IDF and MIDFs were taken after freeze-drying, and samples
were prepared by sticking them to one side of double-sided adhesive
tape attached to a circular specimen stub at the other end.
The samples were viewed using an environmental scanning electron
microscope (ESEM) (Quanta200F, FEI Deutschland GmbH,
Kassel, Germany) at 30 kV voltages and 3.0 spot size. Low vacuum
mode was used while operating the ESEM.