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Nanoporous membranes offer significant advantages in direct contact membrane distillation applications due to their high flux and strong resistance to wetting. This study employs molecular dynamics simulations to explore the performance of membrane distillation in a single nanopore, mainly focusing on wetting behavior, liquid entry pressure, and membrane flux variations across different concentrations and types of salt solutions. The findings indicate that increasing the NaCl concentration enhances the wetting of membrane pores, thereby decreasing the entry pressure of the solution. However, at the same salt concentration, the differences in wetting and liquid entry pressure among various salts, including CaCl2, KCl, NaCl, and LiCl, are minimal. The presence of hydrated ions significantly reduces membrane flux. As the concentration of NaCl solutions increases, the number of hydrated ions rises, thereby lowering the membrane flux of the salt solution. Furthermore, the type of salt has a pronounced effect on the structure of hydrated ions. Solutions with Ca2+ and Li+ exhibit the smallest first-layer radius of hydrated ions. Under the same salt concentration, KCl solutions demonstrate the highest membrane distillation flux, while CaCl2 solutions show the lowest flux. [ABSTRACT FROM AUTHOR]

Nanoporous membranes offer significant advantages in direct contact membrane distillation applications due to their high flux and strong resistance to wetting. This study employs molecular dynamics simulations to explore the performance of membrane distillation in a single nanopore, mainly focusing on wetting behavior, liquid entry pressure, and membrane flux variations across different concentrations and types of salt solutions. The findings indicate that increasing the NaCl concentration enhances the wetting of membrane pores, thereby decreasing the entry pressure of the solution. However, at the same salt concentration, the differences in wetting and liquid entry pressure among various salts, including CaCl2, KCl, NaCl, and LiCl, are minimal. The presence of hydrated ions significantly reduces membrane flux. As the concentration of NaCl solutions increases, the number of hydrated ions rises, thereby lowering the membrane flux of the salt solution. Furthermore, the type of salt has a pronounced effect on the structure of hydrated ions. Solutions with Ca2+ and Li+ exhibit the smallest first-layer radius of hydrated ions. Under the same salt concentration, KCl solutions demonstrate the highest membrane distillation flux, while CaCl2 solutions show the lowest flux.

Early diagnosis of Alzheimer's disease (AD) is critical for preventing disease progression, however, the diagnosis of AD remains challenging for most patients due to limitations of current sensing technologies. A common pathological feature found in AD-affected brains is the accumulation of Amyloid-β (Aβ) polypeptides, which lead to neurofibrillary tangles and neuroinflammatory plaques. Here, we developed a portable ultrasensitive FET biosensor chip based on a self-assembled nanoporous membrane for ultrasensitive detection of Aβ protein in complex environments. The microscale semiconductor channel was covered with a self-assembled organic nanoporous membrane modified by antibody molecules to pick up and amplify the Aβ protein signal. The nanoporous structure helps protect the sensitive channel from non-target proteins and improves its stability since no chemical functionalization process involved, largely reduces background noise of the sensing platform. When a bio-gated target is captured, the doping state of the polymer bulk could be tuned and amplified the strength of the weak signal, achieving ultrasensitive detecting performance (enabling the device to detect target protein less than 1 fg/ml in 1 µl sample). Moreover, the device simplifies the circuit connection by integrating all the connections on a 2 cm × 2 cm chip, avoiding expensive and complex manufacturing processes, and makes it usable for portable prognosis. We believe that this ultrasensitive, portable, low-cost Aβ sensor chip shows the great potential in the early diagnosis of AD and large-scale population screening applications. [ABSTRACT FROM AUTHOR]

Compartmentalization is a ubiquitous feature of life, with a membrane interface that regulates molecular transport and exhibits bioactivities. An artificial enzyme‐integrated membrane cascade system can mimic such interactive properties across different length scales for in vitro application. Here, it is shown that a reticulated nanoporous framework membrane with nano‐caged enzymes presents the first modular macroscale platform for the compartmentalized biocatalytic system interfaced with an external medium. Catalase (CAT)‐integrated polyurea membrane scaffold is prepared by a simple pressurization procedure for a model cyclic cascade of glucose oxidase/catalase (GOx/CAT). The bicontinuous nanoporous membrane readily constructs a compartmentalized system interfacing the glucose/GOx solution and the external environment and mediates glucose oxidation by a cascade reaction under anaerobic or aerobic conditions. Furthermore, the membrane compartment exhibits multiple bioactive capabilities and barrier properties, including hydrogen peroxide detoxification, in situ oxygen generation, and protease exclusion. This work suggests a new strategy toward a robust modular biocatalytic membranous interface to mediate biochemical reaction cascades occurring in a compartment interfaced to an external environment, promising for potential applications in biohybrid devices embedded with tissues and cells. [ABSTRACT FROM AUTHOR]

Abstract Compartmentalization is a ubiquitous feature of life, with a membrane interface that regulates molecular transport and exhibits bioactivities. An artificial enzyme‐integrated membrane cascade system can mimic such interactive properties across different length scales for in vitro application. Here, it is shown that a reticulated nanoporous framework membrane with nano‐caged enzymes presents the first modular macroscale platform for the compartmentalized biocatalytic system interfaced with an external medium. Catalase (CAT)‐integrated polyurea membrane scaffold is prepared by a simple pressurization procedure for a model cyclic cascade of glucose oxidase/catalase (GOx/CAT). The bicontinuous nanoporous membrane readily constructs a compartmentalized system interfacing the glucose/GOx solution and the external environment and mediates glucose oxidation by a cascade reaction under anaerobic or aerobic conditions. Furthermore, the membrane compartment exhibits multiple bioactive capabilities and barrier properties, including hydrogen peroxide detoxification, in situ oxygen generation, and protease exclusion. This work suggests a new strategy toward a robust modular biocatalytic membranous interface to mediate biochemical reaction cascades occurring in a compartment interfaced to an external environment, promising for potential applications in biohybrid devices embedded with tissues and cells.

