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Nanotechnology is transforming therapeutics for brain disorders, especially in developing drug delivery systems. Intrathecal immunoselective nanopheresis with soluble monoclonal antibodies represents an innovative approach in the realm of drug delivery systems for Central Nervous System conditions, especially for targeting soluble beta-amyloid in Alzheimer's disease. This review delves into the concept of intrathecal immunoselective nanopheresis. It provides an overall description of devices to perform this technique while discussing the nanotechnology behind its mechanism of action, its potential advantages, and clinical implications. By exploring current research and advancements, we aim to provide a comprehensive understanding of this novel method, addressing the critical questions of what it is, how it works, why it is needed, and when it should be applied. Special attention is given to patient selection and the optimal timing for therapy initiation in Alzheimer's, coinciding with the peak accumulation of amyloid oligomers in the early stages. Potential limitations and alternative targets beyond beta-amyloid and future perspectives for immunoselective nanopheresis are also described. [ABSTRACT FROM AUTHOR]

Nanotechnology is transforming therapeutics for brain disorders, especially in developing drug delivery systems. Intrathecal immunoselective nanopheresis with soluble monoclonal antibodies represents an innovative approach in the realm of drug delivery systems for Central Nervous System conditions, especially for targeting soluble beta-amyloid in Alzheimer’s disease. This review delves into the concept of intrathecal immunoselective nanopheresis. It provides an overall description of devices to perform this technique while discussing the nanotechnology behind its mechanism of action, its potential advantages, and clinical implications. By exploring current research and advancements, we aim to provide a comprehensive understanding of this novel method, addressing the critical questions of what it is, how it works, why it is needed, and when it should be applied. Special attention is given to patient selection and the optimal timing for therapy initiation in Alzheimer’s, coinciding with the peak accumulation of amyloid oligomers in the early stages. Potential limitations and alternative targets beyond beta-amyloid and future perspectives for immunoselective nanopheresis are also described.

Nanoporous membranes exhibit wide applications in the fields of energy, environmental, and analytical science. Among all nanoporous membrane materials, degradable block copolymers (DBCP) have attracted attention due to their well-defined nanopores, high porosity, narrow pore size distributions, and abundant functional end-groups. In this review, the fabrication strategies of DBCP-derived nanoporous membranes are described first, including degradation of sacrificial blocks, cleavage of block-linkers, and the removal of pore-forming agents. Secondly, the extensive applications of DBCP-derived nanoporous membranes are discussed. Generally, they have been used for separation membranes, nanotemplates, etched masks, catalysis, electronics, biomedicine, etc. Finally, the possible development directions and challenges of DBCP-derived nanoporous membranes in various applications are proposed.

Stimuli‐responsive nanoporous materials represent a newly emerging category of functional materials, for which instant and significant response behavior is strongly demanded but still challenging. Herein, a new kind of conjugated poly(ionic liquid)s (PILs) synthesized via a simple one‐pot spontaneous nucleophilic substitution and polymerization between 4,4'‐vinylenedipyridine and propargyl bromide is reported. A nanoporous membrane actuator is further developed via ionic complexation between the current PIL and trimesic acid. The actuator carries a gradient density in the hydrophobicity content along the membrane cross‐section, which results in a fast response to moisture. [ABSTRACT FROM AUTHOR]

Intrathecal pseudodelivery of drugs is a novel route to administer medications to treat neurodegenerative diseases based on the CSF-sink therapeutic strategy by means of implantable devices. While the development of this therapy is still in the preclinical stage, it offers promising advantages over traditional routes of drug delivery. In this paper, we describe the rationale of this system and provide a technical report on the mechanism of action, that relies on the use of nanoporous membranes enabling selective molecular permeability. On one side, the membranes do not permit the crossing of certain drugs; whereas, on the other side, they permit the crossing of target molecules present in the CSF. Target molecules, by binding drugs inside the system, are retained or cleaved and subsequently eliminated from the central nervous system. Finally, we provide a list of potential indications, the respective molecular targets, and the proposed therapeutic agents. [ABSTRACT FROM AUTHOR]

