Dialysis is a grueling ordeal, tethering patients with kidney failure to machines for hours on end while their blood is cleansed of waste and toxins. Imagine now that a tiny implant could purify the blood on a continual basis without the need for complex equipment, catheters and solutions. That's the idea behind new technology being developed by U.S. Kidney Research Corp. The Roseville, Calif., company's computer-assisted artificial kidney prototype is set to begin animal studies the last week of August.