Showing papers by "Wei Jiang published in 2014"

Integrated Molecular, Interfacial, and Device Engineering towards High‐Performance Non‐Fullerene Based Organic Solar Cells

Abstract: High-performance non-fullerene OSCs with PCEs of up to ca. 6.0% are demonstrated based on PBDTT-F-TT polymer and a molecular di-PBI acceptor through comprehensive molecular, interfacial, and device engineering. Impressive PCEs can also be retained in devices with relatively thick BHJ layer and processed through non-halogenated solvents, indicating these high-performance non-fullerene OSCs are promising for large-area printing applications.

The construction of complex multicomponent supramolecular systems via the combination of orthogonal self-assembly and the self-sorting approach

Abstract: The realization of controllable and well-organized self-assembly within multicomponent supramolecular systems (MSSs) is still a great challenge. Herein, we present the construction of multicomponent supramolecular systems with high-level complexity through the combination of orthogonal self-assembly and the self-sorting approach. Driven by the orthogonality of metal–ligand coordination and host–guest interactions in the orthogonal self-assembly as well as directed by multiple molecular codes in the self-sorting process, five types of simple components (up to eighteen precursors) were successfully self-assembled into two novel tris[2]pseudorotaxanes in one pot through a highly selective manner, which were well-characterized by one-dimensional (1-D) and two-dimensional (2-D) multinuclear NMR as well as ESI-TOF-MS.

Parallel Carbon Nanotube Stripes in Polymer Thin Film with Remarkable Conductive Anisotropy

Abstract: In our previous study (Mao et al. J. Phys. Chem. Lett. 2013, 4, 43−47), we proposed a novel method, that is, the shear-flow-induced hierarchical self-assembly of two-dimensional fillers (octadecylamine-functionalized graphene) into the well-ordered parallel stripes in a polymer matrix, to fabricate the anisotropic conductive materials. In this study, we extend this method to one-dimensional multiwalled carbon nanotubes (MWCNTs). Under the induction of shear flow, the dispersed poly(styrene ethylene/butadiene-styrene) (SEBS) phase and MWCNTs can spontaneously assemble into well-ordered parallel stripes in the polypropylene (PP) thin film. The electrical measurements indicate that the electrical resistivity in the direction parallel to the stripes is almost 6 orders of magnitude lower than that in the perpendicular direction, which is by far the most striking conductive anisotropy for the plastic anisotropic conductive materials. In addition, it is found that the size of the MWCNT stripe as well as the elec...

Enhanced high‐mobility group box 1 (HMGB1) modulates regulatory T cells (Treg)/T helper 17 (Th17) balance via toll‐like receptor (TLR)‐4‐interleukin (IL)‐6 pathway in patients with chronic hepatitis B

Abstract: High-mobility group box 1 (HMGB1) proteins are substantially up-regulated in acute and chronic hepatitis. However, the immunopathogenic role of HMGB1 in patients with chronic hepatitis B (CHB) has not been elucidated. In this study, using a cohort of 36 CHB patients, we demonstrated a crucial role for HMGB1 to modulate balance between regulatory T (Treg) and T helper 17 (Th17) cells via the toll-like receptor (TLR)-4-interleukin (IL)-6 pathway. Serum HMGB1 levels were dramatically higher in CHB patients and increased along with liver injury, inflammation and fibrosis. Notably, HMGB1 increased along with decreased Treg/Th17 cells ratios in the periphery or intrahepatic microenvironment, which provides a clue for HMGB1 to favour Th17 responses whereas inhibit Treg responses. For in vitro studies, serum pools were constructed with serum from CHB patients at an advanced stage, whereas peripheral blood mononuclear cells (PBMC) pools were constructed with cells from those at an early stage. CHB-serum significantly enhanced retinoic acid-related orphan receptor-γt (RORγt), whereas they inhibited forkhead box P3 (Foxp3) expression in CHB-PBMC, which could be reversed by blocking of HMGB1, TLR4, or IL-6. Besides, recombinant HMGB1 (rHMGB1) dose-dependently up-regulated RORγt whereas down-regulated Foxp3 expression in CHB-PBMC, and meanwhile, rHMGB1 enhanced TLR4 and IL-6 expression in CHB-PBMC. Moreover, the axis of HMGB1-TLR4-IL-6-Treg/Th17 required noncontact interactions between CD4 and non-CD4 cells. In addition, rHMGB1 down-regulated anti-inflammatory proteins on CD4(+) CD25(+) cells whereas up-regulated pro-inflammatory cytokines in CD4(+) CD25(-) cells. In summary, enriched HMGB1 in CHB patients shifts Treg/Th17 balance to Th17 dominance via the TLR4-IL-6 pathway, which exacerbates liver injury and inflammation.

