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UV LED Curable Perfluoropolyether (PFPE)-Urethane Methacrylate Transparent Coatings for Photonic Applications: Synthesis and Characterization
No full textThe contribution aims to bring forth a novel synthesis route in developing transparent UV LED-curable coatings accounting for various exposure options. A selection of perfluoropolyether (PFPE)-urethane methacrylate and acrylate resins, free-radical photo-initiator Omnirad 2100, and two distinct silane-based crosslinking agents were blended under a weight ratio of 75:20:5 (without crosslinker) and 70:15:5:10, respectively. The coatings were cured under a UV LED 4 × 3 matrix light emitting source, in a chamber under a controlled atmosphere, by means of an in-house developed conveyor belt type platform, at different conveyor belt speeds (5, 50, 150, 250, and 500 mm/s). The morphologies of fabricated coatings were characterized by FTIR revealing high conversion rates (e.g., from 98 to 100%) for increased exposure time as a result of the 5 or 50 mm/s values, on all combinations. Dynamic–mechanical and optical properties of UV LED-cured transparent coatings were also investigated. A negative shift of the glass transition temperature values with a decrease in exposure time, in all combinations, from about 60 °C to 30 °C, along with storage moduli lowering in the glassy plateau further favors higher exposure times for curing. The refractive indices of poly-mers were from 1.38 to 1.40, whereas the thermo-optic coefficients are showing minor changes around the value of 2.55∙10−4 K−1
Determination of optical constants and scattering properties of transparent polymers for use in optoelectronics
No full textKnowledge of optical constants, i.e. refractive index n and extinction coefficient k, and light scattering properties of optical polymers are required to optimize micro-optics for light-emitting diodes in terms of efficiency, color properties and light distribution. We present here a model-based diagnostic approach to determine the optical properties of polymers, which should be particularly useful in the development of plastics for optical applications. Optical constants and scattering coefficients were obtained from transmission and reflection measurements in a wavelength range from UV to NIR taking into account scattering effects due to rough surfaces and volume inhomogeneity. Based on the models for the dielectric function, the molecular optical transition energies Eg, critical point energies, Urbach energies and exciton transition energies were determined. Rayleigh and Mie scattering model and van de Hulst's anomalous diffraction theory were applied to characterize scattering due to volume inhomogeneities. Scalar diffraction theory was applied to account for surface roughness scattering. Atomic force microscopy with nanomechanical characterization was used to characterize domains in size and shape and to assign optical scattering to a suitable morphological model. The combined optical and mechanical characterization help to improve the qualification of new polymer materials for optical applications
Surface Plasmon Resonance (SPR) Spectroscopy and Photonic Integrated Circuit (PIC) Biosensors: A Comparative Review
No full textLabel-free direct-optical biosensors such as surface-plasmon resonance (SPR) spectroscopy has become a gold standard in biochemical analytics in centralized laboratories. Biosensors based on photonic integrated circuits (PIC) are based on the same physical sensing mechanism: evanescent field sensing. PIC-based biosensors can play an important role in healthcare, especially for point-of-care diagnostics, if challenges for a transfer from research laboratory to industrial applications can be overcome. Research is at this threshold, which presents a great opportunity for innovative on-site analyses in the health and environmental sectors. A deeper understanding of the innovative PIC technology is possible by comparing it with the well-established SPR spectroscopy. In this work, we shortly introduce both technologies and reveal similarities and differences. Further, we review some latest advances and compare both technologies in terms of surface functionalization and sensor performance
Explosive Zeiten
No full textVon der Vision 1964 zur industriellen Realität 1976:
"Detonierender Sprengstoff formt im 3 Minuten-Takt Nutzfahrzeug-Achsbrücken"
Die erstmalige Nutzung der Energie des Sprengstoffes in einer Serienfertigung der Metallindustrie war die Vision, die Art und Weise der Umsetzung, der Kampf bei der Lösung der schwierigen technischen und der Sicherheitsprobleme beim Umgang mit Sprengstoff im Industriebetrieb, die Kreativität des Ingenieurs als treibende Kraft, werden in der Erfolgsgeschichte faktisch und vorbildlich, auch für zukünftige Generationen, spannend dargestellt.
