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Kuwait
In February 2009, French President Nicolas Sarkozy announced that Kuwait was considering buying up to 28 Rafales. In October 2009, during a visit to Paris, the Kuwaiti Defence Minister expressed interest in the Rafale and said that he was awaiting Dassault's terms. Islamist lawmakers in the Kuwaiti national asse... | Dassault Rafale | Wikipedia | 410 | 33731380 | https://en.wikipedia.org/wiki/Dassault%20Rafale | Technology | Specific aircraft | null |
In March 2018, Swiss officials named contenders in its Air 2030 program: The Rafale, Saab Gripen, Eurofighter Typhoon, Boeing F/A-18E/F Super Hornet and Lockheed Martin F-35. In October 2018, the Swiss Air Force was reportedly limited to buying a single-engine fighter for budgetary reasons. In May 2019, the Rafale perf... | Dassault Rafale | Wikipedia | 451 | 33731380 | https://en.wikipedia.org/wiki/Dassault%20Rafale | Technology | Specific aircraft | null |
In late 2007, La Tribune reported that a prospective US$2.85 billion sale to Morocco had fallen through, the government selecting the F-16C/D instead. While French Defense Minister Hervé Morin labelled it as overly sophisticated and too costly, defense analysists have said that miscalculations of the DGA's offer price ... | Dassault Rafale | Wikipedia | 494 | 33731380 | https://en.wikipedia.org/wiki/Dassault%20Rafale | Technology | Specific aircraft | null |
Croatian Air Force – 12 ex French C/B F3-R Rafales ordered, 10 single-seat C F3-R and 2x two-seat B F3-R fighters. The first six were delivered on 25 April 2024 (2 B + 4 C) and the remaining six single-seaters are to be delivered in 2025. In October 2023, Croatia officially acquired the first aircraft at a ceremony at ... | Dassault Rafale | Wikipedia | 127 | 33731380 | https://en.wikipedia.org/wiki/Dassault%20Rafale | Technology | Specific aircraft | null |
A total of 234 have been ordered out of a planned 286. In 2024, 166 units were delivered to the French Armed Forces, with 12 units sold to Greece and another 12 to Croatia, France currently operate around 143 Rafale. Once the deliveries completed, France is expected to field around 225 units. 185 for the Air and Space ... | Dassault Rafale | Wikipedia | 476 | 33731380 | https://en.wikipedia.org/wiki/Dassault%20Rafale | Technology | Specific aircraft | null |
Indian Air Force – 36 (28 single-seat and 8 dual-seat) aircraft delivered by July 2022, of 36 ordered.
Ambala AFS
No. 17 Squadron (Golden Arrows)
Hasimara AFS
No. 101 Squadron (Falcons)
Qatar Emiri Air Force – 36 ordered, all delivered. Qatar ordered 24 of the fighters in 2015, and 12 more in 2018. It also has an ... | Dassault Rafale | Wikipedia | 246 | 33731380 | https://en.wikipedia.org/wiki/Dassault%20Rafale | Technology | Specific aircraft | null |
Notable accidents
On 6 December 2007, a French Air Force twin-seat Rafale crashed during a training flight. The pilot, who suffered from spatial disorientation, died in the accident.
On 24 September 2009, after unarmed test flights, two French Navy Rafales returning to the aircraft carrier , collided in mid-air about... | Dassault Rafale | Wikipedia | 294 | 33731380 | https://en.wikipedia.org/wiki/Dassault%20Rafale | Technology | Specific aircraft | null |
In geometry, the parallel postulate, also called Euclid's fifth postulate because it is the fifth postulate in Euclid's Elements, is a distinctive axiom in Euclidean geometry. It states that, in two-dimensional geometry:
If a line segment intersects two straight lines forming two interior angles on the same side that ... | Parallel postulate | Wikipedia | 485 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
There is at most one line that can be drawn parallel to another given one through an external point. (Playfair's axiom)
The sum of the angles in every triangle is 180° (triangle postulate).
There exists a triangle whose angles add up to 180°.
The sum of the angles is the same for every triangle.