The energy crisis is one of the most emergency problems that humanity is facing now. To alleviate energy crisis, some new energy sources different from traditional fossil energy are developed in the past decades, for example, nuclear energy, wind energy, solar energy, et al. Among these new energy sources, an important energy existing in the ocean and river named as salinity gradient energy benefits from the features of green, safe, low cost and huge amount, and comes into the researcher's sight. In this article, we review the recent progress in harvesting salinity gradient energy with reverse electrodialysis (RED) membrane. First, the mechanism of RED was introduced, including the basic structure and working principle of RED, the ion selectivity, and the ion rectification effect. The materials which are suitable for RED were discussed in detail, such as 1D nanofluidic nanochannels, 2D materials, and composite materials. Among these materials, 2D materials are thought to be one kind of powerful material for RED because of the feasibility of producing ion-selective membranes. Besides, we dwell on the influences of solution conditions on the RED performance, like the salt gradient and species, pH value, and so on. Finally, we discussed what the RED membranes need in theory and experiment to satisfy the practical application. And the large-scale production and the anti-fouling for the long-term running of RED membranes are two key issues needed to be solved through the analysis of this paper. [ABSTRACT FROM AUTHOR]

Exosomes are considered promising biomarkers for liquid biopsy due to their capacity to transfer disease-related biomolecules between tissues or cells. However, their size range, spanning from 50 to 200 nm, presents a challenge in achieving efficient isolation. In this study, we propose a bidirectional flow control filtration (BFF) approach for exosome isolation. We employed a nanoporous polycarbonate membrane with 200 nm pores to eliminate apoptotic bodies, whereas a membrane featuring 50 nm pores was utilized to eliminate soluble proteins and concentrate exosomes. Backflush maneuvers were implemented during each phase to prevent the clogging of membrane pores, which could hinder the separation process. The BFF was applied to isolate exosomes from residual adipose tissue samples, achieving purity ratios 26 and 19 times higher compared to ultracentrifugation and direct-flow filtration, respectively, with a recovery rate of 68 %. In addition, the BFF achieved 4.4-fold higher purity and 1.9-fold higher throughput compared to size-exclusive chromatography for the isolation of exosomes from human serum. This method is scalable and facilitates a high processing rate of 1 L per hour, rendering it an optimal solution for generating large-scale exosomes for therapeutic applications. The method's scalability, minimal physical stress, and lack of chemical additives further enhance its suitability for therapeutic purposes. [Display omitted] • 200- and 50-nm porous PC membranes were used for size-selective exosome isolation. • Bi-directional flow prevents membrane clogging. • Achieved exosome purity was 9.7×108 particles/μg, 26 times higher than UC. • Achieved 4.4-fold higher purity and 1.9-fold higher throughput compared to SEC. • High-throughput processing of 1 L/h. [ABSTRACT FROM AUTHOR]

Aptamer-based methods for detecting pesticides are more efficient than antibody-based methods by high thermal stability, low molecular weight, easy modification, and low cost. In this study, the systematic evolution of ligands by exponential enrichment (SELEX) process, combined with next-generation sequencing (NGS), was performed to select aptamers specific to the pesticide, diazinon, which was fixed on a sol–gel-coated nanoporous-anodized aluminum oxide membrane to overcome the immobilization effect of general method and simplify the elution step. The frequency of specific nucleotide sequences obtained after SELEX rounds was directly analyzed using NGS to eliminate the time-consuming cloning process used in the general SELEX methods. Nine sequences with the highest frequency after SELEX round 10 followed by NGS were selected and tested to derive their binding affinity with the target, diazinon, through circular dichroism (CD) spectrophotometry. The CD signal difference of the aptamer candidates ranged from 0.13 to 2.242 mdeg between diazinon-only treated and diazinon-aptamer-treated samples at a wavelength near 270 nm. Aptamer D-4, which had the highest binding affinity from CD spectrophotometry analysis, showed no cross-reactivity with non-target pesticides, such as baycarb, bifenthrin, and pyridaben, but interacted with the other pesticides, fipronil and 2-phenylphenol. Therefore, an aptamer was effectively screened by selection of high-frequency candidates after SELEX-NGS followed by CD analysis with the highest difference signal. A follow-up study is needed to confirm whether the proposed SELEX process combined with NGS for the discovery of aptamers for new targets can further shorten the SELEX cycle by reducing the number of SELEX rounds to 10 or less. [ABSTRACT FROM AUTHOR]

In this work, the relationship between the water flux through nanoporous two-dimensional hexagonal Boron Nitride (h-BN) and surface tension was investigated from equilibrium and pressure-driven molecular dynamics simulations by considering the most popular rigid water models. From the surface tension calculation, the contact angle was evaluated and compared with the experiment. We exhibit a correlation between the water flux through nanoporous h-BN predicted by the various water models and the surface tension as a result of the difference in the interfacial energy. [ABSTRACT FROM AUTHOR]

