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Deposition (phase transition)
Deposition, also called desublimation, is the exothermic phase transition in which a gas turns directly into a solid without passing through the liquid state, forming hoar frost.
Depositional sequence
A depositional sequence is a relatively conformable succession of genetically related strata bounded by unconformities, recording one cycle of relative sea-level change and serving as the fundamental unit of sequence stratigraphy.
Deprotection of silyl ethers
Deprotection of silyl ethers is the removal of a silyl protecting group to regenerate a masked alcohol, most commonly using fluoride ion such as TBAF.
DEPT (NMR)
DEPT (Distortionless Enhancement by Polarization Transfer) is a carbon-13 NMR experiment, introduced in 1982, that determines how many hydrogens attach to each carbon while suppressing quaternary carbons.
Depth (ring theory)
Depth, also called the depth of a module or of a local ring, is an invariant of commutative algebra measuring the length of a maximal regular sequence on a module.
Depth hoar
Depth hoar, also called sugar snow, is a layer of weak, cup-shaped ice crystals that forms at the base of the snowpack and drives persistent slab avalanches.
Depth interview
A depth interview, also called an in-depth interview or IDI, is a one-on-one qualitative research conversation using open-ended questioning and probing to explore a participant's experiences, motivations, and beliefs.
Depth profiling
Depth profiling is an analytical technique that measures how a material's elemental composition changes with depth, sputtering away surface layers to yield concentration-versus-depth curves for thin films and buried interfaces.
Depth sounding
Depth sounding is the measurement of water depth, historically by weighted lead line and today mostly by timing sound or laser pulses from the seafloor.
Depth-graded multilayer coating
A depth-graded multilayer coating is a thin-film optical structure in which alternating layer thicknesses vary through the stack, letting one coating reflect a broad band of X-rays at a single incidence angle.
Dequantization (quantum computing)
Dequantization is a quantum machine learning research technique in which classical randomized algorithms reproduce quantum algorithms under analogous data-access assumptions, often erasing claimed exponential speedups; it was introduced by Ewin Tang.
Deracemization
Deracemization converts a racemic mixture into one enriched in a single enantiomer without physical separation, achieving 100% theoretical yield and serving as a major route to optically pure pharmaceuticals.
Derangement
A derangement is a permutation of a set that leaves no element in its original position; Montmort posed counting them in 1708, and about 1/e of permutations are derangements.
Derecho
A derecho is a widespread, long-lived windstorm produced by a band of rapidly moving thunderstorms, causing straight-line wind damage along paths hundreds of miles long.
Derek A. Pratt
Derek A. Pratt is a Canadian organic and chemical biology chemist, a professor at the University of Ottawa since 2010, known for research on lipid autoxidation and ferroptosis inhibitors.
Derek Barton
Derek Barton, also known as Derek H. R. Barton, was a British organic chemist who founded conformational analysis and shared the 1969 Nobel Prize in Chemistry.
Derek C. G. Muir
Derek C. G. Muir is a Canadian environmental chemist who studies persistent organic pollutants, PFAS, and mercury in Arctic environments, and was appointed an Officer of the Order of Canada in 2024.
Derek J. de Solla Price
Derek J. de Solla Price, also known as Derek John de Solla Price, was a British historian of science at Yale who founded the quantitative study of science.
Derek Muller
Derek Muller, full name Derek Alexander Muller, is an Australian-Canadian physicist and filmmaker who created Veritasium, a science YouTube channel with over 20 million subscribers.
Derek Vance
Derek Vance is an Irish isotope geochemist, Professor of Geochemistry at ETH Zurich since 2012 and a Fellow of the Royal Society elected in 2023.
Derivation (differential algebra)
In differential algebra, a derivation is a linear map on an algebra obeying the Leibniz product rule, the algebraic abstraction of differentiation begun by Joseph Fels Ritt in the 1930s.
Derivation of the Einstein field equations
The derivation of the Einstein field equations is how general relativity arrives at its central equation relating spacetime curvature to matter, by physical argument or by extremizing the Einstein-Hilbert action.
Derivation of the Navier–Stokes equations
The derivation of the Navier–Stokes equations is the chain of steps producing the governing equations of viscous flow, derived by Navier and Stokes in the early 1800s.
Derivation of the Schwarzschild solution
The derivation of the Schwarzschild solution is the calculation yielding the first exact solution of the Einstein field equations, found by Karl Schwarzschild in 1915.
Derivations of the Lorentz transformations
The derivations of the Lorentz transformations are the mathematical arguments yielding the equations relating space and time coordinates between inertial frames, from Einstein's 1905 postulates and later symmetry-only routes.
Derivative
The derivative of a function is the limit of its average rate of change over shrinking intervals, giving the instantaneous rate of change and tangent slope at a point.
Derivative spectrophotometry
Derivative spectrophotometry is an analytical technique that converts an absorption spectrum into its mathematical derivative to resolve overlapping peaks, suppress background absorption, and quantify analytes in mixtures.
Derivative-free optimization
Derivative-free optimization (DFO) is a class of numerical algorithms that minimize or maximize a function using only its values, when the function is a black-box simulation with no derivative information.
Derivatization
Derivatization is an analytical chemistry technique that chemically modifies a compound, improving its volatility, detectability, or stability for instrumental analysis, most often chromatography with mass spectrometry.
Derived algebraic geometry
Derived algebraic geometry, or DAG, is a branch of mathematics studying derived schemes and stacks, classical schemes enhanced with homotopical, higher categorical data, with foundations laid in the 2000s by Toën, Vezzosi, and Lurie.