scholarly journals Biotite supports long-range diffusive transport in dissolution–precipitation creep in halite through small porosity fluctuations

Solid Earth ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 41-64
Author(s):  
Berit Schwichtenberg ◽  
Florian Fusseis ◽  
Ian B. Butler ◽  
Edward Andò
Keyword(s):  
Groundwater Resources ◽  
Theoretical Models ◽  
Transport Processes ◽  
Rock Properties ◽  
Homogeneous Distribution ◽  
Dynamic Evolution ◽  
Diffusive Transport ◽  
Pore Collapse ◽  
Length Scales ◽  
Porosity Reduction

Abstract. Phyllosilicates are generally regarded to have a reinforcing effect on chemical compaction by dissolution–precipitation creep (DPC) and thereby influence the evolution of hydraulic rock properties relevant to groundwater resources and geological repositories as well as fossil fuel reservoirs. We conducted oedometric compaction experiments on layered NaCl–biotite samples to test this assumption. In particular, we aim to analyse slow chemical compaction processes in the presence of biotite on the grain scale and determine the effects of chemical and mechanical feedbacks. We used time-resolved (4-D) microtomographic data to capture the dynamic evolution of the porosity in layered NaCl–NaCl/biotite samples over 1619 and 1932 h of compaction. Percolation analysis in combination with advanced digital volume correlation techniques showed that biotite grains influence the dynamic evolution of porosity in the sample by promoting a reduction of porosity in their vicinity. However, the lack of preferential strain localisation around phyllosilicates and a homogeneous distribution of axial shortening across the sample suggests that the porosity reduction is not achieved by pore collapse but by the precipitation of NaCl sourced from outside the NaCl–biotite layer. Our observations invite a renewed discussion of the effect of phyllosilicates on DPC, with a particular emphasis on the length scales of the processes involved. We propose that, in our experiments, the diffusive transport processes invoked in classical theoretical models of DPC are complemented by chemo-mechanical feedbacks that arise on longer length scales. These feedbacks drive NaCl diffusion from the marginal pure NaCl layers into the central NaCl–biotite mixture over distances of several hundred micrometres and several grain diameters. Such a mechanism was first postulated by Merino et al. (1983).

scholarly journals Biotite supports long-range diffusive transport in dissolution-precipitation creep in halite

2021 ◽  
Author(s):  
Berit Ina Schwichtenberg ◽  
Florian Fusseis ◽  
Ian B. Butler ◽  
Edward Andò
Keyword(s):  
Groundwater Resources ◽  
Theoretical Models ◽  
Transport Processes ◽  
Rock Properties ◽  
Homogeneous Distribution ◽  
Dynamic Evolution ◽  
Diffusive Transport ◽  
Pore Collapse ◽  
Length Scales ◽  
Porosity Reduction

Abstract. Phyllosilicates are generally regarded to have a reinforcing effect on chemical compaction by dissolution-precipitation creep (DPC) and thereby influence the evolution of hydraulic rock properties relevant to groundwater resources, geological repositories as well as fossil fuel reservoirs. We conducted oedometric compaction experiments on layered NaCl-biotite samples to test this assumption. In particular, we aim to analyse slow chemical compaction processes in the presence of biotite on the grain scale and determine the effects of chemical and mechanical feedbacks. We used time-resolved (4D) microtomographic data to capture the dynamic evolution of the transport properties in layered NaCl-NaCl/biotite samples over 1619 and1932 hours of compaction. Percolation analysis in combination with advanced digital volume correlation techniques showed that biotite grains influence the dynamic evolution of porosity in the sample by promoting a reduction of porosity in their vicinity. However, the lack of preferential strain localisation around phyllosilicates and a homogeneous distribution of axial shortening across the sample suggests that the porosity reduction is not achieved by pore collapse but by the precipitation of NaCl sourced from outside the NaCl/biotite layer. Our observations invite a renewed discussion of the effect of phyllosilicates on DPC, with a particular emphasis on the length scales of the processes involved. We propose that, in our experiments, the diffusive transport processes invoked in classical theoretical models of DPC are superseded by chemo-mechanical feedbacks that arise on longer length scales. These feedbacks drive NaCl diffusion from the marginal pure NaCl layers into the central NaCl-biotite mixture over distances of several hundredμm and several grain diameters. Such a mechanism was first postulated by Merino et al. (1983)

