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Viedma Ripening
Viedma ripening or attrition-enhanced deracemization is a chiral symmetry breaking phenomenon observed in solid/liquid mixtures of enantiomorphous (Racemic mixture, racemic conglomerate) crystals that are subjected to comminution. It can be classified in the wider area of spontaneous symmetry breaking phenomena observed in chemistry and physics. It was discovered in 2005 by geologist Cristobal Viedma, who used glass beads and a magnetic stirrer to enable particle breakage of a racemic mixture of enantiomorphous sodium chlorate crystals in contact with their saturated solution in water. A Sigmoid function, sigmoidal (Autocatalysis, autocatalytic) increase in the solid-phase enantiomeric excess of the mixture was obtained, eventually leading to homochirality, i.e. the complete disappearance of one of the Chirality, chiral species. Since the original discovery, Viedma ripening has been observed in a variety of intrinsically chiral organic compounds that exhibit conglomerate crystallizat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chiral Symmetry Breaking
In particle physics, chiral symmetry breaking is the spontaneous symmetry breaking of a chiral symmetry – usually by a gauge theory such as quantum chromodynamics, the quantum field theory of the strong interaction. Yoichiro Nambu was awarded the 2008 Nobel prize in physics for describing this phenomenon ("for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics"). Overview Quantum chromodynamics Experimentally, it is observed that the masses of the octet of pseudoscalar mesons (such as the pion) are much lighter than the next heavier states such as the octet of vector mesons, such as rho meson. This is a consequence of spontaneous symmetry breaking of chiral symmetry in a fermion sector of QCD with 3 flavors of light quarks, , , and . Such a theory, for idealized massless quarks, has global chiral flavor symmetry. Under SSB, this is spontaneously broken to the diagonal flavor ''SU''(3) subgroup, generating eight Nambu–Goldstone bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |