UN Thread Types. UN (Unified) is a specification of the shape and dimensions of the thread for a given size (diameter) of fastener and number of threads per inch of fastener length. UN bolts and machine screws are the type of fastener in everyday use in the US, UK, and Canada. UN, UNR, and UNJ thread dimensions are measured in Imperial units.
Causes The airway can become narrowed or blocked due to many causes, including: Allergic reactions in which the trachea or throat swell closed, including allergic reactions to a bee sting, peanuts, antibiotics (such as penicillin), and blood pressure medicines (such as ACE inhibitors) Chemical burns and reactions. Epiglottitis (infection of the structure separating the trachea from the esophagus)
In some cases, doctors can't find the cause of the pleurisy. The most common cause of pleural effusion, or fluid in the pleural space, is congestive heart failure. Lung cancer, pneumonia, tuberculosis, and other lung infections also can cause swelling of the pleura and lead to a pleural effusion. Asbestosis, sarcoidosis, and reactions to some medicines also can lead to pleural swelling and pleural effusion.