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PVDF membrane has strong hydrophobicity and low anti-pollution performance, greatly limiting its practical application. These drawbacks have been successfully overcome by designing and then preparing a membrane with a semi-interpenetrating polymer (semi-IPN) of PVDF/poly(acrylic acid) (PAA) as the membrane matrix, TiO2 nanoparticles as functional components and F127 as pore-forming agent. The semi-IPN was prepared by copolymerizing acrylic acid with N,N methyl acrylamide in the presence of PVDF, and the TiO2 gel nanoparticles were in situ formed in the membrane-forming process. The properties of the composite membrane were significantly affected by the semi-IPN, F127 and TiO2. By adjusting the membrane structure with the semi-IPN, F127 and TiO2 nanoparticles, we prepared a composite membrane with a water contact angle of 40o, a BSA rejection ratio of 87.5% and a water flux of 802.5 L/m2/h/bar. After a simple UV irradiation, the water flux of this composite membrane rose to 1030 L/m2/h/bar, without any rejection decline. The membrane contaminated by humic acid could recover the water flux up to above 95.3% of its original value by a single UV irradiation, showing a very good antifouling performance. In addition, the composite membrane also exhibited a very strong pollution resistance and separation performance for bovine serum albumin and oil-water emulsion. All in all, based on the synergy of the semi-IPN and the evenly dispersed TiO2 nanoparticles, the prepared composite membrane exhibited excellent comprehensive properties and demonstrated a great potential for various separation applications.

The high concentrations of heavy metal ions in industrial effluents are one of the most challenging wastewaters to deal with. In this study and in order to change the inner diameter of the halloysite nanotubes (HNT), their internal surface was coated by different polymers (polydopamine, polyaniline and polystyrene) and then, the modified nanotubes were incorporated in the polyamide thin film NF membrane for the treatment of metal ions solutions. Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) studies indicated that the internal coating was successful. Furthermore, the neat and modified nanofiltration (NF) membranes were characterized in terms of morphology, contact angle, water flux and metal ion rejection. The modified membranes displayed lower contact angle values (29.4% reduction) that can be linked to the hydrophilic groups in the structure of the coated polymers and the smoother surface of the thin film nanocomposite (TFN) membrane. In addition, the permeation fluxes of the modified membranes were improved significantly (33.4% improvement) without any major reduction in their ion rejection; that shows HNTs act as the channels to transfer water through the membrane structure while the coating of the inner surface of HNT reduces the size of the channel and makes more repulsion and steric hindrance for the ion to pass through the nanotubes. Among the fabricated membranes, the NF membrane with 0.05 wt% polystyrene-coated HNT showed the lowest contact angle (55.30o) and the highest water permeation flux (27.51 L m-2 hr-1), compared to the neat TFC membrane (15.26 L m-2 hr-1) and the NF membrane with 0.05 wt% unmodified HNT (20.62 L m-2 hr-1).

In this study, poly (ether-block-amide) (Pebax) facilitated transport membranes (FTMs) containing aniline, and ionic liquid (IL) modified alumina (M-Al) particles were prepared. Aniline molecules acted as semi-mobile carriers and IL-modified particles as fixed carriers for CO2 molecules in these membranes. Different amounts of M-Al particles were added to the Pebax/aniline (50 wt%) membrane, and a facilitated transport membrane containing 5 wt% M-Al particles was obtained as the optimal membrane. For Pebax/aniline (50 wt%)/M-Al (5 wt%) membrane, CO2 permeability was 167 barrer, and CO2/N2 selectivity was 123 increased by 94% and 168% compared to pure Pebax membrane, respectively. The CO2 separation performance of the prepared FTMs was also evaluated in the humidified state. The results showed that in the presence of water, the amino groups in the structure of aniline and IL performed better and improved the facilitated transport mechanism. Therefore, for all FTMs, CO2 permeability significantly increased in the humidified state so that CO2 permeability and CO2/N2 selectivity reached 406 barrer and 123, respectively, for optimal membrane. The molecular simulation was used to study details of the motion of aniline molecules in the polymeric matrix. The simulation and experimental results confirmed each other and showed that the presence of aniline prevents the hopping mechanism from stopping even at low concentrations of particles as fixed carriers and creates a combined hopping-vehicle mechanism in the membrane structure that results in excellent performance membranes.

In this paper, we demonstrate a new method of fabricating silicon microfluidic channels filled with a porous nanofibrous structure utilizing a femtosecond laser. The nanofibrous structure can act as a membrane used for microfiltration. This method allows us to generate both the microfluidic channel and the fibrous nanostructure in a single step under ambient conditions. Due to laser irradiation, a large number of nanoparticles ablate from the channel surface, and then aggregate and grow into porous nanofibrous structures and fill the channels. Energy dispersive x-ray spectroscopy (EDS) analysis was conducted to examine the oxygen concentration in the membrane structure. Our results demonstrated that by controlling the laser parameters including pulse repetition, pulse width and scanning speed, different microfluidic channels with a variety of porosity could be obtained.

Recent advances in RNA-based medicine have provided new opportunities for the global current challenge, i.e., the COVID-19 pandemic. Novel vaccines are based on a messenger RNA (mRNA) motif with a lipid nanoparticle (LNP) vector, consisting of high content of unique pH-sensitive ionizable lipids (ILs). Here we provide molecular insights into the role of the ILs and lipid mixtures used in current mRNA vaccines. We observed that the lipid mixtures adopted a nonlamellar organization, with ILs separating into a very disordered, pH-sensitive phase. We describe structural differences of the two ILs leading to their different congregation, with implications for the vaccine stability. Finally, as RNA interacts preferentially with IL-rich phases located at the regions with high curvature of lipid phase, local changes in RNA flexibility and base pairing are induced by lipids. A proper atomistic understanding of RNA-lipid interactions may enable rational tailoring of LNP composition for efficient RNA delivery.

Lipid-protein interactions play an important direct role in the function of many membrane proteins. We argue they are key players in membrane structure, modulate membrane proteins in more subtle ways than direct binding, and are important for understanding the mechanism of classes of hydrophobic drugs. By directly comparing membrane proteins from different families in the same, complex lipid mixture, we found a unique lipid environment for every protein. Extending this work, we identified both differences and similarities in the lipid environment of GPCRs, dependent on which family they belong to and in some cases their conformational state, with particular emphasis on the distribution of cholesterol. More recently, we have been studying modes of coupling between protein conformation and local membrane properties using model proteins. In more applied approaches, we have used similar methods to investigate specific hypotheses on interactions of lipid and lipid-like molecules with ion channels. We conclude this perspective with some considerations for future work, including a new more sophisticated coarse-grained force field (Martini 3), an interactive visual exploration framework, and opportunities to improve sampling.

