Zeolite-based chiral ion-exchangers for chromatographic enantioseparations and potential applications in membrane separation processes.

Chiral resolution of racemic compounds represents an important task in research and development and, most importantly, in the large-scale production of pharmaceuticals. Zeolites, which are already frequently utilized for their unique properties, represent materials that can be used for the development of new chiral stationary phases for liquid chromatography, simulated moving bed or enantioselective membranes. The aim of this study was to modify a series of MWW zeolites by a chiral anion-exchange type selector thereby creating a chiral stationary phase for enantiomeric resolution of acidic compounds.

Elucidating Primary Degradation Mechanisms in High-Cycling-Capacity, Compositionally Tunable High-Entropy Hydrides.

The hydrogen sorption properties of single-phase bcc (TiVNb)Cr alloys ( = 0-35) are reported. All alloys absorb hydrogen quickly at 25 °C, forming fcc hydrides with storage capacity depending on the Cr content. A thermodynamic destabilization of the fcc hydride is observed with increasing Cr concentration, which agrees well with previous compositional machine learning models for metal hydride thermodynamics.

Fatigue Crack Growth Rate Description of RF-Plasma-Sprayed Refractory Metals and Alloys.

A fitting method capable of describing the fatigue crack growth rate (FCGR) data in all stages of crack propagation by a simple Forman-style analytical formula was developed. To demonstrate its robustness, this method was used to quantify the fracture behavior of RF-plasma-sprayed W, Mo, W-Mo composite, and four selected Ni-based tungsten heavy alloys (WHA). The fitted FCGR parameters categorized the studied materials into two distinct sets.

Relation between Ga Vacancies, Photoluminescence, and Growth Conditions of MOVPE-Prepared GaN Layers.

A set of GaN layers prepared by metalorganic vapor phase epitaxy under different technological conditions (growth temperature carrier gas type and Ga precursor) were investigated using variable energy positron annihilation spectroscopy (VEPAS) to find a link between technological conditions, GaN layer properties, and the concentration of gallium vacancies (V). Different correlations between technological parameters and V concentration were observed for layers grown from triethyl gallium (TEGa) and trimethyl gallium (TMGa) precursors. In case of TEGa, the formation of V was significantly influenced by the type of reactor atmosphere (N or H), while no similar behaviour was observed for growth from TMGa.