In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: CONCLUSIONS : Precurarization with 0 . 04 mg / kg rocuronium was the optimal dose considering the reduction in the incidence and severity of fasciculation and myalgia with acceptable onset time , and the safe and effective precurarization .
### Output Text:
CONCLUSIONS : Precurarization with 0 . 04 mg / kg <span class="chemical">rocuronium</span> was the optimal dose considering the reduction in the incidence and severity of fasciculation and myalgia with acceptable onset time , and the safe and effective precurarization . 