Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures.

• Klíčová slova
• 316L stainless steel, Porous implants, Scaffolds, Selective laser melting,
• MeSH
• fotoelektronová spektroskopie MeSH
• lasery * MeSH
• lidé MeSH
• modul pružnosti účinky léků   MeSH
• nádorové buněčné linie MeSH
• nerezavějící ocel farmakologie   MeSH
• pevnost v tahu účinky léků   MeSH
• poréznost MeSH
• povrchové vlastnosti MeSH
• testování materiálů metody   MeSH
• tvar buňky MeSH
• železo farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• nerezavějící ocel MeSH
• SUS 316L MeSH Prohlížeč
• železo MeSH

Ti-based alloys have increased importance for biomedical applications due to their excellent properties. In particular, the two recently developed TiZrPdSi(Nb) alloys, with a predominant β-Ti phase microstructure, have good mechanical properties, such as a relatively low Young's modulus and high hardness. In the present work, the cytocompatibility of these alloys was assessed using human osteoblast-like Saos-2 cells. Cells grown on the alloys showed larger spreading areas (more than twice) and higher vinculin content (nearly 40% increment) when compared with cells grown on glass control surfaces, indicating a better cell adhesion. Moreover, cell proliferation was 18% higher for cells growing on both alloys than for cells growing on glass and polystyrene control surfaces. Osteogenic differentiation was evaluated by quantifying the expression of four osteogenic genes (osteonectin, osteocalcin, osteopontin, and bone sialoprotein), the presence of three osteogenic proteins (alkaline phosphatase, collagen I, and osteocalcin) and the activity of alkaline phosphatase at different time-points. The results demonstrated that TiZrPdSi and TiZrPdSiNb alloys enhance osteoblast differentiation, and that cells grown on TiZrPdSiNb alloy present higher levels of some late osteogenic markers during the first week in culture. These results suggest that the TiZrPdSi(Nb) alloys can be considered as excellent candidates for orthopaedical uses. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 834-842, 2018.

• Klíčová slova
• Saos-2 cells, Ti-based alloy, cytocompatibility, osteogenic gene expression, protein adsorption,
• MeSH
• buněčná diferenciace účinky léků   MeSH
• buněčné linie MeSH
• lidé MeSH
• modul pružnosti * MeSH
• niob chemie   farmakologie   MeSH
• osteoblasty cytologie   metabolismus   MeSH
• osteogeneze účinky léků   MeSH
• palladium chemie   farmakologie   MeSH
• silikony chemie   farmakologie   MeSH
• slitiny * chemie   farmakologie   MeSH
• testování materiálů * MeSH
• titan chemie   farmakologie   MeSH
• zirkonium chemie   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• niob MeSH
• palladium MeSH
• silikony MeSH
• slitiny * MeSH
• titan MeSH
• zirkonium MeSH

A new method to estimate the selected viscoelastic parameters of foods using damped vibration analysis is presented for the evaluation of fruits and baked products. A flat disk is attached to the flat sample surface using a laser rangefinder that measures the sample thickness in advance, and it is locked by a trigger. Next, the trigger is released to allow the probe to press the sample through the force of gravity. The damped vibration of the probe caused by the deformation of the food is measured by monitoring the displacement of the probe via a linear encoder. The bulk modulus and viscosity are estimated using the fractional Zener model and mass. Young's modulus (E) is estimated independently by determining the maximum velocity of the probe using Hooke's law. Poisson's ratio (ν), and the shear modulus and viscosity are calculated by employing the estimated E and bulk modulus. The bulk modulus, bulk viscosity, shear modulus, shear viscosity, and E of apples were found to be higher than those of bananas. The bulk modulus, bulk viscosity, E, and shear modulus for white bread were lower than those for pound cake, but the ν values were higher, whereas those of sponge cake were intermediate. After drying the baked products for 1 day, most of the parameters of the samples increased, but the value of ν for white bread decreased. The proposed free-falling device estimated the four viscoelastic coefficients, Poisson's ratio, and Young's modulus of the food sample in less than 1 s.

