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71.
Yoshinobu Fujishiro Motoyuki Miyata Masanobu Awano Kunihiro Maeda 《Journal of the American Ceramic Society》2003,86(12):2063-2066
The thermal conductivity of polycrystalline Al-doped ZnO was controlled through the fabrication of nanostructured polycrystalline materials, by hot-pressing nanosized Zn1– x Al x O ( x = 0.01, 0.02) particles, which were synthesized by a coprecipitation and spray-drying method. This process resulted in an improved thermoelectric power factor because of the nanosized Zn0.99 Al0.01 O particles of the polycrystalline products. The thermal conductivity also was decreased as a result of the formation of nanocrystalline Zn0.99 Al0.01 O. 相似文献
72.
The triad-level sequence analysis of poly(ethylene/1,4-cyclohexanedimethylene terephthalate) copolymer was reported in a solvent system of o-chlorophenol/deuterated chloroform mixture (50/50 v/v) at 80 °C using 600 MHz 1H NMR. The well-resolved alcoholic CH2 proton peak of the glycol units was observed, which made the detailed sequence analysis possible. The peaks of the cis- and trans-forms of the 1,4-cyclohexanedimethylene glycol units were split into the triad sequence in the chain and could be assigned by a comparison of the spectra with those of homopolymers and by an additional two-dimensional heteronuclear multiple bond correlation observation. The triad sequence distributions centered on 1,4-cyclohexanedimethylene glycol units were determined, which was independent of the cis- and trans-forms of the units and controlled according to Bernoullian statistics. 相似文献
73.
Jooho Moon Masanobu Awano Kunihiro Maeda 《Journal of the American Ceramic Society》2001,84(11):2531-2536
Well-defined La2 Sn2 O7 with a phase-pure pyrochlore structure was produced by hydrothermal synthesis at temperatures as low as 200°C. Production of phase-pure La2 Sn2 O7 requires a pH above 10, and higher pH accelerates the crystallization process. The synthesis produced spherical particles of average particle size ∼0.59 μm (±0.12) and surface area ∼14.1 m2 /g. SEM and TEM observation for morphologic evolution and kinetic analysis during crystallization indicated that La2 Sn2 O7 formation probably proceeds via a two-step reaction. First a transient dissolution–precipitation occurs. Then the primary crystallites aggregate because of their colloidal instability, and heterocoagulation with the lanthanum hydrous oxide precursor particles also occurs. The sluggish reaction rate at the later stage of reaction is characterized by an in situ transformation, where the soluble tin species is diffused through the porous La2 Sn2 O7 aggregates to react with entrapped lanthanum precursors. 相似文献
74.
Hironori Oda 《Coloration Technology》2001,117(5):257-261
The photofading behaviour of carthamin in cellulose acetate film was investigated. A contribution from singlet oxygen to that fading was suggested. Phenyl esters containing nickel sulphonate quenching groups were prepared and the protecting effect of these compounds towards the photofading of carthamin was examined in cellulose acetate film. It is proposed that nickel sulphonate derivatives of phenyl esters can be applied as effective stabilisers against the fading of natural dyes. 相似文献
75.
N‐Phenylmaleimide–N‐(p‐hydroxy)phenylmaleimide–styrene terpolymer (HPMS), carrying reactive p‐hydroxyphenyl groups, was prepared and used to improve the toughness of cyanate ester resins. Hybrid modifiers composed of N‐phenylmaleimide–styrene copolymer (PMS) and HPMS were also examined for further improvement in toughness. Balanced properties of the modified resins were obtained by using the hybrid modifiers. The morphology of the modified resins depends on HPMS structure, molecular weight and content, and hybrid modifier compositions. The most effective modification of the cyanate ester resin was attained because of the co‐continuous phase structure of the modified resin. Inclusion of the modifier composed of 10 wt% PMS (Mw 136 000 g mol?1) and 2.5 wt% HPMS (hydroxyphenyl unit 3 mol%, Mw 15 500 g mol?1) led to 135% increase in the fracture toughness (KIC) for the modified resin with a slight loss of flexural strength and retention of flexural modulus and glass transition temperature, compared with the values for the unmodified resin. Furthermore, the effect of the curing conditions on the mechanical and thermal properties of the modified resins was examined. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified cyanate ester resin system. © 2001 Society of Chemical Industry 相似文献
76.
Katsuki Kusakabe Shigeharu Morooka Hideaki Maeda 《Korean Journal of Chemical Engineering》2001,18(3):271-276
The purpose of this article is to demonstrate the applicability of microreactors for use in catalytic reactions at elevated
temperatures. Microchannels were fabricated on both sides of a silicon wafer by wet chemical etching after pattern transfer
using a negative photoresist. The walls of the reactor channel were coated with a platinum layer, for use as a sample catalyst,
by sputtering. A heating element was installed in the channel on the opposite surface of the reactor channel. The reactor
channel was sealed gas-tight with a glass plate by using an anodic bonding technique. A small-scale palladium membrane was
also prepared on the surface of a 50-Μm thick copper film. In the membrane preparation, a negative photoresist was spin-coated
and solidified to serve as a protective film. A palladium layer was then electrodeposited on the other uncovered surface.
