Understanding electron transfer in molecular systems is important, especially in the context of molecular electronics. With the desire to incorporate biological molecules in molecular electronic devices, there is a need to establish the relative importance of the various factors like the environment and the molecular structure (DNA sequence) on the electrical conduction. There has been much debate about mechanisms of electron transfer in biological molecules. We have conducted a systematic study of electron conduction across DNA molecular segments using the non-equilibrium Green function (NEGF) method. The Hamiltonian matrix elements were determined within the framework of the Extended Hückel Approximation. In considering (CG) base pair sequences, we find that the conductance decreases with segment length and that the substitution of (AT) base-pairs also reduces the conductance. When the DNA segments are in aqueous solution, the conductance is found to almost double in magnitude.

Living neuronal cells present active mechanical structures which evolve with cellular growth and changes in the cell microenvironment. Detailed knowledge of various mechanical parameters such as cell stiffness or adhesion forces and traction stresses generated during axonal extension is essential for understanding the mechanisms that control neuronal growth, development and repair. Here we present a combined Atomic Force Microscopy (AFM)/Fluorescence Microscopy approach for obtaining systematic, high-resolution elasticity and fluorescent maps for live neuronal cells. This approach allows us to simultaneously image and apply controllable forces to neurons, and also to monitor the real time dynamics of the cell cytoskeleton. We measure how the stiffness of neurons changes both during axonal growth and upon chemical modification of the cell, and identify the cytoskeletal components most responsible for the changes in cellular elasticity. This is accomplished by identifying cellular components with unique elastic signatures, and tracking those components over time within healthy cells or within cells treated to disrupt selective components.

A new type of counter-electrode based on platinum (Pt) nanoclusters has been introduced for semi-transparent dye-sensitized solar cells (DSSCs). This electrode is fabricated using a drop coating method where Pt nanoparticles dispersed in an acetone solvent are applied on a heated indium tin oxide (ITO) coated glass substrate. Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) images suggest that the Pt nanoparticles form a nanoporous structure with a large surface area while the distribution of Pt appears to be uniform on the surface of the ITO layer. UV/visible/near infrared transmittance spectroscopy showed that the Pt/ITO/glass electrode is highly transparent with a maximum transparency of 80% at 550 nm.

In this work a survey of possible optical stimulation processes in irradiated KCl:Eu with a focusing on photo-transfer thermoluminescence (PTTL) effects are shown. For different wavelengths in the range from 180 to 800 nm a cycle of measurements was performed, each comprising of a TL measurement after light irradiation, a TL measurement after beta irradiation for reference purposes and a PTTL measurement. The latter was obtained by applying first a beta irradiation, then a partial readout up to a certain end temperature followed by a monochromatic light irradiation of a specific wavelength and finally a TL measurement. This procedure was repeated for different partial readout end temperatures. From the results the existence of at least four different photo-transfer processes, induced by 310, 245 and 550 nm light are deduced. The photo transfer process induced by an approximate value of 245 nm produced a TL glow peak not seen before in beta or light induced TL. Furthermore it was observed that some of the TL peaks created by light of 240 and 260 nm were strongly sensitized after a beta irradiation and a partial readout.

Kinetics of the microstructural evolution in ZnO and NiO black powder mixture during prolonged mechanical processing (MP) was investigated by Scanning electron microscopy (SEM), Laser Particle Sizer (LPS), X-ray diffraction, electron paramagnetic resonance (EPR), infrared absorption (FTIR) and UV-Visible diffuse reflection methods.

Solutions of individual, unbroken single-walled carbon nanotubes in organic solvent were fabricated in a reductive dissolution process. Transparent conductive films deposited from these organic inks gave a significantly higher conductivity to absorptivity ratio than those cast from an aqueous dispersion of carbon nanotubes. For example, films from the organic ink have achieved a sheet resistance of 250 Ω/□ with transmittance of 92% at 550 nm wavelength, compared to 76% transmittance for a 250 Ω/□ film from the aqueous dispersion. The promise of these films as transparent electrodes has been demonstrated by their incorporation into organic solar cells with power conversion efficiency of 2.3%, comparable to that of solar cells produced using indium tin oxide transparent electrodes.

