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Arctic sea ice plays a vital role in the Earth's climate system, through its reflection of solar energy and insulation of ocean heat, and has changed rapidly in the past 20 years. Model simulations of Arctic sea ice display a wide spread both in the present-day and in the future. Due to lack of observations however, evaluation of sea ice simulation has historically been limited in scope mainly to ice extent and (sometimes) volume, with little attempt to evaluate at large scale simulation of the fundamental thermodynamic processes governing sea ice growth and melt. In this thesis two new, contrasting methods are presented for evaluating Arctic climate simulation that address this: firstly, the induced surface flux (ISF) framework attributes model biases (differences) to specific proximate drivers using existing reference datasets. Secondly, the Arctic ice mass balance buoy (IMB) network is used to build a dataset with which to evaluate many sea ice thermodynamic processes directly. We use three UK CMIP models for analysis: HadGEM2-ES, HadGEM3-GC3.1 and UKESM1.0. These models display very different Arctic sea ice simulations, with ice in HadGEM2-ES thinnest and ice in UKESM1.0 thickest. Using the ISF framework and IMB evaluation, it is shown that modelled sea ice volume is tightly coupled to modelled ice growth and melt, and that most of the model biases and differences are caused by differences in albedo and atmospheric forcing arising in the late spring and early summer. Despite this, a downwelling longwave radiation bias present in all models during winter 'predisposes' them towards a thicker ice cover. The methods can also be used to evaluate the proximate impact of specific model improvements in the latter two models on sea ice growth and melt, which is seen to be small but non-negligible. The results also show that more accurate observations of Arctic radiative fluxes, and of snow area and thickness, would be particularly useful in improving model evaluation, and that ice mass balance buoy measurements would be made more useful by simultaneous measurement of salinity.

We present an experimentally guided study of film layer structure and opto-electronic properties of transition metal oxide (TMO) films. The oxide material system studied comprised the metals silicon (Si), zinc (Zn), and indium (In). The films were deposited via radio frequency magnetron sputtering (RFMS) on room-temperature Corning Eagle XG Glass (CEXG) substrates. Distinct (bi-layer (BL) vs single-layer (SL)) layer structures manifest as a function of angular distribution or pressure distance product (Greek letter 'phi') of sputtered material flux sourcing film growth. The films are amorphous, transparent and semiconducting. Experimental determination of absolute temperature (T) dependence of resistivity (Greek letter 'rho') revealed that at temperatures close to room-temperature, ionized impurity scattering (IIS) is the dominant conduction electron scattering mechanism. Thence, application of the Brooks-Herring (BH) model of IIS permitted analysis of the electronic state of the films. Thereby, the electronic state was revealed to be highly compensated. The design of experiment (DOE) and (associated) response surface analysis (RSA) frameworks were recruited from the very first stage - namely, the stage of film fabrication - of this study. This provisioned a self-referencing set of (nine) films (the 'samples') that are the subject of this study. The two layers of the BL films are / will-be-referred-to-as the sub-plantation layer (SPL) and the thin-film layer (TFL). The SPL is situated mediate substrate and TFL, and constitutes thereby the film-substrate interface. For consistent nomenclature, the term 'TFL' will be used to refer to the sole (film) layer of SL films. The layer structures of the films were established via x-ray reflectometry (XRR). The films were interrogated optically via spectroscopic ellipsometry (SE) (at room-temperature), and electrically via AC Field Hall Effect (ACFHE) measurements (between T = 10.1 K to 300 K). An account of the understanding of the film layers - viz., SPL, and TFL - as has been achieved, is as follows: ~ The sub-plantation layer (SPL) ~ We report the controlled emergence of a bonafide nanoscale layer - the SPL - at (comprising) the film-substrate interface. The determination of presence of a SPL is direct - that is, sans any assumptions, or modeling - via Fourier analysis of XRR results. We present three independent - experimental, empirical, and theoretical - threads of analysis to rationalize emergence of the SPL, as follows: > In terms of deposition process conditions under which a SPL manifests. Our semi-quantitative analysis is in terms of angular distribution or phi of the material flux sourcing film growth. Evidently, this thread of analysis is beholden to the specific physics of the deposition process, namely, RFMS. > Via RSA of SPL physical properties (SPL thickness (dSPL), SPL density (DSPL), and SPL roughness (rSPL)). This analysis reveals the following two process factors to be relevant: RF power (PRF), and process gas pressure (p). While the analysis is on the basis of experimentally observed process factors dependence of the physical properties noted, it is not beholden to the physics of the deposition process (RFMS). > Via dimensional analysis (DA) of the physical properties noted previously, in light of RFMS process. The dimensionless group for PRF (PRF*) thus determined reveals precisely the two previously noted process factors to be relevant. This analysis is ab initio. We highlight implications of our results for the industrially important problem of sputtered-film-on-substrate adhesion. Thereby, our results bear commercial promise, particularly for research and development (R&D) of flexible electronics applications. ~ The thin-film layer (TFL) ~ We quantify the semiconducting nature of the films (TFLs) on basis of optical (via SE) and electrical (via ACFHE) measurements of their room-temperature electronic properties. We interrogate the film (material system) electronic state on basis of the experimentally determined T dependences of conduction electron concentration (n) and conduction electron mobility (Greek letter 'mu'). Presence of a T-range (in the vicinity of and including room-temperature) where IIS is the dominant conduction electron scattering mechanism is established. Application of the BH model of IIS then lead to the (quantitative) determination that the electronic state is (highly) compensated. This determination - consistent with the experimentally observed anomalous oxygen content dependence of - is consistent with trap limited conduction. Thereby, we relate the electronic state to the chemistry and physics of film microstructure and material system. ~ The ready-reckoner ~ Figure 7.1 presents another and visual walk through - a 'ready-reckoner' - of this study. ~ Epilogue ~ This study represents new lines of investigation for the Professor Peter P. Edwards FRS ML Group.

Over the last few decades there has been strong interest in quantum information systems based on photonic qubits. Devices able to emit pure single-photon states on demand and detect incoming single photons in the system are fundamental building blocks for the realisation of a quantum photonic scheme. Advances in controlling single carriers have made it possible to transport single electrons using surface acoustic waves (SAWs). In a lateral n-i-p junction SAW-driven single-electron transport can be exploited to pump single electrons across the junction and generate single photons. In this work, devices have been developed in which both electrons and holes can be induced in an undoped GaAs/AlGaAs 15nm quantum well by gates to form a lateral n-i-p junction. The junction is confined into a quasi-1D channel laterally by etching and side gates. Light emission is observed when a 1 or 3 GHz SAW drives a current, by pumping electrons over the potential hill in the intrinsic region. SAW-driven electroluminescence has been characterised in the regime where less than one electron is transported per cycle on average. Time-resolved electroluminescence has been used to extract the electron recombination time and to quantify the contributions from electromagnetic crosstalk and the SAW. In a device without significant crosstalk, the degree of second-order coherence, g(2)(0) , shows the signature of antibunching. Hole SAW-pumping has been investigated as an alternative to electron pumping, showing a shorter recombination time. The dynamics has been further investigated with time-resolved and energy measurements at the junction, using a sub-micron positioner with lens assembly to scan along the pumping direction. A key requirement for practical quantum devices is the scalable integration of single-photon sources, detectors and linear optical elements on a common platform. Using the same type of heterostructure, photons are detected by collecting and measuring the photo-generated carriers. An external light source sends photons into the system, and when they are absorbed in the quantum well, they create electron-hole pairs. The photo-generated carriers are separated and transported by a SAW together with an electric field applied by gates on the surface. The carriers are then collected by ohmic contacts, in order to extract information about the number of photons absorbed. Using the same 15nm GaAs/AlGaAs quantum well as for the single- photon source, an acousto-electric photon detector has been realised and characterised. Single-photon sensitivity can be achieved by measuring the photo-generated charges at single-particle level. The possibility to include single-electron and single-hole charge readout using quantum dots and quantum point contacts has been investigated.

