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: In excellent cases , mean effective dosages were 0 . 086 + / - 0 . 021 mg / kg / day in infants and 0 . 057 + / - 0 . 022 mg / kg / day in schoolchildren , this difference was statistically significant ( p less than 0 . 005 ) .
### Output Text:
In excellent cases , mean effective dosages were 0 . 086 + / - 0 . 021 mg / kg / day in infants and 0 . 057 + / - 0 . 022 mg / kg / day in schoolchildren , this difference was statistically significant ( p less than 0 . 005 ) . 