Rate Of Water Transport Research Articles

Effect of supplemental lighting on water transport, photosynthetic carbon gain and water use efficiency in greenhouse tomato

Despite supplemental lighting is being increasingly applied in greenhouses to improve crop productivity, there have been few studies investigated effects of supplemental lighting on water movement, water consumption and water use efficiency. To examine the potentials to improve water use efficiency via supplemental lighting, photosynthetic productivity versus water movement under contrasting light treatments was investigated in greenhouse tomato (Solanum lycopersicum L.). In the present study, supplemental lighting by light-emitting diodes (LED) facilitated uniform light distributions along vertical profile canopy. The homogeneous light condition increased stomatal and mesophyll conductance for photosynthetic CO2 uptake, especially at the bottom canopy. Consequently, leaf photosynthetic capacity for carbon acquisition and assimilation was overall improved by supplemental lighting. The improvement in leaf photosynthetic capacity was more pronounced with the increased depth down the vertical profile canopy. Both shoot dry biomass and fresh fruit yield were significantly increased by supplemental lighting. Supplemental lighting by LED altered light condition solely and had no significant effect on the distribution of the water driving force along soil-plant-atmospheric continuum, water transport rate and plant water consumption. Taken together, supplemental lighting maximized photosynthetic productivity and consequently significantly increased water use efficiency, whether based of shoot dry biomass and fresh fruit yield, by 10.2% and 8.7%, respectively. Therefore, we concluded that supplemental lighting by LED is an efficient solution to improve greenhouse crop water use efficiency. The present study provides novel information improving water use efficiency without alterning water consumption for sustainable greenhouse production.

Gluten-Free Bread with Cricket Powder-Mechanical Properties and Molecular Water Dynamics in Dough and Ready Product.

Published data indicate that cricket powder (CP) is a good source of not only protein, fat and fiber, but also minerals. Due to the fact that this product naturally does not contain gluten, it is an interesting addition to the enrichment of gluten-free foods. This paper is a report on the results of starch substitution with CP (at 2%, 6% and 10%) on the properties of dough and bread. The rheology of dough and the texture of the final product were studied. While the changes caused in the dough by the introduction of CP were not pronounced, the bread obtained from it was characterized by significantly increased hardness and improved consistency. Analyses of water behavior at the molecular level with the use of 1H Nuclear Magnetic Resonance (NMR) indicated that CP altered both the bound and bulk water fractions. Moreover, examination of water activity revealed a decreased rate of water transport in samples of bread that contained CP. These results indicate improved availability of water to the biopolymers of bread, which likely plays a role in shaping the textural properties of the product.

Microstructure and Transport Analyses in Polymer Electrolyte Membrane Fuel Cells: Comparing Modeling Approaches

Despite the recent entrance of proton exchange membrane fuel cells (PEMFC) into the automotive industry, performance under low platinum loading is still hampered by prohibitive and poorly understood transport losses inside the heterogeneous catalyst layer (CL). Predictive models do not yet sufficiently capture the transport of oxygen, water, and protons in the CL ionomer phase, due to the complexity of the CL microstructure. These transport rates are highly dependent on the substrate, film thickness, and relative humidity. Confinement effects limit water uptake and transport rates below roughly 100 nm thickness, and substrate effects can induce ionomer structures (i.e. lamellae) that further impact transport rates. Implementing these complexities into computational models allows for the microstructural and transport effects on PEMFC performance to be studied and better understood, especially in devices with low platinum loading. Research presented here examines two pseudo-2d, Newman-type model approaches for examining microstructure and transport in PEMFC functional layers: particle-shell and flooded-agglomerate. Figures 1 and 2 show the differences in model domains for these two approaches, respectively. The particle-shell approach approximates a physically realistic structure by simulating a carbon particle at the center of a thin shell of Nafion. This thin shell is discretized to resolve the complex transport that takes place within it. At each vertical discretization, a single Nafion-wrapped carbon particle is taken to be representative of others at that same functional layer depth. The flooded-agglomerate model also simulates a representative spherical domain for each vertical discretization; however, the domain is made up of a cluster of Nafion-wrapped carbon particles enclosed in an additional layer of electrolyte. The models predict cell polarization to examine the effect of CL microstructure as a function of RH- and thickness-dependent transport properties. Figure 3 shows an example overpotential curve from the flooded-agglomerate model in which interesting behavior can be seen with respect to the Nafion thickness. It shows that the CL overpotentials decrease with decreasing ionomer thickness down to 7 nm. Below 7 nm thickness, decreased proton conductivity limits transport, leading to increasing overpotentials at higher currents. The trends indicate that the balance between proton and oxygen transport rates in the CL Nafion can lead to possible trade-offs in optimizing CL design. These and other results will be presented and discussed, to demonstrate the coupled impacts of Nafion thickness and transport on PEMFC performance, and the impact of modeling approach on CL microstructure design. Keywords – Nafion, Transport, PEM, Fuel Cell, Modeling, Electrochemistry, Flooded Agglomerate Figure 1

