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130-615: Magatama ( 勾玉 , less frequently 曲玉 ) are curved, comma -shaped beads that appeared in prehistoric Japan from the Final Jōmon period through the Kofun period , approximately 1000 BCE to the 6th century CE. The beads, also described as "jewels", were made of primitive stone and earthen materials in the early period, but by the end of the Kofun period were made almost exclusively of jade . Magatama originally served as decorative jewelry, but by
260-410: A kofun from the final phase of the Kofun period, and is possibly from a ruler associated with the imperial family. The kofun is 25 metres (82 ft) high and shows evidence of being surrounded by a moat . Among the very large number of funerary objects were high-quality weapons, including swords, 10 mirrors, and a necklace of jadeite magatama , agate cylinders, and glass beads used to make
390-620: A magatama was discovered in its stomach. This magatama was presented to Suinin, who enshrined it at Isonokami Shrine, where it is said to presently reside. A similar practice is described again in the Nihon Shoki during the reign of the Emperor Chūai . Chūai made an inspection trip to the Tsukushi, or Kyūshū , and was presented with an enormous sakaki tree hung with magatama as well as other sacred objects. A noted magatama
520-412: A magatama -style necklace. Archaeologists and historians are unable yet to explain what the origins of magatama forms are, or whether these forms can be traced back to one convergent source. A number of explanations have been suggested, including: The Kojiki and Nihon Shoki , completed in the 8th century, have numerous references to magatama . They appear in the first chapter of
650-405: A glass (or vitreous solid) is a non-crystalline solid formed by rapid melt quenching . However, the term "glass" is often defined in a broader sense, to describe any non-crystalline ( amorphous ) solid that exhibits a glass transition when heated towards the liquid state. Glass is an amorphous solid . Although the atomic-scale structure of glass shares characteristics of the structure of
780-508: A guild , the Tamatsukuri-be, was active from the Yayoi period. An existing jewel at the shrine is said to have great spiritual power. Magatama appear on all sorts of implements of the present-day temple, including amulets , roof tiles , and lanterns. The inari female fox at the gate of a subshrine of Tamatsukuri Inari Shrine wears a necklace of magatama . The shrine has an exhibit on
910-436: A supercooled liquid , glass exhibits all the mechanical properties of a solid. As in other amorphous solids , the atomic structure of a glass lacks the long-range periodicity observed in crystalline solids . Due to chemical bonding constraints, glasses do possess a high degree of short-range order with respect to local atomic polyhedra . The notion that glass flows to an appreciable extent over extended periods well below
1040-462: A tensor . In representing large numbers, from the right side to the left, English texts usually use commas to separate each group of three digits in front of the decimal. This is almost always done for numbers of six or more digits, and often for four or five digits but not in front of the number itself. However, in much of Europe, Southern Africa and Latin America, periods or spaces are used instead;
1170-809: A turquoise colour in glass, in contrast to copper(I) oxide (Cu 2 O) which gives a dull red-brown colour. Soda–lime sheet glass is typically used as a transparent glazing material, typically as windows in external walls of buildings. Float or rolled sheet glass products are cut to size either by scoring and snapping the material, laser cutting , water jets , or diamond-bladed saw. The glass may be thermally or chemically tempered (strengthened) for safety and bent or curved during heating. Surface coatings may be added for specific functions such as scratch resistance, blocking specific wavelengths of light (e.g. infrared or ultraviolet ), dirt-repellence (e.g. self-cleaning glass ), or switchable electrochromic coatings. Structural glazing systems represent one of
1300-562: A burial from the Kisami-Araida area of Shimoda, Shizuoka also revealed clay reproductions of magatama used as effigies. The excavation of the Ubusuna Kofun in Kyōtango , Kyoto yielded two fully intact magatama necklaces of jade and agate, with segments between 1.7 and 5.1 centimetres (0.67 and 2.01 in) in length. The large Muro Miyayama Kofun of Katsuragi, Nara , on
1430-448: A class of magical Relics with the ability to store magic sequences. In Blue Seed , magatama are used as vessels to contain mitama which bestow power to those implanted with them. The series' plot is based on the Izumo cycle from Japanese mythology. In Sailor Moon , Sailor Uranus' Space Sword, Sailor Neptune's Deep Aqua Mirror, and Sailor Pluto's Garnet Orb are based on each item. In
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#17328798224921560-485: A clear "ring" sound when struck. However, lead glass cannot withstand high temperatures well. Lead oxide also facilitates the solubility of other metal oxides and is used in coloured glass. The viscosity decrease of lead glass melt is very significant (roughly 100 times in comparison with soda glass); this allows easier removal of bubbles and working at lower temperatures, hence its frequent use as an additive in vitreous enamels and glass solders . The high ionic radius of
1690-489: A comma and no conjunction (as in "It is nearly half past five, we cannot reach town before dark." ) is known as a comma splice and is sometimes considered an error in English; in most cases a semicolon should be used instead. A comma splice should not be confused, though, with the literary device called asyndeton , in which coordinating conjunctions are purposely omitted for a specific stylistic effect. A much debated comma
1820-520: A comma before quotations unless one would occur anyway. Thus, they would write Mr. Kershner says "You should know how to use a comma." When a date is written as a month followed by a day followed by a year, a comma separates the day from the year: December 19, 1941. This style is common in American English. The comma is used to avoid confusing consecutive numbers: December 19 1941. Most style manuals, including The Chicago Manual of Style and
1950-461: A comma may prevent ambiguity: The serial comma does not eliminate all confusion. Consider the following sentence: As a rule of thumb , The Guardian Style Guide suggests that straightforward lists ( he ate ham, eggs and chips ) do not need a comma before the final "and", but sometimes it can help the reader ( he ate cereal, kippers, bacon, eggs, toast and marmalade, and tea ). The Chicago Manual of Style and other academic writing guides require
2080-533: A comma, called the serial comma , is one of the most disputed linguistic or stylistic questions in English: The serial comma is used much more often, usually routinely, in the United States. A majority of American style guides mandate its use, including The Chicago Manual of Style , Strunk and White 's classic The Elements of Style and the U.S. Government Publishing Office 's Style Manual . Conversely,
