Graphene is one of the most popular material due to its promising properties, for instance electronics applications. Graphene films were grown on silicon carbide (SiC) substrate using chemical vapor deposition (CVD). Influence of the deposition temperature on the morphology of the films was investigated. Characterizations were done by reflectance mapping, atomic force microscopy and Raman spectroscopy. Two samples were done by sublimation process, to compare the number of layers and the morphology of the graphene films with the one grown by chemical vapor deposition.The reflectance mapping showed that the number of layers on the samples made by CVD was notinfluenced by the deposition temperature. But also, demonstrated that sublimation growth is present in allthe samples due to the presence of silicon coating in the susceptor. The growth probably started by sublimation and then CVD deposition. The step morphology characteristic of the silicon carbide substrate surface was conserved during the deposition of graphene. But due to surface step bunching, a decrease inthe step height occurred and the width of the terraces increased. The decreasing in deposition temperature leads to a smoother surface with the CVD method. Raman spectroscopy confirmed the presence ofgraphene and of the buffer layer characteristic of the sublimation growth. Moreover, it demonstrated the presence of compressive strain in the graphene layers.

Caveolae are a type of invaginated membrane domain that has been shown to be involved in several disease states, including lipodystrophy, muscular dystrophies and cancer. Several of these diseases are caused by the lack of caveolae or caveolae-related signaling deficiencies in the tissues in which the caveolar domain are abundant such as lung, adipose, muscle and their related endothelial cells. Caveolae are formed through the assembly of the membrane inserted protein caveolin, cholesterol and the recently described family of cavin proteins, which together form the caveolae coat. The work in this thesis focuses on understanding the protein components and mechanisms that control the biogenesis and dynamics of caveolae. We have found that the protein EHD2 is an important regulator and stabilizer of the caveolar domain at the cell membrane. EHD2 is a dimeric ATPase known to oligomerize into ring-like structures around lipid membranes to control their shape. We have characterized the domain interactions involved in the specific targeting and assembly of this protein at caveolae. We propose a stringent regulatory mechanism for the assembly of EHD2 involving ATP binding and switching of the EH domain position to release the N-terminus and facilitate oligomerization in the presence of membrane species. We show that loss of EHD2 in cells results in hyper- dynamic caveolae and that caveolae stability at the membrane can be restored by reintroducing EHD2 into these cells. In a study of the protein cavin-3, which is known to be an integral component of the caveolar coat, we showed that this protein is targeted to caveolae via direct binding to the caveolar core protein caveolin1. Furthermore, we show that cavin-3 is enriched at deeply invaginated caveolae and regulate the duration time of caveolae at the cell surface. In combination with a biochemical and cellbiological approach, the advanced fluorescence microscopy techniques, like Fluorescence Recovery After Photobleaching (FRAP), Total Internal Reflection microscopy (TIRF), combined with correlative Atomic Force Microscopy (AFM) have allowed us to characterize distinct caveolae-associated proteins and their respective functions at caveolae.

Retirement is an unavoidable and necessary phase in a person’s life. It is also one of the biggest transitions in the life cycle of a human being. Emeritus of the Apostolic Faith Mission of S.A. (AFM) have positive and negative feelings regarding their retirement. In the light of this fact the research question was posed: How can the AFM, from a pastoral perspective, understand the situation of, prepare and assist its emeritus in coping effectively with retirement - in the process addressing their holistic needs - maintaining a meaningful life in the service of God as integral members of His community? With reference to the abovementioned question it is the overall aim of this study to research the holistic needs of the pastors of the AFM, with the objective to create a pastoral model for retirement preparation. In so doing they can remain integral members of God`s community whose holistic needs are taken care of, in a Christian way. The study was done by using the practical-theological model of Osmer as starting point which comprises the following: * the normative task, where Scriptural perspectives on the topic have been researched; * the interpretative task, according to which material from other disciplines are studied; * an empirical research by way of interviews with emeritus; * and a practice theory to design a model for pre-retirement planning for pastors of the AFM. The normative task part of the research indicates that although the Bible does not say much regarding emeritus, definite direction is found regarding old age. God speaks through, and gives direction in his Word concerning the elderly. In the interpretative task part of the study very little literature is found regarding the retirement of clergy. Information exists, however, on the subject of the elderly. Numerous guidelines are also found in Scripture a propos the pastors as a holistic person in connection with body, soul and spirit. Research indicated that preparation for retirement is of cardinal importance. The results which surfaced from the empirical study, confirmed the normative and interpretative theoretical research. Subsequently the practice theory has been formulated from the hermeneutical interaction of the different elements of the research in the format of a model for pre-retirement planning. A model where the strategy for planning has been explained has been compiled finally. Matters related to the problems and fears of emeritus were addressed in creating a model. The intention of the pre-retirement education is to reduce the effect of negative stereotypes of retirement. It will further assist pastors to develop realistic goals for their retirement. With reference to the research question, central theoretical argument and the research reflected in chapters 2 to 5, the final conclusion states that pre-retirement planning for pastors of the AFM is very important. / PhD (Pastoral studies), North-West University, Potchefstroom Campus, 2014

