A5068616446- Iron oxide chemistry and applications
- Radioactive element chemistry and processing
- Glass properties and applications
- Calcium Carbonate Crystallization and Inhibition
- Nuclear materials and radiation effects
- Spectroscopy and Quantum Chemical Studies
- Seismic Waves and Analysis
- Methane Hydrates and Related Phenomena
- Radiation Detection and Scintillator Technologies
- CO2 Sequestration and Geologic Interactions
- Clay minerals and soil interactions
- Minerals Flotation and Separation Techniques
- Earthquake Detection and Analysis
- Groundwater flow and contamination studies
- Electrochemical Analysis and Applications
- High-pressure geophysics and materials
- Electrostatics and Colloid Interactions
- Luminescence Properties of Advanced Materials
- Advancements in Battery Materials
- Atomic and Subatomic Physics Research
- Hydrocarbon exploration and reservoir analysis
- Building materials and conservation
- Recycling and utilization of industrial and municipal waste in materials production
- Concrete and Cement Materials Research
- Nuclear Physics and Applications
Pacific Northwest National Laboratory
2016-2025
Physical Sciences (United States)
2017-2024
Richland College
2019-2020
Weatherford College
2019
Environmental Molecular Sciences Laboratory
2005-2017
Battelle
2007-2016
Sandia National Laboratories
2015
Washington University in St. Louis
2015
Georgia Institute of Technology
2015
University of Minnesota
2015
As key components of the electron transfer (ET) pathways used for dissimilatory reduction solid iron [Fe(III)] (hydr)oxides, outer membrane multihaem c-type cytochromes MtrC and OmcA Shewanella oneidensis MR-1 OmcE OmcS Geobacter sulfurreducens mediate ET reactions extracellularly. Both are at least partially exposed to extracellular side their translocation across is mediated by bacterial type II secretion system. Purified can bind Fe(III) oxides, such as haematite (α-Fe2 O3 ), directly...
Abstract Fracture pattern development has been a challenging area of research in the Earth sciences for more than 100 years. Much learned about spatial and temporal complexity inherent to these systems, but severe challenges remain. Future advances will require new approaches. Chemical processes play larger role opening‐mode fracture hitherto appreciated. This review examines relationships between mechanical geochemical that influence patterns recorded natural settings. For fractures formed...
We calculated the free energy profiles of water and three metal ions (magnesium, calcium, strontium) adsorbing on [1014] calcite surface in aqueous solution. The approach uses molecular dynamics with parametrized equations to describe interatomic forces. potential model is able reproduce interactions between regardless whether they are at mineral or bulk water. simulations predict that adsorption relatively small compared enthalpy previous papers. This suggests a large change entropy...
New insights into the understanding of calcite–water interface structure are obtained through direct comparisons multiple classical molecular dynamics (MD) simulations with high-resolution specular X-ray reflectivity (XR) data. This set comparisons, four different state-of-the-art force fields (including two nonpolarizable, one polarizable, and reactive field), reveal new absolute accuracy simulated structures uniqueness XR-derived structural results. These simulations, though qualitatively...
Molecular dynamics simulations were carried out to investigate the effects of confinement and presence mineral surface on diffusion water electrolyte ions in nanosized fractures. Feldspar was used as a representative because recent studies found that it is an important hosts contaminants within its intragrain fractures at U.S. Department Energy Hanford site. Several properties mineral−water interface varied, such fracture width, ionic strength contacting solution, charge, provide...
Understanding the dissolution of silicate glasses and minerals from atomic to macroscopic levels is a challenge with major implications in geoscience industry. One main uncertainties limiting development predictive models lies formation an amorphous surface layer--called gel--that can some circumstances control reactivity buried interface. Here, we report experimental simulation results deciphering mechanisms by which gel becomes passivating. The study conducted on six-oxide borosilicate...
The aluminum oxyhydroxide boehmite is an important crystalline phase in nature and industry. We report development of a flexible additive-free hydrothermal synthesis method to prepare high quality nanoplates with sizes ranging from under 20 nm 5 μm via using hydrated alumina gels hydroxide amorphous powders as precursors. size morphology the was systematically varied between hexagonal rhombic by adjusting precursor concentrations, pH, temperature, due face-specific effects. transformation...
Crystallization by particle attachment is impacting our understanding of natural mineralization processes and holds promise for novel materials design. When particles assemble in crystallographic alignment, expulsion the intervening solvent coalescence are enabled near-perfect co-alignment via interparticle forces that remain poorly quantified. Here we report measurement simulation these nanoscale aligning ZnO(0001)-ZnO(000[Formula: see text]) system aqueous solution. Dynamic force...