2210-413: A comma. Using commas to offset certain adverbs is optional, including then , so , yet , instead , and too (meaning also ). Commas are often used to enclose parenthetical words and phrases within a sentence (i.e., information that is not essential to the meaning of the sentence). Such phrases are both preceded and followed by a comma, unless that would result in a doubling of punctuation marks or
2340-440: A common rule of thumb is that the function of a comma is generally performed by a pause . In this article, ⟨x⟩ denotes a grapheme (writing) and /x/ denotes a phoneme (sound). The development of punctuation is much more recent than the alphabet. In the 3rd century BC, Aristophanes of Byzantium invented a system of single dots ( théseis ) at varying levels, which separated verses and indicated
2470-401: A cool day" parenthetical: As more phrases are introduced, ambiguity accumulates, but when commas separate each phrase, the phrases clearly become modifiers of just one thing. In the second sentence below, that thing is the walk : A comma is used to separate coordinate adjectives (i.e., adjectives that directly and equally modify the following noun). Adjectives are considered coordinate if
2600-437: A cut-off piece, specifically in grammar , a short clause . A comma-shaped mark is used as a diacritic in several writing systems and is considered distinct from the cedilla . In Byzantine and modern copies of Ancient Greek , the " rough " and " smooth breathings " ( ἁ, ἀ ) appear above the letter. In Latvian , Romanian , and Livonian , the comma diacritic appears below the letter, as in ș . In spoken language ,
2730-443: A green tint in thick sections. Manganese dioxide (MnO 2 ), which gives glass a purple colour, may be added to remove the green tint given by FeO. FeO and chromium(III) oxide (Cr 2 O 3 ) additives are used in the production of green bottles. Iron (III) oxide , on the other-hand, produces yellow or yellow-brown glass. Low concentrations (0.025 to 0.1%) of cobalt oxide (CoO) produce rich, deep blue cobalt glass . Chromium
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#17328798224922860-448: A hole suitable to attach to a string. These first appear in the Kofun period. Also in the Kofun period, magatama appear on necklaces, with several magatama set between bored cylinders . Archeological remains show evidence of similar ankle bracelets, but they are less common. Clay haniwa funerary objects of the Kofun period commonly depict people wearing the necklaces and ankle bracelets. Examples of stone magatama from
2990-408: A human timescale. Silicon dioxide (SiO 2 ) is a common fundamental constituent of glass. Fused quartz is a glass made from chemically pure silica. It has very low thermal expansion and excellent resistance to thermal shock , being able to survive immersion in water while red hot, resists high temperatures (1000–1500 °C) and chemical weathering, and is very hard. It is also transparent to
3120-405: A lighter alternative to traditional glass. Molecular liquids, electrolytes , molten salts , and aqueous solutions are mixtures of different molecules or ions that do not form a covalent network but interact only through weak van der Waals forces or transient hydrogen bonds . In a mixture of three or more ionic species of dissimilar size and shape, crystallization can be so difficult that
3250-561: A long period at a temperature just insufficient to cause fusion. In this way, the crystalline, devitrified material, known as Réaumur's glass porcelain is produced. Although generally transparent to visible light, glasses may be opaque to other wavelengths of light . While silicate glasses are generally opaque to infrared wavelengths with a transmission cut-off at 4 μm, heavy-metal fluoride and chalcogenide glasses are transparent to infrared wavelengths of 7 to 18 μm. The addition of metallic oxides results in different coloured glasses as
3380-482: A mass of hot semi-molten glass, inflating it into a bubble using a hollow blowpipe, and forming it into the required shape by blowing, swinging, rolling, or moulding. While hot, the glass can be worked using hand tools, cut with shears, and additional parts such as handles or feet attached by welding. Flat glass for windows and similar applications is formed by the float glass process, developed between 1953 and 1957 by Sir Alastair Pilkington and Kenneth Bickerstaff of
3510-473: A miniature filled-in figure 9 placed on the baseline . In many typefaces it is the same shape as an apostrophe or single closing quotation mark ’ . The comma is used in many contexts and languages , mainly to separate parts of a sentence such as clauses , and items in lists mainly when there are three or more items listed. The word comma comes from the Greek κόμμα ( kómma ), which originally meant
3640-453: A non-crystalline intergranular phase of grain boundaries . Glass-ceramics exhibit advantageous thermal, chemical, biological, and dielectric properties as compared to metals or organic polymers. The most commercially important property of glass-ceramics is their imperviousness to thermal shock. Thus, glass-ceramics have become extremely useful for countertop cooking and industrial processes. The negative thermal expansion coefficient (CTE) of
3770-494: A number of functions in English writing. It is used in generally similar ways in other languages, particularly European ones, although the rules on comma usage – and their rigidity – vary from language to language. Commas are placed between items in lists, as in They own a cat, a dog, two rabbits, and seven mice. Whether the final conjunction, most frequently and , should be preceded by
3900-401: A plastic resin with glass fibres . It is made by melting glass and stretching the glass into fibres. These fibres are woven together into a cloth and left to set in a plastic resin. Fibreglass has the properties of being lightweight and corrosion resistant and is a good insulator enabling its use as building insulation material and for electronic housing for consumer products. Fibreglass
4030-462: A refractive index of 1.4 to 2.4, and an Abbe number (which characterises dispersion) of 15 to 100. The refractive index may be modified by high-density (refractive index increases) or low-density (refractive index decreases) additives. Glass transparency results from the absence of grain boundaries which diffusely scatter light in polycrystalline materials. Semi-opacity due to crystallization may be induced in many glasses by maintaining them for
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4160-412: A spinning metal disk. Several alloys have been produced in layers with thicknesses exceeding 1 millimetre. These are known as bulk metallic glasses (BMG). Liquidmetal Technologies sells several zirconium -based BMGs. Batches of amorphous steel have also been produced that demonstrate mechanical properties far exceeding those found in conventional steel alloys. Experimental evidence indicates that
4290-435: A structural analogue of silica, fluoride , aluminate , phosphate , borate , and chalcogenide glasses) have physicochemical properties useful for their application in fibre-optic waveguides in communication networks and other specialised technological applications. Silica-free glasses may often have poor glass-forming tendencies. Novel techniques, including containerless processing by aerodynamic levitation (cooling
4420-413: A structurally metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase. Glass is sometimes considered to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume , entropy and enthalpy are discontinuous through
4550-518: A wider spectral range than ordinary glass, extending from the visible further into both the UV and IR ranges, and is sometimes used where transparency to these wavelengths is necessary. Fused quartz is used for high-temperature applications such as furnace tubes, lighting tubes, melting crucibles, etc. However, its high melting temperature (1723 °C) and viscosity make it difficult to work with. Therefore, normally, other substances (fluxes) are added to lower
4680-464: A word, or a group of words, has been omitted, as in The cat was white; the dog, brown. (Here the comma replaces was .) Commas are placed before, after, or around a noun or pronoun used independently in speaking to some person, place, or thing: In his 1785 essay An Essay on Punctuation , Joseph Robertson advocated a comma between the subject and predicate of long sentences for clarity; however, this usage
4810-418: Is 3.25 × 10 /°C as compared to about 9 × 10 /°C for a typical soda–lime glass ). They are, therefore, less subject to stress caused by thermal expansion and thus less vulnerable to cracking from thermal shock . They are commonly used for e.g. labware , household cookware , and sealed beam car head lamps . The addition of lead(II) oxide into silicate glass lowers the melting point and viscosity of
4940-552: Is a common volcanic glass with high silica (SiO 2 ) content formed when felsic lava extruded from a volcano cools rapidly. Impactite is a form of glass formed by the impact of a meteorite , where Moldavite (found in central and eastern Europe), and Libyan desert glass (found in areas in the eastern Sahara , the deserts of eastern Libya and western Egypt ) are notable examples. Vitrification of quartz can also occur when lightning strikes sand , forming hollow, branching rootlike structures called fulgurites . Trinitite
5070-702: Is a glassy residue formed from the desert floor sand at the Trinity nuclear bomb test site. Edeowie glass , found in South Australia , is proposed to originate from Pleistocene grassland fires, lightning strikes, or hypervelocity impact by one or several asteroids or comets . Naturally occurring obsidian glass was used by Stone Age societies as it fractures along very sharp edges, making it ideal for cutting tools and weapons. Glassmaking dates back at least 6000 years, long before humans had discovered how to smelt iron. Archaeological evidence suggests that
5200-418: Is a very powerful colouring agent, yielding dark green. Sulphur combined with carbon and iron salts produces amber glass ranging from yellowish to almost black. A glass melt can also acquire an amber colour from a reducing combustion atmosphere. Cadmium sulfide produces imperial red , and combined with selenium can produce shades of yellow, orange, and red. Addition of copper(II) oxide (CuO) produces
5330-449: Is achieved by homogenizing the raw materials mixture ( glass batch ), stirring the melt, and crushing and re-melting the first melt. The obtained glass is usually annealed to prevent breakage during processing. Colour in glass may be obtained by addition of homogenously distributed electrically charged ions (or colour centres ). While ordinary soda–lime glass appears colourless in thin section, iron(II) oxide (FeO) impurities produce
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5460-406: Is descended from a / , a diagonal slash known as virgula suspensiva , used from the 13th to 17th centuries to represent a pause. The modern comma was first used by Aldus Manutius . In general, the comma shows that the words immediately before the comma are less closely or exclusively linked grammatically to those immediately after the comma than they might be otherwise. The comma performs
5590-676: Is extensively used for fibreglass , used for making glass-reinforced plastics (boats, fishing rods, etc.), top-of-stove cookware, and halogen bulb glass. The addition of barium also increases the refractive index. Thorium oxide gives glass a high refractive index and low dispersion and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern eyeglasses. Iron can be incorporated into glass to absorb infrared radiation, for example in heat-absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs ultraviolet wavelengths. Fluorine lowers
5720-455: Is in widespread use in optical systems due to its ability to refract, reflect, and transmit light following geometrical optics . The most common and oldest applications of glass in optics are as lenses , windows , mirrors , and prisms . The key optical properties refractive index , dispersion , and transmission , of glass are strongly dependent on chemical composition and, to a lesser degree, its thermal history. Optical glass typically has
5850-481: Is incorrect, as once solidified, glass stops flowing. The sags and ripples observed in old glass were already there the day it was made; manufacturing processes used in the past produced sheets with imperfect surfaces and non-uniform thickness (the near-perfect float glass used today only became widespread in the 1960s). A 2017 study computed the rate of flow of the medieval glass used in Westminster Abbey from
5980-426: Is marked by the formation of power centers that came to be individual states. The development of weapons increased in this period to protect increasingly developed rice fields and fishing rights. Trade greatly increased in this period, as did the specialization of production of certain items, including magatama . Magatama producing areas exchanged their product with other products, specifically rice , leading to
6110-538: Is most often formed by rapid cooling ( quenching ) of the molten form. Some glasses such as volcanic glass are naturally occurring, and obsidian has been used to make arrowheads and knives since the Stone Age . Archaeological evidence suggests glassmaking dates back to at least 3600 BC in Mesopotamia , Egypt , or Syria . The earliest known glass objects were beads , perhaps created accidentally during metalworking or
6240-424: Is non- restrictive , as in I cut down all the trees, which were over six feet tall. (Without the comma, this would mean that only the trees more than six feet tall were cut down.) Some style guides prescribe that two independent clauses joined by a coordinating conjunction ( for , and , nor , but , or , yet , so ) must be separated by a comma placed before the conjunction. In the following sentences, where
6370-901: Is produced by forcing molten glass through a fine mesh by centripetal force and breaking the extruded glass fibres into short lengths using a stream of high-velocity air. The fibres are bonded with an adhesive spray and the resulting wool mat is cut and packed in rolls or panels. Besides common silica-based glasses many other inorganic and organic materials may also form glasses, including metals , aluminates , phosphates , borates , chalcogenides , fluorides , germanates (glasses based on GeO 2 ), tellurites (glasses based on TeO 2 ), antimonates (glasses based on Sb 2 O 3 ), arsenates (glasses based on As 2 O 3 ), titanates (glasses based on TiO 2 ), tantalates (glasses based on Ta 2 O 5 ), nitrates , carbonates , plastics , acrylic , and many other substances. Some of these glasses (e.g. Germanium dioxide (GeO 2 , Germania), in many respects