Electrochemical characterization of alumina-based membranes obtained by two different techniques, sinterization or anodization, is performed by analyzing membrane potential values. This analysis allows us the estimation of the effective concentration of fixed charge in the membrane (Xef) and the transport number of the ions into the pores (ti), as well as the determination of ionic permselectivity (P(i)) and their correlation with the different structures (supported, symmetrical or asymmetric), geometrical parameters (pore size and porosity) and surface materials (alumina-zirconia or alumina) of the studied membranes. From these results, the electropositive character of the membranes was stated, but also the significant reduction (70%) in Xef value and around 30% in permselectivity when pore size increases from 25 nm to 100 nm, in the case of sinterized alumina-zirconia membranes with similar porosity (CRF samples), while the clear influence of pore size on the electrochemical behavior of the electrochemically synthesized alumina membranes (NPAM samples) was confirmed as well as the lower influence of membrane porosity. Moreover, the effect of protein (BSA) static fouling on electrochemical parameters for both CRF and NPAMs samples was also analyzed, and our results show a reduction in the electropositive character of both membranes, being this behavior opposite to that discussed for one of the NPAMs as a result of surface modification with a theophylline derivative (Theo 1). [ABSTRACT FROM AUTHOR]

We have previously proposed a radical change in the current strategy to clear pathogenic proteins from the central nervous system (CNS) based on the cerebrospinal fluid (CSF)-sink therapeutic strategy, whereby pathogenic proteins can be removed directly from the CNS via CSF. To this aim, we designed and manufactured an implantable device for selective and continuous apheresis of CSF enabling, in combination with anti-amyloid-beta (Aβ) monoclonal antibodies (mAb), the clearance of Aβ from the CSF. Here, we provide the first proof of concept in the APP/PS1 mouse model of Alzheimer's disease (AD). Devices were implanted in twenty-four mice (seventeen APP/PS1 and seven Wt) with low rates of complications. We confirmed that the apheresis module is permeable to the Aβ peptide and impermeable to mAb. Moreover, our results showed that continuous clearance of soluble Aβ from the CSF for a few weeks decreases cortical Aβ plaques. Thus, we conclude that this intervention is feasible and may provide important advantages in terms of safety and efficacy. [ABSTRACT FROM AUTHOR]

BackgroundPhenol is one of the most versatile and important organic compound. It is also a growing concern as water pollutants due to its high persistence and toxicity. Removal of Phenol from wastewaters was investigated using a novel nanoparticle adsorption and nanofiltration technique named as Nanoparticle Assisted Nano Filtration (NANF).MethodsThe nanoparticle used for NANF study were silver nanoparticles and synthesized to three distinct average particle sizes of 10 nm, 40 nm and 70 nm. The effect of nanoparticle size, their concentrations and their tri and diparticle combinations upon phenol removal were studied.ResultsTotal surface areas (TSA) for various particle size and concentrations have been calculated and the highest was 4710 × 10(12 )nm(2 )for 10 nm particles and 180 ppm concentration while the lowest was for 2461 × 10(11) for 70 nm and 60 ppm concentrations. Tri and diparticle studies showed more phenol removal % than that of their individual particles, particularly for using small particles on large membrane pore size and large particles at low concentrations. These results have also been confirmed with COD and toxicity removal studies.ConclusionsThe combination of nanoparticles adsorption and nanofiltration results in high phenol removal and mineralization, leading to the conclusion that NANF has very high potential for treating toxic chemical wastewaters.

The entrance of even a small amount of phosphorus compounds into natural waters leads to global problems that require the use of modern purification technologies. This paper presents the results of testing a hybrid electrobaromembrane (EBM) method for the selective separation of Cl− (always present in phosphorus-containing waters) and H2PO4− anions. Separated ions of the same charge sign move in an electric field through the pores of a nanoporous membrane to the corresponding electrode, while a commensurate counter-convective flow in the pores is created by a pressure drop across the membrane. It has been shown that EBM technology provides high fluxes of ions being separated across the membrane as well as a high selectivity coefficient compared to other membrane methods. During the processing of solution containing 0.05 M NaCl and 0.05 M NaH2PO4, the flux of phosphates through a track-etched membrane can reach 0.29 mol/(m2×h). Another possibility for separation is the EBM extraction of chlorides from the solution. Its flux can reach 0.40 mol/(m2×h) through the track-etched membrane and 0.33 mol/(m2×h) through a porous aluminum membrane. The separation efficiency can be very high by using both the porous anodic alumina membrane with positive fixed charges and the track-etched membrane with negative fixed charges due to the possibility of directing the fluxes of separated ions in opposite sides.

