PVED

These experimental results could not be confirmed by Lahav and co-workers they suggest that impurities in the starting materials have a much greater effect on the crystallisation process than the PVED (Parity Violating Energy Difference). Extensive experimental studies indicate the importance of small quantities of impurities, particularly in early phases of crystallisation nucleus formation. Amino acids from various sources were used, and the analyses were carried out using the enan-tioselective gas chromatography technique (M. Lahav et al 2006). 

In 1974 Garay and Hrasko [13] contended that PVEDs between enantiomers would, in the course of millions of years of evolution, lead to almost complete selection of one isomer, and in 1975 Letokhov [14] asserted that PVED-generated rate differences as small as 10-16 would over 10s to 109 years be quite sufficient for full selection of either of the two stereoisomeric forms of all the amino acids that occur in animate nature. In 1983 Kondepudi and Nelson [15] claimed that a value of AE/kTof 1017 to 1(T15 is sufficient to have a strong chiral selectivity. ... 

Building on an early theoretical scheme by Frank [16] (see below) for the spontaneous autocatalytic symmetry breaking in which enantiomers act as catalysts for their own production, Kondepudi and Nelson [17-20] further suggested a generalized scheme by which the minor excess of one enantiomer, caused by PVED, might lead to a state of enantiomeric homogeneity. They then calculated that a period as short as 15 000 years could cause chiral domination. [19] In 1989 MacDermott and Tranter [21] maintained that this amplification time would be reduced from 104 years to just one year if the PVED were increased to 10-16 kT , i.e., by a factor of only ten. 

Despite the theoretical difficulties outlined above, some small PVED between enantiomers does exist, on the order of 10 18 3 times the average thermal energy (feT) at room temperature per light-atom molecule. In a mole of a racemic mixture of amino acids, for example, this energy difference leads to an excess of approximately a million molecules of the more energetically stable enantiomer. Thus, we are led to search experimentally for how such minuscule excesses could be translated into a macroscale preference. As yet, another challenge, the measurement of the energy differences associated with the different enantiomers (PVEDs) so far eludes our detection abilities. 

PVED effects. After much study, Bonner [50] concluded that the data offer no evidence whatsoever for the efficacy or intervention of PVEDs. ... 

Since the historical PV weak force origin /3-decay experiment of 60Co [ 106], theoreticians presumed that the tiny parity violating WNC at molecular and subatomic levels may also allow a distinction between mirror image molecules at the macroscopic level as well. This is because PV-WNC at the molecular level may be a candidate for the homochiral scenario under terrestrial and extraterrestrial conditions [1,2,104,109-118]. The WNC, however, did not induce any observable PV effects between enantiomers in their ground states because of the minuscule PV energy difference (PVED) of 10 19 eV and/or negligibly small 10 - % ee in racemates. Theoreticians also proposed several possible amplification mechanisms at reproducible detection levels within laboratory time scales and at terrestrial locations [113,117,118]. 

Mason and Tranter performed calculations and alleged that a 1.4% excess of /- over r/-quartz on the surface of Earth is the inevitable consequence of a parity-violating energy difference (PVED). They calculated that the /-quartz is stabilized by lO kT per Si02 unit This allegation is based on a report that there is 50.17% /-quartz and 49.3% r/-quartz in 16,807 samples collected worldwide that is an excess of 1.4% of /-quartz. But a more recent survey of 27,053 samples yields 50.17 % r/-quartz and 49.83 % /-quartz, which is a. 0.39 % excess of r/-quartz. Therefore it is necessary to accept the fact that the terrestrial distribution of optically active quartz crystals is quite random and, consequently, no basis exists for calcula-... 

Thiemann showed that this calculation of PVED for quartz crystal seems to lack a soimd physical basis because in all examined quartz locations the amoimts of d- and /-quartz crystals are equal. Hence the quartz crystals are erroneously considered as a possible source of one handedness in nature, although local formation of optically active molecules, for example, via autocatalytic processes, appears quite possible in revealing chirality rather than homochirality (Klabunovskii ). 

For another way, based on PVED of enantiomers Mislow recently indicated ...if an enantiomeric excess as tiny as 10 % is sufficient to initiate the amplification then an ee value even as small as 10 % is surely capable in principle of initiating a similar cascade of processes leading to an optically active product. There is no reason to consider that for chiral initiators a critical ee value exists, somewhere between 10 Vo and 10 %, below which automultiplication of chirality can no longer take place..."... 

Antioxidant Effect on the Plaque Forming Cell (PFC) and Hemagglutination (HA) Pvesponses of Mice Immunized with Sheep Pved Blood Cells... 

This relation forms the basis for the search for the PVED effect in exactly those transitions for which ultranarrow saturation resonances were obtained. 

Because of these tirty and imclear PVED s, experimental consequences for chemistry are generally ruled out and have never been shown to exist beyorrd doubt (72). Parity violation is an accepted phenomenon in physics, brrt the question as to whether there is any cormection with biomolecttlar homochirahty on Earth rerrtains operr. 

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