6500-410: Is regarded as an error in modern times. Glass Glass is an amorphous ( non-crystalline ) solid. Because it is often transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window panes, tableware , and optics . Some common objects made of glass are named after the material, e.g. "glass" , " glasses ", " magnifying glass ". Glass
6630-461: Is stronger than most metals, with a theoretical tensile strength for pure, flawless glass estimated at 14 to 35 gigapascals (2,000,000 to 5,100,000 psi) due to its ability to undergo reversible compression without fracture. However, the presence of scratches, bubbles, and other microscopic flaws lead to a typical range of 14 to 175 megapascals (2,000 to 25,400 psi) in most commercial glasses. Several processes such as toughening can increase
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#17328798224926760-408: Is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead, the disordered atomic configuration of the supercooled liquid is frozen into the solid state at T g . The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory . Generally, a glass exists in
6890-567: Is the Yasakani no Magatama ( 八尺瓊勾玉 , also 八尺瓊曲玉 and 八坂瓊曲玉 ) , one of the three Imperial Regalia of Japan . Swords, mirrors, and jewels were common objects of status for regional rulers in Japan as early as the Yayoi period, and were further widespread in the Kofun period, as shown by their ubiquitous presence in kofun tumuli. The Yasakani no Magatama is stored at the Kashiko-dokoro ( 賢所 ) ,
7020-649: Is the one in the Second Amendment to the United States Constitution , which says "A well regulated Militia being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." but ratified by several states as "A well regulated Militia being necessary to the security of a free State, the right of the people to keep and bear Arms shall not be infringed." which has caused much debate on its interpretation. Commas are always used to set off certain adverbs at
7150-436: Is transparent, easily formed, and most suitable for window glass and tableware. However, it has a high thermal expansion and poor resistance to heat. Soda–lime glass is typically used for windows , bottles , light bulbs , and jars . Borosilicate glasses (e.g. Pyrex , Duran ) typically contain 5–13% boron trioxide (B 2 O 3 ). Borosilicate glasses have fairly low coefficients of thermal expansion (7740 Pyrex CTE
7280-534: Is very short, typically when the second independent clause is an imperative , as in: The above guidance is not universally accepted or applied. Long coordinate clauses , particularly when separated by "but", are often separated by commas: In some languages, such as German and Polish , stricter rules apply on comma use between clauses, with dependent clauses always being set off with commas, and commas being generally proscribed before certain coordinating conjunctions. The joining of two independent sentences with
7410-434: The Nihon Shoki , which largely describes the mythology of Japan. Susanoo , god of the sea and storms, received five hundred magatama from Tamanoya no mikoto , or Ame-no-Futodama-no-mikoto , the jewel-making deity. Susanoo went to heaven and presented them to his sister, the sun goddess Amaterasu , who bit off successive parts of the magatama , and blew them away to create other deities. Tamanoya no mikoto remains
7540-582: The AP Stylebook for journalistic writing advises against it. The serial comma is also known as the Oxford comma, Harvard comma, or series comma. Although less common in British English, its usage occurs within both American and British English. It is called the Oxford comma because of its long history of use by Oxford University Press. According to New Hart's Rules , "house style will dictate" whether to use
7670-478: The AP Stylebook , also recommend that the year be treated as a parenthetical, requiring a second comma after it: "Feb. 14, 1987, was the target date." If just the month and year are given, no commas are used: "Her daughter may return in June 2009 for the reunion." When the day precedes the month, the month name separates the numeric day and year, so commas are not necessary to separate them: "The Raid on Alexandria
7800-495: The Kou site , Fujiidera , Osaka Prefecture . Numerous magatama at the Ōishi site, Bungo-ōno , Ōita Prefecture , Kyushu show signs of being used for ceremonial, rather than decorative, purposes. The Sannai-Maruyama Site , excavated 1992 in Aomori , Aomori Prefecture , yielded three large jade beads measuring 5.5 by 6.5 centimetres (2.2 in × 2.6 in). Magatama in
7930-513: The Late Bronze Age , there was a rapid growth in glassmaking technology in Egypt and Western Asia . Archaeological finds from this period include coloured glass ingots , vessels, and beads. Much early glass production relied on grinding techniques borrowed from stoneworking , such as grinding and carving glass in a cold state. The term glass has its origins in the late Roman Empire , in
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#17328798224928060-630: The Record likely describes a tribute of two jade magatama . The large-scale Yayoi period remains at the Yoshinogari site , Yoshinogari and Kanzaki in Saga Prefecture revealed examples of lead glass magatama typical of the Yayoi period. In 2003, the excavation of a large Yayoi period settlement in Tawaramoto, Nara also revealed two large jade magatama , one 4.64 centimetres (1.83 in),
8190-525: The Renaissance period in Europe, the use of large stained glass windows became much less prevalent, although stained glass had a major revival with Gothic Revival architecture in the 19th century. During the 13th century, the island of Murano , Venice , became a centre for glass making, building on medieval techniques to produce colourful ornamental pieces in large quantities. Murano glass makers developed
8320-527: The Roman glass making centre at Trier (located in current-day Germany) where the late-Latin term glesum originated, likely from a Germanic word for a transparent , lustrous substance. Glass objects have been recovered across the Roman Empire in domestic, funerary , and industrial contexts, as well as trade items in marketplaces in distant provinces. Examples of Roman glass have been found outside of
8450-586: The Wa people , an ancient country of Yamatai , and its queen, Himiko . The Record indicates that when Himiko died, her relative Iyo, a girl of 13, was made queen and sent a delegation of twenty officials under Yazuku, an imperial general, to offer tribute to the Northern Wei court. "The delegation visited the capital and offered to the court five thousand white gems and two pieces of carved jade, as well as twenty pieces of brocade with variegated designs." The carved jade in
