Molecular Weight Cut-off Membrane Research Articles

Identification and characterization of immunomodulatory peptides from pepsin\u2013soy protein hydrolysates

To obtain immunomodulatory peptides from isolated soy protein (ISP), pepsin was selected to prepare hydrolysates and 4-h treatment (Pepsin-ISPH4h) showed the highest yield and immunomodulatory activities. The Pepsin-ISPH4h was sequentially fractionated by 30, 10 and 1-kDa molecular weight cut-off (MWCO) membranes, in which 1-kDa MWCO permeate (1P) exhibited the most significant enhancement of phagocytosis activity without causing excessive inflammation as compared with Pepsin-ISPH4h. To further purify and enhance the immunomodulatory activity, 1P was distinct by high-performance liquid chromatography equipped with a reverse-phase column and in vivo immunomodulatory activity of fractions was examined in mice. Fraction 1 (F1) significantly elevated phagocytosis activity of mice spleen macrophages and neutrophils. However, increase of phagocytosis activity did not result from the induction of macrophages M1 or M2 polarization. The immunomodulatory peptide sequence, EKPQQQSSRRGS, from F1 was identified by LC–MS/MS. Phagocytosis activity and macrophage M1 polarization were elevated by synthetic peptide treatment. Hence, our results indicated that isolated soy protein hydrolysates prepared by pepsin could provide a source of peptides with immunomodulatory effects.Graphical

Solvent recovery from photolithography wastes using cellulose ultrafiltration membranes

Solvent recycling and reuse are indispensable for ensuring a sustainable chemical industry and circular economy. In this study we report the fabrication of cellulose ultrafiltration membranes and their application in recovery of propylene glycol methyl ether acetate (PGMEA) used as developer solvent in SU-8 photolithography. Cellulose membranes were fabricated via alkaline hydrolysis of cellulose acetate membranes in aqueous NaOH. Membrane permeance and molecular weight cut-off (MWCO) were tuned via changing cellulose acetate concentration in precursor solution and evaporation of volatile co-solvent, acetone. MWCO of the membranes was found to be smallest in DMSO, followed by water and largest in methanol. The difference was attributed to the different hydrodynamic diameters of the probe molecules in these solvents. SU-8 rejection from its representative developer solutions in PGMEA was assessed in dead-end filtration at up to 80% permeate recovery. After the first filtration, the collected permeate was fed to the same membrane to simulate a two-stage filtration scenario. Rejection was in the range of 87%–89% in a first stage filtration and 79%–80% in a second stage, both operated at 80% permeate recovery. Recycled solvent could be used in photolithography although with some loss of pattern fidelity, possibly owing to remaining SU-8 and photoacid generator in PGMEA. • Cellulose membrane permeance and MWCO tuned between 0.40–23.3 LHM/bar and 4–15 kDa. • Permeance is via pore flow mechanism but is also affected by swelling and steric hindrance. • SU-8 can be recovered from its PGMEA solution and reused in photolithography.

Physicochemical and Functional Properties of Membrane-Fractionated Heat-Induced Pea Protein Aggregates.

This study was carried out to investigate the effect of heat pre-treatment of pea proteins at different pH values on the formation of functional protein aggregates. A 10% (w/v) aqueous mixture of pea protein concentrate (PPC) was adjusted to pH 3.0, 5.0, 7.0, or 9.0 followed by heating at 100°C for 30 min, cooled and centrifuged. The supernatant was sequentially passed through 30 and 50 kDa molecular weight cut-off membranes to collect the <30, 30–50, and >50 kDa fractions. The >50 kDa fractions from pH 3.0 (FT3), 5.0 (FT5), 7.0 (FT7), and 9.0 (FT9) treatments had >60% protein content in contrast to the ≤20% for the <30 and 30–50 kDa fractions. Therefore, the >50 kDa fractions were collected and then compared to the untreated PPC for some physicochemical and functional properties. Protein aggregation was confirmed as the denaturation temperature for FT3 (124.30°C), FT5 (190.66oC), FT7 (206.33oC) and FT9 (203.17oC) was significantly (p < 0.05) greater than that of PPC (74.45oC). Scanning electron microscopy showed that FT5 had a compact structure like PPC while FT3, FT7, and FT9 contained a more continuous network. In comparison to PPC, the >50 kDa fractions showed improved solubility (>60%), oil holding capacity (~100%), protein content (~7%), foam capacity (>10%), foam stability (>7%), water holding capacity (>16%) and surface hydrophobicity (~50%). Least gelation concentration of PPC (18%), FT3 (25%), FT5 (22%), FT7 (22%), and FT9 (25%) was improved to 16, 18, 20, 16, and 18%, respectively, after addition of NaCl.