Changes in the Expression of Aquaporin-3 in the Gastrointestinal Tract Affect Drug Absorption.

Aquaporin-3 (AQP3) plays an important role in water transport in the gastrointestinal (GI) tract. In this study, we conducted a Caco-2 cell permeability assay to examine how changes in the expression and function of AQP3 affect the rate at which a drug is absorbed via passive transport in the GI tract. When the function of AQP3 was inhibited by mercuric chloride or phloretin, there was no change in warfarin permeability. In contrast, when the expression of AQP3 protein was decreased by prostaglandin E2 (PGE2) treatment, warfarin permeability increased to approximately twice the control level, and membrane fluidity increased by 15%. In addition, warfarin permeability increased to an extent comparable to that after PGE2 treatment when cell membrane fluidity was increased by 10% via boric acid/EDTA treatment. These findings suggest the possibility that the increased drug absorption under decreased AQP3 expression was attributable to increased membrane fluidity. The results of this study demonstrate that the rate of water transport has little effect on drug absorption. However, our findings also indicate that although AQP3 and other similar transmembrane proteins do not themselves transport drugs, changes in their expression levels can cause changes in cell membrane fluidity, thus affecting drug absorption rates.

Feasibility Investigation of Improving the Modified Green–Ampt Model for Treatment of Horizontal Infiltration in Soil

Water infiltration in soil is a complex process that still requires appreciation of interactions among three phases (soil particles, water and air) to enable accurate estimation of water transport rates. To simulate this process, the Green–Ampt (GA) model and the Modified Green-Ampt (MGA) model introduced in the paper “A new method to estimate soil water infiltration based on a modified Green–Ampt model” have been widely used. The GA model is based on the hypothesis that the advance of the wetting front in soil under matric suction can be treated as a rectangular piston flow that is instantaneously transformed after passage of the infiltration front, and the MGA model does not contain the influence of pore size change. This cannot accurately reflect the soil moisture change process from unsaturation to saturation. Due to soil stratification and other inhomogeneity, predictions produced with these models often differ widely from observations. To quickly obtain the soil moisture distribution after passage of the wetting front for horizontal infiltration, an improved modified Green–Ampt (IMGA) model is presented, which estimates the soil moisture profile along a horizontal column in a piecewise manner with three functions. A logarithmic function is used to describe the gradual soil saturation process in the transmission zone, and two linear functions are used to represent the wetting zone. The algorithm of the IMGA model for estimating the water infiltration rate and cumulative infiltration is configured. To verify the effectiveness of IMGA model, a lab model test was performed, and a numerical model was built to solve the horizontal one-dimensional Richards equation using the finite–element method. The results show that the IMGA model is more accurate than the GA and MGA models. The horizontal soil moisture profiles obtained by the IMGA model are closer to the measured data than the numerical simulation results. The relative errors of the MGA and IMGA models decrease with an increase in infiltration time, whereas that of the GA model first decreases and then increases with infiltration time. The primary novelty of this study is nonlinear description of soil moisture content distribution, and derivation of unit transfer coefficient.

