A study of the reactions between ZrC and some metal oxides

High temperature chemical reactions of ZrC powder or ZrC coating on alumina spheres with CeO₂, UO₂ and SrO were studied. CeO₂ reacts with ZrC at 1473–2073 K to give Ce₂O₃ and Ce₂Zr₂O₇. Virtually no reactions were observed in UO₂-ZrC mixtures at 1673–1973 K. SrO reacts with ZrC above 1273 K to form SrZrO₃, Sr vapor and, presumably, CO. The SrZrO₃ formation on ZrC coated spheres contained in a bed of SrO powder was rapid at 1673 K. All particles suffered serious damages on the ZrC coatings by the reaction with SrO. Though the Sr concentration in the ZrC was below the detection limit, Sr was found to be distributed within the alumina kernel.     

Correlation and hierarchies in financial markets

As an emerging financial market, the trading value of carbon emission trading market has definitely increased in recent years. The carbon emission is not only trading in carbon emitters but also has become an important investment target. To determine the mechanism of this growing market, we analyzed the EU allowances (EUA) price series in European Climate Exchange (ECX) that is the leading European emissions futures market. As other financial market, the absolute value of price change (volatility) in carbon emission trading market also shows long-term power-law correlations. Our analysis shows that definite cross correlations exist between EUA and many other markets. These cross correlations exist in wild-range fields, stock market index, futures of crude, sugar, cocoa, etc., suggesting that in this new carbon emission trading market the speculation behavior had already become a main factor that can affect the price change.     

S-character of Cd+ centre in γ-irradiated alkali silicate glasses

The s-character of Cd⁺ centres and its fluctuation in -irradiated alkali silicate glasses were investigated using ESR spectroscopy. With increasing alkali content, the s-characters of Cd⁺ centres in sodium and potassium silicate glasses decrease monotonically whereas the s-character in lithium silicate glasses shows a maximum and then decreases. The temperature effect on compositional dependence of the s-character of a Cd⁺ centre is rarely observed in lithium silicate glasses. On the other hand, the temperature effect is clearly observed in sodium and it is suggested that local structures around Cd⁺ centres in sodium and potassium silicate glasses is relaxed by annealing at room temperature.     

Structural analysis of sodium silicate glasses containing TiO2 by pulsed neutron scattering

By the use of the time-of-flight pulsed neutron total-scattering spectrometer HIT at the Japanese National Laboratory for High Energy Physics, measurement of structure factorsS(Q) for glasses of type 10Na₂O·(90–x)SiO₂·xTiO₂ (x=0, 5 and 20 mol%) was made over a wide range of scattering vectors up toQ (=4 sin/) ~ 500 nm^–1. High-resolution real-space information was obtained from the Fourier transform ofS(Q). The influence of TiO₂ on the nearest-neighbour Si-O bond length of the silicate anions existing in the glass samples studied is different from that of alkali oxides such as Na₂O. It is concluded that most of the Ti⁴⁺ ions predominantly substitute for Si⁴⁺ ions in their tetrahedrally coordinated sites, leading to the formation of TiO₆ octahedra.     

Soluble amyloid precursor protein 770 is a novel biomarker candidate for acute coronary syndrome

Most Alzheimer disease patients show deposition of amyloid β (Aβ) peptide in blood vessels as well as the brain parenchyma. We previously found that vascular endothelial cells express amyloid β precursor protein (APP) 770, a different APP isoform from neuronal APP695, and that they produce amyloid β peptide. We analyzed the glycosylation of APP770 and found that O-glycosylated sAPP770 is preferentially processed by proteases for Aβ production. Because the soluble APP cleavage product sAPP is considered to be a possible marker for Alzheimer disease diagnosis, sAPP, consisting of a mixture of these variants, has been widely measured. We hypothesized that measurement of the endothelial APP770 cleavage product in patients separately from that of neuronal APP695 would enable us to discriminate between endothelial and neurological dysfunctions. Our recent findings, showing that the level of plasma sAPP770 is significantly higher in patients with acute coronary syndrome, raise the possibility that sAPP770 could be an indicator of endothelial dysfunction. In this review, we first describe the expression, glycosylation, and processing of APP770, and then discuss sAPP770 as a novel biomarker candidate of acute coronary syndrome.     

