TY - CHAP A1 - Hoeller, Christoph A1 - Mueller-Trapet, Markus T1 - Measured and predicted sound transmission through a laboratory concrete floor T2 - INTER-NOISE and NOISE-CON Congress and Conference Proceedings, INTER-NOISE24, Nantes, France N2 - The direct sound transmission through a simple, massive, homogeneous building element with and without lining is investigated experimentally and compared with analytical and empirical models from the literature. A 150 mm thick concrete floor and a 100 mm thick floating floor were measured in the floor transmission facility of the National Research Council Canada, i.e. without flanking sound transmission. In addition to the sound reduction index and the normalized impact sound pressure level, loss factors, radiation efficiencies, and mean squared velocities were recorded in the laboratory. The measured data is compared to established models of sound transmission. A focus is placed on the calculation model of ISO 12354-1 (Appendix B), which uses calculated radiation efficiencies and loss factors to predict the sound reduction index of heavy, homogeneous building elements. Some difficulties with the calculation model and the examples in the standard are discussed. In principle, the results in this study show that the calculation model of ISO 12354-1 gives good estimates when the correct input parameters are used. However, deviations between the calculated and the measured loss factors and radiation efficiencies have large effects on the accuracy of the estimates, particularly in the region around the coincidence frequency. Y1 - 2024 U6 - https://doi.org/10.3397/IN_2024_3902 SP - 7042 EP - 7050 PB - ingenta ER - TY - THES A1 - Berndt, Dominik T1 - Thermische Wasserstoffsensoren für den Automobilbereich N2 - Für den sicheren Betrieb eines Brennstoffzellenfahrzeugs sind Sensoren wichtig, welche die Wasserstoffkonzentration im Fahrzeuginterieur kontinuierlich überwachen, um möglichen Entzündungen bzw. Explosionen vorzubeugen. Dafür wurden von verschiedenen nationalen und internationalen Instanzen bestimmte Kriterien definiert, die Wasserstoffsensoren für einen Einsatz in Brennstoffzellenfahrzeugen erfüllen müssen. Im Jahr 2020gab es noch keinen einzigen kommerziell erhältlichen Sensor, der alle diese Kriterien bedienen konnte. In der vorliegenden Arbeit wurde für zwei verschiedene Sensoren die Eignung des thermischen Wirkprinzips für die Detektion von Wasserstoff im Kontext dieser Sicherheitskriterien untersucht. Dabei wurden mit einem MEMS-Sensor und einem Mikrodrahtsensor zwei vergleichsweise einfache Geometrien herangezogen, welche den eindimensionalen und zylindersymmetrischen Fall abbilden sollen. Für zwei dynamische Operationsmodi (gepulste Ströme und 3ω-Methode) wurden darauf aufbauend analytische Modelle basierend auf vereinfachten Sensorgeometrien entwickelt, um die Temperaturentwicklung des Sensorelements in Abhängigkeit der Zeit zu charakterisieren. Diese Studien wurden anschließend anhand von detaillierteren Modellen mithilfe von FEM-Simulationen ergänzt und spezifiziert. Darin konnte gezeigt werden, dass für den gepulsten Betrieb sowohl die Pulshöhe als auch die Zeitkonstante des gemessenen Widerstands- bzw. Temperaturpulses als Messgröße herangezogen werden kann. Beim 3ω-Betrieb konnte zudem eine starke Frequenzabhängigkeit dieser Widerstands- bzw. Temperaturcharakteristik beobachtet werden. Die analytischen und numerischen Studien wurden anschließend durch experimentelle Ergebnisse bestätigt. Im Hinblick auf die zuvor definierten Kriterien stellte sich heraus, dass die Auswertung der Zeitkonstante beim gepulsten Betrieb im Hinblick auf Sensitivität und Auflösungsgrenze der Auswertung der Pulshöhe deutlich unterlegen ist. Beim 3ω-Betrieb können durch die hochintegrierte Messumgebung deutlich höhere Genauigkeiten und Auflösungsgrenzen erzielt werden. Für den MEMS-Sensor wurde bei einer Anregungsfrequenz von 1 Hz mit 55 ppm die bislang geringste in der Literatur berichtete Auflösungsgrenze für einen thermischen Wasserstoffsensor erreicht. Der Leistungsverbrauch ist dabei im Vergleich zum Pulsbetrieb entsprechend des jeweiligen Tastgrads leicht bis mäßig erhöht, die Ansprechzeit wird bei beiden Operationsmodi maßgeblich durch die Sensorgeometrie beeinflusst. Die geometrischen Parameter der jeweiligen Sensoren haben ferner einen starken Einfluss auf die Sensitivität, womit die Divergenz in der Performance von MEMS-Chip und Drahtsensor erklärt werden kann. Es besteht ferner eine starke Temperatur- und Feuchtigkeitsabhängigkeit des Sensorsignals, welches bei beiden Operationsmodi indirekt proportional zur Wärmeleitfähigkeit des betrachteten Gasgemischs ist. Die Abhängigkeit vom definierten Umgebungsdruck ist lediglich für die Zeitkonstante relevant, bei der Pulshöhe besteht keine Druckabhängigkeit. Es