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ABSTRACT: The design, synthesis, and characterization of new organic semiconductors (OSCs) are important aspects for the development of next-generation optoelectronic devices. Structurally, organic semiconductors based on π-conjugated molecules can be easily modified via rational synthesis to tune multi-level self-assembled structures and discover novel chemical, optical, and electronic properties. Heteroarenes, which contain chalcogens and nitrogens in fused aromatic rings, are being developed as promising semiconducting materials for applications in a variety of electronic devices due to their outstanding optoelectronic properties. We highlight recent approaches toward realizing high performance p-channel field effect transistors based on linear heteroacenes and heteroatom annulated polycyclic aromatics (PAHs) as key functional components. These comprehensive, but carefully orchestrated approaches simultaneously address (i) practical synthesis, (ii) tunable self-assembled packing arrangement as well as (iii) high electronic performance.
Chemical Society Reviews 04/2013; · 28.76 Impact Factor
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ABSTRACT: The copper-mediated Ullmann coupling of 1,7-dibromoperylene bisimides afforded structurally perfect singly-linked perylene bisimide (PBI) arrays, whilst the homo-coupling of 1,12-dibromoperylene bisimides gave doubly-linked and triply-linked diperylene bisimides. The interactions of three bay-linked diperylene bisimides that differed in their linkage (singly, doubly, and triply) were investigated in their neutral and reduced forms (mono-anion to tetra-anion). UV/Vis absorption and fluorescence spectroscopy revealed different degrees of interaction, which was explained by exciton coupling and conjugation effects. The electrochemical properties and spectroelectrochemistry also showed quite-different degrees of PBI interactions in the reduced mixed-valence species, which was apparent by the observation of CT bands. The interpretation of the experimental findings was supported by spin-restricted and -unrestricted DFT and time-dependent TD-DFT calculations with the long-range-corrected CAM-B3LYP functional. Accordingly, the degree of interaction in both the neutral and reduced forms of the bay-linked PBIs was qualitatively in the order doubly linked<singly linked < triply linked, owing to the different degrees of twisting and flexibility between the two PBIs moieties. Only triply linked diPBI showed completely delocalized wavefunctions over the entire π-system.
Chemistry 05/2012; 18(22):6764-75. · 5.93 Impact Factor
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ABSTRACT: Restorative proctocolectomy with IPAA is the surgical treatment of choice in patients with ulcerative colitis who require colectomy. Pouchitis is the most common long-term complication in patients with IPAA. While immune-mediated disorders frequently coexist with IBD, they appear to be associated with an increased risk for chronic antibiotic-refractory pouchitis.
This study aimed to evaluate histologic features of autoimmune-associated chronic antibiotic-refractory pouchitis in comparison with controls and to assess their possible diagnostic utility.
Clinical definition for autoimmune-associated chronic pouchitis included 1) chronic antibiotic-refractory pouchitis with response only to corticosteroids, immunomodulators, or biologics; 2) positive serum autoantibodies, including antinuclear antibody, rheumatoid factor, and antimicrosomal antibody; and 3) concurrent immune-mediated disorders. Various histologic features of pouch biopsy specimens were evaluated.
The investigation was conducted at a tertiary referral center.
From our Pouchitis Registry, all eligible patients with autoimmune-associated pouchitis (n = 17) were included. The control groups included 16 patients with nonautoimmune-associated chronic antibiotic-refractory pouchitis, 39 with antibiotic-responsive pouchitis, and 19 patients with normal pouches. Various histologic features of pouch biopsy specimens were evaluated.
In comparison with the control groups, the autoimmune-associated pouchitis group showed a significant increase in deep crypt apoptosis (p < 0.001). It also showed more pyloric gland metaplasia in comparison with antibiotic-responsive pouchitis and normal pouches. With the use of apoptosis score which we developed as a diagnostic marker for autoimmune-associated chronic antibiotic-refractory pouchitis, we constructed a receiver operating curve and obtained an area-under-curve value of 0.89 (95% CI: 0.79, 0.99).
Increased deep crypt apoptosis is a distinctive histologic feature of autoimmune-associated chronic antibiotic-refractory pouchitis, and this feature may aid in the diagnosis and differential diagnosis in pouchitis.
Diseases of the Colon & Rectum 05/2012; 55(5):549-57. · 3.13 Impact Factor
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Aifeng Lv,
Yan Li,
Wan Yue,
Lang Jiang,
Huanli Dong,
Guangyao Zhao,
Qing Meng, Wei Jiang,
Yudong He,
Zhibo Li,
Zhaohui Wang,
Wenping Hu
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ABSTRACT: High-performance n-type organic single crystal transistors of a naphthalene diimide are demonstrated. The accomplished transistors exhibit electron mobility as high as 0.7 cm(2) V(-1) s(-1). The anisotropic charge transport in the elongated hexagonal crystals of the naphthalene diimide is also explored. The transport anisotropy along different directions is at least 1.6 (mobility ratio).
