At the object level . Permissions allowed or denied at the object level apply to the entire object. For example, you can set an object-level permission on an OU object that allows a particular group, such as Account Operators, to create child objects in the OU. At the property level .
Ball mills are used in chemistry and in industry to grind hard solids to a very fine powder. They are very similar to rock tumblers. Basically, the idea is to rotate a container filled with heavy metal balls that crush the substance that you want to grind.
grind. 1. to wear, smooth, or sharpen by abrasion or friction; whet: to grind a lens. 2. to reduce to fine particles, as by pounding or crushing; pulverize. 3. to oppress, torment, or crush: ground by poverty. 4. to rub harshly or gratingly; grit: to grind one's teeth.