Abstract: In the illustrative embodiment, a thermoformed plastic face shield includes a shield portion and an integrated strap. The shield portion includes several protrusions configured to hold the face shield away from the face of the user of the face shield. The strap can be removed from the shield portion and attached to the shield portion to form an assembled face shield. The plastic face shield can be formed from a sheet of plastic in a single thermoforming step.

Abstract: A thermodynamic waste heat transfer system including a refrigerant working fluid, an evaporator to absorb waste heat from a source, especially a communication transmitter, and a condenser to discard the waste heat. The fluid enters the evaporator in liquid form, boils in the evaporator, migrates in gaseous form upward to the condenser, returns to liquid form in the condenser, and returns via gravity to the evaporator. Refrigerant R-114 is the preferred fluid. The evaporator is mounted on the source to catch hot exhaust air carrying waste heat from the source which waste heat is discarded via the condenser into ambient air outside a closed building containing the source. Because the evaporator is at a lower elevation than the condenser no pump is needed, primary action producing desired flow of the refrigerant.