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:

Daily sperm production: application in studies of prenatal exposure to nanoparticles in mice. We investigated the influence of maternal airway exposure to nanoparticulate titanium dioxide (TiO2, UV-Titan) and carbon black (CB, Printex90), on male reproductive function in the two following generations. Time-mated C57BL/6J mice were exposed by inhalation to UV-Titan, or by intratracheal instillation with Printex90. Body and testicle weight, sperm content per g testicular parenchyma and daily sperm production (DSP) were assessed. The protocol for assessment of DSP was optimized for application in mice (C57BL/6J) and the influence of different parameters was studied. Maternal particulate exposure did not affect DSP statistically significantly in the F1 generation, although TiO2 tended to reduce sperm counts. Overall, time-to-first F2 litter increased with decreasing sperm production. There was no effect on sperm production in the F2 generation originating after TiO2 exposure. F2 offspring, whose fathers were prenatally exposed to Printex90, showed lowered sperm production. Furthermore, we report statistically significant differences in sperm production between mouse strains.
{"Chemical": ["TiO2", "Printex90", "titanium dioxide", "carbon black"]}