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  • 1
    Electronic Resource
    Electronic Resource
    Mechanism of dynamic nuclear polarization in high magnetic fields (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 4922-4933 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Solid-state NMR signal enhancements of about two orders of magnitude (100–400) have been observed in dynamic nuclear polarization (DNP) experiments performed at high magnetic field (5 T) and low temperature (10 K) using the nitroxide radical 4-amino TEMPO as the source of electron polarization. Since the breadth of the 4-amino TEMPO EPR spectrum is large compared to the nuclear Larmor frequency, it has been assumed that thermal mixing (TM) is the dominate mechanism by which polarization is transferred from electron to nuclear spins. However, theoretical explanations of TM generally assume a homogeneously broadened EPR line and, since the 4-amino TEMPO line at 5 T is inhomogeneously broadened, they do not explain the observed DNP enhancements. Accordingly, we have developed a treatment of DNP that explicitly uses electron–electron cross-relaxation to mediate electron–nuclear polarization transfer. The process proceeds via spin flip–flops between pairs of electronic spin packets whose Zeeman temperatures differ from one another. To confirm the essential features of the model we have studied the field dependence of electron–electron double resonance (ELDOR) data and DNP enhancement data. Both are well simulated using a simple model of electron cross-relaxation in the inhomogeneously broadened 4-amino TEMPO EPR line. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1346640
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  • 2
    Electronic Resource
    Electronic Resource
    Elastase and Thrombogenesis (1963)
    [s.l.] : Nature Publishing Group
    Nature 197 (1963), S. 454-455 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] DURING the past two decades numerous theories have been developed concerning the various lesions associated with arterial disease. To account for the topographically discrete nature of the mural thrombi implicated by one such hypothesis1, the suggestion has been made that some fundamental change in ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/197454a0
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  • 3
    Electronic Resource
    Electronic Resource
    Hydroxyproline and Thermal Stability of Collagen (1957)
    [s.l.] : Nature Publishing Group
    Nature 180 (1957), S. 243-243 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We now wish to report some findings which bear on this question. In a study of the action of collagenase on samples of dermal collagen from sixty individuals, Keech3 found that fifty of these responded normally to the enzyme, the response being a function of age. Eight samples, however, failed to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/180243a0
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  • 4
    Electronic Resource
    Electronic Resource
    Mammalian Cellulose (1958)
    [s.l.] : Nature Publishing Group
    Nature 181 (1958), S. 470-472 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IT has been shown recently that following treatment with alkaline buffers collagenous tissue contains domains in which masses of 'elastiea staining material* can be observed1*2. Further work has shown that numerous fibres or lamellae with a high degree of birefringence may be associated ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/181470a0
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  • 5
    Electronic Resource
    Electronic Resource
    Mucopolysaccharides of Human Nuclei Pulposi (1957)
    [s.l.] : Nature Publishing Group
    Nature 179 (1957), S. 1078-1079 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Nuclei pulposi, from the last five lumbar disks of a subject aged seventy, were subjected to graded extraction as follows. The material was minced, suspended in water, and pulverized in a blendor. The suspension was filtered and the filtrate, after deproteinization by Sevag's method, furnished ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/1791078c0
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  • 6
    Electronic Resource
    Electronic Resource
    Apparent Transformation of Collagen Fibrils into ‘Elastin’ (1955)
    [s.l.] : Nature Publishing Group
    Nature 176 (1955), S. 966-969 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE present communication deals with certain electron microscopical, histological and biochemical observations which appear to indicate a possible transformation of collagen fibrils into elastin-like material. This work forms part of a general study of the properties of connective tissue undertaken ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/176966a0
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal Contraction of Collagen and its Dissolution with Elastase (1953)
    [s.l.] : Nature Publishing Group
    Nature 172 (1953), S. 1100-1100 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The complex structure of aorta and the close association of collagen and elastin fibres in this material makes it difficult for us to accept Dr. Banga's interpretation of the work of Schwarz and Dettmer3. With reference to their observations that the elastin fibrils are not dissolved under the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/1721100a0
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  • 8
    Electronic Resource
    Electronic Resource
    Structure of Elastic Tissue (1952)
    [s.l.] : Nature Publishing Group
    Nature 170 (1952), S. 264-266 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] ELASTIC fibres are described in standard histological texts as being yellow in colour, highly refractile and as exhibiting considerable elasticity1. The fibres run singly, branch freely and anastomose with one another and can be differentiated by selective stains such as acid orcein and resorcinol ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/170264a0
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  • 9
    Electronic Resource
    Electronic Resource
    Movement of Proteins on Filter Paper (1951)
    [s.l.] : Nature Publishing Group
    Nature 168 (1951), S. 685-687 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE separation of proteins by chromatography has been described by several workers1-8. Recently, Franklin and Quastel3'1 reported the separation of proteins on filter paper. They developed two-way ehromatograms with a variety of solvents (sugars, amino-acids and sodium salts of weak dibasic or ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/168685a0
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  • 10
    Electronic Resource
    Electronic Resource
    High frequency (140 GHz) dynamic nuclear polarization: Polarization transfer to a solute in frozen aqueous solution (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 9494-9497 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dynamic nuclear polarization (DNP) transfers the large polarization of unpaired electrons to nuclei and thus significantly enhances the signal strength in nuclear magnetic resonance (NMR) spectroscopy. High frequency/field (140 GHz/5 T) DNP has been implemented in solid state NMR experiments using a nitroxide radical as the paramagnetic polarizing agent in a water:glycerol frozen solution. The 1H and 13C NMR signal strengths of both the solvent and an amino acid solute have been enhanced by a factor of 185, which represents a reduction of (approximately-greater-than)102 in sample size requirements or (approximately-greater-than)104 in signal acquisition time. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468818
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