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.
A solicitation letter is one in which you are openely invited by others. For example, a letter to apply for an open vacancy. A solicited letter is one that you requested to receive. For example, a letter you requested to receive to a company event or a job opportunity.