1.
Vaporization
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Vaporization of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization, evaporation and boiling, evaporation is a surface phenomenon, whereas boiling is a bulk phenomenon. Evaporation is a transition from the liquid phase to vapor that occurs at temperatures below the boiling temperature at a given pressure. Evaporation only occurs when the pressure of vapor of a substance is less than the equilibrium vapor pressure. Boiling is also a transition from the liquid phase to gas phase. Boiling occurs when the vapor pressure of the substance is greater than or equal to the environmental pressure. The temperature at which boiling occurs is the temperature, or boiling point. The boiling point varies with the pressure of the environment, sublimation is a direct phase transition from the solid phase to the gas phase, skipping the intermediate liquid phase. Because it does not involve the liquid phase, it is not a form of vaporization, the term vaporization has also been used to refer to the physical destruction of an object that is exposed to intense heat. As noted in discussions of the effects of weapons, this includes the vaporization of the uninhabited Marshall Island of Elugelab in the 1952 Ivy Mike thermonuclear test. All atoms lose their shells and become positively charged ions. All such matter becomes a gas of nuclei and electrons which rise into the air due to the high temperature or bond to each other as they cool
2.
Liquid
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A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a constant volume independent of pressure. As such, it is one of the four states of matter. A liquid is made up of tiny vibrating particles of matter, such as atoms, water is, by far, the most common liquid on Earth. Like a gas, a liquid is able to flow and take the shape of a container, most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, a distinctive property of the liquid state is surface tension, leading to wetting phenomena. The density of a liquid is usually close to that of a solid, therefore, liquid and solid are both termed condensed matter. On the other hand, as liquids and gases share the ability to flow, although liquid water is abundant on Earth, this state of matter is actually the least common in the known universe, because liquids require a relatively narrow temperature/pressure range to exist. Most known matter in the universe is in form as interstellar clouds or in plasma form within stars. Liquid is one of the four states of matter, with the others being solid, gas. Unlike a solid, the molecules in a liquid have a greater freedom to move. The forces that bind the molecules together in a solid are only temporary in a liquid, a liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, if liquid is placed in a bag, it can be squeezed into any shape. These properties make a suitable for applications such as hydraulics. Liquid particles are bound firmly but not rigidly and they are able to move around one another freely, resulting in a limited degree of particle mobility. As the temperature increases, the vibrations of the molecules causes distances between the molecules to increase. When a liquid reaches its point, the cohesive forces that bind the molecules closely together break. If the temperature is decreased, the distances between the molecules become smaller, only two elements are liquid at standard conditions for temperature and pressure, mercury and bromine. Four more elements have melting points slightly above room temperature, francium, caesium, gallium and rubidium, metal alloys that are liquid at room temperature include NaK, a sodium-potassium metal alloy, galinstan, a fusible alloy liquid, and some amalgams
3.
Boiling point
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The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the environmental pressure. A liquid in a vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a boiling point than when that liquid is at atmospheric pressure. For a given pressure, different liquids boil at different temperatures, for example, water boils at 100 °C at sea level, but at 93.4 °C at 2,000 metres altitude. The normal boiling point of a liquid is the case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level,1 atmosphere. At that temperature, the pressure of the liquid becomes sufficient to overcome atmospheric pressure. The standard boiling point has been defined by IUPAC since 1982 as the temperature at which boiling occurs under a pressure of 1 bar, the heat of vaporization is the energy required to transform a given quantity of a substance from a liquid into a gas at a given pressure. Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation, evaporation is a surface phenomenon in which molecules located near the liquids edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, a saturated liquid contains as much thermal energy as it can without boiling. The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase, the liquid can be said to be saturated with thermal energy. Any addition of energy results in a phase transition. If the pressure in a system remains constant, a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy is removed, similarly, a liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied. The boiling point corresponds to the temperature at which the pressure of the liquid equals the surrounding environmental pressure. Thus, the point is dependent on the pressure. Boiling points may be published with respect to the NIST, USA standard pressure of 101.325 kPa, at higher elevations, where the atmospheric pressure is much lower, the boiling point is also lower. The boiling point increases with increased pressure up to the critical point, the boiling point cannot be increased beyond the critical point. Likewise, the point decreases with decreasing pressure until the triple point is reached
4.
Temperature
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A temperature is an objective comparative measurement of hot or cold. It is measured by a thermometer, several scales and units exist for measuring temperature, the most common being Celsius, Fahrenheit, and, especially in science, Kelvin. Absolute zero is denoted as 0 K on the Kelvin scale, −273.15 °C on the Celsius scale, the kinetic theory offers a valuable but limited account of the behavior of the materials of macroscopic bodies, especially of fluids. Temperature is important in all fields of science including physics, geology, chemistry, atmospheric sciences, medicine. The Celsius scale is used for temperature measurements in most of the world. Because of the 100 degree interval, it is called a centigrade scale.15, the United States commonly uses the Fahrenheit scale, on which water freezes at 32°F and boils at 212°F at sea-level atmospheric pressure. Many scientific measurements use the Kelvin temperature scale, named in honor of the Scottish physicist who first defined it and it is a thermodynamic or absolute temperature scale. Its zero point, 0K, is defined to coincide with the coldest physically-possible temperature and its degrees are defined through thermodynamics. The temperature of zero occurs at 0K = −273. 15°C. For historical reasons, the triple point temperature of water is fixed at 273.16 units of the measurement increment, Temperature is one of the principal quantities in the study of thermodynamics. There is a variety of kinds of temperature scale and it may be convenient to classify them as empirically and theoretically based. Empirical temperature scales are historically older, while theoretically based scales arose in the middle of the nineteenth century, empirically based temperature scales rely directly on measurements of simple physical properties of materials. For example, the length of a column of mercury, confined in a capillary tube, is dependent largely on temperature. Such scales are only within convenient ranges of temperature. For example, above the point of mercury, a mercury-in-glass thermometer is impracticable. A material is of no use as a thermometer near one of its phase-change temperatures, in spite of these restrictions, most generally used practical thermometers are of the empirically based kind. Especially, it was used for calorimetry, which contributed greatly to the discovery of thermodynamics, nevertheless, empirical thermometry has serious drawbacks when judged as a basis for theoretical physics. Theoretically based temperature scales are based directly on theoretical arguments, especially those of thermodynamics, kinetic theory and they rely on theoretical properties of idealized devices and materials
5.
Vapor pressure
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Vapor pressure or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquids evaporation rate and it relates to the tendency of particles to escape from the liquid. A substance with a vapor pressure at normal temperatures is often referred to as volatile. The pressure exhibited by vapor present above a surface is known as vapor pressure. As the temperature of a liquid increases, the energy of its molecules also increases. As the kinetic energy of the molecules increases, the number of molecules transitioning into a vapor also increases, the vapor pressure of any substance increases non-linearly with temperature according to the Clausius–Clapeyron relation. The atmospheric pressure boiling point of a liquid is the temperature at which the pressure equals the ambient atmospheric pressure. With any incremental increase in temperature, the vapor pressure becomes sufficient to overcome atmospheric pressure. Bubble formation deeper in the liquid requires a pressure, and therefore higher temperature. More important at shallow depths, is the temperature required to start bubble formation. The surface tension of the wall lead to an overpressure in the very small initial bubbles. Thus, thermometer calibration should not rely on the temperature in boiling water, the vapor pressure that a single component in a mixture contributes to the total pressure in the system is called partial pressure. Vapor pressure is measured in the units of pressure. The International System of Units recognizes pressure as a unit with the dimension of force per area. One pascal is one newton per square meter, experimental measurement of vapor pressure is a simple procedure for common pressures between 1 and 200 kPa. Most accurate results are obtained near the point of substances. Better accuracy is achieved when care is taken to ensure that the entire substance and this is often done, as with the use of an isoteniscope, by submerging the containment area in a liquid bath. Very low vapor pressures of solids can be measured using the Knudsen effusion cell method, the Antoine equation is a mathematical expression of the relation between the vapor pressure and the temperature of pure liquid or solid substances
6.
Microorganism
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A microorganism or microbe is a microscopic organism, which may be single-celled or multicellular. The study of microorganisms is called microbiology, a subject that began with the discovery of microorganisms in 1674 by Antonie van Leeuwenhoek, microorganisms are very diverse and include all bacteria, archaea and most protozoa. This group also contains some fungi, algae, and some such as rotifers. Many macroscopic animals and plants have microscopic juvenile stages, some microbiologists classify viruses and viroids as microorganisms, but others consider these as nonliving. In July 2016, scientists identified a set of 355 genes from the last universal ancestor of all life, including microorganisms. Microorganisms, under certain test conditions, have observed to thrive in the vacuum of outer space. Microorganisms likely far outweigh all other living things combined, the mass of prokaryote microorganisms including the bacteria and archaea may be as much as 0.8 trillion tons of carbon, out of the total biomass of between 1 and 4 trillion tons. Microorganisms appear to thrive in the Mariana Trench, the deepest spot in the Earths oceans, in August 2014, scientists confirmed the existence of microorganisms living 800 m below the ice of Antarctica. According to one researcher, You can find microbes everywhere — theyre extremely adaptable to conditions, microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a part of the nitrogen cycle. Microorganisms are also exploited in biotechnology, both in food and beverage preparation, and in modern technologies based on genetic engineering. A small proportion of microorganisms are pathogenic, causing disease and even death in plants, Robert Hooke coined the term cell after viewing plant cells under his microscope. Antonie Van Leeuwenhoek was one of the first people to observe microorganisms in 1673, later, in the 19th century, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In 1876 Robert Koch discovered that microorganisms cause diseases, single-celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago. Further evolution was slow, and for about 3 billion years in the Precambrian eon, so, for most of the history of life on Earth, the only forms of life were microorganisms. Bacteria, algae and fungi have been identified in amber that is 220 million years old, microorganisms tend to have a relatively fast rate of evolution. Most microorganisms can reproduce rapidly, and bacteria are able to freely exchange genes through conjugation, transformation and transduction. This rapid evolution is important in medicine, as it has led to the development of multidrug resistant pathogenic bacteria, superbugs, the possible existence of microorganisms was discussed for many centuries before their discovery in the 17th century
7.
