Ultra-high-vacuum in situ electron microscopy of growth processes of epitaxial thin films

Extracts from recent results of ultra-high-vacuum in-situ electron microscopy of growth processes of epitaxial thin films are given. As a modified monolayer-by-monolayer mode, the growth process in Fe/(111)Au of the initial Frank-van der Merwe type, followed by the intrinsic γ → α transformation of Fe is mentioned. For the nucleation and growth mode, a systematic selection of epitaxial orientation according to interfacial lattice fitting, nucleation and coalescence features, the validity of Cabrera's suggestion extending Frank and van der Merwe's idea, the cluster mobility and effects of grown-in dislocations in substrate crystals are discussed on the basis of the observations.     

Bidentate amidine ligands for nickel(0)-mediated coupling of carbon dioxide with unsaturated hydrocarbons

Novel bidentate amidines were designed and synthesized as easily available electron-donating N-ligands for Ni0-mediated coupling of carbon dioxide with alkynes or allenes, and high regioselectivity was achieved even for the carboxylation of aryl substituted internal alkynes.     

Infrared-laser delivery system based on polymer-coated hollow fibers

Infrared Er : YAG laser delivery systems based on hollow fibers with an internal polymer layer has been developed. The system consists of a hollow fiber as the delivery medium, a launching coupler for effective coupling between the laser beam and the fiber, and a sealed hollow-fiber tip attached at the output end of the fiber. Fabrication process of the fiber and attachment of the delivery system is reported.     

Effect of fuel injection location on a plasma jet assisted combustion with a backward-facing step

Non-reacting and reacting experiments on the ignition by a plasma jet (PJ) torch were performed to understand the correlation between fuel injection location and combustion characteristics in unheated Mach 2 airflow. Fuel was injected through three sonic injectors in the recirculation region behind a backward-facing step: a parallel injector at 2 mm from the bottom wall and two normal injectors at 2 and 9 mm from the step wall. In order to mitigate the combustion pressure interaction with nozzle, an isolator was installed between the nozzle and combustor. The combustion performance of normal injection was little affected by the difference of fuel injection locations. Moreover, normally injected fuel was escaped not to be held in the recirculation region despite of low fuel injection rates. This led to lower combustion performance relative to the parallel injection which provided fuel not to leave the recirculation region. In this case, the role of the recirculation region was to fully hold fuel, and the PJ torch provided hot gases as a heat source and acted as a flame-holder to ignite fuel–air mixtures. In a low temperature inflow condition, combustible regions were constrained around the bottom wall where embedded with the PJ torch. When thermal choking occurred in the combustor, it induced shock train both in the combustor and isolator. Under this unstable condition, the combustion performance of the normal injection was lower than that of the parallel injection. This is because the normal injection led most fuel into low temperature incoming air-stream.     

Rotational isomerism of a resveratrol tetramer, shoreaketone, in Shorea uliginosa

A new resveratrol tetramer, shoreaketone, was isolated from the stem bark of Shorea uliginosa (Dipterocarpaceae). The structure and the relative configuration were confirmed on the basis of 1D- and 2D-NMR spectral data. The structure has a novel framework of fused heptacyclic ring system including an α,β-unsaturated carbonyl group. In NMR spectra, shoreaketone is observed as two different conformers due to rotational isomerism.     

Synthesis and stereochemistry-activity relationship of small bacteriocin, an autoinducer of the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum

The four stereoisomers of small bacteriocin, an autoinducer of the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum, were synthesized via a versatile methodology for 3'-hydroxyacyl homoserine lactones based on the Nagao asymmetric aldol reaction. The synthetic isomers were much less effective at inhibiting the growth of R. leguminosarum RBL5523 than the natural isomer, showing the importance of stereochemistry for activity.