Organometallic derivatives of cyclotriphosphazene as precursors of nanostructured metallic materials: a new solid state method

The cyclic phosphazene trimers [N3P3(OC6H5)5OC5H4N·Ti(Cp)2Cl][PF6] (3), [N3P3(OC6H4CH2CN·Ti(Cp)2Cl)6][PF6]6 (4), [N3P3(OC6H4-But)5(OC6H4CH2CN·Ti(Cp)2Cl)][PF6] (5), [N3P3(OC6H5)5C6H4CH2CN·Ru(Cp)(PPh3)2][PF6] (6), [N3P3(OC6H5)5C6H4CH2CN·Fe(Cp)(dppe)][PF6] (7) and N3P3(OC6H5)5OC5H4N·W(CO)5 (8) were prepared and characterized. As a model, the simple compounds [HOC5H5N·Ti(Cp)2Cl]PF6 (1) and [HOC6H4CH2CN·Ti(Cp)2Cl]PF6 (2) were also prepared and characterized. Pyrolysis of the organometallic cyclic trimers in air yields metallic nanostructured materials, which according to transmission and scanning electron microscopy (TEM/SEM), energy-dispersive X-ray microanalysis (EDX), and IR data, can be formulated as either a metal oxide, metal pyrophosphate or a mixture in some cases, depending on the nature and quantity of the metal, characteristics of the organic spacer and the auxiliary substituent attached to the phosphorus cycle. Atomic force microscopy (AFM) data indicate the formation of small island and striate nanostructures. A plausible formation mechanism which involves the formation of a cyclomatrix is proposed, and the pyrolysis of the organometallic cyclic phosphazene polymer as a new and general method for obtaining metallic nanostructured materials is discussed.

An investigation of the role of TRIB2 in steady state and stressed haematopoiesis

TRIB2 is a member of the mammalian Tribbles family of serine/threonine pseudokinases (TRIB1-3). Here, we studied murine haematopoiesis after Trib2 ablation under steady state and proliferative stress conditions, including genotoxic and oncogenic stress. At the steady state, we found that TRIB2 loss did not adversely affect peripheral blood cell counts and populations. No detectable significant differences were found in the populations of haematopoietic stem and progenitor cells. However, Trib2-/- mice had significantly higher thymic cellularity due to the increased proliferation of Trib2-/- developing thymocytes which give rise to increased number of mature thymic subsets. During stressed haematopoiesis, Trib2-/- developing thymocytes demonstrate hypersensitivity to 5-fluorouracil-induced cell death. Nevertheless, Trib2-/- mice exhibit accelerated thymopoietic recovery post 5-fluorouracil treatment due to increased cell division kinetics of developing thymocytes. In an experimental murine T-cell acute lymphoblastic leukaemia (T-ALL) model, Trib2-/- mice had reduced latency in vivo which associated with aggressive T-ALL phenotypes and impaired activation of mitogen-activated protein kinase. Gene set enrichment analysis showed that TRIB2 expression is elevated in immature subtype of human T-ALL enriched with mitogen-activated protein kinase signalling. However, TRIB2 expression is suppressed in mature subtype of human T-ALL. Thus, TRIB2 emerges as a novel regulator of thymocyte cellular proliferation, important for the thymopoietic response to genotoxic and oncogenic stress, and possessing tumour suppressor function. In Drosophila, Tribbles promotes degradation of String which is an orthologue of mammalian CDC25 phosphatases in order to arrest cell cycle during embryonic development. Here, we showed that the role of Tribbles-induced degradation of String is evolutionarily conserved in TRIB2. We found that TRIB2 interacts with CDC25B/C but not CDC25A isoform. Overexpression of TRIB2 promotes polyubiquitination and degradation of CDC25C. Hence, future works are warranted to examine TRIB2-CDC25C interaction in the context of developing thymocytes and in T-cell acute lymphoblastic leukaemia, the malignant counterpart.

Vibration based health monitoring of civil infrastructure using energy harvesting techniques

The use of structural health monitoring of civil structures is ever expanding and by assessing the dynamical condition of structures, informed maintenance management can be conducted at both individual and network levels. With the continued growth of information age technology, the potential arises for smart monitoring systems to be integrated with civil infrastructure to provide efficient information on the condition of a structure. The focus of this thesis is the integration of smart technology with civil infrastructure for the purposes of structural health monitoring. The technology considered in this regard are devices based on energy harvesting materials. While there has been considerable focus on the development and optimisation of such devices using steady state loading conditions, their applications for civil infrastructure are less known. Although research is still in initial stages, studies into the uses associated with such applications are very promising. Through the use of the dynamical response of structures to a variety of loading conditions, the energy harvesting outputs from such devices is established and the potential power output determined. Through a power variance output approach, damage detection of deteriorating structures using the energy harvesting devices is investigated. Further applications of the integration of energy harvesting devices with civil infrastructure investigated by this research includes the use of the power output as a indicator for control. Four approaches are undertaken to determine the potential applications arising from integrating smart technology with civil infrastructure, namely • Theoretical analysis to determine the applications of energy harvesting devices for vibration based health monitoring of civil infrastructure. • Laboratory experimentation to verify the performance of different energy harvesting configurations for civil infrastructure applications. • Scaled model testing as a method to experimentally validate the integration of the energy harvesting devices with civil infrastructure. • Full scale deployment of energy harvesting device with a bridge structure. These four approaches validate the application of energy harvesting technology with civil infrastructure from a theoretical, experimental and practical perspective.