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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 548-554 
    ISSN: 0935-6304
    Keywords: Gas liquid chromatography (GLC) ; Fused silica capillary columns ; Alkali flame ionization detection (AFID) ; Mass spectrometry (MS) ; Quantitation in human serum ; Ethylenediamine ; Aminophylline ; Small molecular weight amines and diamines ; m-Toluoyl derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A specific and sensitive method for the determination of ethylenediamine in human plasma is described. The aqueous sample is treated with m-toluoyl chloride, yielding the N,N′-bis(m-toluoyl) derivative of the diamine, which is extracted into dichloromethane and quantitated after “on column” methylation by capillary gas liquid chromatography with alkali flame ionization detection. The corresponding derivative of putrescine serves as internal standard. The assay is reproducible and calibration curves are linear over the concentration range 0.05 to 10 μg · ml-1. The lower detection limit is about 10 ng · ml-1. The structures of the compounds of interest eluting from the capillary column are examined by gas liquid chromatography/mass spectrometry. The assay has been applied to the analysis of ethylenediamine in plasma following the administration of aminophylline and ethylenediamine in a cross-over study to patients with bronchopulmonary diseases. The method also proves suitable for measuring other primary and secondary amines and diamines in aqueous solutions by gas liquid chromatography.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: IR and Raman spectra of Zn(OH)F, β-Zn(OH)Cl and isostructural Ca(OH)Cl and Cd(OH)Cl and of deuterated specimens recorded at ambient and liquid nitrogen temperature are presented and assigned to OH(OD) stretching, librational and translational modes. The spectra obtained are discussed on the basis of the layered crystal structures of these hydroxide halides. The main results are (i) detection and proof of the presence of very weak hydrogen bonds in the case of M(OH)Cl (M = Ca, Cd) and for OH(2) of Zn(OH)F [in addition to ordinary hydrogen bonds in the case of β-Zn(OH)Cl and OH(1) of Zn(OH)F] with OH stretching wavenumbers of the corresponding hydroxide ions partially greater than that of free, gaseous OH- ions, (ii) a less symmetrical structure of Ca(OH)Cl and Cd(OH)Cl compared with that obtained from the heavy atoms alone and (iii) proof of the presence of two different kinds of hydroxide ions in nearly equal amounts in Zn(OH)F containing two lattice sites each occupied by F- and OH-. The high-energy shift of the OH modes mentioned above is attributed to the synergetic effect.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 3
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: Analytic approximations and numerical simulations are used to derive the characteristic behavior of star counts in a galactic spheroidal population, whose visible stars' stellar luminosity function is obtainable for galactocentric distances between about 4 and 12 kpc from star count observations above 30 deg galactic latitude. The total densities of stars and of mass in the spheroid at the solar position are evaluated using different assumed luminosity functions, in order to extrapolate the measured values to a wider range of absolute magnitudes. The upper limits to the frequency of intermediate population stars are derived for the absolute visual magnitude range of 5-8. If such stars occur in either a flat disk with a scale height of 3 kpc or a spheroid with an ellipticity of 0.5, their local surface density is less than 1.8 times that of the spheroid.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 265
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  • 4
    Publication Date: 2019-06-27
    Description: The paper deals with the spectra of six quasars, ranging in redshift from 0.23 to 2.04, obtained with the 45-cm telescope mounted on the IUE satellite. The average emission-line intensity ratio for L-alpha to H beta and the detection of higher-order Lyman emission lines in two objects are found to be inconsistent with a simple optically thick recombination model. The Lyman and Balmer line velocity profiles are identical. The emission lines in 3C 351 can be decomposed into sharp and broad components, with the sharp lines consistent with the recombination model.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 5
    Publication Date: 2019-06-28
    Description: Attention is given to the spectral energy distributions of nine high-redshift quasars between 1250 and 10,000 A. The distributions steepen shortward of about 1200 A in all but one object. The steepening's lack of correlation with QSO luminosity suggests that it arises from absorption by intervening material along the line of sight. Reddening may contribute to the steepening of the QSO continua, if dust lies along the line of sight to the continuum source, and is difficult to assess quantitatively. In QSOs with redshift sufficiently high for Lyman-alpha to be observed at high resolution, it is possible to account for the observed continuum steepening by the Lyman continuum absorption corresponding to the narrow Lyman-alpha absorption lines seen.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 76-89
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  • 6
    Publication Date: 2019-06-27
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 217
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  • 7
    Publication Date: 2019-08-27
    Description: We report preliminary results from a program to identify optical counterparts of ROSAT sources in the North Ecliptic Pole (NEP) region. The most striking X-ray feature reported by Hasinger et al. (1991) is an extended low surface brightness region of X-ray emission. Within the two X-ray contours of highest count rate we find a cluster of galaxies at a redshift of 0.09 and an early-type galaxy at a redshift of 0.03. X-ray emission from these objects may provide an explanation for the observed X-ray morphology. We also find evidence that other X-ray sources in this region are coincident with clusters or groups of galaxies at redshifts between 0.08 and 0.09. The presence of at least five X-ray detected clusters or groups in this narrow redshift band within a 1.5 deg radius field seems to indicate the existence of a moderate redshift supercluster. The existence of these clusters will have major implications for the study of large-scale structure through X-ray surveys such as ROSAT.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 259; 1; p. L9-L11.
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  • 8
    Publication Date: 2019-07-12
    Description: Images of the gravitational lens 2237+0305 acquired in good seeing have resolved the system into at least five components within the central few arsec of the object: the galaxy nucleus and four point sources in a ringlike formation approximately centered on the galaxy. It is found that the four point sources are distinctly bluer than the galaxy, but that they do not have identical colors. The observed configuration is well reproduced by a simple model that assumes that the four objects are images of the quasar and that the lens is a constant mass-to-light ratio, elliptical, de Vaucouleurs bulge.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1619-162
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  • 9
    Publication Date: 2019-07-12
    Description: Moderate-resolution slit spectroscopy of the extended emission-line objects A1 and B1 located within 5 arcsec of the triple radio source 2016 + 112 shows that at least one is physically associated with the z = 3.273 quasar thought to be multiply imaged by a foreground galaxy. The data and theoretical models unanimously favor the identification of A1 and B1 with two separate clouds of ionized gas that lie within a few kiloparsecs of the primary A/B QSO and radio source. The available evidence does not support the view that they are multiple images of a single object or their classification as separate (companion) galaxies.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 94; 12-15
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  • 10
    Publication Date: 2019-07-12
    Description: A survey for faint quasars has been conducted using slitless spectroscopy with the PFUEI at the 200 inch (5 m) telescope. The survey covers a total of 0.91 sq deg in 113 fields at galactic latitudes above 30 deg. Calibrated spectra in the range 4500-7200 A were obtained for more than 9000 objects. Emission-line candidates were selected on the basis of two criteria: the equivalent width must exceed 50 A, and the signal-to-noise ratio of the detection of the line versus the sky background should be larger than 7. Among 45 candidates so selected, subsequent slit spectroscopy confirmed 27 emission-line objects. Among these, 17 are emission-line galaxies with redshifts in the range 0.04-0.31, and 10 are quasars with redshifts between 0.91 and 2.66. The well-defined selection criteria for these objects, together with the distribution of rest frame equivalent widths of the emission lines, allow derivation of the area of sky covered as a function of the continuum limiting magnitude. The observed number of quasars in the redshift range 0.7-2.7 agrees well with that predicted by the luminosity function models published by Schmidt and Green in 1983. It is concluded that quasars with an absolute magnitude of M(B) = -25 suffer a redshift cutoff near or below a redshift of 3.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 306; 411-427
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