N‐band Hubbard models. III. Boson–fermion and interaction–boson models for high‐Tc superconductivity

In this series of articles (I, II), N‐band Hubbard models have been considered for strongly correlated electron systems, which are realized in d–p, π–d, π–R, and σ–R conjugated systems. The magnetism and superconductivity of these systems have been elucidated in terms of effective exchange integrals (J), which are calculated by first‐principle methods. In part III of this series, the BCS–BEC crossover theory, has been introduced to elucidate the physical foundation of our J and JP model for the high‐T_c superconductivity (HTSC). The boson–fermion (BF) model for this theory is found useful for a reasonable explanation of the experimental phase diagrams of HTSC. The underlying physics of the BF model is different from that of the slave boson field‐theoretical model assuming spinon–holon condensations in the low dimension. The interaction boson model (IBM) for nuclear matter is also employed to describe the cooperative mechanisms of electron–phonon (EP), spin fluctuation (SF), charge fluctuation (CF), and many‐bands (MB) effects. This phenomenological model is useful for pictorial understanding and for the theoretical explanation of the cooperative mechanisms: (EP + SF), (SF + CF), (EP + SF + MB), etc. These are also investigated in analogy to BF model of fermionic gases, where the Feshbach resonance between boson and fermion is responsible for their coupling. The implications of these theoretical results are discussed in relation to recent ALPES and STM experiments for HTSC, which suggest the contributions of SF (J) and EP (P) interactions. The recently discovered superconductivity of boron‐doped diamond is examined as an example of two‐band sigma‐radical (σ–R) conjugated systems. Finally, the bipolaron model is briefly discussed in relation to boson–fermion model via EP interaction to superconductivity. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Synthesis of 4,8-dimethyl-6-phenyl-5,6,7,8-tetrahydro-4H-1,3,6-dioxazocines

Five 6-phenyl-5,6,7,8-tetrahydro-4H-1,3,6-dioxazocines were synthesized by the reaction of the corresponding N,N-bis(2-hydroxypropyl)- and N,N-bis(2-hydroxyethyl)chloroanilines with paraformaldehyde in the presence of p-toluenesulfonic acid.     

Phosphorus in organic synthesis—XI Amino acids and peptides—XXI : Reaction of diethyl phosphorocyanidate(DEPC) with carboxylic acids. A new synthesis of carboxylic esters and amides

Diethyl phosphorocyanidate(DEPC) reacts with carboxylic acids in the presence of triethylamine leading to transient formation of acyl cyanides, but in presence of alcohols or amines, carboxylic esters or amides are produced. DEPC is especially effective for the synthesis of amides and peptides, and showed a satisfactory result on the Young racemization test.     

Die Mikrotaktizität von Polyacrylestern

Ohne Zusammenfassung     

Optimization of Fe/SiO<Subscript>2</Subscript> based metal oxides as selective oxidation catalyst of propane with combinatorial approach

A combinatorial optimization with genetic algorism was performed on the five generations of 0.05 atm% Fe/SiO₂ added multi-metal oxides to be used as catalytic materials for the selective oxidation of propane to give aldehydes at 623-773 K. The loaded multi-metal oxides consist of some elements selected from seven elements with various atomic charges or redox properties. For the best materials, selectivity toward aldehydes from 35% at 1st generation to 45% at 4th generation were achieved at 5% propane conversion. Further rational optimization of the best performance catalyst also improves the selectivity up to 49.5%.