Antioxidant activity of various teas against free radicals and LDL oxidation

Tea is a widely consumed beverage throughout the world. We assessed the antioxidant activity of six teas, including the aqueous extracts of green tea and oolong tea (Camellia sinensis), tochu (Eucommia ulmoides), Gymnema sylvestre, Japanese mugwort (Artemisia princeps), and barley (Hordeum vulgare), against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and LDL oxidation, and examined the association of LDL oxidizability with the plasma catechin levels in 10 healthy volunteers with a single dose of 5 g green tea powder. In vitro, the inhibitory effects of DPPH radicals and LDL oxidation were found to be strongest in the extract of green tea and weakest in that of barley. After the ingestion of green tea powder, the lag time increased from basal 52.2±4.1 to 60.3±4.2 min at 1 h and 59.5±4.1 min at 2 h, and then returned to the baseline lag time (51.9±1.4 at 4 h and 52.1±4.7 min at 6 h). Regarding the plasma catechin levels, epigallocatechingallate and epicatechingallate significantly increased from basal 3.7±1.3 and 0.8±0.8 ng/mL to 65.7±11.6 and 54.6±12.6 ng/mL at 1 h, and 74.4±18.6 and 49.4±7.1 ng/mL at 2 h, respectively. Green tea therefore showed the strongest antioxidant activity among the six different teas, and the inhibitory effects of green tea on LDL oxidation depended on the plasma catechin levels.     

Marked difference in activity of alumina catalysts for selective catalytic reduction of nitrogen monoxide by ethene in excess oxygen

Alumina is well-known as an effective catalyst for the title reaction. The present study revealed that the activity of an alumina catalyst for the reaction largely depended on its type. A critical factor affecting the activity of an alumina was neither the surface area nor pore structure, but the purity; the higher the purity, the higher the activity. Active alumina catalysts showed high activity for both the oxidation of NO to NO₂ and the reduction of NO₂ by ethene. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photocatalytic decomposition of NO on titanium oxide thin film photocatalysts prepared by an ionized cluster beam technique

Transparent TiO₂ thin film photocatalysts were prepared on transparent porous Vycor glass (PVG) by an ionized cluster beam (ICB) method. The UV‐VIS absorption spectra of these films show specific interference fringes, indicating that uniform and transparent TiO₂ thin films are formed. The results of XRD measurements indicate that these TiO₂ thin films consist of both anatase and rutile structures. UV light (λ > 270 nm) irradiation of these TiO₂ thin films in the presence of NO led to the photocatalytic decomposition of NO into N₂, O₂ and N₂O. The reactivity of these TiO₂ thin films for the photocatalytic decomposition of NO is strongly dependent on the film thickness, i.e., the thinner the TiO₂ thin films, the higher the reactivity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Direct decomposition of nitric oxide over Ba catalysts supported on CeO2-based mixed oxides

The direct decomposition of nitric oxide (NO) over barium catalysts supported on various metal oxides was examined in the absence and presence of O₂. Among the Ba catalysts supported on single-component metal oxides, Ba/Co₃O₄ and Ba/CeO₂ showed high NO decomposition activities, while Ba/Al₂O₃, Ba/SiO₂, and Ba/TiO₂ exhibited quite low activities. The effect of an addition of second components to Co and Ce oxides was further examined, and it was found that the activities were significantly enhanced using Ce–Mn mixed oxides as support materials. XRD results indicated the formation of CeO₂–MnO_x solid solutions with the cubic fluorite structure. O₂-TPD of the CeO₂–MnO_x solid solutions showed a large desorption peak in a range of relatively low temperature. The BET surface areas of the CeO₂–MnO_x solid solutions were larger than those of pure CeO₂ and Mn₂O₃. These effects caused by the addition of Mn are responsible for the enhanced activities of the Ba catalysts supported on Ce–Mn mixed oxides.