Shell noun phrases in scientific writing: A diachronic corpus- based study on research articles in chemical engineering Yunyun Wang, Guangwei Hu * Department of English and Communication, The Hong Kong Polytechnic University, AG430, Core A, Hunghom, Kowloon, Hong Kong article info Article history: Keywords: Shell nouns Diachronic change Chemical engineering Scientific writing abstract A key feature of scientific writing is the use of shell noun phrases to turn human expe- riences into abstract entities. This paper reports on a diachronic study of shell noun phrases in 120 chemical engineering research articles over a span of 40 years, focusing on their lexico-grammatical patterns, functional categories and alternative expressions. A corpus-based analysis revealed a significant decline of cataphoric shell noun constructions, a substantial decline in discourse and cognition shell noun phrases and concomitant changes in the frequencies of alternative constructions (i.e., reporting clauses). These observed patterns of shell noun use can be explained by the joint influences of a general move toward greater authorial visibility in the academic writing of hard disciplines, disciplinary developments specific to chemical engineering, the informalization of aca- demic discourse in response to the perceived need for knowledge and identity negotiation, and the functional interrelationships among various linguistic resources. They demon- strate that diachronic changes to academic writing are contextually embedded and respond to discipline-internal developments, shifting epistemologies, larger social changes, and the versatility of linguistic resources. Ó 2023 Elsevier Ltd. All rights reserved. 1. Introduction Although scientific writing has traditionally been perceived as impartial, factual and resistant to change, it is nevertheless a human artifact that is socially constructed, dynamic, and responsive to socio-historical changes (Bazerman, 1988). The changing landscape of academia over the course of history has profoundly impacted on academic practice and shaped sci- entific language. Against this backdrop, there has been increasing scholarly interest in tracing the diachronic evolution of scientific writing in response to social and epistemological developments, sometimes, over a timescale of several hundred years (e.g., Atkinson, 1996, 1998; Bazerman, 1988; Berkenkotter & Huckin, 2016; Salager-Meyer, 1999). In today’s academic world, the speed of change has accelerated partly because of the unprecedented massive expansion of academic publishing in recent decades (Hyland & Jiang, 2019). Accordingly, recent studies have shifted the focus to diachronic trends in academic discourse over the past 50 years or so. These studies have offered valuable insights into academic discourse by examining an assortment of linguistic and rhetorical features such as metadiscourse (Hyland & Jiang, 2018b), stance (Hyland & Jiang, 2016a), engagement (Hyland & Jiang, 2016b; Poole et al., 2019), authorial presence (Junnier, 2020; Li, 2021), citation (Hyland & Jiang, * Corresponding author. Email: E-mail address: guangwei.hu@polyu.edu.hk (G. Hu). Contents lists available at ScienceDirect English for Specific Purposes journal homepage: http://ees.elsevier.com/esp/default.asp https://doi.org/10.1016/j.esp.2023.05.001 0889-4906/Ó 2023 Elsevier Ltd. All rights reserved. English for Specific Purposes 71 (2023) 178–190