Nasdaq- and JSE-listed advanced materials company ASP Isotopes (ASPI) says oil and gas producer Tetra4 has started commissioning Phase 1 of its liquid helium plant, following engineering optimisation, at the Virginia gas project, in South Africa. The start-up of the liquid helium part of the plant is the key remaining step to realise value from two product streams - liquid helium and liquefied natural gas (LNG) before ASPI ramps up production volumes to nameplate capacity during the second half of this year.