konnte eine grundsätzliche Eignung des thermischen Messprinzips für den Einsatz eines Wasserstoffsensors im Automobilbereich festgestellt werden. Für eine Anwendung müssen allerdings Referenzsensoren für Temperatur, Feuchtigkeit und Druck implementiert werden und eine Kalibrierung in Abhängigkeit dieser Größen erfolgen. Der 3ωBetrieb ist aufgrund der höheren Genauigkeit zu bevorzugen. Während der MEMSSensor im Hinblick auf Sensitivität, Ansprechzeit und Leistungsaufnahme gut abschneidet, liegen die Vorteile des Mikrodrahtsensors in seiner Robustheit und der vergleichsweise einfachen Realisierbarkeit N2 - For the safe operation of a fuel cell vehicle, sensors that continuously monitor the hydrogen concentration in the vehicle interior are crucial in order to prevent possible ignitions or explosions. For this purpose, various national and international institutions have defined certain criteria that hydrogen sensors must meet for being used in fuel cell vehicles. In 2020, there was not yet a single commercially available sensor that could serve all of these criteria. In the present work, the suitability of the thermal operating principle for the detection of hydrogen in the context of these safety criteria was investigated for two different sensors. Two relatively simple geometries, a MEMS sensor and a micro-wire sensor, were used to represent the one-dimensional and cylinder-symmetric case. Analytical models based on simplified sensor geometries were subsequently developed for two dynamic operation modes (pulsed currents and 3ω-method) to characterize the temperature response of the sensor element as a function of time. These studies were then extended and specified using more detailed models based on FEM simulations. In these studies, it was shown that for pulsed operation, both the pulse height and the time constant of the measured resistance or temperature pulse can be used as a measurand. For 3ω-operation, a strong frequency dependence of these resistance or temperature characteristics was also observed. The analytical and numerical studies were subsequently confirmed by experimental results. With respect to the previously defined criteria, the evaluation of the time constant during pulsed operation was found to be significantly inferior to the evaluation of the pulse height in terms of sensitivity and resolution limit. For 3ω-operation, significantly higher accuracies and resolution limits could be achieved due to the highly integrated measurement environment. For the MEMS sensor, at an excitation frequency of 1 Hz, the lowest resolution limit for a thermal hydrogen sensor reported in the literature to date was achieved at 55 ppm. The power consumption is slightly increased compared to the pulse mode according to the corresponding duty cycle. The response time is significantly influenced by the sensor geometry for both operation modes. Furthermore, the geometrical parameters of the individual sensors have a strong influence on the sensitivity, which can explain the divergence in the performance of the MEMS chip and the micro-wire sensor. There is also a strong temperature and humidity dependence of the sensor signal, which is indirectly proportional to the thermal conductivity of the gas mixture. The dependence on the ambient pressure is only relevant for the time constant, there is no pressure dependence for the pulse height. A fundamental suitability of the thermal measurement principle for the use of a hydrogen sensor in the automotive sector could be identified. However, for an application, reference sensors for temperature, humidity and pressure must be implemented and calibration must be performed as a function of these variables. The 3ω-operation is preferred due to its higher accuracy. While the MEMS sensor performs well in terms of sensitivity, response time and power consumption, the advantages of the microwire sensor are based on its robustness and the fact that the manufacturing process is comparably easy. KW - Kraftfahrzeugtechnik KW - Brennstoffzellenfahrzeug KW - Wasserstoff KW - Gassensor KW - Sensortechnik KW - Feuchtigkeitsabhängigkeit KW - thermischer Wasserstoffsensor Y1 - 2023 UR - https://opus.bibliothek.uni-augsburg.de/opus4/frontdoor/deliver/index/docId/105227/file/Diss_Berndt.pdf CY - Regensburg ER - TY - JOUR A1 - Mennicken, Max A1 - Peter, Sophia Katharina A1 - Kaulen, Corinna A1 - Simon, Ulrich A1 - Karthäuser, Silvia T1 - Impact of device design on the electronic and optoelectronic properties of integrated Ru-terpyridine complexes JF - Beilstein journal of nanotechnology N2 - The performance of nanoelectronic and molecular electronic devices relies strongly on the employed functional units and their addressability, which is often a matter of appropriate interfaces and device design. Here, we compare two