You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Highly Stretchable Patterned Gold Electrodes Made of Au Nanosheets. Multilayered Au nanosheets are suggested as a novel class of material for fabricating stretchable electrodes suitable for organic-based electronic devices. The electrodes show no difference in resistivity during repeated stretching cycles up to ϵ = 40%.
{"Chemical": ["Au"]}