In a recent post on math.se, I suggested that G. Peano's Arithmetices principia, nova methodo exposita (1889) was probably the last important scientific work written in Latin. This work set forth the so-called Peano axioms, which are still of major importance.
I suppose there must be something published in Latin by the Vatican astronomer. Let's disqualify Vatican-related holdouts. Other than these, is there any significant scientific or mathematical work written in Latin after 1889?