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  • 1
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    An implosive seismoacoustic source for seismic experiments on the ocean floor (1998)
    Springer
    In:  Marine Geophysical Researches, 20 (3). pp. 239-247.
    Details
    Publication Date: 2018-02-08
    Description: Bottom shots have been used for a number of years in seismic studies on the ocean floor. Most experiments utilized explosives as the energy source, though researchers have recognized the usefulness of collapsing water voids to produce seismoacoustic signals. Implosive sources, however, suffered generally from a lack of control of source depth. We present a new experimental tool, called SEEBOSEIS, to carry out seismic experiments on the seafloor utilizing hollow glass spheres as controlled implosive sources. The source is a 10-inch BENTHOS float with penetrator. Inside the sphere we place a small explosive charge (two detonators) to destabilize the glass wall. The time of detonation is controlled by an external shooting device. Test measurements on the Ninetyeast Ridge, Indian Ocean, show that the implosive sources can be used in seismic refraction experiments to image the subbottom P- wave velocity structure in detail beyond that possible with traditional marine seismic techniques. Additionally, the implosions permit the efficient generation of dispersed Scholte waves, revealing upper crustal S-wave velocities. The frequency band of seismic energy ranges from less than 1 Hz for Scholte modes up to 1000 Hz for diving P-waves. Therefore, broadband recording units with sampling rates 〉2000 Hz are recommended to sample the entire wave field radiated by implosive sources.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1023/A:1004552406168
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
    Electronic Resource
    Electronic Resource
    Lattice dynamics and hyperfine interactions of C60Fe(CO)4 (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 7-10 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Detailed 57Fe Mossbauer experiments over the range 85〈T〈210 K have been carried out on the tetra-carbonyl iron derivative of C60(I) as well as on several related organometallic solids. The observed isomer shift and quadrupole splitting parameters are consistent with a bonding interaction between the metal center and the ligand which involves a single carbon–carbon double bond of the buckminsterfullerene. The temperature dependence of the recoil-free fraction, compared to analogous data for maleic anhydride Fe(CO)4(II), suggests that the two previously observed low frequency lattice modes in C60 persist in I. Contrary to expectations, there is no significant temperature-dependent vibrational anisotropy (Gol'danskii–Karyagin effect) evident in the above temperature range. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470869
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Mössbauer studies related to the solid-state dynamics of C60 (1996)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 18 (1996), S. 227-230 
    Details
    ISSN: 0392-6737
    Keywords: Mössbauer spectra ; Mössbauer effect ; other γ-ray spectroscopy ; Crystalline state (including molecular motions in solids) ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary C60 (Buckminsterfullerene) is isolated from organic solvents above 260 K as an f.c.c. solid with complete orientational disorder. The rotational dynamics are diffuse and isotropic, with a short (12 ps) correlation time at 300 K. Below 260 K, the solid forms in a simple cubic lattice withPa3 symmetry. The librational motion occurs by activated jumps with a correlation time of about 60 ns at 200 K. To gain further insight into the dynamics of C60, the compound C60Fe(CO)4 (I) (generously made available to us by A. Stephens and M. Green of Oxford University) has been studied by57Fe Mössbauer spectroscopy. As expected, the resonance at 90 K consists of a doublet with an isomer shift (relative to metallic iron) of 0.034(1) mm s−1 and a quadrupole splitting of 1.607(5) mm s−1. There is no significant temperature-dependent, intensity asymmetry of the doublet. The temperature dependence of the effect magnitude is well fit by a linear regression over the range 85〈T〈210 K. To elucidate the relationship of these results to the effect of the C60 moiety in I, further lattice dynamical Mössbauer studies have been carried out on (maleic anhydride) Fe(CO)4 (II), one of the few isolatable tetracarbonyl complexes of iron. For (II), the quadrupole splitting is 1.371(5) mm s−1 at 90 K, and the temperature, dependence of the isomer shift is smaller than it is for (I), while the temperature dependence of the recoil-free fraction is significantly larger in (I) than in (II).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458895
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  • 4
    Electronic Resource
    Electronic Resource
    Occupational exposure to antineoplastic agents and parameters for renal dysfunction (1997)
    Springer
    International archives of occupational and environmental health 69 (1997), S. 215-218 
    Details
    ISSN: 1432-1246
    Keywords: Key words Antineoplastic agents ; Occupational exposure ; Hospital workers ; Nephrotoxicity ; Retinol-binding protein ; Albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To study the nephrotoxic effects of occupational exposure to antineoplastic agents, the early renal effect parameters retinol-binding protein (RBP) and albumin (ALB) were determined in the urine of 11 hospital workers involved in the preparation and administration of antineoplastic agents and in 23 hospital workers not involved in drug handling, who served as nonexposed controls. No significant difference was found between the exposed group and the nonexposed control group with respect to the early renal effect parameters RBP and ALB. Although it was demonstrated that the hospital workers were exposed to cyclophosphamide (CP) and probably other antineoplastc agents, the results of the present study show that these exposure levels did not cause nephrotoxic effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004200050139