Chemical Communications 04/2012; 48(42):5154-6. · 6.17 Impact Factor
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ABSTRACT: The paper presents a new multiplexing scheme, called convolutional multiplexing (CM), to achieve high diversity gain and high
spectrum efficiency for OFDM-based systems. In this scheme, data symbols are spread onto several subcarriers by the convolutional
spreader. Spectrum efficiency can be improved by two approaches: high order modulation and multi-code multiplexing. With the
best spreading codes searched out, the multi-code multiplexing OFDM-CM system performs better in AWGN channel, but may lose
diversity gain in frequency selective fading channels. On the other hand, the single-code spreading OFDM-CM system with high
order modulation can achieve the maximum diversity order. Simulation results show that the multi-code convolutional multiplexing
perform better than code-division multiplexing (CDM) for OFDM-based systems.
Wireless Personal Communications 04/2012; 49(4):545-560. · 0.46 Impact Factor
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ABSTRACT: A new photorefractive (PR) material sensitized with a novel functional unit DiPBI is prepared based on the guest/host approach. This unique mixture exhibits strong absorption in the whole range of visible light. Moreover, the photorefractive performance as well as PR speed is improved by far compared to the widely used sensitizer PCBM.
Advanced Materials 03/2012; 24(16):2104-8. · 13.88 Impact Factor
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Wan Yue,
Aifeng Lv,
Jing Gao, Wei Jiang,
Linxiao Hao,
Cheng Li,
Yan Li,
Lauren E Polander,
Stephen Barlow,
Wenping Hu,
Simone Di Motta,
Fabrizia Negri,
Seth R Marder,
Zhaohui Wang
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ABSTRACT: Hybrid rylene arrays have been prepared via a combination of Stille coupling and C-H transformation. The ability to extend the π system along the equatorial axis of rylenes not only leads to broadened light absorption but also increases the electron affinity, which can facilitate electron injection and transport with ambient stability.
Journal of the American Chemical Society 03/2012; 134(13):5770-3. · 9.91 Impact Factor
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ABSTRACT: Magnetotactic bacteria synthesize magnetic particles called magnetosomes that cause them to orient to their external magnetic fields. However, the physiological significance and other possible functions of these magnetosomes have not been explored in detail. In this study, we have investigated the biological functions of magnetosomes with respect to their ability to scavenge reactive oxygen species (ROS) in Magnetospirillum gryphiswaldense MSR-1. To assess the changes in ROS levels under different conditions, cells were cultured under aerobic or micro-aerobic conditions in medium containing high and low amounts of iron. To ensure that the observed results were not due to nonspecific interactions, reactions were carried out using a mutant deficient in synthesizing magnetite (mamO-deficient mutant), its complementary strain or the wild-type MSR-1. We observed that the levels of intercellular ROS under micro-aerobic conditions with high-iron medium were much higher when the non-synthetic Fe(3) O(4) crystals mutant Mu21-415 was employed for the assay, compared with the wild-type or complementary strain, or when conditions were aerobic with low-iron medium. These results indicated that magnetosomes function in the scavenging of intracellular ROS. Furthermore, we have demonstrated that the magnetosomes exhibit peroxidase-like properties, by using the earlier reported in vitro horseradish peroxidase assay for artificial magnetic nanoparticles. In addition to possessing peroxidase-like activity, the magnetosomes also exhibited a more enzymatic kinetic response, suggesting that proteins on the membranes of the magnetosomes likely contribute to the enzymatic activity. This is the first study to demonstrate that magnetosomes play an important role in decreasing or eliminating ROS.
Environmental Microbiology 02/2012; 14(7):1722-9. · 5.84 Impact Factor
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ABSTRACT: A novel dipolar-modulated charge-doped trilayer n-n organic heterojunction with a bidirectional tunable energy band discontinuity is constructed. The rectifying mechanism of the trilayer is similar to the rectifying and inverse-rectifying characteristics from n-p and p-n junctions, respectively. Zero-bias optoelectronic behavior and persistent photoconductivity are discovered. These results show that what are viewed as technological hurdles in the development of an organic n-n heterojunction should, in fact, lead to a better approach in organic optoelectronics.
Small 02/2012; 8(4):546-51. · 8.35 Impact Factor
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ABSTRACT: A novel cost-efficient and facile technique, molecular crystal lithography, to fabricate nanogap electrodes efficiently is reported. The gap width of the electrodes can be tuned from ∼9 nm to several micrometers. Organic field-effect transistors based on the nanogap electrodes all exhibit a high performance, indicating the effectiveness and practicability of molecular crystal lithography for mass production of nanogap electrodes.
