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| 2. |
- Carolipio, E. M., et al.
(författare)
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The toroidicity-induced Alfven eigenmode structure in DIII-D : Implications of soft x-ray and beam-ion loss data
- 2001
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 8:7, s. 3391-3401
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Tidskriftsartikel (refereegranskat)abstract
- The internal structure of the toroidicity-induced Alfven eigenmode (TAE) is studied by comparing soft x-ray profile and beam ion loss data taken during TAE activity in the DIII-D tokamak [W. W. Heidbrink , Nucl. Fusion 37, 1411 (1997)] with predictions from theories based on ideal magnetohydrodynamic (MHD), gyrofluid, and gyrokinetic models. The soft x-ray measurements indicate a centrally peaked eigenfunction, a feature which is closest to the gyrokinetic model's prediction. The beam ion losses are simulated using a guiding center code. In the simulations, the TAE eigenfunction calculated using the ideal MHD model acts as a perturbation to the equilibrium field. The predicted beam ion losses are an order of magnitude less than the observed similar to6%-8% losses at the peak experimental amplitude of deltaB(r)/B(0)similar or equal to2-5x10(-4).
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| 3. |
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| 4. |
- Fu, Q. X., et al.
(författare)
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Doped ceria-chloride composite electrolyte for intermediate temperature ceramic membrane fuel cells
- 2002
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Ingår i: Materials letters (General ed.). - 0167-577X .- 1873-4979. ; 53:3, s. 186-192
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Tidskriftsartikel (refereegranskat)abstract
- A kind of oxide-salt composite electrolyte, gadolinium-doped ceria (GDC)-LiCl-SrCl2, prepared with hot-press technique, shows superior ionic conductivity, which is 2-10 times higher than that of GDC itself at the temperature range of 400-600 degreesC. More interestingly, not like the GDC electrolyte, which has some extent of electronic conduction under reducing atmosphere, the composite electrolyte is almost a pure ionic conductor, evidenced by the fuel cell's (FC) open circuit voltage (OCV) close to the theoretical one. The fuel cells based on this composite electrolyte show excellent power density output even at temperature as low as 500 degreesC (240 mW cm(-2)) in spite of the relatively thick electrolyte (0.4 mm). Such high performance, in combination with its low cost in both raw materials and fabrication process, make this kind of composite electrolyte a good candidate electrolyte material for future ultra-low-cost intermediate temperature ceramic membrane fuel cells (IT-CMFCs).
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| 5. |
- Fu, Q. X., et al.
(författare)
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Intermediate temperature fuel cells based on doped ceria-LiCl-SrCl2 composite electrolyte
- 2002
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 104:1, s. 73-78
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Tidskriftsartikel (refereegranskat)abstract
- A new type of oxide-salt composite electrolyte, gadolinium-doped ceria (GDC)-LiCl-SrCl2, was developed and demonstrated its promising use for intermediate temperature (400-700 degreesC) fuel cells (ITFCs). The dc electrical conductivity of this composite electrolyte (0.09-0.13 S cm(-1) at 500-650 degreesC) was 3-10 times higher than that of the pure GDC electrolyte, indicating remarkable proton or oxygen ion conduction existing in the LiCl-SrCl2 chloride salts or at the interface between GDC and the chloride salts. Using this composite electrolyte, peak power densities of 260 and 510 mW cm(-2), with current densities of 650 and 1250 mA cm(-2) were achieved at 550 and 625 degreesC, respectively. This makes the new material a good candidate electrolyte for future low-cost ITFCs.
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| 6. |
- Fu, X, et al.
(författare)
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Oxytocin-induced oscillations of cytoplasmic Ca2+ in human myometrial cells.
