We report radiotracer diffusivities in a Pd43Cu27Ni10P20 melt, presenting for the first time a complete set of data for all components over the whole relevant temperature range. While a vast decoupling of more than 4 orders of magnitude is observed between the diffusivity of Pd and of the smaller components, at the glass transition temperature Tg, the diffusivities of all components merge close to the critical temperature Tc of mode coupling theory. For Pd, the Stokes-Einstein relation holds in the whole range investigated encompassing more than 14 orders of magnitude suggesting the formation of a slow subsystem as a key to glass formation in systems with dynamic asymmetry.

In general, the Stokes-Einstein (SE) equation is well accepted for melts. In the supercooled melt a decoupling of diffusivity and viscosity around the critical temperature Tc of the mode coupling theory is observed. The authors measured simultaneously the P32 and Co57 diffusion in the supercooled melt of the Pd43Cu27Ni10P20 alloy from 573 up to 640K using the radiotracer technique. They found that P and Co have similar diffusivities and compared them to viscosity data using SE equation. This shows that the time scales of Co and P diffusions are decoupled by up to two orders of magnitude from time scales of viscous flow in the supercooled state.

We report (95)Zr and (57)Co radiotracer diffusivities and viscosity data in the equilibrium liquid state of a bulk metallic glass forming Zr(46.75)Ti(8.25)Cu(7.5)Ni(10)Be(27.5) melt (Vitreloy 4) far above the liquidus temperature T(l) that are not affected by convection, as evidenced via quasielastic neutron scattering. Zr diffusion is strongly decoupled from diffusion of the smaller components by more than a factor of 4 at T(l), although it obeys the Stokes-Einstein equation. The results suggest that, in the present Zr-based metallic glass forming systems, diffusion and viscous flow start to develop solidlike, i.e., energy-landscape-controlled, features already in the stable liquid state more than 300 K above the mode coupling temperature T(c).

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Background: Spondylosis leads to an overestimation of bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) but not with quantitative computed tomography (QCT). The correlation between degenerative changes of the spine and QCT-BMD was therefore investigated for the first time. Methods: One hundred thirty-four patients (66 female and 68 male) with a mean age of 49.0 ± 14.6 years (range: 19-88 years) who received a CT scan and QCT-BMD measurements of spine and hip were evaluated retrospectively. The occurrence and severity of spondylosis, osteochondrosis, and spondylarthrosis and the height of the vertebral bodies were assessed. Results: A negative correlation was found between spinal BMD and number of spondylophytes (ρ = −0.35; p < 0.01), disc heights (r = −0.33; p < 0.01), number of discal air inclusions (ρ = −0.34; p < 0.01), the number of Schmorl nodules (ρ = −0.25; p < 0.01), the number (ρ = −0.219; p < 0.05) and the degree (ρ = −0.220; p < 0.05) of spondylarthrosis. Spinal and hip BMD correlated moderately, but the latter did not correlate with degenerative changes of the spine. In linear regression models age, osteochondrosis and spondylarthrosis were factors influencing spinal BMD. Conclusion: Degenerative spinal changes may be associated with reduced regional spinal mineralization. This knowledge could lead to a modification of treatment of degenerative spine disease with early treatment of osteopenia to prevent secondary fractures.