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  • 1
    Electronic Resource
    Electronic Resource
    Effects of hydrogen bonding on the surface energy of ionic-neutral dodecyldimethylamine oxide micelles (1997)
    Springer
    Colloid & polymer science 106 (1997), S. 83-85 
    Details
    ISSN: 1435-1536
    Keywords: Dodecyldimethylamine oxide ; cmc ; surface energy ; hydrogen bond ; mixed micelle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We calculate the surface energy of a micelle consisting of neutral and ionized dodecyl-dimethylamine oxides (DAOs) by Monte Carlo simulation based on a lattice model of the micelle. We obtain the dependence of the surface energy on the fraction,α M, of ionized DDAO and show that the hydrogen bond between DDAOs plays a significant role in determining the properties of micelles. In particular, a conclusion is drawn that a DDAO molecule supports two hydrogen bonds. We also discuss the effects of the coexisting salt and temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189497
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    Paper (German National Licenses)
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  • 2
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    Possible Detection of an Emission Cyclotron Resonance Scattering Feature from the Accretion-Powered Pulsar 4U 1626-67 (2012)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present analysis of 4U 1626-67, a 7.7 s pulsar in a low-mass X-ray binary system, observed with the hard X-ray detector of the Japanese X-ray satellite Suzaku in 2006 March for a net exposure of ~88 ks. The source was detected at an average 10-60 keY flux of approx 4 x 10-10 erg / sq cm/ s. The phase-averaged spectrum is reproduced well by combining a negative and positive power-law times exponential cutoff (NPEX) model modified at approx 37 keY by a cyclotron resonance scattering feature (CRSF). The phase-resolved analysis shows that the spectra at the bright phases are well fit by the NPEX with CRSF model. On the other hand. the spectrum in the dim phase lacks the NPEX high-energy cutoff component, and the CRSF can be reproduced by either an emission or an absorption profile. When fitting the dim phase spectrum with the NPEX plus Gaussian model. we find that the feature is better described in terms of an emission rather than an absorption profile. The statistical significance of this result, evaluated by means of an F test, is between 2.91 x 10(exp -3) and 1.53 x 10(exp -5), taking into account the systematic errors in the background evaluation of HXD-PIN. We find that the emission profile is more feasible than the absorption one for comparing the physical parameters in other phases. Therefore, we have possibly detected an emission line at the cyclotron resonance energy in the dim phase.
    Keywords: Astronomy
    Type: GSFC.JA.7322.2012 , The Astrophysical Journal; 751; 1; 35
    Format: text
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  • 3
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    SN 2010ay is a Luminous and Broad-lined Type Ic Supernova within a Low-metallicity Host Galaxy (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: We report on our serendipitous pre-discovery detection and detailed follow-up of the broad-lined Type Ic supernova SN2010ay at z approx 0.067 imaged by the Pan-STARRS1 3pi survey just approx 4 days after explosion. Combining our photometric observations with those available in the literature, we estimate the explosion date and the peak luminosity of the SN, M(sub R) approximately equals 20.2 mag, significantly brighter than known GRB-SNe and one of the most luminous SNe Ibc ever discovered. We measure the photospheric expansion velocity of the explosion from our spectroscopic follow-up observations, v(sub ph) approximately equals 19.2 X 10 (exp 3) km/s at approx 40 days after explosion. In comparison with other broad-lined SNe, the characteristic velocity of SN2010ay is 2 - 5 X higher and similar to the measurements for GRB-SNe at comparable epochs. Moreover the velocity declines two times slower than other SNe Ic-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of Ni-56, M(sub Ni) = 0.9(+0.1/-0.1) solar mass. Our modeling of the light-curve points to a total ejecta mass, M(sub ej) approx 4.7 Solar Mass, and total kinetic energy, E(sub K,51) approximately equals 11. Thus the ratio of M(sub Ni) to M(sub ej) is at least twice as large for SN2010ay than in GRB-SNe and may indicate an additional energy reservoir. We also measure the metallicity (log(O/H) + 12 = 8.19) of the explosion site within the host galaxy using a high S/N optical spectrum. Our abundance measurement places this SN in the low-metallicity regime populated by GRB-SNe, and approx 0.2(0.5) dex lower than that typically measured for the host environments of normal (broad-lined) Ic supernovae. Despite striking similarities to the recent GRB-SN100316D/2010bh, we show that gamma-ray observations rule out an associated GRB with E(sub gamma) approx 〈 6 X 10(exp 48) erg (25-150 keV). Similarly, our deep radio follow-up observations with the Expanded Very Large Array rule out relativistic ejecta with energy, E approx 〉 10(exp 48) erg. These observations challenge the importance of progenitor metallicity for the production of a GRB, and suggest that other parameters also play a key role.
    Keywords: Astronomy
    Type: GSFC.JA.5904.2012
    Format: application/pdf
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