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This same classification is also used by the National Weather Service. The National Weather Service of Quad Cities use a modified EF scale wording, which gives a new term for each rating on the scale, going from weak to catastrophic. [55] The table shows other variations of the tornado rating classifications based on certain areas.
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.
Buffered oxide etch (BOE), also known as buffered HF or BHF, is a wet etchant used in microfabrication. It is a mixture of a buffering agent, such as ammonium fluoride NH 4 F, and hydrofluoric acid (HF). Its primary use is in etching thin films of silicon nitride (Si 3 N 4) or silicon dioxide (SiO 2), by the reaction:
Group 4 is the second group of transition metals in the periodic table. It contains only the four elements titanium (Ti), zirconium (Zr), hafnium (Hf), and rutherfordium (Rf). ). The group is also called the titanium group or titanium family after its lightest me
Hafnium diboride belongs to the class of ultra-high temperature ceramics, a type of refractory ceramic composed of hafnium and boron. It has a melting temperature of about 3250 °C. It is an unusual ceramic, having relatively high thermal and electrical conductivities, properties it shares with isostructural titanium diboride and zirconium ...
The radioactive isotopes' half-lives range from 400 ms for 153 Hf [16] to 7.0 × 10 16 years for the most stable one, the primordial 174 Hf. [ 15 ] [ 18 ] The extinct radionuclide 182 Hf has a half-life of 8.9 ± 0.1 million years , and is an important tracker isotope for the formation of planetary cores . [ 19 ]
Now, normally: either VHF or UHF; HF communications avionics are usually abbreviated simply HF CORSIA Carbon Offsetting and Reduction Scheme for International Aviation: COTS Commercial off-the-shelf: CPA Closest point of approach CPDLC controller–pilot data link communications: CPR Changed product rule EASA: CPS Cycles per second CRD
Lu–Hf isotope system can provide information on where and when a magmatic body originate. By applying Hf concentration determination to zircons from A-type granites in Laurentia, ɛHf values ranging from −31.9 to −21.9 were obtained, representing a crustal melt origin. [18]