Activity

The ability to correlate industrial high-pressure catalysis with high-vacuum research has been of great interest for decades. We employed a double-chamber vacuum system to study the self-hydrogenation of acetylene to ethylene and its trimerization to benzene at medium pressures to compare the reactivity in this pressure range to the known model catalytic acetylene reactivity in ultrahigh vacuum (UHV). We measured the reactivity of Pd-Cu bimetallic alloy nanoparticles (ANPs) with different elemental compositions deposited on top of native SiO2/Si(100) and on bilayer SiO2/Ru(0001) surfaces, where the latter was shown to contribute to ANP stability. Following exposure to 0.5 mbar of acetylene, ANPs on both surfaces catalyze the formation of ethylene and benzene, with ethylene as the more probable product. The ANPs on bilayer SiO2/Ru(0001) were highly selective toward ethylene formation, with an ethylene/benzene ratio of more than 2 orders of magnitude, whereas on the native SiO2/Si(100) there was a significantly lower selectivity (about 5) at the same temperature range and catalyst elemental composition. Interestingly, these selectivity values are similar to those found under UHV conditions. In addition, ANPs grown on native SiO2/Si(100), unlike SiO2/Ru(0001), revealed an optimal temperature for ethylene and benzene formation due to the limited stability of the particles.Hybrid organic-inorganic perovskites show remarkable charge transport properties despite their deposition via low-temperature solution phase methods. It has recently been shown that this includes the ballistic transport of charges following photoexcitation, with ballistic transport lengths as large as 150 nm measured in MAPI3 films, which is almost twice the value reported for GaAs. Here we explore the ballistic transport regime in high-performance triple-cation and K-passivated triple-cation perovskite films, using femtosecond transient absorption microscopy, which allows us to image carrier motion with 10 fs temporal resolution and 10 nm spatial precision. We observe ballistic transport lengths of 160 and 220 nm in triple-cation and K-passivated triple-cation perovskite films, respectively. We propose that the ballistic transport is limited by nanoscale trap clusters at grain boundaries and interfaces, which can be passivated via chemical treatments to enhance the ballistic transport length, which implies that further enhancements are possible as passivation methods are improved.Lattice constant is one of the paramount parameters that mark the quality of thin film fabrication. Numerous research efforts have been made to calculate and measure lattice constant, including experimental and empirical approaches. Not withstanding these efforts, a reliable and simple-to-use model is still needed to predict accurately this vital parameter. In this study, gene expression programming (GEP) approach was implemented to establish trustworthy model for prediction of the lattice constant of A2XY6 (A = K, Cs, Rb, TI; X = tetravalent cation; and Y = F, Cl, Br, I) cubic crystals based on a comprehensive experimental database. The obtained results showed that the proposed GEP correlation provides excellent prediction performance with an overall average absolute relative deviation (AARD%) of 0.3596% and a coefficient of determination (R2) of 0.9965. Moreover, the comparison of the performance between the newly proposed correlation and the best pre-existing paradigms demonstrated that the established GEP correlation is more robust, reliable, and efficient than the prior models for prediction of lattice constant of A2XY6 cubic crystals.Deep eutectic solvent (DES) gel electrolytes have recently emerged as promising alternatives to ionic liquid- or water-based gels for “ionic skin” sensor applications. Researchers have also been exploring the effects that varying amounts of water may have on the local hydrogen bonding environment within a few model DES systems. In this study, the physical properties and ionic conductivities of biopolymer (gelatin)-supported gels featuring two established DESs and three DES/water mixture formulations are investigated and compared. click here The DES/water mixtures are formed by combining choline chloride with one of three organic hydrogen bond donors (HBDs), ethylene glycol, glycerol, or 1,2-propanediol, in a 12 molar ratio, together with a controlled amount of water, 25 mol % (approximately 5-6 wt % water). For the same fixed gelatin content (20 wt %), DES/water mixture gel Young’s modulus values are found to be tunable based on the organic HBD identity, increasing 6-fold from 7 (1,2-propanediol) to 42 (glycerol) kPa. Furthermore, large differences are observed in the resulting gel properties when water has been intentionally added to well-studied DESs. Coformulation with water is found to increase ethylene glycol-based DES gel toughness, measured via tensile testing, from 23 to 68 kJ/m3 while simultaneously boosting gel room temperature ionic conductivity from 3.3 to 5.2 mS/cm. These results highlight the multiple roles that controlled amounts of water in DES can play within gelatin-supported DES/mixture gel electrolytes, such as influencing gelatin self-assembly and reducing local viscosity to promote facile ion transport.In this work, the contributions of the pathogenic Listeria monocytogenes cell-wall biomacromolecules to the bacterial mechanics and adhesion to a model inert surface of silicon nitride in water were investigated by atomic force microscopy. Chemical ethylenediaminetetraacetic acid (EDTA) and biological enzymatic trypsin treatments of cells were performed to partially or totally remove the bacterial cell-wall proteins and carbohydrates. Removal of 48.2% proteins and 29.2% of carbohydrates from the cell-wall of the bacterium by the EDTA treatment resulted in a significant decrease in the length of the bacterial cell-wall biomacromolecules and an increase in the rigidity of the bacterial cells as predicted from fitting a model of steric repulsion to the force-distance approach data and classic Hertz model to the indentation-force data, respectively. In comparison, removal of almost all the cell-wall proteins (99.5% removal) and 8.6% of cell-wall carbohydrates by the trypsin treatment resulted in an increase in the elasticity of the bacterial cells, an increase in the extension of the cell-wall biomacromolecules, and a significant decrease in their apparent grafting densities.