Showing 26 results for Author: Vitalii Starchenko
Nov, 2023
Journal
The nucleation and growth of barium sulfate in nanoporous silica was investigated using in situ small-angle X-ray scattering and X-ray pair distribution function analysis, together with ex situ transmission and scanning transmission electron microscopy (TEM and STEM) imaging. We found that crystalline barite formation in micropores is likely preceded by a nonbulk barite ph…
Nov, 2023
Journal
Nucleation of barite (BaSO4) has broad implications in geological, environmental, and materials sciences. While impurity metals are common, our understanding of how they impact nucleation remains dim. Here, we used classical optical microscopy compared to fast X-ray nanotomography (XnT) to investigate heterogeneous nucleation of barite on silica in situ with Sr2+ as an imp…
Nov, 2023
Journal
A fundamental understanding of mineral precipitation kinetics relies largely on microscopic observations of the dynamics of mineral surfaces exposed to supersaturated solutions. Deconvolution of tightly bound transport, surface reaction, and crystal nucleation phenomena still remains one of the main challenges. Particularly, the influence of these processes on texture and…
Nov, 2023
Journal
Sparingly soluble sulfate minerals, particularly barite (BaSO4), present an ideal system to understand mineral–water interfacial reactions. The model system barite has been used to develop crystal nucleation, growth, recrystallization, and pore-scale reactive transport models, both for the end-member cases, and in the presence of impurities that form isostructural solid so…
Nov, 2023
Conference Paper
This work develops new techniques within Horovod, a generic communication library supporting data parallel training across deep learning frameworks. In particular, we improve the Horovod control plane by implementing a new coordination scheme that takes advantage of the characteristics of the typical data parallel training paradigm, namely the repeated execution of collect…
Nov, 2023
Journal
This paper explores the effect of permeable grain boundaries on carbonate rock dissolution in order to improve our understanding of grain detachment and migration during reactive flow. To do so we investigated the effects of grain size and enhanced reactivity along grain boundaries on global dissolution kinetics. Variations of permeability and porosity were calculated, and…
Nov, 2023
Journal
Experimental observations of the dissolution of calcium sulfate by flowing water have been used to investigate the assumptions underlying pore-scale models of reactive transport. Microfluidic experiments were designed to observe changes in size and shape as cylindrical disks (radius 10 mm) of gypsum dissolved for periods of up to 40 days. The dissolution flux over the whol…
Nov, 2023
Journal
This manuscript presents a benchmark problem for the simulation of single-phase flow, reactive transport, and solid geometry evolution at the pore scale. The problem is organized in three parts that focus on specific aspects: flow and reactive transport (part I), dissolution-driven geometry evolution in two dimensions (part II), and an experimental validation of three-dime…
Nov, 2023
Journal
We investigate the development of wormholes in laboratory‐scale fractures using three‐dimensional numerical simulations. Well‐controlled initial conditions, involving a small perturbation near the inlet of an otherwise flat fracture aperture field, were used to make a systematic study of the effects of flow rate and reaction rate on the aperture evolution. We find at least…
Nov, 2023
Journal
Understanding of fundamental processes and prediction of optimal parameters during the horizontal drilling and hydraulic fracturing process results in economically effective improvement of oil and natural gas extraction. Although, the modern analytical and computational models can capture fracture growth, there is a lack of experimental data on spontaneous imbibition and w…
Oct, 2023
Journal
It has been proposed to use magnesium oxide (MgO) to separate carbon dioxide directly from the atmosphere at the gigaton level. We show experimental results on MgO single crystals reacting with the atmosphere for longer (decades) and shorter (days to months) periods with the goal of gauging reaction rates. Here, we find a substantial slowdown of an initially fast reaction…
Apr, 2023
Journal
Understanding the behavior of defects in the complex oxides is key to controlling myriad ionic and electronic properties in these multifunctional materials. The observation of defect dynamics, however, requires a unique probe—one sensitive to the configuration of defects as well as its time evolution. Here, we present measurements of oxygen vacancy ordering in epitaxial th…