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  • 1
    Electronic Resource
    Electronic Resource
    Antimicrobial Agents From Higher Plants. Antimicrobial Agents From Peganum harmala Seeds (1981)
    s.l. : American Chemical Society
    Journal of natural products 44 (1981), S. 745-747 
    Details
    ISSN: 1520-6025
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/np50018a025
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  • 2
    Electronic Resource
    Electronic Resource
    Generation and evolution of interplanetary slow shocks (1996)
    Springer
    Annales geophysicae 14 (1996), S. 375-382 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract It is well known that most MHD shocks observed within 1 AU are MHD fast shocks. Only a very limited number of MHD slow shocks are observed within 1 AU. In order to understand why there are only a few MHD slow shocks observed within 1 AU, we use a one-dimensional, time-dependent MHD code with an adaptive grid to study the generation and evolution of interplanetary slow shocks (ISS) in the solar wind. Results show that a negative, nearly square-wave perturbation will generate a pair of slow shocks (a forward and a reverse slow shock). In addition, the forward and the reverse slow shocks can pass through each other without destroying their characteristics, but the propagating speeds for both shocks are decreased. A positive, square-wave perturbation will generate both slow and fast shocks. When a forward slow shock (FSS) propagates behind a forward fast shock (FFS), the former experiences a decreasing Mach number. In addition, the FSS always disappears within a distance of 150R⊙ (where R⊙ is one solar radius) from the Sun when there is a forward fast shock (with Mach number \geq1.7) propagating in front of the FSS. In all tests that we have performed, we have not discovered that the FSS (or reverse slow shock) evolves into a FFS (or reverse fast shock). Thus, we do not confirm the FSS-FFS evolution as suggested by Whang (1987).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-0375-1
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  • 3
    Electronic Resource
    Electronic Resource
    Three-dimensional MHD simulation of interplanetary magnetic field changes at 1 AU as a consequence of simulated solar flares (1996)
    Springer
    Annales geophysicae 14 (1996), S. 383-399 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A fully three-dimensional (3D), time-dependent, MHD interplanetary global model (3D IGM) has been used, for the first time, to study the relationship between different forms of solar activity and transient variations of the north-south component, Bz, of the interplanetary magnetic field (IMF) at 1 AU. One form of solar activity, the flare, is simulated by using a pressure pulse at different locations near the solar surface and observing the simulated IMF evolution of B〈theta〉 (=-Bz) at 1 AU. Results show that, for a given pressure pulse, the orientation of the corresponding transient variation of Bz has a strong relationship to the location of the pressure pulse and the initial conditions of the IMF. Two initial IMF conditions are considered: a unipolar Archimedean spiral with outward polarity and a flat heliospheric current sheet (HCS) with outward polarity in the northern hemisphere and which gradually reverses polarity in the solar equatorial plane to inward polarity in the southern heliospheric hemisphere. The wave guide effect of the HCS is also demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-0383-1
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental characterization of a thermionic-arc discharge ionization device for flowing gases (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 91-97 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The working characteristic of a new hollow cathode, thermionic-arc dc discharge ionization device was investigated experimentally. Under typical operating conditions the device produces a steady, field-free plasma plume by ionizing a flowing gas column. Experiments were performed with argon, nitrogen, and helium, the typical discharge pressures being 0.2–0.6 Torr. The discharge exploits the inherent stability of the point to plane geometry and the ionization efficiency of the hollow cathode. Electrically, the discharge is fed from a constant–voltage power supply and maintained below the interelectrode gap breakdown threshold. Thus the discharge current is given by Ohm's law and is a function of the applied field and local plasma parameters. This modus operandi increases the ionization efficiency by maintaining a local thermal nonequilibrium in the discharge. The degree of nonequilibrium maintained in the plume downstream the cathode was higher in nitrogen (Te/Tgas≅8–10) than in argon (Te/Tgas≅3–4), and is attributed to a lower collision frequency in the nitrogen plume. At an input power level of 0.9 kW plasmas with electron densities of 1017 part/m3 in nitrogen and 1018 part/m3 in argon were recorded in the plume outside the high-field cathode region. Helium discharge displayed the highest nonequilibrium level (Te/Tgas≅100) but at the same time showed the largest degree of instability and the lowest electron density levels 1015 part/m3. The experiments indicate that the stability and the ionization efficiency of the discharge are enhanced by a supersonic flow field. Flow surveys have shown that the more stable argon and nitrogen plumes were slightly supersonic in the range of pressure investigated while helium flow remained subsonic throughout. The important consequence to the supersonic flow is the development of a normal shock in front of the cathode filament. Analysis of the data indicates that the normal shock is an effective stabilizing boundary. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1427415
