407 research outputs found

    On periodic β-expansions of Pisot numbers and Rauzy fractals

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    Azulene-Based Donor-Acceptor Systems: Synthesis, Optical, and Electrochemical Properties

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    First published: 07 Aug 2017We describe the synthesis and properties of azulene-substituted 1,1,4,4-tetracyanobutadienes (AzTCBDs) and heteroazulenyl TCBDs. TCBD derivatives were prepared in good to excellent yields through reaction of the corresponding 1-ethynylazulenes with tetracyanoethylene (TCNE). In contrast, the reaction between propargyl alcohols and the 1-azulenyl group in TCNE generated 2-aminofuran derivatives, which were transformed into 6-aminofulvenes with a 1-azulenyl substituent upon treatment with several amines. The optical and electrochemical properties of the AzTCBDs were clarified by UV/Vis and voltammetry. The AzTCBD derivatives exhibited electrochromism, showing a multi-step color change under electrochemical redox conditions. The multistage redox properties of AzTCBDs could be useful for the development of novel organic electronic materials.ArticleCHEMISTRY-A EUROPEAN JOURNAL. 95(1):16696-16709 (2017)journal articl

    First synthesis of 1-(indo1-2-yl)azulenes by the Vilsmeier-Haack type arylation with triflic anhydride as an activating reagent

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    Azulene derivatives reacted with 2-indolinones in the presence of triflic anhydride (Tf2O) to afford 1-(indo1-2-yl)azulenes in good yields. In the cases of the reaction of 6-tert-butyl-1-(methylthio)azulene (11) and 1-(1,4-dihydropyridin-4-yl)azulene 14, 1,1'-biazulene derivative 24 and 1-(indo1-2-yl)azulene (2) were obtained under the similar reaction conditions, respectively, instead of the presumed electrophilic substitution products.ArticleTETRAHEDRON LETTERS. 53(12):1493-1496 (2012)journal articl

    Stem Cell Therapy in Heart Disease: Limitations and Future Possibilities

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    Heart diseases are one of the major causes of morbidity and mortality worldwide. Despite major advances in drug and interventional therapies, surgical procedures, and organ transplantation, further research into new therapeutic options is still necessary. Stem cell therapy has emerged as one option for the treatment of a variety of heart diseases. Although a large number of clinical trials have shown stem cell therapy to be a promising therapeutic approach, the results obtained from these clinical studies are inconsistent, and stem cell-based improvements of heart performance and cardiac remodeling were found to be quite limited. Since the precise mechanisms underlying the therapeutic actions of stem cells are still under debate, researchers have developed a variety of strategies to improve and boost the potency of stem cells in repair. In this review, we summarize both the current therapeutic strategies using stem cells and future directions for enhancing stem cell potency
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