Large-Area Soluble Covalent Organic Framework Oligomer Coating for Organic Solution Nanofiltration Membranes.

Covalent organic frameworks (COFs) are a family of engaging membrane materials for molecular separation, which remain challenging to fabricate in the form of thin-film composite membranes due to slow crystal growth and insoluble powder. Here, an additive approach is presented to construct COF-based thin-film composite membranes in 10 min via COF oligomer coating onto poly(ether ether ketone) (PEEK）ultrafiltration membranes. By the virtue of ultra-thin liquid phase and liquid-solid interface-confined assembly, the COF oligomers are fast stacked up and grow along the interface with the solvent evaporation. Benefiting from the low out-plane resistance of COFs, COF@PEEK composite membranes exhibit high solvent permeances in a negative correlation with solvent viscosity. The well-defined pore structures enable high molecular sieving ability (Mw = 300 g mol-1 ). Besides, the COF@PEEK composite membranes possess excellent mechanical integrities and steadily operate for over 150 h in the condition of high-pressure cross flow. This work not only exemplifies the high-efficiency and scale-up preparation of COF-based thin-film composite membranes but also provides a new strategy for COF membrane processing.

Confined Nano-Channels Incorporated with Multi-Quaternized Cations for Highly Phosphoric Acid Retention HT-PEMs.

Developing a new strategy to retain phosphoric acid (PA) to improve the performance and durability of high-temperature proton exchange membrane fuel cell (HT-PEMFC) remains a challenge. Here, a strategy for ion-restricted catcher microstructure that incorporates PA-doped multi-quaternized poly(fluorene alkylene-co-biphenyl alkylene) (PFBA) bearing confined nanochannels is reported. Dynamic analysis reveals strong interaction between side chains and PA molecules, confirming that the microstructure can improve PA retention. The PFBA linked with triquaternary ammonium side chain (PFBA-tQA) shows the highest PA retention rate of 95%. Its H2/O2 fuel cell operates within 0.6% voltage decay at 160 °C/0% RH, and it also runs over 100 h at 100 °C/49% RH under external humidification. This combination of high PA retention, and chemical and dimensional stability fills a gap in the HT-PEMFC field, which requires strict moisture control at 90-120 °C to prevent acid leaching, simplifying the start-up procedure of HT-PEMFC without preheating.

Bioinspired Under-Liquid Dual Superlyophobic Surface for On-Demand Oil/Water Separation.

Porous membranes with under-liquid dual superlyophobic properties, which are difficult to achieve because of a thermodynamic contradiction, have attracted considerable interest in the field of switchable oil/water separation. Herein, a bioinspired mesh membrane with alternating hydrophilic and hydrophobic chemical patterns on its surface that endows it with superamphiphilic and under-liquid dual superlyophobic properties is fabricated by a simple liquidus modification process. The as-prepared membrane possesses a combination of under-oil superhydrophobic and under-water superoleophobic characteristics in the absence of external stimuli. Moreover, it can effectively perform the on-demand separation of various oil/water systems, including immiscible oil/water mixtures and oil/water emulsions owing to its under-liquid dual superlyophobic properties.

Efficient and accurate glycopeptide identification pipeline for high-throughput site-specific N-glycosylation analysis.

Study of site-specific N-glycosylation in complex sample remains a huge analytical challenge because protein glycosylation is structurally diverse in post-translational modifications, resulting in an intricacy of N-glycopeptides. Here we have developed a novel approach for high-throughput N-glycopeptide profiling based on a network-centric algorithm for deciphering glycan fragmentation in mass spectrometry. We performed an extensive validation and a high-throughput N-glycosylation study on serum and identified thousands of N-glycopeptide spectra with high confidence. The results revealed a similar level of glycan microheterogeneity to that of conventional glycomics approach on individual proteins and provided the unique in-depth site-specific information that could only be studied through glycopeptide profiling.

Janus Membranes with Asymmetric Superwettability for High-Performance and Long-Term On-Demand Oil/Water Emulsion Separation.

