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The raccoon roundworm (Baylisascaris procyonis) is a gastrointestinal parasitic nematode of the raccoon (Procyon lotor). It is common in its native range in North America, where its prevalence in raccoons [...]

The widespread adoption of renewable energy hinges on the efficient transportation of hydrogen. Reciprocating piston compressor technology in non-lubricated operation will play a key role, ensuring high flow rates and compression ratios. These systems rely on advanced high-strength sealing solutions for piston and rod packing rings utilizing advanced fiber-reinforced polymers. Polyphenylene sulfide (PPS) polymer matrix composites have seen use in tribological applications and promise high mechanical strength and wear resistance. The presented work describes carbon and glass fiber-reinforced PPS matrix polymers in comparison, which are characterized by complementary methods to investigate their properties and potential for application in reciprocating compressor under non-lubricated operation. Thermo-mechanical and tribological testing was supported by microstructure analysis utilizing advanced X-ray and electron imaging techniques. New insights in micromechanical deformation behavior in regard to fiber materials, interface strength and orientation in fiber-reinforced polymers are given. Conclusions on the suitability of different PPS matrix composites for high-pressure hydrogen compression applications were obtained. [ABSTRACT FROM AUTHOR]

Additive manufacturing techniques such as vat photopolymerization have laid the foundation for impressive advances in the 3D structuring of ceramic materials. However, simultaneous structuring of these complex‐shaped ceramic objects on the sub‐µm scale, an essential feature for a wide range of applications in separation, energy conversion and storage, adsorption or sensing, has remained a tremendous challenge. This study demonstrates how complex‐shaped polymer‐derived SiOC ceramics exhibiting hierarchical porosity ranging from the sub‐µm‐ to the millimeter‐range can be generated by combining vat photopolymerization with photopolymerization‐induced phase separation using preceramic polymer‐based phase‐separating resins. In addition to allowing single‐step, multi‐level structural control, this new processing concept allows for the chemical modification of the 3D‐printable, phase‐separating preceramic polymer resins using organometallic compounds, including the possibility to generate functional metal nanoparticles in situ during the polymer‐to‐ceramic conversion. In this manner, a chemical toolbox is provided, facilitating the introduction of Ni, Co, Mo, or La into the hierarchically structured SiOC matrix. The versatile applicability of this new materials design approach is demonstrated by employing complex‐shaped, hierarchically porous monoliths containing in situ generated Ni nanoparticles as heterogeneous catalysts for CO2 methanation, with a profound increase in catalyst performance attained by oxidative post‐treatment of the metal‐ceramic hybrid material. [ABSTRACT FROM AUTHOR]

Alloying rare earth elements into aluminum nitride (AlN) thin films to increase the piezoelectric response has gained a lot of attention in the past few years. Many rare earth elements are investigated in which scandium alloying resulted in the highest piezoelectric response for AlN. At the same time, researchers have also theoretically explored yttrium alloying as a feasible and economical alternative to scandium. Herein, for the first time, experimentally, the increase of the piezoelectric response of sputter-deposited YxAl1-xN thin films as a function of increasing yttrium concentration as predicted by density functional theory calculations is demonstrated. Using differently manufactured targets, YxAl1-xN thin films with four different yttrium alloying concentrations (9, 12, 15, and 20 at%). are synthesized. Detailed thin-film analysis is carried out and the highest value of d33 measured is 12 pC N-1 for Y0.2Al0.8N, which is a 250% increase compared to pure AlN. Even more, the Young's modulus decreases with increasing yttrium concentration in excellent agreement with theoretical predictions. Finally, Y0.15Al0.85N and Y0.2Al0.8N layers show high crystalline stability in pure oxygen environment up to 800 °C, demonstrating high oxidation resistance even under harsh environmental conditions. [ABSTRACT FROM AUTHOR]

As supported CuO is well-known for low temperature activity, CuO/CeO2 nanosphere catalysts were synthesized and tested for CO oxidation and preferential oxidation of CO (PROX) in excess H2. For the first reaction, ignition was observed at 95 °C, whereas selective PROX occurred in a temperature window from 50 to 100 °C. The catalytic performance was independent of the initial oxidation state of the catalyst (CuO vs. Cu0), suggesting that the same active phase is formed under reaction conditions. Density functional modeling was applied to elucidate the intermediate steps of CO oxidation, as well as those of the comparably less feasible H2 transformation. In the simulations, various Cu and vacancy sites were probed as reactive centers enabling specific pathways. [ABSTRACT FROM AUTHOR]

We investigate the effect of cerium and tungsten addition to optimize the deNOx activity of V2O5/TiO2 catalysts over a broad temperature range in the catalytic reduction of NOx with NH3 (NH3-SCR) with and without the presence of water. The catalysts were synthesized following co-impregnation of TiO2 with different loadings and varying content of V2O5, CeO2 and WO3 oxides as promoters. Based on surface and bulk characterization, we show that all catalysts undergo different structural changes depending on the chemical nature of the promoters. X-ray photoelectron spectra indicate a tendency for surface reduction after addition of CeO2, surface oxidation after addition of WO3, and after catalytic NH3-SCR. Promotion of V2O5/TiO2 catalysts with CeO2 and/or WO3 broadens the operation temperature window of the catalytic NH3-SCR reaction under both dry and wet conditions and improves the N2 selectivity at high temperatures. The thermal deactivation resistance of CeO2- and WO3-promoted catalysts improves with increasing amount of WO3. We tentatively relate this to suppression of the sintering of the active VOx component and increasing the amount of CeVO4. The latter, as a consequence of Ce-V interaction, detrimentally changes the surface composition of the catalysts and hides active V in the bulk structure inaccessible for reaction. Water slightly decreases the overall catalytic activity of SCR at low temperatures, while preventing the formation of N2O at elevated temperatures. Addition of CeO2 leads to a slight decrease in overall reducibility of the catalysts, while W causes an enhancement in quantitative H2 uptake. On the contrary, the sole addition of CeO2 leads to an enhancement of ammonia adsorption and the appearance of new acidic surface sites, which beneficially combine the reduced surface of the catalysts with an enhanced deNOx activity at low temperature. [ABSTRACT FROM AUTHOR]

Alloying transition metals into aluminum nitride (AlN) has surged over the past decade to increase the piezoelectric performance of AlN for microelectromechanical systems (MEMS) applications. So far, the highest piezoelectric coefficients have been achieved by alloying scandium into AlN. But, most recently published studies have theoretically predicted by ab‐initio calculations that yttrium can also be a promising and less expensive alternative to scandium. This paper focuses on the impact of an AlN seed layer on the growth and piezoelectric properties of sputter‐deposited, polycrystalline Y0.15Al0.85N thin films on a silicon substrate. For the first time, the increase in piezoelectric performance of YxAl1−xN (x = 15%) thin films with a d33 of ≈7.85 pC N−1 due to this seed layer approach is presented, thus reaching in good agreement theoretical predictions. Furthermore, for the first time, the crystalline stability of Y0.15Al0.85N layers in a pure oxygen environment up to 1200 °C is reported, demonstrating a high oxygen resistance up to 800 °C even in this harsh environment. Detailed thin film analysis is done with various techniques such as X‐ray diffraction, atomic force microscopy, nano‐indentation, and high‐resolution transmission electron microscopy and correlated with piezoelectric coefficient measurements. [ABSTRACT FROM AUTHOR]