Recently, metal-organic frameworks (MOFs) have emerged as powerful nanoporous materials for selective separation of complex gas mixtures because of possible modifications of their structural characteristics. Herein, to investigate the effect of MOF functionalization on their gas separation performance at nanoscale, we have performed separation of H2/CH4 mixtures through functionalized and unfunctionalized IRMOF-1 membranes. A molecular-level understanding is developed by employing a dual-force zone nonequilibrium molecular dynamics (DFZ-NEMD) simulation method. The DFZ-NEMD method was validated by performing H2/CH4 separation through IRMOF-1 and comparing these results with experimental and other computational results reported in the literature. The linkers in different directions with respect to the gas flow were functionalized with acetamide, urea, and methyl groups to explore the effect of structural and chemical features of functional groups on gas separation performance. These results show that both the size and chemical nature of a functional group can play an important role in determining the size of the MOF nanopores and thus the selectivity and permeability of an MOF membrane. Moreover, the carbon atoms on the six-membered ring of linkers of IRMOF-1 were systematically functionalized with urea to understand the effect of the position of functional groups on the gas separation performance and mechanism. We show that by changing only this position, one could generate MOF pore entrances with a diverse density of functional groups, generating MOF membranes with different selectivities and permeabilities. Our gas separation results show that the change in this density of functional groups at the pore entrance can further result in different diffusion mechanisms, including Knudsen-type diffusion, adsorption-diffusion, and molecular sieving. Overall, molecular-level insights from the results of this research can pave a path for the synthesis of functionalized MOFs to control the separation of different gas molecules and hydrocarbons from their mixtures. [ABSTRACT FROM AUTHOR]

Amphiphilic nanoparticles can adsorb at interfaces between immiscible phases and form membranes. The ability to handle nanoparticle monolayers/bilayers as freestanding membranes independently from the interfaces on which they form can be of significant practical interest. Janus nanoparticles (JNPs) could generate membranes that have tunable pore size and are amphiphilic. Here it is shown how freestanding membranes from JNPs can be generated. First, strongly amphiphilic Janus nanoparticles that generate foams in surfactant‐free conditions are synthesized. Upon drying the foam lamellae remain as freestanding membranes consisting of perfectly oriented bilayers or monolayers of JNPs, thus providing direct evidence of structural organization of amphiphiles in foam lamellae. The wet foam lamellae can be picked up on grids and upon drying generate freestanding membranes. Sturdy freestanding membranes by transferring monolayers of JNPs from the air–water interfaces onto grids with fine openings are also prepared. [ABSTRACT FROM AUTHOR]

Intrathecal pseudodelivery of drugs is a novel route to administer medications to treat neurodegenerative diseases based on the CSF-sink therapeutic strategy by means of implantable devices. While the development of this therapy is still in the preclinical stage, it offers promising advantages over traditional routes of drug delivery. In this paper, we describe the rationale of this system and provide a technical report on the mechanism of action, that relies on the use of nanoporous membranes enabling selective molecular permeability. On one side, the membranes do not permit the crossing of certain drugs; whereas, on the other side, they permit the crossing of target molecules present in the CSF. Target molecules, by binding drugs inside the system, are retained or cleaved and subsequently eliminated from the central nervous system. Finally, we provide a list of potential indications, the respective molecular targets, and the proposed therapeutic agents.

[Display omitted] Facemasks are considered the most effective means for preventing infection and spread of viral particles. In particular, the coronavirus (COVID-19) pandemic underscores the urgent need for developing recyclable facemasks due to the considerable environmental damage and health risks imposed by disposable masks and respirators. We demonstrate synthesis of nanoporous membranes comprising carbon dots (C-dots) and poly(vinylidene fluoride) (PVDF), and demonstrate their potential use for recyclable, self-sterilized facemasks. Notably, the composite C-dot-PVDF films exhibit hydrophobic surface which prevents moisture accumulation and a compact nanopore network which allows both breathability as well as effective filtration of particles above 100 nm in diameter. Particularly important, self-sterilization occurs upon short solar irradiation of the membrane, as the embedded C-dots efficiently absorb visible light, concurrently giving rise to elevated temperatures through heat dissipation. [ABSTRACT FROM AUTHOR]

The authors have studied the influence of the adsorption and surface diffusion of one component of a binary gas mixture on pore walls on the effect of separation of the gas mixture during its flow through a nanosize porous membrane in a free molecular regime. A capillary porous-medium model obtained by the momentum-balance method was taken as a basis for analysis. Expressions have been determined for the separation factor and the concentration jump of the adsorbed component for an assigned pressure difference on the membrane, which make it possible to analyze the influence of the initial concentration of the adsorbable component and of the temperature on the separation effect. Calculations have been performed of the concentration jump for a number of commercial gas mixtures (CO2/H2, CO/H2, CH4/H2, and N2/He). It has been shown that taking account of surface diffusion may lead to appreciable variations (of several tens of percent) of the obtained values from Knudsen values of the effect in the absence of adsorption. [ABSTRACT FROM AUTHOR]