Current single-function superwettable materials are typically designed for either oil removal or water removal and are constrained by oil density, limiting their widespread applications. Janus membranes with opposite wettability on their two surfaces have recently emerged and present attractive opportunities for on-demand oil/water emulsion separation. Here, a combination strategy is introduced to prepare a Janus membrane with asymmetric superwettability for switchable oil/water emulsion separation. A mussel-inspired asymmetric interface introduction cooperating with the sequence-confined surface modification not only brings about an asymmetric superwettability Janus interface but also guarantees an outstanding stable interface and remarkable chemical stability surfaces. Specifically, the superhydrophilic surface with underwater superoleophobicity can separate surfactant-stabilized oil-in-water emulsions. Conversely, other surface displays opposite superhydrophobicity and superoleophilicity to treat surfactant-stabilized water-in-oil emulsions. Significantly, this superwettable Janus membrane presents superior long-term on-demand oil/water emulsion separation without obvious flux decline and high recovery ability because of its superwettability and superior stability. Furthermore, the asymmetric superwettability enhances the interfacial floatability at air-water interfaces, enabling the design of advanced interfacial materials. The as-prepared superwettable Janus membrane has established a cooperated separation system, overcoming the monotony of conventional superwettable membranes and expanding the application of these specialized membranes to oily wastewater treatment.

Nano-Interlayers Fabricated via Interfacial Azo-Coupling Polymerization: Effect of Pore Properties of Interlayers on Overall Performance of Thin-Film Composite for Nanofiltration.

The supporting layer of nanofiltration membranes is critical to the overall nanofiltration performance. However, conventional supports lack efficient surface porosity, which leads to the limited utilization rate of the polyamide (PA) layer. Herein a double-skin-layer nanofiltration membrane with porous organic polymer nanointerlayers prepared via a two-step interfacial polymerization technique is presented to investigate the effect of the interlayers' pore properties on the performance of the thin-film composite. Nanometer interlayers with different pore sizes are fabricated via interfacial azo-coupling polymerization. The pore properties of the nanointerlayer extremely influence the permeance, where a suitable pore size of 4.22 nm promotes pure water permeance of up to 32.2 L m-2 h-1 bar-1, which is ∼3.8-fold greater than the membrane without an interlayer. However, an interlayer with 0.54 nm pores limits the performance (4.7 L m-2 h-1 bar-1), which is even lower than the unmodified membrane (7.5 L m-2 h-1 bar-1), because of the narrow pores and confined transport mode. However, the confined diffusion rate of amino monomers from the support to interface leads to a thinner PA layer of ∼45 nm and results in high flux. This work provides a facial route for the fabrication of interlayers and facilitate the design of high-performance membrane materials with interlayers.

High-efficiency Pd nanoparticles loaded porous organic polymers membrane catalytic reactors.

An innovative tactic to prepare porous organic polymer membranes was developed via interfacial azo-coupling polymerization. The membranes possess plentiful anchoring sites for loading Pd nanoparticles, and served as a membrane reactor, which exhibits high-performance catalytic reduction with a flux of 27.3 t m-2 day-1 and good long-term stability due to almost zero Pd leaching.

Experimental and numerical analysis of the cooling performance of water spraying systems during a fire.

The water spray systems are effective protection systems in the confined or unconfined spaces to avoid the damage to building structures since the high temperature when fires occur. NFPA 15 and 502 have suggested respectively that the factories or vehicle tunnels install water spray systems to protect the machinery and structures. This study discussed the cooling effect of water spray systems in experimental and numerical analyses. The actual combustion of woods were compared with the numerical simulations. The results showed that although the flame continued, the cooling effects by water spraying process within 120 seconds were obvious. The results also indicated that the simulation results of the fifth version Fire Dynamics Simulator (FDS) overestimated the space temperature before water spraying in the case of the same water spray system.

Two-step protease digestion and glycopeptide capture approach for accurate glycosite identification and glycoprotein sequence coverage improvement.

