create an ion with a positive charge – a cation, which combines with anions to form salts. Potassium in nature occurs only in ionic salts. Elemental potassium is a soft silvery-white alkali metal that oxidizes in air and reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, burning with a lilac-colored flame, it is found dissolved in sea water, is part of many minerals. Potassium is chemically similar to sodium, the previous element in group 1 of the periodic table, they have a similar first ionization energy, which allows for each atom to give up its sole outer electron. That they are different elements that combine with the same anions to make similar salts was suspected in 1702, was proven in 1807 using electrolysis.
Occurring potassium is composed of three isotopes, of which 40K is radioactive. Traces of 40K are found in all potassium, it is the most common radioisotope in the human body. Potassium ions are vital for the functioning of all living cells; the transfer of potassium ions across nerve cell membranes is necessary for normal nerve transmission. Fresh fruits and vegetables are good dietary sources of potassium; the body responds to the influx of dietary potassium, which raises serum potassium levels, with a shift of potassium from outside to inside cells and an increase in potassium excretion by the kidneys. Most industrial applications of potassium exploit the high solubility in water of potassium compounds, such as potassium soaps. Heavy crop production depletes the soil of potassium, this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production; the English name for the element potassium comes from the word "potash", which refers to an early method of extracting various potassium salts: placing in a pot the ash of burnt wood or tree leaves, adding water and evaporating the solution.
When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it potassium, which he derived from the word potash. The symbol "K" stems from kali, itself from the root word alkali, which in turn comes from Arabic: القَلْيَه al-qalyah "plant ashes". In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite, realized that "potash" was not a product of plant growth but contained a new element, which he proposed to call kali. In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium". In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol "K"; the English and French speaking countries adopted Davy and Gay-Lussac/Thénard's name Potassium, while the Germanic countries adopted Gilbert/Klaproth's name Kalium. The "Gold Book" of the International Union of Physical and Applied Chemistry has designated the official chemical symbol as K.
Potassium is the second least dense metal after lithium. It is a soft solid with a low melting point, can be cut with a knife. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray on exposure to air. In a flame test and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers. Neutral potassium atoms have 19 electrons, one more than the stable configuration of the noble gas argon; because of this and its low first ionization energy of 418.8 kJ/mol, the potassium atom is much more to lose the last electron and acquire a positive charge than to gain one and acquire a negative charge. This process requires so little energy that potassium is oxidized by atmospheric oxygen. In contrast, the second ionization energy is high, because removal of two electrons breaks the stable noble gas electronic configuration. Potassium therefore does not form compounds with the oxidation state of higher. Potassium is an active metal that reacts violently with oxygen in water and air.
With oxygen it forms potassium peroxide, with water potassium forms potassium hydroxide. The reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium; this reaction requires only traces of water. Because of the sensitivity of potassium to water and air, reactions with other elements are possible only in an inert atmosphere such as argon gas using air-free techniques. Potassium does not react with most hydrocarbons such as mineral kerosene, it dissolves in liquid ammonia, up to 480 g per 1000 g of ammonia at 0 °C. Depending on the concentration, the ammonia solutions are blue to yellow, their electrical conductivity is similar to that of liquid metals. In a pure solution, potassium reacts with ammonia to form KNH2, but this reaction is accelerated by minute amounts of transition metal s
Tempered or toughened glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering puts the outer surfaces into the interior into tension; such stresses cause the glass, when broken, to crumble into small granular chunks instead of splintering into jagged shards as plate glass does. The granular chunks are less to cause injury; as a result of its safety and strength, tempered glass is used in a variety of demanding applications, including passenger vehicle windows, shower doors, architectural glass doors and tables, refrigerator trays, mobile screen protectors, as a component of bulletproof glass, for diving masks, various types of plates and cookware. Tempered glass is thermally stronger than normal glass; the greater contraction of the inner layer during manufacturing induces compressive stresses in the surface of the glass balanced by tensile stresses in the body of the glass. For glass to be considered tempered, this compressive stress on the surface of the glass should be a minimum of 69 megapascals.
For it to be considered safety glass, the surface compressive stress should exceed 100 megapascals. As a result of the increased surface stress, if the glass is broken it only breaks into small circular pieces as opposed to sharp jagged shards; this characteristic makes tempered glass safe for high-pressure and explosion proof applications. It is this compressive stress; this is because annealed glass, which has no internal stress forms microscopic surface cracks, any applied tension gets magnified at the surface, reducing the applied tension needed to propagate the crack. Once it starts propagating, tension gets magnified more causing it to propagate at the speed of sound in the material. Annealed glass is fragile and breaks into irregular and sharp pieces. Any cutting or grinding must be done prior to tempering. Cutting and sharp impacts after tempering will cause the glass to fracture; the strain pattern resulting from tempering can be observed by viewing through an optical polarizer, such as a pair of polarizing sunglasses.
Tempered glass is used when strength, thermal resistance, safety are important considerations. Passenger vehicles, for example, have all three requirements. Since they are stored outdoors, they are subject to constant heating and cooling as well as dramatic temperature changes throughout the year. Moreover, they must withstand small impacts from road debris such as stones as well as automobile accidents; because large, sharp glass shards would present additional and unacceptable danger to passengers, tempered glass is used so that if broken, the pieces are blunt and harmless. The windscreen or windshield is instead made of laminated glass, which will not shatter into pieces when broken while side windows and the rear windshield are tempered glass. Other typical applications of tempered glass include: Balcony doors Athletic facilities Swimming pools Facades Shower doors and bathroom areas Exhibition areas and displays Computer towers or cases Tempered glass is used in buildings for unframed assemblies, structurally loaded applications, any other application that would become dangerous in the event of human impact.
Tempered and heat strengthened. Building codes in the United States require tempered or laminated glass in several situations including some skylights, near doorways and stairways, large windows, windows which extend close to floor level, sliding doors, fire department access panels, near swimming pools. Tempered glass is used in the home; some common household furniture and appliances that use tempered glass are frameless shower doors, glass table tops, replacement glass, glass shelves, cabinet glass and glass for fireplaces. "Rim-tempered" indicates that a limited area, such as the rim of the glass or plate, is tempered and is popular in food service. However, there are specialist manufacturers that offer a tempered/toughened drinkware solution that can bring increased benefits in the form of strength and thermal shock resistance. In some countries these products are specified in venues that require increased performance levels or have a requirement for a safer glass due to intense usage. Tempered glass has seen increased usage in bars and pubs in the United Kingdom and Australia, to prevent broken glass being used as a weapon.
Tempered glass products can be found in hotels and restaurants to reduce breakages and increase safety standards. Some forms of tempered glass are used for baking. Manufacturers and brands include Glasslock, Pyrex and Arc International. Most touchscreen mobile devices use some form of toughened glass, as do some aftermarket screen protectors for these devices. Tempered glass can be made from annealed glass via a thermal tempering process; the glass is placed onto a roller table, taking it through a furnace that heats it well above its transition temperature of 564 °C to around 620 °C. The glass is rapidly cooled with forced air drafts while the inner portion remains free to flow for a short time. An alternative chemical toughening process involves forcing a surface layer of glass at least 0.1 mm thick into compression by ion exchange of the sodium ions in the glass surface with potassium ions, by immersion of the glass into a bath of molten potassium nitrate. Chemical toughening results in increased toughness compared with thermal tempering and can be appl