• Klíčová slova
• apple, baked food, banana, damped vibration, free-falling probe,
• MeSH
• modul pružnosti MeSH
• pružnost * MeSH
• viskozita MeSH
• Publikační typ
• časopisecké články MeSH

Evaluation of creep compliance of particulate composites using empirical models always provides parameters depending on initial stress and material composition. The effort spent to connect model parameters with physical properties has not resulted in success yet. Further, during the creep, delamination between matrix and filler may occur depending on time and initial stress, reducing an interface adhesion and load transfer to filler particles. In this paper, the creep compliance curves of glass beads reinforced poly(butylene terephthalate) composites were fitted with Burgers and Findley models providing different sets of time-dependent model parameters for each initial stress. Despite the finding that the Findley model performs well in a primary creep, the Burgers model is more suitable if secondary creep comes into play; they allow only for a qualitative prediction of creep behavior because the interface adhesion and its time dependency is an implicit, hidden parameter. As Young's modulus is a parameter of these models (and the majority of other creep models), it was selected to be introduced as a filler content-dependent parameter with the help of the cube in cube elementary volume approach of Paul. The analysis led to the time-dependent creep compliance that depends only on the time-dependent creep of the matrix and the normalized particle distance (or the filler volume content), and it allowed accounting for the adhesion effect. Comparison with the experimental data confirmed that the elementary volume-based creep compliance function can be used to predict the realistic creep behavior of particulate composites.

• Klíčová slova
• adhesion factor, creep, creep compliance, cube in cube model, elementary volume, modeling, particulate composite,
• MeSH
• modul pružnosti MeSH
• testování materiálů * MeSH
• Publikační typ
• časopisecké články MeSH

Polypropylene (PP) belongs among the most important commodity plastics due to its widespread application. The color of the PP products can be achieved by the addition of pigments, which can dramatically affect its material characteristics. To maintain product consistency (dimensional, mechanical, and optical), knowledge of these implications is of great importance. This study investigates the effect of transparent/opaque green masterbatches (MBs) and their concentration on the physico-mechanical and optical properties of PP produced by injection molding. The results showed that selected pigments had different nucleating abilities, affecting the dimensional stability and crystallinity of the product. The rheological properties of pigmented PP melts were affected as well. Mechanical testing showed that the presence of both pigments increased the tensile strength and Young's modulus, while the elongation at break was significantly increased only for the opaque MB. The impact toughness of colored PP with both MBs remained similar to that of neat PP. The optical properties were well controlled by the dosing of MBs, and were further related to the RAL color standards, as demonstrated by CIE color space analysis. Finally, the selection of appropriate pigments for PP should be considered, especially in areas where dimensional and color stability, as well as product safety, are highly important.

• Klíčová slova
• injection molding, mechanical testing, pigments, polypropylene,
• MeSH
• houby MeSH
• modul pružnosti MeSH
• plastické hmoty * MeSH
• polypropyleny * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• plastické hmoty * MeSH
• polypropyleny * MeSH

