Water Channel Network Research Articles

Structural properties of conductive polymer blends interfaced with water: computational insights from PEDOT:PSS.

In various bioelectronic applications, conductive polymers come into contact with biological tissues, where water is the major component. In this study, we investigated the interface between the conductive polymer poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and water, focusing on how the morphology of the PEDOT:PSS is altered by water permeation. We constructed well-equilibrated PEDOT:PSS-water systems in both PEDOT- and PSS-rich phases. Our findings show that water permeates into the polymer through a complex network of water channels, which exhibit a similar pore size distribution in both PEDOT- and PSS-rich phases, leading to similar water intake in these phases. Compared to the dry state of the polymer, water permeation leads to the formation of smaller, less ordered, and distantly located lamella crystallites, potentially resulting in reduced conductivity. Therefore, we argue that these structural changes from the dry state of the polymer to the wet state may be the origin of the significant conductivity reduction observed experimentally in PEDOT:PSS in water or PEDOT:PSS hydrogels.

Managing a cyanobacteria harmful algae bloom “hotspot” in the Sacramento – San Joaquin Delta, California

Cyanobacterial harmful algal blooms (CHABs) have become a persistent seasonal problem in the upper San Francisco Estuary, California also known as the Sacramento-San Joaquin Delta (Delta). The Delta is comprised of a complex network of open water bodies, channels, and sloughs. The terminus of the Stockton Channel is an area identified as a CHAB “hotspot.” As CHABs increase in severity, there is an urgent need to better understand CHAB drivers to identify and implement mitigation measures that can be used in an estuarine complex like the Delta. We investigated water quality conditions and nutrient dynamics in the Stockton Channel by measuring nutrients in the water column, sediments, and pore waters. In situ nutrient addition bioassay experiments were used to assess the effects of nutrient enrichment on total algal/cyanobacterial growth and pigment concentrations. In both June and September, relative to unamended controls, total chlorophyll and cyanobacterial pigment concentrations were unaffected by nutrient additions; hence, the study area showed signs of classical hypereutrophication, with ambient nitrogen and phosphorus present in excess of algal growth requirements. A cyanobacterial bloom, dominated by Microcystis spp. was present throughout the study area but was most severe and persistent at the shallowest site at the channel terminus. At this site, Microcystis spp. created water quality conditions that allowed for a prolonged bloom from June through September. While targeted nutrient reductions are recommended for long term mitigation, on a shorter timescale, our findings suggest that physical/mechanical controls are the more promising alternative approaches to reduce the severity of CHABs in the terminus of the Stockton Channel.

OR03-06 Transmembrane Water Channels Within The Tsh Receptor

Abstract Disclosure: R. Latif: None. T.F. Davies: Advisory Board Member; Self; Board of Kronus Inc (Starr, ID, USA);. M. Mezei: None. Using our recently reported hydrated model of the TSH receptor transmembrane (TM) region (Endocrinology 2021,162:7;1-12), we have now identified a network of putative TM water channels within this structure. By analyzing the molecular simulation trajectory for water molecules crossing the plasma membrane embedded TSHR we found evidence of putative water channels suggestive of active transport. To ascertain the biological activity of such TSHR channels we examined the movement of water down osmotic gradients using calcein aceto-oxymethyl ester (Calcein-AM) fluorescence in rat thyrocyte cells (FRTL5). Calcein-AM is a membrane permeant fluorescent dye that is quenched in a concentration-dependent manner and is, therefore, an effective probe of cell volume changes that would result from water movement across the cell membrane. Since thyroid cells are known to contain aquaporin (AQP) channels, principally AQP4, we first blocked these channels (using 3μM of TGN020) prior to examining the effects of TSHR activation using TSH (10-103 µU/ml), stimulating TSHR monoclonal antibodies (mAbs MS1 and M22 at 10μg/ml and 1μg/ml respectively) and TSHR-specific small molecule allosteric agonists (MS437 and MS438 at 10µM) and measured the changes in fluorescence quenching. D-Mannitol at 400mM was used as the hypertonic medium to induce cell shrinkage measured by continuous fluorescence measurements with read intervals of 50msec. Analyzing the normalized fluorescence of cells treated with TSH in a dose-dependent manner we observed ∼25% quenching with 103 µU/ml of TSH. On blocking the binding of TSH using a TSHR blocking mAb K1-70 (1μg/ml), we found marked de-quenching. Furthermore, using equimolar concentrations of stimulating TSHR antibodies the quenching was even more significantly enhanced to 54-60%. These data suggested that ligands that activate the TSHR by binding to the TSHR ectodomain could influence the TM water transport. However, using the allosteric activators, which act at the TM, we also showed similar changes indicating this was not ectodomain dependent. These data confirm the presence of the modeled putative TSHR water channels indicating that TSH and TSHR autoantibodies have an important role in regulating TM water passage. Presentation: Thursday, June 15, 2023

