Transport Of Water Molecules Research Articles

Genome-wide identification of plasma membrane aquaporin gene family in Populus and functional identification of PIP1;1 involved in osmotic stress

Aquaporins are the membrane channels that facilitate the transportation of water and small neutral molecules in plants. As such, they play an important role in stress tolerance. This function may be more pronounced in woody plants, which must efficiently absorb water and transport it over long distances. Therefore, a functional analysis of plasma membrane aquaporins (PIP) under drought stress can provide insights into the roles of these proteins in woody plants. In this work, we obtained 15 members of the PtPIP gene family in poplar. They formed two groups in a phylogenetic analysis. Gene structure, including intron phases, was found to be remarkably well conserved among members of this gene family. Five paralogous gene pairs were identified in the PtPIP family, and four of those pairs arose via whole genome duplication. A selection pressure analysis showed that PtPIP genes have undergone positive selection. The transcripts of six PtPIP genes including PtPIP1;1 were predominantly detected in the root. Transgenic poplar overexpressing PtoPIP1;1 was sensitive to osmotic stress, which phenocopied PagMYB216-overexpressing poplar plants. Transactivation and yeast one-hybrid assays showed that PagMYB216, whose homologs in other plants are induced by abiotic stresses, is able to activate PtoPIP1;1 expression through binding to the MBS motif in its promoter. Our results provide new information about PtoPIPs and their roles in response to abiotic stresses, which will be helpful for better understanding their functions in Populus.

The “molecule diode” effect caused by adsorbed surfactant layers improves evaporation efficiency in the bubble column evaporator (BCE) for seawater desalination

The bubble column evaporator (BCE) can be used as an improved thermal desalination technology simply based on pumping a heated gas, such as helium, through a porous sinter to produce hot gas bubbles to transfer heat and mass across the water-gas interface. In this paper, a “molecule diode” effect caused by surfactant monolayers has been proposed, because adding surfactants into the column solution produced an improved evaporation efficiency. The mechanism involved appears to be based on enhancing water molecule transport across the bubble surfaces from the column solution via the hydrophilic headgroups, whilst restricting water vapour molecules returning to the solution because of the layer of hydrophobic tails coating the inside bubble surface. In this paper, the enthalpy of vaporization (△Hv) was estimated, and the bubble saturation period and the bubbling and foaming behaviour was observed, to study the performance of surfactants on improving the evaporation efficiency achieved by the BCE process. Myristyltrimethylammonium bromide (MAB), a typical cationic surfactant, combined with the moderately heated helium bubbles generated in the BCE column, performed best by reducing the apparent △Hv value for water by 15 % and increasing the evaporation efficiency by 2.3 times, compared with the value for non-surfactant column solutions pumped with air, which demonstrates the potential for a low cost thermal desalination technology based on this sub-boiling process.

Water Molecule-Triggered Anisotropic Deformation of Carbon Nitride Nanoribbons Enabling Contactless Respiratory Inspection

The exploitation of the interaction between nanostructured matter and small molecules, such as H2O at interfaces via dynamic hydrogen bonding, is essentially the key for smart, responsive nanodevic...

Sulfonated graphene oxide based membranes with enhanced water transport capacity for isopropanol pervaporation dehydration

By utilizing the synergistic effect of polyelectrolyte (PEL) and sulfonated graphene oxide (SGO), novel composite membranes were prepared to achieve ultrafast transport of water molecules in isopropanol pervaporation dehydration. As confirmed by FTIR, Raman, XPS and XRD measurements, the sulfonation modification resulted in defects and uneven interlayer structure within SGO membrane (SGOM), which could enlarge the free volume for low-resistance water channels. The microstructure changes of composite membranes were observed via FESEM. The measured pervaporation behavior of pure components indicates that the transport capacity of SGOMs has been enhanced compared with graphene oxide membranes. After coated with an ultrathin PEL layer, the synergistic effect of highly enhanced water adsorption from the PEL layer and ultrafast permeation channels from SGOM facilitates the rapid and selective transport of water molecules through the membrane, which ensures excellent isopropanol dehydration performances. Both the flux and separation selectivity increase with temperature. At 70 °C, the flux can reach up to 3.67 kg m−2 h−1 with 99.90 wt% water content in permeate. The prepared membrane also possesses enhanced mechanical strength with firm interfacial adhesion. All the results evidence that SGO-based membranes possess outstanding advantages in isopropanol dehydration.

