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:

Disordered Nanowrinkle Substrates for Inducing Crystallization over a Wide Range of Concentration of Protein and Precipitant. There are large number of proteins, the existence of which are known but not their crystal structure, because of difficulty in finding the exact condition for their crystallization. Heterogeneous nucleation on disordered porous substrates with small yet large distribution of pores is considered a panacea for this problem, but a universal nucleant suitable for crystallizing large variety of proteins does not really exist. To this end, we report here a nanowrinkled substrate which displays remarkable ability and control over protein crystallization. Experiments with different proteins show that on these substrates crystals nucleate even at very low protein concentration in buffer. A small number of very large crystals appear for precipitant concentrations varied over orders of magnitude, ∼0.003-0.3 M; for some proteins, crystals appear even without addition of any precipitant, not seen with any other heterogeneous substrates. In essence, these substrates significantly diminish the influence of the above two parameters, thought to be key factors for crystallization, signifying that this advantage can be exploited for finding out crystallization condition for other yet-to-be-crystallized proteins.
{"Chemical": []}