The ‘Deluge’ of 25 October 1822 in Genoa, Italy

The ‘Deluge’ of 25 October 1822 in Genoa, Italy

Why we should study protein binding to bicontinuous inverted cubic phases, to better understand membrane trafficking.

Many proteins bind to membranes in a curvature-sensitive manner. This includes some adaptors/effectors in the vesicle budding and fusion stages of membrane trafficking. Recently, others showed that some proteins bind preferentially to membranes with Gaussian curvature: they bind more strongly to spherical vesicles (with positive Gaussian curvature) than to tubules with the same mean curvature but zero local Gaussian curvature. Fusion and fission pores (which are intermediates in vesicle fusion & budding) have special curvature properties. Here I show that the surfaces of such pores have curvature that is qualitatively and quantitatively different than in the membrane systems conventionally used to assess curvature-sensitive protein binding (membrane vesicles and tubules). Hence, existing methods may miss proteins that have evolved to bind to pore-relevant curvatures. However, the curvature properties of bicontinuous inverted cubic (QII) phases are quite similar to those of fusion/fission pores. Specifically, both QII phases and fusion/fission pores have negative Gaussian curvature, which is true of neither vesicles nor tubules; have more negative mean curvature than many tubules; and gradients in mean curvature that are either absent or smaller in vesicles and tubules. QII phases can be equilibrated with peptide through the aqueous phase: it has been shown that proteins with molecular weights of several tens of kDa can enter the water channel networks and penetrate into aggregates of QII phase. Thus, we might find new adaptors/effectors of trafficking by studying peptide or protein binding to preparations of QII phase. Some features of QII phases make such experiments awkward. Only certain ranges of lipid compositions form QII phases, and, in phospholipids, temperature-cycling techniques or particular electrolyte compositions may be needed. Appropriate protocols will be proposed.

The Western Zhou Yaoheyuan site in Pengyang County, Ningxia

Abstract The Ningxia Hui Autonomous Regional Institute of Cultural Relics and Archaeology and Pengyang County Commission for Preservation of Ancient Monuments conducted archaeological investigations, probing surveys, and excavations of the Yaoheyuan site from 2017 to 2020. They identified various features, including city walls, moats, a high-ranking burial, a cemetery of small-sized tombs, palatial foundations, a bronze foundry zone, as well as roads and a network of water channels. Retrieved artifacts include objects made of pottery, jade and stone, bone and antler, ivory, mussel, proto-porcelain, and inscribed oracle bone. The Yaoheyuan site, dating from the early through the late Western Zhou, is the capital city of the Huo state of the Western Zhou. This excavation provides invaluable new data for understanding Western Zhou political structure and the relationship between the Zhou royal house and the western frontier. It also sheds new light on the chronological framework and the trajectory of social complexity in the eastern Gansu region.

