High-frequency spindles

Internal circular grinding machines are usually equipped with high frequency grinding spindles (three-phase asynchronous motors) and frequency converters for continuously variable speed control. As a measure of the mechanical power emitted by the grinding spindle, one can use the electrical output power delivered by the converter, which can easily be acquired by conventional measurement techniques. The required control variable - one speaks in this case of constant-power grinding - is therefore almost free of charge. 

In contrast, high concentrations of methylmercury (1 or 2 m) did not increase the frequency of sister chromatid exchanges in cultured blastocysts of early ICR mouse embryos (Matsumoto and Spindle 1982). Severe toxicity, which was more intense in blastocysts than in morulae, consisted of cessation of preimplantation development, blastocoel collapse, and mitotic delay. 

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