Mixed matrix membranes (MMMs) of cellulose acetate/poly(vinylpyrrolidone) (CA/PVP) infused with acid functionalized multiwall carbon nanotubes (f-MWCNTs) were fabricated by an immersion phase separation technique for hemodialysis application. Membranes were characterized using FTIR, water uptake, contact angle, TGA, DMA and SEM analysis. The FTIR was used to confirm the bonding interaction between CA/PVP membrane matrix and f-MWCNTs. Upon addition of f-MWCNTs, TGA thermograms and glass transition temperature indicated improved thermal stability of MMMs. The surface morphological analysis demonstrated revealed uniform distribution of f-MWCNTs and asymmetric membrane structure. The water uptake and contact angle confirmed that hydrophilicity was increased after incorporation of f-MWCNTs. The membranes demonstrated enhancement in water permeate flux, bovine serum albumin (BSA) rejection with the infusion of f-MWCNTs; whereas BSA based anti-fouling analysis using flux recovery ratio test shown up to 8.4% improvement. The urea and creatinine clearance performance of MMMs were evaluated by dialysis experiment. It has been found that f-MWCNTs integrated membranes demonstrated the higher urea and creatinine clearance with increase of 12.6% and 10.5% in comparison to the neat CA/PVP membrane. Thus, the prepared CA/PVP membranes embedded with f-MWCNTs can be employed for wide range of dialysis applications.

Wave-based active vibration control of a membrane structure by using the Active Sink Method is studied in this paper. Unlike the modal-based vibration control method which attempts to suppress several vibration modes that have already been excited, wave-based active controller can keep vibration modes inactive by stopping the formation of standing waves in the structure. First, the wave transfer matrix is deduced to characterize the wave transmission in the membrane structure. Then, feedforward wave control laws are derived analytically to absorb reflected waves or eliminate transmitted waves. The validity of the proposed active wave controllers is verified through numerical simulations. Simulation results show that by using the active wave controllers no standing waves will be produced in the structure, and the vibration of the membrane structure is suppressed significantly.

Bicontinuous membranes in cell organelles epitomize nature’s ability to create complex functional nanostructures. Like their synthetic counterparts, these membranes are characterized by continuous membrane sheets draped onto topologically complex saddle-shaped surfaces with a periodic network-like structure. Their structure sizes, (around 50–500 nm), and fluid nature make transmission electron microscopy (TEM) the analysis method of choice to decipher their nanostructural features. Here we present a tool, Surface Projection Image Recognition Environment (SPIRE), to identify bicontinuous structures from TEM sections through interactive identification by comparison to mathematical “nodal surface” models. The prolamellar body (PLB) of plant etioplasts is a bicontinuous membrane structure with a key physiological role in chloroplast biogenesis. However, the determination of its spatial structural features has been held back by the lack of tools enabling the identification and quantitative analysis of symmetric membrane conformations. Using our SPIRE tool, we achieved a robust identification of the bicontinuous diamond surface as the dominant PLB geometry in angiosperm etioplasts in contrast to earlier long-standing assertions in the literature. Our data also provide insights into membrane storage capacities of PLBs with different volume proportions and hint at the limited role of a plastid ribosome localization directly inside the PLB grid for its proper functioning. This represents an important step in understanding their as yet elusive structure–function relationship., The SPIRE tool facilitates recognition of bicontinuous phases on transmission electron micrographs, which enables in-depth spatial prolamellar body structure analysis from 2D micrographs.

In nature, the folding and conformation of proteins can control the cell or organelle membrane permeability and regulate the life activities. Here we report the first example of synthetic polypeptide vesicles that regulate their permeability via ordered transition of secondary conformations, in a manner similar to biological systems. The polymersomes undergo a β-sheet to α-helix transition in response to reactive oxygen species (ROS), leading to wall thinning without loss of vesicular integrity. The change of membrane structure increases the vesicular permeability and enables specific transport of payloads with different molecular weights. As a proof-of-concept, the polymersomes encapsulating enzymes could serve as nanoreactors and carries for glucose-stimulated insulin secretion in vivo inspired by human glucokinase, resulting in safe and effective treatment of type 1 diabetes mellitus in mouse models. This study will help understand the biology of biomembranes and facilitate the engineering of nanoplatforms for biomimicry, biosensing, and controlled delivery applications.

Zero-dimensional carbon dots have emerged as important nanofillers for the separation membrane due to their small specific size and rich surface functional groups. This study proposed a strategy based on hydrophobic carbon dots (HCDs) to regulate water channels for an efficient forward osmosis (FO) membrane. Thin-film composite (TFC) membranes with superior FO performance are fabricated by introducing HCDs as the nanofiller in the polyacrylonitrile support layer. The introduction of HCDs promotes the formation of the support layer with coherent finger-like hierarchical channels and micro-convex structure and an integrated polyamide active layer. Compared to the original membrane, TFC-FO membrane with 10 wt% HCDs exhibits high water flux (15.47 L m−2 h−1) and low reverse salt flux (2.9 g m−2 h−1) using 1 mol/L NaCl as the draw solution. This improved FO performance is attributed to the lower structural parameters of HCDs-induced water channels and alleviated internal concentration polarization. Thus, this paper provides a feasible strategy to design the membrane structure and boost FO performance.

MXenes, two-dimensional metal carbides or nitrides with multifunctional surfaces, are one of the most promising antibacterial nanoscale materials. However, their putative bactericidal mechanism is elusive. To study their bactericidal mechanism, we investigated the interaction between a MXene nanosheet and a model bacterial membrane by molecular dynamics simulations and found that an adsorbed MXene on a membrane surface induced a local phase transition in a domain where the fluidity of the phospholipid in this domain at room temperature was comparable with that of the gel phase. The domain also showed a denser and thinner phospholipid membrane structure than the peripheral phospholipids. By comparing it with our previous experiments of the bactericidal activity of MXenes, we proposed the leakage of intercellular molecules at the phase boundary defects as a possible bactericidal mechanism of MXenes that leads to cell lysis. This study provides a useful model for tailoring new bactericidal nanomaterials.