Periodic hybrid-exchange density functional theory (DFT) simulations are used to develop a predictive model of the structure of water on the rutile TiO2(110) surface (Θ ≤ 1 ML). A description of the adsorbed species is given: dissociated water molecules and either mixed or dissociative dimers. The behaviour of the adsorbates is rationalised by considering both direct intermolecular and surface-mediated interactions. Some of these results are then compared with those from water adsorption on the rutile SnO2(110) sur- face, isostructural to TiO2(110). Lastly, the electronic structure of the surface in contact with monolayer water (Θ = 1 ML) reveals the contributions of adsorbate states involved in the photocatalytic reaction that controls the water oxidation process.

The development of suitable waste forms for waste produced by generation IV reactors is of critical concern for future operations. To date no accepted disposal route for Tri-Structural Isotropic (TRISO) High Temperature Reactor (HTR) fuel exists. Alumino-borosilicate glass has been studied for its ability to encapsulate TRISO particle fuels. This glass was selected for its high aqueous durability. Encapsulation was achieved by cold pressing and sintering of glass powders mixed with HTR fuel. Sintering profiles capable of eliminating interconnected porosity in the composites were developed. The chemical compatibility and wetting of the glass matrix with the fuel were analysed along with the aqueous durability of the sintered glass matrix. Composites sintered under a controlled atmosphere produced unfractured monoliths with minimal chemical interaction between the glass and the TRISO particles. The Product Consistency Test (PCT) durability assessment indicated the sintered alumino-borosilicate glass was approximately an order of magnitude more durable than an equivalent R7T7 borosilicate glass. These results suggest sintered alumino-borosilicate glass-TRISO particle composites may provide a potential disposal route for spent TRISO particle fuel.

A nanopatternable oligomeric PDMS layer has been first verified as a nano-adhesive for its intrinsic transferability and universal adhesiveness. Utilizing the well-established PDMS surface modification and bonding techniques, we have been able to form irreversible bonding between a wide range of substrate pairs, representing ones within and across different material categories, including metals, ceramics, thermoset, and thermoplastic polymers. The anisotropic conductivity of the PDMS oligomer nano-adhesive has been investigated, which allows specific and excellent directional conductivity between bonded electrodes without risk of electrical shorts across different contacts.

Anodic oxide formation and chemical and electrochemical etching of n-Si(111) have been investigated in alkaline media. Due to the complexity of the processes, the investigation has been restricted to the initial phase where a transitory anodic photocurrent peak is observed slightly positive from the open circuit potential (ocp). In-system photoelectron spectroscopy, performed at the U 49/2 beamline at Bessy, shows sub-monolayer silicon surface oxidation and remnant H-termination, indicating island-type oxide formation. Scanning probe microscopy shows the formation of macropores with 300-500 nm diameter and an average depth of 5-8 nm. The discussion comprises chemical and electrochemical dissolution mechanisms and routes to development of nanoemitter fuel generating devices.

Tungsten is one the most important material for both plasma facing and structural applications in current designs for advanced divertors. Recent work has shown that composites can be manufactured from nanostructured tungsten foils which show significantly higher toughness than monolithic tungsten, but there is no data on the radiation resistance of such materials. In this study W-5 wt% Re foil in both an as rolled and annealed condition was implanted with 2MeV W+ ions to two damage levels, 0.07 and 0.4 dpa. The change in hardness was measured using nanoindentation. An increase in hardness was seen in both materials at both damage levels, with more hardening seen for the 0.4 dpa implanted samples. However the increase in hardness due to ion implantation was 2.6 times higher in the annealed material as compared to the as rolled material. This is due to the smaller grain size and higher dislocation density providing more sinks for the irradiation produced defects in the as rolled material as compared to the annealed material. Thus showing that unannealed tungsten foils are superior for use in applications in which they will see significant levels of radiation damage.

We present a detailed study carried out on oxide buffer layers grown by Metal-Organic Decomposition (MOD) on metallic substrates for YBa2Cu3O7-x (YBCO) coated conductor applications. Precursor solutions have been made starting from acetates or pentanedionates and characterized by means of Differential Scanning Calorimetry (DSC) and Thermogravimetric (TG) analyses coupled with Fourier Transform Infra-Red spectroscopy (FT-IR). Thin buffer layers have been grown by spin-coating on Ni-5at.%W substrates. X-ray diffraction spectra (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) have been employed in order to optimize buffer layers in terms of film microstructure and surface quality, with the final aims of producing a suitable template for YBCO growth. It will be shown that the optimization of the recrystallization process can lead to high quality buffer layer allowing the growth of YBCO films showing good superconductive properties.

