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Hysteresis The most important extension of Bouc-Wen Model was carried out by Baber and Noori and later by Noori and co-workers. That extended model, named, BWBN, can reproduce the complex shear pinching or slip-lock phenomenon that earlier model could not reproduce. BWBN model has been widely used in a wide spectrum of... | https://en.wikipedia.org/wiki?curid=147003 |
Chemical property A chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity. Simply speaking, chemical properties cannot be determined just by viewing or touching the sub... | https://en.wikipedia.org/wiki?curid=147027 |
Polyethylene glycol (PEG; ) is a polyether compound with many applications, from industrial manufacturing to medicine. PEG is also known as polyethylene oxide (PEO) or polyoxyethylene (POE), depending on its molecular weight. The structure of PEG is commonly expressed as H−(O−CH−CH)−OH. PEG is generally considered biol... | https://en.wikipedia.org/wiki?curid=147203 |
Polyethylene glycol The three names are chemically synonymous, but historically "PEG" is preferred in the biomedical field, whereas "PEO" is more prevalent in the field of polymer chemistry. Because different applications require different polymer chain lengths, "PEG" has tended to refer to oligomers and polymers with ... | https://en.wikipedia.org/wiki?curid=147203 |
Polyethylene glycol PEGs are also available with different geometries. The numbers that are often included in the names of PEGs indicate their average molecular weights (e.g. a PEG with would have an average molecular weight of approximately 400 daltons, and would be labeled PEG 400.) Most PEGs include molecules with a... | https://en.wikipedia.org/wiki?curid=147203 |
Polyethylene glycol It is, thus, imperative to assess potential PEG degradation to ensure that the final material does not contain undocumented contaminants that can introduce artifacts into experimental results. PEGs and methoxypolyethylene glycols are manufactured by Dow Chemical under the tradename "Carbowax" for in... | https://en.wikipedia.org/wiki?curid=147203 |
Polyethylene glycol Ethylene glycol and its oligomers are preferable as a starting material instead of water, because they allow the creation of polymers with a low polydispersity (narrow molecular weight distribution). Polymer chain length depends on the ratio of reactants. Depending on the catalyst type, the mechanis... | https://en.wikipedia.org/wiki?curid=147203 |
Octane rating An octane rating, or octane number, is a standard measure of the performance of an engine or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating (igniting). In broad terms, fuels with a higher octane rating are used in high-performance gasoline engine... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating Knocking can cause major engine damage if severe. The most typically used engine management systems found in automobiles today have a knock sensor that monitors if knock is being produced by the fuel being used. In modern computer-controlled engines, the ignition timing will be automatically altered by th... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating (See Effects below and Heat of combustion). They are only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced. Ethanol energy density can be compared... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern pump gasoline will be about 8 to 12 octane l... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating The original testing was done in cars on the road but as technology developed the testing was moved to chassis dynamometers with environmental controls to improve consistency. The evaluation of the octane number by the two laboratory methods requires a standard engine, and the test procedure can be both e... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating The ability to predict the octane quality of the blends prior to blending is essential, something for which the calculated octane index is specially suited. Aviation gasolines used in piston aircraft engines common in general aviation have a slightly different method of measuring the octane of the fuel. S... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating Because octane is a measured and/or calculated rating of the fuel's ability to resist autoignition, the higher the octane of the fuel, the harder that fuel is to ignite and the more heat is required to ignite it. The result is that a hotter ignition spark is required for ignition. Creating a hotter spark ... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating They also evaporate away much more easily than heavier, lower-octane fuel which leads to more accumulated contaminants in the fuel system. Its typically the and the compounds in the fuel that have the most detrimental effects on the engine fuel system components, as such acids corrode many metals used in ... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating And since many airplanes are flown only occasionally and may sit unused for weeks or months, the lighter fuels tend to evaporate away and leave behind fewer deposits such as "varnish". Aircraft also typically have dual "redundant" ignition systems which are nearly impossible to tune and time to produce id... | https://en.wikipedia.org/wiki?curid=147242 |
