Heavy Membrane Research Articles

Surface implantation of ionically conductive polyhydroxyethylaniline on cation exchange membrane for efficient heavy metal ions separation

Extraction of heavy metal ions from aqueous could enable recycling of wastewater and reusing of high-value ion resources. Recently, electrodialysis (ED) technology has been applied in the removal of heavy metal ions from wastewater, however, developing high-efficient and stable heavy metal ions selective cation exchange membrane (CEM) remains an elusive challenge. Herein, we demonstrate the fabrication of high-efficient cations selective CEM with the surface implantation of ionically conductive polyhydroxyethylaniline (PANI-OH) on a commercial CEM membrane (CTG) containing sulfonic acid groups via the electrostatic attraction. Implanted hydrophilic and positively charged PANI-OH facilitates fast and selective transfer of Cu2+ over Zn2+ cations through the membrane. Meanwhile, the synergistic effect of rigid conjugate structure and hydrogen-bond interaction of PANI-OH renders the resultant membrane CTG-PANI-OH with stable structure and separation performance. As such, the Cu2+/Zn2+ permselectivity of CTG-PANI-OH membrane is ~1.70, which is about 190 % of that of the pristine CTG membrane. This work provides a facile design and strategy for the construction of high-efficient cations selective CEMs with great application prospects in the purification and extraction of heavy metal ions from wastewater.

Using of Integrons as Biomarker to Assess Dissemination and Diversity of Antimicrobial Resistance Genes in Farm Animal Manure

Antimicrobial agents are widely used for treatment of animal and human diseases. Heavy use of antimicrobial agents permits bacteria to develop resistance to these agents specifically when a dose of antibiotic is insufficient or course of treatment is incomplete. Antimicrobial resistance genes (ARGs) are usually associated with mobile genetic elements (MGEs) including Integron therefore; these genes can transmit among bacteria via horizontal transmission. The current study was conducted to assess the possible role of manure in dissemination of antimicrobial resistance. The presence, quantitate, and diversity of resistance genes associated with Integron class 1 have been assessed using conventional and quantitative polymerase chain reaction (PCR) combined with sequencing of gene cassette within Integron and analysis of sequenced data by blast tool. Thirty-eight samples were found a positive for Integron and concentration of Integron in positive sample ranged from from 106-1010 copies/g of manure. High frequencies were detected to genes that encoded to sulphonamide and ammonium compound resistance. These genes were detected in 25% and 23% respectively of the total manure samples. In general, the detected genes in manure functionally belong to five protein families including Efflux pump, DNA repair, heavy metal resistance, membrane protein, and antibiotic resistance. Manure might act as a hotspot from which ARGs emerge and transfer to the environment and then to the animal and human environments.

Heavy Metal Stress Tolerance by Serratia nematodiphila sp. MB307: Insights from Mass Spectrometry-based Proteomics

Background: Heavy metals impact living organism deleteriously when exceed the required limits. Their remediation by bacteria is a much pursued area of environmental research. In this study, we explored the quantitative changes for four heavy metals (Cadmium, Chromium, Zinc, Copper), on global and membrane proteome of gram negative S. nematodiphila MB307. This is a versatile bacterium, isolated from rhizosphere of heavy metal tolerating plant and equipped with characteristics ranging from useful biopeptide production to remediation of metals. Methods: We explored changes in its static end products of coding DNA sequences i.e. proteins after 24 incubation under metal stress, using LC-MS/MS. Data analysis was done using MaxQuant software coupled with Perseus package. Results: Up and downregulated protein fractions consisted prominently of chaperones, membrane integrity proteins, mobility or transporter proteins. Comparative analysis with previously studied bacteria and functional contribution of these proteins in metal stress offers evidence for survival of S. nematodiphila under high concentrations of selected metals. Conclusion: The outcomes validate that this soil derived bacterium is well attuned to remove these metals from soil, water and may be additionally useful for boosting phytoremediation of metals. This study delivers interesting insights and overlays ground for further investigations into mechanistic activity of this bacterium under pollutant stress.

