275003 research outputs found
Sort by
Hydrogel-based MPI phantoms
No full textThe validation and performance comparison of imaging modalities, particularly magnetic particle imaging (MPI), requires standardized procedures and phantoms. A challenge for MPI phantoms is the incorporation of structures smaller than 1 mm to demonstrate the high-resolution capabilities, while excluding magnetic or electrically conductive materials. A hydrogel-based phantom is presented, specifically designed for evaluating an in-house developed MPI scanner. Conventional phantom production methods typically involve hollow bodies filled with a magnetic nanoparticle (MNP) solution. As an extension, additive manufacturing enables precise geometric realization by printing phantoms as hollow bodies, allowing for flexibility in intricate structures. An alternative option is the direct 3D printing of phantoms by integrating the MNPs into the print material. Here, a resolution phantom is presented that has been directly manufactured via semi-solid extrusion, utilizing a suspension of MNPs in a hydrogel. In this initial experiment, a self-sealing phantom holder incorporating a circular print bed with a diameter of 29 mm was developed for integration with a bioprinter and hydrogel used. The imageable ink suspension was synthesized by combining the hydrogel, with ~110 mg of MNPs. The phantom was designed with four lines converging from the center at uniform 24° angular spacing, originating at a radius of 4.1 mm, extending 7.3 mm in length, and maintaining a thickness of 0.4 mm. The print was completed using a 3 ml pneumatic printhead with a 0.2 mm (27G) nozzle. The printed phantom was imaged using the MPI scanner, with slice images obtained by a custom hybrid reconstruction method closely resembling the phantom and demonstrating high imaging quality. The presented work provides a robust foundation for future studies and considerations aimed at advancing the production of MPI phantoms by leveraging the unique capabilities of additive manufacturing. High-resolution phantoms created with tuneable materials can efficiently address the rigorous requirements of various imaging.7S
The integration of a ferroelectric memory module into the back end of line (BEoL) of the XFAB XT018 technology for the realization of 1T1C-FeFETs Integration eines ferroelektrischen Speichermoduls in das BEoL der XFAB XT018 Technologie zur Realisierung von 1T1C-FeFETs
No full text41742
Semiconducting Oxide - Based Micro- and Nano-Sensors for Environmental and Biomedical Monitoring
No full textNanosensors and microsensors are important for environmental and biomedical monitoring due to their extraordinary properties. In this work sensor devices are fabricated for the detection of H2 gas and ethanol vapors. These devices are based on ZnO single nanowires, heterostructures composed of TiO2/ZnO columns doped with Cd, as well as TiO2/CuO:Ni, Ag and on a functionalization with Pd and other noble nanodots
Design and Implementation of Non-prehensile Manipulation Strategies
No full text6778Grasping of objects is not always feasible for robot manipulators, e.g., due to their geometric properties. Non-prehensile manipulation strategies can enable manipulators to successfully move these objects around. We discuss strategies for non-prehensile manipulation and focus on the investigation of such manipulation strategies based on open-and closed-loop control based on force torque measurements. The design of grippers for moving objects is also an important factor that is evaluated. The strategies are implemented and evaluated in simulation and on a KUKA LWR4+ manipulator arm
405 nm diode laser system for curing UV adhesives based on embedded sidelight-activated polymer optical fibers
No full textWithin this work, an optical system was developed for coupling 405 nm laser radiation into a bundle of polymer optical fibers (POF) for a UV curing application. Traditional UV curing methods require at least one transparent joining partner, which limits their use in certain industrial applications. To enable efficient light coupling even between non-transparent materials, a novel bonding process has been developed that uses sidelight-activated POF woven into a fabric. By lateral emission from the fabric, the radiation reaches the bonding zone, so that the adhesive is cured over a large area. The optical system aims to achieve homogeneous illumination in the bonding zone by employing a diode laser, which offers advantages over traditional LED sources, particularly in terms of absorption efficiency of UV adhesives. The system is characterized by its coupling efficiency and the feasible homogeneity of the intensity profile in the image plane. Both quantities have been determined experimentally and by simulation with Zemax OpticStudio, achieving a coupling efficiency of up to 74% and a homogeneity exceeding 95% in the focal plane. Further investigation into the distribution of defects inside the fiber revealed that specific parameters significantly influence the homogeneity of lateral light emission. The results indicate that a tailored defect configuration can optimize the curing process, paving the way for future applications in industrial adhesive bonding. The findings underscore the potential for commercialization of this innovative optical coupling system within manufacturing sectors requiring efficient and large-area UV curing solutions.2
An In Vitro Assay to Quantify Effects of Micro- and Nano-Plastics on Human Gene Transcription