Der Schritt von bisher üblichen Verfahren, zu einer komplett anderen Technologie und Achsbrückenkonstruktion war nicht nur neu, sondern weltweit einzig, auch erfolgreich in der Ökonomie und besonders im Energieaufwand.
Die Zielstrebigkeit im Lebenswerk des Autors und seines erfolgreichen Teams sind in Wort und Bild für Historiker, genauso für Lernende und Lehrende, in der Gegenwart und Zukunft eine Erfolgsstory
Electroplated Micro-Labelling as Copy Protection
No full textIn order to achieve good product quality in electroplating, disturbance variables such as the "dog bone" effect must be avoided. In this work, this approach was used to develop a method for marking as product protection. With a defined structure and optimal parameters, it is possible to deposit unique visually non-differentiable layers on suitable substrates. The deposited layers and their local distribution were characterized by confocal laser microscopy, X-ray fluorescence analysis and laser interference measurements and analyzed qualitatively as well as quantitatively. It thus provides interested parties with an essentially traditional process that can lead to new innovations with the chosen approach.Um eine gute Produktqualität in der Galvanik zu erreichen, müssen Störgrößen wie zum Beispiel der "Hundeknochen"-Effekt vermieden werden. In dieser Arbeit wurde dieser Ansatz genutzt, um eine Methode zur Kennzeichnung als Produktschutz zu entwickeln. Mit definiertem Aufbau und optimalen Parametern ist es möglich, auf geeigneten Substraten, unikale visuell nicht differenzierbare Schichten abzuscheiden. Die abgeschiedenen Schichten und deren lokale Verteilung wurden mit Hilfe konfokaler Lasermikroskopie, Röntgenfluores-zenzanalyse und Laserinterferenzmessungen charakterisiert und qualitativ als auch quantitativ analysiert. Interessenten stellt es damit ein im Grunde traditionelles Verfahren zur Verfügung, das mit dem gewählten Ansatz zu neuen Innovationen führen kann
A Test System for Safely Measurements of Cancer-Inducing UV-C Diodes Produced in a Simple and Cost-Effective Way by Rapid Prototyping
No full textNew technologies leading to better and more efficient light emitting diodes. The emitted radiation reaches higher energy levels and lower wavelengths especially in the UV-C spectrum. UV-C light has a cancer inducing effect on human cells. Therefore it is necessary to work in a safe way with those devices.
This work is focused on an open-source solution for rapid 3D printing of an safe UV-C radiation measuring device. Especially for research groups or universities which can not afford big safety labs.
After modeling and printing the prototype, a series of tests has shown the functionality of that UV-C Diode test system. By using black printing filaments and infill rates over 50 %, the transmission of light could be prevented and the system worked well
Concept for improving relevance ranking and research options in the discovery system of the Saxon State and University Library Dresden
No full textUm Möglichkeiten zur Verbesserung des Relevanzrankings im SLUB-Katalog aufzuzeigen, werden in der vorliegenden Arbeit die aktuellen Konfigurationen der Suche im SLUB-Katalog analysiert. Zur Ermittlung geeigneter Indexfelder für die Suche werden insbesondere die verwendeten Feldtypen und die Belegungshäufigkeit in den angesprochenen Solr-Cores untersucht. Darauf aufbauend werden Vorschläge zu Änderungen der Konfigurationen der Standardsuche „Alles“ des SLUB-Katalogs und spezialisierten Sucheinstiege gemacht.
