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11.
Lida T Nakamori R Yabuta R Yada S Takagi Y Mano N Ikegawa S Goto J Nambara T 《Lipids》2002,37(1):101-110
A facile and efficient synthesis of the carboxyl-linked glucosides of bile acids is described. Direct esterification of unprotected
bile acids with 2,3,4,6-tetra-O-benzyl-d-glucopyranose in pyridine in the presence of 2-chloro-1,3,5-trinitrobenzene as a coupling agent afforded a mixture of the
α- and β-anomers (ca. 1∶3) of the 1-O-acyl-d-glucoside benzyl ethers of bile acids, which was separated effectively on a C18 reversedphase chromatography column (isolated yields of α- and β-anomers are 4–9% and 12–19%, respectively). Subsequent hydrogenolysis
of the α- and β-acyl glucoside benzyl ethers on a 10% Pd−C catalyst in acetic acid/methanol/EtOAc (1∶2∶2, by vol) at 35°C
under atmospheric pressure gave the corresponding free esters in good yields (79–89%). Chemical specificities such as facile
hydrolysis and transesterification of the acyl glucosides in various solvents were also discussed. 相似文献
12.
Pengjian Zuo Jun Zhao Yulin Ma Xinqun Cheng Pengfei Shi Tsutomu Takamura 《Electrochimica acta》2006,52(4):1527-1531
The SiMn-graphite composite powder was prepared by mechanical ball milling and its electrochemical performances were evaluated as the candidate anode materials for lithium ion batteries. It is found that the cyclic performance of the composite materials is improved significantly compared to SiMn alloy and pure silicon. The heat treatment of the electrodes is beneficial for enhancing the cyclic stabilities. The SiMn-20 wt.% graphite composite electrode after annealing at 200 °C has an initial reversible capacity of 463 mAh g−1 and a charge-discharge efficiency of 70%. Moreover, the reversible capacity maintains 426 mAh g−1 after 30 cycles with a coulomb efficiency of over 97%. The phase structure and morphology of the composite were analyzed by X-ray diffraction (XRD) and scanning electron microscopy. The lithiation/delithiation behavior was investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The composite materials appear to be promising candidates as negative electrodes for lithium rechargeable batteries. 相似文献
13.
A method has been developed to suppress the decomposition of propylene carbonate (PC) by coating graphite electrode foil with a layer of silver. Results from electrochemical impedance measurements show that the Ag-coated graphite electrode presents lower charge transfer resistance and faster diffusion of lithium ions in comparison with the virginal one. Cyclic voltammograms and discharge-charge measurements suggest that the decomposition of propylene carbonate and co-intercalation of solvated lithium ions are prevented, and lithium ions can reversibly intercalate into and deintercalate from the Ag-coated graphite electrode. These results indicate that Ag-coating is a good way to improve the electrochemical performance of graphitic carbon in PC-based electrolyte solutions. 相似文献
14.
Hiroaki Sakamoto Rie Futamura Ikuya Fujiwara Taichi Meboso Ning Li Eiichiro Takamura Takenori Satomura Shin-ichiro Suye 《应用聚合物科学杂志》2021,138(37):50937
Biofuel cells (BFCs) that produce electrical energy from organic resources through enzymatic reactions have been attracting significant attention. Owing to the high electrical conductivity of carbon nanotubes (CNTs), their modification on the electrode surface of a BFC is expected to increase the current, and their high specific surface area may be useful in increasing the power output. Previously, we constructed a biocathode by immobilizing multicopper oxidase from Pyrobaculum aerophilum (McoP) with a carbon nanotube binding peptide (CBP) sequence on the CNTs. This resulted in higher current densities than when using enzymes without CBP sequences. However, owing to the randomly stacked CNTs on the surface of the electrodes, their conductive properties were impaired and performance as biocathodes was poor. Herein, we constructed a biocathode in which single-walled CNTs (SWCNTs) were oriented one-dimensionally and McoP is immobilized on the surface of an SWNCT via CBP. The current density was successfully increased by two-fold by orienting the CNTs and orienting and immobilizing McoP on their surfaces. This technology provides insights into the development of biodevices with controlled orientation of both the SWCNTs and enzymes immobilized on their surfaces. 相似文献
15.
This paper reports a fundamental study of the stripe laminar flow pattern on a centrifugal microfluidic device with the goal of realizing a sedimentation-based, continuous mode particle separation technique. Microfluidic channels were designed with a concentrically integrated microchannel, and the patterning of the flow in the channel was investigated. A significant secondary flow was observed as a preliminary result. We conclude that the origin of this secondary flow was not the Dean force, because it was observed in a straight microchannel, but was not observed in curved channel during the spinning of the system at rest. The transition of the pattern was investigated using a simulation and experiment, and the flow pattern’s dependence on the rotational speed was determined, which suggested that the origin of the secondary flow was the Coriolis force. The significance of the secondary flow was controlled by adjusting the rotational speed of the disk, and the flow rate and laminar flow patterns were controlled by the stripe flow pattern. 相似文献
16.