Kaskadinė fermentinė reakcija yra tokia cheminių reakcijų grandinė, kai vienos fermentinės reakcijos produktas yra panaudojamas kitose fermentinėse reakcijose tol, kol gaunamas galutinis rezultatas. Tokių reakcijų pavyzdžiai gamtoje yra kraujo krešėjimo reakcija, celiulozės skaidymas bei signalų perdavimas neuronuose. Norint, kad kaskadinė fermentinė reakcija vyktų efektyviai, fermentai, reikalingi reakcijai vykti, turi būti išsidėstę taip, kad po kiekvieno reakcijos etapo tarpinis produktas efektyviai pasiektų kitą reakcijai reikalingą fermentą. Tokių reakcijų efektyvumą galima bandyti pagerinti sutelkiant visus reikalingus reakcijai fermentus šalia vienas kito. Vienas iš variantų kaip būtų galima sukurti daugiafermentį kompleksą yra panaudojant segmentuotus metalinius nanostrypelius kaip koduojančią matricą bei genetiškai modifikuotas fermentų molekules. Prie fermentų molekulių būtų prijungiamos dideli giminiškumą reikalingam nanostrypelio metaliniam segmentui turinčios oligopeptidinės uodegėlės, kurios sukurtų sąlygas fermentams savaime organizuotis ant segmentuoto nanostrypelio paviršiaus. Magistrinio darbo užduotys buvo charakterizuoti susintetintus nanostrypelius, patikrinti ar modifikuotas giminiškomis sidabrui peptidinėmis uodegėlėmis streptavidinas sugeba prisijungti biotiną bei palyginti modifikuoto ir ir nemodifikuoto streptavidino giminiškumą sidabro paviršiui. Atlikus eksperimentus buvo nustatyta, kad naudojantis atominės jėgos mikroskopija nepavyko patikimai... [toliau žr. visą tekstą] / Biochemical enzyme cascade is a series of chemical reactions in which the products of one reaction are consumed in the next reaction. If one could organize all the necessary enzymes for the reaction in close quarters this could possibly lead to more effective cascade reactions. One way of organizing enzymes is by fusing them on barcoded nanowire matrices. This could be achieved by tayloring enzyme molecules with genetically engineered proteins for inorganics (GEPIs). My assignment was to characterise possible nanowire candidates for these biohybrid complexes using AFM and examine silver binding characteristics of GEPI taylored streptavidin using SERS. I could not realiably characterise nanowires because the interaction between AFM probe and nanowires was to interfering. Also the nanowires used to aggregate and it was difficult to separate them using ultrasound. 15nm diameter nanowires aggregated more thant 30nm diameter nanowires. Streptavidin taylored with Ag binding GEPIs showed stronger interaction with Ag electrode surface than ordinary streptavidin. Also this modified streptavidin was capable of binding with biotin. This proves that added oligopeptide chains did not negatively affect the chemical structure of streptavidin.

