Postdoc Publications: Winter 2013/2014

Featured Postdoc Publications*:

Antonio Picon, Postdoctoral Appointee in XSD published his work on extreme ultraviolet vortices in the journal Physical Reviews Letters.

Antonio’s article was recently featured on the Postdoctoral Blog.

Carlos Hernandez-Garcıa, Antonio Picon, Julio San Roman, and Luis Plaja. Attosecond Extreme Ultraviolet Vortices from High-Order Harmonic Generation. Phys. Rev. Lett. 111.

We present a theoretical study of high-order harmonic generation (HHG) and propagation driven by an infrared field carrying orbital angular momentum (OAM). Our calculations unveil the following relevant phenomena: extreme-ultraviolet harmonic vortices are generated and survive to the propagation effects, vortices transport high-OAM multiples of the corresponding OAM of the driving field and, finally, the different harmonic vortices are emitted with similar divergence. We also show the possibility of combining OAM and HHG phase locking to produce attosecond pulses with helical pulse structure.

Michael Johnson, a recent Argonne Postdoc Alumnus, published his work on hydrothermal processing of algal cells for producing biofuels in the journal Industrial $ Engineering Chemistry Research. Michael also presented his work at The 3rd International Conference on Algal Biomass, Biofuels and Bioproducts June 16-19 in Toronto.

Johnson, M.C., Tester, J.W. Lipid Transformation in Hydrothermal Processing of Whole Algal Cells. Industrial & Engineering Chemistry Research. doi:10.1021/ie400876w

Hydrothermal processing may provide an attractive alternative for producing biofuels with microalgae. Hydrothermal processing can be used with wet feedstocks without needing energy-intensive drying or solvents for oil recovery as is typical for algae biofuel processes. In this study, microalgae strains Isochrysis sp. and Thalassiosira weissflogii were processed in a hydrothermal batch reactor at temperatures of 250–350 °C and residence times up to 3 h. Triglyceride feedstock hydrolysis in hydrothermal systems was modeled using previously identified methods. Kinetic parameters for triglyceride hydrolysis were fit to literature data. Degradation of unsaturated fatty acids in hydrothermal systems was modeled by adding reaction pathways to the hydrolysis reaction system, and fitting kinetic parameters to the experimental data. The time scale for the degradation indicates that short reaction times less than 30 min with high temperatures (300–350 °C) will maximize the yield of free fatty acids before degradation occurs.

*Publish or present your work recently and want to let others know? Contact the Postdoctoral Program Office to feature your publications on the Postdoctoral Blog or in the Postdoc Journal Newsletter.

From the Winter 2013/2014 Edition of the Postdoctoral Journal.

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