Application of ZIF-8 nanocomposite membrane in microbial desalination cells for simultaneous heavy metal removal and biofouling prevention

Microbial desalination cells (MDC) syndicate the advantage of physical separation by using membranes to create conditions required for Bioelectrochemical processes for the treatment of various domestic and industrial wastewater, while simultaneously desalinating saline water and generating bioenergy. However, since the introduction of this technology, heavy metal removal has been a challenge, and membrane fouling has become a major bottleneck limiting the optimum performance and efficiency of this technology. This study incorporated the use of ZIF-8 nanocomposite membrane via phase inversion mechanism in MDC for simultaneous heavy metal removal and membrane biofouling prevention. The study was conducted in two MDC systems; MDC-Control (without the ZIF-8 nanocomposite membrane) and MDC with ZIF-8 nanocomposite membrane. The results from the experiment shown that maximum removal efficiency of 85.7%, 84.3%, 84.0%, and 90.61% was obtained for Cu2+, Zn2+, Pb2+, and Cd2+ respectively in MDC-ZIF-8, while MDC control showed 54.17%, 59.71%, 51.94%, and 54.17%. The results were well fitted to the Langmuir adsorption isotherm with correlation coefficients (R2) > 0.99 in all cases for MDC-ZIF-8. A maximum adsorption capacity (Qmax) of 292 mg g−1 was attained for all four metal ions in MDC-ZIF-8. Besides, after 38 days of continuous operation with two complete desalination for both systems, the SEM-EDS characterization analysis, polarization characteristics, and power generation revealed antifouling characteristics of ZIF-8 nanocomposite membrane incorporated in MDC. The integration of the ZIF-8 nanocomposite membrane proved to be simultaneously efficient in biofouling prevention and heavy metal removal without jeopardizing the system's ability for wastewater treatment, bioelectricity generation, and desalination processes.

Graphene nanofiltration membrane intercalated with AgNP@g-C3N4 for efficient water purification and photocatalytic self-cleaning performance

Low water flux and heavy membrane fouling hinder the use of graphene-based membranes for water purification and molecular sieving. To the end, a novel graphene-based membrane, intercalated with Ag nanoparticles anchored g-C3N4 (AgNP@g-C3N4) as pillars and photocatalysts, was fabricated through a mixed-dimensional assembly strategy. The uniform loading of Ag nanoparticles on g-C3N4 can greatly improve the photocatalytic ability of g-C3N4 while creating more water transport channels between reduced graphene oxide (rGO) and g-C3N4 laminates. The resultant rGO/AgNP@g-C3N4 nanofiltration membrane displayed efficient water permeability, superior photocatalytic self-cleaning performance, and owned excellent flexibility and structural stability. The water permeability of the rGO/AgNP@g-C3N4 membrane was considerably improved (210.9 L∙m−2∙h−1∙bar−1) compared to the pure rGO membrane (78.4 L∙m−2∙h−1∙bar−1) due to the larger interlayer spacing and rough surface. After 1 h of visible light irradiation, the decrease of flux produced by pollutant molecule adsorption can recover with a ultrahigh flux recovery ratio (FRR) of 98.1%. Moreover, the high flux of the rGO/AgNP@g-C3N4 membrane remained stable in a cross-flow photocatalytic nanofiltration device. Membrane separation, photocatalytic regeneration, and pollutant degradation by ·OH and ·O2− radicals are proposed as effective cooperation mechanisms.

Efficient Zn2+, Pb2+, and Ni2+ removal using antifouling mixed matrix nanofiltration membrane with curcumin modified mesoporous Santa Barbara Amorphous-15 (Cur-SBA-15) filler

Herein, new mesoporous material (curcumin (Cur) modified mesoporous Santa Barbara Amorphous-15 (Cur-SBA-15)) was prepared and characterized. Consequently, the polyethersulfone (PES)-based mixed matrix nanofiltration (NF) membranes were prepared at various mesoporous Cur-SBA-15 concentrations. The electrostatic interactions (e.g. complexation energy) between membrane acceptors (PES, SBA-15, and Cur) and heavy metal ions were studied by the geometric optimization and Energy Decomposition Analysis (EDA). Moreover, the most stable optimized structure for heavy metal ions and membrane acceptors was obtained. FTIR, EDS, and FESEM analyses were employed to confirm the presence of mesoporous Cur-SBA-15 in the membrane matrix. The effect of presence of mesoporous Cur-SBA-15 on membrane performance and properties was also determined. The 0.3 wt% mesoporous Cur-SBA-15 incorporated mixed matrix membrane (M-0.3) exhibited a high pure water flux of 42.5 kg/m2 h, the flux recovery ratio of 94.4%, irreversible permeability decay rate of 5.6%, and desirable rejection over 97% against Zn2+, Pb2+, and Ni2+. M-0.3 indicated a remarkably ameliorated surface hydrophilicity which has favored satisfactory antifouling behavior. The related results prove an antifouling Cur-SBA-15 mixed matrix membrane can be efficiently applied for the removal of heavy metal ions.