Structural investigation and steric stabilisation of Guerbet glycolipid-based cubosomes and hexosomes using triblock polyethylene oxide-polypropylene oxide-polyethylene oxide copolymers

Aqueous dispersions of inverse nonlamellar liquid crystalline nanostructures namely cubosomes and hexosomes have been used as carriers for drug delivery. The large surface area and internal water channel networks in these nanocarriers make them useful to transport amphiphilic, hydrophilic and hydrophobic active ingredients. However, suitable stabilisers that can maintain the colloidal stability and preserving the internal structures of the complex cubosomes and hexosomes are integral. Herein, Guerbet glycolipids namely 2-hexyl-decyl-β-D-glucopyranoside (β-Glc-OC10C6) and 2-hexyl-decyl-β-D-xylopyranoside (β-Xyl-OC10C6) were investigated for their potential in forming cubosomes and hexosomes respectively using Pluronic copolymers as steric stabilisers. The performance of five different Pluronics was evaluated for stabilisation of the dispersions, with a view to establish a structure-property relationship between the lipids and the stabilisers. The dispersions were assessed through synchrotron small-angle X-ray scattering as a function of temperature and the concentration of stabilisers. The internal structure of dispersed particles of β-Glc-OC10C6 was susceptible to changes upon stabilisation by different Pluronics and with increasing temperature. The lowest molecular weight Pluronic studied, L64, had the greatest propensity to disrupt the structure, suggesting that it is able to penetrate the internal structure to a greater degree than the other Pluronic stabilisers. In contrast, the β-Xyl-OC10C6 counterpart formed a stable inverse hexagonal phase structure that was invariant with the Pluronic used or temperature. The stability of the structure of β-Xyl-OC10C6 suggests it has greater potential for use in drug delivery applications and the studies overall extend the current understanding around the structures formed upon dispersion of Guerbet lipids.

Chemical Exchange of Hydroxyl Groups in Lipidic Cubic Phases Characterized by NMR.

Proton transportation in proximity to the lipid bilayer membrane surface, where chemical exchange represents a primary pathway, is of significant interest in many applications including cellular energy turnover underlying ATP synthesis, transmembrane mobility, and transport. Lipidic inverse bicontinuous cubic phases (LCPs) are unique membrane structures formed via the spontaneous self-assembly of certain lipids in an aqueous environment. They feature two networks of water channels, separated by a single lipid bilayer which approximates the geometry of a triply periodic minimal surface. When composed of monoolein, the LCP bilayer features two glycerol hydroxyl groups at the lipid-water interface which undergo exchange with water. Depending on the conditions of the aqueous solution used in the formation of LCPs, both resonances of the glycerol hydroxyl groups may be observed by solution 1H NMR. In this study, PFG-NMR and 1D EXSY were employed to gain insight into chemical exchange between the monoolein hydroxyl groups and water in LCPs. Results including the relative population of hydroxyl protons in exchange with water for a number of LCPs at different hydration levels and the exchange rate constants at 35 wt % hydration are reported. Several technical aspects of PFG-NMR and EXSY-NMR for the characterization of chemical exchange in LCPs are discussed, including an alternative way to analyze PFG-NMR data of exchange systems which overcomes the inherent low sensitivity at high diffusion encoding.

Synthesis of cubic transition-metal networks from polymer cubosome templates.

The interfacial topology of block copolymer cubic mesophases opens only one of two internal water channel networks for diffusion. Utilizing this topology selection, single and double diamond cubic crystalline networks of Ni were synthesized from cubic block copolymer (BCP) mesophase templates via electroless plating, in which the lattice structures were converted to the polymer cubosome (PC) internal pore networks by selective metal-ion diffusion. This was accomplished by manipulating the BCP molecular weight, which consequently allowed for selective access to the PC internal pore networks. This work provides a selective protocol for highly defined transition-metal cubic networks that are suitable for application in catalysis, electrochemistry, and synthesis of metamaterials with photonic and magnetic properties.

