scholarly journals Infrared vibrational nanocrystallography and nanoimaging

2016 ◽  
Vol 2 (10) ◽  
pp. e1601006 ◽  
Author(s):  
Eric A. Muller ◽  
Benjamin Pollard ◽  
Hans A. Bechtel ◽  
Peter van Blerkom ◽  
Markus B. Raschke
Keyword(s):  
Ion Mobility ◽  
Molecular Orientation ◽  
Hybrid Imaging ◽  
Defect Formation ◽  
Near Field ◽  
Molecular Solids ◽  
Optical Antenna ◽  
Molecular Bond ◽  
Low Symmetry ◽  
Insight Into

Molecular solids and polymers can form low-symmetry crystal structures that exhibit anisotropic electron and ion mobility in engineered devices or biological systems. The distribution of molecular orientation and disorder then controls the macroscopic material response, yet it is difficult to image with conventional techniques on the nanoscale. We demonstrated a new form of optical nanocrystallography that combines scattering-type scanning near-field optical microscopy with both optical antenna and tip-selective infrared vibrational spectroscopy. From the symmetry-selective probing of molecular bond orientation with nanometer spatial resolution, we determined crystalline phases and orientation in aggregates and films of the organic electronic material perylenetetracarboxylic dianhydride. Mapping disorder within and between individual nanoscale domains, the correlative hybrid imaging of nanoscale heterogeneity provides insight into defect formation and propagation during growth in functional molecular solids.

Very Metal-Poor Stars and the Early Universe

2017 ◽  
Vol 13 (S334) ◽  
pp. 3-10
Author(s):  
John E. Norris
Keyword(s):  
Near Field ◽  
Field Studies ◽  
Far Field ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Physical Conditions ◽  
The Galaxy ◽  
Formation And Evolution ◽  
The Universe ◽  
Insight Into

AbstractVery metal-poor stars ([Fe/H] < –2.0) inform our understanding of the formation and evolution of the Galaxy, and the physical conditions in the earliest star-forming environments of the Universe. They play an integral part in the paradigms of stellar populations, stellar archaeology, and near-field cosmology. We review the carbon-rich and carbon-normal sub-populations of the most iron-poor stars, providing insight into chemical enrichment at the earliest times in the Universe. We also discuss the role of very metal-poor stars in providing insight into the Galaxy’s halo, thick disk, and bulge, and the promise they hold for the future. A comparison between the abundances obtained for the nine most Fe-poor stars ([Fe/H] < –4.5) (all but one of which is C-rich) with abundances obtained from far-field cosmology suggests that the former are the most chemically primitive objects yet observed and probably older than the DLA- and sub-DLA systems for which data are currently available from far-field studies.

scholarly journals Entrained flow gasification. Part 3: Insight into the injector near-field by Large Eddy Simulation with detailed chemistry

Fuel ◽  
2018 ◽  
Vol 223 ◽  
pp. 164-178 ◽  
Author(s):  
Georg Eckel ◽  
Patrick Le Clercq ◽  
Trupti Kathrotia ◽  
Alexander Saenger ◽  
Sabine Fleck ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Near Field ◽  
Detailed Chemistry ◽  
Entrained Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Entrained Flow Gasification ◽  
Insight Into

scholarly journals Molecular assemblies of the catalytic domain of SOS with KRas and oncogenic mutants

2021 ◽  
Vol 118 (12) ◽  
pp. e2022403118
Author(s):  
Zahra Moghadamchargari ◽  
Mehdi Shirzadeh ◽  
Chang Liu ◽  
Samantha Schrecke ◽  
Charles Packianathan ◽  
...  
Keyword(s):  
Ion Mobility ◽  
Catalytic Domain ◽  
Therapeutic Interventions ◽  
Nucleotide Exchange ◽  
Molecular Assemblies ◽  
Oncogenic Ras ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Son Of Sevenless ◽  
Insight Into

Ras is regulated by a specific guanine nucleotide exchange factor Son of Sevenless (SOS), which facilitates the exchange of inactive, GDP-bound Ras with GTP. The catalytic activity of SOS is also allosterically modulated by an active Ras (Ras–GTP). However, it remains poorly understood how oncogenic Ras mutants interact with SOS and modulate its activity. Here, native ion mobility–mass spectrometry is employed to monitor the assembly of the catalytic domain of SOS (SOScat) with KRas and three cancer-associated mutants (G12C, G13D, and Q61H), leading to the discovery of different molecular assemblies and distinct conformers of SOScat engaging KRas. We also find KRasG13D exhibits high affinity for SOScat and is a potent allosteric modulator of its activity. A structure of the KRasG13D•SOScat complex was determined using cryogenic electron microscopy providing insight into the enhanced affinity of the mutant protein. In addition, we find that KRasG13D–GTP can allosterically increase the nucleotide exchange rate of KRas at the active site more than twofold compared to KRas–GTP. Furthermore, small-molecule Ras•SOS disruptors fail to dissociate KRasG13D•SOScat complexes, underscoring the need for more potent disruptors. Taken together, a better understanding of the interaction between oncogenic Ras mutants and SOS will provide avenues for improved therapeutic interventions.

Characterization of Perovskite-Like Substrates for Thin Film Superconductors using Synchrotron X-Ray Topography

1991 ◽  
Vol 35 (A) ◽  
pp. 255-261
Author(s):  
G.-D. Yao ◽  
S.Y. Hon ◽  
M. Dudley ◽  
Julia M. Phillips
Keyword(s):  
Defect Formation ◽  
Chemical Properties ◽  
Substrate Material ◽  
Formation Mechanisms ◽  
X Ray ◽  
Physical And Chemical ◽  
Insight Into ◽  
Selection Of ◽  
Potential Substrate

AbstractThe characterization of defect configurations in various perovskite-like substrate materials for high Tc superconductor epitaxial films has been conducted using white beam synchrotron X-ray topography. The substrates were found to contain crystal lattice defects such as twins, dislocations and grain boundaries. It is shown that characterization of substrates can potentially afford insight into factors controlling the properties of the high Tc superconductor tilms supported on them. This can help in the selection of optimum substrate material. Defect formation mechanisms in individual materials as well as their respective influences on the films are discussed. Comparisons between the physical and chemical properties of several potential substrate materials are presented.

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