by Keyword: Mechanical properties

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Minguela, J., Ginebra, M. P., Llanes, L., Mas-Moruno, C., Roa, J. J., (2020). Influence of grinding/polishing on the mechanical, phase stability and cell adhesion properties of yttria-stabilized zirconia Journal of the European Ceramic Society 40, (12), 4304-4314

The changes in mechanical properties, hydrothermal degradation and cell adhesion were studied in 3Y-TZP under two different superficial modification patterns (uni- and multidirectional) with a surface roughness ranging from 16 to 603 nm. In this sense, mechanical properties (i.e. hardness, indentation fracture toughness and scratch) and accelerated tests in water steam were measured to evaluate the influence of the surface treatments on the superficially modified layer. Moreover, a detailed characterization through micro-Raman spectroscopy and X-Ray diffraction was performed. Finally, SaOS-2 osteoblasts were used for the evaluation of the cell adhesion behaviour on the surfaces. Overall, ground/polished specimens increased the mechanical properties and ageing resistance of mirror-like polished specimens, although resistance to degradation was maximum at intermediate conditions (Sa ≈ 40−180 nm). The studied surfaces allowed cell attachment, but promoted contact guidance (i.e. cell alignment) only on unidirectionally ground surfaces above Sa = 150 nm.

Keywords: Cell adhesion, Grinding, Hydrothermal degradation, Mechanical properties, Zirconia

Rajzer, I., Menaszek, E., Kwiatkowski, R., Planell, J. A., Castaño, O., (2014). Electrospun gelatin/poly(ε-caprolactone) fibrous scaffold modified with calcium phosphate for bone tissue engineering Materials Science and Engineering: C 44, 183-190

In this study gelatin (Gel) modified with calcium phosphate nanoparticles (SG5) and polycaprolactone (PCL) were used to prepare a 3D bi-layer scaffold by collecting electrospun PCL and gelatin/SG5 fibers separately in the same collector. The objective of this study was to combine the desired properties of PCL and Gel/SG5 in the same scaffold in order to enhance mineralization, thus improving the ability of the scaffold to bond to the bone tissue. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the wide angle X-ray diffraction (WAXD) measurements confirmed that SG5 nanoparticles were successfully incorporated into the fibrous gelatin matrix. The composite Gel/SG5/PCL scaffold exhibited more enhanced mechanical properties than individual Gel and Gel/SG5 scaffolds. The presence of SG5 nanoparticles accelerated the nucleation and growth of apatite crystals on the surface of the composite Gel/SG5/PCL scaffold in simulated body fluid (SBF). The osteoblast response in vitro to developed electrospun scaffolds (PCL and Gel/SG5/PCL) was investigated by using normal human primary NHOst cell lines. NHOst cell culture studies showed that higher alkaline phosphatase (ALP) activity and better mineralization were obtained in the case of composite materials than in pure PCL scaffolds. The mechanically strong PCL scaffold served as a skeleton, while the Gel/SG5 fibers facilitated cell spreading and mineralization of the scaffold.

Keywords: Bilayer fibrous scaffold, Ceramic nanoparticles, Electrospinning, Gelatin, Polycaprolactone, Biomechanics, Bone, Calcium phosphate, Cell culture, Electrospinning, Fourier transform infrared spectroscopy, Mechanical properties, Mineralogy, Nanoparticles, Phosphatases, Polycaprolactone, Scanning electron microscopy, X ray diffraction, Polycaprolactone, Alkaline phosphatase activity, Bone tissue engineering, Calcium phosphate nanoparticles, Ceramic nanoparticles, Fibrous scaffolds, Gelatin, Simulated body fluids, Wide-angle x-ray diffraction, Electrospuns, Scaffolds (biology), Electrospinning

Stocchi, A., Lauke, B., Giannotti, M. I., Vázquez, A., Bernal, C., (2013). Tensile response and fracture and failure behavior of jute fabrics-flyash-vinylester hybrid composites Fibers and Polymers , 14, (2), 285-291

In this work, hybrid materials consisting on a vinylester matrix simultaneaously reinforced with jute woven fabrics and flyash particles were prepared. The tensile response and the fracture and failure behavior of these hybrid composites were investigated. Thermal stability of these materials was also studied. The aim was to obtain an environmentally friendly hybrid material with a good balance of tensile and fracture properties at relatively low cost. The effect of a novel treatment for the jute fabrics on the hybrids mechanical and fracture properties was investigated. The best balance of tensile and fracture properties was obtained for the hybrid consisting of fabrics treated with alkali under stress and fly ashes which also exhibited relatively high thermal stability.

