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Full-Text Articles in Physical Sciences and Mathematics

Testing The Robustness Of Solution Force Fields For Md Simulations On Gaseous Protein Ions., Justin H Lee, Katja Pollert, Lars Konermann Aug 2019

Testing The Robustness Of Solution Force Fields For Md Simulations On Gaseous Protein Ions., Justin H Lee, Katja Pollert, Lars Konermann

Chemistry Publications

It is believed that electrosprayed proteins and protein complexes can retain solution-like conformations in the gas phase. However, the lack of high-resolution structure determination methods for gaseous protein ions implies that their properties remain poorly understood. Many practitioners tackle this difficulty by complementing mass spectrometry-based experiments with molecular dynamics (MD) simulations. It is a potential problem that the standard MD force fields used for this purpose (such as OPLS-AA/L and CHARMM) were optimized for solution conditions. The question whether these force fields produce meaningful gas-phase data has received surprisingly little attention. Standard force fields are overpolarized to account for an …


Monitoring Tropospheric Gases With Small Unmanned Aerial Systems (Suas) During The Second Cloudmap Flight Campaign, Travis J. Schuyler, Sean C. C. Bailey, Marcelo I. Guzman Aug 2019

Monitoring Tropospheric Gases With Small Unmanned Aerial Systems (Suas) During The Second Cloudmap Flight Campaign, Travis J. Schuyler, Sean C. C. Bailey, Marcelo I. Guzman

Chemistry Faculty Publications

Small unmanned aerial systems (sUAS) are a promising technology for atmospheric monitoring of trace atmospheric gases. While sUAS can be navigated to provide information with higher spatiotemporal resolution than tethered balloons, they can also bridge the gap between the regions of the atmospheric boundary layer (ABL) sampled by ground stations and manned aircraft. Additionally, sUAS can be effectively employed in the petroleum industry, e.g., to constrain leaking regions of hydrocarbons from long gasoducts. Herein, sUAS are demonstrated to be a valuable technology for studying the concentration of important trace tropospheric gases in the ABL. The successful detection and quantification of …


Protein Ions Generated By Native Electrospray Ionization: Comparison Of Gas Phase, Solution, And Crystal Structures., Maryam Bakhtiari, Lars Konermann Feb 2019

Protein Ions Generated By Native Electrospray Ionization: Comparison Of Gas Phase, Solution, And Crystal Structures., Maryam Bakhtiari, Lars Konermann

Chemistry Publications

Experiments and molecular dynamics (MD) simulations in the literature indicate that gaseous proteins generated by electrospray ionization (ESI) can retain native-like structures. However, the exact properties of these ions remain to be explored. Focusing on ubiquitin and lysozyme, we examined several pertinent questions. (1) We applied solvent MD runs to test whether the X-ray structures of both proteins are affected by crystal packing. Main and side-chain orientations were retained in solution, providing a justification for the hitherto unscrutinized approach of relying on crystal data for "solution" versus gas-phase comparisons. (2) Most earlier gas-phase protein MD investigations employed short (ns) simulation …


Recent Trends In Stratospheric Chlorine From Very Short‐Lived Substances, Ryan Hossaini, Elliot Atlas, Sandip S. Dhomse, Martyn P. Chipperfield, Peter F. Bernath, Anton M. Fernando, Jens Mühle, Amber A. Leeson, Stephen A. Montzka, Wuhu Feng Jan 2019

Recent Trends In Stratospheric Chlorine From Very Short‐Lived Substances, Ryan Hossaini, Elliot Atlas, Sandip S. Dhomse, Martyn P. Chipperfield, Peter F. Bernath, Anton M. Fernando, Jens Mühle, Amber A. Leeson, Stephen A. Montzka, Wuhu Feng

Chemistry & Biochemistry Faculty Publications

Very short‐lived substances (VSLS), including dichloromethane (CH2Cl2), chloroform (CHCl3), perchloroethylene (C2Cl4), and 1,2‐dichloroethane (C2H4Cl2), are a stratospheric chlorine source and therefore contribute to ozone depletion. We quantify stratospheric chlorine trends from these VSLS (VSLCltot) using a chemical transport model and atmospheric measurements, including novel high‐altitude aircraft data from the NASA VIRGAS (2015) and POSIDON (2016) missions. We estimate VSLCltot increased from 69 (±14) parts per trillion (ppt) Cl in 2000 to 111 (±22) ppt Cl in 2017, with >80% delivered to …