The incorporation of various nanofillers into the interfacial polymerization (IP) process is widely applied to prepare higher performance NF membranes. However, few studies have reported the influence of nanofillers on nanocomposite membrane formation in the IP process. Here, an optical microscope was employed to study the change rule in the 8-NH2-POSS/PSA nanocomposite membrane formation process due to the addition of 8-NH2-POSS nanoparticles. First, the addition of 8-NH2-POSS reduced the diffusion rate of the polyacrylamide hydrochloride (PAH) water phase on the surface against the oil phase because of the interaction with the PAH molecules. Furthermore, the 8-NH2-POSS/PSA nanocomposite membrane structure was more homogeneous and exhibited uniform pinhole defects distribution due to the interaction of the 8-NH2-POSS nanoparticles to the PAH segment. A significant separation performance was observed in the 8-NH2-POSS/PSA nanocomposite membrane due to the hydrophilicity and positive charge of the 8-NH2-POSS nanoparticles. The permeation flux and MgCl2 rejection of the 8-NH2-POSS/PSA nanocomposite membrane increased up to 50.5 L/m2 h at 0.5 MPa and 94.8%, respectively, which corresponded to increases of 73.5% and 8.7% as compared to the pristine PSA membrane. 8-NH2-POSS/PSA nanocomposite membranes have great application potential in the water softening and treatment of divalent metals ions under acidic conditions.

Purpose The study aims to focus on the preparation of a heterogeneous cation exchange membrane by a three-dimensional (3D) method – fused filament fabrication using a series of nozzles of various diameters (0.4–1.0 mm). Polypropylene random copolymer (PPR) as a polymeric binder was mixed with 50 Wt.% of the selected conventional cation exchange resin, and a filament was prepared using a single screw mini extruder. Then filament was processed by FFF into the membranes with a defined 3D structure. Design/methodology/approach Electrochemical properties, morphology, mechanical properties and water absorption properties were tested. Findings Dependence of the tested properties on the used nozzle diameter was found. Both areal and specific resistances increased with increasing nozzle diameter. The same trend was also found for permselectivity. The optimal membrane with permselectivity above 90%, areal resistance of 8 O.cm2 and specific resistance of 124 O.cm2 was created using a nozzle diameter of 0.4 mm. Originality/value Using new materials for 3D print of cation exchange membrane with production without waste. The possibility of producing 3D membranes with a precisely defined structure and using a cheap 3D printing method. New direction of membrane structure formation. 3D-printed heterogeneous cation exchange membranes were prepared, which can compete with commercial membranes produced by conventional technologies. 3D-printed heterogeneous cation exchange membranes were prepared, which can compete with commercial membranes produced by conventional technologies.

Gas permeation through mixed-matrix membranes (MMMs) filled with fillers of non-spherical shapes can be theoretically predicted through different analytical models on the basis of ideal (two-phase) or non-ideal (three-phase) morphology of membrane structure. The predicting capability of different models was evaluated by comparing the estimated carbon dioxide (CO2) permeance through composite membranes against the available experimental permeation data of Ultrason®/ZIF-300, poly(ethersulfone)/functionalized-CNTs and Matrimid®/graphene oxide hybrid membranes. Experimental-to-theoretical discrepancy in CO2 permeability for composite membranes containing fillers of different shapes was determined by calculating percentage average absolute relative error (AARE%) for each model. General order of data fitting for different models while considering typical values of morphological parameters was found as: Maxwell

Vibration sensors are essential for signal acquisition, motion measuring, and structural health evaluations in civil and industrial applications. However, the mechanical brittleness and complicated installation process of micro-electromechanical system vibration sensors block their applications in wearable devices and human-machine interaction. The development of flexible vibration sensors satisfying the requirements of good flexibility, high sensitivity, and the ability to attach conformably on curved critical components is highly demanded but still remains a challenge. Here, we demonstrate a highly sensitive and fully flexible vibration sensor with a channel-crack-designed suspended sensing membrane for high dynamic vibration and acceleration monitoring. The flexible sensor is designed as a suspended vibration membrane structure by bonding a channel-crack-sensing membrane on a cavity substrate, of which the suspended sensing membrane can freely vibrate out of plane under external vibration. By inducing the cracks to be generated in the embedded multiwalled carbon nanotube channels and fully cracked across the conducting routes, the suspended vibration membrane shows high sensitivity, good reproducibility, and robust sensing stability. The resultant vibration sensor demonstrates an ultrawide frequency vibration response range from 0.1 to 20,000 Hz and exhibits the ability to respond to acceleration vibration with a broad response of 0.24-100 m/s2. The high sensitivity, wide bandwidth, and fully flexible format of the vibration sensor enable it to be directly attached on human bodies and curvilinear surfaces to conduct in situ vibration sensing, which was demonstrated by motion detection, voice identification, and the vibration monitoring of mechanical equipment.

Autophagosome biogenesis is an essential feature of autophagy. Lipidation of Atg8 plays a critical role in this process. Previous in vitro studies identified membrane tethering and hemi-fusion/fusion activities of Atg8, yet definitive roles in autophagosome biogenesis remained controversial. Here, we studied the effect of Atg8 lipidation on membrane structure. Lipidation of Saccharomyces cerevisiae Atg8 on nonspherical giant vesicles induced dramatic vesicle deformation into a sphere with an out-bud. Solution NMR spectroscopy of Atg8 lipidated on nanodiscs identified two aromatic membrane-facing residues that mediate membrane-area expansion and fragmentation of giant vesicles in vitro. These residues also contribute to the in vivo maintenance of fragmented vacuolar morphology under stress in fission yeast, a moonlighting function of Atg8. Furthermore, these aromatic residues are crucial for the formation of a sufficient number of autophagosomes and regulate autophagosome size. Together, these data demonstrate that Atg8 can cause membrane perturbations that underlie efficient autophagosome biogenesis. Lipidated Atg8 affects membrane morphology via two aromatic membrane-facing residues that are important for autophagy in budding yeast and mammalian cells.

Current thin film nanocomposite membranes incorporated with microporous particles are demanding for improving membrane performance. In this study, carbon nanotubes (CNTs)-modified poly(ethyleneimine) (PEI)/sodium lignosulfonate (SL) membranes were prepared through layer-by-layer assembly by dispersing CNTs into PEI and/or SL solutions, in order to investigate the effects of CNTs on membrane structure and forward osmosis performance. The characterization results indicated that the CNTs can be well-incorporated in the PEI/SL membranes, which contribute to a slightly lower hydrophilicity of membrane surface and different membrane morphology. The forward osmosis performance of the PEI/SL and CNTs-modified PEI/SL membranes were investigated for application in separating NaCl from water. Compare with the PEI/SL membrane, PEI/(SL–CNTs) membrane prepared by dispersing CNTs into the SL solution exhibited the best water flux and membrane selectivity. The increase in the CNTs content of the PEI/(SL–CNTs) membrane can enhance the water flux, but cannot significantly impact on the reverse salt flux, resulting in the improvement in membrane selectivity. The PEI/(SL–CNTs) membrane containing 0.075 g L−1 CNTs in SL showed a 66.3% higher water flux of 7.32 LMH, also exhibited better antifouling and foulant-release properties. This study offers a new method to design novel FO membranes for desalination and water purification.

