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  • Chirality
  • Springer  (27)
  • American Physical Society  (1)
  • transcript Verlag  (1)
  • American Association for the Advancement of Science
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  • 1
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    Chirale Welten (2021)
    transcript Verlag | transcript Verlag
    Details
    Publication Date: 2024-04-04
    Description: Die Chemie büßt zugunsten physikalischer und lebenswissenschaftlicher Konzeptionen zunehmend an Deutungsmacht über die molekulare Welt ein. Sandra Lang untersucht, inwiefern die Ausdifferenzierung der chemischen Wissenschaften mit sich ebenfalls ausdifferenzierenden Zugriffen auf das Molekulare zusammenhängt. Anhand der vier exemplarischen Grenzfelder Materialwissenschaften, Biomedizin, Pharmazie und Quantenchemie und deren Narrative zur molekularen Eigenschaft der Chiralität veranschaulicht sie die transformative Phase der Chemie angesichts sich wandelnder Innovationsdispositive.
    Keywords: Chemie ; Chiralität ; Molekülkonzept ; Naturwissenschaften ; Grenzarbeit ; Interdisziplinarität ; Hybridität ; Wissenschaft ; Technik ; Wissenschaftssoziologie ; Techniksoziologie ; Wissenssoziologie ; Wissenschaftsgeschichte ; Soziologie ; Chemistry ; Chirality ; Molecule Concept ; Natural Sciences ; Border Work ; Interdisciplinarity ; Hybridity ; Science ; Technology ; Sociology of Science ; Sociology of Technology ; Sociology of Knowledge ; History of Science ; Sociology ; thema EDItEUR::P Mathematics and Science::PD Science: general issues::PDR Impact of science and technology on society ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology
    Language: German
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    E-BOOK
  • 2
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    Entropy-driven formation of a chiral liquid-crystalline phase of helical filaments (2006)
    American Physical Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2006. This article is posted here by permission of American Physical Society for personal use, not for redistribution. The definitive version was published in Physical Review Letters 96 (2006): 018305, doi:10.1103/PhysRevLett.96.018305.
    Description: We study the liquid-crystalline phase behavior of a concentrated suspension of helical flagella isolated from Salmonella typhimurium. Flagella are prepared with different polymorphic states, some of which have a pronounced helical character while others assume a rodlike shape. We show that the static phase behavior and dynamics of chiral helices are very different when compared to simpler achiral hard rods. With increasing concentration, helical flagella undergo an entropy-driven first order phase transition to a liquid-crystalline state having a novel chiral symmetry.
    Description: M. S. and R. O. are supported by NIH Grant No. EB002583.
    Keywords: Entropy ; Molecular biophysics ; Liquid crystal phase transformations ; Symmetry ; Chirality
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: 765344 bytes
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    PAPER (OA)
  • 3
    Electronic Resource
    Electronic Resource
    Configurations of few lines in 3-space. Isotopy, chirality and planar layouts (1993)
    Springer
    Geometriae dedicata 45 (1993), S. 49-82 
    Details
    ISSN: 1572-9168
    Keywords: Realizability of line diagrams ; Isotopy of lines ; Chirality ; 51E15 ; 51G05 ; 57Q37
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We give a characterization of the planar layouts of configurations with at most five lines. From this we obtain a new proof of Viro's theorem that the isotopy type of such configurations is completely determined by chirality. We extend this result to labelled configurations. We also give an infinite family of non-realizable line diagrams, called ‘alternatingC-angles’, not containing non-realizable subdiagrams.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01667403
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and spectroscopic investigation of some dimeric coumarin and furanocoumarin models (1997)
    Springer
    Monatshefte für Chemie 128 (1997), S. 701-712 
    Details
    ISSN: 1434-4475
    Keywords: bis-Coumarins ; bis-Furanocoumarins ; Chirality ; Aldehyde hydrates ; 1H NMR ; 13C NMR ; Mass spectrometry ; Fragmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Synthese einiger dimerer Cumarin- und Furanocumarin-Modellverbindungen und ihre Strukturaufklärung mit1H- und13C-NMR- sowie Massenspektrometrie werden beschrieben. In Gegenwart von Feuchtigkeit werden einige der Aldehyde von ihren Hydraten begleitet. Verdoppelungen der Methoxy-1H-Signale von8 in Anwesenheit eines chiralen Lanthanoid-Verschiebungsreagenzes beweisen, daß8 ein Dimer ist. In den Massenspektren finden sich Hinweise für heterolytische Spaltungen der O-C-Bindungen. Solche Fragmentierungen sind bei aromatischen Ethern ungewöhnlich.
