Physical world and mathematics

Isophoronediamine

Isophoronediamine (IPDA) is the cycloaliphatic diamine 3-aminomethyl-3,5,5-trimethylcyclohexylamine, a colorless liquid used as an epoxy resin hardener and as the precursor to isophorone diisocyanate for polyurethanes.

Isophthalic acid

Isophthalic acid, also called benzene-1,3-dicarboxylic acid or m-phthalic acid, is an aromatic dicarboxylic acid with two carboxy groups on a benzene ring, produced by oxidizing m-xylene and used chiefly in polyester resins and alkyd coatings.

Isoprenaline

Isoprenaline (isoproterenol), a nonselective beta-1/beta-2 adrenergic agonist synthesized in 1948, used mainly in the electrophysiology lab and as a second-line drug for bradycardia and heart block; contraindicated in coronary ischemia.

Isoprene

Isoprene (2-methyl-1,3-butadiene) is a volatile five-carbon diene that is the monomer of natural rubber. Plants emit it in enormous quantities, and industry polymerizes it into synthetic rubber for tires.

Isopropanolamine

Isopropanolamine, also called monoisopropanolamine (MIPA) or 1-amino-2-propanol, is a corrosive, water-soluble amino alcohol made from propylene oxide and ammonia, used in surfactants, gas purification, and cement processing aids.

Isopropyl acetate

Isopropyl acetate is the ester of acetic acid and isopropanol, a colorless, fruity-smelling, highly flammable liquid used mainly as a fast-evaporating solvent in coatings and printing inks.

Isopropyl alcohol

Isopropyl alcohol, also known as isopropanol or propan-2-ol, is a colorless, flammable secondary alcohol best known as the active ingredient of rubbing alcohol and used as a solvent and disinfectant.

Isopropyl myristate

Isopropyl myristate is the ester of myristic acid and isopropanol, a colorless oily liquid used as an emollient in cosmetics and as a skin penetration enhancer in medicines.

Isopropylamine

Isopropylamine, also called propan-2-amine or MIPA, is a colorless, highly volatile aliphatic amine with an ammonia-like odor, best known as the intermediate for glyphosate herbicide.

Isopropylbenzylamine

Isopropylbenzylamine (N-isopropylbenzylamine) is a secondary amine carrying a benzyl group and an isopropyl group on nitrogen, used industrially and known since 2007–2008 as a methamphetamine adulterant.

Isoproturon

Isoproturon is a selective phenylurea herbicide used to control grasses and broad-leaved weeds in cereals, once a leading UK herbicide before the EU withdrew its approval in 2016.

Isoquinoline

Isoquinoline is an ortho-fused benzopyridine with the formula C₉H₇N, isomeric with quinoline; its ring is the core of alkaloids including morphine and berberine, and it is recovered from coal tar.

Isorhamnetin

Isorhamnetin, also known as 3-methylquercetin or quercetin 3'-methyl ether, is a naturally occurring O-methylated flavonol abundant in sea buckthorn and ginkgo, and a human metabolite of quercetin with reported anti-inflammatory and cardiovascular effects in preclinical studies.

Isoscape

An isoscape is a modeled or interpolated map of the spatial distribution of an element's isotopes in materials like water, soil, or animal tissue, coined in 2008.

Isosceles trapezoid

An isosceles trapezoid, also called an isosceles trapezium, is a trapezoid whose non-parallel sides are equal in length, giving it equal base angles, congruent diagonals, and one line of symmetry.

Isosceles triangle

An isosceles triangle is a triangle with two equal sides; its base angles are equal, the theorem proved as Euclid's Proposition I.5, known as the Pons Asinorum.

Isosorbide

Isosorbide (1,4:3,6-dianhydro-D-glucitol), formula C6H10O4, is a rigid non-toxic bicyclic diol made from sorbitol by acid-catalyzed dehydration and used as a precursor to angina drugs and bio-based polymers.

Isosorbide dinitrate

Isosorbide dinitrate (ISDN) is an organic nitrate vasodilator, synthesized in 1940, that prevents angina pectoris and, with hydralazine, treats heart failure; like nitroglycerin, it has a slower onset.

Isospin

Isospin, or isotopic spin, is a quantum number in particle physics treating the proton and neutron as two states of one particle under the strong interaction.

Oct 22, 2026

Isospin magnetism

Isospin magnetism is the spontaneous magnetic ordering of the spin and valley degrees of freedom of carriers in multilayer graphene, producing ferromagnetism, correlated insulators, and spin-polarized superconductivity.

Isostasy

Isostasy is the gravitational balance of large crustal blocks as though floating on the denser asthenosphere; mountain ranges are supported by deep roots, a principle named by Clarence Dutton in 1889.

Isotachophoresis

Isotachophoresis (ITP) is an electrophoresis technique in which ionic species separate into adjacent zones migrating at the same velocity, concentrating dilute analytes up to million-fold.

Isotherm analysis

Isotherm analysis interprets an adsorption isotherm, the gas or solute uptake of a material versus pressure at constant temperature, to quantify surface area, pore sizes, and adsorption behavior, most often by the BET method.

Isothermal calorimetry

Isothermal calorimetry is a family of techniques measuring the heat released or absorbed by a sample at constant temperature; its best-known form, isothermal titration calorimetry, studies molecular interactions.

Isothermal capacitance transient spectroscopy

Isothermal capacitance transient spectroscopy (ICTS) is an electrical technique that measures deep-level trap density and emission time constants in semiconductors at a fixed temperature, introduced by Okushi and Tokumaru in 1980.

Isothermal microcalorimetry

Isothermal microcalorimetry (IMC) measures microwatt-range heat flow from physical, chemical, or biological processes at constant temperature, serving as a universal, label-free probe of reaction rates.

Isothermal process

An isothermal process is a thermodynamic process in which a system's temperature stays constant while it expands or compresses; for an ideal gas, heat added equals work done.

Isothermal titration calorimetry

Isothermal titration calorimetry (ITC) is a biophysical technique that measures the heat released or absorbed when two biomolecules bind, yielding binding affinity, enthalpy, and stoichiometry from a single, label-free experiment used widely in drug discovery.

Isothiazole

Isothiazole is an aromatic five-membered heterocycle, formula C₃H₃NS, with adjacent sulfur and nitrogen atoms; first synthesized in 1956, it serves as a scaffold in medicinal chemistry.