Complex multiple introductions drive fall armyworm invasions into Asia and Australia.

The fall armyworm (FAW) Spodoptera frugiperda is thought to have undergone a rapid 'west-to-east' spread since 2016 when it was first identified in western Africa. Between 2018 and 2020, it was recorded from South Asia (SA), Southeast Asia (SEA), East Asia (EA), and Pacific/Australia (PA). Population genomic analyses enabled the understanding of pathways, population sources, and gene flow in this notorious agricultural pest species. Using neutral single nucleotide polymorphic (SNP) DNA markers, we detected genome introgression that suggested most populations in this study were overwhelmingly C- and R-strain hybrids (n = 252/262). SNP and mitochondrial DNA markers identified multiple introductions that were most parsimoniously explained by anthropogenic-assisted spread, i.e., associated with international trade of live/fresh plants and plant products, and involved 'bridgehead populations' in countries to enable successful pest establishment in neighbouring countries. Distinct population genomic signatures between Myanmar and China do not support the 'African origin spread' nor the 'Myanmar source population to China' hypotheses. Significant genetic differentiation between populations from different Australian states supported multiple pathways involving distinct SEA populations. Our study identified Asia as a biosecurity hotspot and a FAW genetic melting pot, and demonstrated the use of genome analysis to disentangle preventable human-assisted pest introductions from unpreventable natural pest spread.

Assessing the feasibility of chemical recycling via steam cracking of untreated plastic waste pyrolysis oils: Feedstock impurities, product yields and coke formation.

Chemical recycling of plastic waste to base chemicals via pyrolysis and subsequent steam cracking of pyrolysis oils shows great potential to overcome the limitations in present means of plastic waste recycling. In this scenario, the largest concern is the feasibility. Are plastic waste pyrolysis products acceptable steam cracking feedstocks in terms of composition, product yields and coke formation? In this work, steam cracking of two post-consumer plastic waste pyrolysis oils blended with fossil naphtha was performed in a continuous bench-scale unit without prior treatment. Product yields and radiant coil coke formation were benchmarked to fossil naphtha as an industrial feedstock. Additionally, the plastic waste pyrolysis oils were thoroughly characterized. Analyses included two dimensional gas chromatography coupled to a flame ionization detector for the detailed hydrocarbon composition as well as specific analyses for heteroatoms, halogens and metals. It was found that both pyrolysis oils are rich in olefins (∼48 wt%) and that the main impurities are nitrogen, oxygen, chlorine, bromine, aluminum, calcium and sodium. Steam cracking of the plastic waste derived feedstocks led to ethylene yields of ∼23 wt% at a coil outlet temperature of 820 °C and ∼28 wt% at 850 °C, exceeding the ethylene yield of pure naphtha at both conditions (∼22 wt% and ∼27 wt%, respectively). High amounts of heavy products were formed when steam cracking both pyrolysis oils, respectively. Furthermore, a substantial coking tendency was observed for the more contaminated pyrolysis oil, indicating that next to unsaturated hydrocarbons, contaminants are a strong driver for coke formation.

Pyrolysis of end-of-life polystyrene in a pilot-scale reactor: Maximizing styrene production.

Chemical recycling of polystyrene (PS) via pyrolysis is of great industrial, and academic interest, with styrene being the primary product of interest. To identify the optimal process conditions, the pyrolysis of end-of-life PS was studied in a pilot-scale unit consisting of an extruder, and a continuous stirred tank reactor (CSTR). The PS was pyrolyzed with continuous feeding at a pressure range from 0.02 to 1.0bara, and a temperature range from 450 to 600 °C, giving primarily styrene, other mono-aromatics, and oligomers. The comprehensive two-dimensional gas chromatography (GC × GC) coupled with flame ionization detector (FID), and time-of-flight mass spectrometer (ToF-MS) as well as GC with thermal conductivity detector (TCD) were used to characterize the liquid, and gaseous products exhaustively. The styrene yield increased from 36 wt% at 1.0bara, and 450 °C to 56 wt% at 0.02bara, and 550 °C. Working under a vacuum enhanced the styrene recovery at all corresponding temperature levels. The yield of benzene, toluene, ethylbenzene, and xylene (BTEX) increased from 4 wt% at 450 °C, and 0.02 bara to 17 wt% at 450 °C, and 1.0 bara. The experimental results have been used in a mathematical model that can explain the combined effect of temperature, and pressure on the yield of the primary products. The present work illustrates the potential of a continuous pyrolysis process for end-of-life PS, and paves the way for this technology to be rapidly transferred from mere laboratory use to industrial processes in the circular (petro-) chemical industry.

Formation of Fluorinated Amido Esters through Unexpected C3-C4 Bond Fission in 4-Trifluoromethyl-3-oxo-ß-lactams.

4-Trifluoromethyl-3-oxo-ß-lactams were unexpectedly transformed into 2-[(2,2-difluorovinyl)amino]-2-oxoacetates as major products, accompanied by minor amounts of 2-oxo-2-[(2,2,2-trifluoroethyl)amino]acetates, upon treatment with alkyl halides and triethylamine in DMSO. This peculiar C3-C4 bond fission reactivity was investigated in-depth, from both an experimental and a computational point of view, in order to shed light on the underlying reaction mechanism.