Metal-organic framework (MOF) materials have received extensive attention for the design of advanced thin-film nanocomposite (TFN) membranes with excellent permselectivity. However, the relationship between the unique physicochemical properties and performance of engineered MOF-based membranes has yet to be extensively investigated. In this work, we investigate the incorporation of porous zinc-based MOFs (Zn-MOFs) into a polyamide active layer for the fabrication of TFN membranes on porous poly(phenylsulfone) (PPSU) support layers through an interfacial polymerization approach. The actual effects of varying the amount of Zn-MOF added as a nanofiller on the physicochemical properties and desalination performance of TFN membranes are studied. The presence and layout of Zn-MOFs on the top layer of the membranes were confirmed by X-ray photoelectron spectroscopy, scanning electron microscopy, and ζ potential analysis. The characterization results revealed that Zn-MOFs strongly bind with polyamide and significantly change the membrane chemistry and morphology. The results indicate that all four studied TFN membranes with incorporated Zn-MOFs enhanced the water permeability while retaining high salt rejection compared to a thin-film composite membrane. Moreover, the highest-performing membrane (50 mg/L Zn-MOF added nanofiller) not only exhibited a water permeability of 2.46 ± 0.12 LMH/bar but also maintained selectivity to reject NaCl (>90%) and Na2SO4 (>95%), similar to benchmark values. Furthermore, the membranes showed outstanding water stability throughout 72 h filtration and chlorine resistance after a 264 h chlorine-soaking test because of the better compatibility between the polyamide and Zn-MOF nanofiller. Therefore, the developed TFN membrane has potential to solve trade-off difficulties between permeability and selectivity. Our findings indicate that porous Zn-MOFs play a significant role in the development of a TFN membrane with high desalination performance and chlorine resistance.

Abstract Membrane distillation (MD) is a desalination technique that uses a membrane to thermally separate potable water from sea or brackish water. The mass transport processes through the membrane are commonly described by the dusty gas model. These processes are modeled assuming uniform, ideally cylindrical capillaries and are adjusted for the membrane geometry by including porosity and tortuosity. The tortuosity is usually set to 2 or is used as an adjusting parameter to fit theoretical models to experimentally measured data. In this work, ptychographic X-ray computed tomography is employed to map the three-dimensional (3D) structure of three commercial state-of-the-art PTFE membranes in MD. The porosity, tortuosity and permeability (viscous flow coefficient) of the samples are computed using the lattice Boltzmann method. The intrinsic permeability is compared to the dusty gas model and an apparent permeability is proposed which is corrected for Knudsen slip effects at the membrane structure. Article Highlights 3D structure of membranes for distillation measured at full height at an unprecedented detail using X-ray ptychography for the first time. Comparison of the dusty gas model to 3D direct numerical simulation: permeability and Knudsen effects. Membrane characterization and calculation of the hydraulic tortuosity factor from 3D flow field simulations.

Chlorosulfolipids (CSLs) are major components of flagellar membranes in sea algae. Unlike typical biological lipids, CSLs contain hydrophilic sulfate and chloride groups in the hydrocarbon tail; this has deterred the prediction of the CSL membrane structure since 1960. In this study, we combine coarse-grained (CG) and atomistic molecular dynamics (MD) simulations to gain significant insights into the membrane structure of Danicalipin A, which is one of the typical CSLs. It is observed from the CG MD that Danicalipin A lipids form a stable monolayer membrane structure wherein the hydrocarbon moieties are sandwiched by hydrophilic sulfate and chloride groups in both the head and tail regions. On the basis of the mesoscopic structure, we built the corresponding atomistic model to investigate the integrity of the CSL monolayer membrane structure. The monolayer membrane comprising bent lipids shows high thermal stability up to 313 K. The gel-liquid crystalline phase transition is observed around 300 K.

As an alternative to the energy-intensive evaporation-crystallization method, membrane distillation crystallization (MDC) was applied for the first time to obtain calcium nitrate crystals from its aqueous solution. Calcium nitrate solution was obtained through the reaction between calcium carbonate and nitric acid, and then it was concentrated in the membrane distillation (MD) process and further crystallized. The MD step was conducted using hydrophobic polyvinylidene fluoride (PVDF)/sorbitan trioleate (Span 85) membranes. Span 85 was incorporated into the membrane structure in various concentrations to improve the hydrophobicity of membranes, and the resultant membranes were characterized via different methods. In addition, the resultant calcium nitrate crystals were characterized by X-ray fluorescence (XRF) spectroscopy. The MDC results showed that the optimum amount of Span 85 in the polymeric solution was 4%, which led to the formation of a membrane with higher porosity (67.2%) and water contact angle (95.7°) compared to the neat PVDF membrane. The mentioned membrane exhibited the highest water flux in the MD process compared to the other membranes, and also it produced the highest amount of crystals due to its remarkably better performance in the MD step in terms of feed concentration.

The paper presents the results of an experimental study on the effect of high pressures on the transport of liquids through a composite reverse osmosis membrane of an AG-90 industrial membrane module (GE Water & Process Technologies), which membrane consists of a microporous substrate (polysulfone) coated with a selective polyamide layer. It has been found that when a “philic” liquid (water) is forced through the membrane, permeability changes nonlinearly with increasing pressure and passes through an extremum at 7.5 MPa. For the membrane from the AG-90 module, hysteresis during the pressure increasing–decreasing cycle has been observed, which can be associated with irreversible deformation of the membrane structure by interaction with water at high pressures. For “phobic” liquids (glycerol, propanol-1, and propanol-2), the membrane permeability decreases nonlinearly with increasing pressure and this change can be explained in terms of known transport models.

A novel mixed-matrix-composite (MMC) membrane was prepared by incorporating a novel SiO2@CuFe2O4 nanocomposite with a tunable antibacterial property which is synthesized via hydrothermal method, into the pristine membrane structure, in order to achieve the high dye removal performance and antibacterial properties. The results indicated that adding SiO2@CuFe2O4 nanocomposite improved the hydrophilicity, antifouling, and antibacterial properties. The performance of the MMC membranes were evaluated in terms of pure water flux and dye rejection in the filtration process by use of two anionic dyes as the contaminants. The MMC membrane containing 1wt% SiO2@CuFe2O4 nanocomposite, the water flux was about 23 L m−2 h−1and the rejection values were approximately reached to 99% for the both anionic dyes. Also, during the long-term filtration test for stability investigation, the separation efficiencies were maintained with the values of 99.88% Direct blue 199 and 88.99% Acid blue 25 dyes, comparing with the initial time of the filtration performance. High antifouling properties of the MMC membranes, increased the flux recovery ratio (FRR) up to 95%, which is a significant improvement comparing with the neat PES membrane with the value of 65%. The MMC membranes exhibited the relatively high antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria via colony forming unit and disc diffusion methods.

