Q150r es rotary pumped sputter coater carbon coater

Macroscopic images of the lyophilizate cake were obtained from the above immediately after the lyophilization process with a D5500 digital camera (Nikon, Tokyo, Japan) equipped with an AF-S DX Micro NIKKOR 40 mm f/2.8G lens (Nikon, Tokyo, Japan).
To observe the structure and morphology of the lyophilizate cake and when trying to discover intact lactobacilli, all samples were also subjected to examination under a scanning electron microscope (SEM; MIRA3, Tescan Orsay Holding, Brno, Czech Republic) equipped with a secondary electron detector. A part of the lyophilized cake was mounted on an SEM stub (carbon double-faced adhesive tape—Agar Scientific, Essex, UK) and coated with gold (20 nm layer, argon atmosphere—Q150R ES Rotary-Pumped Sputter Coater/Carbon Coater, Quorum Technologies, Laughton, UK). SEM images were obtained through a secondary electron detector (an accelerating voltage of 3 kV with various image view fields, and the images of the view fields at 20 µm and 1000 µm are included in this article).

Optical microscope analysis: A NIKON SMZ 1500 stereoscopic microscope (Nikon, Japan) with a72AUC02 USB camera (The Imaging Source, Germany) was used to evaluate the equivalent diameter (ED) and sphericity factor (SF) using 15-fold magnification. A total of 200 beads were randomly chosen for each sample and processed using the NIS Elements AR 4.0 software (Nikon, Japan). ED and SF were calculated and expressed as an arithmetic mean with standard deviation (SD) according to the Equations (1) and (2), respectively [43 ,44 ].
$\mathrm{ED}=\sqrt{\frac{4\mathrm{A}}{\mathsf{\pi }}}\left[\mathrm{mm}\right]$
$\mathrm{SF}=\frac{4\mathsf{\pi }\mathrm{A}}{{\mathrm{p}}^2}$ where A is the area of the bead in square millimeter and p is the perimeter of the bead in millimeters.
Scanning electron microscopy (SEM): Scanning electron microscope (SEM; MIRA3, Tescan Orsay Holding, Czech Republic) equipped with a secondary electron detector (SED) was used to observe surface morphology. Samples fixed onto specimen stub with carbon conductive adhesive tape (Agar Scientific, United Kingdom) were sputtered by Au under argon atmosphere (Q150R ES Rotary-Pumped Sputter Coater/Carbon Coater, Quorum Technologies, United Kingdom) for charging artefact elimination. SEM images were obtained at the 3 kV accelerating voltage.

All samples were subjected to the examination of morphology by means of SEM. Pellet cross-sections were obtained by capturing a single pellet with tweezers and cutting it with a razor blade. The sample preparation for the microscopic measurement included mounting the specimen on a SEM stub using a conductive carbon double-faced adhesive tape (Agar Scientific, Essex, UK) followed by coating with a 20 nm gold layer using the metal sputtering coating method in the argon atmosphere (Q150R ES Rotary-Pumped Sputter Coater/Carbon Coater, Quorum Technologies, Laughton, UK). The sample images were taken with the utilization of a secondary electron detector (SED) at an accelerating voltage of 3 kV by means of a scanning electron microscope (MIRA3, Tescan Orsay Holding, Brno, Czech Republic).