Abbreviations

BEI

backscattered electron images

c

current needles

c+1, c+2...

one, two-year-old needles

EDS

energy dispersive analyser

UV-A

ultraviolet-A radiation (320-400 nm)

UV-B

ultraviolet-B radiation (280-320 nm)

UV-C

ultraviolet-C radiation (200-280 nm)

SEM

scanning electron microscope

WTD

wax tube distribution