Search

We have studied the growth dynamics and electronic properties of SrTiO3-δ homoepitaxial films by pulsed laser deposition. We find that the two dominant factors determining the growth mode are the kinetics of surface crystallization and of oxidation. When matched, persistent two-dimensional layer-by-layer growth can be obtained for hundreds of unit cells. By tuning these kinetic factors, oxygen vacancies can be frozen in the film, allowing controlled, systematic doping across a metal-insulator transition. Metallic films can be grown, exhibiting Hall mobilities as high as 25 000 cm2/V s. [ABSTRACT FROM AUTHOR]

Presents information on an experimental study which performed magnetization and magnetoresistance measurements on lanthanum-strontium manganite (LSNO) thin films. Magnetoresistance of LSMO films; Origin of the anisotropy of the magnetoresistance in LSMO films.

Solidification and fluid flow analysis using computer simulation is a current common practice. There is also a high demand for thermal stress analysis in the casting process because casting engineers want to control the defects related to thermal stresses, such as large deformation and crack generation during casting. The riser system is an essential part of preventing the shrinkage defects in the casting process, and it has a great influence on thermal phenomena. The analysis domain is dramatically expanded by attaching the riser system to a casting product due to its large volume, and it makes FEM mesh generation difficult. However, it is difficult to study and solve the above proposed problem caused by riser system using traditional analysis methods which use single numerical method such as FEM or FDM. In this paper, some research information is presented on the effects of the riser system on thermal stress analysis using a FDM/FEM hybrid method in the casting process simulation. The results show the optimal conditions for stress analysis of the riser model in order to save computation time and memory resources. [ABSTRACT FROM AUTHOR]

The purpose of this phase I clinical trial was to evaluate the safety, tolerability and potential efficacy of VM202, naked DNA expressing two isoforms of hepatocyte growth factor, as an adjunct therapy to coronary artery bypass grafting (CABG) in patients with ischemic heart disease (IHD). Nine patients were assigned to receive increasing doses (0.5 to 2.0 mg) of VM202 injected into the right coronary artery (RCA) territory following completion of CABG for the left coronary artery territory. Patients were evaluated for safety and tolerability, and changes in myocardial functions were monitored via echocardiography, cardiac magnetic resonance imaging and myocardial single photon emission computed tomography throughout 6-month follow-up period. No serious complication related to VM202 was observed throughout the 6-month follow-up period. Global myocardial functions (wall motion score index, P=0.0084; stress perfusion, P=0.0002) improved during the follow-up period. In the RCA region, there was an increase in the stress perfusion (baseline vs 3-month, P=0.024; baseline vs 6-month, P=0.024) and also in the wall thickness of the diastolic and systolic phases. Intramyocardial injection of VM202 can be safely used in IHD patients with the tolerable dose of 2.0 mg. In addition, VM202 might appear to have improved regional myocardial perfusion and wall thickness in the injected region. [ABSTRACT FROM AUTHOR]

Recent technical advances in the atomic-scale synthesis of oxide heterostructures have provided a fertile new ground for creating novel states at their interfaces. Different symmetry constraints can be used to design structures exhibiting phenomena not found in the bulk constituents. A characteristic feature is the reconstruction of the charge, spin and orbital states at interfaces on the nanometre scale. Examples such as interface superconductivity, magneto-electric coupling, and the quantum Hall effect in oxide heterostructures are representative of the scientific and technological opportunities in this rapidly emerging field. [ABSTRACT FROM AUTHOR]

The Y-matrix of a three-port dual-mode ring resonator for a balun-bandpass filter (BPF) application is derived. Using Y parameters, it is verified that the structure theoretically satisfies the general balun conditions. The admittance slope parameters of the dual-mode ring resonator with one terminated port are derived so that one can design balun-BPFs using the conventional standard BPF design procedure. The proposed equations are validated by designing a balun-BPF. Inverters are then substituted with low-pass filter unit cells of λ/4 electrical length to suppress harmonics from the second to the fourth. The experimental measurements show good agreement with theoretical and electromagnetic-simulated predictions and suppressed harmonics below -30 dB up to fourth-order harmonics. [ABSTRACT FROM AUTHOR]

