scholarly journals What process causes the slowdown of pressure solution creep

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
Renchao Lu ◽  
Chaojie Cheng ◽  
Thomas Nagel ◽  
Harald Milsch ◽  
Hideaki Yasuhara ◽  
...  
Keyword(s):  
Transport Process ◽  
Creep Behaviour ◽  
Water Film ◽  
Stress Redistribution ◽  
Pressure Solution ◽  
List Type ◽  
Surface Boundary ◽  
Solute Accumulation ◽  
Active Processes ◽  
Rate Limiting

Abstract The slowdown of pressure solution creep has been thought to be caused by stress redistribution. This study presents a fresh view towards this creep behaviour. Basically, two rate-limiting mechanisms come into play amid pressure solution creep: (1) stress redistribution across expanding inter-granular contacts and (2) solute accumulation in the water film. Because non-hydrostatic dissolution occurs under open system conditions, solute accumulation in the water film is constrained by the ensuing solute transport process. Relying on the matter exchange across the contact surface boundary, the active processes in the voids, e.g., solute migration and deposition, affect pressure solution creep. Based upon the above, we sum up two requirements that have to be met for achieving chemical compaction equilibrium: (1) the Gibbs free energy of reaction, i.e., the driving force of non-hydrostatic dissolution process, gets depleted and (2) the concentration gradient between the water film and surrounding pore water vanishes. Highlights The slowdown of pressure solution creep is a combined result of stress migration across contacts and solute accumulation in the water film. Matter exchange with the surroundings inhibits solute accumulation in the water film. This article identifies two prerequisites that need to be fulfilled for achieving chemical compaction equilibrium.

scholarly journals Geometry of Former Subglacial Water Channels and Cavities

1979 ◽  
Vol 23 (89) ◽  
pp. 335-346 ◽  
Author(s):  
Joseph Walder ◽  
Bernard Hallet
Keyword(s):  
Flow Direction ◽  
Water Film ◽  
List Type ◽  
Ice Flow ◽  
Glacier Terminus ◽  
Basal Ice ◽  
Limestone Bedrock ◽  
Rock Interface ◽  
Active Processes ◽  
Nearly Continuous

AbstractThe spatial pattern of the formerly active processes of water flow, cavitation, abrasion, dissolution, and precipitation at the base of a small cirque glacier has been reconstructed by detailed mapping of surficial features on recently deglaciated limestone bedrock near the glacier terminus. Our interpretation of these features, which reflect basal conditions averaged over a period of several or several tens of years, leads us to the following conclusions: 1.A nearly continuous, non-arborescent network of cavities and incised channels existed and probably acted as the primary drainage of melt waters. This network evolved through time as many channels were filled, perhaps intermittently, by basal ice.2.At least 20% of the glacier sole was separated from the bed by water-filled cavities. The rest of the glacier–rock interface characteristically comprises a very thin water film.3.Abrasion was locally intensified, relative to chemical alteration, in 5–10 m wide zones paralleling the ice-flow direction, perhaps as a result of locally enhanced sheet flow of subglacial water.

scholarly journals Geometry of Former Subglacial Water Channels and Cavities

1979 ◽  
Vol 23 (89) ◽  
pp. 335-346 ◽  
Author(s):  
Joseph Walder ◽  
Bernard Hallet
Keyword(s):  
Flow Direction ◽  
Water Film ◽  
List Type ◽  
Ice Flow ◽  
Glacier Terminus ◽  
Basal Ice ◽  
Limestone Bedrock ◽  
Rock Interface ◽  
Active Processes ◽  
Nearly Continuous

AbstractThe spatial pattern of the formerly active processes of water flow, cavitation, abrasion, dissolution, and precipitation at the base of a small cirque glacier has been reconstructed by detailed mapping of surficial features on recently deglaciated limestone bedrock near the glacier terminus. Our interpretation of these features, which reflect basal conditions averaged over a period of several or several tens of years, leads us to the following conclusions:1.A nearly continuous, non-arborescent network of cavities and incised channels existed and probably acted as the primary drainage of melt waters. This network evolved through time as many channels were filled, perhaps intermittently, by basal ice.2.At least 20% of the glacier sole was separated from the bed by water-filled cavities. The rest of the glacier–rock interface characteristically comprises a very thin water film.3.Abrasion was locally intensified, relative to chemical alteration, in 5–10 m wide zones paralleling the ice-flow direction, perhaps as a result of locally enhanced sheet flow of subglacial water.

Simulation of porosity reduction in random structures

1990 ◽  
Vol 5 (10) ◽  
pp. 2184-2196 ◽  
Author(s):  
P. B. Visscher ◽  
Joseph E. Cates
Keyword(s):  
Interface Velocity ◽  
Periodic Boundary Conditions ◽  
Pressure Solution ◽  
Forward Motion ◽  
Porosity Reduction ◽  
Random Structures ◽  
The Difference ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Rate Limiting

We describe an algorithm for computing the motion of a solid-liquid interface in 2D, which is applicable to geological pressure solution or to pressure sintering. The backward motion (toward the solid) of the interface is due to dissolution of the solid, and the forward motion (away from the solid) is due to the inverse process of reprecipitation. The interface velocity is assumed proportional to the difference between the solubility of the solid and the concentration of the solution. The former is dependent upon stress (the phenomenon of “pressure solution”), so our algorithm must also keep track of the stress. We use a Lagrangian grid, with constant-stress periodic boundary conditions. The method has been applied to porosity reduction in sandstone. It is applicable to other interface-following problems, such as freezing, if the motion is slow enough that heat transport is not rate-limiting.