Octane rating Pilots are taught in primary training to avoid settings that produce the highest exhaust gas temperatures, and run the engine either "rich of peak" (more fuel than can be burned with the available air) or "lean of peak" (less fuel, leaving some oxygen in the exhaust) as either will keep the fuel-air mixtu... | https://en.wikipedia.org/wiki?curid=147242 |
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term ""lime"" connotes calcium-containing inorganic materials, in which carbonates, oxides and hydroxides of calcium, silicon, mag... | https://en.wikipedia.org/wiki?curid=147536 |
Calcium oxide Approximately 1.8t of limestone is required per 1.0t of quicklime. Quicklime has a high affinity for water and is a more efficient desiccant than silica gel. The reaction of quicklime with water is associated with an increase in volume by a factor of at least 2.5. In 80 BC, the Roman general Sertorius dep... | https://en.wikipedia.org/wiki?curid=147536 |
Calcium oxide Cement, cement kiln dust, fly ash, and lime kiln dust are potential substitutes for some construction uses of lime. Magnesium hydroxide is a substitute for lime in pH control, and magnesium oxide is a substitute for dolomitic lime as a flux in steelmaking. Because of vigorous reaction of quicklime with wa... | https://en.wikipedia.org/wiki?curid=147536 |
Speed of sound The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or a kilometre in or a mile in . It depends strongly on temperature as well as the medium through which a sound wave is propagating. The speed o... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound The speed of shear waves is determined only by the solid material's shear modulus and density. In fluid dynamics, the speed of sound in a fluid medium (gas or liquid) is used as a relative measure for the speed of an object moving through the medium. The ratio of the speed of an object to the speed of so... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound ) Derham used a telescope from the tower of the church of St Laurence, Upminster to observe the flash of a distant shotgun being fired, and then measured the time until he heard the gunshot with a half-second pendulum. Measurements were made of gunshots from a number of local landmarks, including North O... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound For instance, sound will travel 1.59 times faster in nickel than in bronze, due to the greater stiffness of nickel at about the same density. Similarly, sound travels about 1.41 times faster in light hydrogen (protium) gas than in heavy hydrogen (deuterium) gas, since deuterium has similar properties but... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound It is particularly effective if a multi-gun salute such as for "The Queen's Birthday" is being fired. In a gas or liquid, sound consists of compression waves. In solids, waves propagate as two different types. A longitudinal wave is associated with compression and decompression in the direction of travel... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound In solids, the compression waves are analogous to those in fluids, depending on compressibility and density, but with the additional factor of shear modulus which affects compression waves due to off-axis elastic energies which are able to influence effective tension and relaxation in a compression. The ... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound Per Newton's second law, the pressure-gradient force provides the acceleration: And therefore: where If relativistic effects are important, the speed of sound is calculated from the relativistic Euler equations. In a non-dispersive medium, the speed of sound is independent of sound frequency, so the spee... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound In heterogeneous fluids, such as a liquid filled with gas bubbles, the density of the liquid and the compressibility of the gas affect the speed of sound in an additive manner, as demonstrated in the hot chocolate effect. In gases, adiabatic compressibility is directly related to pressure through the hea... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound In a similar way, compression waves in solids depend both on compressibility and density—just as in liquids—but in gases the density contributes to the compressibility in such a way that some part of each attribute factors out, leaving only a dependence on temperature, molecular weight, and heat capacity... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound Since temperature (and thus the speed of sound) decreases with increasing altitude up to , sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source. The decrease of the speed of sound with height is referred to as a negative sound speed gr... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound 6 due to the assumptions made when it is calculated. If ideal gas "γ" is assumed to be exactly, the speed is calculated (see section below) to be , the coefficient used above. This equation is correct to a much wider temperature range, but still depends on the approximation of heat capacity ratio being i... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound Calculated values for "c" have been found to vary slightly from experimentally determined values. Newton famously considered the speed of sound before most of the development of thermodynamics and so incorrectly used isothermal calculations instead of adiabatic. His result was missing the factor of "γ" b... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound Then, for dry air, where "formula_12" (theta) is the temperature in degrees Celsius(°C). Substituting numerical values for the molar gas constant in J/mole/Kelvin, and for the mean molar mass of air, in kg; and using the ideal diatomic gas value of , we have Finally, Taylor expansion of the remaining squ... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound In the standard atmosphere: In fact, assuming an ideal gas, the speed of sound "c" depends on temperature only, not on the pressure or density (since these change in lockstep for a given temperature and cancel out). Air is almost an ideal gas. The temperature of the air varies with altitude, giving the f... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound In general, at the same molecular mass, monatomic gases have slightly higher speed of sound (over 9% higher) because they have a higher "γ" (...) than diatomics do (). Thus, at the same molecular mass, the speed of sound of a monatomic gas goes up by a factor of This gives the 9% difference, and would be... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound By far the most important factor influencing the speed of sound in air is temperature. The speed is proportional to the square root of the absolute temperature, giving an increase of about per degree Celsius. For this reason, the pitch of a musical wind instrument increases as its temperature increases. ... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound m/s is exact a little below 5 °C and is a good approximation for all "usual" outside temperatures (in temperate climates, at least), hence the usual rule of thumb to determine how far lightning has struck: count the seconds from the start of the lightning flash to the start of the corresponding roll of t... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound He then measured the interval between seeing gunsmoke and arrival of the sound using a half-second pendulum. The distance from where the gun was fired was found by triangulation, and simple division (distance/time) provided velocity. Lastly, by making many observations, using a range of different distanc... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound In this system it is the case that the pipe can be brought to resonance if the length of the air column in the pipe is equal to "(1 + 2"n")λ/4" where "n" is an integer. As the antinodal point for the pipe at the open end is slightly outside the mouth of the pipe it is best to find two or more points of r... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound Sound waves generating volumetric deformations (compression) and shear deformations (shearing) are called pressure waves (longitudinal waves) and shear waves (transverse waves), respectively. In earthquakes, the corresponding seismic waves are called P-waves (primary waves) and S-waves (secondary waves),... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound This is similar to the expression for shear waves, save that Young's modulus replaces the shear modulus. This speed of sound for pressure waves in long rods will always be slightly less than the same speed in homogeneous 3-dimensional solids, and the ratio of the speeds in the two different types of obje... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound For more information see Dushaw et al. An empirical equation for the speed of sound in sea water is provided by Mackenzie: where The constants "a", "a", ..., "a" are with check value for , , . This equation has a standard error of for salinity between 25 and 40 ppt. See Technical Guides. Speed of Sound i... | https://en.wikipedia.org/wiki?curid=147853 |
Speed of sound Just as light waves will refract towards a region of higher index, sound waves will refract towards a region where their speed is reduced. The result is that sound gets confined in the layer, much the way light can be confined to a sheet of glass or optical fiber. Thus, the sound is confined in essential... | https://en.wikipedia.org/wiki?curid=147853 |
Mirror image A mirror image (in a plane mirror) is a reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface. As an optical effect it results from reflection off of substances such as a mirror or water. It is also a concept in geometry and c... | https://en.wikipedia.org/wiki?curid=148234 |