Synergistic effect of polyvinyl alcohol sub-layer and graphene oxide condiment from active layer on desalination behavior of forward osmosis membrane

In this study, polyvinyl alcohol (PVA) modified with maleic acid was coated on polyethersulfone (PES) substrate as sub-layer to improve the water solubilization and salt rejection of forward osmosis (FO) membrane. Graphene oxide (GO) was added to the active layer (prepared by interfacial polymerization of ammonia monomer and acyl chloride monomer) to form nanochannels between GO and polymer matrix for transporting water molecules. On the basis of PVA sub-layer, the effects of GO content on the structure and desalination performance of FO membrane were investigated. When the GO was embedded with 500 ppm, the surface roughness of corresponding membrane (PES-PVA-PA (500)) reached the maximum among all modified membranes and hydrophilicity of the membrane surface was improved. From the analysis of FO performance, when the active layer containing GO formed on the PVA sub-layer, water flux of the membranes increased due to the existence of nanochannels and reverse salt permeation was blocked by GO sheet and PVA sub-layer. Correspondingly, the ratio of reverse salt flux (Js) to water flux (Jv) of PES-PVA-PA (500) achieved the minimum of 0.21 g/L compared with unmodified thin-film composite (TFC) membrane (0.67 g/L) which indicated that the desalination performance has been significantly improved.

Water Transport Mechanisms of Poly(acrylic acid), Poly(vinyl alcohol), and Poly(ethylene glycol) in C-S-H Nanochannels: A Molecular Dynamics Study.

The transport properties of water molecules in nanochannels are critical to the durability of porous materials. In this article, molecular dynamics simulations are used to study the effects of poly(acrylic acid) (PAA), poly(vinyl alcohol) (PAA), and poly(ethylene glycol) (PEG) on the durability of modified cement-based materials. By establishing ideal composite nanopores, the absorption of water molecules in the channel is simulated. The results show that PEG has the best water-blocking effect under the same simulated conditions, followed by PVA, and PAA is the most unfavorable. This difference in the water-blocking effect can be explained by two factors. On the one hand, hydrophobic alkane groups in these polymers can inhibit water molecule transport. A large number of -COOH and -OH functional groups in PAA and PVA will form a complex H-bond network with the water molecules in the nanopore, dragging the water molecules forward, thereby speeding up the water molecule transmission to a certain extent. However, PEG, which mainly contains low-polar oxygen (C-O-C), has weak hydrogen bonding with water molecules, so the water-blocking effect is more obvious. On the other hand, the van der Waals interaction and the electrostatic interaction mainly derived from Op-Caw-Os can ensure the absorption of the polymer on the C-S-H surface during the transport process. The -COOH in PAA ensures its strongest absorption. But PVA and PEG will morphologically agglomerate during the water absorption, occupying pores and hindering the transport of water molecules.

Understanding the effect of hydroxyl/epoxy group on water desalination through lamellar graphene oxide membranes via molecular dynamics simulation

The lamellar graphene oxide (GO) membranes could offer well-defined 2D nanochannels for fast water permeation and excellent ions rejection. In this work, lamellar GO membranes were constructed by stacking GO nanosheets layer-by-layer via molecular simulation. The effect of hydroxyl and epoxy groups as well as their content on the desalination performance in lamellar GO membranes were investigated by molecular dynamics simulation. The transport and separation mechanisms of water molecules and ions passing through the lamellar GO membranes with different functional group were also revealed from thermodynamic and hydrogen bond network. It is found that water flux in GO membranes would be influenced by the order of water molecules and the hydrogen network formed between functional groups and water molecules. GOOH membranes showed a higher Na+ rejection rate than Cl− at high hydroxyl contents.

Atomistic Simulations of Biofouling and Molecular Transfer of a Cross-linked Aromatic Polyamide Membrane for Desalination.

Reverse osmosis through a polyamide (PA) membrane is an important technique for water desalination and purification. In this study, molecular dynamics simulations were performed to study the biofouling mechanism (i.e., protein adsorption) and nonequilibrium steady-state water transfer of a cross-linked PA membrane. Our results demonstrated that the PA membrane surface's roughness is a key factor of surface's biofouling, as the lysozyme protein adsorbed on the surface's cavity site displays extremely low surface diffusivity, blocking water passage, and decreasing water flux. The adsorbed protein undergoes secondary structural changes, particularly in the pressure-driven flowing conditions, leading to strong protein-surface interactions. Our simulations were able to present water permeation close to the experimental conditions with a pressure difference as low as 5 MPa, while all the electrolytes, which are tightly surrounded by hydration water, were effectively rejected at the membrane surfaces. The analysis of the self-intermediate scattering function demonstrates that the dynamics of water molecules coordinated with hydrogen bonds is faster inside the pores than during the translation across the pores. The pressure difference applied shows a negligible effect on the water structure and content inside the membrane but facilitates the transportation of hydrogen-bonded water molecules through the membrane's sub-nanopores with a reduced coordination number. The linear relationship between the water flux and the pressure difference demonstrates the applicability of continuum hydrodynamic principles and thus the stability of the membrane structure.