Highly selective heavy metal ions membranes combining sulfonated polyethersulfone and self-assembled manganese oxide nanosheets on positively functionalized graphene oxide nanosheets

This study presents the synthesis of a novel graphene oxide-manganese oxide (GO-MnO2) nanohybrid and its incorporation into sulfonated polyethersulfone (SPES) ultrafiltration (UF) membranes for wastewater treatment applications. The nanohybrid was first prepared by grafting ethylenediamine (ED) onto the edge of GO followed by direct mixing with the MnO2 nanosheets. The composite membranes were prepared via the phase inversion method and optimized by varying the concentration of the GO-MnO2 nanohybrid (0–6 wt%). The membranes were characterized using scanning electron microscopy, surface zeta potential, water flux, porosity, among others. The results showed that the pure water flux increased from 59.5 ± 2.5 L·m−2·h−1 in the pristine SPES membrane to 129.7 ± 4.1 L·m−2·h−1 in the SPGM4 (4 wt% GO-MnO2). Furthermore, the heavy metal ions rejection improved from 70.1, 49.1, and 55.8% for Cu2+, Zn2+, and Ni2+ ions, respectively, in the pristine SPES membrane to 81.1, 64.0, and 67.4% in the SPGM4 membrane. Also, the composite membranes revealed improvement in the anti-fouling properties over the pristine SPES membrane. For example, the SPGM4 membrane recovered 90.5 ± 2.9% of its initial flux compared to only 72.6 ± 3.1% in the pristine membrane after 4 cycles of heavy metal filtration and simple acid cleaning steps. Overall, the addition of GO-MnO2 nanohybrid enhanced the properties of the pristine SPES, creating new potential for such composite membranes in the wastewater treatment industry.

MAGE-a Inhibits Apoptosis in Multiple Myeloma through Regulation of Bim and PUMA

MAGE-a Inhibits Apoptosis in Multiple Myeloma through Regulation of Bim and PUMA

Eigenmode analysis of membrane stability in inviscid flow

We study the stability of a thin membrane (of zero bending rigidity) with a vortex sheet as a nonlinear eigenvalue problem in the parameter space of membrane mass (${R}_{1}$) and pretension (${T}_{0}$). With both ends fixed light membranes become unstable by a divergence instability and heavy membranes lose stability by flutter and divergence for a ${T}_{0}$ that increases with ${R}_{1}$. With the leading edge fixed and trailing edge free, or both edges free, membrane eigenmodes transition in shape across the stability boundary. We find good quantitative agreement with unsteady time-stepping simulations at small amplitude, but only qualitative similarities with the eventual steady-state large-amplitude motions.

N-glycosylation of Rim21 at an Unconventional Site Fine-tunes Its Behavior in the Plasma Membrane.

The polytopic plasma membrane protein Rim21 senses both the elevation of ambient pH and alterations in plasma membrane lipid asymmetry in the Rim101 pathway in budding yeast. Rim21 is known to undergo N-glycosylation, but the site and function of the glycosylation modification is not known. Using a systematic mutation analysis, we found that Rim21 is N-glycosylated at an unconventional motif located in the N-terminal extracellular region. The Rim21 mutant protein that failed to receive N-glycosylation showed prolonged protein lifetime compared to that of WT Rim21 protein. Although both the WT and mutant Rim21 localized to the plasma membrane, they exhibited different biochemical fractionation profiles. The mutant Rim21, but not WT Rim21, was mainly fractionated into the heavy membrane fraction. Further, compared to WT Rim21, mutant Rim21 was more easily solubilized with digitonin but was conversely more resistant to solubilization with Triton X-100. Despite these different biochemical properties from WT Rim21, mutant Rim21 protein could still activate the Rim101 pathway in response to external alkalization. Collectively, N-glycosylation of Rim21 is not indispensable for its activity as a sensor protein, but modulates the residence of Rim21 protein to some microdomains within the plasma membrane with distinct lipid conditions, thereby affecting its turnover.Key words: plasma membrane, lipid asymmetry, N-linked glycosylation, microdomain, Saccharomyces cerevisiae.