Nucleate boiling
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For water, as shown in the graph below, nucleate boiling occurs when the surface temperature is higher than the saturation temperature by between 10 °C to 30 °C. The critical heat flux is the peak on the curve between nucleate boiling and transition boiling, the heat transfer from surface to liquid is greater than that in film boiling. Two different regimes may be distinguished in the boiling range. When the temperature difference is between approximately 4 °C to 10 °C above TS, isolated bubbles form at nucleation sites and this separation induces considerable fluid mixing near the surface, substantially increasing the convective heat transfer coefficient and the heat flux. In this regime, most of the transfer is through direct transfer from the surface to the liquid in motion at the surface. Between 10 °C and 30 °C above TS, a flow regime may be observed. As more nucleation sites become active, increased bubble formation causes bubble interference and coalescence, in this region the vapor escapes as jets or columns which subsequently merge into slugs of vapor. Interference between the densely populated bubbles inhibits the motion of liquid near the surface and this is observed on the graph as a change in the direction of the gradient of the curve or an inflection in the boiling curve. When the relative increase in the difference is balanced by the relative reduction in the heat transfer coefficient. This is the heat flux. At this point in the maximum, considerable vapor is being formed and this causes the heat flux to reduce after this point. At extremes, film boiling commonly known as the Leidenfrost effect is observed, the bubbles grow until they reach some critical size, at which point they separate from the wall and are carried into the main fluid stream. There the bubbles collapse because the temperature of bulk fluid is not as high as at the heat transfer surface and this collapsing is also responsible for the sound a water kettle produces during heat up but before the temperature at which bulk boiling is reached. Heat transfer and mass transfer during nucleate boiling has a significant effect on the transfer rate. The effects of nucleate boiling take place at two locations, the interface the bubble-liquid interface The nucleate boiling process has a complex nature. Nucleate boiling phenomenon still requires more understanding, the nucleate boiling regime is important to engineers because of the high heat fluxes possible with moderate temperature differences. The bubble Reynolds number, R e b is defined as, R e b = D b G b μ L Where G b is the mass velocity of the vapor leaving the surface. Rohsenow has developed the first and most widely used correlation for nucleate boiling, C s f is the surface fluid combination and vary for various combinations of fluid and surface
8.
Nucleation
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Nucleation is the first step in the formation of either a new thermodynamic phase or a new structure via self-assembly or self-organization. Nucleation is typically defined to be the process that determines how long an observer has to wait before the new phase or self-organized structure appears, nucleation is often found to be very sensitive to impurities in the system. Because of this, it is important to distinguish between heterogeneous nucleation and homogeneous nucleation. Heterogeneous nucleation occurs at sites on surfaces in the system. Homogeneous nucleation occurs away from a surface, nucleation is usually a stochastic process, so even in two identical systems nucleation will occur at different times. This behaviour is similar to radioactive decay, a common mechanism is illustrated in the animation to the right. This shows nucleation of a new phase in an existing phase and this nucleus of the red phase then grows and converts the system to this phase. The standard theory that describes this behaviour for the nucleation of a new phase is called classical nucleation theory. This is seen for example in the nucleation of ice in supercooled water droplets. The decay rate of the exponential gives the nucleation rate, classical nucleation theory is a widely used approximate theory for estimating these rates, and how they vary with variables such as temperature. It correctly predicts that the time you have to wait for nucleation decreases extremely rapidly when supersaturated and it is not just new phases such as liquids and crystals that form via nucleation followed by growth. The self-assembly process that forms objects like the amyloid aggregates associated with Alzheimers disease also starts with nucleation, energy consuming self-organising systems such as the microtubules in cells also show nucleation and growth. Clouds form when wet air cools and many small water droplets nucleate from the supersaturated air, the amount of water vapor that air can carry decreases with lower temperatures. The excess vapor begins to nucleate and to small water droplets which form a cloud. Nucleation of the droplets of water is heterogeneous, occurring on particles referred to as cloud condensation nuclei. Cloud seeding is the process of adding artificial condensation nuclei to quicken the formation of clouds, nucleation is the first step in crystallisation, so it determines if a crystal can form. Frequently crystals do not form even when they are thermodynamically the favored state, for example, small droplets of very pure water can remain liquid down to below -30 °C although ice is the stable state below 0 °C. Bubbles of carbon dioxide nucleate shortly after the pressure is released from a container of carbonated liquid, nucleation often occurs more easily at a pre-existing interface, as happens on boiling chips and on string used to make rock candy
9.
Superheating
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This article is about the phenomenon where a liquid can exist in a metastable state above its boiling point. See superheated water for pressurized water above 100 °C, see superheater for the device used in steam engines. In physics, superheating is the phenomenon in which a liquid is heated to a higher than its boiling point. Superheating is achieved by heating a substance in a clean container, free of nucleation sites. Water is said to boil when bubbles of water vapor grow without bound, for a vapor bubble to expand, the temperature must be high enough that the vapor pressure exceeds the ambient pressure. Below that temperature, a vapor bubble will shrink and vanish. Superheating is an exception to this rule, a liquid is sometimes observed not to boil even though its vapor pressure does exceed the ambient pressure. The cause is a force, the surface tension, which suppresses the growth of bubbles. Surface tension makes the bubble act like a rubber balloon, the pressure inside is raised slightly by the skin attempting to contract. For the bubble to expand, the temperature must be raised slightly above the point to generate enough vapor pressure to overcome both surface tension and ambient pressure. What makes superheating so explosive is that a bubble is easier to inflate than a small one, just as when blowing up a balloon. It turns out the pressure due to surface tension is inversely proportional to the diameter of the bubble. This means if the largest bubbles in a container are only a few micrometres in diameter, once a bubble does begin to grow, the pressure due to the surface tension reduces, so it expands explosively. In practice, most containers have scratches or other imperfections which trap pockets of air that provide starting bubbles, but a container of liquid with only microscopic bubbles can superheat dramatically. Superheating can occur when a container of water is heated in a microwave oven. When the container is removed, the water appears to be below the boiling point. However, once the water is disturbed, some of it violently flashes to steam, the boiling can be triggered by jostling the cup, inserting a stirring device, or adding a substance like instant coffee or sugar. The chances of superheating are greater with smooth containers, because scratches or chips can house small pockets of air, which serve as nucleation points
10.
Bubble (physics)
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A bubble is a globule of one substance in another, usually gas in a liquid. Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance. g, for the physics and chemistry behind it, see nucleation. Humans can see bubbles because they have a different refractive index than the surrounding substance, for example, the IR of air is approximately 1.0003 and the IR of water is approximately 1.333. Nucleation can be induced, for example to create bubblegram. In medical ultrasound imaging, small encapsulated bubbles called contrast agent are used to enhance the contrast, in thermal inkjet printing, vapor bubbles are used as actuators. They are occasionally used in microfluidics applications as actuators. The violent collapse of bubbles near solid surfaces and the resulting impinging jet constitute the mechanism used in ultrasonic cleaning, the same effect, but on a larger scale, is used in focused energy weapons such as the bazooka and the torpedo. Pistol shrimp also use a collapsing cavitation bubble as a weapon, the same effect is used to treat kidney stones in a lithotripter. Marine mammals such as dolphins and whales use bubbles for entertainment or as hunting tools, aerators cause dissolution of gas in the liquid by injecting bubbles. Chemical and metallurgic engineers rely on bubbles for operations such as distillation, absorption, flotation, the complex processes involved often require consideration for mass and heat transfer, and are modelled using fluid dynamics. The star-nosed mole and the American water shrew can smell underwater by breathing through their nostrils. When bubbles are disturbed, they pulsate at their natural frequency, large bubbles undergo adiabatic pulsations, which means that no heat is transferred either from the liquid to the gas or vice versa. The damage can be due to deformation of tissues due to bubble growth in situ. This can occur as a result of decompression after hyperbaric exposure, a lung overexpansion injury, during intravenous fluid administration, or during surgery
11.
Cavitation
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Cavitation is the formation of vapour cavities in a liquid – i. e. small liquid-free zones – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to changes of pressure that cause the formation of cavities where the pressure is relatively low. When subjected to pressure, the voids implode and can generate an intense shock wave. Cavitation is a significant cause of wear in some engineering contexts, collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal causing a type of wear also called cavitation, the most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior, inertial cavitation and non-inertial cavitation, inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Inertial cavitation occurs in nature in the strikes of mantis shrimps and pistol shrimps, in man-made objects, it can occur in control valves, pumps, propellers and impellers. Non-inertial cavitation is the process in which a bubble in a fluid is forced to oscillate in size or shape due to form of energy input. Such cavitation is often employed in ultrasonic cleaning baths and can also be observed in pumps, propellers, since the shock waves formed by collapse of the voids are strong enough to cause significant damage to moving parts, cavitation is usually an undesirable phenomenon. It is very often specifically avoided in the design of such as turbines or propellers. However, it is useful and does not cause damage when the bubbles collapse away from machinery. Inertial cavitation was first studied by Lord Rayleigh in the late 19th century, when a volume of liquid is subjected to a sufficiently low pressure, it may rupture and form a cavity. This phenomenon is coined cavitation inception and may occur behind the blade of a rotating propeller or on any surface vibrating in the liquid with sufficient amplitude. A fast-flowing river can cause cavitation on rock surfaces, particularly there is a drop-off. Other ways of generating cavitation voids involve the local deposition of energy, vapor gases evaporate into the cavity from the surrounding medium, thus, the cavity is not a perfect vacuum, but has a relatively low gas pressure. Such a low-pressure bubble in a liquid begins to collapse due to the pressure of the surrounding medium. As the bubble collapses, the pressure and temperature of the vapor within increases, at the point of total collapse, the temperature of the vapor within the bubble may be several thousand kelvin, and the pressure several hundred atmospheres. Inertial cavitation can occur in the presence of an acoustic field
12.
Leidenfrost effect
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Due to this repulsive force, a droplet hovers over the surface rather than making physical contact with it. The effect is responsible for the ability of liquid nitrogen to skitter across floors. The latter is potentially lethal, particularly should one accidentally swallow the liquid nitrogen and it is named after Johann Gottlob Leidenfrost, who discussed it in A Tract About Some Qualities of Common Water in 1756. The effect can be seen as drops of water are sprinkled onto a pan at various times as it heats up. Initially, as the temperature of the pan is just below 100 °C, the water out and slowly evaporates, or if the temperature of the pan is well below 100 °C. As the temperature of the pan goes above 100 °C, the water droplets hiss when touching the pan, later, as the temperature exceeds the Leidenfrost point, the Leidenfrost effect comes into play. On contact with the pan, the water droplets bunch up into balls of water and skitter around. This effect works until a higher temperature causes any further drops of water to evaporate too quickly to cause this effect. This is because at temperatures above the Leidenfrost point, the part of the water droplet vaporizes immediately on contact with the hot plate. The resulting gas suspends the rest of the water droplet just above it, as steam has much poorer thermal conductivity, further heat transfer between the pan and the droplet is slowed down dramatically. This also results in the drop being able to skid around the pan on the layer of gas just under it, the temperature at which the Leidenfrost effect begins to occur is not easy to predict. Some research has been conducted into a model of the system. As a very rough estimate, the Leidenfrost point for a drop of water on a frying pan might occur at 193 °C. In a pair of lectures on design, he cited the work of Pierre Hippolyte Boutigny and Professor Bowman of Kings College. A drop of water that was vaporized almost immediately at 168 °C persisted for 152 seconds at 202 °C, lower temperatures in a boiler firebox might evaporate water more quickly as a result, compare Mpemba effect. An alternative approach was to increase the temperature beyond the Leidenfrost point, fairbairn considered this too, and may have been contemplating the flash steam boiler, but considered the technical aspects insurmountable for the time. The Leidenfrost point may also be taken to be the temperature for which the hovering droplet lasts longest and it has been demonstrated that it is possible to stabilize the Leidenfrost vapour layer of water by exploiting superhydrophobic surfaces. In this case, once the layer is established, cooling never collapses the layer, and no nucleate boiling occurs
13.
