In physics, the eightfold way is an organizational scheme for a class of subatomic particles known as hadrons that led to the development of the quark model. American physicist Murray Gell-Mann and Israeli physicist Yuval Ne'eman both proposed the idea in 1961.[1][2][notes 1] The name comes from Gell-Mann's 1961 paper and is an allusion to the Noble Eightfold Path of Buddhism.[3]
Baryon decuplet[edit]
The organizational principles of the eightfold way also apply to the spin-32 baryons, forming a decuplet.
Δ−
,
Δ0
,
Δ+
, and
Δ++
delta baryons
Σ∗−
,
Σ∗0
, and
Σ∗+
sigma baryons
Ξ∗−
and
Ξ∗0
xi baryons
Ω−
omega baryon
However, one of the particles of this decuplet had never been previously observed when the eightfold way was proposed. Gell-Mann called this particle the
Ω−
and predicted in 1962 that it would have a strangeness −3, electric charge −1 and a mass near 1680 MeV/c2. In 1964, a particle closely matching these predictions was discovered[8] by a particle acceleratorgroup at Brookhaven. Gell-Mann received the 1969 Nobel Prize in Physics for his work on the theory of elementary particles.
https://en.wikipedia.org/wiki/Eightfold_way_(physics)
infrared microwave gas matricing polymer system rising hyd-ox-cat rs (w sod tipper double riser double polymer) rising-sys-evol-bt and etc. trihydrocat-air surr (sol-liq matrixing w/ gas evo sys; nested systems)
Making ferrofluid from scratch
above. nile red
Aluminum and Mercury
| Main isotopes of mercury | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||
| Other properties | |
|---|---|
| Natural occurrence | primordial |
| Crystal structure | rhombohedral |
| Speed of sound | liquid: 1451.4 m/s (at 20 °C) |
| Thermal expansion | 60.4 µm/(m⋅K) (at 25 °C) |
| Thermal conductivity | 8.30 W/(m⋅K) |
| Electrical resistivity | 961 nΩ⋅m (at 25 °C) |
| Magnetic ordering | diamagnetic[2] |
| Molar magnetic susceptibility | −33.44×10−6 cm3/mol (293 K)[3] |
| CAS Number | 7439-97-6 |
| Atomic properties | |
|---|---|
| Oxidation states | −2 , +1, +2 (a mildly basicoxide) |
| Electronegativity | Pauling scale: 2.00 |
| Ionization energies |
|
| Atomic radius | empirical: 151 pm |
| Covalent radius | 132±5 pm |
| Van der Waals radius | 155 pm |
| Physical properties | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Phase at STP | liquid | ||||||||||||||
| Melting point | 234.3210 K (−38.8290 °C, −37.8922 °F) | ||||||||||||||
| Boiling point | 629.88 K (356.73 °C, 674.11 °F) | ||||||||||||||
| Density (near r.t.) | 13.534 g/cm3 | ||||||||||||||
| Triple point | 234.3156 K, 1.65×10−7 kPa | ||||||||||||||
| Critical point | 1750 K, 172.00 MPa | ||||||||||||||
| Heat of fusion | 2.29 kJ/mol | ||||||||||||||
| Heat of vaporization | 59.11 kJ/mol | ||||||||||||||
| Molar heat capacity | 27.983 J/(mol·K) | ||||||||||||||
Vapor pressure
| |||||||||||||||
The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state, which may be positive, negative or zero, is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic, with no covalent component. This is never exactly true for real bonds.
The oxidation state of an atom does not represent the "real" formal charge on that atom, or any other actual atomic property. This is particularly true of high oxidation states, where the ionization energy required to produce a multiply positive ion is far greater than the energies available in chemical reactions. Additionally, the oxidation states of atoms in a given compound may vary depending on the choice of electronegativity scale used in their calculation. Thus, the oxidation state of an atom in a compound is purely a formalism. It is nevertheless important in understanding the nomenclature conventions of inorganic compounds. Also, several observations regarding chemical reactions may be explained at a basic level in terms of oxidation states.
Oxidation states are typically represented by integers which may be positive, zero, or negative. In some cases, the average oxidation state of an element is a fraction, such as 83 for iron in magnetite Fe
3O
4 (see below). The highest known oxidation state is reported to be +9 in the tetroxoiridium(IX) cation (IrO+
4).[1] It is predicted that even a +12 oxidation state may be achievable by uranium in the unusual hexoxide UO6.[2] The lowest oxidation state is −5, as for boron in Al3BC.[3]
In inorganic nomenclature, the oxidation state is represented by a Roman numeral placed after the element name inside the parenthesis or as a superscript after the element symbol, e.g. Iron(III) oxide.
The term oxidation was first used by Antoine Lavoisier to signify the reaction of a substance with oxygen. Much later, it was realized that the substance, upon being oxidized, loses electrons, and the meaning was extended to include other reactions in which electrons are lost, regardless of whether oxygen was involved. The increase in the oxidation state of an atom, through a chemical reaction, is known as oxidation; a decrease in oxidation state is known as a reduction. Such reactions involve the formal transfer of electrons: a net gain in electrons being a reduction, and a net loss of electrons being oxidation. For pure elements, the oxidation state is zero.
https://en.wikipedia.org/wiki/Oxidation_state
Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. This process thereby changes a nuclear proton to a neutron and simultaneously causes the emission of an electron neutrino.
Since this single emitted neutrino carries the entire decay energy, it has this single characteristic energy. Similarly, the momentum of the neutrino emission causes the daughter atom to recoil with a single characteristic momentum.
The resulting daughter nuclide, if it is in an excited state, then transitions to its ground state. Usually, a gamma ray is emitted during this transition, but nuclear de-excitation may also take place by internal conversion.
Following capture of an inner electron from the atom, an outer electron replaces the electron that was captured and one or more characteristic X-ray photons is emitted in this process. Electron capture sometimes also results in the Auger effect, where an electron is ejected from the atom's electron shell due to interactions between the atom's electrons in the process of seeking a lower energy electron state.
Following electron capture, the atomic number is reduced by one, the neutron number is increased by one, and there is no change in mass number. Simple electron capture by itself results in a neutral atom, since the loss of the electron in the electron shell is balanced by a loss of positive nuclear charge. However, a positive atomic ion may result from further Auger electron emission.
Electron capture is an example of weak interaction, one of the four fundamental forces.
Electron capture is the primary decay mode for isotopes with a relative superabundance of protons in the nucleus, but with insufficient energy difference between the isotope and its prospective daughter (the isobar with one less positive charge) for the nuclide to decay by emitting a positron. Electron capture is always an alternative decay mode for radioactive isotopes that do have sufficient energy to decay by positron emission. Electron capture is sometimes included as a type of beta decay,[1]because the basic nuclear process, mediated by the weak force, is the same. In nuclear physics, beta decay is a type of radioactive decay in which a beta ray (fast energetic electron or positron) and a neutrino are emitted from an atomic nucleus. Electron capture is sometimes called inverse beta decay, though this term usually refers to the interaction of an electron antineutrino with a proton.[2]
If the energy difference between the parent atom and the daughter atom is less than 1.022 MeV, positron emission is forbidden as not enough decay energy is available to allow it, and thus electron capture is the sole decay mode. For example, rubidium-83 (37 protons, 46 neutrons) will decay to krypton-83 (36 protons, 47 neutrons) solely by electron capture (the energy difference, or decay energy, is about 0.9 MeV).
Reaction details[edit]
The electron that is captured is one of the atom's own electrons, and not a new, incoming electron, as might be suggested by the way the above reactions are written. A few examples of electron capture are:
Radioactive isotopes that decay by pure electron capture can be inhibited from radioactive decay if they are fully ionized ("stripped" is sometimes used to describe such ions). It is hypothesized that such elements, if formed by the r-process in exploding supernovae, are ejected fully ionized and so do not undergo radioactive decay as long as they do not encounter electrons in outer space. Anomalies in elemental distributions are thought[by whom?] to be partly a result of this effect on electron capture. Inverse decays can also be induced by full ionisation; for instance, 163
Ho
decays into 163
Dy
by electron capture; however, a fully ionised 163
Dy
decays into a bound state of 163
Ho
by the process of bound-state β− decay.[8]
Chemical bonds can also affect the rate of electron capture to a small degree (in general, less than 1%) depending on the proximity of electrons to the nucleus. For example, in 7Be, a difference of 0.9% has been observed between half-lives in metallic and insulating environments.[9] This relatively large effect is due to the fact that beryllium is a small atom that employs valence electrons that are close to the nucleus, and also in orbitals with no orbital angular momentum. Electrons in s orbitals (regardless of shell or primary quantum number), have a probability antinode at the nucleus, and are thus far more subject to electron capture than p or d electrons, which have a probability node at the nucleus.
