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The R/S system is an important nomenclature system for denoting enantiomers. This approach labels each chiral center R or S according to a system by which its substituents are each assigned a priority , according to the Cahn–Ingold–Prelog priority rules (CIP), based on atomic number.
More generally, for any pair of enantiomers, all of the descriptors are opposite: (R,R) and (S,S) are enantiomers, as are (R,S) and (S,R). Diastereomers have at least one descriptor in common; for example (R,S) and (R,R) are diastereomers, as are (S,R) and (S,S). This holds true also for compounds having more than two stereocenters: if two ...
Two enantiomers of a generic amino acid that are chiral (S)-Alanine (left) and (R)-alanine (right) in zwitterionic form at neutral pH. In chemistry, a molecule or ion is called chiral (/ ˈ k aɪ r əl /) if it cannot be superposed on its mirror image by any combination of rotations, translations, and some conformational changes.
E–Z configuration, or the E–Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry. It is an extension of cis – trans isomer notation (which only describes relative stereochemistry ) that can be used to describe double bonds having two, three or four substituents .
In most quiz bowl competitions, players and coaches may protest the moderator's decision if they believe their answer was incorrectly rejected, or an opponent's answer was incorrectly accepted. [3] Invalid protests or unnecessary protests can result in additional loss of points or an expulsion from the game.
The "Mini Blu-ray Disc" (also, "Mini-BD" and "Mini Blu-ray") is a compact 8-centimetre-diameter (3.1 in) variant of the Blu-ray Disc that can store 7.8 GB of data in its single-layer configuration, or 15.6 GB on a dual-layer disc. [140] It is similar in concept to the MiniDVD and Mini CD. Recordable (BD-R) and rewritable (BD-RE) versions of ...
Referred to in French as a 'Domestique'. A member of a team who chases down competitors and tries to neutralize their efforts; water carriers will often protect their team leader from the wind by surrounding them. When a leader has to get a repair or stop to answer nature, their domestiques will stay with them and pace them back up to the peloton.
The favored aspect ratio of mass-market display industry products has changed gradually from 4:3, then to 16:10, then to 16:9, and has now changed to 18:9 for smartphones. [7] [needs update] The 4:3 aspect ratio generally reflects older products, especially the era of the cathode ray tube (CRT).