Contamination levels of mercury and cadmium in melon-headed whales (Peponocephala electra) from a mass stranding on the Japanese coast

Total mercury (T-Hg), methyl mercury (M-Hg), cadmium (Cd), selenium (Se), zinc (Zn) and copper (Cu) concentrations in the organs of melon-headed whales from a mass stranding on the Japanese coast were analyzed. The mean concentration of T-Hg in the liver (126+/-97 microg/wet g, n=13) was markedly higher than those in kidney (6.34+/-2.36 microg/wet g, n=12) and muscle (4.90+/-2.33 microg/wet g, n=15). In contrast, the mean concentration of M-Hg in the liver (9.08+/-2.24 microg/wet g) was similar to those in the kidney (3.47+/-0.91 microg/wet g) and muscle (3.78+/-1.53 microg/wet g). The mean percentage of M-Hg in the T-Hg found in the liver (13.1+/-10.3) was significantly lower than those in the kidney (58.3+/-15.0) and muscle (78.9+/-8.4). The molar ratio of T-Hg to Se in the liver was effectively 1.0, but those in the kidney and muscle were markedly lower. Conversely, the mean concentration of Cd was markedly higher in the kidney (24.4+/-7.4 microg/wet g) than in the liver (7.24+/-2.08 microg/wet g) and muscle (less than 0.05 microg/wet g). These results suggest that the formation of Hg-Se compounds mainly occurs in the liver after the demethylation of M-Hg, and Cd preferentially accumulates in the kidney of melon-headed whales.     

Optimization of amino acids production from waste fish entrails by hydrolysis in sub and supercritical water

A resource recovery technique using sub‐ and supercritical water hydrolysis was applied to convert waste fish entrails into amino acids. The effect of reaction parameters such as temperature and time necessary for the control of reaction towards optimum yield of amino acids was investigated. Results showed a maximum yield of total amino acids (137 mg/g dry fish) from waste fish entrails at T= 523 K (P = 4 MPa) and reaction time of 60 min in a batch reactor. Under supercritical conditions (e. g., T= 653 K, P = 45 MPa), the yield decreases due to rapid decomposition compared to production rate of amino acids. The results suggest operation of the system at short reaction time and mild temperature condition.     

甘蔗渣纤维增强聚丙烯复合材料的制备和力学性能

利用注射成型制备了甘蔗渣纤维增强聚丙烯复合材料, 分析了纤维质量分数、 注射成型条件以及添加物对复合材料力学性能的影响。结果表明, 随着纤维质量分数的增加, 材料的弯曲模量呈递增趋势。由于甘蔗渣纤维热降解的发生, 材料的力学性能随筒体温度的增加呈下降趋势。在模具温度90℃、 注射间隔时间30s、 不同的筒体温度185℃和165℃的成型条件下, 材料的弯曲性能和冲击强度分别呈现最大值。添加了马来酸酐改性聚丙烯后, 材料的弯曲强度和冲击强度得到了提高。      

Studies on the molecular weight dependence of tacticity of anionically prepared PMMAs by on-line GPC/NMR

Summary Several PMMA samples prepared in toluene with anionic initiators such as t-C₄H₉MgBr, n-C₄H₉MgCl, 1,1-diphenylhexyllithium, t-C₄H₉Li and t-C₄H₉Li(n–C₄H₉)₃Al complex were analyzed by the on-line GPC/NMR method using a 500 MHz ¹H NMR spectrometer as a real-time detector of GPC. The molecular method for a short time (60 min per sample) with a small amount of the sample (1 mg). The plots of intensities of the -methyl proton resonances due to mm- and rr-triads against elution time showed the variation of tacticity with molecular weight of the PMMA. On the basis of the results, the natures of active species in the polymerizations were discussed.     

Implementation and evaluation of a remote authentication system using touchless palmprint recognition

When a cellular phone is lost or stolen, it may be used improperly or the personal information may be stolen from it by a malicious user. Biometric authentication such as palmprint recognition is the strongest of the personal authentication technologies designed to prevent such misuse. In biometric authentication, when compared with a local authentication model, a remote authentication model has several advantages such as direct authentication and authentication levels. Ito et al. proposed several palmprint recognition schemes using correspondence matching based on the phase-only correlation. However, these schemes require a palmprint image to be captured with the hand touching the dedicated device, while palmprint images must be captured without such physical contact when using cellular phones. Thus, these schemes cannot be applied to cellular phones since there are large positioning gaps and large differences in brightness and distortion between the images. Furthermore, they have not been implemented in cellular phones and their performances have not been evaluated either. In this paper, we adopt a remote authentication model from the two types of biometric authentication incorporating the above advantages and propose a remote system between a cellular phone and an authentication server. We implement the proposed system using two different types of Android terminal as the terminal on the user side. We also show the validity of the proposed system by examining and confirming the accuracy and processing time. We furthermore discuss the problem of an impersonation attack on the proposed system and consider solutions to this problem from the viewpoints of security and usability. Then, we adopt a palmprint recognition scheme as a biometric authentication scheme and, in particular, use a palmprint recognition algorithm that incorporates Yörük et al.’s preprocessing technique to Ito et al.’s and Iitsuka et al.’s schemes.     

Forced flow boiling heat transfer of liquid hydrogen for superconductor cooling

Heat transfer from inner side of a heated vertical pipe to liquid hydrogen flowing upward was first measured at the pressure of 0.7 MPa for wide ranges of flow rates and liquid temperatures. The heat transfer coefficients in non-boiling regime for each flow velocity were well in agreement with the Dittus–Boelter equation. The heat fluxes at the inception of boiling and the departure from nucleate boiling (DNB) heat fluxes are higher for higher flow velocity and subcooling. It was found that the trend of dependence of the DNB heat flux on flow velocity was expressed by the correlation derived by Hata et al. based on their data for subcooled flow boiling of water, although it has different propensity to subcooling.     

A method using an on-line digital computer for the improvement of resolution of backscattered electron images

In principle, the resolution of backscattered electron (BSE) images can be little improved, even though an infinitely small beam size is achieved by various improvements in the intrinsic instrument. In order to circumvent this problem, a method is proposed which utilizes an on-line digital computer for the image recording and processing. The major image-processing tools are reduction, expansion, super-imposition with matching of the images, and high-emphasis filtering in the Fourier domain. By using various combinations of these techniques, the resolution of BSE images has been significantly improved. The validity of these improved images has been confirmed. In the case of a BSE image with too wide a dynamic range, both the present method and digital homomorphic filtering provide successful results.     

Accumulation and mother-to-calf transfer of anthropogenic and natural organohalogens in killer whales (Orcinus orca) stranded on the Pacific coast of Japan

Blubber samples were analyzed for anthropogenic and natural persistent organohalogens in nine killer whales (Orcinus orca) stranded on the northern coast of Japan in 2005. Anthropogenic organohalogens were dominated by DDTs (40-240 µg/g lipid weight (lw)), PCBs (19-68 µg/g lw), and chlordanes (trans-nonachlor, 15-80 µg/g lw). Polybrominated diphenyl ethers (PBDEs) were detected at a range of 0.22-0.64 µg/g lw (BDE-47, 42-74% of ΣPBDE). For natural organohalogens, mixed halogenated dimethylbipyrroles (Br₄Cl₂-DBP, 6.4-26 µg/g lw), heptachlorinated methylbipyrrole (Cl₇-MBP, 0.5-1.9 µg/g lw), two methoxylated tetrabromodiphenyl ethers (6-MeO-BDE47, 0.11-0.58 µg/g lw; 2'-MeO-BDE68, 0.02-0.06 µg/g lw), and dimethoxylated tetrabromobiphenyl (2,2'-diMeO-BB80, 0.06-0.20 µg/g lw) were present. These concentrations in the blubber were higher in calves than in lactating females, indicating that large quantities of the persistent organohalogens transferred from the mother to the calf through lactation. The mother-to-calf transfer ratios of PCBs and PBDEs were significantly decreased with increasing number of halogen substituents, suggesting that higher halogenated congeners are less transferable.     

Resist-less patterning on SiO2 by combination of X-ray exposure and vapor HF etching

We succeeded in a resist-less patterning of SiO₂/Si substrates by a combination of X-ray exposure and vapor hydrogen fluoride (HF) etching. A 2 μm thick SiO₂ layer was formed on a Si substrate by employing a thermal oxidation process. An X-ray mask consisted of a 1 μm thick Ta absorber on a 2 μm thick Si₃N₄ membrane mounted on a 1 mm thick Si frame, and a honeycomb pattern where 640 nm diameter circle dots arranged in the corners of a hexagon with a pitch of 960 nm was processed. X-ray exposure experiments were carried out on a beamline BL-4 with a peak photon energy of 2 keV at the TERAS synchrotron radiation (SR) facility. When a dose energy was 750 mAh, the transfer of the patterns was confirmed, although irradiations with different dose energy were also conducted. Moreover, heating temperatures and total etching times of SiO₂/Si substrates in vapor HF etching were changed, and the shapes of etched patterns were observed by scanning electron microscope. It was learnt that an appropriate etching time existed between 30 and 60 min. Moreover, we observed discoloration of irradiated area by SR; and this seemed to be caused by changes in the etching rate of SiO₂/Si substrates that led to the development of resist-less patterning technique.     

Self-crack healing ability and strength recovery in ytterbium disilicate/silicon carbide nanocomposites

The SiO₂ volatility and SiC recession in hydrocarbon-rich combustion atmosphere is the main problem of SiC-reinforced ceramics when they are utilized as coating materials for gas turbine blades. The composite of Yb₂Si₂O₇-Yb₂SiO₅/SiC is expected as a self-crack healing material that can avoid this problem because the monosilicate can react with the SiO₂ glass to form disilicate and hence further reinforce the composite. In this study, the composites, fabricated with various morphology of SiC nanofillers, were precracked and then heat-treated in an oxidizing environment to activate their crack healing behavior. The healing effect as a function of filler morphology and annealing time was investigated. Healing mechanism and future applications of these composites were also discussed.