Abstract: A method of synthesizing polyethyleneimine with a substantially linear backbone is disclosed. The method comprises exposing ethylenediamine dissolved in a solution to electromagnetic radiation for a sufficient time to polymerize the ethylenediamine and thereby resulting in formation of polyethylenimine with a substantially linear backbone in the solution. A method of synthesizing a homopolymer with a substantially linear backbone is also disclosed. In addition, a composition comprising polyethylenimine synthesized from the aforementioned method is disclosed, in which the polyethylenimine comprises a backbone conformation that is substantially linear and has a distribution of molecular weights (MW) ranging from 1 kDa to 200 kDa; and the polyethyleneimine has no cytotoxicity at a concentration of 12 ?g/ml.

Abstract: The present invention provides a shared device, a system and method thereof for multiple communications. The shared device connects a telephone receiver, a telephone, and a computer. The telephone receiver of the present invention can be used to make phone calls as well as replace the conventional microphone and speaker disposed in a computer for video conference. Furthermore, the telephone receiver connected to the shared device serves as the microphone and speaker of the computer, and is simultaneously capable of making a phone call to another participant to join the communication.