Durch die prototypische Entwicklung einer Webapplikation, mit welcher sich Konfigurationen der Rankingberechnung zur Suchanfragezeit anpassen lassen, können die Auswirkungen multipler Faktoren, wie z.B. Auswahl der Indexfelder und Boost-Werte, die die Relevanzberechnung beeinflussen, schneller und unabhängig vom IT-Personal getestet, verglichen und dokumentiert werden
Simulation Modeling for Energy-Flexible Manufacturing: Pitfalls and How to Avoid Them
No full textDue to the high share of industry in total electricity consumption, industrial demand-side management can make a relevant contribution to the stability of power systems. At the same time, companies get the opportunity to reduce their electricity procurement costs by taking advantage of increasingly fluctuating prices on short-term electricity markets, the provision of system services on balancing power markets, or by increasing the share of their own consumption from on-site generated renewable energy. Demand-side management requires the ability to react flexibly to the power supply situation without negatively affecting production targets. It also means that the management and operation of production must consider not only production-related parameters but also parameters of energy availability, which further increase the complexity of decision-making. Although simulation studies are a recognized tool for supporting decision-making processes in production and logistics, the simultaneous simulation of material and energy flows has so far been limited mainly to issues of energy efficiency as opposed to energy flexibility, where application-oriented experience is still limited. We assume that the consideration of energy flexibility in the simulation of manufacturing systems will amplify already known pitfalls in conducting simulation studies. Based on five representative industrial use cases, this article provides practitioners with application-oriented experiences of the coupling of energy and material flows in simulation modeling of energy-flexible manufacturing, identifies challenges in the simulation of energy-flexible production systems, and proposes approaches to face these challenges. Seven pitfalls that pose a particular challenge in simulating energy-flexible manufacturing have been identified, and possible solutions and measures for avoiding them are shown. It has been found that, among other things, consistent management of all parties involved, early clarification of energy-related, logistical, and resulting technical requirements for models and software, as well as the application of suitable methods for validation and verification are central to avoiding these pitfalls. The identification and characterization of challenges and the derivation of recommendations for coping with them can raise awareness of typical pitfalls. This paper thus helps to ensure that simulation studies of energy-flexible production systems can be carried out more efficiently in the future
Welche Erwartungen hat die Eisenbahnbranche an neueingestellte Mitarbeitende?
No full textDieser Fragestellung geht das EU-Projekt ASTONRail in einem ersten Projektteil nach. In einer Umfrage wurde die Eisenbahnbranche in Deutschland und Europa hinsichtlich ihrer Erwartungen an die Hochschulausbildung neueingestellter Eisenbahningenieurinnen und -ingenieure befragt. Erkenntnisse und Schlussfolgerungen für die Hochschulausbildung werden nachfolgend vorgestellt
Bio-inorganic hybrid structures for direct electron transfer to photosystem I in photobioelectrodes
No full textSynthetic materials can be combined with biological components in many ways. One example that provides scientists with multiple challenges is a photobioelectrode that converts sunlight into electrons in a biohybrid approach. In the present study several key parameters are evaluated concerning their influence on the direct electron transfer from a 3D indium tin oxide (ITO) electrode material to photosystem I (PSI) as a light-harvesting biomolecule. In contrast to previous investigations, no mediating molecule is added to shuttle the electrons to the luminal side of PSI. Thus, this setup is less complex than foregoing ones. The solution composition drastically influences the interaction of PSI with the ITO surface. Here, the application of higher buffer concentrations and the addition of salts are advantageous, whereas the nature of the buffer ions plays a minor role. The artificial electrode material's thickness is adjustable since a spin-coating procedure is used for preparation. With a 30 μm thick structure and immobilized PSI cathodic photocurrents up to 10.1 μA cm−2 are obtained at 100 mW cm−2 illumination intensity and an applied potential of −0.1V vs. Ag/AgCl. Over a period of three days the photobioelectrodes are illuminated for a total of 90 min and stored between the measurements at ambient temperature. The stability of the setup is noteworthy as still about 90% of the photocurrent is retained. The photocathode described here offers many positive features, including a high onset potential for the photocurrent starting sligthly above the redox potentail of P700, and applicability in a wide pH range from pH 5 to 8