Improved Water Transport Research Articles

Silicon quantum dot-enhanced thin-film nanocomposite membranes for efficient alcohol dehydration via pervaporation: A sustainable approach

This study explores the effectiveness of silicon quantum dots (SiQDs)—specifically, amine-functionalized (NSiQDs) and amine-hydroxyl-functionalized (NOSiQDs)—in optimizing thin-film nanocomposite (TFN) membranes for pervaporation dehydration of various alcohols. The SiQDs were integrated into the membranes via an innovative interfacial polymerization technique, involving the dispersion of SiQDs in an aqueous amine solution followed by polymerization with trimesoyl chloride. This approach ensured uniform integration of SiQDs, significantly enhancing the nanostructure and surface characteristics of the membranes. Such modifications led to improved water transport capabilities, substantially boosting pervaporation efficiency. Exceptional performance was demonstrated by the TFN-NOSiQDs(400) membranes, which achieved a peak permeation flux of 4195.8 g·m−2·h−1 and maintained over 99 wt% water concentration in the permeate when tested with a 70 wt% isopropanol/water solution at 25°C. Comprehensive long-term stability assessments confirmed the robustness and consistent functionality of the membranes, highlighting their suitability for industrial applications that demand reliable and efficient alcohol separation processes.

3D macroporous MXene/sodium alginate aerogels with “brick-concrete” structures for highly efficient solar-driven water purification

Interfacial water evaporation, powered by solar energy, holds great promise to extract freshwater from seawater on a global scale. It has the potential to address the world's water scarcity challenges using renewable energy. While the ideal design of evaporator materials is critical to the interfacial vaporization desalination, tailoring the structures and compositions of solar evaporators and figuring out the structure/composition-performance relationship of evaporators remains unexplored. Herein, 3D macroporous “brick-concrete” MXene/sodium alginate aerogel (MSA) evaporators were designed and fabricated with constant MXene content and varying polymer loading. The as-made MSAs show sodium alginate-dependent evaporating performance with an optimum evaporation rate of 3.28 kg m−2 h−1 (1 sun). This exceptional rate is attributed to several factors, including enhanced light absorption, optimized pore sizes, reduced enthalpy of evaporation and improved water transport. The water molecule states and hydrogen bonding network in the aerogels can be tuned by their compositions, resulting in the reduced evaporation enthalpy, the monolithic structures with controlled thermal conductivity facilitate the exploitation of environmental energy, leading to the high evaporation rate. Our study not only establishes design principles for achieving superior evaporation performance, but also sheds light on the relationship between structures, compositions, and performance of solar evaporators.

Foliar spraying of zinc oxide nanoparticles improves water transport and nitrogen metabolism in tomato (Solanum lycopersicum L.) seedlings mitigating the negative impacts of cadmium.

The use of bio-nanotechnology in agriculture-such as the biological applications of metal oxide nanoparticles (NPs)-greatly improves crop yield and quality under different abiotic stress factors including soil metal contamination. Here, we explore the effectiveness of zinc oxide (ZnO)-NPs (0, 50 mg/L) foliar spraying to ameliorate the detrimental effects of cadmium (Cd) on the water transport and nitrogen metabolism in tomato (Solanum lycopersicum Mill. cv. Chibli F1) plants grown on a Cd-supplied (CdCl2; 0, 10, 40 μM) Hoagland nutrient solution. The results depicted that the individually studied factors (ZnO-NPs and Cd) had a significant impact on all the physiological parameters analyzed. Independently to the Cd concentration, ZnO-NPs-sprayed plants showed significantly higher dry weight (DW) in both leaves and roots compared to the non-sprayed ones, which was in consonance with higher and lower levels of Zn2+ and Cd2+ ions, respectively, in these organs. Interestingly, ZnO-NPs spraying improved water status in all Cd-treated plants as evidenced by the increase in root hydraulic conductance (L0), apoplastic water pathway percentage, and leaf and root relative water content (RWC), compared to the non-sprayed plants. This improved water balance was associated with a significant accumulation of osmoprotectant osmolytes, such as proline and soluble sugars in the plant organs, reducing electrolyte leakage (EL), and osmotic potential (ψπ). Also, ZnO-NPs spraying significantly improved NO3- and NH4+ assimilation in the leaf and root tissues of all Cd-treated plants, leading to a reduction in NH4+ toxicity. Our findings point out new insights into how ZnO-NPs affect water transport and nitrogen metabolism in Cd-stressed plants and support their use to improve crop resilience against Cd-contaminated soils.

