An apparatus is disclosed including: a housing including a conduit having an inlet port and an outlet port; an insert at least partially disposed within the conduit and including a tapered portion extending from a narrower end proximal the inlet port to a wider end distal the inlet port; and a facility for adjusting the position of the insert within the conduit. In some embodiments, the apparatus is configured to receive a mixed flow of liquid and gas at the inlet port, direct the mixed flow through the conduit around a portion of the insert disposed within the chamber, and outlet the mixed flow at the outlet port.

A high-shear mixing chamber is provided having a single wide slot microchannel that enables a higher throughput, less plugging, and a longer life (e.g., less wear) than typical multi-slotted mixing chambers. The provided mixing chamber may include an inlet and an outlet in fluid communication with a single wide slot microchannel (e.g., via an inlet and outlet plenum). In some aspects, the wide slot microchannel may have a stepped interior such that the wide slot microchannel has portions with different depths. The wide slot microchannel has a first surface opposite a second surface and one or more steps may be formed with the first surface alone, the second surface alone, or with both the first surface and the second surface. The steps may extend a full length of the microchannel between the inlet and outlet chambers.

The invention relates to a coaxial flow device 1 capable of creating comparable microenvironments at various operation scales through the continuous introduction and mixing of nanoparticle precursor solutions for the manufacturing of a dispersion comprising nanoparticles. According to the invention, the device includes first and second coaxial tubes 3, 5 for controlled flows of nanoparticle precursor solutions and a mixing portion 7, wherein a disrupting physical element 21 is arranged to cause formation of the microenvironments. Application to the production of mRNA vaccines.