Colloidal 2D Covalent Organic Framework-Tailored Nanofiltration Membranes for Precise Molecular Sieving.

Covalent organic frameworks (COFs) with tunable pore sizes and ordered structures are ideal materials for engineering nanofiltration (NF) membranes. However, most of the COFs prepared by solvothermal synthesis are unprocessable powders and fail to form well-structured membranes, which seriously hinders the development of COF NF membranes. Herein, colloidal 2D-COFs with processable membrane formation ability were synthesized by oil-in-water emulsion interfacial polymerization technology. COF NF membranes with tailored thickness and surface charge were fabricated via a layer-by-layer (LBL) assembly strategy. The prepared COF NF membrane achieved precise sieving of dye molecules with high permeance (85 L·m-2·h-1·bar-1). In this work, the strategy of prepared COF NF membranes based on colloid 2D-COF LBL assembly is proposed for the first time, which provides a new idea for the on-demand design and preparation of COF membranes for precise molecular sieving.

Multibranched flower-like ZnO anchored on pectin/cellulose nanofiber aerogel skeleton for enhanced comprehensive antibacterial capabilities.

In this study, F-ZnO NPs were used as antibacterial agents, mussel bionic dopamine exerted its adhesive action to immobilize F-ZnO NPs on the pectin/CNF aerogel skeleton. Fruit and vegetable antimicrobial mats with safety, long duration of action and high efficiency were prepared and its potential application has been investigated. The results showed that a dopamine layer was deposited on the surface of the CNF, which promoted the tight adhesion of the F-ZnO NPs to the aerogel skeleton. The F-ZnO@D-CNF aerogel exhibited a slow release of zinc ions, with the first two days being 0.40 ± 0.16 and 1.01 ± 0.13 mg/mL. The aerogel was light, can stand on the petals without collapsing, has regular and uniform pore structure, good tensile/compressive properties and high antibacterial/anti-fungal properties. Strawberries packaged with F-ZnO@D-CNF aerogel exhibited an extended shelf life of 5 days. Additionally, the strawberries maintained a soluble solid content of 6.9 ± 0.82 % and a Vc content of 44.67 ± 3.51 mg/100 g. The weight loss, color and firmness were also notably superior to the other four groups. The final concentration of zinc ions in strawberries was 3.71 ± 0.28 µg/g, which is far below the recommended dietary intake.

Diatom-Inspired TiO2-PANi-Decorated Bilayer Photothermal Foam for Solar-Driven Clean Water Generation.

Interfacial solar-driven evaporation provides one of the most promising green and sustainable technologies to deal with the knotty water crisis by extracting vapor from a variety of water sources powered by solar energy. Advanced photothermal materials play critical roles in interfacial solar-driven evaporation by photothermal conversion and heat localization. Herein, inspired by the unique hierarchical structure and light-harvesting function of diatoms, we propose a novel photothermal material with a diatom-like hierarchical nanostructure derived from TiO2-PANi-decorated bilayer melamine foam (TiO2-PANi@MF) for solar-driven clean water generation. The diatom-like hierarchical nanostructured TiO2-PANi@MF can realize full-spectrum light absorption and photothermal conversion by enhancing multiple light reflection and light scattering. Thanks to the diatom-like hierarchical nanostructure, TiO2-PANi@MF not only impressively achieves an evaporation rate of 2.12 kg m-2 h-1 under 1 sun irradiation but also shows a high solar steam conversion efficiency up to 88.9%. Notably, the TiO2-PANi composite also endows TiO2-PANi@MF with photocatalytic degradation capability. Apart from the excellent steam generation capability, optimized TiO2-PANi@MF also provides the high photocatalytic efficiency of dye degradation and maintains a high evaporation rate of more than 2 kg m-2 h-1. We believe that the proposed photothermal material with a diatom-like hierarchical nanostructure can envision promising practical applications in seawater desalination and sewage purification.

Preparation of Low-Lactose Milk Powder by Coupling Membrane Technology.

Due to lactose intolerance, there is a growing need for lactose-free or low-lactose dairy products. Herein, a combination of three membrane technologies (UF, electrodialysis (ED), and nanofiltration (NF)) was used as a novel green technology to replace the enzymatic preparation of low-lactose milk powder in the traditional industry. In which, large molecules such as proteins and fats are first retained using UF, mineral salt was intercepted and re-added into milk by electrodialysis, and finally, lactose is recovered by NF. Finally, low-lactose milk powder with a lactose content of less than 0.2% was obtained; meanwhile, the high purity (95.7%) of lactose powder could be effectively reclaimed from the NF concentrate (lactose concentrate). The whole membrane process is based on the physical pore size screening mechanism, without adding any chemical reagents with minimal impact on the physical and chemical properties of milk. These results indicate that process development and optimization coupling of three membrane technologies is very promising in preparing low-lactose milk powder and recovering lactose.

Development of polyvinyl alcohol/ß-cyclodextrin antimicrobial nanofibers for fresh mushroom packaging.

Under the optimal conditions, a crosslinked electrospun polyvinyl alcohol/cinnamon essential oil/ß-cyclodextrin (CPVA-CEO-ß-CD) nanofibrous films for sustained release of antimicrobials were successfully prepared. Cinnamon essential oil (CEO) can be sustainably released due to CPVA-CEO-ß-CD nanofibers complex delivery systems. The chemical crosslinking and physical welding achieved simultaneously by glutaraldehyde atomization fumigation, making fibers more suitable for fresh food packaging. Nanofibrous films were characterized in terms of SEM, ATR-FTIR, DSC, water contact angle analysis and antibacterial trials. ATR-FTIR and DSC data indicated that CEO was encapsulated in a ß-CD cavity and they coexisted in PVA nanofibers. The water contact angle of the crosslinked PVA nanofibrous films increased with CEO and the values were always below 90°. Crosslinked nanofibers possessed fine properties in vitro antibacterial against Staphylococcus aureus and Escherichia coli. Furthermore, CPVA/ß-CD/CEO nanofibrous films delayed decay of mushroom during storage, indicating their potential implementation in active food packaging.

A novel nanofiltration membrane inspired by an asymmetric porous membrane for selective fractionation of monovalent anions in electrodialysis.

The present study describes the synthesis of new nanofiltration membranes inspired by asymmetric porous membranes used as monovalent anion selective membranes for electro-membrane separation. The membrane surface was firstly modified, by deposition of a mussel-inspired "bio-glue" polydopamine (PDA) layer, and subsequently a compact polyamide layer was polymerized on the surface of the membrane's active layer. The chemical constitution and structure of these modified porous membranes were explored by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The surface roughness and hydrophilicity of the membranes were explored by atomic force microscopy (AFM) and water contact angle measurements, respectively. In addition, the electrochemical properties of the surface of the modified membranes were analyzed in terms of membrane surface resistance and zeta potential values. As for the performance of these modified porous membranes, this was investigated by measuring the permselectivity of a Cl-/SO4 2- system. The obtained results show that the new membranes exhibit an enhanced monovalent anion permselectivity, which is in agreement with the improved membrane surface properties. Furthermore, membranes modified by the addition of a PDA layer and a dense polyamide active layer lead to a significant improvement in selectivity , compared with a conventional interfacial polymerization modified membrane . The excellent performance can be ascribed to the synergistic effect of the compact PDA layer and negatively charged interfacial polymerization layer, dependent on the sieving and electrostatic repulsion, respectively. Thus, this process is promising for the further development of porous monovalent selective anion exchange membranes.

Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane.

A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl-/SO42- separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl-/SO42- permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later.

Linear headache: clinical characteristics of eight new cases.

BACKGROUND: Linear headache (LH) has recently been described as a paroxysmal or continuous fixed head pain restricted in a linear trajectory of 5-10 mm in width, linking one endpoint in occipital or occipitocervical region with another endpoint in ipsilateral nasion or forehead region. For some patients, this headache had some features resembling migraine without aura. METHODS: We made a prospective search of patients presenting with a clinical picture comprised under the heading of LH and we have accessed eight new cases. A detailed clinical feature of the headache was obtained in all cases to differentiate with cranial neuralgia, paroxysmal hemicrania, cervicogenic headache, nummular headache and migraine. RESULTS: The eight LH patients complained of a recurrent moderate to severe, distending, pulsating, or pressure-like pain within a strictly unilateral line-shaped area. The headache duration would be ranged from 1 h to 2 days or persistent for 1-6 months with recurrent worsening of headaches. For some patients, this headache had couple of features similar to that of migraine pattern, such as accompaniments of nausea, vomiting, and phonophobia, diziness, triggering factors of noise, bright night, resting after physical activity, fatigue, menstruation, and response to anti-migraine therapy. CONCLUSIONS: This description reinforces the proposal of LH as a new headache syndrome or a new variant of a previously known headache syndrome, probably of migraine.

A recurrent headache circumscribed in a coronal line-shaped area around the head: a coronal linear headache.

BACKGROUND: Linear headache (LH) has recently been described as a paroxysmal or continuous head pain restricted in a linear trajectory of 5-10 mm in width, linking one endpoint in occipital or occipitocervical region with another endpoint in ipsilateral nasion or forehead region. The sagittal line-shaped pain area of LH is close and parallel to a sagittal venous sinus, the superior sagittal sinus (SSS). For some patients, the LH had some features resembling the pattern of migraine without aura. CASE DESCRIPTION: A 45 year-old woman complained with a distinct headache for more than half years. The pain trajectory of the headache is confined to a coronal line-shaped area of 5-10 mm in width linking the two points in the bilateral temporal regions with the occipital protuberance. This coronal line-shaped pain area is close and parallel to a coronal cambered venous sinus complex, the combination of the confluences of sinus and the bilateral cavernous sinus (CS), superior petrosal sinus (SPS) linking the CS with transverse sinus (TS) and TS into which the SPS feeds. The patient had a past history of migraine without aura for 10 years and her son had a benign paroxysmal vertigo (BPV) for 12 years. Both of her coronal line-shaped headache and her son's vertigo had well response to sodium valproate. DISCUSSION AND EVALUATION: Its clinical characteristics were distinctly different from those of other two headache entities defined with topographical criteria, nummular headache and epicrania fugax, and different from other existing headache entities except for migraine without aura. CONCLUSION: The distinct coronal line-shaped headache is suggestive of a variant of LH, a coronal LH, and probably belongs to a subtype of migraine without aura as proposed for LH. This coronal LH reinforces the proposal of LH as a new headache syndrome or a subtype of a previously known headache syndrome, probably of migraine.

A Novel Methodology to Synthesize Highly Conductive Anion Exchange Membranes.

Alkaline polyelectrolyte fuel cell now receives growing attention as a promising candidate to serve as the next generation energy-generating device by enabling the use of non-precious metal catalysts (silver, cobalt, nickel et al.). However, the development and application of alkaline polyelectrolyte fuel cell is still blocked by the poor hydroxide conductivity of anion exchange membranes. In order to solve this problem, we demonstrate a methodology for the preparation of highly OH(-) conductive anion exchange polyelectrolytes with good alkaline tolerance and excellent dimensional stability. Polymer backbones were grafted with flexible aliphatic chains containing two or three quaternized ammonium groups. The highly flexible and hydrophilic multi-functionalized side chains prefer to aggregate together to facilitate the formation of well-defined hydrophilic-hydrophobic microphase separation, which is crucial for the superior OH(-) conductivity of 69 mS/cm at room temperature. Besides, the as-prepared AEMs also exhibit excellent alkaline tolerance as well as improved dimensional stability due to their carefully designed polymer architecture, which provide new directions to pursue high performance AEMs and are promising to serve as a candidate for fuel cell technology.

Novel Pendant Benzene Disulfonic Acid Blended SPPO Membranes for Alkali Recovery: Fabrication and Properties.

To reconcile the trade-off between separation performance and availability of desired material for cation exchange membranes (CEMs), we designed and successfully prepared a novel sulfonated aromatic backbone-based cation exchange precursor named sodium 4,4'-(((((3,3'-disulfo-[1,1'-biphenyl]-4,4'-diyl)bis(oxy)) bis(4,1-phenylene))bis(azanediyl))bis(methylene))bis(benzene-1,3-disulfonate) [DSBPB] from 4,4'-bis(4-aminophenoxy)-[1,1'-biphenyl]-3,3'-disulfonic acid [BAPBDS] by a three-step procedure that included sulfonation, Michael condensation followed by reduction. Prepared DSBPB was used to blend with sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) to get CEMs for alkali recovery via diffusion dialysis. Physiochemical properties and electrochemical performance of prepared membranes can be tuned by varying the dosage of DSBPB. All the thermo-mechanical properties like DMA and TGA were investigated along with water uptake (WR), ion exchange capacity (IEC), dimensional stability, etc. The effect of DSBPB was discussed in brief in connection with alkali recovery and ion conducting channels. The SPPO/DSBPB membranes possess both high water uptake as well as ion exchange capacity with high thermo-mechanical stability. At 25 °C the dialysis coefficients (UOH) appeared to be in the range of 0.0048-0.00814 m/h, whereas the separation factor (S) ranged from 12.61 to 36.88 when the membranes were tested for base recovery in Na2WO4/NaOH waste solution. Prepared membranes showed much improved DD performances compared to traditional SPPO membrane and possess the potentiality to be a promising candidate for alkali recovery via diffusion dialysis.

Oriented MOF-polymer composite nanofiber membranes for high proton conductivity at high temperature and anhydrous condition.

The novel oriented electrospun nanofiber membrane composed of MOFs and SPPESK has been synthesized for proton exchange membrane fuel cell operating at high temperature and anhydrous conditions. It is clear that the oriented nanofiber membrane displays the higher proton conductivity than that of the disordered nanofiber membrane or the membrane prepared by conventional solvent-casting method (without nanofibers). Nanofibers within the membranes are significantly oriented. The proton conductivity of the oriented nanofiber membrane can reach up to (8.2 ± 0.16) × 10(-2) S cm(-1) at 160°C under anhydrous condition for the highly orientation of nanofibers. Moreover, the oxidative stability and resistance of methanol permeability of the nanofibers membrane are obviously improved with an increase in orientation of nanofibers. The observed methanol permeability of 0.707 × 10(-7) cm(2) s(-1) is about 6% of Nafion-115. Consequently, orientated nanofibers membrane is proved to be a promising material as the proton exchange membrane for potential application in direct methanol fuel cells.