We introduce a sensor which uses phase shifted dual diffraction gratings in order to increase the detectable range of motion when using phase sensitive diffraction for optical detection of displacement in probe microscopy. The modified FIRAT structure is comprised of a micro-machined bridge structure with integrated diffraction gratings for use in optical detection. With this new design and modified geometry/fabrication process, we will demonstrate force sensing structures with improved displacement detection range and dynamic response. The structure is based upon a previous implementation of force sensor modified for use in AFM imaging. It is built upon a transparent substrate and the bridge / grating serve as an integrated electrostatic actuator. The previously introduced an AFM sensor structure, with integrated actuator, can feasibly obtain Pico Newton force resolution along with increased bandwidth. The advantages of the integrated phase-sensitive diffraction grating and electrostatic actuator over other cantilever based implementations are well developed, yet the FIRAT structure suffered from limited displacement detection range of about ë/4 (167.5 nm for ë = 670 nm), its dynamics were dominated by squeeze film damping and the stiffness was not suitable for many imaging applications. This limitation in range was not due to the device physical structure or actuator, but was inherent to the optical detection scheme used. Modifications to the previous structure design, and sensor detection scheme, are implemented in order to increase the detectable range of the sensor implementation, reduce damping and stiffness, and custom tailor our devices to imaging applications

Hornification is the term used to describe the irreversible changes that occur in cellulose fibers due to recycling. While the effects of hornification have been documented, there are several conflicting hypotheses that attempt to explain the causes. In this research, AFM surface adhesion measurements made on virgin and recycled bleached kraft pulp show that recycling increases the apparent hydrophilicity of the fiber surface. Yet, the water retention values and tensile strength decrease as expected, which is consistent with internal cross-linking of the bonding sites and a reduction in hydrophilicity. Recycling does not affect the amount of monolayer water bound to the fiber surface indicating that the pore water is reduced but not the water bound to fiber surfaces. It is proposed that the contact area between the AFM tip and the fiber is greater for recycled material than for virgin. Image analysis of the fiber surface supports this conclusion, revealing a decrease in the surface roughness. The irregularity of fiber surfaces is apparent in AFM images at all but the smallest scales, with macroscopic fiber features dominating the roughness analyses of images larger than 2500 square nanometers. Hence, in this instance, the surface adhesion values are more a measure of the topography of the surface than of its chemistry. An application to newsprint is illustrated, revealing the limitations of AFM analysis of samples with a high degree of variability.

Esta tesis doctoral tiene como objetivo general el estudio de los procesos de agregación de porfirinas sulfonadas amfifílicas. En el primer capítulo se presentan los trabajos dirigidos a la obtención de porfirinas sulfonadas, necesarias para los objetivos generales de este trabajo. Se ha descrito una nueva vía de sulfonación de 5,15-difenilporfirina que únicamente tiene lugar en presencia de SO3 libre y que proporciona la sulfonación en las posiciones meso.En el segundo capítulo se describen los resultados obtenidos en el estudio de la homoasociación de porfirinas sulfonadas solubles en agua, objetivo principal de este trabajo. La mayor parte de este capítulo corresponde al estudio de la 5,10,15,20-tetraquis(4-sulfonatofenil)porfirina (H4TPPS4) y la 5-fenil-10,15,20-tris(4-sulfonatofenil)porfirina (H3TPPS3). Estas porfirinas han sido obtenidas por primera vez en forma de ácido sulfónico para estudiar la importancia de la naturaleza de los contracationes en el proceso de homoasociación. El valor de pKa(1/2) estimado para estas porfirinas no difiere significativamente respecto al valor descrito previamente para sus respectivas sales sódicas. En cambio, la evolución en agua pura de la homoasociación de H4TPPS4 y H3TPPS3 es mucho más lenta que la de sus respectivas sales sódicas (Na4TPPS4 y Na3TPPS3). Además, los ácidos sulfónicos H4TPPS4 y H3TPPS3, al contrario que sus respectivas sales sódicas, interaccionan con las paredes de los recipientes de vidrio neutro, vidrio Pyrex y cuarzo. En estado sólido, se observa que cuando hay presente una cantidad de H2O menor que la requerida para estabilizar los J-agregados, H4TPPS4 y H3TPPS3 se estabilizan intermolecularmente lado-a-lado, pero formando agregados de menor extensión. Se han estudiado los agregados de estas porfirinas mediante AFM. Las mesofases de H4TPPS4 son cintas que con el tiempo sólo aumentan su longitud pero mantienen una anchura uniforme dentro de un rango relativamente estrecho (35 nm - 60 nm) y un espesor constante de 3,2 nm. En cambio para la H3TPPS3 en un primer estadio se observan cintas rectas, de anchura similar (35 nm - 80 nm) y de espesor igual que las de H4TPPS4, que evolucionan con el tiempo plegándose espontáneamente. Hemos propuesto un modelo de bicapa para los agregados de ambas especies que difieren en la naturaleza de su interficie, iónica para los homasociados de H4TPPS4 e hidrofóbica para los de H3TPPS3. También se ha estudiado la influencia de las fuerzas hidrodinámicas generadas al agitar soluciones agregadas de HnTPPSn (n= 3, 4). En el caso de H4TPPS4 la agitación provoca la ruptura mecánica de los agregados y en el caso de H3TPPS3, acelera el proceso de plegamiento y fomenta la formación de estructuras plegadas. Uno de los resultados más importantes de este trabajo es que la agitación de soluciones concentradas recién preparadas de H3TPPS3 permite la selección estadística del signo de quiralidad de las bandas de DC según el sentido de agitación utilizado. En la parte final de este segundo capítulo se presentan resultados del trabajo realizado en la Universidad de Catania, que muestran cómo la jerarquía de las distintas etapas de agregación de estas porfirinas permite controlar la formación de determinadas estructuras supramoleculares. El autoensamblaje de Na4TPPS4 muestra una influencia jerárquica del orden de adición NaCl/porfirina en su comportamiento de agregación. Para [Na4TPPS4]final < 3 microM, la adición del NaCl antes que la porfirina muestra la aparición de J-agregados mientras que al adicionar primero la porfirina estos no se detectan.Por último, en el capítulo tercero, se estudia por AFM la formación de monocapas de monoestearato de glicerilo sobre grafito. Se pudo demostrar que en el proceso de autoensamblaje bidimensional de la especie racémica sobre el sustrato de grafito tiene lugar una ruptura espontánea de la simetría especular. / Self-assembly processes of amphiphilic porphyrins are receiving increasing interest because of the possibility to obtain Supramolecular structures with defined geometries. One of the primary goals of this thesis has been to obtain for the first time the 5,10,15,20-tetrakis(4-sulfophenyl)porphyrin (H4TPPS4) and the 5-phenyl-10,15,20-tris(4-sulfophenyl)-porphyrin (H3TPPS3) as pure sulfonic acids. The study of these porphyrins allows a better understanding of the importance of the nature of the counterions in aggregation processes. These porphyrins, as pure sulfonic acids, aggregate slower than their sodium salts and, unlike those, interact with glass and quartz surfaces. Freshly prepared H4TPPS4 and H3TPPS3 homoassociates show similar shapes: straight tapes with a 3,2 nm constant height, widths of 35-80 nm, and lengths of 200-800 nm. The aggregates evolve with time increasing their lengths but maintaining similar widths and the same height, H4TPPS4 aggregates remain straight, but those of H3TPPS3, on the contrary, begin to fold spontaneously. We have proposed a bilayer model for H4TPPS4 and H3TPPS3 aggregates. For the former ones this implies the existence of an ionic interaction between the two layers and for the latter ones a hydrophobic one.The influence of hydrodynamic forces generated by stirring aggregated solutions of HnTPPSn (n = 3, 4) has also been studied. In the case of H4TPPS4, stirring causes the mechanical rupture of the aggregates and, in the case of H3TPPS3, accelerates the process of folding and promotes the formation of folded structures. One of the most important conclusions of this work is that the stirring of H3TPPS3 freshly prepared concentrated solutions allows statistical selection of the chiral sign of the DC bands according to the stirring sense.The work performed at the University of Catania shows how the hierarchy of the various stages of aggregation of these porphyrins allows the control of the formation of certain supramolecular structures. The self-assembly process of Na4TPPS4 shows a hierarchical dependence on the addition order of NaCl / porphyrin. Finally, we have studied the formation of 1-monostearoylglycerol monolayers on graphite by AFM. We show that in the two-dimensional self-assembly process of this racemic substance on graphite there is a spontaneous breaking of mirror symmetry.