promising designs to build solid-state electronic devices utilizing the same functional unit. Optically addressable Ru-terpyridine complexes were incorporated in supramolecular wires or employed as ligands of gold nanoparticles and contacted by nanoelectrodes. The resulting small-area nanodevices were thoroughly electrically characterized as a function of temperature and light exposure. Differences in the resulting device conductance could be attributed to the device design and the respective transport mechanism, that is, thermally activated hopping conduction in the case of Ru-terpyridine wire devices or sequential tunneling in nanoparticle-based devices. Furthermore, the conductance switching of nanoparticle-based devices upon 530 nm irradiation was attributed to plasmon-induced metal-to-ligand charge transfer in the Ru-terpyridine complexes used as switching ligands. Finally, our results reveal a superior device performance of nanoparticle-based devices compared to molecular wire devices based on Ru-terpyridine complexes as functional units. KW - Ru-terpyridine wires KW - conductance switching KW - gold nanoparticles KW - nanoelectronic devices KW - optical addressing Y1 - 2022 U6 - https://doi.org/10.3762/bjnano.13.16 VL - 13 SP - 219 EP - 229 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften ER - TY - JOUR A1 - Hausladen, Matthias A1 - Buchner, Philipp A1 - Bartl, Mathias A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Integrated multichip field emission electron source fabricated by laser-micromachining and MEMS technology JF - Journal of Vacuum Science & Technology B N2 - In this work, high-current field emission electron source chips were fabricated using laser-micromachining and MEMS technology. The resulting chips were combined with commercially available printed circuit boards (PCBs) to obtain a multichip electron source. By controlling the separate electron sources using an external current control circuit, we were able to divide the desired total current evenly across the individual chips deployed in the PCB-carrier. In consequence, we were able to show a decreased degradation due to the reduced current load per chip. First, a single electron source chip was measured without current regulation. A steady-state emission current of 1 mA with a high stability of ±1.3% at an extraction voltage of 250 V was observed. At this current level, a mean degradation slope of −0.7 μA/min with a nearly perfect transmission ratio of 99% ± 0.4% was determined. The measurements of a fully assembled multichip PCB-carrier electron source, using a current control circuit for regulation, showed that an even distribution of the desired total current led to a decreased degradation. This was determined by the increase in the required extraction voltage over time. For this purpose, two current levels were applied to the electron source chips of the PCB-carrier using an external current control circuit. First, 300 μA total current was evenly distributed among the individual electron source chips followed by the emission of 300 μA per electron source chip. This allows the observation of the influence of a distributed and nondistributed total current, carried by the electron source chips. Thereby, we obtained an increase in the mean degradation slope from +0.011 V/min (300 μA distributed) to +0.239 V/min (300 μA per chip), which is approximately 21 times higher. Moreover, our current control circuit improved the current stability to under 0.1% for both current levels, 300 μA distributed and 300 μA per chip. KW - MEMS technology KW - Field emitter arrays KW - Electron sources KW - Laser micromachining Y1 - 2024 U6 - https://doi.org/10.1116/6.0003233 VL - 42 IS - 1 PB - AIP Publishing ER - TY - JOUR A1 - Remškar, Maja A1 - Jelenc, Janez A1 - Czepurnyi, Nikolai A1 - Malok, Matjaž A1 - Pirker, Luka A1 - Schreiner, Rupert A1 - Hüttel, Andreas K. T1 - Modulations of the work function and morphology of a single MoS2 nanotube by charge injection JF - Nanoscale Advances N2 - Both the miniaturization of transistor components and the ongoing investigation of material systems with potential for quantum information processing have significantly increased current interest of researchers in semiconducting inorganic nanotubes. Here we report on an additional outstanding aspect of these nanostructures, namely the intrinsic coupling of electronic and mechanical properties. We observe electronic and morphology changes in a single MoS2 nanotube, exposed to charge injections by means of an atomic-force-microscopy tip. An elliptic deformation of the nanotube and helical twisting of the nanotube are visible, consistent with the reverse piezoelectric effect. Work-function changes are found to be dependent on the polarity of the injected carriers. An unexpected long-term