Enhanced electrochemical performances of FeOx–graphene nanocomposites as anode materials for alkaline nickel–iron batteries

Abstract: A new type of graphene-based FeOx nanocomposites have been synthesized by high temperature solid-state reaction using FeC2O4·2H2O. The synthesis conditions are optimized by thermogravimetric analysis of the precursor. When evaluated as anode material for the alkaline nickel–iron battery, the FeOx–graphene nanocomposites deliver a high specific capacity of 552.1 mA h g−1 at a current density of 200 mA g−1 and retain 91% of the initial capacity after 100 cycles. Furthermore, the hybridized FeOx–graphene materials undergo only 26% capacity decay when the discharge current density is changed from 200 mA g−1 to 1000 mA g−1. The enhanced cycling and high discharge rate performance derives from the high specific surface area of iron oxide nanoparticles and particular electric conductivity of graphene. This study suggests a safe, inexpensive and powerful rechargeable iron electrode, enabling the promising prospect of large-scale energy storage based on the aqueous iron-based rechargeable battery.

In Vivo Electroporation of Minicircle DNA as a Novel Method of Vaccine Delivery to Enhance HIV-1-Specific Immune Responses

Abstract: DNA vaccines offer advantage over conventional vaccines, as they are safer to use, easier to produce, and able to induce humoral as well cellular immune responses. Unfortunately, no DNA vaccines have been licensed for human use for the difficulties in developing an efficient and safe in vivo gene delivery system. In vivo electroporation (EP)-based DNA delivery has attracted great attention for its potency to enhance cellular uptake of DNA vaccines and function as an adjuvant. Minicircle DNA (a new form of DNA containing only a gene expression cassette and lacking a backbone of bacterial plasmid DNA) is a powerful candidate of gene delivery in terms of improving the levels and the duration of transgene expression in vivo. In this study, as a novel vaccine delivery system, we combined in vivo EP and the minicircle DNA carrying a codon-optimized HIV-1 gag gene (minicircle-gag) to evaluate the immunogenicity of this system. We found that minicircle-gag conferred persistent and high levels of gag expression in vitro and in vivo. The use of EP delivery further increased minicircle-based gene expression. Moreover, when delivered by EP, minicircle-gag vaccination elicited a 2- to 3-fold increase in cellular immune response and a 1.5- to 3-fold augmentation of humoral immune responses compared with those elicited by a pVAX1-gag positive control. Increased immunogenicity of EP-assisted minicircle-gag may benefit from increasing local antigen expression, upregulating inflammatory genes, and recruiting immune cells. Collectively, in vivo EP of minicircle DNA functions as a novel vaccine platform that can enhance efficacy and immunogenicity of DNA vaccines.

Regioselective functionalization of core-persubstituted perylene diimides.

Abstract: Regioselective functionalization of core per-substituted perylene diimides has been achieved efficiently based on a new versatile building block, named tetrabromotetrachloro-perylene-3,4:9,10-tetracarboxylic acid dianhydride (Br4Cl4-PTCDA), which affords a series of novel chromophores with impressive optoelectronic properties. Direct palladium-catalyzed fourfold intramolecular ring fusion affords successfully unique propeller-shaped biscarbazole[2,3-b]carbazole diimides with six annulated rings.