- 2000
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - 0001-6349 .- 1600-0412. ; 79:3
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To investigate the mechanisms of oxytocin (OT) induced oscillations of the cytoplasmic Ca2+ concentration ([Ca2+]i) in cultured human myometrial cells.METHODS: [Ca2+]i was measured in individual myometrial cells by dual wavelength spectrophotofluorometry using the fluorescent indicator fura-2. Myometrium was obtained at abdominal hysterectomy (n=8) and during cesarean section (n=7).RESULTS: OT (10-300 nM) typically induced [Ca2+]i oscillations with frequencies in the 0.6-0.8/min range. There were no obvious differences in the responses of cells taken from non-pregnant and term pregnant women. The frequency and amplitude of the oscillations were not significantly affected by OT concentrations up to 300 nM. The amplitude of the oscillations decreased in the presence of the voltage-dependent Ca2+ channel antagonist verapamil and gradually disappeared in Ca2+-free medium. The oscillations were further blocked by the inorganic Ca2+ antagonist La3+ and by the intracellular Ca2+-ATPase inhibitor 2.5-di-tert-butylhydroquinone (DTBHQ). Caffeine inhibited the OT-induced oscillations in a concentration-dependent manner. DTBHQ and high concentrations of OT made [Ca2+]i remarkably sensitive to changes in the external Ca2+ concentration.CONCLUSIONS: The results indicate that OT-induced [Ca2+]i oscillations in human myometrial cells are due to inositol 1,4,5-trisphosphate-mediated release of intracellular Ca2+ combined with capacitative as well as voltage-dependent influx of the ion.
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| 7. |
- Fu, Y, et al.
(författare)
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Capacitance analysis for a metal-insulator-semiconductor structure with an ultra-thin oxide layer
- 2003
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Ingår i: Applied Physics A. - : Springer Science Business Media. - 0947-8396 .- 1432-0630. ; 76:1, s. 27-31
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Tidskriftsartikel (refereegranskat)abstract
- We have studied theoretically the capacitance characteristics of a metal-insulator-semiconductor structure with an ultra-thin oxide layer by self-consistently solving Schrodinger and Poisson equations. It is demonstrated that a diffused interface between Si and SiO2 results in a better agreement between the theoretical prediction of conduction current and experimental I-V data. The calculated steady-state capacitance, obtained both analytically and numerically, increases following the increase of the gate bias when the gate bias is small; it reaches a saturation value at intermediate gate bias. The capacitance decreases with increasing gate bias when the gate bias is rather large due to the depletion of the gate material. Simple analytical expressions for the gate capacitance are derived, based on quantum-mechanical considerations, for future device design. The steady-state capacitance of a metal-insulator-semiconductor structure with an oxide layer of 1.5-2.0 nm by state-of-the-art technology is 20 mF/m(2), while it is 40 mF/m(2) when the practical limit of SiO2 layer thickness, i.e. 10-12 Angstrom, is reached.
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| 8. |
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| 9. |
- Fu, Y, et al.
(författare)
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Electron mobilities, Hall factors, and scattering processes of n-type GaN epilayers studied by infrared reflection and Hall measurements
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 67:11
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the drift and Hall mobilities of electrons in metal-organic chemical-vapor-deposited wurtzite GaN thin films on sapphire substrate by infrared (IR) reflection and Hall measurements. By analyzing the Hall factor (the ratio between the drift mobility obtained from IR reflection spectra and the Hall mobility from the Hall measurements), it has been concluded that the electron mobility in GaN epilayer is determined by the ionized impurity when the electron concentration is low. At a high carrier concentration of 3.2x10(18) cm(-3), electronic states of more than 70 meV become populated taking into account the thermal excitation, so that the optical-phonon-scattering process becomes activated (the optical-phonon energy is 69.43 meV obtained from IR reflection measurements). Thus, in highly doped wurtzite GaN epilayers, ionized-impurity- and optical-phonon-scattering processes jointly determine the carrier transport properties.
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| 10. |
- Fu, Y, et al.
(författare)
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Formation and charge control of a quantum dot by etched trenches and multiple gates
- 2002
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Ingår i: Applied Physics A. - : Springer Science Business Media. - 0947-8396 .- 1432-0630. ; 74:6, s. 741-745
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated a GaAs/InGaAs/AlGaAs-based single-electron transistor (SET) formed by etched trenches and multiple gates. Clear Coulomb-blockade oscillations have been observed when the gate biases are scanned. By self-consistently solving three-dimensional Schrodinger and Poisson equations, we have studied the energy-band structure and the carrier distribution of our SET. General agreement between numerical simulation results and measurement data has been obtained, thus indicating the effectiveness of our SET-device design as well as the necessity of a complete three-dimensional quantum-mechanical simulation.
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