Beyond Small Molecular Cations: Elucidating the Alkaline Stability of Cationic Moieties at the Membrane Scale.

A major hindrance in the commercialization of alkaline polyelectrolyte-based electrochemical energy conversion devices is the development of durable anion exchange membranes (AEMs). Despite many alkali-stable cations that have been explored, the stability of these cationic moieties at the membrane scale is in the blind. Herein, we present a molecularly designed polyaromatic AEM with cationic moieties in an alternating manner to unbiasedly compare the alkaline stability of piperidinium and ammonium groups at the membrane state. Using nuclear magnetic resonance spectroscopy, we demonstrate that the pentyltrimethyl group is about 2-fold more stable than piperidinium within a polyaromatic scaffold, either in ex-situ alkaline soaking or in-situ cell operation. This finding challenges the judgment extrapolated from the stability trend of cations, that is, the piperidinium-functionalized AEM is more alkali-stable than the counterparts based on quaternary ammoniums. Moreover, the deterioration mechanism of piperidinium moiety after being embedded in polyaromatic backbone is rationalized by density functional theory.

Formation of Size-Controllable Tetragonal Nanoprisms by Crystallization-Directed Ionic Self-Assembly of Anionic Porphyrin and PEO-Containing Triblock Cationic Copolymer.

The creation of anisotropic nanostructures with precise size control is desirable for new properties and functions, but it is challenging for ionic self-assembly (ISA) because of the non-directional electrostatic interactions. Herein, the formation of size-controllable tetragonal nanoprisms is reported via crystallization-directed ionic self-assembly (CDISA) through evaporating a micellar solution on solid substrates. First, ISA is designed with a crystalline polyethylene oxide (PEO) containing cationic polymer poly(2-(2-guanidinoethoxy)ethyl methacrylate)-b-poly(ethyleneoxide)-b-poly(2-(2-guanidinoethoxy)-ethylmethacrylate) (PGn -PEO230 -PGn ) and an anionic 5,10,15,20-Tetrakis(4-sulfonatophenyl) porphyrin (TPPS) to form micelles in aqueous solution. The PG segments binds excessive TPPS with amplenet chargeto form hydrophilic corona, while the PEO segments are unprecedentedly dehydrated and tightly packed into cores. Upon naturally drying the micellar solution on a silicon wafer, PEO crystallizationdirects the micelles to aggregate into square nanoplates, which are further connected to nanoprisms. Length and width of the nanoprisms can be facilely tuned by varying the initial concentration. In this hierarchical process, the aqueous self-assembly is prerequisite and the water evaporation rate is crucial for the formation of nanostructures, which provides multiple factors for morphology regulating. Such precise size-control strategy is highly expected to provide a new vision for the design of advanced materials with size controllable anisotropic nanostructures.

Synergy between dynamic covalent boronic ester and boron-nitrogen coordination: strategy for self-healing polyurethane elastomers at room temperature with unprecedented mechanical properties.

Achieving mechanical robustness and highly efficient self-healing simultaneously at room temperature is always a formidable challenge for polymeric materials. Herein, a series of novel supramolecular polyurethane elastomers (SPUEs) are developed by incorporating dynamic covalent boronic ester and boron-nitrogen (B-N) coordination. The SPUEs demonstrate the highest tensile toughness (∼182.2 MJ m-3) to date for room-temperature self-healable polymers, as well as an excellent ultimate tensile strength (∼10.5 MPa) and ultra-high fracture energy (∼72 100 J m-2), respectively, owing to a synergetic quadruple dynamic mechanism. It is revealed that the B-N coordination not only facilitates the formation and dissociation of boronic ester at room temperature but also dramatically enhances the mechanical properties by the intermolecular coordinated chain crosslinking and intramolecular coordinated chain folding. Meanwhile, the B-N coordination and urethane hydrogen interaction also serve as sacrificial bonds, which rupture during stretching to dissipate energy and recover after release, leading to superior notch insensitiveness and recoverability. The SPUEs restore their mechanical robustness after self-healing at room temperature and the self-healing efficiency can be dramatically accelerated by surface wetting.

High-sulfur coal-derived nitrogen, sulfur dual-doped carbon as an economical metal-free electrocatalyst for oxygen reduction reaction.

