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Digitale Medien

Low energy electron attachment to SF6 in N2, Ar, and Xe buffer gases (1989)

Hunter, S. R. ; Carter, J. G. ; Christophorou, L. G.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 90 (1989), S. 4879-4891

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The electron attachment rate constants ka for SF6 have been measured in dilute mixtures of SF6 in high pressure (〉1 atm) N2, Ar, and Xe buffer gases at room temperature (T≈300 K) over a wide E/N range (electric field strength to gas number density ratio), corresponding to mean electron energies 〈ε〉 from near thermal electron energies (≈0.04 eV) to 〈ε〉≈4.3 eV. Particular attention has been paid to the effects of space charge distortion, molecular impurities, and changes in the electron energy distribution function on the measured electron attachment rate constant values at the lower E/N values in these mixtures. The present measured thermal electron attachment rate constants in SF6/N2 and SF6/Xe gas mixtures are in excellent agreement with recent accurate measurements of these parameters in several SF6/buffer gas mixtures. At higher 〈ε〉 values, the present SF6/N2 measurements are in fair agreement with previous measurements, while no previous measurements using Ar and Xe buffer gases have been published. These measurements have been used in numerical two term, spherical harmonic Boltzmann equation analyses of the electron motion in these gas mixtures to obtain the low energy (〈10 eV) nondissociative and dissociative electron attachment cross sections for SF6. The present derived electron attachment cross sections are compared with recently measured and derived nondissociative and dissociative electron attachment cross sections for SF6. The primary value of the present results is in the large and overlapping 〈ε〉 ranges of the present ka measurements for the three buffer gases compared with that for SF6/N2 gas mixtures alone, which in turn, makes these measurements ideal for testing cross-section sets in SF6 for use in many applied studies.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.456582

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Digitale Medien

Electron attachment and ionization coefficients and electron drift velocities in BF3 and SiF4 (1989)

Hunter, S. R. ; Carter, J. G. ; Christophorou, L. G.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 65 (1989), S. 1858-1865

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The drift velocity of electrons (w) in SiF4 and BF3 has been measured over the density-reduced electric field (E/N) range 0.5×10−17 V cm2 ≤E/N≤300×10−17 V cm2 using a pulsed Townsend experimental technique. The electron attachment (η/N) and ionization (α/N) coefficients have also been measured in SiF4 and BF3 over the E/N range 30×10−17 V cm2 ≤E/N≤300×10−17 V cm2 in the same experiment. The electron drift velocities in these two gases exhibit regions of negative differential conductivity (NDC) similar to but smaller in magnitude than those in CH4 and CF4 . The effective ionization coefficient (α¯/N) has been obtained from the η/N and α/N measurements in both gases, from which the high-voltage limiting electric field strengths (E/N)lim have been found to be 123×10−17 V cm2 for BF3 and 121×10−17 V cm2 for SiF4. The significance of these results in modeling gas discharges for a number of technological applications is indicated.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.342920

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Digitale Medien

Renal vein thrombosis and response to therapy in a newborn due to protein C deficiency (1989)

Rogers, P. C. J. ; Silva, M. P. ; Carter, J. E. J. ; [weitere]

Springer

European journal of pediatrics 149 (1989), S. 124-125

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ISSN: 1432-1076

Schlagwort(e): Neonatal ; Thrombosis ; Protein C ; Streptokinase

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract A newborn infant was diagnosed as having renal vein thrombosis due to heterozygous protein C deficiency and no other predisposing factor for thrombosis. He responded adequately to treatment with streptokinase, fresh frozen plasma and subsequent anticoagulation with heparin and warfarin (Coumadin). Four years from diagnosis he remains well with no recurrence of thrombosis and with normal renal function.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01995862

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Digitale Medien

An assessment of the bearing capacity of calcareous and silica sands (1989)

Yeung, S. K. ; Carter, J. P.

New York, NY [u.a.] : Wiley-Blackwell

International Journal for Numerical and Analytical Methods in Geomechanics 13 (1989), S. 19-36

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ISSN: 0363-9061

Schlagwort(e): Engineering ; Engineering General

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie

Notizen: A spherical cavity expansion model has been used to study the bearing capacity of foundations on calcareous and silica sands. Two constitutive models have been used to represent each sand: an elastoplastic, collapse-softening model, and a computationally simpler, elastic/perfectly plastic material. The predictions of the limit pressures for spherical cavity expansion are compared with laboratory data on the bearing capacities obtained from model footing tests. It is shown that the numerical predictions of the limit pressures correlate well with the experimental values of bearing capacity, particularly at higher effective overburden pressures.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/nag.1610130104

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Digitale Medien

Letters to the editor (1989)

Carter, J. P. ; Yeung, S. K. ; Kiousis, P. D. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

International Journal for Numerical and Analytical Methods in Geomechanics 13 (1989), S. 101-107

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ISSN: 0363-9061

Schlagwort(e): Engineering ; Engineering General

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/nag.1610130109

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