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Three-phase Firing
Three-phase firing (or three-step firing) or iron reduction technique is a firing technique used in ancient Greek pottery production, specifically for painted vases. Already vessels from the Bronze Age feature the colouring typical of the technique, with yellow, orange or red clay and brown or red decoration. By the 7th century BC, the process was perfected in mainland Greece (Corinth and Athens) enabling the production of extremely shiny black- slipped surfaces, which led to the development of the black-figure and red-figure techniques, which dominated Greek vase painting until about 300 BC. The conventional view, developed in modern times in view of a lack of contemporary accounts, was that painted Greek pottery received a single firing, after the shaped pot had been dried leather-hard and then painted. But the firing had three phases, designed to create the intended colours. Sometimes further painting in other colours was added after firing, especially in white-ground and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plaque Penteskouphia MNB2858
Plaque may refer to: Commemorations or awards * Commemorative plaque, a plate, usually fixed to a wall or other vertical surface, meant to mark an event, person, etc. * Memorial Plaque (medallion), issued to next-of-kin of dead British military personnel after World War I * Plaquette, a small plaque in bronze or other materials Science and healthcare * Amyloid plaque * Atheroma or atheromatous plaque, a buildup of deposits within the wall of an artery * Dental plaque, a biofilm that builds up on teeth * A broad papule, a type of cutaneous condition * Pleural plaque, associated with mesothelioma, cancer often caused by exposure to asbestos * Senile plaques, an extracellular protein deposit in the brain implicated in Alzheimer's disease * Skin plaque, a plateau-like lesion that is greater in its diameter than in its depth * Viral plaque, a visible structure formed by virus propagation within a cell culture Other uses * Plaque, a rectangular casino token See also * * * Builder's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitrification
Vitrification (, via French ') is the full or partial transformation of a substance into a glass, that is to say, a non- crystalline or amorphous solid. Glasses differ from liquids structurally and glasses possess a higher degree of connectivity with the same Hausdorff dimensionality of bonds as crystals: dimH = 3. In the production of ceramics, vitrification is responsible for their impermeability to water. Vitrification is usually achieved by heating materials until they liquify, then cooling the liquid, often rapidly, so that it passes through the glass transition to form a glassy solid. Certain chemical reactions also result in glasses. In terms of chemistry, vitrification is characteristic for amorphous materials or disordered systems and occurs when bonding between elementary particles (atoms, molecules, forming blocks) becomes higher than a certain threshold value. Thermal fluctuations break the bonds; therefore, the lower the temperature, the higher the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Bond
In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently bonded to a more Electronegativity, electronegative donor atom or group (Dn), interacts with another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Unlike simple Dipole–dipole attraction, dipole–dipole interactions, hydrogen bonding arises from charge transfer (nB → σ*AH), Atomic orbital, orbital interactions, and quantum mechanical Delocalized electron, delocalization, making it a resonance-assisted interaction rather than a mere electrostatic attraction. The general notation for hydrogen bonding is Dn−H···Ac, where the solid line represents a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond. The most frequent donor and acceptor atoms are nitrogen (N), oxyg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calgon
Calgon is an American brand of bath and beauty products, owned by PDC Brands. Early history The original product consisted of powdered sodium hexametaphosphate (amorphous sodium polyphosphate), which, in water, would complex with ambient calcium ions and certain other cations—preventing formation of unwanted salts and interference by those cations with the actions of soap or other detergents. Its name, a portmanteau derived from the phrase "calcium gone",Walker, Andrea K. (June 22, 2010)"Calgon, take me away...again" ''The Baltimore Sun''. was originally promoted for general use in bathing and cleaning. It gave rise to derivative products, which have diverged from the original composition. Today, Calgon water softener contains the active ingredient sodium citrate, and the now discontinued powder used zeolite and polycarboxylate, all of which are less problematic in wastewater treatment than phosphates. Companies The brand has its origin in Calgon, Inc. of Pittsburgh, Penn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphosphate
A polyphosphate is a Salt (chemistry), salt or ester of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic (also called, ring) structures. In biology, the polyphosphate esters adenosine diphosphate, ADP and adenosine triphosphate, ATP are involved in energy storage. A variety of polyphosphates find application in mineral sequestration in municipal waters, generally being present at 1 to 5 ppm. guanosine triphosphate, GTP, cytidine triphosphate, CTP, and uridine triphosphate, UTP are also nucleotides important in the protein synthesis, lipid synthesis, and carbohydrate metabolism, respectively. Polyphosphates are also used as food additives, marked E452. Structure Image:Triphosphorsäure.svg, Structure of triphosphoric acid Image:Polyphosphoric acid.svg, Polyphosphoric acid Image:Trimetaphosphat.svg, Cyclic trimetaphosphate Image:Adenosindiphosphat protoni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potash