Influence of acid leaching surface treatment on indentation cracking of soda lime silicate glass

Past work has shown that water or acid soaking treatments can increase the mechanical strength of soda lime silicate (SLS) glasses. In this work, we show that acid leaching treatments result in an increase in the apparent crack resistance of the acid-leached surface of SLS glass during indentation. Vickers indentation tests in controlled environments show a humidity dependence of radial cracking, suggesting that the transport of water through the leached layer plays a critical role in the propagation of cracks to the glass surface. Molecular dynamics simulations with reactive force fields indicate that the leached surface layer can undergo pressure-induced mechanochemical reactions during indentation, which increases the bridging oxygen connectivity in the silica network of the leached layer. Such structural changes can hinder transport of water molecules from the environment to the subsurface crack tip. Based on experimental observations and simulation results, a new hypothesis is proposed that mechanochemical restructuring in the leached layer in response to the applied load may lower the transport kinetics of molecular water to critical flaws, resulting in an apparent enhancement in the crack resistance of the acid-leached surface of SLS glass.

STRUCTURAL CHARACTERISTICS OF MEMBRANES AND KINETIC DEPENDENCES OF ELECTRONANOFILTRATION WASTE WATER TREATMENT OF LATINATING PROCESS

The basic structural characteristics of the membrane and kinetic dependences of the electron-filtration separation of wastewater of the brassing process are investigated. The retention factor and the specific output flow for the near-anode and near-cathode membrane were calculated. The dependences of the retention factor and the specific output flow on the transmembrane pressure and current density are analyzed, and it is noted that the anode membrane as a result of the application of a constant electric potential to the membrane-solution system starts to clog and a sludge layer forms on its surface due to the electrochemical process. A comparison is made of the retention capacity of OPMN-P and OPMN-K membranes for a real spent technological solution after the process of brazing and a model solution containing the same concentrations of copper ions (Cu2+) and zinc (Zn2+) as in real runoff. The structural characteristics of nanofiltration membranes of the type OFAM-K and OPMN-P were studied and analyzed. Changes in the crystalline and amorphous phases of the active layer and the membrane substrate are considered. The change in crystalline parameters in crystallites can be explained only by the structural features of macromolecules of polyamide and their orientation during crystallization. Under the action of transmembrane pressure and transport of water molecules, the polymorphism of the packing of the crystal lattice occurs. The packing density of the amorphous phases of the working membrane decreases, which affects the transport and selective properties of the membrane. In fact, the deformation of an amorphous-crystalline polymer leads to a restructuring of the structure not only in the orientation of the macromolecules of the amorphous, but also the crystalline phases of the membranes. It was also noted that the packing density of the amorphous phases of the working membrane decreases, which affects the transport and selective properties of the membrane.

Advances in research on aquaporins in medical helminthes

Aquaporins (AQPs) are a class of membrane intrinsic proteins in medical helminthes that specifically mediate the transmembrane transport of water or other solute molecules. Previous studies have demonstrated that AQPs play a critical role in promoting the transmembrane transport of water, osmoregulation, uptake of nutrients, release of toxic metabolic products and transport of antiparasitic drugs, which may serve as promising vaccine candidates and drug targets for parasitic diseases. This review describes the structural characteristics of AQPs in medical helminthes, and discusses the feasibility of these AQPs as antihelminth vaccine candidates and drug targets, so as to provide insights into the development of novel vaccines and drugs against parasitic diseases.

Estimation of Arecanut Crop Evapotranspiration Rate using Remote Sensing

Arecanut is a plantation crop sustains for decades and its crop water demand varies with the age. For scheduling and management of irrigation water, crop water requirement information is important. To calculate the crop water requirement, estimation of evapotranspiration is crucial. The term Evapotranspiration (ET) refers to transport of water molecules into the atmosphere from soil (soil evaporation) and vegetation (transpiration) surfaces. It is a most important component of hydrological cycle and also the most difficult factor to quantify. Crop water need is the amount of water required for balancing loss due to evapotranspiration. There are different methods proposed by researchers for the estimation of evapotranspiration. The conventional methods of evapotranspiration estimation from ground data are tedious. The advancement in remote sensing data provides estimation of evapotranspiration in a global scale. The invention of thermal remote sensing has benefitted greatly since it reduces the field data requirement for estimation of ET. It also helps to understand spatial distribution of landmass and different estimates also in estimation of evapotranspiration over a larger extent timely and periodically. In this study to estimate Arecanut crop evapotranspiration Hargreaves Samani, Penman Monteith and Priestly Taylor methods were used and compared. Arecanut crop evapotranspiration rate estimated form Landsat 8 and MODIS data are showed similar range of values between 3 to 4.45 mm/day. The study area covers an area of 835.3 hectares of Arecanut crop and the gross crop water need is found to be 23059 m3.

Are Aquaporins Expressed in Stomatal Complexes Promising Targets to Enhance Stomatal Dynamics?

The opening and closure of stomata depend on the turgor pressure adjustment by the influx or efflux of ions and water in guard cells. In this process, aquaporins may play important roles by facilitating the transport of water and other small molecules. In this perspective, we consider the potential roles of aquaporins in the membrane diffusion of different molecules (H2O, CO2, and H2O2), processes dependent on abscisic acid and CO2 signaling in guard cells. While the limited data already available emphasizes the roles of aquaporins in stomatal movement, we propose additional approaches to elucidate the specific roles of single or several aquaporin isoforms in the stomata and evaluate the perspectives aquaporins might offer to improve stomatal dynamics.

Estimation of Arecanut Crop Evapotranspiration Rate using Remote Sensing

Arecanut is a plantation crop sustains for decades and its crop water demand varies with the age. For scheduling and management of irrigation water, crop water requirement information is important. To calculate the crop water requirement, estimation of evapotranspiration is crucial. The term Evapotranspiration (ET) refers to transport of water molecules into the atmosphere from soil (soil evaporation) and vegetation (transpiration) surfaces. It is a most important component of hydrological cycle and also the most difficult factor to quantify. Crop water need is the amount of water required for balancing loss due to evapotranspiration. There are different methods proposed by researchers for the estimation of evapotranspiration. The conventional methods of evapotranspiration estimation from ground data are tedious. The advancement in remote sensing data provides estimation of evapotranspiration in a global scale. The invention of thermal remote sensing has benefitted greatly since it reduces the field data requirement for estimation of ET. It also helps to understand spatial distribution of landmass and different estimates also in estimation of evapotranspiration over a larger extent timely and periodically. In this study to estimate Arecanut crop evapotranspiration Hargreaves Samani, Penman Monteith and Priestly Taylor methods were used and compared. Arecanut crop evapotranspiration rate estimated form Landsat 8 and MODIS data are showed similar range of values between 3 to 4.45 mm/day. The study area covers an area of 835.3 hectares of Arecanut crop and the gross crop water need is found to be 23059 m 3 .

Role of Aquaporins in Spermatogenesis and Testicular Steroidogenesis.

The transport of water and several other small molecules across cell membranes is vital in many of the processes underlying reproduction. Fluid transport in cells and tissues inclusive of male reproductive organs are regulated by disparate isoforms of aquaporins (AQPs) in living organisms. Alteration in the expression, function and/or regulation of AQPs leads to some forms of male subfertility and infertility. The emerging role of AQPs in male and female reproductive function has been revealed in recent times. However, the role of AQPs with reference to male reproductive system needs to be explored in greater detail. This review emphasizes the distribution of AQPs and their physiological and pathophysiological role in spermatogenesis and steroidogenesis; and understanding the molecular mechanisms behind AQPs mediated regulation of spermatogenesis and steroidogenesis will help us in developing treatment strategies towards improved reproductive health.

Aquaporin locus (12q13.12) might contribute to susceptibility of temporomandibular joint disorder associated with periodontitis.

Aquaporins (AQPs) are membrane channels that provide for transport of water and other small molecules across the lipid bilayer of cells. Their function is essential for physiologic processes such as cell volume regulation, chondrocyte hypertrophy during appendicular skeletal growth, water reabsorption in the kidney tubules, and water excretion by the salivary glands. The ten AQP isoforms show tissue specificity and are involved in different pathologies and inflammatory diseases. This study addresses the hypothesis that arthritis, periodontitis, and temporomandibular joint disorders (TMDs) can be influenced by variation in the AQP genes at 12q13.12 locus. Salivary samples of 688 individuals were obtained from the Dental Registry and DNA Repository project at the University of Pittsburgh. Ten polymorphisms in four AQP genes (AQP1, 2, 5, and 6) were genotyped and correlated to disease status as reported by patients. Associations were found between the single nucleotide polymorphism (SNP) rs467323 in AQP2 and TMD in both genotypic (p = 0.03) and recessive (p = 0.02) models, and between rs1996315 in AQP6 and periodontitis (p = 0.05). Combined analysis of TMD and periodontitis showed an association with rs3741559 in AQP2 (p = 0.02). When conducting haplotype analysis of rs467323 and rs10875989 in AQP2, the haplotype CT showed an association with the TMD phenotype (p = 0.007). Our results suggest that the aquaporin locus at 12q13.12 may contribute to the pathogenesis of inflammatory conditions such as periodontitis and TMD. Thus, oral and skeletal health are correlated and potential susceptibility screening strategies may be developed.

