NOx Storage-Reduction Three-Way Catalyst with Improved Sulfur Tolerance

The NO _x storage-reduction catalyst (NSR catalyst) is poisoned by SO₂ caused by fuel sulfur, thus its activity is reduced. In order to improve the NSR catalyst, the sulfur poisoning phenomenon has been analyzed. Based on this result, we developed TiO₂ and Rh/ZrO₂ to promote the sulfur desorption. The developed catalyst has made remarkable progress in its sulfur tolerance, about 50% improvement in NO _x purification performance compared with the conventional one.     

Synthesis and property of hydrogel membranes consisting of fumaramate with phosphorylcholine group

Fumaramate bearing a phosphoryl choline group, isopropyl‐2‐[2′‐(trimethylammonium) ethyl phosphoryl] ethyl fumaramate (IPTPFA), was radically copolymerized with 2‐hydroxyethylmethacrylate (HEMA) in the presence of various crosslinking agents, water, and 2,2′‐azobis(isobutyronitrile) to obtain hydrogel membranes. The obtained hydrogel membranes adsorbed bovine serum albumin (BSA) much less than those of poly(HEMA), and the values of water content (H) were higher than those of poly(HEMA). The values of tensile strength and tensile elongation of the hydrogel were 68.4 g/mm² and 239%, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2552–2557, 2004     

Syntheses and biodegradability of benzylated waste pulps and graft copolymers from PBzs and L‐lactic acid

Benzylated waste pulps (PBzs) were synthesized from treated waste pulp (Pulp), and benzyl chloride with phase transfer catalyst (PTC), and graft copolymers (PBz‐g‐LA) were synthesized from PBzs and L‐lactic acid (LA). Thermal properties, solubility, crystallinity, and biodegradability of the obtained PBzs and graft copolymers were investigated. PBzs with the degree of substitution (DS) higher than 1.5 showed T_g and T_m in DSC measurement. All PBz‐g‐LA exhibited no T_m. However, the graft copolymers obtained from lower DS PBzs having no T_g, exhibited T_g. The solubility of PBzs enhanced with increasing DS, and the crystallinity of PBzs reduced with increasing DS because of hydrophobicity and steric effect of benzyl groups. The solubility of graft copolymers was similar to that of original PBzs. Biodegradation tests for PBzs, Pulp, and graft copolymers were performed using cellulase in 0.1 M acetate buffer solution (pH 5.5) at 37°C. All samples showed biodegradability though the biodegradation rate decreased with increasing DS of PBz. In PBz‐g‐LA, the initial biodegradation rate was faster than that of original PBz because of hydrolysis of LA units. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2658–2664, 2004     

Efficient Photocatalytic Decomposition of Glucose,Starch, and Cellulose to CO<Subscript>2</Subscript> Using a Mesoporous Semiconductor Thin Film

Abstract  

UV light-activated highly efficient photocatalytic decomposition of aqueous glucose and polysaccharides (starch and cellulose) to CO₂ was successfully achieved by using a mesoporous TiO₂ thin film coated on a fluorine-doped transparent conductive glass (FTO). The external quantum efficiency (η) of 0.08 (=8%) was obtained for glucose photodecomposition at neutral pH based on the total incident UV light, and the internal quantum efficiency (η′) was 8 (=800%) based on the photon that was effective for activating the reactant, demonstrating that the major decomposition mechanism is dark auto-oxidation of the activated reactant by O₂. Glucose gave η′ values of 19 at pH 12 and 25 at pH 2 demonstrating that when a glucose molecule was once activated by one photon, the molecule can undergo auto-oxidative decomposition to CO₂ at these pH under dark. Water-soluble starch was also photodecomposed completely to CO₂ with estimated η′ value of 8.6. Water-soluble carboxymethyl cellulose (CMC) also underwent decomposition to CO₂ with similar efficiency of η′ = 5. Solid state cellulose powders could be photodecomposed to CO₂ by sandwiching them between FTO-coated TiO₂ thin films.     

Impact of Crystalline Phase of Ni-FUSI Gate Electrode on Bias Temperature Instability and Gate Dielectric Breakdown of HfSiON MOSFETs

We investigated the influences of gate metals (n⁺/p⁺ poly-Si, Ni silicide (NiSi), Ni₃Si) on the time dependent dielectric breakdown (TDDB) reliability and negative/positive bias temperature instability (NBTI/PBTI) of phase-controlled Ni-full-silicide (Ni-FUSI)/HfSiON/SiO ₂ FETs. The TDDB reliability of NiSi-electrode n-FETs was comparable to that of n⁺-poly-Si-electrode n-FETs. However, further Ni enriching of the electrode to Ni₃Si degraded the reliability. A degradation of the base SiO₂ layer seems to have been responsible for this. A higher compressive strain was observed for the Ni₃Si sample, which may have caused the degradation of the bottom SiO₂. In contrast, the TDDB reliability of p-FETs improved much by using Ni₃Si. We attribute this improvement to the lower cathode energy and/or the absence of boron in the gate electrode. The PBTI of the n-FETs was negligible and was not degraded by Ni enrichment of the gate electrode and additional annealing, suggesting that HfSiON was stable against the Ni-FUSI process. The threshold voltage (V_T) shift in NBTI of p-FETs did not depend much on the gate materials. The major component of the V _T shift in NBTI, however, was changed by Ni enriching from the generation of interface traps to the trapping of holes by the HfSiON bulk     