8580-447: The Yayoi period (300 BCE – 300 CE) are notably different from Jōmon-period magatama . The jewels moved from a primitive, non-standard form towards more polished and uniform form in this period. The technology to cut large gemstones and polish jewels notably advanced in the Yayoi period. Refined materials such as jadeite, serpentinite, and glass replaced the less sophisticated materials of
8710-465: The dielectric constant of glass. Fluorine is highly electronegative and lowers the polarizability of the material. Fluoride silicate glasses are used in the manufacture of integrated circuits as an insulator. Glass-ceramic materials contain both non-crystalline glass and crystalline ceramic phases. They are formed by controlled nucleation and partial crystallisation of a base glass by heat treatment. Crystalline grains are often embedded within
8840-436: The glass batch preparation and mixing, the raw materials are transported to the furnace. Soda–lime glass for mass production is melted in glass-melting furnaces . Smaller-scale furnaces for speciality glasses include electric melters, pot furnaces, and day tanks. After melting, homogenization and refining (removal of bubbles), the glass is formed . This may be achieved manually by glassblowing , which involves gathering
8970-466: The god of magatama , glasses, and cameras. In the legend Amaterasu later shuts herself in a cave. Ama-no-Koyane-no-mikoto hung magatama , among other objects, on a five hundred-branch sakaki tree, to successfully lure Amaterasu from the cave. In the year 58, in the reign of the Emperor Suinin , the Nihon Shoki records that a dog killed and disemboweled a mujina ( badger ), and
9100-501: The 10th century onwards, glass was employed in stained glass windows of churches and cathedrals , with famous examples at Chartres Cathedral and the Basilica of Saint-Denis . By the 14th century, architects were designing buildings with walls of stained glass such as Sainte-Chapelle , Paris, (1203–1248) and the East end of Gloucester Cathedral . With the change in architectural style during
9230-595: The 16th installment, Hidden Star in Four Seasons , has her ears designed in the shape of magatama. In Blue Eye Samurai , the main character Mizu wore a blue magatama on her katana. In Miraculous: Tales of Ladybug & Cat Noir , the Kwagatama charms named after the magatama serve as a symbol of a bond between the kwami and their holder. In Shin Megami Tensei III: Nocturne , magatamas appear in
9360-461: The 1930s, which later became known as Depression glass . In the 1950s, Pilkington Bros. , England , developed the float glass process, producing high-quality distortion-free flat sheets of glass by floating on molten tin . Modern multi-story buildings are frequently constructed with curtain walls made almost entirely of glass. Laminated glass has been widely applied to vehicles for windscreens. Optical glass for spectacles has been used since
9490-573: The Inland Sea, wood, and bronze. In this period the use of the mirror , sword , and jewels as status symbols for village, and later regional leaders of all kinds, emerged in the Yayoi period, and point to the origin of the mirror, sword, and magatama as the Imperial Regalia of Japan . The Records of the Three Kingdoms , the earliest historical document with a reference to Japan, describes
9620-513: The Japanese card game “Yu-Gi-Oh!”, “Hu-Li the Jewel Mikanko” is based on the “Yasakani no Magatama” - one of the “Three Imperial Regalia of Japan”. Comma The comma , is a punctuation mark that appears in several variants in different languages. Some typefaces render it as a small line, slightly curved or straight, but inclined from the vertical, others give it the appearance of
9750-609: The Jōmon period have been discovered in large numbers at the Kamegaoka site in Tsugaru , Aomori Prefecture . The Kamegaoka remains are among the largest known Jōmon settlement in Japan, and the magatama , among other decorative objects found, may be an indicator of the high social status of the settlement. Other sites associated with the Kamegaoka settlement have yielded magatama , including
9880-422: The Jōmon period. Yayoi period magatama are noted for their reverse C-shaped form, which by the end of the period had become an almost squared shape. From the Yayoi period onwards, magatama uniformly feature a bored hole that allowed the jewels to be held on a string. The Yayoi period is marked by specific geographic centers specializing in magatama and the widespread trade of magatama . The period
10010-568: The Kingdom , the Amber Relics, Dusk Relics, and Secret Stones are all based on the magatama. In the Ace Attorney series, a magatama is frequently cited as the source of an ability that lets its wearer determine people's true intentions. In Unconnected Marketeers , the 18th installment of Touhou Project , the character Misumaru Tamatsukuri is able to craft magatama. Aunn Komano, introduced in
10140-485: The Kofun period are especially numerous. An excavation of the Kamegaoka Kofun , Kishiwada, Osaka , revealed a local who had been buried with a jade, jasper, and alabaster magatama necklace, as well as magatama placed near the feet. A bronze mirror imported from China accompanying the burial was dated to 239 CE. The kofun is a Designated Historical Spot of the city of Kishiwada. Ceremonial offerings from
10270-681: The Middle Ages. The production of lenses has become increasingly proficient, aiding astronomers as well as having other applications in medicine and science. Glass is also employed as the aperture cover in many solar energy collectors. In the 21st century, glass manufacturers have developed different brands of chemically strengthened glass for widespread application in touchscreens for smartphones , tablet computers , and many other types of information appliances . These include Gorilla Glass , developed and manufactured by Corning , AGC Inc. 's Dragontrail and Schott AG 's Xensation. Glass
10400-540: The Pb ion renders it highly immobile and hinders the movement of other ions; lead glasses therefore have high electrical resistance, about two orders of magnitude higher than soda–lime glass (10 vs 10 Ω⋅cm, DC at 250 °C). Aluminosilicate glass typically contains 5–10% alumina (Al 2 O 3 ). Aluminosilicate glass tends to be more difficult to melt and shape compared to borosilicate compositions but has excellent thermal resistance and durability. Aluminosilicate glass
10530-530: The UK's Pilkington Brothers, who created a continuous ribbon of glass using a molten tin bath on which the molten glass flows unhindered under the influence of gravity. The top surface of the glass is subjected to nitrogen under pressure to obtain a polished finish. Container glass for common bottles and jars is formed by blowing and pressing methods. This glass is often slightly modified chemically (with more alumina and calcium oxide) for greater water resistance. Once
10660-814: The Yamato Plain, 238 millimetres (9.4 in) in length, was plundered long before its excavation, but revealed 600 talc ceremonial magatama among other funerary objects, which also included 10 bronze Han Chinese mirrors. The Hiraide remains of Shiojiri, Nagano , one of the three largest prehistoric sites in Japan, and far from any regional power center, includes typical Kofun period remains, but also objects associated with modern Shinto ceremonial practice. Nevertheless, kofun in Hiraide reveal both plain and elaborate magatama among other funerary objects. The Sakurai Kofun in Sakurai, Nara , excavated in 1949, represents