Silicon nanoporous membranes provide the fundamental underlying technology for the development of an implantable bio-artificial kidney. These membranes, which are comprised of micromachined slit-pores that are nominally 10 nm wide, allow for high-efficiency blood filtration as well as immunoprotection for encapsulated cells. Our approach takes advantage of well-established semiconductor fabrication technology to give us precise dimensional control over pore widths, thereby enabling a highly selective filtration function and a clear path towards further miniaturization. This work builds on our prior results on “ribbed nanoporous membranes” by adding a second-level hierarchy of significantly taller “mega-ribs” to further strengthen the membranes. Relying on a two-step Deep Reactive Ion Etch (DRIE) process, we etch $4~\mu \text{m}$ -deep as well as $40~\mu \text{m}$ -deep trenches into a silicon substrate, grow a thermal oxide liner, and deposit a layer of polysilicon into this “mold” to form membranes which, when released after a backside DRIE etch, feature a network of reinforcing ribs on the underside. We have fabricated and tested freestanding membrane spans that are up to 14 times wider than before, with approximately double the measured permeability per unit area. The new architecture can also improve cross-membrane mass-transfer rates and reduce chip-fabrication costs. [2020-0170] [ABSTRACT FROM AUTHOR]

Salinity gradient power generation has attracted much attention for its green and sustainable advantages. However, previous studies have tended to overlook the effect of reservoir size in porous membrane systems on power generation (the reservoir size from nanometer to micrometer were applied for similar-sized nanochannels). In this work, we investigate the ion transport behavior and working performance in the salinity gradient power generation with different reservoir sizes. The results show that there is a significant dependence of reservoir length and edge height on the effect of salinity gradient power generation. Smaller reservoir length or larger edge height corresponds to weaker ion concentration polarization, larger effective concentration difference, and better power generation performance. The regulation of the energy conversion process by reservoir size is significant. The influence of reservoir size on salinity gradient power generation diminishes as the pore distance increases. Sufficiently large reservoir length and edge height are necessary if a more stable output power is to be obtained. This work illustrates the impact of reservoir size on power generation performance and its significant regulatory effect, providing useful information for future selection of reservoir size in porous membrane systems. [Display omitted] • The reservoir size has a significant influence on salinity gradient power generation. • Rational optimization of reservoir dimensions in porous systems can greatly improve ICP effect. • Smaller reservoir length or larger edge height corresponds to larger effective concentration difference. • The effect of reservoir size on salinity gradient generation decreases with increasing pore distance. [ABSTRACT FROM AUTHOR]

[Display omitted] • GO-based membranes have attracted substantial attention in separation processes. • The dye rejection performance of the GO membranes is critically evaluated. • The membrane stability performance and mechanisms of dye rejection are described in detail. • Technological hurdles are underscored while proposing avenues for future research. In the realm of water treatment, the utilization of two-dimensional (2D) graphene and its derivative, graphene oxide (GO), has emerged as a pioneering avenue for the development of nanoporous membranes. These membranes hold immense promise due to the remarkable attributes inherent to GO, notably its expansive specific surface area and the profusion of oxygen-containing surface functional groups. This comprehensive review elucidates the recent advances in the fabrication and utilization of GO-based membranes, specifically tailored for the efficacious removal of dyes from aqueous environments. A detailed analysis of the key physicochemical characteristics, which distinctly influence the synthesis and performance of GO-based membranes, is performed. Furthermore, a profound explication of the intricate mechanisms underpinning the rejection of dyes by these membranes is presented, accompanied by a thorough investigation into the stability performance of the deployed GO-based membranes. A quick comparison of GO membranes with other 2D materials and the application potential of these membranes in treating real textile effluents is also provided. In the end, salient research gaps are pinpointed, leading to clear suggestions for overcoming the mentioned hurdles. This article aimed to help the research community understand GO-based membranes deeply, and also provide valuable ideas about their growing effectiveness in cleaning dyes from various wastewater sources. [ABSTRACT FROM AUTHOR]

Abstract Herein, we report the surface modification of H 2 O 2 -treated nanoporous alumina (anodic aluminum oxide, AAO) membranes with chitosan (CS) by a solution casting method. Later, copper nanoparticles were incorporated into this CS-AAO membrane by immersion in an aqueous solution of a copper salt precursor and subsequent reduction using NaBH 4. The IR spectra and energy dispersive X-ray spectroscopy (EDS) analyses helped to confirm the presence of CS and copper nanoparticles both on the surface and inside the nanochannels of this AAO membrane (denoted CCSA). Notable differences in the surface energy, surface topography and morphology were observed between the CS-AAO and CCSA membranes. The catalytic performance of the CCSA membrane was tested in the reduction of methylene blue (MB).Our findings revealed that this system adequately combines the attractive properties of supporting of the AAO membranes, ion retention by CS and the catalytic activity of copper nanoparticles into a tridimensional array. Finally, the recyclability of the CCSA membrane was also assessed. The results showed that the performance of this membrane was not dramatically affected after four cycles of use. [ABSTRACT FROM AUTHOR]

