Nanostructured bulk copper fabricated by accumulative roll bonding

In this study, we tried to fabricate the nanostructured bulk copper alloys by a severe plastic deformation process. The sheets of copper alloys (OFC, PMC90, and DLP) were heavily deformed to an equivalent strain of 6.4 by the accumulative roll-bonding (ARB) process. The microstructure and the mechanical property of the fabricated specimens were systematically investigated. The microstructure was finely subdivided with increasing the equivalent strain by the ARB process. The severely deformed copper alloys exhibited the ultrafine lamellar boundary structure where the mean lamella spacing was about 200 nm. The strength significantly increased with decreasing the lamella spacing in the ARB processed copper alloys. Especially, the tensile strength of the DLP alloys ARB processed by 8 cycles (the equivalent strain of 6.4) reached to 520 MPa, which was about three times higher than that of same materials with conventional grain size of 10-100 microm. On the other hand, the total elongation greatly dropped only by 1 ARB cycle corresponding to an equivalent strain of 0.8, which was around 3%. However, the total elongation increased again with increasing the number of the ARB cycle, and it reached to 10% after 8 cycles. The recovery of the total elongation could be recognized in all studied copper alloys. The obtained stress-strain curves showed that the improvement of the total elongation was caused by the increase in the post-uniform elongation. It can be concluded that the nanostructured copper alloys sheets having high strength without a large loss of ductility could be fabricated by the ARB process.     

Large area thin film Si module

An initial efficiency of 14.1% (J_sc=13.6 mA/cm², V_oc=1.392 V, FF=74.3%) has been achieved for a-Si/transparent interlayer/poly Si solar cell (total area of 1 cm²). Both a-Si and crystalline Si films were fabricated by plasma chemical deposition at low temperature. The short circuit current was enhanced by the introduction of a transparent intermediate layer. An initial aperture efficiency of 11.7% has been achieved for 910×455 mm² a-Si/poly Si integrated solar cell submodule, where the laser-scribing techniques were applied for series interconnections. The results of our first run of 266 submodules in our pilot plant showed the average efficiency of 11.2%, which is applicable for mass production.     

Evaluation of retained products of conception using pulsed continuous arterial spin-labeling MRI: clinical feasibility and initial results

Objectives

We evaluated the vascularity of retained products of conception (RPOC) using arterial spin-labeling magnetic resonance imaging (ASL-MRI) to clarify the clinical feasibility of this approach.

Materials and methods

A pulsed-continuous ASL sequence with echo-planar imaging (EPI) acquisitions was used. Ten consecutive patients with RPOC were enrolled. All ASL images were evaluated visually and semiquantitatively and compared with the findings of Doppler ultrasound (US) and dynamic contrast-enhanced MRI (DCE-MRI).

Results

The technical success rate was 93.7% (15/16 scans). One failed case was excluded from the analysis. Six patients showed quite high signals over RPOC, while three patients showed no abnormal signals. Doppler US alone failed to detect the hypervascular area in two cases, and ASL-MRI alone failed in three. A significant linear correlation was found between semiquantitative values of ASL-MRI and DCE-MRI. All six patients showing high signals on ASL-MRI underwent follow-up MRI after therapy. High signals in five patients decreased visually and semiquantitatively, while one patient showed signal increases.

Conclusion

Evaluation of RPOC using ASL-MRI was clinically feasible and response to therapy could be evaluated. However, the clinical advantages over conventional imaging remain unclear and need to be evaluated.

     

Corrections to air kerma and exposure measured with free air ionisation chambers for charge of photoelectrons, Compton electrons and Auger electrons

The signal charge from a free air ionisation chamber for the measurement of air kerma and exposure consists of not only the charge of ion pairs produced by secondary electrons (i.e. photoelectrons, Compton electrons and Auger electrons), but also the charge of the secondary electrons and single and multiple charged ions formed by the release of the secondary electrons. In the present work, correction factors for air kerma and exposure for the charge of the secondary electrons and ions were calculated for photons with energies in the range from 1 to 400 keV. The effects of an increase in the W value of air for low-energy electrons were also taken into consideration. It was found that the correction factors for air kerma and exposure have a maximum value near a photon energy of 30 keV; in the lower energy region, the correction factor for exposure monotonically decreases with a decrease in photon energy except for a small dip due to K-edge absorption by argon atoms in air. The values of the correction factors were found to be 0.9951 and 0.9892, respectively, for a spectrum with a mean energy of 7.5 keV, the reference X-ray spectrum with the lowest mean energy in ISO 4037-1. The air kerma correction is smaller than that for exposure, because for air kerma the signal due to the charge of secondary electrons and ions is partly compensated by the decrease in the number of ion pairs produced by the secondary electrons due to the increase of the W value of air for lower energy electrons.     

