Molecular Biology Problem Solver 17. Sách được nhiều nhà khoa học có uy tín, nhiều kinh nghiệm trong nghiên cứu thực nghiệm trình bày những vấn đề thường hay phát sinh trong phòng thí nghiệm. Do vậy mà sách không trình bày các protocol hay quy trình như các sách khác, thay vào đó các tác giả sẽ trình bày các vấn đề nhằm giúp giúp đọc giả: Tự nâng cao khả năng chẩn đoán nguyên nhân khi gặp các vấn để về kỹ thuật, quy trình, hóa chất, thuốc thử trong quá trình thực nghiệm trong phòng thí. | containers. The vial of 35S labeled methionine you might receive is first dispensed into a primary container which is sealed then placed into a secondary container. The secondary container usually has absorbent material placed in it that will absorb any liquid should there be a spill. It is always prudent to wear some thin plastic gloves when dealing with radioactive materials especially when they first arrive and you have no indication on whether or not they are contaminated. The NRC has set action limits to contaminated surfaces of outer packages and containers and the RSO is required to contact the NRC when these levels are surpassed. The amount of contamination considered significant will differ depending on whether the activity is on the primary container secondary container or the outer package. Based on these action levels an institution sometimes sets its own lower contamination limits. Contact your RSO for more information on contamination limits. Your Count-Rate Meter Detects Radiation on the Outside of a Box Containing 1 mCi of a 32P Labeled dATP. Is It Contaminated When you put a count-rate meter up to the outer package containing the 32P substance you will hear clicking sounds indicating the presence of radioactivity. To determine whether the radiation is coming from contamination on the outside of the package or emanating from the vial of material it is necessary to carry out a wipe test on the package. In the overwhelming majority of cases what the instrument is detecting is called Bremsstrahlung. Bremsstrahlung Bremsstrahlung or braking radiation is created when a beta particle interacts with the shielding material to produce X rays. The Plexiglas vial that contains the radioactive material is sufficient to block essentially all beta emissions but not the X rays. Is Bremsstrahlung dangerous The dose rate detected on the surface of a vial with 1mCi of 32P tends to be between 1 and 5 mrem h while there will be no detectable dose rate three feet away.