A biodegradable blend of PBAT-poly(butylene adipate-co-terephthalate)-and PLA-poly(lactic acid)-for blown film extrusion was modified with four multi-functional chain extending cross-linkers (CECL). The anisotropic morphology introduced during film blowing affects the degradation processes. Given that two CECL increased the melt flow rate (MFR) of tris(2,4-di-tert-butylphenyl)phosphite (V1) and 1,3-phenylenebisoxazoline (V2) and the other two reduced it (aromatic polycarbodiimide (V3) and poly(4,4-dicyclohexylmethanecarbodiimide) (V4)), their compost (bio-)disintegration behavior was investigated. It was significantly altered with respect to the unmodified reference blend (REF). The disintegration behavior at 30 and 60 °C was investigated by determining changes in mass, Young's moduli, tensile strengths, elongations at break and thermal properties. In order to quantify the disintegration behavior, the hole areas of blown films were evaluated after compost storage at 60 °C to calculate the kinetics of the time dependent degrees of disintegration. The kinetic model of disintegration provides two parameters: initiation time and disintegration time. They quantify the effects of the CECL on the disintegration behavior of the PBAT/PLA compound. Differential scanning calorimetry (DSC) revealed a pronounced annealing effect during storage in compost at 30 °C, as well as the occurrence of an additional step-like increase in the heat flow at 75 °C after storage at 60 °C. The disintegration consists of processes which affect amorphous and crystalline phase of PBAT in different manner that cannot be understood by a hydrolytic chain degradation only. Furthermore, gel permeation chromatography (GPC) revealed molecular degradation only at 60 °C for the REF and V1 after 7 days of compost storage. The observed losses of mass and cross-sectional area seem to be attributed more to mechanical decay than to molecular degradation for the given compost storage times.

• Klíčová slova
• blown film, chain extending cross-linker, degree of disintegration, disintegration kinetics, molecular mass degradation, poly(butylene adipate terephthalate), poly(lactic acid),
• MeSH
• film jako téma MeSH
• kompostování * MeSH
• modul pružnosti MeSH
• pevnost v tahu MeSH
• polyestery chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• polyestery MeSH

Despite the wide choice of commercial heart valve prostheses, cryopreserved semilunar allograft heart valves (C-AHV) are required, and successfully transplanted in selected groups of patients. The expiration limit (EL) criteria have not been defined yet. Most Tissue Establishments (TE) use the EL of 5 years. From physiological, functional, and surgical point of view, the morphology and mechanical properties of aortic and pulmonary roots represent basic features limiting the EL of C-AHV. The aim of this work was to review methods of AHV tissue structural analysis and mechanical testing from the perspective of suitability for EL validation studies. Microscopic structure analysis of great arterial wall and semilunar leaflets tissue should clearly demonstrate cells as well as the extracellular matrix components by highly reproducible and specific histological staining procedures. Quantitative morphometry using stereological grids has proved to be effective, as the exact statistics was feasible. From mechanical testing methods, tensile test was the most suitable. Young's moduli of elasticity, ultimate stress and strain were shown to represent most important AHV tissue mechanical characteristics, suitable for exact statistical analysis. C-AHV are prepared by many different protocols, so as each TE has to work out own EL for C-AHV.

• Klíčová slova
• Cryopreservation, Expiration limit, Heart valve allograft, Mechanical measurements, Quantitative microscopy, Tissue banking,
• MeSH
• alografty MeSH
• aorta MeSH
• aortální chlopeň * chirurgie   MeSH
• kryoprezervace * MeSH
• lidé MeSH
• modul pružnosti MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The demand for biomaterials has been increasing along with the increase in the population of elderly people worldwide. The mechanical properties and high wear resistance of metallic biomaterials make them well-suited for use as substitutes or as support for damaged hard tissues. However, unless these biomaterials also have a low Young's modulus similar to that of human bones, bone atrophy inevitably occurs. Because a low Young's modulus is typically associated with poor wear resistance, it is difficult to realize a low Young's modulus and high wear resistance simultaneously. Also, the superelastic property of shape-memory alloys makes them suitable for biomedical applications, like vascular stents and guide wires. However, due to the low recoverable strain of conventional biocompatible shape-memory alloys, the demand for a new alloy system is high. The novel body-centered-cubic cobalt-chromium-based alloys in this work provide a solution to both of these problems. The Young's modulus of <001>-oriented single-crystal cobalt-chromium-based alloys is 10-30 GPa, which is similar to that of human bone, and they also demonstrate high wear and corrosion resistance. They also exhibit superelasticity with a huge recoverable strain up to 17.0%. For these reasons, the novel cobalt-chromium-based alloys can be promising candidates for biomedical applications.

