Evaluation of corrosion resistance of aluminium anodic oxide film by Hunter's highly sensitive method

The effect of impurities or alloy component in aluminium on the formation and corrosion resistance of the barrier layer was studied by techniques for producing highly sensitive i—V (current: 10^?9 A/cm²) curves, a dipping test, scanning electron microscopy and transmission electron microscopy. Results were obtained as follows: (a) Hunter's highly sensitive method, it was demonstrated that aluminium of 99.99%, 99.91%, 99.46%, 991.61% and 99.15% purity provided more defects in the same order as the purity; (b) measurements of i—T curves and the dipping test demonstrated that the corrosion resistance of the samples increased in the same order as the purity; and (c) observations by scanning and transmission electron microscopy suggested that the cells decreased in number and were uniform in size, in the same order as the purity noted above. These defects appeared to contribute to pitting corrosion.As noted above, it is concluded that pitting corrosion on aluminium anodic films is dependent on the defects in the barrier layer and the highly sensitive Hunter's method, which has a high sensitivity, is an appropriate means of measuring the defects quantitatively.     

The coloring of geopolymers by the addition of copper compounds

The development of a new coloring technique is desirable to increase the commercial value of geopolymers. Selected copper compounds, i.e. Cu(OH)₂, CuO, Cu₂O, CuCO₃?Cu(OH)₂?H₂O, CuCl₂?2H₂O and CuSO₄?5H₂O, were added to the initial reactants in order to color the geopolymers in the same manner as naturally occurring minerals. When Cu(OH)₂, CuO and Cu₂O were used, these compounds remained in the geopolymer matrix following hardening of the material. On the contrary, CuCO₃?Cu(OH)₂?H₂O, CuCl₂?2H₂O and CuSO₄?5H₂O were not detected in the final products. XAFS analyses were performed to investigate the local structure of copper in the geopolymers produced. The results showed that the copper spectra of geopolymers incorporating Cu(OH)₂, CuO and Cu₂O correspond to those of pure Cu(OH)₂, CuO and Cu₂O, respectively. However, when CuCO₃?Cu(OH)₂?H₂O, CuCl₂?2H₂O and CuSO₄?5H₂O were added, the copper generated spectra similar to that of the mineral chrysocolla ((Cu, Al)₂H₂Si₂O₅(OH)₄?nH₂O) than the respective copper compounds.     

Arginine Arrangement of Bacteriophage λ N‐Peptide Plays a Role as a Core Motif in GNRA Tetraloop RNA Binding

A simple α‐helical N‐model‐peptide was designed to investigate the role of the arginine‐rich motif of bacteriophage λ N‐peptide in selective binding with boxB RNA. The five‐arginine arrangement of native N‐peptide was retained; all other residues were replaced with alanine. In vitro selection of RNA (30 random‐nucleotide region) was carried out with N‐model‐peptide immobilized on a 27 MHz quartz‐crystal microbalance (QCM). Selected RNAs were evaluated on the same QCM plate to obtain binding constants (K_a=10⁷–10⁸ M ^?1). Many selected RNAs contained GNR(N)A‐type loops (similar to the boxB RNA motif recognized by the native N‐peptide). Fragments and minimal RNAs containing the GNRA‐type loop also bound to N‐model‐peptide (K_a=10⁶–10⁷ M ^?1). The RNA recognition specificity of the peptide was studied by changing the “closing” U–A base pair and one base in the tetraloop of the RNA aptamers, and by peptide mutations (18th residue of N‐model‐peptide). It was concluded that the five‐arginine arrangement of the peptide performs selective recognition of the GNRA tetraloop and GNR(N)A pentaloop RNA structures, and that substitution of another functional amino acid residue at the 18th position in N‐peptide adds the recognition ability for a loop‐RNA sequence.     

Seismic response analysis of full-scale boiling water reactor using three-dimensional finite element method

This paper presents the three-dimensional finite element seismic response analysis of full-scale boiling water reactor BWR5 at Kashiwazaki-Kariwa Nuclear Power Station subjected to the Niigata-ken Chuetsu-Oki earthquake that occurred on 16 July 2007. During the earthquake, the automatic shutdown system of the reactors was activated successfully. Although the monitored seismic acceleration significantly exceeded the design level, it was found that there were no significant damages of the reactor cores or other important systems, structures and components through in-depth investigation. In the seismic design commonly used in Japan, a lumped mass model is employed to evaluate the seismic response of structures and components. Although the lumped mass model has worked well so far for a seismic proof design, it is still needed to develop more precise methods for the visual understanding of response behaviors. In the present study, we propose the three-dimensional finite element seismic response analysis of the full-scale and precise BWR model in order to directly visualize its dynamic behaviors. Through the comparison between both analysis results, we discuss the characteristics of both models. The stress values were also found to be generally under the design value.     

