 Tear down this wall!  was the challenge issued by United States President Ronald Reagan to Soviet Union leader Mikhail Gorbachev to destroy the Berlin Wall, in a speech at the Brandenburg Gate near the Berlin Wall on June 12, 1987, commemorating the 750th anniversary of Berlin.n the 1963  Ich bin ein Berliner  speech, U.S. President John F. Kennedy stated the support of the United States for democratic West Germany shortly after the Soviet-supported Communist state of East Germany erected the Berlin Wall as a barrier to prevent movement from East to West.
Feedback happens when a microphone picks up sound from speakers and then pipes that same sound back through the speakers and picks it up again. The never-ending loop of ear-pain is frustrating to experience, but fairly easy to fix by adjusting the levels of the speakers and microphone.
Microbiologically influenced corrosion (MIC) is the degradation of materials, usually metal, due to the activity of microorganisms. It is also known as biocorrosion and this form of corrosion mostly takes place underneath biofilms, which consist of colonies of microorganisms attached to a surface[1].MIC applies not only to metals but also to non-metallic surfaces such as concrete and can result in severe industry losses[1].echanism. Corrosion, the oxidation of metal, requires the simultaneous reduction of another chemical. MIC usually takes place in stagnant water, and either dissolved oxygen or hydrogen is reduced in order for the process to proceed[1].