A synergy between mechanosensitive calcium- and membrane-binding mediates tension-sensing by C2-like domains

When nuclear membranes are stretched, the peripheral membrane enzyme cytosolic phospholipase A2 (cPLA2) binds via its calcium-dependent C2 domain (cPLA2-C2) and initiates bioactive lipid signaling and tissue inflammation. More than 150 C2-like domains are encoded in vertebrate genomes. How many of them are mechanosensors and quantitative relationships between tension and membrane recruitment remain unexplored, leaving a knowledge gap in the mechanotransduction field. In this study, we imaged the mechanosensitive adsorption of cPLA2 and its C2 domain to nuclear membranes and artificial lipid bilayers, comparing it to related C2-like motifs. Stretch increased the Ca2+ sensitivity of all tested domains, promoting half-maximal binding of cPLA2 at cytoplasmic resting-Ca2+ concentrations. cPLA2-C2 bound up to 50 times tighter to stretched than to unstretched membranes. Our data suggest that a synergy of mechanosensitive Ca2+ interactions and deep, hydrophobic membrane insertion enables cPLA2-C2 to detect stretched membranes with antibody-like affinity, providing a quantitative basis for understanding mechanotransduction by C2-like domains.

Non-Solvent Influence of Hydrophobic Polymeric Layer Deposition on PVDF Hollow Fiber Membrane for CO2 Gas Absorption

The implementation of hydrophobicity on membranes is becoming crucial in current membrane technological development, especially in membrane gas absorption (MGA). In order to prevent membrane wetting, a polypropylene (PP) dense layer coating was deposited on a commercial poly(vinylidene fluoride) (PVDF) hollow fiber membrane as a method of enhancing surface hydrophobicity. The weight concentration of PP pellets was varied from 10 mg mL−1 to 40 mg mL−1 and dissolved in xylene. A two-step dip coating was implemented where the PVDF membrane was immersed in a non-solvent followed by a polymer coating solution. The effects of the modified membrane with the non-solvent methyl ethyl ketone (MEK) and without the non–solvent was investigated over all weight concentrations of the coating solution. The SEM investigation found that the modified membrane surface transfiguration formed microspherulites that intensified as PP concentration increased with and without MEK. To understand the coating formation further, the solvent–non-solvent compatibility with the polymer was also discussed in this study. The membrane characterizations on the porosity, the contact angle, and the FTIR spectra were also conducted in determining the polymer coating properties. Hydrophobic membrane was achieved up to 119.85° contact angle and peak porosity of 87.62% using MEK as the non-solvent 40 mg mL−1 PP concentration. The objective of the current manuscript was to test the hydrophobicity and wetting degree of the coating layer. Hence, physical absorption via the membrane contactor using CO2 as the feed gas was carried out. The maximum CO2 flux of 3.33 × 10−4 mol m−2 s−1 was achieved by 25 mg modified membrane at a fixed absorbent flow rate of 100 mL min−1 while 40 mg modified membrane showed better overall flux stability.

Enhanced production from an Air Gap Membrane Distillation Desalination system by varying the feed entry angle

The membrane distillation (MD) process is an evaporative metho driven by the partial pressure difference between two different temperature solutions, namely the hot feed and the coolant. The hot feed evaporates, and the vapour gets condensed to the cooler side. A hydrophobic membrane maintains the evaporating surface. Air Gap Membrane Distillation(AGMD) separates the hot feed from the coolant by a narrow air gap and a coolant plate. The condensate forms on the coolant plate, and the air gap works as an insulation for the heat loss through the membrane. The salient parameters like feed temperature, coolant temperature, and air gap thickness have already been identified through research in previous years. In this study, an innovative technique has been tested to minimize the polarization and increase the production from an AGMD lab-scale unit. The effect of the feed flow entry angle has been investigated. Also, the combined effect of inclined flow entry and a finned coolant surface has been studied. It has been found from the experiments that with a feed flow entry angle of 60°, the system shows an average of 10% to 14% boost in performance. When 60° inlet flow angle and finned coolant plate work in combination, an average of 69% to 78% increase of distillate flux was observed with the same energy input.

Membrane Distillation: Recent Configurations, Membrane Surface Engineering, and Applications

Membrane distillation (MD) is a developing membrane separation technology for water treatment that involves a vapor transport driven by the vapor pressure gradient across the hydrophobic membrane. MD has gained wide attention in the last decade for various separation applications, including the separation of salts, toxic heavy metals, oil, and organic compounds from aqueous solutions. Compared with other conventional separation technologies such as reverse osmosis, nanofiltration, or thermal distillation, MD is very attractive due to mild operating conditions such as low temperature and atmospheric pressure, and 100% theoretical salt rejection. In this review, membrane distillation’s principles, recent MD configurations with their advantages and limitations, membrane materials, fabrication of membranes, and their surface engineering for enhanced hydrophobicity are reviewed. Moreover, different types of membrane fouling and their control methods are discussed. The various applications of standalone MD and hybrid MD configurations reported in the literature are detailed. Furthermore, studies on the MD-based pilot plants installed around the world are covered. The review also highlights challenges in MD performance and future directions.