• Klíčová slova
• Co-Cr-Al-Si, biomaterials, low Young's modulus, shape-memory alloys, superelasticity,
• MeSH
• biokompatibilní materiály chemie   MeSH
• chrom MeSH
• kobalt MeSH
• lidé MeSH
• modul pružnosti MeSH
• senioři MeSH
• slitiny s tvarovou pamětí * MeSH
• slitiny * chemie   MeSH
• testování materiálů MeSH
• titan chemie   MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• chrom MeSH
• kobalt MeSH
• slitiny s tvarovou pamětí * MeSH
• slitiny * MeSH
• titan MeSH

Nanosecond pulsed electric fields (nsPEFs) applied to cells can induce different biological effects depending on pulse duration and field strength. One known process is the induction of apoptosis whereby nsPEFs are currently investigated as a novel cancer therapy. Another and probably related change is the breakdown of the cytoskeleton. We investigated the elasticity of rat liver epithelial cells WB-F344 in a monolayer using atomic force microscopy (AFM) with respect to the potential of cells to undergo malignant transformation or to develop a potential to metastasize. We found that the elastic modulus of the cells decreased significantly within the first 8 min after treatment with 20 pulses of 100 ns and with a field strength of 20 kV/cm but was still higher than the elasticity of their tumorigenic counterpart WB-ras. AFM measurements and immunofluorescent staining showed that the cellular actin cytoskeleton became reorganized within 5 min. However, both a colony formation assay and a cell migration assay revealed no significant changes after nsPEF treatment, implying that cells seem not to adopt malignant characteristics associated with metastasis formation despite the induced transient changes to elasticity and cytoskeleton that can be observed for up to 1 h.

• Klíčová slova
• AFM, Actin cytoskeleton, Anchorage-independent growth, Elastic modulus, Elasticity, nsPEF,
• MeSH
• aktiny metabolismus   MeSH
• buněčné linie MeSH
• časové faktory MeSH
• elektřina * MeSH
• karcinogeneze * MeSH
• metastázy nádorů MeSH
• pohyb buněk MeSH
• proliferace buněk MeSH
• pružnost * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aktiny MeSH

Low-modulus biomedical beta titanium alloys often suffer from low strength which limits their use as load-bearing orthopaedic implants. In this study, twelve different Ti-Nb-Zr-Ta based alloys alloyed with Fe, Si and O additions were prepared by arc melting and hot forging. The lowest elastic modulus (65GPa) was achieved in the benchmark TNTZ alloy consisting only of pure β phase with low stability due to the 'proximity' to the β to α'' martensitic transformation. Alloying by Fe and O significantly increased elastic modulus, which correlates with the electrons per atom ratio (e/a). Sufficient amount of Fe/O leads to increased yield stress, increased elongation to fracture and also to work hardening during deformation. A 20% increase in strength and a 20% decrease in the elastic modulus when compared to the common Ti-6Al-4V alloy was achieved in TNTZ-Fe-Si-O alloys, which proved to be suitable for biomedical use due to their favorable mechanical properties.

• Klíčová slova
• Ductility, Elastic modulus, Orthopaedic implants, Strengthening mechanisms, Ultrasound spectroscopy, β-Ti alloys,
• MeSH
• biokompatibilní materiály analýza   MeSH
• křemík MeSH
• kyslík MeSH
• modul pružnosti MeSH
• niob MeSH
• slitiny analýza   MeSH
• tantal MeSH
• testování materiálů MeSH
• titan MeSH
• zatížení muskuloskeletálního systému MeSH
• železo MeSH
• zinek MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• křemík MeSH
• kyslík MeSH
• niob MeSH
• slitiny MeSH
• tantal MeSH
• titan MeSH
• titanium alloy (TiAl6V4) MeSH Prohlížeč
• železo MeSH
• zinek MeSH