Intermediate Pore Research Articles

Dissecting the effect of substrate on polyamide reverse osmosis membranes via regulating substrate pore size by drying shrinkage

Several studies have proved that the substrate significantly influences the chemical properties of reverse osmosis (RO) membranes, whereas the underlying mechanisms remain elusive. Herein, we adjusted the substrate pore size from 8.6 nm to 4.4 nm by drying shrinkage, ensuring the substrate's chemical properties remained consistent. Interestingly, we observed that an intermediate pore size (7.4 nm) of the substrate resulted in the highest exotherm, with the interfacial temperature rising to 26.8 °C, thus showing that larger pore sizes do not necessarily result in more pronounced exothermic interfacial polymerization (IP) reactions. Through multiscale simulations and various characterization techniques, we found that the IP reaction is governed by two competing effects: (1) the storage capacity of MPD, which provides the reactive monomers; and (2) the water content, which absorbs the heat in the IP reaction. Balancing these two competing factors contributes to enhancing the diffusion of MPD, thereby promoting the progression of the IP reaction. This work revealed a new mechanism through which the substrate affects RO membrane formation.

Fabrication and application of highly permeable ceramic membranes: Membrane-forming mechanism, pore structure, separation performance and fouling mechanism analyses

High separation efficiency and satisfactory economic benefits are of great importance for ceramic membranes in the field of water treatment. Herein, microfiltration ceramic membrane with high permeability and selectivity was prepared in one-step (dip-coating and sintering) by sacrificial-interlayer method. The membrane-forming mechanism, effect of temperature on the morphology and pore structure, separation performance, fouling mechanism, and regeneration performance of the ceramic membranes were systematically investigated. The results show that membrane-forming mechanism of the membranes largely depends on film-coating filtration. The membrane with a mixture of nanocellulose crystals and graphene oxide as sacrificial interlayer (C1G1) and sintered at 1100–1300 °C possessed smooth surface. The open porosity and average pore size increased, and the pore size distribution became broader as the temperature increased. Moreover, the sacrificial-interlayer membrane sintered at 1300 °C (mA4S-C1G1) possessed suitable porosity (53.4%) and average pore size (200 nm), high permeance (4828 L·m−2·h−1·bar−1), which was larger than that of the membrane without sacrificial interlayer, manifesting that C1G1 could prevent the penetration of membrane-forming particles into support. The final fouling mechanism of mA4S-C1G1 was cake filtration, although complete pore blocking, standard pore blocking, intermediate pore blocking also involved in the initial stage. In addition, the oil rejection rate (∼97%) and steady-state feed flux (810–1154 L·m−2·h−1) of mA4S-C1G1 was high, and it also possessed good regeneration performance.

Impact of aminopropyl units on physisorption in mesostructured silica is larger for CH4 than CO2 and depends on pore curvature

Mesoporous silica-based materials attract great interest for diverse applications, including capture, storage, and catalysis due to their large surface area, uniform pore size distribution, and customizable surface. The regular 2D hexagonal pore symmetry of MCM-41 makes it an ideal model. Amine groups are introduced to enhance CO2 adsorption, but the interplay of factors influencing overall performance, including pore size, remains unclear. This computational study explores the physisorption of CO2 and CH4, shedding light on the microscopic details underlying adsorption capacity and selectivity. Three aminopropyl-functionalized MCM-41 models with different pore size are compared through Grand Canonical Monte Carlo and Molecular Dynamics simulations. Aminopropyl chains affect CO2 adsorption, but its affinity for the preserved silanol groups is larger. In addition, the competitive interaction between amine and silanol groups emerged, and it is pore curvature dependent. Surprisingly, CH4 physisorption is influenced even more by surface functionalization. Results show a non-monotonic trend as a function of pore size. Local density of the alkyl chains plays the major role. Overall, the intermediate pore size demonstrates the best performance, thanks to the balance among the various effects. The study emphasizes the importance of understanding the interplay between material texture and gas interactions to optimize adsorption performance.

