MRI of a knee. MRIs employ powerful magnets which produce a strong magnetic field that forces protons in the body to align with that field. When a radiofrequency current is then pulsed through the patient, the protons are stimulated, and spin out of equilibrium, straining against the pull of the magnetic field.
Noun. 1. aestivation - (zoology) cessation or slowing of activity during the summer; especially slowing of metabolism in some animals during a hot or dry period. estivation. zoological science, zoology-the branch of biology that studies animals.
The Passivation Process. Passivation of metal, similar to electropolishing, is a metal finishing operation that many industries specify for their parts. Passivation is a chemical process designed to increase the corrosion resistance of stainless steel parts. To passivate stainless steel parts, the parts are placed in a basket and submerged in a nitric or citric acid bath.