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Thixotropy
Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick or viscous under static conditions will flow (become thinner, less viscous) over time when shaken, agitated, shear-stressed, or otherwise stressed ( time-dependent viscosity). They then take a fixed time to return to a more viscous state. Some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a steep change in shear rate. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids. Others such as yogurt take much longer and can become nearly solid. Many gels and colloids are thixotropic materials, exhibiting a stable form at rest but becoming fluid when agitated. Thixotropy arises because particles or structured solutes re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rheopecty
In continuum mechanics, rheopecty or rheopexy is the rare property of some non-Newtonian fluids to show a time-dependent increase in viscosity ( time-dependent viscosity); the longer the fluid undergoes shearing force, the higher its viscosity. Rheopectic fluids, such as some lubricants, thicken or solidify when shaken. The opposite and much more common type of behaviour, in which fluids become less viscous the longer they undergo shear, is called thixotropy. Examples of rheopectic fluids include gypsum pastes, printer inks, and synovial fluid. There is ongoing research into new ways to make and use rheopectic materials. There is great interest in possible military uses of this technology. Moreover, the high end of the sports market has also begun to respond to it. Body armor and combat vehicle armor are key areas where efforts are being made to use rheopectic materials. Work is also being done to use these materials in other kinds of protective equipment, which is seen as po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudoplastic
In rheology, shear thinning is the non-Newtonian behavior of fluids whose viscosity decreases under shear strain. It is sometimes considered synonymous for pseudo-plastic behaviour, and is usually defined as excluding time-dependent effects, such as thixotropy. Shear thinning is the most common type of non-Newtonian behavior of fluids and is seen in many industrial and everyday applications. Although shear thinning is generally not observed in pure liquids with low molecular mass or ideal solutions of small molecules like sucrose or sodium chloride, it is often observed in polymer solutions and molten polymers, as well as complex fluids and suspensions like ketchup, whipped cream, blood, paint, and nail polish. Theories behind shear-thinning behaviour Though the exact cause of shear thinning is not fully understood, it is widely regarded to be the effect of small structural changes within the fluid, such that microscale geometries within the fluid rearrange to facilitat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Thinning
In rheology, shear thinning is the non-Newtonian behavior of fluids whose viscosity decreases under shear strain. It is sometimes considered synonymous for pseudo-plastic behaviour, and is usually defined as excluding time-dependent effects, such as thixotropy. Shear thinning is the most common type of non-Newtonian behavior of fluids and is seen in many industrial and everyday applications. Although shear thinning is generally not observed in pure liquids with low molecular mass or ideal solutions of small molecules like sucrose or sodium chloride, it is often observed in polymer solutions and molten polymers, as well as complex fluids and suspensions like ketchup, whipped cream, blood, paint, and nail polish. Theories behind shear-thinning behaviour Though the exact cause of shear thinning is not fully understood, it is widely regarded to be the effect of small structural changes within the fluid, such that microscale geometries within the fluid rearrange to facilitate shea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gels
A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady state, although the liquid phase may still diffuse through this system. Gels are mostly liquid by mass, yet they behave like solids because of a three-dimensional cross-linked network within the liquid. It is the cross-linking within the fluid that gives a gel its structure (hardness) and contributes to the adhesive stick ( tack). In this way, gels are a dispersion of molecules of a liquid within a solid medium. The word ''gel'' was coined by 19th-century Scottish chemist Thomas Graham by clipping from ''gelatine''. The process of forming a gel is called gelation. Composition Gels consist of a solid three-dimensional network that spans the volume of a liquid medium and ensnares it through surface tension effects. This internal network structure may result from physical b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketchup
Ketchup or catsup is a table condiment with a sweet and sour flavor. "Ketchup" now typically refers to tomato ketchup, although early recipes for different varieties contained mushrooms, oysters, mussels, egg whites, grapes, or walnuts, among other ingredients. Tomato ketchup is made from tomatoes, sugar, and vinegar, with seasonings and spices. The spices and flavors vary but commonly include onions, allspice, coriander, cloves, cumin, garlic, mustard and sometimes include celery, cinnamon, or ginger. The market leader in the United States (60% market share) and the United Kingdom (82%) is Heinz Tomato Ketchup. Tomato ketchup is often used as a condiment for dishes that are usually served hot, and are fried or greasy: e.g., french fries and other potato dishes, hamburgers, hot dogs, chicken tenders, hot sandwiches, meat pies, cooked eggs, and grilled or fried meat. Ketchup is sometimes used as the basis for, or as one ingredient in, other sauces and dressings, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcano
A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes resulting from divergent tectonic activity are usually non-explosive whereas those resulting from convergent tectonic activity cause violent eruptions."Mid-ocean ridge tectonics, volcanism and geomorphology." Geology 26, no. 455 (2001): 458. https://macdonald.faculty.geol.ucsb.edu/papers/Macdonald%20Mid-Ocean%20Ridge%20Tectonics.pdf Volcanoes can also form where there is str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquefaction
In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics. It occurs both naturally and artificially. As an example of the latter, a "major commercial application of liquefaction is the liquefaction of air to allow separation of the constituents, such as oxygen, nitrogen, and the noble gases." Another is the conversion of solid coal into a liquid form usable as a substitute for liquid fuels. In geology, soil liquefaction refers to the process by which water-saturated, unconsolidated sediments are transformed into a substance that acts like a liquid, often in an earthquake. Soil liquefaction was blamed for building collapses in the city of Palu, Indonesia in October 2018. In a related phenomenon, liquefaction of bulk materials in cargo ships may cause a dangerous shift in the load. In physics and chemistry, the phase transitions from solid and melting.htm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lahar
A lahar (, from ) is a violent type of mudflow or debris flow composed of a slurry of Pyroclastic rock, pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a valley, river valley. Lahars are often extremely destructive and deadly; they can flow tens of metres per second, they have been known to be up to deep, and large flows tend to destroy any structures in their path. Notable lahars include those at Mount Pinatubo in the Philippines and Nevado del Ruiz in Colombia, the latter of which killed more than 20,000 people in the Armero tragedy. Etymology The word ''lahar'' is of Javanese language, Javanese origin. Berend George Escher introduced it as a geological term in 1922. Description The word ''lahar'' is a general term for a flowing mixture of water and pyroclastic debris. It does not refer to a particular rheology or sediment concentration. Lahars can occur as normal stream flows (sediment concentration of less than 30%), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wales
Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic Sea to the south-west. , it had a population of 3.2 million. It has a total area of and over of Coastline of Wales, coastline. It is largely mountainous with its higher peaks in the north and central areas, including Snowdon (), its highest summit. The country lies within the Temperate climate, north temperate zone and has a changeable, Oceanic climate, maritime climate. Its capital and largest city is Cardiff. A distinct Culture of Wales, Welsh culture emerged among the Celtic Britons after the End of Roman rule in Britain, Roman withdrawal from Britain in the 5th century, and Wales was briefly united under Gruffudd ap Llywelyn in 1055. After over 200 years of war, the Conquest of Wales by Edward I, conquest of Wales by King Edward I o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aberfan Disaster
The Aberfan disaster () was the catastrophic collapse of a colliery spoil tip on 21 October 1966. The tip had been created on a mountain slope above the Welsh village of Aberfan, near Merthyr Tydfil, and overlaid a natural spring. Heavy rain led to a build-up of water within the tip which caused it to suddenly slide downhill as a slurry, killing 116 children and 28 adults as it engulfed Pantglas Junior School and a row of houses. The tip was the responsibility of the National Coal Board (NCB), and the subsequent inquiry placed the blame for the disaster on the organisation and nine named employees. There were seven spoil tips on the hills above Aberfan; Tip 7—the one that slipped onto the village—was started in 1958 and, at the time of the disaster, was high. In contravention of the NCB's procedures, the tip was partly based on ground from which springs emerged. After three weeks of heavy rain the tip was saturated and approximately of spoil slipped down the side of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. Clays develop plasticity (physics), plasticity when wet but can be hardened through Pottery#Firing, firing. Clay is the longest-known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery. Some of the earliest pottery shards have been radiocarbon dating, dated to around 14,000 BCE, and Clay tablet, clay tablets were the first known writing medium. Clay is used in many modern industrial processes, such as paper making, cement production, and chemical filtration, filtering. Between one-half and two-thirds of the world's population live or work in buildings made with clay, often baked into brick, as an essenti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyme Regis
Lyme Regis ( ) is a town in west Dorset, England, west of Dorchester, Dorset, Dorchester and east of Exeter. Sometimes dubbed the "Pearl of Dorset", it lies by the English Channel at the Dorset–Devon border. It has noted fossils in cliffs and beaches on the Jurassic Coast, a World Heritage Site and heritage coast. The harbour wall, known as The Cobb, appears in Jane Austen's novel Persuasion (novel), ''Persuasion'', the John Fowles novel ''The French Lieutenant's Woman'' and the 1981 The French Lieutenant's Woman (film), film of that name, partly shot in the town. A former mayor and MP was Admiral Sir George Somers, who founded the English colonial settlement of Somers Isles, now Bermuda, where Lyme Regis is twinned with St. George's, Bermuda, St George's. In July 2015, Lyme Regis joined Jamestown, Virginia in a Historic Atlantic Triangle with St George's. The 2011 United Kingdom census, 2011 census gave the urban area a population of 4,712, estimated at 4,805 in 2019. Histor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