The support flux was first investigated as a separate influencing factor for its effect on performances of ceramic filtration membranes. Three pre-membranes were prepared by tape-casting and then transfer-coated to supports to form dual-layer ceramic membranes after sintering. Experiments demonstrated that membrane layers with almost the same properties were obtained despite the huge difference in support flux. When the support flux increases from 3.120 to 97.53 m3m−2h−1, the flux of these three membrane series have increased by 75%, 186% and 228%, respectively. Experimental rules can provide structural design and evaluation from the perspective of permeability. The limit membrane flux of a certain system was derived according to the resistance distribution law of internal membrane structure and the Darcy's theorem. On this basis, a method for designing support flux was proposed. Furthermore, we present a criterion to quickly and easily evaluate the match between the support and the top layer, which is the ratio of membrane resistance to total resistance. Finally, the filtration resistance of penetration caused by suction of membrane particles into the support was measured for the first time, taking the advantage of the transfer-coating method that inherently free of penetration. Our works are expected to deepen the understanding of the ceramic membrane structure and provided guidance for its rational design and optimization.

Aiming at the problem that the membrane structure is prone to creases in the process of folding and compaction, a proxy model is used to replace the creases to introduce initial defects for the folded membrane to realize the research of the deployment simulation of the membrane. Based on the finite-element method, the Z-folding and deploying process of the membrane is simulated and the elastic-plastic behavior of the crease is parameterized. The ABAQUS connector is used to replace the crease area of the membrane to simulate the characteristics of the crease and its effectiveness is verified. The deployment of Miura-ori membrane is simulated to explore the influence of force driving and constant-speed driving on the deploying process and deployment results of the membrane. In view of the self-contact phenomenon in the membrane deploying process when driven at a constant-speed, referring to the motion trajectory of the membrane loading corner of the force drive, a step-speed driving method is proposed. The research results show that using a step-speed to drive the deployment of folded membrane can reduce the curvature of the membrane surface, solve the problem of membrane self-contact, and eliminate the phenomenon of stress concentration of membrane surface. In addition, compared with other driving methods, the step-speed driving method has a significant advantage in improving the stability of the deploying process of a membrane.

The cell plasma membrane suffers structural disruptions from both daily environmental stresses and trauma. Rapid loss of cell viability occurs if membrane integrity is not rapidly restored. Physiological membrane sealing involves alteration of local intermolecular thermodynamics that is manifested by changes in membrane tension which precede reassembly of the membrane planar bilayer structure. Certain block copolymer surfactants, including poloxamer 188 (P188), have been proven to seal-disrupted cell membranes. However, the specific molecular mechanics of poloxamer-mediated membrane sealing remains a target of investigation. A decrease in membrane tension precedes membrane sealing by natural intrinsic cell sealing processes. The effect of P188 on the quasistatic membrane tension of Madin-Darby canine kidney (MDCK) and Swiss 3T3 fibroblasts cells under normal and saponin-permeabilized conditions was measured using laser optical tweezer (LOT)-extracted membrane tethers. The tether trap length of saponin-permeabilized MDCK cell membranes decreased from an uninjured control of 11.28 ± 1.1 μm to 6.43 ± 0.67 μm. Treatment with P188 (0.2 mM) significantly increased the tether trap length to 9.69 ± 1.0 μm (p < 0.05) while the control polymer, polyethylene glycol (0.2 mM) resulted in tether trap length of 7.02 ± 0.73 μm that was not significantly different. Similar observations were made in the saponin-permeabilized fibroblasts. Corresponding fluorescence cell viability assays revealed that P188-treated cells had a higher survival rate. Thus, surfactant copolymer membrane sealing restores the membrane integrity by decreasing the membrane tension. Cells quickly become non-viable when plasma membrane integrity is lost. Restoring or healing the cell membrane requires alteration in the forces that stabilize the membrane structure. The membrane defect healing processes are preceded by a decrease in membrane interfacial tension. This study demonstrated that amphiphilic block copolymer surfactants, such as poloxamer 188 (P188), reduce membrane tension and promote cell survival. Using laser optical tweezers, this work quantified the effect of surfactant copolymer-catalyzed sealing. Our work utilized laser optical tweezers to demonstrate that copolymer-catalyzed membrane sealing corresponds with a decrease in membrane tension, much like the physiologic response to membrane injury.

In recent trends, membrane structure has increased its applications in space missions due to its significant advantages, such as light in weight, higher folding and packaging efficiency, ease of deployment, and low on-Board volume requirement. The wrinkling and low natural frequency of vibration are the major problems with the membrane structure. This research presents a novel methodology of Kapton-Kevlar material combination for a planar membrane reflector to enhance anti-vibration and anti-wrinkling capabilities of the membrane structure. The comparative study is made for the wrinkle area, RMS error, and natural frequency of vibration with the employed approach. This study provides new insights into a material combination technique to increase performance characteristics of the space-borne membrane reflectors. The outcome of the wrinkling analysis is compared and found to be consistent with the method available in the literature. From the simulation results, it is observed that wrinkles are reduced, and the natural frequency of vibration is also increased significantly with the proposed method.

Pulping and papermaking generate large amounts of waste in the form of lignosulfonates which have limited valorized applications so far. Herein, we report a novel lignosulfonate‐based nanofiltration membrane, prepared by using polyethylenimine (PEI) and sodium lignosulfonate (SL) via a layer‐by‐layer (LbL) self‐assembly. As a low‐cost and renewable natural polyelectrolyte, SL is selected to replace the synthetic polyelectrolyte commonly used in the conventional LbL fabrication for composite membranes. The prepared LbL (PEI/SL)7 membranes were crosslinked by glutaraldehyde (GA) to obtain (PEI/SL)7‐GA membranes with compact selective layer. We characterized (PEI/SL)7 and (PEI/SL)7‐GA membranes to study the chemical compositions, morphologies, and surface hydrophilicity. To improve the nanofiltration performances of the (PEI/SL)7‐GA membranes for water desalination, we investigated the effects of the crosslinking time, GA concentration and the NaCl supporting electrolyte on membrane structure and performance. The optimized (PEI/SL)7‐GA membrane exhibited a permeating flux up to 39.6 L/(m2·h) and a rejection of 91.7% for the MgSO4 aqueous solution 2.0 g/L concentration, showing its promising potential for water desalination. This study provides a new approach to applying the underdeveloped lignin‐based biomass as green membrane materials for water treatment.

