Chemistry - Book Chapters

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Now showing 1 - 5 of 9
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    Mesoporous materials as templates for semiconductor nanowires assembly
    (IOS Press, 2003) Holmes, Justin D.; Morris, Michael A.; Ryan, Kevin M.; European Commission; Intel Corporation; Intel Ireland Ltd.
    In this chapter is described a novel approach for synthesizing mesoporous silicas with tunable pore diameters, wall thickness and pore spacings that can be used as templates for the assembly of semiconductor nanowire arrays. Silicon and germanium nanowires, with size monodisperse diameters, can readily be formed within the mesoporous silica matrix using a supercritical fluid inclusion technique. These nano-composite materials display unique optical properties such as intense room temperature ultraviolet and visible photoluminescence. The implication of these mesoporous nanowire materials for future electronic and opto-electronic devices is discussed.
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    Probing of nanocontacts inside a transmission electron microscope
    (Springer-Verlag Berlin Heidelberg, 2007) Erts, Donats; Lohmus, Ants; Holmes, Justin D.; Olin, Hakan
    In the past twenty years, powerful tools such as atomic force microscopy have made it possible to accurately investigate the phenomena of friction and wear, down to the nanometer scale. Readers of this book will become familiar with the concepts and techniques of nanotribology, explained by an international team of scientists and engineers, actively involved and with long experience in this field. Edited by two pioneers in the field, 'Fundamentals of Frictions and Wear at the Nanoscale' is suitable both as first introduction to this fascinating subject, and also as a reference for researchers wishing to improve their knowledge of nanotribology and to keep up with the latest results in this field.
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    Bioconjugated gold nanoparticles enhance siRNA delivery in prostate cancer cells
    (Springer, 2019-05-17) Rahme, Kamil; Guo, Jianfeng; Holmes, Justin D.; Dinesh Kumar, Lekha; Science Foundation Ireland; Irish Research Council; Department of Science and Technology of Jilin Province; National Council for Scientific Research
    Here we describe a simple way to create a gold nanoparticle (AuNP)-based non-viral delivery system to deliver siRNA into prostate cancer cells. Therefore, positively charged polyethylenimine (PEI)-capped AuNPs were synthesized in water and further conjugated with the targeting ligand (folic acid) for folate receptors (AuNPs-PEI-FA). The AuNPs-PEI-FA could effectively complex small interfering RNA (siRNA) through electrostatic interaction. Flow cytometry displayed that AuNPs-PEI-FA could specifically deliver siRNA into LNCaP cells, a prostate cancer cell line overexpressing prostate-specific membrane antigen (PSMA) that exhibits a hydrolase enzymatic activity with a folate substrate. In contrast, internalization of siRNA into PC-3 cells, a prostate cancer cell line not expressing PSMA or folate receptors, was not achieved using AuNPs-PEI-FA.siRNA. Following endolysosomal escape, the AuNPs-PEI-FA-.siRNA formulation resulted in significant endogenous gene silencing when compared to the nontargeted formulation, suggesting the potential of AuNPs-PEI-FA for targeted delivery of therapeutic siRNAs in the treatment of prostate cancer.
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    Novel approaches for genuine single phase room temperature magnetoelectric multiferroics
    (Wiley, 2016-05) Keeney, Lynette; Schmidt, Michael; Amann, Andreas; Maity, Tuhin; Deepak, Nitin; Faraz, Ahmad; Petkov, Nikolay; Roy, Saibal; Pemble, Martyn E.; Whatmore, Roger W.; Alguero, Miguel; Gregg, J. Marty; Mitoseriu, Liliana; Science Foundation Ireland
    This chapter reviews approaches currently under investigation for the fabrication of single‐phase magnetoelectric multiferroics, from bulk ceramics to those in thin‐film form. It presents an approach of inserting magnetic ions into the Aurivillius phase, layer‐structured ferroelectric materials, whereby thin films of average composition Bi6Ti2.8Fe1.52Mn0.68O18 (B6TFMO) demonstrate room temperature ferroelectricity, ferromagnetism, and magnetoelectric coupling. The chapter also discusses the importance of careful microstructural analysis of the materials and the application of a statistical model to determine a confidence level that the observed effects are from genuine single‐phase magnetoelectric multiferroics. It reviews how careful phase analysis and statistical treatment of the data confirmed that the B6TFMO phase is a single‐phase multiferroic to a confidence level of 99.5%. Finally, it summarizes how direct evidence of magnetoelectric coupling in the B6TFMO thin films was obtained. This review demonstrates that with materials development and design, the development of room temperature multiferroic materials can be achieved.
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    Organometallic-metallic-cyclotriphosphazene mixtures: solid state method for metallic nanoparticle growth
    (Nova Science Publishers, 2013-04) Díaz, Carlos; Valenzuela, María Luisa; O'Dwyer, Colm; Roger Dong; Fondo Nacional de Desarrollo Científico, Tecnológico y de Innovación Tecnológica
    We review a recent general solid state method to obtain metallic, metal oxide and phosphate nanoparticles and crystals by pyrolysis at 800°C using organometallic derivatives of cyclo and polyphosphazene precursors containing diverse organometallic fragments linked to polymeric or oligomeric phosphazenes. When the preparation of the molecular precursor is not possible or results in low yield, an alternative method using solid state mixtures of the type MLn/N3P3[O2C12H8]n, where MLn can be a single metallic salt, and a coordination compound or an organometallic, is possible. For AuCl(PPh3)/[NP(O2C12H8)]n mixtures, single crystal cubic Au nanoparticles form, whose morphology, crystal shape, size and distribution strongly depends on deposition quantity and the mixture molar ratio. Nanoparticles as small as 3.5 nm are observed if the mixture is prepared in a crucible and varied geometries of microcrystals found when the mixture was deposited on Si or SiO2 wafers, including single-crystal gold fullerene structures. Extension to Ag, Pd and Re-containing precursor mixtures such as Ag(PPh3)(CF3SO3)/ [NP(O2C12H8)]3, PdCl2/N3P3[O2C12H8]3, and KReO4/N3P3[O2C12H8]3 allows microcrystal formation during pyrolysis. A thermally induced phase demixing mechanism describes the evolution of the crystal growth, aided microphase separation of the polymer mixture. This microphase demixing is shown to be an overarching mechanism involved in the nano to micro scale growth of crystals. A probable mechanism of the atomic and molecular-level chemistry is also proposed based on decomposition of the macromolecular polymeric, trimer and oligomeric precursors for the initial stages.