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Solid HF consists of zig-zag chains of HF molecules. The HF molecules, with a short covalent H–F bond of 95 pm length, are linked to neighboring molecules by intermolecular H–F distances of 155 pm. [4] Liquid HF also consists of chains of HF molecules, but the chains are shorter, consisting on average of only five or six molecules. [5]
HF's position in the electromagnetic spectrum.. High frequency (HF) is the ITU designation [1] for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters).
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water.Solutions of HF are colorless, acidic and highly corrosive.A common concentration is 49% (48-52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling point near room temperature.
Hafnium, symbol Hf, a chemical element; Hartree–Fock method, a calculation scheme in the field of computational chemistry; Hydrogen fluoride, HF, a diatomic compound which can dissolve in water to form hydrofluoric acid, a highly corrosive solution; Hydrofluoric acid, HF (aq), a solution of hydrogen fluoride (HF) in water
Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF). VHF radio waves propagate mainly by line-of-sight, so they are blocked by hills and mountains, although due to refraction they can travel somewhat beyond the visual horizon out to about 160 km (100 miles).
HF: heart failure: HFpEF: heart failure with preserved ejection fraction: HFrEF: heart failure with reduced ejection fraction HFM: hand, foot and mouth disease: HFMD: hand, foot and mouth disease: HFNC: high flow Nasal cannula: HFRS: hemorrhagic fever with renal syndrome HGB: hemoglobin: HGH Human Growth Hormone: HGSIL: high-grade squamous ...
Another form of economic effect is the cost of product failures during the switch to RoHS compliance. For example, tin whiskers were responsible for a 5% failure rate in certain components of Swiss Swatch watches in 2006, prior to the July implementation of RoHS, reportedly triggering a US$1 billion recall.
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF typically presents with shortness of breath , excessive fatigue , and bilateral leg swelling . [ 3 ]