Reactive compatibilization of high‐impact poly(lactic acid)/ethylene copolymer blends catalyzed by N,N‐dimethylstearylamine

Abstract: The inherent brittleness of poly(lactic acid) (PLA) limits its wide application in many fields. Here, high-impact PLA/ethylene-methyl acrylate-glycidyl methacrylate random terpolymer (EMA-GMA) blends were prepared with the addition of a small amount of N,N-dimethylstearylamine (DMSA) catalyst. It was found that the notched impact resistance of various PLA/EMA-GMA blends could be considerably improved by adding DMSA. In particular, the notched Izod impact strength of the blend with 20 wt% EMA-GMA increased from 35.6 to 83.5 kJ m(-2) by adding 0.2 wt% DMSA. Reactive compatibilization between PLA and EMA-GMA with DMSA was studied using Fourier transform infrared spectroscopy. The results indicated that DMSA promoted the reaction between the epoxide group of EMA-GMA and end groups (-OH, -COOH) of PLA. This considerably improved the interfacial adhesion, leading to better wetting of the dispersed phase by the PLA matrix and finer dispersed EMA-GMA particles. Therefore, the significant increase in notched impact strength was attributed to the effective reactive compatibilization promoted by DMSA. (C) 2013 Society of Chemical Industry

Study of fibrinogen adsorption on poly(ethylene glycol)-modified surfaces using a quartz crystal microbalance with dissipation and a dual polarization interferometry

Abstract: Protein adsorption behavior is a key factor that determines whether materials can be used as medical polymer materials. In this study, fibrinogen (Fib) adsorptions on three different poly(ethylene glycol) (PEG) surfaces that differed in chain length and chain density were investigated using a quartz crystal microbalance with dissipation (QCM-D) and a dual polarization interferometry (DPI) with respect to adsorbed masses, viscoelastic properties and chain conformations. On QCM-D chips, PEG chains were tight and in extended brush conformations. Meanwhile, on DPI chips, PEG1000 and PEG2000 may have the same pancake-like conformations, but PEG5000 had a mushroom conformation. Moreover, several bare spaces were observed on the loose pancake-like PEG1000- and PEG2000-modified DPI surfaces. Fib could fully spread on the relatively dense PEG1000-modified DPI surface and partly spread and tightly orient on the relatively sparse PEG2000-modified DPI surface. Thus, grafting density was found to have greater significance in determining Fib adsorption resistance due to its influence on Fib spreading when the chain conformations of hydrophilic molecules were loose pancake-like structures. Furthermore, brush and mushroom structured PEG5000 chains both had high deformation capacity, which excellently resisted protein adsorption by adjusting their conformation to decrease interaction with Fib. Therefore, the Fib adsorption resistance of PEG-modified surface depended on the grafting density of PEG layer and the deformation capacity of the PEG chain.

Top K Query for QoS-Aware Automatic Service Composition

Abstract: With the proliferation of Web services, service engineers demand automatic service composition algorithms that not only synthesize the correct service compositions from thousands of services but also satisfy the quality requirements of users. This is known as QoS-aware automatic service composition problem. Our observation is that current research of only finding the optimal service composition result has several shortcomings. Users have to utilize the optimal one, which will make it rigid, and consequently bring about problems, such as overload of “hot services” and lack of choices for users. To cope with these problems, a top k query mechanism is introduced in this paper, and a progressive and incremental Key-Path-Based Loose (KPL) algorithm with 100 percent accuracy is proposed. Our QSynth, which won the performance championship of Web Service Challenge 2009 and 2010, is extended to support top k query based on KPL algorithm. Evaluations show that, compared to the state of the art, KPL algorithm achieves superior scalability and accuracy with respect to a large variety of composition scenarios. Moreover, we generalize a new graph problem: top k DAGs (Directed Acyclic Graphs) problem based on the above work. Applications of this new graph problem contain API recommender, supply chain, and so on. KPL algorithm illustrated in this paper can address them efficiently, too.

