Science / Chemistry / Molecular Sieve: A material that contains many small cavities interconnected with pores of precisely uniform size. Zeolites are an example. Molecular sieves adsorb molecules that are small enough to pass through their pore systems- especially water. They are often used as drying agents, and to separate large molecules from smaller ones in preparatory work and in exclusion chromatography.
Science / Biology / Sieve Cells: Conducting cells in the phloem of vascular plants. See sieve elements MORE
Science / Chemistry / Molecular Weight: The average mass of a molecule, calculated by summing the atomic weights of atoms in the molecular formula. Note that the words mass and weight are often used interchangeably in chemistry. MORE