A pulmonary nodule is a discrete opacity in the lung which may be caused by: 1  Neoplasm: benign or malignant. 2  Granuloma: tuberculosis. 3  Infection: roundish pneumonia. 4  Vascular: infarct, varix, granulomatosis with polyangiitis, rheumatoid arthritis.
1 Helium is also commonly used to pressurize and purge systems of unwanted gases. 2  It is also used in controlled atmospheres when the levels of different gases have to be kept constant. 3  It is used as a protective gas when growing silicon and germanium crystals and when producing titanium and zirconium.
Common Uses of Nitrogen. This element is present in virtually all pharmacological drugs. In the form of nitrous oxide it is used as an anesthetic. Cryopreservation also uses the gas to conserve egg, blood, sperm and other biological specimens. The CPUs in computers use the gas to keep them from heating up.