Container containing a gassed acidulated beverage capable of producing a foam when the container is opened and the beverage poured. The outer sleeve delimits an helical track, the inner sleeve delimiting an axial track intersecting the helical track. By arranging the thrust bearing assembly within the hollow shaft, the size of the drive apparatus is reduced to the size of the motor unit. The chatVoIP client and the chatVoIP service application may be arranged such that privileged use of the mobile telecommunications network is enabled, providing a session between the user equipment and a communication environment with a predetermined or agreed Quality of Service. Also provided herein are polyfarnesenes derived from a farnesene; at least two different vinyl monomers, such as acrylic acid, acrylic esters, styrene, and substituted styrenes; and at least one functional comonomer such as maleic anhydride. The carbon dioxide content of an escaping gas stream is monitored.