| 摘要 |
<p>A crystalline material sufficiently pure for use in pharmaceuticals may be made by forming a saturated solution of the material, changing the temperature of the solution so it becomes supersaturated, and briefly subjecting the solution to irradiation by high intensity ultrasound, before allowing the solution to cool gradually without further irradiation. The ultrasound may be applied using a vessel with an array of ultrasonic transducers attached to a wall, so each transducer radiates no more than 3 W/cm<2> yet the power dissipation within the vessel is between 25 and 150 W/litre. This method can reduce the metastable zone width to less than 10 K. There is no erosion of the wall and consequently no formation of small particles of metal. It is applicable for example to aspartame, and to amino acids.</p> |