Elevated water transport of polyamide nanofiltration membranes via aqueous organophosphorus mediated interfacial polymerization

As interfacial polymerization (IP) is a reaction-diffusion process, rational regulation of diamine diffusion rate is effective to heighten the nanofiltration (NF) performance of polyamide (PA) membranes. Herein, we propose an aqueous organophosphorus-regulated IP strategy that promotes the formation of thinner and moderately crosslinked films toward improved water transport. Two similar compounds tetrakis (hydroxymethyl) phosphonium chloride (THPC) and tetrakis (hydroxymethyl) phosphonium sulfate (THPS) were utilized as functional additives to physically interact with piperazine via hydrogen bonding and thus retard piperazine diffusion rate during an IP process. The resultant polyamide membranes have been analyzed in terms of surface morphologies, chemical structures, hydrophilicity, and separation performance in detail. Surface temperature monitoring results revealed that heat release from regulated IP was less than that from unmodified IP, which was ascribed to retard monomer diffusion toward organic boundary in the presence of THPC or THPS. Molecular dynamics simulation further confirmed that the addition of THPC and THPS could efficiently decline the monomer diffusion rate via hydrogen bonds and increased solution viscosity. The modified PA membranes exhibited a reduced film thickness, moderate crosslinking degree, as well as increased average pore size, as revealed by a series of characterizations. Furthermore, the incorporation of THPC or THPS resulted the PA membranes with higher surface hydrophilicity and stronger negative charges. These improved physicochemical features synergically conferred a two-fold water permeance while maintaining a high divalent salt rejection (THPC-0.01: 18.3 L m-2 h−1 bar−1, 99.0 %, THPS-0.015: 20.2 L m−2 h−1 bar−1, 98 %). This aqueous organophosphorus regulated IP offers a simple and feasible approach to the preparation of low-transport-resistance PA membranes for enhanced NF performance.

A self-floating integrated hydrogel evaporator with efficient salt resistance and thermal localization for efficient solar water desalination

Solar-driven interfacial evaporation technology was considered a promising way to effectively alleviate the global freshwater crisis. However, it is still a major challenge to design evaporators with efficient thermal management, salt resistant and self-floating ability to realize efficient clean water production. Here, we design a double-layer hydrogel evaporator with self-floating system. The evaporator is prepared from expanded polystyrene board, poly (vinyl alcohol), polyvinylpyrrolidone, agar and conductive carbon black. The structural design of the evaporator improves water transport capacity of the evaporation system and effectively reduces heat loss, so that the evaporator has efficient salt resistance and thermal localization. The evaporator demonstrates an outstanding evaporation rate and evaporation efficiency of 2.77 kg m-2h−1 and 94.25 % under 1 kW m−2 illumination. Additionally, the evaporator exhibits good stability in the 10-cycle solar evaporation experiment. Furthermore, the evaporator exhibits excellent salt resistance in 3.5 wt% NaCl solution during continuous evaporation for 9 h at 1 kW m−2 illumination. Moreover, the purification rates of the organic wastewater 4-nitrophenol and methylene blue by the evaporator reached 99.8 % and 100 %, respectively. This evaporator has stable and efficient capability of solar water purification, providing a new way for large-scale solar desalination and water purification.

