Unraveling the role of shell thickness and pore size on the mechanical properties of ceramic-based macroporous structures

Macroporous structures are of interest for several technological applications such as catalysis, sensors, filters, membranes, batteries, energy conversion devices, structural colors, and reflective thermal barrier coatings. Ceramic-based inverse opal macroporous structures are especially interesting for high-temperature applications. However, the interrelation between the structural parameters, mechanical properties, and thermal stability of such structures is not yet clarified. In this work, we analyzed the mechanical properties as well as the thermal stability of aluminum oxide inverse opal three-dimensional macroporous structures with different macropore sizes and shell thicknesses produced by atomic layer deposition. Our results show that the structures’ thermal stability increased with increasing shell thickness and macropore size, however, their higher stability was not linked to their mechanical properties. To be able to explain this unexpected behavior, finite element modeling simulations were performed, showing that bending stresses became more pronounced with increasing shell thickness, potentially creating additional critical sites for crack initiation and consequent structural failure.     

Graph Learning in Machine-Readable Plant Topology Data

Digitalization shows that data and its exchange are indispensable for a versatile and sustainable process industry. There must be a shift from a document-oriented to a data-oriented process industry. Standards for the harmonization of data structures play an essential role in this change. In engineering, DEXPI (Data Exchange in the Process Industry) is already a well-developed, machine-readable data standard for describing piping and instrumentation diagrams (P&ID). In this publication, industry, software vendors, and research institutions have joined forces to demonstrate the current developments and potentials of machine-readable P&IDs in the DEXPI format combined with artificial intelligence. The aim is to use graph neural networks to learn patterns in machine-readable P&ID data, which results in the efficient engineering and development of new P&IDs.     

Postural instability-induced compensative movements in virtual reality

Virtual Reality - During virtual reality usage, two egocentric mental representations are constructed simultaneously. The first representation is rooted in the physical reality in which VR is set...     

Process development and accurate low‐cost characterization for OLED sealants by using a calcium test

Abstract— A calcium measurement setup was built for testing encapsulation especially for OLED applications. This setup is able to measure both reflective and transmissive cells. For the characterization of sealants, a method to compare them with other sealing products will be described. This includes the use of spacers, a homogeneous surface energy, and the geometry of the sealant line. The effects of different geometries will be discussed. The setup was designed to achieve good accuracy at a very reasonable component cost, which will allow other facilities to replicate this setup. Therefore, the construction plan as well as the list of components can be downloaded from our website (Ref. 3).     

UV/VIS-spectroscopy of molten and solid CaO-MgO-SiO2 - slags

The previously developed high temperature set-up has been used to monitor the redox state of molten slags at 1500°C directly by UV/VIS spectroscopy. Slags of the CaO-MgO-SiO₂-system were doped with Fe₂O₃ mass contents of 0.80 and 5%. Spectroscopical results at different oxygen partial pressures of the investigated Fe³⁺ charge-transfer (CT) transitions in the wavelength range between 200 and 800 nm were found to be representative for the redox state of the slag. The peak positions and shifts give further information about the optical basicity and the structure of molten slags. The time dependence of the oxidation/reduction equilibrium process was measured and evaluated concerning diffusion mechanisms. In Cr₂O₃-doped silicate-slags in the liquid state CrO₃ - and Cr³⁺- species occur. The different CrO₃-species (CrO₄^2- and Cr₂O₇^2-) in silicate slags have been indicated spectroscopically and registed quantitatively. Further investigations on Cr₂O₃-doped slags uncovered the well known evaporation of chromium out of molten slags as a decrease in the CrO₃ concentration in time. In the molten slag the CrO₃ slowly evaporates, which can be seen spectroscopically as a decrease in the CT-band intensity. The results obtained on numerous optical parameters of molten slags will establish the application of reflection spectroscopy at high temperatures.     

Atomic layer deposition process with TiF4 as a precursor for depositing metal fluoride thin films

A novel atomic layer deposition process for the preparation of fluoride thin films in a temperature range of 225 degrees C-400 degrees C is introduced. The crystallinity, morphology, composition, thicknesses, refractive indices, and transmittance of the films are analyzed. Low impurity levels are obtained at 350 degrees C-400 degrees C with good stoichiometry. Refractive indices of 1.34-1.42 for MgF(2), 1.43 for CaF(2), and 1.57-1.61 for LaF(3) films are obtained.     

Quantum Key Distribution: from Principles to Practicalities

We review the main protocols for key distribution based on principles of quantum mechanics, describing the general underlying ideas, discussing implementation requirements and pointing out directions of current experiments. The issue of security is addressed both from a principal and real-life point of view. Received: October 15, 1998; revised version: June 8, 1999