She has become world renowned for her patented invention of spray on skin for burns victims, a treatment which is continually developing. Via her research, Fiona found that scarring is greatly reduced if replacement skin could be provided within 10 days. As a burns specialist the holy grail for Dr Fiona Wood is 'scarless, woundless healing'.
Scarring is not greatly reduced by spray on skin after 10 days.
There is no evidence that the spray on skin fully loses effectiveness after 10 days. The research likely goes into greater depth of the effects of the spray on skin after the 10 day window. Difficult for AI because this statement seems to disagree with the statement provided that results work within 10 days. 
( z1 reduce :polarity - :ARG0 ( z2 spray :ARG2 ( z3 skin ) ) :ARG1 ( z4 scar ) :degree ( z5 great ) :time ( z6 after :quant ( z7 temporal-quantity :quant 10 :unit ( z8 day ) ) ) )