Lighting a gas grill, getting an ultrasound, using an ultrasonic toothbrush -- these actions involve the use of materials that can translate an electric voltage into a change in shape and vice versa.

Working the gas grill, which faces the sidewalk, Rivera continually lifted cooked slices of meat and placed them into warm tortillas, made on site from corn flour.

Prepare a charcoal or gas grill.

For a gas grill, turn all burners to high and heat, covered, for 15 minutes, then clean and oil the grate; turn all burners to medium-high.

Raichlen doesn't recommend smoking in a gas grill, however.