Effect of multilayer barriers on the optical properties of GaInNAs single quantum-well structures grown by metalorganic vapor phase epitaxy

We report on the effects of combined strain-compensating and strain-mediating layers of various widths on the optical properties of 1.3 μm GaInNAs∕GaAs single quantum well structures grown by metalorganic vapor phase epitaxy (MOVPE). While the emission wavelength of GaInNAs∕GaAs quantum wells can be redshifted by the adoption of strain-compensated GaNAs layers, the material quality is degraded by the increased stress at the well∕barrier interface. This detrimental effect can be cured by inserting a strain-mediating InGaAs layer between them. Contrary to what is expected, however, the emission wavelength is blueshifted by the insertion of the InGaAs layer, which is attributed to the reduced N incorporation due to the improved interface quality. Our results indicate that the optical properties of MOVPE-grown GaInNAs∕GaAs quantum wells can be optimized in quantum efficiency and emission wavelength by combination of strain-compensating and strain-mediating layers with suitable characteristics

Long-term starin monitoring data of jacket-type offshore structure for tidal current power generation under severe tidal current environments

Structural strain responses of the jacket-type Uldolmok tidal current power plant structure under severe\ud tidal environments were analyzed using long-term measurement data from construction to normal operation. From the\ud measured data during construction, it was found that there were significant changes in strain responses at the steps of\ud jacket lifting, weight-block loading, pile ejection and insertion. Strains due to permanent and tidal current loads were\ud analyzed during removal work on one among six jacket legs, and it was found that the strains due to permanent load\ud were much significantly changed after removal of on jacket leg. From the measurement data during normal operation, it\ud was observed that strain responses were obviously fluctuated with M2 and M4 tidal periods and also with relatively\ud short period of about 11 min due to the peculiar tidal characteristics in the Uldolmok strait

Spectroscopic characterization of 1.3µm GaInNAs quantum-well structures grown by metal-organic vapor phase epitaxy

We report optical studies of high-quality 1.3 μm strain-compensated GaInNAs/GaAs single-quantum-well structures grown by metalorganic vapor phase epitaxy. Photoluminescence excitation (PLE) spectroscopy shows clearly the electronic structure of the two-dimensional quantum well. The transition energies between quantized states of the electrons and holes are in agreement with theoretical calculations based on the band anti-crossing model in which the localized N states interact with the extended states in the conduction band. We also investigated the polarization properties of the luminescence by polarized edge-emission measurements. Luminescence bands with different polarization characters arising from the electron to heavy-hole and light-hole transitions, respectively, have been identified and verify the transition assignment observed in the PLE spectrum

Genetic diversity of Legionella pneumophila inferred from rpoB and dotA sequences

ABSTRACTThis study characterised the population structure of Legionella pneumophila by comparing the rpoB (300-bp) and dotA (360-bp) sequences of 267 isolates (18 reference strains, 149 Korean isolates and 100 Japanese isolates). In addition to the six clonal subgroups established previously, four subgroups, P-V to P-VIII, were identified. Subgroupings based on rpoB and dotA sequences were found to correlate with the source of the isolates, and this data may be useful for future epidemiological studies. Fourteen (five Korean and nine Japanese) isolates showed incongruent subgroupings in the rpoB and dotA trees, suggesting that genetic exchange among subgroups, and even among subspecies, may occur frequently in nature

Transient response analysis of a submerged floating tunnel under seismic and wave excitations

In this study, a numerical procedure is described for the transient response analysis of a submerged\ud floating tunnel with reference of a designed tunnel in Japan. Tension legs seizing the tunnel are simply modeled by a\ud spring elements and the tunnel itself is assumed by two rigid bodies between which a flexible joint is used. A recorded\ud seismic excitation is used while the wave load is calculated under a specific design condition. Hydro-damping and\ud added mass are considered for numerically modeling the underwater condition. A numerical procedure is validated with\ud compared to the previous results of the designed tunnel. Some modifications are proposed through the validating\ud process in terms of modeling and analysis procedure. Eventually, the modified numerical procedure will be used in\ud analyzing the transient response of a newly designed tunnel

Time and Amplitude of Afterpulse Measured with a Large Size Photomultiplier Tube

We have studied the afterpulse of a hemispherical photomultiplier tube for an upcoming reactor neutrino experiment. The timing, the amplitude, and the rate of the afterpulse for a 10 inch photomultiplier tube were measured with a 400 MHz FADC up to 16 \ms time window after the initial signal generated by an LED light pulse. The time and amplitude correlation of the afterpulse shows several distinctive groups. We describe the dependencies of the afterpulse on the applied high voltage and the amplitude of the main light pulse. The present data could shed light upon the general mechanism of the afterpulse.Comment: 11 figure

Effect of protease on growth performance and carcass characteristics of growing-finishing pigs

No Abstrac

Single-filament Composite MgB2/SUS Ribbons by Powder-In-Tube Process

We report the successful fabrication of single-filament composite MgB2/SUS ribbons, as an ultra-robust conductor type, employing the powder-in-tube (PIT) process, by swaging and cold rolling only. The remarkable transport critical current (Ic) of the non-sintered MgB2/SUS ribbon has observed, as an unexpected result. Transport critical currents Ic ~ 316 A at T = 4.2 K and Ic ~ 82 A at T = 20 K were observed at self-field, for the non-sintered composite MgB2/SUS ribbon. In addition, the persistent current density Jp values, that were estimated by Bean formula, were more than ~ 7  105 A/cm2 at T = 5 K, and ~ 1.2  105 A/cm2 at T = 30 K, for the sintered composite MgB2/SUS ribbon, at H = 0 G.Comment: 10 pages, 4 figure

Analysis of air-water two phase natural circulation flow by using RELAP5/MOD3

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.Air-water two phase natural circulation flow in the T-HERMES (Thermo-Hydraulic Evaluation of Reactor cooling Mechanism by External Self-induced flow)-1D experiment has been verified and evaluated by RELAP5/MOD3 computer code. The RELAP5 results have shown that an increase in the coolant inlet area leads to an increase in the water circulation mass flow rate. However, the water outlet area has no influence on the water circulation mass flow rate. As the coolant outlet moves to a lower position, the water circulation mass flow rate decreases. The water level has no influence on the water circulation mass flow rate