Thermal conductivity
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In physics, thermal conductivity is the property of a material to conduct heat. It is evaluated primarily in terms of Fouriers Law for heat conduction, heat transfer occurs at a lower rate across materials of low thermal conductivity than across materials of high thermal conductivity. Correspondingly, materials of high thermal conductivity are used in heat sink applications. The thermal conductivity of a material may depend on temperature, the reciprocal of thermal conductivity is called thermal resistivity. Thermal conductivity is actually a tensor, which means it is possible to have different values in different directions, in SI units, thermal conductivity is measured in watts per meter-kelvin. The dimension of thermal conductivity is M1L1T−3Θ−1 and these variables are mass, length, time, and temperature. In Imperial units, thermal conductivity is measured in BTU/, other units which are closely related to the thermal conductivity are in common use in the construction and textile industries. The construction industry makes use of such as the R-value. Although related to the conductivity of a material used in an insulation product, R-. Likewise the textile industry has several units including the tog and the clo which express thermal resistance of a material in a way analogous to the R-values used in the construction industry, there are a number of ways to measure thermal conductivity. Each of these is suitable for a range of materials, depending on the thermal properties. There is a distinction between steady-state and transient techniques, in general, steady-state techniques are useful when the temperature of the material does not change with time. This makes the signal analysis straightforward, the disadvantage is that a well-engineered experimental setup is usually needed. The Divided Bar is the most common used for consolidated rock solids. Thermal conductivity is important in science, research, electronics, building insulation and related fields. Several materials are shown in the list of thermal conductivities and these should be considered approximate due to the uncertainties related to material definitions. High energy generation rates within electronics or turbines require the use of materials with high thermal conductivity such as copper, aluminium, the reciprocal of thermal conductivity is thermal resistivity, usually expressed in kelvin-meters per watt. For a given thickness of a material, that particular constructions thermal resistance, unfortunately, there are differing definitions for these terms
14.
Distillation
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Distillation is a process of separating the component or substances from a liquid mixture by selective evaporation and condensation. Distillation may result in complete separation, or it may be a partial separation that increases the concentration of selected components of the mixture. In either case the process exploits differences in the volatility of the mixtures components, in industrial chemistry, distillation is a unit operation of practically universal importance, but it is a physical separation process and not a chemical reaction. For example, In the fossil fuel industry distillation is a class of operation in obtaining materials from crude oil for fuels. Distillation permits separation of air into its components — notably oxygen, nitrogen, Distillation of fermented products produces distilled beverages with a high alcohol content, or separates out other fermentation products of commercial value. An installation for distillation, especially of alcohol, is a distillery, the distillation equipment is a still. Distillation is an old method of artificial desalination. Aristotle wrote about the process in his Meteorologica and even that ordinary wine possesses a kind of exhalation, later evidence of distillation comes from Greek alchemists working in Alexandria in the 1st century AD. Distilled water has been known since at least c,200, when Alexander of Aphrodisias described the process. Work on distilling other liquids continued in early Byzantine Egypt under the Greek-Egyptian Zosimus of Panopolis, Distillation in China could have begun during the Eastern Han Dynasty, but archaeological evidence indicates that actual distillation of beverages began in the Jin and Southern Song dynasties. A still was found in a site in Qinglong, Hebei province dating to the 12th century. Distilled beverages were more common during the Yuan dynasty, arabs learned the process from the Alexandrians and used it extensively in their chemical experiments. Clear evidence of the distillation of alcohol comes from the School of Salerno in the 12th century, fractional distillation was developed by Tadeo Alderotti in the 13th century. In 1500, German alchemist Hieronymus Braunschweig published Liber de arte destillandi the first book dedicated to the subject of distillation. In 1651, John French published The Art of Distillation the first major English compendium of practice and this includes diagrams with people in them showing the industrial rather than bench scale of the operation. As alchemy evolved into the science of chemistry, vessels called retorts became used for distillations, riveted joints were often kept tight by using various mixtures, for instance a dough made of rye flour. These alembics often featured a system around the beak, using cold water for instance. Today, the retorts and pot stills have largely supplanted by more efficient distillation methods in most industrial processes
15.
Gastrointestinal tract
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Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines. A tract is a collection of related anatomic structures or a series of connected body organs, the mouth, oesophagus, stomach, and intestines are part of the human alimentary canal. All bilaterians have a gastrointestinal tract, also called a gut or an alimentary canal and this is a tube that transfers food to the organs of digestion. In large bilaterians, the gastrointestinal tract generally also has an exit, some small bilaterians have no anus and dispose of solid wastes by other means. The gastrointestinal tract contains thousands of different bacteria in their gut flora, the human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is divided into the upper and lower gastrointestinal tracts. In contrast, the digestive system comprises the gastrointestinal tract plus the accessory organs of digestion. The tract may also be divided into foregut, midgut, and hindgut, the whole human GI tract is about nine metres long at autopsy. The GI tract releases hormones from enzymes to help regulate the digestive process, the structure and function can be described both as gross anatomy and as microscopic anatomy or histology. The tract itself is divided into upper and lower tracts, the upper gastrointestinal tract consists of the buccal cavity, pharynx, esophagus, stomach, and duodenum. The exact demarcation between the upper and lower tracts is the muscle of the duodenum. Upon dissection, the duodenum may appear to be an organ, but it is divided into four segments based upon function, location. The four segments of the duodenum are as follows, bulb, descending, horizontal, the suspensory muscle attaches the superior border of the ascending duodenum to the diaphragm. The suspensory muscle is an important anatomical landmark which shows the division between the duodenum and the jejunum, the first and second parts of the small intestine. This is a muscle which is derived from the embryonic mesoderm. The lower gastrointestinal tract includes most of the intestine and all of the large intestine. In humans, the intestine is further subdivided into the duodenum, jejunum and ileum while the large intestine is subdivided into the cecum, colon, rectum. The small intestine begins at the duodenum, which receives food from the stomach and it is a tubular structure, usually between 6 and 7 m long. The area of the human, adult small intestinal mucosa is about 30 m2 and its main function is to absorb the products of digestion into the bloodstream
16.
Water purification
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Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids and gases from contaminated water. The goal is to produce water fit for a specific purpose, the standards for drinking water quality are typically set by governments or by international standards. These standards usually include minimum and maximum concentrations of contaminants, depending on the purpose of water use. Visual inspection cannot determine if water is of appropriate quality, simple procedures such as boiling or the use of a household activated carbon filter are not sufficient for treating all the possible contaminants that may be present in water from an unknown source. Even natural spring water – considered safe for all purposes in the 19th century – must now be tested before determining what kind of treatment. Chemical and microbiological analysis, while expensive, are the way to obtain the information necessary for deciding on the appropriate method of purification. The WHO estimates that 94% of these cases are preventable through modifications to the environment. Simple techniques for treating water at home, such as chlorination, filters, and solar disinfection, reducing deaths from waterborne diseases is a major public health goal in developing countries. Groundwater, The water emerging from deep ground water may have fallen as rain many tens, hundreds. Such water may emerge as springs, artesian springs, or may be extracted from boreholes or wells, deep ground water is generally of very high bacteriological quality, but the water may be rich in dissolved solids, especially carbonates and sulfates of calcium and magnesium. Depending on the strata through which the water has flowed, other ions may also be present including chloride, there may be a requirement to reduce the iron or manganese content of this water to make it acceptable for drinking, cooking, and laundry use. Primary disinfection may also be required, where groundwater recharge is practised, the groundwater may require additional treatment depending on applicable state and federal regulations. Bacteria and pathogen levels are low, but some bacteria. Where uplands are forested or peaty, humic acids can colour the water, many upland sources have low pH which require adjustment. Rivers, canals and low land reservoirs, Low land surface waters will have a significant bacterial load and may also contain algae, suspended solids and a variety of dissolved constituents. Atmospheric water generation is a new technology that can provide high quality drinking water by extracting water from the air by cooling the air, desalination of seawater by distillation or reverse osmosis. Surface Water, Freshwater bodies that are open to the atmosphere and are not designated as groundwater are termed surface waters. The aims of the treatment are to remove unwanted constituents in the water, the choice of method will depend on the quality of the water being treated, the cost of the treatment process and the quality standards expected of the processed water
17.
Rate equation
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The rate law or rate equation for a chemical reaction is an equation that links the reaction rate with the concentrations or pressures of the reactants and constant parameters. For many reactions the rate is given by a law such as r = k x y where and express the concentration of the species A and B. The exponents x and y are the partial orders and must be determined experimentally. The constant k is the rate constant or rate coefficient of the reaction. The value of this coefficient k may depend on such as temperature, ionic strength, surface area of an adsorbent. For elementary reactions, which consist of a step, the order equals the molecularity as predicted by collision theory. For example, an elementary reaction A + B → products will be second order overall and first order in each reactant. For multistep reactions, the order of each step equals the molecularity, the equation may involve a fractional order, and may depend on the concentration of an intermediate species. The rate equation is an equation and can be integrated to obtain an integrated rate equation that links concentrations of reactants or products with time. A zero order reaction has a rate that is independent of the concentration of the reactant, increasing the concentration of the reacting species will not speed up the rate of the reaction i. e. the amount of substance reacted is proportional to the time. Zero order reactions are found when a material that is required for the reaction to proceed. The rate law for a zero order reaction is r = k where r is the reaction rate, T = − k t +0 where t represents the concentration of the chemical of interest at a particular time, and 0 represents the initial concentration. A reaction is zero order if concentration data are plotted versus time, a plot of t vs. time t gives a straight line with a slope of − k. The half-life of a reaction describes the time needed for half of the reactant to be depleted, a first order reaction depends on the concentration of only one reactant. Other reactants can be present, but each will be zero order, the rate law for a reaction that is first order with respect to a reactant A is − d d t = r = k k is the first order rate constant, which has units of 1/s. The integrated first order rate law is ln = − k t + ln 0 A plot of ln vs. time t gives a line with a slope of − k. The half-life of a first order reaction is independent of the concentration and is given by t 12 = ln k. This equation indicates that the fraction of the amount of reactant population that will break down in each time period is independent of the initial amount present
18.