A New View of Convective-Diffusive Transport Processes in the Arterial Intima

1991 ◽  
Vol 113 (3) ◽  
pp. 314-329 ◽  
Author(s):  
F. Yuan ◽  
S. Chien ◽  
S. Weinbaum
Keyword(s):  
Early Time ◽  
Transport Processes ◽  
Special Role ◽  
Diffusive Transport ◽  
Internal Elastic Lamina ◽  
Time Model ◽  
Feeding Experiments ◽  
Endothelial Surface ◽  
Extracellular Lipid ◽  
Order Of Magnitude

In this paper a new theoretical framework is presented for analyzing the filtration and macromolecular convective-diffusive transport processes in the intimal region of an artery wall with widely dispersed macromolecular cellular leakage sites, as proposed in the leaky junction-cell turnover hypothesis of Weinbaum et al. [11]. In contrast to existing convection-diffusive models, which assume that the transport is either 1-D, or convection is primarily in a direction normal to the endothelial surface, the present model considers for the first time the nonuniform subendothelial pressure field that arises from the different hydraulic resistances of normal and leaky endothelial clefts and the special role of the internal elastic lamina (IEL) in modulating the horizontal transport of macromolecules after they have passed through the leaky clefts of cells that are either in mitosis or demonstrate IgG labeling. The new theory is able to quantitatively explain the growing body of recent experiments in which an unexpectedly rapid early-time growth of the leakage spot has been observed and the longer time asymptotic behavior in which the leakage spot appears to approach an equilibrium diameter. The new theory also predicts the observed doubling in macromolecular permeability between EBA labeled blue and white areas when the frequency of leakage sites is doubled. This frequency for doubling of permeability, however, is an order of magnitude smaller than predicted by the author’s previous model, Tzeghai et al. [10], in which only convection normal to the endothelial surface was considered and the pressure was uniform in the intima. The longer time model predictions are used to explain the time scale for the formation of liposomes [4] in subendothelial tissue matrix in animal feeding experiments where it has been observed that the extracellular lipid concentration rises sharply prior to the entry of monocytes into the intima [45].

scholarly journals Roles of cell and microvillus deformation and receptor-ligand binding kinetics in cell rolling

2008 ◽  
Vol 295 (4) ◽  
pp. H1439-H1450 ◽  
Author(s):  
Parag Pawar ◽  
Sameer Jadhav ◽  
Charles D. Eggleton ◽  
Konstantinos Konstantopoulos
Keyword(s):  
Ligand Binding ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Binding Kinetics ◽  
Cell Deformation ◽  
Receptor Ligand ◽  
Length Scales ◽  
Bond Behavior ◽  
Cell Rolling ◽  
Threshold Phenomenon

Polymorphonuclear leukocyte (PMN) recruitment to sites of inflammation is initiated by selectin-mediated PMN tethering and rolling on activated endothelium under flow. Cell rolling is modulated by bulk cell deformation (mesoscale), microvillus deformability (microscale), and receptor-ligand binding kinetics (nanoscale). Selectin-ligand bonds exhibit a catch-slip bond behavior, and their dissociation is governed not only by the force but also by the force history. Whereas previous theoretical models have studied the significance of these three “length scales” in isolation, how their interplay affects cell rolling has yet to be resolved. We therefore developed a three-dimensional computational model that integrates the aforementioned length scales to delineate their relative contributions to PMN rolling. Our simulations predict that the catch-slip bond behavior and to a lesser extent bulk cell deformation are responsible for the shear threshold phenomenon. Cells bearing deformable rather than rigid microvilli roll slower only at high P-selectin site densities and elevated levels of shear (≥400 s−1). The more compliant cells (membrance stiffness = 1.2 dyn/cm) rolled slower than cells with a membrane stiffness of 3.0 dyn/cm at shear rates >50 s−1. In summary, our model demonstrates that cell rolling over a ligand-coated surface is a highly coordinated process characterized by a complex interplay between forces acting on three distinct length scales.

scholarly journals From atomistic interfaces to dendritic patterns

2018 ◽  
Vol 376 (2113) ◽  
pp. 20170210 ◽  
Author(s):  
P. K. Galenko ◽  
D. V. Alexandrov
Keyword(s):  
Computational Modelling ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Boundary Integral ◽  
Transport Processes ◽  
Atomic Scale ◽  
Theme Issue ◽  
Two Phase ◽  
Field Methods ◽  
Atomistic Modelling

