Zahn Viscosity

A parameter intended to approximate fluid viscosity and measured by a specific kind of orifice viscometer. The measurement unit is Zahn seconds. See also Orifice Viscometer, Table 13.

Z-average Mean

The hydrodynamic (equivalent spherical) diameter of a particle, droplet, or bubble in a fluid, as determined by dynamic light scattering. See Equivalent Diameter; Table 7.

Zeitfuchs Viscometer

A kind of capillary viscometer. See Capillary Viscometer, Table 13.


A class of aluminosilicate minerals having large cavities in their crystal structures. These cavities allow ion exchange of large ions and also can permit the size-selective passage of organic molecules. Zeolites are used as ion exchangers, molecular sieves, and catalysts.

Zernike, Frits (Frederik) (1888–1966)

A Dutch physicist and mathematician. He won the 1953 Nobel Prize in physics for his demonstration of the phase contrast method and his invention of the phase-contrast microscope. Eponyms include the Zernike crater on Earth's moon. See also Binnig, Gerd K. (1947–), Ruska, Ernst (1906–1988), and Zsigmondy, Richard Adolf (1865–1929) for some other key advances in microscopy.

Zero-Dimensional Object

In nanoscience and nanotechnology a zero-dimensional object traps its constituent subparticles in all three dimensions. In a quantum dot, for example, the electrons are trapped in all three dimensions, forcing the electrons into standing waves of probability and making for an approximately ...

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