| 31. |
- Dong, G J, et al.
(författare)
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Super-Gaussian mirror for high-field-seeking molecules
- 2005
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 72:3
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Tidskriftsartikel (refereegranskat)abstract
- A matter wave mirror using a single, pulsed, super-Gaussian (SG) optical beam for specular reflection of neutral ground-state molecules is studied. The mirror has a high reflectivity close to 100% and nearly perfect specular reflection over a large incident angle. This mirror avoids the usual problems due to surface roughness and the van der Waals interactions that occur in conventional atomic mirrors. Further, it is capable of reflectance and transmittance with applications to velocity filtering and deceleration of cold molecules.
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| 32. |
- Fu, Ying, et al.
(författare)
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Nonperturbative dynamic photon absorption of quantum wells
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 99:10
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Tidskriftsartikel (refereegranskat)abstract
- Optical photoresponse of quantum wells in the nonperturbative regime has been studied by high-power and ultrafast-oscillating free-electron laser (FEL) experiments, which revealed a profound deviation of the nonlinear power from conventional perturbative multiple photon absorption processes. By combining the experimental and theoretical works we have shown that the nonperturbative solution of the time-dependent Schrodinger equation is essential to understand the experimental observations. Optical transitions of electrons are dynamic. One photon is absorbed or emitted when an electron transits from one electron state to the other. The rates of absorption and emission are proportional to the time interval in the femtosecond time scale. In the picosecond time scale, multiphoton processes emerge. The strong and fast-oscillating FEL source intensifies the dynamic photon absorption and emission processes in the quantum wells, resulting in a much enhanced nonlinearity in the photoresponse spectrum.
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| 33. |
- Gan, Lu, et al.
(författare)
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Capsid Conformational Sampling in HK97 Maturation Visualized by X-Ray Crystallography and Cryo-EM
- 2006
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 14:11, s. 1655-1665
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Tidskriftsartikel (refereegranskat)abstract
- Maturation of the bacteriophage HK97 capsid from a precursor (Prohead II) to the mature state (Head II) involves a 60 angstrom radial expansion. The mature particle is formed by 420 copies of the major capsid protein organized on a T = 7 laevo, lattice with each subunit covalently crosslinked to two neighbors. Well-characterized pH 4 expansion intermediates make HK97 valuable for investigating quaternary structural dynamics. Here, we use X-ray crystallography and cryo-EM to demonstrate that in the final transition in maturation (requiring neutral pH), pentons in Expansion Intermediate IV (EI-IV) reversibly sample 14 angstrom translations and 6 degrees rotations relative to a fixed hexon lattice. The limit of this trajectory corresponds to the Head II conformation that is secured at this extent only by the formation of the final class of covalent crosslinks. Mutants that cannot crosslink or EI-IV particles that have been rendered incapable of forming the final crosslink remain in the EI-IV state.
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| 34. |
- Hofmann, T., et al.
(författare)
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Anisotropy of the Γ-point effective mass and mobility in hexagonal InN
- 2006
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Ingår i: Physica Status Solidi. C, Current topics in solid state physics. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1610-1634 .- 1610-1642. ; 3:6, s. 1854-1857
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Tidskriftsartikel (refereegranskat)abstract
- We determine the anisotropic electron effective mass and mobility parameters in wurtzite InN thin films with free electron concentration Nfrom 1.8 × 1017 cm–3 to 9.5 × 1018 cm–3 using Infrared Magneto-optic Generalized Ellipsometry. The room-temperature measurements were carried out with magnetic fields up to 4.5 T. For the Γ-point we estimate m*⊥ = 0.047m0 and m*‖ = 0.039m0 for polarization perpendicular and parallel to the c -axis, respectively. Scattering by impurities or ionized donors may explain the decrease of mobility for polarization parallel to the c -axis from 1600 cm2/(Vs) to 800 cm2/(Vs) with increase in N , where the perpendicular mobility is further decreased, likely caused by additional grain boundary scattering.
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| 35. |
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| 36. |
- Hofmann, T., et al.
(författare)
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Optical hall effect in hexagonal InN
- 2008
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 37:5, s. 611-615
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the optical Hall effect in naturally doped high-quality wurtzite-structure InN thin films by generalized ellipsometry reveal that both the surface and the interior (bulk) free electron densities decrease with power-law dependencies on the film thickness. We discover a significant deviation between the bulk electron and dislocation densities. This difference is attributed here to the existence of surface defects with activation mechanism different from bulk dislocations and identifies the possible origin of the so far persistent natural n-type conductivity in InN. We further quantify the anisotropy of the Gamma-point effective mass.
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| 37. |
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| 38. |
- Jiang, Jun, et al.
(författare)
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An elongation method for first principle simulations of electronic structures and electron transport properties of finite nanostructures
- 2006
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 124:21, s. 214711-
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Tidskriftsartikel (refereegranskat)abstract
- An effective elongation method has been developed to study electronic structures and electron transport properties of nanoelectronic and bioelectronic devices at a hybrid density functional theory level. It enables to treat finite nanostructures consisting of as many as 28 000 electrons and has been successfully applied to sub-120-nm-long conjugated polymers, sub-60-nm-long single-walled carbon nanotubes, and 30 base-pair DNA molecules. The calculated current-voltage characteristics of different systems are found to be in good agreement with the experiments. Some unexpected behaviors of these nanosized devices have been discovered.
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| 39. |
- Jiang, Jun, et al.
(författare)
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First-principles simulations of inelastic electron tunneling spectroscopy of molecular electronic devices
- 2005
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 5:8, s. 1551-1555
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Tidskriftsartikel (refereegranskat)abstract
- Inelastic electron tunneling spectroscopy (IETS) is a powerful experimental tool for studying the molecular and metal contact geometries in molecular electronic devices. A first-principles computational method based on the hybrid density functional theory is developed to simulate the IETS of realistic molecular electronic devices. The calculated spectra of a real device with an octanedithiolate embedded between two gold contacts are in excellent agreement with recent experimental results. Strong temperature dependence of the experimental IETS spectra is also reproduced. It is shown that the IETS is extremely sensitive to the intramolecular conformation and the molecule-metal contact geometry changes. With the help of theoretical calculations, it has finally become possible to fully understand and assign the complicated experimental IETS and, more importantly, provide the structural information of the molecular electronic devices.
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| 40. |
- Joura, Elmar A., et al.
(författare)
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HPV antibody levels and clinical efficacy following administration of a prophylactic quadrivalent HPV vaccine
- 2008
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Ingår i: Vaccine. - : Elsevier BV. - 1873-2518 .- 0264-410X. ; 26:52, s. 6844-6851
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy of the quadrivalent Human Papillomavirus (HPV) vaccine is thought to be mediated by humoral immunity. We evaluated the correlation between quadrivalent HPV vaccine-induced serum anti-HPV responses and efficacy. 17,622 women were vaccinated at day 1, and months 2 and 6. At day I and at 6-12 months intervals for up to 48 months, subjects underwent Papanicolaou and genital HPV testing. No immune correlate of protection could be found due to low number of cases. Although 40% of vaccine subjects were anti-HPV 18 seronegative at end-of-study, efficacy against HPV 18-related disease remained high (98.4%; 95% CI: 90.5-100.0) despite high attack rates in the placebo group. These results suggest vaccine-induced protection via immune memory, or lower than detectable HPV 18 antibody titers. (C) 2008 Elsevier Ltd. All rights reserved.
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