Mirror image The concept of reflection can be extended to three-dimensional objects, including the inside parts, even if they are not transparent. The term then relates to structural as well as visual aspects. A three-dimensional object is reversed in the direction perpendicular to the mirror surface. In physics, mirro... | https://en.wikipedia.org/wiki?curid=148234 |
Mirror image The psychology of the perceived left-right reversal is discussed in "Much ado about mirrors" by Professor Michael Corballis (see "external links", below). Reflection in a mirror "does" result in a change in chirality, more specifically from a right-handed to a left-handed coordinate system (or vice versa).... | https://en.wikipedia.org/wiki?curid=148234 |
Mirror image This is because the relative position of objects changes as the observer's perspective changes, or is differently viewed with each eye. Looking through a mirror from different positions (but necessarily with the point of observation restricted to the halfspace on one side of the mirror) is like looking at ... | https://en.wikipedia.org/wiki?curid=148234 |
Mirror image Some movie theaters also take advantage of mirror writing in a Rear Window Captioning System used to assist individuals with hearing impairments watching the film. In the case of two mirrors, in planes at an angle α, looking through both from the sector which is the intersection of the two halfspaces, is l... | https://en.wikipedia.org/wiki?curid=148234 |
Mirror image For example, with a vertical periscope, the shift of the world is away from the observer and down, both by the length of the periscope, but it is more practical to consider the equivalent shift of the observer: up, and backward. It is also possible to create a non-reversing mirror by placing two first surf... | https://en.wikipedia.org/wiki?curid=148234 |
Antiferromagnetism In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spins (on different sublattices) pointing in opposite directions. This is, like ferromagnetism and ferrimagnetism, a manifes... | https://en.wikipedia.org/wiki?curid=148550 |
Antiferromagnetism Various microscopic (exchange) interactions between the magnetic moments or spins may lead to antiferromagnetic structures. In the simplest case, one may consider an Ising model on a bipartite lattice, e.g. the simple cubic lattice, with couplings between spins at nearest neighbor sites. Depending on... | https://en.wikipedia.org/wiki?curid=148550 |
Antiferromagnetism Antiferromagnets can couple to ferromagnets, for instance, through a mechanism known as exchange bias, in which the ferromagnetic film is either grown upon the antiferromagnet or annealed in an aligning magnetic field, causing the surface atoms of the ferromagnet to align with the surface atoms of th... | https://en.wikipedia.org/wiki?curid=148550 |
Antiferromagnetism This illustrates frustration: the inability of the system to find a single ground state. This type of magnetic behavior has been found in minerals that have a crystal stacking structure such as a Kagome lattice or hexagonal lattice. Synthetic antiferromagnets (often abbreviated by SAF) are artificial... | https://en.wikipedia.org/wiki?curid=148550 |
Spin glass In condensed matter physics, a spin glass is a model of a certain type of magnet. Magnetic spins are, roughly speaking, the orientation of the north and south magnetic poles in three-dimensional space. In ferromagnetic solids, component atoms' magnetic spins all align in the same direction. Spin glasses are ... | https://en.wikipedia.org/wiki?curid=148555 |
Spin glass Spin glasses and the complex internal structures that arise within them are termed "metastable" because they are "stuck" in stable configurations other than the lowest-energy configuration (which would be aligned and ferromagnetic). The mathematical complexity of these structures is difficult but fruitful to... | https://en.wikipedia.org/wiki?curid=148555 |
Spin glass Experimental measurements on the order of days have shown continual changes above the noise level of instrumentation. Spin glasses differ from ferromagnetic materials by the fact that after the external magnetic field is removed from a ferromagnetic substance, the magnetization remains indefinitely at the re... | https://en.wikipedia.org/wiki?curid=148555 |
Spin glass The Hamiltonian for this spin system is given by: where formula_3 refers to the Pauli spin matrix for the spin-half particle at lattice point formula_4. A negative value of formula_5 denotes an antiferromagnetic type interaction between spins at points formula_4 and formula_7. The sum runs over all nearest n... | https://en.wikipedia.org/wiki?curid=148555 |
Spin glass Under the assumption of replica symmetry, the mean-field free energy is given by the expression In addition to unusual experimental properties, spin glasses are the subject of extensive theoretical and computational investigations. A substantial part of early theoretical work on spin glasses dealt with a for... | https://en.wikipedia.org/wiki?curid=148555 |
