Dimethicone, also known as polydimethylsiloxane, is a silicon-based polymer that is a man-made synthetic molecule made up of repeating units called monomers. Silicon is the second most abundant element in the Earth's crust after oxygen, and silicon dioxide is also known as sand, commonly found on beaches and shores.
In regards to a job, a refusal letter is written when a company offers a position to an individual who must refuse due to his or her circumstances, such as already having accepted another offer, or simply a lack of interest in this particular job.
If you are found to be ineligible for a visa, you will be given a refusal letter with the specific reason(s) why you were ineligible. If there is a waiver available for the ineligibility, you will be given instructions on how to apply for a waiver. Not all visa ineligibilities have a waiver.