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An aperiodic tiling is a non-periodic tiling with the additional property that it does not contain arbitrarily large periodic regions or patches. A set of tile-types is aperiodic if copies of these tiles can form only non-periodic tilings.
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Khatyrkite is a rare mineral which is mostly composed of copper and aluminium, but may contain up to about 15% of zinc or iron. Its chemical structure is described by an approximate formula (Cu,Zn)Al2 or (Cu,Fe)Al2. It was discovered in 1985 in a placer in association with another rare mineral cupalite. These two minerals have only been found at 62°39′11″N174°30′02″E in the area of the Iomrautvaam, a tributary of the Khatyrka river, in the Koryak Mountains, in Anadyrsky District, Chukotka, Russia. Analysis of one of the samples containing khatyrkite showed that the small rock was from a meteorite. A geological expedition has identified the exact place of the original discovery and found more specimens of the Khatyrka meteorite. The mineral's name derives from the Khatyrka zone where it was discovered. Its type specimen is preserved in the Mining Museum in Saint Petersburg, and parts of it can be found in other museums, such as Museo di Storia Naturale di Firenze.
Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate is an anion with chemical formula [{3,5-(CF3)2C6H3}4B]−, which is commonly abbreviated as [BArF4]−, indicating the presence of fluorinated aryl (ArF) groups. It is sometimes referred to as Kobayashi's anion in honour of Hiroshi Kobayashi who led the team that first synthesised it. More commonly it is affectionately nicknamed "BARF." The BARF ion is also abbreviated BArF24−, to distinguish it from the closely related BArF−
20, [(C6F5)4B]−. However, for a small group of chemists, the anion is abbreviated as TFPB otherwise, short for Tetrakis[3,5-bis(triFluoromethyl)Phenyl]Borate.
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References
- ↑ Brown, David (2001-06-19). "The 'recipe for disaster' that killed 80 and left a £5bn bill". The Daily Telegraph . London. Retrieved 2014-12-02.
- ↑ Greider, Carol W.; Blackburn, Elizabeth H. (December 1985). "Identification of a Specific Telomere Terminal Transferase Activity in Tetrahymena Extracts". Cell . 43 (2:1): 405–13. doi: 10.1016/0092-8674(85)90170-9 . PMID 3907856.
- ↑ Willadsen, S. M. (1986). "Nuclear transplantation in sheep embryos". Nature . 320 (6057): 63–65. Bibcode:1986Natur.320...63W. doi:10.1038/320063a0. PMID 3951549. S2CID 4257911.
- ↑ Willadsen, S. M. (1989). "Cloning of sheep and cow embryos". Genome . 31 (2): 956–62. doi:10.1139/g89-167. PMID 2698854.
- ↑ Kramer, P.; Neri, R. (1984). "On periodic and non-periodic space fillings of Em obtained by projection". Acta Crystallographica. A40 (5): 580. doi:10.1107/S0108767384001203.
- ↑ Shechtman, D.; Blech, I.; Gratias, D.; Cahn, J. (1984). "Metallic Phase with Long-Range Orientational Order and No Translational Symmetry". Physical Review Letters . 53 (20): 1951–4. Bibcode:1984PhRvL..53.1951S. doi: 10.1103/PhysRevLett.53.1951 .
- ↑ Levine, Dov; Steinhardt, Paul Joseph (1984). "Quasicrystals: A New Class of Ordered Structures". Physical Review Letters. 53 (26): 2477–80. Bibcode:1984PhRvL..53.2477L. doi: 10.1103/PhysRevLett.53.2477 .
- ↑ Nishida, H.; Takada, N.; Yoshimura, M.; Sonods, T.; Kobayshi, H. (1984). "Tetrakis(3,5-bis(trifluoromethyl)phenyl)borate: Highly Lipophilic Stable Anionic Agent for Solvent-Extraction of Cations". Bulletin of the Chemical Society of Japan . 57 (9): 2600–2604. doi:10.1246/bcsj.57.2600.
- ↑ Maeda, Nobuyo; Yang, Funmei; Barnett, Don R.; Bowman, Barbara H.; Smithies, Oliver (1984). "Duplication within the haptoglobin Hp 2 gene". Nature. 309 (5964): 131–135. Bibcode:1984Natur.309..131M. doi:10.1038/309131a0. PMID 6325933. S2CID 4368535.
- ↑ "Ukrainian Viazovska wins Fields Medal 2022". www.ukrinform.net. July 2022. Archived from the original on 2022-07-07. Retrieved 2022-07-09.