Janus cotton fabric with Dual-Discrepancies in surface energy and porosity for efficient thermal and moisture management

The Janus fabrics offer potential advantages in moisture management for a comfortable microclimate between our bodies and the environment, but challenges remain in achieving desirable unidirectional sweat transfer and integrating wearing comfort, cost-effectiveness, and fabrication scalability. Here, cotton fabrics are modified on their opposing surfaces to create a Janus structure with dual discrepancies in surface energy and fabric porosity, resulting in improved water transport capability and a well-balanced combination of the mentioned properties. The hydrophobic surface was created by covalently grafting a block copolymer, poly(acrylic acid)-b-poly(lauryl methacrylate), onto one side of a cotton fabric using a “mist polymerization” technique. Porosity differentiation was then achieved by electrospinning silk fibroin (SF) onto the opposite side. The resulting dual-discrepancy in the fabric synergistically enhances its unidirectional transport capability, achieving an outstanding water evaporation rate of 3.0 kg m−2 in 6 h, and at least 2 °C evaporative cooling compared with other conventional fabrics such as cotton and PET. This study demonstrates valuable insights into the development of smart textiles that provide a comfortable microclimate for the human body.

Finely tuned water structure and transport in functionalized carbon nanotube membranes during desalination.

Molecular dynamics simulations were performed to tune the transport of water molecules in nanostructured membrane in a desalination process. Four armchair-type (7,7), (8,8), (9,9) and (10,10) carbon nanotubes (CNTs) with pore diameters around 1 nm were chosen, their interior surfaces were modified with -OH, -CH3 and -F groups. Simulation results show that water transport in nanochannel depends on confined water structures which could be regulated by precisely controlled channel diameter and chemical functionalization. Increasing CNT diameter changes water structures from single-file-like to be square and hexagonal-like, then into a disordered pattern, resulting in a concave-shaped trend of water permeance. The -OH functional groups promote structural ordering of water molecules in (7,7) CNT, but disrupt water structures in (8,8) and (9,9) CNTs, and reduce the order degree of water molecules in (10,10) CNT, moreover, exert an attraction to enhance surface friction inside channel. The -CH3 groups induce more strictly single-file movement of water molecules in (7,7) CNT, turning water structures in (8,8) and (9,9) CNTs into two and triangular column arrangements, improving water transport, however, causing again square-like water structure in (10,10) CNT. Fluorinations of CNT make water structure more disordered in (7,7), (9,9) and (10,10) CNTs, while enhance the square water structure in (8,8) CNT with a lower water permeance. Through changing channel diameter and functionalization, the low tetrahedral order corresponds to a more single-file-like water structure, associated with rapid water diffusion and high permeability; an increase in tetrahedrality results in more ice-like water structures, lower water diffusion coefficients, and permeability. The results of this study demonstrate that water transport could be finely regulated via a functionalized CNT membrane.

Vertical porous aerogel based on polypyrrole and bimetallic modified β-cyclodextrin polymer-chitosan for efficient solar evaporation

Solar-driven interfacial evaporation (SDIE) stands out as a prospective technology for freshwater production, playing a significant role in mitigating global water scarcity. Herein, a cyclodextrin polymer/chitosan composite aerogel (PPy-La/Al@CDP-CS) with vertically aligned channels was prepared as a solar evaporator for efficient solar steam generation. The vertically aligned pore structure, achieved through directional freezing assisted by liquid nitrogen, not only improves water transport during evaporation but also enhances light absorption through multiple reflections of sunlight within the pores. The polypyrrole particles sprayed on the surface of the aerogel acted as a light-absorbing layer, resulting in an impressive absorbance of 98.15 % under wetting conditions. The aerogel has an evaporation rate of 1.85 kg m−2 h−1 under 1 kW m−2 irradiation. Notably, the vertical pore structure of the aerogel allows it to exhibit excellent evaporation performance and salt resistance even in highly concentrated salt solutions. Furthermore, this aerogel is an excellent solar-driven interfacial evaporator for purifying seawater and fluoride-containing wastewater. This photothermal aerogel has the advantages of excellent performance, low cost, and environmental friendliness, and thus this work provides a new approach to the design and fabrication of solar photothermal materials for water treatment.

Dredging of Harbours and Rivers: Review of Practices and Associated Environmental Impacts.

