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The regeneration and recycling of discarded membranes are of great importance for extending the membrane lifespan, and thus, they are crucial to achieve the economic feasibility of the industrial scale membrane process. In this research, an end-of-life reverse osmosis (RO) membrane was analyzed, and a cleaning protocol and mechanism were investigated. Several chemical agents were optimized, including acid (H2SO4), base (NaOH), metal-chelating agents (Na2-EDTA), surfactants (SDS), oxidizing agents (KMnO4), and their combinations. The results showed that good regeneration of the membrane can be achieved after the membrane was cleaned by a KMnO4 + NaOH solution, followed by NaHSO3. To achieve a high cleaning efficiency, the effects of oxidant concentration, cleaning time, and solution pH were studied. The optimum cleaning protocol was a 0.5% (w/v) KMnO4 + 0.2% (w/v) NaOH solution, followed by NaHSO3; and the optimum cleaning time was 60 min, allowing for a cleaning efficiency of 5.87. The experimental results showed that the cleaning procedure could be divided into three stages and that both the KMnO4 concentration and pH can control the cleaning stage. Based on economic feasibility, controlling the solution pH with low KMnO4 concentrations could lead to the transformation of membranes into target recycled membranes (such as reverse osmosis, nanofiltration, and ultrafiltration). [ABSTRACT FROM AUTHOR]

This article summarizes a variety of physical mechanisms proposed in the literature, which can generate micro- and nanodomains in multicomponent lipid bilayers and biomembranes. It mainly focusses on lipid-driven mechanisms that do not involve direct protein-protein interactions. Specifically, it considers (i) equilibrium mechanisms based on lipid-lipid phase separation such as critical cluster formation close to critical points, and multiple domain formation in curved geometries, (ii) equilibrium mechanisms that stabilize two-dimensional microemulsions, such as the effect of linactants and the effect of curvature-composition coupling in bilayers and monolayers, and (iii) non-equilibrium mechanisms induced by the interaction of a biomembrane with the cellular environment, such as membrane recycling and the pinning effects of the cytoplasm. Theoretical predictions are discussed together with simulations and experiments. The presentation is guided by the theory of phase transitions and critical phenomena, and the appendix summarizes the mathematical background in a concise way within the framework of the Ginzburg-Landau theory. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider. [ABSTRACT FROM AUTHOR]

[Display omitted] • Damaged RO membranes with 39 ∼ 66% salt rejection ratios rejected PFOA/PFOS by > 85% • Electrostatic repulsion and size exclusion may play key role in PFOA/PFOS rejection. • Upgraded used RO membranes can be an economically sustainable alternative for RO/NF. Removal of per- and polyfluoroalkyl substances (PFAS) from water use cycles has now become an urgent task due to their wide spread in water environment and associated adverse health effects. Despite the effectiveness of nanofiltration (NF) and reverse osmosis (RO) for PFAS removal, the high cost related to the high pressure operation and membrane replacement mostly limit the application in the actual drinking water treatment. In this study, we investigated the rejection of the two most typical PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) by the chlorine treated RO membranes (Dow FILMTEC™ SW30HR) with five different salt rejection ratios from 12% to 66%, which simulated the used membranes upgraded for the permeability. The damaged membranes were further characterized for their contact angle and zeta potential, and elemental composition was analyzed by X-ray photoelectron spectroscopy. The lab-scale cross-flow filtration tests demonstrated that the damaged RO membranes with 39 ∼ 66% salt rejection ratios achieved over 85% rejection of both PFOA and PFOS, which was comparable or even superior performance to that previously reported for NF membranes. Characterization of damaged membranes suggested that electrostatic repulsion and size exclusion both played an important role in the rejection of PFOA and PFOS by the damaged membrane. The present study provides new insights into the energy-efficient and material-saving, thereby economically sustainable, membrane process for the removal of the legacy PFAS. [ABSTRACT FROM AUTHOR]

Microalgae have been identified as a promising renewable feedstock for production of lipids for feeds and fuels. Current methods for identifying algae strains and growth conditions that support high lipid production require a variety of fluorescent chemical indicators, such as Nile Red and more recently, Bodipy. Despite notable successes using these approaches, chemical indicators exhibit several drawbacks, including non-uniform staining, low lipid specificity, cellular toxicity, and variable permeability based on cell-type, limiting their applicability for high-throughput bioprospecting. In this work, we used in vivo hyperspectral confocal fluorescence microscopy of a variety of potential microalgae production strains ( Nannochloropsis sp., Dunaliella salina , Neochloris oleoabundans , and Chlamydomonas reinhardtii ) to identify a label-free method for localizing lipid bodies and quantifying the lipid yield on a single-cell basis. By analyzing endogenous fluorescence from chlorophyll and resonance Raman emission from lipid-solubilized carotenoids we deconvolved pure component emission spectra and generated diffraction limited projections of the lipid bodies and chloroplast organelles, respectively. Applying this imaging method to nutrient depletion time-courses from lab-scale and outdoor cultivation systems revealed an additional autofluorescence spectral component that became more prominent over time, and varied inversely with the chlorophyll intensity, indicative of physiological compromise of the algal cell. This signal could result in false-positives for conventional measurements of lipid accumulation (via spectral overlap with Nile Red), however, the additional spectral feature was found to be useful for classification of lipid enrichment and culture crash conditions in the outdoor cultivation system. Under nutrient deprivation, increases in the lipid fraction of the cellular volume of ~ 500% were observed, as well as a correlated decrease in the chloroplast fraction of the total cellular volume. The results suggest that a membrane recycling mechanism dominates for nutrient deprivation-based lipid accumulation in the microalgae tested. [ABSTRACT FROM AUTHOR]

