Comparative study of behavior of inhaled samarium and cerium in mice

Distribution of Sm and Ce in mice was investigated after inhalation exposure to their oxide particles of 5 μm diameter and 15 mg/m3.Sm and Ce were mainly distributed in lung,their concentrations decreased with passing time,and their concentrations in lung were correlated with exposure periods.Concentrations of Ce were lower than that of Sm in each point.Sm was also distributed in the other organs and bone but Ce was scarcely detected.These results suggest that the behaviors of Sm and Ce inhaled were different,although their chemical properties are similar.     

Evidence that Crystal Facet Orientation Dictates Oxygen Evolution Intermediates on Rutile Manganese Oxide

Elucidating the mechanism that differentiates the oxygen‐evolving center of photosystem II with its inorganic counterpart is crucial to develop efficient catalysts for the oxygen evolution reaction (OER). Previous studies have suggested that the larger overpotential for MnO₂ catalysts under neutral conditions may result from the instability of the Mn³⁺ intermediate to charge disproportionation. Here, by monitoring the surface intermediates of electrochemical OER on rutile MnO₂ with different facet orientations, a correlation between the stability of the intermediate species and crystal facets is confirmed explicitly for the first time. The coverage of the Mn³⁺ intermediate is found to be 11‐fold higher on the metastable (101) surfaces compared to (110) surfaces, leading to the superior OER activity of (101) surfaces. The difference in OER activity may result from the difference in surface electronic states of Mn³⁺, where interlayer charge comproportionation of Mn²⁺ and Mn⁴⁺ to generate two Mn³⁺ species is favored on (101) facets. Considering the fact that the OER enzyme accommodates Mn³⁺ stably during the Kok cycle, the enhanced OER activity of the rutile MnO₂ catalyst with a metastable surface highlights the importance of mimicking not only the crystal structure but also the electronic structure of the targeted natural enzyme.     

InGaAs quantum dots formed in tetrahedral-shaped recesses on GaAs (111)B grown by metalorganic chemical vapor deposition

Novel semiconductor quantum dots (QDs), grown in tetrahedral-shaped recesses (TSRs) formed on a (111)B GaAs substrate, are described from both material science and device application points of view. After explaining the fabrication procedure for TSRs, growth of InGaAs QDs and their optical properties are explained. It is revealed that an InGaAs QD of indium-rich chemical composition is formed spontaneously at the bottom of each TSR. The mechanism of the QD formation is discussed in detail. It is proved from magneto-photoluminescence that the QDs actually have optical properties peculiar to zero-dimensional confinement. Several experimental results indicating excellent growth controllability of the QDs are presented. Finally, recent challenges to apply the QDs to electronic memory devices are reported. Two kinds of devices, where the position of individual QD is artificially controlled, are proposed for the first time and the preliminary experimental results are explained.     

Liquid-Liquid-Gas Triphasic Hydrogenation of Bicarbonate to Formate in a Continuous Flow Tubular Reactor

Multiphasic reaction of bicarbonate hydrogenation to form formate using homogeneous Ru PNP pincer catalyst in a continuous flow tubular reactor is reported. The reaction system consists of three phases. Catalyst is dissolved in toluene while potassium bicarbonate is dissolved in water. The significance of efficient mixing among the organic phase, aqueous phase and gaseous hydrogen to improve hydrogenation reaction by using different inert packing materials is studied by operando visualization and also quantitatively discussed. The bicarbonate conversion of up to 67% is achieved after optimization of important reaction and reactor parameters. The designed reactor setup comprised of effective recycling system that recycles the catalyst with >99% activity.     

Characteristics and oil absorption of deep‐fat fried dough prepared from ball‐milled wheat flour

BACKGROUND: High levels of oil in fried products has been recognized as causing health problems. The formation of microstructure during frying is one factor that influences oil absorption. Above the glass transition temperature (T_g), the physical properties of a polymer influences the formation of structure. The ball‐milling process changes the physicochemical properties of wheat flour constituents. The present study investigated the effects of physicochemical changes in wheat flour by the ball‐milling process on structure formation and oil absorption in wheat flour dough model. RESULTS: Dough samples were made from wheat flour that had been ball‐milled for 0 to 10 h and then fried in frying oil at 150 °C for 1–7 min. Thermal properties of wheat flour, structure alteration, and textural properties of fried samples were evaluated. As compared with samples made of non‐milled flour, samples made from milled flour had smaller pores and higher oil absorption. The fracture force of a fried sample prepared from non‐milled flour was lower than that of a sample prepared from milled flour. CONCLUSION: Ball‐milling affected the microstructure formation in fried wheat flour dough, and subsequently oil absorption. The crispness of a sample prepared from non‐milled wheat flour is higher than that of a sample prepared from ball‐milled wheat flour. This may be due not only to a plasticization effect, but may also be dependent on microstructure. Copyright © 2008 Society of Chemical Industry