Thermal effects.

This review focuses on the research literature published in 2018 relating to thermal effects in wastewater and solid waste treatment. This review is divided into the following sections: treatment of wastewater and sludge, removal and recovery of nitrogen and phosphorus, reduction and recovery of heavy metals, membrane technology, and treatment and disposal of solid wastes. PRACTITIONER POINTS: Thermal effect plays an important role in the treatment of wastewater and sewage sludge. Recovery of nitrogen and phosphorus from wastewater and sewage sludge offers an excellent feedstock for soil amendment. Increase of treatment temperature facilitates removal and recovery of heavy metals from water and soil environment.

Gene Determinants for Mercury Bioremediation as Revealed by Draft Genome Sequence Analysis of Stenotrophomonas sp. Strain MA5.

A soilborne Stenotrophomonas sp. strain (MA5) that is resistant to mercury was isolated. A draft genome sequence-based analysis revealed a suite of gene determinants to resist mercury and other heavy metals, multidrug efflux, stress response, and membrane transport, and these provide cues to a suite of mechanisms that underpin cellular survival in contaminated soil.

A Novel Botulinum Toxin TAT-EGFP-HCS Fusion Protein Capable of Specific Delivery Through the Blood-brain Barrier to the Central Nervous System.

Botulinum toxin has many applications in the treatment of central diseases, as biological macromolecules, it is difficult to pass through the blood-brain barrier which greatly limits their application. In this paper, we verified whether the botulinum toxin heavy chain HCS has a specific neural guidance function. We have constructed a fusion protein with botulinum toxin heavy chain and a membrane penetrating peptide TAT (TAT-EGFP-HCS). Recombinant plasmid of botulinum toxin light chain (LC) and TAT were also constructed. The biological activity of HCS, LC, TAT-EGFP-HCS and TAT-EGFP-LC were measured by its ability to cleave protein SNAP-25. The intracellular expression efficiency was evaluated by detecting the fluorescence intensity of EGFP in the cells by fluorescence microscopy and FACS. In addition, we also determined the effect of the above plasmid expression on the apoptosis of PC12 cells. Finally, the tissue specificity of TAT-EGFP-HCS in vivo experiments was also examined. In the present study, we have constructed a fusion protein with botulinum toxin heavy chain and a membrane penetrating peptide TAT which can lead the entire molecule through the blood-brain barrier and reach the central nervous system. Moreover, we also examined the biological activities of this recombinant biological macromolecule and its physiological effects on nerve cells in vitro and in vivo. TAT-EGFP-HSC expressed in vitro has neural guidance function and can carry large proteins across the cell membrane without influencing the biological activity.

Incorporation of UiO-66-NH2 MOF into the PAN/chitosan nanofibers for adsorption and membrane filtration of Pb(II), Cd(II) and Cr(VI) ions from aqueous solutions.

In the present study, the UiO-66-NH2 MOF synthesized by microwave heating method was incorporated into the PAN/chitosan nanofibers for the removal of Pb(II), Cd(II) and Cr(VI) ions through the adsorption and membrane filtration processes. The synthesized MOFs and nanofibers were characterized using XRD, BET, FTIR, SEM, and DSC analysis. The effect of UiO-66-NH2 MOF content (0-15 wt.%), pH (2-7), contact time(5-90 min), metal ions initial concentration (20-1000 mg/L) and temperature (25-45 °C) was studied on the metal ions adsorption using PAN/chitosan/UiO-66-NH2 nanofibrous adsorbent. The kinetic, isotherm and thermodynamic parameters were evaluated to understand the metal ions adsorption mechanism using nanofibers. The Pseudo-second-order kinetic and Redlich-Peterson isotherm model were well described the experimental sorption data. In the heavy metal ions membrane filtration process, the different parameters such as MOF concentration (2-15 wt.%), membrane thickness (10-70 μm), metal ions concentration (5-50 mg/L), temperature (25-45 °C) and filtration time (1-24 h) were investigated on the performance of PVDF/ PAN/chitosan/UiO-66-NH2 nanofibrous membrane toward metal ions removal. The high water flux and high metal ions removal within 18 h filtration time showed the high potential of PVDF/ PAN/chitosan/UiO-66-NH2 membrane for the removal of metal ions from aqueous solutions.