This paper reports on a bidirectional Knudsen pump (KP) with a 3D-printed thermal management platform; the pump is intended principally for microscale gas chromatography applications. Knudsen pumps utilize thermal transpiration, where non-viscous flow is created against a temperature gradient; no moving parts are necessary. Here, a specialized design leverages 3D direct metal laser sintering and provides thermal management that minimizes loss from a joule heater located on the outlet side of KP, while maintaining convective cooling on the inlet side. The 3D-KP design is integrative and compact, and is specifically intended to simplify assembly. The 3D-KP pumping area is ≈1.1 cm2; with the integrated heat sink, the structure has a footprint of 64.2 × 64.2 mm2. Using mixed cellulose ester (MCE) membranes with a 25 nm average pore diameter and 525 μm total membrane thickness as the pumping media, the 3D-KP achieves a maximum flow rate of 0.39 sccm and blocking pressure of 818.2 Pa at 2 W input power. The operating temperature is 72.2 °C at ambient room temperature. In addition to MCE membranes, anodic aluminum oxide (AAO) membranes are evaluated as the pumping media; these AAO membranes can accommodate higher operating temperatures than MCE membranes. The 3D-KP with AAO membranes with 0.2 μm average pore diameter and 531 μm total membrane thickness achieves a maximum flow rate of 0.75 sccm and blocking pressure of 496.1 Pa at 9.8 W at an operating temperature of 191.2 °C.

Abstract: Ions transport through confined space with characteristic dimensions comparable to the Debye length has many applications, for example, in water desalination, dialysis, and energy conversion. However, existing 2D/3D smart porous membranes for ions transport and further applications are fragile, thermolabile, and/or difficult to scale up, limiting their practical applicability. Now, polymeric carbon nitride alternatively allows the creation of an ultrathin free‐standing carbon nitride membrane (UFSCNM), which can be fabricated by simple CVD polymerization and exhibits excellent nanofluidic ion‐transport properties. The surface‐charge‐governed ion transport also endows such UFSCNMs with the function of converting salinity gradients into electric energy. With advantages of low cost, facile fabrication, and the ease of scale up while supporting high ionic currents, UFSCNM can be considered as an alternative for energy conversion systems and new ionic devices. [ABSTRACT FROM AUTHOR]

The ability to produce metallic membrane materials with porosity on the nanoscale from Ni‐based superalloys, hitherto used exclusively for high temperature applications, has been discovered 15 years ago. The basic principle is to first convert the initial γ/γ′ microstructure, containing isolated γ′‐precipitates, into a bi‐continuous network where both phases are in themselves continuous and interpenetrate each other. Then, one of the two phases is selectively removed, so that a rigid structure consisting of the remaining phase with pores on the location of the removed phase results. This article reviews the progress made so far. In that time period, a number of ways to fabricate these unique materials have emerged, utilizing 1) single crystals and polycrystals as precursor materials as well as 2) coarsening of coherent and incoherent γ′‐precipitates to realize bi‐continuity of the microstructure. Consequently, a family of superalloy membranes has emerged with specific microstructures, properties, advantages, and limitations. It is the intention of this article to give an overview on these various manufacturing routes, as well as on resulting microstructures and properties. Finally, possible fields of applications are outlined. It is demonstrated that the particular manufacturing process from a solid to the porous material leads to certain advantages, such as the ability to structure the material in porous and solid areas as required by the application. [ABSTRACT FROM AUTHOR]

Poor dispersibility in aqueous media of polymer functionalized one-dimensional materials including carbon nanotubes (CNTs), inorganic nanoparticles and polymer nanofibers is an inherent challenge to their utilization in several applications. Herein, polydopamine grafted CNTs (PDA-CNTs) are rendered dispersible through chemical crosslinking via bioinspired borate chemistry. Nanolayer coatings of polydopamine are deposited on the side walls of CNTs forming aggregates that lead to highly dense and agglomerated PDA-CNTs sediments in aqueous media. Borate crosslinking facilitates the obtainment of a homogeneous dispersion of borate crosslinked PDA-CNTs (B-PDA-CNTs) by forming strong hydrogen bonds in solution and thus permitting the facile fabrication of B-PDA-CNTs membranes with an interconnected nanoporous structure on a macroporous support. The obtained membranes with a controllable thickness are stable and display good ultrafiltration performances of ferritin molecules (>90%) and high water permeability of more than 2.8 × 10 3  L m −2  h −1  bar −1 . The borate chemical crosslinking highlights a versatile approach for the preparation of stable polydopamine coated nanomaterials for wide applications with bio-macromolecules and in nanocomposite materials. [ABSTRACT FROM AUTHOR]