This work explores novel applications of X-ray Photoelectron Spectroscopy (XPS) of organic systems and formulations, as well as improvement of the so-called pKa rule for predictability of multicomponent solid-state forms. Physicochemical properties of active drugs can be substantially improved by combination with a coformer, although distinguishing between the nature of the resulting form can be difficult as it relies on the position of a proton. XPS is sensitive to the chemical and electronic states of elements, and N 1s XP spectra have previously been shown to unambiguously distinguish between protonated NH+···O (salts) and un-protonated N···HO (co-crystal) states. N 1s analysis of three compounds with uncertainty as to the presence of quasi-centred hydrogen (N··Hδ+··O) or hydrogen bond disorder has unequivocally identified the lack of quasi-centred hydrogen positions. The degree of disorder could be recognised and quantified with XPS, showing the viability of this application, even for compounds with five different nitrogen moieties. The capabilities of O 1s spectra to identify proton transfer were investigated using three fluorescein tautomers with OHO interactions. Analysis revealed a similar degree, opposite sign chemical shift in binding energy for de-protonation of oxygen (-2.5 eV) as for the previously established protonation shift for nitrogen (+2 eV). The pKa rule is a quick guide used in the selection of suitable coformers based on the difference in pKa between components. An inexpensive and accessible tool for generating the pKa values for a large set of structures was devised via the cheminformatics platform KNIME and used for the analysis of organic acid-base complexes with an NHO interaction. Results found a significant improvement in the precision of the pKa rule once the nature of the intermolecular interactions is considered, demonstrating a 49 % reduction (RP < 90 %) for the region in which the pKa difference is uncertain in predicting salt vs. co-crystal. The exterior surface and cleaved interior surface (representative of bulk) of paracetamol tablets were analysed using C 1s XPS to identify whether low % w/w magnesium stearate (MgSt) could be detected. Analysis conclusively showed an abundance of MgSt on the exterior surface in addition to qualitative and quantitative information regarding alterations in the surface composition for tablets stored under varying relative humidity conditions. The results of the combined studies demonstrate the potential breadth of information obtainable through XPS analysis for simple to increasingly complex organic systems.

In linear accelerator driven 4th generation Free Electron Lasers (FELs), the final beam quality is set by the linac and ultimately by its photoinjector and photocathode. Therefore, to deliver cutting-edge beam characteristics, there are stringent requirements for the photocathode used in the photoinjector. Understanding how surface properties of materials influence photocathode properties such as quantum efficiency (QE) and intrinsic emittance is critical for such sources. Metal photocathode research at Daresbury Laboratory (DL) is driven by our on-site accelerators VELA (Versatile Electron Linear Accelerator) and CLARA (Compact Linear Accelerator for Research and Applications), a free electron laser test facility. Metals offer the advantage of a fast response time which enable the generation of short electron pulses. Additionally, they are robust to conditions within the gun cavity. The main challenge with metal photocathodes is to maximise their (relatively) low electron yield. In this PhD thesis, the goal has been to carry out an experimental investigation on alternative metals to copper, correlating surface properties with photoemissive properties. A range of surface analysis techniques have been employed: surface composition was investigated using X-ray Photoelectron Spectroscopy and Medium Energy Ion Scattering, Kelvin Probe apparatus and Ultra-violet Photoelectron Spectroscopy were used to measure work function, and Atomic Force Microscopy and Interferometric microscope provided images characterising surface morphology. The photocathode properties studied include: QE measured using a 265 nm UV LED source that was later upgraded to a 266 nm UV LASER, and Mean Transverse Energy measured using the Transverse Energy Spread Spectrometer. As a result of this work, Mg, Nb, Pb, Ti and Zr have all been identified as photocathode candidate materials, each exhibiting a QE greater than Cu. Additionally, surface preparation procedures for optimising QE from a selection of metals has been explored; the findings of these experiments would suggest that ex-situ Ar plasma treatment followed by in-situ heat treatment is well suited to remove surface contaminants without altering the surface morphology of the cathode. As part of this work, metallic thin films produced by magnetron sputtering have been produced; ultimately the chosen cathode metal will be deposited onto a cathode plug which will be inserted into the electron gun that will drive CLARA. Thus the preparation of metal thin films has been investigated and the effect of different substrate materials on the film properties has been explored. Preliminary experiments studying the effects of surface roughness on photoelectron energy distribution have been conducted; the findings have not been conclusive, thus further systematic studies are required.

Consider the graph induced by Z^d, equipped with uniformly elliptic random conductances on the edges. At time 0, place a Poisson point process of particles on Z^d and let them perform independent simple random walks with jump probabilities proportional to the conductances. It is well known that without conductances (i.e., all conductances equal to 1), an infection started from the origin and transmitted between particles that share a site spreads in all directions with positive speed. We show that a local mixing result holds for random conductance graphs and prove the existence of a special percolation structure called the Lipschitz surface. Using this structure, we show that in the setup of particles on a uniformly elliptic graph, an infection also spreads with positive speed in any direction. We prove the robustness of the framework by extending the result to infection with recovery, where we show positive speed and that the infection survives indefinitely with positive probability.

Three norbornane fused dihydro-tetrathiafulvalene derivatives which contained the thiol, disulfide and acetylthio functionalities were synthesised. Cyclic voltammetry was used to measure the redox properties of the compounds, which showed that the molecules were able to undergo two reversible, one electron oxidation processes. X-ray structures of all three functionalities were obtained. The three compounds were sublimed onto Au(111) surfaces, and characterised using a number of surface science techniques. Disordered structures are formed initially for all three compounds when adsorbed at room temperature. Following progressive annealing of the substrate, highly ordered adlayer structures are formed that are believed to be bound to the surface via a gold adatom. Van der Waals and hydrogen bonding interactions are shown to play an important role in the formation of these ordered structures. The adsorption of triphenylphosphine sulfide on Au(111) is also investigated, using a combination of RAIRS and STM experiments. Here an extremely ordered (2√3×2√3)R30º structure is formed immediately upon deposition at 298 K. From the experimental data and DFT calculations, the orientation of the molecule is deduced. The attempted synthesis of a thiol functionalised donor-acceptor compound is also described, with a few previously unknown intermediate compounds being synthesised. Finally, a series of four known aryl amidoximes were synthesised. These were subsequently deposited on a Cu(111) crystal and studied using a vibrational spectroscopy. Three of the compounds were found to decompose to varying degrees during the sublimation process. The possible conformations of the amidoxime group on the copper surface are discussed.

There is a need for wind sensors with high accuracy and measurement frequency for deployment on the surface of Mars. The wind data obtained to date have been adversely affected by thermal contamination and calibration issues. Improved data would not only help to constrain and validate theoretical models, but also increase safety and longevity of lander operations. The mechanical and thermal wind sensing techniques used on previous missions, whilst sufficient for basic meteorology, are wholly inadequate for measuring fundamental phenomena such as dust and volatile transport. Two promising technologies, optical and acoustic anemometry, could permit precise and high-frequency measurement of three-dimensional wind speeds on the Martian surface. Ultrasonic acoustic anemometry, which relies on time-of-flight measurements, was ultimately chosen for its lower processing requirements and ability to measure the speed of sound; and therefore temperature. Capacitive transducers were selected for their low impedance and high sensitivity, to maximise signal transmission through the rarefied Martian atmosphere. These transducers, which consist of a metallised polymer film oscillating on top of a contoured metal backplane, were evaluated for their suitability as anemometers on the Martian surface. A theoretical framework was assembled to model transducer performance and determine which factors are the most important in determining received signal amplitude. A pair of transducers were designed and manufactured to allow for testing of a wide range of parameters including thickness of the oscillating membrane and diameter. Tests were carried out on the assembled transducers to investigate the dependence on these parameters, and their behaviour was generally found to fit the assembled theoretical framework well. Transducer performance was highly dependent on roughness depth of the backplanes, as expected. The frequency response of the transducers was dominated by the backplane roughness at atmospheric pressure but by film thickness at low pressures. Cross-correlation of the sent and received signals was confirmed as the most reliable signal detection method at low signal amplitudes. The transducers were tested under simulated Martian conditions (a low-pressure carbon dioxide atmosphere with airborne dust), and found to be capable of accurately and reliably measuring the incident wind speed. The cumulative deposition of airborne dust noticeably reduced received signal amplitude, but further testing is required to determine the effect of significant amounts of dust on transducer performance. The impact of the transducer heads impeding the incident fluid flow was found to be very significant in wind tunnel testing. Preliminary computational models were found to accurately predict these effects, but a more comprehensive modelling campaign and experimental validation would be required to ensure accurate instrument calibration.

