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Posters |
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Fusion of Cellulose Microspheres with Pulp Fibers: Creating an Unconventional Type of Paper
Alexa Scheer, Institute of Bioproducts and Paper Technology, TU Graz
Abstract: Cellulose microspheres (CMS) are spherical regenerated cellulose particles with tunable properties and broad potential for functionalization, commonly used in fields such as pharmaceutical formulation, chromatography, and purification. Despite their versatility, the integration of CMS into paper-based materials has received little attention. In this study, we demonstrate a method to incorporate up to 50 wt.% CMS into hand sheets, resulting in mechanically stable paper structures with a unique microstructure, significantly exceeding the typical filler content of conventional papers. To evaluate the properties of hand sheets containing CMS, we compare blank sheets of identical grammage (lower fiber content) and lower grammage (equivalent fiber mass). Surface analysis by infinite focus microscopy shows that a CMS layer forms on the fiber network, filling voids and smoothing the surface. Gurley air permeance measurements confirm that the microspheres densify the sheet by occupying interstitial spaces among fibers. Tensile tests on hand sheets with identical fiber content reveal that fiber-fiber bonding remains unaffected, as reflected by the retention of tensile strength. These findings demonstrate the feasibility of fabricating CMS-cellulose fiber composites, providing a foundation for further studies aimed at developing advanced CMS–cellulose fiber materials. |
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Attosecond Electron Control
Alexander Sagar Grossek, Marcus Ossiander, Martin Schultze
Abstract: We excite ultrafast electron dynamics in Argon and Xenon with ultrashort laser pulses. Subsequently we track these dynamics of the electrons in a pump/probe scheme. As the pump we use an broadband Extreme-UV pulse to excite multiple coherent Rydberg state oscillations in Argon/Xenon. As the probe we use an IR pulse which ionises the Rydberg states variably depending on the live position of the electron oscillations, which we control with the delay of the probe. The resulting current produced by the free electrons is measured and the Rydberg oscillations are reflected in the current trace. |
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Fe-doping of the lead-free piezoceramic (Ba,Ca)(Zr,Ti)O3 system
Anamaria Mihaljevic, Alexander Fally, Anna M. Paulik, Jurij Koruza
Abstract: In recent years research has been directed towards the development of non-toxic, lead-free ferroelectric materials, with significant attention drawn to the exceptional piezoelectric properties of the (Ba,Ca)(Zr,Ti)O3 (BCZT) ferroelectric system. However, while the system exhibited high properties for low-frequency applications, its usability at higher frequencies, i.e., under resonance conditions, is limited. The latter require materials with low losses and high mechanical quality factors, which can be achieved by point defects induced by acceptor doping.
Our study investigated the effect of doping the (Ba0.82Ca0.18)(Zr0.08Ti0.92)O3 system with Fe ions at the perovskite B-site, which was expected to create acceptor states in the electronic structure and charge-compensating oxygen vacancies. We investigated the influence of different concentrations of Fe on the microstructure and ferroelectric properties of the BCZT system. To this end, we performed Rietveld analysis of the X-ray diffraction data, optical microscopy, dielectric measurements, polarization and strain measurements, as well as impedance resonance spectroscopy. The Rietveld analysis revieled that an increase in Fe concentration above 1% results in a transition from a tetragonal to a cubic structure at room temperature. The addition of Fe decreased the Curie point and eventually induced relaxor-like behaviour. Moreover, the findings have been confirmed by the observed slimming of the polarization-electric field loops with increasing concentration of Fe.
While Fe has been shown to reduce overall piezoelectric properties, an increase in the mechanical quality factor from 150 to 500 was achieved for 0.5% Fe. These results demonstrate the potential for tailoring functional properties through precise control of doping levels and illustrate the complexity of the BCZT system, providing a foundation for future doping and co-doping strategies.
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Magnetic Characterization of printed FeCrCo Magnets
Andreas Gschwentner , Institute of Fundamentals and Theory in Electrical Engineering, Graz University of Technology
Abstract: Andreas Gschwentner (1), Siegfried Arneitz (2), M.C. Poletti (2), C. Sommitsch (2),A. Griffond (3), P. DeRango (3), K. Roppert (1), M. Kaltenbacher (1)
(1) Institute of Fundamentals and Theory in Electrical Engineering, Graz University of Technology (2) Institute of Materials Science, Joining and Forming, Graz University of Technology, (3) Institut Nèel, Grenoble, France
Hard and permanent magnets find a broad range of industrial applications, whether in the automotive sector for permanent synchronous machines or as lifting devices in logistics. Crucial for the different applications is the accurate determination of the mechanical and magnetic properties for these magnets. This study investigates the magnetic properties of printed FeCrCo magnets. A key advantage of these magnets is that no rare earth elements are needed. Additionally, the printing process allows the manufacturing of complex geometries, enabling new designs for various devices. |
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Optical Trace Ammonia Sensors: From Synthesis to Application
Andreas Matijevic, Sergey M. Borisov, Torsten Mayr, Institute of Analytical Chemistry and Food Chemistry
Abstract: The global human population is expected to grow by nearly 2 billion people over the next 30 years, intensifying challenges related to food security. In response, aquaculture has grown rapidly in importance, contributing to the global food supply.[1] Its market value is predicted to double by 2050.[2] The UN’s vision for a Blue Transformation in the food industry underscores the importance of sustainable practices in this sector.
A notable trend within aquaculture is the shift toward inland farming, which demands precise monitoring of critical parameters to ensure fish health. Among these, ammonia levels are particularly crucial, as ammonia is highly toxic to the aquatic flora and fauna. The toxicity threshold for fish is estimated to be 25 µg/L, making accurate detection essential.
This work presents an optical ammonia sensor based on a novel aza-BODIPY dye, capable of detecting ammonia concentrations in the low µg/L range. The sensor demonstrates excellent long-term stability and resilience to variations of temperature and pH, making it a reliable tool for monitoring ammonia in fish farms and diverse biotechnological applications.
[1] FAO. (February 2, 2024). Global fish production from 2002 to 2023 (in million metric tons) [Graph]. In Statista. Retrieved January 27, 2025, from https://www.statista.com/statistics/264577/total-world-fish-production-since-2002/
[2] Office of Industry Analysis. (November 11, 2022). Global aquaculture market value forecast from 2020 to 2026 (in billion U.S. dollars)* [Graph]. In Statista. Retrieved January 27, 2025, from https://www.statista.com/statistics/240334/us-aquaculture-production-value-since-2001/
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(Extreme) Ultraviolet Metaoptics
Anna Karner, David Grafinger, Marcus Ossiander, Insitute of Experimentalphysics, TU Graz
Abstract: Extreme ultraviolet (EUV) light carved out an essential role in countless applications such as high-resolution imaging/lithography, quantum optics and attosecond metrology, just to name a few. In spite of this, conventional optical elements for EUV light are relatively scarce and expensive, as materials suited for the short wavelengths are hard to come by. Dielectric metasurfaces, whose function is based on the microscopic modulation of the electromagnetic (EM) wave instead of the macroscopic refraction/diffraction of light, could offer an alternative to this inherent problem. While these nanoscale optics have already established a prominent role in applications from infrared (IR) to the visible spectrum, the EUV range still poses challenges. However, a metasurface concept which is suitable down to the EUV region was recently demonstrated (Ossiander, 2023). We want to build on this to develop new optics for EUV microscopy.
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Effects of Ultrasonic Joining Parameters on Quasi-static Strength of Wood-Polymer Hybrid Joints
Awais Awan, Institute of Materials Science, Joining and Forming (IMAT)
Abstract: Awan A.1, Oliveira G.H.M.1, Auer P.1,2, Domitner J.1,2, Amancio-filho S.T.1
1 Institute of Materials Science, Joining and Forming (IMAT), Professorship “Aviation Materials and Manufacturing Techniques”, Graz University of Technology (TU Graz), Graz, Austria
2 Institute of Materials Science, Joining and Forming (IMAT), Research Group of Lightweight and Forming Technologies, Graz University of Technology (TU Graz), Graz, Austria
The increase in carbon emissions has raised the demand for innovative, eco-friendly material combinations and advanced joining techniques in the transportation industry, aiming to reduce dependency on fossil fuels and minimize their environmental impact. Ultrasonic Joining (U-Joining) is a novel friction-based joining technique developed recently to produce high-strength joints between dissimilar materials. U-Joining even enables the manufacturing of hybrid joints between wood and fiber-reinforced thermoplastics. The current study produced single lap joints between as-received beech wood and additively manufactured short carbon fiber-reinforced polyamide (PA6-15CF) using U-Joining. This process employs high-frequency mechanical vibrations to generate frictional heat at the joint interface, melting the thermoplastic polymer, which then consolidates on the wood surface to form a strong bond. A Box-Behnken design of experiments was applied to optimize key U-Joining parameters (energy, pressure, and amplitude) to maximize the ultimate lap shear force (ULSF). Optimized joints achieved an ultimate lap shear force of 2.1 ± 0.1 kN, with a displacement at break (DaB) of 1.6 ± 0.2 mm. Analysis of variance (ANOVA) results showed that all three process parameters had statistically significant effects on ULSF. Moreover, a second-order interaction effect of amplitude and a two-way interaction effect between joining energy and amplitude were also found to be statistically significant. Scanning electron microscopy (SEM) images of the joint cross-section revealed the micro-mechanical interlocking between the consolidated PA6-15CF and the rough wood surface. Fracture analysis showed that failure occurred via delamination at the interface, exhibiting a mixed cohesive and adhesive fracture mode. Given the nominal overlap area (15.5 mm x 12.7 mm), the ultimate lap shear strength (ULSS) reached 10.8 ± 0.6 MPa, making the beech/PA6-15CF joints a promising candidate for eco-friendly lightweight structures. This study highlights the potential of U-Joining in advancing sustainable materials and joining technologies for the transportation sector.
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Investigation of diluted donor solar cells with D18:L8-BO
Bernadette Ortner
Abstract: Semitransparency, which can be achieved by organic solar cells (OSC), in contrast to inorganic semiconductors, is advantageous for several applications such as building-integrated photovoltaics (BIPV). Transmission of visible light is increased when the active layer contains a diluted donor content. However, reduced donor content results in efficiency losses. 16.4% were achieved for the D18:L8-BO 1:1.5 ratio and drops to 7.6% for 1:10. To gain further insight into the origin of this efficiency drop we investigated the morphology changes with scanning transmission electron microscopy and found a network formation of the donor material in the active layer even at high ratios of 1:50. An elevated acceptor content has been demonstrated to have a negligible impact on the generation of charge carriers although electron and hole mobilities remained unaffected by the decreasing donor content. The drop in performance is mainly caused by higher recombination and inefficient charge separation due to limited interfaces. With further investigation of these networks more efficient semitransparent cells would be possible. |
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Spatio-temporal averaging of three-dimensional Discrete Dislocation Dynamics (DDD) data
Bernhard Heininger, Institute of Strength of Materials
Abstract: Continuum Dislocation Dynamics (CDD) theories have long been focusing on
the spatial averaging process, which is particularly challenging because dislocations are curved, flexible line-like objects. This entails that dislocation configurations need to be characterized by at least a few density and curvature tensors in order to achieve kinematical self-consistency [1]. However, the derivation of a crystal plasticity theory based on CDD requires a kinematic closure in terms of average dislocation velocities. Such velocity averaging necessarily needs to be done in space and time [2], where the spatial and temporal dimensions of the (spatio-temporal) averaging volume are inevitably coupled.
From an extensive data set of three-dimensional discrete disloction dynamics (DDD) simulations of uniaxial tensile tests [3] in different crystallographic orientations we extract alignment-, curvature-, and velocity-tensors of various orders for different spatio-temporal (4D) resolutions. We analyse the loss of information as compared to the data evolution, when the CDD evolution is based on the average quantities. From this comparison we deduce suitable dimensions of the spatio-temporal averaging volume based on the dislocation density and the applied stress or the strain rate. This analysis is an important step towards endowing 3D-CDD theories with a suitable scale of spatio-temporal resolution.
References
[1] Thomas Hochrainer. Multipole expansion of continuum dislocations dynamics in terms of alignment tensors. Philosophical Magazine, 95(12):1321–1367,2015.
[2] Pierre-Louis Valdenaire, Yann Le Bouar, Benoît Appolaire, and Alphonse Finel. Density-based crystal plasticity: From the discrete to the continuum. Physical Review B, 93(21):214111, 2016.
[3] Sh Akhondzadeh, Ryan B Sills, Nicolas Bertin, and Wei Cai. Dislocation density-based plasticity model from massive discrete dislocation dynamics database. Journal of the Mechanics and Physics of Solids, 145:104152, 2020. |
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Repurposing dredged mud through 3D clay printing technology
Britta Nader
Abstract: Britta Nader (a), Hana Vašatko (a), Julian Jauk (a), Dorothee Hippler (b), Milena Stavric (a)
(a) Graz University of Technology, Institute of Architecture and Media
(b) Graz University of Technology, Institute of Applied Geosciences
Abstract:
The construction industry is under growing pressure to adopt sustainable practices and materials to reduce its environmental impact. In order to address these issues, we explore an innovative approach for dredged mud from Lake Neusiedl in Austria, a resource that is both abundant and largely untapped, transforming it into a 3D-printable material for building applications. We moreover aim to combine the dredged mud with fibers from Phragmites australis, i.e. common reed, to investigate if fiber reinforcement enhances consolidation and the material’s properties. Central research questions include: What adjustments are needed to make 3D printing technology compatible with this distinct material? What performance characteristics, such as strength and durability, can be achieved in 3D-printed objects made from this material? The project employs an integrated research approach, including material analysis, optimization of the 3D printing processes, and mechanical testing of the printed components. A custom-built 3D printer is being developed for extruding the dredged mud. Simultaneously, advanced analytical techniques, such as X-ray diffraction, scanning electron microscopy, grain size analysis and BET, will be used to evaluate the geomaterials on a small scale.
This research proposes a repurposing of dredged mud as a viable, sustainable material for 3D printing in construction. By combining it with natural fibers to improve its properties, the project offers a new perspective on site-specific building material development. The creation of a specialized 3D printer for on-site use further highlights its potential to advance sustainable building practices.
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Piezoelectric hardening: Mechanisms, Processing, Characterization and Applications
Chinmay Chandan Parhi, Anna Margarethe Paulik, Anamaria Mihaljevic, Jurij Koruza, Institute for Chemistry and Technology of Materials
Abstract: Piezoelectric materials enable the coupling between electrical and mechanical signals and are widely used in various electronic applications. A large part of piezoceramics is used in high-power devices, which among others include voltage transformers, ultrasonic motors, ultrasonic welding, cutting, cleaning devices, and therapeutic medical appli-cations [1]. In these devices the piezoelectric is driven in the vicinity of its resonance frequency by a comparatively-high AC electric field, which induces a high vibration velocity. These harsh conditions require piezoelectrically hard materials with low losses and high stability.
We start by describing the underlying piezoelectric hardening mechanisms, which are based on hindering the move-ment of ferroelectric domain walls by various defects. The first mechanism includes point defects, which are intro-duced by acceptor doping and resulting charge-compensating vacancies. We are developing a new concept of Fermi level engineering in piezoceramics, whereby targeted co-doping enables to increase the concentration of dopants [2]. The second mechanism is based on the introduction of dislocations, i.e., 1-dimensional (line) defects with charged cores and space-charge layers [3]. These enable elastic and electrostatic pinning of ferroelectric/ferroelastic domain walls. The third mechanism utilizes 2-dimensional defects, mostly grain boundaries, which are restricting domains by intragranular stresses and direct pinning [4]. The fourth mechanism includes 3-dimensional defects, such as second phase precipitates [5]. Selected material compositions exhibiting the above-mentioned mechanisms will be presented and their synthesis routes will be detailed.
In the final part, we present the structural and electro-mechanical characterization methods used for the evaluation of hard-type piezoelectric materials. In particular, we focus on measurements of the piezoelectric resonance, which enables amplification of the displacement. In order investigate the mechanisms and directly follow the interactions between the various defects and domain walls, we developed a method combining resonance electro-mechanical excitation with high-energy X-ray diffraction [6]. Finally, an outlook on further material development and potential applications of the newly-developed materials will be provided.
Bibliographic references:
[1] K. Uchino, Woodhead Publ., Cambridge UK (2017).
[2] A. Klein, et al., Journal of Electroceramics, Vol. 51 (2023) 147-177.
[3] M. Höfling, et al., Science, Vol. 372 (2021) 961-964.
[4] J. Schultheiß, et al., Journal of the European Ceramic Society, Vol. 40 (2020) 3965-3973.
[5] C. Zhao, et al., Advanced Materials, Vol. 33 (2021) 2102421.
[6] M. Slabki, et al., Physical Review B, Vol. 103 (2021) 174113.
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Development of CuO/Cu$_2$O based MOx sensors for gas detection
Christian Maier$^1$, Larissa Egger$^1$, Anton Köck$^1$, Sören Becker$^2$, Jan Steffen Niehaus$^2$, Klaus Reichmann$^3$, Materials Center Leoben Forschung GmbH
Abstract:
1. Materials Center Leoben Forschung GmbH, Roseggerstraße 12, 8700 Leoben, Austria
2. Fraunhofer Center for Applied Nanotechnology CAN, Grindelallee 117, 20146 Hamburg, Germany
3. Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
Indoor air quality has become a subject of considerable interest and discussion in recent years due to the potential presence of various gases, including carbon monoxide (CO) and volatile organic compounds (VOCs), which have the potential to be harmful, and in some cases, toxic. A significant concern is the presence of carbon dioxide (CO$_2$) in indoor environments, particularly when levels exceed 1000 ppm. This can result in symptoms such as reduced concentration levels, headaches, and potentially more severe health implications, including respiratory and circulatory problems. Metal oxide (MOx) based gas sensors, such as CuO/Cu$_2$O [1], are considered to be highly promising candidates due to their ability to integrate into microelectronic systems [2] and their high sensitivity to a wide range of AQ-relevant gases. The sensing mechanism of these sensors is based on a change in the conductivity of the MOx caused by various chemical reactions with gas molecules on their surface. In this study, we have developed and investigated various types of CuO and Cu$_2$O thin films as gas sensing materials. The micro hotplate sensors [3] were tested against different target gases, including CO, CO$_2$ and a mixture of hydrocarbons (HC$_{Mix}$), in order to evaluate the cross-sensitivity and humidity. Furthermore, the sensor devices were functionalised with gold nanoparticles (Au-NPs) of different sizes in order to enhance the sensor response towards target gases and reduce the cross-sensitivity.
References
[1] Maier, C.; Egger, L.; Köck, A.; Reichmann, K. A Review of Gas Sensors for CO$_2$ Based on Copper Oxides and Their Derivatives. Sensors (Basel) 2024, 24, doi:10.3390/s24175469.
[2] Maier, C.; Leitgeb, V.; Egger, L.; Köck, A. Size-Dependent Thresholds in CuO Nanowires: Investigation of Growth from Microstructured Thin Films for Gas Sensing. Nanomaterials (Basel) 2024, 14, doi:10.3390/nano14141207.
[3] Maier, C.; Egger, L.; Köck, A.; Becker, S.; S. Niehaus, J.; Reichmann. K. OT5.154 - Gas Sensing Performance of CuO Sensors Functionalized with Different Stabilized Au-NP. In Lectures. EUROSENSORS XXXVI, Debrecen (Hungary), 01–04 Sep. 2024; AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, 2024; pp 119–120.
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Building Bridges: Tailoring Low-Valent Heteroatomic Frameworks of Phosphorus and the Heavier Tetrel Elements
Clara A. Roller, Roland C. Fischer, Michaela Flock, Institute of Inorganic Chemistry
Abstract: In conjunction with Lappert's landmark syntheses of the ditetrylenes species [((Me3Si)2HC)2E]2 (E = Ge, Sn, Pb),[1a,b] the isolation of the first stable N-heterocyclic carbene (NHC) by Arduengo during the 1990s is commonly acknowledged as a pivotal achievement in the investigation of main group compounds in nontraditional bonding environments.[2] Currently, a wide range of nitrogen-substituted derivatives is documented in literature,[3] while the number of phosphatetrylenes is limited to just a handful of compounds[4a-d] and examples of heteroleptic N/P-substituted representatives are even more scarce.[5a,b] Herein, we investigate the reactivity and structural diversity of phosphanyl-supported group 14 compounds in non-traditional bonding environments. This includes the isolation of the first amidophosphaplumbylene [(u2-R(H)P)Pb(N(SiMe3)2)]2 (R = C(SiMe3)3). The dual functionality of the remaining amide and hydride groups within this species enables targeted synthesis of heteronuclear cluster architectures, such as cubanes [(RP)E]4 and propellanes [(RP)3E2] (E = Sn, Pb), with heavier tetrel atoms occupying the bridgehead positions. 1,3-diplumba-2,4,5-triphospha[1.1.1]propellane is the first example of a Pb-containing [1.1.1]propellane, completing the set of heavier tetrel representatives for this unique framework.[6a,b]
References:
[1] (a) D. H. Harris, M. F. Lappert, J. Chem. Soc. Chem. Comm. 1974, 895–896. (b) D. E. Goldberg, D. H. Harris, M. F. Lappert, K. M. Thomas, J. Chem. Soc. Chem. Comm. 1976, 227, 261–262.
[2] A. J. Arduengo, R. L. Harlow, M. Kline, J. Am. Chem. Soc. 1991, 113, 361–363.
[3] Y. Mizuhata, T. Sasamori, N. Tokitoh, Chem. Rev. 2009, 109, 3479–3511.
[4] (a) M. Balmer, Y. J. Franzke, F. Weigend, C. von Hänisch, Chem. Eur. J. 2020, 26, 192–197. (b) K. Izod, P. Evans, P. G. Waddell, Inorg. Chem. 2020, 59, 863–874. (c) E. Schwarz, S. K. Mueller, G. Weinberger, A. Torvisco, M. Flock, Organometallics 2018, 37, 2950–2960. (d) M. Driess, R. Janoschek, H. Pritzkow, S. Rell, U. Winkler, Angew. Chem. Int. Ed. 1995, 34, 1614–1616.
[5] (a) A. Hinz, J. M. Goicoechea, Chem. Eur. J., 2018, 24, 7358-7363. (b) T. Reznicek, L. Dostal, A. Ruzicka, R. Jambor, Eur. J. Inorg. Chem., 2012, 2983-2987.
[6] (a) D. Nied, P. Oña-Burgos, W. Klopper and F. Breher, Organometallics, 2011, 30, 1419– 1428. (b) E. Moos, T. Augenstein, D. Garnier and F. Breher, in Can. J. Chem. 2014, 92, 574–579. |
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BIOPOLYMERIC ALGINATE COMPOSITES - Sustainable Approach for Advanced Material Applications
Cornelia Ott, Institute of Architecture and Media
Abstract: Cornelia Ott (1), Rupert Kargl (2), Tamilselvan Mohan (2), Karin Stana Kleinschek (2), Milena Stavric (1)
(1) Institute of Architecture and Media (IAM), Faculty of Architecture, Graz University of Technology
(2) Institute for Chemistry and Technology of Biobased Systems (IBioSys), Faculty of Technical Chemistry, Chemical and Process Engineering, and Biotechnology, Graz University of Technology
The construction industry profoundly affects ecosystems through high energy consumption, resource depletion, and carbon emissions, resulting in significant environmental challenges. Innovating sustainable material solutions is essential to address these environmental challenges effectively. In this context, this research examines sodium alginate, a seaweed-derived biopolymer, as a structural binder in composite materials. Despite its extensive application in various sectors, alginate remains underutilized in the construction industry. However, its remarkable properties-including biocompatibility, biodegradability, and ease of processing—make it a promising candidate for the development of sustainable and advanced materials in the building industry.
Alginate is well-known for its ability to form strong and uniform gels. It is composed of linear chains of monomers arranged in a single, unidirectional sequence without branches or side chains. This straight, unbranched structure is crucial to alginate’s gel-forming properties, as it facilitates the formation of robust, heat-stable gels when cross-linked with divalent cations such as calcium (Ca2+ ions). The strength and stability of these gels increase with the concentration of Ca2+ ions, as higher concentrations promote more cross-links between the alginate chains, thereby enhancing rigidity and stability [1-3].
This poster presentation explores alginate-based composites developed using the gelation method, incorporating corn, clay, and perlite as additives. The effects of varying cross-link concentrations and composite formulations on material properties were systematically analysed. Results indicate that the inclusion of corn enhances the composite’s rigidity due to its structural contribution, while maintaining a density of approximately 0.34 g/cm3 - comparable to cork but offering superior stability. In contrast, the addition of micro-sized clay particles, particularly in the presence of glycerol as a plasticizer, improved the material’s flexibility, yielding a more pliable behaviour with a relatively high density of approximately 1.67 g/cm3. Perlite, a lightweight filler, significantly reduced the composite’s density (0.12 g/cm3) while enhancing its thermal insulation properties. These findings demonstrate the potential of alginate-based composites for applications that require a tailored balance of mechanical strength, flexibility, and thermal performance, highlighting their suitability for sustainable and multifunctional material solutions.
[1] Kuen Yong Lee a b, David J. Mooney (2012). Alginate: Properties and biomedical applications. Progress in Polymer Science. Progress in Polymer Science, Vol. 37, Issue 1, 106-126. https://doi.org/10.1016/j.progpolymsci.
2011.06.003
[2] Bojorges, H., López-Rubio, A., Martínez-Abad, A., & Fabra, M. J. (2023). Overview of alginate extraction processes: Impact on alginate molecular structure and techno-functional properties. Trends in Food Science
& Technology, 140, 104142. https://doi.org/10.1016/j.tifs.2023.104142
[3] Abka-khajouei, R., Tounsi, L., Shahabi, N., Patel, A. K., Abdelkafi, S., & Michaud, P. (2022). Structures, Properties and Applications of Alginates. Marine Drugs, 20(6), 364. https://doi.org/10.3390/md2006036
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Scale-Up of 3D-Printed Bioreactors for Continuous-Flow Biotransformation
Daniel Pint, IPPT/IBioSys
Abstract: Daniel Pint (1,2), Florian Lackner (2), Lenny Yap (3), Lisa Schmedler (1), Rupert Kargl (2), Robert Kourist (3), Heidrun Gruber-Wölfler (1), Karin Stana Kleinschek (2)
1) Institute of Process and Particle Engineering (IPPE), Graz University of Technology, Inffeldgasse 13/III, 8010 Graz
2) Institute for Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz
3) Institute of Molecular Biotechnology (IMBT), Graz University of Technology, Petersgasse 14, 8010 Graz
The scale-up and optimization of 3D-printed bioreactors for continuous-flow biotransformations using immobilized cyanobacteria (Synechocystis sp. PCC 6803) are reported. Drawing on previous advancements in anisotropic hydrogels [1] and light-driven biotransformations [2], the reactor design was refined and scaled up to a reactor area from approximately 20 cm² to 120 cm², enabling the transition from batch to continuous-flow. Initial testing with smaller reactors, connected in series, demonstrated promising performance in continuous flow, providing a foundation for further optimization. The biotransformation of cyclohexanone via Baeyer-Villiger monooxygenases (BVMO) and 2-methylmaleimide via ene-reductase (YqjM) was investigated, providing comparative insights into enzymatic performance. Mechanical characterization through tensile testing proved the structural integrity of the 3D-printed polysaccharide bioink scaffolds which are very robust in operative environments [3, 4]. This work represents a step forward in integrating 3D bioprinting with continuous-flow technologies, advancing scalable and efficient biocatalytic processes beyond semi-continuous approaches.
[1] F. Lackner u. a., „3D-Printed Anisotropic Nanofiber Composites with Gradual Mechanical Properties“, Adv Mater Technol, Bd. 8, Nr. 10, Mai 2023, doi: 10.1002/admt.202201708.
[2] L. Malihan-Yap, H. C. Grimm, und R. Kourist, „Recent Advances in Cyanobacterial Biotransformations“, 1. November 2022, John Wiley and Sons Inc. doi: 10.1002/cite.202200077.
[3] C. Han u. a., „Effects of nanocellulose on Alginate/Gelatin Bio-inks for Extrusion-based 3D Printing“, Bioresources, Bd. 15, Nr. 4, S. 7357–7373, Aug. 2020, doi: 10.15376/biores.15.4.7357-7373.
[4] F. Lackner u. a., „4-Axis 3D-Printed Tubular Biomaterials Imitating the Anisotropic Nanofiber Orientation of Porcine Aortae“, Adv Healthc Mater, Bd. 13, Nr. 2, Jän. 2024, doi: 10.1002/adhm.202302348.
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Master’s Thesis: Covalent Crosslinking of Alginate by Native Chemical Ligation (NCL)
David Bucak Gasser, Karin Stana Kleinschek, Rupert Kargl, Institute of Chemistry and Technology of Biobased Systems, Graz University of Technology
Abstract:
Since its introduction in 1994 by Kent and colleagues, native chemical ligation (NCL) has emerged as a revolutionary tool in protein chemistry. This innovative method facilitates the ligation of two unprotected peptide segments via the formation of an amide bond between a C-terminal peptide thioester and an N-terminal cysteine peptide.[1] Notably, NCL operates under mild, aqueous, and neutral pH conditions, achieving near-quantitative yields with exceptional chemo-selectivity. These features have enabled NCL to transcend beyond its initial applications in peptide chemistry and reach diverse fields, including biotechnology, biomedicine, and materials science.[2]
Despite its versatility, the potential of NCL as a bioconjugation and crosslinking strategy for biopolymers remains largely unexplored.[3] We report on an innovative strategy for covalent crosslinking of alginate using NCL. Alginate (Alg) was functionalized with amino-acid-based thioester functionalities (AA-SR) and crosslinked with a bifunctional L-cysteine-based linker, forming hydrogels under mild, aqueous, and neutral pH conditions within minutes. This work highlights an innovative utilization of NCL, demonstrating its potential for engineering biocompatible hydrogels with broad implications for biomedicine.
[1] Kent, S. B. H., Total chemical synthesis of proteins. Chemical Society Reviews 2009, 38 (2),338-351.
[2] Agouridas, V., El Mahdi, O., Diemer, V., Cargoët, M., Monbaliu, J.-C. M., Melnyk, O., Native Chemical Ligation and Extended Methods: Mechanisms, Catalysis, Scope, and Limitations. Chemical Reviews 2019, 119 (12), 7328-7443.
[3] Gao, Y., Peng, K., Mitragotri, S., Covalently Crosslinked Hydrogels via Step-Growth Reactions: Crosslinking Chemistries, Polymers, and Clinical Impact. Advanced Materials 2021, 33 (25), 2006362.
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Polydicyclopentadien-Based Hard Carbon for Long Cycle Life Na-Ion Battery Anodes
David Schuster(a), Bernd Fuchsbichler(b), Glen Smales(a), Max Schmallegger(a), Christian Slugovc(a), (a)TU Graz (b) Varta Innovation GmbH
Abstract: As an unidentical twin to lithium-ion batteries (LIBs), sodium-ion batteries (SIBs) are widely considered a promising alternative due to the abundance and low cost of raw materials. However, the development of high-performance and cost-effective electrode materials remains a significant challenge, particularly when competing with lithium iron phosphate (LFP) systems.[1,2,3] Herein, we present a hard carbon (HC) material derived from inexpensive and readily available poly(dicyclopentadiene) for use as a negative electrode in SIBs. This work introduces a cost-effective approach for producing hard carbon materials with distinctive nanostructure and provides valuable insights into achieving long cycle life in sodium-ion batteries. |
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3D-Printed Alginate-NFC Scaffolds functionalized with HP-beta-CD/CBD Complexes. A Novel Approach for Enhanced Solubility and Drug Delivery of CBD
Dennis A. Silva-Cullishpuma , Nutrition, Food and Health (NAS), Universidad Catolica San Antonio de Murcia, Avda. Los Jeronimos 135, Guadalupe de Maciascoque, 30107 Murcia, Spain
Abstract: Dennis A. Silva-Cullishpuma (1), Maria Teresa Mercader-Ros (1), Camilo Zamora-Ledezma (2), Carmen Lucas-Abellan (1), Rupert Kargl (3), Karin Stana Kleinschek (3) and Tamilselvan Mohan (3)
1) Nutrition, Food and Health (NAS), Faculty of Pharmacy and Nutrition, UCAM-Universidad Catolica de Murcia, Avda. Los Jeronimos 135, Guadalupe de Maciascoque, 30107 Murcia, Spain
2) Higher Polytechnic School, UAX-Universidad Alfonso X el Sabio, Avda. Universidad, 1, Villanueva de la Canada, 28691 Madrid, Spain
3) Institute for Chemistry and Technology of Biobased System (IBioSys), Graz University of Technology, Stremayrgasse 9, Graz, 8010 Austria
Cannabidiol (CBD) is a hydrophobic compound with significant therapeutic potential; however, its poor aqueous solubility severely limits its bioavailability and functionality in pharmaceutical, nutraceutical, and biomedical applications [1]. To overcome this limitation, the formation of inclusion complexes with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was explored as a strategy to enhance CBD solubility and stability. Phase solubility studies demonstrated that HP-beta-CD significantly improved CBD aqueous solubility through the formation of inclusion complexes with a 1:1 stoichiometry and a high complexation constant. Solid HP-beta-CD/CBD complexes were prepared via spray drying and characterized using advanced techniques such as SEM, DSC, TGA, etc. These analyses confirmed the stable host-guest interactions between CBD and HP-beta-CD, elucidating the encapsulation mechanism and validating the potential of these complexes for improving CBD’s physicochemical properties [2].
Building on this foundation, the need for scaffolds capable of delivering CBD in a controlled and localized manner has become increasingly evident, particularly for applications in drug delivery, tissue engineering, and functional food systems. To address this need, the study focused on the development a 3D-printed scaffold using a bioink composed of alginate, nanofibrillated cellulose (NFC), and calcium chloride (CaCl2), incorporating the previously characterized HP-beta-CD/CBD complexes. Alginate-based bioinks have demonstrated excellent printability and mechanical properties in prior research, making them ideal candidates for such applications [3]. Therefore, the composition of the HP-beta-CD/CBD bioink was successfully optimized in this study, resulting in stable 3D printed scaffolds with consistent performance [4]. These scaffolds may represent a biocompatible matrix capable of sustained CBD release, making them highly suitable for potential drug delivery and functional material development in biomedical and nutraceutical contexts.
[1] M. Parlak Khalily, Improving the water solubility of cannabidiol using a peptide carrier, Turk J Chem, vol. 48, no. 2, p. 229, 2024, doi: 10.55730/1300-0527.3655.
[2] D. A. Silva-Cullishpuma et al., Optimising the nutraceutical potential of Hemp major non psychoactive cannabinoid (Cannabidiol) via Hydroxypropyl-beta-Cyclodextrin Complexation and Mesenchymal Stem Cell Response, Article in Preparation, 2025.
[3] F. Lackner et al., 3D-Printed Anisotropic Nanofiber Composites with Gradual Mechanical Properties, Adv Mater Technol, vol. 8, no. 10, May 2023, doi: 10.1002/ADMT.202201708.
[4] D. A. Silva-Cullishpuma, M. T. Mercader-Ros, C. Zamora-Ledezma, C. Lucas-Abellan, and K. Stana Kleinschek and T. Mohan, Innovative 3D-Printed Alginate Scaffolds with Sequential CaCl2 Crosslinking. Characterization and Advanced Delivery of Non-Psychoactive Cannabinoids Complexed in HP-beta-CD, Article in Preparation, 2025.
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IsoME: Streamlining High-Precision Eliashberg Calculations
Dominik Spath
Abstract: Conventional superconductivity arises from the formation of Cooper pairs, where an attractive interaction between electrons mediated by the electron-phonon coupling allows them to overcome the repulsive Coulomb interaction. Migdal-Eliashberg theory [1, 2] is a state-of-the-art perturbative many-body framework that provides a detailed and accurate description of the superconducting phase.
Although Migdal-Eliashberg theory has been available since the 1960s, progress in the field of superconductivity has historically been driven by experimental discoveries. However, the exponential growth in computational power over the past decades, coupled with the development of highly efficient and accurate numerical codes, enables the discovery of novel crystals and the determination of their superconducting properties entirely from first principles.
We present the very efficient and highly accurate, yet easy-to-use, open-source Julia package IsoME, which can calculate superconducting properties at different levels of approximation within the framework of isotropic Migdal-Eliashberg theory.
[1] A. B. Migdal, Zhur. Eksptl’. i Teoret. Fiz. Vol: 34, (1958).
[2] G. M. Eliashberg, Sov. Phys. - JETP (Engl. Transl.); (UnitedStates) 11:3, (1960).
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Electrochemical migration and its impact on reliability of printed circuit boards
Eva Kastenauer
Abstract: Printed Circuit Boards (PCBs) are essential in electronic devices. Modern PCBs are made of copper, patterned by etching and plating processes, which is separated by insulating fiberglass-reinforced epoxy resin. Since PCBs are difficult to repair or recycle (1), long service life is key to reducing environmental impact. Electrochemical migration (ECM) is among the most common failure modes found in PCBs. It is triggered by small amounts of water that are adsorbed in the prepreg. Once a current bias is applied, this combination of bias and moisture promotes the leaching of copper ions, which can form a conductive deposit, causing a fatal short-circuit (2, 3). Factors such as increased temperature, high-humidity environment and small conductor spacing, as well as certain process chemicals and prepreg compositions, have been found to accelerate ECM (4). ECM can manifest as conductive anodic filament (CAF) or dendrite formation (5, 6). Analyzing ECM is complex and time-consuming, usually requiring samples to be cut and examined using optical microscopy, thermal imaging, or fluorescence microscopy. Scanning electron microscopy techniques are used to understand the chemical makeup of the migration path. Improved understanding of ECM mechanisms allows for better modeling and simulation, enhancing the accuracy and speed of reliability analysis.
1. Ning, C.; Lin, C. S. K.; Hui, D. C. W.; McKay, G. Waste Printed Circuit Board (PCB) Recycling Techniques. Topics in current chemistry (Cham) 2017, 375 (2), 43. DOI: 10.1007/s41061-017-0118-7.
2. Medgyes, B.; Illés, B.; Berényi, R.; Harsányi, G. In situ optical inspection of electrochemical migration during THB tests. J Mater Sci: Mater Electron 2011, 22 (6), 694–700. DOI: 10.1007/s10854-010-0198-4.
3. He, X.; Azarian, M. H.; Pecht, M. G. Evaluation of Electrochemical Migration on Printed Circuit Boards with Lead-Free and Tin-Lead Solder. Journal of Elec Materi 2011, 40 (9), 1921–1936. DOI: 10.1007/s11664-011-1672-3.
4. Lee, E. L.; Goh, Y. S.; Haseeb, A. S. M. A.; Wong, Y. H.; Sabri, M. F. M.; Low, B. Y. Review—Electrochemical Migration in Electronic Materials: Factors Affecting the Mechanism and Recent Strategies for Inhibition. J. Electrochem. Soc. 2023, 170 (2), 21505. DOI: 10.1149/1945-7111/acb61a.
5. Zou, L. C.; Hunt, C. A new approach to investigate conductive anodic filament (CAF) formation. Soldering & Surface Mount Technology 2015, 27 (1), 22–30. DOI: 10.1108/SSMT-02-2014-0002.
6. Dominkovics, C.; Harsányi, G. Fractal description of dendrite growth during electrochemical migration. Microelectronics Reliability 2008, 48 (10), 1628–1634. DOI: 10.1016/j.microrel.2008.06.010.
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Pathway to High Temperature Superconductors: Theoretical Insights into BaSiH$_8$
Eva Kogler
Abstract: High-pressure hydrides are an excellent example of the success story of computational material design. Highly accurate and reliable ab-initio methods and increasing computational power made it possible to predict novel materials to guide experiments, which are often expensive and time consuming. In the theoretical analysis of materials, it is important to assess stability and metastability from thermodynamic, dynamic, and kinetic perspectives.
The investigation becomes particularly intricate for hydrogen-rich materials due to the light mass of hydrogen atoms, which can induce anharmonic and quantum ionic effects. Traditionally, studying these effects would require thousands or even hundreds of thousands of DFT calculations. However, the use of machine-learned interatomic potentials within the framework of SSCHA accelerates this process by more than 10$^4$ times, while maintaining DFT-level accuracy. One can therefore consider larger supercells and significantly improve the convergence of the calculations. By accounting for anharmonic and quantum ionic effects, a more precise estimation of stability and the critical superconducting temperature (Tc) can be achieved.
I will present the findings of our comprehensive investigation into the stability of BaSiH$_8$, a hydride superconductor with a Tc above 70 K. [1]
[1] Lucrezi et al., npj Computational Materials, 8(1):119, 2022 and Lucrezi et al., Commun. Phys. 6, 298, 2023
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Refill Friction Stir Spot Welding of AA1050 to Cu-ETP for hybrid busbar applications
Felix Schindler
Abstract: F. Schindler (a), S. Fritsche (a), B. Schweighofer (b), T. Weinberger (c), S.T. Amancio-Filho (a)
(a) Graz University of Technology, Institute of Materials Science, Joining and Forming, Graz, AT
(b) Graz University of Technology, Institute of Electrical Measurement and Sensor Systems, Graz, AT
(c) Stirtec GmbH, Kalsdorf bei Graz, AT
With the rising demand for electric vehicles, new technologies are essential for constant improvement, and the joining of aluminium to copper for hybrid busbar systems is a key factor towards lighter and more cost-effective designs. A parameter study was conducted on dissimilar refill friction stir spot welded joints between sheets of AA1050 and Cu-ETP, building on preliminary investigations that identified distinct areas of varying joining behaviour in relation to welding time, plunge depth, and tool rotational speed. Using a central composite design methodology, a quadratic regression model was developed, leading to an optimised parameter set that achieved 3.97 ± 0.16 kN in quasi-static lap shear testing. The failure modes of the joints were investigated, and microscopic characterisation (optical and scanning electron microscopy) was carried out to examine the formation of intermetallic compounds and the process-related material flow. A testing method was devised to measure the electrical resistance of the samples, demonstrating that the spot welds were relatively robust to parameter variations and exhibited suitable electrical conduction for industrial applications (achieving an electrical performance factor of 1.064 ± 0.004 for the optimised parameter set). Finally, as a proof of concept, a demonstrator component inspired by a hybrid busbar used in the automotive industry was manufactured using the insights gained from this research. |
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Metallographische Untersuchung von mittelalterlichem Schmiedeeisen Ein Vergleich zwischen Feuerwaffen und anderen Anwendungen
Florian Widlroither
Abstract: How was the material of medieval arquebuses be like, and was higher-quality iron used for them? To investigate this question, five different samples of wrought iron from the period between approximately 1480 and 1647 were analyzed using various methods, and the results were compared. The samples include a piece from a hook gun from the Styrian Armoury and wall anchors from the Ringelschmiedhaus in Thörl and the Styrian Armory.
The microstructure was characterized using light and scanning electron microscopy. To learn more about the mechanical properties, hardness measurements were carried out on all samples. Due to its size, the piece from the Styrian Armory also underwent an charpy impact test and a tensile test. Finally, a chemical analysis of the samples was conducted to qualitatively and quantitatively determine the trace elements in the iron.
Wie war das das Material mittelalterlicher Hakenbüchsen beschaffen und wurde dafür ein höherwertiges Eisen verwendet? Um dieser Frage auf den Grund zu gehen wurden 5 verschiedene Proben von Schmiedeeisen aus der Zeit von etwa 1480 bis 1647 mit verschiedenen Methoden untersucht und die Ergebnisse miteinander verglichen. Bei den Proben handelt es sich um ein Stück von einer Hakenbüchse aus dem Grazer Landeszeughaus und um Mauerschließen aus dem Ringelschmiedhaus in Thörl und dem Grazer Landeszeughaus.
Das Gefüge wurde mittels Licht und Rasterelektronenmikroskopie charakterisiert. Um mehr über die mechanischen Eigenschaften zu erfahren, wurde an allen Proben eine Härtemessung durchgeführt. An dem Stück aus dem Grazer Landeszeughaus konnte aufgrund seiner Größe auch ein Kerbschlagbiegeversuch und ein Zugversuch durchgeführt werden. Abschließend wurde noch eine chemische Analyse der Proben durchgeführt, um die Begleitelemente des Eisens qualitativ und quantitativ zu bestimmen.
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Joining of Wood-Polymer by Additive Manufacturing
Gean Marcatto, Institute of Materials Science, Joining and Forming
Abstract: Gean H. M. Oliveira1, *, Awais Awan1, Peter Auer1,2, Josef Domitner1,2, Sergio T. Amancio-Filho1, *
1Graz University of Technology, Institute of Materials Science, Joining and Forming (IMAT), Professorship “Aviation Materials and Manufacturing Techniques”, Kopernikusgasse 24/I, 8010 Graz, Austria
2Graz University of Technology, Research Group of Lightweight and Forming Technologies, Inffeldgasse 11/I, 8010 Graz, Austria
The growing need for sustainable lightweight materials in the transportation industry has driven the development of innovative hybrid structures. This study explores the potential of joining European beech wood with carbon fiber-reinforced polyamide (PA6-15CF) through an additive manufacturing technique known as AddJoining. Using fused filament fabrication (FFF), the polymer composite was directly printed onto untreated wood substrates. Quasi-static lap-shear testing revealed an ultimate lap-shear strength (ULSS) of 7.5 ± 1.1 MPa. Strong adhesion at the wood-polymer interface, attributed to micromechanical interlocking, was confirmed by microstructural analysis. Wood fibers remaining on the polymer surface indicate that micromechanical interlocking occurred as the molten polymer infiltrated the rough texture of the wood's natural surface. This, combined with favorable chemical compatibility between the materials, likely resulted in the formation of adhesive primary bonds at the wood-polymer interface. Additionally, localized transverse cracking in the PA6-15CF component was observed, potentially caused by stress concentrations and secondary bending effects arising from the disparity in material properties and the asymmetry of the single-lap joint geometry. These findings demonstrate that AddJoining is a promising manufacturing method for producing lightweight, sustainable wood-polymer hybrid joints, suitable for structural applications in environmentally conscious design.
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DACHS: A Database for Traceable Synthesis and Characterization
Glen J Smales, Brian R Pauw, Ingo Breßler, Julian Rosalie
Abstract: Ensuring reproducibility and traceability in materials synthesis remains a challenge compared to advances in characterization standardization. DACHS (Database for Automation, Characterization, and Holistic Synthesis) addresses this by providing a structured framework to track synthesis workflows alongside characterization data.
DACHS has been applied to 1,200 samples from 20 synthesis series, meticulously recording each synthesis parameter in a traceable manner. Beyond standard synthesis variables, DACHS captures often-overlooked details—such as bottle opening dates, lab temperature and humidity, injection speed, and solution age—which have proven crucial for understanding synthesis outcomes.
Characterization data, including SAXS/WAXS and microscopy, are integrated into DACHS, with all data explorable through an interactive dashboard for efficient visualization and analysis. By setting a new standard for modern, data-driven materials synthesis, DACHS provides a scalable and robust framework for handling large datasets in research. |
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Developing inoculation methods for digitally fabricated mycelium-based clay composites
Hana Vašatko, Institute of Architecture and Media
Abstract: Hana Vašatko (a), Dorothee Hippler (b), Milena Stavric (a)
(a) Graz University of Technology, Institute of Architecture and Media
(b) Graz University of Technology, Institute of Applied Geosciences
This research intersects experimental architecture, mineralogy, and mycology to develop new bio-based materials using digital technologies. These materials offer a sustainable alternative with the potential to replace conventional building materials in the future. A major challenge marks the absence of standardised methods for fabricating mycelium-based clay composites (MBCCs), which is still an unexplored field. Traditional inoculation methods from mycology, though well-suited for growing mushrooms, present specific limitations when adapted to MBCCs, especially within digital fabrication processes, such as 3D printing. The aim of this research is developing a new approach of inoculation by growing liquid mycelial cultures that are more suitable to the geometry of the inoculated objects, as opposed to the usual grain spawn inoculation. The liquid inoculum is applied on prefabricated and sterilised clay-based objects, rather than printing pre-inoculated, living material. In this way, we can actively control the growing environment of the objects, while successfully eliminating potential contamination. Scanning Electron Microscopy (SEM) imaging compares the growth patterns of both inoculation methods, revealing that grain spawn inoculation promotes dense mycelial growth around pores, while liquid inoculation results in uniform, grid-like networks. These findings provide valuable insights for scaling the fabrication process. Building on this valuable knowledge, future studies will investigate the mechanical effects of the two inoculation methods, beginning with compressive and tensile strength tests. Furthermore, we will contribute to developing a workflow for large-scale MBCC fabrication. |
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Development of a Lightweight Wing for Autonomous Sailing Drones
Helena Strniscak
Abstract: Development of a Lightweight Wing for Autonomous Sailing Drones
Strniscak, Helena (a), Oliveira, Gean H. M. (a), Amancio-Filho, Sergio T. (a)
a Institute of Materials Science, Joining and Forming, Professorship “Aviation Materials and Manufacturing Techniques”, Graz University of Technology (TU Graz), Graz, Austria
The rapid advancement of autonomous vehicle technology and environmental research has made sail drones crucial in marine research, surveillance, and offshore industries, requiring advanced materials for their construction. The High-Performance Sailing Team (HPS) at Graz University of Technology developed the Mola-Mola project to design autonomous sail drones, with the latest iteration, Mola-Mola 3, aimed at competing in the transatlantic Microtransat Challenge. This project focuses on the design and construction of the lightweight wing sail for Mola-Mola 3 [1]. The wing serves as a critical component, acting as the primary propulsion system, and its strength, efficiency, and durability are important for ensuring optimal performance in extreme marine conditions [2, 3]. Key objectives include analyzing sail forces, performing strength calculations, optimizing material selection, and conducting simulations of critical components. Material selection was guided by critical parameters such as density, cost, saltwater resistance, and UV durability, using GRANTA EduPack 2021 software. Simulations of the most stressed components, such as the mast and stringers, were conducted in Abaqus, providing insights into structural performance. To validate the materials chosen for critical parts, tensile tests were performed. The final step involved assembling the wing. The stringer was fabricated from plywood, while the mast and wing skin were constructed using carbon fiber reinforced polymer (CFRP) [4]. The stringer was fix to the mast using epoxy adhesive. The CFRP cloth was applied using a hand lay-up process, followed by vacuum bagging to ensure optimal resin distribution and consolidation.
[1] Sebastian Anton Bachl: Conception and investigation of a symmetrical wing profile as a sail drive for the autonomous sailing boat Mola-Mola 2, Institute of Mechanical Engineering and Information Systems, Graz University of Technology, August 2024
[2] Silva, M. F., Friebe, A., Malheiro, B., Guedes, P., Ferreira, P., & Waller, M. (2019). Rigid wing sailboats: A state of the art survey. Ocean Engineering, 187, 106150. https://doi.org/10.1016/j.oceaneng.2019.106150
[3] Trujillo, E., Nik, A. M., Campos, J., & Friebe, A. (2020). Experimental and numerical study of an autonomous sailboat prototype for ocean observation. Journal of Marine Science and Engineering, 8(1), 26. https://doi.org/10.3390/jmse8010026
[4] William d. Callister Jr.: Materials Science and Engineering : an Introduction, 7th edition, ISBN-13: 978-0-471-73696-7
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Optical lactate biosensor for microfluidic cell culture monitoring
Iga Malicka, Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Graz, Austria
Abstract: Monitoring the concentration of lactate in cell culturing can provide useful information about the state of cells. In the case of mitochondrial dysfunction, the metabolic pathway shifts from oxidative phosphorylation to glycolysis which rapidly increases lactate production. The majority of available lactate sensors is based on electrochemical detection [1]. Despite various assets of that approach, sensor integration into microfluidic chips involves rather complex multi-step procedures.
Previously, we presented an enzymatic optical glucose sensor that can be directly incorporated into microfluidic systems [2]. In this work, the same sensing concept was adapted to develop a phosphorescent biosensor for lactate. The sensor consists of oxygen sensitive particles and lactate oxidase, both immobilized in a polymeric matrix. Enzymatic conversion of lactate results in oxygen depletion at the sensor’s surface which is detected by a fiber optics oxygen meter. To limit the chemical degradation of lactate oxidase, a catalyst for the decomposition of hydrogen peroxide is added. Sensor integration is achieved by spotting the sensor cocktail onto a sealing tape or directly into the microfluidic chip. The spot size can be altered according to the width of the microfluidic channel. Additionally, the dynamic range of the sensor can be modified to a desired value by implementing porous diffusion membranes.
While developing the sensor, influence of various factors (e.g. pH, temperature, sensor size) on its performance was evaluated. Moreover, long-term sensor stability was investigated. The final system was successfully used for measuring lactate level in a drug toxicity study with a Liver-on-Chip system.
References
[1] S. Fuchs et al., ACS Biomater. Sci. Eng. 7 (2021) 2926 – 2948.
[2] S. Fuchs et al., Biosens Bioelectron. 237 (2023) 115491.
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Microstructure Characterization within ELISHA: ELectrIc current effects on the Self-Healing of Al alloys
Ilse Letofsky-Papst, Institute of Electron Microscopy and Nanoanalysis (FELMI)
Abstract: Microstructure Characterization within ELISHA: ELectrIc current effects on the Self-Healing of Al alloys
Ilse Letofsky-Papst, M. Cecilia Poletti, Gerald Kothleitner
Some materials exhibit self-healing properties, either during service, delaying failure, or after service, recovering damage. While well-established in polymers, this property remains largely unexplored in metals, despite evidence of self-healing potential in certain alloys under creep conditions. The ELISHA project aims to develop self-healing Al-alloys and restore creep-induced pores using electric currents or heat. Additionally, physical models will be developed to predict their creep performance.
In a first step, subproject 03 focuses on the ex situ microstructural characterization of the as-printed and heat-treated LPBF-printed AlCu4.5 alloy. The microstructural analysis at different heat treatment stages, as presented in this poster, forms the basis for future in situ heating and biasing experiments in a transmission electron microscope with atomic resolution.
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High Ionic Conductivity in Na3SbS4: The Dominant Role of Na-Ion Vacancies Over Structural Transition
Jana Königsreiter, TU Graz
Abstract: Jana Königsreiter, Bernhard Gadermaier, and Martin R. Wilkening
Institute for Chemistry and Technology of Materials, TU Graz
Na3SbS4 is a promising solid ion conductor for all-solid-state sodium batteries. Aliovalent substitution of Sb5+ with W6+ significantly increases its conductivity to 15 mS/cm, introducing (i) Na-ion vacancies and (ii) transforming the tetragonal phase to a nearly cubic structure, where the a- and c-lattice parameters approach unity. However, the relative contributions of these factors to the enhanced Na-ion diffusivity remain unclear. In this study, we synthesized Na3SbS4 and W-doped Na3SbS4 under different conditions to obtain materials with varying c/a ratios and Na-ion vacancies. Using 23Na NMR spin-lattice relaxation rate measurements and impedance spectroscopy, we demonstrate that Na-ion diffusivity is markedly higher in the W-doped, nearly cubic material. In contrast, undoped Na3SbS4 materials with different c/a ratios but no Na-ion vacancies show similar ionic conductivity. These results suggest that Na-ion vacancies play a more significant role in improving ionic conductivity than the structural transition from tetragonal to cubic. |
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Electrochemical Investigation of Symmetric Aminoquinones
Janine Maier, Institute of Bioproducts and Paper Technology, TU Graz
Abstract: Quinones have a wide range of valuable properties and potential applications in medicinal chemistry, materials science, optoelectronic devices, and batteries.[1] Molecular redesign using different functional groups, like amines, can optimize their properties and prevent unwanted side reactions. However, particularly the synthesis of aminoquinones can be challenging at times, and there is a need for simple and efficient routes to access these compounds without metal catalysts or halogenated starting materials.[2] Here, we demonstrate the synthesis and electrochemical characterization of a series of aminoquinones derived from renewable sources, namely vanillin or 2-methoxyhydroquinone.[3] We employ a series of primary and secondary amines, varying in their electronic situation as well as steric demand. Depending on the type of starting material, either the desired aminoquinone or the related Schiff-base adduct was obtained. The aminoquinones were further explored for their stability at different pH values. At extreme pH values, the deeply colored aminoquinones decompose, accompanied by decolorization of the solutions within a few minutes (pH 14) or hours (pH 1). At intermediate pH values (3-8) the aminoquinones are stable upon storage in solution, where they feature a quasi-reversible redox chemistry and fast, diffusion limited kinetics.[4]
[1] a) P. Lavayen, C. Yang, J. Larochelle, L. Liu, R. J. Tishko, A. C. P. de Oliveira, E. Muñoz, and E. Candelario-Jalil, Neurochem. Int., 165, 105508 (2023). b) L. Liu, W. Wu, J. Li, W. H. Jiao, L. Y. Liu, J. Tang, L. Liu, F. Sun, B. N. Han, and H. W. Lin, Biomed. pharmacother., 100, 417 (2018).
[2] A. H. Crosby and R. E. Lutz, J. Am. Chem. Soc., 78, 1233 (1956).
[3] a) N. Zhou, W. P. D. W. Thilakarathna, Q. S. He, and H. P. V. Rupasinghe, Front. Energy Research, 9 (2022). b) W. Schlemmer, P. Nothdurft, A. Petzold, G. Riess, P. Frühwirt, M. Schmallegger, G. Gescheidt-Demner, R. Fischer, S. A. Freunberger, W. Kern, and S. Spirk, Angew. Chem. Int. Ed., 59, 22943 (2020). c) M. Barbero, V. A. Papillo, A. A. Grolla, R. Negri, F. Travaglia, M. Bordiga, F. Condorelli, M. Arlorio, and G. B. Giovenzana, Eur. J. Org. Chem., 2020 (1), 136-139 (2020). b) M. Barbero, V. A. Papillo, A. A. Grolla, R. Negri, F. Travaglia, M. Bordiga, F. Condorelli, M. Arlorio, and G. B. Giovenzana, Eur. J. Org. Chem., 2020 (1), 136-139 (2020).
[4] S. Bayen, N. Barooah, R. J. Sarma, T. K. Sen, A. Karmakar, and J. B. Baruah, Dyes Pigm., 75, 770 (2007).
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Analysis of non-classical void nuclei on the basis of chemo-mechanical phase-field models
Kevin Pendl, Institute of Strength of Materials
Abstract: High vacancy concentrations in crystals, caused by e.g. irradiation or large plastic deformation, may lead to the nucleation and growth of voids. These phenomena are associated with irradiation-induced swelling and decisively influence the initial stages of ductile failure. Additionally, a comprehensive understanding of void nucleation in ductile failure requires coupling vacancy diffusion to the stress field and accounting for vacancy generation from plastic deformation. Classical nucleation theory (CNT) may be considered as one of the traditional modeling techniques, however, strong assumptions about the size and shape of nuclei are made as well as incorporating elastic effects remains a challenging task. In contrast, phase-field models (PFMs) offer a potential solution to these limitations through the derivation of non-classical nuclei, which can be interpreted as stationary distributions of the introduced total free energy.
In our recent work [1], we employed a modified gentlest ascent dynamics (GAD) [2, 3] to identify non-classical void nuclei within a chemo-mechanical PFM. The model features a coupled Cahn–Hilliard/Allen–Cahn PFM, capturing the kinetic interplay between vacancy diffusion and void evolution. Elastic coupling is realized through eigenstrains, which arise from the relaxation of the surrounding crystal lattice when an atom is removed. The eigenstrains are dependent on the introduced phase fields and are linked to the elastic strain field. We outline the formalism for deriving non-classical void nuclei from the governing phase-field formulation employing a modified GAD. The results are compared to predictions from CNT, the unstable behavior of the stationary non-classical nucleus distribution (saddle point) is illustrated, and factors influencing nucleus morphology, such as vacancy supersaturation and elastic coupling, are examined.
[1] K. A. Pendl and T. Hochrainer. Non-classical critical void nuclei from a vacancy-based chemo-mechanical phase-field model. Modelling and Simulation in Materials Science and Engineering (under review), 2025.
[2] W. E and X. Zhou. The gentlest ascent dynamics. Nonlinearity, 24(6):1831–1842, 2011. doi: 10.1088/0951-7715/24/6/008.
[3] L. Lunéville et al. Non-classical critical precipitates in a nucleation and growth regime: Reconciliation of simulation and experiment. Applied Physics Letters, 121(18):184102, 2022. doi: 10.1063/5.0122126. |
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Improvements on Tin Perovskite Solar Cells by Crystallization Mediators and Plasma-assisted Conversion
Kevin Pree, Jakov Tenžera, Thomas Rath, Gregor Trimmel, Institute for Chemistry and Technology of Materials
Abstract: The performance of tin perovskite solar cells is highly influenced by the quality of the perovskite crystals and their interfaces with charge-selective contacts. One critical factor in optimizing these materials is the use of crystallization mediators, which play a crucial role in controlling the growth and quality of tin perovskite films. This work focuses on investigating the effects of different precursor solutions, including various crystallization mediators, on the deposition, crystallization, and overall quality of tin perovskite absorber layers. By examining these processes in detail, the aim is to identify key correlations between material properties and solar cell performance. The ultimate goal is to enhance the efficiency and stability of tin perovskite solar cells by developing optimized strategies for film fabrication and crystallization, contributing to the advancement of this promising photovoltaic technology. Different combinations of solvents have been used in the open-air plasma-assisted crystallization of the perovskite layer. |
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Germanium-based IniSwitches: Towards New Photoresponsive Materials
Konstantin Knaipp, Institute of Physical and Theoretical Chemistry, Graz University of Technology
Abstract: Radical polymerization reactions can be induced with light by employing a photoinitiator. Acylgermanes have been established as efficient photoinitators across a wide range of wavelengths.[1] Recently it has been demonstrated that acylgermanes can be conjugated onto surfaces, anchoring the growing polymer chain and enabling facile access to functionalized surfaces.[2] Molecular photoswitches are compounds that can be “switched” between different states depending on the wavelength of illumination. One such molecule is azobenzene, which can be reversibly photoisomerized between its cis and trans isomer. Conjugating azobenzene to polymers gives access to materials that can undergo reversible phase changes when illuminated at different wavelengths, which has potential applications in the field of energy storage.[3]
In this study we present the first investigations on acylgermane-based IniSwitches; compounds that combine a photoinitiating acylgermane moiety and a photoswitching azobenzene moiety. We show possible synthetic pathways, investigate photochemical behavior and explore how this novel class of compounds gives access to photoswitchable polymer materials.
References:
[1] Radebner, J.; Eibel, A.; Leypold, M.; Gorsche, C.; Schuh, L.; Fischer, R.; Torvisco, A.; Neshchadin, D.; Geier, R.; Moszner, N.; et al. Angew Chem Int Ed Engl 2017, 56 (11), 3103-3107. DOI: 10.1002/anie.201611686.
[2] Muller, M.; Drusgala, M.; Fischer, R. C.; Torvisco, A.; Kern, W.; Haas, M.; Bandl, C. ACS Appl Mater Interfaces 2023, 15 (26), 31836-31848. DOI: 10.1021/acsami.3c05528.
[3] Imato, K.; Kaneda, N.; Ooyama, Y. Polymer Journal 2024, 56 (4), 269-282. DOI: 10.1038/s41428-023-00873-7.
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Alcohols in Lewis-base catalysed polyaddition reactions: The case of aliphatic isocyanates
Lena M. Hofbauer, Susanne Fischer, Christian Slugovc, Institute for Chemistry and Technology of Materials
Abstract: While the use of aliphatic alcohols as monomers in polyaddition reactions such as ring opening of epoxides or Michael chemistry is rather underdeveloped, alcohols are often used in the reaction with isocyanates to form poly(urethanes). For room temperature curing of aliphatic isocyanates, tin-based catalysis is still the state of the art. However, the development of fast curing tin-free formulations is an important goal for the practical application of this chemistry.1
In this contribution we present our results on Lewis base catalysis for the reaction of aliphatic isocyanates with alcohols at room temperature. Emphasis is placed on uncovering the role of the electronic properties of the alcohol on the rate of the reaction using different Lewis bases and dibutylin dilaureate (DBTL) as a reference catalyst. The results showed that none of the Lewis bases could compete with DBTL in catalytic activity. However, a strong dependence of the reaction rate on the acidity of the alcohol was found. More acidic alcohols (e.g. propargyl alcohol) react much faster than less acidic ones (e.g. propanol). This phenomenon is much less pronounced when DBTL is used as the catalyst.
Finally, we compare the reactivity of the alcohols in isocyanate chemistry with their reactivity with other electrohiles, namely epoxides and some Michael acceptors, and find different dependencies of the alcohols acidity on the reaction rate.2
1 Sardon, H.; Pascual, A.; Mecerreyes, D.; Taton, D.; Cramail, H.; Hedrick, J. L. Macromolecules 2015, 48, 3153. DOI: 10.1021/acs.macromol.5b00384
2 Fischer, S. M.; Kaschnitz, P.; Slugovc, C. Catal. Sci. Technol. 2022, 12, 6204. DOI: 10.1039/D2CY01335E
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Evaluation of (Sub)Microsecond TADF-Emitters as Molecular Thermometers
Lisa Eiber, Graz University of Technology, Institute of Analytical Chemistry and Food Chemistry
Abstract: Fluorescence lifetime imaging microscopy (FLIM) is a common technique used to investigate different cellular processes by visualizing the analyte. Therefore, sensitive dyes with very short lifetimes are needed. Thermally activated delayed fluorescence (TADF)-emitting dyes have proven to be highly suitable for optical sensing and imaging of temperature. [1] Such dyes however, typically show long lifetimes in the range of tens of microseconds to milliseconds, which is too long for FLIM applications. Furthermore, this leads to cross-sensitivity towards oxygen even in matrices of low oxygen permeability.
TADF-emitters with very short lifetimes might be able to overcome the above limitations and qualify for FLIM. Design of such emitters requires a precise manipulation of singlet- and triplet energy levels and control of intersystem crossing rates. This involves a reduction of the spatial separation of the highest occupied- and lowest unoccupied molecular orbital and the implementation of heavy atoms. This enables a finetuning of the analytical range and the luminescence lifetime of the dye.
Herein we report our investigation of several dyes which show very short TADF-lifetimes. They were successfully synthesized and then investigated for their photophysical properties and suitability for optical thermometry and imaging microscopy.
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[1] Russegger, A.; Debruyne, A. C.; Berrio, D. C.; Fuchs, S.; Marzi, J.; Schenke-Layland, K.; Dmitriev, R. I.; Borisov, S. M. Bright and Photostable TADF-Emitting Zirconium(IV) Pyridinedipyrrolide Complexes: Efficient Dyes for Decay Time-Based Temperature Sensing and Imaging. Advanced Optical Materials 2023, 11 (9). DOI: 10.1002/adom.202202720.
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Heat transport in crystalline organic semiconductors: coexistence of phonon propagation and tunneling
Lukas Legenstein, Institute of Solid State Physics
Abstract: Understanding heat transport in organic semiconductors is of fundamental and practical relevance. Therefore, we study the lattice thermal conductivities of a series of (oligo)acenes, where an increasing number of rings per molecule leads to a systematic increase of the crystals' complexity. Temperature-dependent thermal conductivity experiments in these systems disagree with predictions based on the traditional Peierls-Boltzmann framework, which describes heat transport in terms of particle-like phonon propagation. We demonstrate that accounting for additional phonon-tunneling conduction mechanisms through the Wigner Transport Equation resolves this disagreement and quantitatively rationalizes experiments. The pronounced increase of tunneling transport with temperature explains several unusual experimental observations, such as a weak temperature dependence in naphthalene's conductivity and an essentially temperature-invariant conductivity in pentacene. While the anisotropic conductivities within the acene planes are essentially material-independent, the tunneling contributions (and hence the total conductivities) significantly increase with molecular length in the molecular backbone direction, which for pentacene results in a surprising minimum of the thermal conductivity at 300 K.
preprint: doi.org/10.48550/arXiv.2412.05062 |
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Sustainable Synthesis of Organic Semiconductors for Organic Electronics
Magdalena Steinbrugger, Jakob Keler, Suman Mallick, Thomas Rath and Gregor Trimmel, Institute of Chemistry and Technology of Materials, Graz University of Technology
Abstract: The environmental impact of modern-day electronics throughout their lifecycle—manufacture, use, and disposal—has become a pressing global concern. GreenOMorph aims to radically reduce these impacts by developing innovative solutions that avoid using critical raw materials, minimize energy consumption and environmental impact.
Central to this approach is the development of sustainable, high-performance organic semiconductors (OSCs) for organic thin-film transistors (OTFTs) and organic electrochemical transistors (OECTs), which serve as the backbone of modern electronics. Among the known OSCs, pentacenes and thienoacene derivatives, such as C8-BTBT, and DNTT, stand out for their exceptional charge mobilities (µ = 10-20 cm²/Vs), achieved through the interplay between their molecular and crystal structures.[1] To address the environmental impact of current OSC synthesis, GreenOMorph aims for developing more sustainable synthetic pathways and green solvent processing, thus avoiding highly toxic chemicals and solvents.[2]
[1] B.D. Paulsen, K. Tybrandt, E. Stavrinidou, J. Nat. Mater. 2020, 19, 13–26.
[2] Li Ding, Zi-Di Yu, Xiao-Ye Wang, Ze-Fan Yao, Yang Lu, Chi-Yuan Yang, Jie-Yu Wang, Jian Pei, Chem. Rev., 2023, 123 (12), 7421-7497.
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Xanthates as powerful precursors for highly porous metal sulfides
Marco Sigl,(a) Melissa Egger,(a) Daniel Knez,(b) Fernando Warchomicka,(c) Heinz Amenitsch,(d) Gregor Trimmel,(a) Thomas Rath a), ICTM, Institute for Chemistry and Technology of Materials
Abstract: b) Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria
c) Institute of Materials Science, Joining and Forming, Graz University of Technology, Kopernikusgasse 24, 8010 Graz, Austria.
d) Institute of Inorganic Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
In heterogeneous (photo)catalysis, the efficiency depends on plethora of factors, like the absorption coefficent, bandgap alignment, stability and available surface area. Many of these parameters can be tackled by using metal sulfides like ZnIn2S4[1], CuInS2[2], Cu3BiS3[3], CuSbS2, Cu12Sb4S13[4] and AgBiS2[5], showing bandgaps in the lower visible range and high absorption coefficients above 105 cm-1. A problem specific to heterogeneous catalysis however, is that the activity is limited by the available reaction sites and thus by the surface area of the catalyst. To address this problem, we synthesized various metal sulfides from the corresponding metal xanthates. These metal xanthates provide both the metal and sulfur source, while reacting to metal sulfide and volatile decomposition products forming micro- or mesopores in the process. These pores can be controlled by the metal types and the corresponding xanthate side chains, which also provide control over the solubility of the precursors and thei conversion temperatures.[6] Furthermore, we can combine these micro- and mesopores with other sources of porosity like microsphere colloidal lithography to prepare hierarchically porous thin films, to even further increase the available surface area. Furthermore, we used the investigated ternary metal sulfides in dye degradation experiments with Rhodamine B (RhB) and Methylene Blue (MB) to show their applicability as photocatalysts.
[1] M. Sigl, M. Egger, F. Warchomicka, D. Knez, M. Dienstleder, H. Amenitsch, G. Trimmel, T. Rath, J. Mater. Chem. A 2024, 12, 28965.
[2] E. Vakalopoulou, T. Rath, F. G. Warchomicka, F. Carraro, P. Falcaro, H. Amenitsch, G. Trimmel, Mater. Adv. 2022, 3, 2884.
[3] T. Rath, J. M. Marin-Beloqui, X. Bai, A.-C. Knall, M. Sigl, F. G. Warchomicka, T. Griesser, H. Amenitsch, S. A. Haque, ACS Appl. Mater. Interfaces 2023, 15, 41624.
[4] T. Rath, A. J. MacLachlan, M. D. Brown, S. A. Haque, J. Mater. Chem. A. 2015, 3, 24155.
[5] E. Vakalopoulou, D. Knez, M. Sigl, G. Kothleitner, G. Trimmel, T. Rath, ChemNanoMat 2023, 9, e202200414.
[6] E. Vakalopoulo, T. Rath, M. Kräuter, A. Torvisco, R. C. Fischer, B. Kunert, R. Resel, H. Schröttner, A. M. Coclite, H. Amenitsch et al., ACS Appl. Nano Mater. 2022, 5, 1508.
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Additive manufacturing of the refractory-based, complex concentrated alloy Ti$_x$-Al$_{0.1x}$-Cr$_x$-Mo$_x$-Nb$_{0.5x}$ (at.%) using LPBF and in-situ alloying
Markus Maßwohl, Siegfried Arneitz, Marlene Eichlseder, Christof Sommitsch, Petra Spoerk-Erdely, Institute of Materials Science, Joining and Forming, TU Graz
Abstract: Complex concentrated alloys, whose alloying concept is based on the introduction of multiple principal elements, have been shown to exhibit remarkable mechanical and functional properties, making them attractive for advanced applications. However, the most common bulk production method, casting, involves multiple vacuum remelting steps to achieve material homogeneity. This approach is energy-intensive, can result in suboptimal microstructures related to strong segregation phenomena and large grain sizes, and imposes design limitations. Additive manufacturing techniques, such as laser powder bed fusion (LPBF), offer a promising alternative, since they allow the production of complex parts with a fine-grained microstructure while consuming less energy. The attractiveness of this technique can be further amplified by the usage of in-situ alloying, a method where the alloy is directly created inside the 3D-printing chamber, as in this case, by melting of the elemental powder blend. This eliminates the need for pre-alloyed powders, reducing energy consumption, providing a critical advantage when processing materials with high melting points.
This study investigates the fabrication of a Ti$_x$-Al$_{0.1x}$-Cr$_x$-Mo$_x$-Nb$_{0.5x}$ (at.%) alloy using LPBF and in-situ alloying. An elemental powder blend was selectively melted layer by layer using various parameter sets to optimize the outcome of the manufacturing process. The resulting samples were investigated in terms of porosity, homogeneity and phase composition. Porosity was assessed through light optical microscopy, while homogeneity and elemental distribution were examined using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The phase composition was characterized using synchrotron X-ray diffraction (SXRD).
In this poster presentation key findings on parameters influencing material homogeneity and chemical composition will be presented. Based on these results, further printing strategies were developed, forming the foundation for ongoing heat treatment studies.
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Homogenization of porous, intermetallic Ni$_3$Al fabricated by additive manufacturing and in-situ alloying
Marlene Eichlseder(1), Siegfried Arneitz(1), Andreas Stark(2), Christof Sommitsch(1), Petra Spoerk-Erdely(1), (1) Institute of Materials Science, Joining and Forming, TU Graz
Abstract: (1) Institute of Materials Science, Joining and Forming, TU Graz, (2) Institute of Materials Physics, Helmholtz-Zentrum Hereon, Germany.
Nickel is a common and cost-efficient catalytic material with various industrial applications. However, it comes with disadvantages such as poisoning and sintering at the elevated temperatures required for certain processes. Intermetallic Ni3Al has been found to exhibit catalytic properties comparable to pure Ni while being less prone to degenerating effects. Therefore, we have started to investigate potential approaches to fabricate a Ni3Al catalyst.
As a large surface area is crucial for catalysis, samples were produced utilizing additive manufacturing. In particular, laser powder bed fusion (LPBF) was used to create complex inner structures as well as a significant amount of open bulk porosity. Furthermore, in order to keep the fabrication route economically competitive, so-called in-situ alloying was used to print the samples. In-situ alloying refers to the procedure of mixing two elemental powders mechanically and creating the alloy during the printing process rather than using pre-alloyed powder.
The chemical composition of 76 at.% Ni and 24 at.% Al is very well-researched for catalysis, therefore the printing parameters for both dense and porous bulk samples were optimized for this composition. However, the printing parameters, especially those for the porous structure, yielded inhomogeneities with pronounced variations in the local chemical composition. During the printing process, the powder particles were melted, but solidified, before an equilibrium could be reached. Using X-ray diffraction, the phases Ni(Al), Ni$_3$Al, NiAl, Al$_3$Ni$_5$, and Al$_3$Ni were detected in these as-printed samples. To increase the phase fraction of Ni3Al and homogenize the microstructure, heat treatments were conducted. To obtain temperature and time-dependent information on the phase evolution, in-situ heating experiments were conducted in a dilatometer setup at the Hereon-run beamline P07B at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The data collected by means of high-energy X-ray diffraction offer valuable insights into the effect of the various heat treatments on the as-printed samples and allow us to draw conclusions as to their final catalytic properties.
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Gelectrode: A Wireless Tissue-Inspired Stimulator
Mathias Polz
Abstract: Wireless stimulation of excitable cells offers a promising alternative to traditional wired devices and imprecise non-invasive methods. Our aim is to develop tissue-inspired photovoltaic implants that convert light into localized electrical stimuli for nerves and brain tissue. Substrates based on poro-viscoelastic hydrogels mimic tissue properties to ensure seamless integration, optimize biocompatibility, and enhance mechanical and electrical coupling. Advanced organic photovoltaic materials, such as bulk heterojunction systems like PM6:Y6, enable precise and efficient stimulation using safe light intensities. Validation through mechanical and biological studies demonstrated the hydrogel’s ability to mimic adjacent tissue and the photovoltaic layer's potential to activate excitable cells, offering new approaches for treating neurological disorders and enhance brain plasticity. |
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Enhancing mechanical properties of polyamide 66 by means of carbon-based nanofillers
Matija Avbar, Institute of Materials Science, Joining and Forming (IMAT), Professorship “Aviation Materials and Manufacturing Techniques”, Graz University of Technology
Abstract: Avbar, M. 1; Marcatto, G. H. O1; Amancio-Filho, S. T.1
1Institute of Materials Science, Joining and Forming, Professorship “Aviation Materials and Manufacturing Techniques”, Graz University of Technology (TU Graz), Graz, Austria
Carbon-based nanofillers are highly effective in enhancing the mechanical properties of polyamide 66 (PA66), offering significant improvements even at low loadings. Literature highlights that optimal nanofiller concentrations, typically between 0.25% and 1 wt%, result in consistent enhancements in quasi-static mechanical properties. Notable increases in Young’s modulus (E) and in ultimate tensile strength (UTS) have been reported. Preliminary investigations employing melt mixing to produce PA66 nanocomposites reinforced with carbon nanotubes (CNTs) at loadings up to 1 wt% demonstrate an increase in Young’s modulus. However, reductions in ultimate tensile strength and strain at break are observed. Scanning electron microscopy (SEM) imaging of fracture surfaces reveals details about CNT dispersion and distribution within the matrix. These results highlight the potential and current challenges of incorporating carbon-based nanofillers into PA66, paving the way for the design of advanced nanocomposite materials. |
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Stochastic 3D modeling of hierarchically structured cathodes in lithium-ion batteries
Matthias Neumann, Institute of Statistics, Graz University of Technology
Abstract: A data-driven stochastic 3D modeling approach for hierarchically structured cathodes of lithium-ion batteries is presented. By means of stochastic 3D modeling, we generate virtual, but realistic, i.e., statistically similar, pore structures on the micro- and nanoscale. On the micro-scale, particle-based models are used, which mimic the arrangement of active material particles within the electrode. Moreover, stochastic models for the nanostructured porous active material particles as well as for the nanoporous binder-conductive additive phase have been developed and calibrated using 3D image data acquired by FIB-SEM tomography. The calibrated models are validated by morphological descriptors that have not been used for model calibration. Moreover, it is shown that effective macroscopic properties (such as effective electric conductivity and effective ionic diffusivity) are well reproduced in the model. Based on the developed models, a large range of virtual structures can be generated allowing for a resource-efficient quantification of the impact of morphology on effective macroscopic properties, which have a crucial impact on electrochemical processes in the cathode and thus on the performance of battery cells. |
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Trapping the key intermediate in nucleophile initiated Michael reactions
Matthias Steiner; Johann A. Hlina, Christian Slugovc
Abstract: Nucleophilic catalysis is used in carba-, thia- or oxa-Michael reactions as an alternative for base catalysis. First, a nucleophile reacts with the Michael-acceptor forming a zwitterionic species, which then acts as a base for deprotonating the carba-, thia- or oxa-donor molecules. The effectivity of nucleophilic catalysis is now depending on many parameters, most importantly the strength of the nucleophile, the electron deficiency of the Michael acceptor, the acidity of the Michael donor and the concentration [1].
Herein we try to further increase the mechanistic understanding of nucleophilic catalysis in Michael chemistry by studying the reaction of ortho-hydroxy substituted aryl phosphines with Michael acceptors, which generates stable and isolable zwitterions upon proton transfer from the OH-group.
[1] Fischer, S. M.; Renner, S.; Boese, A. D.; Slugovc, C. Beilstein J. Org. Chem. 2021, 17, 1689–1697. |
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Polymer Immobilized Metals for Heterogeneous Catalysis
Max Schmallegger, Institute of Physical and Theoretical Chemistry
Abstract: Polymer materials prepared through photochemical processes serve as effective and versatile supports for the incorporation and stabilization of catalytically active metallic species. We present two distinct approaches for preparing polymer-immobilized metals, which can be employed as efficient heterogeneous catalysts.
First, we describe a facile photochemical method for the one-step synthesis of well-defined metal-polymer nanocomposites. This approach utilizes Norrish Type I photoinitiators, which, upon light irradiation, undergo bond cleavage to produce two radicals, enabling simultaneous radical polymerization and metal reduction. The resulting composites were characterized using UV-VIS spectroscopy, powder XRD, and synchrotron (in situ) small-angle X-ray scattering. Their catalytic activity was evaluated in Suzuki coupling, CuAAC, and reduction reactions, employing Pd, Cu, and Ag nanoparticles as catalysts, respectively.
Additionally, we demonstrate the straightforward preparation of an AlCl3/polystyrene composite, which acts as an easily accessible catalyst for efficient solvent-free tetrazole synthesis and facilitates a simple work-up procedure. Its structure and properties were characterized using gas sorption analysis, XRD, and IR spectroscopy, and its efficacy was investigated in the preparation of aryl-substituted tetrazoles.
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In-situ $\mu$-CT: Microstructure of fibrous materials and its changes
Maximilian Fuchs, Institute of Solid State Physics
Abstract: M. Fuchs, W. Napetschnig, E. Baikova, R. Teubler, A. Serebrennikova, E. Machado Charry, U. Hirn, M. Neumann, K. Zojer
The Xray-microtomography device at the TU Graz is capable of determining, how the microstructure of materials changes under external stress. Here we demonstrate how the uptake of solvent vapors (including moisture) or liquids by fibrous porous materials can be monitored with time. We developed specific compartments and chambers that allow us to expose the sample to liquid or to vapor and to scan the microstructure at pre-defined times. Particularly for paper and webs of viscose fibers, such scans clearly show a swelling of the fibers. Using sophisticated statistical analysis tools, that we will showcase, the structural changes can be quantified and interpreted. |
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Mechanochemical Synthesis of Hydrogen-Bonded Organic Framework Enzyme Biocomposites for Enhanced Stability and Activity
Michael R. Hafner, Institute of Physical and Theoretical Chemistry, Graz University of Technology, Austria
Abstract: Hydrogen-bonded organic frameworks are an emerging class of porous materials with broad applicability in the fields of sensing [1], catalysis [2] and biocatalysis [3]. They are composed of organic molecules (linkers) with an aromatic core and various functional groups that can form hydrogen bonds [4]. Through the geometry of the organic linkers, pi-pi stacking of the aromatic part thereof and the directionality of the hydrogen bonds, 3-D networks are assembled [4]. Moreover, the synthesis takes place in aqueous solution at room temperature. Additionally, they are stable across a wide pH-range and against several common solvents [2,3]. Due to the geometry of the organic linkers and the directionality of the H-bonds, extended pores and channels are present in the material, which make it porous. Therefore, these kinds of materials are valuable candidates for enzyme encapsulation in the use of immobilised enzymes in biocatalysis [3].
However, in some cases the one-pot syntheses used to prepare HOF biocomposites can lead to the immobilization of enzymes close to the surface, and this can limit the protection against proteolytic agents (like the protease trypsin) [5]. Similarly, functional nanoparticles can be integrated into HOF biocomposites via one-pot syntheses, and they were found close to the surface of the HOF crystals. A possible reason for this could be the rapid crystallisation (seconds) of the HOF upon the combination of the organic linkers [3]. To modify the spatial distribution of exogenous entities into HOF crystals, the investigation of alternative synthetic methods was envisaged.
We explored an alternative synthetic method for the preparation of HOF biocomposites, namely mechanochemistry. Through this innovative approach, a homogeneous distribution of the enzyme throughout the bulk of the HOF particles was achieved. The enzyme@HOF biocomposites prepared via mechanochemistry showed higher protection against proteolytic agents, compared to the solution-based one-pot synthesis. This novel mechanochemistry-based synthetic approach could pave the way to new possibilities of combining HOFs and enzymes into innovative biocomposites.
References
[1] Y.-X. Lin, C. Jiang, Y.-B. Wang, J.-X. Wang, B. Li, G. Qian, J. Mater. Chem. A 2024, 12, 153–161.
[2] Q. Yin, P. Zhao, R.-J. Sa, G.-C. Chen, J. Lü, T.-F. Liu, R. Cao, Angew. Chem. 2018, 130, 7817–7822.
[3] W. Liang, F. Carraro, M. B. Solomon, S. G. Bell, H. Amenitsch, C. J. Sumby, N. G. White, P. Falcaro, C. J. Doonan, J. Am. Chem. Soc. 2019, 141, 14298–14305.
[4] S. A. Boer, M. Morshedi, A. Tarzia, C. J. Doonan, N. G. White, Chemistry A European J 2019, 25, 10006–10012.
[5] F. Carraro, M. Aghito, S. Dal Zilio, H. Wolinski, C. J. Doonan, B. Nidetzky, P. Falcaro, Small 2024, 2407487.
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Development of 3D-Printed Polysaccharide Biomaterials using a Dual-Enzyme Crosslinking System: Structural Stabilization, Mechanical Integrity and Swelling Behavior
Miriam Zeller, Florian Lackner, Karin Stana Kleinschek, Tamilselvan Mohan, Institute of Chemistry and Technology of Biobased Systems, Graz University of Technology, Stremayrgasse 9, A 8010 Graz, Austria
Abstract: The advancement of 3D printing technology has significantly enhanced the development of polysaccharide-based hydrogels for applications in tissue engineering and regenerative medicine.[1] This study focuses on the fabrication and characterization of 3D-printed polysaccharide biomaterials, specifically utilizing alginate modified with tyramine and nano fibrillated cellulose. Through an innovative enzyme-assisted crosslinking approach involving calcium ions and horseradish peroxidase (HRP) enzyme, structures with exceptional shape fidelity, mechanical and dimensional stability were achieved. The printed materials were rigorously analyzed for their swelling behavior, structural stabilization, mechanical strength, and morphological properties. The findings demonstrate the potential of these 3D-printed polysaccharide structures to serve as robust, biocompatible, and customizable scaffolds, mimicking the properties of native tissues such as cartilage and cardiovascular tissue.[2, 3]
[1] Hama, R.; Ulziibayar, A.; Reinhardt, J. W.; Watanabe, T.; Kelly, J.; Shinoka, T. Biomolecules 2023, 13 , 280.
[2] Leppiniemi, J. et al. ACS applied materials & interfaces 2017, 9 (26), 21959
[3] Heggset, E. B. et al. Cellulose 2019, 26, 581
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PDE learning for continuum dislocation dynamics
Niko Heinemann, Institute of Strength of Materials
Abstract: Plasticity in crystalline materials is the result of the motion and interaction of dislocations. Continuum Dislocation Dynamics (CDD), which relies on conservation laws and balance equations for alignment tensors, offers a promising approach by providing an efficient continuum-level description of dislocation behavior, reducing the computational complexity compared to Discrete Dislocation Dynamics (DDD). This approach has been particularly successful in single-slip systems. However, CDD faces challenges in multi-slip systems, where dislocations interact across multiple systems. In these cases, the precise evolution of alignment tensors during complex interactions remains insufficiently understood, limiting the CDD model’s predictive capacity [1].
To address these challenges and develop a more comprehensive description of plasticity, advanced data-driven methods based on DDD data are employed to estimate and incorporate multi-slip system interaction terms in the evolution equations of the alignment tensors. In the current work, a Koopman-based lifting technique for infinite-dimensional systems is applied to identify and model these interaction terms. This method uses a generalized extended dynamic mode decomposition for infinite-dimensional systems alongside the infinitesimal generator of the Koopman operator, which provides a promising tool for the extraction of missing source terms in the evolution equations directly from data [2]. A reduced system is employed to gain insights into the possible slip system interaction terms that can occur in CDD. Building upon this, interaction terms can be estimated for the full model. By matching these identified terms to empirical data, the model ensures that all relevant interactions are accounted for within the CDD framework, allowing for a more accurate representation of multi-slip dynamics. Capturing these interaction terms is crucial, as it completes the evolution equations for alignment tensors and brings the CDD framework closer to a fully predictive model of plasticity.
[1] T. Hochrainer. Multipole expansion of continuum dislocation dynamics in terms of alignment tensors. Philosophical Magazine, 95(12):1321–1367, 2015.
[2] A. Mauroy. Koopman operator framework for spectral analysis and identification of infinite-dimensional systems. Mathematics, 9(19):2495, 2021. |
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Basis Set Selection for Calculating Infrared Spectra of Hybrid Materials Using Periodic Structure Codes
Nina Strasser and Egbert Zojer, Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz
Abstract: Accurately predicting infrared spectra requires careful selection of computational methods and basis sets, particularly when modeling hybrid systems such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs), and molecular crystals. This study systematically investigates the convergence behavior of vibrational frequencies, equilibrium geometries and total energies using three distinct types of basis sets - plane waves, numeric atom-centered, and Gaussian-type - employed in commonly used periodic electronic structure codes such as VASP, FHI-aims and CRYSTAL23. |
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Energy Dissipation on h-BN: Electron-Phonon Coupling and Molecular Diffusion
Noah Hourigan, Philipp Seiler, Boyao Liu, Jack Kelsall, Anton Tamtögl, Institute of Experimental Physics
Abstract: Helium atom scattering offers a non-destructive method to probe energy dissipation processes and dynamical properties of material surfaces in the low meV region. Debye-Waller analysis determines the electron-phonon coupling, $\lambda$, through the thermal attenuation of specular helium reflection. The helium spin-echo technique can determine the characteristics of adsorbate diffusion on Å length and ps timescales. |
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Functionalized Electron-Rich Pyridines as Initiators for the Epoxy Homopolymerization
Peter Weiss; David Edinger, Christian Slugovc
Abstract: A simple and modular dialkylation of two electron-rich pyridine derivatives, namely 4-aminopyridine or 1,2,3,4-tetrahydropyrido[3,4-b]pyrazine, is achieved by aza-Michael reactions with electron-poor olefins (ethyl acrylate and acrylonitrile). Reducing the ester groups in the ethyl acrylate-derived compounds yielded the corresponding hydroxyl-containing derivatives. Subsequently, homopolymerization of phenyl glycidyl ether as well as an epoxy-alcohol polyaddition are catalyzed using the introduced compounds. As a reference catalyst, 4-dimethylaminopyridine is used. It is found that in all cases an irreversible termination of the polymerization at temperatures above 100 °C occurred. The decomposition is particularly rapid in the case of pyridine derivatives containing hydroxyl groups. In contrast, at a constant temperature of 100 °C, the latter compounds gave the fastest phenyl glycidyl ether homopolymerization and high conversions are found for all electron-rich pyridine derivatives. However, testing the catalysts at high alcohol concentrations at temperatures higher than 100 °C resulted in similarly moderate conversions in all cases. |
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Zerstörungsfreie Untersuchungen von Hakenbüchsen im Landeszeughaus Graz
Philip Scholte van Mast
Abstract: Ziel der vorliegenden Arbeit ist es, schmiedeeiserne Hakenbüchsen aus dem 15. Jahrhundert
zu untersuchen, um Erkenntnisse zu den Fertigungsmethoden von Büchsenmachern dieser Zeit
zu erlangen. Den Grundstock dieser Arbeit bildet dabei ein Artikel von DI Heinz Kloger aus
dem Jahr 2010, der eine Büchse aus der Pögl-Schmiede zu Thörl untersucht hat und entdeckte,
dass die Pögl-Schmiede eine bis dato unbekannte Fertigungsmethode verwendete. Bei dieser
Methode wurde die Platine vor dem Dornschmieden und Feuerverschweißen abgestuft, was
die Qualität der Schweißnaht erheblich erhöhte.
In Anlehnung an diesen Artikel wurden folgende Forschungsfragen definiert:
1. Wie wurden die Hakenbüchsen hergestellt?
2. Kann man am Kaliber eine Ausbauchung an der Stelle erkennen, an der das Pulver
gezündet wird?
Zur Beantwortung dieser Fragen wurden die Hakenbüchsen mit Ultraschall, Endoskop und einem Taststab zur Bestimmung des Kaliberverlaufs über die Seelenlänge untersucht.
Die Ergebnisse dieser Untersuchungen ließen eine Beantwortung der ersten Forschungsfrage
für 4 von 7 untersuchten Läufen zu. Davon wurden bei zwei Büchsen das aus der Literatur
bekannte ‚Dornschmiedeverfahren‘ mit abgeschrägter Platine nachgewiesen. Die anderen
Zwei – beide aus der Pögl-Schmiede – lieferten abweichende Untersuchungsergebnisse: Bei
einem Lauf wurde das durch DI Kloger entdeckte Verfahren nachgewiesen, beim Anderen ein
bisher unbekanntes Verfahren, bei dem eine dünnere Platine zweifach um einen Dorn geschmiedet wurde. Dies brachte im Vergleich zum Dornschmiedeverfahren mit abgeschrägter
Platine vermutlich Vorteile bei der Festigkeit. Diese Ergebnisse bestätigen einerseits die Resultate von DI Kloger, andererseits sind sie ein Indiz für den Innovationswillen der Pögls.
Die zweite Forschungsfrage muss negativ beantwortet werden, da sich in den Kalibermessungen keine eindeutigen Indizien für eine entsprechende Aufweitung im Bereich, in dem das Pulver gezündet wurde, finden ließen.
Im Zuge der Kalibermessungen fiel jedoch auf, dass bei zwei Läufen eine ähnliche Mündungsform auftrat, wie sie heutzutage bei Flinten zur Erhöhung der Reichweite verwendet wird. Um
festzustellen, ob dies von den Büchsenmachern beabsichtigt war und ob diese Läufe als Flinte
verwendet wurden, sind weitere Forschungen erforderlich. |
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Characterization of room temperature Sodium Sulfur Batteries using Small-Angle and Wide-Angle X-ray scattering (SAXS/WAXS) methods
Philipp Materna, Heinz Amenitsch, Institute for inorganic chemistry, TU Graz
Abstract: Sodium-sulfur (Na-S) batteries have attracted attention as promising candidates for large-scale energy storage due to their high theoretical energy density and low cost. Understanding the structural evolution and phase transitions during battery cycling is crucial for optimizing their performance and durability. In this study, we employed Small-Angle X-ray Scattering (SAXS) and Wide-Angle X-ray Scattering (WAXS) techniques to investigate the nanostructural changes occurring within Na-S batteries during charge-discharge cycles, as previously done for Li-S batteries.
SAXS provides insights into the morphology and size distribution of nanoparticles, while WAXS elucidates the crystalline structure and phase transitions within the battery components. By systematically analyzing the in operando scattering patterns obtained during battery cycling, we unveiled the evolution of sodium polysulfide species and the redistribution of sulfur within the porous carbon host cathode material.
Our results reveal the complex interplay between electrode morphology, sulfur reduction/oxidation kinetics, and electrochemical performance in Na-S batteries. Furthermore, the combination of SAXS and WAXS techniques offers a comprehensive approach to understanding the complex nanostructural dynamics underlying battery operation. This study provides valuable insights for the design and optimization of Na-S batteries for large-scale energy storage applications.
This research underscores the significance of advanced X-ray scattering techniques in unraveling the structural intricacies of battery materials and guiding the development of next-generation energy storage technologies.
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Photoactivation of dynamic thioester-networks with spatial resolution
Pia-Maria Egger (1,2), Elisabeth Rossegger (1), Sandra Schlögl (1), Gregor Trimmel (2), (1) Polymer Competence Center Leoben, (2) TU Graz
Abstract: Covalent adaptable networks (CANs) are crosslinked polymer structures that undergo dynamic bond exchange reactions when heated, enabling a reorganization of their topology. This unique characteristic allows these polymers to merge the durability and chemical resistance of thermosets with the processing versatility and recyclability of thermoplastics. [1]
In this study, we concentrated on thiol-thioester exchange reactions, which can occur rapidly even at low temperatures when appropriate catalysts are used, a property that is particularly relevant for biomedical applications. Initially, we produced vinyl monomers with thioester functionalities to promote network formation through a thiol-ene click reaction under visible light exposure. To achieve a spatial resolution of dynamic exchange reactions, a photobase generator (TMG-PLB) was synthesized. The purity of the monomers and the TMG-PLB was characterized by 1H- and 13C-NMR spectroscopy. By using equimolar amounts of thiol and vinyl monomer, 3mol% TMG-PLB and photoinitiator, the photosensitive resin was prepared. After curing the resin via 450 nm irradiation, spatially resolved activation of the photobase was accomplished through 365 nm UV-light illumination. To explore the resulting dynamic behavior, we conducted stress relaxation measurements at various temperatures. Additionally, a reshaping experiment was carried out to visualize the spatial activation of dynamic exchange reactions in a macroscopic manner.
[1] Bongiardina N. J.; Long K. F.; Podgórski M.; Bowman C. N., Macromolecules 2021, 54, 8341 |
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Welding time optimisation for increased efficiency of AA6082-T6 refill friction stir spot welds.
Riedl Helmut
Abstract: Riedl Helmut (a), Felix Schindler (a), Fritsche Sebastian (a), Thomas Weinberger (b), Sergio T. Amancio-Filho (a)
(a)Graz University of Technology, Institute of Material Science, Joining and Forming, Graz, AT
(b)Stirtec GmbH, Kalsdorf bei Graz, AT
The Refill Friction Stir Spot Welding (RFSSW) process is a solid-state joining process that is particularly suitable for aluminium alloys such as AA6061. The objective of this study is to minimize the welding time while ensuring maximum ULSF. To achieve this, various parameters of the welding process, including rotational speed, plunge depth and tamp depth, are systematically varied and optimized using a design of experiments approach. Experimental tests and microstructural analyses were used to identify the combinations of welding parameters that allow both high-quality welds -i.e., defect free and with high quasi-static strength - at short cycle times. Welding times of less than 1 s were achieved while maintaining the quasi-static mechanical properties of the joint. The results enable a wide range of industrial applications, in particular by increasing the efficiency and process stability for AA6061 RFSSW joints. |
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micro CT Graz
Robert Schennach
Abstract: 13 Institutes from three Universities (TUG, KFU, MUG) came together to acquire a state of the art micro CT machine. To accommodate all the specifications within the consortium we bought 2 machines. Since January 2022 we are performing experiments for colleagues within the consortium as well as outside of the consortium.
We bought a TESCAN UniTOM HR and a TESCAN UniTOM XL. Both machines were designed to make in situ experiments. The HR machine has a voxel resolution of about 0.8 nm in 3D and the XL machine can achieve about 1 µm resolution in 3D.
For further information please contact Robert Schennach or Eduardo Machado. |
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Investigating the fibrillation process and the characteristics of nanocellulose obtained through high-pressure homogenization
Simon Brunner, IBioSys
Abstract: Simon Brunner(1), Hannah Seifried(1),
Florian Lackner(1), Thomas Harter(2), Ulrich Hirn(2), Rupert Kargl(1), Karin Stana Kleinschek(1)
1)Institute for Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
2)Institute of Bioproducts and Paper Technology (BPTI), Inffeldgasse 23, 8010, Graz, Austria.
Nanocellulose has attracted significant attention due to its outstanding properties, including high mechanical strength, low density, large surface area, and biodegradability. [1] These properties can be significantly influenced by chemical modifications. A promising way to produce nanocellulose is high pressure homogenization (HPH). HPH is a mechanical process that employs pressures up to 1200 bar to break down materials into nanoscale sizes. The process involves pumping the material through a narrow gap, thereby generating intense shear forces. The pressure level and the number of passes can be adjusted. It is possible to continuously produce 20 g dry mass of nanomaterial within hours. The nanocellulose can for instance be used as rheological modifier, for coatings or in 3D bioprinting.
The structure of cellulose varies depending on its source, whether derived from plants, bacteria, or algae. Crystallinity, molecular weight, the arrangement of cellulose microfibrils, and the presence of lignin, hemicellulose, other biopolymers and small molecules influence the nanocellulose production process and the properties of the final products. Hence, it is beneficial to gain further knowledge about defibrillation, and the properties of the products depending on the feedstock, and its pretreatment.
In this poster presentation, the fibrillation process was examined depending on different pretreatments [2] and pressure levels during HPH, using refined Eucalyptus Kraft pulp as a precursor material. The pretreatments investigated were oxidations using Fenton´s reagent or TEMPO, 2,2,6,6-Tetramethylpiperidinyloxy, and hydrolysis using enzymes. The concentration of the nanosized fractions was determined by centrifugation analysis, and the size by light microscopy.
[1] Li, T.; Chen, C.; Brozena, A. H.; Zhu, J. Y.; Xu, L.; Driemeier, C.; Dai, J.; Rojas, O. J.; Isogai, A.; Wågberg, L.; Hu, L., Developing fibrillated cellulose as a sustainable technological material. Nature 2021, 590 (7844), 47-56.
[2] Hannah Seifried, Bachelorthesis (2024), Investigation of Pretreatment Processes for the Production of Nano Fibrillated Cellulose through High Pressure Homogenization, IBIOSYS, Supervisors: Univ.-Prof. Dr.rer.nat. Karin Stana Kleinschek, Dr. techn. Florian Lackner.
[3] Desmaisons, J., Boutonnet, E., Rueff, M., Dufresne, A., & Bras, J. (2017). A new quality index for benchmarking of different cellulose nanofibrils. Carbohydrate Polymers, 174, 318–329.
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Growing metastable surface structures
Simon Hollweger, Anna Werkovits, Oliver T. Hofmann, Institute of Solid State Physics, TU Graz
Abstract: Organic molecules adsorbed on inorganic substrates are well known for growing a variety of different polymorphs on the surface. It is of interest to be able to grow a specific structure with promising interface properties. However this is easier said than done, as these different structures are usually metastable surface structures and not accessible during a standard growth procedure at a certain temperature and pressure. Only thermodynamic favorable polymorphs emerge on the surface. Nevertheless, in this study we propose a growth procedure that is capable of forming a metastable surface structure. With targeted temperature and pressure changes, the system can be brought out of thermodynamic equilibrium and a transformation to the metastable target polymorph is triggered. As a proof of principle, this procedure is demonstrated on a simple microscopic interface model of planar molecules adsorbing on a square lattice. The growth simulations were conducted within a kinetic Monte Carlo (kMC) framework and we were able to show that a metastable upright standing structure of the planar molecules can be formed. |
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Refinement of perovskite film crystallization in lead-free tin halide perovskite solar cells
Stefan Moscher
Abstract: Stefan Moscher (1), Sebastian Mairinger (1), Lukas Troi (1), Fernando Warchomicka (2), Gregor Trimmel (1), Thomas Rath (1)
(1) Institute for Chemistry and Technology of Materials, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
(2) Institute of Materials Science, Joining and Forming, Graz University of Technology, Kopernikusgasse 24, 8010 Graz, Austria
Significant advancements have been made in perovskite solar cells in recent years, with impressive efficiencies exceeding 26% [1] now being achieved. However, as the absorber materials used in these cells contain lead, which has harmful effects on both humans and the environment, researchers are focused on replacing the toxic lead and developing lead-free perovskite systems.
Tin has emerged as a promising alternative, with efficiencies already exceeding 15% [2]. It offers several advantages: it is cost-effective, non-toxic, and has electronic properties similar to those of lead. However, challenges remain, such as the rapid oxidation of Sn2+ to Sn4+ in tin perovskite layers and the limited durability of tin halide perovskites against environmental factors like temperature, oxygen, and humidity. Therefore, further research is crucial to enhance efficiency and improve long-term stability.
The antisolvent treatment during perovskite film crystallization is a key process that significantly impacts the properties of the perovskite film, thus playing a crucial role in addressing the challenges mentioned earlier. This work aims to explore the effects of different antisolvents on perovskite crystallization. Preliminary findings using the environmentally friendly antisolvent diethyl carbonate [3] suggest that commonly used antisolvents like chlorobenzene and toluene could potentially be replaced, as diethyl carbonate leads to more defined perovskite grains.
Another focus of this work is to investigate the impact of large A-cations, such as phenethylammonium (PEA) and its derivatives, as well as conjugated diammonium cations, on the material and photovoltaic properties of tin perovskites. Studies on PEA and its derivatives, which lead to quasi-2D perovskites, show a significant improvement in solar cell performance, reaching up to 12.5%, compared to similarly processed conventional 3D perovskites, alongside promising stability under inert conditions.
References:
[1] https://www.nrel.gov/pv/assets/pdfs/best-research-cell-efficiencies.pdf, NREL-Chart.
[2] J. Chen, et al., Nat. Photon., 2024, 18, 464–470.
[3] Z. Zhang, et al., Energy Environ. Sci., 2023, 16, 3430-3440.
This work has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101084422.
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Synthesis and application of Fluorene-based non-fused-ring acceptors for organic solar cells
Suman Mallick, Virginia Lafranconi, Thomas Rath and Gregor Trimmel, TU Graz
Abstract: Most high-performing non-fullerene acceptors that have recently emerged for application in organic solar cells are based on fused rings as the central unit, typically requiring multi-step reactions that inevitably increase the overall cost of the target molecules. Conversely, non-fused-ring acceptors (NFRAs) offer significant advantages, including easier synthesis, higher yields and improved stability, facilitating the production of cost-effective OSCs.[1] In this work, a pair of new Fluorene-based non-fused acceptors, called FHM-F and FHM-Cl, featuring an acceptor-donor-acceptor (A-D-A) architecture was synthesized through a three-step synthesis with high yields. Starting with a fluorene core, a Suzuki coupling reaction was used to introduce thiophene groups on both sides of the core. Followed by a Vilsmeier-Haack reaction in which an aldehyde group was added to the thiophene rings. Finally, a Knoevenagel condensation was performed, resulting in the electron-accepting end groups being attached to the molecule. Afterwards, solar cells based on these molecules were fabricated and optimized, reaching a power conversion efficiency (PCE) of 10.7% - 8%. A detailed study revealed that superior light absorbance and solid-state packing result in better efficiency for the FHM-Cl-based solar cells compared to the fluorinated derivative.
