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The crystallization process in small droplet possessed wide engineering applications in micromaterial fabrication and fine crystal screening. Herein, hydrophilic sessile platform via 3D printing technology was developed to facilely construct the interfacial confined droplets (ICDs) with a designed contact angle by conveniently regulating the droplet volume. The micro‐flows inside the droplet were adjusted by controlling the intensity of Marangoni flow and capillary flow within different droplet shapes (i.e., contact angle), which were verified by experimental and simulative results. Especially for the 120° ICD, the micro‐flows, achieved by the coordination of Marangoni flow and capillary flow, could convey solutes toward droplet center and harvest a standard cubic crystal at sessile platform center. These results indicated that ICD and sessile platform possessed great potential on high‐quality crystal screening and crystallization technique development, which additionally enriched the research strategy on crystal engineering. [ABSTRACT FROM AUTHOR]

Targeted and high throughput manufacture of crystalline biominerals with diverse morphologies is of importance, due to the significant impact of shape and texture on the material properties, while tunable morphosynthesis of crystalline is restrained by the proper ion transfer process during the reactive crystallization, and is commonly regulated using organic soluble additives. Herein, Janus membranes (JMs) are facilely produced for the continuous confined reactive crystallization of calcium carbonate. Fabricated JM simultaneously achieves rapid and uniform directional CO32− ions transfer in the aqueous solution through the straight, uniform nanoscale hydrophilic channels, and the interfacial reactive crystallization is generated with confined ion adsorption and gating effect at the hydrophobic side. Hollow CaCO3 microcomposites via JM system are continuously and directly synthesized in the aqueous system without any assisted organic solvent or polymer additive, which is green and highly efficient. In addition, the reversed ion transfer direction in JM can be ideally managed resulting in highly selective manufacturing of cube or sphere‐type microcomposites. This study provides a feasible route for the rapid production of advanced particle materials with tunable morphology, displaying great potential applications of JM in material engineering. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have permanent, nanometer‐scale pores endowed with high porosity and thermal and chemical stability, which is widely used as composite membranes and applied in the field of separation. Conventional methods for preparing composite membranes, such as spray coating, spin coating, and pressure‐assisted or vacuum‐assisted filtration, have problems such as the selective layer can easily fall off. Here, an integrated casting–precipitation–evaporation method is proposed to prepare flexible COF composite membranes (DPBI/HTpBD). The DPBI/HTpBD composite membranes constructed with hollow spherical shell COF selective layer (HTpBD) and porous supporting layer are designed and applied in a vanadium flow battery. The excellent coulombic efficiency (CE, 99.5%) and voltage efficiency (VE, 81.1%) of batteries (180 mA cm−2) are achieved by the nanometre‐scale pores of the hollow spherical shell COF selective layer. In addition, the rigid pore structure inside COF bonded by covalent bonds endows the DPBI/HTpBD composite membranes with outstandingly high temperature stability. Compared to that of the Nafion 212 and DPBI pristine membranes (CE reduces by 5.2%, 3.3%), the CE of DPBI/HTpBD‐9 composite membrane‐based cell only reduces by 0.9% as the temperature increases from 25 to 55 °C. This work provides a new preparation method for high ion‐selective and high temperature stable battery membranes. [ABSTRACT FROM AUTHOR]

A two‐level trade‐credit mode, in which both supplier and retailer provide trade credit to their buyers, is prevalent in several types of markets. This paper investigates the optimal trade credits provided by the supplier and retailer, and the optimal order quantity, assuming credit‐dependent demand in a newsvendor model. The strategic interaction between the supplier and retailer is modeled as a Stackelberg game with the supplier as the leader. We provide conditions under which the optimal decisions on trade credits and order quantity can be uniquely determined, which enable us to examine the relationship between the optimal trade credits and describe conditions providing them. We also compare the credit contract and price contract in profit, consumer surplus, social welfare, double marginalization, and supply chain coordination, and our analysis shows that the trade‐credit contract amounts to an alternative for the price contract. Finally, we use several numerical examples to illustrate the theoretical results and provide managerial insights. [ABSTRACT FROM AUTHOR]

