Ulm University of Applied Sciences

Sicks B., Hessling M., Stucke-Straub K., Kupferschmid S., Lotfi R.

Background and Objectives: The cornea protects the eye from external influences and contributes to its refractive power. Corneas belong to the most frequently transplanted tissues, providing a last resort for preserving the patient’s vision. There is a high demand for donor corneas worldwide, but almost 4% of these transplants are not eligible due to microbial contamination. The objective of this study is to ascertain the suitability of 222 nm Far-UVC irradiation for the decontamination of corneas without damaging corneal endothelial cells. Materials and Methods: To assess the destructive effect of irradiation and, thus, identify the applicable dose needed to decontaminate the cornea without interfering with its integrity, 141 porcine corneas were irradiated with 0, 60 or 150 mJ/cm2 at 222 nm. In the second step, a series of 13 human corneas were subjected to half-sided irradiation using 15 or 60 mJ/cm2 at 222 nm. After five days of in vitro culturing, the endothelial cell density of the non-irradiated area of each human cornea was compared to the irradiated area. Results: Irradiation with up to 60 mJ/cm2 had no detectably significant effect on the cell integrity of human corneas (p = 0.764), with only a minimal reduction in cell density of 3.7% observed. These findings were partially corroborated by tests on porcine corneas, wherein the variability between test groups was consistent, even at increased irradiation doses of up to 150 mJ/cm2, and no notable effects on the irradiated porcine endothelium were monitored. The efficacy of the antimicrobial treatment was evident in the disinfection tests conducted on corneas. Conclusions: These initial irradiation experiments demonstrated that 222 nm Far-UVC radiation has the potential to decontaminate the cornea without compromising sensitive endothelial cell viability.

Sattler T., Gottschalk S., König H., Braun T., Büchele G., Denkinger M., Fleiner T., Nerz C., Rapp K., Schäufele M., Werner C., Dams J.

Abstract Background Fear of falling (FoF) is estimated to be prevalent in over 50% of older adults and several studies suggest that it negatively affects health-related quality of life (HrQoL). Unlike previous studies that examined only few mediating variables, this study aimed to develop a more comprehensive path model explaining the association between FoF and HrQoL. Methods A theoretical path model was developed based on existing evidence and expert feedback and fitted to cross-sectional baseline data on 385 community-dwelling (pre-)frail older adults from the PromeTheus randomized controlled trial using robust weighted least squares estimation. FoF and HrQoL were operationalized by the Short Falls Efficacy Scale International and EQ-5D Index, respectively. The model included potential explanatory pathways through physical activity (German Physical Activity Questionnaire for middle-aged and older adults), physical capacity (Short Physical Performance Battery), physical performance (Late-Life Function and Disability Instrument [LLFDI] function component), disability (LLFDI disability component – short form), and affect (visual analogue scales on ‘happiness’, ‘sadness’, ‘calmness’ and ‘tension’). Age, sex, education, and previous falls were considered as covariates. Results The model demonstrated good fit to the data and the remaining direct effect of FoF on HrQoL was small (β=-0.05). Physical capacity and physical performance were the most important mediators (combined indirect effect of β=-0.17, accounting for > 50% of the total effect). Pathways of minor individual relevance (e.g. through disability or affect) contributed considerably to the total indirect effect when combined. Controlling for sociodemographic data and previous falls only had minor effects on model fit and path coefficients. Conclusion Physical capacity and physical performance are particularly important levers for reducing the impact of FoF on HrQoL through interventions. However, the other pathways also had a considerable influence when taken together. Hence, research on the association of FoF and HrQol should acknowledge the complexity of causal pathways that may explain this association and not neglect minor pathways. The proposed model should be tested on an alternative sample, using longitudinal data, and extended to include additional explanatory factors (e.g. activity avoidance). Trial registration German Clinical Trials Register, ID: DRKS00024638, https://drks.de/search/en/trial/DRKS00024638, date of registration: March 11th 2021.

Das A., Schlüter S.

In this work, we introduce an innovative approach to managing electricity costs within Germany’s evolving energy market, where dynamic tariffs are becoming increasingly normal. In line with recent German governmental policies, particularly the Energiewende (Energy Transition) and European Union directives on clean energy, this work introduces a risk management strategy based on a combination of the well-known risk measures of the Value at Risk (VaR) and Conditional Value at Risk (CVaR). The goal is to optimize electricity procurement by forecasting hourly prices over a certain horizon and allocating a fixed budget using the aforementioned measures to minimize the financial risk. To generate price predictions, a Gaussian process regression model is used. The aim of this hybrid approach is to design a model that is easily understandable but allows for a comprehensive evaluation of potential financial exposure. It enables consumers to adjust their consumption patterns or market traders to invest and allows more cost-effective and risk-aware decision-making. The potential of our approach is shown in a case study based on the German market. Moreover, by discussing the political and economical implications, we show how the implementation of our method can contribute to the realization of a sustainable, flexible, and efficient energy market, as outlined in Germany’s Renewable Energy Act.

