At the institute there are a number of topics available for scientific final works, not always listed on this page. If you are interested in a special topic please contact the corresponding person of our working areas.
Ongoing and finished theses
Structural characterization of biodegradable bone implants in the region of the bone-implant interface (in progess 11.2011)
Under the BRIC project the mechanical properties of the bone are examined in the range of the interface between the bone and implant. In the degradation of the implant, some of the ingredients are incorporated into the bone. With different methods of investigation, this change is examined in bone formation.
Microchemistry and nanostructure of xylem conduits and pit membranes (in progess 11.2014)
Chemical composition and structure of tracheid and vessel cell walls will be investigated in situ by combining Confocal Raman Microscopy and Atomic Force Microscopy. Using the Raman imaging approach lignification will be assessed on the micron-level in developing xylem to gain a better understanding of the secondary cell wall formation. Lignin amount and composition in dependence of species, size, age, position and environmental conditions (e.g. drought stress) will be investigated to learn on the plasticity and functionality of lignin. Furthermore pits as important valves in water transport and wood impregnation will be focused on. The combination of Raman microscopy and AFM allows to get new insights on microchemistry (lateral resolution 300nm) together with nanostructure and thus a better understanding of structure-function relationships (e.g. hydrophobisation, surface properties, water transport).
Bio inspired nanocomposites (finished 08/02/2016)
Basend on knowledge on the structure-function relatinoship in biological tissue, the thesis aims at incorporating selected nanostructural mechanisms into artificial composites in order to improve the mechanical performance by means of nanostructural methods.
Fatigue in 12% Cr steam turbine steel due to pitting corrosion (finished 02/19/2014)
The influence of corrosion pits on the fatigue behavior of martensitic 12% Cr steel was investigated. Based on extensive measurements, a method was developed which allows an estimation of the endurable cyclic stresses in relation to pit width, environment and stress ratio.
Contact: DI Dr Bernd Schönbauer (Prof. E. K. Tschegg, Univ.-Prof.in i. R. Stefanie Tschegg)
Bio-inspired bilayered actuators consisting of compression and normal pine wood tissue (finished 2015)
This master thesis is intended to generalize and investigate bio-inspired wooden actuators. The principle of those wooden bilayers is based on the model of pine cones, which open when dried to release ripe seeds and close when wet as a result of changing ambient humidity condition. The reason for this mechanism is the bilayered structure of the scales. In the experiment, the different linear expansion of both layers of one actuator at a certain humidity level results in a bending movement. This mechanism is comparable to a bimetal, responding to humidity-, instead of temperature change.
The main focus of this work is to take advantage of the structure-function relationship of wood for technical application. The interaction between the characteristics of the wood tissues and the resulting bending behaviour as well as force of the latter are explored in order to examine the potential for technical application.
Influence of testing frequency on the fatigue properties of polycrystalline copper (finished 2015)
The influence of testing frequency on the fatigue properties of polycrystalline copper is investigated. Tests are performed at conventional testing frequencies using a servohydraulic testing machine and with ultrasonic testing technique at a testing frequency of 19 kHz.
Nano-structure of bone after the application of bio-resorbable implants (finished 02.2014)
Bioresorbable implants are a class of implants that are resorbed by the body of a patient over the time of healing. Especially magnesium based alloys are a promising class of implants as no further operation is necessary but, unlike polymer systems they exhibit sufficient mechanical properties to effectively support the bone structure mechanically in case of a fracture. A class of patients that can hugely benefit from this behavior are children as they still exhibit significant skeletal growth and would hence need a second operation in the case of a nondegradable implant. The investigations are embedded into the BRIC (BioResorable Implants for Children) project that is a currently running project initiative of the Laura Bassi Laboratory under the project lead of MedUni Graz. This thesis deals with the nanostructural response of the bone structure on the implant over a certain span of time as studied by the method of small angle xray scattering (SAXS). The nanostructural changes of six rat femur bones with different Magnesium implant dwelling times from one to 18 month has been characterized on the basis of the orientation and morphology of the mineral platelets that make up the mineral reinforcement of the collagen matrix of the bone. A 2D mapping has been carried out to gain knowledge on local transitions in response to the implant with a resolution of about 350 µm. From the scattering patterns averaged information on the degree and direction of preferential orientation as well as the shape, thickness of the mineral platelets has been extracted. In this master thesis it is shown that:
- the direction of the platelets changes with the distance to the implant.
- the thickness of the mineral increases over time
- a different degradation behaviour of the pin is visible of in different types of bone.
Contact: Agathe Ogie (Univ.-Prof.inH. Lichtenegger)
Structure and Mineralization of Bone at the Interface to Bio-resorbable Implants
The Bachelor thesis is part of a larger project for the development of bio-resorbable bone implants based on magnesium alloys. In contrast to conventional implant materials they dissolve with time and are replaced by bone tissue. The aim of the Bachelor thesis is the study of structure and degree of mineralization at the interface between bio-resorbable implant and newly grown bone tissue (rat bone from small animla study). The thesis work is mainly laboratory based and focused on backscattered electron microscopy.
Contact: Lukas Meidlinger (Univ.-Prof.inH. Lichtenegger)