This thesis is concerned with the synthesis of diazo compounds for the introduction of various functional groups on the surface of polymers by means of carbene insertion and diazonium coupling. Characterisation and investigation of their properties were conducted. A library of functionalised polystyrene beads containing pyridine rings has been established for the coordination of metal ions and metal complexes. The pyridyl system on the surface has demonstrated its capability to bind with zinc complexes of bis(thiosemicarbazones) and release the corresponding copper complexes upon transmetallation. A spiropyran derivative has been introduced onto the surface of polystyrene and polyethylene terephthalate. The chromophore on both polymers exhibited photoswitchability as determined from colour change and wettability. Polystyrenes with either pyridine or spiropyran units have been investigated for reversible immobilisation of bioactive species. Materials coated with penicillin V gave significant inhibition zones in antibacterial assays, showing efficacy in drug delivery. Finally, a range of diazo compounds with different substituents has been synthesised and their thermal stabilities have been assessed by differential scanning calorimetry technique.

The pursuit for improved engine efficiency is driving the demand for accurate temperature measurement inside turbine engines. Accurate measurement can allow engines to be operated closer to their design limits to improve thermal efficiency. It can enable engineers to verify mechanical integrity, provide better prediction of component life, validate CFD and other design tools and aid the development for leaner more efficient engines. Unfortunately, experimentally measuring surface temperatures under harsh rotating conditions is challenging. This EngD study conducted by Ashiq Hussain Khalid at the University of Manchester and Rolls-Royce plc, reviews the rationale of using phosphor thermometry over existing methods, including thermocouples, pyrometry and thermal paints/melts, which lack detail, accuracy, or are too expensive for continuous testing. Although phosphor thermometry exhibits desirable characteristics, the high temperature and fast rotating engine environment presents some challenges that would need to be addressed before a successful measurement system can be implemented. Examples of such issues include: rising blackbody radiation, restricted optical access, fibre optic constraints and limited time period to collect data. These factors will impose measurement limits and greatly influence the design philosophy of the system, including phosphor choice, phosphor lifetime characteristics, bonding technique, excitation/detection methodologies and probe design. Taking these into consideration, the research focuses on the development of phosphor thermometry systems for use in development gas turbine engines, with measurement solutions for specific engine components. The high pressure turbine blade was given research priority. A number of phosphors including YAG:Tb, YAG:Tm. Y2O3:Eu and Mg3F2GeO4:Mn were investigated and characterised in terms of intensity and lifetime decay, with increasing temperature up to 1500oC. Spectral analysis and absolute intensity measurements established emission peaks and permitted comparative quantitative analysis to optimise system setup. The intensity of phosphor emission relative to Planck's blackbody radiation was also performed. YAG:Tm under 355nm illumination was found to exhibit the highest emission intensity at high temperatures, and because its spectral emission peak at 458nm was the lowest, its advantage in terms of blackbody radiation was further amplified. For rotating components, an upper temperature limit is reached based on the emission intensity at rising blackbody radiation levels and the system's ability to detect fast decays. A lower limit is reached based on the quenching temperature, probe design and rotational velocity. There are different methods to correct the distorted decay waveform as it traverses through the acceptance cone of the fibre. A phosphor selection criterion, taking into consideration these limitations, was successfully applied for various rotating engine components. The optical layout was setup and tested on stationary and rotating cases under laboratory conditions using similar design constraints, including fibre choice, maximum permissible lens size and target distances. A series of tests validated design methodologies and assumptions to enable testing on full scale rotating engine components. Mg3F2GeO4:Mn, using 355nm illumination, was found to be the most suitable phosphor for the HP drive cone. The estimated performance under the expected rotational speeds was found to be 624-812°C with a standard uncertainty of ±0.99%. YAG:Tm, illuminated with 355nm, was found to be the most promising phosphor for high pressure turbine blade measurements. The performance under the expected rotational speeds was found to be 1117-1375°C with a standard uncertainty of ±0.97%. This is better than other competing technologies that are currently available for temperature measurement of rotating turbine blades.

Hyaluronic acid (HA) is one of the major components of the extracellular matrix; and may exhibit different biological functions, dependent on polymer molecular weight (MW). The signalling events performed by HA are mediated through interactions with its main cell receptors: CD44 and RHAMM. However, the direct effect between the HA MW and the expression of CD44 and RHAMM remains unclear. This study aimed to investigate whether different HA polymer MW alters the proliferation of tumour-derived cell lines, and whether different HA-sized has an effect on the regulation of the expression of CD44 and RHAMM. In order to determine size-specific responses of tumour cells of defined fragment MW, this investigation was undertaken using HA-tethered culture surfaces. Four surfaces were constructed, coated with polymers of different MWs. HA (4, 234, 2590 kDa) and an oligomer mixture were tethered onto an aminosilane (AHAPTMS)-treated glass surfaces using a carbodiimide reaction. Surfaces were analysed using a toolbox of in situ characterisation techniques, including wettability measurements, QCM, AFM and confocal microscopy. Using the constructed surfaces was demonstrated that HA-polymer MW modulates cell proliferation of human bladder (RT112 and T24) and prostate (PC3 and PNT1A) cell lines, with low HA MW (HA4) increasing proliferation, whereas a decrease is seen in the presence of medium (HA234) and high MW fragments (HA2590). The proliferation stimulus performed by HA was found to be phenotype dependent, with HA4 surfaces stimulating an increased proliferation in those less invasive cell lines (T24 and PNT1A), while HA234 and HA2590 inducing a sharper decrease in the most malignant tumour cell lines (RT112 and PC3). It was also demonstrated that the regulation of CD44 and RHAMM transcripts expression appears to be phenotype dependent but not HA-MW dependent. HA down-regulates CD44 and RHAMM in the most malignant cell lines; with up-regulation of the expression of the cell receptors in the less invasive cell lines. In addition, the presence of exogenous HA was shown to be involved in the regulation of the expression of CD44 variants expression. The results obtained for the CD44 and RHAMM protein expression were also found to be correlated with the obtained transcripts expression. However, the significance of these findings in tumourigenesis remains unclear. Findings from this investigation may help in the design and development of biocompatible implants with controlled surface properties to be used in cancer therapeutics; with medium and large HA polysaccharides being potential biopolymer candidates, useful for the development of novel therapies for highly invasive cancer. In addition, implications from this work can serve as a base for future research, and can lead to ideas for drugs and methods to be used in cancer therapeutic approaches.

The principal aims of this research have been the development of photogrammetric techniques for the measurement of anisotropic deformation in uniaxially loaded cylindrical specimens. This has been achieved through the use of calibrated cameras and the application of edge detection and multiple view geometry. The techniques have been demonstrated at quasi-static strain rates, 10^-3 s^-1, using a screw-driven loading device and high strain rates, 10^3 s^-1, using Split Hopkinson Bars. The materials that have been measured using the technique are nearlyisotropic steel, anisotropic cross-rolled Ti-6Al-4V and anisotropic clock-rolled commercially pure Zr. These techniques allow the surface shapes of specimens that deform elliptically to be completely tracked and measured in situ during loading. This has allowed the measurement of properties that could not have been recorded before, including true direct stress and the ratio of transverse strains in principal material directions, at quasi-static and elevated strain rates, in tension and compression. The techniques have been validated by measuring elliptical prisms of various aspect ratios and independently measuring interrupted specimens using a coordinate measurement machine. A secondary aim of this research has been to improve the characterisation of the anisotropic mechanical properties of cross-rolled Ti-6Al-4V using the techniques developed. In particular, the uniaxial yield stresses, hardening properties and the associated anisotropic deformation behaviour along the principal material directions, have all been recorded in detail not seen before. Significant findings include: higher yield stresses in-plane than in the through-thickness direction in both tension and compression, and the near transverse-isotropy of the through-thickness direction for loading conditions other than quasi-static tension, where significant anisotropy was observed.

In the early twentieth century, the modernists problematized ornament in their refashioning of architecture for the industrial age. Today, architects are formulating different responses to image and its (re)production in the information age. In both discourses of ornament and image, surfaces are often the perpetrators: visual boundaries that facilitate false appearances, imprisoning humanity in a shadowy cave of illusion. Such views follow a familiar metaphysical model characterized by the opposition between inside and outside and the opaque boundary that acts as a barrier. This model determines the traditional (Platonic) philosophical approach that follows a distinct hierarchical order and a perpendicular movement of thought that seeks to penetrate appearances in order to arrive at the essence of things. This thesis deploys Gilles Deleuze’s philosophy to advance a different understanding of surface, image and appearance in architecture. Using the Bilbao Guggenheim Museum as a catalyst, the thesis argues that many of the concepts with which commentators and critics analyse contemporary architecture follow models of thought that consider surfaces and their effects as secondary categories. Given the significance of visual (re)production and communication for contemporary society, the thesis proposes a different model based on surface as that which simultaneously produces, connects and separates image and reality. This non-hierarchical approach is inspired by surficial philosophy, which relates to Earth, to geology and topology, conjuring up a diversity of concepts from the thickness of the crust to the smooth fluidity of the seas. The result is an unfamiliar, polemical model of thought that does not define surface as a limit or barrier, rather a medium, a pliable space of smooth mixture. In this model, difference is not in the opposition between the two sides of a boundary line, rather it occurs upon and within the surficial landscape that consumes categories, promoting nomadic movements of thought that offer greater flexibility towards creativity and new possibilities. In surficial thought, images and appearances are not artificial copies of an originary reality, rather they possess a unique reality of their own. This approach allows architectural imagery to be theorised as a positive surfacing of architecture beyond disciplinary lines and the locality of a specific time and place.

