A process for depositing porous silicon oxide-based films using a sol-gel approach utilizing a precursor solution formulation which includes a purified nonionic surfactant and an additive among other components, where the additive is either an ionic additive or an amine additive which forms an ionic ammonium type salt in the acidic precursor solution. The invention also provides a vaccine comprising a CHIV immunogen and a pharmaceutically acceptable carrier. The inverter assembly may include a housing enclosing a symmetrical DC input portion, a symmetrical AC output portion, a DC link capacitor, and a gate drive portion having a pair of power modules. The SIP-INVITE message contains a Universal Resource Identifier identifying the non-SIP client as a destination of the bearer flow.