Large-area hexagonal boron nitride (h-BN) promises many new applications of two-dimensional materials, such as the protective packing of reactive surfaces or as membranes in liquids. However, scalable production beyond exfoliation from bulk single crystals remained a major challenge. Single-orientation monolayer h-BN nanomesh is grown on 4 in. wafer single crystalline rhodium films and transferred on arbitrary substrates such as SiO2, germanium, or transmission electron microscopy grids. The transfer process involves application of tetraoctylammonium bromide before electrochemical hydrogen delamination. The material performance is demonstrated with two applications. First, protective sealing of h-BN is shown by preserving germanium from oxidation in air at high temperatures. Second, the membrane functionality of the single h-BN layer is demonstrated in aqueous solutions. Here, we employ a growth substrate intrinsic preparation scheme to create regular 2 nm holes that serve as ion channels in liquids. [ABSTRACT FROM AUTHOR]

Abstract: Treated effluent from an electrically enhanced membrane bioreactor (eMBR) was filtered through MnO2 or TiO2 nanoporous membranes for the removal of residual heavy metals, bacteria, and biological oxygen demand (BOD). The fresh and spent membranes were characterized via energy‐dispersive X‐ray spectroscopy (EDAX), zeta potential analysis, and thermogravimetric analysis (TGA). Water analysis was performed by means of UV/Vis spectrophotometry. For most contaminants, eMBR‐TiO2 showed highest removal efficiency compared to MnO2 because of the combined adhesion and photocatalytic effects of TiO2. Meanwhile, eMBR‐MnO2 provided higher removal efficiency for Fe. [ABSTRACT FROM AUTHOR]

In the present review, we discuss recent advances in the field of nanoporous networks based on polymerisable liquid crystals. The field has matured in the last decade, yielding polymers having 1D, 2D, and 3D channels with pore sizes on the nanometer scale. Next to the current progress, some of the future challenges are presented, with the integration of nanoporous membranes in functional devices considered as the biggest challenge. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to create nanoporouse aluminium oxide membrane which could be used as vibroactive nanofilter in biomedical micro hydraulic devices. This research paper covers the experimental setup of nanoporouse aluminium oxide membrane fabrication and the investigations of its chemical and surface properties. A custom-made anodization experimental setup was used to form membrane with hexagonal pores of 70 nm diameter and 110 nm interpore distance. [ABSTRACT FROM AUTHOR]

• Polymer conical nanopores are prepared using the track-etching technique. • The nanopore acts as an electrochemical valve with on/off conductance states. • Zero-average fluctuating potentials are applied as driving forces. • Cation pumping against an external concentration difference is demonstrated. • A load capacitor characterizes the pumping for a range of experimental data. We study the cation transport against an external concentration gradient (cation pumping) that occurs in conical nanopores when zero-average oscillatory and white noise potentials are externally applied. This pumping, based on the electrically asymmetric nanostructure, is characterized here by a load capacitor arrangement. In the case of white noise signals, the conical nanopore acts as an electrical valve that allows extraction of order from chaos. No molecular carriers, specific ion pumps, and competitive ion-binding phenomena are required. The nanopore conductance on / off states mimic those of the voltage-gated ion channels in the cell membrane. These channels allow modulating membrane potentials and ionic concentration gradients along oscillatory pulses in circadian rhythms and the cell cycle. We show that the combination of asymmetric nanostructures with load capacitors can be useful for the understanding of nanofluidic processes based on bioelectrochemical gradients. [ABSTRACT FROM AUTHOR]

Battery safety has been of critical concerns and there are renewed interest in developing safer membranes for enhancing the inherent safety of lithium ion batteries. In this paper, the synthesis of a robust and safer self‐reinforced composite ultrahigh molecular weight polyethylene (UHMWPE) membrane is described. The self‐reinforced composite membrane consists of ≈200 nm nanopores homogeneously embedded inside interpenetrating nanofibrillar “shish kebab” networks. It performs thermal fuse function by selectively melting its kebab crystals while the elongated shish fibrillary backbones remain intact. Simulated thermal fuse function tests show that the newly prepared separator displays a 300% increase in tensile strength (550 MPa), 300% increase in puncture resistance (1.5 N μm−1), as well as an 18 000 times increase in impedance when lateral dimensions are kept constant. Cells prepared using the UHMWPE separators also exhibit a 10% higher energy density and better cyclability than those using commercial separators. Hence, the newly prepared ultrathin and dimensionally stable membrane will enhance the safety protections for rechargeable batteries with low impedance for high energy and power density.

