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Research project (§ 26 & § 27)
Duration : 2017-08-01 - 2020-07-31

Due to global warming an increase of average temperatures is expected, which will affect tree populations in Austrian forests. More drought resistant species such as oak and pine will adapt, which are known to accumulate higher contents of extractives in their inner “heartwood”. Some of these extractive components are known to enhance the trees natural durability by protecting against microbial attacks. Apart of the fact that heartwood is essential for a long-living tree, these more durable heartwoods are desired for construction applications and might give access to valuable add-on products in a biorefinery process. On the other hand in the paper and timber industry the presence of extractives is not always welcome as technical processes may be hindered and have to be adapted. Heartwood formation has been studied since a long time. High variabilities among species, within single trees and under different environmental conditions have shown the complexity of this natural drying and impregnation process. Up to know, the chemical characterization has been mainly achieved by using different wet-chemical and chromatographic analysis. The context and relation to the wood microstructure is lost and often not all components are solved as changes in composition might need other treatment conditions and interactions with other cell wall polymers might occur. Still a knowledge gap exists on the distribution of these extractives on the micro- and nano scale and their interaction with other wood components. Are they mainly accumulated in the place of biosynthesis in the ray parenchyma cells or also transported to and impregnated in the fiber, tracheid and vessel cell walls? Is it a fast process or an ongoing slow polymerization process with changes in time and age? With this project these knowledge gaps will be filled by investigating native never dried heartwood samples by state of the art microspectroscopic in-situ approaches. Fluorescence microscopy will give an overview of the distribution of the phenolic compounds and Raman microscopy deliver a more detailed picture on the chemical composition in context with the microstructure as well as TOF-SIMS microscopy. Co-located ESEM will elucidate the ultrastructure of the changing cell walls during heartwood formation. With these approaches the we will 1) monitor heartwood formation of pine, douglas fir and oak trees by following the extractives from biosynthesis to the cell wall impregnation, 2) Assess the interactions of the extractives with other cell wall components and 3) determine the role of drying during the formation of heartwood and for a kind of “self-sealing” effect observed in some preliminary experiments. The results will reveal new insights into the biology of heartwood due to the detailed in-situ studies on the extractive distribution in context with the micro-and nanostructure as well as changes, solubilities and interactions. Furthermore in comparison to the natural dry falling of the tracheids the effects induced by artificial drying and thus important characteristics of wood as an industrial raw material will be derived. This will break new scientific grounds in the field of plant physiology (tree ageing), biomimetic plant protection mechanisms (decay resistance, “self-sealing”), but also regarding optimization of industrial applications and processes and the valorisation of add-on products in new biorefinery concepts.
Research project (§ 26 & § 27)
Duration : 2017-01-01 - 2019-12-31

Bacterial surface layer proteins (S-layers) have the ability to build protein crystal layers with nanometer regularity on solution and many different substrates. They are currently being tested as nano-templates for different biotechnological applications. However, the (path)way in which such proteins self-assemble forming organized nanostructures is not fully understood. In this context, we propose to investigate the recrystallization of three S-layer proteins, wild type SbpA and the recombinant proteins rSbpA31–1068 and rSbpA31-918, on (molecularly controlled) hydrophobic and hydrophilic disulfides. First, we will study the adsorption kinetics and recrystallization of the three bacterial proteins. Second, we would like to find the relation between the kinetics and the physical properties of the formed protein crystal (e.g. crystal domain size, lattice parameters). Third, we would like to clarify the question of the recrystallization pathway as a function of the properties of the substrate for these bacterial proteins (which also imply to get insight about protein/substrate interactions, especially about the recognition by the protein of hydrophobic and/or hydrophilic moieties).
Research project (§ 26 & § 27)
Duration : 2016-09-01 - 2021-08-31

Seeds enclosed in maternal tissue are an important evolutionary plant development as they protect the embryo in many different environments. The protecting coverings are very heterogeneous in structure and origin due to different seed dispersal strategies and environments designed for. The ones having hard outer coverings are commonly called nuts and their shells have recently become of interest for biomimetic research as they represent hard and tough lightweight structures with biological and environmental resistance. Biological materials are optimized at numerous length scales. To unravel the design principles on the micro- and nano scale and their assembly are a big challenge in biomimetic research. Thus the objectives of this project are threefold: 1) develop in-situ methods for in-depth characterization at the micro- and nano level, 2) reveal the heterogeneity and common design principles by investigating different species and 3) follow development (soft), maturation (hard) and germination (open). By measuring the inelastic scattering of laser light (RAMAN microscopy), tapping with a tip (Atomic force microscopy AFM, pulsed force mode) and combining both (Scanning near field optical microscopy-SNOM, Tip enhanced Raman spectroscopy-TERS) sophisticated applications for imaging natural packaging structures will be developed. This will enable us to gain new insights into micro- and nanochemistry as well as nanomechanics in the context of tissue and cell organization. Furthermore in-depth knowledge on the developmental processes of cell assembly, maturation and germination will be obtained. This will lead to a better understanding of the underlying design principles, which is important in order to extract structure-function relationships and identify features that contribute e.g. to the high strength and cracking resistance and longevity. Such information is important for biology (agriculture) and will give new input in intelligent biomimetic material design.

Supervised Theses and Dissertations