Numerous fields of applications require a digital model to be produced from a physical object, for example in computer-aided design of appliance casings, manufacture of engineering components and virtual reality. A digital description allows changes in design and manipulation of the data, where it would be, for example, too expensive, too dangerous, or too time-consuming to do the same in the physical world. In order to obtain data from the physical object, coordinate measuring devices record data either by contact-less or by contact measurement, and in many cases the result yields an unstructured point cloud. Before the surface of a digitised object can be manipulated interactively, it must be reconstructed from the (possibly unstructured) set of points. With structured points the generation of a triangulated surface is relatively straightforward. To generate an initial triangulated surface out of the unstructured point cloud sophisticated methods have been established. The present project aims to achieve the next important step in surface reconstruction, namely to segment the triangulated surface into parts of simple geometric primitives, in particular of the following: plane, sphere, cylinder, cone, and torus. Such segmentation enables engineers to manipulate data for design purposes more quickly, because connected point sets, rather than individual points, will be affected. Subsequently the data can be used for "rapid prototyping", i.e. the manufacture of a physical model from a digital description. In order to obtain a segmentation of a triangulated surface the approach for the extraction of geometric primitives used in this project has been based on a "region growing" method. It attempts to grow small initial seed regions satisfying a "homogeneous shape" criterion within a given tolerance. Each time the growing process yields a sufficiently large connected set of triangles a new segment of a geometric primitive with its corresponding characteristic parameters and boundary curves is identified. An additional source of shape information about triangulated surfaces is an estimate of curvature for each triangle. Curvature information allows the selection of appropriate seed regions, and it allows good initial estimates of characteristic parameters to be found. This is important because the growing process under preservation of shape involves numerical optimisation, whereby the initial ^ characteristic parameters are adjusted as the region grows. Methods of curvature estimation for triangulated surfaces have been investigated. Curvature estimation algorithms for triangulated surfaces have been developed and evaluated for both synthetic data (for which curvature values are known) and "real" data. They compare favourably with other curvature estimation algorithms suitable for discrete data. A formula for the sign of curvature has been found in the literature to give sometimes a wrong result and an appropriate correction has been suggested. Algorithms for region growing have been established which are based on the curvature estimates obtained. Techniques have been developed for determination of initial characteristic parameters for planes, spheres, cylinders, cones, and tori using the estimated curvature, when only very small seed regions are available. Further work has established how characteristic parameters of segments of geometric primitives can be adjusted by region growing formulated as a minimax optimisation problem. A fast method for the extraction of planar patches on a triangulated surface has been developed which is faster than the numerical approaches needed for the more complicated geometric primitives. This extraction employs a new, simple geometric method that exploits the asymptotic behaviour of an "expanded triangle" used to represent the plane. This method cannot only be applied to triangulated surfaces but also to any data representation that provides adjacency information. Results from the extraction involving all types of the above geometric primitives have been evaluated on "real" data. For many simple objects successful segmentation has been achieved and it is expected that further refinement of the developed algorithms will enhance their performance.cannot only be applied to triangulated surfaces but also to any data representation that provides adjacency information. Results from the extraction involving all types of the above geometric primitives have been evaluated on "real" data. For many simple objects successful segmentation has been achieved and it is expected that further refinement of the developed algorithms will enhance their performance.

The preparation of mesoporous platinum has been studied by the reduction of a platinum salt in the aqueous domains of the hexagonal phases of Brij surfactant systems. A detailed study of the synthesis of mesoporous platinum from such mixtures revealed the ability to increase the regularity of the nanostructure and surface area of the materials by varying the amount of surfactant in the templating mixture or varying the reduction temperature. The most successful method of preparing H₁ material employed reduction with iron metal from Brij 76 lyotropic H₁ phase at 40 °C. BET surface area analysis showed the mesoporous platinum to have a surface area of 46 m²g⁻¹. The pore size of the H₁ materials was found to be ~3nm with -3.5 nm thick walls. The templating mechanism was then extended to the chemical preparation of mesoporous palladium and lead materials from the H₁ phase of Brij 76. The electrochemical reduction of lead precursors within the H₁ domain of Brij 56 on Au support was also shown to be a successful method to obtain nanostructured lead films. Direct liquid crystal templating of Pt-based alloys was also investigated. The co-reduction of binary mixture of platinum and ruthenium metal compounds dissolved in the H₁ phase of Brij 76 leads to bimetallic alloy powders that have a long range nanostructure and high surface areas. Investigations into the electrochemical preparation of the same materials showed that nanostructured bimetallic films could be obtained. Finally, the catalytic activity of mesoporous platinum and platinum/ruthenium alloys was assessed in hydrogenation reactions and in the formulation of electrodes for CO and methanol oxidation. When compared to the equivalent commercial catalysts, kinetic data for the heterogeneous reactions showed that the catalytic activity of H₁ platinum and H₁ platinum/ruthenium was significantly higher from that of the equivalent catalysts and that this difference cannot be explained only by differences in the specific surface area. Preliminary results showed that mesoporous Pt and Pt based alloys could play an important role in the development of effective catalysts for CO and methanol electrooxidation.

Activated carbons are used widely for the adsorption of environmentally unfriendly species from both liquid and gas phases, the separation of gases and adsorption of species from aqueous solution. Examples of the processes are the adsorption of Au(CN)2 and Ag(CN)2 from aqueous solution for the recovery of precious metals, the treatment of waste water containing organic chemicals and toxic metal species and the preparation of metal catalysts supported on carbon. This investigation has involved the study of the influence of porous structure and surface functional groups on the adsorption of both anionic and cationic metal species in order to understand the mechanism of adsorption of these species on active carbon from aqueous solution. Various types of oxygen functional groups were introduced onto the surface of coconut shell derived activated carbon through oxidation using nitric acid. Fourier transform infrared spectroscopy (FTIR), temperature programmed desorption (TPD) and selective neutralisation were used to characterise the surface oxygen functional groups. The oxidised carbons were also heat treated to provide a suite of carbons where the oxygen functional groups of various thermal stability were varied progressively. It was found that acidic oxygen functional groups mainly as carboxylic acid groups were incorporated into activated carbon by HNO3 oxidation. The phenol and quinone groups were also introduced by the oxidation process while the lactone groups were formed during heat treatment. The oxygen functional groups had a range of thermal stabilities with carboxylic acid groups being the least stable. A coconut shell derived active carbon was treated with ammonia and nitric acid followed by ammonia to incorporate nitrogen functional groups into the carbon. Active carbon with high nitrogen content was also prepared from nitrogen-rich precursor polyacrylonitrile (PAN). X-ray absorption near edge structure spectroscopy (XANES) and FTIR were used to investigate the structures of the nitrogen functional groups in carbons. The possible nitrogen functional groups present on carbon surface were pyridinic, pyrrolic (or indolic), pyridonic and aromatic amine-like structures. The adsorption characteristics of gold and silver cyanide anionic species on a suite of active carbons derived from coconut shell, polyacrylonitrile and chemical modification of the coconut shell carbon were investigated. The gold and silver cyanide adsorption capacities for coconut shell derived carbons correlate with total pore volume. Nitric acid oxidation treatment of the carbon was detrimental to gold adsorption in spite of the incorporation of oxygen content of carbon. The influence of nitrogen functional groups in the carbon structure on gold and silver adsorption was investigated using carbons derived from polyacrylonitrile. The addition of ethanol and butanol to the solution had an adverse effect on gold adsorption. Adsorption of silver cyanide ionic species on the active carbon was suppressed in the presence of excess free cyanide ions in solution whereas gold cyanide adsorption was not greatly affected at room temperature. The adsorption of gold cyanide was suppressed by the excess free cyanide and sodium sulphide at 70 °C. The adsorption of cadmium ions was enhanced dramatically by oxidation of the carbon. The ratio of released proton to adsorbed cadmium on oxidised carbon was approximately 2 indicating cation exchange was involved in the adsorption process. Na+ exchange studies with the oxidised carbon gave a similar ratio. After heat treatment of the oxidised carbons to remove oxygen functional groups, the ratio of H+/Cd2+ decreased significantly as well as the adsorption capacity. Both reversible and irreversible adsorption were involved in the process of cadmium adsorption with reversible adsorption having higher enthalpy. The irreversible adsorption resulted from cation exchange with carboxylic acid groups whereas the reversible adsorption probably involved physisorption of the partially hydrated cadmium ion. The nitrogen functional groups may act as ligands which can coordinate with transition metal cations. The adsorption of transition metal cations such as Cd 2+, Ni2+ and Cu2+ on active carbon was appreciably increased by the nitrogen functional groups present on carbon surface whereas ammonia treatment of the carbon showed little effect on the adsorption of alkali earth metal cation Cat+. There is little difference in the adsorption capacities of cadmium ions on coconut shell derived carbon at pH 4.1 and pH 7 whereas the adsorption of cadmium ions was significantly enhanced with increasing pH for the carbons with high nitrogen content. The nitrogen rich carbons show selectivity towards various transition metal cations reflected by adsorbing more Cu 2+ than Cd2+. This is consistent with the fact that the coordination compound of Cu 2+ with pyridine has higher stability constant than that of cadmium.