Hessling M., Noller K., Sicks B.

AbstractThe application of touchscreens in the public and healthcare sectors is increasing worldwide. Their use by different people allows the unintentional spread of pathogens. The combination of UVC LEDs and a quartz plate appears to make it possible to rapidly and automatically disinfect touchscreens between different users without harming the human operator.

Chen S., Urban K., Rusnák J., Heilscher G.

Kim B., Belkilani K., Heilscher G., Otto M., Huh J., Suh D.

Halbauer C., Capanni F., Paech A., Knop C., Merkle T., Da Silva T.

Abstract Objectives Helical plating is an established method for treating proximal humeral shaft fractures, mitigating the risk of iatrogenic radial nerve damage. However, biomechanical test data on helical plates under physiological load condition is limited. Hence, the aim of this study was to compare the biomechanical performance of helical and straight PHILOS® Long plates in AO12C2 fractures using static and cyclic implant system testing. Methods Helical and straight PHILOS® Long plates on artificial bone substitutes were tested under physiological axial static (n=6) and cyclic loading (n=12). The axial construct stiffness was the main parameter for comparing the biomechanical performance of the two groups. Mimicking a clinical scenario, the helical deformation was performed consecutively by an experienced surgeon using iron bending tools. The torsional angle was determined computationally from 3D-scanning models afterwards. Results Helical plating resulted in a significantly reduced axial construct stiffness in all test scenarios compared to conventional straight plating (static testing: p=0.012; cyclic testing: p≤0.010). No failure occurred within the range of physiological loading in both groups. Conclusions Helical plating favors multidimensional deformation of the test sample in lateral-ventral direction under axial loading, resulting in a reduced axial construct stiffness and in an increased interfragmentary movement. No biomechanical failure is to be expected within physiological load boundaries.

Leinthaler I., Gierling H., Jäger R., Lapatki B., Mayer J., Schmidt F., Peuscher H.

Abstract Orthodontic tooth movement is related to application of forces and moments to individual teeth. Experimental testing of orthodontic wires helps clinicians to exert adequately dimensioned therapeutic loads. In this work, an existing experimental setup to analyze the force delivery of orthodontic wires is augmented with an algorithm that automatically finds a neutral position in which the wire transmits as little force and torque as possible; to this end, the drives of the setup are traversed to an optimal position based on measurements. The algorithm is first tested with the help of a simulation-based software-in-the-loop framework and then implemented on the real setup. Experimental results show massive time savings compared to manual alignment.

Oezcelik S., Haeger A.

Abstract In the world of dental implants, the essential determinant of success lies in the phenomenon of osseointegration, wherein titanium implants exhibit the ability for robust integration with the surrounding bone and tissue. Beyond the inherent qualities of titanium which make it an attractive candidate as an implant material, attention has shifted towards its’ tailored surface modifications. These methods help the implant manufacturers to modify the implant surface for successful osseointegration and higher chances of enduring implantation. This review explores different surface modification methods and their impact on the dental implant success.

Komposch J., Malzacher T., Baumgärtner T., Braun M., Roßkopf J., Franz A.M., Schmitz B.

Abstract Artificial intelligence (AI) has the potential to support time-critical stroke treatment. In a previous study we demonstrated the feasibility of deep learning based automatic classification for thrombus detection during thrombectomies, a catheter-guided procedure to remove occlusions of cerebral vessels. However, this method has yet to be tested during a live intervention. In this work, we present a setup to integrate AI based support in an angiography suite. A classification PC was connected to the angiography by means of a real-time video connection as well as a research interface for control signals. We found that video conversion in real-time does not affect the classification result in comparison to offline classification of DICOM data. Analyzing 50 video streams of previous cases, the system could classify digital-subtraction angiography (DSA) sequences within 13.3 seconds on average. This processing time can further be reduced to an average of 7.9 seconds with GPU acceleration. Additionally, the system successfully classified two DSA sequences acquired during live thrombectomy, identifying the presence of thrombi in less than 5 seconds. So far, the classification result has only been displayed in the control room of the angiography suite to demonstrate feasibility. In the outlook, however, we also discuss how the result can be displayed directly on the angiography screen.

Roegnitz A., Haeger A.

Abstract Titanium and its alloys play a vital role in dental implantology, providing a stable foundation for replacement teeth and restoring oral function effectively. Titanium alloys, particularly CP-Ti and Ti-6Al-4V, are widely utilized due to their biocompatibility, corrosion resistance and mechanical properties. However, concerns arise regarding the release of cytotoxic elements and stress shielding effects. Addressing these concerns requires advancements in material design and tribological properties. Research focuses on developing low modulus β-type Ti-based alloys with improved wear resistance and biocompatibility, incorporating elements like niobium, tantalum or zirconium. This review explores the tribological implications of these advancements, focussing on the implantabutment interface, emphasizing the need for optimized titanium alloys for dental implant applications.

