The second law of thermodynamics says that the entropy of the universe (or any isolated system therein) is increasing; i.e., the energy of the universe is becoming more uniformly distributed. It is often noted that the second law indicates that nature tends to go from order to disorder, from complexity to simplicity.
Small-bore catheters and Heimlich valves have been successfully used in. the treatment of pneumothoraces in several studies.4,5 The thoracic vent. (see Figure 1) is a minimally invasive device for the treatment of. pneumothorax. It consists of a polyurethane catheter connected to a. plastic chamber containing a one-way valve.
Ducts are used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The needed airflows include, for example, supply air, return air, and exhaust air.Ducts commonly also deliver ventilation air as part of the supply air.