In this paper, a plate counter-flow dew-point evaporative cooling system was designed with a nanoporous membrane covered on the surface of the wet channel for enhancement of heat and mass transfer. First, the operating principle of this device and theoretical analysis of nanoporous membrane evaporation were discussed in detail. Then, the impacts of several operating parameters on cooling performance, mainly including inlet air temperature, humidity, velocity, and the effect of utilizing the membrane, were investigated in trials. It was found that the cooling performance can be improved by using membrane significantly. In the dry channel, the maximum temperature decrease can reach 12.5 °C. At a high inlet air temperature, the product air can be dropped to a lower temperature, contributing to a more significant heat transfer process. Lower humidity, on the other hand, resulted in a reduced product air temperature and a lower cooling efficiency. Under the condition of 50% humidity, the wet-bulb efficiency and dew-point efficiency were 1.09 and 0.79, respectively. With the inlet air velocity increasing from 1.5 m/s to 2 m/s, the outlet air temperature would rise, and the wet-bulb efficiency and dew-point efficiency would decrease. To achieve better cooling performance, inlet air velocity ought to be limited to a low speed. [ABSTRACT FROM AUTHOR]

Abstract A method to directly collect negatively charged nucleic acids, such as DNA and RNA, in the biosamples simply by applying an electric field in between the sample and collection buffer separated by the nanofilter membrane is proposed. The nanofilter membrane was made of low-stress silicon nitride with a thickness of 100 nm, and multiple pores were perforated in a highly arranged pattern using nanoimprint technology with a pore size of 200 nm and a pore density of 7.22 × 108/cm2. The electrophoretic transport of hsa-mir-93-5p across the membrane was confirmed in pure microRNA (miRNA) mimic solution using quantitative reverse transcription-polymerase chain reactions (qRT-PCR). Consistency of the collected miRNA quantity, stability of the system during the experiment, and yield and purity of the prepared sample were discussed in detail to validate the effectiveness of the electrical protocol. Finally, in order to check the applicability of this method to clinical samples, liquid biopsy process was demonstrated by evaluating the miRNA levels in sera of hepatocellular carcinoma patients and healthy controls. This efficient system proposed a simple, physical idea in preparation of nucleic acid from biosamples, and demonstrated its compatibility to biological downstream applications such as qRT-PCR as the conventional nucleic acid extraction protocols.

As the potential adverse health and environmental effects of nanoscale pollutants have garnered significant attention, the demand for monitoring and capturing ultrafine particulate matter has been growing. With the rise in ultrafine dust emissions, this issue has become increasingly important. However, submicron particles require advanced strategies to be captured because of their limited inertial effect. For example, electrostatic air filters have been investigated for their improved performance in the fine particle regime. On the other hand, Raman spectroscopy was proposed as a promising analytical strategy for aerosol particles because it can be used to conveniently detect analytes in a label-free manner. Thus, the synergistic integration of these strategies can open new applications for addressing environment-related challenges. This study presents a multifunctional approach for achieving both air filtration and surface-enhanced Raman scattering (SERS) for analyte identification. We propose a nanoporous membrane composed of a thin gold layer, copper, and copper oxide to provide the desired functions. The structures are produced by performing scalable electrodeposition and subsequent electron-beam evaporation, attaining an excellent filtration efficiency of 95.9% with an applied voltage of 5 kV for 300 nm KCl particles and a pressure drop of 121 Pa. Raman intensity measurements confirm that the nanodendritic surface of the membrane intensifies the Raman signals and allows for the detection of 10 μL of nanoplastic particle dispersion with a concentration of 50 μg/mL. Rhodamine 6G aerosol stream with an approximate particle deposition rate of 0.040 × 10 6 mm -2 ·min -1 is also identified in a minimum detectable time of 50 s. The membrane is shown to be recyclable owing to its structural robustness in organic solvents. In addition, the fatigue resistance of the structure is evaluated through 22,000 iterative loading cycles at a pressure of 177 kPa. No performance degradation is observed after the fatigue loading.

Biaxial melt‐drawing of blend films composed of ultra‐high molecular weight polyethylene and normal molecular weight polyethylene produced a unique network structure consisting of 30‐nm thick homogeneous folded chain crystals. Subsequent biaxial solid‐drawing produced a nanoporous structure covering a large area of the membrane surface (120 mm × 120 mm). Effects of preparation parameters, including annealing and subsequent solid‐drawing, on resultant nanoporous morphology are also testified to achieve the desirable membrane. The higher gas permeability coefficients of the nanoporous membranes indicate that these nanopores are interconnected along the thickness direction. Despite such excellent porosity, the tensile strength reached 30 MPa, which is similar to that for the initial non‐porous film. Consistence of membrane porousness and robustness is highly desirable for various separation applications, including filtration, water purification, dialysis, and lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

The need for beneficial innovations in filtration expertise has lead to little consideration of cutting-edge materials, such as nanofiber membranes for water distillation. The presence of organic matter and traces of organics accumulation in wastewater poses a major problem and current technologies such as coagulation/flocculation and chlorine technology are unable to yield satisfying results. The extra volume of sludge generated by these technologies needs further processing and disposal. Nanotechnology has outstanding potential for filtration applications due to its capability to create precise structural controlled materials for such requirements. Electrospun nanofibrous membranes (ENMs) are cutting edge membrane technology that offer substantial high flux and high rejection rates compared to conventional membranes. ENMs present a revolution in water and sewage purification by offering a lightweight, cost-effective, and lower energy consumption process compared with conventional membranes. ENMs possess high porosity, generally approximately 80%, while conventional membranes have 5–35% porosity. Nano-engineered membranes have great potential in water treatment due to their exotic properties. In this connection, electrospinning membranes are emerging as a versatile technique with promising features for water treatment. This work highlights the application of ENM in wastewater treatment and surface modification of nanomembranes in order to address fouling issues and wastewater treatment from Tabuk Sewage Treatment Plant, Saudi Arabia.