Hitoshi Takamura Hiroshi Sugai Masato Watanabe Takehiro Kasahara Atsunori Kamegawa Masuo Okada 《Journal of Electroceramics》2006,17(2-4):741-748
The preparation and oxygen permeation properties of the (Ce0.8Pr0.2)O2−δ − x vol% MnFe2O4 composites, where x = 0 to 35, have been investigated. The samples were prepared by the Pechini method. In the case of Ce0.8Pr0.2O2−δ, an oxygen flux density of 6 μmol⋅cm−2⋅s−1 (L = 0.0247 cm) and the maximum methane conversion of 50% were attained at 1000∘C. Unlike composites consisting of Gd-doped CeO2 and MnFe2O4, the oxygen permeability of the (Ce0.8Pr0.2)O2−δ – x vol% MnFe2O4 composites was almost constant regardless of the volume fraction of MnFe2O4; however, the optimum volume fraction of MnFe2O4 was determined to be 5 to 25 in the context of the chemical and mechanical stabilities under methane conversion atmosphere.
In addition, the surface modification of the (Ce0.8Gd0.2)O2−δ – 15 vol% MnFe2O4 composite was performed by using the FePt nanoparticles. The catalyst loading of 2.8 mg/cm2 on the both side of the 0.3 mm-thick (Ce0.8Gd0.2)O2−δ – 15vol% MnFe2O4 composite increased the oxygen flux density from 0.30 to 0.76 μmol⋅cm−2⋅s−1 in the case of He/air gradients; however, the effect seems to be reduced in the case of high oxygen flux density caused by
a large pO2 gradient. Moreover, the Langmuir-Blodgett film of the FePt nanoparticles were successfully prepared on the tape-cast (Ce0.8Gd0.2)O2−δ – 15vol% MnFe2O4 composite. Hydrophobic treatments for the surface of the composite were crucial to achieve high transfer ratio for the deposition
of the LB film. 相似文献
17.
Application of an ultrahigh-resolution scanning electron microscope (UHS-T1) to biological specimens
Keiichi Tanaka Akira Mitsushima Yuzuru Kashima Takashi Nakadera Hitoshi Osatake 《Microscopy research and technique》1989,12(2):146-154
In 1985 we developed an ultrahigh-resolution scanning electron microscope with a resolution of 0.5 nm. It is equipped with a field emission gun and an objective lens with a very short focal length. In this study we report a survey of some different preparation techniques and biological specimens using the new scanning electron microscope. Intracellular structures such as cell organelles were observed surprisingly sharper than those observed by ordinary scanning electron microscopes. However, at magnifications over 250,000 X, platinum particles could be discerned as scattered pebbles on the surface of all structures in coated materials. Using an uncoated but conductively stained specimen, we successfully observed ribosomes on a rough endoplasmic reticulum at a direct magnification of 1 million. In these images some protrusions were recognized on the ribosomes. Ferritin and immunoglobulin G were used as samples of biological macromolecules. These samples were observed without metal coating and conductive staining. The ferritin particles appeared as rounded bodies without any substructure on the surface and immunoglobulin G as complexes of three-unit bodies. In the latter the central body might correspond to the Fc fragment and two side ones to Fab fragments. We assume that ultrahigh-resolution scanning electron microscopy is an effective means for observation of the cell fine structures and biological macromolecules. It will open a new research field in biomedicine. 相似文献
18.
Motonaka Kuroda Yumiko Kato Junko Yamazaki Naoko Kageyama Toshimi Mizukoshi Hiroshi Miyano Yuzuru Eto 《Food chemistry》2012
The determination of the kokumi peptide, γ-glutamyl-valyl-glycine (γ-Glu-Val-Gly) in raw scallop and processed scallop products was carried out using high pressure liquid chromatography–tandem mass spectrometry (LC/MS/MS). The detection of γ-Glu-Val-Gly was achieved using a multiple reaction monitoring (MRM) method. The optimised condition enabled the precise determination of γ-Glu-Val-Gly. Raw scallop contained 0.08 μg/g γ-Glu-Val-Gly, and the γ-Glu-Val-Gly levels in processed scallop products, such as dried-scallop and scallop extract, were measured to be 0.64 and 0.77 μg/g, respectively. This is the first report to confirm the existence of γ-Glu-Val-Gly in foodstuff. 相似文献
19.
Kazuo Nakajima Satoshi Ono Ryota Murai Yuzuru Kaneko 《Journal of Electronic Materials》2016,45(6):2837-2846
20.
Design criteria for gas entrainments (GE) from the liquid surface in a fast breeder reactor system were proposed in this paper for the two types of GE phenomena from a vortex dimple based on a computational fluid dynamics (CFD) method. The first gas entrainment phenomenon is a gas core extension directly to the outlet piping level, which induces large amount of GE to the flow system. The second is continuous bubble detachments from the tip of the vortex dimple. Based on CFD calculations for elemental experiments of the surface vortex, local CFD non-dimensional numbers were defined as the design criteria to prevent GE. In conclusion, it was found that the CFD non-dimensional numbers are useful for the design parameters of GE prevention. 相似文献