Around the elements in the middle of the periodic table, isotopes that are lighter than stable isotopes of the same element tend to decay through electron capture, while isotopes heavier than the stable ones decay by electron emission. Electron capture happens most often in the heavier neutron-deficient elements where the mass change is smallest and positron emission isn't always possible. When the loss of mass in a nuclear reaction is greater than zero but less than 2m[0-1e-],[clarification needed] the process cannot occur by positron emission, but occurs spontaneously for electron capture.
https://en.wikipedia.org/wiki/Electron_capture
Vertical ionization energy[edit]
Due to the possible changes in molecular geometry that may result from ionization, additional transitions may exist between the vibrational ground state of the neutral species and vibrational excited states of the positive ion. In other words, ionization is accompanied by vibrational excitation. The intensity of such transitions is explained by the Franck–Condon principle, which predicts that the most probable and intense transition corresponds to the vibrationally excited state of the positive ion that has the same geometry as the neutral molecule. This transition is referred to as the "vertical" ionization energy since it is represented by a completely vertical line on a potential energy diagram (see Figure).
For a diatomic molecule, the geometry is defined by the length of a single bond. The removal of an electron from a bonding molecular orbital weakens the bond and increases the bond length. In Figure 1, the lower potential energy curve is for the neutral molecule and the upper surface is for the positive ion. Both curves plot the potential energy as a function of bond length. The horizontal lines correspond to vibrational levels with their associated vibrational wave functions. Since the ion has a weaker bond, it will have a longer bond length. This effect is represented by shifting the minimum of the potential energy curve to the right of the neutral species. The adiabatic ionization is the diagonal transition to the vibrational ground state of the ion. Vertical ionization may involve vibrational excitation of the ionic state and therefore requires greater energy.
In many circumstances, the adiabatic ionization energy is often a more interesting physical quantity since it describes the difference in energy between the two potential energy surfaces. However, due to experimental limitations, the adiabatic ionization energy is often difficult to determine, whereas the vertical detachment energy is easily identifiable and measurable.
https://en.wikipedia.org/wiki/Ionization_energy#Vertical_ionization_energy
https://en.wikipedia.org/wiki/Mass–energy_equivalence
https://en.wikipedia.org/wiki/Spacetime#Mass-energy_relationship
https://en.wikipedia.org/wiki/Nuclear_binding_energy
https://en.wikipedia.org/wiki/Black_hole
https://en.wikipedia.org/wiki/Electron_hole
https://en.wikipedia.org/wiki/Gravity#Equivalence_principle
https://www.researchgate.net/publication/233728601_On_the_Mass-Energy_and_Charge-Energy_Equivalences
https://www.npl.washington.edu/eotwash/equivalence-principle
http://www.sciencepublishinggroup.com/journal/paperinfo?journalid=122&doi=10.11648/j.ajmp.20200904.12
https://en.wikipedia.org/wiki/Mass-to-charge_ratio
https://en.wikipedia.org/wiki/Cathode-ray_tube
https://en.wikipedia.org/wiki/Deflection_(physics)
https://en.wikipedia.org/wiki/Lead_glass
https://en.wikipedia.org/wiki/Cold_cathode
https://en.wikipedia.org/wiki/Electrostatic_deflection
A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field.[1]
https://en.wikipedia.org/wiki/Magnetic_field
A magnetic domain is a region within a magnetic material in which the magnetization is in a uniform direction. This means that the individual magnetic moments of the atoms are aligned with one another and they point in the same direction. When cooled below a temperature called the Curie temperature, the magnetization of a piece of ferromagneticmaterial spontaneously divides into many small regions called magnetic domains. The magnetization within each domain points in a uniform direction, but the magnetization of different domains may point in different directions. Magnetic domain structure is responsible for the magnetic behavior of ferromagnetic materials like iron, nickel, cobaltand their alloys, and ferrimagnetic materials like ferrite. This includes the formation of permanent magnets and the attraction of ferromagnetic materials to a magnetic field. The regions separating magnetic domains are called domain walls, where the magnetization rotates coherently from the direction in one domain to that in the next domain. The study of magnetic domains is called micromagnetics.
Magnetic domains form in materials which have magnetic ordering; that is, their dipoles spontaneously align due to the exchange interaction. These are the ferromagnetic, ferrimagnetic and antiferromagnetic materials. Paramagnetic and diamagnetic materials, in which the dipoles align in response to an external field but do not spontaneously align, do not have magnetic domains.
https://en.wikipedia.org/wiki/Magnetic_domain
A neodymium magnet (also known as NdFeB, NIB or Neo magnet) is the most widely used[1] type of rare-earth magnet. It is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure.[2] Developed independently in 1984 by General Motors and Sumitomo Special Metals,[3][4][5] neodymium magnets are the strongest type of permanent magnet available commercially.[2][6] Because of different manufacturing processes, they are divided into two subcategories, namely sintered NdFeB magnets and bonded NdFeB magnets.[7][8] They have replaced other types of magnets in many applications in modern products that require strong permanent magnets, such as electric motors in cordless tools, hard disk drives and magnetic fasteners.
Sintered Nd2Fe14B tends to be vulnerable to corrosion, especially along grain boundaries of a sintered magnet. This type of corrosion can cause serious deterioration, including crumbling of a magnet into a powder of small magnetic particles, or spalling of a surface layer.
This vulnerability is addressed in many commercial products by adding a protective coating to prevent exposure to the atmosphere. Nickel plating or two-layered copper-nickel plating are the standard methods, although plating with other metals, or polymer and lacquer protective coatings, are also in use.[21]
https://en.wikipedia.org/wiki/Neodymium_magnet
Xenon is a chemical element with the symbol Xe and atomic number 54. It is a colorless, dense, odorless noble gas found in Earth's atmosphere in trace amounts.[11] Although generally unreactive, xenon can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized.[12][13][14]
Xenon is used in flash lamps[15] and arc lamps,[16] and as a general anesthetic.[17] The first excimer laser design used a xenon dimer molecule (Xe2) as the lasing medium,[18] and the earliest laser designs used xenon flash lamps as pumps.[19] Xenon is used to search for hypothetical weakly interacting massive particles[20] and as the propellant for ion thrusters in spacecraft.[21]
Naturally occurring xenon consists of seven stable isotopes and two long-lived radioactive isotopes. More than 40 unstable xenon isotopes undergo radioactive decay, and the isotope ratios of xenon are an important tool for studying the early history of the Solar System.[22] Radioactive xenon-135 is produced by beta decay from iodine-135 (a product of nuclear fission), and is the most significant (and unwanted) neutron absorber in nuclear reactors.[23]
https://en.wikipedia.org/wiki/Xenon
The trihydrogen cation or protonated molecular hydrogen is a cation (positive ion) with formula H+
3, consisting of three hydrogen nuclei (protons) sharing two electrons.
The trihydrogen cation is one of the most abundant ions in the universe. It is stable in the interstellar medium (ISM) due to the low temperature and low density of interstellar space. The role that H+
3 plays in the gas-phase chemistry of the ISM is unparalleled by any other molecular ion.