Boehmite (γ-AlOOH) and gibbsite (α-Al(OH)3) are important archetype (oxy)hydroxides of aluminum in nature that also play diverse roles across a plethora industrial applications. Developing the ability to understand predict properties characteristics these materials, on basis their natural growth or synthesis pathways, is an fundamental science enterprise with wide-ranging impacts. The present study describes bulk surface novel materials comprehensive detail, using collectively sophisticated...
Atomistic simulation methods have been used to model the interaction of water with {101̄4} calcite surface and energetics for removal carbonate groups in presence water. Electronic structure calculations show that associative adsorption is energetically favored mode on surface, strongly bound atom-based simulations reproduce adsorption. The use molecular dynamics techniques calcite−water interface found loses its hydrogen-bond network when adsorbing it causes an oscillation density vicinity...
Understanding lithium diffusion properties in electrode materials is important for designing rechargeable lithium-ion batteries with improved performance. In this work, the dynamics layered Li2TiO3 were characterized using a combination of 6,7Li nuclear magnetic resonance (NMR) over wide temperature range (150−500 K) and molecular (MD) simulations. The 7Li static NMR stimulated echo experiments show slow partial Li2TiO3. high-field (21.1 T) 6Li magic-angle spinning shows new tetrahedral site...
Molecular dynamics (MD) simulations of the interface between graphene and ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIM OTf) were carried out to gain molecular-level insights into performance graphene-based supercapacitors and, in particular, determine effects presence oxygen-containing defects at surface on their integral capacitance. The MD predict that increasing coverage hydroxyl groups negatively affects capacitance, whereas effect epoxy is much less...
Insights at the microscopic level of process radiocesium adsorption and interaction with clay mineral particles have improved substantially over past several years, triggered by pressing social issues such as management huge amounts waste soil accumulated after Fukushima Dai–ichi nuclear power plant accident. In particular, computer–based molecular modeling supported advanced hardware algorithms has proven to be a powerful approach. Its application can now generally encompass full complexity...
Adsorption at mineral surfaces is a critical factor controlling the mobility of uranium(VI) in aqueous environments. Therefore, molecular dynamics (MD) simulations were performed to investigate uranyl(VI) adsorption onto two neutral aluminosilicate surfaces, namely, orthoclase (001) surface and octahedral aluminum sheet kaolinite surface. Although uranyl preferentially adsorbs as bidentate inner-sphere complex on both free energy (−15 kcal mol–1) significantly more favorable than that (−3...
We present classical molecular simulations of the adsorption free energy profiles for aqueous Fe(II) ion approaching key low index crystal faces goethite at neutral surface charge conditions. Calculated show minima corresponding to stable outer- and inner-sphere adsorbed structures. analyzed energetics kinetics most possible interfacial electron transfer reactions, as well analyzing same subsurface migration pathways injected electrons through calculating Marcus surfaces. conclude that...
Abstract Nuclear waste glasses dissolve at the forward dissolution rate ( r f ) in very dilute aqueous solutions, which can isolate impact of glass composition from solution feedback and alteration product effects. While it has long been known that pH temperature T strongly , impacts have remained uncertain. In this work, data 19 nuclear were used with aim identifying effect on . The values modeled as: = k 0 10 –η exp(− E a / RT ), η R respectively, being intrinsic constant, coefficient,...
Mineral and glass dissolution is a scientific topic that has been deeply investigated but not understood completely; it continues to be of great interest in the geochemical materials science communities. If interfacial dissolution/reprecipitation mechanism seems applicable most silicate minerals, debate remains open concerning glass. Here, we studied two model glasses, ternary borosilicate (CJ1) same doped with 4.1 mol % Al2O3 (CJ2). The glasses were altered at 90 °C, pH 9, conditions far...
Although interfacial solution structure impacts environmental, biological, and technological phenomena, including colloidal stability, protein assembly, heterogeneous nucleation, water desalination, its molecular details remain poorly understood. Here, we visualize the three-dimensional (3D) hydration at boehmite(010)–water interface using fast force mapping (FFM). Using a self-consistent scheme to decouple long-range tip-sample interactions from short-range solvation forces, obtain with...
Solid–liquid interfaces are central to a range of interesting phenomena including colloidal aggregation, crystallization by particle attachment, catalysis, heterogeneous nucleation, water desalination, and biomolecular assembly. While three-dimensional atomic force microscopy (3D AFM) has emerged as technique for resolving interfacial solution structure at the molecular scale, key challenges data interpretation persist, most notably regarding influence probe on measured structure. Using...
Molecular dynamics simulations of three solid surfaces, namely, the (00.1) and (01.2) hematite surfaces (10.4) calcite surface, in contact with an aqueous solution have been performed structure water near interface investigated. We initially calculated hydration hydroxylation energies two using static calculations to determine adsorbed state on these before studying molecular dynamics. The show that, each case, density exhibits a damped oscillatory behaviour up distance at least 15 Å from...