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81.
Fujio Y Plashnitsa VV Breedon M Miura N 《Langmuir : the ACS journal of surfaces and colloids》2012,28(2):1638-1645
The carbon monoxide (CO) sensitivity of a mixed-potential-type yttria-stabilized zirconia (YSZ)-based tubular-type sensor utilizing a ZnCr(2)O(4) sensing electrode (SE) was tuned by the addition of different precious metal nanoparticles (Ag, Au, Ir, Pd, Pt, Ru and Rh; 1 wt % each) into the sensing layer. After measuring the electromotive force (emf) response of the fabricated SEs to 100 ppm of CO against a Pt/air-reference electrode (RE), the ZnCr(2)O(4)-Au nanoparticle composite electrode (ZnCr(2)O(4)(+Au)-SE) was found to give the highest response to CO. A linear dependence on the logarithm of CO concentration in the range of 20-800 ppm at an operational temperature of 550 °C under humid conditions (5 vol % water vapor) was observed. From the characterization of the ZnCr(2)O(4)(+Au)-SE, we can conclude that the engineered high response toward CO originated from the specific properties of submicrometer sized Au particles, formed via the coalescence of nanosized Au particles located on ZnCr(2)O(4) grains, during the calcining process at 1100 °C for 2 h. These particles augmented the catalytic activities of the gas-phase CO oxidation reaction in the SE layer, as well as to the anodic reaction of CO at the interface; while suppressing the cathodic reaction of O(2) at the interface. In addition, the response of the ZnCr(2)O(4)(+Au)-SE sensor toward 100 ppm of CO gradually increased throughout the 10 days of operation, and plateaued for the remainder of the month that the sensor was examined. Correlations between SEM observations and the CO sensing characteristics of the present sensor were suggestive that the sensitivity was mostly affected by the morphology of the Au particles and their catalytic activities, which were in close proximity to the ZnCr(2)O(4) grains. Furthermore, by measuring the potential difference (emf) between the ZnCr(2)O(4)(+Au) and a ZnCr(2)O(4) electrode, sensitivities to typical exhaust component gases other than CO were found to be negligible at 550 °C. 相似文献
82.
S. Iijima A. Nomura F. Mizukami S. Shin F. Mizutani 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(2):297-302
Spinel iron oxide (Fe3O4-γ-Fe2O3) particles were supported on microbeads of silica gel by the calcination of the silica gel base adsorbing citric acid and Fe3+ ions. The X-ray diffraction patterns and the57Fe Mössbauer spectra measured for the spinel iron oxide indicated that the particle size of the oxide was regulated by the mean pore diameter (4–82 nm) of the silica gel support employed. In the case of α-Fe2O3 particles prepared by using the same silica gel beads, it was revealed by the Mössbauer spectra and the electron micrographs that there were relatively large particles of the oxide on the surface of the beads, in addition to the particles in the silica gel micropores. 相似文献
83.
A new cascade reaction including formal [5?+?2] cycloaddition was developed. Treatment of homocinnamyl alcohol and Co2(CO)6-complexed arylpropynal with BF3·OEt2 resulted in the generation of hydrobenzocycloheptafuran having an alkyne-Co2(CO)6 complex. The reaction consists of 5-membered ring selective Prins cyclization and subsequent Friedel-Crafts cyclization. The cascade reaction was applied to a further multi-step cascade cyclization, which resulted in the formation of more complex polycyclic hydrofurans. 相似文献
84.
85.
K. Mizukami S. Y. Zhang H. S. Wu 《Journal of Optimization Theory and Applications》1995,85(3):727-739
The problem of the robust stability of large-scale dynamical systems including delayed states and parameter perturbations in interconnections is considered. By using algebraic Riccati equations and some analytical methods, some sufficient conditions on linear decentralized state feedback controllers are derived so that the systems remain stable in the presence of delayed states and parameter perturbations. Such conditions give some bounds on the perturbations of interconnections with delayed states and uncertain parameters, and result in a quantitative measures of robustness for large-scale dynamical systems including delayed states and uncertain parameters in interconnections. The results obtained in this paper are applicable not only to large-scale systems with multiple time-varying delays, but also to large-scale systems without exact knowledge of the delays, i.e., large-scale systems with uncertain delays. 相似文献
86.
