All articles A–Z
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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.
Diazomethane
Diazomethane (CH₂N₂) is the simplest diazo compound, a yellow gas that is highly toxic and explosive, so it is freshly prepared in dilute ether solution to methylate acids in the laboratory.
Diazonium compound
A diazonium compound, or diazonium salt, is a salt of the cation R-N2+, known since 1858 as a versatile intermediate in aromatic chemistry, though many are thermally unstable and hazardous.
Diazotization
Diazotization is the chemical conversion of a primary aromatic amine into an arenediazonium salt by nitrous acid at low temperature, introduced by Peter Griess in 1863 and central to azo dye production.
Diazoxide
Diazoxide is a benzothiadiazine-derived drug that opens ATP-sensitive potassium channels; originally an antihypertensive, it treats hypoglycemia from excess insulin and, as a choline salt, hyperphagia in Prader-Willi syndrome.
Dibaba family
The Dibaba family is an Ethiopian distance-running family from Chefe near Bekoji, in the Arsi region; sisters Ejegayehu, Tirunesh, Genzebe, Anna, and Melat have won Olympic and world medals.
Dibakar Banerjee (दिबाकर बनर्जी)
Dibakar Banerjee (दिबाकर बनर्जी), born 1969 in New Delhi, is an Indian Hindi-film director, screenwriter, and producer, not the astrophysicist or other namesakes. Known for Khosla Ka Ghosla, LSD, Shanghai, Detective Byomkesh Bakshy!, and the shelved Netflix film Tees.
Dibang Multipurpose hydroelectric plant
The Dibang Multipurpose Project is a 2,880 MW hydroelectric and flood-moderation scheme on the Dibang river in Arunachal Pradesh, India, planned around India's highest dam and due in 2032.
Dibaratrir Kabya
Dibaratrir Kabya (দিবারাত্রির কাব্য) is a Bengali novel by Manik Bandopadhyay, written in 1929 at age 21 and published in 1935, an early study of love and the human mind.
Dibba Al-Fujairah
Dibba Al-Fujairah is a coastal town in the Emirate of Fujairah, UAE, on the Gulf of Oman near the Omani border, known for Bronze and Iron Age collective tombs.
Dibenzepin
Dibenzepin (Noveril, Wander), a tricyclic antidepressant, ATC N06AA08, formula C18H21N3O, introduced 1965; 480–720 mg daily; low antimuscarinic potency; distinct from other drugs named Noveril.