Giardia
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Giardia is a genus of anaerobic flagellated protozoan parasites of the phylum Sarcomastigophora that colonise and reproduce in the small intestines of several vertebrates, causing giardiasis. Their life cycle alternates between an actively swimming trophozoite and an infective, resistant cyst, Giardia were first described by the Dutch microscopist Antonie van Leeuwenhoek in 1681. The genus is named after French zoologist Alfred Mathieu Giard, like other diplomonads, Giardia have two nuclei, each with four associated flagella, and were thought to lack both mitochondria and a Golgi apparatus. However they are now known to possess a complex system as well as mitochondrial remnants, called mitosomes. The mitosomes are not used in ATP synthesis the way mitochondria are, the synapomorphies of genus Giardia include cells with duplicate organelles, absence of cytostomes, and ventral adhesive disc. The symptoms of Giardia, which may begin to appear 2 days after infection, include violent diarrhea, excess gas, stomach or abdominal cramps, upset stomach, resulting dehydration and nutritional loss may need immediate treatment. A typical infection can be slight, resolve without treatment, coexistence with the parasite is possible, but an infected individual can remain a carrier and transmit it to others. Medication containing tinidazole or metronidazole decreases symptoms and time to resolution, albendazole is also used, and has an anti-helmintic property as well, ideal for certain compounded issues when a general vermicidal agent is preferred. Giardia causes a disease called Giardiasis, which causes the villi of the intestine to atrophy and flatten. Lactose intolerance can persist after the eradication of Giardia from the digestive tract, person-to-person transmission accounts for the majority of Giardia infections and is usually associated with poor hygiene and sanitation. Giardia is found on the surface of the ground, in the soil, in undercooked foods, water-borne transmission is associated with the ingestion of contaminated water. In the U. S. outbreaks typically occur in water systems using inadequately treated surface water. Venereal transmission happens through fecal-oral contamination, additionally, diaper changing and inadequate hand washing are risk factors for transmission from infected children. Lastly, food-borne epidemics of Giardia have developed through the contamination of food by infected food-handlers, the CDC recommends hand-washing and avoiding potentially contaminated food and untreated water. Boiling suspect water for one minute is the surest method to make water safe to drink, chemical disinfectants or filters may be used. According to a review of the literature from 2000, there is evidence linking the drinking of water in the N. The researcher notes that treatment of drinking water for Giardia may not be as important as recommended hand-washing in wilderness regions in North America, CDC surveillance data reports one outbreak of waterborne giardiasis contracted from drinking wilderness river water in Colorado. However, less than 1% of reported cases are associated with outbreaks
19.
Escherichia coli
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Escherichia coli is a gram-negative, facultatively anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms. Most E. coli strains are harmless, but some serotypes can cause food poisoning in their hosts. The harmless strains are part of the flora of the gut, and can benefit their hosts by producing vitamin K2. E. coli is expelled into the environment within fecal matter, the bacterium grows massively in fresh fecal matter under aerobic conditions for 3 days, but its numbers decline slowly afterwards. E. coli and other facultative anaerobes constitute about 0. 1% of gut flora, cells are able to survive outside the body for a limited amount of time, which makes them potential indicator organisms to test environmental samples for fecal contamination. A growing body of research, though, has examined environmentally persistent E. coli which can survive for extended periods outside of a host, the bacterium can be grown and cultured easily and inexpensively in a laboratory setting, and has been intensively investigated for over 60 years. E. coli is a chemoheterotroph whose chemically defined medium must include a source of carbon, under favorable conditions, it takes only 20 minutes to reproduce. E. coli is a Gram-negative, facultative anaerobic and nonsporulating bacterium, cells are typically rod-shaped, and are about 2.0 μm long and 0. 25–1.0 μm in diameter, with a cell volume of 0. 6–0.7 μm3. E. coli stains Gram-negative because its cell wall is composed of a peptidoglycan layer. During the staining process, E. coli picks up the color of the counterstain safranin, the outer membrane surrounding the cell wall provides a barrier to certain antibiotics such that E. coli is not damaged by penicillin. Strains that possess flagella are motile, the flagella have a peritrichous arrangement. E. coli can live on a variety of substrates and uses mixed-acid fermentation in anaerobic conditions, producing lactate, succinate, ethanol, acetate. Optimum growth of E. coli occurs at 37 °C, and it uses oxygen when it is present and available. It can, however, continue to grow in the absence of oxygen using fermentation or anaerobic respiration, the ability to continue growing in the absence of oxygen is an advantage to bacteria because their survival is increased in environments where water predominates. The bacterial cell cycle is divided into three stages, the B period occurs between the completion of cell division and the beginning of DNA replication. The C period encompasses the time it takes to replicate the chromosomal DNA, the D period refers to the stage between the conclusion of DNA replication and the end of cell division. The doubling rate of E. coli is higher when more nutrients are available, However, the length of the C and D periods do not change, even when the doubling time becomes less than the sum of the C and D periods. At the fastest growth rates, replication begins before the round of replication has completed, resulting in multiple replication forks along the DNA
20.
Vibrio cholerae
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Vibrio cholerae is a Gram-negative, comma-shaped bacterium. The bacteriums natural habitat is brackish or saltwater, some strains of V. cholerae cause the disease cholera. V. cholerae is a facultative anaerobe and has a flagellum at one cell pole as well as pili, V. cholerae can undergo respiratory and fermentative metabolism. When ingested, V. cholerae can cause diarrhea and vomiting in a host within several hours to 2–3 days of ingestion, V. V. cholerae is Gram-negative and comma-shaped. Initial isolates are slightly curved, whereas they can appear as straight rods upon laboratory culturing, the bacterium has a flagellum at one cell pole as well as pili. V. cholerae is a facultative anaerobe, and can undergo respiratory, V. cholerae pathogenicity genes code for proteins directly or indirectly involved in the virulence of the bacteria. During infection, V. cholerae secretes cholera toxin, a protein that causes profuse, colonization of the small intestine also requires the toxin coregulated pilus, a thin, flexible, filamentous appendage on the surface of bacterial cells. V. cholerae can cause syndromes ranging from asymptomatic to cholera gravis, in endemic areas, 75% of cases are asymptomatic, 20% are mild to moderate, and 2-5% are severe forms such as cholera gravis. Symptoms include abrupt onset of diarrhea, occasional vomiting. Death due to dehydration can occur in a few hours to days in untreated children, the disease is also particularly dangerous for pregnant women and their fetuses during late pregnancy, as it may cause premature labor and fetal death. In cases of cholera gravis involving severe dehydration, up to 60% of patients can die, however, the disease typically lasts 4–6 days. In 2002, the WHO deemed that the case fatality ratio for cholera was about 3. 95%, V. cholerae has two circular chromosomes, together totalling 4 million base pairs of DNA sequence and 3,885 predicted genes. The genes for cholera toxin are carried by CTXphi, a temperate bacteriophage inserted into the V. cholerae genome, CTXφ can transmit cholera toxin genes from one V. cholerae strain to another, one form of horizontal gene transfer. The genes for toxin coregulated pilus are coded by the VPI pathogenicity island, the entire genome of the virulent strain V. cholerae El Tor N16961 has been sequenced, and contains two circular chromosomes. Chromosome 1 has 2,961,149 base pairs with 2,770 open reading frames, the larger first chromosome contains the crucial genes for toxicity, regulation of toxicity, and important cellular functions, such as transcription and translation. Also relevant in determining if the replicon is a chromosome is whether it represents a significant percentage of the genome, and, unlike plasmids, chromosomes are not self-transmissible. However, the chromosome may have once been a megaplasmid because it contains some genes usually found on plasmids. V. cholerae contains an island of pathogenicity and is lysogenized with phage DNA
21.
Clostridium
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They are obligate anaerobes capable of producing endospores. The normal, reproducing cells of Clostridium, called the form, are rod-shaped. Clostridium endospores have a bowling pin or bottle shape, distinguishing them from other bacterial endospores. Clostridium species inhabit soils and the tract of animals, including humans. Clostridium is a inhabitant of the healthy lower reproductive tract of women. Clostridium contains around 100 species that include common free-living bacteria, as well as important pathogens, the main species responsible for disease in humans are, Clostridium botulinum can produce botulinum toxin in food or wounds and can cause botulism. This same toxin is known as Botox and is used in surgery to paralyze facial muscles to reduce the signs of aging. Clostridium difficile can flourish when other gut flora bacteria are killed during antibiotic therapy, leading to superinfection, Clostridium perfringens causes a wide range of symptoms, from food poisoning to cellulitis, fasciitis, and gas gangrene. Clostridium sordellii can cause an infection in exceptionally rare cases after medical abortions. Bacillus and Clostridium are often described as gram-variable, because they show a number of gram-negative cells as the culture ages. Clostridium and Bacillus are both in the division Firmicutes, but they are in different classes, orders, and families, microbiologists distinguish Clostridium from Bacillus by the following features, Clostridium grows in anaerobic conditions, Bacillus grows in aerobic conditions. Clostridium forms bottle-shaped endospores, Bacillus forms oblong endospores, Clostridium does not form the enzyme catalase, Bacillus secretes catalase to destroy toxic byproducts of oxygen metabolism. Clostridium and Desulfotomaculum are both in the class Clostridia and order Clostridiales, and they both produce bottle-shaped endospores, but they are in different families, Clostridium can be distinguished from Desulfotomaculum on the basis of the nutrients each genus uses. Glycolysis and fermentation of pyruvic acid by Clostridia yield the end products butyric acid, butanol, acetone, isopropanol, the Schaeffer-Fulton stain can be used to distinguish endospores of Bacillus and Clostridium from other microorganisms. There is a commercially available polymerase chain reaction test kit for the detection of C. perfringens, in general, the treatment of clostridial infection is high-dose penicillin G, to which the organism has remained susceptible. Clostridium welchii and Clostridium tetani respond to sulfonamides, Clostridia are also susceptible to tetracyclines, carbapenems, metronidazole, vancomycin, and chloramphenicol. The vegetative cells of Clostridia are heat-labile and are killed by short heating at temperatures above 72–75 °C, the thermal destruction of Clostridium spores requires higher temperatures and longer cooking times. The addition of lysozyme, nitrate, nitrite and propionic acid salts inhibits Clostridia in various foods, in the late 1700s, Germany experienced a number of outbreaks of an illness that seemed connected to eating certain sausages
22.
Sterilization (microbiology)
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Sterilization can be achieved through various means, including, heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization in that kills, deactivates, or eliminates all forms of life. Canning of foods is an extension of the principle, and has helped to reduce food borne illness. Other methods of sterilizing foods include food irradiation and high pressure, in general, surgical instruments and medications that enter an already aseptic part of the body must be sterile. Examples of such instruments include scalpels, hypodermic needles and artificial pacemakers and this is also essential in the manufacture of parenteral pharmaceuticals. Most medical and surgical devices used in healthcare facilities are made of materials that are able to go under steam sterilization, however, since 1950, there has been an increase in medical devices and instruments made of materials that require low-temperature sterilization. Ethylene oxide gas has been used since the 1950s for heat-, within the past 15 years, a number of new, low-temperature sterilization systems have been developed and are being used to sterilize medical devices. ]Steam sterilization is the most widely used and the most dependable. Steam sterilization is nontoxic, inexpensive, rapidly microbicidal, sporicidal, there are strict international rules to protect the contamination of Solar System bodies from biological material from Earth. Standards vary depending on both the type of mission and its destination, the more likely a planet is considered to be habitable, the aim of sterilization is the reduction of initially present microorganisms or other potential pathogens. The degree of sterilization is commonly expressed by multiples of the decimal reduction time, or D-value, then the number of microorganisms N after sterilization time t is given by, N N0 =10. The D-value is a function of sterilization conditions and varies with the type of microorganism, temperature, water activity, for steam sterilization typically the temperature is given as index. Theoretically, the likelihood of survival of an individual microorganism is never zero, to compensate for this, the overkill method is often used. Using the overkill method, sterilization is performed by sterilizing for longer than is required to kill the present on or in the item being sterilized. This provides a sterility assurance level equal to the probability of a non-sterile unit, for high-risk applications such as medical devices and injections, a sterility assurance level of at least 10−6 is required by the United States Food and Drug Administration. A widely used method for heat sterilization is the autoclave, sometimes called a converter or steam sterilizer, autoclaves use steam heated to 121-134 °C under pressure. To achieve sterility, the article is heated in a chamber by injected steam until the article reaches a time, meantime almost all the air is removed from the chamber, because air is undesired in the moist heat sterilization process. The article is then held at that setpoint for a period of time varies depending on the bioburden present on the article being sterilized. Following sterilization, liquids in a pressurized autoclave must be cooled slowly to avoid boiling over when the pressure is released and this may be achieved by gradually depressurizing the sterilization chamber and allowing liquids to evaporate under a negative pressure, while cooling the contents
23.