The expression of platelet-activating factor receptor modulates the cisplatin sensitivity of ovarian cancer cells: a novel target for combination therapy

Abstract: The expression of platelet-activating factor receptor modulates the cisplatin sensitivity of ovarian cancer cells: a novel target for combination therapy

Confinement of Polymer-Tethered Gold Nanowires in Polymeric Colloids

Abstract: Driven by the interfacial tension, polymer-tethered ultrathin gold nanowires (AuNWs) are successfully confined in polymeric nanocolloids, such as spheres, vesicles, and cylinders. The confined morphology of the AuNWs significantly depends on the size and the shape of the confined space. A series of structured hybrid colloids containing elastically or inelastically distorted AuNWs are obtained. Uncoiling the elastically deformed AuNWs can be realized through solvent swelling of the polymer shell. Thus, the hybrid colloids can be applied for mechanical energy storage and release. The elastic potential and the resilience of a confined AuNW can be estimated to be 3.2 x 10(-17) J and 1.6 x 10(-9) N, respectively. Moreover, the hydrophobicity of the tethered molecular shell on the AuNWs has been studied to reveal the influence of the interfacial tension to the coiling of the AuNWs, which offers an important guideline for manipulating nanomaterials in emulsion droplets.

Asymmetric vesicle constructed by AB/CB diblock copolymer mixture and its behavior: a Monte Carlo study.

Abstract: Asymmetric vesicles constructed from AB/CB diblock copolymer mixture in a selective solvent for A and C blocks are studied using Monte Carlo simulation. The effects of the mixed ratio of the two diblock copolymers, the solution pH, and the hydrophilic chain length on the distributions of hydrophilic blocks on the surfaces of asymmetric vesicles are studied systematically. The simulation results show that asymmetric vesicle, in which the inner and outer surfaces are constructed from different hydrophilic blocks, can be obtained from AB/CB diblock copolymer mixture. The formation of ABC or CBA three-layer asymmetric vesicle depends on the composition of the mixture, the chain length of hydrophilic block, and the solution pH. The hydrophilic block with the same charge (induced by the solution pH), or longer chain length, or lower content in the mixture is more likely to distribute on the outer surface of the vesicle. Moreover, the transition from ABC to CBA three-layer asymmetric vesicle in which blocks C are charged can occur by adjusting the composition of the mixture. On the other hand, the investigations of the interfacial energy density of asymmetric vesicles elucidate the distribution regularity of hydrophilic blocks. When the hydrophilic chain lengths are equal, the difference between the outer and inner interfacial energies is the main factor that determines the asymmetric vesicle structures; that is, the distributions of different hydrophilic blocks on asymmetric vesicles always tend to gain the largest difference between the outer and inner interfacial energies. However, when the hydrophilic chain lengths are different, the chain conformational entropy becomes the main driving force for determining the distribution of hydrophilic blocks on asymmetric vesicles.

Ultralong cylindrical micelles precisely located with semiconductor nanorods by solvent evaporation-driven self-assembly

Abstract: We demonstrate the efficient incorporation of PS-tethered cadmium sulfide nanorods (PS-CdS NRs) into polystyrene-block-poly(ethylene oxide) (PS-b-PEO) ultralong cylindrical micelles by solvent evaporation-driven self-assembly. The hexadecyl trimethyl ammonium bromide (CTAB) was used as the surfactant in chloroform-in-water emulsions. It is a prerequisite to improve the enthalpic compatibility between the CdS NRs and the PS block of PS-b-PEO to accomplish their cooperative assembly. We investigated the effects including the concentration of CTAB in the aqueous solution ([CTAB]), the weight fraction of CdS NRs (f), the volume ratio of the organic solvent to water and the magnetic stirring rate on the cooperative assembly behaviors. The different morphologies of hybrid assemblies formed at varied [CTAB] were rationalized in view of the adsorption of the aqueous surfactant and block copolymer at the oil–water interfaces, thereby leading to the disparate mechanisms by which the organic–water interfacial instabilities proceeded. This work presents an extremely precise location of the CdS NRs in the centers of the cylindrical micelles, i.e. 95.2% of the CdS NRs were distributed in the central ca. 4 vol% regions of the cylinders and all of them were dispersed in the central ca. 38% radial spans. The length of the hybrid cylindrical micelles can reach tens of micrometers. The ultralong cylindrical micelles functionalized by the CdS NRs in the central cores can lower the toxicity of the CdS NRs and improve the biocompatibility, which have potential applications in fluorescence probes, labels and many others.