In this paper, a plate counter-flow dew-point evaporative cooling system was designed with a nanoporous membrane covered on the surface of the wet channel for enhancement of heat and mass transfer. First, the operating principle of this device and theoretical analysis of nanoporous membrane evaporation were discussed in detail. Then, the impacts of several operating parameters on cooling performance, mainly including inlet air temperature, humidity, velocity, and the effect of utilizing the membrane, were investigated in trials. It was found that the cooling performance can be improved by using membrane significantly. In the dry channel, the maximum temperature decrease can reach 12.5 °C. At a high inlet air temperature, the product air can be dropped to a lower temperature, contributing to a more significant heat transfer process. Lower humidity, on the other hand, resulted in a reduced product air temperature and a lower cooling efficiency. Under the condition of 50% humidity, the wet-bulb efficiency and dew-point efficiency were 1.09 and 0.79, respectively. With the inlet air velocity increasing from 1.5 m/s to 2 m/s, the outlet air temperature would rise, and the wet-bulb efficiency and dew-point efficiency would decrease. To achieve better cooling performance, inlet air velocity ought to be limited to a low speed.

Adsorptive polyethesulfone (PES) membranes were prepared by intercalation of powder activated carbon (PAC) with and without functionalization. Accordingly, PAC was aminated with 1,5-diamino-2-methylpentane, and the physicochemical properties of the functionalized PAC were analyzed. Intercalation of PAC within the PES scaffold changed the porosity and mean pore size of the aminated membrane (AC-NH2) from 52.6% to 92.5% and from 22.6 nm to 3.5 nm, respectively. The effect of temperature on the performance of the modified membranes was monitored by the flux and chemical oxygen demand (COD) removal of leachate. At ambient temperature, the COD removal of the neat, AC-containing, and AC-NH2 membranes was 47%, 52%, and 58.5%, respectively. A similar increment was obtained for the membrane flux, which was due to the synergistic effect of the high porosity and large number of hydrophilic functional groups. The experimental leachate adsorption data were analyzed by Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. For all membranes, the significant thermodynamic parameters (ΔH, ΔS, and ΔG) were calculated and compared. The isosteric heat of adsorption was lower than 80 kJ∙mol–1, indicating that the interaction between the membranes and the leachate is mainly physical, involving weak van der Waals forces. [ABSTRACT FROM AUTHOR]

A facile technique to combine natural compounds and metal organic frameworks (MOFs) that produces a well-structured membrane with unparalleled separation performances was designed. Our synthesized membrane enables ultra-fast, low-pressure, precise separations for both solvent purification via organic solvent nanofiltration and desalination – key membrane-based processes for efficiently tackling worldwide water crisis. • Natural-driven nanocomposite membranes was first fabricated. • A sub-214 nm-thick selective layer was synthesized by natural materials. • The novel membrane has an extraordinary stability even in strong solvent environment. • The membranes exhibited high rejection against angstrom-sized contaminants. Synthetic polymer membranes can potentially reduce the large energy and carbon footprints that are typically associated with traditional chemical separation technologies. Unfortunately, current production protocols negate the green benefits of membrane separation. To address this bottleneck, here we report the use of natural materials monosaccharide – glucose and polydopamine and Zr-based metal organic frameworks (MOFs) to fabricate ultrathin nanocomposite membranes via interfacial polymerization reaction. The synergistic effect of these three materials on angstrom-scale molecular transport both in organic solvent and aqueous environment was elucidated using a series of complementary techniques. We demonstrate such nature-inspired nanocomposite membranes enable structural stability even in polar aprotic solvents, and unparalleled ultra-fast, low-pressure, precise separations in both nanofiltration modes, which easily surpass state-of-the-art membranes relying on unsustainable materials. The multi-functionality of saccharide nanocomposites was elegantly harnessed to impact separation applications that contribute towards a better living environment. [ABSTRACT FROM AUTHOR]

A method to directly collect negatively charged nucleic acids, such as DNA and RNA, in the biosamples simply by applying an electric field in between the sample and collection buffer separated by the nanofilter membrane is proposed. The nanofilter membrane was made of low-stress silicon nitride with a thickness of 100 nm, and multiple pores were perforated in a highly arranged pattern using nanoimprint technology with a pore size of 200 nm and a pore density of 7.22 × 108/cm2. The electrophoretic transport of hsa-mir-93-5p across the membrane was confirmed in pure microRNA (miRNA) mimic solution using quantitative reverse transcription-polymerase chain reactions (qRT-PCR). Consistency of the collected miRNA quantity, stability of the system during the experiment, and yield and purity of the prepared sample were discussed in detail to validate the effectiveness of the electrical protocol. Finally, in order to check the applicability of this method to clinical samples, liquid biopsy process was demonstrated by evaluating the miRNA levels in sera of hepatocellular carcinoma patients and healthy controls. This efficient system proposed a simple, physical idea in preparation of nucleic acid from biosamples, and demonstrated its compatibility to biological downstream applications such as qRT-PCR as the conventional nucleic acid extraction protocols. [ABSTRACT FROM AUTHOR]

Permeation and separation efficiency of ceramic membranes are strongly dependent on their nanoporous structures, especially on the pore size. In this work, ultrasound is employed to form the size-controlled ZrO2 nanoparticles, and a ceramic membrane is prepared with tunable pore size. Under the ultrasound treatment, H+ from water plays a key role in the synthesis process. The cavitation caused by ultrasound promotes the hydrolysis of the precursor in water, which produces a large number of H+. These H+ will react with precipitant added and generate cyclic tetrameric units. Excess H+ can peptize cyclic tetrameric units and form an electrical double layer, resulting in a stable sol. Unlike ultrasound treatment, precipitant will react directly with the precursor and generate precipitation if there is no ultrasound added. Moreover, cavitation is good for the dispersion of cyclic tetrameric units. The particle size of Zr-based colloidal sol can be tuned in the ranges of 1.5 to 120 nm by altering the molar ratio of precursor to precipitant, ultrasonic power density and radiation time. Meanwhile, ultrasonic power density and radiation time have effects on grain size and the crystalline transition temperature of particles which influence performance of the ceramic membrane. As a result, membranes exhibit high performance together with high permeability and desirable rejection. To develop such a simple and controllable method for tuning particle size is extremely important in the preparation of nanoporous ceramic membranes.

