Influence of the characteristics of soil and fly ash on the supercritical carbon dioxide extraction of dioxins.

Several investigations on the extraction of dioxins from soil and fly ash with supercritical fluid have been reported; however, few of them describe the influence of components on the extraction. We extracted dioxins from eight samples with different values of organic carbon content and surface area with supercritical CO(2) at a temperature of 463 K, a pressure of 40 MPa, and using 10% toluene as an entrainer. We researched the influence of the characteristics of soil and fly ash on supercritical CO(2) extraction of dioxins. The results revealed that the extraction efficiencies of PCDD/DFs and PCBs were high for all soil samples, while that of fly ash samples decreased with the increase in organic carbon content and surface area. The extraction efficiencies of dioxins from four standard samples, activated carbon, humic acid, alumina, and florisil, were also examined. The results revealed that the extraction efficiencies were strongly influenced by activated carbon like components present in the samples.     

Synthesis of lipophilic bisanthracene fluorophores: versatile building blocks toward the synthesis of new light-harvesting dendrimers

Lipophilic bisanthracene-based fluorophore and its derivatives were synthesized by the Suzuki-Miyaura cross-coupling reaction of 9-anthrylboronic acid with a substituted dibromobenzene. In addition to desirable fluorescent properties, these molecular systems were demonstrated to serve as versatile building blocks toward the synthesis of two types of new light-harvesting dendrimers due to their chemical stability.     

A splitting theorem for infinite dimensional Alexandrov spaces with nonnegative curvature and its applications

We prove a splitting theorem for Alexandrov space of nonnegative curvature without properness assumption. As a corollary, we obtain a maximal radius theorem for Alexandrov spaces of curvature bounded from below by 1 without properness assumption. Also, we provide new examples of infinite dimensional Alexandrov spaces of nonnegative curvature.     

Mechanism of selective oxygen reduction on platinum by 2,2'-bipyridine in the presence of methanol

Mechanism of selective oxygen reduction on platinum by 2,2'-bipyridine in the presence of methanol has been investigated by in situ surface-enhanced infrared absorption spectroscopy. The addition of 2,2'-bipyridine caused the decrease of adsorbed water molecules and those existing near the surface of platinum. The formation of both CO and formate, the latter being the intermediate in the non-CO path for methanol oxidation, depressed in the presence of 2,2'-bipyridine, suggests that 2,2'-bipyridine hinders methanol oxidation via both non-CO and CO paths on platinum. The geometrical effect of 2,2'-bipyridine adsorbed onto platinum was also investigated by multisite Monte Carlo simulation. It is indicated that selective oxygen reduction is caused by the difference in the number of required adsorption sites between methanol and dioxygen molecules. The suppression of Pt oxide species by 2,2'-bipyridine is found to be another factor that enhances the oxygen reduction.     

Dynamics of 15N natural abundance in wood-decomposing fungi and their ecophysiological implications

Nine species of basidiomycota and one species of ascomycota were grown in an ammonium sulphate media and on beech wood; and the general (15)N dynamic patterns of the hyphae were examined. The fungal body initially became depleted in (15)N in both the types of incubation. However, the underlying mechanisms were quite different, that is, significant fungal (15)N drop on the beech wood is associated with the fungal N reallocation and the uptake of atmospheric ammonia and/or NO(x), in addition to isotope fractionation during assimilation. Although the (15)N values of the wood-decomposing basidiocarps were generally close to the (15)N values of the wood, it does not always indicate that the wood derived N was the sole N source for the fungi throughout the growth periods as shown in our wood-decomposing experiment.     

Food webs in Mongolian grasslands: The analysis of 13C and 15N natural abundances

Overgrazing often lowers species richness and productivity of grassland communities. For Mongolian grassland ecosystems, a lack of detailed information about food-web structures makes it difficult to predict the effects of overgrazing on species diversity and community composition. We analysed the δ¹³C and δ¹⁵N signatures of herbaceous plants, arthropods (grouped by feeding habit), wild and domestic mammals, and humans in central Mongolia to understand the predominant food-web pathways in this grassland ecosystem. The δ¹³C and δ¹⁵N values of mammals showed little variation within species, but varied considerably with slope position for arthropods. The apparent isotopic discrimination between body tissue and hair of mammals was estimated as 2.0 ‰ for δ¹³C and 2.1 ‰ for δ¹⁵N, which was large enough to cause overestimation of the trophic level of mammals if not taken into account when using hair samples to measure isotopic enrichment.     

Synthetic construction of a Le determinant via gabriel amine synthesis and the glycopolymer involving highly clustered Le residues

Synthetic construction of a Le^x determinant was accomplished via slightly modified Gabriel amine synthesis from three building blocks. Further transformations followed by polymerization of the Le^x derivative gave a glycopolymer having trisaccharidic units as pendant-type epitopes.     

Synthetic studies on sugar-fused erinacines

Samarium-mediated 7-endo-trig radical cyclization afforded excellent stereocontrol of the four contiguous asymmetric centers present in the 6-7-6 tricyclic cores of the (sugar-fused) erinacines E, F, and G.     

π-Extended Carbazole Derivatives as Host Materials for Highly Efficient and Long-Life Green Phosphorescent Organic Light-Emitting Diodes

High-performance organic light-emitting diodes (OLEDs) that use phosphorescent and/or thermally activated delayed fluorescence emitters are capable of realizing 100 % electron-to-photon conversion. The host materials in these OLEDs play crucial roles in determining OLED performance. Carbazole derivatives are frequently used as host materials, among which 3,3-bis(9H-carbazol-9-yl)biphenyl ( mCBP ) is often used for lifetime testing in scientific studies. In this study, the π conjugation of the carbazole unit was expanded to enhance OLED lifetime by designing and developing two benzothienocarbazole (BTCz)-based host materials, namely m1BTCBP and m4BTCBP . Among these host materials, m1BTCBP formed a highly efficient [Ir(ppy)₃]-based OLED with an operational luminescence half-life (LT₅₀) of over 300 h at an initial luminance of approximately 12000 cd m⁻² (current density: 25 mA cm⁻²). The LT₅₀ value at 1000 cd cm⁻² was estimated to be about 23 000 h. This performance is clearly higher than that of mCBP -based OLEDs (LT₅₀≈8500 h).