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: w . once daily to rats for 1 , 3 , 6 , 9 and 12 months revealed neurological disorders indicating cerebellum damage ( " valproate encephalopathy " ) .
### Output Text:
w . once daily to rats for 1 , 3 , 6 , 9 and 12 months revealed neurological disorders indicating cerebellum damage ( " <span class="chemical">valproate</span> encephalopathy " ) . 