A Bioinspired Active Micropump

2015 ◽  
Author(s):  
Prashanta Dutta ◽  
Jin Liu
Keyword(s):  
Fluid Flow ◽  
Osmotic Pressure ◽  
Sucrose Solution ◽  
Chemical Species ◽  
Mass Conservation ◽  
Pressure Head ◽  
Proton Gradient ◽  
Low Flow ◽  
Preliminary Design ◽  
Transporter Proteins

A preliminary design concept is provided for a bioinspired active micropump. The proposed micropump uses light energy to activate the transporter proteins (bacteriorhodopsin protein and sucrose/sugar transporter proteins), which create an osmotic pressure gradient and drive the fluid flow. The purpose of the bacteriorhodopsin protein is to pump proton from the pumping section to the sucrose source for a proton gradient. This proton gradient is used by the sucrose transporter proteins to transport sugar molecules from the sucrose solution chamber to the pumping channel, which generates an osmotic pressure in the pumping section. A numerical model is used to evaluate the performance of the micropump where the concentrations of proton and sucrose molecules are calculated using the conservation of chemical species equations. The fluid flow and pressure field are calculated from momentum and mass conservation equations. Simulation results predict that the micropump is capable of generating a pressure head that is comparable to other non-mechanical pumps. The proposed bioinspired self-sustained micropump will be most effective at low flow rate.

Hydrofractures and crustal-scale fluid flow

2021 ◽  
Author(s):  
Paul D. Bons ◽  
Tamara de Riese ◽  
Enrique Gomez-Rivas ◽  
Isaac Naaman ◽  
Till Sachau
Keyword(s):  
Fluid Flow ◽  
Large Scale ◽  
Low Flow ◽  
Fault System ◽  
Tectonic Activity ◽  
Field Evidence ◽  
Dehydration Reactions ◽  
Matrix Flow ◽  
Matrix Porosity ◽  
Fluid Sources

<p>Fluids can circulate in all levels of the crust, as veins, ore deposits and chemical alterations and isotopic shifts indicate. It is furthermore generally accepted that faults and fractures play a central role as preferred fluid conduits. Fluid flow is, however, not only passively reacting to the presence of faults and fractures, but actively play a role in their creation, (re-) activation and sealing by mineral precipitates. This means that the interaction between fluid flow and fracturing is a two-way process, which is further controlled by tectonic activity (stress field), fluid sources and fluxes, as well as the availability of alternative fluid conduits, such as matrix porosity. Here we explore the interaction between matrix permeability and dynamic fracturing on the spatial and temporal distribution of fluid flow for upward fluid fluxes. Envisaged fluid sources can be dehydration reactions, release of igneous fluids, or release of fluids due to decompression or heating.</p><p> </p><p>Our 2D numerical cellular automaton-type simulations span the whole range from steady matrix-flow to highly dynamical flow through hydrofractures. Hydrofractures are initiated when matrix flow is insufficient to maintain fluid pressures below the failure threshold. When required fluid fluxes are high and/or matrix porosity low, flow is dominated by hydrofractures and the system exhibits self-organised critical phenomena. The size of fractures achieves a power-law distribution, as failure events may sometimes trigger avalanche-like amalgamation of hydrofractures. By far most hydrofracture events only lead to local fluid flow pulses within the source area. Conductive fracture networks do not develop if hydrofractures seal relatively quickly, which can be expected in deeper crustal levels. Only the larger events span the whole system and actually drain fluid from the system. We present the 10 square km hydrothermal Hidden Valley Mega-Breccia on the Paralana Fault System in South Australia as a possible example of large-scale fluid expulsion events. Although field evidence suggests that the breccia formed over a period of at least 150 Myrs, actual cumulative fluid duration may rather have been in the order of days only. This example illustrates the extreme dynamics that crustal-scale fluid flow in hydrofractures can achieve.</p>

Penetrability of a marine pseudomonad by inulin, sucrose, and glycerol and its relation to the mechanism of lysis