A general approach is developed for controlling the pore size and pore chemistry of integral isoporous membranes derived from the assembly of polystyrene- b-poly-4-vinyl pyridine (PS- b-P4VP) diblock copolymer. In this approach, initially, the sub-50 nm pore surface, decorated with poly-4-vinyl pyridine (P4VP) polymer brush, is coated with polyacrylic acid (PAA). PAA offers a majority of anionic and a minority of neutral acid functionalities. The neutral acid groups adhere to the P4VP segments of the pore wall through hydrogen bonding interactions and the anionic sites remain free. The availability of the anionic sites sets the stage for a layer-by-layer deposition of cationic and anionic polymers, in a sequential manner, on the pore-wall surface through a continuous flow of a dilute polyelectrolyte solution through the nanoporous membrane. In this way, multiple layers, stabilized through electrostatic interactions, can be deposited leading to a continuous decrease in the pore size and a known surface charge. Due to the known facile nature of the large area isoporous asymmetric membrane formation and modular nature of the polyelectrolyte assembly, the present approach is anticipated to yield new block copolymer membranes with tailored separation, sensing, and catalytic properties. [ABSTRACT FROM AUTHOR]

Extensive nonequilibrium molecular dynamics simulations were carried out to study the transport and separation of binary mixtures of $$\hbox {CO}_2$$ and n-alkane chains in a molecular pore network model of nanoporous carbon molecular-sieve membrane. Separation of both sub- and supercritical mixtures was studied. The membrane was generated atomistically by the Voronoi tessellation of the space, using tens of thousands of atoms. The simulations indicate that there is an optimal pressure drop for separation of mixtures of $$\hbox {CO}_2$$ and n-alkanes, when the mixtures enter the membrane under supercritical conditions. In addition, separation of $$\hbox {CO}_2$$ from n-alkanes becomes increasingly more efficient as the size of the alkane increases. [ABSTRACT FROM AUTHOR]

Surface wettability-tailored porous ceramic/metallic membranes (in the tubular and planar disc form) were prepared and studied for both vapor-phase separation and liquid pervaporative separations of water-ethanol mixtures. Superhydrophobic nanoceramic membranes demonstrated more selective permeation of ethanol (relative to water) by cross-flow pervaporation of liquid ethanol–water mixture (10 wt % ethanol feed at 80 °C). In addition, both superhydrophilic and superhydrophobic membranes were tested for the vapor-phase separations of water–ethanol mixtures. Porous inorganic membranes having relatively large nanopores (up to 8-nm) demonstrated good separation selectivity with higher permeation flux through a non-molecular-sieving mechanism. Due to surface-enhanced separation selectivity, larger nanopore-sized membranes (~5–100 nm) can be employed for both pervaporation and vapor phase separations to obtain higher selectivity (e.g., permselectivity for ethanol of 13.9 during pervaporation and a vapor phase separation factor of 1.6), with higher flux due to larger nanopores than the traditional size-exclusion membranes (e.g., inorganic zeolite-based membranes having sub-nanometer pores). The prepared superhydrophobic porous inorganic membranes in this work showed good thermal stability (i.e., the large contact angle remains the same after 300 °C for 4 h) and chemical stability to ethanol, while the silica-textured superhydrophilic surfaced membranes can tolerate even higher temperatures. These surface-engineered metallic/ceramic nanoporous membranes should have better high-temperature tolerance for hot vapor processing than those reported for polymeric membranes.

In the present review, we discuss recent advances in the field of nanoporous networks based on polymerisable liquid crystals. The field has matured in the last decade, yielding polymers having 1D, 2D, and 3D channels with pore sizes on the nanometer scale. Next to the current progress, some of the future challenges are presented, with the integration of nanoporous membranes in functional devices considered as the biggest challenge.

The entrance of even a small amount of phosphorus compounds into natural waters leads to global problems that require the use of modern purification technologies. This paper presents the results of testing a hybrid electrobaromembrane (EBM) method for the selective separation of Cl - (always present in phosphorus-containing waters) and H 2 PO 4 - anions. Separated ions of the same charge sign move in an electric field through the pores of a nanoporous membrane to the corresponding electrode, while a commensurate counter-convective flow in the pores is created by a pressure drop across the membrane. It has been shown that EBM technology provides high fluxes of ions being separated across the membrane as well as a high selectivity coefficient compared to other membrane methods. During the processing of solution containing 0.05 M NaCl and 0.05 M NaH 2 PO 4 , the flux of phosphates through a track-etched membrane can reach 0.29 mol/(m 2 ×h). Another possibility for separation is the EBM extraction of chlorides from the solution. Its flux can reach 0.40 mol/(m 2 ×h) through the track-etched membrane and 0.33 mol/(m 2 ×h) through a porous aluminum membrane. The separation efficiency can be very high by using both the porous anodic alumina membrane with positive fixed charges and the track-etched membrane with negative fixed charges due to the possibility of directing the fluxes of separated ions in opposite sides.

