In this Article. In this Article. A solitary pulmonary nodule (SPN) is a single abnormality in the lung that is smaller than 3 cm in diameter. Generally, a pulmonary nodule must grow to at least 1 cm in diameter before it can be seen on a chest X-ray.
Osmosis is the scientific process of transferring fluid between molecules. When molecules move in and out of a cell to achieve the same concentration of something, like salt, on both sides, then osmosis is happening.
Osmosis is a form of passive transport thatâs similar to diffusion and involves a solvent moving through a selectively permeable or semipermeable membrane from an area of higher concentration to an area of lower concentration. Solutions are composed of two parts: a solvent and a solute. 1  The solvent is the liquid in which a substance is dissolved; water is called the universal solvent because more materials dissolve in it than in any other liquid. 2  A solute is the substance dissolved in the solvent.