Luminous block copolymer–quantum dots hybrids formed by cooperative assembly in a selective solvent

Abstract: The formation of well-defined polymer/inorganic nanoparticle (NP) hybrid micelles is of considerable interest to the development of nanomaterials with desired optical, electric, magnetic, and mechanical properties. Herein, we introduce the efficient encapsulation of monodisperse polystyrene (PS)-grafted semiconductor quantum dots (QDs) into the PS cores of PS-b-PEO micelles through a “solution phase self-assembly” approach. We demonstrated that the size and the QD loading number of the coassemblies can be thermodynamically or kinetically tuned by varying the concentration of QDs and/or block copolymer (BCP) in the initial solution. Moreover, diverse morphologies of QD/BCP hybrid assemblies can be obtained by tuning the experimental parameters, such as the size of QDs, stirring time and many others. Interestingly, a novel Janus complex comprising a vesicular part without QDs and a spherical part with lots of QDs was firstly reported in our work. The Janus complexes were unstable and tended to transform their morphologies to the predominantly spherical QD-loaded micelles. The QD/BCP hybrid assemblies can present good water solubility, stability, lower toxicity and high luminous performance, indicating their potential applications in the biological field, especially for use as fluorescence probes and labels.

Morphology Control and Stabilization in Immiscible Polypropylene and Polyamide 6 Blends with Organoclay

Abstract: In the current study, 70/30 (w/w) polypropylene (PP)/polyamide 6 (PA6)/organoclay ternary blends were prepared by melt mixing in three different blending sequences, i.e., organoclay premixed with PA6 and then mixed with PP (S1 blending sequence), organoclay premixed with PP and then mixed with PA6 (S2 blending sequence), and organoclay, PA6 and PP mixed simultaneously (S3 blending sequence). The effects of organoclay on the phase morphologies, rheological properties and mechanical properties of the blends are examined to reveal the role of organoclay in these immiscible blends. First of all, the dispersion and distribution of organoclay is investigated using XRD and TEM techniques. The organoclay is exfoliated and distributed in the dispersed PA6 phase as well as at the interface between PA6 and PP. Interestingly, more organoclay sheets are observed at the interface when the S2 or S3 blending sequences are utilized. From the SEM images, it is clear that the domain size of the PA6 phase decreases remarkably after introducing organoclay into the PP/PA6 blends. Two different rheological protocols are applied to probe the effect of organoclay on the morphology of the blend by in-situ monitoring the morphological evolution. The rheological results reveal that the phase morphology of the PP/PA6 blends remains relatively stable during shear for a wide range of shear rates when 1.0 wt% organoclay has been added. For the blends with a relatively high clay loading (5.0 wt%), a characteristic and pronounced "plateau" is observed in the low frequency range of the G'-omega curves, which indicates the presence of a percolating network of clay nanosheets. From the mechanical measurements, we find that the tensile strength of the blends increases slightly first and then declines dramatically with increasing organoclay content. Moreover, the elongation at break drops sharply as the organoclay content increases. In summary, it is clear that the organoclay can effectively reduce the domain size of the dispersed PA6 phase and stabilize the phase morphology in shear flow. However, the mechanical properties of the blends are not really improved by clay addition, even though a co-continuous morphology with a percolated clay network was generated.

APISynth: a new graph-based API recommender system

Abstract: Current API recommendation tools yield either good recall ratio or good precision, but not both. A tool named APISynth is proposed in this paper by utilizing a new graph based approach. Preliminary evaluation demonstrates that APISynth wins over the state of the art with respect to both the two criteria.

Toughening poly(3-hydroxybutyrate) with propylene carbonate plasticized poly(propylene carbonate)

Abstract: Poly(3-hydroxybutyrate) (phb)/poly(propylene carbonate) (ppc) blends containing various amounts of plasticizer propylene carbonate (pc) were prepared, and the toughness of the blends as a function of temperature was studied. it was found that the brittle-ductile transition temperature (t-bd) of phb toughened by ppc decreased from 60 degrees c to 10 degrees c with the increase in pc content. as pc is the plasticizer of ppc, the mechanical properties, such as young's modulus of plasticized ppc with different pc contents, were also studied. sequentially, the relationship between t bd and the ratio of the young's modulus (e-1) of the phb matrix to that of the plasticized ppc elastomer (e-2) was investigated. it was found that the young's modulus of plasticized ppc should be considerably lower than that of the phb matrix in order to obtain 'the tough phb/plasticized ppc blends at a lower temperature. in contrast, the morphology of the dispersed particles also had an important influence on the toughness. when the plasticizer content was more than 20 wt.%, the ppc particles became more spherical and smaller. the toughness could be considerably improved accordingly.

