Development of a radon trap device using a corona discharge

Radon is one of the noble gases, which are chemically inert and do not make any reactants under normal conditions. In this experiment we demonstrated an enigmatic reaction between radon and fluorine when a corona discharge is used as a promoter. Distinctive changes in radon concentrations were caused by the discharge and a trap efficiency of >99.5% was estimated. The mass balance between the trapped and the released radon was found to be reasonable. This indicates the existence of chemical reactions with radon. This trap phenomenon has application as a technique for reducing radon concentration in radon-contaminated air. It is possible that this technique will be applicable to other noble gases.     

Wave-optical evaluation of interference fringes and wavefront phase in a hard-x-ray beam totally reflected by mirror optics

The intensity flatness and wavefront shape in a coherent hard-x-ray beam totally reflected by flat mirrors that have surface bumps modeled by Gaussian functions were investigated by use of a wave-optical simulation code. Simulated results revealed the necessity for peak-to-valley height accuracy of better than 1 nm at a lateral resolution near 0.1 mm to remove high-contrast interference fringes and appreciable wavefront phase errors. Three mirrors that had different surface qualities were tested at the 1 km-long beam line at the SPring-8/Japan Synchrotron Radiation Research Institute. Interference fringes faded when the surface figure was corrected below the subnanometer level to a spatial resolution close to 0.1 mm, as indicated by the simulated results.     

Monolithically integrated high-speed light source using 1.3-µm wavelength DFB-DC-PBH laser

The first monolithic high-speech light source, consisting of an InGaAsP/InP DFB laser, metal-insulator-semiconductor field-effect transistors, and a monitoring photodiode, has been fabricated. Small-signal modulation bandwidth up to 4 GHz was successfully achieved. The device design, fabrication procedures, and operating characteristics for the integrated light source are described.     

New Magnesium Composite with Mg17Al12 Intermetallic Particles

Powder Metallurgy and Metal Ceramics - Although magnesium is one of the materials with the lowest density, its application is limited amongst other commercial materials due to insufficient...     

Elution of sodium caseinate from agar-based gel matrixes in simulated gastric fluids

Elution of sodium caseinate from agar/psyllium composite gels was investigated in simulated gastric fluids to determine predominant mechanical parameters of gels for the elution kinetics and to predict the kinetics using the parameters. When the concentration of agar was fixed at 0.5% in the composite gels, elastic moduli determined by creep tests decreased with increasing concentration of psyllium, while viscosities increased. Compression load upon syringing through an enteral tube increased with increasing concentration of psyllium, whereas the surface-volume diameter d_3,2 of gel particles after syringing decreased. The elution kinetics of sodium caseinate from cylindrical gels was described using two different diffusion coefficients; D₁ and D₂ (D₁ > D₂) and the diameter of gels. Both diffusion coefficients decreased with increasing concentration of psyllium, resulting in 1.9 × 10⁻⁶ (for D₁) and 6.7 × 10⁻⁸ (for D₂) cm²/min by 1.5% addition, which corresponded to approx. 30% and 45% of the control (i.e., 0% psyllium), respectively. The fraction ratio of sodium caseinate having D₁ was not sensitive to psyllium concentration; approx. 80%–85% in the concentration range tested. D₁ was inversely proportional to viscosities determined by creep tests, particularly one from the Voigt body η₁ in the 4-element mechanical model. When cube gels were divided into smaller ones without changing the total volume, elution rates were inversely proportional to the cube length, where the diffusion coefficients did not change. The elution kinetics of sodium caseinate from the gel matrixes was anticipated using η₁ of gels before syringing and d_3,2 of gel particles after syringing when the usage of gels for percutaneous endoscopic gastrostomy is assumed.     

High-temperature properties of extruded titanium composites fabricated from carbon nanotubes coated titanium powder by spark plasma sintering and hot extrusion

Pure titanium matrix composite reinforced with carbon nanotubes (CNTs) was prepared by spark plasma sintering and hot extrusion via powder metallurgy process. Titanium (Ti) powders were coated with CNTs via a wet process using a zwitterionic surfactant solution containing 1.0, 2.0 and 3.0 wt.% of CNTs. In situ TiC formation via reaction of CNTs with titanium occurred during sintering, and TiC particles were uniformly dispersed in the matrix. As-extruded Ti/TiCs composite rods were annealed at 473 K for 3.6 ks to reduce the residual stress during processing. After annealing process, the tensile properties of the composites were evaluated at room temperature, 473, 573 and 673 K, respectively. Hardness test was also performed at room temperature up to 573 K with a step of 50 K. The mechanical properties of extruded Ti/CNTs composites at elevated temperature were remarkably improved by adding a small amount of CNTs, compared to extruded Ti matrix. These were due to the TiC dispersoids originated from CNTs effectively stabilized the microstructure of extruded Ti composites by their pinning effect. Moreover, the coarsening and growth of Ti grain never occurred even though they were annealed at 573, 673 K for 36 ks and 673 K for 360 ks, respectively.     

Retardation of Crystallization of Diacylglycerol Oils Using Polyglycerol Fatty Acid Esters

Liquid oil containing high concentrations of diacylglycerols (DAG > 80 %, hereafter referred to as DAG-rich oil) is generally more likely to cause precipitation at chilled temperatures (clouding phenomena) than triacylglycerol-based oil. The clouding phenomena that occur during long-term storage of DAG-rich oil are unwanted in consumer products and therefore, must be prevented. In the present study, we attempted to retard precipitation by adding food emulsifiers, polyglycerol fatty acid esters (PGFE) containing different fatty acid moieties. DSC, polarized optical microscopy, and X-ray diffraction studies revealed that the addition of 0.2 % PGFE containing palmitic and oleic acid moieties very effectively retarded precipitation in the DAG-rich oil. To confirm these observations, we prepared a model DAG oil to mimic DAG-rich oil and examined the retardation behavior of high-melting DAG fractions using PGFE. The results are discussed in terms of the effects of PGFE additives on the pre-nucleation processes of high-melting fractions in DAG-rich oil.     

A new technique for fabrication of OEICs-the etched back planarprocess-and its application to the fabrication of planar embeddedInP-InGaAs p-i-n photodiodes

The etched back planar process utilizes a nonselective reactive ion beam etching (RIBE) technique both for semiconductor layers and for photoresist. Application of the technique to the fabrication of a planar InP-InGaAs embedded p-i-n photodiode is discussed. The groove depth on the wafer was reduced from 5.3 μ to 0.6 μm, and the wafer was nearly planarized. Estimates based on photoluminescence intensity variation and the characteristics of the fabricated p-i-n photodiode indicate that little damage was incurred during the process. These results indicate that fabrication of planar OEICs by means of this process is feasible