Mathematical modeling of the process of water-soline transport in soils

A problem related to the actual problem of the process of water and salt transport in soil is solved in the paper; the review of scientific papers devoted to various aspects and mathematical support of the object under research is given. A mathematical model is proposed in the paper to carry out a complex study, taking into account: the colmatage of soil pores with finely dispersed particles with time; the changes in soil permeability coefficient, fluid loss and filtration coefficient; the changes in the initial porosity and settled mass porosity and an effective numerical algorithm based on the Samarsky-Fryazinov vector scheme with the second order approximation where the differential operators in equations are substituted by finite-difference ones. For the derivation of mathematical model of salt transport it is assumed in the paper that the pressure gradient in the canal is constant and equal to atmospheric pressure. The results of calculations on the proposed algorithms are presented in the form of graphs; a detailed analysis of these results is given. At the end of the paper, conclusions are drawn related to the analysis of numerical computer calculations. It is established that with scarce irrigation, the maximum absorption of water and the accumulated salt transport occurs in the upper layers of soil. Numerical calculations have established that changes in the rate of water transport in soil depend on: porosity, soil permeability, filtration coefficient, composition and structure of soil, and the porosity of settled mass. The process of salinity has reached equilibrium after the use in irrigation of salt water for several years.

Quantifying water transport in anion exchange membrane fuel cells

Sufficient water transport through the membrane is necessary for a well-performing anion exchange membrane fuel cell (AEMFC). In this study, the water flux through a membrane electrode assembly (MEA), using a Tokuyama A201 membrane, is quantified using humidity sensors at the in- and outlet on both sides of the MEA. Experiments performed in humidified inert gas at both sides of the MEA or with liquid water at one side shows that the aggregation state of water has a large impact on the transport properties. The water fluxes are shown to be approximately three times larger for a membrane in contact with liquid water compared to vaporous. Further, the flux during fuel cell operation is investigated and shows that the transport rate of water in the membrane is affected by an applied current. The water vapor content increases on both the anode and cathode side of the AEMFC for all investigated current densities. Through modeling, an apparent water drag coefficient is determined to −0.64, indicating that the current-induced transport of water occurs in the opposite direction to the transport of hydroxide ions. These results implicate that flooding, on one or both electrodes, is a larger concern than dry-out in an AEMFC.

Single-channel permeability and glycerol affinity of human aquaglyceroporin AQP3

For its fundamental relevance, transport of water and glycerol across the erythrocyte membrane has long been investigated before and after the discovery of aquaporins (AQPs), the membrane proteins responsible for water and glycerol transport. AQP1 is abundantly expressed in the human erythrocyte for maintaining its hydrohomeostasis where AQP3 is also expressed (at a level ~30-folds lower than AQP1) facilitating glycerol transport. This research is focused on two of the remaining questions: How permeable is AQP3 to water? What is the glycerol-AQP3 affinity under near-physiological conditions? Through atomistic modelling and large-scale simulations, we found that AQP3 is two to three times more permeable to water than AQP1 and that the glycerol-AQP3 affinity is approximately 500/M. Using these computed values along with the data from the latest literature on AQP1 and on erythrocyte proteomics, we estimated the water and glycerol transport rates across the membrane of an entire erythrocyte. We used these rates to predict the time courses of erythrocyte swelling-shrinking in response to inward and outward osmotic gradients. Experimentally, we monitored the time course of human erythrocytes when subject to an osmotic or glycerol gradient with light scattering in a stopped-flow spectrometer. We observed close agreement between the experimentally measured and the computationally predicted time courses of erythrocytes, which corroborated our computational conclusions on the AQP3 water-permeability and the glycerol-AQP3 affinity.

Performance of multi-decadal ocean simulations in the Adriatic Sea

A performance study of seven regional ocean configurations based on NEMO has been carried out for the Adriatic Sea over a common period (1980–2012). Assessed models differ in resolution, model physics, atmospheric forcing (forced vs. coupled models) and river discharges imposed within the Adriatic Sea. Models have been evaluated on the long-term temperature and salinity measurements in all of the Adriatic sub-basins, in particular within dense water collectors (Jabuka Pit and South Adriatic Pit) and dense water formation sites (northern and southern Adriatic). Adriatic-wide salinity content is mostly linked to the proper introduction of the overall water budget, rather than to the local river forcing. Forced models mostly overestimate temperature and salinity values. On average, coupled models better reproduce the thermohaline properties and processes, in particular the Adriatic-Ionian Bimodal Oscillating System (BiOS) reversals and its decadal variability. Wintertime heat losses are playing major role in defining the Adriatic Deep Water (ADW) transport rates in coupled models, while in forced models preconditioning in salinity is the most important factor. Further on, increase of resolution of the atmospheric forcing results in more realistic ocean behaviour, including dense water formation (DWF) in the complex coastal northern Adriatic. However, all models have large temperature biases and lower deep stratification at the dense water collector sites, indicating overall underrepresentation of the Adriatic DWF. Consequently, mixed-layer depth in the southern Adriatic is overestimated, reaching the bottom during some years. Ocean model resolution and river forcing seem to play a second-order role in defining the overall Adriatic-Ionian thermohaline properties, while inclusion of aerosol trend only slightly modified the BiOS reproduction.