Dye Transport Across the Retinal Basement Membrane of the Blowfly Calljphora Erythrocephala

1989 ◽  
Vol 141 (1) ◽  
pp. 47-59
Author(s):  
E. WEYRAUTHER ◽  
J. G.H. ROEBROEK ◽  
D. G. STAVENGA
Keyword(s):  
Low Temperature ◽  
Transport Process ◽  
Trypan Blue ◽  
Lucifer Yellow ◽  
Phenol Red ◽  
Calliphora Erythrocephala ◽  
Time Constants ◽  
Dye Transport ◽  
Procion Yellow ◽  
Active Processes

In the blowfly, Calliphora erythrocephala, transport of dye into or out of the retina, following injection into the eye or thorax, was investigated, mainly by microspectrophotometry and fluorimetry. After injection into the eye, Phenol Red, Trypan Blue, Lucifer Yellow and 9-amino-acridine were transported out of the retina; Procion Yellow and Rhodamine-123 stayed in it. The time constants of this transport process were in the range 45–80 min at 23°C, depending on the dye. When Lucifer Yellow was injected into the thorax, it was transported into the retina. The transport of these dyes across the retina was inhibited by nitrogen, ouabain and low temperature, indicating that active processes are involved.

scholarly journals Activity-dependent nucleation of dynamic microtubules at presynaptic boutons is required for neurotransmission

2019 ◽  
Author(s):  
Xiaoyi Qu ◽  
Atul Kumar ◽  
Heike Blockus ◽  
Clarissa Waites ◽  
Francesca Bartolini
Keyword(s):  
Synaptic Vesicle ◽  
Neuronal Activity ◽  
Neurotransmitter Release ◽  
Hippocampal Neurons ◽  
De Novo ◽  
List Type ◽  
Neuronal Function ◽  
Presynaptic Boutons ◽  
Rate Limiting ◽  
Activity Dependent

SUMMARYControl of microtubule (MT) dynamics is critical for neuronal function. Whether MT nucleation is regulated at presynaptic boutons and influences overall presynaptic activity remains unknown. By visualizing MT dynamics at individual excitatory en passant boutons in axons of hippocampal neurons we found that MTs preferentially grow from presynaptic boutons as a result of γ-tubulin and augmin-dependent nucleation. MT nucleation at boutons is promoted by neuronal activity, functionally coupled to synaptic vesicle (SV) transport, and required for neurotransmission. Hence, en passant boutons act as hotspots for activity-dependent MT nucleation, which is required for neurotransmission by providing the tracks for a rate-limiting supply of SVs to sites of neurotransmitter release.HighlightsExcitatory boutons are hotspots for neuronal activity-induced γ-tubulin dependent MT nucleationThe augmin complex is required for the correct polarity of presynaptic de novo nucleated MTsPresynaptic MT nucleation promotes SV motility and exocytosis at sites of releaseIn BriefOur results demonstrate that excitatory en passant boutons are hotspots for neuronal activity-induced γ-tubulin- and augmin-dependent oriented MT nucleation, and that the resulting presynaptic de novo nucleated MTs promote inter-bouton SV motility which is rate-limiting for neurotransmitter release.

Numerical modelling of pressure solution in sandstone, rate-limiting processes and the effect of clays

2002 ◽  
Vol 200 (1) ◽  
pp. 41-60 ◽  
Author(s):  
E. Gundersen ◽  
D. K. Dysthe ◽  
F. Renard ◽  
K. Bjørlykke ◽  
B. Jamtveit
Keyword(s):  
Numerical Modelling ◽  
Pressure Solution ◽  
Rate Limiting

Book Reviews

Tempo ◽  
1995 ◽  
pp. 29-36
Keyword(s):  
List Type

Volume I of Messiaen's ‘Traite’, ‘Music and Color’, and organ recordings Christopher DingleRobert Craft's Stravinsky memoirs and recordings Rodney Lister

Open discussion

1982 ◽  
Vol 99 ◽  
pp. 605-613
Author(s):  
P. S. Conti
Keyword(s):  
Buenos Aires ◽  
Large Mass ◽  
List Type ◽  
Common Phenomenon ◽  
Open Discussion ◽  
The Stability ◽  
Ring Nebulae

Conti: One of the main conclusions of the Wolf-Rayet symposium in Buenos Aires was that Wolf-Rayet stars are evolutionary products of massive objects. Some questions:–Do hot helium-rich stars, that are not Wolf-Rayet stars, exist?–What about the stability of helium rich stars of large mass? We know a helium rich star of ∼40 MO. Has the stability something to do with the wind?–Ring nebulae and bubbles : this seems to be a much more common phenomenon than we thought of some years age.–What is the origin of the subtypes? This is important to find a possible matching of scenarios to subtypes.

Solar Corona Investigation by the Coronal Line Photometer at Lomnický Peak

1994 ◽  
Vol 144 ◽  
pp. 431-434
Author(s):  
M. Minarovjech ◽  
M. Rybanský
Keyword(s):  
Solar Corona ◽  
Time Resolution ◽  
Active Regions ◽  
High Time ◽  
High Time Resolution ◽  
List Type ◽  
Type Number ◽  
Coronal Line ◽  
Global Cycle

AbstractThis paper deals with a possibility to use the ground-based method of observation in order to solve basic problems connected with the solar corona research. Namely:1.heating of the solar corona2.course of the global cycle in the corona3.rotation of the solar corona and development of active regions.There is stressed a possibility of high-time resolution of the coronal line photometer at Lomnický Peak coronal station, and use of the latter to obtain crucial observations.

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