Novel method for the facile control of molecular weight cut-off (MWCO) of ceramic membranes

This study demonstrates a simple and novel preparation method to prepare ceramic nanofiltration membranes with a precise and tunable molecular weight cut-off (MWCO) by packing variously sized nanoparticles into existing membrane pores. As a result, ceramic membranes with a MWCO from 1000 Da to 10,000 Da were successfully prepared with the narrow distribution of the pore size after the filtration-coating process. In addition, the effective porosity of the ceramic membranes was calculated from the results of the membrane properties by the Hagen-Poiseuille equation which fit within the range of the sphere packing theory from 17.3% to 41.8%. Furthermore, the results of nonlinear curve fitting between the MWCO and the nanoparticle size show a high accuracy, which implies that the MWCO of the ceramic membranes can be predicted using the curve fitting model with variously sized nanoparticles in the filtration-coating process. In conclusion, the novel filtration-coating method enables precise pore control and provides a tunable MWCO to ceramic membranes by preparing various sizes of nanoparticles.

Extraction of the Bacterial Extracellular Polysaccharide FucoPol by Membrane-Based Methods: Efficiency and Impact on Biopolymer Properties.

In this study, membrane-based methods were evaluated for the recovery of FucoPol, the fucose-rich exopolysaccharide (EPS) secreted by the bacterium Enterobacter A47, aiming at reducing the total water consumption and extraction time, while keeping a high product recovery, thus making the downstream procedure more sustainable and cost-effective. The optimized method involved ultrafiltration of the cell-free supernatant using a 30 kDa molecular weight cut-off (MWCO) membrane that allowed for a 37% reduction of the total water consumption and a 55% reduction of the extraction time, compared to the previously used method (diafiltration-ultrafiltration with a 100 kDa MWCO membrane). This change in the downstream procedure improved the product’s recovery (around 10% increase) and its purity, evidenced by the lower protein (8.2 wt%) and inorganic salts (4.0 wt%) contents of the samples (compared to 9.3 and 8.6 wt%, respectively, for the previously used method), without impacting FucoPol’s sugar and acyl groups composition, molecular mass distribution or thermal degradation profile. The biopolymer’s emulsion-forming and stabilizing capacity was also not affected (emulsification activity (EA) with olive oil, at a 2:3 ratio, of 98 ± 0% for all samples), while the rheological properties were improved (the zero-shear viscosity increased from 8.89 ± 0.62 Pa·s to 17.40 ± 0.04 Pa·s), which can be assigned to the higher purity degree of the extracted samples. These findings demonstrate a significant improvement in the downstream procedure raising FucoPol’s recovery, while reducing water consumption and operation time, key criteria in terms of process economic and environmental sustainability. Moreover, those changes improved the biopolymer’s rheological properties, known to significantly impact FucoPol’s utilization in cosmetic, pharmaceutical or food products.

