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Full-Text Articles in Physical Sciences and Mathematics
Nanoscale Oxide Patterns On Si (100) Surfaces, T. -C. Shen, C. Wang, J. W. Lyding, J. R. Tucker
Nanoscale Oxide Patterns On Si (100) Surfaces, T. -C. Shen, C. Wang, J. W. Lyding, J. R. Tucker
T. -C. Shen
Ultrathin oxide patterns of a linewidth of 50 Å have been created on Si(100)‐2×1 surfaces by a scanning tunneling microscope operating in ultrahigh vacuum. The oxide thickness is estimated to be 4–10 Å. The morphology and spectroscopy of the oxide region are obtained. Hydrogen passivation is used as an oxidation mask. The defects caused by oxidation in the passivated region before and after the hydrogen desorption are compared and discussed. The multistep silicon processings by an ultrahigh vacuum scanning tunneling micropscope is thus demonstrated.
Time Dependent Response Of Equatorial Ionospheric Electric Fieldsto Magnetospheric Disturbances, Bela G. Fejer, L. Scherliess
Time Dependent Response Of Equatorial Ionospheric Electric Fieldsto Magnetospheric Disturbances, Bela G. Fejer, L. Scherliess
Bela G. Fejer
We use extensive radar measurements of F region vertical plasma drifts and auroral electrojet indices to determine the storm time dependence of equatorial zonal electric fields. These disturbance drifts result from the prompt penetration of high latitude electric fields and from the dynamo action of storm time winds which produce largest perturbations a few hours after the onset of magnetic activity. The signatures of the equatorial disturbance electric fields change significantly depending on the relative contributions of these two components. The prompt electric field responses, with lifetimes of about one hour, are in excellent agreement with results from global convection …
Detection Of Dityrosine In Apoferritin, Stephen E. Bialkowski
Detection Of Dityrosine In Apoferritin, Stephen E. Bialkowski
Stephen E. Bialkowski
Laser-excited fluorescence spectroscopy was adopted for dityrosine detection in horse spleen apoferritin. Dityrosine was identified in horse spleen apoferritin. Fractionation of acid-hydrolyzed horse spleen apoferritin showed fluorescence attributed to dityrosine, and other compounds, excited by 325-nm laser radiation. The other fluorescent compounds resulted in a broad fluorescence emission spectrum of horse spleen apoferritin. The broad emission band overlapped with the fluorescence emission spectrum of pure dityrosine. Fractionation of horse spleen apoferritin acid hydrolysate prior to laser-excited fluorescence detection was necessary for dityrosine quantitative analysis. The concentration of dityrosine in horse spleen apoferritin was 2.5% (mol/mol), estimated from the method of …
Laser Excited Fluorescence Of Dityrosine, Sahar F. Mahmoud, Stephen E. Bialkowski
Laser Excited Fluorescence Of Dityrosine, Sahar F. Mahmoud, Stephen E. Bialkowski
Stephen E. Bialkowski
In this research, laser-excited fluorescence was examined for sensitive detection of aqueous dityrosine. Samples were excited with a 6.3-mW, 325-nm helium-cadmium laser focused into a small volume-fluorescence cell with a 10-cm lens. The resulting fluorescence emission was collected perpendicular to the excitation and detected with two different schemes. An optical bandpass filter was used with a photomultiplier tube for sensitive quantitative measurement, while a photodiode array detector was used in conjunction with a spectrograph for qualitative characterization of fluorescence emission spectra. Dityrosine detection on the order of 2 × 10-11 M was obtained with the use of the photomultiplier …
Global Equatorial Ionosphericvertical Plasma Drifts Measured By The Ae-E Satellite, Bela G. Fejer, E. R. De Paula, R. A. Heelis, W. B. Hanson
Global Equatorial Ionosphericvertical Plasma Drifts Measured By The Ae-E Satellite, Bela G. Fejer, E. R. De Paula, R. A. Heelis, W. B. Hanson
Bela G. Fejer
Ion drift meter observations from the Atmosphere Explorer E satellite during the period of January 1977 to December 1979 are used to study the dependence of equatorial (dip latitudes ≤ 7.5°) F region vertical plasma drifts (east-west electric fields) on solar activity, season, and longitude. The satellite-observed ion drifts show large day-to-day and seasonal variations. Solar cycle effects are most pronounced near the dusk sector with a large increase of the prereversal velocity enhancement from solar minimum to maximum. The diurnal, seasonal, and solar cycle dependence of the longitudinally averaged drifts are consistent with results from the Jicamarca radar except …