ALBERT

Notes: A two (dietary energy levels; low energy, LE and high energy, HE) × 4 (feeding frequency; one feeding in 2 days, one feeding daily, two times daily and three times daily) factorial experiment was performed to determine the effects of dietary energy level and/or feeding frequency on the growth and body composition of juvenile flounder Paralichthys olivaceus. The survival rate was not significantly different among treatments. Weight gain of fish fed the LE and HE diets significantly increased as feeding frequency increased. The weight gain of fish fed the LE diet was higher at each level of increasing feeding frequency. The weight gain of fish fed the HE diet was higher than that of fish fed the LE diet once in 2 days and once daily, but weight gain of fish fed the HE diet was lower than the LE diet three times daily. Daily feed intake was significantly influenced by feeding frequency, but not by dietary energy level. Feed efficiency of fish fed the HE diet once daily was significantly higher than that of fish fed the LE diet once in 2 days, but no significant difference in feed efficiency was observed among other groups of fish. The protein efficiency ratio of fish fed the LE diet once in 2 days was the lowest. Feeding frequency and dietary energy level had a significant effect on the body lipid content. A feeding frequency of two times or three times daily would be effective, depending on dietary energy level for maximum growth of juvenile flounder grown from 3.5 to 15 g.

Notes: Time-domain reflectometry (TDR) is being used increasingly for measuring the moisture content of porous media. However, successful application for measuring water in soil has been limited to non-deformable soils, and it would be a valuable extension of the technique if it could be used for soils that shrink on drying. We have recently investigated its application to soils rich in clay and organic matter and peats. Here we propose a method for determining moisture content in deformable soils based on the relation between the dielectric constant, K, and the volumetric moisture content, Θ, measured by TDR.Parallel TDR probes with a length of 15 cm and a spacing of 2 cm were placed horizontally in soil cores with a diameter of 20 cm and height of 10 cm taken from a forest. The soil is very porous with large proportions of both silt and clay. The sample weight and travel time of the electromagnetic wave guided by parallel TDR probes were simultaneously measured as a function of time, from saturation to oven-dryness during which the core samples shrank considerably. Vertical and horizontal components of shrinkage were also measured to take the air-exposed region of TDR probe into account in the determination of K. The effect of deformation on volumetric moisture content was formulated for two different expressions, namely actual volumetric moisture content (AVMC) and fictitious (uncorrected) volumetric moisture content (FVMC). The effects of air-exposure and expressions of volumetric moisture content on the relation between K andΘ were examined by fitting the observations with a third-order polynomial. Neglecting the travel time in the air-exposed part or use of the FVMC underestimated the Θ for a given K. The difference was more pronounced between AVMC and FVMC than between two different dielectric constants, i.e. accounting for air-exposure, Kac, and not accounting for air-exposure, Kau. When the existing empirical models were compared with the fitted results, most underestimated the relation based on the AVMC. This indicates that published empirical models do not reflect the effect of deformation on the determination of Θ in our forest soil. Correct use of the Θ expression has more impact on determining moisture content of a deformable soil than the accommodation of travel time through the air-exposed region of TDR probe.

Notes: A simulation program for admittance calculations in a semiconductor Schottky junction with a trap was developed using physical parameters including the Poole–Frenkel electric field-assisted emission effect. The simulation revealed limitations in the validity of the admittance measurement technique in determining thermal activation energies of semiconductors. The controversy in the observed thermal activation energy of the GaN:Mg structures between the Hall effect and admittance spectroscopy measurements is explained using the simulation results. The admittance measurement technique can only determine the real energies when the overall doping concentration of the shallow (NS) and deep (NT) levels is low and while NT≤NS. While the condition of NT≥NS causes a reduction in the apparent measured energies, the electric field built up at the crossover by NS or/and NT further reduces the energies by lowering the barrier potential for the trap emission. Particularly if NT(very-much-greater-than)NS, the electric field induced by the deep level itself induces the reduction in the barrier potential. This is the case for the rather highly doped GaN:Mg structures. © 2000 American Institute of Physics.

