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:

Synthesis of superconducting nanocables of FeSe encapsulated in carbonaceous shell. The recent discovery of superconductivity in iron selenide has attracted considerable attention due to the simplicity of composition, unconventional nature of superconductivity, and ease of synthesis. We have synthesized superconducting FeSe nanowires with a simple catalyst-aided vapor transport reaction at 800 °C in an inert atmosphere. The precursors were chosen to be elemental Se and iron acetylacetonate [Fe(III)(C₅H₈O₂)₃]. These vaporized very easily, thereby facilitating transport, and also contributed to the formation of a carbonaceous shell encapsulating the FeSe nanowires. The superconductivity of these nanocables was confirmed through magnetic measurements and a T(c) of ≈8 K was obtained for an ensemble of nanocables. The length of FeSe filling inside the carbon nanofibers could be varied by controlling the reaction conditions while the diameter of nanowires was dependent on the thickness of Au-Pd coating used as a catalyst. Extensive analysis through high-resolution microscopy revealed that there was considerable lattice contraction of FeSe in the nanocable up to about 3.6% along the c-direction leading to a reduced spacing between the (001) lattice planes. Interestingly, this compression was more pronounced near the catalyst-FeSe interface and was reduced further along the length of the nanocable. The presence of carbon nanofibers as a shell around the FeSe protected the FeSe nanowires from both atmospheric O₂ and moisture attack, as was evident from the very long ambient condition shelf life of these nanocables, and also makes them more stable under e-beam irradiation.
{"Chemical": ["iron selenide", "iron acetylacetonate", "O\u2082", "Se", "Fe(III)(C\u2085H\u2088O\u2082)\u2083", "carbon", "Au-Pd", "FeSe"]}