Intense magnetic fields have been shown to affect memory-related behaviours of rodents. A series of experiments was performed to investigate further the effects of a 50 Hz magnetic field on the foraging behaviour of adult, male C57BL/6J mice performing a spatial learning task in an eight-arm radial
The effects of ultrasound irradiation on a biodegradable 50-50% copolymer of polylactic and polyglycolic acids
β Scribed by Agrawal, C. M. ;Kennedy, M. E. ;Micallef, D. M.
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 926 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0021-9304
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β¦ Synopsis
The aim of this study was to investigate the effects of ultrasound irradiation on a biodegradable drug delivery system. Microporous, disk-shaped specimens of a 50-50% copolymer of polylactic and polyglycolic acids were gel cast from an acetone solution. A protein was incorporated in these specimens, which were then immersed in phosphate buffered saline and subjected to ultrasound irradiation every second day. The investigation was performed in two phases: in the first, a study was performed for 58 days to determine if ultrasonic irradiation affected the kinetics of protein release from the specimens. In the second phase, effects of frequency and duration of the ultrasound signal on the degradation of the implant were studied for 40 days. The results indicate that ultrasound irradiation resulted in almost a threefold increase in protein elution from the specimens. Both the ultrasound frequency and signal duration affected the molecular weight loss and mass loss, and changed the overall degradation kinetics of the polymer.
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By usiiig optical rotatory dispersion measurements, the helix content of poly G 1 ~5 ~L y s 5 ~ has been investigated and compared with that of poly G1u20Lys20AlaGa in aqueous solutions. RLeasurements were made at pH 3 and at pH 8 in various concentrations of lithium bromide. Various factors affecti
## Abstract ## Background. Previous work from this department has shown that resistive tracheostomy filters increase the partial pressure of oxygen in capillary blood and also provide a significant amount of heat/moisture exchange. Until now it has not been shown whether there is any longβterm ben