Abstract: Ganglioside GM1 and its seven potential catabolic products: asialo-GM1, GM2, asialo-GM2, GM3, Lac-Cer, Glc-Cer and Cer, were labeled with tetramethylrhodamine (TMR) to permit ultra-sensitive analysis using laser-induced fluorescence (LIF) detection. The preparation involved acylation of the homogenous C18 lyso-forms of GM1, Lac-Cer, Glc-Cer and Cer with the N-hydroxysuccinimide ester of a β-alanine-tethered 6-TMR derivative, followed by conversion of these labeled products using galactosidase, sialidase, and sialyltransferase enzymes. The TMR–glycolipid analogs produced are detectable on TLC down to the 1ng level by the naked eye. All eight compounds could be separated within 4min in capillary electrophoresis where they could be detected at the zeptomole (ca. 1000 molecule) level using LIF. [Copyright &y& Elsevier]

Abstract: The NMR-visible mobile lipid (ML) signals of C6 glioma cells have been monitored at 9.4 and 11.7 T (single pulse and 136 ms echo time) from cell pellets by 1H NMR spectroscopy. A reproducible behavior with growth has been found. ML signals increase from log phase (4 days of culture) to postconfluence (7 days of culture). This ML behavior is paralleled by the percentage of cells containing epifluorescence detectable Nile Red stained cytosolic droplets (range 23%–60% of cells). The number of positive cells increases after seeding (days 0–1), decreases at log phase (days 2–4), increases again at confluence (day 5) and even further at post-confluence (day 7). C6 cells proliferation arrest induced by growth factors deprivation induces an even higher accumulation of cytosolic droplets (up to 100% of cells) and a large ML increase (up to 21-fold with respect to 4-day log phase cells). When neutral lipid content is quantified by thin-layer chromatography (TLC) on total lipid extracts of C6 cells, no statistically significant change can be detected (in μg/108 cells) with growth or growth arrest in major neutral lipid containing species (triacylglycerol, TAG, diacylglycerol, DAG, cholesteryl esters, ChoEst) except for DAG, which decreased in post-confluent, 7-day cells. The apparent discrepancy between NMR, optical microscopy and TLC results can be reconciled if possible biophysical changes in the neutral lipid pool with growth are taken into account. A cellular explanation for the observed results is proposed: the TAG-droplet-size-change hypothesis. [Copyright &y& Elsevier]

Sorting proteins to their target membranes. The functional polarity of epithelial cells depends upon the selective insertion of proteins and lipids into distinct plasma membrane domains, and upon the maintenance of these specialized domains once they are established during epithelial development. This polarized distribution of important categories of proteins including membrane transporters, channels, enzymes, cell adhesion molecules and junctional components allows cells to carry out the vectorial transport of fluid, ions and other molecules across the epithelial barrier. Several mechanisms are required to ensure the directed movement of membrane components within the cell, and to control their delivery to the appropriate target membrane. These include specific “targeting” cassettes in the amino acid sequence of the transported proteins (such as PDZ domains and NPXY or YRRF domains), a variety of accessory proteins (including GTP-binding proteins) that associate with carrier vesicles and membrane compartments within the cell, and cytoskeletal elements such as microtubules, microfilaments and the spectrin-ankyrin network. Incorrectly folded proteins are retained and degraded within the cell, and many “chaperones” are involved in ensuring that newly-synthesized proteins assume the correct two- and three-dimensional orientations and oligomerization prior to exiting from the endoplasmic reticulum (ER). Many of the proteins involved in neurotransmitter release (for example, synaptobrevins, syntaxins) have homologs that are found in non-neuronal cells, where they play a key role in vesicle fusion with the plasma membrane. In view of the complexity of these trafficking processes, it is not surprising that a growing number of disease pathologies have been identified that involve defective targeting and trafficking of proteins. These diseases can be grouped under the name “sorting disorders,” and they result from abnormal... [ABSTRACT FROM AUTHOR]

In this study, an activation treatment for recycled anion exchange membranes is proposed. Following the circular economy approach, these membranes were prepared by using end-of-life reverse osmosis membranes as mechanical support. The end-of-life membrane was previously used and discarded by desalination plants after overcoming its lifespan. The activation treatment was based on the subsequent immersion of the membranes in diluted acid and alkali solutions. This treatment promoted the complete dissociation of the functional groups in the membrane, making them more reactive to the counter ions. The effects of acid and alkali concentrations and exposition times on the electrochemical properties were studied and the best combination was selected. In such a way, a decrease of 37% in membrane electrical resistance was achieved. The performance of activated and non-activated membranes in brackish water desalination by electrodialysis was compared. The results showed that the proposed activation treatment increased the flux of fresh water more than four-fold (from 1.2 to 4.9 L h−1·m−2), with a considerable reduction of energy consumption (from 5.2 to 3.0 kWh·m−3) and a great improvement in current efficiency (from 38% to 71%). In conclusion, this work shows a simple and low cost methodology for the improvement of the electrochemical properties of recycled electromembranes and thus, their performance in electrodialysis. Image 1 • End-of-life reverse osmosis membranes were used as mechanical support. • Recycled anion exchange membranes were prepared. • The electric resistance of the membranes was decreased by an activation treatment. • Membranes were tested in brackish desalination using electrodialysis. • Performance in desalination of activated and non-activated membranes was compared. [ABSTRACT FROM AUTHOR]