Retraction notice to “Optimization of variable compression ratio diesel engine fueled with Zinc oxide nanoparticles and biodiesel emulsion using response surface methodology” [Fuel 323 (2022) 124290] (Fuel (2022) 323, (S0016236122011425), (10.1016/j.fuel.2022.124290))

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been retracted at the request of the Editor in Chief. An investigation identified violations of the journal's policies on authorship related to this paper. Authorship changes were made during both revisions of this paper: Two authors were removed at the paper's first revision. The authors Van Tam Bui and Xuan Phuong Nguyen were added at the same stage. One of these added authors was then subsequently removed at the final revision. One additional author (Zafar Said) was also added to the paper at the final revision. These changes were made without validation or authorisation. This breached the journal's policy on authorship. The Corresponding (and other) Authors responded to requests for clarification on these points, but those explanations did not satisfactorily address the concerns. As such and due to the nature of the irregularities uncovered, the Editor has lost confidence in the validity/integrity and findings of the article and decided to retract the article. The scientific community takes a very strong view on this matter and apologies are offered to readers. The Authors do not agree with the decision to retract the paper and dispute the grounds for it.