The trihydrogen cation is the simplest triatomic molecule, because its two electrons are the only valence electrons in the system. It is also the simplest example of a three-center two-electron bond system.
https://en.wikipedia.org/wiki/Trihydrogen_cation
A three-center two-electron (3c–2e) bond is an electron-deficient chemical bond where three atoms share two electrons. The combination of three atomic orbitalsform three molecular orbitals: one bonding, one non-bonding, and one anti-bonding. The two electrons go into the bonding orbital, resulting in a net bonding effect and constituting a chemical bond among all three atoms. In many common bonds of this type, the bonding orbital is shifted towards two of the three atoms instead of being spread equally among all three. An example of a 3c–2e bond is the trihydrogen cation and diborane H
3+ and B
2H
6. In some structures, the three atoms form an angular geometry, leading to a bent bond.
https://en.wikipedia.org/wiki/Three-center_two-electron_bond
https://en.wikipedia.org/wiki/Air
https://en.wikipedia.org/wiki/hydrogen
https://en.wikipedia.org/wiki/strontium_oxide
https://en.wikipedia.org/wiki/catalyst
https://en.wikipedia.org/wiki/sodium
https://en.wikipedia.org/wiki/oxygen
https://en.wikipedia.org/wiki/nitrogen
https://en.wikipedia.org/wiki/sulfur
https://en.wikipedia.org/wiki/phosphorus
https://en.wikipedia.org/wiki/silicone
https://en.wikipedia.org/wiki/Three-center_two-electron_bond
https://en.wikipedia.org/wiki/Atmosphere_of_Earth
https://en.wikipedia.org/wiki/cesium
https://en.wikipedia.org/wiki/Bent_bond
https://en.wikipedia.org/wiki/Bent_bond
https://en.wikipedia.org/wiki/Beam
https://en.wikipedia.org/wiki/Ethylene_oxide
https://en.wikipedia.org/wiki/Bent_bond
https://en.wikipedia.org/wiki/Low-barrier_hydrogen_bond
https://en.wikipedia.org/wiki/Resonance-assisted_hydrogen_bond
https://en.wikipedia.org/wiki/Dihydrogen_bond
https://en.wikipedia.org/wiki/C–H···O_interaction
https://en.wikipedia.org/wiki/London_dispersion_force
https://en.wikipedia.org/wiki/Metal_aromaticity
https://en.wikipedia.org/wiki/Hypervalent_molecule
https://en.wikipedia.org/wiki/Agostic_interaction
https://en.wikipedia.org/wiki/Electron_deficiency
https://en.wikipedia.org/wiki/Bent_bond
https://en.wikipedia.org/wiki/Bent_bond
barium radon
hydrogen fusion helium
hydrogen oxygen water
https://en.wikipedia.org/wiki/Periodic_table#/media/File:Periodic_table_(32-col,_enwiki),_black_and_white.png
https://en.wikipedia.org/wiki/Henry_Cavendish
Lavosier, Cavendish, Schönbeinhttps://en.wikipedia.org/wiki/Metallophilic_interaction
https://en.wikipedia.org/wiki/Chalcogen_bond
https://en.wikipedia.org/wiki/Pi-Stacking_(chemistry)
https://en.wikipedia.org/wiki/Pi-Stacking_(chemistry)
https://en.wikipedia.org/wiki/Cation–pi_interaction
https://en.wikipedia.org/wiki/Salt_bridge_(protein_and_supramolecular)
https://en.wikipedia.org/wiki/Cation–pi_interaction#Anion–π_interaction
https://en.wikipedia.org/wiki/Intercalation_(chemistry)
In 1962, a group of researchers at Bell Laboratories discovered laser action in xenon,[133] and later found that the laser gain was improved by adding helium to the lasing medium.[134][135] The first excimer laser used a xenon dimer (Xe2) energized by a beam of electrons to produce stimulated emission at an ultraviolet wavelength of 176 nm.[18] Xenon chloride and xenon fluoride have also been used in excimer (or, more accurately, exciplex) lasers.[136]
Xenon is used as a "starter gas" in high pressure sodium lamps. It has the lowest thermal conductivity and lowest ionization potential of all the non-radioactive noble gases. As a noble gas, it does not interfere with the chemical reactions occurring in the operating lamp. The low thermal conductivity minimizes thermal losses in the lamp while in the operating state, and the low ionization potential causes the breakdown voltage of the gas to be relatively low in the cold state, which allows the lamp to be more easily started.[132]
Continuous, short-arc, high pressure xenon arc lamps have a color temperature closely approximating noon sunlight and are used in solar simulators. That is, the chromaticity of these lamps closely approximates a heated black body radiator at the temperature of the Sun. First introduced in the 1940s, these lamps replaced the shorter-lived carbon arc lamps in movie projectors.[16] They are also employed in typical 35mm, IMAX, and digital film projection systems. They are an excellent source of short wavelength ultraviolet radiation and have intense emissions in the near infrared used in some night visionsystems. Xenon is used as a starter gas in metal halide lamps for automotive headlights, and high-end "tactical" flashlights.
The individual cells in a plasma display contain a mixture of xenon and neon ionized with electrodes. The interaction of this plasma with the electrodes generates ultraviolet photons, which then excite the phosphor coating on the front of the display.[130][131]
Surgery[edit]
The xenon chloride excimer laser has certain dermatological uses.[166]
NMR spectroscopy[edit]
Because of the xenon atom's large, flexible outer electron shell, the NMR spectrum changes in response to surrounding conditions and can be used to monitor the surrounding chemical circumstances. For instance, xenon dissolved in water, xenon dissolved in hydrophobic solvent, and xenon associated with certain proteins can be distinguished by NMR.[167][168]
Hyperpolarized xenon can be used by surface chemists. Normally, it is difficult to characterize surfaces with NMR because signals from a surface are overwhelmed by signals from the atomic nuclei in the bulk of the sample, which are much more numerous than surface nuclei. However, nuclear spins on solid surfaces can be selectively polarized by transferring spin polarization to them from hyperpolarized xenon gas. This makes the surface signals strong enough to measure and distinguish from bulk signals.[169][170]
Imaging[edit]
Gamma emission from the radioisotope 133Xe of xenon can be used to image the heart, lungs, and brain, for example, by means of single photon emission computed tomography. 133Xe has also been used to measure blood flow.[157][158][159]
Xenon, particularly hyperpolarized 129Xe, is a useful contrast agent for magnetic resonance imaging (MRI). In the gas phase, it can image cavities in a porous sample, alveoli in lungs, or the flow of gases within the lungs.[160][161] Because xenon is soluble both in water and in hydrophobic solvents, it can image various soft living tissues.[162][163][164]
Xenon-129 is currently being used as a visualization agent in MRI scans. When a patient inhales hyperpolarized xenon-129 ventilation and gas exchange in the lungs can be imaged and quantified. Unlike xenon-133, xenon-129 is non-ionizing and is safe to be inhaled with no adverse effects.[165]
Because they are strongly oxidative, many oxygen–xenon compounds are toxic; they are also explosive (highly exothermic), breaking down to elemental xenon and diatomic oxygen (O2) with much stronger chemical bonds than the xenon compounds.[182]
Xenon gas can be safely kept in normal sealed glass or metal containers at standard temperature and pressure. However, it readily dissolves in most plastics and rubber, and will gradually escape from a container sealed with such materials.[183] Xenon is non-toxic, although it does dissolve in blood and belongs to a select group of substances that penetrate the blood–brain barrier, causing mild to full surgical anesthesia when inhaled in high concentrations with oxygen.[182]
Xenon compounds
show
Pharmacodynamics
show
Authority control Edit this at Wikidata
Categories: Xenon5-HT3 antagonistsATPase inhibitorsChemical elementsGeneral anestheticsGlycine receptor agonistsIndustrial gasesNicotinic antagonistsNMDA receptor antagonistsNoble gasesRocket propellants
https://en.wikipedia.org/wiki/Xenon#Gas-discharge_lamps
Buoyant levitation[edit]
Gases at high pressure can have a density exceeding that of some solids. Thus they can be used to levitate solid objects through buoyancy.[5] Noble gases are preferred for their non-reactivity. Xenon is the densest non-radioactive noble gas, at 5.894g/L. Xenon has been used to levitate polyethylene, at a pressure of 154atm.
Casimir force[edit]
Scientists have discovered a way of levitating ultra small objects by manipulating the so-called Casimir force, which normally causes objects to stick together due to forces predicted by quantum field theory. This is, however, only possible for micro-objects.[6][7]
Uses[edit]
Maglev trains[edit]
Magnetic levitation is used to suspend trains without touching the track. This permits very high speeds, and greatly reduces the maintenance requirements for tracks and vehicles, as little wear occurs. This also means there is no friction, so the only force acting against it is air resistance.
https://en.wikipedia.org/wiki/Levitation#Buoyant_levitation
https://en.wikipedia.org/wiki/Periodic_table
Chemical properties
Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate, nitrate, and chloride. Like silver, mercury reacts with atmospheric hydrogen sulfide. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use activated carbon and powdered zinc).[11]
Amalgams
Mercury dissolves many metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally been used to trade mercury. Several other first row transition metals with the exception of manganese, copper and zinc are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include platinum.[12][13] Sodium amalgam is a common reducing agent in organic synthesis, and is also used in high-pressure sodium lamps.
Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth (as in iron rusting), even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.[14]
Mercury embrittlement is the most common type of liquid metal embrittlement.
https://en.wikipedia.org/wiki/Mercury_(element)
Former mines in Italy, the United States and Mexico, which once produced a large proportion of the world supply, have now been completely mined out or, in the case of Slovenia (Idrija) and Spain (Almadén), shut down due to the fall of the price of mercury. Nevada's McDermitt Mine, the last mercury mine in the United States, closed in 1992. The price of mercury has been highly volatile over the years and in 2006 was $650 per 76-pound (34.46 kg) flask.[32]
Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is
- HgS + O2 → Hg + SO2
https://en.wikipedia.org/wiki/Mercury_(element)
Mercury exists in two oxidation states, I and II. Despite claims otherwise,[37] Hg(III) and Hg(IV) compounds remain unknown,[38][39] though short-lived Hg(III) has been achieved through electrochemical oxidation.[40]
Compounds of mercury(I)
Unlike its lighter neighbors, cadmium and zinc, mercury usually forms simple stable compounds with metal-metal bonds. Most mercury(I) compounds are diamagneticand feature the dimeric cation, Hg2+
2. Stable derivatives include the chloride and nitrate. Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to Hg2+
and elemental mercury.[41] Mercury(I) chloride, a colorless solid also known as calomel, is really the compound with the formula Hg2Cl2, with the connectivity Cl-Hg-Hg-Cl. It is a standard in electrochemistry. It reacts with chlorine to give mercuric chloride, which resists further oxidation. Mercury(I) hydride, a colorless gas, has the formula HgH, containing no Hg-Hg bond.
Indicative of its tendency to bond to itself, mercury forms mercury polycations, which consist of linear chains of mercury centers, capped with a positive charge. One example is Hg2+
3(AsF−
6)
2.[42]
Compounds of mercury(II)
They form tetrahedral complexes with other ligands but the halides adopt linear coordination geometry, somewhat like Ag+ does. Best known is mercury(II) chloride, an easily sublimating white solid. HgCl2 forms coordination complexes that are typically tetrahedral, e.g. HgCl2−
4.
Mercury(II) oxide, the main oxide of mercury, arises when the metal is exposed to air for long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by Joseph Priestley in an early synthesis of pure oxygen.[11] Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver.
Being a soft metal, mercury forms very stable derivatives with the heavier chalcogens.
Mercury fulminate is a detonator widely used in explosives.[5]
Niche uses
Gaseous mercury is used in mercury-vapor lamps and some "neon sign" type advertising signs and fluorescent lamps. Those low-pressure lamps emit very spectrally narrow lines, which are traditionally used in optical spectroscopy for calibration of spectral position. Commercial calibration lamps are sold for this purpose; reflecting a fluorescent ceiling light into a spectrometer is a common calibration practice.[63] Gaseous mercury is also found in some electron tubes, including ignitrons, thyratrons, and mercury arc rectifiers.[64] It is also used in specialist medical care lamps for skin tanning and disinfection.[65] Gaseous mercury is added to cold cathode argon-filled lamps to increase the ionization and electrical conductivity. An argon-filled lamp without mercury will have dull spots and will fail to light correctly. Lighting containing mercury can be bombarded/oven pumped only once. When added to neon filled tubes the light produced will be inconsistent red/blue spots until the initial burning-in process is completed; eventually it will light a consistent dull off-blue color.[66]
The Deep Space Atomic Clock (DSAC) under development by the Jet Propulsion Laboratory utilises mercury in a linear ion-trap-based clock. The novel use of mercury allows very compact atomic clocks, with low energy requirements, and is therefore ideal for space probes and Mars missions.[67]
https://en.wikipedia.org/wiki/Mercury_(element)
https://en.wikipedia.org/wiki/Mercury_polycations
https://en.wikipedia.org/wiki/Iridium_tetroxide
https://en.wikipedia.org/wiki/Boron
https://en.wikipedia.org/wiki/Magnetite
https://en.wikipedia.org/wiki/Pseudohalogen
Chemically, aluminium is a weak metal in the boron group...
However, minute traces of 26Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons.
https://en.wikipedia.org/wiki/Aluminium
https://en.wikipedia.org/wiki/Amphoterism
Chemical reactivity[edit]
Hydrides[edit]
Most of the elements in the boron group show increasing reactivity as the elements get heavier in atomic mass and higher in atomic number. Boron, the first element in the group, is generally unreactive with many elements except at high temperatures, although it is capable of forming many compounds with hydrogen, sometimes called boranes.[6] The simplest borane is diborane, or B2H6.[5] Another example is B10H14.
The next group-13 elements, aluminium and gallium, form fewer stable hydrides, although both AlH3 and GaH3 exist. Indium, the next element in the group, is not known to form many hydrides, except in complex compounds such as the phosphinecomplex H3InP(Cy)3.[7] No stable compound of thallium and hydrogen has been synthesized in any laboratory.
Oxides[edit]
All of the boron-group elements are known to form a trivalent oxide, with two atoms of the element bonded covalently with three atoms of oxygen. These elements show a trend of increasing pH (from acidic to basic).[13] Boron oxide (B2O3) is slightly acidic, aluminium and gallium oxide (Al2O3 and Ga2O3 respectively) are amphoteric, indium(III) oxide (In2O3) is nearly amphoteric, and thallium(III) oxide (Tl2O3) is a Lewis base because it dissolves in acids to form salts. Each of these compounds are stable, but thallium oxide decomposes at temperatures higher than 875 °C.
Halides[edit]
The elements in group 13 are also capable of forming stable compounds with the halogens, usually with the formula MX3(where M is a boron-group element and X is a halogen.)[14] Fluorine, the first halogen, is able to form stable compounds with every element that has been tested (except neon and helium),[15] and the boron group is no exception. It is even hypothesized that nihonium could form a compound with fluorine, NhF3, before spontaneously decaying due to nihonium's radioactivity. Chlorine also forms stable compounds with all of the elements in the boron group, including thallium, and is hypothesized to react with nihonium. All of the elements will react with bromine under the right conditions, as with the other halogens but less vigorously than either chlorine or fluorine. Iodine will react with all natural elements in the periodic table except for the noble gases, and is notable for its explosive reaction with aluminium to form 2AlI3.[16] Astatine, the heaviest halogen, has only formed a few compounds, due to its radioactivity and short half-life, and no reports of a compound with an At–Al, –Ga, –In, –Tl, or –Nh bond have been seen, although scientists think that it should form salts with metals.[17]
| showSome common chemical compounds of the boron group[5] |
|---|
Cosmic voids are vast spaces between filaments (the largest-scale structures in the universe), which contain very few or no galaxies. The cosmological evolution of the void regions differs drastically from the evolution of the Universe as a whole: there is a long stage when the curvature term dominates, which prevents the formation of galaxy clusters and massive galaxies. Hence, although even the emptiest regions of voids contain more than ~15% of the average matter density of the Universe, the voids look almost empty for an observer. [1] Voids typically have a diameter of 10 to 100 megaparsecs (30 to 300 million light years); particularly large voids, defined by the absence of rich superclusters, are sometimes called supervoids. They were first discovered in 1978 in a pioneering study by Stephen Gregory and Laird A. Thompson at the Kitt Peak National Observatory.[2]
Voids are believed to have been formed by baryon acoustic oscillations in the Big Bang, collapses of mass followed by implosions of the compressed baryonic matter. Starting from initially small anisotropies from quantum fluctuations in the early universe, the anisotropies grew larger in scale over time. Regions of higher density collapsed more rapidly under gravity, eventually resulting in the large-scale, foam-like structure or "cosmic web" of voids and galaxy filaments seen today. Voids located in high-density environments are smaller than voids situated in low-density spaces of the universe.[3]
Voids appear to correlate with the observed temperature of the cosmic microwave background (CMB) because of the Sachs–Wolfe effect. Colder regions correlate with voids and hotter regions correlate with filaments because of gravitational redshifting. As the Sachs–Wolfe effect is only significant if the universe is dominated by radiation or dark energy, the existence of voids is significant in providing physical evidence for dark energy.[4][5]
https://en.wikipedia.org/wiki/Void_(astronomy)
https://en.wikipedia.org/wiki/Oscilloscope
The earliest and simplest type of oscilloscope consisted of a cathode ray tube, a vertical amplifier, a timebase, a horizontal amplifier and a power supply. These are now called "analog" oscilloscopes to distinguish them from the "digital" oscilloscopes that became common in the 1990s and 2000s.
https://en.wikipedia.org/wiki/Oscilloscope_types#Cathode-ray_oscilloscope
Before the introduction of the CRO in its current form, the cathode ray tube had already been in use as a measuring device. The cathode ray tube is an evacuated glass envelope, similar to that in a black-and-white television set, with its flat face covered in a fluorescent material (the phosphor). The screen is typically less than 20 cm in diameter, much smaller than the one in a television set. Older CROs had round screens or faceplates, while newer CRTs in better CROs have rectangular faceplates.