Chlorinated polypropylene (propylene carbonate) and preparation method thereof

Abstract: The invention provides chlorinated polypropylene (propylene carbonate) and a preparation method thereof. The chlorinated polypropylene (propylene carbonate) is as shown in a formula (I). Compared with existing polypropylene (propylene carbonate), due to the existence of chlorine atoms, the chlorinated polypropylene (propylene carbonate) has relatively strong electronegativity, the interaction between the chlorinated polypropylene (propylene carbonate) and other polar materials can be enhanced, and the chlorinated polypropylene (propylene carbonate) can be further widely applied as a compatibilizer, a binding agent, a coating, printing ink and the like; after the chlorine atoms are introduced, the interaction of hydrogen bonds can be produced in the chlorinated polypropylene (propylene carbonate), the processing performance and the mechanical properties can be further improved, and the chlorine atoms can be used for improving the flame retardance of the chlorinated polypropylene (propylene carbonate) material. The formula I is as shown in the specification.

Monte Carlo simulation of temperature-induced reversible morphological changes between sphere and vesicle formed by AB diblock copolymers

Abstract: Temperature-induced reversible morphological changes of micelles formed by AB diblock copolymers in a selective solvent for A blocks was studied through Monte Carlo simulation. When only hydrophobic B blocks are temperature-sensitive, the micelle morphology changes from sphere at high temperature to vesicle with a decrease in temperature. When the system was heated back to high temperature, the vesicles transform into spheres, indicating reversible morphological changes with temperature. However, the simulation results show that the pathways of morphological changes between sphere and vesicle depend on temperature change rate. The pathway of the sphere changing into vesicle under a quenching process is different from the pathway of the vesicle changing into sphere when the system was directly heated to the higher temperature. Moreover, the time consumed in the simulation for vesicle transformation into sphere upon heating is significantly shorter than that for the reverse process upon quenching. By contrast, when changing the temperature gradually, the pathways of morphological transitions from sphere to vesicle and from vesicle to sphere are almost identical. Moreover, the time consumed in the simulation for the annealing and gradual heating processes are nearly the same. This pathway differences observed when directly and gradually changing the temperature of the system are further elucidated by investigating the contact number variation between B blocks and solvents with simulation time. On the other hand, when the hydrophilic blocks and hydrophobic blocks are both temperature-sensitive, the introduction of the temperature-sensitivity of hydrophilic blocks hinders the morphological transition from sphere to vesicle under annealing conditions, and only larger spheres can be obtained after the annealing process when the degree of temperature-sensitivity of blocks A is rather high. Meanwhile, the simulation results show that the morphological transitions are still reversible under a slow temperature change rate when the hydrophilic blocks and hydrophobic blocks are both temperature-sensitive.

Online rheological investigation on ion-induced micelle transition for amphiphilic polystyrene-block-poly(acrylic acid) diblock copolymer in dilute solution.

Abstract: The ion-induced micellar transition is online-investigated by the time dependence of the viscosity of the solution under shear flow for the first time. During the morphological transition, the change in the micellar structure can be tracked by the change in viscosity. Adding HCl or CaCl2 into pre-prepared spherical micelle solution from the self-assembly of polystyrene-block-poly(acrylic acid) (PS144-b-PAA(22)) in the N,N-dimethylformamide (DMF)/water mixture, the micellar structures change into short cylinders, long, entangled cylinders, and then lamellae or vesicles, corresponding to the viscosity increasing first and then declining. When HCl or CaCl2 is added to the pre-prepared spherical micelle solution formed by PS144-b-PAA(50) in the dioxane/water mixture, the micellar structures are quickly transformed into cylinders or lamellae before carrying out the rheological measurement and then are turned to vesicles or spheres under the shearing, corresponding to a gradual decline in viscosity. This study shows that the rheology can be a very simple and effective online method on the investigation of the micellization, which plays an important role in understanding the micellization mechanism and micellar transition pathway of block copolymers in dilute solution.