Keywords: Natural fibers, Fly ash, Hybrid composite, Mechanical properties, Fracture

Serra, T., Navarro, M., Planell, J. A., (2012). Fabrication and characterization of biodegradable composite scaffolds for tissue engineering Innovative Developments in Virtual and Physical Prototyping 5th International Conference on Advanced Research and Rapid Prototyping (ed. Margarida, T., Ferreira, D.), Taylor & Francis (Leiria, Portugal) VR@P, 67-72

In this study, polylactic acid (PLA) and polyethylene glycol (PEG) were combined with soluble CaP glass particles and processed by rapid prototyping to obtain fully biodegradable structures for Tissue Engineering applications. The obtained 3D biodegradable structures were characterized in terms of their architecture and mechanical properties. The scaffold morphology, internal micro-architecture and mechanical properties were evaluated using Scanning Electron Microscopy (SEM), micro-computed tomography (micro-CT) and mechanical testing, respectively. Well defined structures with pore size of 350-400μm (in the axial view), struts width of approximately 70-80μm, and a porosity ranging between 60-65% were obtained. The combination RP and PLA/PEG/CaP glass turned into promising fully degradable, mechanically stable, bioactive and biocompatible composite scaffolds for TE.

Keywords: Axial view, Biodegradable composites, Composite scaffolds, Glass particles, Mechanically stable, Micro architectures, Micro computed tomography (micro-CT), Poly lactic acid, Scaffold morphology, Tissue engineering applications, Well-defined structures, Bioactive glass, Mechanical properties, Mechanical testing, Polyethylene glycols, Polymer blends, Rapid prototyping, Scaffolds (biology), Scanning electron microscopy, Computerized tomography

Tambe, Dhananjay T., Corey Hardin, C., Angelini, Thomas E., Rajendran, Kavitha, Park, Chan Young, Serra-Picamal, Xavier, Zhou, Enhua H., Zaman, Muhammad H., Butler, James P., Weitz, David A., Fredberg, Jeffrey J., Trepat, X., (2011). Collective cell guidance by cooperative intercellular forces Nature Materials 10, (6), 469-475

Cells comprising a tissue migrate as part of a collective. How collective processes are coordinated over large multi-cellular assemblies has remained unclear, however, because mechanical stresses exerted at cell–cell junctions have not been accessible experimentally. We report here maps of these stresses within and between cells comprising a monolayer. Within the cell sheet there arise unanticipated fluctuations of mechanical stress that are severe, emerge spontaneously, and ripple across the monolayer. Within that stress landscape, local cellular migrations follow local orientations of maximal principal stress. Migrations of both endothelial and epithelial monolayers conform to this behaviour, as do breast cancer cell lines before but not after the epithelial–mesenchymal transition. Collective migration in these diverse systems is seen to be governed by a simple but unifying physiological principle: neighbouring cells join forces to transmit appreciable normal stress across the cell–cell junction, but migrate along orientations of minimal intercellular shear stress.

Keywords: Biological materials, Mechanical properties

Roa, J. J., Oncins, G., Diaz, J., Capdevila, X. G., Sanz, F., Segarra, M., (2011). Study of the friction, adhesion and mechanical properties of single crystals, ceramics and ceramic coatings by AFM Journal of the European Ceramic Society 31, (4), 429-449

This paper reviews commonly used methods of analyzing and interpreting friction, adhesion and nanoindentation with an AFM tip test data, with a particular emphasis of the testing of single crystals, metals, ceramics and ceramic coatings. Experimental results are reported on the friction, mechanical and adhesion properties of these materials. The popularity of AFM testing is evidenced by the large quantity of papers that report such measurements in the last decade. Unfortunately, a lot of information about these topics is scare in the literature. The present paper is aimed to present the basic physical modelling employed and also some examples using each technique.

Keywords: Mechanical properties, Plasticity, Biomedical applications, Engine components

Lacroix, D., (2009). Biomechanical aspects of bone repair Bone repair biomaterials (ed. Planell, J. A., Lacroix, D., Best, S., Merolli, A.), Woodhead (Cambridge, UK)

A fundamental aspect of the rapidly expanding medical care sector, bone repair continues to benefit from emerging technological developments. This text provides researchers and students with a comprehensive review of the materials science and engineering principles behind these developments. The first part reviews the fundamentals of bone repair and regeneration. Further chapters discuss the science and properties of biomaterials used in bone repair, including both metals and biocomposites. Final chapters analyze device considerations such as implant lifetime and failure, and discuss potential applications, as well as the ethical issues that continually confront researchers and clinicians.

Keywords: Bone composition and structure, Biomechanical properties of bone, Bone damage and repair