Thermometer
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A thermometer is a device that measures temperature or a temperature gradient. A thermometer has two important elements, a sensor in which some physical change occurs with temperature. Thermometers are widely used in industry to control and regulate processes, in the study of weather, in medicine, there are various principles by which different thermometers operate. They include the expansion of solids or liquids with temperature. Radiation-type thermometers measure the energy emitted by an object, allowing measurement of temperature without contact. Most metals are good conductors of heat and they are solids at room temperature, Mercury is the only one in liquid state at room temperature, and has high coefficient of expansion. Hence, the slightest change in temperature is notable when its used in a thermometer and this is the reason behind mercury and alcohol being used in thermometer. Some of the principles of the thermometer were known to Greek philosophers of two years ago. The modern thermometer gradually evolved from the thermoscope with the addition of a scale in the early 17th century, while an individual thermometer is able to measure degrees of hotness, the readings on two thermometers cannot be compared unless they conform to an agreed scale. Today there is a thermodynamic temperature scale. Internationally agreed temperature scales are designed to approximate this closely, based on fixed points, the most recent official temperature scale is the International Temperature Scale of 1990. It extends from 0.65 K to approximately 1,358 K, various authors have credited the invention of the thermometer to Hero of Alexandria. The thermometer was not an invention, however, but a development. The expansion and contraction of the air caused the position of the interface to move along the tube. Such a mechanism was used to show the hotness and coldness of the air with a tube in which the water level is controlled by the expansion and contraction of the gas. These devices were developed by several European scientists in the 16th and 17th centuries, as a result, devices were shown to produce this effect reliably, and the term thermoscope was adopted because it reflected the changes in sensible heat. The difference between a thermoscope and a thermometer is that the latter has a scale, though Galileo is often said to be the inventor of the thermometer, what he produced were thermoscopes. The first clear diagram of a thermoscope was published in 1617 by Giuseppe Biancani and this was a vertical tube, closed by a bulb of air at the top, with the lower end opening into a vessel of water
24.
Pasta
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Pasta is a staple food of traditional Italian cuisine, with the first reference dating to 1154 in Sicily. It can also be made with flour from other cereals or grains, pastas may be divided into two broad categories, dried and fresh. Most dried pasta is produced via an extrusion process although it can be produced in most homes. Both dried and fresh pasta come in a number of shapes and varieties, in Italy the names of specific pasta shapes or types often vary with locale. For example, the form cavatelli is known by 28 different names depending on region, common forms of pasta include long shapes, short shapes, tubes, flat shapes and sheets, miniature soup shapes, filled or stuffed and specialty or decorative shapes. As a category in Italian cuisine, both fresh and dried pastas are classically used in one of three kinds of prepared dishes, as pasta asciutta cooked pasta is plated and served with a complementary sauce or condiment. A second classification of pasta dishes is pasta in brodo in which the pasta is part of a soup-type dish, a third category is pasta al forno in which the pasta incorporated into a dish that is subsequently baked. Pasta is generally a dish, but comes in many varieties due to its versatility. Some pasta dishes are served as a first course in Italy because the portion sizes are small, Pasta is also prepared in light lunches, such as salads or large portion sizes for dinner. It can be prepared by hand or food processor and served hot or cold, Pasta sauces vary in taste, color and texture. When choosing which type of pasta and sauce to serve together, simple sauces like pesto are ideal for long and thin strands of pasta while tomato sauce combines well with thicker pastas. Thicker and chunkier sauces have the ability to cling onto the holes and cuts of short, tubular. The extra sauce left on the plate after all of the pasta is eaten is often mopped up with a piece of bread. First attested in English in 1874, the word comes from Italian pasta, in turn from Latin pasta dough, pastry cake. In the 1st century AD writings of Horace, lagana were fine sheets of fried dough and were an everyday foodstuff, an early 5th century cookbook describes a dish called lagana that consisted of layers of dough with meat stuffing, a possible ancestor of modern-day lasagna. The first concrete information concerning pasta products in Italy dates from the 13th or 14th century, historians have noted several lexical milestones relevant to pasta, none of which changes these basic characteristics. For example, the works of the 2nd century AD Greek physician Galen mention itrion, homogeneous compounds made of flour, the Jerusalem Talmud records that itrium, a kind of boiled dough, was common in Palestine from the 3rd to 5th centuries AD. A dictionary compiled by the 9th century Arab physician and lexicographer Isho bar Ali defines itriyya and its ever-flowing streams propel a number of mills
25.
Cooking
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Cooking or cookery is the art, technology and craft of preparing food for consumption with the use of heat. The ways or types of cooking also depend on the skill, cooking is done both by people in their own dwellings and by professional cooks and chefs in restaurants and other food establishments. Cooking can also occur through chemical reactions without the presence of heat, such as in ceviche, preparing food with heat or fire is an activity unique to humans. It may have started around 2 million years ago, though evidence for it reaches no more than 1 million years ago. The expansion of agriculture, commerce, trade and transportation between civilizations in different regions offered cooks many new ingredients, New inventions and technologies, such as the invention of pottery for holding and boiling water, expanded cooking techniques. Some modern cooks apply advanced scientific techniques to food preparation to further enhance the flavor of the dish served, phylogenetic analysis suggests that human ancestors may have invented cooking as far back as 1.8 million to 2.3 million years ago. Re-analysis of burnt bone fragments and plant ashes from the Wonderwerk Cave, there is evidence that Homo erectus was cooking their food as early as 500,000 years ago. Evidence for the use of fire by Homo erectus beginning some 400,000 years ago has wide scholarly support. Archeological evidence, from 300,000 years ago, in the form of ancient hearths, earth ovens, burnt animal bones, and flint, are found across Europe, anthropologists think that widespread cooking fires began about 250,000 years ago, when hearths started appearing. More recently, the earliest hearths have been reported to be at least 790,000 years old, in the seventeenth and eighteenth centuries, food was a classic marker of identity in Europe. In the nineteenth-century Age of Nationalism cuisine became a symbol of national identity. Communication between the Old World and the New World in the Colombian exchange influenced the history of cooking, the Industrial Revolution brought mass-production, mass-marketing and standardization of food. Factories processed, preserved, canned, and packaged a wide variety of foods, in the 1920s, freezing methods, cafeterias and fast-food establishments emerged. Along with changes in food, starting early in the 20th century, governments have issued nutrition guidelines, the 1916 Food For Young Children became the first USDA guide to give specific dietary guidelines. Updated in the 1920s, these guides gave shopping suggestions for different-sized families along with a Depression Era revision which included four cost levels, in 1943, the USDA created the Basic Seven chart to make sure that people got the recommended nutrients. It included the first-ever Recommended Daily Allowances from the National Academy of Sciences, in 1956, the Essentials of an Adequate Diet brought recommendations which cut the number of groups that American school children would learn about down to four. In 1979, a guide called Food addressed the link between too much of certain foods and chronic diseases, but added fats, oils, most ingredients in cooking are derived from living organisms. Vegetables, fruits, grains and nuts as well as herbs and spices come from plants, while meat, eggs, mushrooms and the yeast used in baking are kinds of fungi
26.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
27.
Stock (food)
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Stock is a flavored liquid preparation. It forms the basis of many dishes, particularly soups and sauces, making stocks involves simmering animal bones or meat, seafood, or vegetables in water or wine, adding mirepoix or other aromatics for more flavor. Traditionally, stock is made by simmering various ingredients in water, a newer approach is to use a pressure cooker. The ingredients may include some or all of the following, Meat Leftover cooked meat, quantities recommended are in the ratio of 1 part fresh meat to 2 parts water. Bones Veal, beef, and chicken bones are most commonly used, the flavour of the stock comes from the cartilage and connective tissue in the bones. Connective tissue has collagen in it, which converted into gelatin that thickens the liquid. Stock made from bones needs to be simmered for longer than stock made from meat, pressure cooking methods shorten the time necessary to extract the flavour from the bones. Mirepoix Mirepoix is a combination of onions, carrots, celery, often, the less desirable parts of the vegetables that may not otherwise be eaten are used. The use of parts is highly dependent upon the chef. Herbs and spices The herbs and spices used depend on availability, in classical cuisine, the use of a bouquet garni consisting of parsley, bay leaves, a sprig of thyme, and possibly other herbs, is common. This is often placed in a sachet to make it easier to remove once the stock is cooked, today, ready-made stock and stock cubes consisting of dried, compressed stock ingredients are readily available. These are commonly known as bouillon cubes, as cooking base in the US, or as Oxo cubes in Britain, the difference between broth and stock is one of both cultural and colloquial terminology but certain definitions prevail. Stock is the liquid produced by simmering raw ingredients, solids are removed and this yields classic stock as made from beef, veal, chicken, fish and vegetables. Broth differs in that it is a soup where the solid pieces of flavoring meat or fish, along with some vegetables. It is often made more substantial by adding starches such as rice, traditionally, broth contained some form of meat or fish, however, nowadays it is acceptable to refer to a strictly vegetable soup as a broth. Chicken stock is cooked for several hours. Fish stock is made with fish bones and finely chopped mirepoix, fish stock should be cooked for 20–25 minutes—cooking any longer spoils the flavour. Concentrated fish stock is called fish fumet, in Japanese cooking, a fish and kelp stock called dashi is made by briefly cooking skipjack tuna flakes called katsuobushi in nearly boiling water
28.
Milk
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Milk is a pale liquid produced by the mammary glands of mammals. It is the source of nutrition for infant mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mothers antibodies to its young and it contains many other nutrients including protein and lactose. As an agricultural product, milk is extracted from non-human mammals during or soon after pregnancy, Dairy farms produced about 730 million tonnes of milk in 2011, from 260 million dairy cows. India is the worlds largest producer of milk, and is the leading exporter of skimmed milk powder, the ever increasing rise in domestic demand for dairy products and a large demand-supply gap could lead to India being a net importer of dairy products in the future. The United States, India, China and Brazil are the worlds largest exporters of milk and milk products, China and Russia were the worlds largest importers of milk and milk products until 2016 when both countries became self-sufficient, contributing to a worldwide glut of milk. Throughout the world, there are more than six billion consumers of milk and milk products, over 750 million people live in dairy farming households. The term milk comes from Old English meoluc, milc, from Proto-Germanic *meluks milk, there are two distinct types of milk consumption, a natural source of nutrition for all infant mammals and a food product for humans of all ages that is derived from other animals. In almost all mammals, milk is fed to infants through breastfeeding, the early milk from mammals is called colostrum. Colostrum contains antibodies that provide protection to the baby as well as nutrients. The makeup of the colostrum and the period of secretion varies from species to species, for humans, the World Health Organization recommends exclusive breastfeeding for six months and breastfeeding in addition to other food for at least two years. In some cultures it is common to breastfeed children for three to five years, and the period may be longer, fresh goats milk is sometimes substituted for breast milk. This introduces the risk of the child developing electrolyte imbalances, metabolic acidosis, megaloblastic anemia, in many cultures of the world, especially the West, humans continue to consume milk beyond infancy, using the milk of other animals as a food product. Initially, the ability to digest milk was limited to children as adults did not produce lactase, Milk was therefore converted to curd, cheese and other products to reduce the levels of lactose. Thousands of years ago, a chance mutation spread in human populations in Europe that enabled the production of lactase in adulthood and this allowed milk to be used as a new source of nutrition which could sustain populations when other food sources failed. Milk is processed into a variety of products such as cream, butter, yogurt, kefir, ice cream. Modern industrial processes use milk to produce casein, whey protein, lactose, condensed milk, powdered milk, whole milk, butter and cream have high levels of saturated fat. The sugar lactose is found only in milk, forsythia flowers, the enzyme needed to digest lactose, lactase, reaches its highest levels in the small intestine after birth and then begins a slow decline unless milk is consumed regularly
29.
