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.
Liquid helium is a vital coolant in Magnetic Resonance Imaging (MRI) systems. Air Products supplies cryogenic gases and services to nearly 6,000 MRI sites around the world, and provides gases for over half the world s MRI magnets.iquid helium is a vital coolant in Magnetic Resonance Imaging (MRI) systems. Air Products supplies cryogenic gases and services to nearly 6,000 MRI sites around the world, and provides gases for over half the world s MRI magnets.