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.
Balloons that are inflated with helium are often used for gifts or party decorations for birthdays, anniversaries, and other special occassions.  Helium is also used in neon signs. If the sign is a bright orange-red color, it is very likely that helium is being used.  In a liquid state, it helps to achieve very low temperatures in electronic devices.  Helium is also used in asthma treatments because it diffuses easily through the lungs. When used this way, it is mixed with oxygen.  Mixed with oxygen, it is used to create an artificial air supply for deep sea divers.  Though it is not actually a use, it is sometimes inhaled because it effects the vocal cords and makes the voice a higher pitch.