All articles starting with H
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Hexagonal boron nitride spin defects
Hexagonal boron nitride spin defects are atom-like defects in hBN, chiefly the negatively charged boron vacancy, whose spins can be optically controlled at room temperature for quantum sensing.
Hexagonal close-packed
Hexagonal close-packed (HCP) is a crystal structure in which identical atoms stack in close-packed layers repeating ABABAB, giving each atom twelve equidistant nearest neighbors; it occurs in metals like magnesium, zinc, and titanium.
Hexagonal crystal family
The hexagonal crystal family, designated h, is one of six crystal families in three-dimensional crystallography, covering space groups with two free cell parameters, a and c.
Hexagonaria
Hexagonaria, extinct Devonian colonial rugose coral genus (family Disphyllidae) with honeycomb cerioid corallites; H. percarinatum of Michigan's Gravel Point Formation is the Petoskey stone; went extinct at end-Permian.
Hexagram
A hexagram is a six-pointed star figure, most familiarly the compound of two equilateral triangles known as the Star of David and Seal of Solomon.
Hexamethonium
Hexamethonium is a ganglion-blocking bis-quaternary ammonium compound, introduced in 1952 as the first effective drug class for severe hypertension and now used only in research.
Hexamethylbenzene
Hexamethylbenzene, also known as mellitene, is an aromatic hydrocarbon in which all six hydrogen atoms of benzene are replaced by methyl groups; its X-ray structure proved the benzene ring is a flat hexagon.
Hexamethylbenzene dication
The hexamethylbenzene dication is a carbocation with one carbon bonded to six others in a pentagonal pyramid, first prepared in 1973 and confirmed by X-ray crystallography in 2016.
Hexamethyldisiloxane
Hexamethyldisiloxane (HMDSO) is the simplest linear methyl siloxane, a volatile liquid made from chlorotrimethylsilane and used as a silicone intermediate, plasma-deposition precursor, and cosmetic ingredient.
Hexamethylene diisocyanate
Hexamethylene diisocyanate (HDI), also called 1,6-diisocyanatohexane, is a colorless aliphatic diisocyanate used almost entirely to make polyurethane foams, coatings, and hardeners for two-component automobile paints.
Hexamethylene triperoxide diamine
Hexamethylene triperoxide diamine (HMTD) is an organic peroxide primary explosive, first synthesized in 1885 and known as an improvised explosive used in the 2005 London bombings.
Hexamethylenediamine
Hexamethylenediamine, also called 1,6-hexanediamine or diaminohexane, is a corrosive six-carbon diamine, made by hydrogenating adiponitrile, that is best known as the amine monomer of nylon 6,6.
Hexamethylenetetramine
Hexamethylenetetramine (C6H12N4), also known as hexamine or methenamine, is a cage-like white crystalline compound made from formaldehyde and ammonia, used to cure resins, make RDX, fuel tablets, and treat urinary infections.
Hexamethylphosphoramide
Hexamethylphosphoramide (HMPA), also called hexamethylphosphoric triamide, is a polar aprotic solvent used in organic synthesis to solvate metal cations and accelerate SN2 reactions, though its carcinogenicity limits its use.
Hexamidine
Hexamidine is an aromatic diamidine antiseptic (C20H26N4O2), used as its diisethionate salt for skin infections, amoebic keratitis, and as a preservative, limited to 0.1% in cosmetics.
Hexamilion wall
The Hexamilion wall (Greek: Εξαμίλιον τείχος), a Roman barrier across the Isthmus of Corinth, was built under Theodosius II to shield the Peloponnese from invasion.
Hexanal
Hexanal, also known as hexaldehyde or caproaldehyde, is a saturated fatty aldehyde, a clear colorless liquid with a pungent odor that becomes fruity on dilution.
Hexane
Hexane is a liquid hydrocarbon whose straight-chain form, n-hexane, is a highly flammable petroleum solvent used to extract vegetable oils and make glues, and whose chronic inhalation damages the peripheral nerves.
Hexane-2,5-dione
Hexane-2,5-dione, also called acetonyl acetone or 2,5-hexanedione, is a 1,4-diketone that is both the standard substrate for the Paal-Knorr pyrrole synthesis and the neurotoxic metabolite of n-hexane, whose urinary levels serve as the biomarker of exposure.
Hexanitrodiphenylamine
Hexanitrodiphenylamine, also known as dipicrylamine or Hexyl, is a powerful yellow crystalline explosive with a detonation velocity of 7200 m/s, used by Germany and Japan in the World Wars.
Hexapod machine tool
A hexapod machine tool is a machining center built on a Gough–Stewart platform, where six variable-length struts move the spindle with six degrees of freedom, introduced in the 1990s.
Hexapoda
Hexapoda is a subphylum of six-legged arthropods comprising the insects and the wingless springtails, coneheads, and two-pronged bristletails. With over one million described species, it is the largest group in the phylum Arthropoda.
Hexapyla
Hexapyla ("six gates") were the gates in the northern wall of Epipolae at Syracuse, Sicily, through which Dion (357 BC) and Marcellus (213 BC) entered the city; Pleiades also records a sanctuary north of Syracuse.
HEXASIIL
HEXASIIL (SIIHEXA) is a WHO-prequalified, fully liquid hexavalent DTwP-HepB-IPV-Hib infant vaccine by Serum Institute of India, given at 6, 10, 14 weeks plus a 12-24 month booster.
Hexasodium phytate
Hexasodium phytate (SNF472, hexasodium fytate), intravenous hexasodium salt of phytate (IP6) that binds hydroxyapatite to inhibit vascular calcification and calciphylaxis; tested through phase 3 in hemodialysis patients.
Hexasterophora
Hexasterophora (Schulze, 1886) is the larger subclass of glass sponges (Hexactinellida), defined by hexaster microscleres; sister to Amphidiscophora, with orders Lyssacinosida, Sceptrulophora, and Lychniscosida.
Hexathelid and related tunnel-web spiders of Australasia
Australasian tunnel-web spiders: Australian funnel-web spiders (Atracidae: Atrax, Hadronyche, Illawarra), slender funnel-webs (Hexathelidae), and NZ tunnelwebs (Porrhothelidae); 2018 phylogenomic split of Hexathelidae, δ-hexatoxin venom, and 1981 antivenom.
Hexavalent chromium
Hexavalent chromium, also called chromium-6 or Cr(VI), is chromium in the +6 oxidation state and a known human carcinogen used in electroplating, welding, and stainless steel production.
Hexaxim
Hexaxim (also Hexyon, Hexacima) is Sanofi Pasteur's fully liquid 6-in-1 hexavalent infant vaccine against diphtheria, tetanus, acellular pertussis, polio, hepatitis B, and Hib; WHO-prequalified since December 2014, first licensed 2012, sold in over 100 countries.
Hexazinone
Hexazinone (Velpar, CAS 51235-04-2) is a triazine-dione herbicide, first US-registered in 1975, inhibiting photosynthesis; used on alfalfa, sugarcane, blueberries, and forestry, mobile in soil, low acute toxicity, eye irritant.