Disclosed is a product and method for transplanting biological fluids into a host animal that have been collected from donor animals. Apparatus for rotationally positioning one or more of the ultrasonic transducer supporting devices in proximity of the pipe to enable ultrasonic defect testing thereof, comprises means for rotating the or each device around at least part of the pipe’s circumference whilst maintaining the or each device in proximity of the pipe. The variable resistance module comprises a resistance network including at least one resistor and an interface including a plurality of contacts. As a result, it is possible to increase a density of particles filled in the concave portion. Before a structure is coated with the low-work function material, a metal oxide layer is formed on the structure.