A simple and effective damage constitutive model for PVC-coated fabrics be developed, which could be used to predict the nonlinear mechanical response of membrane structures under tension more accurately. In this paper, based on continuum damage mechanics theory, a nonlinear damage constitutive model for PVC-coated fabrics was established. Firstly, the off-axis tensile tests were carried out on the membrane material at 0 °, 15 °, 30 °, 45 °, 60 °, 75 °, and 90 ° with an electronic universal tensile testing machine, and the tensile curves of seven specimens were obtained. Then, the Helmholtz free energy function is constructed based on the continuum damage mechanics theory and the existing research foundation, and the constitutive equation of the material is derived. Then, according to the characteristics of the off-axial tensile test curve of the coated fabrics, a damage evolution equation for the materials under tension was established with strain as an independent variable. By compiling a MATLAB program of the constitutive model, the parameters were obtained, and the off-axial tensile test curves of PVC-coated fabrics were predicted. The constitutive model was compiled using the user-defined subroutine UMAT in ABAQUS, and the correctness of the model was verified by simulating a static loading test of the membrane structure under in-plane tension. The model shows a good performance in computation and the obtained results are also in good agreement with experimental data. These features enable the proposed model to be used in numerical calculations for membrane structures.

Crosslinker is a vital factor for the preparation of polymeric membranes, which has a substantial effect not only on the membrane-forming process, but also on the membrane structure as well as separation performance. However, little attention has been paid on UV-crosslinked membrane for organics pervaporation. In this work, the effect of crosslinker 3-methacryloxypropylmethyldimethoxysilane (KH571) on (1) the UV-crosslinking kinetics was characterized by real-time infrared spectroscopy and photo-rheology, (2) the membrane structure was characterized by crosslinking density, and (3) separation performance was evaluated by ethanol pervaporation. Moreover, the conventional polydimethylsiloxane (PDMS) was replaced by polydimethylsiloxane-poly[(3,3,3-trifluoropropyl)methylsiloxane] (PDMS-PTFPMS) block copolymer, where the strong C–F bond contributes to enhance membrane hydrophobicity. Results show an ultrafast membrane-forming process (30−50 s) for all coating solution systems and an outstanding separation performance, including 11.3 of ethanol separation factor and 1149 g m−2 h-1 of total flux for pervaporation recovery of 5 wt% ethanol/water solution at 60 °C.

Ion exchange membrane plays a crucial role in transforming and upgrading traditional chemical manufacturing procedures and boosting a multitude of new applications. Due to the strict regulations on wastewater discharge and increasing demands of renewable energy, anion exchange membrane (“A” membrane), bipolar membrane (“B” membrane) and cation exchange membrane (“C” membrane) have become a key material for upgrading various process industries. Herein, we summarized several novel synthetic routes for “ABC” membranes fabrication from the viewpoints of designing novel membrane synthetic routes, regulating the ionic transport channels, imparting dynamic transfer regions, introducing intrinsic micro‐porosity into the membrane and among others. The account includes a brief introduction to membrane structure designs and fabrications, emerging and industrial applications, and perspectives on ion exchange membranes.

The development of microorganisms and formation of thrombus on a biomaterial surface can seriously lead to device failure and threaten human health. Nonetheless, a surface that has both antibacterial and anticoagulant properties has scarcely been developed. Herein, a novel dual-action membrane composed of polyethersulfone (PES) bulk material and a hydrophilic anionic poly-2-acrylamido-2-methylpropanesulfonic acid (PAMPS) polymer has been prepared via the cationic antibacterial agent poly(hexamethylene biguanide) (PHMB)-induced phase separation technique. Interestingly, the resultant membrane can offer tunable antibacterial and anticoagulant properties, while maintaining satisfactory permeability and greatly increasing selectivity. The membrane also shows excellent hydrophilicity, a well-defined porous surface, and cross section with a sponge gradient structure. Furthermore, the PHMB-PAMPS complex formed on the membrane surface displays outstanding long-term stability, which is crucial for further practical applications. More importantly, the hollow fiber membrane fabricated by the cationic polyelectrolyte-induced phase separation technique confirms its capability to control the membrane permeability (257.4 L·m-2·h-1·bar-1) and selectivity (95.9%) without destroying the membrane structure. The present work opens a straightforward and efficient avenue for the rational design of a functional surface to fight biomedical material-associated infections.

The output acoustic energy of a capacitive micromachined ultrasonic transducer (CMUT) can be enhanced by adjusting its membrane structure. In this paper three dissimilar membranes shapes of CMUT: circular, rectangular and hexagonal, were aimed and 3D finite element method simulated using adaptive meshing technique. The displacement as well as strain and stress outputs for a single membrane and an array of four membranes on a single substrate were obtained. The simulated results are supported by analytical modeling. A static bias of 40 V and a signal of amplitude 100 mV are employed. A pressure of 8603.98 N/m2 resulting in a force of 16.894 µN was applied at the membrane. Fixtures were provided on every possible face of the structure except the face 1 (membrane). The outcomes showed that the membrane displacement is highest for a circular geometry under same uniform pressure and area of vibration. Moreover as the distance between the elemental membranes increases the displacement decreases for circular and hexagonal membranes while the reverse behavior is observed for rectangular membranes.

Mutations in thePRPH2gene encoding the photoreceptor-specific protein PRPH2 (also known as peripherin-2 or rds) cause a broad range of autosomal dominant retinal diseases. Most of these mutations affect the structure of the light-sensitive photoreceptor outer segment, which is composed of a stack of flattened “disc” membranes surrounded by the plasma membrane. The outer segment is renewed on a daily basis in a process whereby new discs are added at the outer segment base and old discs are shed at the outer segment tip. New discs are formed as serial membrane evaginations, which eventually enclose through a complex process of membrane remodeling (completely in rods and partially in cones). As disc enclosure proceeds, PRPH2 localizes to the rims of enclosed discs where it forms oligomers which fortify the highly curved membrane structure of these rims. In this study, we analyzed the outer segment phenotypes of mice of both sexes bearing a single copy of either the C150S or the Y141C PRPH2 mutation known to prevent or increase the degree of PRPH2 oligomerization, respectively. Strikingly, both mutations increased the number of newly forming, not-yet-enclosed discs, indicating that the precision of disc enclosure is regulated by PRPH2 oligomerization. Without tightly controlled enclosure, discs occasionally over-elongate and form large membranous “whorls” instead of disc stacks. These data show that the defects in outer segment structure arising from abnormal PRPH2 oligomerization are manifested at the stage of disc enclosure.SIGNIFICANCE STATEMENTThe light-sensitive photoreceptor outer segment contains a stack of flattened “disc” membranes that are surrounded, or “enclosed,” by the outer segment membrane. Disc enclosure is an adaptation increasing photoreceptor light sensitivity by facilitating the diffusion of the second messenger along the outer segment axes. However, the molecular mechanisms by which photoreceptor discs enclose within the outer segment membrane remain poorly understood. We now demonstrate that oligomers of the photoreceptor-specific protein peripherin-2, or PRPH2, play an active role in this process. We further propose that defects in disc enclosure because of abnormal PRPH2 oligomerization result in major structural abnormalities of the outer segment, ultimately leading to loss of visual function and cell degeneration in PRPH2 mutant models and human patients.

