|
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 H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plaque Penteskouphia MNB2858
Plaque may refer to: Commemorations or awards * Commemorative plaque, a plate or tablet fixed to a wall 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 plate * Plac (other) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitrification
Vitrification (from Latin ''vitreum'', "glass" via French ''vitrifier'') is the full or partial transformation of a substance into a glass, that is to say, a non-crystalline 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 its impermeability to water. Vitrification is usually achieved by heating materials until they liquidize, 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 low ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Bond
In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Such an interacting system is generally denoted , where the solid line denotes a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond. The most frequent donor and acceptor atoms are the second-row elements nitrogen (N), oxygen (O), and fluorine (F). Hydrogen bonds can be intermolecular (occurring between separate molecules) or intramolecular (occurring among parts of the same molecule). The energy of a hydrogen bond depends on the geometry, the environment, and the nature of the specific donor and acceptor atoms and can vary between 1 and 40 kcal/mol. This makes them somewhat stronger than a van der Waals interaction, and weaker than fully covalent ... [...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 was a portmanteau derived from the phrase "calcium gone".Walker, Andrea K. (June 22, 2010)"Calgon, take me away...again" ''The Baltimore Sun''. 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 brands have their origin in Calgon, Inc. of Pittsburgh, Penn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphosphate
Polyphosphates are salts or esters of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic ring structures. In biology, the polyphosphate esters ADP and 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. GTP, CTP, and 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 protoniert.svg, Adenosine diphosphate (ADP) The structure of tripolyphosphoric acid illustrates the principles which define the structures of polyphosp ... [...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 . The word '''' is derived from ''potash''. Potash is produced worldwide in amounts exceeding 90 million |
Ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous waste, particularly among aquatic organisms, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to 45% of the world's food and fertilizers. Around 70% of ammonia 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 pharmaceutical products and is used in many commercial cleaning products. It is mainly collected by downward displacement of both air and water. Although common in nature—both terrestrially and in the outer planets of the Solar System—and in wide use, ammonia is both caust ... [...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 NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and 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 manufacture of pulp and paper, textiles, drinking water, soaps and de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dionysos
In ancient Greek religion and myth, Dionysus (; grc, Διόνυσος ) is the god of the grape-harvest, winemaking, orchards and fruit, vegetation, fertility, insanity, ritual madness, religious ecstasy, festivity, and theatre. The Romans called him Bacchus ( or ; grc, Βάκχος ) for a frenzy he is said to induce called ''bakkheia''. As Dionysus Eleutherios ("the liberator"), his wine, music, and ecstatic dance 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 Orphic religion, he was ... [...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 Greece, Etruria and Rome, though the sculpture collection is located in the opposite Glyptothek and works created ''in'' Bavaria are on display in a separate museum. Ancient Egypt also has its own museum. History of the building The neo-classical building at Königsplatz with Corinthian columns was established in 1848 as counterpart to the opposite ''Glyptothek'' and commissioned by the Bavarian King Ludwig I. The architect was Georg Friedrich Ziebland. Already from 1869 to 1872 the building housed the royal antiquarium before the Munich Secession resided here from 1898 to 1912. From 1919 the building contained the New State Gallery. The museum building was severely damaged by bombing in World War II but was reconstructed and reopened to the public in the late 1960s to display the State Collection of Antiques. Collecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exekias
Exekias ( grc, Ἐξηκίας, ''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 dignit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sintering
Clinker nodules produced by 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 in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because 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 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 compact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
-3D-balls.png "Click for more on -> Ammonia")
