Abstract: Cold atmospheric plasma (CAP) is a promising technology for several medical applications, including the removal of biofilms from surfaces. However, the molecular mechanisms of CAP treatment are still poorly understood. Here we unravel the possible mechanisms of CAP‐induced oxidation of oligosaccharides, employing reactive molecular dynamics simulations based on the density functional‐tight binding potential. Specifically, we find that the interaction of oxygen atoms (used as CAP‐generated reactive species) with cellotriose (a model system for the oligosaccharides) can break structurally important glycosidic bonds, which subsequently leads to the disruption of the oligosaccharide molecule. The overall results help to shed light on our experimental evidence for cellotriose CAP. This oxidation by study provides atomic‐level insight into the onset of plasma‐induced removal of biofilms, as oligosaccharides are one of the main components of biofilm.

Abstract: For oxygen conducting materials applied in solid oxide fuel cells and chemical-looping processes, the understanding of the oxygen diffusion mechanism and the materials’ crystal structure at different stages of the redox reactions is a key parameter to control their performance. In this paper we report the first ever in situ 3D ED experiment in a gas environment and with it uncover the structure evolution of SrFeO2.5 as notably different from that reported from in situ X-ray and in situ neutron powder diffraction studies in gas environments. Using in situ 3D ED on submicron sized single crystals obtained from a high quality monodomain SrFeO2.5 single crystal , we observe the transformation under O2 flow of SrFeO2.5 with an intra- and interlayer ordering of the left and right twisted (FeO4) tetrahedral chains (space group Pcmb) into consecutively SrFeO2.75 with space group Cmmm (at 350°C, 33% O2) and SrFeO3-δ with space group Pm3 ̅m (at 400°C, 100% O2). Upon reduction in H2 flow, the crystals return to the brownmillerite structure with intralayer order, but without regaining the interlayer order of the pristine crystals. Therefore, redox cycling of SrFeO2.5 crystals in O2 and H2 introduces stacking faults into the structure, resulting in an I2/m(0βγ)0s symmetry with variable β.

Abstract: A crucial property for implants is their biocompatibility. To ensure biocompatibility, thin coatings of hydroxyapatite (HA) are deposited on the actual implant. In this study, we investigate the effects of the addition of silicate anions to the structure of hydroxyapatite coatings on their adhesion strength via a scratch test and ab initio calculations. We find that both the grain size and adhesion strength decrease with the increase in the silicon content in the HA coating (SiHA). The increase in the silicon content to 1.2 % in the HA coating leads to a decrease in the average crystallite size from 28 to 21 nm, and in the case of 4.6 %, it leads to the formation of an amorphous or nanocrystalline film. The decreases in the grain and crystallite sizes lead to peeling and destruction of the coating from the titanium substrate at lower loads. Further, our ab initio simulations demonstrate an increased number of molecular bonds at the amorphous SiHA-TiO2 interface. However, the experimental results revealed that the structure and grain size have more pronounced effects on the adhesion strength of the coatings. In conclusion, based on the results of the ab initio simulations and the experimental results, we suggest that the presence of Si in the form of silicate ions in the HA coating has a significant impact on the structure, grain size, and number of molecular bonds at the interface and on the adhesion strength of the SiHA coating to the titanium substrate.

Abstract: We investigate at the atomic level the most probable phase transformations under strain, that are responsible for the ferroelectric/ antiferroelectric behavior in Hf1-xZrxO2 materials. Four different crystalline phase transformations exhibit a polar/non-polar transition: monoclinic-to-orthorhombic requires a gliding strain tensor, orthorhombic-to-orthorhombic transformation does not need strain to polarize the material, whereas tetragonal-to-cubic cell compression and tetragonal-to-orthorhombic cell elongation destabilizes the non-polar tetragonal phase, facilitating the transition towards a polar atomic configuration, therefore changing the polarization-electric field loop from antiferroelectric to ferroelectric. Oxygen vacancies can reduce drastically the polarization reversal barriers.

Abstract: This study presents novel sulfolane based non-aqueous CO2 capture solvents, as an alternative solution for capturing CO2 from industrial processes. In order to select the most promising amine system, five different amines were tested by monitoring CO2 absorption and desorption processes using the time-base Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. During absorption experiments, we observed the formation of Monomethyl Carbonate (MMC) in diisopropylamine (DIPA) and 2-amino-2-methyl-1-propanol (AMP) systems, while carbamate was observed as the main product for the other three amine systems tested. In regeneration experiments, the MMC could be desorbed relatively easily from the amine solution at a mild temperature.