scholarly journals Water Transport and Ion Diffusion Investigation of an Amphotericin B-Based Channel Applied to Forward Osmosis: A Simulation Study

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 646
Author(s):  
Hao-Chen Wu ◽  
Tomohisa Yoshioka ◽  
Keizo Nakagawa ◽  
Takuji Shintani ◽  
Hideto Matsuyama
Keyword(s):  
Amphotericin B ◽  
Water Transport ◽  
Water Permeability ◽  
Salt Water ◽  
Water Channel ◽  
Forward Osmosis ◽  
Water Molecules ◽  
Ion Leakage ◽  
Channel Models ◽  
Water Permeation

The use of an Amphotericin B_Ergosterol (AmBEr) channel as an artificial water channel in forward osmosis filtration (FO) was studied via molecular dynamics (MD) simulation. Three channel models were constructed: a common AmBEr channel and two modified C3deOAmB_Ergosterol (C3deOAmBEr) channels with different diameters (12 Å and 18 Å). During FO filtration simulation, the osmotic pressure of salt-water was a driving force for water permeation. We examined the effect of the modified C3deOAmBEr channel on the water transport performance. By tracing the change of the number of water molecules along with simulation time in the saltwater region, the water permeability of the channel models could be calculated. A higher water permeability was observed for a modified C3deOAmBEr channel, and there was no ion permeation during the entire simulation period. The hydrated ions and water molecules were placed into the channel to explore the ion leakage behavior of the channels. The mean squared displacement (MSD) of ions and water molecules was obtained to study the ion leakage performance. The Amphotericin B-based channels showed excellent selectivity of water molecules against ions. The results obtained on an atomistic scale could assist in determining the properties and the optimal filtration applications for Amphotericin B-based channels.

scholarly journals Direct visualization of the arterial wall water permeability barrier using CARS microscopy

2017 ◽  
Vol 114 (18) ◽  
pp. 4805-4810 ◽  
Author(s):  
Bertrand M. Lucotte ◽  
Chloe Powell ◽  
Jay R. Knutson ◽  
Christian A. Combs ◽  
Daniela Malide ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Water Permeability ◽  
Vascular Function ◽  
Basolateral Membrane ◽  
Water Channel ◽  
Vascular Complications ◽  
Permeability Barrier ◽  
Internal Elastic Lamina ◽  
Water Permeation ◽  
Cars Microscopy

The artery wall is equipped with a water permeation barrier that allows blood to flow at high pressure without significant water leak. The precise location of this barrier is unknown despite its importance in vascular function and its contribution to many vascular complications when it is compromised. Herein we map the water permeability in intact arteries, using coherent anti-Stokes Raman scattering (CARS) microscopy and isotopic perfusion experiments. Generation of the CARS signal is optimized for water imaging with broadband excitation. We identify the water permeation barrier as the endothelial basolateral membrane and show that the apical membrane is highly permeable. This is confirmed by the distribution of the AQP1 water channel within endothelial membranes. These results indicate that arterial pressure equilibrates within the endothelium and is transmitted to the supporting basement membrane and internal elastic lamina macromolecules with minimal deformation of the sensitive endothelial cell. Disruption of this pressure transmission could contribute to endothelial cell dysfunction in various pathologies.

scholarly journals Water transport through epoxy-based powder pipeline coatings

2021 ◽  
Author(s):  
Hossein Zargarnezhad ◽  
Edouard Asselin ◽  
Dennis Wong ◽  
C.N. Catherine Lam
Keyword(s):  
Water Transport ◽  
Powder Coating ◽  
Operating Conditions ◽  
Vapor Transport ◽  
Internal Stresses ◽  
Water Molecules ◽  
Epoxy Coatings ◽  
Water Permeation ◽  
Vapor Permeation ◽  
Self Association

