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  1. AU="Franklin Wong"
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  1. Article ; Online: An Optical and Structural Study of Pentacene Thin-film Polymorphs

    Franklin Wong / Rui He / Aaron Pinczuk

    Columbia Undergraduate Science Journal, Vol 01, Iss 01, Pp 50-

    2006  Volume 55

    Abstract: Because of its high conductivity, pentacene is an attractive organic material for electronic applications, but the understanding of its thin-film polymporphism is still lacking. In this work, two pentacene films, 70nm and 2.5μm thick, were evaporated ... ...

    Abstract Because of its high conductivity, pentacene is an attractive organic material for electronic applications, but the understanding of its thin-film polymporphism is still lacking. In this work, two pentacene films, 70nm and 2.5μm thick, were evaporated onto silicon dioxide substrates. X-ray Diffraction identified two different phases in the 70nm film and four in the 2.5μm film. Oxygen and fluorine impurities were detected by X-ray Photoelectron Spectroscopy, suggesting that some of the phases in the films may be impurity-based mixed crystals of pentacene. With improved sensitivity from the resonance Raman effect, low-energy intermolecular phonons were studied and assigned as signature modes to the different polymorphs identified in the films. The 39cm-1 mode is characteristic of the 14.3Å pure pentacene polymorph, and the 45 and 50cm-1 modes are signatures of the 15.3Å pure polymorph. This is the first time that the intermolecular modes of pentacene thin films has been studied, and a more thorough analysis can further elucidate the structures of the different thin-film polymorphs.
    Keywords Applied Physics and Materials Science ; Pentacene ; Science (General) ; Q1-390 ; Science ; Q ; DOAJ:Science (General) ; DOAJ:Science General
    Subject code 530
    Language English
    Publishing date 2006-01-01T00:00:00Z
    Publisher Columbia University Libraries
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Mechanism-Specific Pharmacodynamics of a Novel Complex-I Inhibitor Quantified by Imaging Reversal of Consumptive Hypoxia with [ 18 F]FAZA PET In Vivo

    Seth T. Gammon / Federica Pisaneschi / Madhavi L. Bandi / Melinda G. Smith / Yuting Sun / Yi Rao / Florian Muller / Franklin Wong / John De Groot / Jeffrey Ackroyd / Osama Mawlawi / Michael A. Davies / Y.N. Vashisht Gopal / M. Emilia Di Francesco / Joseph R. Marszalek / Mark Dewhirst / David Piwnica-Worms

    Cells, Vol 8, Iss 12, p

    2019  Volume 1487

    Abstract: Tumors lack a well-regulated vascular supply of O 2 and often fail to balance O 2 supply and demand. Net O 2 tension within many tumors may not only depend on O 2 delivery but also depend strongly on O 2 demand. Thus, tumor O 2 consumption rates may ... ...

    Abstract Tumors lack a well-regulated vascular supply of O 2 and often fail to balance O 2 supply and demand. Net O 2 tension within many tumors may not only depend on O 2 delivery but also depend strongly on O 2 demand. Thus, tumor O 2 consumption rates may influence tumor hypoxia up to true anoxia. Recent reports have shown that many human tumors in vivo depend primarily on oxidative phosphorylation (OxPhos), not glycolysis, for energy generation, providing a driver for consumptive hypoxia and an exploitable vulnerability. In this regard, IACS-010759 is a novel high affinity inhibitor of OxPhos targeting mitochondrial complex-I that has recently completed a Phase-I clinical trial in leukemia. However, in solid tumors, the effective translation of OxPhos inhibitors requires methods to monitor pharmacodynamics in vivo. Herein, 18 F-fluoroazomycin arabinoside ([ 18 F]FAZA), a 2-nitroimidazole-based hypoxia PET imaging agent, was combined with a rigorous test-retest imaging method for non-invasive quantification of the reversal of consumptive hypoxia in vivo as a mechanism-specific pharmacodynamic (PD) biomarker of target engagement for IACS-010759. Neither cell death nor loss of perfusion could account for the IACS-010759-induced decrease in [ 18 F]FAZA retention. Notably, in an OxPhos-reliant melanoma tumor, a titration curve using [ 18 F]FAZA PET retention in vivo yielded an IC 50 for IACS-010759 (1.4 mg/kg) equivalent to analysis ex vivo. Pilot [ 18 F]FAZA PET scans of a patient with grade IV glioblastoma yielded highly reproducible, high‐contrast images of hypoxia in vivo as validated by CA-IX and GLUT-1 IHC ex vivo. Thus, [ 18 F]FAZA PET imaging provided direct evidence for the presence of consumptive hypoxia in vivo, the capacity for targeted reversal of consumptive hypoxia through the inhibition of OxPhos, and a highly-coupled mechanism-specific PD biomarker ready for translation.
    Keywords hypoxia ; [18f]faza ; pet ; iacs-010759 ; mitochondrial complex i ; metabolism ; pharmacodynamics ; oxidative phosphorylation ; collateral lethality ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2019-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

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