Osseointegration, or the direct integration of an implant into bone tissue, is necessary for implant success. Titanium is commonly used clinically in dental and orthopaedic implants because of its passivating oxide layer, which facilitates osseointegration, and its mechanical properties such as a modulus of elasticity similar to bone. Diverse studies have shown that surface microtopography, chemistry, and surface energy affect osteoblast behavior. The problem with these studies is that they access the average behavior of a culture in response to a substrate and not the behavior of individual cells. The objective of this study was to develop a method for correlating the behavior of individual cells with the characteristics of the surface underneath them. More specifically, this work developed a method to correlate integrin beta-1 (β1) expression with the surface characteristics under individual cells. Integrins are cell surface receptors that bind to specific proteins in the extracellular matrix adsorbed on the implant surface. Previous work has shown that expression of certain integrins is increased when osteoblasts on titanium substrates develop a more differentiated phenotype, and that integrin β1 is necessary for osteoblast response to roughness on titanium substrates. This study used molecular beacons specific to integrin β1 to quantify integrin β1 expression of MG63 cells cultured on titanium disks. A template was designed to coordinate the location of cells using fluorescence microscopy and scanning electron microscopy (SEM) in reference to laser etchings on the disks. After live cell imaging, cells were fixed, dried, and critical point dried for focused ion beam (FIB) milling. Transmission electron microscopy (TEM) sections of cells identified with high and low integrin β1 molecular beacon intensity were milled, and cells with high and low integrin β1 molecular beacon intensity were also serial sectioned. While our TEM results were inconclusive, SEM images from serial sectioning showed contact points between the cell body and the substrate, consistent with previous results. Cells cultured on pretreatment (PT) or sandblasted acid etched (SLA) titanium surfaces were also serial sectioned, showing that cells on SLA surfaces have more regions of contact between the cells and the substrate than cells on PT surfaces. This work is significant as it is the first study to develop a method to correlate individual cell behavior with the substrate surface characteristics under the individual cells. Previous studies have reported the average cell behavior in response to their substrates, while this work allows for the study of substrate surface characteristics that positively affect integrin β1 expression in individual cells. Further optimization of the fluorescence imaging process and FIB milling process could be done, and the method developed in this study could be used in future studies to investigate surface characteristics after using other fluorescent analyses of cell behavior, such as immunocytochemistry.

Two multiscale continuum models for simulating protein dynamics are developed which allow for resolution of protein peptide planes in a beam-like finite element. A curvature and strain based finite element formulation is utilized. This formulation is advantageous in simulating proteins since amino acid chains may be described by a single element, even when the protein segment considered exhibits large curvature and twist such as the alpha-helical shapes prominent in many proteins. Specifically, concurrent and hierarchical multiscale models are developed for the curvature and strain based beam formulation. The hierarchical multiscale continuum model utilizes a novel shooting method to calculate the deformed configuration of the protein. An optimization algorithm determines the requisite stiffness parameters by varying the beam stiffness used in the shooting method until deformed configurations of test cases correspond to those produced by the LAMMPS molecular dynamics software. Additionally, a concurrent multiscale method is detailed for evaluating protein inter-atomic potential parameters from the curvature and strain degrees of freedom employed in the model. This allows internal forces and moments to be calculated using nonlinear protein potentials. Proof of concept testing and model verification for both models includes comparing the multiscale techniques to all-atom molecular dynamics solutions. Specifically, the models are verified by simulating a polypeptide in a vacuum and comparing the predicted results to those computed using LAMMPS.

