Geminisem 450

SEM evaluation was performed on a separate set of dentin samples (n = 8 per material) that were subjected to the same lactic acid immersion protocol as the set of specimens used for the MH and pH study. At each of the following time points: 4, 8, 16, and 32 days, 2 dentin samples per restorative material were taken out of the immersion solution, rinsed with distilled water, dried, and sputter-coated with gold (5 nm). The surfaces of dentin samples were observed using a scanning electron microscope (SEM; GeminiSEM 450, Zeiss, Oberkochen, Germany) at 10 kV and 10,000× magnification.

Samples were prepared to visualize the inner and outer surface and the cross section of the electro-spun mesh. The samples were fixed on the SEM-carrier with conductive double-sided adhesive. Coating and imaging were performed with equipment maintained by the Center for Microscopy and Image Analysis, University of Zurich. The samples were coated with a 10-nm film of platinum with a sputter coater (Safematic CCU-010). The examination was by SEM (Zeiss Gemini SEM 450, Zeiss, Jena, Germany) at a high voltage of 5 kV. Pictures were taken at a magnification of 507× and at a brightness of 49%. The detector was set to secondary electrons. The fiber diameter and the thickness of the tube wall were measured by ImageJ (1.53e/Java 1.8.0_172 (64-bit)) using the scale bar from the microscope image. For standardization of the wall thickness, the scheme of a clock was used, and SEM pictures were recorded at 2, 4, 6, 8, 10, and 12 o’clock, respectively. From each image, there were three random measurements. Per each SEM image, a diagonal line was drawn and all the fibers, crossed by the line, were measured.

Thirty individual pyroclasts were carefully extracted from a large ~30 cm by 30 cm by 20 cm tephra sample. Only pyroclasts that could be removed easily and without damage from the lapilli tuff were used in this study. These grains were then sorted into similar sized groups and impregnated with epoxy to form a series of coherent cylinders with a diameter of ~2.5 cm. During impregnation about half of the groups were orientated vertically and half horizontally relative to the long axis of the pyroclast. The cylinders were cut into polished thin sections, centered at the middle of the pyroclasts. The thin sections were then carbon coated using a sputter coater and analyzed under a Philips XL30 SEM in scanning electron mode using with a 15 kV accelerating voltage, a 35 μA beam current, and an average working distance of 12 mm. A series of overlapping images were taken to document the pyroclast, especially its rim. On the same samples, Energy Dispersive X-Ray Spectroscopy (EDS) was performed on a Zeiss Gemini SEM 450 in the SEM Shared Research Facility at the University of Liverpool.

Samples were sputter-coated using the Leica EM ACE600 with a 10-nm layer of gold. SEM was subsequently conducted on a Zeiss Gemini SEM 450 at an accelerating voltage of 5 kV.

To assess changes in surface roughness, discs were analyzed using a contact profilometer (Taylor Hobson, AMETEK GmbH, Weiterstadt, Germany). Six measurements were taken per disc before and after treatment, covering a preset analysis length of 1.5 × 1.5 mm² in 0.5 mm increments along the Y-axis. As the discs displayed continuous parallel grooves after the instrumentation, three measurements were conducted in the direction of instrumentation, with the remaining three taken at a 90° angle to the instrumentation direction. Surface abrasion of each disc was measured using a perthometer (Mahr S2; Perthometer, Thalwil, Switzerland). A total of five measurements, spanning a length of 1.5 mm with 250 μm increments along the X-axis, were analyzed. To evaluate surface changes resulting from instrumentation, the surfaces of two discs per group were examined using SEM (GeminiSEM450, Carl Zeiss, Oberkochen, Germany). Before analysis, the samples were coated with a 6 nm layer of gold. Magnifications of 100×, 1000×, 5000×, 10,000×, and 10 kV were utilized. To determine the size and shape of the released particles, three discs per group were examined. An adhesive tape was used to collect particles from the disc surfaces, and these particles were subsequently analyzed using SEM at the same magnification level.

The optical images of NiSe flakes are obtained by using an optical microscope (BX41M-LED, OLYMPUS, Tokyo, Japan). Elemental analysis of NiSe materials is performed via XPS technology (AXIS UltraDLD, Kratos, UK). The layer thicknesses of the NiSe flakes are determined by using AFM (MicroNano D-5A). The EDX characterization is carried out on a field emission scanning electron microscope (GeminiSEM 450, ZEISS, Oberkochen, Germany) facility with an acceleration voltage of 5 kV. Raman spectroscope (LabRAM HR-800, Horiba, Kyoto, Japan) with a laser excitation wavelength of 532 nm was employed to characterize the Raman spectra of the samples. The grating was 1800 lines mm-1. The laser beam was focused by a 50× objective on the samples. The transmission electron microscope (TEM) sample is prepared by using an isopropanol-assisted transfer technology. The STEM images were recorded by an FEI Talos F200X system (Thermo Scientific, Waltham, MA, USA) with an acceleration voltage of 300 kV.