Ask HN: The Ethics of Working with Someone Else's research

I live and work in India. I have some experience of research and development in a certain field. Recently I decided to start up on my own and developed certain algorithms based on available research, which do borrow somewhat from current algorithms. I have an ethics question: I am not American. Most of this current public research is paid for by the US taxpayer (although I did pay a minuscule amount of US tax since I lived there for 2 years). The university that did the research behind the algorithms that I have partaken of (remember I did the coding myself, only looked at papers publicly available; I can't stress this enough) has never responded to my requests for licensing parts of their algorithm (the reason why I try to license is that they have applied for a US patent). They haven't come into the Indian market and I don't have any plans of trying to go outside India (and besides, who's to know if I'll succeed or not at this point). All these preliminaries lead to the question: Do I use the papers in the public domain together with my modifications for a commercial enterprise? Or do I drop it?