Background: The mechanisms of vagal nerve stimulation (VNS) for the treatment of drug‐resistant epilepsy (DRE) remain unclear. This study aimed to measure spontaneous brain activity changes caused by VNS in DRE patients using resting‐state functional MRI (rs‐fMRI). Methods: The rs‐fMRI scans were performed in 16 DRE patients who underwent VNS surgery. Amplitude of low‐frequency fluctuations (ALFF) and regional homogeneity (ReHo) was generated and examined using paired sample t‐test to compare activity changes at different current intensity stage. The preoperative and postoperative ALFF/ReHo were also compared in eight responders (≥50% reduction of seizure frequency three months after surgery) and eight nonresponders using paired sample t‐test. Results: The significant ALFF and ReHo changes were shown in various cortical/subcortical structures in patients under different current intensity. After three months of stimulation, responders exhibited increased ALFF in the right middle cingulate gyrus, left parahippocampal gyrus, and left cerebellum, and increased ReHo in the right postcentral gyrus, left precuneus, left postcentral gyrus, right superior parietal gyrus, right precentral gyrus, and right superior frontal gyrus. Nonresponders exhibited decreased ALFF in the left temporal lobe and right cerebellum, increased ALFF in bilateral brainstem, decreased ReHo in bilateral lingual gyri, and increased ReHo in the right middle frontal gyrus and right anterior cingulate gyrus. Conclusions: The spontaneous neural activity changes in DRE patients caused by VNS were in an ongoing process. Increased ALFF/ReHo in frontal cortex, cingulate gyri, precentral/postcentral gyri, parahippocampal gyri, precuneus, parietal cortex, and cerebellum may implicate in VNS‐induced improvement in seizure frequency. [ABSTRACT FROM AUTHOR]

Droplet evaporative crystallization on microscale heterogeneous surface is a vivid topic in chemical engineering, bioengineering, nanomaterials, and so on. Here, 3D printed interfacial matrix platform with regular pillar convexity and tunnel structure is fabricated to reveal the mechanism of the interfacial micro droplet crystallization. Element‐based rotation volume model is established to simulate the concentration and nucleation barrier distribution during the microscale process. Sodium urate monohydrate and NaCl crystallization on the pillar convex structure both confirm that confined capillary flow in the micro droplet and initial nucleation condition dominate the nucleation, growth control and particle distribution. Droplet crystallization stretches over the tunnel structure reveal an interesting phenomenon that two regions possessing distinct‐different nucleation barriers can isolated obtain the crystal particles from nanoscale to even millimeter scale. The fabricated platform and the capillary circulation transfer theory unfold a potential approach to harvest high value‐added crystals with specific morphology and desire sizes distribution. [ABSTRACT FROM AUTHOR]

Heavy metal ions (HMIs) in wastewater can be removed by polyethyleneimine (PEI) adsorption, however, it is difficult to recycle PEI macromolecules from their mixture with suspended particles in wastewater. A novel HMIs adsorption technique with renewable PEI-grafted porous membranes was developed. PEI molecules were dispersed with high specific area and structured morphology, which allowed HMIs and suspended particles to be retained separately at different locations of the membrane, with the former adsorbed in matrix and the latter rejected on surface. The membranes with the optimized PEI loading ratio of 30 k wt % behaved excellently with microsphere rejection and Co(II) adsorption reaching 98.5% and 51.0 mg/g, respectively. They successfully decreased Co(II) concentration from 3.0 mg/L to the allowable discharge standard (0.5 mg/L), even with an enhanced flux of 6200 L/m2/h at 0.12 MPa under the cyclic tests. Overall, PEI-grafted membrane adsorption is highly efficient for removing HMIs and suspended particles simultaneously from wastewater. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4541-4548, 2017 [ABSTRACT FROM AUTHOR]

