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Articles 1 - 13 of 13
Full-Text Articles in Physical Sciences and Mathematics
A Novel Bath Lily-Like Graphene Sheet-Wrapped Nano-Si Composite As A High Performance Anode Material For Li-Ion Batteries, Jun Chen, Jun Yang, Zi-Feng Ma, Pengfei Gao, Yu-Shi He, Xiao Zhen Liao, Xiaowei Yang
A Novel Bath Lily-Like Graphene Sheet-Wrapped Nano-Si Composite As A High Performance Anode Material For Li-Ion Batteries, Jun Chen, Jun Yang, Zi-Feng Ma, Pengfei Gao, Yu-Shi He, Xiao Zhen Liao, Xiaowei Yang
Faculty of Science - Papers (Archive)
"A novel bath lily-like graphene sheet-wrapped nano-Si composite synthesized via a simple spray drying process exhibits a high reversible capacity of 1525 mAh g(-1) and superior cycling stability, which could be attributed to a synergistic effect between highly conductive graphene sheets and active nanoparticles in the open nano/micro-structure."
Photoelectron-Photofragment Coincidence Spectroscopy In A Cryogenically Cooled Linear Electrostatic Ion Beam Trap, Christopher J. Johnson, Ben B. Shen, Berwyck L. J Poad, Robert E. Continetti
Photoelectron-Photofragment Coincidence Spectroscopy In A Cryogenically Cooled Linear Electrostatic Ion Beam Trap, Christopher J. Johnson, Ben B. Shen, Berwyck L. J Poad, Robert E. Continetti
Faculty of Science - Papers (Archive)
A cryogenically cooled linear electrostatic ion beam trap for use in photoelectron-photofragment coincidence (PPC) spectroscopy is described. Using this instrument, anions created in cold, low-dutycycle sources can be stored for many seconds in a ∼20 K environment to cool radiatively, removing energetic uncertainties due to vibrationally excited precursor anions. This apparatus maintains a well-collimated beam necessary for high-resolution fragment imaging and the high experimental duty cycle needed for coincidence experiments. Ion oscillation is bunched and phase-locked to a modelocked laser, ensuring temporal overlap between ion bunches and laser pulses and that ions are intersected by the laser only when travelling …
Ion Selectivity In Channels And Transporters, Benoit Roux, Simon Berneche, Berhard Egwolf, Bogdan Lev, Sergei Y. Noskov, Christopher N. Rowley, Haibo Yu
Ion Selectivity In Channels And Transporters, Benoit Roux, Simon Berneche, Berhard Egwolf, Bogdan Lev, Sergei Y. Noskov, Christopher N. Rowley, Haibo Yu
Faculty of Science - Papers (Archive)
No abstract provided.
Average Mass Scan Of The Total Ion Chromatogram Versus Percentage Chemical Composition In Multivariate Statistical Comparison Of Complex Volatile Mixtures, Niko Radulovic, Polina Blagojevic, Danielle Skropeta
Average Mass Scan Of The Total Ion Chromatogram Versus Percentage Chemical Composition In Multivariate Statistical Comparison Of Complex Volatile Mixtures, Niko Radulovic, Polina Blagojevic, Danielle Skropeta
Faculty of Science - Papers (Archive)
The analysis of complex volatile mixtures by gas chromatography-mass spectrometry (GC-MS) is a time-consuming process. It involves separation and identification of the components based on their retention times and fragmentation patterns, followed by determination of their relative percentages from integration of their peak areas. Herein we show that multivariate statistical analysis of the relative abundances of the m/z values obtained from the average mass scans (AMS) of the complex mixture is a faster and potentially more reliable method of assessing these mixtures. To achieve this, 15 model complex mixtures, were prepared comprising varying amounts of 10 different constituents. The AMS …
A Combined Experimental And Theoretical Study Of Ion Solvation In Liquid N-Methylacetamide, Haibo Yu, Christopher L. Mazzanti, Troy W. Whitfield, Roger E. Koeppe Ii, Olaf S. Andersen, Benoit Roux
A Combined Experimental And Theoretical Study Of Ion Solvation In Liquid N-Methylacetamide, Haibo Yu, Christopher L. Mazzanti, Troy W. Whitfield, Roger E. Koeppe Ii, Olaf S. Andersen, Benoit Roux
Faculty of Science - Papers (Archive)
