Effects of Porous Structure of the Auxiliary Electrode on the CO2 Sensing Properties of a NASICON-based Sensor

Structural effects of the auxiliary electrode layer on the CO_2 sensing properties of NASICON (Na_3Zr_2Si_2PO_) solid electrolyte sensors have been investigated. The sensor with a macroporous Li_2CO_3-BaCO_3-based auxiliary layer showed faster CO_2 response and recovery and a smaller EMF drift against a humidity change than those observed for the sensor equipped with a dense auxiliary layer. The CO_2 response of the present sensors was slightly larger than the theoretical one. This suggests the existence of some impurities capable of reacting with CO_2 in the auxiliary layer prepared in the present study.Nagasaki Symposium on Nano-Dynamics 2008 (NSND2008) 平成20年1月29日(火)於長崎大学 Poster Presentatio

Fabrication of Highly Porous Alumina-Based Ceramics with Connected Spaces by Employing PMMA Microspheres as a Template

Highly porous alumina-based ceramics were fabricated by a slip casting method by employing polymethylmethacrylate (PMMA) microspheres having different diameters as a template and MgO or SiC powder as a sintering aid and subsequent calcination at 1600°C. Spherical pores reflecting the morphology of the PMMA microspheres could be fabricated. In addition, the formation of much smaller connected space among the pores was observed on the pore\u27s inner walls of all ceramics. In this method, porous structure, for example, pore diameter, shape (open or closed), and mechanical properties, could be controlled by varying the particle size of PMMA microspheres and its concentration in alumina-based slurries. Highly porous and mechanically strong alumina-based ceramics having an open porosity of 62, a connected space size of 1.3 m, and a compressive strength of 147.6 MPa could be fabricated by employing PMMA microspheres with a mean particle size of 22.6 m and an appropriate amount of SiC

H2S Sensing Properties and Mechanism of Macroporous Semiconductor Sensors

Macroporous (mp-) In2O3-based films with and without 1 wt% CuO loading were fabricated by a modified sol-gel technique employing polymethylmethacrylate microspheres as a template and their sensor responses to H2S and the reaction behavior of H2S over the sensor materials were investigated. Introduction of macropores into an In2O3 film and simultaneous loading of CuO on the In2O3 surface were enormously effective in improving the H2S response. The large surface area of mp-In2O3 loaded with CuO, which increased the reactivity of CuO with H2S, is probably the most important factor to enhance the H2S response.214th ECS Meeting : Honolulu, HI, October 12 - October 17, 200

Fabrication of porous alumina ceramics having cell windows with controlled size by PMMA template method

Highly porous alumina compacts have been prepared by filling alumina slurry into opening of a specially designed template block prepared by cross-linked (cl-) polymethylmethacrylate (PMMA) microspheres (mean particle size: 98.6 μm) under reduced pressure, followed by firing to remove the template and then sintering at 1600 °C. The template blocks were prepared by utilizing cl-PMMA and acetone solution dissolving noncrosslinked (Ncl-) PMMA as an adhesive to make partial connection among the cl-PMMA microspheres. Furthermore, the effects of the addition of other chemicals (two types of triblockcopolymers and a nonionic surfactant) to the Ncl-PMMA adhesive solution were tested to improve the wettability of the solution to cl-PMMA and then to control the cell windows among the cl-PMMA-originated cells after the firing. By employing the template block, prepared with the adhesive solution containing an appropriate amount of triblockcopolymer, a highly porous alumina compact having an open porosity of 77.2%, a mean cell window diameter of 28.8 μm, and strong alumina skeleton could be fabricated.The original publication is available at www.springerlink.co

Characterizations of Polystyrene-Based Hybrid Particles Containing Hydrophobic Mg (

Polystyrene (PS)-based hybrid particles containing a large amount of Mg(OH)2 powder treated with methylhydrogen polysiloxane (MHS) were fabricated by a bulk and subsequent suspension two-step polymerization method. All the particles fabricated showed spherical shape and their particle sizes were about 500 μm, irrespective of the additive amount of the Mg(OH)2 powder modified with MHS (ST-1). The actual content of ST-1 powder incorporated inside each kind of hybrid particle was almost the same as that in the raw mixture, and agglomeration of ST-1 powder was hardly observed inside the hybrid particles. The compressive strength of the hybrid particles remained almost unchanged, even when the ST-1 powder content increased from 10 to 50 phr. Furthermore, a composite fabricated by employing the hybrid particles achieved homogenous distribution of ST-1 powder and showed a higher oxygen index than that of a composite fabricated by directly mixing of PS pellets and ST-1 powder

Microstructural effects of mesoporous SnO_2 powders on their H_2 sensing properties

