Low-crosstalk 3.125 Gbit/s×four-channel LD array withisolated electrodes for parallel optical communications

An array of 1.3 μm FP-LDs with their anodes and cathodes separated channel by channel was developed to suppress interchannel electric crosstalk at high frequency. Low crosstalk of less than -30 dB was obtained between neighbouring LDs at 3.125 GHz. This is sufficiently low that BER characteristics observed under asynchronous operation of a four-channel LD array were found to be no worse than those under single channel operation     

Visualization of hydrogen in hydrogen storage alloys using neutron radiography

Small amounts of hydrogen in hydrogen storage alloys, such as Mg₂Ni, were detected using neutron radiography (NRG). Hydrogen concentrations in a hydrogenated solid solution were determined by this technique. Furthermore, we were able to obtain NRG images for an initial stage of hydrogen absorption in the hydrogen storage alloys. NRG would be a new method of measurement to clarify the behavior of hydrogen in hydrogen storage alloys.     

Investigation of Initial Transient Oxidation of Fe–<Emphasis Type="Italic">x</Emphasis>Cr–6at.%Al Alloys Using Synchrotron Radiation During Heating to 1000 °C in Air

To understand the role of composition in the oxidation behavior of Ti–Mo system and to evaluate the extent of oxygen ingress into the metal substrate during high temperature exposure, a compositionally graded Ti–xMo specimen (0 ≤ x ≤ 12 wt% Mo) was prepared using an additive manufacturing technique, solutionized and then subjected to oxidation tests at 650 °C for different exposure times. The depth of oxygen diffusion, across the composition range, was assessed via change in the local hardness and the results were coupled with quantitative measurement of the oxygen concentration. The concentration of O in the α phase was reduced by 90 % after a short distance of 16 μm from the metal/oxide interface while it remained more or less the same in β phase. The solubility of Mo in α phase also approached zero near the surface as O changed the partition coefficient of this element between α and β phases. It was shown that the addition of Mo reduces the solubility of O in the metal substrate which in turn retards the transition point from parabolic to the linear oxidation stage.     

Model of physico-chemical effect on flow accelerated corrosion in power plant

Flow accelerated corrosion (FAC) is caused by the accelerated dissolution of protective oxide film under the condition of high flow rate and has been one of the most important subjects in fossil and nuclear power plants. The dominant factors of FAC are water chemistry, material, and fluid dynamics. Understanding of the thinning mechanism is very important to estimate the quantitative effects of the dominant factors on FAC. In this study, a novel model of chemical effect on FAC under the steady-state condition was developed in consideration of the diffusion of soluble iron and chromium species, dissolved hydrogen, and dissolved oxygen. The formula to evaluate the critical concentration of dissolved oxygen for FAC suppression was derived. The present model reproduced qualitatively the effect of major environmental parameters on FAC rate. The model could explain the following facts. (1) The FAC rate shows a peak around 413 K. (2) The FAC rate decreases with an increase in Cr content. (3) The FAC rate decreases with an increase in pH. (4) The FAC rate decreases with an increase in dissolved oxygen concentration. (5) The maximum of critical dissolved oxygen concentration is observed around 353 K. (6) The critical dissolved oxygen concentration decreases with an increase in pH. We conclude that the diffusion of soluble species from the saturated layer under the steady-state condition well reproduces the unique FAC behavior with variation of water chemistry parameters.     

Poly-γ-glutamate-based Materials for Multiple Infection Prophylaxis Possessing Versatile Coating Performance

Poly-γ-glutamate (PGA) possesses a nylon-like backbone and polyacrylate-like carboxyl groups, and shows an extraordinary solubility in water. In this study, the effective synthesis and structural analysis of some water-insoluble PGA ion-complexes (PGAICs) using cationic surfactants, hexadecylpyridinium (HDP), dodecylpyridinium, benzalkonium and benzetonium, were examined. We demonstrated their spontaneous coating performance to the surfaces of different materials (i.e., plastics, metals, and ceramics) as potent anti-staphylococcal and anti-Candida agents. The tests against Staphylococcus aureus revealed that, regardless of a variety of materials, PGAICs maintained surface antimicrobial activity, even after the water-soaking treatment, whereas those against Candida albicans indicated that, among PGAICs, PGA/HDP complex is most useful as an anti-fungal agent because of its coating stability. Moreover, the log reduction values against Influenza A and B viruses of PGA/HDP-coated surfaces were estimated to be 5.4 and 3.2, respectively, suggesting that it can be dramatically suppressed the infection of influenza. This is to our knowledge the first observation of PGA-based antiviral coatings.     

Adsorption mechanism of copper and cadmium onto defatted waste biomass

In this study, the amount of copper or cadmium adsorbed using waste biomass (i.e., coffee grounds (CG) and rice bran (RB)) was investigated. The amount of crude protein in defatted CG (D-CG) or RB (D-RB) was greater than that in CG or RB, respectively. The amount of copper or cadmium adsorbed using CG was greater than that using RB. Additionally, the amount of copper or cadmium adsorbed was not affected by the presence of fat in CG. Adsorption data was fitted to the Freundlich equation, and the correlation coefficients were in the range of 0.794-0.991. The main adsorption mechanism was thought to be monolayer adsorption onto the surface of the waste biomass. The adsorption rate data was fitted to the pseudo-second-order model, and the correlation coefficient average was in the range of 0.891-0.945. This result showed that the rate-limiting step may be chemisorption. Moreover, the amount of copper or cadmium desorbed from CG or RB using 0.01 mol/L or 1.00 mol/L HNO(3) was investigated. Desorption with 0.01 mol/L HNO(3) resulted in the recovery of 86-97% of the copper and cadmium, indicating that copper or cadmium that was adsorbed using waste biomass was recoverable.     

Phosphate adsorption ability of granular gibbsite and cerium hydroxide

In the present study, the phosphate adsorption abilities of granular materials, gibbsite (GB) and cerium hydroxide (CE), granulated with ethyl cellulose and ethanol, were investigated. For suitable granular conditions using GB or CE, the percentage of binder and amount of solvent were 10% and 3.25 mL/5 g for GB and 7.5% and 2.50 mL/5 g for CE. The amount of phosphate adsorbed by granular GB or CE was similar to that adsorbed by powdered GB or CE. The adsorption isotherms of phosphate were also similar for the granular and powdered materials. The results of a column experiment showed that when GB was used, the suitable concentration of sodium hydroxide as the desorption solution was 2 mmol/L. In these experiments, the amount of phosphate adsorbed was 31.4 mg/g, the amount of phosphate desorbed was 25.3 mg/g, and the recovery percentage was 80.5%. In contrast, when CE was used, the suitable concentration of sodium hydroxide was 500 mmol/L; the amount of phosphate adsorbed was 77.7 mg/g, the amount of phosphate desorbed was 57.8 mg/g, and the recovery percentage was 74.4%. Results also indicate that granular GB and CE could be used at least five times in a column without loss of absorption or desorption abilities. Moreover, granulation of GB and CE is possible using ethyl cellulose and ethanol.     

Balanced Secure Scan: Partial Scan Approach for Secret Information Protection

Scan-based Design-for-Testability technique is widely used to enhance the testability. However, it increases the vulnerability to attacks through scan chains for secure chips such as cryptographic circuits with embedded secret keys. This paper proposes a secure scan design method which protects the circuits containing secret information such as cryptographic circuits from scan-based side channel attacks. The proposed method prevents the leakage of secret information by partial scan design based on a balanced structure. We also guarantee the testability of both the design under test and DFT circuitry, and therefore, realize both security and testability. Experiments for RSA circuit shows the effectiveness of the proposed method.