This article studies the optimal capacity investment problem for a risk-averse decision maker. The capacity can be either purchased or salvaged, whereas both involve a fixed cost and a proportional cost/revenue. We incorporate risk preference and use a consumption model to capture the decision maker's risk sensitivity in a multiperiod capacity investment model. We show that, in each period, capacity and consumption decisions can be separately determined. In addition, we characterize the structure of the optimal capacity strategy. When the parameters are stationary, we present certain conditions under which the optimal capacity strategy could be easily characterized by a static two-sided ( s, S) policy, whereby, the capacity is determined only at the beginning of period one, and held constant during the entire planning horizon. It is purchased up to B when the initial capacity is below b, salvaged down to Σ when it is above σ, and remains constant otherwise. Numerical tests are presented to investigate the impact of demand volatility on the optimal capacity strategy. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 218-235, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT A mixed methanesulfonic acid/sulfuric acid solvent based chlromethylation of poly(ether ether ketone) (PEEK) is described. Methanesulfonic acid is the solvent, sulfuric acid is the catalyst, and chloromethyl octyl ether (CMOE) is the chloromethylating reagent. 1H-NMR spectra confirmed the successful synthesis of chloromethylated PEEK (CMPEEK). The effects of polymer concentration, catalyst/polymer ratio, and reaction temperature on the rate of PEEK chloromethylation were investigated. In order to minimize crosslinking, the PEEK concentration must be kept very low (< 2%). The reaction rate increases with increased catalyst/polymer ratio and reaction temperature. The activation energy of PEEK chloromethylation is 30.9 kJ mol−1. The extent of reaction for the new route is more easily controllable as compared with the previous sulfuric acid based route. The reaction rate constant at 25°C for the new route is 1.29 h−1 which is lower than that for chloromethylation by concentrated sulfuric acid at −10°C (rate constant 1.88 h−1). As a result, the degree of chloromethylation of CMPEEK can be easily controlled at room temperature using this mixed solvent. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41404. [ABSTRACT FROM AUTHOR]

ABSTRACT Modification of proton conductive channels (PCCs) in Nafion has been achieved with the assistance of 3, 4-dimethylbenzaldehyde (DMBA). During annealing, ionic clusters develop from small isolated spheres (1.72 nm) to wide continuous channels (5.15 nm), and the crystallinity of Nafion/DMBA membranes is also improved from 17% to 32% as shown by X-ray diffraction. Molecular dynamic simulation reveals that hydrogen bonding and hydrophobic interaction between DMBA and Nafion work synergistically to achieve better phase separation. The morphology-property relationship shows that, versus various PCCs width, the corresponding proton conductivities vary greatly from 0.079 to 0.139 S/cm at 80 °C. By carefully tuning the width of PCCs, the proton conductivity shows an improvement of 22-34% as compared with pristine Nafion. A significant enhancement on the maximum power density is achieved for the membrane electrode assembly on Nafion/DMBA-8h (as high as 1018 mW/cm−2), yielding an enhancement of 39% on pristine Nafion-8h (730 mW/cm−2). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 52, 1107-1117 [ABSTRACT FROM AUTHOR]

The sulfonated polybenzimidazole (sPBI)/sulfonated imidized graphene oxide (SIGO) was evaluated to be a potential candidate for high temperature proton exchange membranes fuel cells (HT‐PEMFCs). Multifunctionalized covalently bonded SIGO is incorporated in sPBI matrix to resolve the drawbacks such as low proton conductivity, poor water uptake, and ion‐exchange capacity (IEC) of sPBI polymer, synthesized by direct polycondensation in phosphoric acid for the application of proton exchange membranes. Strong hydrogen bonding among multifunctional groups established a neighborhood of interconnected hydrophobic graphene sheets and organic polymer chains. It provides hydrophobic–hydrophilic phase separation and facile proton hopping architecture. The optimized sPBI/SIGO (15 wt %) revealed 2.45 meq g−1 IEC; 5.81 mS cm−1 proton conductivity [120 °C and 10% relative humidity (RH)] and 2.45% bound water content. The maximum power density of the sPBI/SIGO‐15 membrane was 0.40 W cm−2 at 160 °C (5% RH) and ambient pressure with stoichiometric feed of H2/air. This recommends that sPBI/SIGO composite membranes are compatible candidate for HT‐PEMFCs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47892. [ABSTRACT FROM AUTHOR]

Sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) is a kind of novel non‐fluorine polymer, whose high proton conductivity is dependent on high degree of sulfonation, which resulting in loss of dimensional stability. SPPESK/superacid sulfated zirconia (SZrO2) composite proton exchange membranes are fabricated first. The composite membrane shows good dimensional stability, ascribing to the restriction effect of hydrogen bonding force on the mobility and relaxation of polymer chains. Introducing SZrO2 simultaneously enhances the conductivity and anti‐methanol permeation, owing to the connected ion domains, enlarged and aggregated ion clusters, excess proton conduction sites, and good blocking effect to methanol of SZrO2. For composite membrane containing 1.5 wt % SZrO2, the highest conductivity of 180 mS cm−1 is obtained at 80 °C. Compared with pristine SPPESK and Nafion 115, the methanol permeability is reduced by 54 and 77%, and the maximum power density of direct methanol fuel cell is enhanced by 133 and 25%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46758. [ABSTRACT FROM AUTHOR]