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Disproportionality analysis
Disproportionality analysis is a family of statistical methods, including PRR, ROR, IC, and EBGM, used to detect higher-than-expected reporting of drug–adverse-event pairs in spontaneous-reporting databases.
Disproportionation
Disproportionation, also called dismutation, is a redox reaction in which a single substance is both oxidized and reduced, yielding products in higher and lower oxidation states.
Disruption (fusion)
A disruption in magnetic confinement fusion is the sudden loss of tokamak plasma confinement, releasing stored energy in milliseconds; research focuses on prediction, avoidance, and mitigation.
Dissimilatory nitrate reduction to ammonium
Dissimilatory nitrate reduction to ammonium (DNRA), also called nitrate ammonification, is an anaerobic microbial pathway that reduces nitrate via nitrite to ammonium, conserving fixed nitrogen in soils and sediments.
Dissipation
Dissipation is the irreversible conversion of organized mechanical or electrical energy into disordered thermal energy, destroying the capacity to do useful work; friction and Joule heating are examples.
Dissipative Kerr soliton
A dissipative Kerr soliton (DKS) is a short pulse of light that persists indefinitely in an optical resonator by balancing gain with loss and dispersion with nonlinearity.
Dissipative Kerr soliton microcomb
A dissipative Kerr soliton microcomb is an optical frequency comb generated by pumping a high-Q microresonator, producing a chip-scale, phase-coherent spectrum used in communications and clocks.
Dissipative molecular shuttling
Dissipative molecular shuttling is the fuel-driven back-and-forth movement of a ring-shaped molecule between binding stations on a threaded axle, sustained by continuously consuming chemical fuel.
Dissipative particle dynamics
Dissipative particle dynamics is a mesoscale simulation method, introduced by Hoogerbrugge and Koelman at Shell in 1992, that models fluids as coarse-grained beads conserving momentum and used for colloids, polymers, blood, and membranes.
Dissipative phase transition
A dissipative phase transition is a phase transition in the steady state of an open quantum system, arising when drive strength or dissipation crosses a critical value.
Dissipative self-assembly
Dissipative self-assembly is the formation of ordered supramolecular or colloidal structures held together by a continuous supply of energy, such as a chemical fuel or light, which disassemble when the fuel is depleted.
Dissipative soliton
A dissipative soliton is a localized pulse or beam of light that maintains its shape by balancing nonlinearity against dispersion or diffraction, and gain against loss.
Dissipative structure
A dissipative structure is an ordered pattern that forms and persists only in a system held far from thermodynamic equilibrium by a continuous energy flow.
Dissipative supramolecular polymers
Dissipative supramolecular polymers are polymer-like assemblies of small monomers held by reversible noncovalent interactions, maintained out of thermodynamic equilibrium by continuous fuel or light input and waste removal.
Dissociation (chemistry)
Dissociation in chemistry is the separation of a molecular entity into two or more entities, seen in ionic solids dissolving, acid-base equilibria measured by Ka, and covalent bond cleavage into radicals or ions.
Dissociation constant
The dissociation constant is an equilibrium constant for how readily a complex or acid separates into components; a smaller value means stronger association or weaker dissociation.
Dissociative electron attachment
Dissociative electron attachment is a collision process in which a low-energy electron briefly attaches to a molecule, breaking it into a negatively charged fragment and a neutral one.
Dissociative recombination
Dissociative recombination is a reaction in which a molecular ion captures a free electron and breaks into neutral fragments, the dominant neutralization route for molecular ions in ionized gases.
Dissolution dynamic nuclear polarization
Dissolution dynamic nuclear polarization (d-DNP) is a hyperpolarization technique invented in Sweden in 2003, in which polarized frozen samples are dissolved for NMR spectroscopy and MRI.
Dissolution testing
Dissolution testing is a laboratory procedure that measures the rate and extent to which a drug substance is released from a dosage form, such as a tablet or capsule, under controlled conditions.
Dissolution–precipitation
Dissolution–precipitation, also called coupled dissolution–reprecipitation (CDR), is a fluid-mediated solid-to-solid transformation in which a parent solid dissolves and a more stable phase precipitates at a shared reaction front, driving zeolite synthesis and CO2 mineral storage.
Dissolved inorganic carbon
Dissolved inorganic carbon (DIC) is the total inorganic carbon dissolved in seawater, mainly bicarbonate, carbonate, and carbon dioxide, and is the route by which human-made CO₂ enters the ocean.
Dissolved organic carbon
Dissolved organic carbon (DOC) is the organic carbon in water that passes a 0.45-micrometer filter, making up about 90% of total organic carbon in most waters.
Dissolved oxygen
Dissolved oxygen (DO) is the amount of oxygen gas dissolved in water and available to aquatic organisms, usually reported in mg/L, and a core measure of water quality.
Distance
Distance is the scalar length of the path actually traveled between two positions; unlike displacement, it has no direction and depends on the path taken.
Distance correlation
Distance correlation is a measure of statistical dependence between two random vectors, introduced by Székely, Rizzo, and Bakirov in 2007, that is zero if and only if they are independent.
Distance from a point to a line
The distance from a point to a line, also called the perpendicular distance, is the length of the shortest segment joining the point to the line, minimized by the perpendicular.
Distance geometry
Distance geometry is a mathematical method that determines possible three-dimensional structures of molecules from a set of distances between pairs of points, mainly from NMR data.
Distance matrix
A distance matrix is a square matrix recording the pairwise distances between elements of a finite set, with a symmetric, zero-diagonal form when the distance is a metric.
Distance modulus
The distance modulus is the difference between an astronomical object's apparent and absolute magnitude, μ = m − M, which provides a direct measure of its distance.