Browsing by Author "Chu, D"

Now showing 1 - 4 of 4
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    Ferromagnetic ordering in Mn-doped ZnO nanoparticles
    (Springer, 2014-01-01) Luo, X; Lee, WT; Xing, GZ; Bao, N; Yonis, A; Chu, D; Lee, J; Ding, J; Li, S; Yi, JB
    Zn1 - xMn x O nanoparticles have been synthesized by hydrothermal technique. The doping concentration of Mn can reach up to 9 at% without precipitation or secondary phase, confirmed by electron spin resonance (ESR) and synchrotron X-ray diffraction (XRD). Room-temperature ferromagnetism is observed in the as-prepared nanoparticles. However, the room-temperature ferromagnetism disappears after post-annealing in either argon or air atmosphere, indicating the importance of post-treatment for nanostructured magnetic semiconductors.© 2014 Luo et al.; licensee Springer.
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    Reversible hydrophobic to hydrophilic transition in graphene via water splitting induced by UV irradiation
    (Macmillan Publisher, 2014-09-01) Xu, ZM; Ao, ZM; Chu, D; Younis, A; Li, CM; Li, S
    Although the reversible wettability transition between hydrophobic and hydrophilic graphene under ultraviolet (UV) irradiation has been observed, the mechanism for this phenomenon remains unclear. In this work, experimental and theoretical investigations demonstrate that the H2O molecules are split into hydrogen and hydroxyl radicals, which are then captured by the graphene surface through chemical binding in an ambient environment under UV irradiation. The dissociative adsorption of H2O molecules induces the wettability transition in graphene from hydrophobic to hydrophilic. Our discovery may hold promise for the potential application of graphene in water splitting. © 2014 Macmillan Publishers Limited
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    Segregation-induced low-dimensional surface structures in oxide semiconductors
    (Springer-Verlag Berlin Heidelberg, 2014-03-01) Atanacio, AJ; Bak, T; Chu, D; Ionescu, M; Nowotny, J
    The present work considers quasi-isolated low-dimensional surface structures, which are formed as a result of segregation of intrinsic and extrinsic defects in oxide semiconductors. It has been documented that the local properties of these structures, such as crystalline structure, electronic structure, chemical composition, as well as charge and mass transport kinetics, are entirely different from those of the bulk phase. There is an increasingly urgent need to better understand their local properties, which have a strong impact on the reactivity of solids in general and photocatalytic properties in particular. The accumulation of data on the properties of surface structures opens a new discipline of the science of materials interfaces. The present work is focused on the surface structures, which are formed at TiO2-based semiconductors. It is shown that these structures play crucial role in the conversion of solar energy into chemical energy. © 2014, Springer-Verlag Berlin Heidelberg.
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    Size‐dependent penetration of nanoparticles in tumor spheroids: a multidimensional and quantitative study of transcellular and paracellular pathways
    (Wiley, 2023-10-11) Chen, W; Wang, WQ; Xie, Z; Centurion, F; Sun, B; Paterson, DJ; Tsao, SCH; Chu, D; Shen, Y; Mao, G; Gu, Z
    Tumor penetration of nanoparticles is crucial in nanomedicine, but the mechanisms of tumor penetration are poorly understood. This work presents a multidimensional, quantitative approach to investigate the tissue penetration behavior of nanoparticles, with focuses on the particle size effect on penetration pathways, in an MDA‐MB‐231 tumor spheroid model using a combination of spectrometry, microscopy, and synchrotron beamline techniques. Quasi‐spherical gold nanoparticles of different sizes are synthesized and incubated with 2D and 3D MDA‐MB‐231 cells and spheroids with or without an energy‐dependent cell uptake inhibitor. The distribution and penetration pathways of nanoparticles in spheroids are visualized and quantified by inductively coupled plasma mass spectrometry, two‐photon microscopy, and synchrotron X‐ray fluorescence microscopy. The results reveal that 15 nm nanoparticles penetrate spheroids mainly through an energy‐independent transcellular pathway, while 60 nm nanoparticles penetrate primarily through an energy‐dependent transcellular pathway. Meanwhile, 22 nm nanoparticles penetrate through both transcellular and paracellular pathways and they demonstrate the greatest penetration ability in comparison to other two sizes. The multidimensional analytical methodology developed through this work offers a generalizable approach to quantitatively study the tissue penetration of nanoparticles, and the results provide important insights into the designs of nanoparticles with high accumulation at a target site. ©2023 The Authors. Small published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.