In a limited company, the liability of members or subscribers of the company is limited to what they have invested or guaranteed to the company.
The current President pro tempore of the Senate is Utah Republican Orrin Hatch. Elected on January 6, 2015, he is the 90th person to serve in this office.
The vice president is the official head of the senate (really only used for ties in voting), but in terms of an actual elected senator, the official title is the President pro tempore (name for the senator).