Not much to elaborate. You're told to bring a stack of documents if you have a scientific or technical background, such as CV, a list of publications, an invitation letter from your US host, a letter from your university etc. If the embassy official isn't satisfied, you are asked to send more documents to a state.gov email address. On one occasion they wanted more information about my work as a programmer before I started my PhD. When they asked me for more documents I was tempted to joke that it doesn't matter what address I use, the email will reach the required destination anyway.