persistence of the shape deformations is observed and explained with accumulation of structural defects and the resultant strain, which could cause a memory-like charge confinement and a long lasting modulation of the work function. Y1 - 2024 U6 - https://doi.org/10.1039/d4na00490f SN - 2516-0230 PB - Royal Society of Chemistry (RSC) ER - TY - CHAP A1 - Ali, Md. Wajed A1 - Ahmmed, Tanvir A1 - Al Emran, Md A1 - Roy, Dipon A1 - Refat, Kawsar Ahmed A1 - Khan, Robiul T1 - Driver Fatigue Detection using CWT-Extracted Features and a Deep Learning Approach (CNNLSTM) T2 - 2024 IEEE International Conference on Biomedical Engineering, Computer and Information Technology for Health (BECITHCON), 28-29 Nov. 2024, Dhaka, Bangladesh N2 - Driver fatigue is a leading reason behind traffic accidents globally, resulting in significant threats to public safety and substantial economic costs. Electroencephalography (EEG) has shown to be a critical tool for identifying driver fatigue as it can record brain activity associated with sleepiness, which gives it an advantage over other physiological modalities. Although raw EEG data can provide insightful information, accurate fatigue identification requires strong feature extraction techniques because of the inherent complexity of the data. This emphasizes how urgent it is to investigate revolutionary deep-learning architectures that can successfully extract discriminative features from raw EEG data. This study provides an innovative framework for driver fatigue identification from EEG that combines continuous wavelet transform (CWT) with convolutional neural networks (CNN) and long-short term memory (LSTM). In order to gain the advantage over the drawbacks of manual feature extraction, this study generates time-frequency spectrum representations of EEG data using the CWT. Following extracting information, each channel’s time-frequency images are concatenated and fed into a CNN-LSTM architecture. This combination models the temporal and spatial characteristics of the EEG data and automatically learns discriminative features for identifying drivers’ normal and fatigued states. A publicly available EEG dataset with recordings from twelve subjects is used to evaluate the proposed CWT-CNN-LSTM architecture. The result shows a prominent classification accuracy of 98.34% for both the average of each subject and combined subjects. These findings show how well the CNN-LSTM framework captures EEG patterns associated with fatigue, which may result in more reliable driver fatigue detection systems and improved traffic safety. KW - Accuracy KW - Brain modeling KW - CNN KW - Continuous wavelet transforms KW - Convolutional neural networks KW - CWT KW - Deep learning KW - Deep Learning (DL) KW - Driver Fatigue KW - EEG KW - Electroencephalography KW - Fatigue KW - Feature extraction KW - Long short term memory KW - LSTM KW - Time-frequency analysis Y1 - 2025 UR - https://ieeexplore.ieee.org/document/10962632 SN - 979-8-3315-3435-6 U6 - https://doi.org/10.1109/BECITHCON64160.2024.10962632 SP - 77 EP - 82 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Haynack, Alexander A1 - Timothy, Jithender J. A1 - Kränkel, Thomas A1 - Gehlen, Christoph A1 - Thiel, Charlotte T1 - Analyse des Frost‐Tausalz‐Widerstands zementgebundener Baustoffe mittels 3D‐Laserscanning JF - ce/papers: Proceedings in Civil Engineering N2 - Eine Herausforderung performancebasierter Prüfverfahren zur Bewertung der Dauerhaftigkeit ist die Beschleunigung natürlicher Mechanismen. Dies ist notwendig, um innerhalb kurzer Zeit die Langzeit-Leistungsfähigkeit ermitteln zu können. Die Bestimmung der Frost-Tausalzbeständigkeit von Beton kann durch den CDF-Test erfolgen, welcher für Betone mit ausreichendem Frost-Tausalz-Widerstand sehr gut funktioniert. Bei Proben mit einer unzureichenden bzw. unbekannten Performance können erhöhte Randabwitterungen auftreten, welche durch das Ablösen des seitlichen Abdichtbands entstehen. Der zunehmende Randeinfluss führt so zu einer Verfälschung der Ergebnisse und zu einer Unterschätzung der tatsächlichen Performance des Bauteils. In diesem Beitrag werden Mörtel- und Betonprobekörper mit unterschiedlichen Abwitterungsraten in Anlehnung an das CDF-Verfahren untersucht. Zusätzlich wird die Oberflächenschädigung der Proben anhand einer neuartigen Messmethode mittels hochauflösendem 3D-Laserscanning ausgewertet. Die Ergebnisse zeigen, dass die Randeffekte mit der Laserscan-Methode umgangen und vergleichbare Ergebnisse zu den CDF-Untersuchungen erzielt werden können. Somit können Betone ohne Randeinflüsse charakterisiert und eine präzise Prognose der Langzeitbeständigkeit getroffen werden. KW - Beton KW - Mörtel KW - Frost-Tausalz-Widerstand KW - Dauerhaftigkeit KW - 3D-Laserscanning Y1 - 2023 U6 - https://doi.org/10.1002/cepa.2951 SN - 2509-7075 