scholarly journals Water Structure, Dynamics and Ion Adsorption at the Aqueous {010} Brushite Surface

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 334 ◽  
Author(s):  
Natalya Garcia ◽  
Paolo Raiteri ◽  
Elias Vlieg ◽  
Julian Gale
Keyword(s):  
First Principles ◽  
Water Structure ◽  
Dynamics Simulation ◽  
Free Energies ◽  
X Ray Diffraction ◽  
Bone Implant ◽  
X Ray ◽  
Solution Interface ◽  
Aqueous Environments ◽  
Implant Coating

Understanding the growth processes of calcium phosphate minerals in aqueous environments has implications for both health and geology. Brushite, in particular, is a component of certain kidney stones and is used as a bone implant coating. Understanding the water–brushite interface at the molecular scale will help inform the control of its growth. Liquid-ordering and the rates of water exchange at the brushite–solution interface have been examined through the use of molecular dynamics simulation and the results compared to surface X-ray diffraction data. This comparison highlights discrepancies between the two sets of results, regardless of whether force field or first principles methods are used in the simulations, or the extent of water coverage. In order to probe other possible reasons for this difference, the free energies for the adsorption of several ions on brushite were computed. Given the exothermic nature found in some cases, it is possible that the discrepancy in the surface electron density may be caused by adsorption of excess ions.

scholarly journals The crystal structures and mechanical properties of the uranyl carbonate minerals roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite

2020 ◽  
Vol 7 (21) ◽  
pp. 4197-4221 ◽  
Author(s):  
Francisco Colmenero ◽  
Jakub Plášil ◽  
Jiří Sejkora
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Diffraction Pattern ◽  
Crystal Structures ◽  
First Principles ◽  
X Ray Diffraction ◽  
Carbonate Minerals ◽  
X Ray ◽  
Uranyl Carbonate

The structure, hydrogen bonding, X-ray diffraction pattern and mechanical properties of six important uranyl carbonate minerals, roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite, are determined using first principles methods.

scholarly journals Adsorption of malic acid at the hydroxyapatite/aqueous NaCl solution interface

2021 ◽  
Author(s):  
Władysław Janusz ◽  
Ewa Skwarek
Keyword(s):  
Zeta Potential ◽  
Malic Acid ◽  
Particle Sizes ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Radioisotope Method ◽  
X Ray ◽  
Solution Interface ◽  
Adsorption Desorption ◽  
Kinetics Of

AbstractThe aim of the study was the basic incidence on the phenomenon of adsorption that occurs at the hydroxyapatite/malic acid interface, leading to a change in the surface properties of hydroxyapatite, Analytical methods used in the research: X-ray diffraction (XRD) as well as by the, adsorption–desorption of nitrogen (ASAP), potentiometric titration. The specific adsorption of malic acid ions at the hydroxyapatite interface was investigated by means of the radioisotope method. The zeta potential of hydroxyapatite dispersions was determined by electrophoresis with Zetasizer Nano ZS90 by Malvern. The particle sizes of hydroxyapatite samples were analyzed using Masteriszer 2000 Malvern. Studies on the kinetics of malic acid on hydroxyapatite from a solution with an initial concentration of 1 mmol/dm3 have shown that the adsorption process is initially fast, followed by a slow adsorption step. An increase in the pH of the solution causes a decrease in the malic acid adsorption as a result of competition with hydroxyl ions. The presence of adsorbed malic acid was confirmed by the FTIR measurements. The effect of malic acid adsorption on the zeta potential and particle size distribution of hydroxyapatite in the NaCl solution was investigated.

scholarly journals Crystal Structures of Al2Cu Revisited: Understanding Existing Phases and Exploring Other Potential Phases

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1037 ◽  
Author(s):  
Sai Wang ◽  
Changzeng Fan
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Single Crystal ◽  
First Principles ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Relationships ◽  
Al2cu Phase ◽  
High Pressure Sintering

When processing single crystal X-ray diffraction datasets for twins of Al2Cu sample synthesized by the high-pressure sintering (HPS) method, we have clarified why the crystal structure of Al2Cu was incorrectly solved about a century ago. The structural relationships between all existing Al2Cu phases, including the Owen-, θ-, θ’-, and Ω-Al2Cu phases, were investigated and established based on a proposed pseudo Al2Cu phase. Two potential phases have been built up by adjusting the packing sequences of A/B layers of Al atoms that were inherent in all existing Al2Cu phases. The mechanical, thermal, and dynamical stability of two such novel phases and their electronic properties were investigated by first-principles calculations.

scholarly journals New Insights on the Reversible Lithiation Mechanism of TiO2(B) by Operando X-ray Absorption Spectroscopy and X-ray Diffraction Assisted by First-Principles Calculations

2014 ◽  
Vol 118 (47) ◽  
pp. 27210-27218 ◽  
Author(s):  
Marcus Fehse ◽  
Mouna Ben Yahia ◽  
Laure Monconduit ◽  
Frédéric Lemoigno ◽  
Marie-Liesse Doublet ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
First Principles ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption
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