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: By day 4 , foot process effacement was complete and proteinuria appeared in parallel with signs of size barrier damage .
### Output Text:
By day 4 , foot process effacement was complete and proteinuria appeared in parallel with signs of size barrier damage . 