10790-719: The action of water, making it an ideal material for the manufacture of containers for foodstuffs and most chemicals. Nevertheless, although usually highly resistant to chemical attack, glass will corrode or dissolve under some conditions. The materials that make up a particular glass composition affect how quickly the glass corrodes. Glasses containing a high proportion of alkali or alkaline earth elements are more susceptible to corrosion than other glass compositions. The density of glass varies with chemical composition with values ranging from 2.2 grams per cubic centimetre (2,200 kg/m ) for fused silica to 7.2 grams per cubic centimetre (7,200 kg/m ) for dense flint glass. Glass
10920-432: The amount of breath needed to complete each fragment of the text when reading aloud. The different lengths were signified by a dot at the bottom, middle, or top of the line. For a short passage, a komma in the form of a dot ⟨·⟩ was placed mid-level. This is the origin of the concept of a comma, although the name came to be used for the mark itself instead of the clause it separated. The mark used today
11050-416: The beginning of a sentence, including however , in fact , therefore , nevertheless , moreover , furthermore , and still . If these adverbs appear in the middle of a sentence, they are followed and preceded by a comma. As in the second of the two examples below, if a semicolon separates the two sentences and the second sentence starts with an adverb, this adverb is preceded by a semicolon and followed by
11180-635: The central shrine of the Three Palace Sanctuaries at the Tokyo Imperial Palace , and is used in the enthronement ceremony of the Emperor of Japan . Daniel Clarence Holtom stated in 1928 in Japanese enthronement ceremonies; with an account of the imperial regalia that the Yasakani no Magatama is the only one of the three regalia that is used in its original form for ceremonies, preferring
11310-455: The comma is used as a decimal separator , equivalent to the use in English of the decimal point . In India, the groups are two digits, except for the rightmost group, which is of three digits. In some styles, the comma may not be used for this purpose at all (e.g. in the SI writing style ); a space may be used to separate groups of three digits instead. Commas are used when rewriting names to present
11440-411: The cost factor has a low priority. In the laboratory mostly pure chemicals are used. Care must be taken that the raw materials have not reacted with moisture or other chemicals in the environment (such as alkali or alkaline earth metal oxides and hydroxides, or boron oxide ), or that the impurities are quantified (loss on ignition). Evaporation losses during glass melting should be considered during
11570-427: The crystalline ceramic phase can be balanced with the positive CTE of the glassy phase. At a certain point (~70% crystalline) the glass-ceramic has a net CTE near zero. This type of glass-ceramic exhibits excellent mechanical properties and can sustain repeated and quick temperature changes up to 1000 °C. Fibreglass (also called glass fibre reinforced plastic, GRP) is a composite material made by reinforcing
11700-683: The desired form is obtained, glass is usually annealed for the removal of stresses and to increase the glass's hardness and durability. Surface treatments, coatings or lamination may follow to improve the chemical durability ( glass container coatings , glass container internal treatment ), strength ( toughened glass , bulletproof glass , windshields ), or optical properties ( insulated glazing , anti-reflective coating ). New chemical glass compositions or new treatment techniques can be initially investigated in small-scale laboratory experiments. The raw materials for laboratory-scale glass melts are often different from those used in mass production because
11830-565: The end of the Kofun period functioned as ceremonial and religious objects. Magatama first appeared in Japan in the Final Jōmon period (1000–300 BCE), and in this period were made from relatively simple, naturally occurring materials, including clay , talc , slate , quartz , gneiss , jadeite , nephrite , and serpentinite . Magatama from the Jōmon period were irregularly shaped, lacked continuity in form from region to region, and have been called " Stone Age magatama " for this reason. Magatama are thought to be an imitation of
11960-424: The end of the period. Large magatama made of talc , imitations of smaller ones made of more precious materials, were used as grave goods . Magatama are found in kofun tumuli across Japan from the period. Their use went from merely decorative to sacred and ceremonial grave goods. Chōjigashira magatama ( 丁字頭勾玉 ) are magatama with inscriptions that look like flowers of the clove tree and have
12090-462: The exceptionally clear colourless glass cristallo , so called for its resemblance to natural crystal, which was extensively used for windows, mirrors, ships' lanterns, and lenses. In the 13th, 14th, and 15th centuries, enamelling and gilding on glass vessels were perfected in Egypt and Syria. Towards the end of the 17th century, Bohemia became an important region for glass production, remaining so until
12220-454: The first true synthetic glass was made in Lebanon and the coastal north Syria , Mesopotamia or ancient Egypt . The earliest known glass objects, of the mid-third millennium BC, were beads , perhaps initially created as accidental by-products of metalworking ( slags ) or during the production of faience , a pre-glass vitreous material made by a process similar to glazing . Early glass
12350-448: The form of parasitic, insect-like creatures that grant their human hosts special, demonic powers. In Ghostwire: Tokyo , magatamas are made of jade and are used for upgrading Akito's abilities. They can be obtained through side missions (37), and street stalls (three). In Ōkami and its sequel Ōkamiden , one of the weapon options (rosaries) are based on Amaterasu's magatama. In The Irregular at Magic High School , magatama are
12480-733: The former Roman Empire in China , the Baltics , the Middle East , and India . The Romans perfected cameo glass , produced by etching and carving through fused layers of different colours to produce a design in relief on the glass object. In post-classical West Africa, Benin was a manufacturer of glass and glass beads. Glass was used extensively in Europe during the Middle Ages . Anglo-Saxon glass has been found across England during archaeological excavations of both settlement and cemetery sites. From
12610-555: The glass and melt phases. Important polymer glasses include amorphous and glassy pharmaceutical compounds. These are useful because the solubility of the compound is greatly increased when it is amorphous compared to the same crystalline composition. Many emerging pharmaceuticals are practically insoluble in their crystalline forms. Many polymer thermoplastics familiar to everyday use are glasses. For many applications, like glass bottles or eyewear , polymer glasses ( acrylic glass , polycarbonate or polyethylene terephthalate ) are