The search for an economical electrocatalyst for oxygen reduction reaction (ORR) is a worldwide issue for fuel cells and metal-air batteries. Herein, we used cheap and available high-sulfur inferior coal as the single precursor to synthesize an N, S dual-doped carbon (NSC) metal-free electrocatalyst for the ORR. The N, S dual-doped carbon (NSC), prepared at 800 °C (NSC800), possessed a large specific surface area of 942 m2 g-1, with an amorphous carbon structure and more defects than the others. Furthermore, it contains 1.06 at% N and 2.24 at% S, where N is resolved into pyridinic-N, pyrrolic-N, and graphitic-N. For the electrochemical behavior, NSC800 displayed a good ORR electrocatalytic activity, with the ORR peak potential at -0.245 V (vs. SCE) and half-wave potential (E 1/2) at -0.28 V (vs. SCE) in an alkaline solution. This study not only gives an original and facile method to prepare an economical ORR electrocatalyst but also provides a novel clean-use of high-sulfur inferior coal.

Frontal Ring-Opening Metathesis Copolymerization: Deviation of Front Velocity from Mixing Rules.

Frontal ring-opening metathesis polymerization (FROMP) of dicyclopentadiene (DCPD) shows promise for rapid, energy-efficient manufacturing of high-performance polymers and composites. Copolymerization in FROMP allows for systematic modification of materials properties while retaining the benefits of the DCPD system such as low cost of the monomer and excellent mechanical properties of the resulting polymer. While the copolymerization reactivity and copolymer properties generally exhibit monotonic dependence on monomer composition as predicted by simple, empirical mixing rules, we discovered that the frontal copolymerization behavior of DCPD with a dinorbornenyl (di-NBE) cross-linker deviates significantly from that expected relationship. As the comonomer content increases, the FROMP reaction shows a nonmonotonic increase in front velocity with intermediate compositions 40% faster than either pure component. We then studied the behavior of a series of comonomers, analyzed several factors (such as thermodynamic and kinetic properties) that might influence front velocity, and found that the nonmonotonic trend mainly results from the cross-linked structure. This copolymerization system provides a promising strategy to tune materials properties (such as glass transition temperature) and simultaneously improve the efficiency in FROMP-based materials manufacturing.

Focal adhesion kinase (FAK) is associated with poor prognosis in urinary bladder carcinoma.

OBJECTIVE: Overexpression of the enhancer of focal adhesion kinase (FAK) protein, an intracellular tyrosine kinase protein, has been reported to be associated with biological malignancy of gastric cancer and several other tumors. The purpose of this study was to examine the expression of FAK and analyze its correlation with the clinicopathological features of human urinary bladder carcinoma. METHODS: 315 archived cases of urinary bladder carcinoma were reviewed and TMAs were developed as per established procedures. Immunohistochemical staining for FAK was performed to assess the correlation between the expression profiles and the clinicopathological parameters and clinical outcome. RESULTS: Protein level of FAK was up-regulated in urinary bladder carcinoma compared with adjacent non-tumor tissues. Overexpression of FAK was significantly associated with high histologic grade, angiolymphatic invasion, lymph node metastasis, myometrial invasion and cervical involvement (P < 0.05). Further multivariate analysis suggested that expression of FAK was independent prognostic indicator for urinary bladder carcinoma. These alterations in expression were also associated with greater risk of disease progression and decreased chance of carcinoma-specific survival. Kaplan-Meier analysis demonstrates that overexpression of FAK was significantly associated with decreased overall survival. CONCLUSION: Overexpression of FAK corelates with well established pathologic risk factors and may predict more aggressive biologic behavior in urinary bladder carcinoma. The expression patterns of FAK correlated well with the pathologic stage, disease progression, and carcinoma-specific survival. This finding may aid in identifying more biologically aggressive carcinomas and thus patients who could benefit from more intensive adjuvant therapy.

A mechanically strong and tough anion exchange membrane engineered with non-covalent modalities.

A mechanically robust and tough anion exchange membrane was constructed using the strategy of supramolecular modalities. After introducing a secondary amide as a hydrogen-bonding crosslinking motif into the side chain of the PPO backbone, the membrane exhibits high mechanical strength and excellent flexibility (101% elongation at break), as well as suppressed water uptake, enhanced thermal stability and good fuel cell performances.