1970 ◽  
Vol 16 (2) ◽  
pp. 75-81 ◽  
Author(s):  
Francis L. A. Buckmire ◽  
Robert A. MacLeod
Keyword(s):  
Osmotic Pressure ◽  
Exchange Resin ◽  
Sucrose Solution ◽  
Cell Envelope ◽  
Sucrose Concentration ◽  
Ion Exchange Resin ◽  
Cell Preparation ◽  
Cell Envelopes ◽  
Almost All ◽  
Isolated Cell

Cells of a marine pseudomonad were prevented from lysing when suspended in a 0.15 M sucrose solution even after treatment of the sucrose with an ion exchange resin to remove contaminating trace elements. Isolated cell envelopes of the organism in concentrations of sucrose able to prevent lysis of the cells released non-dialyzable hexosamine-containing material into the suspending medium. This did not occur when the envelopes were suspended in concentrations of NaCl able to prevent cell lysis. Glycerol was found to occupy almost all the available fluid space in a packed cell preparation of the organism. Sucrose occupied less space than glycerol, and inulin the least. When the sucrose concentration was increased from 3 mM to 0.2 M, both the sucrose and inulin spaces increased. The results have been interpreted as indicating that sucrose prevents lysis by balancing the internal osmotic pressure of the cells, that the various layers of the cell envelope of the organism differ in their permeability to various solutes, and that the whole cell shrinks in solutions of high osmotic pressure.

scholarly journals Study of FRSN cells migration under the conditions of continuous low flow

2018 ◽  
pp. 144-147
Author(s):  
А.А. Московцев ◽  
Д.В. Колесов ◽  
А.Н. Мыльникова ◽  
А.А. Кубатиев
Keyword(s):  
Stem Cells ◽  
Shear Stress ◽  
Cell Migration ◽  
Fluid Flow ◽  
Flow Direction ◽  
The Body ◽  
Low Flow ◽  
Slip Mode ◽  
Stick Slip ◽  
Low Intensity

Поток жидкости оказывает значительное влияние на морфофункциональное состояние большинства клеток в организме. Это может проявляться в миграции клеток под действием сдвиговой деформации или градиента питательных веществ. Мезенхимные стволовые фибробластоподобные клетки FRSN были культивированы в условиях воздействия постоянного потока жидкости в микрофлюидном чипе. Проведены исследования миграции клеток на разных стадиях адгезии под действием потока в различных областях чипа. Обнаружены значительные перемещения клеток в режиме «stick-slip» вдоль направления потока. The fluid flow exerts a significant effect on most cells in the body. This effect can involve cell migration under the action of shear stress or nutrient gradient. FRSN mesenchymal stem cells were cultured under the action of a constant fluid flow of low intensity in a microfluidic chip. The study of cell migration at different stages of adhesion was performed under the action of flow in different areas of the chip. Significant cell movements in a stick-slip mode along the flow direction were observed.

scholarly journals TAMI-15. THE EFFECT OF INTERSTITIAL FLUID FLOW AND ASTROCYTES / MICROGLIA ON INVASION, PROLIFERATION AND STEMNESS OF PATIENT-DERIVED GLIOMA STEM CELLS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii216-ii216
Author(s):  
Naciye Atay ◽  
Jessica Yuan ◽  
Chase Cornelison ◽  
Jennifer Munson
Keyword(s):  
Stem Cells ◽  
Fluid Flow ◽  
Interstitial Fluid ◽  
Pressure Head ◽  
Molecular Classification ◽  
Patient Specific ◽  
Glioma Stem Cells ◽  
Interstitial Fluid Flow ◽  
Static Conditions