There exists a pair... | Parallel postulate | Wikipedia | 299 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
However, the alternatives which employ the word "parallel" cease appearing so simple when one is obliged to explain which of the four common definitions of "parallel" is meant – constant separation, never meeting, same angles where crossed by some third line, or same angles where crossed by any third line – since the e... | Parallel postulate | Wikipedia | 281 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
History
From the beginning, the postulate came under attack as being provable, and therefore not a postulate, and for more than two thousand years, many attempts were made to prove (derive) the parallel postulate using Euclid's first four postulates. The main reason that such a proof was so highly sought after was that... | Parallel postulate | Wikipedia | 461 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
The Persian mathematician, astronomer, philosopher, and poet Omar Khayyám (1050–1123), attempted to prove the fifth postulate from another explicitly given postulate (based on the fourth of the five principles due to the Philosopher (Aristotle), namely, "Two convergent straight lines intersect and it is impossible for ... | Parallel postulate | Wikipedia | 450 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
Nasir al-Din's son, Sadr al-Din (sometimes known as "Pseudo-Tusi"), wrote a book on the subject in 1298, based on his father's later thoughts, which presented one of the earliest arguments for a non-Euclidean hypothesis equivalent to the parallel postulate. "He essentially revised both the Euclidean system of axioms an... | Parallel postulate | Wikipedia | 488 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
Where Khayyám and Saccheri had attempted to prove Euclid's fifth by disproving the only possible alternatives, the nineteenth century finally saw mathematicians exploring those alternatives and discovering the logically consistent geometries that result. In 1829, Nikolai Ivanovich Lobachevsky published an account of ac... | Parallel postulate | Wikipedia | 446 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
Criticism
Attempts to logically prove the parallel postulate, rather than the eighth axiom, were criticized by Arthur Schopenhauer in The World as Will and Idea. However, the argument used by Schopenhauer was that the postulate is evident by perception, not that it was not a logical consequence of the other axioms.
De... | Parallel postulate | Wikipedia | 254 | 33731493 | https://en.wikipedia.org/wiki/Parallel%20postulate | Mathematics | Euclidean geometry | null |
A digital buffer (or a logic buffer) is an electronic circuit element used to copy a digital input signal and isolate it from any output load. For the typical case of using voltages as logic signals, a logic buffer's input impedance is high, so it draws little current from the input circuit, to avoid disturbing its sig... | Digital buffer | Wikipedia | 444 | 43440252 | https://en.wikipedia.org/wiki/Digital%20buffer | Technology | Digital logic | null |
Non-inverting buffer
This kind of buffer performs no inversion or decision-making possibilities. A single input digital buffer is different from an inverter. It does not invert or alter its input signal in any way. It reads an input and outputs a value. Usually, the input side reads either HIGH or LOW input and output... | Digital buffer | Wikipedia | 500 | 43440252 | https://en.wikipedia.org/wiki/Digital%20buffer | Technology | Digital logic | null |
In mathematics, the Pythagorean theorem or Pythagoras' theorem is a fundamental relation in Euclidean geometry between the three sides of a right triangle. It states that the area of the square whose side is the hypotenuse (the side opposite the right angle) is equal to the sum of the areas of the squares on the other ... | Pythagorean theorem | Wikipedia | 507 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
In another proof rectangles in the second box can also be placed such that both have one corner that correspond to consecutive corners of the square. In this way they also form two boxes, this time in consecutive corners, with areas and which will again lead to a second square of with the area .
English mathematici... | Pythagorean theorem | Wikipedia | 429 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
Let ABC represent a right triangle, with the right angle located at , as shown on the figure. Draw the altitude from point , and call its intersection with the side AB. Point divides the length of the hypotenuse into parts and . The new triangle, ACH, is similar to triangle ABC, because they both have a right angle... | Pythagorean theorem | Wikipedia | 307 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
Albert Einstein gave a proof by dissection in which the pieces do not need to be moved. Instead of using a square on the hypotenuse and two squares on the legs, one can use any other shape that includes the hypotenuse, and two similar shapes that each include one of two legs instead of the hypotenuse (see Similar figur... | Pythagorean theorem | Wikipedia | 461 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
For the formal proof, we require four elementary lemmata:
If two triangles have two sides of the one equal to two sides of the other, each to each, and the angles included by those sides equal, then the triangles are congruent (side-angle-side).
The area of a triangle is half the area of any parallelogram on the same... | Pythagorean theorem | Wikipedia | 151 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
The proof is as follows:
Let ACB be a right-angled triangle with right angle CAB.
On each of the sides BC, AB, and CA, squares are drawn, CBDE, BAGF, and ACIH, in that order. The construction of squares requires the immediately preceding theorems in Euclid, and depends upon the parallel postulate.