Most current biomolecular simulations are based on potential energy functions that treat the electrostatic energy as a sum of pairwise Coulombic interactions between effective fixed atomic charges. This approximation, in which many-body induced polarization effects are included in an average way, is expected to be satisfactory for a wide range of systems, but less accurate for processes involving the transfer and partition of ions among heterogeneous environments. The limitations of these potential energy functions are perhaps most obvious in studies of ion permeation through membrane channels. In many cases, the pore is so narrow that the permeating ion must shed …
Assessing The Accuracy Of Approximate Treatments Of Ion Hydration Based On Primitive Quasichemical Theory, Benoit Roux, Haibo Yu
Assessing The Accuracy Of Approximate Treatments Of Ion Hydration Based On Primitive Quasichemical Theory, Benoit Roux, Haibo Yu
Faculty of Science - Papers (Archive)
Quasichemical theory (QCT) provides a framework that can be used to partition the influence of the solvent surrounding an ion into near and distant contributions. Within QCT, the solvation properties of the ion are expressed as a sum of configurational integrals comprising only the ion and a small number of solvent molecules. QCT adopts a particularly simple form if it is assumed that the clusters undergo only small thermal fluctuations around a well-defined energy minimum and are affected exclusively in a mean-field sense by the surrounding bulk solvent. The fluctuations can then be integrated out via a simple vibrational analysis, …
Ion-Molecule Reactions Of O,S-Dimethyl Methylphosphonothioate: Evidence For Intramolecular Sulfur Oxidation During Vx Perhydrolysis, Jilliarne Williams, Martin Paine, Stephen J. Blanksby, Michael L. Rogers, Andrew M. Mcanoy
Ion-Molecule Reactions Of O,S-Dimethyl Methylphosphonothioate: Evidence For Intramolecular Sulfur Oxidation During Vx Perhydrolysis, Jilliarne Williams, Martin Paine, Stephen J. Blanksby, Michael L. Rogers, Andrew M. Mcanoy
Faculty of Science - Papers (Archive)
The alkaline perhydrolysis of the nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) was investigated by studying the ion-molecule reactions of HOO- with O,S-dimethyl methylphosphonothioate in a modified linear ion-trap mass spectrometer. In addition to simple proton transfer, two other abundant product ions are observed at m/z 125 and 109 corresponding to the S-methyl methylphosphonothioate and methyl methylphosphonate anions, respectively. The structure of these product ions is demonstrated by a combination of collision-induced dissociation and isotope-labeling experiments that also provide evidence for their formation by nucleophilic reaction pathways, namely, (i) S(N)2 at carbon to yield the S-methyl methylphosphonothioate anion and (ii) nucleophilic …
Ion-Molecule Reactions Reveal Facile Radical Migration In Peptides, Stephen J. Blanksby, Benjamin N. Moore, Ryan R. Julian
Ion-Molecule Reactions Reveal Facile Radical Migration In Peptides, Stephen J. Blanksby, Benjamin N. Moore, Ryan R. Julian
Faculty of Science - Papers (Archive)
Ion-molecule reactions between molecular oxygen and peptide radicals in the gas phase demonstrate that radical migration occurs easily within large biomolecules without addition of collisional activation energy.
On The Utilization Of Energy Minimization To The Study Of Ion Selectivity, Haibo Yu, Benoit Roux
On The Utilization Of Energy Minimization To The Study Of Ion Selectivity, Haibo Yu, Benoit Roux
Faculty of Science - Papers (Archive)
The major pitfalls in studying ion selectivity in binding site models using energy minimization based methods are examined and discussed. It is shown that the properties derived from energy minimization are strongly configuration-dependent and that the results should be interpreted with caution. It is concluded that computational studies of ion selectivity must include thermal fluctuations and entropic effects.