The thermobaric and concentrational stresses, which arise during the operation of a membrane element under cyclic conditions, can result in the violation of the integrity of a membrane comprising an element and in failure of the element. Studies of the effect of thermobaric cycling in a hydrogen atmosphere at operating parameters (pressure differential, temperature, time of operation) on the properties of membranes allow us to determine the optimum operation conditions of the membrane element. The stability of the Pd–6 wt % In–0.5 wt % Ru–1 wt % Co membrane structure is estimated using the studied temperature dependence of the specific hydrogen permeability of the membrane during its operation in a hydrogen atmosphere, and the possibility of efficient operation of the membrane under given conditions in a temperature range of 250–600°C is noted. The surface of the Pd–6 wt % In–0.5 wt % Ru–1 wt % Co membrane subjected to thermobaric cycling in a commercial-purity hydrogen atmosphere is studied by atomic force microscopy and X‑ray diffraction analysis.

Literature data about qualitative composition of the classes of polar lipids constituting plant cell membranes are discussed. A diversity of classes of phospho-, glyco-, and other lipids and hydrophobic compounds lacking acyl groups are given. Fatty acid composition of polar lipids, composition of amino alcohols as components of glycosphingolipids, and oxyacids abundant in cerebrosides are considered. A key role of saturated fatty acids in the creation of an optimal physical state of membranes necessary for their normal operation is emphasized. A necessity and feasibility of construction of 3D models of biomembranes is stressed. A logic approach is proposed to a better understanding of the role of qualitative diversity of lipid composition in membrane organization. Materials showing a possibility of chemical and biological transformation of lipids in plants are cited. Several issues of membrane structure, including microdomains, remodeling of bilayer, and vesicular traffic are addressed.

Characterization of the internal morphology of thin film composite membranes used in reverse osmosis (RO) is a prerequisite for understanding the connection between microstructure and water transport properties and is necessary for the design of membranes with improved performance. Here, we examine a series of fully aromatic polyamide active layers of RO membranes that vary in crosslinking using a combination of resonant soft X-ray scattering (RSoXS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Analysis of RSoXS profiles reveals a correlation between membrane structure and crosslinking density. Through a combination of scattering contrast calculations, TEM, and AFM micrographs, we assign the dominant contribution to RSoXS data as either surface roughness or chemical heterogeneity, depending on the X-ray energy used. Altogether, our results demonstrate the utility of soft X-ray scattering to examine the microstructure of water filtration membranes.

Biological membrane, the most fluidic structure of a cell or an organelle, refrains the cells to progress toward apoptosis by sustaining their optimum environment. This bilayer-membrane equips all machineries required for cellular communication, limits the entry of foreign bodies, selectively transports molecules or ions depending on the need of the system but, it also acts as a first line defense against environmental insults. Due to the presence of a vast number of poly unsaturated fatty acids (PUFA), the biological membrane is highly prone to oxidative stress and as a consequence, acceleration in lipid peroxidation by free radicals, becomes a threat to cellular viability. Alterations in the biophysical state of bilayer caused by oxidative stress frequently occur in the in vivo as well as in vitro conditions. It has been well documented that the molecule, melatonin, exhibits profound coherence in neutralizing oxidative stress and thus, to normalize fluidity status of biological membranes. Aging associated decline in melatonin level with subsequent ascended lipid peroxidation and membrane viscosity found in almost all organisms further suggest the importance of melatonin in this context. Since disruption of membrane structure or even some modifications will cause a spectrum of diseases, keeping membrane intactness would be an adequate strategy to prevent these diseases. Considering the high permeability, safe and potent antioxidant capacity of melatonin, this molecule can be a superlative choice to alleviate membrane bilayer rigidity and its related ailments.

There is ample evidence that both native functions and pathogenic aggregation of α-synuclein are intimately dependent on lipid interactions and fatty acid type; the regulatory mechanism however remains unclear. In the present work, using extensive atomistic molecular dynamics simulations and enhanced-sampling, we have focused on exploring the mechanism of fatty acid dependent regulation of monomeric α-Syn100 in a native synaptic vesicle-like membrane. Our results show that α-Syn100 spontaneously binds to the membrane through its N-terminal region (residues 1-34), where the depth of membrane insertion, the structure, and orientation of the membrane-bound α-Syn100 and its impact on membrane structure are modulated by docosahexaenoic acid (DHA). DHA is a polyunsaturated fatty acid abundantly found in the brain and known to promote the oligomerization of α-synuclein. We found that DHA exhibits marked propensity to interact with monomeric α-Syn100 and modulates the microenvironment of the protein by preferentially sorting DHA-containing phospholipids, depleting other phospholipids and cholesterol as well as increasing the proportion of anionic to neutral lipids in the immediate vicinity of the protein. Owing to the unique conformational flexibility, DHA chains form more lipid-packing defects in the membrane and efficiently coat the membrane-embedded surface of the protein, compared to the saturated and monounsaturated fatty acids. DHA thus makes the bilayer more amiable to protein adsorption and less prone to α-synuclein-induced perturbation associated with cytotoxicity. Indeed, in the absence of DHA, we observed significant thinning of the local bilayer membrane induced by α-Syn100. Though α-Syn100 is predominantly α-helical in membranes studied here, in the presence of DHA we observe formation of β-sheet/β-strands in the C-terminal region (residues 35-100) of α-Syn100, which is extended out from the membrane surface. Notably, DHA induces β structure in the NAC domain of α-Syn100 and promotes extended conformations as well as large solvent exposure of this hydrophobic domain, properties that are known to facilitate self-assembly of α-synuclein. To the best of our knowledge, this study for the first time provides the atomistic insights into DHA-induced regulatory mechanism of monomeric α-synuclein, having implications in protein structure and its physiological/pathological functions.