From A, draw a line p... | Pythagorean theorem | Wikipedia | 504 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
Proofs by dissection and rearrangement
Another by rearrangement is given by the middle animation. A large square is formed with area , from four identical right triangles with sides , and , fitted around a small central square. Then two rectangles are formed with sides and by moving the triangles. Combining the smal... | Pythagorean theorem | Wikipedia | 496 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
The triangle ABC is a right triangle, as shown in the upper part of the diagram, with BC the hypotenuse. At the same time the triangle lengths are measured as shown, with the hypotenuse of length , the side AC of length and the side AB of length , as seen in the lower diagram part.
If is increased by a small amount ... | Pythagorean theorem | Wikipedia | 492 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
A corollary of the Pythagorean theorem's converse is a simple means of determining whether a triangle is right, obtuse, or acute, as follows. Let be chosen to be the longest of the three sides and (otherwise there is no triangle according to the triangle inequality). The following statements apply:
If then the tria... | Pythagorean theorem | Wikipedia | 506 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
The equation can be transformed to,
where for any non-zero real . If the are to be integers, the smallest solution is then
using the smallest Pythagorean triple . The reciprocal Pythagorean theorem is a special case of the optic equation
where the denominators are squares and also for a heptagonal triangle whose... | Pythagorean theorem | Wikipedia | 508 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
The distance formula in Cartesian coordinates is derived from the Pythagorean theorem. If and are points in the plane, then the distance between them, also called the Euclidean distance, is given by
More generally, in Euclidean -space, the Euclidean distance between two points, and , is defined, by generalization o... | Pythagorean theorem | Wikipedia | 489 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
where the last step applies Pythagoras' theorem. This relation between sine and cosine is sometimes called the fundamental Pythagorean trigonometric identity. In similar triangles, the ratios of the sides are the same regardless of the size of the triangles, and depend upon the angles. Consequently, in the figure, the ... | Pythagorean theorem | Wikipedia | 471 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
The basic idea behind this generalization is that the area of a plane figure is proportional to the square of any linear dimension, and in particular is proportional to the square of the length of any side. Thus, if similar figures with areas , and are erected on sides with corresponding lengths , and then:
But, b... | Pythagorean theorem | Wikipedia | 193 | 26513034 | https://en.wikipedia.org/wiki/Pythagorean%20theorem | Mathematics | Geometry | null |
A supermoon is a full moon or a new moon that nearly coincides with perigee—the closest that the Moon comes to the Earth in its orbit—resulting in a slightly larger-than-usual apparent size of the lunar disk as viewed from Earth. The technical name is a perigee syzygy (of the Earth–Moon–Sun system) or a full (or new) M... | Supermoon | Wikipedia | 377 | 31156672 | https://en.wikipedia.org/wiki/Supermoon | Physical sciences | Celestial mechanics | Astronomy |
The term perigee-syzygy or perigee full/new moon is preferred in the scientific community. Perigee is the point at which the Moon is closest in its orbit to the Earth, and syzygy is when the Earth, the Moon and the Sun are aligned, which happens at every full or new moon. Astrophysicist Fred Espenak uses Nolle's defini... | Supermoon | Wikipedia | 438 | 31156672 | https://en.wikipedia.org/wiki/Supermoon | Physical sciences | Celestial mechanics | Astronomy |
In the Islamic calendar, the occurrence of full supermoons follows a seven-year cycle. In the first year, the full moon is near perigee in month 1 or 2, the next year in month 3 or 4, and so on. In the seventh year of the cycle the full moons are never very near to perigee. Approximately every 20 years the occurrences ... | Supermoon | Wikipedia | 507 | 31156672 | https://en.wikipedia.org/wiki/Supermoon | Physical sciences | Celestial mechanics | Astronomy |
Total lunar eclipses which fall on supermoon and micromoon days are relatively rare. In the 21st century, there are 87 total lunar eclipses, of which 28 are supermoons and 6 are micromoons. Almost all total lunar eclipses in Lunar Saros 129 are micromoon eclipses. An example of a supermoon lunar eclipse is the Septembe... | Supermoon | Wikipedia | 340 | 31156672 | https://en.wikipedia.org/wiki/Supermoon | Physical sciences | Celestial mechanics | Astronomy |
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occur... | Nuclear magnetic resonance | Wikipedia | 483 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
In the dominant chemistry application, the use of higher fields improves the sensitivity of the method (signal-to-noise ratio scales approximately as the power of with the magnetic field strength) and the spectral resolution. Commercial NMR spectrometers employing liquid helium cooled superconducting magnets with fiel... | Nuclear magnetic resonance | Wikipedia | 485 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), and in several types of magnetometers.