Fouling resistant and performance tunable ultrafiltration membranes via surface graft polymerization induced by atmospheric pressure air plasma

Surface modification of polysulfone (PSf) surface, via acrylic acid (AA) surface graft polymerization, induced by atmospheric pressure Air plasma (Air APP) surface treatment, was explored for imparting UF membrane fouling resistance and tuning its performance. PSf surface activation with Air APP and subsequent tethering of PAA chains resulted in a higher degree of surface hydrophilicity relative to the use of He and He/O2 plasmas. Surface-nano-structed (SNS) PSf membranes with tethered PAA chains were of increased surface hydrophilicity and the polar component of the surface energy by 14% and 556%, respectively, and had a greater negative zeta potential (by 26% at pH >∼6) relative to the native-PSf membrane. Fouling filtration tests with bovine serum albumin (BSA) and sodium alginate demonstrated reduced fouling resistance, relative to the native-PSf membrane. Moreover, complete permeability recovery of the fouled SNS-PAA-PSf membrane was achieved, via simple water backwash, relative to 66%-81% permeability recovery for the native PSf membrane. Tethering the PSf UF surface with PAA chains was also enabled tuning of the membrane molecular weight cutoff (MWCO) and hydraulic permeability. It was shown that starting with the same PSf UF membrane a series of SNS-PAA-PSf membranes can be synthesized whereby performance tuning was achieved over a MWCO range of 5.5–11 kDa and a corresponding permeability range of 12.7–23.5 L·m−2·h−1·bar−1. The present approach of PSf UF membrane surface structuring with tethered PAA chains, employing Air APP for surface activation, was shown to be effective for UF membrane fouling reduction and performance tuning. Thus, the present study results suggest that there is merit in exploring its scalability given the utilization of air as a low cost plasma source gas.

Serial fractionation of spent brewer's yeast protein hydrolysate by ultrafiltration: A peptide-rich product with low RNA content

Spent brewer's yeast (SBY) application as a new source of peptides depends on the development of proper downstream processes. This work aimed to separate yeast hydrolysate peptides from sugars and ribonucleic acids (RNA) by a 3-step designed fractionation process using ceramic ultra and nanofiltration following two sequences: (1) 50, 8 and 1 kDa and (2) 15, 8 and 1 kDa molecular weight cut-off (MWCO) membranes. In step one, 15 kDa MWCO membrane retained more components and increased performance of subsequent steps, when compared to 50 kDa. Peptide composition of the initial hydrolysate was gradually changed until 90% of the peptides smaller than 1 kg mol −1 were found in the final permeate. Fractionation increased peptide purity regarding RNA and total sugars up to 1.7 and 2.7-fold, respectively. Innovative protein-rich ingredients from SBY residue with an RNA content as low as 1.4% were produced by membrane separation technology. High quality ingredients presented different peptide profiles and great potential in food and pharmaceutical industries applications. • Efficient RNA reduction was achieved using membrane separation technology. • RNA content in protein-rich fraction was as low as 1.4% (dry weight). • Membranes of 15–1 kDa range were adapted to spent yeast ultrafiltration. • Protein purity of obtained fractions increased 1.7 and 2.7-fold for RNA and sugars. • A fraction with bioactive potential (65% of the peptides < 1 kg mol −1 ) was produced.

Revisiting the Molar Mass and Conformation of Derivatized Fractionated Softwood Kraft Lignin.

The limited utilization of reliable tools and standards for determination of the softwood kraft lignin molar mass and the corresponding molecular conformation hampers elucidation of the structure-property relationships of lignin. At issue, conventional size exclusion chromatography (SEC) is unable to robustly measure the molar mass because of a lack of calibration standards with a similar structure to lignin. In the present work, the determination of the absolute molar mass of acetylated technical lignin was revisited utilizing SEC combined with multi-angle light scattering with a band pass filter to suppress the fluorescence. Fractionated lignin isolated using sequential techniques of solvent and membrane methods was used to enhance the clarity of light-scattering profiles by narrowing the molar mass distribution of lignin fractions. Further information on the molecular conformation of derivatized samples was studied utilizing a differential viscometer, and chemical structures were identified by NMR spectroscopy analysis. Through the help of fractionation, intrinsic viscosity values were determined for the different fractions as a function of molecular weight cut-off membranes. The derivatized acetone-soluble lignin was found to possess a lower molecular weight and an extremely compact structure relative to the derivatized acetone-insoluble fraction based on a significantly lower "α" value in the Mark-Houwink-Sakurada plot (0.15 acetone-soluble vs 0.33 acetone-insoluble). The differences in geometry were supported by the linkage analysis from NMR showing the acetone-soluble part containing fewer native linkages. In both of these examples, kraft lignin behaved like a solid sphere, limiting the ability to provide entanglements between molecular chains. From this standpoint, macroscopic properties of lignin are justified with this knowledge of a dense and extremely compact structure.