In the neck of the tube is an electron gun, which is a small heated metal cylinder with a flat end coated with electron-emitting oxides. Close to it is a much-larger-diameter cylinder carrying a disc at its cathode end with a round hole in it; it's called a "grid" (G1), by historic analogy with amplifier vacuum-tube grids. A small negative grid potential (referred to the cathode) is used to block electrons from passing through the hole when the electron beam needs to be turned off, as during sweep retrace or when no trigger events occur.
However, when G1 becomes less negative with respect to the cathode, another cylindrical electrode designated G2, which is hundreds of volts positive referred to the cathode, attracts electrons through the hole. Their trajectories converge as they pass through the hole, creating quite-small diameter "pinch" called the crossover. Following electrodes ("grids"), electrostatic lenses, focus this crossover onto the screen; the spot is an image of the crossover.
Typically, the CRT runs at roughly -2 kV or so, and various methods are used to correspondingly offset the G1 voltage. Proceeding along the electron gun, the beam passes through the imaging lenses and first anode, emerging with an energy in electron-volts equal to that of the cathode. The beam passes through one set of deflection plates , then the other, where it is deflected as required to the phosphor screen.
The average voltage of the deflection plates is relatively close to ground, because they have to be directly connected to the vertical output stage.
By itself, once the beam leaves the deflection region, it can produce a usefully bright trace. However, for higher bandwidth CROs where the trace may move more rapidly across the phosphor screen, a positive post-deflection acceleration ("PDA") voltage of over 10,000 volts is often used, increasing the energy (speed) of the electrons that strike the phosphor. The kinetic energy of the electrons is converted by the phosphor into visible light at the point of impact.
When switched on, a CRT normally displays a single bright dot in the center of the screen, but the dot can be moved about electrostatically or magnetically. The CRT in an oscilloscope always uses electrostatic deflection. Ordinary electrostatic deflection plates can typically move the beam roughly only 15 degrees or so off-axis, which means that oscilloscope CRTs have long, narrow funnels, and for their screen size, are usually quite long. It's the CRT length that makes CROs "deep", from front to back. Modern flat-panel oscilloscopes have no need for such rather-extreme dimensions; their shapes tend to be more like one kind of rectangular lunchbox.
Between the electron gun and the screen are two opposed pairs of metal plates called the deflection plates. The vertical amplifier generates a potential difference across one pair of plates, giving rise to a vertical electric field through which the electron beam passes. When the plate potentials are the same, the beam is not deflected. When the top plate is positive with respect to the bottom plate, the beam is deflected upwards; when the field is reversed, the beam is deflected downwards. The horizontal amplifier does a similar job with the other pair of deflection plates, causing the beam to move left or right. This deflection system is called electrostatic deflection, and is different from the electromagnetic deflection system used in television tubes. In comparison to magnetic deflection, electrostatic deflection can more readily follow random and fast changes in potential, but is limited to small deflection angles.
Common representations of deflection plates are misleading. For one, the plates for one deflection axis are closer to the screen than the plates for the other. Plates that are closer together provide better sensitivity, but they also need to be extend far enough along the CRT's axis to obtain adequate sensitivity. (The longer the time a given electron spends in the field, the farther it's deflected.) However, closely spaced long plates would cause the beam to contact them before full amplitude deflection occurs, so the compromise shape has them relatively close together toward the cathode, and flared apart in a shallow vee toward the screen. They are not flat in any but quite-old CRTs!
The timebase is an electronic circuit that generates a ramp voltage. This is a voltage that changes continuously and linearly with time. When it reaches a predefined value the ramp is reset and settles to its starting value. When a trigger event is recognized, provided the reset process (holdoff) is complete, the ramp starts again. The timebase voltage usually drives the horizontal amplifier. Its effect is to sweep the screen end of the electron beam at a constant speed from left to right across the screen, then blank the beam and return its deflection voltages to the left, so to speak, in time to begin the next sweep. Typical sweep circuits can take significant time to reset; in some CROs, fast sweeps required more time to retrace than to sweep.
Meanwhile, the vertical amplifier is driven by an external voltage (the vertical input) that is taken from the circuit or experiment that is being measured. The amplifier has a very high input impedance, typically one megohm, so that it draws only a tiny current from the signal source. Attenuator probes reduce the current drawn even more. The amplifier drives the vertical deflection plates with a voltage that is proportional to the vertical input. Because the electrons have already been accelerated by typically 2kV (roughly), this amplifier also has to deliver almost a hundred volts, and this with a very wide bandwidth. The gain of the vertical amplifier can be adjusted to suit the amplitude of the input voltage. A positive input voltage bends the electron beam upwards, and a negative voltage bends it downwards, so that the vertical deflection at any part of the trace shows the value of the input at that time.[6]
The response of any oscilloscope is much faster than that of mechanical measuring devices such as the multimeter, where the inertia of the pointer (and perhaps damping) slows down its response to the input.
Observing high speed signals, especially non-repetitive signals, with a conventional CRO is difficult, due to non-stable or changing triggering threshold which makes it hard to "freeze" the waveform on the screen. This often requires the room to be darkened or a special viewing hood to be placed over the face of the display tube. To aid in viewing such signals, special oscilloscopes have borrowed from night vision technology, employing a microchannel plate electron multiplier behind the tube face to amplify faint beam currents.
Although a CRO allows one to view a signal, in its basic form it has no means of recording that signal on paper for the purpose of documentation. Therefore, special oscilloscope cameras were developed to photograph the screen directly. Early cameras used roll or plate film, while in the 1970s Polaroid instant cameras became popular. A P11 CRT phosphor (visually blue) was especially effective in exposing film. Cameras (sometimes using single sweeps) were used to capture faint traces.
The power supply is an important component of the oscilloscope. It provides low voltages to power the cathode heater in the tube (isolated for high voltage!), and the vertical and horizontal amplifiers as well as the trigger and sweep circuits. Higher voltages are needed to drive the electrostatic deflection plates, which means that the output stage of the vertical deflection amplifier has to develop large signal swings. These voltages must be very stable, and amplifier gain must be correspondingly stable. Any significant variations will cause errors in the size of the trace, making the oscilloscope inaccurate.
Later analog oscilloscopes added digital processing to the standard design. The same basic architecture — cathode ray tube, vertical and horizontal amplifiers — was retained, but the electron beam was controlled by digital circuitry that could display graphics and text mixed with the analog waveforms. Display time for those was interleaved — multiplexed — with waveform display in basically much the same way that a dual/multitrace oscilloscope displays its channels. The extra features that this system provides include:
- on-screen display of amplifier and timebase settings;
- voltage cursors — adjustable horizontal lines with voltage display;
- time cursors — adjustable vertical lines with time display;
- on-screen menus for trigger settings and other functions.
- automatic measurement of voltage and frequency of a displayed trace
Dual-beam oscilloscope[edit]
A dual-beam oscilloscope was a type of oscilloscope once used to compare one signal with another. There were two beams produced in a special type of CRT.
Unlike an ordinary "dual-trace" oscilloscope (which time-shared a single electron beam, thus losing about 50% of each signal), a dual-beam oscilloscope simultaneously produced two separate electron beams, capturing the entirety of both signals. One type (Cossor, UK) had a beam-splitter plate in its CRT, and single-ended vertical deflection following the splitter. (There is more about this type of oscilloscope near the end of this article.)
Other dual-beam oscilloscopes had two complete electron guns, requiring tight control of axial (rotational) mechanical alignment in manufacturing the CRT. In the latter type, two independent pairs of vertical plates deflect the beams. Vertical plates for channel A had no effect on channel B's beam. Similarly for channel B, separate vertical plates existed which deflected the B beam only.
On some dual-beam oscilloscopes the time base, horizontal plates and horizontal amplifier were common to both beams (the beam-splitter CRT worked this way). More elaborate oscilloscopes like the Tektronix 556 and 7844 could employ two independent time bases and two sets of horizontal plates and horizontal amplifiers. Thus one could look at a very fast signal on one beam and a slow signal on another beam.
Most multichannel oscilloscopes do not have multiple electron beams. Instead, they display only one trace at a time, but switch the later stages of the vertical amplifier between one channel and the other either on alternate sweeps (ALT mode) or many times per sweep (CHOP mode). Very few true dual-beam oscilloscopes were built.