Membrane phospholipid metabolism forms lysophospholipids, which possess unique biochemical and biophysical properties that influence membrane structure and dynamics. However, lysophospholipids also function as ligands for G-protein–coupled receptors that influence embryonic development, postnatal physiology, and disease. The 2 most well-studied species—lysophosphatidic acid and S1P (sphingosine 1-phosphate)—are particularly relevant to vascular development, physiology, and cardiovascular diseases. This review summarizes the role of lysophosphatidic acid and S1P in vascular developmental processes, endothelial cell biology, and their roles in cardiovascular disease processes. In addition, we also point out the apparent connections between lysophospholipid biology and the Wnt (int/wingless family) pathway, an evolutionarily conserved fundamental developmental signaling system. The discovery that components of the lysophospholipid signaling system are key genetic determinants of cardiovascular disease has warranted current and future research in this field. As pharmacological approaches to modulate lysophospholipid signaling have entered the clinical sphere, new findings in this field promise to influence novel therapeutic strategies in cardiovascular diseases.

Oxidative stress can damage organs, tissues, and cells through reactive oxygen species (ROS) by oxidizing DNA, proteins, and lipids, thereby resulting in diseases. However, the underlying molecular mechanisms remain to be elucidated. In this study, employing scanning ion conductance microscopy (SICM), we explored the early responses of human embryonic kidney (HEK293H) cells to oxidative DNA damage induced by potassium chromate (K(2)CrO(4)). We found that the short term (1−2 h) exposure to a low concentration (10 μM) of K(2)CrO(4) damaged the lipid membrane of HEK293H cells, resulting in structural defects and depolarization of the cell membrane and reducing cellular secretion activity shortly after the treatment. We further demonstrated that the K(2)CrO(4) treatment decreased the expression of the cytoskeleton protein, β-actin, by inducing oxidative DNA damage in the exon 4 of the β-actin gene. These results suggest that K(2)CrO(4) caused oxidative DNA damage in cytoskeleton genes such as β-actin and reduced their expression, thereby disrupting the organization of the cytoskeleton beneath the cell membrane and inducing cell membrane damages. Our study provides direct evidence that oxidative DNA damage disrupted human cell membrane integrity by deregulating cytoskeleton gene expression.

We report on the fabrication of the defect-free mixed-matrix membrane (MMM) based on the polyethylenimine (PEI) matrix with uniformly dispersed metal-organic framework (MOF) filler UiO-66-NH2, covalently bonded by polyvinylpyrrolidone (PVP). The key feature of the molecular level-controlled filler deposition in prepared UiO-66-NH2-PVP-PEI membranes was bridging the MOF particles to the PEI polymer matrix via PVP polymer chains. Such an approach improved the polymer-filler interface interactions and boosted the MOF dispersion into the polymer matrix for higher MOF loadings up to 23 wt %. The overall membrane structure and properties were characterized using FTIR, XRD, TG, DSC, SEM and 3D optical profiler techniques. Obtained results revealed the uniform dispersion of UiO-66-NH2, the strong polymer-filler interface interactions and entanglement of PEI with UiO-66-NH2-PVP. Furthermore, the outstanding CO2/H2 separation performance was determined for the UiO-66-NH2-PVP-PEI membrane with 18 wt % of MOF loading; the average CO2 permeability of 394 Barrer and the separation factor of 12 for circa 100 h of the membrane testing overcome the 2008 Robeson reverse upper bound limit. Such improved CO2/H2 separation performance was achieved due to the combination of the diffusion-solution mechanism with the preferential adsorption of the CO2 via the reversible bicarbonate reaction with amino groups of the UiO-66-NH2 and PEI which acts as fixed CO2 carrier sites in MMM structure.

Polysulfone is among the polymers known for excellent electrical resistivity, elongation capacity, transparency and thermal resistance. Polysulfone is being used in battery caps, oil pumps, oil control pistons, transmission parts, water treatment, etc. The focus of the presented work is to control the porosity level of polysulfone membranes through plasma treatment for water treatment application. Polysulfone membrane was fabricated using phase inversion method and treated with microwave plasma of oxygen under fixed plasma conditions. The membrane samples were plasma treated for 15 s to 30 s and analyzed for surface morphology, pore size distribution and functional groups. Presence of benzene rings, sulfonic groups and phenols groups in the samples were observed in a range of 855–1000 cm−1, 1290–1360 cm−1 and 3250–3420 cm−1, respectively. The blank sample had wider pore size distribution (3–18 µm) while plasma treated samples exhibited narrow pore size distribution. The pore size distribution after 15 s and 30 s of treatment ranged from 3 to 9 µm and 3 to 5 µm, respectively. Conclusively, uniform pore size distribution was possible after 30 s of plasma treatment.

This paper proposes a method to derive the upper-bound vibration spectrum of a membrane structure from a few selected point measurements. The upper-bound spectrum exceeds the measured spectra by a ...

In recent years, the construction of enclosed material yard projects has becoming an urgent requirement to improve ecological environment and living environment quality. Thin membrane structures have been widely used in industrial building, especially for storage building roofs. Due to the thermal-optical properties of translucent thin fabric material, such as the absorption and transmittance of solar radiation, the indoor thermal environment is seriously disturbed. Moreover, membrane building structures are usually irregular. Compared with conventional buildings material, the translucent thin fabric material particularly responsive to changes in external environment conditions. As a result, the solar radiation heat gain calculation of membrane buildings is complicated. It is worth exploring measures to tackle this problem. Therefore, in order to solve the problem that the relevant thermal-optical parameter is difficult to obtain. The 13 thin membrane samples were tested and the thermal optical characteristic parameters were analyzed in this paper. A practical enclosed membrane structure building was selected as the research object. In addition, a solar radiation heat transfer model was established. The indoor solar heat gain under the action of solar radiation heat was calculated and the effect of different light transmittance and absorptance on the indoor radiation heat gain was studied. It can provide reference for heat gain calculation and ventilation design of membrane structure storage buildings.

The implementation of the pore-forming agent in the polymeric membrane has been applied for ages in enhancing the characteristics and performance of mixed matrix membrane. In this work, chlorophyll extracted from spinach has been used as an additional pore-forming agent alongside polyethylene glycol (PEG) to improve the polysulfone's pore structure (PSf) mixed matrix membrane. The effect of chlorophyll was investigated in terms of characteristics and performance of the mixed matrix membrane. As a result, the cross-section morphologies show that the pore structure was enhanced significantly inside the membrane structure for 0.25 wt% chlorophyll concentration, thus resulted in better hydrophilicity, surface roughness, and membrane porosity value. Plus, the permeation and rejection performance was increased drastically due to the pore formation inside the mixed matrix membrane structure. These results prove that the addition of chlorophyll with low concentration managed to improve the characteristics and performance of the fabricated mixed matrix membrane.