Identification of Antimicrobial Peptides Isolated From the Skin Mucus of African Catfish, Clarias gariepinus (Burchell, 1822).

Antimicrobial peptides (AMPs) constitute a broad range of bioactive compounds in diverse organisms, including fish. They are effector molecules for the innate immune response, against pathogens, tissue damage and infections. Still, AMPs from African Catfish, Clarias gariepinus, skin mucus are largely unexplored despite their possible therapeutic role in combating antimicrobial resistance. In this study, African Catfish Antimicrobial peptides (ACAPs) were identified from the skin mucus of African Catfish, C. gariepinus. Native peptides were extracted from fish mucus scrapings in 10% acetic acid (v/v) and ultra-filtered using 5 kDa molecular weight cut-off membrane. The extract was purified using C18 Solid-Phase Extraction. The antibacterial activity was determined using the Agar Well Diffusion method and broth-dilution method utilizing Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922). Thereafter, Sephadex G-25 gel filtration was further utilized in bio-guided isolation of the most active fractions prior to peptide identification using Orbitrap Fusion Lumos Tribrid Mass Spectrometry. The skin mucus extracted from African Catfish from all the three major lakes of Uganda exhibited antimicrobial activity on E. coli and S. aureus. Lake Albert’s C. gariepinus demonstrated the best activity with the lowest MIC of 2.84 and 0.71 μg/ml on S. aureus and E. coli, respectively. Sephadex G-25 peak I mass spectrometry analysis (Data are available via ProteomeXchange with identifier PXD029193) alongside in silico analysis revealed seven short peptides (11–16 amino acid residues) of high antimicrobial scores (0.561–0.905 units). In addition, these peptides had a low molecular weight (1005.57–1622.05 Da) and had percentage hydrophobicity above 54%. Up to four of these AMPs demonstrated α-helix structure conformation, rendering them amphipathic. The findings of this study indicate that novel AMPs can be sourced from the skin mucus of C. gariepinus. Such AMPs are potential alternatives to the traditional antibiotics and can be of great application to food and pharmaceutical industries; however, further studies are still needed to establish their drug-likeness and safety profiles.

In Vivo Microdialysis in Mice Captures Changes in Alzheimer's Disease Cerebrospinal Fluid Biomarkers Consistent with Developing Pathology.

Preclinical models of Alzheimer's disease (AD) can provide valuable insights into the onset and progression of the disease, such as changes in concentrations of amyloid-β (Aβ) and tau in cerebrospinal fluid (CSF). However, such models are currently underutilized due to limited advancement in techniques that allow for longitudinal CSF monitoring. An elegant way to understand the biochemical environment in the diseased brain is intracerebral microdialysis, a method that has until now been limited to short-term observations, or snapshots, of the brain microenvironment. Here we draw upon patient-based findings to characterize CSF biomarkers in a commonly used preclinical mouse model for AD. Our modified push-pull microdialysis method was first validated ex vivo with human CSF samples, and then in vivo in an AD mouse model, permitting assessment of dynamic changes of CSF Aβ and tau and allowing for better translational understanding of CSF biomarkers. We demonstrate that CSF biomarker changes in preclinical models capture what is observed in the brain; with a decrease in CSF Aβ observed when plaques are deposited, and an increase in CSF tau once tau pathology is present in the brain parenchyma. We found that a high molecular weight cut-off membrane allowed for simultaneous sampling of Aβ and tau, comparable to CSF collection by lumbar puncture in patients. Our approach can further advance AD and other neurodegenerative research by following evolving neuropathology along the disease cascade via consecutive sampling from the same animal and can additionally be used to administer pharmaceutical compounds and assess their efficacy.

