Vhx 7000

Feeding tracks were recorded by melting paraffin and applying it onto a petri-dish evenly. This was placed into one aquarium with 4 additional animals, which were not used previously in experiments. Algae paste was spread over it to encourage feeding on the surface. After one day, the petri-dish was dried, controlled by microscope, and most pronounced feeding tracks were visualized with a Keyence VHX-7000 (KEYENCE, Neu-Isenburg, Germany) (Fig. 11).Figure 11

Feeding tracks left by gastropods on paraffin surface. Only the traces of lateral tooth II cusps are clearly visible. (A–C) Feeding track I from different perspectives: (A) Stacked image in SEM optic; (B, D) Colored surface texture visualized with Keyence VHX-7000. (C, E, F) Feeding track II from different perspectives: (E) Stacked image in SEM optic; (C, F) Colored surface texture visualized with Keyence VHX-7000. Dimensions are given in μm.

Negative control is important to assess potential contamination of samples by the collection and extraction procedures. To check whether there were any MP particles resulting from the sampling method, we poured 14.4 L of deionized water through the plankton net (three replicates) and treated with similar procedure used for the samples from the study sites: dried, filtered, placed in Petri dishes, visually analyzed, and possible MPs photographed using a Keyence VHX-7000 digital microscope at 500–1000× magnification.
We also checked whether there were any MP particles in the laboratory air. We used clean glass microfiber filters (three replicates) that were placed in the opened Petri dishes for 4 h in the working area of the laboratory. Each filter was visually analyzed under the stereoscopic microscope Huvitz HSZ-ZB700, and possible MPs were photographed using a Keyence VHX-7000 digital microscope at 500–1000x magnification.

The surface roughness of cubes was measured using a Keyence VHX7000 (Keyence Germany GmbH, Neu-Isenburg, Germany). By analyzing the depth of focus, a 3D model of the surface was obtained on which surface roughness can be measured.
For relative density analysis, samples were cold mounted in epoxy resin, ground up to 4000 grade sandpaper and subsequently polished manually with a 1 µm diamond suspension. Relative density was measured using the Keyence VHX7000. Using 100× magnification, images of the entire surface were stitched together. The built-in Keyence software distinguished pores and solid material based on contrast changes.
For the analysis of the microstructure, samples were etched with 10% ferric nitrate solution. A Zeiss Scanning Electron Microscope (SEM; Carl Zeiss AG, Oberkochen, Germany) was used. An EDX spectrum was measured to verify chemical composition. EBSD analysis was carried out for a 1 mm × 3 mm field. Average grain size, grain orientation and grain boundary angles were calculated.
Using the same samples as for the relative density measurements, the hardness (HV0.2) was measured with the Qness 30A+ microhardness tester (ATM Qness GmbH, Mammelzen, Germany) along the build direction, in the middle of the sample. A mean of 3 measurements per location was calculated.