Spin glass Parisi, M.A. Virasoro and many others—revealed the complex nature of a glassy low temperature phase characterized by ergodicity breaking, ultrametricity and non-selfaverageness. Further developments led to the creation of the cavity method, which allowed study of the low temperature phase without replicas. A... | https://en.wikipedia.org/wiki?curid=148555 |
Spin glass Unlike the Edwards–Anderson model, similar to the SK model, the interaction range is still infinite. The Hamiltonian for this model is described by: where formula_30 have similar meanings as in the EA model. The formula_31 limit of this model is known as the random energy model. In this limit, it can be seen... | https://en.wikipedia.org/wiki?curid=148555 |
Spin glass One characteristic of spin glass systems is that, below the freezing temperature formula_40, instances are trapped in a "non-ergodic" set of states: the system may fluctuate between several states, but cannot transition to other states of equivalent energy. Intuitively, one can say that the system cannot esc... | https://en.wikipedia.org/wiki?curid=148555 |
Medical uses of silver The medical uses of silver include its use in wound dressings, creams, and as an antibiotic coating on medical devices. Wound dressings containing silver sulfadiazine or silver nanomaterials may be used on external infections. The limited evidence available shows that silver coatings on endotrach... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver Silver, used as a topical antiseptic, is incorporated by bacteria it kills. Thus dead bacteria may be the source of silver which may kill additional bacteria. Silver sulfadiazine (SSD) is a topical antibiotic used in partial thickness and full thickness burns to prevent infection. It was discover... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver A 2014 data set from a recent meta-analysis concluded that the use of silver dressings improves healing time, and can lead to overall cost savings compared with treatment with non-silver dressings. It also found that patients who had been treated with silver dressings had a faster wound closure c... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver Another 2012 review agreed that the use of silver-coated endotracheal tubes reduces the prevalence of VAP in intubated patients, but cautioned that this on its own is not sufficient to prevent infection. They also suggested that more research is needed to establish the cost-effectiveness of the t... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver A 2011 critical analysis of eight studies found a consistent pattern which supported using silver-alloy urinary catheters over uncoated catheters to reduce infections in adult patients, and concluded that using silver-alloy catheters would significantly improve patient care. A 2007 systemic revie... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver Research in 2018 into the treatment of central nervous system infections caused by free-living amoebae such as "Naegleria fowleri" and "Acanthamoeba castellanii", tested the effectiveness of existing drugs as well as the effectiveness of the same drugs when they were conjugated with silver nanopa... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver As it turns them permanently a dark-purple/black color, in doing so increasing individual cells' visibility under a microscope and allowing for differentiation between cells, or identification of irregularities. Silver is also used in bone prostheses, reconstructive orthopedic surgery, and cardia... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver Localized argyria can occur as a result of topical use of silver-containing creams and solutions, while the ingestion, inhalation, or injection can result in generalized argyria. Preliminary reports of treatment with laser therapy have been reported. These laser treatments are painful and general... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver Many modern hospitals filter hot water through copper-silver filters to defeat MRSA and legionella infections. The World Health Organization (WHO) includes silver in a colloidal state produced by electrolysis of silver electrodes in water, and colloidal silver in water filters as two of a number ... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver Silver is not an essential mineral in humans; there is no dietary requirement for silver, and hence, no such thing as a silver "deficiency". There is no evidence that colloidal silver treats or prevents any medical condition, and it can cause serious and potentially irreversible side effects such... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver In 2009, the USFDA issued a "Consumer Advisory" warning about the potential adverse effects of colloidal silver, and said that "...there are no legally marketed prescription or over-the-counter (OTC) drugs containing silver that are taken by mouth." Quackwatch states that colloidal silver dietary... | https://en.wikipedia.org/wiki?curid=149881 |