12740-493: The glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. However, the equilibrium theory of phase transformations does not hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids. Glass can form naturally from volcanic magma. Obsidian
12870-406: The glass transition temperature is not supported by empirical research or theoretical analysis (see viscosity in solids ). Though atomic motion at glass surfaces can be observed, and viscosity on the order of 10 –10 Pa s can be measured in glass, such a high value reinforces the fact that glass would not change shape appreciably over even large periods of time. For melt quenching, if the cooling
13000-477: The history and production of magatama . Magatama became very common in the Kofun period (250–536 CE), and by the end of the period almost all kofun tumuli contained magatama . In the early Kofun period, magatama were made from jadeite as in earlier periods, but by the middle of the period were made from jasper , and by the end of the period, almost exclusively of agate and jade . Magatama capped by silver or gold also appear towards
13130-458: The liquid can easily be supercooled into a glass. Examples include LiCl: R H 2 O (a solution of lithium chloride salt and water molecules) in the composition range 4< R <8. sugar glass , or Ca 0.4 K 0.6 (NO 3 ) 1.4 . Glass electrolytes in the form of Ba-doped Li-glass and Ba-doped Na-glass have been proposed as solutions to problems identified with organic liquid electrolytes used in modern lithium-ion battery cells. Following
13260-423: The marks hinder optical character recognition . Canada Post has similar guidelines, only making very limited use of hyphens. Similar to the case in natural languages, commas are often used to delineate the boundary between multiple mathematical objects in a list (e.g., ( 3 , 5 , 12 ) {\displaystyle (3,5,12)} ). Commas are also used to indicate the comma derivative of
13390-471: The meaning would be the same if their order were reversed or if and were placed between them. For example: Some writers precede quoted material that is the grammatical object of an active verb of speaking or writing with a comma, as in Mr. Kershner says, "You should know how to use a comma." Quotations that follow and support an assertion are often preceded by a colon rather than a comma. Other writers do not put
13520-481: The melt whilst it floats on a gas stream) or splat quenching (pressing the melt between two metal anvils or rollers), may be used to increase the cooling rate or to reduce crystal nucleation triggers. In the past, small batches of amorphous metals with high surface area configurations (ribbons, wires, films, etc.) have been produced through the implementation of extremely rapid rates of cooling. Amorphous metal wires have been produced by sputtering molten metal onto
13650-433: The melt. The high density of lead glass (silica + lead oxide (PbO) + potassium oxide (K 2 O) + soda (Na 2 O) + zinc oxide (ZnO) + alumina) results in a high electron density, and hence high refractive index, making the look of glassware more brilliant and causing noticeably more specular reflection and increased optical dispersion . Lead glass has a high elasticity, making the glassware more workable and giving rise to
13780-619: The melting temperature and simplify glass processing. Sodium carbonate (Na 2 CO 3 , "soda") is a common additive and acts to lower the glass-transition temperature. However, sodium silicate is water-soluble , so lime (CaO, calcium oxide , generally obtained from limestone ), along with magnesium oxide (MgO), and aluminium oxide (Al 2 O 3 ), are commonly added to improve chemical durability. Soda–lime glasses (Na 2 O) + lime (CaO) + magnesia (MgO) + alumina (Al 2 O 3 ) account for over 75% of manufactured glass, containing about 70 to 74% silica by weight. Soda–lime–silicate glass
13910-410: The metallic ions will absorb wavelengths of light corresponding to specific colours. In the manufacturing process, glasses can be poured, formed, extruded and moulded into forms ranging from flat sheets to highly intricate shapes. The finished product is brittle but can be laminated or tempered to enhance durability. Glass is typically inert, resistant to chemical attack, and can mostly withstand
14040-409: The most significant architectural innovations of modern times, where glass buildings now often dominate the skylines of many modern cities . These systems use stainless steel fittings countersunk into recesses in the corners of the glass panels allowing strengthened panes to appear unsupported creating a flush exterior. Structural glazing systems have their roots in iron and glass conservatories of
14170-400: The parenthetical is at the start or end of the sentence. The following are examples of types of parenthetical phrases: The parenthesization of phrases may change the connotation, reducing or eliminating ambiguity . In the following example, the thing in the first sentence that is relaxing is the cool day, whereas in the second sentence, it is the walk since the introduction of commas makes "on
14300-468: The period. A "middle Jōmon exchange network" may have existed, whereby magatama were produced in regions where materials for their manufacture were readily plentiful. Jade and talc examples produced in bead-making villages located in present-day Itoigawa, Niigata have been found at a large number of sites along the northern coast, in the central mountains, and in Kantō region . Examples of magatama from
14430-922: The production of faience , which is a form of pottery using lead glazes. Due to its ease of formability into any shape, glass has been traditionally used for vessels, such as bowls , vases , bottles , jars and drinking glasses. Soda–lime glass , containing around 70% silica , accounts for around 90% of modern manufactured glass. Glass can be coloured by adding metal salts or painted and printed with vitreous enamels , leading to its use in stained glass windows and other glass art objects. The refractive , reflective and transmission properties of glass make glass suitable for manufacturing optical lenses , prisms , and optoelectronics materials. Extruded glass fibres have applications as optical fibres in communications networks, thermal insulating material when matted as glass wool to trap air, or in glass-fibre reinforced plastic ( fibreglass ). The standard definition of
14560-512: The second 3.63 centimetres (1.43 in) in length. The larger Tawaramoto magatama is the 10th-largest example found to date in Japan. Both jade magatama from the site are of unusually high-quality brilliant green jade. One known center of Yayoi magatama production was in the area of the Tamatsukuri Inari Shrine in Osaka . Tamatsukuri literally means "jewel making", and
14690-413: The second clause is independent (because it can stand alone as a sentence), the comma is considered by those guides to be necessary: In the following sentences, where the second half of the sentence is a dependent clause (because it does not contain an explicit subject ), those guides prescribe that the comma be omitted: However, such guides permit the comma to be omitted if the second independent clause