Malonate-Bound Structure Of The Glycerophosphodiesterase From Enterobacter Aerogenes (Gpdq) And Characterization Of The Native Fe2+ Metal-Ion Preference, Colin J. Jackson, Kieran S. Hadler, Paul D. Carr, Aaron J. Oakley, Sylvia Yip, Gerhard Schenk, David L. Ollis
Malonate-Bound Structure Of The Glycerophosphodiesterase From Enterobacter Aerogenes (Gpdq) And Characterization Of The Native Fe2+ Metal-Ion Preference, Colin J. Jackson, Kieran S. Hadler, Paul D. Carr, Aaron J. Oakley, Sylvia Yip, Gerhard Schenk, David L. Ollis
Faculty of Science - Papers (Archive)
The structure of a malonate-bound form of the glycerophosphodiesterase from Enterobacter aerogenes, GpdQ, has been refined at a resolution of 2.2 A ̊ to a final R factor of 17.1%. The structure was originally solved to 2.9 A ̊ resolution using SAD phases from Zn2+ metal ions introduced into the active site of the apoenzyme [Jackson et al. (2007), J. Mol. Biol. 367, 1047–1062]. However, the 2.9 A ̊ resolution was insufficient to discern significant details of the architecture of the binuclear metal centre that constitutes the active site. Furthermore, kinetic analysis revealed that the enzyme lost a significant amount …
Reactions Of The Hydroperoxide Anion With Dimethyl Methylphosphonate In An Ion Trap Mass Spectrometer: Evidence For A Gas Phase A-Effect, Andrew M Mcanoy, Martin Paine, Stephen J. Blanksby
Reactions Of The Hydroperoxide Anion With Dimethyl Methylphosphonate In An Ion Trap Mass Spectrometer: Evidence For A Gas Phase A-Effect, Andrew M Mcanoy, Martin Paine, Stephen J. Blanksby
Faculty of Science - Papers (Archive)
The gas phase degradation reactions of the chemical warfare agent (CWA) simulant, dimethyl methylphosphonate (DMMP), with the hydroperoxide anion (HOO–) were investigated using a modified quadrupole ion trap mass spectrometer. The HOO– anion reacts readily with neutral DMMP forming two significant product ions at m/z 109 and m/z 123. The major reaction pathways correspond to (i) the nucleophilic substitution at carbon to form [CH3P(O)(OCH3)O]– (m/z 109) in a highly exothermic process and (ii) exothermic proton transfer. The branching ratios of the two reaction pathways, 89% and 11% respectively, indicate that the …
Effect Of Protein Stabilization On Charge State Distribution In Positive- And Negative Ion Electrospray Ionization Mass Spectra, Stephen J. Watt, Margaret Sheil, Jennifer L. Beck, Pavel Prosselkov, Gottfried Otting, Nicholas E. Dixon
Effect Of Protein Stabilization On Charge State Distribution In Positive- And Negative Ion Electrospray Ionization Mass Spectra, Stephen J. Watt, Margaret Sheil, Jennifer L. Beck, Pavel Prosselkov, Gottfried Otting, Nicholas E. Dixon
Faculty of Science - Papers (Archive)
Changes in protein conformation are thought to alter charge state distributions observed in electrospray ionization mass spectra (ESI-MS) of proteins. In most cases, this has been demonstrated by unfolding proteins through acidification of the solution. This methodology changes the properties of the solvent so that changes in the ESI-MS charge envelopes from conformational changes are difficult to separate from the effects of changing solvent on the ionization process. A novel strategy is presented enabling comparison of ESI mass spectra of a folded and partially unfolded protein of the same amino acid sequence subjected to the same experimental protocols and conditions. …
Direct Imaging Of Lipid-Ion Network Formation Under Physiological Conditions By Frequency Modulation Atomic Force Microscopy, Michael J. Higgins, Suzi P. Jarvis, Takeshi Fukuma
Direct Imaging Of Lipid-Ion Network Formation Under Physiological Conditions By Frequency Modulation Atomic Force Microscopy, Michael J. Higgins, Suzi P. Jarvis, Takeshi Fukuma
Faculty of Science - Papers (Archive)
Various metal cations in physiological solutions interact with lipid headgroups in biological membranes, having an impact on their structure and stability, yet little is known about the molecular-scale dynamics of the lipid-ion interactions. Here we directly investigate the extensive lipid-ion interaction networks and their transient formation between headgroups in a dipalmitoylphosphatidylcholine bilayer under physiological conditions. The spatial distribution of ion occupancy is imaged in real space by frequency modulation atomic force microscopy with sub-Angstrom resolution.