Physical world and mathematics

Imputation (statistics)

Imputation, also called data imputation, is the statistical process of replacing missing values in a dataset with substituted values so analyses can proceed on complete records.

IMRAD is a common structure for scientific journal articles, dividing them into Introduction, Methods, Results, and Discussion sections; leading medical journals fully adopted it between 1975 and 1985.

Imre Lakatos

Imre Lakatos, born Imre Lipschitz (1922–1974), was a Hungarian-born philosopher of mathematics and science at the London School of Economics, known for Proofs and Refutations and the Methodology of Scientific Research Programmes.

Sep 21, 2026

In Jae Chung

In Chung is a South Korean solid-state materials chemist and professor at Seoul National University, known for all-solid-state dye-sensitized solar cells using CsSnI3 and for thermoelectric materials research.

In silico

In silico (Latin for "in silicon") describes experiments performed by computer or computer simulation rather than in living organisms (in vivo) or the laboratory (in vitro), first used in 1989.

In situ crystallization

In situ crystallization is a laboratory technique in which crystals are grown and probed by diffraction or spectroscopy inside the reaction mixture, capturing transient phases invisible to ex situ methods.

In situ electron microscopy

In situ electron microscopy images materials in a gas or liquid, or while heat, electrical bias, or force is applied, instead of after the fact under vacuum.

In situ infrared spectroscopy

In situ infrared spectroscopy measures infrared absorption or reflection spectra of a material under reaction conditions, identifying adsorbed reactants and intermediates on working catalysts and electrodes; with simultaneous product analysis it is called operando spectroscopy.

In situ polymerization

In situ polymerization is a chemical synthesis method in which monomers polymerize directly inside a matrix, mold, or device, letting low-viscosity monomer wet fibers and pores before solidifying.

In situ Raman spectroscopy

In situ Raman spectroscopy measures Raman scattering from a material while it operates inside an electrochemical cell, tracking electrode transformations during battery cycling and reaction intermediates on working electrocatalysts.

In situ transmission electron microscopy

In situ transmission electron microscopy images a specimen inside a transmission electron microscope while heat, gas, liquid, or strain is applied, recording changes as they happen.

In situ U–Pb dating

In situ U–Pb dating is a microanalytical geochronology method that dates zircon and other minerals in place, by laser ablation or ion microprobe, preserving their petrographic setting.

In situ X-ray absorption spectroscopy

In situ X-ray absorption spectroscopy (XAS) measures a material's X-ray absorption spectrum while it operates under realistic reaction, temperature, pressure, or electrochemical conditions, tracking oxidation state and local atomic structure.

In situ X-ray computed tomography

In situ X-ray computed tomography reconstructs 3D images of a sample from X-ray radiographs while it is loaded, heated, or operated, tracking internal structural evolution over time.

In situ X-ray diffraction

In situ X-ray diffraction (XRD) records X-ray scattering patterns from a material while it is heated, charged, reacted, or compressed, tracking structural change in real time.

Sep 21, 2026

In Su Lee

In Su Lee (이인수) is a South Korean materials chemist at POSTECH since 2011, known for silica nanoreactors controlling nanocrystal formation and for tiling silica onto living cells.

In-cell NMR

In-cell NMR is a branch of biomolecular NMR spectroscopy that observes isotope-labeled proteins and nucleic acids at atomic resolution inside living cells, pioneered in 2001 and applied to drug discovery.

In-ear monitor

An in-ear monitor (IEM), also called in-ear headphones, is an earphone that inserts into the ear canal with an acoustic seal, used by performing musicians to hear a personal mix.

In-line holography

In-line holography is a holographic imaging technique in which the reference beam and object-scattered light share one optical axis, devised by Dennis Gabor in 1947.

In-phase and quadrature components

In-phase and quadrature components (I and Q) are the two parts of a bandpass signal that multiply cosine and sine carriers 90 degrees out of phase.

In-plane anisotropy of black phosphorus

In-plane anisotropy of black phosphorus is the direction-dependent behavior of its electronic, optical, thermal, and mechanical properties within its layers, arising from a puckered structure with armchair and zigzag axes.

In-situ tomography

In-situ tomography is a three-dimensional X-ray imaging method in which a sample is scanned repeatedly while a stimulus such as heat, load, or corrosion is applied, producing 4D data.

In2Se3

In2Se3 (indium(III) selenide) is a layered van der Waals semiconductor whose α phase keeps stable, electrically switchable ferroelectric polarization in films down to a single monolayer.

Inaccessible cardinal

An inaccessible cardinal is an uncountable cardinal that cannot be reached from smaller cardinals by successor, union, and power set operations, and whose existence ZFC cannot prove.

INADEQUATE

INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment) is a nuclear magnetic resonance experiment, introduced by Ad Bax, Ray Freeman, and S. P. Kempsell in 1980, that maps a molecule's carbon skeleton directly.

InAs colloidal quantum dots

InAs colloidal quantum dots (InAs CQDs) are solution-synthesized nanocrystals of the III–V semiconductor indium arsenide, spanning the near-infrared and short-wave infrared and pursued as a low-toxicity alternative to lead-based quantum dots.