[1] Li et al., J. Mater. Chem. C, 2023,11, 15426-15434 |
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Luminescent (Surface-Anchored) Metal Organic Frameworks for Sensing of Oxygen
Theresa Mautz
Abstract: Theresa Mautz (a), Georg Schwendt(a), Christian Slugovc(b), Sergey Borisov(a)
a) Institute of Analytical Chemistry and Food Chemistry
b) Institute for Chemistry and Technology of Materials
Metal Organic Frameworks (MOFs) have emerged as a promising class of sensing materials, including those for oxygen measurements. In particular, MOFs based on porphyrins, specifically metal(II)-tetrakis-(4-carboxyphenyl)porphyrin (M(II)TCPP, where M = Pt or Pd), and Zr6 clusters have demonstrated remarkable sensing properties. Besides high thermal stability and permanent porosity, these materials offer high accessibility to gases while retaining the characteristic photophysical properties of porphyrins, which makes them particularly interesting for optical sensing.
In this study, we report novel crystalline MOFs with new porphyrinic building blocks bearing electron-withdrawing substituents, showing promising sensitivity to oxygen. Furthermore, Surface-Anchored MOFs (SURMOFs) composed of Pt(II)TCPP and indium-oxo clusters were fabricated on functionalized glass substrates, with their oxygen sensitivity optimized through tuning of fabrication parameters. The layer-by-layer dipping procedure was employed to immobilize the SURMOFs directly on the substrate, yielding a homogeneous surface with sufficient stability to facilitate the measurement of oxygen at trace levels.
References:
1) T. Burger, M.V. Hernández, C. Carbonell, J. Rattenberger, H. Wiltsche, P. Falcaro, C. Slugovc, S. Borisov, ACS Appl. Nano Mater. 2023, 6, 248-260
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Transforming Post-Consumer Textile Waste into Sustainable Packaging Materials
Thomas Harter, Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria
Abstract: T. Harter, A. Wagner, A. Weissensteiner, U. Hirn
Institute of Bioproducts and Paper Technology, Graz University of Technology, Inffeldgasse 23, 8010 Graz, Austria.
Environmental challenges associated with textile waste demand effective strategies for resource recovery and impact mitigation. This study explores the mechanical processing of post-consumer cotton and viscose textiles for application in paper-based packaging materials, addressing both waste management and sustainable packaging.
Textile waste was mechanically refined using standard laboratory equipment to produce a fibrous suspension for papermaking. Pre-treatment steps, including adjustments to scrap size (5–20 mm), were applied to enhance energy efficiency. The resulting fibres, with an average length-weighted fibre length of 1.8 mm, were used in papermaking trials.
Integration trials with industrial recycled paper stock showed that adding 30% recycled textile fibres improved the tensile strength of packaging materials without increasing density. These results highlight the potential of incorporating textile waste into circular production systems.
This poster demonstrates the feasibility of adapting conventional mechanical processing to convert post-consumer textiles into raw materials for the paper packaging industry. By addressing textile waste and promoting sustainable packaging, this approach offers a pathway to more circular material cycles. |
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Chemical Modification of Chitosan: A Versatile Strategy for Developing Bioactive Thin Films and Bulk Materials
Tobias Dorn, Herwig Prasch, Tobias Steindorfer, Andre Culum, Martin Thonhofer, Karin Stana Kleinschek, Tanja M. Wrodnigg, Rupert Kargl, TU Graz, Institute of Chemistry and Technology of Biobased Systems
Abstract: Chitosan, a polysaccharide consisting of beta-1,4-D-glucosamine, has found extensive use in different fields, from water & waste treatment over food additives to biopharmaceutical applications. While this biopolymer has many desirable properties, like good biocompatibility and intrinsic antibacterial properties, chemical modifications can tailor it for specific purposes. [1] Many different methods have already been developed to attach different residues to the polysaccharide, either by one of the alcohols or the primary amino group at position C-2. [2]
We are interested in the study of solid-liquid interfaces of modified oligo- and polysaccharides, which play an important role in e.g. cell adhesion and biological recognition processes. [3] Therefore, we wanted to create a straightforward way of covalently linking different residues, like enzyme inhibitors, to either chitosan thin-films or bulk material (Figure 1). By using different azido modified linkers, a variety of suitable propargyl containing target molecules can be synthesized and used for the polysaccharide modification by a copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC). Synthetic as well as analytical details with different techniques, like QCM-D, AFM and Fluorescence Spectroscopy, will be presented.
[1] M. Rinaudo, Prog. Polym. Sci. 2006, 31, 603–632.
[2] P.S. Bakshi, D. Selvakumar, K. Kadirvelu, N.S. Kumar, Int. J. Biol. Macromol. 2020, 150, 1072–1083.
[3] E. Armingol, A. Officer, O. Harismendy, N. E. Lewis, Nat. Rev. Genet. 2021, 22, 71–88. |
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Neuroimprint: Organic neuromorphic devices by direct 3D nanoimprinting
Tobias Pötzelsberger (a), Barbara Stadlober (b), Gregor Trimmel (a), Andreas Petritz (b), Thomas Rath (a,b)
Abstract: (a) Institute for Chemistry and Technology of Materials, Graz University of Technology, Graz, Austria
(b) JOANNEUM RESEARCH Forschungsgesellschaft mbH, MATERIALS Institute for Sensors, Photonics and Manufacturing Technologies, Weiz, Austria
Organic thin-film transistors (OTFTs), organic electrochemical transistors (OECTs) and organic diodes (ODs) on flexible substrates are essential components for emerging neuromorphic devices, which can be considered as a promising solution for future flexible intelligent systems, such as flexible e-skins, human-machine interfaces and soft robots. The main remaining challenges in the fabrication of neuromorphic devices are either low performance and reproducibility, or the inability to fabricate them cost-effectively at large scale. Nanoimprint lithography (NIL) has emerged as a promising fabrication method to overcome these challenges. However, the current state of OTFTs and OECTs fabricated by NIL still requires wet chemical lift-off or etching methods.
Therefore, the main objective of this work is to fabricate OTFTs, OECTs and ODs on flexible substrates using a direct 3D nanoimprinting process without wet chemical lithography steps, which we call "DINOFED". Only one imprint step is required to define high resolution source/drain patterns with small separations (< 1 µm) that are self-aligned to the highly crystalline organic semiconductor layer (OTFTs) or electroactive polymer (OECTs), resulting in organic transistors with small channel length L and ultra-precise definition of width W. The DINOFED process fulfils all the requirements for "next generation flexible electronics", being large area, high throughput, high resolution and inherently self-aligned.
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Concrete corrosion analysis using optical chemical sensors and imaging
Torsten MAYR, Institute of Analytical Chemistry and Food Chemistry, TU Graz
Abstract: Bernhard Müller1, Leonard Sterz1, Isabel Galan3, Cyrill Grengg3, Marlene Sakoparnig2, Florian Mittermayr2, Joachim Juhart2 and Torsten Mayr1
1 Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Graz, Austria
2 Institute of Technology and Testing of Building Materials, Graz University of Technology, Graz
3 Institute of Applied Geosciences, Graz University of Technology, Graz, Austria
Introduction
Corrosion-related damages on concrete infrastructure account globally for several billion US dollars annually. Roughly 38% of these costs could be saved by the application of optimized materials and/or more efficient monitoring technologies. Currently, the most commonly used methods to assess the state of a concrete structure in terms of carbonation and chloride penetration, are phenolphthalein coloration and silver nitrate titration, respectively. However, the accuracy of the methods and the correlation of the obtained results with the actual state of the considered structure in terms of potential damage are constantly being questioned.
Methods
Optical chemical sensors are applied based on luminescent pH and chloride sensitive dyes, to quantitatively access the pH evolution and chloride concentration of cement-based construction materials. Dual lifetime referencing was applied for chemical imaging and sensor probes. For this method a fluorescent pH or chloride indicator dye (short lifetime) is combined with a phosphorescent reference dye (long lifetime) with similar spectral properties.
Results
We present high resolution pH imaging, demonstrated on various real concrete samples with different levels of carbonation and a comparison with the standard method (phenolphthalein coloration). We show that the imaging method provides high alkalinity pH-profiles of carbonation with a higher level of information than the standard method. Using this technique, we critically discuss crucial aspects of pH measurement, which have to be reconsidered when determining the pH of concrete structures. We also show an optical chloride sensor suitable for the measurement of released chloride from concrete powder samples and point out the challenges of sample preparation.
The promising results show that the application of this novel methodology will allow for a better assessment of the concrete structures’ state and for a better understanding of the processes taking place in cementitious matrices during hydration and exposure to the environment. The methodology has the potential to enable field measurements with a faster detection and on-sight decision making on the status of buildings.
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Tuning MAF Biocomposites with Multivariate Ligands for Enhanced Enzymatic Performance
Verena Lipic(a,b), Mercedes Linares-Moreau(a), Eva Maria Steyskal(b), Roland Würschum(b), Paolo Falcaro(a)
Abstract: (a) Institute of Physical and Theoretical Chemistry, Graz University of Technology, Austria
(b) Institute of Materials Physics, Graz University of Technology, Austria
Metal-Organic Frameworks (MOFs) are extended network materials comprising metal nodes and multitopic organic ligands, exhibiting a porous structure. A subclass of MOFs, designated as Metal-Azolate Frameworks (MAFs), can be combined with a multivariate synthesis, thereby facilitating the incorporation of a multitude of distinct azolate ligands as building blocks (MTV-MAFs). This approach preserves the material's intrinsic properties while optimizing the pore environment and enhancing specific characteristics, such as hydrophobicity. [1] In recent years, there has been a notable increase in interest in the use of MAFs for the protection of biomacromolecules. MAFs offer a promising platform for enzyme encapsulation, maintaining enzyme structure and protecting them from harsh environmental conditions. [2] This study explores the synthesis of enzyme@MTV-MAF biocomposites through the incorporation of different ligands to create an isoreticular structure. The interactions between the enzyme and the MTV-MAF biocomposite were analyzed by investigating various ligand ratios and their effects on crystallinity, chemical composition, enzymatic activity, and encapsulation efficiency. The results demonstrate a non-linear relationship between enzymatic activity and the utilized ligand ratios. This resulted in an approximately 41% enhancement of the enzymatic activity of the biocomposite compared to that of the free enzyme, without the use of additives that are commonly employed to enable the formation of the MOF. The development of an additive-free highly active enzyme@MTV-MAF system, with an optimized ligand ratio will increase its potential for use in sensing and catalysis applications.
[1] Y. Li, et al. J. Am. Chem. Soc. 2021, 143, 15378.
[2] W. Liang, et al. J. Am. Chem. Soc. 2019, 141, 2348. |
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Flavin-based crown ethers with ion-sensing properties
Vojtech Krusbersky, Faculty of Chemistry, Brno University of Technology; iBioSys, TU Graz
Abstract: Vojtech Krusbersky (1,2), Jan Richtar (1), Karin Stana Kleinschek (2), Jozef Krajcovic (1), Rupert Kargl (2)
(1) Faculty of chemistry, Brno University of Technology, Purkynova 464/118, 612 00 Brno
(2) Institute for Chemistry and Technology of Biobased Systems, Technische Universität Graz, Stremayrgasse 9, 8010 Graz
Crown ethers are a versatile group of macrocyclic hosts which have been widely used for various applications in ion selective electrodes as sensors, as extracting agents or as chemotherapeutics due to their antitumor properties etc. [1] Flavins are a family of bio-inspired compounds derived from riboflavin which are known for their interesting optical behavior and catalytic properties among other important attributes. It is supposed that crown ethers can work as ion sensors upon attachment to flavin-based molecules [2] or enhance the photocatalytic efficiency during the hydrogen generation process.
A series of flavin-crown ether conjugates has been prepared by stepwise synthetic pathway. The series consists of four already prepared distinctive molecules varying in the aromatic system of the flavin and crown ether cavity size while the synthesis of another four derivatives containing specific functional groups is in progress. Furthermore, optical characterization of prepared derivatives in terms of UV-VIS absorption and fluorescence measurements including experiments with addition of selected metal ions has been carried out.
Prepared molecules have shown high responsivity to the ion presence, especially the addition of Na+, K+ or Ca2+ ions leads to significant enhancement of the fluorescence intensity, in some cases even the maximal emission wavelength has been shifted. According to the size of their cavity, flavin crown derivatives proved selectivity towards particular cations.
Some of the prepared molecules contain amino functional group which has been used for their covalent attachment to the carboxylic groups of sodium alginate. Two types of the conjugates have been synthetized, isolated and characterized in terms of their degree of substitution. Those systems are intended for ionic cross-linking sensing by change in fluorescence intensity and/or spectral shift upon complexation of calcium ions which are used for alginate cross-linking. Their fluorescence behavior is to be deeply examined; however, first measurements show response of the system to calcium ions respective to their concentration.
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Fabrication and Performance of Supercapacitor Electrodes with TPU Binder
Wiktoria Żyła
, Graz University of Technology, Institute for Chemistry and Technology of Materials
Abstract: Graz University of Technology, Institute for Chemistry and Technology of Materials
Poznan University of Technology, Faculty of Chemical Technology
Supercapacitors are important energy storage devices capable of delivering energy at a very fast rate, making them ideal for applications like electric vehicles and renewable energy systems. They are constructed with two electrodes separated by an electrolyte and a porous separator, enabling charge storage through electrostatic and electrochemical processes.
The electrodes are typically made from high-surface-area materials like activated carbon, graphene or metal oxides. The selection of electrode materials and their fabrication play a crucial role in enhancing the capacitive performance of SCs [1]. Electrodes of SCs must provide thermal stability,
high SSA, corrosion resistance, high electrical conductivity, appropriate chemical stability, and suitable surface wettability. They should also be low-cost and environmentally benign [2]. Since the electrode is the core component of an SC, the electrode’s structural design substantially determines an SC’s overall
performance [3].
In general, supercapacitor electrodes are prepared from a mixture of three components: an active carbon (e.g. YP-80F), a conductive additive like carbon black (e.g. SUPER C65) and a polymeric binder (e.g. PTFE or PVDF). The method of electrode fabrication depends on the assembly of the capacitor, whether in a Swagelok or pouch cell configuration [4].
The role of the binder in an electrode is to hold the active materials, conductive additives, and current collectors together, ensuring structural integrity and preventing the components from separating during the charge/discharge cycles. It also helps maintain good adhesion between the active material and the current collector, facilitates the formation of a cohesive electrode structure, and improves the overall mechanical stability of the electrode. Additionally, the binder aids in distributing the conductive additives uniformly throughout the electrode, enhancing electrical conductivity.
In this study, there were developed electrodes using a binder from the thermoplastic polyurethane elastomer (TPU) group. The resulting electrodes demonstrated superb mechanical
properties over standard ones made with binder from fluoropolymers group (PTFE, PVDF), while the electrochemical parameters did not deviate from the norm in any way.
[1] Lai L.; Yang S.; et al.; Preparation of supercapacitor electrodes through selection of graphene surface
functionalities; ACS Nano.; 2012; 5941-5951.
[2] Forouzandeh P.; Kumaravel V.; Pillai, S.C. Electrode Materials for Supercapacitors: A Review of Recent
Advances; Catalysts; 2020; 969
[3] Yu Minghao; et al.; Thin-Film Electrode-Based Supercapacitors; Joule; 338-360
[4] Arunkumar M.; Amit P.; Importance of Electrode Preparation Methodologies in Supercapacitor Applications;
ACS Omega; 2017; 8039-8050 |