This thesis is concerned with the steering and manoeuvring of surface ships. Recent developments in hull design have seen the introduction of the pram stern. This hullform has proved less directionally stable than more conventional stern shapes. Recent theoretical developments include the effect of stern vortices in a slender-body treatment of the ships hull. The inclusion of these vortex effects explains the discrepancy between the distribution of force and moment coefficients along a hull obtained experimentally compared to those determined using slender body theory alone. As yet this approach requires the position and strength of the shed vortices to be determined by other means. The theory also offers a means of explaining the relative instability of the pram stern. An experiment has been designed to directly test some of the predictions of this theory. The experiment entailed oblique towing of a set of 7 hullforms with segmented stern sections. The first group of five models are based on the British Bombardier with a variety of conventional and pram stem configurations. The remaining models were based on a simple elliptic hullform. The experiments provide detailed data of the longitudinal distribution of force and moment sway derivatives of the stem regions of these models. The experimental evidence provided support for the theoretical predictions, although some results were inconclusive because of the effect of additional flow phenomena. The physical insight provided by the generalised slender body theory has generated the impetus to use a semi-empirical approach to predict the manoeuvring derivatives from basic hull geometry. The equations developed for the linear velocity derivatives use predictors based on the physical phenomena and are formulated to recognise the interdependency of these derivatives. The new equations are statistically more satisfactory than previous analyses of this type.

Mixed-mode chromatography is a chromatographic method in which solutes interact with stationary phase through more than one interaction mode or mechanism. It is because of these multiple complex interactions, which makes it difficult to predict chromatographic behavior of analytes on Mixed-mode columns. In order to fully understand the retention mechanisms on Mixed-mode columns, the packing material properties must be well characterized since each characteristic may contribute to the overall chromatographic performance of the column. Many non-chromatographic and chromatographic techniques are available to characterize and compare Mixed-mode columns in terms of their interaction abilities, retentivity, surface chemistry, chemical properties and geometry. Characterization of different Mixed-mode columns on the basis of interaction energy characteristics has not been explored. In this study, different ratios of porous silica (Axia Luna Silica) and C18 (Axia Luna C18), which are commonly used single mode adsorbents were blended in various ratios to simulate Mixed-mode materials and analyzed by Low Temperature Nitrogen Adsorption (LTNA). Adsorption isotherms, surface area, and BET C-Constants were obtained for all the blended materials and a linear relationship between the BET C-Constant and the blend ratio of silica has been observed. A new BET C-Constant energy scale was created from a plot of non-specified average interaction energy vs. percent silica surface. A variety of commercially available Mixed-mode columns were unpacked and the materials were analyzed by LTNA in order to explore the use of the BET C-Constant energy scale as a universal indexation system to characterize Mixed-mode materials. Adsorption isotherms, surface area, and BET C-Constants were obtained for all the commercial Mixed-mode materials. The non-specified average interaction energy and the equivalent percent silica surface was calculated from the BET C-Constant and plotted on the BET C-Constant energy scale to enable Mixed-mode column comparison based on average interaction energy. The data in this research project suggests that the BET C-Constant may be a viable parameter that can be used to characterize commercial Mixed-mode columns on the basis of average interaction energy. Utilizing this BET C-Constant energy scale in conjunction with the study of retention behaviors on Mixed-mode material could lead to improvements in the understanding of method development on Mixed-mode columns, allow the comparison and selection of commercialized Mixed-mode columns, and even predict retention behavior of analytes in Mixed-mode columns.

Functional enzymes are the basis for many biotechnological systems, including biosensors, bio-fuel cells, and heterogeneous biocatalysts. In these systems, enzymes are often immobilized on a solid support or surface to capture their catalytic activity. Immobilization has the advantage of improving enzyme stability and reusability but often results in a significant loss of catalytic activity (1-2 orders of magnitude) when compared to the native enzyme. This inactivation is due to direct interactions between the enzyme and the solid support. Here, we developed methods to study enzyme immobilization and resulting inactivation. The aim of this work was to identify optimal surface chemistries and attachment strategies that promote high binding efficiencies while minimizing activity losses. Subsequently, we studied this using three enzymes (acetylcholinesterase (AChE), β-galactosidase (β-gal), horseradish peroxidase (HRP)) immobilized on gold surfaces by direct adsorption, covalent attachment, and DNA-directed attachment. First, AChE was directly adsorbed onto a variety of gold surfaces modified with self-assembled monolayers (SAMs) terminated with -COO⁻, -NH₃⁺, -OH, and -CH₃ functional groups at varying mole % to study the effect of surface hydrophobicity and charge on binding and activity. We found that binding was directly proportional to surface hydrophobicity (r = 0.75) and activity was inversely proportional to surface hydrophobicity (r = -0.62). The highest binding observed was ~40% of a monolayer on the most hydrophobic surfaces and the lowest binding observed was ~10% of a monolayer on the most hydrophilic surfaces. Conversely, on the most hydrophobic surfaces AChE retained

Chitosan-based hydrogels are prepared via the formation of polypseudorotaxanes (PPR), by selectively threading alpha-cyclodextrin (alpha-CD) macrocycles onto polymeric chains, which, through the formation of microcrystalline domains, act as junction points for the network. Specifically, host-guest inclusion complexes are formed between alpha-CD and PEGylated chitosan (PEG-Ch), resulting in the formation of supramolecular gels. PEG-grafted chitosan is obtained with a reaction yield of 79.8%, a high degree of grafting (50.9% GW) and water solubility (approximate to 16 mg mL(-1)), as assessed by turbidimetry. A range of compositions for mixtures of PEG-Ch solutions (0.2-0.8% w/w) and alpha-CD solutions (2-12% w/w, or 0.04-0.2% mol) are studied. Regardless of PEG content, gels are not formed at low alpha-CD concentrations (

