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: Effects of the novel compound aniracetam ( Ro 13 - 5057 ) upon impaired learning and memory in rodents .
### Output Text:
Effects of the novel compound <span class="chemical">aniracetam</span> ( <span class="chemical">Ro 13 - 5057</span> ) upon impaired learning and memory in rodents . 