PubMed · 5203400
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R E Thompson. 1970. Static electricity--causes and controls.. https://doi.org/10.1016/s0001-2092(07)63690-4
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Powered toothbrushes were first developed over 50 years ago. More recent advances in design and technology mean that there are now a considerable number of different models available on the market. It is not surprising, therefore, that patients, when considering buying a powered toothbrush, often turn to their general dental practitioner for advice.
PURPOSE: To evaluate the usefulness of low-vacuum, low-voltage scanning electron microscopy (LVSEM) in examining the surfaces of intraocular lenses (IOLs) without preparation. SETTING: In vitro laboratory experiment. METHODS: Six commercially available IOLs made of poly(methyl methacrylate) (PMMA) and one explanted PMMA IOL were evaluated with LVSEM without sputter coating. Sham surgical maneuvers were performed on some IOLs and the surface changes observed. RESULTS: Smooth surfaces of IOL optics and haptics, relatively sharp edges of optic holes, and irregularities at the optic/haptic junction were clearly observed. Crystalline deposits were seen on the surfaces after the IOLs were dipped and dried in saline solution. Scratches and marks were observed after they were grasped with a forceps. CONCLUSIONS: Low-vacuum, low-voltage scanning electron microscopy is a time-saving procedure that can be used by inexperienced investigators. The resolution under relatively low magnification appeared to be satisfactory for evaluating the IOL surface.
A new quantity termed the "practical peak voltage" is proposed. This quantity is derived by equating the low level contrast in an exposure made with an X-ray tube connected to a generator delivering any arbitrary wave form, to the contrast produced by the same X-ray tube connected to a constant potential generator. Out of the great number of possible contrast configurations one is selected as being suitable for diagnostic radiology. By means of an eigenvalue problem a direct link is established between the electrical quantity X-ray tube voltage and the practical peak voltage which was initially defined through the properties of the X-ray field. It is shown that the spread in total X-ray tube filtration as encountered in medical diagnostic radiology can influence the result of a measurement of the practical peak voltage only marginally.