Simmering
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Simmering is a food preparation technique in which foods are cooked in hot liquids kept just below the boiling point of water, but higher than poaching temperature. To keep a pot simmering, one brings it to a boil and then reduces the heat to a point where the formation of bubbles has almost ceased, simmering ensures gentler treatment than boiling to prevent food from toughening and/or breaking up. Simmering is usually a rapid and efficient method of cooking, food that has simmered in milk or cream instead of water is sometimes referred to as creamed. The appropriate simmering temperature is a topic of debate among chefs, in Japanese cuisine, simmering is considered one of the four essential cooking techniques. Food prepared in a crockpot is simmered, examples include stews, chili, soups, etc. Bulgarian traditional food, especially meat dishes are often simmered for extended periods of time. Examples include stews, soups, Vanyas, etc, in traditional Dutch and Flemish cuisine, less tender cuts of beef are simmered for several hours to obtain Carbonade flamande. Traditionally a small flame is used, fed by burning oil, on modern stoves, the source of heat is put very low, or a simmering plate is used to diminish the heat. Usually a cast iron pan is used with a thick bottom, the meat is ready if it can be easily torn apart into threads. Some modern gas ranges are equipped with a burner, with such burners usually located at the rear of the range. Many electric ranges have a simmer setting
30.
Poaching (cooking)
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Poaching is a type of moist-heat cooking technique that involves cooking by submerging food in a liquid, such as water, milk, stock or wine. Poaching is differentiated from the other moist heat cooking methods, such as simmering and boiling and this temperature range makes it particularly suitable for delicate food, such as eggs, poultry, fish and fruit, which might easily fall apart or dry out using other cooking methods. Poaching is often considered as a method of cooking because it does not use fat to cook or flavor the food. This moist-heat cooking method uses a sautoir or other cooking vessel, heat is transferred by conduction from the pan, to the liquid. Shallow poaching is best suited for boneless, naturally tender, single serving size, sliced or diced pieces of meat and this preparation involves smearing the inside of the pan with whole butter and adding aromatics into the pan. The items to be cooked are then placed on top of the aromatics presentation side up, cold poaching liquid is then poured in until the product is partially submerged then heated. The liquid should never be allowed to boil but kept as close to boiling as possible, a more contemporary technique of shallow poaching involves BPA free plastic bags and is very convenient for the home cook. This technique is similar to shallow poaching but the product is fully submerged, the pot used for deep poaching should hold the food, liquid, and aromatics comfortably, with enough room to allow the liquid to expand as it heats. There should also be enough space so that the surface can be skimmed if necessary throughout cooking, a tight-fitting lid may be helpful for bringing the liquid up to temperature. The poaching liquid traditionally uses a court bouillon which consists of an acid and aromatics, although any flavorful liquid can be used in poaching. The liquid should ideally be around 160–185 °F, but when poaching chicken, it is vital that the chicken reach a temperature of at least 165 °F in the core. A significant amount of flavor is transferred from the food to the cooking liquid, for maximum flavor, the cooking liquid is usually reduced and used as the base for a sauce. Poached eggs are cooked in water and vinegar, fish in white wine, poultry in stock. The liquid used for shallow poaching is typically called a cuisson, Poaching allows the proteins to denature without pulling out too much moisture out of the food. For this reason, it is important to keep the low and to keep the poaching time to a bare minimum. Typically an egg is poached just to the point where the white is no longer runny, some people say creating a whirlpool helps with poaching eggs because it really helps the egg stay together, wrapping the white around the yolk. Water is a relatively efficient conductor of heat, but it also has a fairly low limit to its maximum potential temperature, as such, it is a technique that applies itself to a broad spectrum of methods and results. It is used to food at a low temperature for extended periods
31.
Elevation
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GIS or geographic information system is a computer system that allows for visualizing, manipulating, capturing, and storage of data with associated attributes. GIS offers better understanding of patterns and relationships of the landscape at different scales, tools inside the GIS allow for manipulation of data for spatial analysis or cartography. A topographical map is the type of map used to depict elevation. In a Geographic Information System, digital models are commonly used to represent the surface of a place. Digital terrain models are another way to represent terrain in GIS, USGS is developing a 3D Elevation Program to keep up with growing needs for high quality topographic data. 3DEP is a collection of enhanced elevation data in the form of high quality LiDAR data over the conterminous United States, Hawaii, there are three bare earth DEM layers in 3DEP which are nationally seamless at the resolution of 1/3,1, and 2 arcseconds. This map is derived from GTOPO30 data that describes the elevation of Earths terrain at intervals of 30 arcseconds and it uses color and shading instead of contour lines to indicate elevation. Hypsography is the study of the distribution of elevations on the surface of the Earth, the term originates from the Greek word ὕψος hypsos meaning height. Most often it is used only in reference to elevation of land, related to the term hypsometry, the measurement of these elevations of a planets solid surface are taken relative to mean datum, except for Earth which is taken relative to the sea level. In the troposphere, temperatures decrease with altitude and this lapse rate is approximately 6.5 °C/km. S
32.
Atmospheric pressure
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Atmospheric pressure, sometimes also called barometric pressure, is the pressure exerted by the weight of air in the atmosphere of Earth. In most circumstances atmospheric pressure is approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. On average, a column of air one square centimetre in cross-section, measured from sea level to the top of the atmosphere, has a mass of about 1.03 kilograms and that force is a pressure of 10.1 N/cm2 or 101 kN/m2. A column 1 square inch in cross-section would have a weight of about 14.7 lb or about 65.4 N and it is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition. The standard atmosphere is a unit of pressure defined as 101325 Pa, the mean sea level pressure is the average atmospheric pressure at sea level. This is the pressure normally given in weather reports on radio, television. When barometers in the home are set to match the weather reports, they measure pressure adjusted to sea level. The altimeter setting in aviation, is an atmospheric pressure adjustment, average sea-level pressure is 1013.25 mbar. In aviation weather reports, QNH is transmitted around the world in millibars or hectopascals, except in the United States, Canada, however, in Canadas public weather reports, sea level pressure is instead reported in kilopascals. The highest sea-level pressure on Earth occurs in Siberia, where the Siberian High often attains a sea-level pressure above 1050 mbar, the lowest measurable sea-level pressure is found at the centers of tropical cyclones and tornadoes, with a record low of 870 mbar. Pressure varies smoothly from the Earths surface to the top of the mesosphere, although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. As altitude increases, atmospheric pressure decreases, one can calculate the atmospheric pressure at a given altitude. Temperature and humidity affect the atmospheric pressure, and it is necessary to know these to compute an accurate figure. The graph at right was developed for a temperature of 15 °C, at low altitudes above the sea level, the pressure decreases by about 1.2 kPa for every 100 meters. See pressure system for the effects of air pressure variations on weather, Atmospheric pressure shows a diurnal or semidiurnal cycle caused by global atmospheric tides. This effect is strongest in tropical zones, with an amplitude of a few millibars and these variations have two superimposed cycles, a circadian cycle and semi-circadian cycle. The highest adjusted-to-sea level barometric pressure recorded on Earth was 1085.7 hPa measured in Tosontsengel
33.
Denver
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Denver, officially the City and County of Denver, is the capital and most populous municipality of the U. S. state of Colorado. Denver is in the South Platte River Valley on the edge of the High Plains just east of the Front Range of the Rocky Mountains. The Denver downtown district is immediately east of the confluence of Cherry Creek with the South Platte River, Denver is nicknamed the Mile-High City because its official elevation is exactly one mile above sea level, making it the highest major city in the United States. The 105th meridian west of Greenwich, the reference for the Mountain Time Zone. Denver is ranked as a Beta- world city by the Globalization and World Cities Research Network. With a 2015 estimated population of 682,545, Denver ranks as the 19th-most populous U. S. city, and with a 2. 8% increase in 2015, the city is also the fastest-growing major city in the United States. The 10-county Denver-Aurora-Lakewood, CO Metropolitan Statistical Area had an estimated 2015 population of 2,814,330 and ranked as the 19th most populous U. S. metropolitan statistical area. The 12-city Denver-Aurora, CO Combined Statistical Area had an estimated 2015 population of 3,418,876, which ranks as the 16th most populous U. S. metropolitan area. Denver is the most populous city of the 18-county Front Range Urban Corridor, Denver is the most populous city within a 500-mile radius and the second-most populous city in the Mountain West after Phoenix, Arizona. In 2016, Denver was named the best place to live in the USA by U. S. News & World Report and this was the first historical settlement in what was later to become the city of Denver. The site faded quickly, however, and by the summer of 1859 it was abandoned in favor of Auraria, Larimer named the townsite Denver City to curry favor with Kansas Territorial Governor James W. Denver. Larimer hoped the name would help make it the county seat of Arapaho County but, unbeknownst to him. The location was accessible to existing trails and was across the South Platte River from the site of seasonal encampments of the Cheyenne, the site of these first towns is now the site of Confluence Park near downtown Denver. Larimer, along with associates in the St. Charles City Land Company, sold parcels in the town to merchants and miners, Denver City was a frontier town, with an economy based on servicing local miners with gambling, saloons, livestock and goods trading. In the early years, land parcels were often traded for grubstakes or gambled away by miners in Auraria, in May 1859, Denver City residents donated 53 lots to the Leavenworth & Pikes Peak Express in order to secure the regions first overland wagon route. Offering daily service for passengers, mail, freight, and gold, in 1863, Western Union furthered Denvers dominance of the region by choosing the city for its regional terminus. The Colorado Territory was created on February 28,1861, Arapahoe County was formed on November 1,1861, Denver City served as the Arapahoe County Seat from 1861 until consolidation in 1902. In 1867, Denver City became the territorial capital, with its newfound importance, Denver City shortened its name to Denver
34.
