http://hdl.handle.net/10563/1000003 2026-05-11T13:25:26Z http://hdl.handle.net/10563/1012821 Ni- and Zn-Doping Effects on Cu/SiO2 Catalysts in Nonoxidative Ethanol Dehydrogenation Pokorný, Tomáš; Macháč, Petr; Moravec, Zdeněk; Šimoníková, Lucie; Leonová, Lucie; Hlavenková, Zuzana; Škoda, David; Pacultová, Kateřina; Karásková, Kateřina; Stýskalík, Aleš Nonoxidative ethanol dehydrogenation opens a pathway for the sustainable production of acetaldehyde and butadiene. One crucial aspect of producing butadiene by the Lebedev process is the high-temperature stability of ethanol to acetaldehyde conversion. However, copper-based catalysts, despite exhibiting high activity and selectivity, suffer from sintering and coking and need to be improved for successful industrial applications. Herein, we show Cu-based (similar to 2.5 wt %) catalysts doped with Ni and Zn (0.028-0.36 wt %) to improve the catalytic performance of nanoparticles. The catalysts were prepared by hydrolytic sol-gel and dry impregnation methods. STEM analysis determined the nanoparticle sizes in the 1.9-2.8 nm range. Ni-doped catalysts outperformed the parent Cu catalysts in ethanol dehydrogenation activity at lower temperatures (185-220 degrees C) but suffered from faster deactivation. The Zn-doped catalysts exhibited improved high-temperature stability. For these materials, acetaldehyde selectivity fluctuated around similar to 90% and acetaldehyde productivity reached 3.63 g g-1 h-1 at 290 degrees C and a WHSV of 4.73 h-1. The improved stability of the Zn-doped samples was correlated with lower coke formation (XPS, TG analysis, and Raman spectroscopy). 2026-01-01T00:00:00Z http://hdl.handle.net/10563/1012822 Simultaneous Cross-Linking and Nanoparticle Anchoring by Dialdehyde Cellulose in Injectable Composite Chitosan/Polypyrrole Hydrogels Muchová, Monika; Münster, Lukáš; Kolařík, Roman; Víchová, Zdenka; Vašíček, Ondřej; Humpolíček, Petr; Vícha, Jan The injectable composite hydrogel with covalently bound polypyrrole (PPy) has been prepared using dialdehyde cellulose (DAC) as a bifunctional cross-linker, forming dynamic imine bonds with water-soluble half acetylated chitosan (SCN) and simultaneously tethering the PPy nanoparticles by aldol condensation. The novelty lies in translating this dual chemistry into an injectable, self-healing hydrogel system, for the first time fully utilizing dynamic Schiff base cross-linking in combination with covalent PPy anchoring. PPy is also involved both in hydrogel cross-linking, altering its rheological behavior, but also providing antioxidative and anti-inflammatory effects. The resulting hydrogels exhibited shear-thinning behavior, rapid self-healing, and storage moduli ranging from 25 to 47 Pa, allowing for injection through 21 G needles. All formulations were noncytotoxic toward NIH/3T3 fibroblasts and RAW 264.7 macrophages. In scratch assays, SCN_DAC_20_PPy significantly accelerated wound closure, with the residual wound area to 39 +/- 2% after 10 h versus 83 +/- 7% for controls and 65 +/- 3% for the corresponding PPy-free hydrogel. In LPS-stimulated macrophages, all hydrogels decreased nitric oxide production, and PPy-containing hydrogels additionally reduced IL-6 secretion. The SCN/DAC/PPy injectable hydrogels thus exhibit cytocompatibility, self-healing properties, and anti-inflammatory activity, representing a promising platform for the future development of advanced wound dressings. 2026-01-01T00:00:00Z http://hdl.handle.net/10563/1012810 Towards reliable elastic characterization of glass bead reinforced thermoplastic composites using impulse excitation and conventional testing Rech, Julian Niklas; Dresbach, Christian; Van Dorp Ramakers, Esther Dorothea Victoria; Möginger, Bernhard; Hausnerová, Berenika Reliable determination of elastic properties is essential for the structural use of polymer composites in engineering applications. This work aims to evaluate the impulse excitation technique (IET) as a method for determining elastic constants of glass bead‑reinforced polyamide 66 (PA66) and polybutylene terephthalate (PBT), and to compare its performance to tensile testing (TT), dynamic mechanical analysis (DMA), and oscillatory torsion (OT). Commercial PA66 and PBT grades with 0–40 wt% glass beads were injection‑molded and annealed; the addition of glass beads increased Young’s moduli by 60–70% for PA66 and 40–60% for PBT compared to the neat matrices, depending on filler content. IET, supported by finite element analysis, provided dynamic flexural and longitudinal moduli, shear modulus, and Poisson’s ratio which were comparable to those obtained from TT, DMA and OT. In the linear elastic regime IET data differed within the standard deviations of TT, DMA and OT. The moduli determined by flexural excitation using IET and DMA agreed within experimental uncertainty only above an amplitude threshold of approximately 110 μm, while Young’s moduli from TT and IET showed good agreement, though TT exhibited greater variability. Consistent trends were also found for shear modulus and Poisson’s ratio. The higher longitudinal moduli (4 to 8% for PA66 and 2 to 4% for PBT) measured by IET are explained by higher frequencies (3 to 4 orders of magnitude) and cross-sectional microstructural anisotropy and crystallinity differences confirmed by microscopy and calorimetry. The results demonstrate that IET is a much faster, non‑destructive and accurate method for obtaining elastic constants of thermoplastic composites particularly suited for the design and dimensioning of load‑bearing structural components.. 2026-01-01T00:00:00Z http://hdl.handle.net/10563/1012807 Rheological and Mechanical Characterization of Styrene-Butadiene Rubber Reinforced With Recovered Carbon Versus Carbon Black Yilmazoglu, Unal C.; Robertson, Christopher G. We studied the rheological and mechanical property effects of replacing N650 carbon black (CB) with recovered carbon (rC) filler in styrene-butadiene rubber (SBR) compounds, using a type of rC produced from end-of-life tires by a chloramine devulcanization process. When compared at the same filler loading, rC gave a smaller Payne effect than CB in the uncured and cured states; this is consistent with the larger particle size for rC (lower surface area) and associated less tendency for filler networking. In Fourier transform rheology (FT-rheology), the strain amplitude (γ0) dependence of the ratio of the third harmonic to the first harmonic for the dynamic torque (I3/1) showed clear differences for compounds with rC versus CB. We proposed and utilized a new empirical Double Sigmoidal Nonlinearity Model (DSNM) to fit the γ0-dependent I3/1. This modeling approach captured well the data for all compounds and allowed the nonlinear rheological differences between rC and CB fillers to be effectively quantified. The cure curves, along with temperature-dependent viscoelastic measurements of the cured materials, indicated a reduction in crosslink density from substituting rC for CB. This under-cure effect, in addition to less filler reinforcement, resulted in deterioration of tensile mechanical properties from substituting rC for CB. © 2026 Wiley Periodicals LLC. 2026-01-01T00:00:00Z