Medical uses of silver In the early 20th century, physicians used silver-containing eyedrops to treat ophthalmic problems, for various infections, and sometimes internally for diseases such as tropical sprue, epilepsy, gonorrhea, and the common cold. During World War I, soldiers used silver leaf to treat infected wound... | https://en.wikipedia.org/wiki?curid=149881 |
Mercury-in-glass thermometer The mercury-in-glass or mercury thermometer was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714). It consists of a bulb containing mercury attached to a glass tube of narrow diameter; the volume of mercury in the tube is much less than the volume in the bulb. The volume o... | https://en.wikipedia.org/wiki?curid=150245 |
Mercury-in-glass thermometer Anders Celsius, a Swedish scientist, devised the Celsius scale, which was described in his publication "The origin of the Celsius temperature scale" in 1742. Celsius used two fixed points in his scale: the temperature of melting ice and the temperature of boiling water. This wasn't a new id... | https://en.wikipedia.org/wiki?curid=150245 |
Mercury-in-glass thermometer Finally, Celsius proposed a method of calibrating a thermometer: These points are adequate for approximate calibration but both vary with atmospheric pressure. Nowadays, the triple point of water is used instead of the freezing point (the triple point occurs at 273.16 kelvins (K), 0.01 °C).... | https://en.wikipedia.org/wiki?curid=150245 |
Mercury-in-glass thermometer The original design contains mercury, but solely as a way to indicate the position of a column of alcohol whose expansion indicates the temperature; it is not a thermometer operated by the expansion of mercury; mercury-free versions are available. Mercury thermometers cover a wide temperatu... | https://en.wikipedia.org/wiki?curid=150245 |
Mercury-in-glass thermometer Some manufacturers use galinstan, a liquid alloy of gallium, indium, and tin, as a replacement for mercury. The typical "fever thermometer" contains between of elemental mercury. Swallowing this amount of mercury would pose little danger but the inhaling of the vapour could lead to health p... | https://en.wikipedia.org/wiki?curid=150245 |
Mercury-in-glass thermometer The Federal Ministry supported each sold thermometer (covering about 30% of the direct costs) and advertised the project. During the collection period, consumers could bring in a mercury thermometer and buy an electronic thermometer for a subsidised price of 1 Euro. Between October 2007 and... | https://en.wikipedia.org/wiki?curid=150245 |
Mercury-in-glass thermometer Shops holding stocks of unsold thermometers had to withdraw them from sale; mercury thermometers purchased before this date could be used without legal implications. The purpose of these restrictions is to protect the environment and public health by decreasing the amount of mercury waste r... | https://en.wikipedia.org/wiki?curid=150245 |
Charles Hatchett FRS FRSE (2 January 1765 – 10 March 1847) was a British mineralogist and analytical chemist who discovered the element niobium, for which he proposed the name "columbium". Hatchett was elected a Fellow of the Linnaean Society in 1795, and of the Royal Society in 1797. Hatchett was elected to the Litera... | https://en.wikipedia.org/wiki?curid=150986 |
Charles Hatchett His diary of this trip was edited by Arthur Raistrick and published in 1967 as "The Hatchett diary: a tour through the counties of England and Scotland in 1796 visiting their mines and manufactories". Charles Hatchett's work on chemistry occurred mostly between 1796 and 1806, a ten-year period. In 1796... | https://en.wikipedia.org/wiki?curid=150986 |
Charles Hatchett Lavoisier had defined the term "element" a mere 13 years previously. Hatchett called this new element "columbium" (Cb) in honour of Christopher Columbus, the discoverer of America. On 26 November of that year he announced his discovery before the Royal Society. In 1802 Anders Gustaf Ekeberg (1767–1813)... | https://en.wikipedia.org/wiki?curid=150986 |
Charles Hatchett It has been described as "a little estate built in a fine Italian style" with nearby "a very well-equipped laboratory". The house was designed by Sir Robert Taylor for George Clive, with modifications by the Italian architect Placido Columbani in 1780. The gardens were laid out by Capability Brown in 1... | https://en.wikipedia.org/wiki?curid=150986 |
Charles Hatchett The award is given for "the best research on the science and technology of niobium and its alloys". The medal is cast in pure niobium. | https://en.wikipedia.org/wiki?curid=150986 |