In modern times, the ability to investigate the aeroelastic behavior of dynamic components on rotorcraft has become essential for the prediction of their useful fatigue life. At the same time, the aeroelastic modeling of a rotorcraft is particularly complex and costly. Inaccuracies in numerical predictions are mostly due to imprecisions in the structural modeling, to the presence of structural degradation or to the limited information on aerodynamic loads. The integration of experimental measurements on dynamic components such as rotor blades has the potential to improve fatigue estimation, augment the knowledge of the dynamic behavior and inform numerical models. The objective of this research is the development of a combined numerical and experimental approach, named Confluence Algorithm, that accurately predicts the response of dynamic components with a limited set of experimental data. The integration of experimental measurements into a numerical algorithm enables the continuous and accurate tracking of the dynamic strain and stress fields. The Confluence Algorithm systematically updates the numerical model of the external loads, and mass and stiffness distributions to improve the representation and extrapolation of the experimental data, and to extract information on the response of the system at non-measured locations. The capabilities of this algorithm are first verified in a numerical framework and with well-controlled lab experiments. Numerical results from a comprehensive UH-60A multibody model are then compared with available experimental data. These analyses demonstrate that the integration of the Confluence Algorithm improves the accuracy of the numerical prediction of the dynamic response of systems characterized by a periodic behavior, even in presence of non-linearities. The algorithm enables the use of simplified models that are corrected through experimental data to achieve accurate tracking of the system.

In-beam Positron Emission Tomography (PET) is a system for monitoring high precision radiation therapy which is in the most cases applied to the tumors near organs at risk. High quality and fast availability of in-beam PET images are, therefore, extremely important for successful verification of the dose delivery. Two main problems make an in-beam PET monitoring a challenging task. Firstly, in-beam PET measurements result in a very low counting statistics. Secondly, an integration of the PET scanner into the treatment facility requires significant reduction of the sensitive surface of the scanner and leads to a dual-head form resulting in imaging artifacts. The aim of this work is to bring the imaging process by means of in-beam PET to optimum quality and time scale. The following topics are under consideration: - analysis of image quality for in-beam PET; - image reconstruction; - solutions for building, testing, and integration of a PET monitoring system into the dedicated treatment facility.

The rapid growth of the microelectronics industry in the last decades made it possible to produce structures in the sub-micrometer scale on silicon chips and to reach an integration scale under 100 nm. Decreasing the size and increasing the complexity of these structures make a control of quality and defects investigation more difficult. During a long time ultrasound devices are being used for nondestructive investigation of materials, like ultrasound microscopes, scanning photo-acoustic microscopes or scanning electron-acoustic microscopes, where acoustic waves are generated by acoustic transducers, focused laser or electron beams, respectively. The aim of this work is to investigate more precisely the acoustic wave generation by pulsed and periodically modulated ion beams in different solid materials depending on the beam parameters and to demonstrate the possibility to apply an intensity modulated focused ion beam (FIB) for acoustic emission and for nondestructive investigation of the internal structure of materials on a microscopic scale. The combination of a FIB and an ultrasound microscope in one device can provide the opportunity of nondestructive investigation, production and modification of micro- and nanostructures simultaneously. The FIB spot size in modern systems is comparable with that of a focused electron beam and the penetration depth of ions with energy of 20-60 keV is lower than 100 nm. This makes it possible to reach a sub-micrometer resolution of a scanning ion acoustic microscope. On the other hand side a FIB with energy of 20-60 keV is a good tool which can be used for the fabrication of nanostructures using ion milling, implantation or ion beam assisted deposition techniques. The bulk ultrasound emission in a solid was investigated using a pulsed high energy ion beam focused on aluminum, copper, iron and silicon samples. Oxygen, silicon and gold ion beams were applied in charge states from 1+ to 4+ with the pulse duration of 0.5 - 4 µs and an energy of 1.5 - 10 MeV. Intensity of the detected acoustic waves shows a linear dependence on the energy of the incident ions, on the ion flux as well as on the pulse duration. No influence of the ion charge and ion mass to the emission of acoustic waves was observed. The ion acoustic effect was applied for a nondestructive material inspection using intensity modulated FIB providing by the IMSA-100 FIB system with an accelerating potential of 30-35 kV. The achieved lateral resolution of this scanning ion acoustic microscope is in the micrometer range depending on the sample material and the beam modulation frequency. The resolution can be improved by increasing the frequency. The maximal modulation frequency which was obtained at IMSA-100 is about 2 MHz corresponding to lateral resolution of 4-5 µm on silicon. Using this microscope, some images of integrated microstructures on a silicon chip were obtained using the lock-in technique for filtering of the signal from the noise and increasing of the total imaging time. The possibility to visualize near sub-surface structure was demonstrated. Due to the strong sputtering effect and the long time of irradiation the imaged structures were significantly damaged. Si2+, Ge2+, Ga+ and Au+ ions were used. All these ions are quite heavy and have high sputtering coefficients. Long-time imaging improves the quality of acoustic images, i. e. the signal-to-noise ratio is reduced with the square root from the pixel time, but leads to significant erosion of the imaged structure.

