Compositional Dependence of Judd-Ofelt Parameters in Silicate, Borate, and Phosphate Glasses

Judd-Ofelt parameters Ω _t with t = 2,4, 6 for the rare-earth ions Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, and Tm³⁺ in alkali and/or alkaline-earth silicate, borate, and phosphate glasses have been determined. The variations of Ω _t with the number of 4 f electrons of the rare-earth ions are demonstrated, and factors affecting the Judd-Ofelt parameter Ω₆are discussed. The intensity parameter Ω₆ depends on the ionic packing ratio of the glass host by changing modifier type in silicate and borate glasses, and it is independent of that in a series of borate glasses as a function of modifier content and phosphate glasses. The peak wavenumbers of the transitions whose intensities are determined mainly by the Ω₆<| U ⁽⁶⁾|>² term—where <| U ⁽⁶⁾|> is one of the reduced matrix elements—shift systematically with the values of Ω₆ for all the rare-earth ions.     

Evaluation performance for site amplification factors: S-wave impedance vs. VS30

Simplified regression models to evaluate site amplification are widely adopted for seismic microzonation maps, design specifications, and so forth. In practice, the most popular parameter for controlling the evaluation models is an averaged S-wave velocity of top z m depth, V_Sz, especially V_S30. The S-wave impedance ratio of the uppermost layer to the base layer, I_S1/I_S0, is an alternative evaluation parameter. In this study, we compare the evaluation performance of V_Sz and I_S1/I_S0 for SH wave amplification factors on the basis of numerical experiments on artificially generated soil profiles. Taking the average S-wave velocity, depth z must be selected on the basis of the target period range of the site amplification factors. I_S1/I_S0 is found to perform similarly to V_S10, and it is better than V_S30 for the peak ground acceleration (PGA) and the short-period range (0.1–0.5?s). This implies that I_S1/I_S0 is effective for use in site amplification evaluations because I_S1 only requires a physical parameter on the uppermost surface layer.     

METASTABLE R-PHASE IN Fe-Cr-Mo AND Fe-Cr-W ALLOYS

The precipitation behaviour of Fe-Cr-Mo and Fe-Cr-W alloys during aging has been ex- perimentally studied.It was found that in the early stage of aging,a metastable R phase pre- cipitated in both alloys,it was transformed into stable μ-phase,Laves-phase,X-phase or σ-phase in the later stages.The crystallographic structure of metastable R-phase is rhombohedral with lattice parameters of a=0.9075 nm and α=74.45°.The chemical compo- sition of R-phase is Fe-(27.5—34.9)Mo-(0—25.5)Cr and Fe-(28.9—33.0)W-(9.36— 21.0)Cr in at.-% in Fe-Cr-Mo and Fe-Cr-W system,respectively.     

Preparation of ZSM-5 Zeolite Honeycomb Monoliths Using Microporous Silica Obtained from Metakaolinite

Zeolite honeycomb monoliths were prepared from ZSM-5 powders synthesized under hydrothermal conditions using microporous silica obtained by selective leaching of metakaolinite. This honeycomb material was compared with those prepared using alkoxides (TEOS) as the silica source. The honeycomb monoliths were formed by extrusion of paste made from the synthesized powders through a multi-channel honeycomb die. The morphology and porous properties of these materials were studied using XRD, FTIR, SEM and N₂/Ar adsorption. ZSM-5 grains in the monoliths prepared from metakaolinite showed platy morphology with preferred orientation of the crystals in the extruded surface, and displayed an absence of secondary growth. The twinned morphology of ZSM-5 crystals was observed in the monoliths prepared using TEOS and this contributed to an increase in the external surface area even though the total surface area was identical to that of samples prepared from metakaolinite. The physical properties, thermal stability and mechanical strength of the monoliths was compared with zeolite-coated honeycombs. The results show that microporous silica prepared by acid leaching of metakaolinite is a cost-effective raw material for preparing ZSM-5 honeycomb monoliths with controlled morphology and tunable SiO₂/Al₂O₃ ratios.     

Phase behavior and hydrated solid structure in lysophospholipid/long-chain alcohol/water system and effect of cholesterol addition

Phase behavior in lysophospholipid/long-chain alcohol/water system at 80°C was investigated using hexanol and oleyl alcohol as the long-chain alcohol. Similarly to hydrophilic surfactant, a micellar phase in a lysophospholipid/water system transitioned to a lamellar liquid-crystalline phase by the addition of long-chain alcohol. In the oleyl alcohol system the lamellar liquid-crystalline phase was observed in wider region compared to the hexanol system. The effect of cholesterol addition on the phase behavior was also studied. The region of liquid-crystalline phase and (reverse micellar + liquid-crystalline + water) phase shifted towards higher lysophospholipid concentrations. The structure of hydrated solid as well as the transition between lamellar liquid-crystalline phase and hydrated solid was analyzed by X-ray scattering measurement and differential scanning calorimetry measurement. It was revealed that the hydrated solid was α-type crystals with lamellar structure. The hydrated solid (gel)-liquid crystal transition temperature gradually decreased with increasing oleyl alcohol concentration and the decrement was enhanced by the addition of cholesterol.     

Ordered Mesoporous Aluminosilicates Assembled from Dissolved LTA Precursors

Aluminosilicate sols containing Si–O–Al bonds were obtained by dissolving zeolite LTA crystals in HCl solution. The solutions were used as single-source molecular precursors of silicon and aluminum. Highly ordered cage-like mesoporous aluminosilicates with Si/Al ratios ranging from 13 to 35 were synthesized using PEO₁₀₆PPO₇₀PEO₁₀₆ triblock copolymer aqueous solution and LTA dissolved in HCl solution under mild acidic conditions.     

Measurement of multi-degree-of-freedom error motions of a precision linear air-bearing stage

This paper describes the measurement of straightness error motions (vertical straightness and horizontal straightness) and rotational error motions (pitch, yaw and roll) of a commercial precision linear air-bearing stage actuated by a linear motor. Each of the error motions was measured by two different methods for assurance of reliability. The stage was placed in the XY-plane and moved along the X-direction. The pitch error and yaw error, which were measured by an autocollimator and the angle measurement kit of a laser interferometer, were about 8.7 and 1.6 arc-s, respectively, over a travel of 150 mm with a moving speed of 10 mm/s. The roll error was measured by the autocollimator through scanning a flat mirror along the X-direction. The second method for roll error measurement was to scan two capacitance-type displacement probes along the flat surface placed in the XZ-plane. The two probes with their sensing axes in the Y-direction were aligned with a certain spacing along the Z-axis. The roll error can be obtained by dividing the difference of the outputs of the two probes by the spacing between the two probes. The roll error was measured to be approximately 11.8 arc-s over the 150 mm travel. The horizontal straightness error and the vertical straightness error (Y- and Z-straightness errors) were measured by using the straightness measurement kit of the laser interferometer. The second method for straightness measurement was to scan the flat surface with a capacitance-type displacement probe. The horizontal and vertical straightness errors of the stage over the 150 mm travel were measured to be approximately 207 and 660 nm, respectively.