All articles starting with H
20,046 articles
High-entropy oxide electrodes
High-entropy oxide electrodes are battery and electrocatalyst electrodes made from oxides with five or more randomly mixed metal cations in a single phase, stabilized by configurational entropy since 2015.
High-entropy oxide thermal barrier coatings
High-entropy oxide thermal barrier coatings are thermal barrier coatings whose ceramic topcoat is a high-entropy oxide with five or more cations, candidates to replace yttria-stabilized zirconia.
High-entropy oxides
High-entropy oxides are multicomponent oxide ceramics, typically with five or more cations in near-equiatomic ratios, known for intrinsically low thermal conductivity and use in thermal barrier coatings.
High-entropy shape-memory alloys
High-entropy shape-memory alloys (HESMAs) are shape-memory alloys following the high-entropy alloy principle, mixing five or more principal elements for higher strength, wider transformation temperature range, and better thermal cycling stability than conventional alloys.
High-entropy solid electrolytes
High-entropy solid electrolytes (HESEs) are solid ion-conducting battery materials that mix several cations or anions into one disordered lattice, an approach adapted from high-entropy alloys to raise ionic conductivity.
High-entropy thermoelectrics
High-entropy thermoelectrics are thermoelectric materials in which several principal elements share the same lattice sites, stabilizing a single disordered phase that scatters phonons and lowers thermal conductivity.
High-explosive squash head
High-explosive squash head (HESH), known in American usage as high-explosive plastic (HEP), is a shell that flattens plastic explosive on armor and defeats it by spalling.
High-Fat Diet
High-fat diet: consumption of excessive dietary fats (MeSH D059305). Covers habitual high-fat intake limited by WHO guidance and deliberate ketogenic regimens (4:1 ratio, under 50 g carbohydrate daily) used for epilepsy since the 1920s.
High-flow oxygen therapy
High-flow oxygen therapy (HFNC) delivers heated, humidified blended air and oxygen through wide-bore nasal prongs at 20 to 70 L/min, used for hypoxemic respiratory failure, post-extubation support, and pediatric bronchiolitis.
High-flux dialysis
High-flux dialysis is a form of hemodialysis that uses dialyzer membranes with high water permeability and larger pores, allowing removal of middle-molecular-weight solutes such as beta-2-microglobulin beyond conventional low-flux clearance.
High-Flyer (幻方)
High-Flyer (幻方) is a Chinese quantitative hedge fund founded in 2015 by Liang Wenfeng, whose AI-driven portfolio peaked at 100 billion yuan before it incubated DeepSeek.
High-Flyer Quant
High-Flyer Quant (幻方量化, 九章资产) is a Hangzhou-based quantitative hedge fund founded by Liang Wenfeng and Xu Jin that uses deep-learning models to trade Chinese securities.
High-frequency Active Auroral Research Program
The High-frequency Active Auroral Research Program, known as HAARP, is an ionospheric research facility in Gakona, Alaska, whose 180-antenna array radiates 3.6 megawatts into the upper atmosphere.
High-frequency audiometry
High-frequency audiometry, also called extended high-frequency (EHF) audiometry, is a diagnostic hearing test measuring the quietest audible tones above 8 kHz, up to 20 kHz.
High-frequency chest wall oscillation
High-frequency chest wall oscillation (HFCWO) is an airway clearance therapy in which an inflatable vest vibrates the chest at 5–25 Hz to loosen mucus, prescribed mainly for cystic fibrosis.
High-frequency trading
High-frequency trading, or HFT, is a form of algorithmic trading in which computers initiate and manage orders at high speed, accounting for roughly half of US equity volume.
High-frequency transformer
A high-frequency transformer transfers power at frequencies far above the 50 or 60 Hz grid, typically tens of kilohertz, providing galvanic isolation in switched-mode power supplies, DC-DC converters, and solid-state transformers.
High-frequency ultrasound imaging
High-frequency ultrasound imaging uses acoustic frequencies above the conventional 2–15 MHz diagnostic range to image superficial tissues at near-microscopic resolution, in ophthalmology, dermatology, and intravascular imaging.
High-frequency ventilation
High-frequency ventilation (HFV) is a ventilation technique delivering tiny tidal volumes at several hundred breaths per minute, used for over 30 years in newborns, especially preterm infants.
High-fructose corn syrup
High-fructose corn syrup (HFCS), a corn-starch-derived liquid sweetener with 42% or 55% fructose (HFCS-42, HFCS-55), replaced sucrose in most US beverages by the mid-1980s; cheaper than sugar, GRAS status, declining use since 2000.
High-functioning autism
High-functioning autism is an informal, non-diagnostic label for autistic people with average or above IQ and speech, roughly DSM-5 level 1 ASD; clinicians and advocates now prefer support-needs language.
High-gain antenna
A high-gain antenna (HGA) is a directional antenna that concentrates radio power into a narrow beam, the principal dish antenna spacecraft use to communicate across interplanetary distances.
High-grade B-cell lymphoma
High-grade B-cell lymphoma (HGBL) is an aggressive B-cell non-Hodgkin lymphoma, about 2% of cases, defined by MYC and BCL2 rearrangements or blastoid morphology, and often refractory to standard therapy.
High-grade neuroendocrine carcinoma of the cervix uteri
High-grade neuroendocrine carcinoma of the cervix uteri, also called poorly differentiated neuroendocrine cervical carcinoma, is a rare aggressive cervical cancer (about 1-2% of cases) linked to HPV 18, comprising small cell and large cell types, with 5-year survival around 25-40%.
High-grade second degree atrioventricular block
High-grade (advanced, high-degree) second degree AV block: two or more consecutive non-conducted P waves at a normal atrial rate with some conduction preserved; usually infra-Hisian, generally requiring permanent pacing.
High-harmonic fast-wave heating
High-harmonic fast-wave (HHFW) heating is a radio-frequency technique for heating fusion plasmas and driving current by launching the fast magnetosonic wave at high harmonics of the ion cyclotron frequency so electrons absorb it.
High-harmonic generation
High-harmonic generation (HHG) is an extreme nonlinear optical process in which intense femtosecond laser pulses drive atoms or solids to emit coherent extreme-ultraviolet light and attosecond pulses.
High-harmonic spectroscopy
High-harmonic spectroscopy (HHS) is an all-optical technique that uses an intense laser to drive an electron from its atom or molecule and back, probing the medium with attosecond resolution.
High-heeled shoe
A high-heeled shoe raises the heel above the toe, shifting weight forward. Originating in Persian cavalry footwear, it became male aristocratic status wear in Baroque Europe, then women's fashion.
High-income economy
A high-income economy is a country or territory the World Bank classifies in its top income group, with GNI per capita above $14,375; 83 economies qualified in 2022.