Optics for modulating multiple beams using an asymmetric multilevel phase grating and a multichannel acousto-optic modulator

Asymmetric multilevel phase gratings for generating even numbered beams have been designed, assuming that their phase patterns are formed by overlapping plural binary-phase patterns, each of which has an arbitrary phase height. The grating for four beams, which produces uniform and high intense diffraction orders of the minus first to the plus second order, is fabricated. The efficiency is 75.5%, although the theoretical efficiency is 79.9%. It is also demonstrated that the optics in which the beams from the grating are fed into a multichannel acousto-optic modulator through a Fourier-transform lens makes their successful modulation possible for pulse signals of 20-ns pulse duration.     

Infrared sensors using poly‐Si thin‐film transistors for proximity sensors integrated in smartphone displays

We have developed infrared sensors using poly‐Si thin‐film transistors (TFTs) for proximity sensors integrated in smartphone displays. Initially, we evaluate the infrared sensitivities of the poly‐Si TFTs, and it is found that a pin‐type TFT is suitable for the infrared sensors. Next, we propose three types of the infrared sensors. First, an analog current detection‐type sensor has a simple structure, and it is found that it can detect presence of a hand. Second, a lock‐in detection‐type sensor has tolerance against ambient light, and it is found that it can detect a target signal under noise signals. Third, a frequency detection‐type sensor has an advantage that only a digital circuit is necessary for detection, and it is found that it can detect the infrared intensity because the oscillation frequency increases monotonically with the intensity. We can utilize these infrared sensors on demand.     

Quantitative analysis of agglomerates levitated from particle layers in a strong electric field

The electrification, agglomeration, and levitation of particles in a strong electric field were analyzed experimentally and theoretically. Particle layers of glass, alumina, and ferrite were formed on a plate electrode and an external voltage was applied. Microscopic observations of the agglomerates levitated from the particle layers revealed that the number of primary particles constituting an agglomerate is affected by particle diameter and electrical resistance, but not by the applied electric field. The electric field distributions in the system were calculated by considering the charges and geometries of the agglomerates formed on the particle layers. The charges of the agglomerates were obtained experimentally. All forces acting on the agglomerates (i.e., gravitational forces, Coulomb forces, interaction forces between polarized particles, image forces, and gradient forces) were analyzed under different conditions, including various electric field distributions and charges of agglomerates. Furthermore, the critical conditions for the levitation of the agglomerates were evaluated using a force balance.     

Directing the assembly of charged organic molecules by a hydrophilic-hydrophobic nanostructured monolayer at electrified interfaces

Nanostructured monolayers of water-insoluble amphiphilic 5-alkoxy-isophthalic acids direct the reversible self-assembly of water-soluble positively and negatively charged molecules under electrochemical control. The surface potential is in control of the monolayer composition, structure, and guest dynamics.     

Environmental Effects on Microstructural Stability of SiC/SiC Composites

LowZmaterialshavemanyadvantagesinnuclearenvirOInnellts,suchaslessProductionofradioactivewastesduetosubstantiallylowactivation,andhigherconVergentefficiencyduetothecapabilityofhightemp~OPeration.HopkinhasdiscussedSiC-basedmaterialsforfhaionreactorsfor...     

Synthesis of nanocrystalline LaF3 doped silica glasses by hydrofluoric acid catalyzed sol–gel process

Silica glasses doped with LaF₃ nanocrystals were prepared by HF-catalyzed sol–gel method. HF was used both as fluorine source and as catalyst of the sol–gel reaction, making it possible to shorten the processing time with reducing the concentration of SiOH groups to ～10¹⁸ cm^?3. The resultant glasses are transparent at visible spectral range, and the optical loss at the ultraviolet absorption edge is dominated by the Rayleigh scattering from LaF₃ crystallites. The size of LaF₃ crystallites increases with an increase in the sintering temperature and time, and is smaller than ～40 nm in samples showing good visible transparency. Green upconversion photoluminescence is observed in an Er³⁺-doped sample under excitation at 980 nm.     

Mechanical properties of Al–Si–Cu alloys produced by the continuous casting process with heating process

The mechanical properties of aluminium alloys produced by the continuous cast process and heating process (heat-cast-sample) were investigated, where the aluminium alloys are heated continuously to high temperatures for 1 h immediately following heated mould continuous casting (HMC) and sand gravity casting (SGC). The material strength and ductility of the aluminium alloys were irregularly altered depending on the heating temperature. The mechanical properties decreased when the heating temperature increased to 400 °C and were then recovered when the temperature increased to 520 °C. However, these properties decreased again when heated to more than 540 °C. The mechanical properties of the HMC-heat-cast-sample showed overall higher than those for the SGC-sample. In addition to high tensile strength, high ductility was obtained for the HMC-520 °C samples compared with those for the as-cast-sample. Such changes were found to be directly attributable to the different severity of precipitate; moreover the crystal orientation was unchanged even after the heating process.     

Biodegradable β-tricalcium phosphate cement with anti-washout property based on chelate-setting mechanism of inositol phosphate

Novel biodegradable β-tricalcium phosphate (β-TCP) cements with anti-washout properties were created on the basis of chelate-setting mechanism of inositol phosphate (IP6) using β-TCP powders. The β-TCP powders were ball-milled using ZrO₂ beads for 0–6 h in the IP6 solutions with concentrations from 0 to 10,000 ppm. The chelate-setting β-TCP cement with anti-washout property was successfully fabricated by mixing the β-TCP powder ball-milled in 3,000 ppm IP6 solution for 3 h and 2.5 mass% Na₂HPO₄ solution, and compressive strength of the cement was 13.4 ± 0.8 MPa. An in vivo study revealed that the above cement was directly in contact with host and newly formed bones without fibrous tissue layers, and was resorbed by osteoclast-like cells on the surface of the cement. The chelate-setting β-TCP cement with anti-washout property is promising for application as a novel injectable artificial bone with both biodegradability and osteoconductivity.     

Hydrothermal conversion of Mg2TiO4 into brookite-type TiO2 under mild conditions

A simple and mild synthetic route via a hydrothermal treatment of Mg₂TiO₄ has been developed to prepare brookite-type TiO₂. The hydrothermal conversion of Mg₂TiO₄ to brookite proceeded in 1 M HCl solution even at 100 °C. The converted brookite grains were composed of the angular particles covered on the textured surface, leaving the original morphology of Mg₂TiO₄ grains. Compared with the commercially available TiO₂ catalysts (rutile, anatase, and P25), the brookite obtained in this study showed a good photocatalytic activity toward the oxidation of benzyl alcohol to benzaldehyde under a simulated sunlight irradiation.