A three-mechanism (intermediate pore blocking, standard pore blocking and cake filtration) model considering correction of effective filtration area

A general three-mechanism (intermediate pore blocking, standard pore blocking and cake filtration) model considering correction of the effective filtration area based on Darcy's law, Hagen-Poiseuille equation and Hermes’ law was firstly developed to describe the variation of trans-membrane pressure (∆p(t)) in the constant flowrate cross-flow filtration mode by using EPS model solutions (bovine serum albumin (BSA), sodium alginate (SA) and humic acid (HA)). Results showed that the model predictions fitted well with the experimental data (the single EPS model solution (R2≥0.904), the binary EPS model solution (R2≥0.910) and the ternary EPS model solution (R2≥0.878)). For all model solution, the domination mechanism in the first stage was intermediate pore blocking, while that in the second stage was cake filtration. Meanwhile, higher flux or concentration would led to the transition point appear earlier, while higher cross-flow velocity made it appear later. Moreover, the predictive accuracy of the proposed model improved by 1.25 % compared with that without considering the correction of the effective filtration area. Also, the proposed model was also validated using other membranes (polyvinylidene fluoride (PVDF) and polyether sulfone (PES) membranes) (R2≥0.953) and other feed suspensions (yeast, kaolin and activated sludge suspensions) (R2≥0.981).

Investigating the Fouling Models of the Microfiltration Mixed Matrix Membranes-Based Oxide Nanoparticles Applied for Oil-in-Water Emulsion Separation

Membrane fouling is a major problem encountered in the use of microfiltration (MF) processes to separate the emulsified oil from water. This work involves assessing the efficacy of removing oil-in-water emulsion (O/W emulsion), and evaluating fouling resistance by studying the membrane morphology before and after fouling, and after washing with different cleaning solutions via field emission scanning electron microscopy (FESEM) analysis. Also, the fundamental mechanism involved in the flux drop during crossflow MF has been assessed using models such as the Hermia blocking models and the modified model by Field. The standard and intermediate pore blocking models provided the best prediction for experimental behavior when analyzing the decay in the flux with time for the bio silicon oxide/polyvinylchloride (B-SiO2/PVC) membrane and the stannic oxide/polyvinylchloride (SnO2/PVC) membrane. This research established regression equations of the flux for both membranes in which these equations are highly correlated with R2 of 98.33% for B-SiO2/PVC and R2 of 99.52% for SnO2/PVC using the surface response methodology (RSM). The high flux recovery ratio (FRR) is indicative of the improved antifouling feature of the manufactured membranes where it was 96.8% for B-SiO2/PVC and 94.6% for SnO2/PVC. The results obtained by Hermia and Field were in good agreement with RSM analysis supporting the standard pore-blocking mechanism.

Impact of membrane characteristics and chemical ageing on algal protein fouling behaviour of ultrafiltration membranes

Membrane characteristics can exacerbate the prevailing challenges associated with membrane fouling in industry. However, the combined impact of deliberate membrane modifications and the unavoidable effects of chemical ageing on fouling behaviour is still not well understood. In this study, three polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes with different pore size and surface roughness were selected and subject to chemical ageing with 5000 ppm sodium hypochlorite (NaOCl) at pH 10.5, selected to simulate accelerated ageing conditions. The impact of NaOCl on membrane characteristics was assessed for exposure times from 1.2 x 105 to 25.2 x 105 ppm·h using scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, contact angle, and clean water resistance analysis. The fouling behaviour of each pristine and aged membrane was compared using 10 mg C·L−1 dissolved organic carbon algal protein feed containing 18 % biopolymeric compounds. The membrane with intermediate pore size presented lower overall filtration resistance compared to the membrane with smaller pores that developed rapid foulant cake layers. It also displayed less susceptibility to fouling via pore blocking mechanisms compared to membranes with larger pores where greater surface area available in pore walls leads to higher foulant adhesion.

Experimental Study of a Sequential Membrane Process of Ultrafiltration and Nanofiltration for Efficient Polyphenol Extraction from Wine Lees.

The wine industry is a sector of great importance in the Spanish economy, contributing substantial annual revenues. However, one challenge facing the industry is the amount of waste generated, reaching millions of tons annually. These residues consist of organic matter of industrial interest, such as polyphenols. These substances are characterised by their excellent antioxidant properties, making them ideal for use in the food, cosmetic, and pharmaceutical industries. Modern techniques, such as membrane technology, are explored for their extraction based on separating compounds according to size. This work studies a sequential filtration process using ultrafiltration (UF) and nanofiltration (NF) membranes at different operating conditions (2 bar and 9.5 bar for UF and NF, respectively, at 20 °C) to extract polyphenols from wine lees. The results show a total polyphenols rejection rate for each process of 54% for UF and 90% for NF. Pore blocking models have been studied for the UF process and an intermediate pore blocking of the membrane upon wine lees filtration has been identified. A mathematical model that justifies the behavior of a polymeric NF membrane with the filtration of pre-treated vinasse residues has been validated. This study shows a viable process for extracting polyphenols from wine lees with sequential membrane technology.

Microporous electrospun nonwovens combined with green solvents for the selective peel-off of thin coatings from painting surfaces

Over the last few decades, significant research efforts have been devoted to developing new cleaning systems aimed at preserving cultural heritage. One of the main objectives is to selectively remove aged or undesirable coatings from painted surfaces while preventing the cleaning solvent from permeating and engaging with the pictorial layers. In this work, we propose the use of electrospun polyamide 6,6 nonwovens in conjunction with a green solvent (dimethyl carbonate). By adjusting the electrospinning parameters, we produced three distinct nonwovens with varying average fiber diameters, ranging from 0.4 μm to 2 μm. These samples were characterized and tested for their efficacy in removing dammar varnish from painted surfaces. In particular, the cleaning process was monitored using macroscale PL (photoluminescence) imaging in real-time, while post-application examination of the mats was performed through scanning electron microscopy. The solvent evaporation rate from the different nonwovens was evaluated using gravimetric analysis and Proton Transfer Reaction- Time-of-Flight. It was observed that the application of the nonwovens with small or intermediate pore sizes for the removal of the terpenic varnish resulted in the swollen resin being absorbed into the mats, showcasing a peel-off effect. Thus, this protocol eliminates the need for further potentially detrimental removal procedures involving cotton swabs. The experimental data suggests that the peel-off effect relates to the microporosity of the mats, which enhances the capillary rise of the swollen varnish. Furthermore, the application of these systems to historical paintings underwent preliminary validation using a real painting from the 20th century.

Identification of Membrane Fouling with Greywater Filtration by Porous Membranes: Combined Effect of Membrane Pore Size and Applied Pressure.

Membrane fouling caused by complex greywater synthesized by personal care products and detergents commercially available for household applications was investigated using dead-end microfiltration (MF) and analyzed systematically by a multistage Hermia blocking model as a first attempt. The highest flux decline was associated with the smallest pore size of the membrane (0.03 μm). This effectiveness was more pronounced at higher applied pressures to the membrane. A cake layer was formed on the membrane consisting mainly of silica particles present as ingredients in greywater. Although organic rejection was low by the porous MF membrane, the organic compound contributed to membrane fouling in the filtration stage. With a 0.03 μm pore size of the membrane, dominant fouling mechanisms were classified into three stages as applied pressure increased, such as complete pore blocking, intermediate pore blocking, and cake layer formation. Specifically, during the early stage of membrane filtration at 1.5 bar, membrane fouling was determined by complete pore blocking in the 0.10 μm pore size of the membrane. However, the later stage of membrane fouling was controlled mainly by intermediate pore blocking. Regardless of the applied pressure, pore constriction or standard blocking played an important role in the fouling rate with a 0.45 μm pore size of the membrane. Our results also support that complex formation can occur due to the concentration of organic and inorganic species present in simulated greywater. Thus, strategic approaches such as periodic, chemically enhanced backwashing need to be developed and tailored to remove both organic and inorganic fouling from MF membranes treating greywater.

Prediction of reverse osmosis membrane fouling in water reuse by integrated adsorption and data-driven models

In contemporary society, the reverse osmosis (RO) process is important for water treatment and reuse industry. However, membrane fouling remains a challenging issue during operation. To date, RO system operation mainly relies on the operator's knowledge, and the maintenance is carried out based on schedule or pre-defined criteria due to our limited understanding of RO fouling in real applications. To better understand the process and enable system optimization, an integrated data-driven coupled with adsorption model has been proposed in this study. The data-driven model calibrates the mechanistic model and predicts future values, while the adsorption model provides predictions on transmembrane pressure (TMP). By integrating these two models, an accurate prediction with high robustness and an insight into the detailed fouling mechanisms in real plants were achieved. In addition to the model itself, multiple regression analysis (MRA) had also been applied to identify the dominant fouling mechanisms. This analysis confirms that it is highly possible that membrane fouling is developed from an intermediate pore blockage to cake filtration.

Three membrane fusion pore families determine the pathway to pore dilation

During exocytosis secretory vesicles fuse with a target membrane and release neurotransmitters, hormones, or other bioactive molecules through a membrane fusion pore. The initially small pore may subsequently dilate for full contents release, as commonly observed in amperometric traces. The size, shape, and evolution of the pore is critical to the course of contents release, but exact fusion pore solutions accounting for membrane tension and bending energy constraints have not been available. Here, we obtained exact solutions for fusion pores between two membranes. We find three families: a narrow pore, a wide pore, and an intermediate tether-like pore. For high tensions these are close to the catenoidal and tether solutions recently reported for freely hinged membrane boundaries. We suggest membrane fusion initially generates a stable narrow pore, and the dilation pathway is a transition to the stable wide pore family. The unstable intermediate pore is the transition state that sets the energy barrier for this dilation pathway. Pore dilation is mechanosensitive, as the energy barrier is lowered by increased membrane tension. Finally, we study fusion pores in nanodiscs, powerful systems for the study of individual pores. We show that nanodiscs stabilize fusion pores by locking them into the narrow pore family.

From molecular sieving to gas effusion through nanoporous 2D graphenes: Comparison between analytical predictions and molecular simulations.

In this paper, we study the permeation of polyatomic gas molecules through 2D graphene membranes. Using equilibrium molecular dynamics simulations, we investigate the permeation of pure gas compounds (CH4, CO2, O2, N2, and H2) through nanoporous graphene membranes with varying pore sizes and geometries. Our simulations consider the recrossing mechanism, often neglected in previous studies, which has a significant effect on permeation for intermediate pore size to molecular diameter ratios. We find that the permeation process can be decoupled into two steps: the crossing process of gas molecules through the pore plane and the escaping process from the pore region to a neighboring adsorption site, which prevents recrossing. To account for these mechanisms, we use a permeance model expressed as the product of the permeance for the crossing process and the probability of molecule escape. This phenomenological model is extended to account for small polyatomic gas molecules and to describe permeation regimes ranging from molecular sieving to effusion. The proposed model captures the temperature dependence and provides insights into the key parameters of the gas/membrane interaction controlling the permeance of the system. This work lays the foundation for predicting gas permeance and exploring membrane separation factors in 2D materials such as graphene.

Zeolite membrane separators for fire-safe Li-ion batteries – Effects of crystal shape and membrane pore structure

The state-of-the-art lithium-ion batteries (LIB) use carbonate-based liquid electrolytes and polymeric separators which pose safety issues including fire-hazard. The use of fire-retarding salt-concentrated electrolytes can address the safety issues of LIBs, but these electrolytes have high viscosity and low wettability with polymeric separators making it difficult to fabricate high performance LIBs with the electrolytes. Here we report development of zeolite membrane separators with tailored pore structure and surface chemistry for preparation of fire-safe LIBs using salt-concentrated electrolytes. The zeolite membrane separators are made of zeolite particles with a specific zeolite structure, Si/Al ratio, and different particle shapes, coated on cathode by a scalable blade coating method. Intermediate pore, pure silica MFI-type zeolite (silicalite) was selected as the fire-proof material for membrane separators which also offer high wettability for the fire-retarding salt-concentrated electrolyte of lithium bis(fluorosulfonyl)imide (LiFSI) in tri-methyl phosphate solvent (TMP) solvent. Two silicalite membrane separators of similar pore size but different porosity and tortuosity were coated on cathode (LiNi0.5Mn0.3Co0.2O2 or NMC) using plate-shaped silicalite particles of low aspect ratio (LAR) and high aspect ratio (HAR). Both zeolite separators show significantly better wettability for the LiFSI/TMP electrolyte than the commercial polypropylene (PP) separator allowing fabrication of high-performance NMC/LiFSI-TMP/graphite cells with the non-combustible silicalite separator. The new fire-safe zeolite-membrane-based LIBs with the fire-retarding electrolyte exhibit excellent charge and discharge characteristics and cycle performance (similar to the state-of-the-art, but fire-unsafe LIBs with LiPF6-carbonate electrolyte and polymer separator). The membrane separators made of HAR plate-shaped zeolite showing low interparticle porosity and high tortuosity perform better than the membrane made of LAR zeolite particles, due to a more uniform lithium-ion flux from both interparticle pores and intraparticle zeolitic pores at the separator/anode interface.

Assessment of natural tannin-based coagulant for effective ultrafiltration (UF) of UASB effluent: Fouling mechanisms, pollutant removal and water reclamation feasibility

In this work, tannin coagulant (TANm) was applied at different dosages and compared with a PACl for UASB effluent filterability enhancement during membrane ultrafiltration. The results showed that TANm exhibited the greatest potential to improve UASB effluent filterability. Flux decay, total fouling resistance, and specific cake layer resistance were all reduced by both coagulants. However, the highest flux (55%) and fouling resistance reduction (70%) were obtained with 40 mg.L−1 of TANm, which was caused by an increase in particles larger than 200 μm, facilitating its removal by cross-flow filtration. Protein and carbohydrate reduction in the membrane was only observed at 25 mg.L−1 for both coagulants, with a higher influence of proteins in strongly/very strongly bound for all samples. In addition, fouling irreversibility increases, with a strong correlation between TANm dosage and Rirr and complete and intermediate pore blocking pointed as the main mechanisms responsible for irreversibility for both coagulants. Based on these and other findings, the mechanisms of the fouling layer adhered to the membrane with coagulants included the formation of complexes with proteins that were more strongly adhered (related to UASB effluent zeta potential increase), the density of the cake layer due to the presence of compact aggregates, and action of the coagulants themselves as foulants. Lastly, the economic evaluation revealed that the system without coagulant would have a lower total cost, but payback showed that the application of TANm has a lower investment time of return due to a lesser CAPEX.

Breathing Behaviour Modification of Gallium MIL-53 Metal-Organic Frameworks Induced by the Bridging Framework Inorganic Anion.

Controlling aspects of the μ2 -X- bridging anion in the metal-organic framework Ga-MIL-53 [GaX(bdc)] (X- =(OH)- or F- , bdc=1, 4-benzenedicarboxylate) is shown to direct the temperature at which thermally induced breathing transitions of this framework occur. In situ single crystal X-ray diffraction studies reveal that substituting 20 % of (OH)- in [Ga(OH)(bdc)] (1) for F- to produce [Ga(OH)0.8 F0.2 (bdc)] (2) stabilises the large pore (lp) form relative to the narrow pore (np) form, causing a well-defined decrease in the onset of the lp to np transition at higher temperatures, and the adsorption/desorption of nitrogen at lower temperatures through np to lp to intermediate (int) pore transitions. These in situ diffraction studies have also yielded a more plausible crystal structure of the int-[GaX(bdc)] ⋅ H2 O phases and shown that increasing the heating rate to a flash heating regime can enable the int-[GaX(bdc)] ⋅ H2 O to lp-[GaX(bdc)] transition to occur at a lower temperature than np-[GaX(bdc)] via an unreported pathway.

Tangential microfiltration of lime and pineapple juices using inexpensive tubular ceramic membrane and analysis of fouling mechanism

A non-thermal tangential filtration of lime and pineapple juices using an indigenously elaborated inexpensive bentonite-based tubular ceramic membrane (96 $/m2) is discussed in the present work. The fabricated membrane exhibited a porosity of 37% with 0.11 µm pore size and possessed adequate flexural stability of 18 MPa. Microfiltration experiments were conducted for both centrifuged juice (CJ) and Enzymatic treated centrifuged juice (ETCJ) of lime and pineapple at various operating pressures (69 – 345 kPa) and crossflow rates (110 – 150 Lph) to evaluate their effects on the resulting permeate flux and clarified juice properties. The membrane provided a maximum permeate flux of both ETCJ of lime and pineapple juices as 2.22 × 10−5 m3/m2s and 1.31 × 10−5 m3/m2s, respectively, at operating conditions of 345 kPa pressure and 150 Lph flowrate. Enzymatic pretreatment considerably enhanced the permeate fluxes of both juices. Also, comparatively a high clarity and complete removal of alcohol-insoluble solids were observed for permeate streams of ETCJ. In all the cases, the desirable characteristics of citrus juices, including pH, total soluble solids, and citric acid content, were unaltered, ensuring the uniqueness of the membrane separation processes. Furthermore, fouling analysis was carried out using Hermia's models, revealing experimental data best fits into the cake filtration model for pineapple juice and intermediate pore blocking model for lime juice clarification are identified as dominant mechanisms, respectively.

Differential development characteristics of secondary pores and effects on pore structure and movable fluid distribution in tight gas sandstones in the lower Permian, northeastern Ordos Basin, China

The lower Permian tight gas sandstones (TGSs) in the northeastern Ordos Basin have developed a complex pore network composed mainly of secondary pores with strong reservoir heterogeneity, which affects evaluation and exploitation of gas resources. In this study, lower Permian TGSs were analyzed through the thin sections, scanning electron microscopy, X-ray diffraction, He porosimetry, high-pressure mercury injection capillary pressure, X-ray computed tomography, and nuclear magnetic resonance experiments to elucidate the differential developmental characteristics of secondary pores and their effects on the pore structures and movable fluid distribution. Secondary pores in the lower Permian TGSs include dissolution pores associated with feldspar dissolution and micropores related to authigenic clay minerals. Based on fractal results, we designated the first-order dissolution pores as those with pore throat diameters greater than 1.98 μm, the second-order dissolution pores as those with pore throat diameters between 0.05 and 1.98 μm, and the pore throats diameters of micropores are mainly smaller than 0.05 μm. Both volumetric feldspar leaching calculations and petrographic statistics suggest that the secondary porosity observed in the lower Permian TGSs may not represent a net increase in porosity and more likely represents a redistribution of the original porosity. Dissolution requires sandstones with nonnegligible initial porosity and permeability: coarse-grained, quartz-rich, low proportion of ductile grains sandstones are more likely to maintain high porosity during burial, and dissolution of coarse-grained feldspar facilitates the development of first-order dissolution pores, thus generating the highest redistributed secondary porosity. The first-order dissolution pores have wide pore throat diameters, which enable seepage of movable fluids; the second-order dissolution pores have intermediate pore throat diameters, which allow moderate movable fluid seepage; and the micropores have small pore throat diameters, which are not conducive to seepage of movable fluids. Combinations of different types of secondary pores lead to differences in pore structures and distributions of movable fluids in the lower Permian TGSs. Specifically, TGSs with high first-order dissolution porosity have better pore structures, corresponding to the highest movable fluid saturation (MFS) and movable fluid porosity (MFP). When micropores dominate the pore system, the pore structure and pore network connectivity are poor, and the MFS and MFP decrease.

3D printed structured porous hydrogel promotes osteogenic differentiation of BMSCs

Hydrogel is a suitable material for three-dimensional cell culture, and is rich in water content and can better simulate a natural extracellular matrix. However, the relatively compact pores in the interior often inhibit the growth and differentiation of containing cells. Additionally, the impact of the pore structure on the differentiation of cells remains to be unknown. In this work, porous hydrogel scaffolds with medium pore sizes (100–1000 μm) were prepared using 3D printing technology, and the hydrogel scaffolds without pores and non-printed hydrogel scaffolds were designed as control to investigate the effect of 3D printed porous structures on osteogenic differentiation of BMSCs within hydrogel scaffolds, both in vitro and in vivo. The pore structure of 3D printed structured porous scaffold was explicitly inspected by SEM. The water content and expansion rate of hydrogel did not change, despite its porous structure. The BMSCs were evenly distributed across the porous scaffold and maintained high activity, thus benefiting from the sufficient circulation and diffusion of oxygen and nutrients due to the regular pores. In vitro, the osteogenic differentiation of BMSCs in the structured porous hydrogels was more prominent compared to the non-porous groups. Moreover, the mineralization of the hydrogel scaffolds was also enhanced. After ectopic implantation in the posterior gluteal muscle punch, the structured porous hydrogel exhibited relatively good mineralization and ectopic osteogenesis by the three-dimensional reconstruction of micro-CT, collagen staining, and immunological analysis. The 3D printing-based approach provides a facile strategy for the preparation of hydrogels with intermediate pore structures. This can promote the viability and osteogenic differentiation of BMSCs in hydrogel scaffolds.

Fructose Diet-Associated Molecular Alterations in Hypothalamus of Adolescent Rats: A Proteomic Approach

The enhanced consumption of fructose as added sugar represents a major health concern. Due to the complexity and multiplicity of hypothalamic functions, we aim to point out early molecular alterations triggered by a sugar-rich diet throughout adolescence, and to verify their persistence until the young adulthood phase. Thirty days old rats received a high-fructose or control diet for 3 weeks. At the end of the experimental period, treated animals were switched to the control diet for further 3 weeks, and then analyzed in comparison with those that were fed the control diet for the entire experimental period. Quantitative proteomics identified 19 differentially represented proteins, between control and fructose-fed groups, belonging to intermediate filament cytoskeleton, neurofilament, pore complex and mitochondrial respiratory chain complexes. Western blotting analysis confirmed proteomic data, evidencing a decreased abundance of mitochondrial respiratory complexes and voltage-dependent anion channel 1, the coregulator of mitochondrial biogenesis PGC-1α, and the protein subunit of neurofilaments α-internexin in fructose-fed rats. Diet-associated hypothalamic inflammation was also detected. Finally, the amount of brain-derived neurotrophic factor and its high-affinity receptor TrkB, as well as of synaptophysin, synaptotagmin, and post-synaptic protein PSD-95 was reduced in sugar-fed rats. Notably, deregulated levels of all proteins were fully rescued after switching to the control diet. A short-term fructose-rich diet in adolescent rats induces hypothalamic inflammation and highly affects mitochondrial and cytoskeletal compartments, as well as the level of specific markers of brain function; above-reported effects are reverted after switching animals to the control diet.

Ultrasonication-assisted fouling control during ceramic membrane filtration of primary wastewater under gravity-driven and constant flux conditions

This study investigated the feasibility of using ultrasonication as a ceramic microfiltration membrane fouling control strategy during gravity-driven membrane (GDM) filtration and constant flux filtration of primary municipal wastewater. The fouling model fitting curves revealed that initial intermediate pore blocking was dominant in the GDM system, followed by cake filtration; while cake filtration was dominant during constant flux filtration with a continuously increasing pattern. In the GDM system, periodic ultrasonication cleaning achieved higher cake resistance reduction (∼60 % vs ∼ 26 %) and led to lower specific cake resistances (0.2–2.0 × 107vs 29.6–59.3 × 107 m/mg) compared to periodic backwash. Ultrasonication-facilitated fouling mitigation effectiveness was related to cake properties (such as cake foulant density and porosity) and improved with extending ultrasonication duration. The foulant examination indicated that ultrasonication may result in porous cake nature by cake expansion and facilitate detaching particulate foulants and soluble organics (such as biopolymers) from the membrane. Cost analysis revealed that with commercial ceramic membranes, ultrasonication-facilitated GDM systems are economically feasible for treating wastewater at a household scale (∼1.1 EUR/m3 water), while ultrasonication-facilitated constant flux filtration systems are favorable at a small-community scale (∼0.5 EUR/m3 water). Furthermore, it was predicted that the use of low-cost recycled ceramic membranes would allow GDM systems as economical decentralized wastewater treatment processes due to their lower water production cost (∼0.16 EUR/m3 water) with easy operation and maintenance.