My organic teacher is still using a program called "beaker" which looks like it was written in DOS and has 8 bit graphics. When I mentioned that Marvin is what I use and that it can predict NMR she said Beaker can do something that no other program can do, predict the change in chemical shifts of hydrogen bonding capable protons, like a hydroxyl hydrogen with changes in concentration. Beaker has a slider which allows you to change the concentration of the compound being examined. And as much as I hate to admit it, she was right. There is no setting for concentration in Marvin. You should add it. She said if someone can show her another program that can do it, she would start using it. Could mean they buy a school wide license from you guys! Plus I would love to prove her wrong, and get her to stop using that awful program.