With the advent of digital signal capture, true dual-beam oscilloscopes became obsolete, as it was then possible to display two truly simultaneous signals from memory using either the ALT or CHOP display technique, or even possibly a raster display mode.
Analog storage oscilloscope[edit]
Trace storage is an extra feature available on some analog oscilloscopes; they used direct-view storage CRTs. Storage allows the trace pattern that normally decays in a fraction of a second to remain on the screen for several minutes or longer. An electrical circuit can then be deliberately activated to store and erase the trace on the screen.
The storage is accomplished using the principle of secondary emission. When the ordinary writing electron beam passes a point on the phosphor surface, not only does it momentarily cause the phosphor to illuminate, but the kinetic energy of the electron beam knocks other electrons loose from the phosphor surface. This can leave a net positive charge. Storage oscilloscopes then provide one or more secondary electron guns (called the "flood guns") that provide a steady flood of low-energy electrons traveling towards the phosphor screen. Flood guns cover the entire screen, ideally uniformly. The electrons from the flood guns are more strongly drawn to the areas of the phosphor screen where the writing gun has left a net positive charge; in this way, the electrons from the flood guns re-illuminate the phosphor in these positively charged areas of the phosphor screen.[7]
If the energy of the flood gun electrons is properly balanced, each impinging flood gun electron knocks out one secondary electron from the phosphor screen, thus preserving the net positive charge in the illuminated areas of the phosphor screen. In this way, the image originally written by the writing gun can be maintained for a long time — many seconds to a few minutes. Eventually, small imbalances in the secondary emission ratio cause the entire screen to "fade positive" (light up) or cause the originally written trace to "fade negative" (extinguish). It is these imbalances that limit the ultimate storage time possible. [7]
Storage oscilloscopes (and large-screen storage CRT displays) of this type, with storage at the phosphor, were made by Tektronix. Other companies, notably Hughes, earlier made storage oscilloscopes with a more-elaborate and costly internal storage structure.
Some oscilloscopes used a strictly binary (on/off) form of storage known as "bistable storage". Others permitted a constant series of short, incomplete erasure cycles which created the impression of a phosphor with "variable persistence". Certain oscilloscopes also allowed the partial or complete shutdown of the flood guns, allowing the preservation (albeit invisibly) of the latent stored image for later viewing. (Fading positive or fading negative only occurs when the flood guns are "on"; with the flood guns off, only leakage of the charges on the phosphor screen degrades the stored image.
Analog sampling oscilloscope[edit]
The principle of sampling was developed during the 1930s in Bell Laboratories by Nyquist, after whom the sampling theorem is named. The first sampling oscilloscope was, however, developed in the late 1950s at the Atomic Energy Research Establishment at Harwell in England by G.B.B. Chaplin, A.R. Owens and A.J. Cole. ["A Sensitive Transistor Oscillograph With DC to 300 Mc/s Response", Proc I.E.E. (London) Vol.106, Part B. Suppl., No. 16, 1959].
The first sampling oscilloscope was an analog instrument, originally developed as a front-end unit for a conventional oscilloscope. The need for this instrument grew out of the requirement of nuclear scientists at Harwell to capture the waveform of very fast repetitive pulses. The current state-of-the-art oscilloscopes — with bandwidths of typically 20 MHz — were not able to do this and the 300 MHz effective bandwidth of their analog sampling oscilloscope represented a considerable advance.
A short series of these "front-ends" was made at Harwell and found much use, and Chaplin et al. patented the invention. Commercial exploitation of this patent was ultimately done by the Hewlett-Packard Company (later Agilent Technologies).
Sampling oscilloscopes achieve their large bandwidths by not taking the entire signal at a time. Instead, only a sample of the signal is taken. The samples are then assembled to create the waveform. This method can only work for repetitive signals, not transient events. The idea of sampling can be thought of as a stroboscopic technique. When using a strobe light, only pieces of the motion are seen, but when enough of these images are taken, the overall motion can be captured[8]
Related instruments[edit]
A large number of instruments used in a variety of technical fields are really oscilloscopes with inputs, calibration, controls, display calibration, etc., specialized and optimized for a particular application. In some cases additional functions such as a signal generator are built into the instrument to facilitate measurements that would otherwise require one or more additional instruments.
The waveform monitor in television broadcast engineering is very close to a standard oscilloscope, but it includes triggering circuits and controls that allow a stable display of a composite video frame, field, or even a selected line out of a field. Robert Hartwig explains the waveform monitor as "providing a graphic display of the black-and-white portion of the picture."[9] The black-and-white portion of the video signal is called the "luminance" due to its fluorescent complexion. The waveform monitor's display of black vs. white levels allows the engineer to troubleshoot the quality of the picture and be certain that it is within the required standards. For convenience, the vertical scale of the waveform monitor is calibrated in IRE units.
https://en.wikipedia.org/wiki/Oscilloscope_types#Cathode-ray_oscilloscope
The history of the oscilloscope reaches back to the first recordings of waveforms with a galvanometer coupled to a mechanical drawing system in the second decade of the 19th century. The modern day digital oscilloscope is a consequence of multiple generations of development of the oscillograph, cathode-ray tubes, analog oscilloscopes, and digital electronics.
https://en.wikipedia.org/wiki/History_of_the_oscilloscope
https://en.wikipedia.org/wiki/Galvanometer
https://en.wikipedia.org/wiki/Gyroscope
https://en.wikipedia.org/wiki/Fibre-optic_gyroscope
https://en.wikipedia.org/wiki/Ring_laser_gyroscope
https://en.wikipedia.org/wiki/Gyrotheodolite
https://en.wikipedia.org/wiki/Degrees_of_freedom_(mechanics)
https://en.wikipedia.org/wiki/Euler_angles
https://en.wikipedia.org/wiki/Dihedral_angle
https://en.wikipedia.org/wiki/Maglev
https://en.wikipedia.org/wiki/Linear_induction_motor
https://en.wikipedia.org/wiki/Linear_motor
https://en.wikipedia.org/wiki/Magnetic_induction
https://en.wikipedia.org/wiki/differential
https://en.wikipedia.org/wiki/integral
https://en.wikipedia.org/wiki/calculus
https://en.wikipedia.org/wiki/coupling
https://en.wikipedia.org/wiki/electrostatics
https://en.wikipedia.org/wiki/rotation
https://en.wikipedia.org/wiki/nuclear_transmutation
https://en.wikipedia.org/wiki/Transform
https://en.wikipedia.org/wiki/angular_acceleration
https://en.wikipedia.org/wiki/Energy
https://en.wikipedia.org/wiki/Magnetic_levitation
https://en.wikipedia.org/wiki/launch_loop
https://en.wikipedia.org/wiki/linear_stage
https://en.wikipedia.org/wiki/Linear-motion_bearing
https://en.wikipedia.org/wiki/eigenvalue
https://en.wikipedia.org/wiki/eigenenergy
https://en.wikipedia.org/wiki/eigenstate
https://en.wikipedia.org/wiki/state
https://en.wikipedia.org/wiki/phase_change
https://en.wikipedia.org/wiki/fusion
https://en.wikipedia.org/wiki/Linear-motion_bearing
https://en.wikipedia.org/wiki/Rolling-element_bearing#Roller_bearings
https://en.wikipedia.org/wiki/Rolling
https://en.wikipedia.org/wiki/flywheel
https://en.wikipedia.org/wiki/pressure
https://en.wikipedia.org/wiki/pressure_gradient
https://en.wikipedia.org/wiki/pressure_differential
https://en.wikipedia.org/wiki/Thrust_bearing
https://en.wikipedia.org/wiki/Rotation_around_a_fixed_axis
https://en.wikipedia.org/wiki/axial_load
https://en.wikipedia.org/wiki/axial_plane
https://en.wikipedia.org/wiki/suspension
https://en.wikipedia.org/wiki/Torque
https://en.wikipedia.org/wiki/Tensor
https://en.wikipedia.org/wiki/Torsion
https://en.wikipedia.org/wiki/Pendulum
https://en.wikipedia.org/wiki/beam
https://en.wikipedia.org/wiki/spring
https://en.wikipedia.org/wiki/string
https://en.wikipedia.org/wiki/oscillation
https://en.wikipedia.org/wiki/period
https://en.wikipedia.org/wiki/cycle
https://en.wikipedia.org/wiki/circular_motion
https://en.wikipedia.org/wiki/level
Level dimensionalization etc.