Efficient phenol removal of wastewater from phenolic resin plants using crosslinked cyclodextrin particles

Removal of phenolic compounds from a raw industrial wastewater from phenolic resin processing, of which the components are phenol (8.9 wt%), m‐ and p‐cresols (0.33 wt%), and xylenols (0.044 wt%), was carried out by using crosslinked cyclodextrin particles as a sorbent. A series of sorbents was prepared by varying the combination of cyclodextrin (CyD), β‐CyD, γ‐CyD, Mix‐CyD (α‐CyD:β‐CyD:γ‐CyD:dextrin = 30:10:10:50 wt/wt), the crosslinker, hexamethylene diisocyanate (HDI) or toluene‐2,6‐diisocyanate, and their molar ratio in the reaction batch. The removal of the phenolic compounds from raw industrial wastewater was an instantaneous process and was completed within about 5 min. The best removal efficiency was obtained by the crosslinked β‐CyD with HDI in a 1:8 molar ratio or the crosslinked Mix‐CyD with HDI, also in a 1:8 molar ratio. The prepared sorbents were efficiently regenerated by elution of the adsorbed phenols from the crosslinked polymers with methanol. Copyright © 2006 Society of Chemical Industry     

Effects of lithium salts on ASR gel composition and expansion of mortars

Suppression of alkali-silica reaction (ASR) expansion in mortar and concrete by the addition of lithium salts has been confirmed by some workers. It has been revealed that lithium hydroxide tended to reduce the reaction between sodium or potassium hydroxide and reactive silica, and that the ASR gel incorporating lithium was less expansive. However, it has not been reported how the addition of a lithium salt influenced the composition of the ASR gel. The calcium in ASR gel is considered to play an important role in the expansion of the gel. Thus, it is significant to characterize ASR gel composition in mortars containing lithium salts by BSE-EDS analysis. This study aims to discuss the mechanisms of suppression of ASR expansion in mortar by lithium salts from the viewpoint of ASR gel composition. The average CaO/SiO₂ ratio in ASR gels decreased with increasing amount of added lithium salts. It should be noted that the extent of variations in the CaO/SiO₂ ratio in ASR gels significantly decreased with increasing amount of lithium salts. The addition of relatively small amounts of LiOH and Li₂CO₃ resulted in increased expansion. We also obtained an unexpected result that ASR gels became homogeneous with respect to their CaO contents at high dosage levels. However, the reduction in average CaO/SiO₂ ratios and the homogenization in the CaO content of ASR gels due to the addition of lithium salts may not be related to the expansion of mortars.     

SrTiO3 thin films by mocvd for 1 gbit DRAM application

Abstract

Three important aspects of the preparation of SrTiO₃ thin films by MOCVD are discussed in detail in view of the application of these films as the capacitor dielectric of Gbit-scale DRAMs: CVD reactions in the Sr(DPM)₂-Ti(i-OC₃H₇)₄-O₂ system, step coverage and relations between microstructure and electrical properties. The effect of the substrate temperature on the Sr and Ti deposition rates was first investigated for thermal and ECR CVD SrTiO₃ films. SrO and TiO₂ deposition by thermal CVD above 550°C were found to be controlled by the surface reaction and gas transport, respectively, whereas both SrO and TiO₂ deposition are controlled by gas transport for ECR CVD at 450 to 600°C. The influence of the Sr and Ti deposition regimes on the step coverage of SrO, TiO₂ and SrTiO₃ were then assessed. SrO films prepared by thermal CVD at 600°C exhibited the best step coverage, indicating that a relation exists between reaction controlled deposition and good step coverage. The effect of the film composition and film thickness on the microstructure of SrTiO₃ thin films were finally investigated and correlations were made to other analyzed physical and electrical properties. Polycrystalline perovskite phase SrTiO₃ films were obtained for a composition 0.7 ≤ Sr/Ti ≤ 1.2. The best crystallinity, maximum permittivity and maximum refractive index were obtained for Sr/Ti = 0.95. Titanium rich films are thought to be composed of a mixture of a titanium rich amorphous phase and crystalline SrTiO₃, and strontium rich films are believed top correspond to a (SrTiO₃)_m (SrO)_n structure. The dielectric constant slowly decreased as the film thickness was reduced. The sharp decrease observed near 400–500 Å could be due to the existence of some perturbed layer at the interface with one or both of the electrodes     

Analysis model of leakage current in a long shield power cable in inverter‐fed AC drives

Each time switching occurs, a PWM inverter produces high‐frequency leakage currents flowing through stray capacitors. Since the inverter for a trash conveyance crane is installed far away from the motor, the shield power cables between them become long, and leakage currents pass through the stray capacitances of the shielded cables and flow to the ground. This paper proposes a model circuit for analyzing leakage currents which flow into the shields of the cables. The effectiveness of the proposed model circuit is verified by comparison of simulated leakage currents using the proposed method and measured leakage currents. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 65–72, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.2002