Various mesoporous tin oxide (m-SnO_2) powders were prepared by combinations of two kinds of surfactants and tin sources. Specific surface area and pore volume of m-SnO_2 prepared from C_16PyCl ((C_5H_5NC_H_)Cl?H_2O) and Na_2SnO_3?3H_2O (m-SnO_2(1)) were larger than those of m-SnO_2 prepared from AOT (C_H_O_7SNa) and SnCl_4?5H_2O (m-SnO_2(2)). However, the specific surface area of m-SnO_2(1) decreased dramatically by grinding, while m-SnO_2(2) with small secondary agglomerates showed a little decrease in the specific surface area and better H_2 response with low resistance in air than m-SnO_2(1), especially at low operating temperature.Nagasaki Symposium on Nano-Dynamics 2008 (NSND2008) 平成20年1月29日(火)於長崎大学 Poster Presentatio

Hydrogen Sensing Properties of an Anodized TiO2 Film Equipped with a Pd-Pt Electrode

An anodized TiO2 sensor equipped with a Pd-Pt electrode was subjected to heat treatment in air (air-treated) and additionally in N2 (N2-treated), and then its responses to H2 balanced with air or N2 were investigated under dry and wet conditions. Among the conditions tested, the N2-treated sensor showed the largest H2 response in dry N2 atmosphere. But, H2 response of the air-treated sensor increased with the existence of water vapor, while that of the N2-treated sensor decreased with the existence of water vapor. As a result, H2 response of the air-treated sensor in wet air was quite comparable with that of the N2-treated sensor in wet N2. Thus, it was revealed that the existence of water vapor reduced the pretreatment- and measurement atmosphere-dependent H2 response of the sensor.214th ECS Meeting : Honolulu, HI, October 12 - October 17, 200

The stereochemistry of ethylene-1,2-d2 epoxidation over silver catalysts

The stereochemistry of the catalytic epoxidation of cis-ethylene-1,2-d2 to ethylene oxide over four unsupported and two supported silver catalysts as well as over Ag2O and AgO was studied. Variations of the stereochemistry with reaction composition including addition of C4H2Cl2 to moderate the catalyst and the use of N2O as the oxidant were also explored. Equilibration in the product ranged between 57 and 99%. A correlation in the equilibration with extent of oxidation of the surface was proposed. Several models were discussed which could rationalize the observed partial equilibration and the sensitivity of the randomization kinetics to certain reaction variables such as oxygen concentration or addition of C2H4Cl2 or N2O but not others such as temperature and catalyst selectivity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23136/1/0000060.pd

The stereochemistry of propylene-1,2-d2 epoxidation over silver catalysts

The stereochemistry of the epoxidation of cis-propylene-1,2-d2 to propylene oxide over three unsupported and one supported silver catalysts as well as over Ag2O and AgO was studied by microwave spectroscopy. Variations of the stereochemistry with N2O as the oxidant and with catalysts heavily moderated by C2H4Cl2 were also explored. In the absence of Cl moderators, the equilibration in the product ranged between 66 and 99% and was similar to a previous study with ethylene. Unlike ethylene, the use of Cl moderators had a large effect and equilibration varied between 37 and 65%. Substitution of methyl hydrogen atoms with deuterium, where trans-propylene-1,2,3,3,3-d5 was used, did not change the equilibration kinetics even though the selectivity was increased. Three theses are developed from the results. (1) The predominant epoxidation mechanisms for ethylene and propylene are similar for unmoderated catalysts. (2) The randomization kinetics upon epoxidation are uncoupled from the parallel production of CO2. (3) Chloride moderation alters the randomization kinetics for propylene perhaps by stabilizing a secondary radical or otherwise increasing the rotational barrier about the C---C bond of an adsorbed intermediate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24326/1/0000593.pd

Altered distribution of plasma PAF-AH between HDLs and other lipoproteins in hyperlipidemia and diabetes mellitus

Platelet-activating factor acetylhydrolase (PAF-AH) is a phospholipase A2 associated with lipoproteins that hydrolyzes platelet-activating factor (PAF) and oxidized phospholipids. We have developed an ELISA for PAF-AH that is more sensitive than previous methods, and have quantified HDL-associated and non-HDL-associated PAF-AH in healthy, hyperlipidemic, and diabetic subjects. In healthy subjects, plasma total PAF-AH concentration was positively correlated with PAF-AH activity and with plasma total cholesterol, triacylglycerol, LDL cholesterol and apolipoprotein B (apoB) concentrations (all P < 0.01). HDL-associated PAF-AH concentration was correlated positively with plasma apoA-I and HDL cholesterol. Subjects with hyperlipidemia (n = 73) and diabetes mellitus (n = 87) had higher HDL-associated PAF-AH concentrations than did controls (P < 0.01). Non-HDL-associated PAF-AH concentration was lower in diabetic subjects than in controls (P < 0.01). Both hyperlipidemic and diabetic subjects had lower ratios of PAF-AH to apoB (P < 0.01) and higher ratios of PAF-AH to apoA-I (P < 0.01) than did controls. Our results show that the distribution of PAF-AH mass between HDLs and LDLs is determined partly by the concentrations of the lipoproteins and partly by the mass of enzyme per lipoprotein particle, which is disturbed in hyperlipidemia and diabetes mellitus