Localized Nanoscale Heating Leads to Ultrafast Hydrogel Volume-Phase Transition.

The rate of the volume-phase transition for stimuli-responsive hydrogel particles ranging in size from millimeters to nanometers is limited by the rate of water transport, which is proportional to the surface area of the particle. Here, we hypothesized that the rate of volume-phase transition could be accelerated if the stimulus is geometrically controlled from the inside out, thus facilitating outward water ejection. To test this concept, we applied transient absorption spectroscopy, laser temperature-jump spectroscopy, and finite-element analysis modeling to characterize the dynamics of the volume-phase transition of hydrogel particles with a gold nanorod core. Our results demonstrate that the nanoscale heating of the hydrogel particle core led to an ultrafast, 60 ns particle collapse, which is 2-3 orders of magnitude faster than the response generated from conventional heating. This is the fastest recorded response time of a hydrogel material, thus opening potential applications for such stimuli-responsive materials.

A New Perspective for Assessing Water Transport and Associated Retention Effects in a Large Reservoir

AbstractRadioactive tracer techniques may be useful for assessing water transport and the overall effects of concurrent biogeochemical processes in river‐reservoir systems. In this study, we show that radium isotopes can assess the hydrodynamics and sediment/nutrient retention in the Xiaolangdi Reservoir, the largest impoundment along the Yellow River, China. Activity ratios of 224Ra/226Ra and 223Ra/226Ra were used for water mass age calculations in the riverine, transition, and lentic reaches of the reservoir. Water ages were combined with the length scale of three river‐reservoir zones to determine water transport rates of 3.6 ± 1.2, 1.3 ± 0.3, and 0.16 ± 0.14 km/day, respectively. Radium ages were also used to quantify the net retention of sediment and nutrients in different parts of the river‐reservoir system. Suspended sediment was removed at a rate of 1.4 ± 0.6 g/m3/day, mainly in the riverine zone. Nutrient dynamics were more complicated, with addition or removal at different rates within the three zones.

Electrodialysis-based desalination and reuse of sea and brackish polymer-flooding produced water

The reuse of polymer flooding produced water (PFPW) generated in oil and gas industry is limited by its salt content, making desalination by electrodialysis a promising treatment option. Therefore, this study aimed to 1) assess the technical feasibility of employing electrodialysis to desalinate PFPW generated in assorted scenarios, and 2) evaluate the reuse of the electrodialysis-desalted water to confect polymer-flooding solution. The experimental work involved desalting two kinds of synthetic PFPW solutions, one with relatively low salinity (TDS = 5000 mg/L, brackish PFPW), and another with high salinity (TDS = 32,000 mg/L, sea PFPW), at two different temperatures, and later reusing the desalted solution to prepare viscous solutions. For the electrodialysis runs, the effects of feed composition and temperature on water transport, energy consumption and current efficiency were analyzed. It was found that the presence of polymer did not significantly influence the water transport rate or the specific energy consumption for the seawater cases, but had a measurable effect when desalting brackish water at 20 °C. It was also found that some polymer remained in the stack, the loss occurring faster for the brackish PFPW. Still, both kinds of reused PFPW probed adequate to be employed as a basis for preparing n polymer solution.

Spatially resolved observation of water transport across nanomembranes using bright-field nanoscopy