Elucidating the kinetics of DNA passage through a solid-state nanopore is a fertile field of research, and mechanisms for controlling capture, passage, and trapping of biopolymers are likely to find numerous technological applications. Here we present a nanofiltered nanopore device which forms an entropic cage for DNA following first passage through the nanopore, trapping the translocated DNA, and permitting recapture for subsequent reanalysis and investigation of kinetics of passage under confinement. We characterize the trapping properties of this nanodevice by driving individual DNA polymers into the nanoscale gap separating the nanofilter and the pore, forming an entropic cage similar to a "two pores in series" device, leaving polymers to diffuse in the cage for various time lengths, and attempting to recapture the same molecule. We show that the cage results in effectively permanent trapping when the radius of gyration of the target polymer is significantly larger than the radii of the pores in the nanofilter. We also compare translocation dynamics as a function of translocation direction to study the effects of confinement on DNA just prior to translocation, providing further insight into the nanopore translocation process. This nanofiltered nanopore device realizes simple fabrication of a femtoliter nanoreactor in which to study fundamental biophysics and biomolecular reactions on the single-molecule level. The device provides an electrically permeable single-molecule trap with a higher entropic barrier to escape than previous attempts to fabricate similar structures. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • PMF of molecules and ions were calculated to explain the transport of them. • The hydrophilic chemical functions can improve the water permeability. • The system 4 (–OH group on the pore edge) is more effective in water desalination. Abstract The effect of functionalized nanoporous boron nitride nanosheet (BNNS) membranes was investigated for salt separation from sea water by molecular dynamics simulations. For this purpose, a pore was created in the BNNS membrane and functionalized with various chemical functions such as hydrogen (–H), fluorine (–F), and hydroxyl (–OH) group. Functionalized membrane was placed in the middle of the simulation box in an aqueous ionic solution containing Na+ and Cl− ions. For salt rejection, an external pressure was applied to the simulation box. In this work, water permeability and salt rejection were obtained for four different systems at pressure range of 10–100 MPa. Potential of mean force of water molecules, Na+ and Cl− ions were calculated to explain the transport of water molecules and ions through the functionalized pore of BNNS membrane. Also, the water density, radial distribution functions of water-water and ion-water, hydrogen bonds, water density map, and number of water molecules inside the pore of membrane were obtained. The results demonstrated that the hydrophilic chemical functions such as –F and –OH group can improve the water permeability even at low pressures. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Polyphenylene superhoneycomb network (PSN) and covalent triazine framework (CTF) are experimentally realized periodically porous graphene derivatives. Such ultrathin layers with homogeneously distributed pores of controllable sizes are highly desirable for applications in molecular separations such as water purification. The permeation energy barrier is expected to be a function of not only the pore size, but also the specific permeation trajectory as determined by hydrogen bonding interactions at the water-pore interface. Here, we report a detailed first-principles study of permeation of a single H 2 O molecule through a monolayer PSN and CTF-0, as well as its diffusion behavior inside a bilayer PSN. The calculated energy barrier of 1.44 eV indicates the infeasibility of using PSN as a water permeation membrane. However, the barrier decreases considerably to 0.94 eV when three C-H pairs at the pore are replaced with N atoms into CTF-0. Inside a bilayer PSN, we find facile interlayer sliding as well as interlayer expansion owing to out-of-plane reorientation of the H 2 O molecule. In all cases, the functional groups at the pore significantly alter the orientation of the H 2 O molecule and the corresponding barriers. Such atomistic insights at the porous interface would provide a valuable guidance in advancing rational pore design principles. [ABSTRACT FROM AUTHOR]

Abstract Desalination provides an effective method to meet the worldwide freshwater crisis. Reverse osmosis (RO) based on polyamide (PA) thin-film composite (TFC) membranes have dominated desalination area with the enhancing desalting properties and decreasing energy consumption. However, it is still an urgent affair for the researchers all over the world to explore more advanced RO desalination materials and procedures to further enhance the popularization of desalination, among which development of superior membranes with as far as possible high water flux and satisfied salt rejections are particularly important. Two-dimensional (2D) nanoporous membranes with sub-nanopores, typically represented by graphene and its derivatives accompanied with some analogues such as molybdenum disulfide (MoS 2), have displayed great potential and attracted vast interest in designing such kinds of desalination membranes. Actually, 2D nanoporous membranes might have opened a new era in desalination membranes fabrication and demonstrated brilliant future. Given this, in this review paper we reviewed and discussed the development of 2D nanoporous membranes with sub-nanopores on desalination with emphasis in simulations coupled with experimental studies. Besides, the feasibility and future directions of 2D nanoporous membranes are prospected. We sincerely hope that this paper could provide clues and insights for the future exploration of novel desalination membranes, and further contribute to the advance of desalination membranes synthesis and large-scale production. Highlights • Various 2D nanoporous membranes are emerging hotspots in RO desalination. • Research of 2D nanoporous membranes in RO desalination was reviewed. • Practicability of 2D nanoporous membranes in RO desalination was commented. • Future research in 2D nanoporous RO desalination membranes was proposed. [ABSTRACT FROM AUTHOR]

