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Silex
Silex is any of various forms of ground stone. In modern contexts the word refers to a finely ground, nearly pure form of silica or silicate. In the late 16th century, it meant powdered or ground up "flints" (i.e. stones, generally meaning the class of "hard rocks") It was later used in 1787 when describing experiments in a published paper by Antoine Lavoisier where such earths are mentioned as the source of his isolation of the element silicon. ''Silex'' is now most commonly used to describe finely ground silicates used as pigments in paint. Archaic and foreign uses * The word "silex" was previously used to refer to flint and chert and sometimes other hard rocks. * In Latin "silex" originally referred to any hard rock, although now it often refers specifically to flint.Vitruvius ''De Arch'' 1.5.8.5 http://latin.packhum.org/loc/1056/1/9/4230-4235 * In many Latin languages, "silex" or a similar word is used to refer to flint. Although the modern English word "silex" has the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as a synthetic product. Notable examples include fused quartz, fumed silica, silica gel, opal and aerogels. It is used in structural materials, microelectronics (as an Insulator (electricity), electrical insulator), and as components in the food and pharmaceutical industries. Structure In the majority of silicates, the silicon atom shows tetrahedral coordination geometry, tetrahedral coordination, with four oxygen atoms surrounding a central Si atomsee 3-D Unit Cell. Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. In contrast, CO2 is a linear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicate
In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate. The name "silicate" is sometimes extended to any anions containing silicon, even if they do not fit the general formula or contain other atoms besides oxygen; such as hexafluorosilicate .Most commonly, silicates are encountered as silicate minerals. For diverse manufacturing, technological, and artistic needs, silicates are versatile materials, both natural (such as granite, gravel, and garnet) and artificial (such as Portland cement, ceramics, glass, and waterglass). Structural principles In all silicates, silicon atom occupies the center of an idealized tetrahedron whose corner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flint
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Flint was widely used historically to make stone tools and start fires. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.''The Flints from Portsdown Hill'' Inside the nodule, flint is usually dark grey, black, green, white or brown in colour, and often has a glassy or waxy appearance. A thin layer on the outside of the nodules is usually different in colour, typically white and rough in texture. The nodules can often be found along s and |
Antoine Lavoisier
Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794), When reduced without charcoal, it gave off an air which supported respiration and combustion in an enhanced way. He concluded that this was just a pure form of common air and that it was the air itself "undivided, without alteration, without decomposition" which combined with metals on calcination. After returning from Paris, Priestley took up once again his investigation of the air from mercury calx. His results now showed that this air was not just an especially pure form of common air but was "five or six times better than common air, for the purpose of respiration, inflammation, and ... every other use of common air". He called the air dephlogisticated air, as he thought it was common air deprived of its phlogiston. Since it was therefore in a state to absorb a much greater quantity of phlogiston given off by burning bodies and respiring animals, the greatly enhanced combustion of substances and the greater e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form. Its oxides form a family of anions known as silicates. Its melting and boiling points of 1414 °C and 3265 °C, respectively, are the second highest among all the metalloids and nonmetals, being surpassed only by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is widely distributed in space in cosmic dusts, planetoids, and planets as various forms of silicon dioxide ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paint
Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many colors—and in many different types. Paint is typically stored, sold, and applied as a liquid, but most types dry into a solid. Most paints are either oil-based or water-based and each has distinct characteristics. For one, it is illegal in most municipalities to discard oil-based paint down household drains or sewers. Clean-up solvents are also different for water-based paint than they are for oil-based paint. Water-based paints and oil-based paints will cure differently based on the outside ambient temperature of the object being painted (such as a house.) Usually, the object being painted must be over , although some manufacturers of external paints/primers claim they can be applied when temperatures are as low as . History Paint was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chert
Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a precipitation (chemistry), chemical precipitate or a diagenesis, diagenetic replacement, as in petrified wood. Chert is typically composed of the petrified remains of siliceous ooze, the biogenic sediment that covers large areas of the deep ocean floor, and which contains the silicon skeletal remains of diatoms, Dictyochales, silicoflagellates, and radiolarians. Precambrian cherts are notable for the presence of fossil cyanobacteria. In addition to Micropaleontology, microfossils, chert occasionally contains macrofossils. However, some chert is devoid of any fossils. Chert varies greatly in color (from white to black), but most often manifests as gray, brown, grayish brown and light green to rusty redW.L. Roberts, T.J. Campbell, G.R. Rapp Jr. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitruvius
Vitruvius (; c. 80–70 BC – after c. 15 BC) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work entitled ''De architectura''. He originated the idea that all buildings should have three attributes: , , and ("strength", "utility", and "beauty"). These principles were later widely adopted in Roman architecture. His discussion of perfect proportion in architecture and the human body led to the famous Renaissance drawing of the ''Vitruvian Man'' by Leonardo da Vinci. Little is known about Vitruvius' life, but by his own descriptionDe Arch. Book 1, preface. section 2. he served as an artilleryman, the third class of arms in the Roman military offices. He probably served as a senior officer of artillery in charge of ''doctores ballistarum'' (artillery experts) and ''libratores'' who actually operated the machines. As an army engineer he specialized in the construction of ''ballista'' and '' scorpio'' artillery war machines for sieges. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Romance Languages
The Romance languages, sometimes referred to as Latin languages or Neo-Latin languages, are the various modern languages that evolved from Vulgar Latin. They are the only extant subgroup of the Italic languages in the Indo-European language family. The five most widely spoken Romance languages by number of native speakers are Spanish (489 million), Portuguese (283 million), French (77 million), Italian (67 million) and Romanian (24 million), which are all national languages of their respective countries of origin. By most measures, Sardinian and Italian are the least divergent from Latin, while French has changed the most. However, all Romance languages are closer to each other than to classical Latin. There are more than 900 million native speakers of Romance languages found worldwide, mainly in the Americas, Europe, and parts of Africa. The major Romance languages also have many non-native speakers and are in widespread use as linguae francae.M. Paul Lewis,Summary by l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
False Friends
In linguistics, a false friend is either of two words in different languages that look or sound similar, but differ significantly in meaning. Examples include English ''embarrassed'' and Spanish ''embarazada'' 'pregnant'; English ''parents'' versus Portuguese ''parentes'' and Italian ''parenti'' (both meaning 'relatives'); English ''demand'' and French ''demander'' 'ask'; and English ''gift'', German ''Gift'' 'poison', and Norwegian ''gift'' 'married'. The term was introduced by a French book, ''Les faux amis: ou, Les trahisons du vocabulaire anglais'' (''False friends, or, the betrayals of English vocabulary''), published in 1928. As well as producing completely false friends, the use of loanwords often results in the use of a word in a restricted context, which may then develop new meanings not found in the original language. For example, ''angst'' means 'fear' in a general sense (as well as 'anxiety') in German, but when it was borrowed into English in the context of psyc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FK Sileks
FK Sileks ( mk, ФК Силекс) is a football club based in Kratovo, North Macedonia who play in the Macedonian First League. History The club was founded in 1965. Sileks biggest accomplishment in 90s came in the Yugoslav Cup where they reached the quarter-final. It was a remarkable achievement considering they defeated both Sarajevo teams, FK Željezničar and FK Sarajevo in back to back rounds. Since the formation of the First Macedonian Football League, they played at top level from the start until their relegation in 2013. Their biggest success happened during the 90s, when they won three league titles (including a record five time runners-up) and two national cups. *After 24 years finally Silkes managed to win the Macedonian cup. Beating Akademia Pandev on PK 3-2 after scoreless draw 0-0 in 120 mins extra time. Home ground Stadium Sileks (Macedonian: Градски стадион Силекс-Кратово) is a multi-purpose stadium in Kratovo, North Macedonia. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kratovo, North Macedonia
Kratovo ( mk, Кратово ) is a small town in North Macedonia. It is the seat of Kratovo Municipality. It lies on the western slopes of Mount Osogovo at an altitude of above sea level. Having a mild and pleasant climate, it is located in the crater of an extinct volcano. It is known for its bridges and towers. History Early Middle Ages In the Roman period there was a settlement called ''Tranatura'' located within the modern city municipality. There was a mine nearby and the town was the seat of local authorities. No remains of the settlement has been found, however, remnants of Roman fortification were found on Zdravče kamen hill above the town. Byzantine and Bulgarian Empires ruled the area subsequently. Late Middle Ages In 1282 Kratovo became part of the Kingdom of Serbia. In all probability the wealth of the town came from its mines. Saxon miners and Croatian merchants from Dubrovnik who already had worked in other parts of Macedonia settled here. The town was first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