History
Nuclear magnetic resonance was first described and measured in molecular beams by Isidor Rabi in 1938, by extending the Stern–Gerl... | Nuclear magnetic resonance | Wikipedia | 503 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
In the 2020s zero- to ultralow-field nuclear magnetic resonance (ZULF NMR), a form of spectroscopy that provides abundant analytical results without the need for large magnetic fields, was developed. It is combined with a special technique that makes it possible to hyperpolarize atomic nuclei.
Theory of nuclear magnet... | Nuclear magnetic resonance | Wikipedia | 467 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
A non-zero spin is associated with a non-zero magnetic dipole moment, , via the relation where γ is the gyromagnetic ratio. Classically, this corresponds to the proportionality between the angular momentum and the magnetic dipole moment of a spinning charged sphere, both of which are vectors parallel to the rotation ... | Nuclear magnetic resonance | Wikipedia | 494 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Consider nuclei with a spin of one-half, like , or . Each nucleus has two linearly independent spin states, with m = or m = − (also referred to as spin-up and spin-down, or sometimes α and β spin states, respectively) for the z-component of spin. In the absence of a magnetic field, these states are degenerate; that i... | Nuclear magnetic resonance | Wikipedia | 491 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Magnetic resonance and radio-frequency pulses
A perturbation of nuclear spin orientations from equilibrium will occur only when an oscillating magnetic field is applied whose frequency νrf sufficiently closely matches the Larmor precession frequency νL of the nuclear magnetization. The populations of the spin-up and -d... | Nuclear magnetic resonance | Wikipedia | 411 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
This shift in the NMR frequency due to the electronic molecular orbital coupling to the external magnetic field is called chemical shift, and it explains why NMR is able to probe the chemical structure of molecules, which depends on the electron density distribution in the corresponding molecular orbitals. If a nucleus... | Nuclear magnetic resonance | Wikipedia | 478 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
RD can result in line broadening and measurement of a shorter spin-lattice relaxation time (). For instance, a sample of water in a 400 MHz NMR spectrometer will have around 20 ms, whereas its is hundreds of milliseconds. This effect is often described using modified Bloch equations that include terms for radiation d... | Nuclear magnetic resonance | Wikipedia | 203 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Radiation damping in NMR is influenced significantly by system parameters. It is notably more prominent in systems where the NMR probe possesses a high quality factor () and a high filling factor , resulting in a strong coupling between the probe coil and the sample. The phenomenon is also impacted by the concentration... | Nuclear magnetic resonance | Wikipedia | 438 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
The precessing nuclei can also fall out of alignment with each other and gradually stop producing a signal. This is called T2, "spin-spin" or transverse relaxation. Because of the difference in the actual relaxation mechanisms involved (for example, intermolecular versus intramolecular magnetic dipole-dipole interactio... | Nuclear magnetic resonance | Wikipedia | 435 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
NMR spectroscopy is one of the principal techniques used to obtain physical, chemical, electronic and structural information about molecules due to the chemical shift of the resonance frequencies of the nuclear spins in the sample. Peak splittings due to J- or dipolar couplings between nuclei are also useful. NMR spect... | Nuclear magnetic resonance | Wikipedia | 461 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
As of 1996, CW instruments were still used for routine work because the older instruments were cheaper to maintain and operate, often operating at 60 MHz with correspondingly weaker (non-superconducting) electromagnets cooled with water rather than liquid helium. One radio coil operated continuously, sweeping through ... | Nuclear magnetic resonance | Wikipedia | 509 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Applying such a pulse to a set of nuclear spins simultaneously excites all the single-quantum NMR transitions. In terms of the net magnetization vector, this corresponds to tilting the magnetization vector away from its equilibrium position (aligned along the external magnetic field). The out-of-equilibrium magnetizati... | Nuclear magnetic resonance | Wikipedia | 474 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
There are many such experiments. In some, fixed time intervals allow (among other things) magnetization transfer between nuclei and, therefore, the detection of the kinds of nuclear–nuclear interactions that allowed for the magnetization transfer. Interactions that can be detected are usually classified into two kinds.... | Nuclear magnetic resonance | Wikipedia | 447 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Professor Raymond Andrew at the University of Nottingham in the UK pioneered the development of high-resolution solid-state nuclear magnetic resonance. He was the first to report the introduction of the MAS (magic angle sample spinning; MASS) technique that allowed him to achieve spectral resolution in solids sufficien... | Nuclear magnetic resonance | Wikipedia | 511 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
