Anomalous thermal contraction of the first coordination shell in metallic alloy liquids

2014 ◽  
Vol 140 (4) ◽  
pp. 044505 ◽  
Author(s):  
A. K. Gangopadhyay ◽  
M. E. Blodgett ◽  
M. L. Johnson ◽  
J. McKnight ◽  
V. Wessels ◽  
...  
Keyword(s):  
Coordination Shell ◽  
Metallic Alloy ◽  
Thermal Contraction ◽  
Alloy Liquids

scholarly journals Ideality of liquid structure: A case study for metallic alloy liquids

2020 ◽  
Vol 101 (3) ◽  
Author(s):  
Chae Woo Ryu ◽  
Wojciech Dmowski ◽  
Takeshi Egami
Keyword(s):  
Liquid Structure ◽  
Metallic Alloy ◽  
Alloy Liquids

Mechanisms of ATP to cAMP Conversion Catalyzed by the Mammalian Adenylyl Cyclase: A Role of Magnesium Coordination Shells and Proton Wires

2019 ◽  
Author(s):  
Bella Grigorenko ◽  
Igor Polyakov ◽  
Alexander Nemukhin
Keyword(s):  
Adenylyl Cyclase ◽  
Bond Cleavage ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Md Simulations ◽  
Coordination Shell ◽  
Energy Profile ◽  
One Step ◽  
Type V

<p>We report a mechanism of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) conversion by the mammalian type V adenylyl cyclase revealed in molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations. We characterize a set of computationally derived enzyme-substrate (ES) structures showing an important role of coordination shells of magnesium ions in the solvent accessible active site. Several stable six-fold coordination shells of Mg<sub>A</sub><sup>2+ </sup>are observed in MD simulations of ES complexes. In the lowest energy ES conformation, the coordination shell of Mg<sub>A</sub><sup>2+ </sup>does not include the O<sub>δ1</sub> atom of the conserved Asp440 residue. Starting from this conformation, a one-step reaction mechanism is characterized which includes proton transfer from the ribose O<sup>3'</sup>H<sup>3' </sup>group in ATP to Asp440 via a shuttling water molecule and P<sup>A</sup>-O<sup>3A</sup> bond cleavage and O<sup>3'</sup>-P<sup>A</sup> bond formation. The energy profile of this route is consistent with the observed reaction kinetics. In a higher energy ES conformation, Mg<sub>A</sub><sup>2+</sup> is bound to the O<sub>δ1</sub>(Asp440) atom as suggested in the relevant crystal structure of the protein with a substrate analog. The computed energy profile initiated by this ES is characterized by higher energy expenses to complete the reaction. Consistently with experimental data, we show that the Asp440Ala mutant of the enzyme should exhibit a reduced but retained activity. All considered reaction pathways include proton wires from the O<sup>3'</sup>H<sup>3' </sup>group via shuttling water molecules. </p>

scholarly journals Investigation of the Structural Heterogeneity and Corrosion Performance of the Annealed Fe-Based Metallic Glasses

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 929
Author(s):  
Dandan Liang ◽  
Jo-Chi Tseng ◽  
Xiaodi Liu ◽  
Yuanfei Cai ◽  
Gang Xu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Passive Film ◽  
Metallic Glasses ◽  
Function Analysis ◽  
Supercooled Liquid ◽  
Structural Heterogeneity ◽  
Coordination Shell ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Corrosion Performance

This study investigated the structural heterogeneity, mechanical property, electrochemical behavior, and passive film characteristics of Fe–Cr–Mo–W–C–B–Y metallic glasses (MGs), which were modified through annealing at different temperatures. Results showed that annealing MGs below the glass transition temperature enhanced corrosion resistance in HCl solution owing to a highly protective passive film formed, originating from the decreased free volume and the shrinkage of the first coordination shell, which was found by pair distribution function analysis. In contrast, the enlarged first coordination shell and nanoscale crystal-like clusters were identified for MGs annealed in the supercooled liquid region, which led to a destabilized passive film and thereby deteriorated corrosion resistance. This finding reveals the crucial role of structural heterogeneity in tuning the corrosion performance of MGs.

scholarly journals Effects of dopants on the glass forming ability in Al-based metallic alloy

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
Yang Sun ◽  
Feng Zhang ◽  
Lin Yang ◽  
Huajing Song ◽  
Mikhail I. Mendelev ◽  
...  
Keyword(s):  
Glass Forming Ability ◽  
Metallic Alloy ◽  
Glass Forming

scholarly journals Bulk and Confined Benzene-Cyclohexane Mixtures Studied by an Integrated Total Neutron Scattering and NMR Method

