High-concentration Na doping of SrRuO3 and CaRuO3.

The Na-doped perovskite-structure ruthenates Sr(1-x)Na(x)RuO3 and Ca(1-y)Na(y)RuO3 were prepared by high-pressure synthesis, which enables us to go beyond the previously reported Na doping limits and substitute Na for over 50% of the Sr in SrRuO3 and the Ca in CaRuO3. Gradual and systematic changes in the crystal structures were observed, and the decreases in the Ru-O bond lengths confirmed the Na substitution at the A site caused hole doping to Ru(4+) at the B site. In contrast to what has been previously reported, Sr(1-x)Na(x)RuO3 showed metallic conductivity.

Control of L-type ferrimagnetism by the Ce/vacancy ordering in the A-site-ordered perovskite Ce(1/2)Cu3Ti4O12.

A-site-ordered perovskite Ce1/2Cu3Ti4O12 has been found to crystallize in two different forms, one with random and the other with ordered Ce/vacancy distribution at the A site of the prototype AA'3B4O12 structure. The random phase is isostructural with CaCu3Ti4O12, and the ordered phase is a new ordered derivative of the AA'3B4O12-type perovskite with two crystallographically distinct Cu sites. Although both phases form a G-type antiferromagnetic arrangement of Cu(2+) spins below 24 K, their magnetisms are quite different.

Magnetic interactions in A-site-ordered perovskites LnCu3(Ge(3/4)Ga(1/4))4O12 (Ln = La, Dy).

A-site-ordered perovskites LaCu(3)(Ge(3/4)Ga(1/4))(4)O(12) and DyCu(3)(Ge(3/4)Ga(1/4))(4)O(12) were synthesized, and their magnetism was investigated. Ferromagnetic ordering of the square-planar-coordinated Cu(2+) spins was observed at 12-13 K in both compounds, and the Dy(3+) moment in DyCu(3)(Ge(3/4)Ga(1/4))(4)O(12) stayed paramagnetic below T(C). The decoupling of the magnetic behavior of Cu(2+) and Dy(3+) sublattices revealed the weak magnetic interaction between Cu(2+) and Dy(3+).

A three-dimensional FRET analysis to construct an atomic model of the actin-tropomyosin-troponin core domain complex on a muscle thin filament.

It is essential to know the detailed structure of the thin filament to understand the regulation mechanism of striated muscle contraction. Fluorescence resonance energy transfer (FRET) was used to construct an atomic model of the actin-tropomyosin (Tm)-troponin (Tn) core domain complex. We generated single-cysteine mutants in the 167-195 region of Tm and in TnC, TnI, and the β-TnT 25-kDa fragment, and each was attached with an energy donor probe.