Physical world and mathematics

Disease progression modeling

Disease progression modeling is a biostatistical method using mathematical models to describe a disease's trajectory over time and separate natural progression from drug effects in drug development.

Diselenide chemistry concerns organic compounds containing a selenium–selenium single bond, R–Se–Se–R, and the exchange reaction diselenide metathesis, which enables self-healing polyurethane thermosets and visible-light-programmable liquid crystal elastomers.

Disgregation

Disgregation is a thermodynamic quantity introduced by Rudolf Clausius in 1862 as a measure of the separation of the parts of a body, and a component of the entropy he defined in 1865.

Dishwashing liquid

Dishwashing liquid, also called washing-up liquid or dish soap, is a detergent for hand dishwashing whose surfactants lift grease and food residue from dishes, glassware, and cookware.

Disiloxane

Disiloxane, also called disilyl ether, is the simplest siloxane, a volatile compound of two silyl groups joined by one oxygen atom and the parent of the siloxane series.

Disjoining pressure

Disjoining pressure is the pressure difference across a thin liquid film confined between two surfaces, arising from intermolecular forces, introduced by Derjaguin and Obuchov in 1936.

Disjoint sets

Disjoint sets, also called mutually exclusive sets, are sets that share no elements, so their intersection is empty; the concept underlies partitions and counting rules.

Disk laser

A disk laser, typically thin-disk, is a diode-pumped solid-state laser using a thin crystal on a heat sink, enabling high power, efficiency, and beam quality.

Dislocation

A dislocation, also called a crystal dislocation, is a line defect in a crystal lattice whose motion lets crystals deform permanently at stresses far below theoretical strength.

Disodium helide

Disodium helide (Na₂He) is a stable compound of helium and sodium, first synthesized in 2017, that exists only under extreme pressure, above 113 GPa, and was the first stable helium compound known.

Disodium phosphate

Disodium phosphate (Na₂HPO₄), also called disodium hydrogen phosphate or sodium phosphate dibasic, is a white, weakly alkaline salt of phosphoric acid used as a buffer, food emulsifier, and corrosion inhibitor.

Disopyramide

Disopyramide, sold as Norpace, is a class 1A antiarrhythmic drug that blocks cardiac sodium channels, approved in 1978 for ventricular arrhythmias and used off-label for obstructive hypertrophic cardiomyopathy.

Disorder-free localization

Disorder-free localization (DFL) is a 2017-proposed ergodicity-breaking mechanism in which a quantum many-body system with a clean, translationally invariant Hamiltonian fails to thermalize due to dynamically generated disorder.

Disperse Red 1

Disperse Red 1 is a synthetic azo dye used as a red colorant, mainly for polyester textiles, and a recognized skin sensitizer also studied in nonlinear optical polymers.

Dispersion (optics)

Dispersion, or chromatic dispersion, is the dependence of a medium's refractive index on light's wavelength, separating white light in prisms and rainbows and causing chromatic aberration.

Dispersion (water waves)

Dispersion in water waves is the dependence of wave speed on wavelength, so in deep water longer waves outrun shorter ones and a mixed group spreads out.

Dispersion polymerization

Dispersion polymerization is a form of precipitation polymerization in which a homogeneous solution of monomer, initiator, and stabilizer yields sterically stabilized, monodisperse spherical polymer particles, typically in polar organic media.

Dispersion relation

A dispersion relation, also called a dispersion equation, is the function relating a wave's angular frequency to its wavenumber; it determines phase velocity, group velocity, and how wave packets disperse.

Dispersion relations

Dispersion relations are linear integral equations relating the real and imaginary parts of scattering amplitudes, first derived by Kramers and Kronig in optics in 1926 and 1927 and rooted in causality.

Dispersion strengthening

Dispersion strengthening is a metallurgical hardening method in which fine, thermally stable second-phase particles block dislocation motion, best known in ODS alloys used up to about 1,200 °C.

Dispersion-compensating fiber

Dispersion-compensating fiber (DCF) is optical fiber engineered with large negative chromatic dispersion, deployed as spooled modules at amplifier sites to undo pulse spreading in long-haul systems.

Dispersive liquid–liquid microextraction

Dispersive liquid–liquid microextraction (DLLME) is a sample preparation method in analytical chemistry, introduced in 2006, that concentrates dissolved analytes into a tiny sedimented solvent drop before analysis.

Dispersive prism

A dispersive prism is a triangular block of glass or other transparent material that spreads white light into a spectrum because its refractive index varies with wavelength.

Dispersive readout

Dispersive readout is a technique for measuring quantum bits, in which a qubit coupled off-resonantly to a microwave resonator shifts the resonator's frequency depending on its state.

Dispersive solid phase extraction

Dispersive solid phase extraction (d-SPE) is a sample preparation method in which sorbent particles are dispersed directly into a liquid sample to remove interferences or preconcentrate analytes, serving as the cleanup step of the QuEChERS workflow.

Displacement (geometry)

Displacement, also called a displacement vector, is the change in position of a point, a vector with both magnitude and direction; in geometry it defines a translation.

Displacement (ship)

Displacement, also called ship displacement or displacement tonnage, is the actual mass of a ship and everything aboard, equal by Archimedes' principle to the water displaced.

Displacement chromatography

Displacement chromatography is a chromatography mode, discovered by Arne Tiselius in 1943, in which a strongly binding displacer pushes sample components into consecutive rectangular bands rather than peaks.

Displacement current

The displacement current, also called Maxwell's displacement current, is a term James Clerk Maxwell added to Ampère's law so a changing electric field produces a magnetic field.