Transport processes around phase interfaces, together with thermodynamic properties and kinetic phenomena, control the formation of dendritic patterns. Using the thermodynamic and kinetic data of phase interfaces obtained on the atomic scale, one can analyse the formation of a single dendrite and the growth of a dendritic ensemble. This is the result of recent progress in theoretical methods and computational algorithms calculated using powerful computer clusters. Great benefits can be attained from the development of micro-, meso- and macro-levels of analysis when investigating the dynamics of interfaces, interpreting experimental data and designing the macrostructure of samples. The review and research articles in this theme issue cover the spectrum of scales (from nano- to macro-length scales) in order to exhibit recently developing trends in the theoretical analysis and computational modelling of dendrite pattern formation. Atomistic modelling, the flow effect on interface dynamics, the transition from diffusion-limited to thermally controlled growth existing at a considerable driving force, two-phase (mushy) layer formation, the growth of eutectic dendrites, the formation of a secondary dendritic network due to coalescence, computational methods, including boundary integral and phase-field methods, and experimental tests for theoretical models—all these themes are highlighted in the present issue. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’.

scholarly journals Dynamics of proteins in solution

2019 ◽  
Vol 52 ◽  
Author(s):  
Marco Grimaldo ◽  
Felix Roosen-Runge ◽  
Fajun Zhang ◽  
Frank Schreiber ◽  
Tilo Seydel
Keyword(s):  
Protein Dynamics ◽  
Protein Function ◽  
Center Of Mass ◽  
Mass Diffusion ◽  
Transport Processes ◽  
Side Chain ◽  
Neutron Spectroscopy ◽  
Length Scales ◽  
Comprehensive Picture ◽  
Mechanistic Understanding

AbstractThe dynamics of proteins in solution includes a variety of processes, such as backbone and side-chain fluctuations, interdomain motions, as well as global rotational and translational (i.e. center of mass) diffusion. Since protein dynamics is related to protein function and essential transport processes, a detailed mechanistic understanding and monitoring of protein dynamics in solution is highly desirable. The hierarchical character of protein dynamics requires experimental tools addressing a broad range of time- and length scales. We discuss how different techniques contribute to a comprehensive picture of protein dynamics, and focus in particular on results from neutron spectroscopy. We outline the underlying principles and review available instrumentation as well as related analysis frameworks.

Modeled Near-Field Environment Porosity Modification due to Coupled Thermohydrologic and Geochemical Processes

1999 ◽  
Vol 556 ◽  
Author(s):  
John J. Nitao ◽  
William E. Glassley
Keyword(s):  
Reactive Transport ◽  
Near Field ◽  
Mineral Dissolution ◽  
Rock Properties ◽  
Actual Distribution ◽  
Porosity Reduction ◽  
Field Environment ◽  
Flow Pathways ◽  
Waste Repositories ◽  
Dissolution And Precipitation

AbstractHeat generated by waste packages in nuclear waste repositories can modify rock properties by instigating mineral dissolution and precipitation along hydrothermal flow pathways. Modeling this reactive transport requires coupling fluid flow to permeability changes resulting from dissolution and precipitation. Modification of the NUFT thermohydrologic (TH) code package to account for this coupling in a simplified geochemical system has been used to model the timedependent change in porosity, permeability, matrix and fracture saturation, and temperature in the vicinity of waste-emplacement drifts, using conditions anticipated for the potential Yucca Mountain repository. The results show dramatic porosity reduction approximately 10 m above emplacement drifts within a few hundred years. Most of this reduction is attributed to deposition of solute load at the boiling front, although some of it also results from decreasing temperature along the flow path. The actual distribution of the nearly sealed region is sensitive to the time-dependent characteristics of the thermal load imposed on the environment and suggests that the geometry of the sealed region can be engineered by managing the waste-emplacement strategy and schedule.

scholarly journals THEMIS observations of plasma transport via eddy diffusion

2012 ◽  
Vol 30 (12) ◽  
pp. 1703-1707
Author(s):  
T. Izutsu ◽  
M. Fujimoto
Keyword(s):  
Boundary Layer ◽  
Eddy Diffusion ◽  
Quantitative Agreement ◽  
Transport Processes ◽  
Plasma Transport ◽  
Navier Stokes ◽  
Diffusive Transport ◽  
Low Latitude ◽  
Stokes Fluid ◽  
Low Latitude Boundary Layer