Fractionation of Subcellular Compartments from Human Brain Tissue.

Subcellular fractionation methods permit the isolation, purification, and/or enrichment of specific cellular compartments from complex tissue samples. Enrichment of multiple subcellular compartments from the same tissue sample permits comparisons of the spatial distribution of target proteins between specific intracellular compartments and, in some cases, can provide information about spatiotemporal processing of key cellular components. Here we describe a method to generate subcellular fractions enriched for heavy membranes and nuclei, rough and smooth endoplasmic reticulum membranes, light membranes and cytosol, synapses, and other intermediate cellular membranes from postmortem human brain tissue. These subcellular fractions can be used in a variety of downstream applications to assess the localization, relative abundance, and stoichiometry of glutamate receptor subunits along the forward trafficking pathway.

Assessment of Dynamic BCL-2 Protein Shuttling Between Outer Mitochondrial Membrane and Cytosol.

BCL-2 proteins control stress-dependent commitment to the programmed cell death apoptosis. In nonapoptotic cells the proapoptotic BCL-2 proteins BAX and BAK but also prosurvival family members, like BCL-xL or MCL-1, translocate to the outer mitochondrial membrane (OMM) and retrotranslocate from the mitochondria back into the cytosol. The resulting equilibrium produces a broad range of localization pattern observed for BAX and BAK in human cells and shows correlation between relative BAX and BAK localizations and cellular predisposition to apoptosis. The retrotranslocation of BCL-2 proteins from the OMM can be measured using fluorescence-labeled protein in intact cells or endogenous protein from isolated heavy membrane fractions.

Preparation and characterization of nanofibers of polyvinyl alcohol/polyaniline-montmorillonite clay

This work describes the preparation of polyvinyl alcohol/polyaniline-montmorillonite clay (PVA/PANI-OMMT) nanofibers through electrospinning. Initially, for improving the compatibility of the clay towards the organic polymer, the montmorillonite (MMT) was submitted to an organophilization process using hexadecyltrimethylammonium bromide (CH3(CH2)15N(Br)(CH3)3). The PANI-OMMT composite, which was obtained after the in situ polymerization of aniline in presence of the organophilic clay (ratio of ≈1:3 in weight), was then placed in a matrix of PVA (weight ratio of 1:7 of composite:PVA) for the production of the PVA/PANI-OMMT composite fibers through electrospinning. We used several characterization techniques (X-ray diffraction (XRD); infrared absorption spectroscopy (FTIR), ultraviolet visible absorption spectroscopy (UV–Vis), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS)) to analyze the different samples produced. The clay organophilization was confirmed after observing the (001) plane displacement from 5,6° to 4,7° and absorption bands in 2924 cm−1, 2853 cm−1 and 1479 cm−1, as analyzed by XRD and FTIR, respectively. The presence of polyaniline in its emeraldine salt was identified by the presence of the characteristic UV–Vis absorption bands in 360 nm, 430 nm and 822 nm, while the formation of the PANI/OMMT nanocomposite was confirmed by observing the characteristic FTIR bands of each individual component. From the SEM images, we could establish that the resulting nanocomposite mats were composed by uniform fibers with an average diameter of 240 nm and presented good surface quality. We have found that EIS is an efficient technique for the evaluation of changes in the electric properties of the nanofibers after their exposure to vapors of methanol. We suggest that this organic-inorganic composite may find useful applications in the preparation of several devices based on polymers, such as heavy metal filtration membranes and gas sensors.

