Sputter coater em scd500

For scanning electron microscopy (SEM), bacteria were fixed with 3% (vol/vol) glutaraldehyde (Agar Scientific, Wetzlar, Germany) in PBS for at least 4 h, washed in 0.1 M Soerensen’s phosphate buffer (Merck, Darmstadt, Germany) for 15 min, and dehydrated by incubating consecutively in an ascending acetone series (30%, 50%, 70%, 90%, and 100%) for 10 min each and the last step thrice. The samples were critical point dried in liquid CO₂ and then sputter coated (Sputter Coater EM SCD500; Leica, Wetzlar, Germany) with a 10-nm gold/palladium layer. Samples were analyzed using an environmental scanning electron microscope (ESEM XL 30 FEG, FEI, Philips, Eindhoven, The Netherlands) with a 10-kV acceleration voltage in a high-vacuum environment.

For SEM, bacteria were fixed with 3% (v/v) glutaraldehyde (Agar Scientific, Wetzlar, Germany) in PBS for at least 4 h, washed in 0.1 M Soerensen’s phosphate buffer (Merck, Darmstadt, Germany) for 15 min, and dehydrated by incubating consecutively in an ascending acetone series (30, 50, 70, 90, and 100%) for 10 min each and the last step thrice. The samples were critical point dried in liquid CO₂ and then sputter coated (Sputter Coater EM SCD500; Leica, Wetzlar, Germany) with a 10-nm gold/palladium layer. Samples were analyzed using an environmental scanning electron microscope (ESEM XL 30 FEG, FEI, Philips, Eindhoven, Netherlands) with a 10-kV acceleration voltage in a high-vacuum environment.

The morphology of the whiskers was observed by field emission scanning electron microscope (SEM) (Nova NanoSEM 200, FEI). Imaging of sample microstructure was performed in high-vacuum conditions using an ETD detector at a 10 kV accelerating voltage. Before the study, the samples were covered with conductive material (10 nm gold film) using a Leica EM SCD500 sputter coater. The morphology of the whiskers before and after modification was also observed by a STEM detector installed in SEM. In STEM observations, the whiskers were placed on a copper mesh and observed at 25 kV accelerating voltage. The microstructure of composites was also observed by SEM. Whisker dimensions and composite macropore sizes were determined on the basis of microscopic images using measurement and annotation functions on the sample area. At least 50 measurements were performed.

The solid surface is imaged before and after each experiment using Scanning Electron Microscopy (SEM). A FEI Quanta 650 FEG scanning electron microscope (SEM) is used for this purpose which is connected to an Energy Dispersive Spectroscopy (EDS) detector. The images are taken in Concentric BackScatter mode. For the first sample (Bentheimer Sandstone), we only aim to identify whether microbial activities were present during the experiment. As such, the SEM imaging technique following the standard procedure was used, as it allows for identification of the microbial activity by detecting some traces of the formation of biofilm. For the second experiment (pure Quartz sample), however, it was also aimed to study the structure of the fairly intact biofilm. Therefore, the following preservation procedure was carried out immediately after taking the sample out of the captive-bubble cell: (1) Place the sample in 2.5% glutaraldehyde in the fridge at 4^∘ to 7^∘ C overnight to fix the biofilm on the sample, (2) Wash the sample with water twice, (3) Let the sample air dry overnight, and (4) Sputter the sample with gold. For the gold sputtering a Leica EM SCD 500 sputter coater is used.