A possibility of holon (boson) pair condensation is explored for hole doped high Tc cuprates, by using the U(1) slave-boson representation of the t-J Hamiltonian with the inclusion of hole-hole repulsion. A phase diagram of the hole doped high Tc cuprates is deduced by allowing both the holon pairing and spinon pairing. It is shown that the spin gap size remains nearly unchanged below the holon pair condensation temperature. We find that the s-wave holon pairing under the condition of d-wave singlet pairing is preferred, thus allowing d-wave hole pairing.

Titanium and zirconium complexes with a pyridine diamide ligand, [2,6‐(RNCH2)2NC5H3]2− (PDMP; R = 2,6‐dimethylphenyl) have been synthesized and their catalytic behaviors investigated for ethylene polymerization. It was found that the zirconium complexes, [PDMP]ZrCl2 (7) and [PDMP][ZrCl3 × THF]2 (8), gave higher activities than the titanium complexes, [PDMP]TiCl2 (5) and [PDMP][TiCl3]2 (6). The bimetallic complexes (6, 8) gave higher activities than the corresponding monometallic complexes (5, 7). The titanium complexes gave polymers with higher molecular weight (Mw) than the zirconium complexes. The molecular weight distribution (Mw/Mn) of the polymers obtained from the pyridine diamide complexes were much broader than that of the normal metallocene catalysts. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3756–3762, 1999

The objective of this study is to investigate the magnetic susceptibility of Zr-Cu binary alloys for their potential use as biomaterials with nullifying magnetic properties for magnetic resonance imaging diagnosis. The Zr-Cu binary alloys were prepared using the arc-melting process with zirconium strips and oxygen-free copper. This binary alloy has two dominant phases consisting of ¡-Zr and CuZr 2 intermetallic phase. The magnetic susceptibility of the Zr-Cu binary alloys was extremely low, approximately 10 ¹7 ; this level is approximately one order less than that of pure Zr and other commercialized metallic biomaterials. Consequently, Zr-Cu binary alloys have the potential to be used as biomaterials with low magnetic property.

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