We designed efficient precursors that combine complementary associative groups with exceptional binding affinities and thiocarbonylthio moieties enabling precise RAFT polymerization. Well defined PS and PMMA supramolecular polymers with molecular weights up to 30 kg mol−1 are synthesized and shown to form highly stable supramolecular diblock copolymers (BCPs) when mixed, in non-polar solvents or in the bulk. Hierarchical self-assembly of such supramolecular BCPs by thermal annealing affords morphologies with excellent lateral order, comparable to features expected from covalent diblock copolymer analogues. Simple washing of the resulting materials with protic solvents disrupts the supramolecular association and selectively dissolves one polymer, affording a straightforward process for preparing well-ordered nanoporous materials without resorting to crosslinking or invasive chemical degradations. [ABSTRACT FROM AUTHOR]

A mathematical model was developed using molecular dynamics to describe the gas mass transfer in membrane nanopores for any Knudsen numbers. Software for describing the mass transfer in membrane nanopores was created based on CUDA technology to take into account the number of molecules (up to 2000000) in a pore and to perform a computational experiment in order to determine the effect of variation of parameters such as the temperature and pressure in the pore, the pore diameter and length, and the mass of the gas on the mass transfer characteristics. [ABSTRACT FROM AUTHOR]

A probabilistic method for evaluating the porosity of nanofiltration and reverse-osmosis membranes developed earlier was tested. A method for calculating the selective porosity of membranes with a rigid structure was proposed. [ABSTRACT FROM AUTHOR]

The influence of surface diffusion on the anisotropy of gas permeation through a two-layer nanoporous membrane has been studied. A model of gas transport in the bilayer membrane for the case of a gas flow composed of free molecular and surface flows has been constructed, wherein the scattering of molecules on the surface is defined by the “white noise” model. The influence of the surface diffusion on the anisotropy of gas permeability through the nanoporous bilayer membrane in the case of anisotropic scattering of gas molecules from the inner surface of the pores has been analyzed. [ABSTRACT FROM AUTHOR]

We demonstrate DNA translocations through silicon nitride pores formed by simple chemical etching on glass substrates using microscopic amounts of hydrofluoric acid. DNA translocations and transmission electron microscopy (TEM) prove the fabrication of nanopores and allow their characterization. From ionic measurements on 318 chips, we report the effective pore diameters ranging from zero (pristine membranes) and sub-nm to over 100 nm, within 50 μm diameter membranes. The combination of ionic conductance, DNA current blockades, TEM imaging, and electron energy loss spectroscopy (EELS) provides comprehensive information about the pore area and number, from single to few pores, and pore structure. We also show the formation of thinned membrane regions as precursors of pores. The average pore density, about 5 × 10 -4 pores/μm 2 , allows pore number adjustment statistically (0, 1, or more). This simple and affordable chemical method for making solid-state nanopores accelerates their adoption for DNA sensing and characterization applications.

Abstract: A two-dimensional model for the mass transport of carbon dioxide from the gas mixture in nanoporous membrane contactors was developed in this work. A solution of 2-amino-2-methyl-1-propanol and piperazine (activator of absorption) is used as a chemical solvent for capture of CO2. The diffusion in the radial and axial direction of the fibers, through the membrane and the shell of membrane contactor was investigated. The convection inside the tube and shell was also investigated along with chemical analysis. Computational fluid dynamics technique was used to solve the model equations including continuity and momentum equations. The predictions of the model were compared with the experimental data and good agreements were observed which confirmed the validity of developed mass transfer model. According to the presented results, an increase in the gas and liquid flow rate results in an increase in the rate of CO2 absorption (at N Re <20). Also, an increase in the concentration of piperazine results in an increase in the CO2 absorption of the gas mixture. This study indicates that the proposed model is capable of predicting the rate of CO2 capture in membrane contactors with good precision. [Copyright &y& Elsevier]

The simulation of fermentation product separation using nanoporous membranes is presented. The aim of the simulation was to predict the performance of an extraction process to remove compounds from aqueous solutions. The simulation was conducted using computational fluid dynamics techniques for the solution of governing equations. The system studied was a membrane-based extractor of acetone from aqueous solutions using near-critical CO2 as solvent. The predicted extraction percentages obtained by the simulations were compared to experimental values reported in the literature and showed very good agreement. The simulation can predict the concentration profile of acetone in the membrane and also predicts the formation of a concentration boundary layer. [ABSTRACT FROM AUTHOR]