A tungsten-based ductile metallic glass with the composition W46Ru37B17 was produced by a single-roller melt-spinning procedure. The differential scanning calorimetry measurement showed a two-step crystallization with the first crystallization temperature as high as 1174 K. Young’s modulus of the glass at room temperature was estimated to be 309±20 GPa by a nanoindentation test and the Vickers hardness at room temperature was 16.8±1 GPa. These values are higher than those of any metallic glasses so far reported. High-temperature Vickers hardness test indicated that the hardness value is higher than 10 GPa up to 900 K.

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Ternary and quaternary tungsten-based alloys were melt-spun to produce metallic glasses having high crystallization temperature and high hardness. Alloy compositions were selected based on eutectic compositions of tungsten-based binary alloys; they are W 46 Ru 37 B 17 , W 54 Rh 26 B 20 , W 56 Ir 23 B 21 , etc. In most of the alloys, ductile metallic glasses were produced. DSC measurements showed that most of the metallic glasses undergo a two-step crystallization with the onset temperature of the first crystallization being as high as 1049$1298 K. Vickers hardness values at room temperature are 13$17 GPa. The ratio of the hardness H v to Young's modulus E satisfies the general rule for metallic glasses, i.

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We have studied the stiffness of myofilament lattice in sarcomeres in the pre-force generating state, which was realized by a relaxing reagent, BDM (butane dione monoxime). First, the radial stiffness for the overlap regions of sarcomeres of isolated single myofibrils was estimated from the resulting decreases in diameter by osmotic pressure applied with the addition of Dextran. Then, the radial stiffness was also estimated from force-distance curve measurements with AFM technology. The radial stiffness for the overlap regions thus obtained was composed of a soft and a rigid component. The soft component visco-elastically changed in a characteristic fashion depending on the physiological conditions of myofibrils, suggesting that it comes from cross-bridge structures. BDM treatments significantly affected the soft radial component of contracting myofibrils depending on the approach velocity of cantilever: It was nearly equal to that in the contracting state at high approach velocity, whereas as low as that in the relaxing state at low approach velocity. However, comparable BDM treatments greatly suppressed the force production and the axial stiffness in contracting glycerinated muscle fibers and also the sliding velocity of actin filaments in the in vitro motility assay. Considering that BDM shifts the cross-bridge population from force generating to pre-force generating states in contracting muscle, the obtained results strongly suggest that cross-bridges in the pre-force generating state are visco-elastically attached to the thin filaments in such a binding manner that the axial stiffness is low but the radial stiffness significantly high similar to that in force generating state.

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