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  • 5
    Electronic Resource
    Electronic Resource
    Alloying and post-heat-treatment of thermal-sprayed coatings of self-fluxing alloys
    Amsterdam : Elsevier
    Surface & Coatings Technology 58 (1993), S. 73-77 
    Details
    ISSN: 0257-8972
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0257-8972(93)90176-O
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  • 6
    Electronic Resource
    Electronic Resource
    The virial coefficients for argon atoms adsorbed on xenon-plated graphite
    Amsterdam : Elsevier
    Surface Science 41 (1974), S. 475-482 
    Details
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0039-6028(74)90063-6
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  • 7
    Electronic Resource
    Electronic Resource
    Mixing energies of nickel atoms and vacancies in Ni-Te
    Amsterdam : Elsevier
    Solid State Communications 28 (1978), S. 413-414 
    Details
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1098(78)90425-8
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  • 8
    Electronic Resource
    Electronic Resource
    Partial analysis of the flare-prominence of 30 April 1974 (1975)
    Springer
    Solar physics 44 (1975), S. 117-133 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A portion of an east limb flare-prominence observed in Hα by NOAA/Boulder and NASA/ MSFC patrol facilities on 30 April 1974 is analyzed. Following a rapid (∼2 min) achievement of a maximum mass ejection velocity of about 375 km s−1, the ascending prominence reached a height of, at least, 2 × 105 km. We use a one-dimensional, time-dependent hydrodynamic theory (Nakagawa et al., 1975) to compute the total mass (∼2 × 1011 g) and energy (∼4 × 1026erg) ejected during this part of this event. Theoretical aspects of the coronal response are discussed. We conclude that a moderate temperature and density pulse (factors of ten and two, respectively), for a duration of only 3 min, is sufficient for an acceptable simulation of the Hα observations and the likely coronal response to the ascending prominence and flare-related ejections. No attempt was made to simulate the additionally-important spray and surge features which probably contributed a higher level of mass and energy efflux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156850
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  • 9
    Electronic Resource
    Electronic Resource
    Dynamic response of an isothermal static corona to finite-amplitude disturbances (1975)
    Springer
    Solar physics 41 (1975), S. 387-396 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The velocity evolution of sprays, surges and fast ejections is characterized by a rapid acceleration followed by a slowdown. In contrast, eruptive prominences show a velocity evolution with a slow increase followed by a rapid acceleration. We examine the physical causes which differentiate these two characteristic velocity evolutions, and study the dynamic responses of the solar corona. For simplicity, the ascending disturbances are modelled as purely radial adiabatic flows caused by finite-amplitude perturbations (pulses) in an initially isothermal, static corona. It is shown that the resultant flow depends strongly on the nature of the disturbing causes. In particular, the coronal response to sprays and fast ejections can be identified with temperature and velocity pulses at the bottom of the corona, with surges related to shorter pulses, while the slow moving eruptive prominences are correlated with density pulses. It is shown that for large flare sprays 5 × 1039 particles can be injected into the solar wind.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00154076
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  • 10
    Electronic Resource
    Electronic Resource
    On build-up of magnetic energy in the solar atmosphere (1976)
    Springer
    Solar physics 47 (1976), S. 193-203 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamic response of the solar atmosphere is examined with the use of self-consistent numerical solutions of the complete set of nonlinear, two-dimensional, hydromagnetic equations. Of particular interest are the magnetic energy build-up and the velocity field established by emerging flux at the base of an existing magnetic loop structure in a stationary atmosphere. For a plasma with a relatively low beta (β = 0.03) the magnetic energy build-up is approximately twice that of the kinetic energy, while the build-up in magnetic energy first exceeds but is eventually overtaken by the kinetic energy for a plasma with an intermediate beta (β = 3). The increased magnetic flux causes the plasma to flow upward near the loop center and downward near the loop edges for the low beta plasma. The plasma eventually flows downward throughout the lower portion of the loop carrying the magnetic field with it for the intermediate beta plasma. It is hypothesized that this latter case, and possibly the other case as well, may provide a reasonable simulation of the disappearance of prominences by flowing down into the chromosphere (a form of disparition brusque).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152256
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