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  • 1
    Electronic Resource
    Electronic Resource
    Mass fragmentation and structure of siphonaxanthin, siphonein and derivatives (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 565-572 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution mass spectrometry has been employed to establish the structural formulae of the unique carotenoid pigment siphonaxanthin, its natural ester, siphonein and several derivatives. Siphonaxanthin exhibits a fragmentation reaction that is unusual among carotenoid pigments, namely, the elimination of carbon dioxide, observed as [M - CO2] and [M - (CO2 + H2O)]. This reaction involves the migration of an oxygen atom. Siphonaxanthol, a partially hydrogenated siphonaxanthin, exhibits a similar reaction involving the elimination of carbon monoxide and formaldehyde. From the fragmentation of derivatives of siphonaxanthin, such as the triacetate, the dimethyl ether and siphonaxanthol, and also from the fragmentation of related pigments, such as loroxanthin and fucoxanthin, the unique structural units responsible for the elimination of the carbon dioxide and carbon monoxide have been identified.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210050508
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Mass spectrometric comparison of ordinary and fully deuterated α- and β-carotene (1972)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1972), S. 843-851 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The individual, deuterated, isomeric α- and β-carotenes were isolated from the green alga, Scenedesmus obliquus, cultivated in D2O containing 99·7 to 99·8 atom percent deuterium. Mass spectroscopy showed that both the α- and β-deuterio-carotene preparations contained principally the fully deuterated pigment molecules (C40D56), small quantities of deuterated molecules with one proton (C40D55H) and yet smaller quantities of deuterated molecules with two protons (C40D54H2). From statistical calculations the deuterio-carotene preparations also contained one to several isotopically-substituted deuterio-carotenes of each mass in the mass range 585 to 599 because of variation of the number of 13C and H atoms per molecule. The mass fragmentation of the deuterated pigments was analogous to that of the respective ordinary α- and β-carotene. It indicated that the protons in the C40D55H and C40D54H2 molecules were distributed approximately randomly in various parts of the structure as in the terminal rings and in the ends and central portions of the polyene chain.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210060804
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  • 3
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    Implications of photometric and spectroscopic periods of SS433 (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: It is suggested that a comparison of the periodicities inferred from spectroscopic and photometric observations of SS433 may help clarify its structure. The interaction between the orbital and beam motions may produce sideband periods in the photometry. It is found that Lense-Thirring and slaved disk models make differing predictions.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 95; 2, Ma; Mar. 198
    Format: text
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  • 4
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    The bizarre spectrum of SS 433 (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Results are reported for extensive spectrophotometric observations, over the wavelength range from 3800 to 7800 A, of the peculiar 14th-mag emission-line object Stephenson-Sanduleak (SS) 433, which has been identified with a variable nonthermal radio source and is positionally coincident with the X-ray source A1909+04. It is found that the spectrum is dominated by intense variable Balmer and He I emission, that three of the He I lines have very prominent P Cygni profiles, and that virtually all the emission features undergo changes in equivalent width on a time scale of days. Anomalous emission features are described which consist of three previously unreported, very strong, broad emission lines at unfamiliar wavelengths in the green, red, and IR, and which vary nightly in intensity, profile, and wavelength. SS 433 is inferred to be a luminous object with an absolute visual magnitude of -3.1 or brighter.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 230
    Format: text
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  • 5
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    Yet another model of soft gamma repeaters (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-08-27
    Description: We develop a model of soft gamma repeaters (SGRs) in which a supernova leaves planets orbiting a neutron star in intersecting orbits. These planets will collide in approximately 10(exp 4) yr if their orbits are coplanar. Some fragments of debris lose their angular momentum in the collision and fall onto the neutron star, producing a SGR. The initial accretion of matter left by the collision with essntially no angular momentum may produce a superburst like that of 1979 March 5, while debris fragments which later lose their angular momentum produce an irregular but non-Poissonian pattern of smaller bursts resembling those observed in spectrum and duration.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 437; 2; p. 727-732
    Format: text
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