Stepwise synthesis of polyacrylonitrile-supported oligoamide membranes with selective dye–salt separation

Production processes of the dye and textile industries release toxic organic dyes that are detrimental to the environment. The treatment of industry waste effluents using membranes is difficult as membrane recovery is hampered by high salt contents in dyes. This work reports a molecular layer-by-layer approach for preparing oligoamide membranes on a poly(acrylonitrile) (PAN) support capable of effective dye–salt separation, where the oligoamide film is covalently linked to a functionalized PAN support. Membranes with improved water permeance, molecular weight cut-off (MWCO), and dye–salt selectivity were synthesized by screening different PAN supports and investigating their effect on performance, varying the number of oligoamide synthesis cycles, and tuning the monomer coupling reaction conditions. Microscopic and spectroscopic techniques confirmed the structure of the oligoamide membranes. Water permeance was directly correlated to the number of synthesis cycles, the MWCO of the oligoamide membranes varied between 104.5 and 2.0 kDa for 2.5 to 10.5 synthesis cycles, respectively. Synthesis with 10.5 cycles gave an oligoamide membrane with >99% rejection of Congo Red with a high permeate flux of 87.5 ± 14.8 L m−2 h−1 bar−1 and 99%–100% salt passage, demonstrating its promising potential of fractionating dye–salt mixtures. The synthesized membranes showed excellent stability during long-term (one week) filtration of Congo Red effluents containing 20 g/L NaCl. The reported membranes hold great promise for dye–salt separation and treatment of wastewater from the dye and textile industries.

Automated Electrokinetic Platform for High-Throughput Sodium Dodecyl Sulfate Depletion Ahead of Proteome Analysis by Mass Spectrometry.

Sodium dodecyl sulfate (SDS) provides numerous benefits for proteome sample preparation. However, the surfactant can be detrimental to downstream mass spectrometry analysis. Although strategies are available to deplete SDS from proteins, each is plagued by unique deficiencies that challenge their utility for high-throughput proteomics. An optimal approach would rapidly and reproducibly achieve less than 10 ppm residual SDS while simultaneously maximizing analyte recovery. Here, we describe improvements to a simple electrokinetic device termed transmembrane electrophoresis, which we previously reported for automated, rapid SDS depletion of proteome samples. Voltage-driven transport of SDS across a molecular weight cutoff membrane is enhanced at higher electric fields, which is herein achieved by integrating an active cooling mechanism to mitigate the impacts of Joule heating. We report 99.9% reduction of SDS (final concentration < 5 ppm) in 5 min. The device is employed in a detergent-based proteomic workflow for analysis of an enriched yeast membrane proteome extract, demonstrating quantitative protein recovery (>98%) and increasing the number of identifications by liquid chromatography-tandem mass spectrometry.

Antifungal Activity and Major Bioactive Compounds of Water Extract of Pangium edule Seed against Aspergillus flavus.

Pangium edule seeds are widely used as spices in Southeast Asia in a fresh and fermented form and are reported to have active compounds for food preservation. However, scientific data on the active compounds of P. edule seed that can prevent the growth of toxigenic Aspergillus flavus have not been widely reported. This research subjected to determine the antifungal activity and identify the active compounds of water extract of old and fermented seed of P. edule against A. flavus. The water extract was compared to the extracts obtained by multilevel maceration using 50% ethanol, ethyl acetate, and n-hexane as solvents. Alkaloid, saponin, phenolic compound, flavonoid, triterpenoid, and glycoside were detected qualitatively in the crude extracts. The water extract showed the best activity to suppress the growth of A. flavus, determined by the agar dilution method, with the minimum inhibitory concentration (MIC) of 12.5 and 25 mg/mL for old and fermented seed, respectively. The water extracts showed a moderate toxicity with LC50 of 100-500 μg/mL, determined by the brine-shrimp toxicity test. After fractionation using 3 kDa molecular-weight (MW) cut-off ultrafiltration membrane, two fractions, i.e., fraction with MW < 3 kDa and >3 kDa, were obtained. The fraction with MW < 3 kDa showed the best antifungal activity with the MIC of 6.25 and 12.5 mg/mL for old and fermented seed, respectively. LC-MS/MS profile showed that different compounds belong to fatty acid, amino acid, glycoside, and peptide were found as major active compounds in the fractionated water extract. The principal compounds and partial least-square analysis, however, suggested that fatty acid and glycoside are responsible for the antifungal activity. Hence, this study concluded that the water extract of P. edule seed had promising antifungal activity against A. flavus which was due to presence of particular compounds belong to fatty acid and glycoside.

Enhanced removal of perfluorooctane sulfonic acid and perfluorooctanoic acid via polyelectrolyte functionalized ultrafiltration membrane: Effects of membrane modification and water matrix

This study investigated the mechanisms of removal of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) using polyelectrolyte (PE) functionalized ultrafiltration (UF) membranes, performed through a fluidic method of layer-by-layer (LbL) deposition of polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) multilayer coatings. The effects of source water composition (humic acids [HA] and cations [Ca2+ and Mg2+]) on PFOS and PFOA removal efficiency by the functionalized membrane were determined. PAH/PAA modification resulted in approximately 38 % and 9.2 % reduction in membrane molecular weight cut-off (MWCO) and porosity, respectively, leading to approximately 30 % increase in the removal of PFOS and PFOA primarily due to size exclusion. The presence of only HA led to 10–12 % higher removal of PFOS/A when compared to DI water; however, an increase in HA concentration did not further influence their removal efficiency. The coexistence of cations and HA resulted in significantly higher removal of PFOS and PFOA (up to 23 % higher for PFOS). Further enhancement of PFOS removal (14 % higher) was observed when cation concentrations were doubled, attributable to the interactions of PFOS/A with the source water components and the functionalized membrane, resulting in enhanced size and charge exclusion of macromolecular complexes including PFOS-cation-PFOS, PFOS-cation-HA, and PFOA-cation-HA.

Sequence-Specific Capture of Oligonucleotide Probes (SCOPE): a Simple and Rapid Microbial rRNA Quantification Method Using a Molecular Weight Cutoff Membrane.

A method named sequence-specific capture of oligonucleotide probes (SCOPE) was developed for quantification of microbial rRNA molecules in a multiplex manner. In this method, a molecular weight cutoff membrane (MWCOM) was used for the separation of fluorescence-labeled oligonucleotide probes hybridized with rRNA from free unhybridized probes. To demonstrate proof of concept, probes targeting bacteria or archaea at different taxonomic levels were prepared and were hybridized with rRNAs. The hybridization stringency was controlled by adjusting reaction temperature and urea concentration in the mixture. Then, the mixture was filtered through the MWCOM. The rRNA and hybridized probes collected on the MWCOM were recovered and quantified using a spectrophotometer and fluorospectrometer, respectively. The method showed high accuracy in detecting specific microbial rRNA in a defined nucleic acid mixture. Furthermore, the method was capable of simultaneous detection and quantification of multiple target rRNAs in a sample with sensitivity up to a single-base mismatch. The SCOPE method was tested and benchmarked against reverse transcription-quantitative PCR (RT-qPCR) for the quantification of Bacteria, Archaea, and some key methanogens in anaerobic sludge samples. It was observed that the SCOPE method produced more reliable and coherent results. Thus, the SCOPE method allows simple and rapid detection and quantification of target microbial rRNAs for environmental microbial population analysis without any need for enzymatic reactions. IMPORTANCE Microorganisms play integral roles in the Earth's ecosystem. Microbial populations and their activities significantly affect the global nutrient cycles. Quantification of key microorganisms provides important information that is required to understand their roles in the environment. Sequence-based analysis of microbial population is a powerful tool, but it provides information only on relative abundance of microorganisms. Hence, the development of a simpler and quick method for the quantification of microorganisms is necessary. To address the shortcomings of a variety of molecular methods reported so far, we developed a simple, rapid, accurate, and multiplexed microbial rRNA quantification method to evaluate the abundance of specific microbial populations in complex ecosystems. This method demonstrated high specificity, reproducibility, and applicability to such samples. The method is useful for quantitative detection of particular microbial members in the environment.

Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry Analysis for Molecular Characterization of Chitosan

Chitosan oligosaccharides designated to COS were derived from the hydrolysis of high molecular weight chitosan (HMWC). The range of molecular weight of COS was estimated to be approximately 0.5 to 2.5 kDa after the fractionation performed through gel-filtration, followed by MALDI-TOF mass spectrometry analysis. It was confirmed through the results that significant separation or fractionation was not observed well. Also, both dialyzed COS using a 12~14 kDa molecular weight cut-off (MWCO) membrane and salting-out COS were also showed no significant difference in the molecular weight of COS by MALDI-TOF mass spectrometry analysis. These results suggested that it is difficult to separate the chitosan hydrolysates bigger than 1 kDa according to the size (6-glucosamine) due to their high affinity between molecules which may tightly be associated together by hydrophobic or van der Waals force. Therefore, further examination on chitosan hydrolysis and fractionation for the production of COS with various sizes i.e., 7 or 8 units of glucosamine in large-scale, should be carefully considered for various applications.

MECHANICAL PROPERTIES OF POLYSULFONE-ZnO NANOCOMPOSITE MEMBRANE

Large quantities of wastewater are generated by the petroleum refining process. Micron-scale emulsion droplets and submicron droplets are difficult to remove from oil-refined wastewater, and addressing these issues has been a major challenge for researchers. Membrane technology is widely used in water treatment because it is very selective and effective in the filtration process. his research focuses on oil refinery water treatment using a polysulfone membrane (PSF)-nano-ZnO membrane with the addition of polyethylene glycol (PEG). This research aims to determine the PEG ratio that produces the optimum PSF-ZnO membrane in terms of mechanical properties, including thickness, tensile strength, and molecular weight cut-off (MWCO) value. The membranes with the optimum clearance were obtained at 3% PEG with a thickness of 0.0077 mm, Young's modulus of 8800 N/m2, and Morphological analysis was performed using the SEM (Scanning Electron Microscopy) method on the membrane which had the highest and lowest permeability values.. The best membrane MWCO value was achieved by the addition of 19% PSF-nano-ZnO 1% wt at 5 minutes of UV irradiation. This shows that the addition of PEG composite affects pore openings. The membrane formed with variations in PEG concentrations affecting the thickness of the membrane. Higher concentrations make the membrane thicker, resulting in a higher Young’s modulus.

Polyamide layer sulfonation of a nanofiltration membrane to enhance perm‐selectivity via regulation of pore size and surface charge

AbstractIn this study, sulfonated nanofiltration membranes were synthesized via interfacial polymerization (IP) of aqueous‐phase piperazine (PIP), 3‐amino‐1‐propanesulfonic acid (APA), and organic‐phase trimesoyl chloride (TMC) monomers on porous substrates. Membranes with different APA contents were thoroughly characterized to determine how APA affected the physicochemical characteristics and perm‐selectivity of the membranes. Membrane characterization confirmed the incorporation of APA into the generated polyamide (PA) layer. The optimal membrane performance was obtained at a 0.8 w/v% aqueous‐phase APA content, where the enhanced membrane molecular weight cutoff (MWCO) and surface hydrophilicity resulted in a pure water permeability of 11.9 L m−2 h−1 bar−1, approximately 13.1% higher than that of the blank membrane. Enhanced electrostatic repulsion of the APA‐modified membrane on Na2SO4 resulted in up to a 96.2% Na2SO4 rejection rate. The 24.3% NaCl rejection rate resulted in NaCl/Na2SO4 selectivity for the mixed‐salt solution of the optimized membrane of 19.9, which was a significant increase over that of the blank. The embedding of APA did not affect the long‐term stability of the NF membrane. The combined effects of the hydrophilicity, charge, and roughness of the membrane surface slightly enhanced the antifouling ability of the APA‐modified membrane over that of the blank. This study provides a facile strategy for the fabrication of NF membranes with high perm‐selectivity.