Hydration of epoxy coatings reduces adhesion performance and causes degradation of the material, such as microstructural failures. Quantification of water vapor transport at elevated temperatures is fundamental to understanding polymer coating performance, especially when the coating is exposed to extreme operating conditions. As the water activity increases, the permeability/selectivity of polymers against other permeants changes. In this study, we examined the water permeation kinetics of two common epoxy-based powder coating systems for pipelines (fusion-bonded epoxy, FBE, and high-performance powder coating, HPPC) across a range of industrially-relevant temperatures (from room temperature to 80°C). Specifically, we utilized vapor permeation features of FBE and HPPC films with quantification of equilibrium flux as a function of temperature and pressure. In addition, we analyzed the nonlinear dependency of water transport on the vapor concentration at 65°C. The vapor transport analysis demonstrated that although data for FBE were indicative of a decrease in permeability around 65°C, perhaps due to self-association of water molecules, the coating was likely to experience a plasticization pressure around this temperature. We also examined microstructural changes of the epoxy network due to water transport. Our results revealed evidence of irreversible damage to epoxy coatings under wet-state conditions above 65°C. It appears that the combination of thermal exposure and internal stresses in the glassy epoxy lead to a phase separation of filler particles from the epoxy matrix, as well as to a distinctive cavity formation in the coating membrane. Yet, despite formation of percolating paths for water transport, our results indicate that vapor permeation is primarily restrained due to self-association of water molecules. The vapor transport flux and its permeance are lowered by one order of magnitude in the multilayered HPPC thanks to the moisture-resistant polyethylene topcoat, thus reducing the extent of damage to the underlying substrate. Since barrier protection against gas phase diffusion is controlled by the FBE primer, however, consequences of coating hydration are more pronounced in the overall selectivity toward gaseous transport. Hydrothermal exposure is likely to increase aggregate porosity of the coating and a conservative implementation of standard coating requirements is therefore reasonable to avoid early degradation issues.

Imidazole derivatives as artificial water channel building-blocks: structural design influence on water permeability

2018 ◽  
Vol 209 ◽  
pp. 113-124 ◽  
Author(s):  
Zhanhu Sun ◽  
Istvan Kocsis ◽  
Yuhao Li ◽  
Yves-Marie Legrand ◽  
Mihail Barboiu
Keyword(s):  
Water Transport ◽  
Water Permeability ◽  
Structural Design ◽  
Water Channel ◽  
Building Blocks ◽  
Structural Modifications ◽  
Imidazole Derivatives ◽  
Permeability Variation ◽  
Self Assembled ◽  
Artificial Water

A series of mono- and di-ureidoethylimidazole derivatives were tested as self-assembled supramolecular channels for water transport across a vesicle bilayer. Structural modifications of the selected compounds were related to permeability variation.

scholarly journals Water transport through epoxy-based powder pipeline coatings

2021 ◽  
Author(s):  
Hossein Zargarnezhad ◽  
Edouard Asselin ◽  
Dennis Wong ◽  
C.N. Catherine Lam
Keyword(s):  
Water Transport ◽  
Powder Coating ◽  
Operating Conditions ◽  
Vapor Transport ◽  
Internal Stresses ◽  
Water Molecules ◽  
Epoxy Coatings ◽  
Water Permeation ◽  
Vapor Permeation ◽  
Self Association