    Notes: Summary The synthesis of some dimeric coumarin and furanocoumarin models and their structure elucidation by1H NMR,13C NMR, and mass spectroscopy is presented. In the presence of moisture some aldehydes are accompanied by their hydrates. Methoxy signal doubling in the presence of a chiral lanthanide shift reagent proves the dimeric nature of compound8. In the mass spectra, heterolytic cleavage of the O-C linkage was noticed which is a rare fragmentation in the case of aromatic ethers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807602
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  • 5
    Electronic Resource
    Electronic Resource
    On the origin of molecular “handedness” in living systems (1975)
    Springer
    Journal of molecular evolution 6 (1975), S. 91-98 
    Details
    ISSN: 1432-1432
    Keywords: Asymmetry ; Biopoesis ; Chirality ; Geomagnetism ; Handedness ; Lava Flows ; Magnetite ; Optical Activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Elementary particle effects (β-decay) provide at best only a weakly handed radiation in the biologically effective energy ranges. Global magnetic effects coupled to sunlight are randomized by paleomagnetic reversals. Hence a persistent terrestrial handed bias at possible local biopoetic sites offers a more promising explanation for the origin of the "handedness" of the molecules found among living systems on earth. Magnetite in lava flows maintains a handed bias for surface catalysis through many magnetic reversals. Magnetite contaminated with sulfur has already been proposed by Granick as a biopoetic site because it provides a weak source of chemical energy derived by photochemical conversion. Indirect evidence for this hypothesis has been provided by the molecular structure of ferredoxin - a single strand of the 14 primordial amino acids wrapped around an FeS core. Lava flows have been suggested as biopoetic sites by Fox, since their temperature and chemical composition might allow for the rapid synthesis of prebiotic compounds at the surface of the primitive earth. The additional fact that magnetite in lava flows also provides a persistent handed site for surface catalysis offers a further argument for the experimental investigation of this specific biopoetic environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732290
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  • 6
    Electronic Resource
    Electronic Resource
    Neutral currents in weak interactions and molecular asymmetry (1975)
    Springer
    Journal of molecular evolution 6 (1975), S. 77-89 
    Details
    ISSN: 1432-1432
    Keywords: Optical Asymmetry ; Chirality ; Weak Interactions ; Neutral Currents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Weak interactions are parity violating forces, i.e. they differentiate between mirror images. Therefore it is a very attractive hypothesis to invoke weak interactions in explaining the origin of molecular asymmetry. It is, however, not clear whether weak interactions may operate between electrons and/or between electrons and protons? For these types of interactions so called neutral currents are needed. Recent experiments with muon neutrinos at CERN gave some evidence for the existence of neutral currents. Thus we may suppose that parity violating forces are active in molecules. In the first part of this paper a very elementary theory of weak interactions is outlined with special reference to the discovery of neutral currents. In the second part we show how weak interactions may differentiate between mirror image molecules. The asymmetrically distributed static charges in chiral molecules represent a helical potential field. This helical potential field may exert an effect on the orbital electrons and therefore coupling of spins and momenta occurs. Thus the enantiomers are parity transformed images not only as geometrical bodies, but their orbital electrons are parity transformed too as "a helical electron gas". Weak interactions will differentiate between L and D forms because their orbital electrons have a nonzero spin polarization with respect to their velocity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732289
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  • 7
    Electronic Resource
    Electronic Resource
    Amplification of chirality based upon the association of nucleic acid strands of opposite handedness (1987)
    Springer
    Journal of molecular evolution 25 (1987), S. 100-105 
    Details
    ISSN: 1432-1432
    Keywords: Chirality ; Origin of biomolecular chirality ; Nucleic acids ; Amplification of chirality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It is proposed that nucleotide strands of opposite handedness may strongly associate and thereby provide the key step of a mechanism for the amplification of a small enantiomeric excess in an initially near-racemic mixture of poly- or oligonucleotides. This hypothesis, if confirmed by experimentation, may have important implications for the question of the origin of biomolecular chirality. The results of preliminary NMR experiments are given, which do show evidence of a strong association between pentanucleotide RNA strands whose monomers have opposite chirality. Simple kinetic equations are solved to demonstrate the conditions under which such association can produce amplification of chirality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101751
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  • 8
    Electronic Resource
    Electronic Resource
    Couplings of character and of chirality in the origin of the genetic system (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 233-239 
    Details
    ISSN: 1432-1432
    Keywords: Amino acids ; Nucleotides Character ; Chirality ; Genetic system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data from the literature and new data presented here suggest that the genetic system (coding and protein synthesis) is based on relationships of character and structure between amino acids and nucleic acids. Character relationships seem to be anticodonic and structurally the greatest preferences are seen between the heteropair, l-amino acids and d-ribose nucleic acids. However, living systems using the other heteropair must have been equally likely. Homopairing (l-l and d-d) in living systems seems unlikely. Awareness of the heterocoupling of steric forms narrows somewhat the problem of understanding the origin of chirality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175499
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  • 9
    Electronic Resource
    Electronic Resource
    Radionuclide-induced evolution of DNA and the origin of life (1992)
    Springer
    Journal of molecular evolution 35 (1992), S. 346-355 
    Details
    ISSN: 1432-1432
    Keywords: DNA evolution ; Genetic code ; Groundwater radioactivity ; Radiation track properties ; Nucleotide polymerization ; Radiation repair ; Radiation resistance ; Chirality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Artesian groundwaters of high radionuclide concentration are ubiquitous and may have provided the large, sustained energy sources that were required to drive the multistage process of DNA and primordial cell evolution. The rapid, early development of the genetic code as well as its degeneracy can be attributed to exceptionally high radiation-induced mutation rates in this unique environment. The ability of double-strand DNA to direct enzymatic repair of radiation damage to single strands contributed importantly to its selective evolution. It is postulated that the polymerization of nucleotides took place at elevated temperatures within α-particle tracks of high ion and free-radical density, followed by rapid quenching to ambient conditions. It also is evident that radiation resistance and ploidy were important selection factors in cellular evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00161172
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  • 10
    Electronic Resource
    Electronic Resource
    β-Turn-driven early evolution: The genetic code and biosynthesis pathways (1987)
    Springer
    Journal of molecular evolution 25 (1987), S. 15-19 
    Details
    ISSN: 1432-1432
    Keywords: β-Turns ; Secondary structures ; Chirality ; Genetic code ; Biosynthetic pathways ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The physicochemical properties of β-turns suggest their biological importance prior to the formation of the genetic code. These properties include ones potentially affecting the preference for eitherl- ord-amino acids. The abundance of certain amino acids in β-turns is correlated with their assignment to a small, well-defined part of the genetic code and with their role as metabolic precursors for other amino acids. It is proposed that in the prebiotic environment, β-turns became objects of selection that influenced the evolution of the genetic code and biosynthetic pathways for amino acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02100036
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