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  • 5
    Electronic Resource
    Electronic Resource
    Critical evaluation and review of cadmium concentrations in blood for use in occupational health according to the TRACY protocol (1997)
    Springer
    International archives of occupational and environmental health 69 (1997), S. 372-378 
    Details
    ISSN: 1432-1246
    Keywords: Key words Blood ; Cadmium ; Reference intervals ; Occupational health
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Cadmium in blood (B-Cd) may be used to assess recent exposure to cadmium in the working or general environment. In a paper published elsewhere pooled reference values using meta-analysis of B-Cd values in general-population studies were calculated. In the present study tentative reference intervals were described which can be used for comparison with data from occupationally exposed groups or individuals. The selection of studies was done according to criteria as published by the international project TRACY. For this purpose, 800 publications covering the period 1983–1992 were reviewed on their suitability for establishing tentative reference intervals. From these 800 publications, four finally met the selection criteria. Most important criteria for selection were the check for contamination during sampling of the blood, the storage and pretreatment procedures, and the existence of internal and external quality control programs. Also, stratifications into sex, smoking habits and occupation were important selection criteria. It turned out that for non-smoking white-collar workers in the age range of 19–65 years, B-Cd values were below 0.8 μg/l for most areas. All other groups within this age group, e.g., white collar workers in Japan, blue-collar workers, and smokers tend to have higher B-Cd values in these sequences. Blue-collar workers not clearly exposed to Cd have higher values than white-collar workers, indicating still some minor exposure. It is not clear if this small exposure has an occupational or lifestyle (e.g., diet) origin. Geographic regions also show an influence on B-Cd levels, e.g., values in Japan are higher than elsewhere. This influence may be due to differences in diet. The conclusion will be that reference values for B-Cd in fact are area-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004200050163
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Relationship between Shot-Induced Noise and Shot Interval in Seismic Refraction Experiments at Sea (1997)
    Springer
    Marine geophysical researches 19 (1997), S. 257-265 
    Details
    ISSN: 1573-0581
    Keywords: Shot-induced noise ; shot interval ; seismic refraction ; S/N ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Seismic noise induced by the seismic source during continuous profiling reduces the signal-to-noise ratio and hence the data quality. This noise is largely dependent on the shot interval. In this paper, the noise amplitude of refraction seismic records from a special experiment is analysed as a function of the shot interval. An empirical exponential relationship between mean peak noise amplitude and shot interval is deduced. By increasing the shot interval, the induced noise can be minimized on all successive records. This results in an improvement of the data, predominantly the signal-to-noise ratio. Because the seismic signal and the shot-induced noise have nearly the same spectra, the chance of improving the signal-to-noise ratio by stacking is significantly reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004227027730
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    An implosive seismoacoustic source for seismic experiments on the ocean floor (1998)
    Springer
    Marine geophysical researches 20 (1998), S. 239-247 
    Details
    ISSN: 1573-0581
    Keywords: bottom shots ; implosive sources ; P-waves ; Scholte waves ; seismic velocities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Bottom shots have been used for a number of years in seismic studies on the ocean floor. Most experiments utilized explosives as the energy source, though researchers have recognized the usefulness of collapsing water voids to produce seismoacoustic signals. Implosive sources, however, suffered generally from a lack of control of source depth. We present a new experimental tool, called SEEBOSEIS, to carry out seismic experiments on the seafloor utilizing hollow glass spheres as controlled implosive sources. The source is a 10-inch BENTHOS float with penetrator. Inside the sphere we place a small explosive charge (two detonators) to destabilize the glass wall. The time of detonation is controlled by an external shooting device. Test measurements on the Ninetyeast Ridge, Indian Ocean, show that the implosive sources can be used in seismic refraction experiments to image the subbottom P-wave velocity structure in detail beyond that possible with traditional marine seismic techniques. Additionally, the implosions permit the efficient generation of dispersed Scholte waves, revealing upper crustal S-wave velocities. The frequency band of seismic energy ranges from less than 1 Hz for Scholte modes up to 1000 Hz for diving P-waves. Therefore, broadband recording units with sampling rates 〉2000 Hz are recommended to sample the entire wave field radiated by implosive sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004552406168
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
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