Md dac

Thread cross-sections were prepared by embedding the threads of S. formivorus in epoxy resin (EpoFix, Struers) with a resin to hardener ratio of 15:2. After complete hardening for 3 days, the epoxy blocks were ground stepwise using silicon carbide abrasive paper discs ending up with an abrasive particle size of 2.5 µm. Polishing was carried out using MD-Dac, MD-Nap and MD-Chem discs (Struers) applied with suspensions of diamonds with 3, 1 and 0.04 µm particle sizes, respectively.

The control bismuth oxide, as received, and the dark powder produced after exposure to sodium hypochlorite solution for 24 weeks, were examined by SEM, both loose and in ground section. Embedding was in epoxy resin (Epofix, Struers, Ballerup, Denmark), which when set was ground using an automatic polishing machine (Phoenix Beta; Buehler, Lake Buff, USA) with progressively finer diamond discs (MD-Piano 200 ~ 1200 grit; Struers) under water, and then polished on cloth (MD-Largo, MD-Dac, MD-Nap; Struers) using diamond-impregnated polishing liquids (DiaPro 9 μm, 3 μm, 1 μm; Struers). The materials were viewed using a low-vacuum scanning electron microscope (Phenom XL; Thermo Fisher Scientific, Eindoven, The Netherlands) using backscatter mode at 10 kV.