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.
Uses of Liquid Nitrogen. Liquid nitrogen is an amazing substance that can be used in a variety of ways. Medical procedures, science experiments and even to make ice cream. Nitrogen is a gas that comprises approximately 78% of the air that we breathe. Liquid nitrogen is a product that is made by compressing the air and heating it until the gas is changed to a different state of matter, liquid.