All articles starting with H

Hetao 101 (核桃编程)

Hetao 101 (核桃编程) is a Beijing education startup founded in 2017 by Zeng Pengxuan and Wang Yuhang that teaches programming to children aged 4 to 12.

Hetauda (हेटौंडा) is a sub-metropolitan city in Makwanpur District, Bagmati Province, Nepal, and the province's capital. At the Tribhuvan–Mahendra highway junction, it had 193,576 residents in 2021 and hosts Nepal's largest industrial estate.

Hetch Hetchy

Hetch Hetchy, a glacial valley in Yosemite National Park on the Tuolumne River, dammed under the 1913 Raker Act to form the O'Shaughnessy Dam reservoir supplying 2.7 million Bay Area residents.

Oct 15, 2026

HETE (satellite)

HETE, the High Energy Transient Explorer, was a series of two small NASA satellites designed to detect and localize gamma-ray bursts; HETE-2 launched in 2000 and operated until 2008.

Oct 15, 2026

HETE-2

HETE-2 (High Energy Transient Explorer 2) was a small astronomical satellite built by MIT that detected gamma-ray bursts from 2000 until 2008, transmitting burst positions to ground observers within seconds.

Hetepheres I

Hetepheres I was a queen of Egypt's Fourth Dynasty, wife of Sneferu and mother of Khufu, whose hidden burial chamber at Giza, found in 1925, held gilded furniture and an empty sarcophagus.

Hetepheres II

Hetepheres II was a royal woman of Egypt's Fourth Dynasty, daughter of King Khufu, wife of Prince Kawab, and mother of Meresankh III, known from tombs at Giza.

Hetephernebti

Hetephernebti, also spelled Hetephernebty, was a queen of Egypt's Third Dynasty, the wife of King Djoser, attested on boundary stones at Saqqara and a relief from Heliopolis.

Hetepti (king's mother)

Hetepti was an Egyptian royal woman of the late Twelfth Dynasty, known as the mother of King Amenemhat IV and attested by a single inscription at Medinet Madi.

Heteractinida

Heteractinida (order Heteractinida, Hinde 1888) is an extinct Paleozoic order of calcareous sponges (Calcarea) with octactine spicules, Cambrian to Permian, regarded as the early stem group of Calcarea.

Heteraster

Heteraster, an extinct Cretaceous toxasterid spatangoid (heart urchin) genus by d'Orbigny, type species Spatangus oblongus; 87 nominal species, defined by alternating ambulacral pore pairs, extinct by early Cenomanian.

Hetero Group of Companies

Hetero Group of Companies is an Indian pharmaceutical group founded in 1993 by Dr. B. Partha Saradhi Reddy in Hyderabad, a leading maker of generic anti-retroviral drugs.

Oct 22, 2026

Hetero-deformation-induced strengthening

Hetero-deformation-induced (HDI) strengthening is a strengthening and work-hardening mechanism in metals mixing soft and hard zones, where dislocation pileups create back stress, raising yield strength while sustaining ductility.

Sep 29, 2026

Hetero-Diels–Alder reaction

The hetero-Diels–Alder reaction is a [4+2] cycloaddition extending the all-carbon Diels–Alder reaction, in which a diene reacts with a heteroatom-containing dienophile to build six-membered heterocycles used in pharmaceutical synthesis.

Heteroaryl ethers

Heteroaryl ethers are ethers in which one group attached to oxygen is a heteroaryl group, a structural motif found in drugs such as lansoprazole and flecainide.

Heterobasidiomycetes

Heterobasidiomycetes: historical basidiomycete group with septate (phragmo)basidia, jelly fungi, rusts, and smuts, defined by Patouillard; now abandoned as polyphyletic after molecular phylogenetics.

Heterobranchia

Heterobranchia is a major clade of gastropod molluscs, established by Burmeister in 1837, that unites sea slugs, sea hares, bubble shells, and most land snails and slugs, with a fossil record reaching the Devonian.

Heterobranchus bidorsalis

Heterobranchus bidorsalis, African giant catfish or eel-like fattyfin catfish, a clariid catfish described 1809 from the Nile, ranging Senegal to Ethiopia, reaching 1500 mm and 30 kg, farmed and hybridized with Clarias gariepinus.

Heterobranchus longifilis

Heterobranchus longifilis (vundu, Sampa), Valenciennes 1840, a large African airbreathing clariid catfish up to 150 cm and 55 kg, widespread from the Nile to West Africa, Least Concern, farmed and used in heteroclarias hybrids.

Heterochromatin

Heterochromatin is the condensed, largely transcriptionally inert form of eukaryotic chromatin, defined by Emil Heitz in 1928; it comes in constitutive and facultative classes, carries H3K9me and HP1 marks, and silences repeats.

Heterochromia iridum

Heterochromia iridum, also called heterochromia iridis, is a difference in iris color between the two eyes or within one iris. Usually a harmless genetic trait, it can signal Horner syndrome, Waardenburg syndrome, neuroblastoma, injury, or latanoprost use.

Sep 29, 2026

Heterochronic parabiosis

Heterochronic parabiosis is a surgical method that joins the circulatory systems of a young and an old animal to test whether blood factors reverse tissue aging.

Heteroconchia

Heteroconchia is a clade of bivalve mollusks within Autobranchia, uniting Palaeoheterodonta, Archiheterodonta, and Euheterodonta; defined by heterodont hinge dentition and crossed-lamellar shell structure, supported by nuclear phylogenomics but disputed by mitochondrial trees favoring Amarsipobranchia.

Heterocyclic compound

A heterocyclic compound is a cyclic compound whose ring contains atoms of at least two different elements, most commonly carbon with nitrogen, oxygen, or sulfur.

Heterocyst

Heterocyst: specialized nitrogen-fixing cell of filamentous cyanobacteria such as Anabaena and Nostoc; thick glycolipid envelope shields oxygen-sensitive nitrogenase; spaced 10-15 cells apart; evolved 2,450-2,100 Ma.

Heterodera avenae

Heterodera avenae, the cereal cyst nematode or oat cyst nematode (Wollenweber, 1924), is a cyst-forming root parasite of wheat, barley, oats, and rye causing 20-50% grain losses in Australia, with one generation per year and pathotypes classified by the International Test Assortment.