Iron speciation in solution is relatively well understood, yet interfacialdistributions of iron species are not. In the following chapters, interfacial species ofinorganic iron (III) and (II) chloride solutions at the air-aqueous interface areinvestigated. In Chapter 1, iron speciation in bulk and at the interface of salt solutions issummarized. This literature review chapter provides a background on the iron chemistry,iron complexes from speciation, difference of ion population between bulk and interface,and experimental techniques in surface studies. Chapter 2 explores the observation ofinterfacial FeCl3 species by surface sensitive spectroscopic techniques. Through a seriesof measurements, the speciation of iron (III) complexes is determined using UV/Visibleabsorption spectroscopy, comparison to calculation (ChemEQL-generated speciationcurves), and second harmonic generation (SHG) experiments. To explore the possibilityof resonant iron (III) chloro species, molar absorptivity, and dipole moment calculationswere carried out. At concentrations below 0.6 mol/kg water, SHG data of FeCl3 solutionsreveal destructive interference and a nonresonant electric-field response due to thestructural ordering effect from the [FeCl2(H2O)4]+ complex. At concentrations above 3mol/kg water, with 800 and 860 nm laser excitation, SHG response of FeCl3 showedtrends that fit to Frumkin-Fowler-Guggenheim adsorption model as opposed to theLangmuir model. With the excitation of 760 nm, the trend of SH E-field exhibited twoiiidifferent slopes. The different trend suggests the surface adsorption of [FeCl3(H2O)3]0 atthe excitation of 800 and 860 nm, where the presence of [FeCl4]- is suggested with SHGexcitation at 760 nm. However, the interfacial existence of [FeCl2(H2O)4]+ complex is notruled out. In Chapter 3, the presence of acidified FeCl2 (FeCl2-HCl) species is identifiedby a systematic study using UV/Visible absorption, Raman spectroscopy, and SHG.UV/Visible absorption spectra and speciation curves of acidified FeCl2 solutionsdetermined the existence of a dominant species in the acidified solution. Ramanspectroscopy reveals a perturbed hydrogen-bonding network of water molecule at highconcentration. In SHG measurements, the SH E-field of acidified FeCl2 solution showeda trend that follows the Langmuir adsorption model. Evaluation of the data and resonancethen suggests the presence of [FeCl(H2O)5]+ within the aqueous interface. Overall, thesestudies show that the iron (III) chloride solutions retain speciation at the air-aqueousinterface, of which adsorption of the [FeCl3(H2O)3] complex is suggested throughresonance analysis. On the other hand, SHG response of iron (II) chloride solution showsa trend that can fit to a simple Langmuir adsorption model. Our spectroscopicmeasurements suggest that [FeCl(H2O)5]+ is predominant at the solution interface, andthe higher Cl:Fe species, [FeCl2(H2O)4], is not likely formed in solution interface.

As conventional electronics approach the physical limits of size and speed, desire for more capable and energy efficient technologies has driven studies of the individual and collective behavior of electron spins within solid state materials to achieve new forms of information processing. Recent developments in this field of spintronics have led to the discovery particle-like magnetic textures called magnetic skyrmions where spins are arranged in a swirling, vortex-like pattern. To advance the understanding of materials capable of stabilizing magnetic skyrmions and the mechanisms that govern their stability and dynamical properties, we use spin-polarized scanning tunneling microscopy. The research presented here builds on the connection between the physical and magnetic structure at the surface of materials. First, we observe novel surface structures and investigate the electronic and magnetic properties of Cr(001) and Fe/Ir(111), two systems that can be used to characterize the magnetic tip of the scanning tunneling microscope. Next, we detail a technique to determine the grain structure of B20-type magnetic materials FeGe and MnGe, where the structural chirality is known to determine the chirality of the magnetic textures. The surface termination, stacking order of the layered atomic lattice, and grain chirality can all be identified by analysis of the atomic corrugation and insights from density functional theory calculations. Finally, we observe novel topological spin textures at the surface of MnGe(111). The stabilization of these is correlated to structural deformation of the film, and their three-dimensional structure is deduced based on comparison of the spin-polarized imaging with micromagnetic simulations.

Ultra-Fast Scanning Tunneling Microscopy (UFSTM) is a novel imaging technique that uses high intensity femtosecond laser light to generate atomic defect states called "traps" and provide subsequent atomic surface imaging between pulses. Many surface engineering applications are possible through femtosecond laser induced damage (fs-LID), a process where a strong non-perturbing laser electric field generates a high density of charge carriers that eventually thermalize and impart energy into a material's lattice changing the surface morphology. The number of pulses during illumination plays a large role in the resulting morphology with current theory predicting the formation of trap states in-between pulses. The trap states are too subtle to observe using traditional methods (ie. scanning electron microscopy or optical based microscopy). This thesis presents a coordinated effort in developing a novel scanning tunneling microscope system capable of detecting atomic trap states. In particular, a discussion of the instrumentation challenges associated with UFSTM techniques are presented. This work also includes a brief summary of the X-ray STM imaging technique that can also be used for elemental resolved surface imaging. The instrumentation challenges associated with coupling x-ray light with a standard STM system is included.

Understanding plant chemicals can greatly help achieve the important goals of reducing negative environmental impacts of agriculture and achieving high crop yields. One class of chemicals that has a big influence on plant health and growth is triterpenoid. However, there is a limited number of biological systems in which to study triterpenoids in detail. To increase the number of study systems, and thus our potential to build knowledge of triterpenoid function, there is a critical need to understand which triterpenoids can be found on which plant species' surface. The objective of this project was to build maps of plant surface compound presence with an emphasis on triterpenoids, using published and newly acquired gas chromatography-mass spectrometry data. The maps reveal trends that some triterpenoids are very commonly found on plant surface, while others are rare. In addition, divergent and convergent evolution traits among plants regarding their triterpenoid and other wax compounds presence were also identified.

The exact surface configuration of scandate cathodes has been a point of contention for the materials community for a long time. Without proper understanding of it and the related structures and emission mechanisms, scandate cathodes remain patchy and unreliable emitters. Thus, density functional theory techniques were applied to various potential surface arrangements and found that there are several low-energy surfaces with low work functions that incorporate a scandium interlayer between tungsten and oxygen or otherwise have a scandium-on-tungsten structure. Furthermore, it was discovered that adding a monolayer of scandium directly to a tungsten surface is surprisingly favorable, thermodynamically. While none of the test surfaces match the properties or compositions of real scandate cathode surfaces, they shine a light on the previously-unexplored phenomenon of this scandium monolayer effect which runs counter to commonly-understood metallurgical principles.

The fundamental understanding of both the reactions at catalytic surfaces and the ways in which these surfaces change throughout a catalytic cycle and lifetime are important for both academic and industrial disciplines. To develop these understandings on complex catalytic systems, ultra-high vacuum techniques such as molecular beam studies, temperature programmed desorption, reflection-absorption infrared spectroscopy and Auger electron spectroscopy can be used to study the simplest interactions between gas molecules and surfaces. These interactions can be studied from a bottom-up approach to learn about the system in question, upon which additional complexities can be added. To parallel these experimental techniques, a number of computational methods can be used to support findings and guide new experiments. Ab-initio electronic structure calculations allow for a better understanding of adsorbate-surface interactions, while long timescale dynamic simulations provide insight into the time evolution and kinetics of catalysts and catalytic surfaces. Empirical and machine-learning guided potentials can be developed to lessen computational cost while retaining accuracies comparable to ab-initio calculations. Fitting such potentials ultimately allows for larger calculations to be performed and longer timescales to be simulated. The above methods will be applied to a number of industrially and academically relevant catalytic systems, including studying the interaction of H₂ and CO with Cobalt based Fischer-Tropsch catalysts and the interaction between hydrogen and palladium surfaces. Additionally, the development of a machine learning package to fit and use interatomic potentials will be discussed.

The research work focused on examining the interfacial adhesion of unsized, epoxy, and urethane-sized textile grade carbon fiber (TCF) reinforced in different classes of polyurethane (PU) thermoplastic (TPU) and thermoset (TSU) polyurethane (PU) through the structure-property relationship. The Carbon Fiber Technology Facility (CFTF) at Oak Ridge National Laboratory (ORNL) has produced TCF to reduce the cost of commercial-grade carbon fiber. The first part of the research examined the fundamental relationships between (a) soft segment thermoplastic polyurethane (S-TPU), (b) hard segment thermoplastic polyurethane (H-TPU), (c) thermoset polyurethane (TSU) and TCF reinforcement’s molecular behavior at the interface using the surface and thermal analysis (e.g., atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA)). The results showed that S-TPU, H-TPU and TSU could produce strong interaction with urethane sizing TCF through nucleophilic addition reaction. In the second part of the research, the surface and thermal results obtained from material characterization were used to validate the interfacial adhesion of TCF-TPU and TCF-TSU composites, respectively. The mechanical properties showed that segmented TPU is compatible with epoxy-sized TCF, whereas urethane-sized TCF is compatible with the TSU system. Furthermore, the joining of dissimilar materials is a significant step to produce cost-effective automotive and aircraft components. Hence, the fusion bonding study was conducted using epoxy-sized TCF-TPU and urethane-sized TCF-TSU composites. The lap shear strength of fusion boded TCF-TSU and TCF-TPU showed 21% improvement compared to PA66/GF and epoxy/CF bonded composites. The third part of the research studied the effect of sizing thickness on composites' mechanical properties using the Dehomogenized approach. The results showed that increasing sizing thickness from 0.01 to 0.5 enhances the tensile strength by 1200% of TCF-TSU composites. The TCF and TSU properties obtained through reverse engineering mechanism further validated for the cross-ply laminate. The simulations results showed less than 10% variation in the tensile properties than experimental findings. The overall outcome of this work can advance state of the art in TCF polyurethane composites for a range of applications such as aerospace, automotive, sports, and industrial products.

