you cannot use a negated character class to match a q not followed by a u. Negative lookahead provides the solution: q(?!u).
Positive lookahead works just the same. q(?=u) matches a q that is followed by a u
P. Pantel, and M. Pennacchiotti. Ontology Learning and Population: Bridging the Gap between Text and Knowledge, volume 167 of Frontiers in Artificial Intelligence and Applications, IOS Press, (2008)
Y. Li, R. Krishnamurthy, S. Raghavan, S. Vaithyanathan, and H. Jagadish. Proceedings of the 2008 Conference on Empirical Methods in Natural Language Processing, page 21--30. Honolulu, Hawaii, Association for Computational Linguistics, (October 2008)