Tetragonal SmBa2Cu3O7−x [x = 0.74 (4)]

Crystals of the title compound, samarium barium copper oxide, were prepared by a modified top‐seeded solution‐growth method. The crystals thus prepared showed no superconductivity down to 4.2 K. A careful examination showed that the structure closely resembles that of tetragonal YBCO, and there is no atom mixing at the Ba or other sites, within experimental accuracy. A bond‐valence‐sum calculation at the Ba site also indicated the absence of Sm. Each site is fully occupied by a single atom, except for the oxy­gen site in the basal plane of the CuO₆ octahedron. The occupancy of this oxy­gen site is significantly reduced [0.13 (2)], as is commonly observed in the 123 system. The atomic displacement parameters of the atoms in the CuO₂ plane, as well as of the Sm atom, are very small, indicating that two equivalent CuO₂ planes tightly sandwich the Sm atom.     

Electronic transmission of three-terminal pyrene molecular bridge

This paper investigates theoretically the electronic transmission spectra of the three terminal pyrene molecular bridge and the quantum current distribution on each bond by the tight-binding model based on nonequilibrium Green's function and the quantum current density approach, in which one π molecular orbital is taken into account per carbon atom when the energy levels and HOMO-LUMO gap are obtained. The transmission spectra show that the electronic transmission of the three terminal pyrene molecular bridge depends obviously on the incident electronic energy and the pyrene eigenenergy. The symmetrical and oscillation properties of the transmission spectra are illustrated. A novel plus-minus energy switching function is found. The quantum current distribution shows that the loop currents inside the pyrene are induced, and some bond currents are much larger than the input and the output currents. The reasons why the loop currents and the larger bond currents are induced are the phase difference of the atomic orbits and the degeneracy of the molecular orbits. The calculations illustrate that the quantum current distributions are in good agreement with Kirchhoff quantum current conservation law.     

New Heteroaromatic Polymers Consisting of Alkyl‐ and Amino‐1,3,5‐triazine Units. Their Basic Optical Properties and n‐Type Time‐of‐Flight Drift Mobility

Summary: Alternating copolymers between substituted 1,3,5‐triazine (substituent = alkyl or amine) and thiophene or bithiophene are synthesized. The copolymer of amino‐1,3,5‐triazine with thiophene is soluble in organic solvents, transparent in most parts of the visible region, and photoluminescent. The copolymer receives electrochemical n‐doping with an E_pc of −2.08 V vs Ag⁺/Ag and shows a time‐of‐flight electron drift mobility of 2.0 × 10⁻⁴ cm² · V⁻¹ · s⁻¹, which is larger than that of widely used Al(8‐quinolinolato)₃.

Structure of the poly(1,3,5‐triazine)s.     

Analysis of amino acids and proteins using a poly(methyl methacrylate) microfluidic system

Plastic microchips are very promising analytical devices for the high-speed analysis of biological compounds. However, due to its hydrophobicity, their surface strongly interacts with nonpolar analytes or species containing hydrophobic domains, resulting in a significant uncontrolled adsorption on the channel walls. This paper describes the migration of fluorescence-labeled amino acids and proteins using the poly(methyl methacrylate) microchip. A cationic starch derivative significantly decreases the adsorption of analytes on the channel walls. The migration time of the analytes was related to their molecular weight and net charge or pI of the analytes. FITC-BSA migrated within 2 min, and the theoretical plate number of the peak reached 480,000 plates/m. Furthermore, proteins with a wide range of pI values and molecular weights migrated within 1 min using the microchip.     

New plastoquinones isolated from the brown alga, Sargassum micracanthum

Four new plastoquinones were isolated from the methanolic extract of the brown alga, Sargassum micracanthum. Their structures were elucidated based on spectroscopic analysis and chemical conversions from 2-geranylgeranyl-6-methyl-1,4-benzohydroquinone. These plastoquinones exhibited significant antioxidant activities such as an inhibitory effect on lipid peroxidation and a radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH). Some of the new plastoquiones showed cytotoxic activity against cancer cell line.     

New entry of coupling reaction of phenacylamine derivatives with silylstannane

The new coupling reaction of phenacylamines with silylstannane and lithium diisopropylamide (LDA) is reported. The treatment of a phenacylamine iodide 1 with (trimethylsilyl)tributylstannane (Me3SiSnBu3) and cesium fluoride (CsF) gave a dimerization product 2 having no iodine atom. Reaction of 1 with LDA afforded a dimerization product 3 with an iodine atom. The products 2 and 3 were separated to the meso and racemic isomers, respectively.     

Holographic Bragg gratings in a photoresponsive cross-linked polymer-liquid-crystal composite

Holographic gratings were in a composite material that comprised a cross-linked polymer with azobenzene side chains and a nematic liquid crystal. Holographic recording was based on the photoinduced alignment of the nematic liquid crystal inside a cell as a result of amplification of the photoreorientation of azobenzene residues. The diffraction efficiency depends on cell thickness and reading angle of the gratings, so this composite material exhibits volume holographic properties with Bragg diffraction.     

Preferential uniplanar orientation mechanism of the (101) crystal plane of regenerated cellulose

The molecular orientation behavior of regenerated cellulose, in both crystalline and noncrystalline phases, was investigated quantitatively under various conditions during coagulation-regeneration from viscose solution and during drying of the resulting gel film. It was concluded that the stronger the tensions which arise parallel to the film surface during coagulation-regeneration and drying of the gel film, the more prominent become the uniplanar orientation of the (101) crystal plane and planar orientations of the crystal b axis and noncrystalline chain segments, all parallel to the film surface and associated with considerable distortion and disintegration of the regenerated crystal. This conclusion suggests an orientation mechanism of the cellulose II crystal, namely, rotation of the crystal around the U_{(101 )} axis associated with slippage of the (101) crystal plane, the most highly hydrated and most readily dislocated plane, in the direction of the tension, which is also parallel to the surface of the film. The behavior of this type of uniplanar orientation of the (101) crystal plane is characterized semiquantitatively by comparing observed distributions of the orientation of crystallographic axes with those calculated on the basis of a relatively simple model for crystal orientation.