VL - 6 IS - 6 SP - 1189 EP - 1196 PB - Ernst & Sohn ER - TY - JOUR A1 - Peter, Daniel A1 - Dalmer, Michael A1 - Lechner, Alfred A1 - Gigler, Alexander M. A1 - Stark, Robert W. A1 - Bensch, Wolfgang T1 - The influence of liquid media on the fracture strength of polysilicon nanostructures JF - Solid State Phenomena N2 - The mechanical stability of nanostructures depends on the surrounding medium. Their stability was probed by lateral force microscopy in liquid media. Previously reported data on water and isopropanol showed an increase in the fracture strength for the latter. Further tests with other alcohols (ethanol, 1-butanol) also showed an increasing strength. The interface between the liquid and the surface is the decisive factor for the influence of the media. When altering the interface with a cationic surfactant or a self-assembled monolayer, an increase of the fracture force by 100 % compared to de-ionized water could be measured. KW - pattern collapse KW - fracture strength KW - damage KW - atomic force microscopy Y1 - 2012 U6 - https://doi.org/10.4028/www.scientific.net/SSP.187.127 VL - 187 SP - 127 EP - 130 PB - Trans Tech Publications ER - TY - CHAP A1 - Escher, Lukas A1 - Rück, Thomas A1 - Jobst, Simon A1 - König, Martin A1 - Bierl, Rudolf T1 - Design and Characterization of a Low-Cost Photoacoustic Sensor for NO2 Using Lateral Illumination and Background Suppression T2 - Imaging and Applied Optics Congress 2022 (3D, AOA, COSI, ISA, pcAOP): 11–15 July 2022, Vancouver, British Columbia, Canada N2 - We introduce a low-cost photoacoustic NO2 sensor based on lateral LED illumination and optical background signal compensation. The 3σ limit of detection (LOD) was identified to be 24 ppbV. Y1 - 2022 SN - 978-1-957171-09-8 U6 - https://doi.org/10.1364/3D.2022.JTu2A.10 PB - Optica Publishing Group ER - TY - INPR A1 - Pangerl, Jonas A1 - Sukul, Pritam A1 - Rück, Thomas A1 - Escher, Lukas A1 - Miekisch, Wolfram A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Photoacoustic Trace-Analysis of Breath Isoprene and Acetone Via Interband- and Quantum Cascade Lasers N2 - This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the PAS systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm-1Hz-0.5 and 4.9E-9 Wcm-1Hz-0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices. KW - photoacoustic spectroscopy KW - breath analysis/profiling KW - real-time mass spectroscopy KW - isoprene KW - acetone Y1 - 2024 U6 - https://doi.org/10.2139/ssrn.4834735 PB - Elsevier / SSRN ER - TY - JOUR A1 - Pangerl, Jonas A1 - Sukul, Pritam A1 - Rück, Thomas A1 - Escher, Lukas A1 - Miekisch, Wolfram A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Photoacoustic trace-analysis of breath isoprene and acetone via interband- and Quantum Cascade Lasers JF - Sensors and Actuators: B. Chemical N2 - This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the photoacoustic systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm 1Hz 0.5 and 4.9E-9 Wcm 1Hz 0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices KW - Photoacoustic spectroscopy KW - Breath analysis/profiling KW - Real-time mass spectrometry KW - Isoprene KW - Acetone Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77024 N1 - Corresponding author der OTH Regensburg: Jonas Pangerl VL - 424 PB - Elsevier ER - TY - CHAP A1 - Escher, Lukas A1 - Müller, Max A1 - Rück, Thomas A1 - Jobst, Simon A1 - Bierl, Rudolf T1 - Digitaler Zwilling photoakustischer Spurengassensoren zur Prozessüberwachung T2 - 16. Dresdner Sensor-Symposium 2022: Vorträge N2 - Stickstoffdioxid (NO2) wird hauptsächlich durch anthropogene Verbrennungsprozesse in Verkehr und Industrie in die Umgebungsluft eingebracht [1]. Die stark reaktive, oxidative Wirkung von NO2 kann bei Exposition mit höheren Konzentrationen Reizungen und allergische Reaktionen in den Atemwegen hervorrufen. Weiter führt NO2 zur Bildung von saurem Regen, Smog und Ozon (O3) die sich ebenso negativ auf die menschliche Gesundheit und Umwelt auswirken [2,3]. Aufgrund dieser Effekte wird die Spurengaskonzentration von NO2 in der Luft in Deutschland an ausgewählten, verkehrsreichen Orten gemessen. Y1 - 2022 SN - 978-3-9819376-7-1 U6 - https://doi.org/10.5162/16dss2022/3.3 PB - AMA (Association for Sensors + Measurement) ER - TY - JOUR A1 - Rück, Thomas A1 - Pangerl, Jonas A1 - Escher, Lukas A1 - Jobst, Simon A1 - Müller, Max A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Kinetic cooling in mid-infrared methane photoacoustic spectroscopy: A quantitative analysis via digital twin verification JF - Photoacoustics N2 - This study presents a detailed quantitative analysis of kinetic cooling in methane photoacoustic spectroscopy, leveraging the capabilities of a digital twin model. Using a quantum cascade laser tuned to 1210.01 cm⁻¹, we investigated the effects of