Gaining a detailed understanding of water transport behavior through ultra-thin membranes including atomically thin graphene layers is increasingly becoming necessary due to their potential applications in water desalination and ion separation. It is important to correlate the nanoscopic architecture of the membrane with the macroscopic properties such as the average water transport rate and the ion selective transport rates. Such correlations are only possible when spatially resolved (in the lateral direction) information of mass transport across the membrane is available. Then, one will be able to identify the relative role of grain boundaries, defects, and other topographical structures of interest in determining the macroscopic parameters which will aid in optimizing the fabrication processes of such membranes. Current techniques do not provide spatially resolved information and only provide macroscopic parameters such as the bulk water transport rate. We describe a technique, referred to here as Bright-Field Nanoscopy (BFN), which provides a spatially resolved measurement of water transport across nanomembranes. Using this technique, we demonstrate how grain engineering of atomically thin chemical vapor deposited graphene membranes can tune the bulk water transport rate across the membranes by orders of magnitude. BFN exploits the strong thickness dependent color response of an optical stack consisting of a thin (∼25 nm) germanium film deposited over a gold substrate and only requires a regular bright-field microscope for data acquisition. To show the generality of this technique, we demonstrate the strong influence of the terminal layer on the bulk water transport rates in thin (∼20 nm) layer-by-layer deposited polyelectrolyte multilayer films by exploiting the spatially resolved nature of the acquired data. We also show that by controlling the ambient conditions, the effect of the terminal layer can be completely suppressed.

Transport Rate of Liquid Water and Saturated Water Vapors across Polymer Proton-Exchange Membranes

Dependences of the transport rate of liquid water and saturated water vapor across commercial membranes (Nafion, MF-4SK) and proton-exchange membranes synthesized by the authors (PVDF, PP, UHMWPE, PTFE films modified with sulfonated polystyrene) on the membrane thickness have been studied. It has been found that at room temperature (17–25°C), the transport rate of liquid water and saturated water vapor across the membranes into an air stream hardly depends on the membrane type and thickness (60–240 μm), with the transport rate of saturated vapor being almost an order of magnitude below that of liquid water contacting one of the membrane surfaces. The fact that the flux of water and water vapor across the membrane does not depend on membrane thickness under conditions of maximum moistening suggests that the flow resistance is determined by the resistance at the feed and permeate interfaces. If one of the membrane surfaces is in contact with liquid water, the transport rate is equal to the rate of water removal from the permeate surface of the membrane; in the case of contact with saturated vapor, the transport rate is determined by the rate of water sorption from the vapor phase by the membrane. The results can be used to optimize the operation of fuel cells based on polymer proton-exchange membranes.

Response to Comment on "Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins".

Horner and Pohl argue that high water transport rates reported for carbon nanotube porins (CNTPs) originate from leakage at the nanotube-bilayer interface. Our results and new experimental evidence are consistent with transport through the nanotube pores and rule out a defect-mediated transport mechanism. Mechanistic origins of the high Arrhenius factor that we reported for narrow CNTPs at pH 8 require further investigation.

Water Transport through Ultrathin Polyamide Nanofilms Used for Reverse Osmosis.

Thin-film composite membranes comprising a polyamide nanofilm separating layer on a support material are state of the art for desalination by reverse osmosis. Nanofilm thickness is thought to determine the rate of water transport through the membranes; although due to the fast and relatively uncontrolled interfacial polymerization reaction employed to form these nanofilms, they are typically crumpled and the separating layer is reported to be ≈50-200 nm thick. This crumpled structure has confounded exploration of the independent effects of thickness, permeation mechanism, and the support material. Herein, smooth sub-8 nm polyamide nanofilms are fabricated at a free aqueous-organic interface, exhibiting chemical homogeneity at both aqueous and organic facing surfaces. Transfer of these ultrathin nanofilms onto porous supports provides fast water transport through the resulting nanofilm composite membranes. Manipulating the intrinsic nanofilm thickness from ≈15 down to 8 nm reveals that water permeance increases proportionally with the thickness decrease, after which it increases nonlinearly to 2.7 L m-2 h-1 bar-1 as the thickness is further reduced to ≈6 nm.

Macroporous temperature‐sensitive gels with fast response: Comparison of preparation methods

ABSTRACTApplication of thermo‐responsive gels as soft actuators for microfluidic devices with repeating “open–close” cycles requires high rates of water transport driven by changes in temperature. These rates are conventionally evaluated by comparison of water retention curves in T‐jump tests with fixed initial and final temperatures. A shortcoming of this method is that it does not allow changes in diffusivity with temperature to be assessed quantitatively. To characterize cooperative diffusivity of water molecules, we propose a novel approach based on modeling the responses of temperature‐sensitive gels in equilibrium swelling tests and T‐jump experiments. Analysis of observations on poly(N‐isopropylacrylamide) gels synthesized in aqueous solutions of pore‐forming agents reveals that formation of a macroporous structure in a gel is a necessary, but not sufficient condition for acceleration of water transport. The effect of cosolvents used under preparation (phenol, ethanol, methanol, diethyl ether, dioxane, sucrose, and dodecyl dimethyl benzyl ammonium bromide) on water diffusivity is studied in detail. It is shown that the most pronounced enhancement of diffusivities under deswelling and reswelling is reached when the gels are synthesized in aqueous solutions of the surfactant at subzero temperatures. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46353.