Realization of anti-slip/skid re-adhesion control for electric commuter train based on disturbance observer

Recently, disturbance observer has been used in many system and industry applications. This paper focus on the fine motion control technology based on disturbance observer for electric commuter train. The improvement of adhesion characteristics is important in electric commuter train. We propose the anti-slip/skid re-adhesion control system based on disturbance observer and sensor-less vector control. The effectiveness of the proposed method is confirmed by the experiment based on the actual electric commuter train, which is Series 205-5000 of East Japan Railway Company. Moreover, in order to extend the anti-slip/skid re-adhesion control considering the bogie vibration phenomenon, we propose a new anti-slip re-adhesion control based on the high order disturbance observer considering the resonant frequency of bogie system. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Co-planar bi-metallic interdigitated electrode substrate for spin-coated organic solar cells

A bulk heterojunction organic solar cell with co-planar interdigitated electrodes was fabricated and tested. The co-planar electrodes had a separation distance of 1-3 μm and were fabricated from aluminum and nickel on a heavily oxidized silicon wafer using photolithography. The device was prepared by spin-coating MEH-PPV:PCBB in a 1:3 wt ratio with a total donor:acceptor solution concentration of 2.44%. The device demonstrated a strong photovoltaic response under AM1.5 illumination of 80 mW/cm² with an open circuit voltage of 0.704 V. The co-planar electrode design offers advantages in terms of electrode material selection and reliability as well as simplified device fabrication.     

Distribution of a novel angiotensin I-converting enzyme inhibitory substance (2″-hydroxynicotianamine) in the flour,plant parts,and processed products of buckwheat

2″-Hydroxynicotianamine (HNA) is a recently discovered angiotensin I-converting enzyme inhibitory compound present in buckwheat which displays hypotensive activity. Here, HNA levels in buckwheat flour, plants, and products were quantified to examine the potential functionality of this food. The HNA content of buckwheat flour ranged from 16–28 mg per 100 g dry weight. When the content was evaluated by the milling stage, common buckwheat contained 24.3, 24.1, and 34.1 mg in the inner, middle, and outer layers, respectively, whereas tartary buckwheat contained 16.8, 30.5, and 51.8 mg of HNA, respectively. Comparison of the distribution of HNA within buckwheat plants revealed that HNA was predominantly localised in seeds (buckwheat flour). The residual HNA levels after cooking ranged from 21% to 41% in dried buckwheat noodles. This study clarified that buckwheat flour contains high levels of HNA and is a readily available source of HNA if incorporated into one’s diet, which may help reduce hypertension.     

Accuracy assessment of a noninvasive device for monitoring beat-by-beat blood pressure in the radial artery using the volume-compensation method

For the noninvasive and accurate measurement of instantaneous blood pressure (BP) in the radial artery, the performance of a device based on the principle of volume-compensation was assessed by comparison with simultaneous measurement of direct (invasive) radial artery pressure in nine healthy subjects. Bias and precision of systolic BP (SBP) and diastolic BP (DBP) derived from Bland-Altman plots of data from the present system and the direct method averaged -0.5 +/- 2.1 mmHg and 0.6 +/- 1.8 mmHg respectively, over a wide range of SBP and DBP. These results clearly indicate that, using this system, instantaneous radial artery pressure can be measured noninvasively with high accuracy.     

Endovascular grafts for noninfected aortoiliac anastomotic aneurysms

PURPOSE: This report describes our experience with endovascular repair of aortic and iliac anastomotic aneurysms. METHODS: Between June 1994 and March 1996, 12 noninfected aortic or iliac anastomotic aneurysms in 10 patients who had serious comorbid medical conditions that precluded or made difficult standard operative repair were treated using endovascular grafts. No patient in this study had a history of fever, leukocytosis, or computed tomographic evidence of a periprosthetic fluid collection that was suggestive of infection of the original graft. Endovascular grafts composed of polytetrafluoroethylene and balloon-expandable stents were introduced through a femoral arteriotomy and were placed using over-the-wire techniques under C-arm fluoroscopic guidance. RESULTS: Endovascular grafts were successfully inserted in all patients with aortic or iliac anastomotic aneurysms. There were no procedure-related deaths, and complications included one postprocedure wound hematoma and one perioperative myocardial infarction. Graft patency has been maintained for a mean of 16.1 months, with no computed tomographic evidence of aneurysmal enlargement or perigraft leakage. CONCLUSIONS: Endovascular grafts appear to be a safe and effective technique for excluding some noninfected aortoiliac anastomotic aneurysms in high-risk patients and may become a treatment option in all patients who have clinically significant lesions.