Polarity discontinuities at the interfaces between different crystalline materials (heterointerfaces) can lead to nontrivial local atomic and electronic structure, owing to the presence of dangling bonds and incomplete atomic coordinations. These discontinuities often arise in naturally layered oxide structures, such as the superconducting copper oxides and ferroelectric titanates, as well as in artificial thin film oxide heterostructures such as manganite tunnel junctions. If polarity discontinuities can be atomically controlled, unusual charge states that are inaccessible in bulk materials could be realized. Here we have examined a model interface between two insulating perovskite oxides-LaAlO3 and SrTiO3-in which we control the termination layer at the interface on an atomic scale. In the simple ionic limit, this interface presents an extra half electron or hole per two-dimensional unit cell, depending on the structure of the interface. The hole-doped interface is found to be insulating, whereas the electron-doped interface is conducting, with extremely high carrier mobility exceeding 10,000?cm2?V-1?s-1. At low temperature, dramatic magnetoresistance oscillations periodic with the inverse magnetic field are observed, indicating quantum transport. These results present a broad opportunity to tailor low-dimensional charge states by atomically engineered oxide heteroepitaxy. [ABSTRACT FROM AUTHOR]

The use of dual-stage gain-clamped erbium-doped fiber amplifier (GC–EDFA) having a pump laser diode and 16-channel wavelength-division multiplexing (WDM) of 0.8 nm spacing in the C-band of 1545–1560 nm wavelength was demonstrated in a burst packet-mode optical switching system through an experimental setup. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 316–319, 2002. [ABSTRACT FROM AUTHOR]

The use of a dual-stage gain-clamped erbium-doped fiber amplifier (GC–EDFA) having a pump laser diode and 16-channel wavelength-division multiplexing (WDM) with 0.8 nm spacing in the C-band of 1545–1560 nm wavelength was demonstrated in a burst packet-mode optical switching system through an experimental setup. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 167–170, 2002. [ABSTRACT FROM AUTHOR]

Heterostructures composed of perovskite overlayers on anatase TiO2 films were fabricated on LaAlO3 substrates. By depositing LaTiO3 and LaAlO3 thin films on the insulating anatase TiO2 films, metallic conduction was induced in the anatase layer with the increasing thickness of the perovskite overlayer. This perovskite overlayer deposition on TiO2 provides a method to induce free carriers, which may be applied to the development of transparent conducting oxides. [ABSTRACT FROM AUTHOR]

Strong effects of surface depletion have been observed in metallic La-doped SrTiO[sub 3] thin films grown on SrTiO[sub 3] substrates by pulsed-laser deposition. The depletion layer grows with decreasing temperature due to the large temperature-dependent dielectric response of SrTiO[sub 3]. When the depletion layer becomes comparable to or exceeds the thickness of the doped film, the Hall mobility shows significant enhancements as more of the electron distribution extends into the undoped substrate, in conceptual analogy to modulation doping in compound semiconductor heterostructures. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Describes research which showed that low-field grain-boundary magnetoresistance can be realized in a non-perovskite magnetoresistive oxide, the pyrochlore Tl2Mn2O7. Magnetoresistance in perovskite manganites and its limitations; Modification of manganites by tunnelling; Benefits and explanation of low-field response.

Presents research which observed low-field tunneling magnetoresistance in films of half-metallic CrO2 that were grown by high-pressure thermal decomposition of CrO3. High-temperature annealing treatments; Implications of research.

Presents an abstract of a study on doped LaMnO[sub3] with fixed carrier concentration. Relationship between the Curie temperature and the average ionic radius of the lanthanum site; Lattice effects on magnetoresistance; Result of microstructural changes induced by composition, temperature, and pressure variations.

Grating couplers are widely used optical interfaces in integrated photonics, especially on the Silicon-On-Insulator (SOI) platform. Their design has been optimized for coupling light between a Photonic Integrated Circuit (PIC) and a single-mode fiber, a μlens for free space transport, or even a second PIC in the same SOI platform. In this work, we co-design matching pairs of grating-couplers on distinct SOI and InP photonic platforms for optimized PIC-to-PIC coupling. By matching the scattering strengths of the two grating-couplers, we show that a PIC-to-PIC insertion loss of 3dB can be achieved. We also investigate how the design parameters impact the coupling efficiency and the bandwidth, ending up with a tolerance analysis. The proposed coupling approach between two different waveguide materials has prospective applications for the hybrid-integration of SOI and InP photonic platforms for communication technologies. [ABSTRACT FROM AUTHOR]

A correction to the article "A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface" that was published in the Number 427, 2004 issue is presented.