Potash ( ) includes various mined and manufactured salts that contain potassium in water- soluble form.Potash , USGS 2008 Minerals Yearbook The name derives from ''pot ash'', plant ashes or soaked in water in a pot, the primary means of manufacturing potash before the Industrial Era. The word '''' is derived from ''potash''. Potash is produced worldwide in amounts exceeding 71.9 million |
Ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pungent smell. It is widely used in fertilizers, refrigerants, explosives, cleaning agents, and is a precursor for numeous chemicals. Biologically, it is a common nitrogenous waste, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to fertilisers. Around 70% of ammonia produced industrially is used to make fertilisers in various forms and composition, such as urea and diammonium phosphate. Ammonia in pure form is also applied directly into the soil. Ammonia, either directly or indirectly, is also a building block for the synthesis of many chemicals. In many countries, it is classified as an List of extremely hazardous substances, extremely hazardous substance. Ammonia is toxic, cau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caustic Soda
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base and alkali that decomposes lipids and proteins at ambient temperatures and at high concentrations may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates . The monohydrate crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students. Sodium hydroxide is used in many industries: in the making of wood pulp and paper, textiles, drinking w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dionysos
In ancient Greek religion and myth, Dionysus (; ) is the god of wine-making, orchards and fruit, vegetation, fertility, festivity, insanity, ritual madness, religious ecstasy, and theatre. He was also known as Bacchus ( or ; ) by the Greeks (a name later adopted by the Romans) for a frenzy he is said to induce called ''baccheia''. His wine, music, and ecstatic dance were considered to free his followers from self-conscious fear and care, and subvert the oppressive restraints of the powerful. His ''thyrsus'', a fennel-stem sceptre, sometimes wound with ivy and dripping with honey, is both a beneficent wand and a weapon used to destroy those who oppose his cult and the freedoms he represents. Those who partake of his mysteries are believed to become possessed and empowered by the god himself. His origins are uncertain, and his cults took many forms; some are described by ancient sources as Thracian, others as Greek. In Orphism, he was variously a son of Zeus and Persephone; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staatliche Antikensammlungen
The Staatliche Antikensammlungen (, ''State Collections of Antiquities'') is a museum in Munich's Kunstareal holding Bavaria's collections of antiquities from Ancient Greek art, Greece, Etruscan art, Etruria and Roman art, Rome, though the sculpture collection is located in the Glyptothek opposite, and works created ''in'' Bavaria are on display in Bavarian State Archaeological Collection, a separate museum. Art of ancient Egypt, Ancient Egypt also has Staatliche Sammlung für Ägyptische Kunst, its own museum. History of the building The Neoclassical architecture, neo-classical building in Königsplatz, Munich, Königsplatz with Corinthian order, Corinthian columns was established in 1848 as a counterpart to the ''Glyptothek'' opposite, and commissioned by King Ludwig I of Bavaria. The architect was Georg Friedrich Ziebland. From 1869 to 1872 the building already housed the royal antiquarium. Later, the Munich Secession resided here from 1898 to 1912. From 1919 the building conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exekias
Exekias (, ''Exēkías'') was an ancient Greek vase painter and potter who was active in Athens between roughly 545 BC and 530 BC. Exekias worked mainly in the black-figure technique, which involved the painting of scenes using a clay slip that fired to black, with details created through incision. Exekias is regarded by art historians as an artistic visionary whose masterful use of incision and psychologically sensitive compositions mark him as one of the greatest of all Attic vase painters. The Andokides painter and the Lysippides Painter are thought to have been students of Exekias. Background The works of Exekias are distinguished by their innovative compositions, precise draughtsmanship, and subtle psychological characterization, all of which transcend the inherent challenges of the black-figure technique. John Boardman, the eminent historian of Greek art, described Exekias' style as follows: "The hallmark of his style is a near statuesque dignity which brings vase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sintering
Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms/molecules in the sintered material diffuse across the boundaries of the particles, fusing the particles together and creating a solid piece. Since the sintering temperature does not have to reach the melting point of the material, sintering is often chosen as the shaping process for materials with extremely high melting points, such as tungsten and molybdenum. The study of sintering in metallurgy, metallurgical powder-related processes is known as powder metallurgy. An example of sintering can be observed when ice cubes in a glass of water adhere to each other, which is driven by the temperature difference between the water and the ice. Examples of pressure-driven sintering are the compacting of snowfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
