Catalytic oxidation of nitrogen monoxide over La1−xCexCoO3 perovskites

This paper presents an investigation on the NO oxidation properties of perovskite oxides. La_1−xCe_xCoO₃ (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4) perovskite-type oxides were synthesized through a citrate method and characterized by XRD, BET and XPS. The catalytic activities were enhanced significantly with Ce substitution, and achieved the best when x was 0.2, but decreased at higher x values. The performed characterizations reveal that the adsorbed oxygen on the surface plays an important role in the oxidation of NO into NO₂. The surface compounds after the co-adsorption of NO and O₂ at room temperature, were investigated by DRIFTS and TPD experiments. Three species: the bridging nitrate, the hyponitrites and the monodentate nitrate, were formed on the surface. The order of thermal stabilities was as follows: monodentate > hyponitrite > bridging. Among them, only the monodentate nitrate which decomposed at above 300 °C, would desorb NO₂ into the gas phase. When Ce was added, the temperature of monodentate nitrate desorption became low and the adsorption of the other two species decreased. This might be related to the oxidation state of Co on the surface. Analysis by synthesizing the characterization results and catalytic activity data shows that large amounts of adsorbed oxygen, small amount of inactive compounds on the surface and low NO₂ desorption temperature are favorable for the oxidation of NO.     

Anti-wear Chemistry of ZDDP and Calcium Borate Nano-additive. Coupling Experiments, Chemical Hardness Predictions, and MD Calculations

Zinc dialkyl dithiophosphate (ZDDP) is an anti-wear additive for steel surfaces currently used in engine oils. Its anti-wear performance (against abrasion) is due to tribochemical reaction of zinc polyphosphate with abrasive metal oxides nanoparticles, under the combined effect of pressure and shear. However, phosphorous and sulfur are nocuous for environmental issues. Borates are possible candidates to replace phosphates in engine oils. Friction reduction with borates is found to be better than ZDDP but the anti-wear efficiency of borates is lower. In this work, we show how chemical hardness model and computer simulation can explain these different behaviors. Also we show that molecular dynamics is able to predict accurately behavior of mixtures of phosphates and borate. Results show that mixtures of additives with a P:B ratio slightly above unity can be a good compromise to have both good tribological performance and low content of phosphorous and sulfur in the lubricant.     

Chronic effects of methylmercury in rats. I. Biochemical aspects

The effect of a pre-coronary angioplasty education and counselling program on knowledge and psychological status of patients and on knowledge and quality of life/coping status of their spouses was evaluated. Forty patients and their spouses participated in a pre-coronary angioplasty education and counselling program and 40 served as controls. Knowledge, psychological status and quality of life/coping status were assessed prior to coronary angioplasty and at a mean of four and 11 months post-coronary angioplasty. At four months, improved knowledge and reduced anxiety were found for patients in the experimental group. At 11 months, spouses in the experimental group showed continued improvement in quality of life compared to those in the control group. It was concluded that pre-coronary angioplasty education and counselling can impact favourably upon knowledge in patients and quality of life in spouses.     

Ultra Accelerated Quantum Chemical Molecular Dynamics Study on Ethylene Polymerization Reaction Using CpSiH2NHTiCl2—Constrained Geometry Catalyst

The ethylene polymerization process using constrained geometry catalyst CpSiH₂-NH-TiCl₂ (CGC) was investigated by ultra accelerated quantum chemical molecular dynamics (UA-QCMD). We observed that the co catalyst MAO reacted with Ti CGC and forms ion pair within 85 fs. With the coordination of ethylene monomer the MAO-CGC ion pair dissociated and once the initial ethylene insertion has taken place, the further ethylene insertion occurring with a less energy barrier, is in good agreement with experimental findings.     

Bile acid metabolism in young-old parabiotic rats

Serum cholesterol, triglyceride and phospholipid levels, liver cholesterol concentration, bile flow, biliary cholesterol, phospholipid and bile acid secretion rates, fecal sterol and bile acid levels and their bile acid compositions were examined in young-old parabiotic rats and compared with those in young and old control rats and young-young parabiotic rats. Bile acid composition was expressed in terms of the cholic acid group/chenodeoxycholic acid group (CA/CDCA) ratio. Body weight (BW) gain decreased after parabiosis especially in old rats, but the liver weight (g/100 g BW), diet-intake, feces dry weight, liver cholesterol concentration and fecal sterol level were almost the same in all the groups. The biliary bile acid secretion rate was higher and the fecal bile acid level was lower in old rats than those in young rats but both the levels became comparable with those in young rats after parabiosis of old rats with young rats. Young rats, however, showed no changes in these levels after parabiosis. The serum cholesterol level and the biliary and fecal CA/CDCA ratios in old rats were higher than those in young rats but decreased after parabiosis with young rats, although they were still higher than those in young rats. The serum cholesterol level in young rats increased after parabiosis with old rats, but not after parabiosis with young rats, and the fecal bile acid level and the CA/CDCA ratio were not changed in either case. It is concluded from these findings that the serum cholesterol level and the CA/CDCA ratio increased with age and that these increases were prevented after parabiosis with young rats, while young rats, although their serum cholesterol level was increased, showed no increase in the CA/CDCA ratio after parabiosis with old rats.     