Abstract. We provide an event study of THEMIS observations of the low-latitude boundary layer in the dayside magnetosphere. Simultaneous multipoint observations obtained on 5 December 2008 show that the magnetosheath-like plasma in the low-latitude boundary layer is transferred earthward from the magnetopause. This earthward transport is accompanied by decrease in the density and fluctuating bulk flow. We calculate the eddy diffusion coefficients, which can be estimated from the observed velocity data, and found that the numbers are in good quantitative agreement with the spatial and time scales of the observed earthward transport signatures. It is shown that other possible plasma transport processes such as convection or diffusion induced by plasma wave turbulence are inconsistent with the observations. Our study strongly suggests that the observed transport is due to diffusive transport via turbulent eddy motions as is the case of an ordinary (Navier–Stokes) fluid.

Transport Phenomena Analysis in Proton Exchange Membrane Fuel Cells

2005 ◽  
Vol 127 (12) ◽  
pp. 1363-1379 ◽  
Author(s):  
Hongtan Liu ◽  
Tianhong Zhou ◽  
Ping Cheng
Keyword(s):  
Experimental Investigation ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Transport Phenomena ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Transport Processes ◽  
Proton Exchange ◽  
Exchange Membrane

The objective of this review is to provide a summary of modeling and experimental research efforts on transport phenomena in proton exchange membrane fuel cells (PEMFCs). Several representative PEMFC models and experimental studies in macro and micro PEMFCs are selected for discussion. No attempt is made to examine all the models or experimental studies, but rather the focus is to elucidate the macro-homogeneous modeling methodologies and representative experimental results. Since the transport phenomena are different in different regions of a fuel cell, fundamental phenomena in each region are first reviewed. This is followed by the presentation of various theoretical models on these transport processes in PEMFCs. Finally, experimental investigation on the cell performance of macro and micro PEMFC and DMFC is briefly presented.

Numerical modeling of multiple length scales in thermal transport processes

2014 ◽  
Vol 24 (4) ◽  
pp. 781-796 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Numerical Modeling ◽  
Boundary Conditions ◽  
Time Scales ◽  
Transport Processes ◽  
Thermal Processes ◽  
Length Scales ◽  
Content Type ◽  
Multiple Length Scales ◽  
Wide Range ◽  
Simulation Results

Purpose – Multiple length and time scales arise in a wide variety of practical and fundamental problems. It is important to obtain accurate and validated numerical simulation results, considering the different scales that exist, in order to predict, design and optimize the behavior of practical thermal processes and systems. The purpose of this paper is to present modeling at the different length scales and then addresses the question of coupling the different models to obtain the overall model for the system or process. Design/methodology/approach – Both numerical and experimental methods to obtain results at the different length scales, particularly at micro and nanoscales, are considered. Even though the paper focusses on length scales, multiple time scales lead to similar concerns and are also considered. The two circumstances considered in detail are multiple length scales in different domains and those in the same domain. These two cases have to be modeled quite differently in order to obtain a model for the overall process or system. The basic considerations involved in such a modeling are discussed. A wide range of thermal processes are considered and the methods that may be used are presented. The models employed must be validated and the accuracy of the simulation results established if the simulation results are to be used for prediction, control and design. Findings – Of particular interest are concerns like verification and validation, imposition of appropriate boundary conditions, and modeling of complex, multimode transport phenomena in multiple scales. Additional effects such as viscous dissipation, surface tension, buoyancy and rarefaction that could arise and complicate the modeling are discussed. Uncertainties that arise in material properties and in boundary conditions are also important in design and optimization. Large variations in the geometry and coupled multiple regions are also discussed. Research limitations/implications – The paper is largely focussed on multiple-scale considerations in thermal processes. Both numerical modeling/simulation and experimentation are considered, with the latter being used for validation and physical insight. Practical implications – Several examples from materials processing, environmental flows and electronic systems, including data centers, are given to present the different techniques that may be used to achieve the desired level of accuracy and predictability. Originality/value – Present state of the art and future needs in this interesting and challenging area are discussed, providing the impetus for further work. Different methods for treating multiscale problems are presented.

Sign in / Sign up

Export Citation Format

Share Document