Expression of concern: Techno-economic perspective on the use of pyrolysis oil from digestate in spark-ignition engines

The publisher of Aircraft Engineering and Aerospace Technology is issuing an Expression of Concern for the following article Maroušek, J. and Žáková, K. (2025), “Techno-economic perspective on the use of pyrolysis oil from digestate in spark-ignition engines”, Aircraft Engineering and Aerospace Technology, Vol. ahead-of-print No. ahead-of-print. Link to the cited article., which was submitted to the guest-edited special issue ‘AI Applications in High-Speed Aerospace Propulsion Systems’, to inform readers that concerns have been raised regarding its authorship. This special issue has subsequently been cancelled. An investigation by the publisher found a number of articles with multiple concerns, including but not limited to lack of suitability for the scope of the journal and special issue, evidence of third-party involvement, and the inclusion of irrelevant citations. An investigation is ongoing and is currently unresolved. The authors of this paper would like to note that they do not agree with the content of this notice. Further information will be provided by Aircraft Engineering and Aerospace Technology as it becomes available. The publisher of the journal sincerely apologizes to the readers of this article.