Ordered macroporous silica, a silica gel microhoneycomb (SMH), has been prepared through a method which uses micrometer-sized ice crystals as a template. Template ice crystals, which have a continuous rod shape, a polygonal cross section, and ordered diameters, were grown inside precursor silica hydrogels under a condition where the pseudo-steady-state growth of them continues. Besides their ordered macroporosity, micro-/mesopores develop inside the honeycomb walls through the freeze-drying of SMHs soaked in tert-butyl alcohol. SMHs have straight and polygonal macroporous voids, which are created and retained through the formation and removal of the ice crystals. Micromorphology including macropore size and wall thickness, micro-/mesoporosity inside the honeycomb walls, and thermal stability of SMHs were investigated in detail through scanning electron microscopy observation, nitrogen adsorptiondesorption measurements, and thermogravimetric analysis. It was found that the macropore size of the SMHs can be controlled by changing the immersion rate into a cold bath and the freezing temperature without changing the micro-/mesoporosity of their honeycomb walls. It was also found that the thickness of the honeycomb walls was affected by the SiO 2 concentration and the macropore size. On the other hand, the porosity of the honeycomb walls could be controlled to be microporous as well as mesoporous by hydrothermal treatment of as-prepared SMHs in basic aqueous solutions. Moreover, it was found that SMHs with developed mesopores showed a higher stability against heat treatment.

The aim of this study was to evaluate the effect of surface roughness on the initial attachment of mouse osteoblast-like cells on ceria stabilized zirconia/alumina nanocomposite (NANOZR) and yttria-stabilized zirconia (3Y-TZP) in comparison to those on pure titanium (Ti) and alumina oxide (AO). Specimens with smooth and rough surfaces were prepared by grinding with diamond paper or by sandblasting, respectively. For four substrates examined, the number of attached cells on the rough surface specimens was significantly higher than that on the smooth surface specimens (p < 0.05). Integrin α5 and β1 expression had a greater increase in rough surface specimens than in smooth surface specimens. Actin cytoskeleton organization was, however, similar for both smooth and rough surface specimens. NANOZR and 3Y-TZP produced good cell attachment, similar to Ti and AO. The overall results demonstrated that NANOZR and 3Y-TZP with rough surface could provide good initial cell responses, adequate for future implant usage.

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Extinctions within major pelagic groups (e.g., radiolarians and conodonts) occurred in a stepwise fashion during the last 15 Myr of the Triassic. Although a marked decline in the diversity of pelagic faunas began at the end of the middle Norian, the cause of the middle Norian extinction is uncertain. Here we show a possible link between the end-middle Norian radiolarian extinction and a bolide impact. Two palaeoenvironmental events occurred during the initial phase of the radiolarian extinction interval: (1) a post-impact shutdown of primary and biogenic silica production within a time span of 104–105 yr, and (2) a sustained reduction in the sinking flux of radiolarian silica for ~0.3 Myr after the impact. The catastrophic collapse of the pelagic ecosystem at this time was probably the dominant factor responsible for the end-middle Norian conodont extinction.