T-symmetry or time reversal symmetry is the theoretical symmetry of physical laws under the transformation of time reversal: implies the conservation of entropy. Since the second law of thermodynamics states that entropy increases as time flows toward the future, in general, the macroscopic universe does not show symme... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry Many other phenomena, such as the relative motion of bodies with friction, or viscous motion of fluids, reduce to this, because the underlying mechanism is the dissipation of usable energy (for example, kinetic energy) into heat. The question of whether this time-asymmetric dissipation is really inevitable h... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry In this notion, a fixed initial state of a macroscopic system corresponds to relatively low entropy because the coordinates of the molecules of the body are constrained. As the system evolves in the presence of dissipation, the molecular coordinates can move into larger volumes of phase space, becoming more ... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry Since within a black hole the forward light-cone is directed towards the center and the backward light-cone is directed outward, it is not even possible to define time-reversal in the usual manner. The only way anything can escape from a black hole is as Hawking radiation. The time reversal of a black hole w... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry In physical and chemical kinetics, of the mechanical microscopic equations implies two important laws: the principle of detailed balance and the Onsager reciprocal relations. of the microscopic description together with its kinetic consequences are called microscopic reversibility. Classical variables that d... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry This allows one to analyze the conditions under which optical phenomena that locally break time-reversal, such as Faraday isolators and directional dichroism, can occur.) The laws of gravity also seem to be time reversal invariant in classical mechanics. In physics one separates the laws of motion, called ki... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry On the other hand, the notion of quantum-mechanical time reversal turns out to be a useful tool for the development of physically motivated quantum computing and simulation settings, providing, at the same time, relatively simple tools to assess their complexity. For instance, quantum-mechanical time reversa... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry If time reversal were implemented as a unitary operator, it would reverse the sign of the energy just as space-reversal reverses the sign of the momentum. This is not possible, because, unlike momentum, energy is always positive. Since energy in quantum mechanics is defined as the phase factor exp(–"iEt") th... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry However, since d is a vector, its expectation value in a state |ψ⟩ must be proportional to ⟨ψ| "J" |ψ⟩, that is the expected spin. Thus, under time reversal, an invariant state must have vanishing EDM. In other words, a non-vanishing EDM signals both "P" and "T" symmetry-breaking. Some molecules, such as wat... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry This implies that if , then there is a twofold degeneracy in the state. This result in non-relativistic quantum mechanics presages the spin statistics theorem of quantum field theory. Quantum states that give unitary representations of time reversal, i.e., have , are characterized by a multiplicative quantum... | https://en.wikipedia.org/wiki?curid=151013 |
T-symmetry Thus the second law of thermodynamics is thought to originate in the initial conditions in the universe. Strong measurements (both classical and quantum) are certainly disturbing, causing asymmetry due to the second law of thermodynamics. However, noninvasive measurements should not disturb the evolution so ... | https://en.wikipedia.org/wiki?curid=151013 |
Oak Ridge, Tennessee Oak Ridge is a suburban city in Anderson and Roane counties in the eastern part of the U.S. state of Tennessee, about west of Knoxville. Oak Ridge's population was 29,330 at the 2010 census. It is part of the Knoxville Metropolitan Area. Oak Ridge's nicknames include "the Atomic City", "the Secret ... | https://en.wikipedia.org/wiki?curid=151055 |
Oak Ridge, Tennessee The Oak Ridge area was largely uninhabited by the time Euro-American explorers and settlers arrived in the late 18th century, although the Cherokee claimed the land as part of their hunting grounds. During the early 19th century, several rural farming communities developed in the Oak Ridge area, na... | https://en.wikipedia.org/wiki?curid=151055 |
Oak Ridge, Tennessee The version recalled by neighbors and relatives has been reported as follows: In 1942, the United States federal government chose the area as a site for developing materials for the Manhattan Project. Maj. Gen. Leslie Groves, military head of the Manhattan Project, liked the area for several reason... | https://en.wikipedia.org/wiki?curid=151055 |
Oak Ridge, Tennessee House and dormitory accommodations at the Clinton Engineer Works in Oak Ridge and Hanford Engineer Works in Washington State were basic, with coal rather than oil or electric furnaces. But they were of a higher standard than Director Groves would have liked, and were better than at Los Alamos. Medi... | https://en.wikipedia.org/wiki?curid=151055 |
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