varying nitrogen-oxygen matrix compositions on the photoacoustic signals of 15 ppmV methane. Notably, the photoacoustic signal amplitude decreased with increasing oxygen concentration, even falling below the background signal at oxygen levels higher than approximately 6 %V. This phenomenon was attributed to kinetic cooling, where thermal energy is extracted from the surrounding gas molecules rather than added, as validated by complex vector analysis using a previously published digital twin model. The model accurately reproduced complex signal patterns through simulations, providing insights into the underlying molecular mechanisms by quantifying individual collision contributions. These findings underscore the importance of digital twins in understanding the fundamentals of photoacoustic signal generation at the molecular level. Y1 - 2024 U6 - https://doi.org/10.1016/j.pacs.2024.100652 VL - 40 PB - Elsevier ER - TY - JOUR A1 - Leonhardt, Carina A1 - Guertler, Katherine T1 - Unearthing Corporate Greenwashing: A Content Analysis of Sustainability Reporting in the Mining Sector JF - Tripodos N2 - Greenwashing is a common form of corporate disinformation that is often challenging for the general public to detect. Companies engage in greenwashing in their reporting to mislead shareholders and stakeholders about their environmental efforts, seeking to enhance legitimacy and gain competitive advantages. While systems for identifying greenwashing exist, they typically focus on advertising, leaving greenwashing in corporate reports underexamined. This study aims to address this gap by conducting a qualitative content analysis of a climate report from a mining and commodity trading company, considering the company’s profile, the report’s target audience, and current research. The findings reveal that the company employs numerous subtle greenwashing strategies to project a more sustainable image through strategic omissions, hedging and vague long-term goals. Moreover, this research broadens the scope of greenwashing analysis to include corporate reporting, which targets a more informed audience, such as shareholders and experts, rather than the general public. The results underscore the need for stricter regulation of sustainability reports and highlight the importance of fostering greater scrutiny among shareholders. KW - climate communication KW - corporate communication KW - greenwashing KW - sustainability reporting Y1 - 2025 U6 - https://doi.org/10.51698/tripodos.2025.57.06 SN - 1138-3305 VL - 2025 IS - 57 SP - 78 EP - 97 PB - Blanquerna School of Communication and International Relations CY - Barcelona ER - TY - CHAP A1 - Mühlberger, Thomas A1 - Schoplocher, Paul Dragos A1 - Steffens, Oliver ED - Fouad, Nabil A. T1 - Thermische Gebäudesimulation: aktuelle Anwendungen und Erweiterungen mittels der Finite‐Elemente‐Methode T2 - Bauphysik-Kalender 2025: Simulationen, BIM und KI N2 - Nach einem kurzen historischen Abriss der Entwicklung der Gebäudesimulation wird die aktuell übliche gleichungsbasierte Kompaktmodell-Simulation beschrieben und deren praktische Anwendung aufgezeigt. Dabei wird auf die Bedeutung der Validierung von Simulationstools und auf etablierte Validierungsstandards eingegangen. Gebäudesimulation dient der Optimierung des Bauens in allen Planungsphasen. Mit Praxisbeispielen vom sommerlichen Wärmeschutz bis hin zur Modellierung innovativer Konstruktionen werden unterschiedliche Einsatzbereiche demonstriert. Im zweiten Teil wird die Verwendung der Finite-Elemente-Methode (FEM) für die bauphysikalische Modellierung vorgestellt. Anhand von Beispielen zeigen wir, dass die (rechenzeitintensive) FEM aufgrund einer detaillierteren Modellierung von Geometrie, Strahlung und Konvektion präzisere Simulationsergebnisse liefert. Zum Abschluss werden Wege vorgeschlagen, wie dies zur Erweiterung der schnelleren Kompaktmodell-Simulation eingesetzt werden kann. KW - Energieeffizienz KW - Finite-Elemente-Methode KW - Gebäudesimulation KW - Kompaktmodelle KW - thermische Bauphysik Y1 - 2025 SN - 9783433034514 U6 - https://doi.org/10.1002/9783433612095.ch12 SP - 435 EP - 468 PB - Ernst & Sohn CY - Berlin ER - TY - JOUR A1 - Jobst, Simon A1 - Recum, Patrick A1 - Écija-Arenas, Ángela A1 - Moser, Elisabeth A1 - Bierl, Rudolf A1 - Hirsch, Thomas T1 - Semi-Selective Array for the Classification of Purines with Surface Plasmon Resonance Imaging and Deep Learning Data Analysis JF - ACS sensors N2 - In process analytics or environmental monitoring, the real-time recording of the composition of complex samples over a long period of time presents a great challenge. Promising solutions are label-free techniques such as surface plasmon resonance (SPR) spectroscopy. They are, however, often limited due to poor reversibility of analyte binding. In this work, we introduce