As noted above, the sensitivity of nuclear magnetic resonance signals is also dependent on the presence of a magnetically susceptible nuclide and, therefore, either on the natural abundance of such nuclides or on the ability of the experimentalist to artificially enrich the molecules, under study, with such nuclides. T... | Nuclear magnetic resonance | Wikipedia | 113 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Other limitations on sensitivity arise from the quantum-mechanical nature of the phenomenon. For quantum states separated by energy equivalent to radio frequencies, thermal energy from the environment causes the populations of the states to be close to equal. Since incoming radiation is equally likely to cause stimulat... | Nuclear magnetic resonance | Wikipedia | 437 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Commonly used nuclei:
, the most commonly used spin- nucleus in NMR investigations, has been studied using many forms of NMR. Hydrogen is highly abundant, especially in biological systems. It is the nucleus providing the strongest NMR signal (apart from , which is not commonly used due to its instability and radioacti... | Nuclear magnetic resonance | Wikipedia | 496 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
, spin-1, is a medium sensitivity nucleus with wide chemical shift range. Its large quadrupole moment interferes with acquisition of high resolution spectra, limiting usefulness to smaller molecules and functional groups with a high degree of symmetry such as in the head-groups of lipids.
, spin-, is relatively common... | Nuclear magnetic resonance | Wikipedia | 314 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Other nuclei (usually used in the studies of their complexes and chemical bonding, or to detect presence of the element):
,
, ,
,
,
,
,
,
Applications
NMR is extensively used in medicine in the form of magnetic resonance imaging. NMR is widely use... | Nuclear magnetic resonance | Wikipedia | 512 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
A chemist can determine the identity of a compound by comparing the observed nuclear precession frequencies to known or predicted frequencies. Further structural data can be elucidated by observing spin–spin coupling, a process by which the precession frequency of a nucleus can be influenced by the spin orientation of ... | Nuclear magnetic resonance | Wikipedia | 443 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Electrodes and Structural Transformations: During charge and discharge cycles, the materials in the anodes and cathodes undergo local structural transformations. These changes can be monitored using NMR by analyzing the signal's line shape, line intensity, and chemical shift. These transformations are often not capture... | Nuclear magnetic resonance | Wikipedia | 311 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
In Situ and Ex Situ NMR Techniques
NMR technology can be divided into two main experimental approaches in battery research: In Situ NMR and Ex Situ NMR. Each offers unique advantages depending on the research goals.
In Situ NMR: In situ NMR enables real-time observation of chemical and structural changes in batteries w... | Nuclear magnetic resonance | Wikipedia | 509 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Non-destructive testing
Nuclear magnetic resonance is extremely useful for analyzing samples non-destructively. Radio-frequency magnetic fields easily penetrate many types of matter and anything that is not highly conductive or inherently ferromagnetic. For example, various expensive biological samples, such as nucleic... | Nuclear magnetic resonance | Wikipedia | 368 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
NMR logging, a subcategory of electromagnetic logging, measures the induced magnet moment of hydrogen nuclei (protons) contained within the fluid-filled pore space of porous media (reservoir rocks). Unlike conventional logging measurements (e.g., acoustic, density, neutron, and resistivity), which respond to both the r... | Nuclear magnetic resonance | Wikipedia | 425 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Process control
NMR has now entered the arena of real-time process control and process optimization in oil refineries and petrochemical plants. Two different types of NMR analysis are utilized to provide real time analysis of feeds and products in order to control and optimize unit operations. Time-domain NMR (TD-NMR) ... | Nuclear magnetic resonance | Wikipedia | 365 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
An important feature of EFNMR spectrometry compared with high-field NMR is that some aspects of molecular structure can be observed more clearly at low fields and low frequencies, whereas other aspects observable at high fields are not observable at low fields. This is because:
Electron-mediated heteronuclear J-coupli... | Nuclear magnetic resonance | Wikipedia | 452 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Surface magnetic resonance (or magnetic resonance sounding) is based on the principle of nuclear magnetic resonance (NMR) and measurements can be used to indirectly estimate the water content of saturated and unsaturated zones in the earth's subsurface. SNMR is used to estimate aquifer properties, including quantity of... | Nuclear magnetic resonance | Wikipedia | 145 | 25110709 | https://en.wikipedia.org/wiki/Nuclear%20magnetic%20resonance | Physical sciences | Nuclear physics | Physics |
Overexploitation, also called overharvesting or ecological overshoot, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term applies to natural resources such as water aquifers, g... | Overexploitation | Wikipedia | 421 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
One poignant example can be found in the ceremonial cloaks of Hawaiian kings, which were adorned with the feathers of the now-extinct mamo bird. Crafting a single cloak required the feathers of approximately 70,000 adult mamo birds, illustrating a staggering scale of resource extraction that ultimately contributed to i... | Overexploitation | Wikipedia | 354 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
The fastest-ever recorded extinction of megafauna occurred in New Zealand. By 1500 AD, a mere 200 years after the first human settlements, ten species of the giant moa birds were driven to extinction by the Māori. This rapid extinction underscores the significant impact humans can have on native wildlife, especially in... | Overexploitation | Wikipedia | 402 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
In 1968, the journal Science published an article by Garrett Hardin entitled "The Tragedy of the Commons". It was based on a parable that William Forster Lloyd published in 1833 to explain how individuals innocently acting in their own self-interest can overexploit, and destroy, a resource that they all share. Lloyd de... | Overexploitation | Wikipedia | 501 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
In wild fisheries, overexploitation or overfishing occurs when a fish stock has been fished down "below the size that, on average, would support the long-term maximum sustainable yield of the fishery". However, overexploitation can be sustainable.
When a fishery starts harvesting fish from a previously unexploited sto... | Overexploitation | Wikipedia | 423 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
The tragedy of the commons can be avoided within the context of fisheries if fishing effort and practices are regulated appropriately by fisheries management. One effective approach may be assigning some measure of ownership in the form of individual transferable quotas (ITQs) to fishermen. In 2008, a large scale study... | Overexploitation | Wikipedia | 397 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
Forests are overexploited when they are logged at a rate faster than reforestation takes place. Reforestation competes with other land uses such as food production, livestock grazing, and living space for further economic growth. Historically utilization of forest products, including timber and fuel wood, have played a... | Overexploitation | Wikipedia | 409 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
All living organisms require resources to survive. Overexploitation of these resources for protracted periods can deplete natural stocks to the point where they are unable to recover within a short time frame. Humans have always harvested food and other resources they need to survive. Human populations, historically, w... | Overexploitation | Wikipedia | 407 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
Where there is substantial human migration, civil unrest, or war, controls may no longer exist. With civil unrest, for example in the Congo and Rwanda, firearms have become common and the breakdown of food distribution networks in such countries leaves the resources of the natural environment vulnerable. Animals are ev... | Overexploitation | Wikipedia | 463 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
Overexploitation of species can result in knock-on or cascade effects. This can particularly apply if, through overexploitation, a habitat loses its apex predator. Because of the loss of the top predator, a dramatic increase in their prey species can occur. In turn, the unchecked prey can then overexploit their own foo... | Overexploitation | Wikipedia | 373 | 25111839 | https://en.wikipedia.org/wiki/Overexploitation | Physical sciences | Earth science basics: General | Earth science |
Many laboratories contain significant risks, and the prevention of laboratory accidents requires great care and constant vigilance. Examples of risk factors include high voltages, high and low pressures and temperatures, corrosive and toxic chemicals and chemical vapours, radiation, fire, explosions, and biohazards inc... | Laboratory safety | Wikipedia | 361 | 45266571 | https://en.wikipedia.org/wiki/Laboratory%20safety | Physical sciences | Research methods | Basics and measurement |
Anthrax - Anthrax is an acute infectious disease caused by a spore-forming bacterium called Bacillus anthracis.
Avian Flu - Avian influenza is caused by Influenza A viruses.
Botulism - Cases of botulism are usually associated with consumption of preserved foods.