After the protective film was removed, the resist was again spin-coated on the copper surface, and a pattern of microslits
was transferred by photolithography. After development, the microslits were electrolitically etched away, resulting in the
formation of a palladium membrane as an assemblage of thin layers formed in the microslits. The integration of the microreactor
and the membrane is currently under way. 相似文献
77.
Reuben Wu Karen A. Kozielski Patrick G. Hartley Eric F. May John Boxall Nobuo Maeda 《American Institute of Chemical Engineers》2013,59(7):2640-2646
Induction time distributions for gas hydrate formation were measured for gas mixtures of methane + propane at pressures up to 11.3 MPa using a high‐pressure automated lag time apparatus (HP‐ALTA). Measurements were made at subcooling temperatures between 4.3 and 13.5 K and, while isothermal induction times between 0 and 15,000 s were observed, the median isothermal induction times for the distributions ranged from 100 to 4000 s. A hyperbolic relationship between median induction time and subcooling was used to correlate the data. A graphical interpretation is presented that relates the two types of data that can be acquired by using the HP‐ALTA in one of two modes to study hydrate formation: induction time distributions at constant subcooling and formation temperature distributions observed during linear cooling ramps. The equivalence of these two modes provides a robust method for studying the variation of formation phenomena in different hydrate systems. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2640–2646, 2013 相似文献
78.
Blending a crosslinked high‐density polyethylene (xHDPE) enhances melt strength and strain hardening behavior in elongational viscosity of high‐density polyethylene (HDPE) to a great degree. Gel fraction of xHDPE has a stronger effect on the strain hardening than sol fraction, although sol fraction also enhances the strain hardening to some degree. Further, the xHDPE crosslinked by peroxide in a compression mold exhibits more pronounced effect than xHDPE by radiation, which is attributed to the difference in the amount of the gel fraction. The xHDPE, which enhances the strain hardening, has sparse crosslink points in the network. Moreover, it was found from linear viscoelastic measurements, such as oscillatory modulus and relaxation modulus, that the xHDPE is characterized as a critical gel, which was also supported by the result of tensile testing. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 73–78, 2002 相似文献
79.
Isao Kagomiya Shinji Matsumoto Ken-ichi Kakimoto Hitoshi Ohsato Hiroshi Sakai Yukinori Maeda 《Journal of the European Ceramic Society》2013,33(5):985-990
We investigated annealing effects of La1?xSrxMnO3 (x = 0–0.6) on electrical resistivity and the temperature coefficient of resistivity (TCR). The annealed samples’ resistivity was lower than those of non-annealed samples. For example, annealing changed the resistivity of x = 0.3 at 25 °C from 4.50 × 10?5 to 3.71 × 10?5 Ω m. Remarkable difference in TCR was observed after annealing, for x = 0.3, 0.45, and 0.5. For x = 0.3, the TCR after annealing was 4000 ppm/°C, which was 1250 ppm/°C greater than that before annealing. We investigated (1) crystal phase, (2) Mn average valence, (3) Mott insulator–metal transition temperature, and (4) microstructure. The microstructure was remarkably varied for annealed x = 0.3 and 0.5. The average grain size of the x = 0.3 increased from 1.60 up to 2.38 μm. Results show that annealing affects resistivity and TCR because of grain growth during annealing. 相似文献
80.
Oleg Vasylkiv Yoshio Sakka Yasuaki Maeda Valeriy V. Skorokhod 《Journal of the American Ceramic Society》2005,88(3):639-644
A uniformly aggregated 3 mol% yttria-stabilized tetragonal zirconia nano-powder (3Y-TZP) was prepared using thermal hydrolysis and the ultrasonic deagglomeration technique. The possibility of nano-engineering of Pt–3Y-TZP composite aggregates was studied. The as-synthesized Pt nano-particles (∼2 nm) were impregnated into zirconia nano-aggregates (20–45 nm). The morphology manipulation technique allowed production of the composite zirconia-based aggregates in which a significant fraction of the Pt particles was embedded into the densified zirconia aggregates. Using the colloidal technique and low-temperature (1150°C) sintering, we prepared the Pt-zirconia (0.5–1.5 wt% of platinum) nano-composites with average 3Y-TZP grain sizes of 120 nm, and with the platinum grains size in the range of 20–60 nm. The catalytic properties of composite Pt–3Y-TZP nano-composites were studied and described. 相似文献