Recent Submissions
Impact of interstitial carbon on local lattice distortions in CoCrFeMnNi high-entropy alloys
(2026) Smekhova, Alevtina; Kuzmin, Alexei; Muralikrishna, G. Mohan; Welter, Edmund; Levcenko, Sergiu; Körmann, Fritz; Ikeda, Yuji; Divinski, Sergiy V.
Here, we explore component-dependent local lattice distortions in polycrystalline, equiatomic, face-centered cubic CrMnFeCoNi high-entropy alloys and their modifications induced by dilute interstitial carbon. Multi-edge extended X-ray absorption fine structure spectroscopy combined with reverse Monte Carlo analysis reveals that the Cr component experiences the most substantial local distortions, independent of the temperature of prolonged annealing treatments (993 K or 1373 K) and the nominal carbon content (0 to 0.8 at.%). The static disorder around Cr atoms was found to increase markedly and monotonically upon carbon alloying, whereas Mn, Fe, Co, and Ni demonstrate weaker and non-monotonic tendencies. The carbon-induced lattice distortions extend over several coordination shells, indicating the pronounced effect of the carbon presence on the local environment around Cr absorbers. First-principles density functional theory and finite-temperature molecular dynamics simulations confirm the greater impact of carbon on the local lattice distortions around Cr than around the other 3dconstituent elements, based on the previous finding that carbon preferentially occupies Cr-rich interstitial sites. These results provide decisive hints towards the atomistic origin of the non-monotonic diffusion behavior previously reported for carbon-doped CrMnFeCoNi alloys, and are noticeable for understanding the carbon-induced phase transitions in compositionally complex systems.
Effective dynamics and fluctuations of a trapped probe moving in a fluid of active hard discs
(2023) Jayaram, Ashreya; Speck, Thomas
From biotechnological residues to biodegradable printed circuit boards : aspergillus niger mycelium as a structural support material
(2026) Oehlsen, Nina; Wachsmann, Sebastian B.; Fauser, Dominik; Glauche, Florian; Laschat, Sabine; Selbmann, Franz; Steeb, Holger; Árki, Pál; Glöser-Chahoud, Simon; Stegbauer, Linus
The electronics industry urgently seeks sustainable, biodegradable alternatives to conventional substrates for printed circuit boards (PCBs) to reduce the environmental impact of electronic waste and CO2 emissions. Here, we introduce a biobased, plastic-like material derived from Aspergillus niger mycelium, AnimatRT. This material is produced from residual biomass generated in industrial citric acid production, offering a circular-economy approach. The raw mycelial biomass, consisting of spherical pellets, is processed via mold casting and air-drying, consolidating the pellets into a dense, plastic-like monolith (1.23 g cm-3).When formed into sheets, AnimatRT serves as a viable substrate for low-complexity PCB fabrication, allowing for direct ink writing and manual soldering of electronic components. Although its electrical properties are lower than those of FR-2 (flame retardant 2), a common, low-cost PCB laminate made of paper bonded with a phenolic resin, it remains suitable for low-frequency and proof-of-concept applications and, on average, has 56% lower embodied carbon. The mycelium boards disintegrate in water, allowing recovery of operative electronic components, whose functionality was demonstrated by re-soldering them onto a conventional PCB. The material exhibits high mechanical performance, with compressive strengths of up to 121 MPa, a flexural modulus of 2.3 GPa, and a flexural strength of 30 MPa. It is fully biodegradable (ISO 20200), redispersible in water, has low flammability, and favorable thermal insulation properties (0.21 W (mK)-1). Heat treatment at 120 °C enhances the mechanical properties, improves water resistance, and slows biodegradation. This study demonstrates the first use of biotechnology-derived A. niger mycelium as a biodegradable substrate for PCBs, addressing circularity and end-of-life challenges in electronics.
Time-delay interferometry infinity for tilt-to-length noise estimation in LISA
(2023) Houba, Niklas; Delchambre, Simon; Hechenblaikner, Gerald; Ziegler, Tobias; Fichter, Walter
Broadening of microwave heating beams in the DIII-D tokamak by edge turbulence
(2023) Brookman, Michael; Holland, Lou; Thomas, Matthew Bryn; Austin, Max E.; Barada, Kshitish; Gentle, Kenneth W.; La Haye, Robert John; Leddy, Jarrod; Petty, Craig; Rhodes, Terry L.; Yan, Z.; Vann, Roddy G. L.; Köhn-Seemann, Alf
Rebound effects of digital textile microfactories in fashion, a system dynamics study of CO2 emissions
(2026) Martinez‐Jaramillo, Juan Esteban; Stütz, Luis; Tilebein, Meike
The fashion industry's high resource use and globalised supply chains generate environmental degradation through overproduction, waste and pollution. Digital Textile Microfactories (DTMFs) are promoted as a more sustainable alternative because they enable fast, digitalised and often localised production, but lower costs and a greener image may also trigger rebound effects. We develop a stylised system dynamics model of a T‐shirt market in a fictional city to analyse how DTMF diffusion may affect market behaviour and CO2‐eq emissions over time. The model represents feedbacks between production capacity, prices, sustainability perception, overconsumption and emissions and is used to simulate a baseline diffusion scenario and policy variants with price competition and an introductory subsidy. The results show that a technology shift towards DTMFs alone is insufficient to reduce emissions, because increased demand and overconsumption can outweigh per unit efficiency gains, which underscores the need for complementary demand side measures.
Controlled feeding facilitates the development of a robust production process for terpolymeric polyhydroxyalkanoates
(2026) Achenbach, Birk; Tamang, Pravesh; Leonhardt, Steven; Tovar, Günter E. M.; Zibek, Susanne
Polyhydroxyalkanoates (PHAs) are a promising class of biodegradable and sustainable biopolymers. However, the current use of PHA is limited by its restricted availability, which is deplorable, as novel PHA variants such as copolymers or terpolymers could offer improved material properties. In this study, we report the production of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate‐co‐4‐hydroxyvalerate) (PHBVV) terpolymer with high 3‐hydroxyvalerate (3HV) content using Cupriavidus necator. A fully controlled feeding strategy, based on the pH‐ and pO2‐signal, was successfully implemented and validated in 7.5 and 42‐L bioreactors, enabling controlled delivery of the growth‐inhibiting substrate levulinic acid. A maximum biomass of 40.2 ± 0.9 g L-1 with 75% CDW PHA was obtained, corresponding to a yield of 0.32 ± 0.02 gPHA gLA−1. Importantly, the process enabled the production of PHBVV with a high 3HV content of 38%–46% and a 4HV content of 1%-2% at both production scales. Beyond demonstrating scalable PHBVV production in stirred tank bioreactors, this work provides a comprehensive comparative dataset, including specific growth rates, substrate uptake rates, yield coefficients, and respiratory activity. The findings presented here constitute both a methodological framework for scaling and process automation of PHBVV production and a valuable reference for the future optimization of PHA bioprocesses.
Emissive liquid crystalline boron C,N‐chelates : synthesis, self‐assembly, and photophysical properties
(2026) Müller, Franziska; Feucht, Falk; Beck, Alexander; Seher, Ramona; Zens, Anna; Kästner, Johannes; Molard, Yann; Laschat, Sabine
A library of novel phenylpyridine‐based boron C,N‐chelates bearing a mesogenic unit was synthesized and investigated to clarify how the chain type, length, and number, as well as the boron substitution (BH2 vs. BMe2) influence the mesomorphic and photophysical behavior. All BH2 derivatives exhibited SmA or N phases even with short alkyl chains, whereas BMe2 analogues remained nonmesomorphic unless a semi‐perfluorinated chain was introduced, demonstrating the strong influence of boron substitution on mesophase formation. All compounds displayed intense blue emission in solution, with spectral properties primarily determined by the boron C,N core and only minor shifts induced by variation in the mesogenic unit in agreement with complementary DFT calculations. Quantum yields reached up to 100% in solution. These results demonstrate that mesomorphic behavior can be introduced and tuned while preserving the excellent photophysical performance of the boron‐C,N‐chelate system.
Optimisation and evaluation of pre-design models for offshore wind turbines with jacket support structures and their influence on integrated load simulations
(2014) Schafhirt, Sebastian; Kaufer, Daniel; Cheng, Po Wen
In recent years many advanced load simulation tools, allowing an aero-servo-hydroelastic analyses of an entire offshore wind turbine, have been developed and verified. Nowadays, even an offshore wind turbine with a complex support structure such as a jacket can be analysed. However, the computational effort rises significantly with an increasing level of details. This counts especially for offshore wind turbines with lattice support structures, since those models do naturally have a higher number of nodes and elements than simpler monopile structures. During the design process multiple load simulations are demanded to obtain an optimal solution. In the view of pre-design tasks it is crucial to apply load simulations which keep the simulation quality and the computational effort in balance. The paper will introduce a reference wind turbine model consisting of the REpower5M wind turbine and a jacket support structure with a high level of detail. In total twelve variations of this reference model are derived and presented. Main focus is to simplify the models of the support structure and the foundation. The reference model and the simplified models are simulated with the coupled simulation tool Flex5-Poseidon and analysed regarding frequencies, fatigue loads, and ultimate loads. A model has been found which reaches an adequate increase of simulation speed while holding the results in an acceptable range compared to the reference results.
Simulation of a 5MW wind turbine in an atmospheric boundary layer
(2014) Meister, Konrad; Lutz, Thorsten; Krämer, Ewald
This article presents detached eddy simulation (DES) results of a 5MW wind turbine in an unsteady atmospheric boundary layer. The evaluation performed in this article focuses on turbine blade loads as well as on the influence of atmospheric turbulence and tower on blade loads. Therefore, the turbulence transport of the atmospheric boundary layer to the turbine position is analyzed. To determine the influence of atmospheric turbulence on wind turbines the blade load spectrum is evaluated and compared to wind turbine simulation results with uniform inflow. Moreover, the influences of different frequency regimes and the tower on the blade loads are discussed. Finally, the normal force coefficient spectrum is analyzed at three different radial positions and the influence of tower and atmospheric turbulence is shown.