Hydration of epoxy coatings reduces adhesion performance and causes degradation of the material, such as microstructural failures. Quantification of water vapor transport at elevated temperatures is fundamental to understanding polymer coating performance, especially when the coating is exposed to extreme operating conditions. As the water activity increases, the permeability/selectivity of polymers against other permeants changes. In this study, we examined the water permeation kinetics of two common epoxy-based powder coating systems for pipelines (fusion-bonded epoxy, FBE, and high-performance powder coating, HPPC) across a range of industrially-relevant temperatures (from room temperature to 80°C). Specifically, we utilized vapor permeation features of FBE and HPPC films with quantification of equilibrium flux as a function of temperature and pressure. In addition, we analyzed the nonlinear dependency of water transport on the vapor concentration at 65°C. The vapor transport analysis demonstrated that although data for FBE were indicative of a decrease in permeability around 65°C, perhaps due to self-association of water molecules, the coating was likely to experience a plasticization pressure around this temperature. We also examined microstructural changes of the epoxy network due to water transport. Our results revealed evidence of irreversible damage to epoxy coatings under wet-state conditions above 65°C. It appears that the combination of thermal exposure and internal stresses in the glassy epoxy lead to a phase separation of filler particles from the epoxy matrix, as well as to a distinctive cavity formation in the coating membrane. Yet, despite formation of percolating paths for water transport, our results indicate that vapor permeation is primarily restrained due to self-association of water molecules. The vapor transport flux and its permeance are lowered by one order of magnitude in the multilayered HPPC thanks to the moisture-resistant polyethylene topcoat, thus reducing the extent of damage to the underlying substrate. Since barrier protection against gas phase diffusion is controlled by the FBE primer, however, consequences of coating hydration are more pronounced in the overall selectivity toward gaseous transport. Hydrothermal exposure is likely to increase aggregate porosity of the coating and a conservative implementation of standard coating requirements is therefore reasonable to avoid early degradation issues.

scholarly journals The Water Channel Aquaporin-8 Is Mainly Intracellular in Rat Hepatocytes, and Its Plasma Membrane Insertion Is Stimulated by Cyclic AMP

2001 ◽  
Vol 276 (15) ◽  
pp. 12147-12152 ◽  
Author(s):  
Fabiana Garcı́a ◽  
Arlinet Kierbel ◽  
M. Cecilia Larocca ◽  
Sergio A. Gradilone ◽  
Patrick Splinter ◽  
...  
Keyword(s):  
Water Transport ◽  
Water Permeability ◽  
Plasma Membranes ◽  
Water Channel ◽  
Rat Hepatocytes ◽  
Immunoblot Analysis ◽  
Subcellular Fractionation ◽  
Bile Secretion ◽  
Confocal Immunofluorescence Microscopy ◽  
Microsomal Membranes

We previously found that water transport across hepatocyte plasma membranes occurs mainly via a non-channel mediated pathway. Recently, it has been reported that mRNA for the water channel, aquaporin-8 (AQP8), is present in hepatocytes. To further explore this issue, we studied protein expression, subcellular localization, and regulation of AQP8 in rat hepatocytes. By subcellular fractionation and immunoblot analysis, we detected anN-glycosylated band of ∼34 kDa corresponding to AQP8 in hepatocyte plasma and intracellular microsomal membranes. Confocal immunofluorescence microscopy for AQP8 in cultured hepatocytes showed a predominant intracellular vesicular localization. Dibutyryl cAMP (Bt2cAMP) stimulated the redistribution of AQP8 to plasma membranes. Bt2cAMP also significantly increased hepatocyte membrane water permeability, an effect that was prevented by the water channel blocker dimethyl sulfoxide. The microtubule blocker colchicine but not its inactive analog lumicolchicine inhibited the Bt2cAMP effect on both AQP8 redistribution to cell surface and hepatocyte membrane water permeability. Our data suggest that in rat hepatocytes AQP8 is localized largely in intracellular vesicles and can be redistributed to plasma membranes via a microtubule-depending, cAMP-stimulated mechanism. These studies also suggest that aquaporins contribute to water transport in cAMP-stimulated hepatocytes, a process that could be relevant to regulated hepatocyte bile secretion.

scholarly journals Porous organic cages as synthetic water channels

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi Di Yuan ◽  
Jinqiao Dong ◽  
Jie Liu ◽  
Daohui Zhao ◽  
Hui Wu ◽  
...  
Keyword(s):  
Water Channel ◽  
Water Channels ◽  
Water Desalination ◽  
Water Molecules ◽  
One Dimensional ◽  
Water Permeation ◽  
Hydrated Ions ◽  
Branched Chains ◽  
Protein Channels ◽  
Synthetic Water

