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Osteoblast reactions to topographic structures of titanium play a key role in host tissue responses and the final osseointegration. Since it is difficult to fabricate micro- and nano-scale structures on titanium surfaces, little is known about the mechanism whereby the topography of titanium surfaces exerts its effects on cell behavior at the cellular level. In the present study, the titanium surface was structured in micron- and submicron-scale ranges by anodic oxidation in either 0.2 M H₃PO₄ or 0.03 M calcium glycerophosphate with 0.15 calcium acetate. The average dimensions of pores in the structured surface were about 0.5 and 2 µm in diameter, with roughness averaging at 0.2 and 0.4 µm, respectively. Enhanced attachment of cells (SaOS-2) was shown on micron- and submicron-scale structures. Initial cell reactions to different titanium surfaces, e.g. the development of the actin-containing structures, are determined by the different morphology of the surfaces. It is demonstrated that on either micron- or submicron-structured surfaces, many well-developed filopodia were observed to be primary adhesion structures in cell-substrate interactions, and some of them entered pores using their distinct tips or points along their length for initial attachment. Therefore, porous structures at either micro- or submicrometre scale supply positive guidance cues for anchorage-dependent cells to attach, leading to enhanced cell attachment. In contrast, the cells attached to a smooth titanium surface by focal contacts around their periphery as predominant adhesion structures, since repulsive signals from the environment led to retraction of the filopodia back to the cell bodies. These cells showed well-organized stress fibres, which exert tension across the cell body, resulting in flattened cells.

Energy loss rates for hot carriers in graphene have been measured using graphene produced by epitaxial growth on SiC, exfoliation, and chemical vapor deposition (CVD). It is shown that the temperature dependence of the energy loss rates measured with high-field damped Shubnikov-de Haas oscillations and the temperature dependence of the weak localization peak close to zero field correlate well, with the high-field measurements understating the energy loss rates by ∼40% compared to the low-field results. The energy loss rates for all graphene samples follow a universal scaling of T 4 e at low temperatures and depend weakly on carrier density ∝n − 1 2 , evidence for enhancement of the energy loss rate due to disorder in CVD samples.

Weak localization in graphene is studied as a function of carrier density in the range from 1 × 10 11 cm −2 to 1.43 × 10 13 cm −2 using devices produced by epitaxial growth onto SiC and CVD growth on thin metal film. The magnetic field dependent weak localization is found to be well fitted by theory, which is then used to analyze the dependence of the scattering lengths L ϕ , L i , and L * on carrier density. We find no significant carrier dependence for L ϕ , a weak decrease for L i with increasing carrier density just beyond a large standard error, and a n −1/4 dependence for L * . We demonstrate that currents as low as 0.01 nA are required in smaller devices to avoid hot-electron artifacts in measurements of the quantum corrections to conductivity.

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