Abstract SIGNIFICANCE Glioblastoma is a highly infiltrative, malignant, and deadly glioma that can be classified into subtypes based on molecular classification. Treatment resistant glioma stem cells (GSCs) depend on the tumor microenvironment (TME) to drive recurrence. Cellular composition and interstitial fluid flow (IFF) are significant aspects of the TME. IFF and astrocyte and microglia (A+M) presence have independently been shown to mediate invasion. This study’s goal is to expand our knowledge of IFF and A+M effects on invasion to proliferation and stemness. METHODS Seven patient-derived GSC lines were tested in an in vitro 3D model, which consists of GSCs ± A+M resuspended in 0.2% hyaluronan / 0.12% rat tail collagen I gel. The gel was applied to an 8um pore 96-well transwell system. Flow and static conditions were modeled with and without a pressure head above the gel, respectively. Cells beyond the transwell membrane after 18 hrs of incubation were considered invaded. Stemness and proliferation were determined via flow cytometry for CD71 and Ki67, respectively. RESULTS/CONCLUSIONS The three mesenchymal GSC lines tested exhibited the largest IFF fold increases in stemness, proliferation, and invasion with averages of 23.9, 19.1, and 2.1, respectively. CD44+ cell populations, highest in mesenchymal cells, had a strong correlation with proliferation (R=0.8439) and stemness (R=0.7829) under flow. Furthermore, depending on the cell line/subtype, the addition of A+M either amplified, reduced, reversed, mitigated, or kept constant the effect of IFF on invasion and proliferation. Incorporating A+M never amplified the effect of IFF on stemness. Adding A+M had a strong effect on the IFF fold change of at least one parameter in six of the cell lines. This is the first presentation showing that IFF, patient-specific, and context-specific factors contribute to both increased proliferation, and maintenance of stem-like phenotypes in glioma.

Visualisation of fluid flow mechanisms through a viscous-porous rock-analogue medium – experiment and model results

2021 ◽  
Author(s):  
Reinier van Noort ◽  
Lawrence Hongliang Wang ◽  
Viktoriya Yarushina
Keyword(s):  
Fluid Flow ◽  
Bulk Viscosity ◽  
Numerical Models ◽  
Digital Camera ◽  
Injection Rate ◽  
Low Flow ◽  
Experimental Conditions ◽  
Deep Earth ◽  
Flow Mechanisms ◽  
Flow Through

<p>Understanding fluid flow patterns in the shallow and deep earth is one of the major challenges of modern earth sciences. Fluid flow may be slow and pervasive, or fast and focused. In the deep earth, focused fluid flow may result in, for example, dikes, veins, volcanic diatremes and gas venting systems. In the shallow Earth, focused fluid flow can be found in the form of fluid escape pipes and gas conducting chimneys, mud volcanoes, sand injectites, pockmarks, hydrothermal vent complexes, etc.</p><p>Focused fluid flow has been reproduced in visco-plastic models of flow through porous materials. However, the mechanisms that cause fluid flow to focus along such relatively narrow channels, with transiently elevated permeability, have not been investigated thoroughly in experiments. We have carried out experiments in a transparent Hele-Shaw cell. In our experiments, a hydrous fluid is injected into an aggregate of viscous grains, and the mechanisms by which this injected fluid flows are recorded using a digital camera. Our experiments demonstrate a dependence of fluid flow mechanisms on the injection rate. At low injection rate, we observe the formation of a slowly-rising diapir. As this diapir slowly rises through the porous medium, it is fed by transient, focused fluid flow following the path of the rising diapir. Once the diapir escapes through the surface of our aggregate, continued fluid flow through the porous aggregate is focused and transient. At high injection rate, instead of a diapir fed by focused fluid flow, an open channel forms as a result of local fluidization of the granular material.</p><p>Our experimental observations are interpreted through visco-plastic models simulating the experimental conditions. These numerical models can reproduce the diapirs observed in our experiments at low flow rate by assuming flow through a layered porous aggregate, with a layer with relatively high bulk viscosity overlying a layer with relatively low bulk viscosity. For low injection rates, such a model reproduces focused fluid flow in the low-viscosity layer, that feeds into a slowly rising diapir in the high-viscosity layer. This model observation thus suggests that the passage of the rising diapir in our experiments leaves a trail, where the aggregate bulk viscosity is lowered and along which ongoing fluid flow can focus transiently.</p>

