Quantum Sensing for Detection of Zinc-Triggered Free Radicals in Endothelial Cells

Oxidative stress originating from the overproduction of free radicals poses a major threat to cell fate, therefore it is of great importance to address the formation of free radicals in cells subjected to various pathological stimuli. Here we investigate the free radical response of endothelial cells to biodegradable zinc. In addition to the standard free radical assays, relaxometry was used for determining the production of free radicals in cells exposed to non-physiological concentrations of zinc ions. The cellular morphology, intracellular zinc accumulation, as well as the levels of reactive oxygen/nitrogen species, are determined using standard fluorescent methods. For endothelial cells subjected to 50% zinc extracts, deviations from the normal cell shape and cell agglomeration tendency are observed. The culture medium containing the highest amount of zinc ions caused nuclei fragmentation, blebbing, and cell shrinkage, indicating cell death. A potential explanation for the observed phenomena is an overproduction of free radicals. In the case of 1% and 10% zinc extracts, the formation of free radicals is clearly confirmed by relaxometry, while the results obtained by using fluorescent techniques are unambiguous. It is revealed that high concentrations of zinc ions released from biodegradable samples induce a deleterious effect on endothelial cells.</p

Texture-Governed Cell Response to Severely Deformed Titanium

The phenomenon of superior biological behavior , r it observed in titanium processed by an unconventional severe plastic deformation method, that is, hydrostatic extrusion, has been described within the present study. In doing so, specimens varying significantly in the crystallographic orientation of grains, yet exhibiting comparable grain refinement, were meticulously investigated. The aim was to find the clear origin of enhanced biocompatibility of titanium-based materials, having microstructures scaled down to the submicron range. Texture, microstructure, and surface characteristics, that is, wettability, roughness, and chemical composition, were examined as well as protein adsorption tests and cell response studies were carried out. It has been concluded that, irrespective of surface properties and mean grain size, the (10 (1) over bar0) crystallographic plane favors endothelial cell attachment on the surface of the severely deformed titanium. Interestingly, an enhanced albumin, fibronectin, and serum adsorption as well as dearly directional growth of the cells with preferentially oriented cell nuclei have been observed on the surfaces having (0001) planes exposed predominantly. Overall, the biological response of titanium fabricated by severe plastic deformation techniques is derived from the synergistic effect of surface irregularities, being the effect of refined microstructures, surface chemistry, and crystallographic orientation of grains rather than grain refinement itself

Scattering vector (h 2 k 2 l 2 ) Scattering vector (h 1 k 1 l 1 ) α α 2θ 2 t New developments of multireflection grazing incidence diffraction

Abstract. The multireflection grazing incident X-ray diffraction (MGIXD) is used to determine a stress gradient in thin surface layers (about 1-20 µm for metals). In this work two theoretical developments of this method are presented. The first procedure enables determination of c/a parameter in hexagonal polycrystalline materials exhibiting residual stresses. In the second method, the influence of stacking faults on the experimental data is considered. The results of both procedures were verified using X-rays diffraction. Introduction Multireflection grazing incidence X-ray diffraction (MGIXD) is a non-destructive method which allows performing an analysis of the heterogeneous stress field for different volumes below the surface of the sample. The penetration depth of X-ray radiation is well defined and does not change during experiment in a wide 2θ range for a given incidence angle

Study of damage process using self-consistent elastoplastic model

International audienceThe elastoplastic rate-independent self-consistent model has been used to predict influence of damage process on the mechanical behavior of polycrystalline material. In this model, the behavior of a crystal grain inside polycrystalline material under applied stresses is studied. The calculations are performed on two different scales: the macro-scale, where the average elastic and plastic macrostrains are defined, and the grain-scale, on which the behavior of each crystallite under stress is analyzed

Residual stress field in steel samples during plastic deformation and recovery processes

International audienceX-ray diffraction method was applied to measure residual stresses and stored elastic energy in deformed and annealed polycrystalline ferritic and austenitic steel samples. Orientation distribution of incompatibility stresses created during elastoplastic deformation was determined and presented in Euler space. Using deformation models, the second order stresses were correlated with different types of intergranular interactions occurring in the studied materials. An important decrease of the first and the second order residual stresses was observed during recovery and recrystallization processes. Diffraction peaks related to dislocations density were studied and correlated with stress variation during annealing process. Differences in stress relaxation between ferritic and austenitic samples were explained by different values of the stacking fault energy, which influences climb of dislocations