The charge-density wave is a phenomenon observed in certain materials.

Regular exercise can help improve bone mineral density.

The relative densities of the two substances are significantly different.

The charge densities of the ions in the solution were measured.

The vapour densities of the two substances are significantly different.

Regular exercise can help improve bone densities.

The agricultural densities in this region are quite high.

The arithmetic densities of the population in the city and the suburbs are significantly different.

The bulk densities of the samples were measured using a gravimetric method.

The column densities of the elements were measured using spectroscopic techniques.