Nanoscale Electrical Potential and Roughness of a Calcium Phosphate Surface Promotes the Osteogenic Phenotype of Stromal Cells

Mesenchymal stem cells (MSCs) and osteoblasts respond to the surface electrical charge and topography of biomaterials. This work focuses on the connection between the roughness of calcium phosphate (CP) surfaces and their electrical potential (EP) at the micro- and nanoscales and the possible role of these parameters in jointly affecting human MSC osteogenic differentiation and maturation in vitro. A microarc CP coating was deposited on titanium substrates and characterized at the micro- and nanoscale. Human adult adipose-derived MSCs (hAMSCs) or prenatal stromal cells from the human lung (HLPSCs) were cultured on the CP surface to estimate MSC behavior. The roughness, nonuniform charge polarity, and EP of CP microarc coatings on a titanium substrate were shown to affect the osteogenic differentiation and maturation of hAMSCs and HLPSCs in vitro. The surface EP induced by the negative charge increased with increasing surface roughness at the microscale. The surface relief at the nanoscale had an impact on the sign of the EP. Negative electrical charges were mainly located within the micro- and nanosockets of the coating surface, whereas positive charges were detected predominantly at the nanorelief peaks. HLPSCs located in the sockets of the CP surface expressed the osteoblastic markers osteocalcin and alkaline phosphatase. The CP multilevel topography induced charge polarity and an EP and overall promoted the osteoblast phenotype of HLPSCs. The negative sign of the EP and its magnitude at the micro- and nanosockets might be sensitive factors that can trigger osteoblastic differentiation and maturation of human stromal cells

A review of geophysical studies of the lithosphere in the Carpathian–Pannonian region

International audienceHere, we revisit the most prominent features of the complete Bouguer anomaly map and their interpretation, along with the current knowledge of the lithospheric thickness in the Carpathian–Pannonian region. The stripped gravity map, i.e., the sediment-stripped complete Bouguer anomaly map, was used to interpret the most prominent highs and lows of the gravity field. The complete Bouguer anomaly data were used in structural density modelling and integrated geophysical modelling to determine or revise the previously known sources of the most pronounced gravity features of the region. The Carpathian gravity low was divided into three sub-lows: the Western, Eastern, and Southern. The Western Carpathian gravity low consists of the clearly distinguishable External and Internal lows, which are due to different causes. The source of the External Western Carpathian gravity low reflects the low-density sediments of the External Western Carpathians (2.49–2.59 g cm–3) and the Foredeep (~2.43 g cm–3), while the Internal Western Carpathian gravity low is explained by the upper crustal deficit mass, which is formed by the rocks of the Alpine Tatric and Veporic units. These tectonic units are built mainly from granites and crystalline schists, of which the average density (~2.70 g cm–3) is lower than the average density of the lower crust of the Internal Western Carpathians (~2.90 g cm–3). The main sources of the Eastern and Southern Carpathian gravity lows are the gravity effects of the crustal roots created by continental collision, the Foredeep, and the surface sediments of the External Carpathians. The Pannonian gravity high is caused by the expressive Moho elevation (24–26 km). Since the Pannonian Basin upper mantle, which is built by high-density peridotites or dunites, is located several kilometres closer to the surface, this rock material represents a great excess mass (high-density anomalous bodies). Based on the calculated stripped gravity map, several local gravity highs (˃ +50 mGal) have been recognised, and they are all located in the Danube Basin, the Transcarpathian Basin, the Békés Basin, as well as the Makó trough. Their sources are high-density crustal bodies (Eo-Alpine metamorphic complexes), whose apical parts reach depths of only 7 to 12 km. Finally, the expressive different depths of the lithosphere-asthenosphere boundary in the Western and Eastern Carpathians were explained by the different Neo-Alpine development of both orogens. The mantle lithospheric root (~240 km) in the Eastern Carpathians is results from the sinking of the upper part of the broken slab during the frontal continental collision. On the contrary, no thickening of the mantle lithosphere was observed in the junction zone of the Western Carpathians and the Bohemian Massif. The typical thickness of the continental lithosphere (~100 km) in this zone was explained by the oblique continental collision. The Pannonian Basin system is characterised by one of the thinnest continental crusts (~25 km) and lithospheres (~75 km) in the world

Analyzing the Deformation and Fracture of Bioinert Titanium, Zirconium and Niobium Alloys in Different Structural States by the Use of Infrared Thermography

Bioinert metals are used for medical implants and in some industrial applications. This study was performed to detect and analyze peculiarities that appear in the temperature distributions during quasi-static tensile testing of bioinert alloys. These alloys include VT1-0 titanium, Zr-1%Nb and Ti-45%Nb in both coarse-grain (CG) and ultrafine-grain (UFG) states. The crystal structure, as well as the crystal domain and grain sizes of these alloys in the UFG state, may be different from the CG versions and identifying the thermal signatures that occur during their deformation and fracture is of interest, as it may lead to an understanding of physical processes that occur during loading. By comparing the surface temperature distributions of specimens undergoing deformation under tensile loading to the distributions at maximum temperatures it was found that the observed differences depend on the alloy type, the alloy structural state and the thermal properties of structural defects in the specimen. Macro-defects were found in some specimens of VT1-0 titanium, Zr-1Nb and Ti-45Nb alloys in both the CG and UFG states. The average tensile strength of specimens containing defects was lower than that of specimens with no defects. Infrared thermography documents change in the thermal patterns of specimens as they are deformed under tensile loading and when the load stops changing or the specimen breaks

Development of ultrafine-grained and nanostructured bioinert alloys based on titanium, zirconium and niobium and their microstructure, mechanical and biological properties

For this paper, studies of the microstructure as well as the mechanical and biological properties of bioinert titanium, zirconium, and niobium alloys in their nanostructured (NS) and ultrafine-grained (UFG) states have been completed. The NS and UFG states were formed by a combined two-step method of severe plastic deformation (SPD), first with multidirectional forging (MDF) or pressing into a symmetrical channel (PSC) at a given temperature regime, and then subsequent multi-pass groove rolling (MPGR) at room temperature, with pre-recrystallization annealing. Annealing increased the plasticity of the alloys in the NS and UFG states without changing the grain size. The UFG structure, with an average size of structural elements of no more than 0.3 mu m, was formed as a result of applying two-step SPD and annealing. This structure presented significant improvement in the mechanical characteristics of the alloys, in comparison with the alloys in the coarse-grained (CG) or small-grained (SG) states. At the same time, although the formation of the UFG structure leads to a significant increase in the yield strength and tensile strength of the alloys, their elastic modulus did not change. In terms of biocompatibility, the cultivation of MG-63 osteosarcoma cells on the polished and sandblasted substrates demonstrated high cell viability after 10 days and good cell adhesion to the surface

Influence of Zr-1 wt.% Nb alloy structure state on its deformation and thermal behavior under quasi-static tension

The influence of the average size of the structure elements on the deformation and thermal behavior of the Zr-1 wt.% Nb (Zr1-Nb) alloy under quasi-static tension was investigated using the digital image correlation and infrared thermography methods. It is shown that with increasing average size of the structural elements in the range 0.2–2.0 mm the physico-mechanical properties, such as yield strength, microhardness, maximal true strain, and maximal temperature increment during deformation decrease, while longitudinal and transverse strain increase. According to the obtained results, correlations between the mentioned deformation characteristics and the average size of the structural element d–1/2 can be described by linear functions