Synthesis and characterization of mixed matrix membranes incorporated with hydrous manganese oxide nanoparticles for highly concentrated oily solution treatment

AbstractIn this work, ultrafiltration (UF) mixed matrix membranes (MMMs) incorporated with hydrophilic hydrous manganese oxide (HMO) nanoparticles were synthesized and used for the treatment process of a highly concentrated oily solution. The MMMs were fabricated via a phase inversion process and were characterized with respect to physiochemical properties and filtration performances. The results showed that the MMMs demonstrated higher water flux and better oil rejection rates compared to the control membrane (without HMO incorporation) when tested at three different oily solutions with oil concentration in the range of 5000–15 000 ppm. The membrane incorporated with the highest amount of HMO (labelled as MMM‐2) in particular showed the best results even when subjected to 15 000 ppm oily solution filtration, recording water flux of 32.2 L/m2 · h · bar and oil rejection of 82 %. The enhanced performance can be attributed to improved surface hydrophilicity coupled with better structural integrity and higher porosity that contributed to lower degree of oil molecules deposition and greater water transport rate. It was also reported that with the use of a feed spacer during the filtration process, the degree of flux deterioration of MMMs could be further reduced without compromising rejection. The findings of this work indicated the potential of MMMs for the treatment of highly concentrated oily effluent produced from industries, by producing permeate of high quality at reasonably good water permeability.

Fuel Cell Catalyst Layers and Membrane-Electrode Assemblies Containing Multiblock Poly(arylene ether sulfones) Bearing Perfluorosulfonic Acid Side Chains

A sulfonated poly(arylene ether sulfone) multiblock copolymer bearing perfluorosulfonic acid side chains has been studied as both the membrane and cathode catalyst layer ionomer in fuel cell membrane-electrode assemblies. The multi-block, hydrocarbon-backbone polymer was designed to possess good conductivity with low ion exchange capacity and low water sorption to mimic perfluorosulfonic acid ionomers, but without the synthetic difficulty. A H2/O2-fuel cell power density of 1080 mW·cm−2 was achieved at 80°C, 100% RH using membrane-electrode assemblies incorporating the sulfonated poly(arylene ether sulfone) membrane and traditional PFSA ionomer in the catalyst layer. An accelerated stress test using 30% RH, 90°C, H2/Air demonstrated durability to open circuit potentials of more than 400 h, which is 4 times longer than for Nafion 211. No membrane thinning was observed over the same period, which is attributed to low gas crossover and inhibition of membrane degradation reactions, despite the rate of water transport across the membrane remaining high. Cathode catalyst layers fabricated using 20 wt% sulfonated poly(arylene ether sulfone) as the ionomer exhibited comparable power densities to benchmark PFSA MEAs, under high current densities, over a wide range of operational relative humidities, demonstrating that hydrocarbon-backbone, solid polymer electrolytes hold technological promise as both the membrane and catalyst layer ionomer in fuel cell membrane-electrode-assemblies.

Impact of PEG additives and pore rim functionalization on water transport through sub-1nm carbon nanotube porins.

Carbon nanotubes represent one of the most interesting examples of a nanofluidic channel that combines extremely small diameters with atomically smooth walls and well-defined chemical functionalities at the pore entrance. In the past, sub-1 nm diameter carbon nanotube porins (CNTPs) embedded in a lipid membrane matrix demonstrated extremely high water permeabilities and strong ion selectivities. In this work, we explore additional factors that can influence transport in these channels. Specifically, we use stopped-flow transport measurements to focus on the effect of chemical modifications of the CNT rims and chaotropic polyethyleneglycol (PEG) additives on CNTP water permeability and Arrhenius activation energy barriers for water transport. We show that PEG, especially in its more chaotropic coiled configuration, enhances the water transport and reduces the associated activation energy. Removal of the static charges on the CNTP rim by converting -COOH groups to neutral methylamide groups also reduces the activation energy barriers and enhances water transport rates.