Growth-inhibition of hiochi bacteria in namazake (raw sake) by bacteriocins from lactic acid bacteria

The bacteriocins produced by Lactococcus lactis subsp. lactis C101910 (C101910) and NBRC 12007 (NBRC 12007) were used to prevent the growth of sake spoiling hiochi bacteria (Lactobacillus hilgardii, Lactobacillus fructivorans, and Lactobacillus paracasei) in namazake, which is raw (unpasteurized) sake. The bacteriocin concentrations required for decreasing the viable cell concentrations of L. hilgardii and L. fructivorans below the detection limit (1.0 × 10² cells/ml) in 24 h from the initial concentration of 4.0–9.5 × 10⁵ cells/ml in the namazake at pH 4.5 and at 4°C, were 18–35 U/ml and 5.6 U/ml for the bacteriocin from C101910 and NBRC 12007, respectively. To decrease the viable cell concentration of L. paracasei from the initial concentration of 7.5 × 10⁵ cells/ml to below the detection limit (1.0 × 10² cells/ml) in 24 h, 350 U/ml bacteriocin from C101910 and 140 U/ml bacteriocin from NBRC 12007 were required. In experiments using McIlvaine buffer (pH 4.5) with 15% ethanol instead of namazake as the medium, the viable cell concentrations of L. hilgardii and L. paracasei decreased to less than 1.0 × 10² cells/ml, whereas those of L. fructivorans decreased to less than 1.0 × 10³ cells/ml, when bacteriocins were added at the concentrations that had proven effective in namazake. The membrane depolarization assay using a fluorescent probe showed that the presence of ethanol stimulated the collapse of the membrane potential induced by bacteriocins. The ethanol induced collapse of the membrane potential suggests that the application of bacteriocins at the storage stage of namazake is more beneficial than when used in other stages of the sake brewing process.     

Changes of aquaporin 5-distribution during release and reaccumulation of secretory granules in isoproterenol-treated mouse parotid gland

Water channel aquaporin 5 (AQP5) is present in the apical membrane of the salivary gland acinar cells. We examined changes of AQP5-distribution during the fusion process of secretory granule membranes into the apical membrane and subsequent recovery process in the mouse parotid gland by administering isoproterenol (IPR) in vivo. We performed immunoperoxidase, immunofluorescence and immunoelectron microscopy. In the basal state, AQP5 was localized mainly in the apical membrane of the acinar cell. It was also present in the basolateral membrane to a lesser extent. When IPR was administered to mice, dot-like, vesicle-like and vacuole-like labeling for AQP5 was seen in the subapical regions by light microscopy. By immunoelectron microscopy, AQP5 was localized at both the apical and basolateral plasma membranes in the basal state. At 5 and 30 min after the IPR-administration, acinar lumen became enlarged and small invaginations formed by fusion of secretory granules were seen. AQP5 was positive along the apical plasma membrane and its small invaginations. At 60 min, large invaginations of the lumen were formed. AQP5 remained positive in the membrane of these large invaginations. At 6 h, large invaginations disappeared and AQP5 was localized in the apical plasma membrane. AQP5 was restricted to plasma membranes and continuous invaginations formed by the exocytosis of secretory granules. AQP5 was not detected in the cytoplasm. These observations show that AQP5 does not seem to be endocytosed during the membrane recycling process following the exocytosis.     

Fine dispersion of carbon black in fluorene‐based resin

The dispersion ability of fluorene‐based epoxy resin (FBE), bisphenol A based epoxy resin (PBE), fluorene‐based polyester (FBP), and polycarbonate (PC) in carbon black (CB) was evaluated. CB/FBE composite had a lower L value (reflectance, blackness) than that of CB/PBE composite, for the same CB content. Aggregations of CB in CB/FBE composites were much smaller than those in CB/PBE composites. The strong interaction between fluorene with cardo structure and CB resulted in a fine dispersion of CB in FBE. FBP had much higher dispersion ability of CB than PC. CB (50 wt%) was dispersed into FBP compared with the 10 wt% of CB dispersed in PC by melt blending. The effect of CB on the mechanical properties of FBP was much higher than that on PC due to fine dispersion of CB in FBP. The effect of CB addition on the T_g of FBP was also higher than that of CB on the T_g of PC. Computational simulation indicates that most stable energy between fluorene with a cardo structure and graphite structure was smaller than the energy between bisphenol A and graphite. It was also shown that the minimum energy appeared when the fluorene structure was almost parallel to the graphite plane. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers