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61.
62.
Sea urchin gonads are highly priced sushi foodstuff “Uni” in Japanese traditional food, but after removal of them the residual shells with spines are dumped as waste. However, sea urchin shells contain naphthoquinone pigments with several phenolic hydroxyl groups, which were expected to act as potent antioxidant substances by donating hydrogens. Our previous study has evaluated their antioxidant ability to depress lipid peroxidation. This study examined other antioxidant property of the pigments from purple sea urchin shells, which possess larger amount of pigments than those of red and green sea urchins. The pigments as well as known antioxidant, α-tocopherol, exhibited 1,1-diphenyl 2-picryhydrazyl (DPPH) radical scavenging ability. Superoxide anion radical and hydrogen peroxide were also scavenged while hydroxyl radical, one of the most reactive oxygen species, was not significantly inhibited. However, because the pigments had significant activity to scavenge hydrogen peroxide and superoxide anion radical that could be in vivo precursors of hydroxyl radical, sea urchin pigments would be able to depress the generation of its related active oxygen radical species. These results suggested that sea urchin shells, which are still regarded as food waste, would be a new bio-resource for obtaining natural antioxidant. 相似文献
63.
We determined phase equilibria in the Co-rich Co-Al-W-Ti quaternary system at a temperature range between 900 °C and 1200 °C with a close attention to the thermodynamic stability of the γ′-Co3(Al, W, Ti) (L12) phase, based on micro-structure observation and electron microprobe analysis on bulk alloy samples heat-treated for periods up to 2000 h. In the quaternary system the single phase field of γ′ extends from the Co-Ti binary edge to a composition of Co-5Al-8.5W-8Ti (in at.%) at 900 °C. At the tip of the single phase field, the γ′ phase is in equilibrium with the γ-Co (A1), Co2AlTi (L21) and Co3W (D019) phases. The constructed vertical section of phase diagram between Co-9.4Al-9.6W and Co-16.5Ti indicates that there is a narrow composition range around Co-4.5Al-5.4W-7.5Ti in which the γ single phase field exists at high temperatures above 1200 °C and two-phase of γ+γ′ is thermodynamically stable at low temperatures below 1100 °C. 相似文献
64.
Koji Sugano Yuki Uchida Osamu Ichihashi Hideo Yamada Toshiyuki Tsuchiya Osamu Tabata 《Microfluidics and nanofluidics》2010,9(6):1165-1174
Gold nanoparticles with diameters of a few tens of nanometer and a narrow size distribution were synthesized using a pulsed
mixing method with a microfluidic system which consists of a Y-shaped mixing microchannel and two piezoelectric valveless
micropumps. This mixing method enables control of the mixing speed of gold salts and reducing agent by changing the switching
frequency of the micropumps, which was our focus to improve the particle size distribution, which is an essential parameter
in gold nanoparticle synthesis. In the proposed method, the mixing time was inversely proportional to the switching frequency
and the minimum mixing time was 95 ms at a switching frequency of 200 Hz. During synthesis experiments, the mean diameter
of the synthesized gold nanoparticles was found to increase, and the coefficient of variation of particle size was found to
decrease with decreasing mixing time. We successfully improved the coefficient of variation to less than 10% for a mean diameter
of around 40 nm. 相似文献
65.
By applying square wave AC voltage to the Au source electrode of tetracene based field-effect transistor (FET), electroluminescence (EL) was obtained. The results suggest that electrons and holes were injected alternately from the source electrode and recombined each other, and lead to the EL. This type of EL was localized at the interface between the source electrode and tetracene, and enhanced periodically with two relaxation times in accordance with the applied AC voltage cycle. We modeled the carrier behavior in the FET and explained the decay of EL, taking into account the space charge field contribution. Finally, using an AC voltage superposed on DC bias voltage, it was shown that electron injection was prompted only by space charge field. 相似文献
66.
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68.
Koichi Hatada Tatsuki Kitayama Kinzo Fujikawa Koji Ohta Heimei Yuki 《Polymer Bulletin》1978,1(2):97-102
Summary Copolymer of methyl methacrylate-d8(M1) with a small amount of trityl methacrylate(M2) was radically prepared in tetrahydrofuran and converted into the copolymer of methyl methacrylate-d8 with a small amount of undeuterated methyl methacrylate by the selective hydrolysis of the trityl group and subsequent methylation with diazomethane. From the 1H NMR spectrum of the derived copolymer the assigned coisotactic parameters 12 and 21 were determined to be 0.14 and 0.61, respectively. This may be the first example of the unequivocal determination of assigned configurational parameters in cross propagation for copolymerization. 相似文献
69.
Hisamoto H Shimizu Y Uchiyama K Tokeshi M Kikutani Y Hibara A Kitamori T 《Analytical chemistry》2003,75(2):350-354
Here we report a design and synthesis of a chemically functional polymer membrane by an interfacial polycondensation reaction and multilayer flow inside a microchannel. Single and parallel dual-membrane structures are successfully prepared by using organic/aqueous two-layer flow and organic/aqueous/organic three-layer flow inside the microchannel followed by an interfacial polycondensation reaction. By using the inner-channel membrane, permeation of ammonia species through the inner-channel membrane is successfully achieved. Furthermore, horseradish peroxidase is immobilized on one side of the membrane surface to integrate the chemical transform function onto the inner-channel membrane. Here substrate permeation through the membrane and subsequent chemical transformation at the membrane surface are realized. The polymer membrane prepared inside the microchannel has an important role in ensuring stable contact of different phases such as gas/liquid or liquid/ liquid and the permeation of chemical species through the membrane. Furthermore, membrane surface modification chemistry allows chemical transformation of permeated chemical species. These methods are expected to lead to development of complicated and sophisticated chemical systems involving membrane permeation and chemical reactions. 相似文献
70.
Hiromi?YoshidaEmail author Kyoko?Matsuda Yuki?Hirakawa Yoshiyuki?Mizushina 《Journal of the American Oil Chemists' Society》2003,80(7):665-674
To clarify the effects of microwave roasting on the distribution of tocopherols and FA of phospholipids within soybeans, whole
soybeans (Glycine max) were treated by microwave and further evaluted as compared to a raw sample. Tocopherol homologs, measured using HPLC, and
phospholipid profiles, quantified with GC, were determined in the seed coat, the embryonic axis, and selections of cotyledons
separated from three cultivars. The tocopherols were predominantly detected in the axis, followed by the cotyledons, and then
very little in the coat. As much as 25% of the individual tocopherols originally present in the coat were lost at 12 min of
roasting, whereas <25% was lost in the cotyledons and the axis after 20 min of roasting. The greatest rate of phospholipid
loss (P<0.05) was observed in PE, followed by PC and PI, and their changing patterns were more pronounced in the coat than in the
cotyledons or the axis. Thus, tocopherol content and phospholipid profiles change with microwave roasting according to tissue. 相似文献