A recyclable polyoxometalate-based supramolecular chemosensor for efficient detection of carbon dioxide.

A new type of supramolecular chemosensor based on the polyoxometalate (POM) Na9DyW10O36 (DyW10) and the block copolymer poly(ethylene oxide-b-N,N-dimethylaminoethyl methacrylate) (PEO114-b-PDMAEMA16) is reported. By taking advantage of the CO2 sensitivity of PDMAEMA blocks to protonate the neutral tertiary amino groups, CO2 can induce the electrostatic coassembly of anionic DyW10 with protonated PDMAEMA blocks, and consequently trigger the luminescence chromism of DyW10 due to the change in the microenvironment of Dy3+. The hybrid complex in dilute aqueous solution is very sensitive to CO2 content and shows rapid responsiveness in luminescence. The luminescence intensity of the DyW10/PEO-b-PDMAEMA complex increases linearly with an increasing amount of dissolved CO2, which permits the qualitative and quantitative detection of CO2. The complex solution also shows good selectivity for CO2, with good interference tolerance of CO, N2, HCl, H2O and SO2. The supramolecular chemosensor can be recycled through disassembly of the hybrid complex by simply purging with inert gases to remove CO2.

pH-responsive inorganic-organic hybrid supramolecular hydrogels with jellyfish-like switchable chromic luminescence.

A unique type of novel supramolecular hybrid hydrogel based on the co-assembly of the anionic polyoxometalate and the cationic ABA triblock copolymer via electrostatic interaction was reported to show jellyfish-like switchable chromic luminescence. The hydrogel undergoes reversible sol-gel transition in response to pH changes, and simultaneously exhibits an unprecedented luminescent chromism from weak green to strong white.

Tunable, luminescent, and self-healing hybrid hydrogels of polyoxometalates and triblock copolymers based on electrostatic assembly.

Hybrid hydrogels based on electrostatic co-assembly of polyoxometalates and ABA triblock copolymers were readily prepared and exhibit excellent luminescence and self-healing performance.

Tunable assembly of amphiphilic rod-coil block copolymers in solution.

This review covers the recent progress in the research field of rod-coil block copolymers (BCPs) containing rigid rod-like blocks and flexible coil-like blocks. Their assembly behaviors are fundamentally different from coil-coil BCPs in morphology because of the geometric disparity between the rod and coil segments and anisotropic interactions between rod blocks to form liquid crystalline or crystalline structures. Rod-coil BCPs can self-assemble into diverse nanostructures in selective solvents, such as micelles, cylinders, vesicles, tubules, belts, and rings. This review highlights valuable contributions in the past six years on the self-assembly behavior of rod-coil BCPs controlled by the volume fraction and the composition of the blocks from both the experimental and theoretical perspectives, and their tunable self-assembled nanostructures triggered by external stimuli, such as solvent, pH, temperature, light, and chemical additives. We also briefly introduce emerging applications of rod-coil nanoparticles in the biological field.

The REGγ proteasome regulates hepatic lipid metabolism through inhibition of autophagy.

The ubiquitin-proteasome and autophagy-lysosome systems are major proteolytic pathways, whereas function of the Ub-independent proteasome pathway is yet to be clarified. Here, we investigated roles of the Ub-independent REGγ-proteasome proteolytic system in regulating metabolism. We demonstrate that mice deficient for the proteasome activator REGγ exhibit dramatic autophagy induction and are protected against high-fat diet (HFD)-induced liver steatosis through autophagy. Molecularly, prevention of steatosis in the absence of REGγ entails elevated SirT1, a deacetylase regulating autophagy and metabolism. REGγ physically binds to SirT1, promotes its Ub-independent degradation, and inhibits its activity to deacetylate autophagy-related proteins, thereby inhibiting autophagy under normal conditions. Moreover, REGγ and SirT1 dissociate from each other through a phosphorylation-dependent mechanism under energy-deprived conditions, unleashing SirT1 to stimulate autophagy. These observations provide a function of the REGγ proteasome in autophagy and hepatosteatosis, underscoring mechanistically a crosstalk between the proteasome and autophagy degradation system in the regulation of lipid homeostasis.