Foodborne Disease - Foodborne illnesses are caused by vir... | Laboratory safety | Wikipedia | 446 | 45266571 | https://en.wikipedia.org/wiki/Laboratory%20safety | Physical sciences | Research methods | Basics and measurement |
Ergonomic Hazards
Laboratory workers are at risk for repetitive motion injuries during routine laboratory procedures such as pipetting, working at microscopes, operating microtomes, using cell counters, and keyboarding at computer workstations. Repetitive motion injuries develop over time and occur when muscles and jo... | Laboratory safety | Wikipedia | 420 | 45266571 | https://en.wikipedia.org/wiki/Laboratory%20safety | Physical sciences | Research methods | Basics and measurement |
Laboratory standard for compressed gas
Is a gas or mixture of gases in a container having an absolute pressure exceeding 40 pounds per square inch (psi) at 70 °F (21.1 °C); or
Is a gas or mixture of gases having an absolute pressure exceeding 104 psi at 130 °F (54.4 °C) regardless of the pressure at 70 °F (21.1 °C); ... | Laboratory safety | Wikipedia | 493 | 45266571 | https://en.wikipedia.org/wiki/Laboratory%20safety | Physical sciences | Research methods | Basics and measurement |
PPE includes:
Long-sleeved shirts, lab coats, aprons
Goggles
Safety gloves;
The two most common types of safety gloves are latex and nitrile gloves. Latex gloves have a high sensitivity when it comes to contact and fine control which is very suitable for surgery. Nitrile gloves are generally more durable and resis... | Laboratory safety | Wikipedia | 393 | 45266571 | https://en.wikipedia.org/wiki/Laboratory%20safety | Physical sciences | Research methods | Basics and measurement |
Glassware
Broken glass is a hazard for a sharps
Correct eye protection should be worn in most experiments involving glassware.
Inserting a glass rod through a stopper can introduce the possibility of a stab wound or sharps injury if the rod breaks. The hands must be protected.
Tubing should be cut from a barbed... | Laboratory safety | Wikipedia | 330 | 45266571 | https://en.wikipedia.org/wiki/Laboratory%20safety | Physical sciences | Research methods | Basics and measurement |
Plaice is a common name for a group of flatfish that comprises four species: the European, American, Alaskan and scale-eye plaice.
Commercially, the most important plaice is the European. The principal commercial flatfish in Europe, it is also widely fished recreationally, has potential as an aquaculture species, and ... | Plaice | Wikipedia | 510 | 25119018 | https://en.wikipedia.org/wiki/Plaice | Biology and health sciences | Acanthomorpha | null |
The species is considered by the Northwest Atlantic Fisheries Organization to be overfished, with no signs of recovery. Though they are also currently endangered in Canada due to overfishing, the Canadian government believes the species is abundant. Flatfish, as a group, are second-most caught (by weight) only to cod i... | Plaice | Wikipedia | 457 | 25119018 | https://en.wikipedia.org/wiki/Plaice | Biology and health sciences | Acanthomorpha | null |
In cuisine and culture
In North German and Danish cuisine, plaice is one of the most commonly eaten fish. Filleted, battered, and pan-fried plaice is popular hot or cold as an open sandwich topping together with remoulade sauce and lemon slices. Battered plaice is often served hot with french fries and remoulade sauce ... | Plaice | Wikipedia | 170 | 25119018 | https://en.wikipedia.org/wiki/Plaice | Biology and health sciences | Acanthomorpha | null |
Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single, non-technical user. These computers were a distinct market segment tha... | Home computer | Wikipedia | 501 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
As early as 1965, some experimental projects, such as Jim Sutherland's ECHO IV, explored the possible utility of a computer in the home. In 1969, the Honeywell Kitchen Computer was marketed as a luxury gift item, and would have inaugurated the era of home computing, but none were sold.
