Fei quanta 200 scanning electron microscope

Next, we evaluated the density and porosity of the scaffolds as described previously (Liu et al., 2013 (link)). Scanning electron microscopy (SEM; FEI Quanta 200 Scanning Electron Microscope; FEI, Hillsboro, OR, United States) was performed to observe the morphology of the membranes. Water contact angles were evaluated using a contact-angle analyzer (DSA25S; Data Physics Corporation). We captured random images from five replicates for each group at 1000 × magnification. Photoshop 8.0 was used to evaluate the average fiber diameter based on random images from 20 fiber tissues and 200 sections.

Transmission electron microscopy was carried out using a high-resolution transmission electron microscope (JEM-2100 transmission electron microscope, JEOL, Tokyo, Japan). Microscopic features of membranes were investigated using a FEI Quanta 200 scanning electron microscope (FEI Company, Eindhoven, The Netherlands) at an acceleration voltage of 20 kV.

The main stem at the base of the second internode of the two cultivars was examined at 7 d after flowering under low N. Stem segments (~2 mm) from the base were removed and placed in 4% glutaraldehyde fixative for 4 h, and washed three times for 10 min in 0.1 M phosphate buffer solution (pH 7.2). Samples were then fixed in osmium tetroxide for 2 h, and washed three times for 10 min in 0.1 M phosphate buffer. The sections were dehydrated sequentially in ethanol at concentrations of 50, 50, 70, and 100% for 10 min. Critical point drying with CO₂ or freeze-drying was performed. Samples were kept in a desiccator until metallisation. An FEI Quanta 200 scanning electron microscope (FEI Company, Eindhoven, Netherlands) at 10e15 kV was used for the SEM observations and analysis.

Morphological analysis of RH and RB was performed by FEI Quanta 200 Scanning Electron Microscope (Thermo Fisher Scientific, United States) to determine the surface changes in RB. Samples were carbon-coated, then attached to the SEM sample holder and placed carefully on the analyzing chamber, the chamber was closed with a high vacuum environment, and the pressure was auto-controlled by the machine. The sample morphology was analyzed by the computer connected with the SEM machine.

B. cereus NZRM5 and P. aeruginosa ATCC25668 were grown overnight in MHB and diluted with fresh MHB to achieve 1 × 10⁷ CFU/mL. Bacterial cultures were then treated with 4 mg/mL HICA, or sterile water followed by incubation at 35°C for a total of 120 min. Samples were drawn at various treatment time intervals and the cells were harvested by centrifugation at 10,000 x g for 10 min, washed twice with 0.1 M phosphate-buffered saline (PBS) and used for SEM technique. The cells treated with sterile water served as the untreated control for comparing morphological changes after HICA treatment.
The primary fixation of cells was done with 0.1 M PBS containing 3% glutaraldehyde (Merck, Germany) for at least 8 h. The cell suspensions were passed through 0.4 μm Isopore™ membrane filters (Millipore, Ireland) to place the cells on the membrane. The membranes were washed three times with 0.1 M PBS for 15 min each. Dehydration was performed with rising ethanol concentrations as follows; 25%, 50%, 75%, 95%, and 100% for 15 min each and a final 100% for 1 h. All the samples were dried using a critical point drying apparatus (Quorum technologies, UK), mounted on the aluminium stubs and sputter coated with approximately 100 nm thickness of gold (Bal-Tec, USA). Bacteria were imaged using the FEI Quanta 200 scanning electron microscope (ThermoFisher, USA) at an accelerating voltage of 15 kV.