Advances in research on the effects of aquaporins on animal health

Aquaporins (AQPs) are an essential transmembrane channel protein and have been discovered in many different tissues (e.g., brain, liver, kidney, and intestine) in animals and serve many specialized biological functions. Research shows that AQPs not only carry the transport of water and other small molecules in animals, but also play a crucial role in diarrhea, constipation, stress, and immunity. Currently, the research about AQPs mainly focuses on the excavation of the water channel structure and function. Additionally, researchers are using knockout mice to construct a channel protein deletion model to explore its mechanism of action on human health as well as exploring the impact of AQPs on livestock health. This paper reviews research progress on understanding AQPs in animal health, especially the impact of aquaporin on livestock health and its nutritional regulation. We also present a bioinformatics method that was used to predict the homology between livestock, poultry, and mouse AQPs genes and proteins. This research provides a theoretical reference for AQPs in animal nutrition research and scientific application.

Alcohol dehydration performance of pervaporation composite membranes with reduced graphene oxide and graphene quantum dots homostructured filler

Graphene quantum dots(GQDs) were used to possibly cover the structural defects on the graphitic regions of reduced graphene oxide(rGO). The resulting homostructure nanocomposite fillers(rGO + GQD) were incorporated in an alginate solution creating a dense composite membrane for pervaporation. The membranes were applied to separate alcohol/water mixtures in which the successful covering of structural defects was observed with good separation performance of lower molecular weight alcohols. The Raman spectra and elemental analyses confirmed the successful changes on the physical and chemical structures of the homostructured fillers. The X-ray diffraction pattern showed that the crystallinity of the membrane was greatly affected when incorporated with rGO + GQD. The alginate incorporated with 3 wt% of rGO + GQD(Alg-rGO + GQD) has the best pervaporation performance in separating methanol/water mixture with a permeation flux of 2323 g m−2 h−1 and water concentration in permeate of 92.7% at 70 °C. While the positron annihilation lifetime spectroscopy results supported that the minimization of the structural defects enhanced the water selectivity of the membrane by easy transport of water molecules through the free volume spaces and blocks methanol molecules. The results in this study may provide the possible sealing or curing the defects on rGO with GQDs and improve the interfacial interaction with the polymer matrix.

Light-Induced Transport of Water and Guest Molecules in Mesoporous Silica Nanocontainer Interface

Light-Induced Transport of Water and Guest Molecules in Mesoporous Silica Nanocontainer Interface

Superhydrophilic and mechanically robust phenolic resin as double layered photothermal materials for efficient solar steam generation

Solar steam generation has been emerged as one of efficient and green technologies for harvesting solar energy for seawater desalination and wastewater treatment. Herein, we demonstrate a facile approach for scalable fabrication of phenolic aldehyde foams (PAFs), which were synthesized by polymerization of formaldehyde with phenol and hydroquinone through one-step hydrothermal method, as double layered photothermal materials for efficient solar steam generation. The resulting PAFs show high porosity of higher than 93.6%, low apparent density (0.152–0.167 g cm−3), low thermal conductivity (0.034–0.054 W m−1 k−1) and a good mechanical strength (0.07 MPa under 30% strain). The presence of close-packed open channels, by combination with their surface superhydrophilicity (water contact angle ~ 0°), ensure the PAFs a rapid transportation of water molecules. After facile coating a thin layer of carbon soot on PAFs, a double layered photothermal materials with enhanced light absorption (~90%) was fabricated (named as CPAFs). Under 1 sun irradiation, the CPAFs possess a high water evaporation rate of 1.4922 kg m−2 h−1 and a solar conversion efficiency of 87.86%, making it promising candidate as solar generators for efficient solar desalination. By combining with their simple, scalable and cost-efficient manufacture process, it is suggested that such CPAFs may have great potentials for real applications.