Hydrofractures and crustal-scale fluid flow

2020 ◽  
Author(s):  
Paul D. Bons ◽  
Tamara de Riese ◽  
Enrique Gomez-Rivas ◽  
Isaac Naaman ◽  
Till Sachau
Keyword(s):  
Fluid Flow ◽  
Large Scale ◽  
Low Flow ◽  
Fault System ◽  
Tectonic Activity ◽  
Field Evidence ◽  
Dehydration Reactions ◽  
Matrix Flow ◽  
Matrix Porosity ◽  
Fluid Sources

<p>Fluids can circulate in all levels of the crust, as veins, ore deposits and chemical alterations and isotopic shifts indicate. It is furthermore generally accepted that faults and fractures play a central role as preferred fluid conduits. Fluid flow is, however, not only passively reacting to the presence of faults and fractures, but actively play a role in their creation, (re-) activation and sealing by mineral precipitates. This means that the interaction between fluid flow and fracturing is a two-way process, which is further controlled by tectonic activity (stress field), fluid sources and fluxes, as well as the availability of alternative fluid conduits, such as matrix porosity. Here we explore the interaction between matrix permeability and dynamic fracturing on the spatial and temporal distribution of fluid flow for upward fluid fluxes. Envisaged fluid sources can be dehydration reactions, release of igneous fluids, or release of fluids due to decompression or heating.</p><p> </p><p>Our 2D numerical cellular automaton-type simulations span the whole range from steady matrix-flow to highly dynamical flow through hydrofractures. Hydrofractures are initiated when matrix flow is insufficient to maintain fluid pressures below the failure threshold. When required fluid fluxes are high and/or matrix porosity low, flow is dominated by hydrofractures and the system exhibits self-organised critical phenomena. The size of fractures achieves a power-law distribution, as failure events may sometimes trigger avalanche-like amalgamation of hydrofractures. By far most hydrofracture events only lead to local fluid flow pulses within the source area. Conductive fracture networks do not develop if hydrofractures seal relatively quickly, which can be expected in deeper crustal levels. Only the larger events span the whole system and actually drain fluid from the system. We present the 10 square km hydrothermal Hidden Valley Mega-Breccia on the Paralana Fault System in South Australia as a possible example of large-scale fluid expulsion events. Although field evidence suggests that the breccia formed over a period of at least 150 Myrs, actual cumulative fluid duration may rather have been in the order of days only. This example illustrates the extreme dynamics that crustal-scale fluid flow in hydrofractures can achieve.</p>

Modifying the Classical 1D Catalyst Model to Include Axial Conduction and Diffusion

2012 ◽  
Author(s):  
Sudarshan Loya ◽  
Christopher Depcik
Keyword(s):  
Equations Of Motion ◽  
Chemical Species ◽  
Earth Metal ◽  
Space Velocity ◽  
Low Flow ◽  
Lean Nox Trap ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Axial Conduction ◽  
And Diffusion

Lean NOx Trap (LNT) catalytic aftertreatment devices are one potential option for the reduction of oxides of nitrogen (NOx) in the exhaust of Compression Ignition engines. They work through a controlled modulation between a storage phase that captures NOx over an alkali earth metal and a regeneration phase that reduces the stored nitrates on the surface using a rich pulse of injected fuel or via stoichiometric engine operation. This rich phase has an associated fuel penalty while being relatively difficult to control through temperature and chemical species. In order to improve system efficiency, a number of researchers have proposed dual leg LNT systems using two LNTs, of which one is always storing while the other is undergoing regeneration. The majority of the exhaust flows through the storage LNT while only a small fraction (low space velocity) advects across the regeneration LNT. This increases the regeneration residence time, improving effectiveness and decreasing the amount of fuel used. From an LNT simulation standpoint, most researchers utilize the classical one-dimensional (1D) aftertreatment model constructed from the Euler equations of motion that neglects axial conduction and diffusion. This paper explores the applicability of this model under low flow situations prevalent in a dual leg LNT system through a carbon monoxide light-off experiment. The authors chose this type of experiment in order to focus purely on fluid mechanics and not the choice of LNT reaction mechanism. The results suggest that a Navier-Stokes (N-S) version of the 1D aftertreatment model is preferred for the regeneration leg of a dual LNT system. Moreover, the authors provide the solution of such a model within this paper.

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