The erosion prone areas on the blade surfaces of a centrifugal impeller handling granular solids have been investigated both theoretically and eperimentally. The objective of the theoretical study is to develop software to predict the erosion prone areas on the blade surfaces of a slurry handling impeller. The basic concept in the theoretical study has been to find the particle trajectories inside the impeller. The governing equations of the motion of particles within the impeller are solved in a stepwise manner with time for a given flow field. The flow field is calculated by solving the conservation equations for the flow, using a finite difference method. The number density of the particles in the cross-section of the pipe through which the particles enter the impeller is calculated by applying a discretization procedure to the insitu concentration profile of the particles. The damage to the surface caused by impacting particles is estimated by calculating the velocity and the angle at which the particles impact on a surface. The material property of the particle or the surface does not explicitly enter into calculations. It is shown that for a given combination of particles and surface material, the material property of the particles and the surface can be isolated. In this way a relative measure of the depth of volume loss at different positions of the surface can be calculated. The surface can then be divided into a number of erosion prone areas. The model is tested by undertaking a number of experiments using a commercially available slurry pump which handled a mixture of fine pea gravels in water. The predicted erosion pattern suggested the area near the leading edge to be the most erosion prone zone. The agreement with the experimental results in this respect was satisfactory. The extent of the erosion zone on the blade surface as suggested by the analytical model was in close agreement with the experimental values. The analytical model also suggested that the major part of the erosion areas would lie near the back shroud of the impeller. This was in close agreement with the experimental results.

Surfactants are extensively used as corrosion inhibitors to mitigate the internal corrosion of oil and gas pipelines. Surfactants are amphiphilic, consisting of both polar headgroup and nonpolar tail group. The arrangement of headgroup and tail group governs the adsorption as well as the inhibition process. In this dissertation, we explore the conformation of the short alkyl chain length and the nature of the headgroup of surfactants that affects on the ordering of interfacial water molecules. Quaternary ammonium compound (Quat) with five different chain lengths were synthesized via Quaternization of primary amine with Bromo alkane. Imidazolines with five different chain lengths were synthesized from fatty acid or aldehyde and amine. Aqueous solutions of Quat at different ionic strengths were studied by surface and interface selective sum frequency generation spectroscopy technique at the air-liquid interface. We found that Quat solutions containing 0%, 1%, and 10% NaCl salt showed no clear trend for the number of gauche defect as a function of ionic strength. In general, the longer chain surfactants were found to have more ordered interfacial water molecules compared to the shorter ones at the air-liquid interface. The SFG results were correlated with the surface tension measurements and pH values. As a continuation, the self-assembly of surfactant was also studied in-situ at the liquid-metal interface by SFG spectroscopy. A self-assembled monolayer at liquid-metal interface is vital for corrosion, catalysis, and electrochemical reactions. We probed the adsorption and self-assembly of Quats at the liquid-metal interface by SFG spectroscopy without applying any external potential. This provides direct evidence of the effect of alkyl chain length of surfactants in the conformational changes of an adsorbed monolayer on the liquid-metal interface. We found that longer chain surfactant forms highly ordered monolayer due to the strong tail-tail interaction. On the other hand, shorter chain surfactant forms less ordered monolayer due to weak tail-tail interaction.

Obtaining molecular-level structural information about heterogeneous catalysts and catalyst supports such as silicas and all-silica zeolites (zeosils) is critical for the rational design of new catalysts. Magnetic resonance techniques, including solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) and electron paramagnetic resonance (EPR) spectroscopies, are powerful and non-invasive tools, which were used to acquire detailed structural and dynamic information about these silica-based systems. Thermal dehydroxylation reduces the number of silanol sites on silica surfaces and is typically used to increase the fraction of non-interacting silanols for well-defined active sites, however, several studies have suggested that pairs or clusters of silanols persist even upon extreme heat treatment. The spatial distribution of these silanols was investigated using VCl4 as a paramagnetic probe molecule. EPR signals for the grafted V(IV) were absent at room temperature, but a Lorentzian lineshape characteristic of spin-spin coupled centers was observed below 20 K. The latter finding indicates strong electron spin-spin coupling and implies that the silanols are clustered. 1H double-quantum single-quantum MAS NMR also suggests that many silanols are closely spaced. Varying the V-loading combined with an analysis of the contribution of the coupled V(IV) component to the total EPR spectrum led to the finding that silanols are clustered in groups of 7 or more, and consequently cannot be described as isolated. Zeosils modified with H3PO4, referred to as P-zeosils, selectively catalyze the dehydration of biomass-derived alcohols, but are unstable in the presence of water. The nature of the active P-sites in these catalysts, and how they are impacted by water is not known. The P-site distribution in a P-modified self-pillared pentasil (P-SPP) was probed using solid-state 31P MAS NMR with frequency-selective detection, dynamic nuclear polarization-enhanced 29Si-filtered 31P detection and 31P-31P correlation experiments. The P-sites in the dehydrated material are surface-bound via hydrolytically sensitive P-O-Si linkages, while some are also oligomers containing hydrolytically robust P-O-P linkages. The P-sites evolve rapidly when exposed to water, even at room temperature. Initial cleavage of some P–O–Si linkages results in an evolving mixture of surface-bound mono- and oligonuclear P-sites with acidity due to the generation of POH groups. Eventually all are converted to H3PO4. The effect of the zeosil framework on the stability of the P-sites was determined by comparing the solid-state 31P and ultrafast 1H MAS-NMR of P-SPP to that of a hydrophobic P-modified BEA zeosil (P-BEA). P-BEA contains a higher fraction of hydrolytically-stable P-O-P bonds and a lower accessibility to water compared to P-SPP. Thus, both the water content and the framework play a role in the P-site distribution, which in turn impact the acidity and hence, catalytic activity of P-zeosils. However, elucidating the precise nature of the active P-sites under reaction conditions requires the use of operando NMR. At elevated temperatures (140 °C) and in the presence of 2-propanol, 31P and 13C operando MAS NMR spectra suggest the POH sites are converted to phosphate esters. The ability to identify acidic sites in P-zeosils, and to describe their structure and stability, by combining insights using conventional and operando NMR, will play an important role in controlling the activity of microporous catalysts.

Polymers are commonly used in applications requiring long-term exposure to water and aqueous mixtures including as medical implants, marine antifouling coatings, and water purification membranes. In all of these, the chemistry and structure of the polymer surfaces determine the effectiveness of the final material via interactions with water, dispersed solutes, and larger biomolecular structures. In the past, scientific progress has been made primarily through empirical results derived from chemically distinctive coatings and membranes, but design rules are essential for improving the rate of advancement. This work leverages a two-pronged approach for relating surface chemistry to its effects on interactions at the water–polymer surface. Design of surfaces containing sequence-defined, peptidomimetic “peptoid” side chains provides fine control over both chemistry and the relative spacing between functional groups, while self-assembled monolayers (SAMs) allow for investigation of model surfaces consisting of a single functional group with negligible surface roughness. This work also includes the development of ambient pressure X-ray photoelectron spectroscopy (APXPS) for studying the chemistry and surface interactions in hydrated polymer surfaces. First, the presence or lack of hydrogen bonding in marine antifouling coatings is found to alter both the polymer’s interactions with water and with soft algal foulers. Afterwards, the capability of side chains to present at the surface and modify polymer hydrophilicity is investigated using APXPS. Finally, the effects of functional group chemistry on the adsorption of small organic molecules are explored in APXPS experiments on model SAM surfaces. The findings of this work indicate that polymer surface chemistry can be modulated by minor changes in composition, and that these changes can have large effects on surface interactions with water, organic molecules, and organisms.