Dredging of harbors and rivers is essential for waterway accessibility and infrastructure enhancement. This review explores key aspects of dredging, including types, applications, environmental concerns, mitigation strategies, and insightful case studies. This paper highlights the importance of dredging in improving water transport and related sectors. It covers diverse dredging types and applications such as Maintenance dredging, Capital dredging, Environmental dredging and Land Reclamation showcasing their adaptability to different project needs. It examines environmental issues linked to dredging and proposes effective mitigation methods. These measures address sediment disturbance, habitat disruption, and water quality degradation. There were two case histories which are The panama Canal Expansion and The Rhine river dredging in Europe illustrating practical dredging applications. These cases offer insights into both successful practices and challenges encountered during project execution. This, summarizes key findings and provides sustainable dredging recommendations. These include enhanced planning, monitoring, and the integration of eco-friendly technologies.

Performance and Stability of Aemion and Aemion+ Membranes in Zero-Gap CO2 Electrolyzers with Mild Anolyte Solutions.

The dependence of performance and stability of a zero-gap CO2 electrolyzer on the properties of the anion exchange membrane (AEM) is examined. This work firstly assesses the influence of the anolyte when using an Aemion membrane and then shows that when using 10 mM KHCO3 , a CO2 electrolyzer using a next-generation Aemion+ membrane can achieve lower cell voltages and longer lifetimes due to increased water permeation. The impact of lower permselectivity of Aemion+ on water transport is also discussed. Using Aemion+, a cell voltage of 3.17 V at 200 mA cm-2 is achieved at room temperature, with a faradaic efficiency of >90 %. Stable CO2 electrolysis at 100 mA cm-2 is demonstrated for 100 h, but with reduced lifetime at 300 mA cm-2 . However, the lifetime of the cell at high current densities is shown to be increased by improving water transport characteristics of the AEM and reducing dimensional swelling, as well as by improving cathode design to reduce localized dehydration of the membrane.

Surpassing 2D Photoabsorbers with Palm Fiber Upcycling as Highly Hydrophilic and Low-Cost Photothermal Materials for Improved Water Transport Interfacial Solar Steam Generation

Solar steam generation (SSG) has been proposed in the recent years as one of the countermeasures for solving the increasing risk of water scarcity on a global scale. SSG outshines conventional water treatment technologies with solar energy being its primary driving energy as well as its relatively simple system design. Nevertheless, challenges have been addressed for SSG, particularly the low efficiency of steam generation and dubious economic feasibility. In this study, a solar evaporator consisting of low-temperature carbonized oil palm fibers with integration of polydopamine is used to construct a biomass-based solar evaporator. Owing to the synergistic effect of the wide solar absorption spectrum of the carbonized fiber and highly hydrophilic characteristics of polydopamine, a water evaporation rate of 1.637 kg m–2 h–1 is achieved under 1 sun irradiation. To demonstrate the ability of the as-designed system for water treatment applications, actual lake water and seawater are employed as water reservoirs, and the water purification effect is assessed in terms of total dissolved solids and salinity. This biomass-derived evaporator offers a design rationale for cost-effective steam generation via biomass waste upcycling of the oil palm industry, which is advantageous for the scalable setup of the system in water-scarce, impoverished area.

An NMR study of the role of coir fibers in the hydration and drying of cement paste at early age

Natural fibers such as coir fibers have been increasingly explored as reinforcement in the cementitious composite to promote sustainable and economical construction. However, the in-situ application of this composite presents challenges due to the complex interplay of water behaviors, involving the hydrophilicity of natural fibers, the hydration of cement and the evaporation due to drying. Although these water-related processes play a crucial role in achieving the desired properties, they have been relatively underreported in the literature. This study aims to investigate the role of coir fibers in the water distribution and pore size distribution during the early age (initial 3 days) of cement paste hydration under drying conditions. Accordingly, Nuclear Magnetic Resonance (NMR) methods involving the moisture profiling and transverse relaxation are used to monitor the water distribution and pore size distribution in time but also in space. The samples are made by adding water-saturated coir fibers to the cement paste at different dosages (0, 1%, 2% and 4%). The effects of drying and coir fiber dosages on the samples are evaluated. The results show that drying leads to a moisture gradient and a larger transverse relaxation time T2, i.e., a coarser pore structure near the drying surface. By adding the saturated coir fibers, the moisture gradient caused by drying is decreased and spread out along the sample. As the coir fiber content increases, the water content along the sample and the total water content of the sample increase. As a result, the samples with coir fibers exhibit a lower T2, i.e., a denser pore structure near the drying surface. Coir fibers are shown to eliminate the adverse effect of drying on cement hydration through three effects, including the internal curing, improved water transport and crack control. The results from this study reveal the promising potential of coir fibers for in-situ construction applications.

Improving water transport through sub‐nanometer channels by alternating hydrophilic–hydrophobic patterns

AbstractHydrophilicity is key factor to sub‐nanometer channels for water transport. However, how to effectively integrate the respective advantages of hydrophilicity and hydrophobicity to realize ultrafast water transport at the sub‐nanometer scale is still confusing. By using sub‐nanometer channels formed by two‐dimensional covalent organic frameworks as typical models, we herein demonstrate that alternating hydrophilic–hydrophobic patterns in channels are capable of significantly improving water transport. Alternatingly stacking hydrophilic and hydrophobic monolayers is testified to be energetically favorable to directly piling their multilayers. Meanwhile, alternatingly‐stacked hydrophilic–hydrophobic multilayers are able to achieve much higher water permeability than individual hydrophilic or hydrophobic multilayers. The effect of framework flexibility is also investigated. The exceptional performances benefit from the perfect balance between excellent wettability of hydrophilicity and low friction of hydrophobicity. In order to give full play to the synergistic advantages, the thickness of hydrophobic patterns spaced by hydrophilic ones should be less than 1 nm.

ZIF-67 templated thin-film composite forward osmosis membrane: Importance of incorporation method on morphology and performance

In this study, a promising strategy is reported to synthesize a high water-permeable polyamide (PA) rejection layer using ZIF-67 nanoparticle as a sacrificial templating material. ZIF-67 nanoparticle was incorporated into the PA rejection layer using two different strategies (i) conventional blending interfacial polymerization (IP) and (ii) newly introduced in-situ growth methods. The primary aim was to study the effects of various incorporation strategies on template removal efficiency. In the conventional blending IP method, the pre-synthesized ZIF-67 nanoparticle was dispersed in the amine monomer solution and incorporated into the PA layer of thin-film composite membranes (TFN-ZIF-PS, modified with pre-synthesized ZIF-67). But in the in-situ method, ZIF-67 was synthesized and incorporated simultaneously with the formation of the PA layer via interfacial reaction of aqueous amine/Co+2 and organic acid chloride/Hmim solutions (TFN-ZIF-IS, modified with in-situ synthesized ZIF-67). After IP reaction, ZIF-67 nanoparticles were removed by water dissolution, which created nanovoids within the PA layer. Systematic membrane characterization confirmed that the incorporation method significantly affects template removal efficiency, where the TFN-ZIF-IS membrane shows a quite different morphology after ZIF-67 removal (membrane with nanovoids (NV), TFC-NV-IS). The effective incorporation and removal of ZIF-67 nanoparticles increased the water permeability of TFC-NV-IS to 5.6 LMH/bar, which is about 5-fold compared with the control TFC membrane. Additionally, TFC-NV-IS exhibited forward osmosis water flux that was raised about 2-fold compared with the control TFC one with a negligible decrease in selectivity. These considerably enhanced separation performances can be attributed to the improved water transport through the as-formed nanovoids. Thus, our strategies (incorporation and template removal) in this study provide a new avenue to synthesize advanced TFC-FO membranes with exceptional performance.

Laser Structured Gas Diffusion Layers for Improved Water Transport and Fuel Cell Performance

Polymer electrolyte fuel cells are promising energy converters for future green energy systems. For wide commercial use, still cost reductions by increasing the power density are required. Structurally optimized gas diffusion layers (GDLs), allowing for cell operation at high current densities with reduced mass transport losses, are an essential component for this development. Here we demonstrate that GDLs modified with perforations can improve water transport in the high current density regions and increase fuel cell performance. Laser perforation prior to GDL hydrophobization circumvents previously observed flooding problems and allows for stable operation. The advanced pattern, connecting channel and land regions drains pores, hence decreasing the liquid water fraction, especially close to the GDL and catalyst layer interface. Operando dynamic X-ray tomographic microscopy (XTM) is employed to understand water transport in the modified structure, and the competition with random break-through of water clusters to the channel is analyzed. The detailed and time-resolved insights allow us to propose guidelines for future advanced patterning geometries, suggesting denser perforations and methods to counteract the observed high frequency resistance (HFR) increase. Furthermore, this approach can act as model system for next generation GDLs and lead to a more rational design of transport layers.

β-Patchoulene Ameliorates Water Transport and the Mucus Barrier in 5-Fluorouracil-Induced Intestinal Mucositis Rats via the cAMP/PKA/CREB Signaling Pathway.

Intestinal mucositis (IM) is the main side effect observed in patients who receive cancer chemotherapy. The characteristics of ulceration, vomiting, and severe diarrhea cause patients to delay or abandon further treatment, thereby aggravating their progress. Hence, IM cannot be overlooked. β-patchoulene (β-PAE) is an active ingredient isolated from Pogostemon cablin (Blanco) Benth (Labiatae) and has shown a marked protective effect against gastrointestinal diseases in previous studies. However, whether β-PAE plays a positive role in IM is still unknown. Herein, we explore the effects and the underlying mechanism of β-PAE against 5-fluorouracil (5-FU)-induced IM in IEC-6 cells and rats. β-PAE significantly recovered cell viability, upregulated the IM-induced rat body weight and food intake and improved the pathological diarrhea symptoms. Aquaporin is critical for regulating water fluid homeostasis, and its abnormal expression was associated with pathological diarrhea in IM. β-PAE displayed an outstanding effect in inhibiting aquaporin 3 (AQP3) via the cAMP/protein kinase A (PKA)/cAMP-response element-binding protein (CREB) signaling pathway. Besides, inflammation-induced mucus barrier injury deteriorated water transport and aggravated diarrhea in IM-induced rats. β-PAE’s effect on suppressing inflammation and recovering the mucus barrier strengthened its regulation of water transport and thus alleviated diarrhea in IM-induced rats. In sum, β-PAE improved IM in rats mainly by improving water transport and the mucus barrier, and these effects were correlated with its function on inhibiting the cAMP/PKA/CREB signaling pathway.

The role of oxidation level in mass-transport properties and dehumidification performance of graphene oxide membranes

Here we report on gas and vapor transport properties of ultra-thin graphene oxide (GO) membranes, with various C:O ratios. Graphene oxide nanosheets with an average lateral size of 800 nm and C:O ratio ranging from 2.11 to 1.81 have been obtained using improved Hummers’ method by variation of graphite:KMnO4 ratio. Thin-film selective layers based on the obtained graphene oxide have been spin-coated onto porous substrates. To extend the C:O range to 2.60, thermal reduction of GO membranes was applied. A decrease in C:O ratio leads to significant water vapor permeance growth to over 60 m3(STP)·m−2·bar−1·h−1 while the permeance towards permanent gases reduces slightly. According to the permeation and sorption measurements, a decisive role of H2O diffusivity has been established, while the water sorption capacity of the graphene oxide stays nearly independent of C:O ratio in GO. The result is supported by semi-empirical modeling which reveals diminution of H2O jump activation barriers with both increasing GO interlayer spacing and its oxidation degree. The height of the activation barriers was found to vary up to an order of magnitude within the entire range of relative humidity (0–100% RH), lowering significantly for strongly oxidized GO. Our results evidence the necessity of attaining maximum GO oxidation degree for improving water transport in GO, especially at low partial pressures.

Bipolar Membranes with Systematically Varied Interfacial Areas in the Junction Region

Bipolar membranes (BPMs) have been historically deployed in electrodialysis for pH adjustment of process streams and the production of acids and bases. More recently, it has seen increasing popularity for fuel cell and electrolysis technologies. Under reverse bias, BPMs allow for disparate pH control in electrochemical cells and regeneration of electrolyte. The ability to maintain disparate pH in the cell expands the palette of electrocatalysts for a given cell configuration. Despite the enticing potential BPM electrolyte separators offer, they often cannot facilitate large current density values normally attained with single-ion conducting membranes (i.e., CEM or AEMs) in fuel cells and electrolyzers. This challenge has motivated three general strategies to improve the performance of BPMs: i.) judicious selection of the water-dissociation catalyst in the junction region; ii.) facilitating improved water transport to the junction region; and iii.) fabricating high surface area interfaces between the AEM and CEM in the junction region.This talk presents soft-lithography as a method to generate micropatterned membrane surfaces with a defined interfacial area that is retained during BPM fabrication. The approach is conducive for a variety of commercially available CEM and AEM chemistries (e.g., Nafion, perfluorinated AEM, Orion poly(arylene) AEM, and SPEEK). These chemistries are stable at elevated temperatures, extreme pHs, and in the presence of strong oxidizers. Our work demonstrates a 250 mV in the on-set potential for water-splitting while also increasing the current density by 15% when increasing the interfacial area by 2.28x. The improved water-splitting observations are primarily explained by calculating the electric field in the junction region using the Poisson equation. The marginal increase in current density was attributed to the BPM being under mixed reaction-diffusion control. Finally, we demonstrate a block copolymer lithography approach for generating nanopatterned surfaces on ion-exchange membranes. Taking advantage of the tunability of block copolymer lithography, the feature sizes and geometry of the nanostructure at the interface can be systematically controlled.This work was supported from NSF Award # 1703307. Figure 1

Graphene-like MOF nanosheets stabilize graphene oxide membranes enabling selective molecular sieving

Thin laminar membranes assembled by 2D nanomaterials evince the potential to achieve rapid and efficient molecular transport due to precisely amendable in-plane pores and interlayer distances. Despite the extensive use of graphene oxide (GO) membranes for water treatment, water-induced instability and the barrier effect remain challenging issues to be addressed. Here, a water-stable, graphene-like MOF nanosheet (Cu-TCPP) was implemented as a framework bridge to stabilize the GO laminates against swelling and redispersion into water. A stable heterostructure was established by the electrostatic interaction between porphyrin and oxygen-containing groups, and metal coordination of the carboxyl groups of GO nanosheets. The presence of ultrathin Cu-TCPP nanosheets promotes the formation of a nano-wrinkled surface with vertical-slit and in-plane pores that dominate the significantly improved water transport. The resultant composite membranes evince a 7-fold-higher water permeance (165.2 L m−2 h−1 bar−1) than that of GO membranes with remarkable solute retention (Congo red: 99.1%). Furthermore, this membrane shows an excellent sieving ability either for RB5/MO solutions or for CR/salt mixtures, while achieving a remarkable antibacterial activity against E. coli. The combination of rigid and flexible nanosheets opens an avenue to construct a water-stable multi-channel frame for the next generation of porous 2D materials for water purification.

A gene that underwent adaptive evolution, LAC2 (LACCASE), in Populus euphratica improves drought tolerance by improving water transport capacity

Drought severely limits plant development and growth; accordingly, plants have evolved strategies to prevent water loss and adapt to water deficit conditions. However, experimental cases that corroborate these evolutionary processes are limited. The LACCASEs (LACs) family is involved in various plant development and growth processes. Here, we performed an evolutionary analysis of LACs from Populus euphratica and characterized the functions of LACs in Arabidopsis and poplar. The results showed that in PeuLACs, multiple gene duplications led to apparent functional redundancy as the result of various selective pressures. Among them, PeuLAC2 underwent strong positive selection. Heterologous expression analyses showed that the overexpression of PeuLAC2 alters the xylem structure of plants, including thickening the secondary cell wall (SCW) and increasing the fiber cell length and stem tensile strength. Altogether, these changes improve the water transport capacity of plants. The analysis of the physiological experimental results showed that PeuLAC2-OE lines exhibited a stronger antioxidant response and greater drought tolerance than WT. Three genes screened by transcriptome analysis, NAC025, BG1, and UGT, that are associated with SCW synthesis and drought stress were all upregulated in the PeuLAC2-OE lines, implying that the overexpression of PeuLAC2 thickened the SCW, improved the water transport capacity of the plant, and further enhanced its drought tolerance. Our study highlights that genes that have undergone adaptive evolution may participate in the development of adaptive traits in P. euphratica and that PeuLAC2 could be a candidate gene for molecular genetic breeding in trees.