Hello Judy, there is a link at the bottom of the referenced article to what looks like the original published paper, entitled: "On holes and strings: Earliest displays of human adornment in the Middle Palaeolithic", found here:

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0234924

Thermoluminenscence is mentioned re: the Misliya Cave. For the Qafzeh Cave, the shells were found directly under burials. Striations on five of the Qafzeh shells were microscopically analyzed, then evidently reproduced on shells using hand-made wild flax string (see Microwear Analysis and Discussion) via natural suspension. Hopes this helps.

j