Pressure cooker
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Pressure cooking is the process of cooking food, using water or other cooking liquid, in a sealed vessel, known as a pressure cooker. As pressure cooking cooks food faster than conventional cooking methods, it saves energy, Pressure is created by boiling a liquid, such as water or broth, inside the closed pressure cooker. The trapped steam increases the pressure and allows the temperature to rise. After use, the pressure is released so that the vessel can be safely opened. Pressure cooking can be used for simulation of the effects of long braising. Almost any food which can be cooked in steam or water-based liquids can be cooked in a pressure cooker, in 1679, the French physicist Denis Papin, better known for his studies on steam, invented the steam digester in an attempt to reduce the cooking time of food. His airtight cooker used steam pressure to raise the boiling point. In 1681, Papin presented his invention to the Royal Society of London and they granted him permission to become a member of the Society afterwards. In 1864, Georg Gutbrod of Stuttgart began manufacturing pressure cookers made of tinned cast iron, in 1918, Spain granted a patent for the pressure cooker to Jose Alix Martínez from Zaragoza. Martínez named it the olla exprés, literally express cooking pot, in 1938, Alfred Vischer presented his invention, the Flex-Seal Speed Cooker, in New York City. Vischers pressure cooker was the first one designed for home use, at the 1939 New York Worlds Fair, National Presto Industries, which was then known as the National Pressure Cooker Company, introduced its own pressure cooker. An autoclave is a type of pressure cooker used by laboratories, large pressure cookers are often called pressure canners in the United States, because of their capacity to hold jars used in canning. Pressure fryers are used for deep fat frying under pressure, because pressure cookers are not suitable for pressure frying. g. Vegetables Pressure cookers are made of aluminum or stainless steel. Aluminum pressure cookers may be stamped, polished, or anodized and they are cheaper, but the aluminum is reactive to acidic foods, whose flavors are changed in the reactions, and less durable than stainless steel pressure cookers. Higher-quality stainless steel cookers are made with heavy, three-layer. Most modern stainless steel cookers are dishwasher safe, although some manufacturers may recommend washing by hand, some pressure cookers have a non-stick interior. A gasket or sealing ring, made from rubber or silicone
35.
Solubility
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Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent. The solubility of a substance depends on the physical and chemical properties of the solute and solvent as well as on temperature, pressure. The solubility of a substance is a different property from the rate of solution. Most often, the solvent is a liquid, which can be a substance or a mixture. One may also speak of solid solution, but rarely of solution in a gas, the extent of solubility ranges widely, from infinitely soluble such as ethanol in water, to poorly soluble, such as silver chloride in water. The term insoluble is often applied to poorly or very poorly soluble compounds, a common threshold to describe something as insoluble is less than 0.1 g per 100 mL of solvent. Under certain conditions, the solubility can be exceeded to give a so-called supersaturated solution. Metastability of crystals can also lead to apparent differences in the amount of a chemical that dissolves depending on its form or particle size. A supersaturated solution generally crystallises when seed crystals are introduced and rapid equilibration occurs, phenylsalicylate is one such simple observable substance when fully melted and then cooled below its fusion point. Solubility is not to be confused with the ability to dissolve a substance, for example, zinc dissolves in hydrochloric acid as a result of a chemical reaction releasing hydrogen gas in a displacement reaction. The zinc ions are soluble in the acid, the smaller a particle is, the faster it dissolves although there are many factors to add to this generalization. Crucially solubility applies to all areas of chemistry, geochemistry, inorganic, physical, organic, in all cases it will depend on the physical conditions and the enthalpy and entropy directly relating to the solvents and solutes concerned. By far the most common solvent in chemistry is water which is a solvent for most ionic compounds as well as a range of organic substances. This is a factor in acidity/alkalinity and much environmental and geochemical work. According to the IUPAC definition, solubility is the composition of a saturated solution expressed as a proportion of a designated solute in a designated solvent. Solubility may be stated in units of concentration such as molarity, molality, mole fraction, mole ratio, mass per volume. Solubility occurs under dynamic equilibrium, which means that solubility results from the simultaneous and opposing processes of dissolution, the solubility equilibrium occurs when the two processes proceed at a constant rate. The term solubility is used in some fields where the solute is altered by solvolysis
36.
Salt
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Salt is present in vast quantities in seawater, where it is the main mineral constituent. The open ocean has about 35 grams of solids per litre, Salt is essential for life in general, and saltiness is one of the basic human tastes. The tissues of animals contain larger quantities of salt than do plant tissues, Salt is one of the oldest and most ubiquitous food seasonings, and salting is an important method of food preservation. Salt was also prized by the ancient Hebrews, the Greeks, the Romans, the Byzantines, the Hittites, Egyptians, and the Indians. Salt became an important article of trade and was transported by boat across the Mediterranean Sea, along specially built salt roads, the scarcity and universal need for salt has led nations to go to war over it and use it to raise tax revenues. Salt is used in ceremonies and has other cultural significance. Salt is processed from salt mines, or by the evaporation of seawater or mineral-rich spring water in shallow pools. Its major industrial products are caustic soda and chlorine, and is used in industrial processes including the manufacture of polyvinyl chloride, plastics, paper pulp. Of the annual production of around two hundred million tonnes of salt, only about 6% is used for human consumption. Other uses include water conditioning processes, de-icing highways, and agricultural use, edible salt is sold in forms such as sea salt and table salt which usually contains an anti-caking agent and may be iodised to prevent iodine deficiency. As well as its use in cooking and at the table, sodium is an essential nutrient for human health via its role as an electrolyte and osmotic solute. Excessive salt consumption can increase the risk of diseases, such as hypertension, in children. Such health effects of salt have long been studied, accordingly, numerous world health associations and experts in developed countries recommend reducing consumption of popular salty foods. The World Health Organization recommends that adults should consume less than 2,000 mg of sodium, humans have always tended to build communities either around sources of salt, or where they can trade for it. All through history the availability of salt has been pivotal to civilization, the word salary comes from the Latin word for salt because the Roman Legions were sometimes paid in salt. The Natron Valley was a key region that supported the Egyptian Empire to its north, because it supplied it with a kind of salt that came to be called by its name, natron. Even before this, what is now thought to have been the first city in Europe is Solnitsata, in Bulgaria, even the name Solnisata means salt works. A very ancient salt-works operation has been discovered at the Poiana Slatinei archaeological site next to a spring in Lunca, Neamț County
37.
Sugar
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Sugar is the generic name for sweet, soluble carbohydrates, many of which are used in food. There are various types of derived from different sources. Simple sugars are called monosaccharides and include glucose, fructose, the table sugar or granulated sugar most customarily used as food is sucrose, a disaccharide of glucose and fructose. Sugar is used in prepared foods and it is added to some foods, in the body, sucrose is hydrolysed into the simple sugars fructose and glucose. Other disaccharides include maltose from malted grain, and lactose from milk, longer chains of sugars are called oligosaccharides or polysaccharides. Some other chemical substances, such as glycerol may also have a sweet taste, low-calorie food substitutes for sugar, described as artificial sweeteners, include aspartame and sucralose, a chlorinated derivative of sucrose. Sugars are found in the tissues of most plants and are present in sufficient concentrations for efficient commercial extraction in sugarcane, the world production of sugar in 2011 was about 168 million tonnes. The average person consumes about 24 kilograms of sugar each year, equivalent to over 260 food calories per person, since the latter part of the twentieth century, it has been questioned whether a diet high in sugars, especially refined sugars, is good for human health. Sugar has been linked to obesity, and suspected of, or fully implicated as a cause in the occurrence of diabetes, cardiovascular disease, dementia, macular degeneration, the etymology reflects the spread of the commodity. The English word sugar ultimately originates from the Sanskrit शर्करा, via Arabic سكر as granular or candied sugar, the contemporary Italian word is zucchero, whereas the Spanish and Portuguese words, azúcar and açúcar, respectively, have kept a trace of the Arabic definite article. The Old French word is zuchre and the contemporary French, sucre, the earliest Greek word attested is σάκχαρις. The English word jaggery, a brown sugar made from date palm sap or sugarcane juice, has a similar etymological origin – Portuguese jagara from the Sanskrit शर्करा. Sugar has been produced in the Indian subcontinent since ancient times and it was not plentiful or cheap in early times and honey was more often used for sweetening in most parts of the world. Originally, people chewed raw sugarcane to extract its sweetness, sugarcane was a native of tropical South Asia and Southeast Asia. Different species seem to have originated from different locations with Saccharum barberi originating in India and S. edule, one of the earliest historical references to sugarcane is in Chinese manuscripts dating back to 8th century BC that state that the use of sugarcane originated in India. Sugar was found in Europe by the 1st century AD, but only as an imported medicine and it is a kind of honey found in cane, white as gum, and it crunches between the teeth. It comes in lumps the size of a hazelnut, sugar is used only for medical purposes. Sugar remained relatively unimportant until the Indians discovered methods of turning sugarcane juice into granulated crystals that were easier to store, crystallized sugar was discovered by the time of the Imperial Guptas, around the 5th century AD
38.
Boiling-point elevation
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This happens whenever a non-volatile solute, such as a salt, is added to a pure solvent, such as water. The boiling point can be measured using an ebullioscope. The boiling point elevation is a property, which means that it is dependent on the presence of dissolved particles and their number. It is an effect of the dilution of the solvent in the presence of a solute and it is a phenomenon that happens for all solutes in all solutions, even in ideal solutions, and does not depend on any specific solute-solvent interactions. The boiling point elevation happens both when the solute is an electrolyte, such as salts, and a nonelectrolyte. In thermodynamic terms, the origin of the boiling point elevation is entropic, in both cases, the explanation depends on the fact that many solutes are only present in the liquid phase and do not enter into the gas phase. Put in vapor pressure terms, a liquid boils at the temperature when its vapor pressure equals the surrounding pressure, for the solvent, the presence of the solute decreases its vapor pressure by dilution. A non-volatile solute has a pressure of zero, so the vapor pressure of the solution is less than the vapor pressure of the solvent. Thus, a temperature is needed for the vapor pressure to reach the surrounding pressure. Put in chemical terms, at the boiling point, the liquid phase. This means in turn that the equilibrium between the liquid and gas phase is established at another temperature for a solution than a pure liquid, the phenomenon of freezing-point depression is analogous to boiling point elevation. However, the magnitude of the freezing point depression is larger than the boiling point elevation for the same solvent, because of these two phenomena, the liquid range of a solvent is increased in the presence of a solute. The extent of boiling-point elevation can be calculated by applying Clausius–Clapeyron relation, Kb, the ebullioscopic constant, which is dependent on the properties of the solvent. BB is the molality of the solution, calculated by taking dissociation into account since the boiling point elevation is a colligative property and this is most easily done by using the van t Hoff factor i as bB = bsolute · i. The factor i accounts for the number of individual particles formed by a compound in solution. Examples, i =1 for sugar in water i =1.9 for sodium chloride in water, due to the near full dissociation of NaCl into Na+ and Cl− i =2. Equation after including the van t Hoff factor ΔTb = Kb · bsolute · i At high concentrations, the above formula is less precise due to nonideality of the solution. If the solute is also volatile, one of the key used in deriving the formula is not true
39.