Abstract: Silicon is the foundation of the electronics industry and is now the basis for a myriad of new hybrid electronics applications, such as sensing, silicon nanoparticle-based imaging and light emission, photonics, and applications in solar fuels. From interfacing of biological materials to molecular electronics, the nature of the chemical bond plays important roles in electrical transport and can have profound effects on the electronics of the underlying silicon itself, affecting its work function, band bending, and surface dipole. When a semiconductor device becomes small (on the nanoscale), the surface:bulk ratio increases dramatically, and thus surface functionalization can dominate the electronic properties. Much attention has been focused on silicon surfaces functionalized with monolayers bound through Si–C or Si–O bonds, and experimental results have been complemented by many theoretical studies. However, the chemistry of oxygen’s chalcogenide cousins, ≡Si−E bonds (E = S, Se, and Te), has not been investigated extensively. These ≡Si−E bonds could be of significance because the additional electronic states for the heavier atoms (Te versus Se versus S versus O) can affect electron transfer to and from molecules attached to a silicon surface. Furthermore, as is seen in the case of molecular silane chemistry, the chemistry of organochalcogenides on silicon surfaces could offer a variety of reactivity. This dissertation is focused on the formation of Si–E bonds on silicon surfaces via the reaction of hydride-terminated porous or flat silicon with dichalcogenides, the investigation of the mechanism of the reaction, and the quantification of the substitution level. Hydride-terminated porous Si(100) surfaces were reacted first with a range of organochalcogenide reagents, including di-n-butyl disulfide, di-t-butyl disulfide, di- n-octadecyl disulfide, diphenyl disulfide, diphenyl diselenide, diphenyl ditelluride, and bis(4-chlorophenyl) disulfide, through fast microwave heating (10–15 s) or direct thermal heating (hot plate, 2 min), resulting in the formation of ≡Si−E bonds with low levels of oxidation. The research was followed by the second type of reaction between hydride- terminated flat Si(111) surfaces and dichalcogenides under UV irradiation accompanied by mild heating for 15 min. The mechanism of both types of reactions appears to be radical in nature, involving surface silyl radicals or dangling bonds that react with either the alkyl or aryl dichalcogenide directly or with their homolysis products, the alkyl or aryl chalcogenyl radicals. For the functionalized flat Si(111) surfaces, the coverage and electronic properties were investigated as well. The substitution level of the phenyl chalcogenide derivatives (≡Si−E−Ph) was lower than that of the aliphatic chalcogenide (≡Si−S−n-octadecyl) group, most likely due to the fact that the phenyl group blocks the surface Si–H groups and thus sterically prevents them from reacting. The XPS- and UPS-determined electronic properties of ≡Si−E−Ph surfaces, including surface dipoles and work function, did not change significantly compared to those of the starting ≡Si−H surface maybe due to the low level of substitution. The series of chalcogen–silicon bonds, from Si–O, to Si–S, to Si–Se, and now to Si–Te, can be accessed easily and applied to a variety of electronic applications on this semiconductor. The comparison of the errors in estimating the substitution level using the ratio of carbon to silicon versus the ratio of heteroatom to silicon was discussed. It is found that the usage of heteroatoms (F and S) as atomic tags will reduce the error by an order of magnitude in the quantification of the substitution level that resulted from the effect of adventitious carbon.

Minority carrier lifetime is a commonly mentioned metric when characterizing semiconductor materials and Infrared devices. More specifically, the minority carrier lifetime is perhaps the most important metric when examining the quality of these various as-grown materials. The reasoning behind this lies in the precise, accurate, and non-destructive nature of minority carrier lifetime extraction as it pertains to sample quality. Through a combined effort of both stimulating a device to produce carriers and examining the rate at which these carriers recombine, the rate of recombination can be extracted to better expose properties of the examined sample. For these reasons, the importance of understanding how sample characteristics and topologies change the minority carrier lifetime cannot be understated. It is important to note that carrier lifetime is not one metric but rather a combination of various recombination mechanisms making individual characterization quite difficult. The objective of this thesis was to investigate if the temporal decay of the microwave reflectance could be used to measure difference between mesa-etched and as-grown samples. This data was collected and visualized through modeling to then allow inferences and conclusions to be proposed concerning the dependencies of the various lifetime mechanism apparent in the sample. Through modeling, the different recombination mechanisms at play could be separated and analyzed in an effort to understand how lifetime dependencies change and interact with each other depending on the sample topology, temperature, and laser fluence, in the experiment performed. The key result was that at T=20K, one of the lifetime dependent data sets of the microwave decay increased noticeably in the as-grown sample especially when compared to the unpassivated mesa sample. The same lifetime dependent data decreased in the passivated sample potentially showing successful surface lifetime dependency. This opens the possibility of using microwave reflectance to measure the properties of surfaces.

The surface of a semiconductor often has a key role in determining its properties. For metal halide perovskites, understanding the surface features and their impact on the materials and devices is becoming increasingly important. At length scales down to the nanoscale regime, surface features become dominant in regulating the properties of perovskite materials owing to the high surface-to-volume ratio. For perovskite bulk films in the micrometer range, defects and structural disorder readily form at the surface and affect device performance. Through concerted efforts to optimize processing techniques, high-quality perovskite thin films can now be fabricated with monolayer-like polycrystalline grains or even single crystals. Surface defects, therefore, remain the major obstacle to progress, pushing surface studies to the forefront of perovskite research. Hence, research towards fundamental understanding of perovskite surfaces and how they can affect the materials properties is crucial to further improving the perovskite-based optoelectronic devices.In Chapter 2, surface energies will be shown to play an important role in affecting the phase stability of perovskite materials. Thermodynamic and crystallographic analyses revealed that enhanced contribution of the surface energy and lattice contraction contribute to the superior stability of colloidal quantum dots (CQDs). This approach provides a new route for achieving stable formamidinium lead iodide (FAPbI3) perovskite solar cells. Later on, in Chapter 3, a conjugated small molecule ITIC was introduced into the FAPbI3 CQDs perovskite solar cells to further enhance the power conversion efficiency of the devices.In Chapter 4, I will show that in lead halide perovskites, how their “soft” nature renders them highly responsive to the external field, allowing for extended depth scale affected by the surface. By taking advantage of this unique feature of perovskites, I demonstrate a methodology for property manipulation of perovskite thin films based on secondary grain growth, where tuning of the surface induces the internal property evolution of the entire perovskite film. While in conventional microelectronic techniques secondary grain growth generally involves harsh conditions such as high temperature and straining, it is easily triggered in a perovskite thin film by a simple surface post-treatment, producing enlarged grain sizes of up to 4 μm. The resulting photovoltaic devices exhibit significantly enhanced power conversion efficiency and operational stability over a course of 1000 h and an ambient shelf stability of over 4000 h while maintaining over 90% of its original efficiency.Surface trap-mediated non-radiative charge recombination is a major limit to achieving high-efficiency metal-halide perovskite photovoltaics. The ionic character of perovskite lattice has enabled molecular defect passivation approaches via interaction between functional groups and defects. However, a lack of in-depth understanding of how the molecular configuration influence the passivation effectiveness is a challenge to rational molecule design. In Chapter 5, the chemical environment of a functional group that is activated for defect passivation was systematically investigated with theophylline, caffeine and theobromine. When N-H and C=O were in an optimal configuration within the molecule, hydrogen-bond formation between N-H and I assisted the primary C=O binding with the antisite Pb defect to maximize surface-defect binding. A stabilized power conversion efficiency of 22.6% of photovoltaic device was demonstrated with theophylline treatment.

All surfaces generate electric-field noise, yet the physical origins of this noise are not well understood. This has been an active area of research in the ion trapping community for the past two decades, as ions are highly sensitive to electric-field fluctuations. With our work, we aim to illuminate the microscopic processes that drive charge dynamics on metal surfaces, so as to enable the engineering of low noise quantum devices. We use single trapped calcium ions as detectors to study the 1/f noise generated by the surfaces of ion traps. We the study this noise by observing how it responds to changes in the properties of the trap surface. The surface properties are altered using treatments including prolonged heating, argon ion milling, and electron bombardment. In situ characterization tools are used to monitor the effects of these treatments. Our measurements are consistent with noise produced by an ensemble of thermally activated fluctuators, so our data is discussed in this context. In this dissertation, we present results from a lengthy series of surface treatment experiments, the majority of which took place on a single aluminum-copper substrate. The results of these experiments indicate that argon ion milling can lower noise both by removing contaminants and by altering the morphology of the trap surface. The effects of morphology are isolated from the effects of contaminant removal via heat treatments, which alter the structure of the surface without changing its chemical composition. Through electron bombardment experiments, we begin an exploration of the relationship between hydrocarbon adsorbate structure and electric-field noise. In addition, we compare the noise characteristics of a set of similarly fabricated traps, and determine that atmosphere exposure has a major impact on noise produced by aluminum-copper films.These experiments establish links between the electric-field noise characteristics and the microscopic properties of a contaminated metal trap surface. The insights we draw in this work can inform the next generation of ion trap engineering, storage, and treatment.