Silicatein is general catalyst for synthesis of silica structure in siliceous sponges. However, the advent of biomimetic silicification by this recombinant version is limited by its poor yield. To overcome this limitation, we employed a cathepsin L as an alternative to silicatein. Cathepsin L has high sequence identity and similarity with silicatein alpha except cysteine other than serine residues at the active site. Here, we expressed recombinant hypothetical cathepsin-like protein (CAT) from Nematostella vectensis, displaying not only protease activity but also silica condensing activity. To increase the silica forming activity, some residues including cysteine in active site were changed into silicatein conserved residues. The mutant silicatein-like cathepsin (SLC) revealed increased protein stability in comparison with that of CAT when expressed in E. coli. The silica forming activity of SLC was comparable to that of SIL. SLC produced silica particles of size less than 50 nm which were increased to 200∼300 nm in the presence of a structure-directing agent, Triton X-100. Protein immobilization by SLC-mediated silicification was performed using bovine carbonic anhydrase under ambient conditions. Immobilized protein retained its enzymatic activity for a longer time and was reused up to several times. In conclusion, CAT from Nematostella vectensis was evolved to a more soluble and available biosilica forming protein that can be applied for various silica-based materials.

We report a method for stress measurement and analysis in silicon oxide thin films using optical interference. Effects of design and fabrication on stress have been studied by fabricating submicron-thick slabs of oxide anchored at one end and extending over a reflective surface. Optical interference occurs between reflections from the surface and the oxide slab, giving rise to light and dark fringes that may be imaged with a microscope. Analysis of the interference pattern at different wavelengths gives the radius of curvature and means of stress mapping. The accuracy exceeds non-interferometric profilometry using optical or confocal microscopes, and it can be more quantitative than scanning electron microscopy. This nondestructive profilometry method can aid the stress optimization of silicon oxide or other transparent thin films to achieve specific mechanical characteristics in MEMS devices.

The real-time electronic performance of a gallium nitride nanowire-based field effect transistor was investigated at five-minute intervals over thirty minutes of continuous irradiation by Xenon-124 relativistic heavy ions. An initial current surge that resulted in device improvement rather than device failure was observed. The current surge, and subsequent electronic behavior, was modeled using a combined thermionic emission-tunnelling approach, leading to information about barrier height, carrier concentrations, expected temperature behavior, and tunnelling.

Ultra-high molecular weight polyethylene/graphite nanocomposites were prepared by high-energy cryogenic milling followed by syntering. Microstructure changes shows that graphite was reduced to graphite nanoplatelets by high-energy cryomilling and partial exfoliation of graphite to few layered graphene nanoplatelets occurred in a small extent. The resulting nanocomposites revealed high electrical conductivity and good mechanical performance. Thermal characterization of the nanocomposites was also carried out by differential scanning calorimetry.

Papers in the Appendix were published in electronic format as Volume 1534

Poly(methyl methacrylate)/biphasic calcium phosphate (PMMA/BCP) coating has been prepared by mixing BCP in situ with the poly(methyl methacrylate) obtained from methyl methacrylate (MMA) polymerization. For comparative studies, concentration of BCP into PMMA matrix was varied in order to determine the influence of BCP incorporation into PMMA matrix on the hardness and friction behavior. The micro-hardness of PMMA/BCP coatings on stainless steel was evaluated using a Vickers hardness tester, while the wear tests for PMMA/BCP coatings on stainless steel were carried out on a CSM tribometer in dry conditions with normal load of 2 N. The incorporation of BCP into the polymer matrix significantly improves the microhardness of PMMA increasing to 15 % with 0.25 wt.% of BCP content. Whereas, the lowest friction coefficient value µk = 0.35 was obtained for PMAA/BCP with 0.35wt.% of BCP.

LiMnPO4 cathode materials of various sizes and shapes are synthesized by a hydrothermal method. In order to control the morphology of the LiMnPO4 particles, a nonionic surfactant or a cationic surfactant has employed as a key additive to the reactant solution. LiMnPO4 nanoparticles of grain-shape and rod-shape can be made with sizes between about 100 and 300 nm by adding a nonionic large polymer surfactant. Micrometer-sized LiMnPO4 particles of cuboid shape result from the reaction with a cationic surfactant. LiMnPO4 spheres of about 20 μm diameter are produced when no surfactant is added. The cathode composed of nanocrystalline (about 100 nm size) LiMnPO4 exhibited the best performance with the specific capacity of 153 mAhg-1 for the first battery cycle.