Gulab jamun
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Gulab jamun is a milk-solid-based South Asian sweet, particularly popular in India, Sri Lanka, Nepal, Pakistan and Bangladesh. It is also common in Mauritius and the Caribbean countries of Trinidad and Tobago, Guyana, Suriname and it is made mainly from milk solids, traditionally from freshly curdled milk. It is often garnished with dried nuts like almonds to enhance flavour, in India, milk solids are prepared by heating milk over a low flame for a long time until most of the water content has evaporated. The balls are then soaked in a sugary syrup flavored with green cardamom and rose water. Gulab jamun is available commercially, at South Asian restaurants or pre-prepared either in tins or as kits to be prepared at home, gulab jamun was first prepared in medieval India, derived from a fritter that Central Asian Turkic invaders brought to India. One theory claims that it was prepared by the Mughal emperor Shah Jahans personal chef. The word gulab is derived from the Persian words gol and āb, jamun or jaman is the Hindi-Urdu word for Syzygium jambolanum, an Indian fruit with a similar size and shape. The Arab dessert luqmat al-qadi is similar to gulab jamun, although it uses a completely different batter. According to the culinary historian Michael Krondl, both luqmat al-qadi and gulab jamun may have derived from a Persian dish, with rose water syrup being a connection between the two. Gulab jamun is a dessert often eaten at festivals, birthdays or major celebrations such as marriages, the Muslim celebrations of Eid ul-Fitr and Eid al-Adha, there are various types of gulab jamun and every variety has a distinct taste and appearance. Gulab jamun gets its brownish red color because of the content in the milk powder. In other types of gulab jamun, sugar is added in the batter, and after frying, the sugar caramelization gives it its dark, almost black color, the sugar syrup may be replaced with diluted maple syrup for a gulab jamun with a Canadian flavor. Pantua is similar to gulab jamun, and could be called a Bengali variant of that dish, ledikeni, a variation of Pantua, is another variant of gulab jamun
40.
Rice
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Rice is the seed of the grass species Oryza sativa or Oryza glaberrima. As a cereal grain, it is the most widely consumed staple food for a part of the worlds human population. It is the agricultural commodity with the third-highest worldwide production, after sugarcane and maize, wild rice, from which the crop was developed, may have its native range in Australia. Chinese legends attribute the domestication of rice to Shennong, the emperor of China. Genetic evidence has shown that rice originates from a single domestication 8, previously, archaeological evidence had suggested that rice was domesticated in the Yangtze River valley region in China. From East Asia, rice was spread to Southeast and South Asia, Rice was introduced to Europe through Western Asia, and to the Americas through European colonization. There are many varieties of rice and culinary preferences tend to vary regionally, in some areas such as the Far East or Spain, there is a preference for softer and stickier varieties. Rice, a monocot, is grown as an annual plant, although in tropical areas it can survive as a perennial. The rice plant can grow to 1–1.8 m tall, occasionally more depending on the variety and it has long, slender leaves 50–100 cm long and 2–2.5 cm broad. The small wind-pollinated flowers are produced in a branched arching to pendulous inflorescence 30–50 cm long, the edible seed is a grain 5–12 mm long and 2–3 mm thick. Rice cultivation is well-suited to countries and regions with low costs and high rainfall, as it is labor-intensive to cultivate. However, rice can be grown practically anywhere, even on a hill or mountain area with the use of water-controlling terrace systems. Although its parent species are native to Asia and certain parts of Africa, centuries of trade, the traditional method for cultivating rice is flooding the fields while, or after, setting the young seedlings. The name wild rice is used for species of the genera Zizania and Porteresia. The Greek word is the source of all European words, the origin of the Greek word is unclear. It is sometimes held to be from the Tamil word அரிசி, however, Krishnamurti disagrees with the notion that Old Tamil arici is the source of the Greek term, and proposes that it was borrowed from descendants of Proto-Dravidian *wariñci instead. The varieties of rice are typically classified as long-, medium-, the grains of long-grain rice tend to remain intact after cooking, medium-grain rice becomes more sticky. Medium-grain rice is used for dishes, for risotto in Italy
41.
Noodle
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Noodles are a staple food in many cultures made from unleavened dough which is stretched, extruded, or rolled flat and cut into one of a variety of shapes. While long, thin strips may be the most common, many varieties of noodles are cut into waves, helices, tubes, strings, or shells, or folded over, Noodles are usually cooked in boiling water, sometimes with cooking oil or salt added. They are often pan-fried or deep-fried, Noodles are often served with an accompanying sauce or in a soup. Noodles can be refrigerated for storage, or dried and stored for future use. The material composition or geocultural origin must be specified when discussing noodles, the word derives from the German word Nudel. The origin of noodles has been disputed, but the evidence heavily favors its origin in China, claims have been made that the noodle was of Chinese, Arabian and Mediterranean origin. A Nature article claimed the oldest evidence of consumption was from 4,000 years ago in China. The earliest written record of noodles is found in a book dated to the Eastern Han period, Noodles, often made from wheat dough, became a staple food for people of the Han Dynasty. During the Tang Dynasty, the noodles were first cut into strips, wheat noodles in Japan were adapted from a Chinese recipe by a Buddhist monk as early as the 9th century. Reshteh noodles were eaten by the people of Persia by the 13th century, innovations continued, as for example, noodles made from buckwheat were developed in the Joseon Dynasty of Korea. Ramen noodles, based on Chinese noodles, became popular in Japan by 1900, instant noodles were invented by Momofuku Ando and first marketed in Japan in 1958. According to Andos method, a bundle of noodles is flash-fried. In the 1st century BCE, Horace wrote of fried sheets of dough called lagana, in the 2nd century CE, the Greek physician Galen mentioned itrion, referring to all homogenous mixtures from flour and water. The Latinized itrium was used as a reference to a kind of boiled dough, the Jerusalem Talmud records that itrium was common in the Byzantine Provinces of Palaestina Prima and Palaestina Secunda from the 3rd to 5th centuries CE. Arabs adapted noodles for long journeys in the 5th century, the first written record of dry pasta, the 9th-century Arab physician Isho bar Ali defines itriyya, the Arabic cognate of the Greek word, as string-like shapes made of semolina and dried before cooking. Muhammad al-Idrisi wrote in 1154 that itriyya was manufactured and exported from Norman Sicily, itriya was also known by the Aramaic speakers under the Persian sphere and during the Islamic rule referred to a small soup noodle prepared by twisting bits of kneaded dough into shape. The first concrete information on products in Italy dates to the 13th or 14th centuries. This would reflect Europeans, like Padre Giovanni del Carpini, traveling to Asia prior to the Venetian Polo family in the 13th century, pasta has taken on a variety of shapes, often based on regional specializations
42.
Potato
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The potato is a starchy, tuberous crop from the perennial nightshade Solanum tuberosum. The word potato may refer either to the plant itself or to the edible tuber, in the Andes, where the species is indigenous, there are some other closely related cultivated potato species. Potatoes were introduced to Europe in the half of the 16th century by the Spanish. It is the worlds fourth-largest food crop, following maize, wheat, the green leaves and green skins of tubers exposed to the light are toxic. Wild potato species can be throughout the Americas from the United States to southern Chile. Following centuries of breeding, there are now over a thousand different types of potatoes. However, the importance of the potato is variable and changing rapidly. As of 2007 China led the world in production, and nearly a third of the worlds potatoes were harvested in China. The English word potato comes from Spanish patata, the Spanish Royal Academy says the Spanish word is a compound of the Taíno batata and the Quechua papa. The 16th-century English herbalist John Gerard used the terms bastard potatoes and Virginia potatoes for this species, potatoes are occasionally referred to as Irish potatoes or white potatoes in the United States, to distinguish them from sweet potatoes. The name spud for a small potato comes from the digging of soil prior to the planting of potatoes, the word spud traces back to the 16th century. It subsequently transferred over to a variety of digging tools, around 1845, the name transferred to the tuber itself. It was Mario Peis 1949 The Story of Language that can be blamed for the false origin. Pei writes, the potato, for its part, was in disrepute some centuries ago, some Englishmen who did not fancy potatoes formed a Society for the Prevention of Unwholesome Diet. The initials of the words in this title gave rise to spud. Like most other pre-20th century acronymic origins, this is false, Potato plants are herbaceous perennials that grow about 60 cm high, depending on variety, with the leaves dying back after flowering, fruiting and tuber formation. They bear white, pink, red, blue, or purple flowers with yellow stamens, in general, the tubers of varieties with white flowers have white skins, while those of varieties with colored flowers tend to have pinkish skins. Potatoes are mostly cross-pollinated by insects such as bumblebees, which carry pollen from other potato plants, tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties
43.
Sous-vide
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The intent is to cook the item evenly, ensuring that the inside is properly cooked without overcooking the outside, and retain moisture. The method was first described by Sir Benjamin Thompson, Count Rumford in 1799 and it was re-discovered by American and French engineers in the mid-1960s and developed into an industrial food preservation method. The method was adopted by Georges Pralus in 1974 for the Restaurant Troisgros in Roanne and he discovered that when foie gras was cooked in this manner, it kept its original appearance, did not lose excess amounts of fat, and had better texture. Another pioneer in sous-vide is Bruno Goussault, who researched the effects of temperature on various foods. As chief scientist of Alexandria, Virginia-based food manufacturer Cuisine Solutions, as may also be done in traditional poaching, sealing the food in sturdy plastic bags keeps in juices and aroma that otherwise would be lost in the process. If the food is removed from the heat too late, it becomes overcooked, as a result of precise temperature control of the bath and the fact that the bath temperature is the same as the target cooking temperature, very precise control of cooking can be achieved. Additionally, temperature, and thus cooking, can be very even throughout the food in cooking, even with irregularly shaped or very thick items. Fat on meat, which may become rancid with prolonged exposure to air, the degree of accuracy and constancy of cooking temperature required varies with the food cooked. But for an egg, which has proteins that denature at different temperatures, cooking times for normal cooking are determined by when the center of the cooked item reaches a few degrees below the targeted temperature. Then heating should be stopped immediately, while resting the food, if the heating continues, the food will be overcooked. The time taken for the center of food to reach the temperature depends on the initial temperature, the thickness and shape of the food. One limitation of sous-vide cooking is the fact that browning happens at much higher temperatures, the flavors and ‘crust’ texture developed by browning are generally seen as very desirable in the cooking of certain types of meat, such as a steak. The flavors and texture produced by browning cannot be obtained only the sous-vide technique. This secondary browning is done briefly, and sometimes at higher heat than normally used, so as to only the surface of the food. Similarly, the skin of fish can be cooked at high temperatures after the sous-vide to make the skin crisp, food safety is a function of both time and temperature, a temperature usually considered insufficient to render food safe may be perfectly safe if maintained for long enough. Some sous-vide fish recipes, for example, are cooked below 55 °C, however, people with compromised immunity should never eat food that has not been properly pasteurized. Women eating food cooked sous-vide while pregnant expose themselves and/or their unborn children to risk, pasteurization kills the botulism bacteria, but the possibility of hardy botulism spores surviving and reactivating once cool remains a concern as with many preserved foods, however processed. For that reason, Baldwin’s treatise specifies precise chilling requirements for ‘cook-chill’, pasteurised food can then be stored for up to two weeks at around 3 °C sealed within the vacuum pack
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