Symptoms of seminal vesiculitis range from vague back or lower abdominal pain; penile, scrotal, or perineal pain; irritative and obstructive voiding symptoms or impotence. In addition to the above mentioned symptoms, in addition, it could cause painful ejaculation, hypoactive sexual interest disorder, spermatorrhea, decrease of sperm, and prospermia. When a mixture of different substances is rotated at extremely high speeds within a closed path (in your case a closed container), substances of higher mass often go on to the outermost path and lighter particles experience the nearest to rotating axis. The same principle can be used in centrifuge oil cleaning.