Abstract Nature has protein channels (e.g., aquaporins) that preferentially transport water molecules while rejecting even the smallest hydrated ions. Aspirations to create robust synthetic counterparts have led to the development of a few one-dimensional channels. However, replicating the performance of the protein channels in these synthetic water channels remains a challenge. In addition, the dimensionality of the synthetic water channels also imposes engineering difficulties to align them in membranes. Here we show that zero-dimensional porous organic cages (POCs) with nanoscale pores can effectively reject small cations and anions while allowing fast water permeation (ca. 109 water molecules per second) on the same magnitude as that of aquaporins. Water molecules are found to preferentially flow in single-file, branched chains within the POCs. This work widens the choice of water channel morphologies for water desalination applications.

scholarly journals Water transport through epoxy-based powder pipeline coatings

2021 ◽  
Author(s):  
Hossein Zargarnezhad ◽  
Edouard Asselin ◽  
Dennis Wong ◽  
C.N. Catherine Lam
Keyword(s):  
Water Transport ◽  
Powder Coating ◽  
Operating Conditions ◽  
Vapor Transport ◽  
Internal Stresses ◽  
Water Molecules ◽  
Epoxy Coatings ◽  
Water Permeation ◽  
Vapor Permeation ◽  
Self Association

Hydration of epoxy coatings reduces adhesion performance and causes degradation of the material, such as microstructural failures. Quantification of water vapor transport at elevated temperatures is fundamental to understanding polymer coating performance, especially when the coating is exposed to extreme operating conditions. As the water activity increases, the permeability/selectivity of polymers against other permeants changes. In this study, we examined the water permeation kinetics of two common epoxy-based powder coating systems for pipelines (fusion-bonded epoxy, FBE, and high-performance powder coating, HPPC) across a range of industrially-relevant temperatures (from room temperature to 80°C). Specifically, we utilized vapor permeation features of FBE and HPPC films with quantification of equilibrium flux as a function of temperature and pressure. In addition, we analyzed the nonlinear dependency of water transport on the vapor concentration at 65°C. The vapor transport analysis demonstrated that although data for FBE were indicative of a decrease in permeability around 65°C, perhaps due to self-association of water molecules, the coating was likely to experience a plasticization pressure around this temperature. We also examined microstructural changes of the epoxy network due to water transport. Our results revealed evidence of irreversible damage to epoxy coatings under wet-state conditions above 65°C. It appears that the combination of thermal exposure and internal stresses in the glassy epoxy lead to a phase separation of filler particles from the epoxy matrix, as well as to a distinctive cavity formation in the coating membrane. Yet, despite formation of percolating paths for water transport, our results indicate that vapor permeation is primarily restrained due to self-association of water molecules. The vapor transport flux and its permeance are lowered by one order of magnitude in the multilayered HPPC thanks to the moisture-resistant polyethylene topcoat, thus reducing the extent of damage to the underlying substrate. Since barrier protection against gas phase diffusion is controlled by the FBE primer, however, consequences of coating hydration are more pronounced in the overall selectivity toward gaseous transport. Hydrothermal exposure is likely to increase aggregate porosity of the coating and a conservative implementation of standard coating requirements is therefore reasonable to avoid early degradation issues.

scholarly journals Aluminosilicate Nanotubes Embedded Polyamide Thin Film Nanocomposite Forward Osmosis Membranes with Simultaneous Enhancement of Water Permeability and Selectivity

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 879 ◽  
Author(s):  
She-Ji Shi ◽  
Ye-Han Pan ◽  
Shao-Fei Wang ◽  
Zheng-Wei Dai ◽  
Lin Gu ◽  
...  
Keyword(s):  
Thin Film ◽  
Water Permeability ◽  
Structural Parameters ◽  
High Surface ◽  
Forward Osmosis ◽  
Chloride Ions ◽  
Water Molecules ◽  
Broad Leaf ◽  
Tfc Membrane ◽  
Thin Film Nanocomposite