Computers became affordable for ... | Home computer | Wikipedia | 440 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
The rise of the home computer also led to a fundamental shift during the early 1980s in where and how computers were purchased. Traditionally, microcomputers were obtained by mail order or were purchased in person at general electronics retailers like RadioShack. Silicon Valley, in the vanguard of the personal compute... | Home computer | Wikipedia | 379 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Still, home computers competed in the same market as the consoles. A home computer was often seen as simply a higher-end purchase than a console, adding abilities and productivity potential to what would still be mainly a gaming device. A common marketing tactic was to show a computer system and console playing games s... | Home computer | Wikipedia | 348 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Books of type-in program listings like BASIC Computer Games were available, dedicated for the BASICs of most models of computer, with titles along the lines of 64 Amazing BASIC Games for the Commodore 64. While most of the programs in these books were short and simple games or demos, some titles, such as Compute!s Spee... | Home computer | Wikipedia | 384 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Introduced in August 1981, the IBM Personal Computer would eventually supplant CP/M as the standard platform used in business. This was largely due to the IBM name and the system's 16 bit open architecture, which expanded maximum memory tenfold, and also encouraged production of third-party clones. In the late 1970s, t... | Home computer | Wikipedia | 461 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Although the Apple II and Atari computers are functionally similar, Atari's home-oriented marketing resulted in a game-heavy library with much less business software. By the late 1980s, many mass merchants sold video game consoles like the Nintendo Entertainment System, but no longer sold home computers.
Toward the en... | Home computer | Wikipedia | 384 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Many home computers were superficially similar. Most had a keyboard integrated into the same case as the motherboard, or, more frequently, a mainboard. While the expandable home computers appeared from the very start (the Apple II offered as many as seven expansion slots) as the whole segment was generally aimed downma... | Home computer | Wikipedia | 459 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
In the early part of the 1980s, the dominant microprocessors used in home computers were the 8-bit MOS Technology 6502 (Apple, Commodore, Atari, BBC Micro) and Zilog Z80 (TRS-80, ZX81, ZX Spectrum, Commodore 128, Amstrad CPC). One exception was the TI-99/4, announced in 1979 with a 16-bit TMS9900 CPU. The TI was origin... | Home computer | Wikipedia | 491 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Initially, many home computers used the then-ubiquitous compact audio cassette as a storage mechanism. A rough analogy to how this worked would be to place a recorder on the phone line as a file was uploaded by modem to "save" it, and playing the recording back through the modem to "load". Most cassette implementations... | Home computer | Wikipedia | 475 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Toward the end of the home computer era, drives for a number of home computer models appeared offering disk-format compatibility with the IBM PC. The disk drives sold with the Commodore 128, Amiga, and Atari ST were all able to read and write PC disks, which themselves were undergoing the transition from 5.25" to 3.5" ... | Home computer | Wikipedia | 427 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Although modern operating systems include extensive programming libraries to ease development and promote standardization, home computer operating systems provided little support to application programs. Professionally-written software often switched out the ROM-based OS anyway to free the address space it occupied and... | Home computer | Wikipedia | 335 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
From the introduction of the IBM Personal Computer (ubiquitously known as the PC) in 1981, the market for computers meant for the corporate, business, and government sectors came to be dominated by the new machine and its MS-DOS operating system. Even basic PCs cost thousands of dollars and were far out of reach for ty... | Home computer | Wikipedia | 448 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Many decision-makers in the computer industry believed there could be a viable market for office workers who used PC/DOS computers at their jobs and would appreciate an ability to bring diskettes of data home on weeknights and weekends to continue work after-hours on their "home" computers. So, the ability to run indus... | Home computer | Wikipedia | 235 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Tandy Corporation capitalized on IBM's blunder with its PCjr-compatible Tandy 1000 in November. Like the PCjr, it was pitched as a home, education, and small-business computer, featuring joystick ports, better sound and graphics (same as the PCjr but with enhancements), combined with near-PC/DOS compatibility (unlike T... | Home computer | Wikipedia | 497 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
In 1986, UK home computer maker Amstrad began producing their PC1512 PC-compatible for sale in the UK. Later they would market the machine in the US as the PC6400. In June 1987, an improved model was produced as the PC1640. These machines had fast 8086 CPUs, enhanced CGA graphics, and were feature-laden for their modes... | Home computer | Wikipedia | 432 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
Still, later prices of white box PC clone computers by various manufacturers became competitive with the higher-end home computers (see below). Throughout the 1980s, costs and prices continued to be driven down by: advanced circuit design and manufacturing, multi-function expansion cards, shareware applications such as... | Home computer | Wikipedia | 476 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
The second generation of MSX computers (MSX2) achieved the performance of high-performance computers using a high-speed video processor (Yamaha V9938) capable of handling resolutions of 512424 pixels, and 256 simultaneous colors from a palette of 512.
MSX
MSX was a standard for a home computing architecture that was... | Home computer | Wikipedia | 449 | 25122906 | https://en.wikipedia.org/wiki/Home%20computer | Technology | Computer hardware | null |
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