FIG. 2.

The McMillan blast device (MBD). (A) Photo of the entire device. The flanges at the adjacent edges between the compression and expansion chambers are lined with silicone gaskets that seal around a Mylar membrane. In compressed air- or compressed helium-driven mode, the Mylar membrane is naturally ruptured or is ruptured by a 4-point blade affixed to a pneumatic cylinder that is designed to induce complete membrane failure at a pre-determined pressure in the compression chamber. (B) The Mylar sheet is inserted between the compression and expansion chambers of the MBD. (C) For the explosive-driven modes (oxyhydrogen or RDX) a blast plate is inserted between the compression and expansion chambers. The plate contains a manifold for the hydrogen and oxygen, which flow into a flange facing the expansion chamber. The polyethylene bag is inserted over the flange and filled with the hydrogen and oxygen. (D) The reflected (face-on) pressure sensor (PCB model #113A24) embedded in the dorsal surface of the polyurethane rat model. (E) The free field (side-on) sensor (PCB model #137A22). (F) The anesthetized rat is fitted with a Kevlar vest (not shown) and inserted into a mesh netting support. This is then loaded into a shock tube insert. The netting is tightened and securely fastened to prevent rotational movement of the head during blast exposure. The insert is placed into a cutout in the MBD such that the rat is positioned laterally within the expansion chamber of the shock tube approximately 1 foot from the open end, with the left side of the rat facing the blast source. Following blast exposure, the insert is rapidly removed and the rat is removed from the netting (RDX, cyclotrimethylenetrinitramine).