Formation Energy Profiles of Oxygen Vacancies at Grain Boundaries in Perovskite-Type Electroceramics

Oxygen vacancy formation energies play a major role in the electric field-assisted abnormal grain growth of technologically relevant polycrystalline perovskite phases. The underlying effect on the atomic scale is assumed to be a redistribution of cationic and anionic point defects between grain boundaries (GBs) and the bulk interior regions of the grains due to different defect formation energies in the structurally different regions, accompanied by the formation of space charge zones. Using atomistic calculations based on classical interatomic potentials, optimized structures of the symmetric tilt GBs Σ5(210)[001] and Σ5(310)[001], and of the asymmetric tilt GB (430)[001]||(100)[001] in the electroceramic perovskite materials SrTiO₃, BaTiO₃, and BaZrO₃, are derived and discussed. Profiles of oxygen vacancy formation energies across those GBs are presented and their dependence on composition and GB type is discussed.     

Atomic Migration and Ordering of Binary Ferromagnetic Intermetallic L10 Phases and Influences of Alloying Elements and Electric Fields

The ordered body-centered tetragonal intermetallic ${\text{L1}}_0$ phase of FeNi is a promising candidate for high-performance permanent magnets without rare-earth elements. However, on earth FeNi is found naturally only in the disordered face-centered-cubic A1 phase. Herein, the atomic migration and ordering processes in binary intermetallic ${\text{L1}}_0$ phases are investigated within the framework of density-functional theory. The main objectives are 1) to develop a thorough understanding of the thermally activated diffusion processes at the atomic scale and 2) to make a critical assessment in how far electric field and current effects can be effective means for an enhanced hardening-by-ordering of disordered, soft-ferromagnetic alloys. The scope is extended from FeNi to the hard-ferromagnetic ${\text{L1}}_0$ phases of FePt, FePd, MnAl, and MnGa as well as ternary Fe(Pt,Ni) alloys. These materials cover a wide range of thermal-ordering time scales and related experimental feasibility.     

Assessment of antimicrobial activity of melittin encapsulated in bicontinuous microemulsions prepared using renewable oils

The objective of this study is to demonstrate that melittin, a well-studied antimicrobial peptide (AMP), can be solubilized in an active form in bicontinuous microemulsions (BMEs) that employ biocompatible oils. The systems investigated consisted of Winsor-III and -IV BME phases composed of Water/Aerosol-OT (AOT)/Polysorbate 85/isopropyl myristate and a Winsor-IV BME employing Polysorbate 80 and limonene. We found that melittin resided in an α-helix-rich configuration and was in an apolar environment for the AOT/Polysorbate 85 Winsor-III system, suggesting that melittin interacted with the surfactant monolayer and was in an active conformation. An apolar environment was also detected for melittin in the two Winsor-IV systems, but to a lesser extent than the Winsor-III system. Small-angle X-ray scattering analysis indicated that melittin at a concentration of 1.0 g/L_aq in the aqueous subphase of the Winsor-IV systems led to the greatest impact on the BME structure (e.g., decrease of quasi-periodic repeat distance and correlation length and induction of interfacial fluidity). The antimicrobial activity of the Polysorbate 80 Winsor-IV system was evaluated against several bacteria prominent in chronic wounds and surgical site infections (SSIs). Melittin-free BMEs inhibited the growth of all tested bacteria due to its oil, limonene, while the inclusion of 1.0 g/L_aq of melittin in the BMEs enhanced the activity against several bacteria. A further increase of melittin concentration in the BMEs had no further enhancement. These results demonstrate the potential utility of BMEs as a delivery platform for AMPs and other hydrophilic and lipophilic drugs to inhibit antibiotic-resistant microorganisms in chronic wounds and SSIs.     

Repurposing of 8-Hydroxyquinoline-Based Butyrylcholinesterase and Cathepsin B Ligands as Potent Nonpeptidic Deoxyribonuclease I Inhibitors

A library of 31 butyrylcholinesterase (BChE) and cathepsin B (CatB) inhibitors was screened in vitro for inhibition of deoxyribonuclease I (DNase I). Compounds 22 , 8 and 7 are among the most potent synthetic non-peptide DNase I inhibitors reported to date. Three 8-hydroxyquinoline analogues inhibited both DNase I and BChE with IC₅₀ values below 35 μM and 50 nM, respectively, while two nitroxoline derivatives inhibited DNase I and Cat B endopeptidase activity with IC₅₀ values below 60 and 20 μM. Selected derivatives were screened for various co-target binding affinities at dopamine D₂ and D₃, histamine H₃ and H₄ receptors and inhibition of 5-lipoxygenase. Compound 8 bound to the H₃ receptor and is highlighted as the most promising multifunctional ligand with a favorable pharmacokinetic profile and one of the most potent non-peptide DNase I inhibitors. The present study demonstrates that 8-hydroxyquinoline is a structural fragment critical for DNase I inhibition in the presented series of compounds.