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[[abstract]]In this thesis, we investigated that quasi-one-dimensional nanomaterials of single-walled carbon nanotubes (SWCNTs) and boron-nitride nanotubes(BNNTs) been used to enhance the photovoltaic performance and device lifetime in an organic photovoltaic (OPV) cells, respectively. In the first task, we fabricated and characterized OPV devices with hybrid composite anodes containing SWCNT networks sandwiched between ITO and PEDOT:PSS. We found that Voc of our OPV devices was insensitive to SWCNTs’ work function shifting caused by the employed chemical treatments, while Jsc and PCE both increased in the order of : reference devices < devices with pristine SWCNT networks < devices with H2SO4/HNO3-treated SWCNT networks < cells with N2H4-treated SWCNT networks. Compared to reference devices, Jsc and PCE of devices with N2H4-treat...
There is broad interest in surface functionalization of 2D materials and its related applications. In this work, we present a novel graphene layer transistor fabricated by introducing fluorinated graphene (fluorographene), one of the thinnest 2D insulator, as the gate dielectric material. For the first time, the dielectric properties of fluorographene, including its dielectric constant, frequency dispersion, breakdown electric field and thermal stability, were comprehensively investigated. We found that fluorographene with extremely thin thickness (5 nm) can sustain high resistance at temperature up to 400°C. The measured breakdown electric field is higher than 10 MV cm−1, which is the heightest value for dielectric materials in this thickness. Moreover, a proof-of-concept methodology, one-step fluorination of 10-layered graphene, is r...
Comment: This manuscript was summited to the journal Carbon at Dec. 1, 2009. The revised manuscript was submitted to the journal Carbon at Mar. 24, 2010. This manuscript has been accepted by the journal Carbon at May 2, 2010.
[[abstract]]Boron nitride nanotubes (BNNTs) were selectively synthesized on patterned bilayer (Fe/Al) catalysts by the plasma-assisted chemical vapor deposition (PACVD) method. The as-grown nanotubes comprise both coaxial and cup-stacking tubular structures. Optical transitions on cup-stacking BNNTs are investigated for the first time. The observed red-shift of free excitonic luminescence was attributed to the excitonic recombination in terms of defect trapping in the tube's surface. The O2 additives during the synthetic process were found to balance the excess H radicals that in turn enhance the growth yield of BNNTs. Moreover, our elemental mapping results provide direct evidence of the metal catalytic mechanism and the influence of the as-formed Al 2O3 underlayer.
Stress-inducible protein-1 (STI-1) is the proposed ligand for the cellular prion protein (PrPC), which is thought to facilitate recovery following stroke. Whether STI-1 expression is affected by stroke and how its signalling facilitates recovery remain elusive. Brain slices from patients that died of ischemic stroke were collected for STI-1 immunohistochemistry. These findings were compared to results from cell cultures, mice with or without the PrPC knockout, and rats. Based on these findings, molecular and pharmacological interventions were administered to investigate the underlying mechanisms and to test the possibility for therapy in experimental stroke models. STI-1 was upregulated in the ischemic brains from humans and rodents. The increase in STI-1 expression in vivo was not cell-type specific, as it was found in neurons, glia a...
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