Cf
CF, Cf, cf and similar may refer to:
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Science and medicine
2C-F
2C-F, or 4-fluoro-2,5-dimethoxyphenethylamine, is a lesser-known psychedelic drug of the 2C family. It was first synthesized by Alexander Shulgin. In his book PiHKAL (Phenethylamines i Have Known And Loved), the minimum dosage is listed as 250 mg. 2C-F may be found as a brownish freebase oil, or as a white crystalline hydrochloride salt.
Pharmacology
Very little data exists about the pharmacological properties, metabolism, and toxicity of 2C-F.
Effect
At a dose of 250 milligrams, 2C-F produces modest closed-eye visuals accompanied by lethargy. The amphetamine analogue DOF is likely to be more active than the phenethylamine derivative 2C-F, and in animal trials DOF was found to be 1/6 the activity of the potent hallucinogen DOI, which would make an active dose of DOF likely to be in the 6-18 milligram range, although it is not known to have been tested in humans.
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Difluoroacetylene
Difluoroacetylene, C2F2, is a compound of carbon and fluorine. A linear molecule, its two carbons are joined by a triple bond and have terminal fluorines: F-C≡C-F. The molecule is the perfluorocarbon analog of acetylene, C2H2. Preparation of difluoracetylene is difficult, with danger of explosions and with low yields. Nevertheless, the compound has been made, isolated, and characterized by NMR and IR spectroscopy. The compound is of interest as a precursor to fluoropolymers containing double bonds, analogous to polyacetylene.
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Comet Yi–SWAN
Comet C/2009 F6 (Yi–SWAN) is a non-periodic comet which appeared in March 2009.
It was first discovered by Korean amateur astronomer Dae-am Yi on March 26, 2009, using a Canon 5D camera and 90-mm lens. It is believed to be the first comet discovered by a Korean in the modern age. Independently, on April 4 Rob Matson reported he had discovered a comet in the SWAN instrument photographs on the SOHO (Solar and Heliospheric Observatory) spacecraft website.
The comet was not bright enough to be seen by the naked eye, but was theoretically visible through amateur telescopes. However, it was harder to see than predicted, as it remained quite small and did not form much of a visible tail. It reached a peak magnitude around +8.5 in April into May, and passed 1.5 degrees south of the Double cluster in Perseus on April 23.
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C/2007 F1
C/2007 F1 (LONEOS) is a hyperbolic comet discovered on March 19, 2007 as part as the Lowell Observatory Near Earth Object Search (LONEOS). The comet reached perihelion, or closest approach to the sun on October 28, 2007.
The comet reached 6th magnitude in October, making it easily visible in binoculars, and just barely visible to the naked eye for observers in the Northern Hemisphere, just after sunset in the west. It reached a max brightness of magnitude 5 around perihelion, before starting to slowly dim on its way out of the solar system. It continued to move south in the sky and became visible to southern hemisphere comet chasers in mid November.
The comet was also observed from both the STEREO spacecraft, first by STEREO-B on October 22 and then by STEREO-A for several days starting from October 28 as the comet had just passed perihelion and was receding from the Sun.
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Hexafluoroethane
Hexafluoroethane is a fluorocarbon counterpart to the hydrocarbon ethane. It is a non-flammable gas negligibly soluble in water and slightly soluble in alcohol.
Physical properties
Hexafluoroethane's solid phase has two polymorphs. In the scientific literature, different phase transition temperatures have been stated. The latest works assign it at 103 K (−170 °C). Below 103 K it has a slightly disordered structure, and over the transition point, it has a body centered cubic structure.
Table of densities:
Vapor density is 4.823 (air = 1), specific gravity at 21 °C is 4.773 (air = 1) and specific volume at 21 °C is 0.1748 m3/kg.
Uses
Hexafluoroethane is used as a versatile etchant in semiconductor manufacturing. It can be used for selective etching of metal silicides and oxides versus their metal substrates and also for etching of silicon dioxide over silicon. The primary aluminium and the semiconductor manufacturing industries are the major emitters of hexafluoroethane.
Together with trifluoromethane it is used in refrigerants R508A (61%) and R508B (54%).
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