A systematic evaluation on the performance and mechanism of surfactants as additive of draw solution in forward osmosis

In this study, the performances of six different types of surfactants, each with a series of concentrations around its critical micelle concentration, were systematically tested as additives of draw solution (DS) to improve the performance of DS in forward osmosis. The influence mechanism of surfactants on DS characteristics, membrane fouling and characteristics of ideal surfactants were discussed comprehensively. The six surfactants showed big differences in considering their effects on the characteristics of DS and their performances, which could be explained by the combined effects of thin dense layer formed by surfactant molecules adsorbed on the surface of supporting layer (SL), blocked pores of SL by micelles aggregation, increased viscosity of DS, improved hydrophilicity of membrane SL and ionization of the hydrophilic groups. The nonionic surfactants could significantly reduce the reverse solute flux, accompanied by sharply decreased water flux and heavy membrane fouling. Compared with nonionic surfactants, the anionic surfactants with their Hydrophile-Lipophilic Balance around 10 could significantly reduce the reverse solute flux while with no or low decrease of water flux and reversible membrane fouling. In our work, Sodium dodecyl benzene sulfonate, at 5 mmol/L concentration, had the best performance on the improvement of DS.

Abstract 529: Asporin - Extracellular Matrix Protein Mitigates Pathological Remodeling

The cardiac extracellular matrix is a complex network of proteins and plays a key role in cardiac remodeling after myocardial infarction. One of the extracellular matrix proteins, asporin, is a member of the SLRP family and inhibits TGFβ signaling. However, very little is known about the function and regulation of asporin in cardiac remodeling. Using bioinformatics approach, microarray data analysis from publicly available datasets identified asporin as a top candidate showing an increase in left ventricle tissue with ischemic cardiomyopathy as compared to control donor hearts. To confirm, we detected an increase in asporin expression in paired heart biopsies taken before and after cardiopulmonary bypass surgery by western blot analysis. Our group showed that glucagon like receptor 1 agonist (GLP-1Ra) is beneficial for cardiac remodeling and prevents fibrosis. In a permanent coronary artery ligation model, we found increased extracellular asporin expression after 30 days in border zone and scar area with GLP-1Ra treatment compared to vehicle-treatment. To further elucidate the mechanism of asporin secretion, we used H9c2 cells as well as left ventricle tissue from mice and found that asporin was predominantly present in the heavy membrane enriched fraction (8,000xg pellet from postnuclear supernatant). Sequence analysis of asporin protein using SecretomeP 2.0 server predicted asporin might use the non-conventional form of secretion (secretory autophagy). Differentiation of H9c2 cells is accompanied by autophagy and mitochondrial biogenesis, and we found that the abundance of asporin in total lysate and heavy membrane fraction decreased suggesting it could be released via secretory autophagy. Using recombinant human asporin, we demonstrated that asporin stimulates an increase in LC3 and p62 in parallel to a decrease in COX IV and SMAD2 phosphorylation, indicating mitophagy induction and a decrease in TGFβ signaling. Based on our preliminary data and sequence comparison to a previously reported human peptide, we developed a rodent asporin peptide which is predicted to induce mitophagy while decreasing TGFβ signaling to prevent fibrosis. Studies are ongoing to establish the clinical relevance of asporin in animal models of ischemic injury.

Drops Floating on Granular Rafts: A Tool for Liquid Transport and Delivery.

Solid particles can modify the properties of liquid interfaces and are therefore widely used to coat drops, bubbles, and stabilize emulsions and foams. Here, we propose a new, easy, and affordable method to produce millimetric to centimetric water-in-water capsules using solid particles. We prevent the coalescence of a water drop at an oil–water interface using a monolayer of large, dense, and hydrophobic particles: a “granular raft”. The capsule is then formed by a mechanical instability occurring when the interface collapses under the combined load of the floating drop and particle weight. During the destabilization, the water drop sinks into the water subphase through an oil-particle film which covers it to produce the armored capsule. By modeling the raft as a heavy membrane, we predict the floating drop shape, the raft deformation, its destabilization and highlight the complex dual nature (solid- and liquid-like) of the capsule shell. Because armored capsules’ content is isolated, transportable, and easily releasable, they are great candidates for applications requiring transport of water-soluble compounds in aqueous systems such as green chemistry or cell biology.