Advanced Materials 02/2012; 24(5):694-8. · 13.88 Impact Factor
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ABSTRACT: The insulin loaded nanoparticles composed of poly (lactic-co-glycolic acid) (PLGA) and hydroxypropyl methylcellulose phthalate (HP55) were prepared via the emulsions solvent diffusion method with two different solvents, namely, DMSO and acetone/water. The microstructures of the nanoparticles were studied by the solubility parameters theory, DSC, FTIR, and the nitrogen adsorption technique. Phase-separated PLGA domains were observed from the nanoparticles prepared with both types of solvents. Mesopores were observed from the nanoparticles prepared with DMSO as the solvent and almost did not exist with acetone/water. An in vitro drug release study showed that the pH-sensitivity of nanoparticles was not only attributed to the pH-dependent dissolubility of HP55 but also to the internal microstructure. The formation of mesopores accelerated the release of insulin, leading to no obvious pH-sensitivity of the nanoparticles prepared with DMSO. However, for the nanoparticles prepared with acetone/water, the release of insulin was pH-dependent. The results demonstrated that solvents played an important role in affecting the microstructures of nanoparticles, which influenced markedly the insulin release behavior.
Colloids and surfaces. B, Biointerfaces 02/2012; 94:206-12. · 2.60 Impact Factor
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ABSTRACT: Tetracene tetracarboxylic diimides have been synthesized based on direct double ring extension of electron-deficient naphthalene diimides involving metallacyclopentadienes. Atomic structure and electronic transitions responsible for their NIR absorption spectra are investigated with quantum-chemical calculations. In light of their unique structure and admirable photophysical and electronic properties, this new molecular skeleton is promising candidate for n-type semiconductors.
Journal of the American Chemical Society 11/2011; 133(45):18054-7. · 9.91 Impact Factor
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ABSTRACT: Part-of-speech (POS) tagging and shallow parsing are sequence modeling problems. While HMM and other generative models are
not the most appropriate for the task of labeling sequential data. Compared with HMM, Maximum Entropy Markov models (MEMM)
and other discriminative finite-state models can easily fused more features, however they suffer from the label bias problem.
This paper presents a method of Chinese POS tagging and shallow parsing based on conditional random fields (CRF), as new discriminative
sequential models, which may incorporate many rich features and well avoid the label bias problem. Moreover, we propose the
information feedback from syntactical analysis to lexical analysis, since natural language should be a multi-knowledge interaction
in nature. Experiments show that CRF approach achieves 0.70% F-score improvement in POS tagging and 0.67% improvement in shallow
parsing. And we also confirm the effectiveness of information feedback to some complicated multi-class words.
03/2011: pages 677-689;
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ABSTRACT: Solution-processed, high-performance 1D single-crystalline nanoribbon transistors fabricated from dithioperylene are described. The integration of two sulfur atoms into the perylene skeleton induces a compressed highly ordered packing mode directed by S···S interactions. The mobilities of up to 2.13 cm(2) V(-1) s(-1) for a dithioperylene individual nanoribbon make it particularly attractive for electronic applications.
Journal of the American Chemical Society 01/2011; 133(1):1-3. · 9.91 Impact Factor
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ABSTRACT: A facile strategy towards conformationally stable chiral ladder-type oligo-perylene bisimides is established via copper-mediated Ullmann coupling. Absolute configurations are determined with the help of quantum-chemical calculations.
Chemical Communications 09/2010; 46(33):6078-80. · 6.17 Impact Factor
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ABSTRACT: A homogeneous series of well-defined oligo-butadiynylene-NDIs containing up to five naphthalene diimides (NDIs) moieties have been efficiently synthesized in one pot by oxidative homocoupling of 1,6-di((trimethylsilyl)ethynyl)naphthalene diimides in good yields.
Organic Letters 08/2010; 12(15):3460-3. · 5.86 Impact Factor
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ABSTRACT: Direct functionalization of electron-deficient and electron-rich polycyclic aromatics via copper-mediated radical perfluoroalkylation was achieved in high yields.
Organic Letters 05/2010; 12(10):2374-7. · 5.86 Impact Factor
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ABSTRACT: Two regiospecifically pyridyl annelated perylene bisimides have been prepared in one pot by the combination of the Suzuki cross-coupling reaction and subsequent light-promoted cyclization in high yields.
Organic Letters 12/2009; 12(2):228-31. · 5.86 Impact Factor
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ABSTRACT: A facile palladium-catalyzed procedure for meta-selective alkylation of perylene bisimides with alkyl halides has been achieved by direct C-H functionalization.
Organic Letters 11/2009; 11(23):5430-3. · 5.86 Impact Factor
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Applied Physics Letters. 01/2009; 94(15).