Beam dumps are installed at the experimental areas of the ELBE facility. Their purpose is to absorb the primary electron beam and the secondary radiation. The beam dump consists of a purified graphite core inside a water cooled stainless steel vessel. The radiation shield surrounding the beam dump will be designed individually for each experimental area. In this context, dose rate calculations were carried out to estimate the dose rate source term around the stainless steel vessel of the beam dump. Detailed Monte Carlo simulations were carried out using the code FLUKA. The energy dependent photon and neutron fluences and the equivalent dose rates were obtained near the surface of the cylindrical steel vessel for a beam current of 1 mA and energies of 20 MeV and 50 MeV.

The formation of Ge nanowires in V-grooves has been studied experimentally as well as theoretically. As substrate oxide covered Si V-grooves were used formed by anisotropic etching of (001)Si wafers and subsequent oxidation of their surface. Implantation of 1E17 Ge+ cm^-2 at 70 keV was carried out into the oxide layer covering the V-grooves. Ion irradiation induces shape changes of the V-grooves, which are captured in a novel continuum model of surface evolution. It describes theoretically the effects of sputtering, redeposition of sputtered atoms, and swelling. Thereby, the time evolution of the target surface is determined by a nonlinear integro-differential equation, which was solved numerically for the V-groove geometry. A very good agreement is achieved for the predicted surface shape and the shape observed in XTEM images. Surprisingly, the model predicts material (Si, O, Ge) transport into the V-groove bottom which also suggests an Ge accumulation there proven by STEM-EDX investigations. In this Ge rich bottom region, subsequent annealing in N2 atmosphere results in the formation of a nanowire by coalescence of Ge precipitates shown by XTEM images. The process of phase separation during the nanowire growth was studied by means of kinetic 3D lattice Monte-Carlo simulations. These simulations also indicate the disintegration of continuous wires into droplets mediated by thermal fluctuations. Energy considerations have identified a fragmentation threshold and a lower boundary for the droplet radii which were confirmed by the Monte Carlo simulation. The here given results indicate the possibility of achieving nanowires being several nanometers wide by further growth optimizations as well as chains of equally spaced clusters with nearly uniform diameter.

In this conceptual report the idea to establish an European Positron Source for Applied Research ("EPOS") based on new LINAC facilities in Germany (ELBE/Rossendorf or TTF-DESY/Hamburg) is considered. The report contains not only the outline of obvious applications in atomic physics, materials science and surface physics, but also several new methodical developments which are only possible with an intense positron beam. This opportunity will also allow the use and further development of imaging techniques being of special interest for industrial applications.

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<p>This report investigates the feasibility and accuracy of determining fastener flexibility with 3D FE and representing fasteners in FE load distribution models with simple elements such as springs or beams. A detailed study of 3D models compared to experimental data is followed by a parametric study of different shell modelling techniques. These are evaluated and compared with industry semi-empirical equations.</p><p>The evaluated 3D models were found to match the experimental values with good precision. Simulations based on these types of 3D models may replace experimental tests. Two different modelling techniques were also evaluated for use in load distribution models. Both were verified to work very well with representing fastener installations in lap-joints using the ABAQUS/Standard solver. Further improvement of one of the models was made through a modification scale factor. Finally, the same modelling technique was verified using the NASTRAN solver.</p><p>To summarize, it is concluded that:</p><p>• Detailed 3D-models with material properties defined from stress-strain curves correspond well to experiments and simulations may replace actual flexibility tests.</p><p>• At mid-surface modelling of the connecting parts, beam elements with a circular cross section as a connector between shell elements is an easy and accurate modelling technique, with the only data input of bolt material and dimension.</p><p>• Using connector elements is accurate only if the connecting parts are modelled in the same plane, i.e. with no offset. Secondary bending due to offset should only be accounted for once and only once throughout the analysis, and it is already included in the flexibility input.</p>