https://en.wikipedia.org/wiki/stepwise
https://en.wikipedia.org/wiki/spontaneous_symmetry_breaking
https://en.wikipedia.org/wiki/Transform
https://en.wikipedia.org/wiki/space_division_multiplexing
https://en.wikipedia.org/wiki/quadpole
https://en.wikipedia.org/wiki/quantum_interface
https://en.wikipedia.org/wiki/quantum_ion_computing
https://en.wikipedia.org/wiki/Trapped_ion_quantum_computer
https://en.wikipedia.org/wiki/Torque
Fluid bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces.[1] Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly.[1]
They can be broadly classified into two types: fluid dynamic bearings (also known as hydrodynamic bearings) and hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and the pressurization is done by a pump. Hydrodynamic bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces. Fluid bearings are frequently used in high load, high speed or high precision applications where ordinary ball bearings would have short life or cause high noise and vibration. They are also used increasingly to reduce cost. For example, hard disk drive motor fluid bearings are both quieter and cheaper than the ball bearings they replace. Applications are very versatile and may even be used in complex geometries such as leadscrews.[2]
The fluid bearing may have been invented by French civil engineer L. D. Girard, who in 1852 proposed a system of railway propulsion incorporating water-fed hydraulic bearings.[3][1]
https://en.wikipedia.org/wiki/Fluid_bearing
https://en.wikipedia.org/wiki/Vacuum
https://en.wikipedia.org/wiki/Rigid_body_dynamics#Rigid-body_angular_momentum
https://en.wikipedia.org/wiki/Fluid_dynamics
https://en.wikipedia.org/wiki/Continuum_mechanics
https://en.wikipedia.org/wiki/Augustin-Louis_Cauchy
https://en.wikipedia.org/wiki/Limit_of_a_sequence
https://en.wikipedia.org/wiki/Metric_space
https://en.wikipedia.org/wiki/Topological_property
https://en.wikipedia.org/wiki/Homeomorphism
https://en.wikipedia.org/wiki/Trefoil_knot
https://en.wikipedia.org/wiki/Spinor
https://en.wikipedia.org/wiki/Linear_map
https://en.wikipedia.org/wiki/Scalar_multiplication
https://en.wikipedia.org/wiki/Zero_element#Additive_identities
https://en.wikipedia.org/wiki/Intermolecular_force
https://en.wikipedia.org/w/index.php?search=zero+dipole&title=Special:Search&go=Go&ns0=1&searchToken=5j8jikd7i1v1pbqlwvqrzhjhc
https://en.wikipedia.org/wiki/Debye
https://en.wikipedia.org/wiki/Zero-point_energy
https://en.wikipedia.org/wiki/Force_between_magnets
https://en.wikipedia.org/wiki/Quadrupole
https://en.wikipedia.org/wiki/multipole_expansion
https://en.wikipedia.org/wiki/Overtone_band
https://en.wikipedia.org/wiki/Observable_universe
https://en.wikipedia.org/wiki/Dark_matter
https://en.wikipedia.org/wiki/Overtone_band
https://en.wikipedia.org/wiki/Ground_state
https://en.wikipedia.org/wiki/Cosmic_microwave_background
https://en.wikipedia.org/wiki/Inflation_(cosmology)
https://en.wikipedia.org/wiki/Gravitational_wave_background
https://en.wikipedia.org/wiki/Cosmic_microwave_background
https://en.wikipedia.org/wiki/Cosmic_neutrino_background
https://en.wikipedia.org/wiki/Neutrino
https://en.wikipedia.org/wiki/Neutronium
https://en.wikipedia.org/wiki/Neutron
https://en.wikipedia.org/wiki/Subatomic_particle
https://en.wikipedia.org/wiki/Nucleon
https://en.wikipedia.org/wiki/Overtone_band
https://en.wikipedia.org/wiki/Cabibbo–Kobayashi–Maskawa_matrix
https://en.wikipedia.org/wiki/Electroweak_interaction
https://en.wikipedia.org/wiki/Quantum_chromodynamics
https://en.wikipedia.org/wiki/Lambda-CDM_model
https://en.wikipedia.org/wiki/Nuclear_binding_energy
https://en.wikipedia.org/wiki/Helium-4
https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis
Baryon–photon ratio[edit]
The baryon–photon ratio, η, is the key parameter determining the abundances of light elements after nucleosynthesis ends. Baryons and light elements can fuse in the following main reactions:
along with some other low-probability reactions leading to 7Li or 7Be. (An important feature is that there are no stable nuclei with mass 5 or 8, which implies that reactions adding one baryon to 4He, or fusing two 4He, do not occur). Most fusion chains during BBN ultimately terminate in 4He (helium-4), while "incomplete" reaction chains lead to small amounts of left-over 2H or 3He; the amount of these decreases with increasing baryon-photon ratio. That is, the larger the baryon-photon ratio the more reactions there will be and the more efficiently deuterium will be eventually transformed into helium-4. This result makes deuterium a very useful tool in measuring the baryon-to-photon ratio.
Heavy elements[edit]
Big Bang nucleosynthesis produced very few nuclei of elements heavier than lithium due to a bottleneck: the absence of a stable nucleus with 8 or 5 nucleons. This deficit of larger atoms also limited the amounts of lithium-7 produced during BBN. In stars, the bottleneck is passed by triple collisions of helium-4 nuclei, producing carbon (the triple-alpha process). However, this process is very slow and requires much higher densities, taking tens of thousands of years to convert a significant amount of helium to carbon in stars, and therefore it made a negligible contribution in the minutes following the Big Bang.
The predicted abundance of CNO isotopes produced in Big Bang nucleosynthesis is expected to be on the order of 10−15that of H, making them essentially undetectable and negligible.[10] Indeed, none of these primordial isotopes of the elements from beryllium to oxygen have yet been detected, although those of beryllium and boron may be able to be detected in the future. So far, the only stable nuclides known experimentally to have been made before or during Big Bang nucleosynthesis are protium, deuterium, helium-3, helium-4, and lithium-7.[11]
Neutron–proton ratio[edit]
The neutron–proton ratio was set by Standard Model physics before the nucleosynthesis era, essentially within the first 1-second after the Big Bang. Neutrons can react with positrons or electron neutrinos to create protons and other products in one of the following reactions:
At times much earlier than 1 sec, these reactions were fast and maintained the n/p ratio close to 1:1. As the temperature dropped, the equilibrium shifted in favour of protons due to their slightly lower mass, and the n/p ratio smoothly decreased. These reactions continued until the decreasing temperature and density caused the reactions to become too slow, which occurred at about T = 0.7 MeV (time around 1 second) and is called the freeze out temperature. At freeze out, the neutron–proton ratio was about 1/6. However, free neutrons are unstable with a mean life of 880 sec; some neutrons decayed in the next few minutes before fusing into any nucleus, so the ratio of total neutrons to protons after nucleosynthesis ends is about 1/7. Almost all neutrons that fused instead of decaying ended up combined into helium-4, due to the fact that helium-4 has the highest binding energy per nucleon among light elements. This predicts that about 8% of all atoms should be helium-4, leading to a mass fraction of helium-4 of about 25%, which is in line with observations. Small traces of deuterium and helium-3 remained as there was insufficient time and density for them to react and form helium-4.[6]
https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis
https://en.wikipedia.org/wiki/Deuterium
https://en.wikipedia.org/wiki/Proton–proton_chain
https://en.wikipedia.org/wiki/Cosmological_lithium_problem
https://en.wikipedia.org/wiki/Functional_analog_(chemistry)
https://en.wikipedia.org/wiki/Structural_analog
https://en.wikipedia.org/wiki/Substrate_analog
https://en.wikipedia.org/wiki/Isoelectronicity
https://en.wikipedia.org/wiki/Hydrogen-like_atom
https://en.wikipedia.org/wiki/Rydberg_atom
https://en.wikipedia.org/wiki/Azimuthal_quantum_number
https://en.wikipedia.org/wiki/Binding_energy
https://en.wikipedia.org/wiki/Separation_energy
https://en.wikipedia.org/wiki/Photoionization
https://en.wikipedia.org/wiki/Photodissociation
https://en.wikipedia.org/wiki/Photoelectric_effect
https://en.wikipedia.org/wiki/Photovoltaics
https://en.wikipedia.org/wiki/Bond-dissociation_energy
https://en.wikipedia.org/wiki/Nuclear_physics
https://en.wikipedia.org/wiki/Powder_coating
https://en.wikipedia.org/wiki/Melt_electrospinning
https://en.wikipedia.org/wiki/Electrospinning
https://en.wikipedia.org/wiki/Electret
https://en.wikipedia.org/wiki/Overvoltage
https://en.wikipedia.org/wiki/Gaseous_fission_reactor
https://en.wikipedia.org/wiki/Electron-beam_technology
A gas nuclear reactor (or gas fueled reactor or vapor core reactor) is a proposed kind of nuclear reactor in which the nuclear fuel would be in a gaseous state rather than liquid or solid. In this type of reactor, the only temperature-limiting materials would be the reactor walls. Conventional reactors have stricter limitations because the core would melt if the fuel temperature were to rise too high. It may also be possible to confine gaseous fission fuel magnetically, electrostatically or electrodynamically so that it would not touch (and melt) the reactor walls. A potential benefit of the gaseous reactor core concept is that instead of relying on the traditional Rankine or Brayton conversion cycles, it may be possible to extract electricity magnetohydrodynamically, or with simple direct electrostatic conversion of the charged particles.