A novel two-step protease digestion and glycopeptide capture approach has been developed. It is different from traditional tryptic digestion, glycopeptide enriching and identification approach in glycoproteomics. Here, proteins were first digested by Lys-C into relatively large peptides. Glycopeptides among them were selectively captured by hydrazide resin through oxidized glycans. After thorough washing steps, trypsin was used as a second protease to in situ release non-glycosylated part (named as LT-peptides) from glycopeptides. Subsequently, the remaining part of glycopeptides on resin was de-glycosylated by peptide-N-glycosidase F, and collected as DG-peptides. Finally, both LT- and DG-peptides could be analyzed by mass spectrometer, achieving glycoprotein and glycosite identification. The approach was applied to cell lysate after positive validation by a model glycoprotein: 143 N-glycoproteins identified from DG- and LT-fraction both. In those glycoproteins, 189 DG-peptide-revealed N-glycosites got further confirmation by neighboring LT-peptides, which, in the meantime, made 109 glycoproteins get improved sequence coverage with increase even up to 350% (averagely 79.4%). Through controllable release, separate identification and combined interpretation of non-glycopeptides (newly introduced LT-peptides here) and traditional de-glycopeptides, the approach could not only achieve routine N-glycosite identification, but also provide further proofs of N-glycosites and increase glycoprotein sequence coverage.

[Combination of matrix-assisted laser desorption ionization and electrospray ionization mass spectrometry for the analysis of intact glycopeptides from horseradish peroxidase].

The mass spectrometric analysis of glycan composition and structure is a difficult but essential part in future study following the present glycoprotein identification. Intact glycopeptides analysis is an attracting field, in considering its capability to provide glycosite and corresponding glycan structure information at the same time. Mass spectrometry has been proven to be an important and a key tool for glycan analysis over the past few years. Making use of two soft ionization techniques-matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI), through tandem mass spectrometry (MS/MS) analysis, the information for glycans of the glycopeptides can be obtained in the investigation. Meanwhile, by comparing the MALDI-MS/MS and ESI-MS/MS approaches using model glycoprotein (horseradish peroxidase, HRP), the complementary results have been verified experimentally. We believe that the combination of the two techniques is necessary and will provide useful information for the understanding of protein glycosylation.

One-pipeline approach achieving glycoprotein identification and obtaining intact glycopeptide information by tandem mass spectrometry.

A novel one-pipeline approach is reported, which can demonstrate glycoprotein identification and obtain intact glycosylation information after glycopeptide-level enrichment, without de-glycosylation. The proposed workflow has two enrichment steps plus two proteolytic processes: enriched glycoproteins were digested to peptides by Lys-C, and then enriched again and secondly digested by trypsin. In the resulting mixture, with a reasonable complexity, intact glycopeptides could be preserved and utilized informatively for glycosylation analysis, and non-glycopeptides for protein identification. In both standard protein mixture tests and real sample analysis, the resulting glycopeptides and non-glycopeptides were proved to play their expected roles, thus more confident protein glycosylation information was obtained.

Identification of N-glycosylation sites on secreted proteins of human hepatocellular carcinoma cells with a complementary proteomics approach.

N-linked glycosylation is prevalent in proteins destined for extracellular environments; nearly all secreted proteins are glycosylated. However, with respect to their glycosylation sites, little attention has been paid. Here, we report the analysis of N-glycosylation sites on secreted proteins of human hepatocellular carcinoma cells. For the enrichment of glycopeptides, capture methods with hydrophilic affinity (HA) and hydrazide chemistry (HC) were used complementarily. With the use of both methods in combination with nano-LC-ESI-MS/MS analysis, 300 different glycosylation sites within 194 unique glycoproteins were identified, and 172 glycosites have not been determined experimentally previously. A direct comparison between HA and HC methods was also investigated for the first time. In brief, in terms of selectivity for glycopeptides, HC is superior to HA (92.9% vs 51.3%); however, based on the number of glycosites identified, HA outweighs HC (265 vs 159). Furthermore, unavoidable contaminants such as actin and bovine serum albumin which are not N-glycosylated could be easily depleted by using this glycoproteomic strategy. As a consequence, more low-abundance and genuinely secreted proteins were identified. Among the glycoproteins identified, alpha-fetoprotein, CD44 and laminin have been reported to be implicated in HCC and its metastasis.