While I appreciate the nominators' desire to preserve the exact words of the notebook, I'm afraid most people will be confused by the construction of the sentence and the use of quotation marks and parentheses. Until I read the notes - which won't be available to people reading the plaque - I was totally mystified.
Another concern in the same sentence is saying that the resistance "was" something "as" the temperature was lowered. The "was" implies an action completed while the "as" suggests a process in progress. I realize this is probably a nit but I think it would be better to say the resistance approached zero or became practically zero as the temperature was reduced or that the the resistance was practically zero after the temperature had been reduced.