The book collects a few articles on QCD and heavy quarks by close colleagues and friends of Prof. Dr. Nikolai Uraltsev, who passed away early and unexpectedly in 2013. Nikolai Uraltsev was an excellent theorist and a wonderful friend, and this book is to honor his ground breaking work in fundamental physics, such as CP violation, instantons and renormalons in QCD, and in particular his work on the heavy quark expansion.The book summarizes some aspects of QCD from a special perspective, which is relevant for the applications of QCD in the context of weak interactions. This includes CP violation in hadronic processes as well as the hadronic matrix elements in weak decays. The reader will get insight into the special way of understanding fundamental physics, which was peculiar of our former colleague Nikolai Uraltsev.