Thermal and photo-induced surface damage in paratellurite

Long-term operation of TeO2 acousto-optical device is limited by the formation of surface damage caused by the He–Cd laser irradiation. Similar surface damage occurs during the heat treatment of the TeO2 crystal at 350°C. In this study, TeO2 specimens after various surface treatments have been observed by electron microscopy and X-ray photoelectron spectroscopy. The variation of the transmittance for mechanically polished specimens has been measured in situ during heat treatments. It was found that the thermal surface damage at 350°C was formed in the surface layer damaged by mechanical polishing. The mechanically damaged layer was amorphous and deficient in oxygen in the as-polished state. The electron microscopic observation revealed that the surface damage layer induced by heat treatments or by the ultraviolet light irradiation contained tellurium particles (20–40 nm) in diameter dispersed in the TeO2 matrix. On annealing the TeO2 specimen at 500°C in air, however, the particles disappeared because of the melting, evaporation and oxidation of tellurium which restores the transmittance of the crystal. Based on the results, combined with the observation of surface damage induced by the visible light irradiation, a possible mechanism of the surface damage formation has been briefly discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

Gain of chromosome 20 is a frequent aberration in liver metastasis of colorectal cancers

To investigate the characteristics of the numerical chromosome aberrations in liver metastasis of colorectal cancers, fluorescence in situ hybridization (FISH) for chromosomes 8, 18, 14/22, and 20 was performed in 18 specimens of primary regions and 18 of metastatic regions in liver metastasis of colorectal cancers compared with 15 of non-liver metastatic cancers. Among these numerical aberrations, the gain of chromosome 20, especially copy numbers exceeding three, was frequently observed in primary and metastatic cancers. Among these numerical aberrations, the gain of chromosome 20, especially copy numbers exceeding three, was frequently observed in primary and metastatic regions of liver metastasis groups compared with that of the non-liver metastasis group (P < 0.05). The incidences of gain of chromosome 20 in both regions of the liver metastasis group were higher than that of the non-liver metastasis group (P < 0.05). The gain of chromosome 20 is a frequent aberration in primary and metastatic regions in patients with liver metastatic colorectal cancers and may be available as a genetic marker for the diagnosis or prediction of liver metastasis.     

Effect of Temperature on the Slurry Characteristics and Green Bodies of Alumina

The importance of temperature in colloidal processing was examined by investigating its effect on the characteristics of a ceramic slurry and on the subsequent processing before firing. An aqueous alumina slurry was used as a model system in the present study. The viscosity of the slurry was found to vary significantly with temperature, and the structure of the resultant green bodies made by centrifugation varied correspondingly. The importance of temperature in the production of ceramics is discussed in light of these results.     

Room-temperature formation of low refractive index silicon oxide films using atmospheric-pressure plasma

This study aims to apply atmospheric-pressure (AP) plasma to the fabrication of single-layer anti-reflection (AR) coatings with porous silicon oxide. 150 MHz very high-frequency (VHF) excitation of AP plasma permits to enhance the chemical reactions both in the gas phase and on the film-growing surface, increasing deposition rate significantly. Silicon oxide films were prepared from silane (SiH4) and carbon dioxide (CO2) dual sources diluted with helium. The microstructure and refractive index of the films were studied using infrared absorption and ellipsometry as a function of VHF power density. It was shown that significant increase in deposition rate at room temperature prevented the formation of a dense SiO2 network, decreasing refractive index of the resulting film effectively. As a result, a porous silicon oxide film, which had the lowest refractive index of 1.24 at 632.8 nm, was obtained with a very high deposition rate of 235 nm/s. The reflectance and transmittance spectra showed that the low refractive index film functioned as a quarter-wave AR coating of a glass plate.     

Preparation of novel transparent glass–ceramics containing fluoride crystals

Transparent glass–ceramics containing YLiF₄ nano-crystals were synthesized by controlled heat-treatments of LiFYF₃Al₂O₃SiO₂ glass. The crystallite size estimated to be about 8 nm was much less than the wavelength of the visible light. The transmittance of the glass–ceramic with a thickness of 2 mm was more than 85% at 400 nm and as high as 95% in the infrared region. The fluorescence centered around 1000 nm was hardly observed from Er³⁺-doped precursor glass under 800 nm excitation, while the emission with the Stark spitting was clearly observed for the Er³⁺-doped glass–ceramic. The phonon sideband of the ⁷F₀ → ⁵D₂ excitation spectra of Eu³⁺ reveals that Eu³⁺ doped in precursor glass is in silicate network while Eu³⁺ doped in the glass–ceramic is in not only silicate framework but also fluoride framework. These results indicate that rare-earth ions such as Er³⁺ and Eu³⁺ could be successfully incorporated into YLiF₄ nano-crystals in the glass–ceramics.