David A. Pacheco Tanaka Margot A. Llosa Tanco Junya Okazaki Yoshito Wakui Fujio Mizukami Toshishige M. Suzuki 《Journal of membrane science》2008,320(1-2):436-441
Mesoporous YSZ–γ-Al2O3 membranes were coated on α-Al2O3 (Ø2 mm) tube by dipping the α-Al2O3 support tube into mixed sol consists of nano-size YSZ and bohemite particles followed by drying and calcination at 600 °C. Addition of bohemite in YSZ sol helped a good adhesion and uniform coating of the membrane film onto α-Al2O3 support. The quality of the mesoporous YSZ–γ-Al2O3 membranes was evaluated by the gas permeability experiments. The number of defects was minimized when the γ-Al2O3 content became more than 40%. Addition of γ-Al2O3 inhibited the crystal growth of YSZ, sintering shrinkage and distortion stress. Increase of calcination temperature and time results in the increase of pore size and N2 permeance. A hydrogen perm-selective membrane was prepared by filling palladium into the nano-pores of YSZ–γ-Al2O3 layer by vacuum-assisted electroless plating. Crystal growth of palladium was observed by thermal annealing of the membrane at 600 °C for 40 h. The Pd–YSZ–γ-Al2O3 composite membrane revealed improved thermal stability allowing long-term operation at elevated temperature (>500 °C). This has been attributed to the improved fracture toughness of YSZ–γ-Al2O3 layer and matching of thermal expansion coefficient between palladium and YSZ. Although fracture of the membrane did not occur, decline of H2 flux was observed when the membrane was exposed in 600 °C. This has been attributed to the agglomeration of palladium particles by crystal growth and dense packing into the pore networks of YSZ–γ-Al2O3 by elevation of temperature. 相似文献
87.
Summary
Schöniger's method for the microdetermination of halogen has been improved by using ammonium hydroxide solution as an absorbing solution instead of sodium hydroxide solution in order to simplify the after treatment. On boiling the absorbing solution, interfering ions can be removed together with excess ammonia. Ammonium halide which formes in the solution is titrated with AgNO3 solution in the presence of an adsorption indicator. Satisfactory results are obtained more rapidly.
Zusammenfassung Um die Weiterbehandlung der Absorptionslösung bei der Mikrobestimmung der Halogene nachSchöniger zu vereinfachen, wurde an Stelle von Natronlauge Ammoniaklösung verwendet. Durch Kochen der Absorptionslösung können störende Ionen zugleich mit dem Ammoniaküberschuß entfernt werden. Das in der Lösung entstandene Ammoniumhalogenid wird mit Silbernitrat in Gegenwart eines Adsorptionsindikators titriert. Bei verkürzter Analysendauer werden zufriedenstellende Ergebnisse erzielt.
Résumé On a amélioré la méthode deSchöniger pour le microdosage des halogénes en utilisant une solution d'ammoniaque comme absorbant à la place de la solution d'hydroxyde de sodium afin de simplifier le traitement ultérieur. En faisant bouillir la solution d'absorption on peut éliminer les ions gênants avec de l'ammoniaque en excés. On titre l'halogénure d'ammonium qui se forme en solution, par une solution d'AgNO3 en présence d'un indicateur d'adsorption. On a obtenu des résultats satisfaisants plus rapidement.相似文献
88.
Summary In the analysis of halogen and sulphur by the combustion method employing silver granules, electrostatic charges on the absorption funnel has been experimentally shown to cause inaccurate weighing of the funnel.An investigation of the influence of this phenomenon on blank values has been made, and possible countermeasures have been examined. By cooling the heated funnel in a desiccator saturated with moist air, the charges are removed and satisfactory analyses are obtained.
Zusammenfassung Bei der analytischen Bestimmung der Halogene und des Schwefels durch Verbrennung und Bindung an Silbergranellen verursachen, wie gezeigt werden konnte, elektrostatische Aufladungen der Absorptionsgefäße Wägefehler. Untersuchungen über den Einfluß dieser Erscheinung durch Bestimmung von Leerwerten wurden ausgeführt und die Möglichkeit von Gegenmaßnahmen geprüft. Durch Abkühlen der heißen Absorptionsgefäße in einem mit feuchter Luft gefüllten Exsiccator lassen sich die Aufladungen beheben und richtige Analysenergebnisse erzielen.
Résumé On a montré expérimentalement que dans l'analyse des halogènes et du soufre suivant la méthode de combustion avec granules d'argent, les charges électrostatiques sur le tube d'absorption étaient la cause d'une pesée inexacte de ce tube.On a fait une étude de l'influence de ce phénomène sur les valeurs à blanc et l'on a examiné la possibilité de mesures de l'éviter. En refroidissant le tube chauffé dans un dessicateur saturé d'air humide, on élimine les charges et l'on obtient des analyses satisfaisantes.相似文献
89.
Mizue Fujio Toshikazu Adachi Yoshifumi Shibuya Akihisa Murata Yuho Tsuno 《Tetrahedron letters》1984,25(40):4557-4560
Substituent effects of p-MeO and p-MeS groups deactivated by additional m-substituents in cumyl and α-phenylethyl solvolyses were studied to provide evidence for the higher resonance demand in the α-phenylethyl system. 相似文献
90.
采用柱层析等步骤纯化了根霉G7的羧甲基纤维素酶及β-葡糖苷酶,回收率分别为4.5%和19.6%.二种酶的最适酶反应温度都为55°C,并都能在较大pH范围内保持稳定,其中羧甲基纤维素酶具有很高的耐热性,在100°C水浴中保持1h也仍可检测出约20%的酶活性,最适反应pH为7.0~7.5;而β-葡糖苷酶的热稳性较差,其最适反应pH为5.0.该两种酶的分子量分别为2.5×104和9.5×104,而Km值则分别为7.40mgmL-1和0.213mgmL-1. 相似文献