Step 1: Understanding the Concept:
The question asks which listed mixer is an example of a high shear mixer.
Step 2: Key Concept or Approach:
A high shear mixer applies strong, concentrated force to break up and blend viscous or semisolid material, as opposed to devices built for gentle blending of liquids or free-flowing powders.
Step 3: Detailed Explanation:
Turbine and jet mixers both work by moving liquid through the vessel using an impeller or a jet stream, suited to low-viscosity fluids rather than thick masses.
The Nauta mixer uses a slow orbiting screw designed specifically for gentle, low shear blending of dry powders and granules.
The sigma blade mixer instead uses two interlocking blades that rotate toward each other, gripping and kneading the material caught between them with strong shearing force, which is why it is used for thick pastes and semisolid pharmaceutical bases and is classified as high shear equipment.
Step 4: Final Answer:
The sigma blade mixer is the example of a high shear mixer.