2021 ◽  
Author(s):  
Terri-Louise Hughes ◽  
Marta Falkowska ◽  
Markus Leutzsch ◽  
Andrew J. Sederman ◽  
Mick D. Mantle ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Structure Refinement ◽  
Computational Simulation ◽  
Liquid Mixtures ◽  
Coordination Shell ◽  
Bulk Liquid ◽  
Total Neutron ◽  
Time Resolved ◽  
Sample Composition ◽  
Potential Structure

AbstractHerein mixtures of cyclohexane and benzene have been investigated in both the bulk liquid phase and when confined in MCM-41 mesopores. The bulk mixtures have been studied using total neutron scattering (TNS), and the confined mixtures have been studied by a new flow-utilising, integrated TNS and NMR system (Flow NeuNMR), all systems have been analysed using empirical potential structure refinement (EPSR). The Flow NeuNMR setup provided precise time-resolved chemical sample composition through NMR, overcoming the difficulties of ensuring compositional consistency for computational simulation of data ordinarily found in TNS experiments of changing chemical composition—such as chemical reactions. Unique to the liquid mixtures, perpendicularly oriented benzene molecules have been found at short distances from the cyclohexane rings in the regions perpendicular to the carbon–carbon bonds. Upon confinement of the hydrocarbon mixtures, a stronger parallel orientational preference of unlike molecular dimers, at short distances, has been found. At longer first coordination shell distances, the like benzene molecular spatial organisation within the mixture has also found to be altered upon confinement.

Magnetic and transport properties of the giant-unit-cell Al3.26Mg2 complex metallic alloy

2007 ◽  
Vol 15 (10) ◽  
pp. 1367-1376 ◽  
Author(s):  
J. Dolinšek ◽  
T. Apih ◽  
P. Jeglič ◽  
I. Smiljanić ◽  
A. Bilušić ◽  
...  
Keyword(s):  
Transport Properties ◽  
Unit Cell ◽  
Metallic Alloy

Thermomechanical properties of iron and iron-carbon alloys: density and thermal contraction

1991 ◽  
Vol 62 (1) ◽  
pp. 24-33 ◽  
Author(s):  
Angela Jablonka ◽  
Klaus Harste ◽  
Klaus Schwerdtfeger
Keyword(s):  
Thermomechanical Properties ◽  
Thermal Contraction

Röntgenbeugungsuntersuchung an geschmolzenem Selen und Tellur sowie an Legierungen des Systems Selen—Tellur/ X-ray Diffraction Study of Molten Selenium, and Tellurium and of Molten Selenium — Tellurium-Alloys

1975 ◽  
Vol 30 (12) ◽  
pp. 1633-1639 ◽  
Author(s):  
W. Hoyer ◽  
E. Thomas ◽  
M. Wobst
Keyword(s):  
Chain Length ◽  
Short Range ◽  
Short Range Order ◽  
Coordination Shell ◽  
Range Order ◽  
Average Chain Length ◽  
X Ray Diffraction ◽  
Coordination Numbers ◽  
Nearest Neighbours ◽  
Increasing Temperature

Abstract At temperatures just above the melting point molten Selenium seems to be a mixture of long chains and eight-membered rings. With increasing temperature the number of rings and the average chain length decrease. At 460 °C the average chain length lies in the range of 10 atoms.In a slightly supercooled Tellurium-melt the number of first neighbours is two. The atoms are arranged in chains. Selenium rich Se-Te-alloy-melts are built up of mixed chains. It seems to be possible, that a smaller part of atoms forms Se6Te2 rings. At Tellurium concentrations higher than approximately 50 at.-% the chainlike structure with two next nearest neighbours changes to a disturbed Arsen-like short range order. The number of electrons in the first coordination shell, the short range order parameter introduced by Cowley and the partial coordination numbers show that Se-Te-alloys are of the "solution system" type, but in the whole concentration range for each atom there is a tendency to have "strange coordination".

Electrochemical reactivity, surface composition and corrosion mechanisms of the complex metallic alloy Al3Mg2

2010 ◽  
Vol 52 (2) ◽  
pp. 562-578 ◽  
Author(s):  
Ming Liu ◽  
Patrik Schmutz ◽  
Sandrine Zanna ◽  
Antoine Seyeux ◽  
Helene Ardelean ◽  
...  
Keyword(s):  
Surface Composition ◽  
Metallic Alloy ◽  
Electrochemical Reactivity ◽  
Corrosion Mechanisms
Sign in / Sign up

Export Citation Format

Share Document