All articles starting with D
24,034 articles
Diaspora politics
Diaspora politics is the political engagement of emigrant communities with the politics of their homeland, including state policies such as external voting and diaspora institutions, now found in over half of UN member states.
Diaspora Revolt
The Diaspora Revolt, also known as the Second Jewish–Roman War, was a series of Jewish uprisings in Roman Egypt, Cyrenaica, and Cyprus during 115–117 CE, under Emperor Trajan.
Diaspore
Diaspore is an aluminum oxide hydroxide mineral, a principal aluminum-bearing component of bauxite alongside gibbsite and böhmite, and a color-change gemstone sold as Zultanite or Csarite.
Diastasis of muscle
Diastasis of muscle, or myodiastasis, ICD-11 FB32.0: pathological separation of muscle fibers from fibers, tendons, or fascia. Most common form is diastasis recti abdominis, defined as linea alba widening over 2 cm.
Diastasis recti
Diastasis recti (diastasis recti abdominis, rectus diastasis) is a widening of the linea alba over 2 cm separating the rectus abdominis muscles, common in pregnancy; treated with exercise or fascial plication surgery.
Diastema
Diastema (tooth gap) is a space between adjacent teeth, most often the upper central incisors (midline diastema). Causes include genetics, oversized frenum, habits, and gum disease; treatments include bonding, veneers, braces, and frenectomy.
Diastereomer
Diastereomers, also called diastereoisomers, are stereoisomers that are not mirror images, unlike enantiomers, so they differ in melting point and can be separated by crystallization.
Diastereomeric excess
Diastereomeric excess (de, or diastereoisomer excess) is a stereochemistry measure: the difference between the mole fractions of two diastereomers, defined by IUPAC by analogy with enantiomeric excess.
Diastereoselectivity
Diastereoselectivity is the preferential formation in a chemical reaction of one diastereoisomer over another, quantified by diastereomeric ratio and rationalized by models such as Cram's rule and Felkin–Anh.
Diastereotopic
Diastereotopic describes two identical atoms or groups in a molecule whose separate replacement by another group yields diastereomers, stereoisomers that are not mirror images of each other.
Diastole
Diastole: the relaxation and filling phase of the cardiac cycle, opposite systole. Covers its four phases, diastolic blood pressure, diastolic dysfunction grading, and the 2025 ASE echocardiography guidelines.
Diastolic function
Diastolic function is the left ventricle's ability to relax and fill with blood during diastole, assessed mainly by echocardiography and central to heart failure with preserved ejection fraction.
Diastrophic dysplasia
Diastrophic dysplasia (DTD, diastrophic dwarfism) is a rare autosomal recessive skeletal dysplasia caused by SLC26A2 mutations, marked by short stature, joint contractures, hitchhiker thumbs, and cleft palate; most survive to adulthood.
Diatessaron
The Diatessaron is a single continuous gospel account woven from Matthew, Mark, Luke, and John by Tatian in the late second century, the first known gospel harmony.
Diathermy
Diathermy, or deep heating, is a therapy using shortwave, microwave, or ultrasound energy to heat tissue below the skin for pain and muscle conditions, and a surgical technique (electrosurgery) for cutting tissue and coagulating blood.
Diathesis–stress model
Diathesis–stress model: psychiatric theory that disorders arise when an underlying vulnerability (diathesis, genetic or psychological) interacts with environmental stress; rooted in 19th-century predisposing/exciting causes, formalized by Meehl and Zubin & Spring.
Diatom
Diatoms (Bacillariophyceae) are single-celled golden-brown algae with silica cell walls (frustules), 2–500 µm, 20,000 to 2 million estimated species, driving ~40% of oceanic carbon fixation and used in water monitoring and diatomite.
Diatom analysis
Diatom analysis identifies microscopic siliceous algal remains in sediments, water, or body tissues to infer drowning, sample provenance, or past environmental conditions; bone marrow is the most reliable tissue.
Diatomaceous earth
Diatomaceous earth, also called diatomite or kieselguhr, is a soft, finely porous siliceous sedimentary rock made of fossilized diatom skeletons, used mainly as a filter aid and insecticide.
Diatomaceous earth and perlite filtration media
Diatomaceous earth (diatomite, kieselguhr) and expanded perlite are the two principal mineral filter aids used as precoat or body feed in food, beverage, pharmaceutical, and chemical filtration, differing in bulk density, crystalline silica content, and trace metal leaching.
Diatomic molecule
A diatomic molecule is a molecule made of exactly two atoms, either of the same element, such as H2 and O2, or of different elements, such as CO.
Diatonic and chromatic
Diatonic and chromatic: paired music-theory terms from Greek tetrachord genera. Diatonic notes belong to a key's scale; chromatic notes fall outside it, with distinct semitone sizes in unequal tunings.
Diatonic scale
The diatonic scale is a seven-note musical scale with five whole steps and two half steps per octave, the basis of most Western tonal music.
Diatrizoate
Diatrizoate, also called diatrizoic acid or amidotrizoic acid, is a high-osmolality iodinated X-ray contrast medium, developed in 1953 and used in gastrointestinal studies, angiography, and urography.
Diauehi
Diauehi, also known as Daiaeni, was an Iron Age kingdom near Urartu in eastern Anatolia, attested from the 12th century BC and conquered by Urartu in the 8th century BC.
Diavik Diamond Mine
The Diavik Diamond Mine was a Rio Tinto diamond mine on an island in Lac de Gras, Northwest Territories, Canada, producing over 150 million carats from 2003 to 2026.
Diazepam
Diazepam (Valium) is a long-acting benzodiazepine introduced by Hoffmann-La Roche in 1963 for anxiety, alcohol withdrawal, muscle spasm, and status epilepticus; half-life 24-48 h with active metabolite 50-120 h.
Diazinon
Diazinon, also sold as Dimpylate or Basudin, is a synthetic organophosphate insecticide with formula C12H21N2O3PS, registered in 1956 and phased out of residential use by 2004 over health risks.
Diazirine photoaffinity probes
Diazirine photoaffinity probes are small molecules in which a diazirine group, activated by UV light to a reactive carbene, covalently captures a ligand's protein targets for mass spectrometry.
Diazirine-based photoaffinity labeling
Diazirine-based photoaffinity labeling is a chemical biology technique in which a diazirine tag, activated by UV light, covalently captures the protein targets of small molecules.