Mechanism of Water Content on the Electrochemical Surface Area of the Catalyst Layer in the Proton Exchange Membrane Fuel Cell

Combined molecular dynamics (MD) simulation and experiment are adopted to gain the mechanism of water content on the electrochemical surface area (ECSA) of the catalyst layer in a proton exchange membrane fuel cell. The morphology of water domains in the catalyst layer has a strong impact on the ECSA via MD simulation. The morphology of the water domains is isolated water clusters at low water content, resulting in the poor ECSA due to the lack of proton transport paths. The transport paths of protons tend to be quickly established with increasing water content during the transition process of the morphology of water domains from isolated water clusters to the water channel network, thereby leading to the rapid increase of the ECSA. However, the slight increase of the ECSA at high water content mainly results from the improved contact area between water domains and Pt particle instead of the formation of new transport paths. In addition, the stronger binding of water molecules and the Pt particle at low temperature results in a higher ECSA.

Tide propagation and salinity distribution response to changes in water depth and channel network in the Guadalquivir River Estuary: An exploratory model approach

This study analyzes the management alternatives that are currently considered by public administrations in the Guadalquivir River Estuary, which is a well-mixed and rather channelized estuary in the southwest of Spain. A linearized multichannel exploratory model that operates at tidal and averaged scales is used. The model extends the previous developments for calculating the tidal variations of salinity and provides elevations, currents and salinity. The effects of the change in mean depth of the main navigation channel, the reconnection of a secondary tidal channel (Brazo del Oeste) and the recovery of a marsh in the lower part of the estuary are the three alternatives analyzed. The model outputs indicate that the channel deepening would produce an increase in the amplitudes of the elevations, tidal salinities, and tidal prisms, as well as the extent of the saline intrusion. Similar effects could be alternatively obtained with the reconnection of the secondary channel with suitable design parameters. The increase in tidal elevations due to channel deepening should therefore be considered in any dredging project, because lower sediment volumes need to be dredged to attain the projected water column height at high water. The recovery of marshes notably influences the tidal wave propagation when the connecting width with the navigation channel exceeds one hundred meters. Its most remarkable effect is to increase the tidal amplitudes and to reduce the tidal currents upstream the connection point in proportion to the degree of connectivity with the main channel. A combination of alternatives could potentially serve to mitigate the specific effects of individual alternatives. The effects of channel deepening on the amplitudes of the tidal elevation and the currents could be partially compensated for through the recovery of tidal marshes.

Negative refraction of deep water waves through water channel network

A design method of a negative refractive index for free surface water waves in deep water is presented. To obtain a condition of a negative index, an analogy between water waves in a water channel and electric waves in an electric circuit. An analytical solution of waves around a periodic array of rectangular columns is obtained by a circuit analysis. Attention is not focused on columns but a space among columns, and then the space is regarded as the water channel. Therefore, the circuit analysis can be applied to water waves. One channel is treated as a unit structure and a number of channels are periodically cascaded as a network. The negative refraction and backward waves by a network of the water channels are shown. Since the negative refraction might occur even around simple periodic structures, it is meaningful to understand wave phenomenon around offshore structures and develop innovative technology.

Enhancing hydrophilicity and permeation flux of chitosan/kaolin composite membranes by using polyethylene glycol as porogen

A novel chitosan/kaolin composite membrane with high flux and enhanced hydrophilicity was prepared by solvent casting and evaporation process in the presence of polyethylene glycol (PEG). The characterization of the as-fabricated membranes indicated that the combined effect of kaolin as reinforcing agent and PEG as porogen into a chitosan matrix showed significant influence on the morphology and hydrophilicity. Highly porous membranes with finger-like structure were obtained. Both size and density of the pores increased with increasing the PEG content from 0 to 3 wt%. The incorporation of the hydrophilic polymeric additive constructed a water channel network and increased the free volume within the composite matrix, contributing to the enhanced filtration performance of the resulting membrane. Additionally, their mechanical, thermal and chemical stability showed a large improvement compared to the unmodified one.