In considering the concept of surface-immobilised liposomes as a drug release system, two factors need to addressed, the interfacial surface density of the liposomes for maximum drug loading and the stability of these liposomes to allow for controlled drug release. This thesis investigates a multilayer system for the affinity immobilisation of liposomes and their stability to various applied stresses. In the work presented here an allylamine monomer was used to create plasma coatings that were stable, thin and amine-rich. The aging studies using AFM showed these films to rapidly oxidise on exposure to water. The freshly deposited films were used for further surface modifications, by the covalent grafting of PEG layers of different interfacial densities under the conditions of varying polymer solvation. The AFM was used to measure the interaction forces between the grafted PEG layers and modified silica interfaces. It was found that the polydispersity of the PEG species resulted in bridging interactions of ???brush???-like PEG layers with the silica surface. These interactions were screened minimised by increasing the ionic strength of the solution. Although the densely grafted PEG layers were found to be highly protein-resistant by the XPS and QCM-D some minor protein-polymer adhesions were observed by the AFM. The densely anchored biotinylated PEG chains served as an optimum affinity platform for affinity-docking of NeutrAvidinTM molecules, which assembled in a rigid, 2-D layer as confirmed by the QCM-D. The submonolayer surface density of NeutrAvidin, as determined by Europium-labelling, was attributed to steric hindrance of the immobilised molecules. The final protein layer enabled specific binding of biotin-PEG-liposomes as a highly dissipative, dense and stable layer verified by tapping mode AFM and QCM-D. We found that these liposomes were also stable under a range of stresses induced by the shearing effects of water, silica probe and HSA layer at increased loads and velocities. The frictional response of the liposome layer also demonstrated the viscoelasticity and stability of these surface immobilised liposomes. Finally, the minimal adhesive interaction forces, as measured by the AFM, demonstrated the repellency of these liposomes to commonly found proteins, such as HSA.

1 Title: Interaction of group III and IV metals with Si(100) surface in temperature range from 20 to 800 K Author: Martin Setvín Department: Departement of Surface and Plasma Science Supervisor of the doctoral thesis: Doc. RNDr. Ivan Ošt'ádal CSc. Abstract: Interaction of group III and IV metals with Si(100) surface was studied by STM (Scanning Tunneling Microscopy) and AFM (Atomic Force Microscopy) in temperature range from 20 to 800 K. Adsorption and hopping of single metal adatoms on Si(100)-c(4×2) reconstruction can be observed by STM at low temperatures. Activation energies and frequency prefactors for hopping of single indium atoms were measured by two meth- ods - direct STM measurement at low temperature and Kinetic Monte Carlo simulations of layer growth at room temperature. Group III and IV atoms self-assemble into single atom wide chains on Si(100) surface at about room temperature. Atomic and electronic structure of the chains was investi- gated by means of STM and dynamic non-contact AFM. Keywords: Si(100), STM, AFM, adsorption, diffusion

Single crystals of iron with 20, 28 and 40 at. % aluminium were deformed in compression at room temperature. The later two alloys were deformed also at temperatures in the range of yield stress anomaly. Room temperature deformation was carried under the atomic force microscope (AFM) and the evolution of surface was recorded in-situ. Samples deformed at elevated temperatures were investigated by AFM after the deformation. Dislocation structures in deformed samples were then investigated in transmission electron microscope (TEM). Observations of surface (AFM) and bulk (TEM) are compared. Results of both techniques mutually agree and support the interpretation of observed phenomena. Several original analysis methods were developed. Most notably the stereographic reconstruction, which was applied to dislocation structures and carbide particles present in investigated alloys. Model explaining the distribution of carbide particle axes is presented. Powered by TCPDF (www.tcpdf.org)