Recent Progress on Tailoring and Modification of Membranes for Membrane Distillation: A Review

Membrane distillation (MD) has gained the interest of many researchers since it is a promising method for the separation and purification process. Membrane distillation (MD) is a non-isothermal separation process in which differential vapor pressure between porous hydrophobic membrane surfaces acts as a driving factor. A hydrophobic membrane is used in the application of MD, which permits only the passage of vapor produced on the feed side through its pores to the permeate side. One of the most significant obstacles to the commercialisation of the MD method is a lack of appropriate membranes for the process. On the other hand, conventional hydrophobic membranes are subjected to rapid wetting and severe fouling, mainly when low surface tension compounds are present in saline water, resulting in decreased MD performance. In recent decades, MD membranes have received exceptional scientific interest, with substantial progress being made in the design and production of MD membranes appropriate for use in many applications. This review gives a comprehensive overview of recent research developments in the tailoring morphological structure of hydrophobic membranes, emphasising advancements in the fabrication and modification of membranes towards exhibiting high efficiency in the MD process. In addition, the critical morphology characteristics, mainly surface roughness, wettability, and water contact angle, are analysed. Finally, the challenges faced and future research direction is highlighted.

Insights into Membrane Distillation Application for Textile Wastewater Treatment – A Review

Textile wastewater must be effectively treated with the best available technology prior to release to receiving water bodies to prevent its impact on the environment. Apparently, membrane distillation shows great potential in treating textile wastewater a part of the complexity of the textile wastewater composition. This membrane process enables the water vapour to pass through its porous hydrophobic membrane and retains the concentrated pollutants to be transported. This paper provides data and information from previous studies using membrane distillation to treat textile wastewater. An overview of the development of membrane distillation as well as the fundamental theory is presented. Recent progress in the application of membrane distillation in textile wastewater is then discussed. The final part of the paper looked at the future orientation of this technology to be acceptable in the industrial sector, especially for the textile industry.

The Effect of the Osmotically Active Compound Concentration Difference on the Passive Water and Proton Fluxes across a Lipid Bilayer

The molecular details of the passive water flux across the hydrophobic membrane interior are still a matter of debate. One of the postulated mechanisms is the spontaneous, water-filled pore opening, which facilitates the hydrophilic connection between aqueous phases separated by the membrane. In the paper, we provide experimental evidence showing that the spontaneous lipid pore formation correlates with the membrane mechanics; hence, it depends on the composition of the lipid bilayer and the concentration of the osmotically active compound. Using liposomes as an experimental membrane model, osmotically induced water efflux was measured with the stopped-flow technique. Shapes of kinetic curves obtained at low osmotic pressure differences are interpreted in terms of two events: the lipid pore opening and water flow across the aqueous channel. The biological significance of the dependence of the lipid pore formation on the concentration difference of an osmotically active compound was illustrated by the demonstration that osmotically driven water flow can be accompanied by the dissipation of the pH gradient. The application of the Helfrich model to describe the probability of lipid pore opening was validated by demonstrating that the probability of pore opening correlates with the membrane bending rigidity. The correlation was determined by experimentally derived bending rigidity coefficients and probabilities of lipid pores opening.

Designed ONE-FLOW System for the Synthesis of Rufinamide

A nano-compartmentalized one-solvent (ONE-FLOW) procedure was developed for the two-step synthesis of Rufinamide, employing a combined simulation and experimental approach. Computer-aided solvent selection was combined with reagent/catalyst compartmentalization in a continuous flow set-up. The synthetic route encompassed azidation of benzyl chloride, followed by a Cu-catalyzed azide alkyne cycloaddition (CuAAC) reaction. A functional solvent was chosen via a COSMO-RS based method, which allowed a one-phase reaction while facilitating a thermally induced final product separation from the reaction mixture. To perform azidation and CuAAC reactions in a microfluidic system, both azidation reagent and Cu(I) catalyst were immobilized, on a packed bed and in the hydrophobic membrane of polymer vesicles, respectively, as this allowed a higher reaction efficiency, facile regeneration of azidation reagent, and recovery of the metal catalyst. This ONE-FLOW process has great benefits for the pharmaceutical industry in their quest to scalable, efficient and safe synthetic processes with minimal waste generation.

Facile Fabrication of Multi-Hydrogen Bond Self-Assembly Poly(MAAc-co-MAAm) Hydrogel Modified PVDF Ultrafiltration Membrane to Enhance Anti-Fouling Property

In this work, a facile preparation method was proposed to reduce natural organics fouling of hydrophobic membrane via UV grafting polymerization with methacrylic acid (MAAc) and methyl acrylamide (MAAm) as hydrophilic monomers, followed by multihydrogen bond self-assembly. The resulting poly(vinylidene fluoride)-membranes were characterized with respect to monomer ratio, chemical structure and morphology, surface potential, and water contact angle, as well as water flux and organic foulants ultrafiltration property. The results indicated that the optimal membrane modified with a poly(MAAc-co-MAAm) polymer gel layer derived from a 1:1 monomer ratio exhibited superior hydrophilicity and excellent gel layer stability, even after ultrasonic treatment or soaking in acid or alkaline aqueous solution. The initial water contact angle of modified membranes was only 36.6° ± 2.9, and dropped to 0° within 13 s. Moreover, flux recovery rates (FRR) of modified membranes tested by bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA) solution, respectively, were all above 90% after one-cycle filtration (2 h), significantly higher than that of the pure membrane (70–76%). The total fouling rates (Rt) of the pure membrane for three foulants were as high as 47.8–56.2%, while the Rt values for modified membranes were less than 30.8%. Where Rt of BSA dynamic filtration was merely 10.7%. The membrane designed through grafting a thin-layer hydrophilic hydrogel possessed a robust antifouling property and stability, which offers new insights for applications in pure water treatment or protein purification.