Abstract As researchers can control the nanostructure of the nanoporous membrane based on block copolymer precursors, it is considered to be an ideal device for separation and purification. However, the challenge still remains to make ultrathin, economic, nanopore sized and charged isoporous membranes without post-treatment. Hence, a simple, energy saving and sacrificial layer free technique was adopted to bridge the gap between the uniformly spread PS- b -PAA nanospheres and the ultrathin, negatively charged nanoporous membrane. The flux of the membrane is as high as 350 L m−2 h−1 bar−1, while the effective pore size is only ca. 8 nm. It can separate not only the nanoparticles based on their size differences, but can also separate similarly sized proteins based on the charge differences efficiently. Moreover, nanofibers and lamellae formed nanoporous membranes have now been fabricated. The effective pore size can be customized, and can even be smaller than 1.5 nm for the lamellae formed membrane. Graphical abstract Nanopore sized membranes based on block copolymer micelles, i.e. , nanospheres, nanofibers and lamellae were fabricated in this work. These membranes exhibited higher permeability and sieving performance fx1 [ABSTRACT FROM AUTHOR]

Evaporation from nanoporous structures is widely studied theoretically and experimentally due to its huge potential in thermal management of high heat flux electronic devices. Yet a fundamental understanding of liquid-vapor interfacial transport is lacking due to the absence of a molecular/atomic level modeling framework. In the current study, a computational setup is constructed to model the steady-state, continuous evaporation from a single nanopore, which is analogous to a nanoporous membrane due to the utilization of proper periodic boundary conditions. Under increasing heat loads, shape and position of the evaporating meniscus are observed, and different evaporation regimes (pinning and receding) are identified. An uncommon, self-regulation of the meniscus during receding is discovered and the underlying physical mechanism is elucidated. Heat removal ability of the nanopore is examined in response to different operating conditions. To the best of the author knowledge, the current study is the first attempt to model the evaporation from a nanoporous membrane incorporating non-continuum effects associated with the both liquid and vapor flows. The methodology presented opens up an avenue for the molecular/atomic level modeling of evaporation from nanoporous membranes. [ABSTRACT FROM AUTHOR]

Abstract The ability to modulate heat transfer with widely tunable and high thermal conductance is desirable for various applications in energy conversion, thermal management, and thermal logics. Current thermal switches based on controlling heat conduction via forming and breaking mechanical contacts are limited by the narrow range of conductance modulation and the low conductance value when the switch is at the ON state, and/or suffer from reliability issues due to the use of liquid metal or high contact pressure. Here, we demonstrated widely tunable liquid-vapor phase change heat transfer with high thermal conductance. While traditional phase change heat transfer phenomena, such as boiling and evaporation, are often not tunable, we utilized a new "thin film boiling" mechanism recently discovered by us. We implemented the thin film boiling of a low surface tension fluid, ethanol, on nanoporous membranes, which showed a wide range of boiling curves with negative differential thermal conductance (NDTC), that is, decreasing superheat with increasing heat flux. Importantly, this NDTC is fully reversible and can be actively tuned by changing the liquid pressure. This unique feature enables us to actively and reversibly regulate the thermal conductance over a wide range of working conditions. The demonstrated ON/OFF conductance ratio was over 6000, and during the ON states, the conductance could be modulated over 100 times. Additionally, the maximum ON state conductance is close to 20 W/cm2 K, which is an order of magnitude higher than that of the current solid/solid contact thermal switches. This work paves the way for constructing active thermal switches and regulators to dynamically control heat transfer for a variety of applications. Graphical abstract fx1 Highlights • The thin film boiling mechanism is implemented for thermal regulation application. • Actively tunable and reversible thermal regulations of heat flux, superheat, and thermal conductance are demonstrated. • The thin film boiling based thermal switch has 100-fold conductance range in the ON state and ~6000 ON/OFF conductance ratio. [ABSTRACT FROM AUTHOR]

Nanoporous superalloy membranes are a functional extension of the use of nickel-based alloys. The material, which is usually used for high-temperature applications, consists mainly of the two phases γ and γ′. Through coarsening of the precipitates and thus forming of a bicontinuous γ/γ′ network, membranes can be produced by removing either of these phases. From the single-crystalline alloy CMSX-4, the bicontinuous network can be formed either thermo-mechanically by directional coarsening of coherent precipitates or by load-free coalescence of incoherent precipitates. Recent investigations have shown that membranes also can be produced from polycrystalline starting material in both ways. In this article, the process route for membranes by load-free coarsening of incoherent γ′ precipitates from a carbon-free version of the polycrystalline alloy Nimonic 115 is presented. This manufacturing method has the advantage of its simplicity and in comparison to single-crystalline membranes it can be realized in larger scales. We discuss the microstructure and show the mechanical properties by means of tensile tests. Despite the grain boundaries as a mechanical weak link, polycrystalline membranes show promising mechanical properties. Their strength even exceeds that of the single-crystalline membranes despite the significantly higher pore volume content.

