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  • 1
    Electronic Resource
    Electronic Resource
    Primordial origins of chirality (1975)
    [s.l.] : Nature Publishing Group
    Nature 254 (1975), S. 538-538 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In a new approach to this problem we carried out the crystallisation of DL-NaNH4 tartrate in the presence and absence of chiral p particles from 3aP. Below 27 C, DL-NaNH4 tartrate crystallises in racemic conglomerates18, that is, D and L crystallisation centres form independently and then grow. Any ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/254538a0
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  • 2
    Electronic Resource
    Electronic Resource
    Stereoselective crystallization induced by traces of dissolved optically active impurities (1977)
    Springer
    Journal of molecular evolution 10 (1977), S. 161-166 
    Details
    ISSN: 1432-1432
    Keywords: Induced resolution ; Chiral influence ; Sodium-ammonium tartrate ; Origin of optical activity ; Stereoselective crystallization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Isothermal crystallization of D,L-sodium-ammonium tartrate with traces of different impurities admixed shows that the added chiral contaminations produce a preferential crystallization of the tartrate isomer of same handedness. The critical lowest concentration of effective seeding agents is 0.1-0.5 %. 1 % optically active excess material induces 1.0-3.6 % optical purity in the deposited crystals. An analysis of the relevant data reported so far gives similar figures in different crystallization systems. The relation of the results to the suggested lattice energy difference between enantiomers is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01751809
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  • 3
    Electronic Resource
    Electronic Resource
    Beta irradiation may induce stereoselectivity in the crystallization of optical isomers (1981)
    Springer
    Origins of life and evolution of the biospheres 11 (1981), S. 37-52 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A novel approach has been introduced to detect the manifestation of symmetry breaking weak interactions at molecular level. In the racemic conglomerate crystallization of D, L-sodium-ammonium tartrate the effect of32P irradiation was studied by measuring the weight and optical purity of the crystalline phase as well as the size distribution of the crystallites. The high number of independent experiments (over 1000) permitted statistical analysis of the results. The following observations have been made: 1. Beta irradiation influences the crystallization process, irradiated samples yield more crystalline material. 2. The effect involves presumably crystal seed formation because from the irradiated solutions more and smaller crystallites are formed. 3. The presence of beta particles induces stereoselective crystallization, the crystalline phase shows optical activity characteristic of the “unnatural” L-isomer. 4. The above changes are attributed to the beta irradiation as the magnitude of the effects depends on the amount of added radioactivity. Optically active contaminants are highly unlikely sources of the differences between irradiated and control series. 5. In the absence of32P the tartrate enantiomers have equal probability to form crystals, i.e., the contribution of mixing of weak interaction into the electromagnetic one is not measurable in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00927997
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  • 4
    Electronic Resource
    Electronic Resource
    Recent advances in biohydrogen research (2000)
    Springer
    Pflügers Archiv 439 (2000), S. r081 
    Details
    ISSN: 1432-2013
    Keywords: Key words: biohydrogen ; environmental biotechnology ; metalloenzymes ; enzyme stability ; biogas ; denitrification.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. A fundamental and principal difficulty of the future energy supply is that the formation of fossil fuels is much slower than the rate of their exploitation. Therefore the reserves which can be recovered in an energetically feasible manner are shrinking parallel with an increasing world-wide energy demand. Among the alternative energy carriers, hydrogen is preferred because it is easy to transport and store and it burns to environmentally friendly water vapour when utilized. Hydrogen can be produced in biological systems, however, our understanding of the molecular details is just emerging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240000099
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  • 5
    Electronic Resource
    Electronic Resource
    Unconsidered sources of chirality in nature (1981)
    Springer
    Origins of life and evolution of the biospheres 11 (1981), S. 93-103 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00928001
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