Akrah A., Hessling M.

Abstract Catheter-associated urinary tract infections are among the most common hospital-acquired infections and all previous measures to reduce their incidence have been less successful. Therefore, the present study investigates an approach based on the antimicrobial effect of visible light. The radiation of a violet or blue LED is guided via optical fiber with a diffuser tip into a catheter surrounded by an E. coli suspension (phosphate buffered saline or urine) in a simple urinary tract model. The irradiation led to bacterial reductions of up to several orders of magnitude that depended on various parameters. Violet light had a stronger antimicrobial effect than blue light, even in the experiments with urine, which absorbs violet light more strongly than blue light. An increase in irradiation intensity led to a greater reduction in bacteria. Human cells are not expected to be damaged by this irradiation. Therefore, the application of violet light to prevent catheter-associated urinary tract infections seems particularly promising but should be tested on even more realistic models in the future, which should not only include planktonic cells but also biofilms.

Schneider S.M., Engleder T., Schneider R., Haeger A.

Abstract The ISO 14801 standard test is repeatedly criticized for not reflecting the actual conditions and loads realistically enough to which dental implants are exposed (e. g. during chewing). The aim of this paper is to provide a brief review of the test parameters of the ISO standard and to compare them critically with the parameters that prevail in vivo. The research revealed significant simplifications of the test conditions, wich can partly be justified with better reproducibility and comparability. Nevertheless, the realization remains that the test deviates considerably from real physiological loading conditions and should be adapted accordingly or supplemented by further tests.

Kast R.E., Kast A.P., Arnhold J., Capanni F., Sanabria L.N., Bader N., Vieira B.M., Alfieri A., Karpel-Massler G., da Silva E.B.

This paper presents the basis for LoGlo PDT, a new treatment for glioblastoma. Glioblastoma is currently treated with maximal safe resection, temozolomide, and ionizing irradiation. Mortality in 2024 remains over 80% within several years from diagnosis. Oral 5-aminolevulinic acid (5-ALA) is an FDA/EMA approved drug that is selectively taken up by malignant cells, including by glioblastoma. In photodynamic treatment of glioblastoma, intense intraoperative light causes glioblastoma tissue that has taken up 5-ALA to generate cytotoxic reactive oxygen species. The requirement for intense light flux has restricted photodynamic treatment to a single one-hour intraoperative session. We analyze here published data showing that external light, illuminating the entire intact scalp, can attain low μW/cm2 flux several cm into intact brain that would be sufficient to mediate 5-ALA photodynamic treatment of glioblastoma if the light and 5-ALA are delivered continuously over 24 h. At the core of LoGlo PDT regimen is the dataset showing that, for a given fluence, as the duration of PDT light delivery goes down, light intensity (flux) delivered must go up to achieve the same glioblastoma cell cytotoxicity as would a weaker light (lower flux) delivered over a longer time. Thus, a repetitive, noninvasive PDT of glioblastoma using an external light source may be possible. We analyze 5-ALA cellular physiology to show that three non-oncology drugs, ciprofloxacin, deferiprone, and telmisartan, can be repurposed to increase light energy capture after 5-ALA, thereby increasing photodynamic treatment’s glioblastoma cell cytotoxicity. The LoGlo PDT approach uses both drug augmentation and prolonged ultra-low noninvasive transcranial light delivery for a repetitive, noninvasive 5-ALA photodynamic treatment of glioblastoma.

Gross M., Gagel A., Maierhofer A.

Clinical studies have shown that hemodiafiltration reduces morbidity and mortality of dialysis patients compared to hemodialysis alone. This is attributed to its superior middle molecule clearance compared to standard hemodialysis. However, doubts arose as to whether a high convective flux through the dialyzer membrane has an influence on the equilibrium concentration of small ions, especially that of sodium. Due to the presence of negatively charged impermeable proteins on the blood side, the Gibbs-Donnan effect leads to an asymmetric distribution of membrane permeable ions on both sides of the membrane. In thermodynamic equilibrium, the concentrations of those ions can easily be calculated. However, the convective fluid flow leads to deviations from thermodynamic equilibrium. In this article, the effect of a convective flow on the ion distribution across a semipermeable membrane is analyzed in a theoretical model. Starting from the extended Nernst-Planck equation, including diffusive, convective, and electrostatic effects, a set of differential equations is derived. An approximate solution for flow speeds up to 0.1 ms−1 as well as a numerical solution are given. The results show that in any practical dialysis setting the convective flow has negligible influence on the electrolyte concentrations.