[Display omitted] • Early diagnoses of diseases require us to detection tiny biomarkers. • Nanofluidic devices magnify signal of tiny biomarkers. • Nanofluidic devices hold a promise for in portable sensors and POC detection. Disease diagnosis, especially for early diagnosis, is the most effective method to prevent disease development and mortality. However, low abundance clinical biomarkers in samples pose a challenge to sensitivity and selectivity of early diagnosis. Nanoconfined environment provides unique effects, including ionic current rectification, steric effect, and selective transport, etc., which could be applied to magnify signal and enhance sensitivity in discrimination of biomarkers on electrochemical (EC) sensors. Therefore, nanofluidic EC sensors have experienced a speedy development in ultra-sensitive sensing. In this review, we highlight the application of nanofluidic EC sensors with different structures (nanocapillary, nanoporous membrane, nanopore, and micro/nanofluidic chip) in biomarkers detection. Different types of nanofluidic devices, mechanism of nanoconfined effect, and their applications in ultra-sensitive sensing are summarized and discussed. Finally, this review provides a respective about nanofluidic EC sensors in biomarkers detection and helps the understanding nanoconfined effect for developing new analysis. [ABSTRACT FROM AUTHOR]

Recent studies have shown that the use of membranes based on artificial nanoporous materials can be effective for desalination and decontamination of water, separation of ions and gases as well as for solutions to other related problems. Before the expensive stages of synthesis and experimental testing, the search of the optimal dimensions and geometry of nanopores for the water desalination membranes can be done using computer-aided design. In the present study, we propose and examine the assumption that rectangular nanopores with a high aspect ratio would demonstrate excellent properties in terms of water permeation rate and ion rejection. Using the non-equilibrium molecular dynamic simulations, the properties of promising hexagonal boron nitride (h-BN) membranes with rectangular nanopores were predicted. It has been found that not only the nanopore width but also its design (“armchair” or “zigzag”) determines the permeability and ion selectivity of the h-BN-based membrane. The results show that membranes with a zigzag-like design of nanopores of ~6.5 Å width and the armchair-like nanopores of ~7.5 Å width possess better efficiency compared with other considered geometries. Moreover, the estimated efficiency of these membranes is higher than that of any commercial membranes and many other previously studied single-layer model membranes with other designs of the nanopores.

Hydrogel-facilitated phase separation (HFPS) has recently been applied to make microstructured porous membranes by modified phase separation processes. In HFPS, a soft lithographically patterned hydrogel mold is used as a water content source that initiates the phase separation process in membrane fabrication. However, after each membrane casting, the hydrogel content changes due to the diffusion of organic solvent into the hydrogel from the original membrane solution. The absorption of solvent into the hydrogel mold limits the continuous use of the mold in repeated membrane casts. In this study, we investigated a simple treatment process for hydrogel mold recovery, consisting of warm and cold treatment steps to provide solvent extraction without changing the hydrogel mold integrity. The best recovery result was 96%, which was obtained by placing the hydrogel in a warm water bath (50 °C) for 10 min followed by immersing in a cold bath (23 °C) for 4 min and finally 4 min drying in air. This recovery was attributed to nearly complete solvent extraction without any deformation of the hydrogel structure. The reusability of hydrogel can assist in the development of a continuous membrane fabrication process using HFPS.

In this study, a new anodized aluminum oxide (AAO) nanostructure membrane was synthesized by anodization process under a constant voltage, in oxalic acid solution that was improved with trace amounts of sulfuric acid at room temperature. The effect of various parameters on the morphology of the synthesized nanostructures such as voltage, electrolyte composition, anodization time and type of stripping solution were investigated. According to the results, corrosion of the walls, size regularity, diameter and number of the pores increased in the presence of sulfuric acid (0.018 mol.L −1 ). Nitrogen adsorption-desorption analysis confirmed significant porosity, array and uniformity of the pore size in the synthesized nanoporous membrane. A new modification method was used based on ultrasonic-hydrothermal method to modify the synthesized AAO with Fe 3 O 4 /SiO 2 nanoparticles for metals and metalloids removal from aqueous solution. In this method, Fe 3 O 4 /SiO 2 nanoparticles were placed very regularly and uniformly on the surface and inside the pores. This modification was confirmed by characterization techniques. The modified AAO@Fe 3 O 4 /SiO 2 membrane showed excellent results for removing arsenic from aqueous media. [ABSTRACT FROM AUTHOR]

Because of their unique ordered structures, block copolymers (BCPs) are known to form a broad range of morphologies (e.g., cylinders, vesicles, spheres, and lamellae). These types of assemblies can be utilized for various potential and practical applications in numerous fields including nanotechnology. This review addresses classification of different BCPs based on polymeric moieties and arrangement of polymer chains present in their structure. Physicochemical characteristics of BCP micelles in aqueous media are also discussed along with the beneficial features of BCP self assembly in the generation of nanostructures. Potential applications of BCP-drug conjugates have also been described with numerous case studies. In addition, successful implementation of BCP self-assembly in modern age research of nanoporous ultrafiltration membrane, nanolithography, functionalized nanomaterial preparation has been overviewed with mechanistic details. Finally, we offer a brief perspective on the future opportunities of BCPs in diverse research fields. [ABSTRACT FROM AUTHOR]

Phase change heat transfer is fundamentally important for thermal energy conversion and management, such as in electronics with power density over 1 kW/cm2. The critical heat flux (CHF) of phase change heat transfer, either evaporation or boiling, is limited by vapor flux from the liquid–vapor interface, known as the upper limit of heat flux. This limit could in theory be greater than 1 kW/cm2 on a planar surface, but its experimental realization has remained elusive. Here, we utilized nanoporous membranes to realize a new “thin film boiling” regime that resulted in an unprecedentedly high CHF of over 1.2 kW/cm2 on a planar surface, which is within a factor of 4 of the theoretical limit, and can be increased to a higher value if mechanical strength of the membranes can be improved (demonstrated with 1.85 kW/cm2 CHF in this work). The liquid supply is achieved through a simple nanoporous membrane that supports the liquid film where its thickness automatically decreases as heat flux increases. The thin film configuration reduces the conductive thermal resistance, leads to high frequency bubble departure, and provides separate liquid–vapor pathways, therefore significantly enhances the heat transfer. Our work provides a new nanostructuring approach to achieve ultrahigh heat flux in phase change heat transfer and will benefit both theoretical understanding and application in thermal management of high power devices of boiling heat transfer. [ABSTRACT FROM AUTHOR]

