tailieunhanh - Molecular Biology Problem Solver 46

Molecular Biology Problem Solver 46. 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. | What Practices Should the Laboratory Use to Ensure That Storage Phosphor Screens Are Completely Erased before Exposure to a Sample Storage phosphor screens are erased by exposure to white light and light boxes with bright fluorescent bulbs are usually used after scanning to completely erase the residual image. Since one cannot always be sure that the previous user has adequately erased the screen it is a good practice to always erase a screen with white light just before beginning an exposure. This practice also minimizes any background signal on the screen due to prolonged storage in the presence of cosmic radiation or slight contamination of the screen surface. How Can Problems Be Prevented Can These Machines Accidentally Generate Misleading Data Storage phosphor imagers could generate misleading data if the screen was contaminated or incompletely erased so that artifac-tual signals appear in the image. Storage phosphor imagers like other imaging systems can generate misleading or confusing results depending on how the image data are displayed on the computer monitor or in an exported or printed image. Important details might be overlooked or significant artifacts might be intentionally hidden by manipulation of the image display. What Causes the Background with Storage Phosphor Imaging and How Can It Be Reduced Some of the background in storage phosphor images is due to instrument noise or very slight stimulated emission of light from the storage phosphor in the absence of stored energy. This component of the background is a property of the system and cannot be reduced. Another component of the background is due to the absorption of cosmic radiation during the exposure. Shielding the exposure cassette from cosmic radiation with lead bricks during the exposure can reduce this component of the background. This measure is worthwhile only for very long exposure times. For exposures up to a few days long the background due to cosmic radiation is not very significant.