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:

Structure of hydrated cobalt ions confined in the nanospace of single-walled carbon nanotubes. The structure of hydrated Co ions confined in the nanospace of single-walled carbon nanotubes (SWNTs) has been studied using the X-ray absorption fine structure (XAFS) technique. Water adsorption isotherms on Co-impregnated SWNTs indicate a high affinity of Co ions to water molecules. The results of XAFS analysis provided the information on the proportion of dissolved species in nanospaces against the total amount of cobalt ions adsorbed on the open-pored SWNT. The structural information of the first shell around a Co ion was expressed in terms of the hydration number, Co-O distance and Debye-Waller factor. The actual coordination number and the interatomic distance of Co-O for the dissolved species were remarkably reduced compared to the bulk aqueous solution indicating the dehydration of water molecules from Co ions and a compact hydrated structure in the micropore of SWNTs.
{"Chemical": ["carbon", "Co", "cobalt", "Co-O"]}