14820-424: The selection of the raw materials, e.g., sodium selenite may be preferred over easily evaporating selenium dioxide (SeO 2 ). Also, more readily reacting raw materials may be preferred over relatively inert ones, such as aluminium hydroxide (Al(OH) 3 ) over alumina (Al 2 O 3 ). Usually, the melts are carried out in platinum crucibles to reduce contamination from the crucible material. Glass homogeneity
14950-538: The serial comma. "The general rule is that one style or the other should be used consistently." No association with region or dialect is suggested, other than that its use has been strongly advocated by Oxford University Press. Its use is preferred by Fowler 's Modern English Usage . It is recommended by the United States Government Printing Office , Harvard University Press , and the classic Elements of Style of Strunk and White . Use of
15080-413: The serial comma: all lists must have a comma before the "and" prefacing the last item in a series ( see Differences between American and British usage below ). If the individual items of a list are long, complex, affixed with description, or themselves contain commas, semicolons may be preferred as separators, and the list may be introduced with a colon . In news headlines , a comma might replace
15210-587: The start of the 20th century. By the 17th century, glass in the Venetian tradition was also being produced in England . In about 1675, George Ravenscroft invented lead crystal glass, with cut glass becoming fashionable in the 18th century. Ornamental glass objects became an important art medium during the Art Nouveau period in the late 19th century. Throughout the 20th century, new mass production techniques led to
15340-469: The strength of glass. Carefully drawn flawless glass fibres can be produced with a strength of up to 11.5 gigapascals (1,670,000 psi). The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption
15470-438: The surname first, generally in instances of alphabetization by surname: Smith, John . They are also used before many titles that follow a name: John Smith, Ph.D. It can also be used in regnal names followed by their occupation: Louis XIII, king of France and Navarre . Similarly in lists that are presented with an inversion: socks, green: 3 pairs; socks, red: 2 pairs; tie, regimental: 1 . Commas may be used to indicate that
15600-460: The system Al-Fe-Si may undergo a first-order transition to an amorphous form (dubbed "q-glass") on rapid cooling from the melt. Transmission electron microscopy (TEM) images indicate that q-glass nucleates from the melt as discrete particles with uniform spherical growth in all directions. While x-ray diffraction reveals the isotropic nature of q-glass, a nucleation barrier exists implying an interfacial discontinuity (or internal surface) between
15730-406: The teeth of large animals, pierced with a hole, which are found in earlier Jōmon remains. These resemble magatama , but more recent scholarship indicates that these early Jōmon may have simply had a decorative function, and have no relationship to magatama . Magatama in the Jōmon period appear to have moved from the purely decorative to having a status and ceremonial function by the end of
15860-546: The use of replicas for the sword and mirror due to its delicate fragility. Replicas of the sword and mirror were made as early as the 9th century, and the originals were entrusted to other shrines. D. C. Holtom stated that noro priestesses ( Okinawan : nūru ) of the Ryukyu Kingdom wore magatama necklaces early in the 20th century for ceremonial purposes, but provides no other details. In The Legend of Zelda: Skyward Sword and The Legend of Zelda: Tears of
15990-451: The widespread availability of glass in much larger amounts, making it practical as a building material and enabling new applications of glass. In the 1920s a mould -etch process was developed, in which art was etched directly into the mould so that each cast piece emerged from the mould with the image already on the surface of the glass. This reduced manufacturing costs and, combined with a wider use of coloured glass, led to cheap glassware in
16120-422: The widespread distribution of magatama across Japan. Magatama were commonly used to create necklaces and bracelets worn on the wrists or ankles. The necklace was typically constructed of jadeite magatama separated by cylindrical bored-holed pieces of jasper. Small beads of dark-blue glass are also not uncommon on the necklace. The bracelet typically also used shells from the coastal areas of Shikoku and
16250-437: The word "and", even if there are only two items, in order to save space, as in this headline from Reuters: Commas are often used to separate clauses . In English, a comma is often used to separate a dependent clause from the independent clause if the dependent clause comes first: After I fed the cat, I brushed my clothes. (Compare this with I brushed my clothes after I fed the cat. ) A relative clause takes commas if it
16380-402: The year 1268. The study found that the room temperature viscosity of this glass was roughly 10 Pa · s which is about 10 times less viscous than a previous estimate made in 1998, which focused on soda-lime silicate glass. Even with this lower viscosity, the study authors calculated that the maximum flow rate of medieval glass is 1 nm per billion years, making it impossible to observe in
16510-726: The Ōboriya shell mound , in the northwest corner of Ōfunato Bay , which yielded a huge number of beads, as well as the Korekawa site , near Hachinohe , Aomori Prefecture . Remains from the Korekawa site can be seen at the Korekawa Archaeological Museum in Hachinohe. Stone and clay magatama and magatama -like beads have also been discovered at the Amataki site, Ninohe , Iwate Prefecture , Osagata site, Ibaraki Prefecture , and
16640-700: Was carried out on 19 December 1941." Commas are used to separate parts of geographical references, such as city and state ( Dallas, Texas ) or city and country ( Kampala, Uganda ). Additionally, most style manuals, including The Chicago Manual of Style and the AP Stylebook , recommend that the second element be treated as a parenthetical, requiring a second comma after: "The plane landed in Kampala, Uganda, that evening." The United States Postal Service and Royal Mail recommend leaving out punctuation when writing addresses on actual letters and packages, as
16770-510: Was originally used in the United Kingdom and United States during World War II to manufacture radomes . Uses of fibreglass include building and construction materials, boat hulls, car body parts, and aerospace composite materials. Glass-fibre wool is an excellent thermal and sound insulation material, commonly used in buildings (e.g. attic and cavity wall insulation ), and plumbing (e.g. pipe insulation ), and soundproofing . It
16900-539: Was rarely transparent and often contained impurities and imperfections, and is technically faience rather than true glass, which did not appear until the 15th century BC. However, red-orange glass beads excavated from the Indus Valley Civilization dated before 1700 BC (possibly as early as 1900 BC) predate sustained glass production, which appeared around 1600 BC in Mesopotamia and 1500 BC in Egypt. During
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