Despite the rapid progress in the development of catalysts for dye decolorization, the simultaneous catalyzing and product separation to achieve continuous processing remains a great challenge. Here, silver nanoparticle-doped bacterial cellulose (AgNP@BC) nanoporous membrane with AgNP diameter of ~ 8.1 nm is successfully fabricated without employing any other reductants, capping or dispersing agents. In the procedure, BC hydrogel with 3D network acts as not only a stable scaffold, but also a reductant for the synthesis of AgNPs. The as-prepared membrane exhibits high efficiency of continuous catalytic decolorization toward two typical organic dyes (rhodamine 6G and methyl orange) due to its distinct nanoporous structure. Furthermore, it shows excellent recyclability with a decolorization efficiency of~ 99% even after ten times of reusing. Our strategy offers a novel, simple and eco-friendly route for the fabrication of nanoporous catalytic membrane and opens up new opportunities for the continuous catalytic decolorization of dyes in scalable application. [ABSTRACT FROM AUTHOR]

A scale-up nanoporous membrane centrifuge is designed and modeled. It can be used for nanoscale scale separation including reverse osmosis desalination. There are micron-size pores on the wall of the centrifuge and nanoscale pores on local graphene membrane patches that cover the micron-size pores. In this work, we derived the critical angular velocity required to counter-balance osmosis force, so that the reverse-osmosis (RO) desalination process can proceed. To validate this result, we conducted a large scale (four million atoms) full atom molecular dynamics (MD) simulation to examine the critical angular velocity required for reverse osmosis at nanoscale. It is shown that the analytical results derived based on fluid mechanics and the simulation results observed in MD simulation are consistent and well matched. The main advantage of such nanomaterial based centrifuge is its intrinsic anti-fouling ability to clear and ions accumulated at the vicinity of the pores due to the Coriolis effect. Analyses have been conducted to study the relation between osmotic pressure, centrifugal pressure, and water permeability. [ABSTRACT FROM AUTHOR]

Nanoporous materials exhibit wide applications in the fields of electrocatalysis, nanodevice fabrication, energy, and environmental science, as well as analytical science. In this review, we present a summary of recent studies on nanoporous membranes for water purification application. The types and fabrication strategies of various nanoporous membranes are first introduced, and then the fabricated nanoporous membranes for removing various water pollutants, such as salt, metallic ions, anions, nanoparticles, organic chemicals, and biological substrates, are demonstrated and discussed. This work will be valuable for readers to understand the design and fabrication of various nanoporous membranes, and their potential purification mechanisms towards different water pollutants. In addition, it will be helpful for developing new nanoporous materials for quick, economic, and high-performance water purification. [ABSTRACT FROM AUTHOR]

Hydrophilic nanoporous ion exchange barrier membrane, based on polyethersulfone (PES)/sulfonated polyphenylether sulfone ketone (SPPESK), was utilized for the pH dependent separation of copper and nickel ions with a commercial extractant, LIX84-I. The extraction and stripping performance of the membrane was demonstrated in a single stage membrane contactor as well as in an integrated extraction/stripping system. By adjusting the feed pH to 2.9, a complete separation of copper and nickel was achieved using the membrane contactors, where a copper flux of 1.10 × 10-8 mol/cm2 s was observed. In an extraction/stripping integrated sandwiched membrane extraction contactor, significantly higher copper flux was observed due to the coupling of copper stripping. In addition, the PES/SPPESK barrier membrane prevented the loss of the organic extractant, exhibiting high stability in 30 days dynamic test. The results indicated th a t the membrane extraction contactor system is of great potential for selective extraction of metal ions. [ABSTRACT FROM AUTHOR]

The development of chemically stable and high conductive membranes is one of the most important issues to improve the performance of vanadium flow batteries (VFBs). Herein, poly(vinylidene fluoride) (PVDF)/graphene composite nanoporous membranes were easily fabricated by manipulating crystallization processes. The graphene was used to enhance membrane selectivity and conductivity. In the nanoscale channels of the membranes, the graphene nanosheets reduced the apertures among the crystal grains, thus restraining vanadium ions crossover due to the size exclusion effect. Moreover, the oxygen groups on the graphene improved the surface hydrophilicity and formed hydrogen bonds with the PVDF polymer chains, which facilitated the proton transport. The composite membranes, with a 0.15 wt % graphene loading, showed a selectivity of 38.2 and conductivity of 37.1 mS/cm. The single cell exhibited a coulomb efficiency of 94.7%, a voltage efficiency of 88.5%, and an energy efficiency of 83.8%, which was 13% higher than that of the pristine PVDF membranes. The composite membranes showed excellent stability during 100 charge-discharge cycles. All these results indicate that the PVDF/graphene composite membrane is a promising candidate for VFB applications.

Microfluidic devices that allow biological particle separation and concentration have found wide applications in medical diagnosis. Here we present a viral separation polydimethylsiloxane (PDMS) device that combines tangential flow microfiltration and affinity capture to enrich HIV virus in a single flow-through fashion. The set-up contains a filtration device and a tandem resistance channel. The filtration device consists of two parallel flow channels separated by a polycarbonate nanoporous membrane. The resistance channel, with dimensions design-guided by COMSOL simulation, controls flow permeation through the membrane in the filtration device. A flow-dependent viral capture efficiency is observed, which likely reflects the interplay of several processes, including specific binding of target virus, physical deposition of non-specific particles, and membrane cleaning by shear flow. At the optimal flow rate, nearly 100% of viral particles in the permeate are captured on the membrane with various input viral concentrations. With its easy operation and consistent performance, this microfluidic device provides a potential solution for HIV sample preparation in resource-limited settings.