Fabrication and electron transport properties of epitaxial films of electron-doped 12CaO·7Al2O3 and 12SrO·7Al2O3

Epitaxial growth and electron doping of 12CaO·7Al₂O₃ (C12A7) and 12SrO·7Al₂O₃ (S12A7) are reported. The C12A7 films were prepared on Y₃Al₅O₁₂ (YAG) single-crystal substrates by pulsed laser deposition at room temperature and subsequent thermal crystallization. X-ray diffraction patterns revealed the films were grown epitaxially with the orientation relationship of (001)[100] C12A7 || (001)[100] YAG. For S12A7, pseudo-homoepitaxial growth was attained on the C12A7 epitaxial layer. Upon electron doping, metallic conduction was achieved in the C12A7 film and the S12A7/C12A7 double-layered films. Analyses of optical absorption spectra for the S12A7/C12A7 films provided the densities of free electrons in each layer separately. Hall measurements exhibited larger electron mobility in the S12A7/C12A7 film than those in C12A7 and S12A7 films, suggesting free electrons may be accumulated at the S12A7/C12A7 interface due presumably to a discontinuity of the cage conduction bands.     

Reaction control in radical polymerization of di‐n‐butyl itaconate utilizing a hydrogen‐bonding interaction

We have reported that intramolecular chain‐transfer reaction takes place in radical polymerization of itaconates at high temperatures and/or at low monomer concentrations. In this article, radical polymerizations of di‐n‐butyl itaconate (DBI) were carried out in toluene at 60 °C in the presence of amide compounds. The ¹³C‐NMR spectra of the obtained poly(DBI)s indicated that the intramolecular chain‐transfer reaction was suppressed as compared with in the absence of amide compounds. The NMR analysis of DBI and N‐ethylacetamide demonstrated both 1:1 complex and 1:2 complex were formed at 60 °C through a hydrogen‐bonding interaction. The ESR analysis of radical polymerization of diisopropyl itaconate (DiPI) was conducted in addition to the NMR analysis of the obtained poly(DiPI). It was suggested that the suppression of the intramolecular chain‐transfer reaction with the hydrogen‐bonding interaction was achieved by controlling the conformation of the side chain at the penultimate monomeric unit of the propagating radical with an isotactic stereosequence. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4895–4905, 2004     

Synthesis and properties of bis(pyrazino[2′,3′:4,5]imidazole)-fused 1,2,5,6-tetrahydro-1,4,5,8,9,10-hexaazaanthracenes: a new fluorescent nitrogen-rich heterocycle

Nitrogen-rich heterocycles, bis(pyrazino[2′,3′:4,5]imidazole)-fused 1,2,5,6-tetrahydro-1,4,5,8,9,10-hexaazaanthracenes (BPI-HAAs) were prepared by conventional Pd(OAc)₂/BINAP-catalyzed C-N coupling reactions of 5-aryl-3-bromoaminopyrazines. The BPI-HAA core is a planar structure with aromaticity, and this heterocycle exhibits red fluorescence and moderate electron-accepting characteristics.     

Solution‐processable colorless polyimides derived from hydrogenated pyromellitic dianhydride with controlled steric structure

This work presents novel colorless polyimides (PIs) derived from 1R,2S,4S,5R‐cyclohexanetetracarboxylic dianhydride (H″‐PMDA). Isomer effects were also discussed by comparing with PI systems derived from conventional hydrogenated pyromellitic dianhydride, that is, 1S,2R,4S,5R‐cyclohexanetetracarboxylic dianhydride (H‐PMDA). H″‐PMDA was much more reactive with various diamines than H‐PMDA, and the former led to PI precursors with much higher molecular weights. The results can be explained from the quite different steric structures of these isomers. The thermally imidized H″‐PMDA‐based films were colorless regardless of diamines because of inhibited charge‐transfer interaction. In particular, the H″‐PMDA/4,4′‐oxydianiline system simultaneously achieved a very high T_g exceeding 300 °C, high toughness (elongation at break > 70%), and good solution processability. In contrast, the H‐PMDA‐based counterparts were essentially insoluble. The outstanding solubility of the former probably results from disturbed chain stacking by its nonplanar steric structure. An advantage of chemical imidization process is also proposed. In some cases, a copolymerization approach with an aromatic tetracarboxylic dianhydride was effective to improve the thermal expansion property. The results suggest that the H″‐PMDA‐based PI systems can be promising candidates for novel high‐temperature plastic substrate materials in electronic paper displays. A potential application as optical compensation film materials in liquid crystal displays (LCD) is also proposed in this work. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Microsequencing of proteins electrotransferred onto immobilizing matrices from polyacrylamide gel electrophoresis: application to an insoluble protein

Semidry electroblotting is convenient and allows a rapid and efficient protein transfer from one- or two-dimensional polyacrylamide gels onto sequencer stable supports for protein microsequence analysis in a gas-phase sequencer. Using this technique, we determined the amino acid sequences of the basic 7S globulin (Bg), an insoluble protein present in soybean seeds. Based on sequence determination, the cDNA-encoding Bg could be easily cloned and characterized.     

Analysis of one-and two-particle spectra at RHIC based on a hydrodynamical model

We calculate the one-particle hadronic spectra and correlation functions of pions based on a hydrodynamical model. Parameters in the model are so chosen that the one-particle spectra reproduce experimental results of √s= 130 AGeV Au + Au collisions at RHIC. Based on the numerical solution, we discuss the space-time evolution of the fluid. Two-pion correlation functions are also discussed. Our numerical solution suggests the formation of the quark-gluon plasma with large volume and low net baryon density.     

Pd black deposited on polypropylene sheet as a highly selective catalyst for hydrogenation of alkenes

A catalyst deposited on a polypropylene sheet having an activity of almost the same level as commercially available Pd black and capable of promoting hydrogenolysis-free hydrogenation was developed.     

Copper‐Catalyzed Stereoselective Aminoboration of Bicyclic Alkenes

A copper‐catalyzed aminoboration of bicyclic alkenes, including oxa‐ and azabenzonorbornadienes, has been developed. With this method, amine and boron moieties are simultaneously introduced at an olefin with exo selectivity. Subsequent stereospecific transformations of the boryl group can provide oxygen‐ and nitrogen‐rich cyclic molecules with motifs that may be found in natural products or pharmaceutically active compounds. Moreover, a catalytic asymmetric variant of this transformation was realized by using a copper complex with a chiral bisphosphine ligand, namely (R,R)‐Ph‐BPE.