Notes: A series of GaN:Mg structures were grown in molecular beam epitaxy, using either one or two rf nitrogen sources, and in metalorganic chemical vapor deposition systems with varying Mg flux. Acceptor energies were measured using the Hall effect and admittance spectroscopy techniques. The acceptor energies were found to be different for the two methods, i.e., 135–155 meV for the Hall effect measurement and 80–115 meV for the admittance spectroscopy measurement. The apparently small acceptor energies from the admittance spectroscopy measurement were explained, through a simulation process, by the combined effects of (1) high Mg acceptor concentration with no other free carrier sources, and (2) the Mg emission kinetics assisted by the Frenkel–Poole field effect in the GaN:Mg structures. © 2000 American Institute of Physics.

Notes: A detailed systematic study on the growth morphology of carbon nanotubes (CNTs) on Si in atmospheric pressure thermal chemical vapor deposition was undertaken. The role of NH3 for vertical alignment of CNTs was investigated. The direct cause for the alignment was a dense distribution of the catalytic metal particles, but that the particles are maintained catalytically active under amorphous carbon deposits was established by NH3. It allows a dense nucleation of the CNTs, and consequently, assists vertical alignment through entanglement and mechanical leaning among the tubes. The CNTs grew in a base growth mode. Since Ni is consumed both by silicide reaction and by capture into the growing tube, the growth stops when Ni is totally depleted. It occurs earlier for smaller particles, and thus a long time of growth results in a thin bottom with poor adhesion. © 2002 American Institute of Physics.

Notes: The properties of SrBi2Ta2O9 (SBT) films, such as remanent polarization and leakage current density, are closely related to the film/electrode interface and surface roughness of the underlying electrode. SBT films grown on stable Pt/TiO2/SiO2/Si and Pt/ZrO2/SiO2/Si substrates exhibit high remanent polarization, low leakage current density, and low voltage saturation as compared to SBT films synthesized on Pt/Ti/SiO2/Si. It is shown that severe diffusion of Ti from the Ti interlayer onto the surface of the Pt bottom electrode and the increased surface roughness of this electrode stack play key roles in degradation of SBT properties. © 2000 American Institute of Physics.

Notes: The effects of growth temperature on the microscopic structure of GaN nucleation layers were studied in a synchrotron x-ray scattering experiment. As the growth temperature increases from 467 to 655 °C, the stacking of GaN changes from random stacking to a mixture of cubic and hexagonal stacking. With increasing the growth temperature, the order in the atomic layer positions in the out-of-plane direction increases and the mosaic distribution becomes narrow. The optimal photoluminescence spectrum was obtained on the GaN epilayer deposited on the nucleation layer grown at 505 °C. © 1999 American Institute of Physics.

Notes: We report reproducible realization of GaAs/Al0.25 Ga0.75 As(100) inverted heterojunctions with liquid-nitrogen electron mobilities in excess of 105 cm2 /(V s). This is made possible through use of reflection high-energy electron-diffraction (RHEED) intensity dynamics determined optimized growth conditions, but without the use of short-period superlattices as buffers or spacer layers.

Notes: A 3 (protein levels, 380, 460 and 520 g kg–1 diet) × 2 (lipid levels, 65 and 140 g kg–1 diet) factorial experiment with three replicates was conducted. Weight gain, feed efficiency and daily feed intake were not significantly affected by dietary protein level, but were by dietary lipid level. Weight gains of fish fed 65 g lipid kg–1 diet were significantly, or slightly, higher than for 140 g lipid kg–1 diet at all protein levels. Daily protein intake was significantly affected by both dietary protein and lipid levels (P 〈 0.002). Daily lipid intake was not significantly affected by dietary protein level, but was by dietary lipid level (P 〈 0.001). Protein efficiency ratio was significantly affected by dietary protein level (P 〈 0.02), but not by dietary lipid level. Protein efficiency ratio tended to improve with the decrease of dietary protein level at the same lipid level. Moisture, protein and lipid contents of whole fish were significantly affected by dietary lipid level (P 〈 0.01). Increased dietary lipid did not improve growth or feed efficiency, but increased body fat deposition. It was concluded that the optimum dietary protein and lipid level for growth of juvenile ayu may be 380 and 65 g kg–1 diet, respectively, when fish were fed to satiety three times daily in seawater.