No full text122131In today’s age, plastic waste is a major problem for our environment. The decomposition of plastic waste causes widespread contamination in all types of ecosystems worldwide. Micro-plastics in the lower micrometer size range and especially nano-plastics can become internalized by cells and thus become a threat to human health. To investigate the effects of internalized micro- and nano-plastics on human gene transcription, we used an in vitro assay to quantify CREB (cAMP response element binding protein) mediated transcription. Here we show that CREB mediated gene expression was mainly but not exclusively induced by phosphorylation. In addition, the amount of CREB affected transcription was also studied. We were also able to show that the strong CREB mediated stimulation of transcription was diminished by micro- and nano-plastics in any chosen setting. This indicates a threat to human health via the deregulation of transcription induced by internalized micro- and nano-plastics. However, this established quantifiable in vitro transcription test system could help to screen for toxic substances and non-toxic alternatives.2
Subjective Evaluation of Filter- and Optimization-Based Motion Cueing Algorithms for a Hybrid Kinematics Driving Simulator
No full text16191626Interactive driving simulation has become a key technology to support the development and optimization process of modern vehicle components and driver assistance systems both in academic research and in the automotive industry. However, the validity of the results obtained within the virtual environment depends essentially on the adequate reproduction of the simulated vehicle movements and the corresponding immersion of the driver. For that reason, specific motion platform control strategies, so-called Motion Cueing Algorithms (MCA), are used to replicate the simulated accelerations and angular velocities within the physical limitations of the driving simulator best possible. In this paper, we present the design and evaluation of a subjective comparison of three different filter- and optimization-based MCA resulting from previous research. For that purpose, a Human-in-the-Loop experiment was conducted with 27 participants in four typical driving situations, using a hybrid kinematics motion system as an application example. The statistical analysis of the study proves that the optimization-based algorithm is preferred by the subjects regardless of the presentation sequence and the respective driving maneuver, while the filter-based approaches differ only insignificantly in their ranking. Results thus correlate with the findings of an objective evaluation of the control quality and identify further potentials for improving the driving experience
New Current Limiting Control for Grid-Forming Converter under Unbalanced Faults
No full text416422In the future, most power systems will rely on converter based generation. In order to guarantee stable operation so-called grid-forming converters were developed. In contrast to synchronous generators, the behaviour of converters is mainly dependent on its control algorithm and not by its physics. This offers a wide range of opportunities for shaping the control in the desired manner. The disadvantage of low overcurrent capability can be overcome by oversized power electronics or by appropriate controls. In this paper we present a control scheme based on the virtual synchronous machine with an approach for overcurrent protection in positive- and negative-sequence. The proposed approach can limit fault currents successfully and keeps its grid-forming functionality during the fault. Furthermore prioritization of active and reactive power in positive- and negative-sequence during fault is possible and good transient stability can be observed. The effectiveness is shown in MATLAB/Simulink and laboratory tests
Emulsion and interfacial properties of blended potato-lupin protein systems
No full textThe demand for plant-based proteins in emulsified foods has grown, necessitating deeper insights into how individual components and blends of plant proteins behave in oil-water systems. We examined potato (PPI) and lupin protein isolate (LPI), alone and in blends, at varying concentrations (1.0 %, 0.5 %, 0.1 %, 0.01 %) in oil-in-water emulsions produced by microfluidisation. Emulsions were analysed for droplet size distribution, and the protein content and protein composition of the aqueous phases were determined. Additionally, interfacial tension (IFT) was measured using pendant drop tensiometry. At 1.0 % total protein concentration, PPI formed small droplets (dx(50) = 0.83 ± 0.05 µm), whereas LPI exhibited median particle sizes around 3.45 ± 1.95 µm. The trend reversed at 0.1 % protein concentration. Blended systems showed significant droplet aggregation. Pendant drop tensiometry indicated that PPI effectively lowered IFT (9.19 ± 0.07 mN/m at 1.0 % total protein after 120 min), although adequate protein concentrations were necessary for a rapid decrease. LPI reduced IFT more rapidly at lower concentrations but maintained a higher IFT after 120 min compared to PPI at 1.0 % (11.55 ± 0.52 mN/m). In blends, the strong tension-lowering effect of PPI dominated at higher protein concentrations, while LPI fractions reduced IFT more rapidly at lower concentrations, highlighting a concentration-dependent interaction. Protein composition analysis confirmed that key PPI fractions readily adsorbed at the interface, while blending promoted depletion of selected lupin fractions from the continuous phase. The findings suggest that combining potato and lupin proteins can be used to tune emulsion properties in a concentration- and blend-ratio-dependent manner, offering valuable insights for formulating plant-based emulsions.737Part