how SPR imaging in combination with a semi-selective functional surface and smart data analysis can identify small and chemically similar molecules. Our sensor uses individual functional spots made from different ratios of graphene oxide and reduced graphene oxide, which generate a unique signal pattern depending on the analyte due to different binding affinities. These patterns allow four purine bases to be distinguished after classification using a convolutional neural network (CNN) at concentrations as low as 50 μM. The validation and test set classification accuracies were constant across multiple measurements on multiple sensors using a standard CNN, which promises to serve as a future method for developing online sensors in complex mixtures. KW - surface plasmon resonance imaging KW - functional surface KW - graphene oxide KW - reduced graphene oxide KW - 2D materials KW - pattern recognition KW - small-molecule sensing Y1 - 2023 U6 - https://doi.org/10.1021/acssensors.3c01114 VL - 8 IS - 9 SP - 3530 EP - 3537 PB - American Chemical Society ER - TY - CHAP A1 - Hausler, Peter A1 - Wunderlich, Lukas A1 - Fischer, Johannes A1 - Pfab, Christina A1 - Heckscher, Simon A1 - Hirsch, Thomas A1 - Bierl, Rudolf T1 - Surface plasmon resonance imaging for detection of drug metabolites in water T2 - Proceedings of SPIE, Optical Sensors 2019, 1 - 4 April 2019, Prague, Czech Republic N2 - The analysis of surface water, groundwater, drinking water as well as sewage is important to get information about the contamination of the water cycle. Currently, these time-consuming investigations require special equipment, like for example hyphenated mass spectrometry. Surface plasmon resonance (SPR) is a faster alternative as it is highly sensitive to changes in the dielectric medium next to a thin metal layer and makes it a quasi-universal detector. Therefore, and due to the labelfree nature, SPR is a widely used sensing tool for real‐time monitoring of molecular interactions of various analytes. SPR imaging (SPRi) has several advantages to standard surface plasmon resonance, as it allows to observe many analytes in parallel as well as the integration of referencing technologies. However, the homogenous illumination of a large area (several millimeters) with a small light source is challenging and demands new approaches. Allopurinol, a drug used to lower the blood concentration of urate and hence decrease the affection of gout, gets metabolized to oxipurinol in the body and dropped out almost entirely by urinary excretion. After wastewater treatment, concentrations of oxipurinol up to 21.7 μg•L-1 are detected. Further tracking of oxipurinol in the urban water cycle showed its presence in rivers and streams or even in groundwater. Therefore, the high biological stability of oxipurinol allows this molecule to be used as a marker for domestic wastewater in the environment. For the detection of oxipurinol by SPR graphene was used as receptive layer, as the analyte can bind via π-stacking to this surface. An SPRi technique was developed and compared to conventional SPR system for the detection of oxipurinol. Y1 - 2019 U6 - https://doi.org/10.1117/12.2522324 SN - 0277-786X VL - Vol. 11028 ER - TY - CHAP A1 - Hausler, Peter A1 - Roth, Carina A1 - Aumer, F. A1 - Vitzthumecker, Thomas A1 - Genslein, Christa A1 - Hirsch, Thomas A1 - Bierl, Rudolf T1 - Miniaturisiertes Sensorsystem zur Oberflächenplasmonenresonanzspektroskopie T2 - 118. Jahrestagung der deutschen Gesellschaft für angewandte Optik (DGaO), 6.-10. Juni 2017, Dresden N2 - Die Oberflächenplasmonenresonanzspektroskopie (SPR) wird aufgrund ihrer Vorzüge der zerstörungs- und markierungsfreien Messung, sowie der hohen Sensitivität sehr erfolgreich im Labormaßstab eingesetzt. Aufgrund der hohen Kosten geschieht dies bislang hauptsächlich in der Bioanalytik und dem Wirkstoffscreening. Gezeigt wird ein Ansatz, mit dem diese Technologie auf ein ultrakompaktes, kostengünstiges Sensorsystem übertragen wird, welches in der Lage ist, hoch-sensitiv Änderungen im Brechungsindex von 10-6 Einheiten (RIU) zu detektieren. Für Wasser bewirkt eine Temperaturschwankung von 1 K bereits eine Änderung von 1 mRIU. Daher wird durch ein integriertes Referenzsystem, sowie die Miniaturisierung erreicht, dass das System gegenüber Temperaturschwankungen, weitestgehend stabil ist. In dem MOEMS wird anstatt der konventionellen 1-Punkt bzw. 2-Punkt Messung ein bildgebendes Verfahren angewendet. Die Sensorfläche von 15 x 15 mm wird dabei mit einem handelsüblichen 4 Mio. Pixel CMOS Sensor ausgewertet. Um verlässliche Datenpunkte zu erhalten benötigt man eine Fläche von 10 x 10 Pixel. Demzufolge können auf dem Sensor theoretisch bis zu 40.000 Sensorspots parallel ausgewertet werden. KW - Messtechnik KW - Optische Systeme KW - Spektroskopie Y1 - 