All articles starting with S

Semialdehyde

Semialdehyde, also called aldehydic acid, is a monocarboxylic acid derived from a dicarboxylic acid by the formal reduction of one carboxy group to a formyl group.

Semibalanus balanoides, the northern acorn barnacle (formerly Balanus balanoides), is a dominant North Atlantic intertidal barnacle; a cross-fertilizing hermaphrodite breeding below 7.2 °C, subject of Connell's 1961 competition experiments, with a 350 km poleward US range shift.

Semicircle law

The semicircle law is a theorem of random matrix theory stating that the eigenvalues of a large random Hermitian matrix converge to a half-circle-shaped density.

Semicircular canals

Semicircular canals: three fluid-filled inner-ear loops (anterior, posterior, horizontal) sensing angular head acceleration via endolymph-cupula mechanics; basis of the VOR, Ewald's laws, BPPV, and vHIT/caloric testing.

Sep 29, 2026

Semiclassical approximation

The semiclassical approximation treats wave propagation as a family of classical ray trajectories, yielding ray paths, travel times, amplitudes, and phases, and is used in seismology and gravitational wave physics.

Semiclassical gravity

Semiclassical gravity is the framework in which a classical spacetime, governed by general relativity, is sourced by the expectation value of quantum matter's stress-energy tensor, as in Hawking radiation.

Semiclathrate hydrates

Semiclathrate hydrates are crystalline inclusion compounds in which guest species like tetra-n-butylammonium bromide help build the host framework, forming above 0 degrees C near atmospheric pressure.

Semicolon

Semicolon (;), punctuation mark joining closely related independent clauses and separating complex list items. Invented in Venice in 1494 by Aldus Manutius for De Aetna; Unicode U+003B; flourished in the 17th-18th centuries, now often discouraged.

SEMICON West

SEMICON West is the flagship North American exposition for the semiconductor supply chain, organized annually by SEMI since 1971 and long held at the Moscone Center in San Francisco.

Semiconducting epigraphene

Semiconducting epigraphene is epitaxial graphene grown on silicon carbide that acts as a semiconductor with a 0.6 eV band gap, reported in 2024 by Walter de Heer's team at Georgia Tech.

Semiconducting polymer nanoparticles

Semiconducting polymer nanoparticles (SPNs), also called semiconducting polymer dots, are organic nanoparticles made from light-absorbing semiconducting polymers, used chiefly as imaging agents and for phototherapy.

Semiconductor

A semiconductor is a material, such as silicon, whose electrical conductivity can be tuned over a wide range, and it is the base material for most electronics.

Semiconductor detector

A semiconductor detector converts ionizing radiation directly into electrical charge inside a silicon or germanium crystal, giving far better energy resolution than gas-filled or scintillation detectors.

Semiconductor device

A semiconductor device is an electronic component whose operation depends on controlled conduction of a semiconductor such as silicon, from diodes and transistors to integrated circuits.

Semiconductor device fabrication

Semiconductor device fabrication, also called silicon chip fabrication, builds integrated circuits layer by layer on ultrapure silicon wafers, with leading-edge fabs costing billions of dollars.

Semiconductor drift detector

The semiconductor drift detector, most commonly the silicon drift detector (SDD), is a silicon radiation sensor with a small, low-capacitance anode giving high X-ray energy resolution.

Semiconductor industry

The semiconductor industry designs and manufactures integrated circuits, the chips in every modern electronic system, operating as a global production chain with sales of $630.5 billion in 2024.

Semiconductor industry in China

Semiconductor industry in China: the Chinese integrated circuit design, fabrication, packaging, equipment, and materials sector under the 2014 National IC Plan, Big Fund, and Made in China 2025; largest chip consumer, third-ranked producer, about 30% self-sufficiency.

Semiconductor Manufacturing International Corporation

Semiconductor Manufacturing International Corporation (SMIC) is a Chinese semiconductor wafer foundry headquartered in Shanghai and the world's third-largest foundry, founded in 2000 by Richard Chang.

Semiconductor optical amplifier

A semiconductor optical amplifier (SOA) is an electrically pumped semiconductor device that provides optical gain to light signals, working in both 1310 nm and 1550 nm fiber bands.

Semiconductor plasmonics

Semiconductor plasmonics is the branch of nanophotonics that uses heavily doped semiconductors instead of noble metals to support tunable plasmon resonances from the visible to the far-infrared.

Semiconductor-superconductor hybrid nanowire

A semiconductor-superconductor hybrid nanowire is a nanoscale semiconductor wire, typically InAs or InSb, coated with a thin superconducting shell that induces superconductivity through the proximity effect.

Semiconductor–superconductor nanowires

A semiconductor–superconductor nanowire is a hybrid device, typically indium arsenide or indium antimonide coated with aluminum, that induces superconductivity and hosts proposed Majorana zero modes.

Semiconservative replication

Semiconservative replication: the mode of DNA replication in which each daughter double helix keeps one parental strand and one new strand, proven by the 1958 Meselson–Stahl experiment in E. coli using 15N/14N density labeling.

Semicontinuity

Semicontinuity is a one-sided weakening of continuity for real-valued functions, where upper or lower semicontinuity permits jumps in one direction; introduced by René Baire in 1899, it underlies existence of minimizers.

Sep 29, 2026

Semidefinite programming

Semidefinite programming is a convex optimization technique that optimizes a linear function of a symmetric matrix under positive semidefinite constraints, generalizing linear programming and underpinning approximation algorithms, control theory, and machine learning.