Templated synthesis of cubic crystalline single networks having large open-space lattices by polymer cubosomes

The synthesis of biophotonic crystals of insects, cubic crystalline single networks of chitin having large open-space lattices, requires the selective diffusion of monomers into only one of two non-intersecting water-channel networks embedded within the template, ordered smooth endoplasmic reticulum (OSER). Here we show that the topology of the circumferential bilayer of polymer cubosomes (PCs)—polymeric analogues to lipid cubic membranes and complex biological membranes—differentiate between two non-intersecting pore networks embedded in the cubic mesophase by sealing one network at the interface. Consequently, single networks having large lattice parameters (>240 nm) are synthesized by cross-linking of inorganic precursors within the open network of the PCs. Our results pave the way to create triply periodic structures of open-space lattices as photonic crystals and metamaterials without relying on complex multi-step fabrication. Our results also suggest a possible answer for how biophotonic single cubic networks are created, using OSER as templates.

The spatial and temporal distribution of metals in an urban stream: A case study of the Don River in Toronto, Canada

Abstract Widespread growth of cities, the association of trace metals with urban runoff, and the potentially deleterious effect of metals on aquatic ecology have made it important to understand the distribution and transport of metals through surface water channel networks. The Don River in Toronto, Canada has been identified as an Area of Concern for pollution to Lake Ontario, with historically high levels of metal contamination. Sampling programs are sparse, therefore a model is needed to understand the spatial and temporal variability of metals in the river network. The objectives of the current study are to: i) describe the sampled spatial and temporal variability of metals in the Don River and ii) develop a modelling strategy to describe within flood metal transport dynamics. A model setup tool is developed that links Storm Water Management Model (SWMM) with the Environmental Fluid Dynamics Code (EFDC) to allow a seamless transition from catchment hydrology to in-stream hydraulic and chemical processes. Results show that lead pollution in the Don River is decreasing, likely as a result of policy changes and sediment dredging in the mouth of the river. However, zinc and copper pollution are increasingly problematic, with copper exceeding recommended lower guidelines, particularly during floods. Model results confirm that most of the sediment and metals are transported in relatively short bursts within longer flood durations and are stored in depositional hotspots within the Lower Don River. A better monitoring strategy is needed to understand and more accurately parametrize these processes in an urban river system.

Desalination properties of a free-standing, partially oxidized few-layer graphene membrane

Multi-stacked graphene oxide (GO) sheets containing intricate networks of microcapillary water channels are attractive as filtration membranes displaying both ultrahigh water permeation and ion exclusion properties. However, their practical utilization as desalination membranes is hampered by multiple issues, which include scalability, swelling of interlayer space, and mechanical instability under pressure-driven flux. To address these challenges, we have developed a process to laminate GO sheets with acryl binder to form large-area (>1 m2 in lab) free-standing membranes for high-performance desalination. The key to high-performance desalination lies in the control of interlayer spacing in the graphene sheets and the controlled oxidation of graphene. Our results show that the performance of partially oxidized few-layer graphene (POFG) is much better than heavily oxidized GO in forward osmosis (FO) due to its smaller interlayer distance and resistance to swelling. Our acryl-laminated, POFG membrane (79 L/m2/h water flux, 3.4 g/m2/h reverse salt flux) performs at least seven times (with respective to the water flux) and three times (with respective to the reverse salt flux) better than that of commercial cellulose triacetate (CTA) membrane (10 L/m2/h and 12 g/m2/h) in FO.

Small water channel network for designing wave fields in shallow water

A small water channel network is proposed for designing shallow water fields, and the network is applied to attain water wave cloaking. The design formula is derived from an analogy between waves in a water channel and in an electric circuit; an approach of a transmission line metamaterial is extended to water waves and the water channel is used as an alternative of the transmission line. The size of the water channel is sufficiently smaller than the wavelength and a number of the channels are periodically connected as a network. This small water channel network makes artificial wave fields, and it works for a wide band of frequencies. First, we make an isotropic network equivalent to a shallow water space with constant depth in order to validate the proposed design method. It shows no wave reflection at the interface due to impedance matching. After that, the proposed theory is applied to designing an anisotropic small water channel network for demonstrating shallow water cloaking. A cylinder is cloaked from waves by the network surrounding the cylinder. Both cases are confirmed with numerical computations by solving the boundary-value problem based on linear potential theory.