2017 ER - TY - CHAP A1 - Hausler, Peter A1 - Genslein, Christa A1 - Roth, Carina A1 - Vitzthumecker, Thomas A1 - Hirsch, Thomas A1 - Bierl, Rudolf T1 - Miniaturized Surface Plasmon Resonance based Sensor System T2 - Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology - PHOTOPTICS, Funchal, Madeira, Portugal N2 - We describe the miniaturization of the Surface Plasmon Resonance (SPR) technology which mainly finds its applications in pharmaceutical screening and biotechnology so far. SPR spectroscopy is a label-free, non-destructive and highly sensitive measurement principle detecting changes in the refractive index in striking distance to a gold surface. A transfer of this technology to a miniaturized sensor will broaden the range of possible applications. A promising feature which is included in the miniaturized system is the angle-dependent recording of the SPR signals without moving parts. Commercial SPR assays are mainly working with a small number of sensing spots. In contrast, the SPR imaging system shown here will allow to use an array of many sensing spots. In combination with chemical receptors designed as an artificial nose, the simultaneous detection of many analytes is envisioned for future applications. KW - Surface Plasmon Resonance Spectroscopy KW - Sensor KW - SPR-imaging KW - Miniaturization KW - Micro-Opto-Electro-Mechanical Systems Y1 - 2018 SN - 978-989-758-286-8 U6 - https://doi.org/10.5220/0006555400630066 SP - 63 EP - 66 PB - SciTePress ER - TY - JOUR A1 - Genslein, Christa A1 - Hausler, Peter A1 - Kirchner, Eva-Maria A1 - Bierl, Rudolf A1 - Baeumner, Antje J. A1 - Hirsch, Thomas T1 - Graphene-enhanced plasmonic nanohole arrays for environmental sensing in aqueous samples JF - Beilstein Journal of Nanotechnology N2 - The label-free nature of surface plasmon resonance techniques (SPR) enables a fast, specific, and sensitive analysis of molecular interactions. However, detection of highly diluted concentrations and small molecules is still challenging. It is shown here that in contrast to continuous gold films, gold nanohole arrays can significantly improve the performance of SPR devices in angle-dependent measurement mode, as a signal amplification arises from localized surface plasmons at the nanostructures. This leads consequently to an increased sensing capability of molecules bound to the nanohole array surface. Furthermore, a reduced graphene oxide (rGO) sensor surface was layered over the nanohole array. Reduced graphene oxide is a 2D nanomaterial consisting of sp2-hybridized carbon atoms and is an attractive receptor surface for SPR as it omits any bulk phase and therefore allows fast response times. In fact, it was found that nanohole arrays demonstrated a higher shift in the resonance angle of 250–380% compared to a continuous gold film. At the same time the nanohole array structure as characterized by its diameter-to-periodicity ratio had minimal influence on the binding capacity of the sensor surface. As a simple and environmentally highly relevant model, binding of the plasticizer diethyl phthalate (DEP) via π-stacking was monitored on the rGO gold nanohole array realizing a limit of detection of as low as 20 nM. The concentration-dependent signal change was studied with the best performing rGO-modified nanohole arrays. Compared to continuous gold films a diameter-to-periodicity ratio (D/P) of 0.43 lead to a 12-fold signal enhancement. Finally, the effect of environmental waters on the sensor was evaluated using samples from sea, lake and river waters spiked with analytically relevant amounts of DEP during which significant changes in the SPR signal are observed. It is expected that this concept can be successfully transferred to enhance the sensitivity in SPR sensors. KW - diethyl phthalate KW - environmental sensing KW - nanohole array KW - nanosphere lithography KW - surface plasmon resonance Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:355-epub-398623 IS - 7 SP - 1564 EP - 1573 ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Dietrich, Clemens A1 - Tarsevitch, Alexander A1 - Horn-von Hoegen, Michael A1 - von der Linde, Dietrich A1 - Cavalleri, Andrea A1 - Kammler, Martin A1 - Uschmann, Ingo A1 - Foerster, Eckhart T1 - Femtosecond X-ray Diffraction Study of Large Amplitude Coherent Optical Phonons in Laser-Excited Bismuth JF - Conference on Lasers and Electro-Optics, 1–6 June 2003, Baltimore, Maryland N2 - Femtosecond time-resolved X-ray diffraction was used to directly study optical phonons in laser-excited Bismuth. A periodic modulation of the diffraction efficiency reveals initially coherent lattice distortions with atomic displacements of nearly 10% of the nearest- neighbor-distance. Y1 - 2003 UR - https://opg.optica.org/abstract.cfm?uri=cleo-2003-CMZ6 PB - Optical Society of America ER -