In Vivo Monitoring of Acetylcholine Release from Nerve Endings in Salivary Gland.

Simple SummaryStimulation of the parasympathetic nervous system results in the secretion of saliva. Previous studies have demonstrated acetylcholine content in homogenate obtained from salivary glands. Acetylcholine in homogenate, however, includes that stored in the cells, as well as that released in the interstitial fluid. The activity of the parasympathetic nervous system is mainly determined by the amount of acetylcholine released. We established an in vivo microdialysis method for monitoring the acetylcholine released from nerve endings in the salivary glands in rats. The results of the present study demonstrated that acetylcholine levels in the dialysate reflect acetylcholine levels in the interstitial fluid of the submandibular gland, and that an increase in the acetylcholine level in the dialysate depends predominantly on the release of acetylcholine from the parasympathetic nerve endings.A microdialysis technique was used to monitor acetylcholine levels in the local interstitial fluid in rat submandibular glands, with the aim of determining parasympathetic nerve activity in vivo. The dialysis probe housed a 10 × 0.22 mm semipermeable membrane (molecular weight cutoffs: 50,000 Da). When the probe was perfused at 2 μL/min in vitro, the mean relative recovery of acetylcholine was 41.7% ± 2.5%. The dialysis probes were implanted in the submandibular glands of anesthetized rats and perfusion with Ringer’s solution, at 2 μL/min, was performed. Acetylcholine concentrations in the dialysate were measured by high-performance liquid chromatography and electrochemical detection. The results revealed the following: (1) that mixing Eserine with Ringer’s solution allowed acetylcholine in the salivary glands to be quantified; (2) that acetylcholine concentrations in the dialysate were highly variable and unstable over the first 120 min after probe implantation, but reached a nearly stable level (4.8 ± 2.7 nM) thereafter in the presence of 100 µM of Eserine; and (3) that electrical stimulation of the chorda tympani nerve, or perfusion with high potassium Ringer’s solution, significantly increased acetylcholine concentrations in the dialysate. These results indicate that the present microdialysis technique offers a powerful tool for detecting changes in parasympathetic activity within the salivary glands.

Glucan Conversion and Membrane Recovery of Biomimetic Cellulosomes During Lignocellulosic Biomass Hydrolysis.

Enzyme immobilization has been identified as one way to recycle enzymes and reduce processing costs during enzymatic hydrolysis of lignocellulosic materials. However, most immobilization methods have not been attractive to lignocellulosic processing plants. In this study, cellulase enzymes were attached to a copolymer of glycidyl methacrylate (GMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) to make polymer-enzyme conjugates (PECs) and facilitate recovery using a 50-kDa molecular weight cutoff membrane. Glucan conversion during biomass hydrolysis was investigated using new PECs and PECs recovered after an initial hydrolysis stage. Enzyme immobilization on PECs did not reduce effectiveness during the initial hydrolysis. Temperature and pH showed similar effects on free enzymes and PECs. PECs facilitated higher conversion rates than free enzymes at high biomass loadings. Recovered PECs were used to achieve approximately 100% glucan conversion in a subsequent hydrolysis step when supplemented with 40% of the free enzyme used in the first stage. The combination of PECs and membrane recovery has the potential to reduce hydrolysis cost during cellulosic bioprocessing.