A numerical method for junctions in networks of shallow-water channels

There is growing interest in developing mathematical models and appropriate numerical methods for problems involving networks formed by, essentially, one-dimensional (1D) domains joined by junctions. Examples include hyperbolic equations in networks of gas tubes, water channels and vessel networks for blood and lymph transport in the human circulatory system. A key point in designing numerical methods for such applications is the treatment of junctions, i.e. points at which two or more 1D domains converge and where the flow exhibits multidimensional behaviour. This paper focuses on the design of methods for networks of water channels. Our methods adopt the finite volume approach to make full use of the two-dimensional shallow water equations on the true physical domain, locally at junctions, while solving the usual one-dimensional shallow water equations away from the junctions. In addition to mass conservation, our methods enforce conservation of momentum at junctions; the latter seems to be the missing element in methods currently available. Apart from simplicity and robustness, the salient feature of the proposed methods is their ability to successfully deal with transcritical and supercritical flows at junctions, a property not enjoyed by existing published methodologies. Systematic assessment of the proposed methods for a variety of flow configurations is carried out. The methods are directly applicable to other systems, provided the multidimensional versions of the 1D equations are available.

Enhancement in Proton Conductivity and Thermal Stability in Nafion Membranes Induced by Incorporation of Sulfonated Carbon Nanotubes.

Proton exchange membrane fuel cell (PEMFC) is one of the most promising green power sources, in which perfluorinated sulfonic acid ionomer-based membranes (e.g., Nafion) are widely used. However, the widespread application of PEMFCs is greatly limited by the sharp degradation in electrochemical properties of the proton exchange membranes under high temperature and low humidity conditions. In this work, the high-performance sulfonated carbon nanotubes/Nafion composite membranes (Su-CNTs/Nafion) for the PEMFCs were prepared and the mechanism of the microstructures on the macroscopic properties of membranes was intensively studied. Microstructure evolution in Nafion membranes during water uptake was investigated by positron annihilation lifetime spectroscopy, and results strongly showed that the Su-CNTs or CNTs in Nafion composite membranes significantly reinforced Nafion matrices, which influenced the development of ionic-water clusters in them. Proton conductivities in Su-CNTs/Nafion composite membranes were remarkably enhanced due to the mass formation of proton-conducting pathways (water channels) along the Su-CNTs. In particular, these pathways along Su-CNTs in Su-CNTs/Nafion membranes interconnected the isolated ionic-water clusters at low humidity and resulted in less tortuosity of the water channel network for proton transportation at high humidity. At a high temperature of 135 °C, Su-CNTs/Nafion membranes maintained high proton conductivity because the reinforcement of Su-CNTs on Nafion matrices reduced the evaporation of water molecules from membranes as well as the hydrophilic Su-CNTs were helpful for binding water molecules.

Leak Detection in Pipe Networks Using Hybrid ANN Method

The idea of hydro informatics is applied for determining the assignment dilemma accompanied to water-based mechanism. This consideration applied prototype data as well as assertion for developing advantageous prototype for water-based approach. Hydro informatics can also assist for hydraulics, hydrology, and mechanical engineering. Hydro informatics applies software-based artificial technology for determining these consequences accompanied to water-based approach. Hydro pipe network is placed underground as well as once constructed, it is difficult to identify the status of ducts when excrete or crack occurs. Accordingly, post activity is frequently postponed later the error arises. Hence, the consistent error activity approach of water channel mesh is mandated to control the coincidence as well as lower the depletion. In this application, we compose online error identification approach of water channel network utilizing details of pipes similar as flow rate. The ephemeral prototype explaining water flow in pipelines is showed along with depicted utilizing MATLAB. The defect locations for waste or crack can be illustrated as discharge or pressure information’s when the error combined. Errors identified by applying of FFT and DWT algorithms; additionally, it was contrasted for achieving favorable error breakthrough outcome.