Nanocomposite membranes are strongly desired to break a trade-off between permeability and selectivity. This work reports new thin film nanocomposite (TFN) forward osmosis (FO) membranes by embedding aluminosilicate nanotubes (ANTs) into a polyamide (PA) rejection layer. The surface morphology and structure of the TFN FO membranes were carefully characterized by FTIR, XPS, FESEM and AFM. The ANTs incorporated PA rejection layers exhibited many open and broad “leaf-like” folds with “ridge-and-valley” structures, high surface roughness and relatively low cross-linking degree. Compared with thin film composite (TFC) membrane without ANTs, the TFN membrane with only 0.2 w/v% ANTs loading presented significantly improved FO water permeability, selectivity and reduced structural parameters. This promising performance can be mainly contributed to the special ANTs embedded PA rejection layer, where water molecules preferentially transport through the nanochannels of ANTs. Molecular dynamic simulation further proved that water molecules have much larger flux through the nanotubes of ANTs than sodium and chloride ions, which are attributed to the intrinsic hydrophilicity of ANTs and low external force for water transport. This work shows that these TFN FO membranes with ANTs decorated PA layer are promising in desalination applications due to their simultaneously enhanced permeability and selectivity.

scholarly journals Aquaporin-4–dependent K+ and water transport modeled in brain extracellular space following neuroexcitation

2012 ◽  
Vol 141 (1) ◽  
pp. 119-132 ◽  
Author(s):  
Byung-Ju Jin ◽  
Hua Zhang ◽  
Devin K. Binder ◽  
A.S. Verkman
Keyword(s):  
Water Transport ◽  
Water Permeability ◽  
Extracellular Space ◽  
Water Channel ◽  
Aquaporin 4 ◽  
Solute Diffusion ◽  
Water Transport Properties ◽  
And Diffusion ◽  
K Permeability ◽  
Brain Extracellular Space

Potassium (K+) ions released into brain extracellular space (ECS) during neuroexcitation are efficiently taken up by astrocytes. Deletion of astrocyte water channel aquaporin-4 (AQP4) in mice alters neuroexcitation by reducing ECS [K+] accumulation and slowing K+ reuptake. These effects could involve AQP4-dependent: (a) K+ permeability, (b) resting ECS volume, (c) ECS contraction during K+ reuptake, and (d) diffusion-limited water/K+ transport coupling. To investigate the role of these mechanisms, we compared experimental data to predictions of a model of K+ and water uptake into astrocytes after neuronal release of K+ into the ECS. The model computed the kinetics of ECS [K+] and volume, with input parameters including initial ECS volume, astrocyte K+ conductance and water permeability, and diffusion in astrocyte cytoplasm. Numerical methods were developed to compute transport and diffusion for a nonstationary astrocyte–ECS interface. The modeling showed that mechanisms b–d, together, can predict experimentally observed impairment in K+ reuptake from the ECS in AQP4 deficiency, as well as altered K+ accumulation in the ECS after neuroexcitation, provided that astrocyte water permeability is sufficiently reduced in AQP4 deficiency and that solute diffusion in astrocyte cytoplasm is sufficiently low. The modeling thus provides a potential explanation for AQP4-dependent K+/water coupling in the ECS without requiring AQP4-dependent astrocyte K+ permeability. Our model links the physical and ion/water transport properties of brain cells with the dynamics of neuroexcitation, and supports the conclusion that reduced AQP4-dependent water transport is responsible for defective neuroexcitation in AQP4 deficiency.

Enhancing Water Permeability with Super-hydrophilic Metal-Organic Frameworks and Hydrophobic Straight Pores

2021 ◽  
Author(s):  
Mehdi Habibollahzadeh ◽  
Juran Noh ◽  
Liang Feng ◽  
Hong-Cai Zhou ◽  
Ahmed Abdel-Wahab ◽  
...  
Keyword(s):  
Osmotic Pressure ◽  
Water Permeability ◽  
Metal Organic Frameworks ◽  
Water Flux ◽  
Forward Osmosis ◽  
High Water ◽  
Metal Organic

High water flux and salt selectivity have been the most demanding goals for osmosis-based membranes. Osmotic pressure differences across membranes are particularly important in emerging forward osmosis and pressure retarded...

Sign in / Sign up

Export Citation Format

Share Document