https://en.wikipedia.org/wiki/Gaseous_fission_reactor
https://en.wikipedia.org/wiki/Ionic_compound
https://en.wikipedia.org/wiki/Laser_printing
https://en.wikipedia.org/wiki/3D_printing
https://en.wikipedia.org/wiki/Joule_heating
https://en.wikipedia.org/wiki/Aramid
https://en.wikipedia.org/wiki/International_System_of_Units
https://en.wikipedia.org/wiki/Nikola_Tesla
https://en.wikipedia.org/wiki/Failure_of_electronic_components#Electrostatic_discharge
https://en.wikipedia.org/wiki/Volcanic_lightning
https://en.wikipedia.org/wiki/Coating
https://en.wikipedia.org/wiki/Plastic_recycling#Electrostatic_separation
https://en.wikipedia.org/wiki/Aluminium
https://en.wikipedia.org/wiki/Electrolysis
https://en.wikipedia.org/wiki/Water
https://en.wikipedia.org/wiki/Silicon
https://en.wikipedia.org/wiki/Fusion_bonded_epoxy_coating
https://en.wikipedia.org/wiki/Welding
https://en.wikipedia.org/wiki/Iodine
https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#Electrostatic-boosted_radioisotope_heat_sources
https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
https://en.wikipedia.org/wiki/Lightning
https://en.wikipedia.org/wiki/Sodium_chloride
https://en.wikipedia.org/wiki/Electric_arc
https://en.wikipedia.org/wiki/Lunar_soil#Moon_dust_fountains_and_electrostatic_levitation
https://en.wikipedia.org/wiki/Capacitor
https://en.wikipedia.org/wiki/Flash_powder
https://en.wikipedia.org/wiki/Ceramic
https://en.wikipedia.org/wiki/Arc_suppression
https://en.wikipedia.org/wiki/Snowball
https://en.wikipedia.org/wiki/Cathode-ray_tube
https://en.wikipedia.org/wiki/Cathode-ray_tube#Electrostatic_deflection
https://en.wikipedia.org/wiki/Electrostatic_deflection
https://en.wikipedia.org/wiki/Flow_cytometry#Fluorescence-activated_cell_sorting
Electrostatic deflection refers to a way for modifying the path of a beam of charged particles by the use of an electric fieldapplied transverse to the path of the particles. The technique is called electrostatic because the strength and direction of the applied field changes slowly relative to the time it takes for the particles to transit the field, and thus can be considered not to change (be static) for any particular particle.
https://en.wikipedia.org/wiki/Electrostatic_deflection
Monday, September 20, 2021
09-20-2021-1030 - Plasmon (drafting Hydroelectric power and hydroelectric gas search)
In physics, a plasmon is a quantum of plasma oscillation. Just as light (an optical oscillation) consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quantization of plasma oscillations, just like phonons are quantizations of mechanical vibrations. Thus, plasmons are collective (a discrete number) oscillations of the free electron gas density. For example, at optical frequencies, plasmons can couple with a photon to create another quasiparticle called a plasmon polariton.
https://en.wikipedia.org/wiki/Plasmon
https://en.wikipedia.org/wiki/Linus_Pauling
https://en.wikipedia.org/wiki/Wolfgang_Pauli
Spiral groove bearings (also known as Rifle bearings) are self-acting (journal and thrust), or hydrodynamic bearings used to reduce friction and wear without the use of pressurized lubricants. They have this ability due to special patterns of grooves. Spiral groove bearings are self-acting because their own rotation builds up the pressure needed to separate the bearing surfaces. For this reason, they are also contactless bearings.
https://en.wikipedia.org/wiki/Spiral_groove_bearing
https://en.wikipedia.org/wiki/Compressibilityhttps://en.wikipedia.org/wiki/rheology
https://en.wikipedia.org/wiki/viscosity
https://en.wikipedia.org/wiki/vertical
https://en.wikipedia.org/wiki/vertical_pressure
https://en.wikipedia.org/wiki/Pressure_gradient
https://en.wikipedia.org/wiki/Vertical_pressure_variation
https://en.wikipedia.org/wiki/Atmospheric_pressure
https://en.wikipedia.org/wiki/Thermal_wind
https://en.wikipedia.org/wiki/Elevation
https://en.wikipedia.org/wiki/Hydrostatics
https://en.wikipedia.org/wiki/Vapor_pressure
https://en.wikipedia.org/wiki/Lift_(force)
https://en.wikipedia.org/wiki/Hydrostatics#Hydrostatic_pressure
https://en.wikipedia.org/wiki/Hypsometric_equation
https://en.wikipedia.org/wiki/International_Standard_Atmosphere
https://en.wikipedia.org/wiki/Lateral_earth_pressure
https://en.wikipedia.org/wiki/Retaining_wall
https://en.wikipedia.org/wiki/Lift_(force)#Pressure_differences
https://en.wikipedia.org/wiki/Azeotrope#Pressure_swing_distillation
https://en.wikipedia.org/wiki/Rear_flank_downdraft
https://en.wikipedia.org/wiki/Overburden_pressure
https://en.wikipedia.org/wiki/Station_model#Sea_level_pressure_and_height_of_pressure_surface
https://en.wikipedia.org/wiki/Siphon
https://en.wikipedia.org/wiki/Altitude
https://en.wikipedia.org/wiki/Souders–Brown_equation
https://en.wikipedia.org/wiki/Well_cluster
https://en.wikipedia.org/wiki/Low-pressure_area
https://en.wikipedia.org/wiki/Navier–Stokes_equations#Pressure_recovery
https://en.wikipedia.org/wiki/Anemometer#Pressure_anemometers
https://en.wikipedia.org/wiki/Marine_steam_engine#Walking_beam
https://en.wikipedia.org/wiki/Partial_pressure
https://en.wikipedia.org/wiki/Vertical-axis_wind_turbine
https://en.wikipedia.org/wiki/Air_current#Vertical_currents
https://en.wikipedia.org/wiki/Jurin%27s_law#Laplace_pressure
https://en.wikipedia.org/wiki/Flight_level#Reduced_vertical_separation_minima_%28RVSM%29
https://en.wikipedia.org/wiki/Vapor-compression_refrigeration
https://en.wikipedia.org/wiki/Cascade_refrigeration
https://en.wikipedia.org/wiki/Heat_recovery_steam_generator
https://en.wikipedia.org/wiki/Geopotential_height
A linear-motion bearing or linear slide is a bearing designed to provide free motion in one direction.
https://en.wikipedia.org/wiki/Linear-motion_bearing
The Quadruplanar inversor of Sylvester and Kempe is a generalization of Hart's inversor. Like Hart's inversor, is a mechanism that provides a perfect straight line motion without sliding guides.
The mechanism was described in 1875 by James Joseph Sylvester in the journal Nature.[1]
Like Hart's inversor, it is based on an antiparallelogram (KBCD in the figures below) but the rather than placing the fixed, input and output points on the sides (dividing them in fixed proportion so they are all similar), Sylvester recognized that the additional points could be displaced sideways off the sides, as long as they formed similar triangles. Hart's original form is simply the degenerate case of triangles with altitude zero.
https://en.wikipedia.org/wiki/Quadruplanar_inversorA Roberts mechanism is a mechanical linkage which converts a rotational motion to approximate straight-line motion.[1]
The linkage was developed by Richard Roberts (1789–1864).[1]
The Roberts mechanism can be classified as:
- Watt-type linkage[1]
- Grashof rocker-rocker[2]
- symmetrical four-bar linkage[3]
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