Electro-Mechanical Behavior of Wet Bone—Part I: Theory

1984 ◽  
Vol 106 (3) ◽  
pp. 249-261 ◽  
Author(s):  
N. Guzelsu ◽  
S. Saha
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Bone Tissue ◽  
Bone Matrix ◽  
Hydrogen Ions ◽  
Mechanical Effects ◽  
Substantial Interest ◽  
Stimulation Of

The remodeling properties of bones due to various stimuli have been of substantial interest to the scientists. Examination of electro-mechanical properties of bone and their relation to remodeling and osteogenesis have been investigated mainly by experimental means. In this study, by using continuum physics, it is shown that the remodeling of bones can be formulated theoretically in terms of electrical and mechanical effects. The interactions among the constituents of bone (bone matrix, bone salts, electrolytes and hydrogen ions) and effects of various stimuli (mechnical, electrical and chemical) on the remodeling mechanism of bone tissue are interpreted with this model. Moreover, the stimulation of osteogenesis by electrical means is predicted.

Influence of strain rate on the mechanical behavior of cortical bone interstitial lamellae at the micrometer scale

2006 ◽  
Vol 21 (8) ◽  
pp. 2093-2097 ◽  
Author(s):  
Maximilien Vanleene ◽  
Pierre-Emmanuel Mazeran ◽  
Marie-Christine Ho Ba Tho
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Bone Matrix ◽  
Femur Bone ◽  
Structure Assessment ◽  
Continuous Stiffness Measurement ◽  
Micrometer Scale

Investigations of bone mechanical properties are of major importance for bone pathology research, biomaterials, and development of in vivo bone characterization devices. Because of its complex multiscale structure, assessment of bone microstructure is an important step for understanding its mechanical behavior. In this study, we have investigated the strain rate influence on the mechanical properties of interstitial lamellae on two human femur bone samples. Nanoindentation tests were performed with the continuous stiffness measurement technique. Young's modulus and hardness were calculated using the Oliver and Pharr method. A statistical significant influence of strain rate on hardness was found (p < 0.05) showing a viscoplastic behavior of interstitial bone at the micrometer scale. This phenomenon may reflect the role of the organic component in the bone matrix mechanical behavior.

MODELISATION DE L'INFLUENCE DU TRAITEMENT THERMIQUE SUR LES PROPRIETES MECANIQUES DES ALLIAGES ALUMINIUM-CUIVRE (Al-Cu)

2015 ◽  
Vol 10 (2) ◽  
pp. 2753-2761
Author(s):  
Saad El Madani ◽  
S. ELHAMZI ◽  
A. IBNLFASSI ◽  
L. ZERROUK ◽  
O. BEN LENDA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Solidification Process ◽  
Traitement Thermique ◽  
Homogenization Process ◽  
Fundamental Reason ◽  
Segregation Phenomenon ◽  
Proprietes Mecaniques ◽  
Cooling Velocity ◽  
Copper Effect

In order to master and improve the quality and properties of the final products, the major industrial challenge lies in the possibility of controlling the morphology, size of microstructures that reside within the molded pieces, as well as their defects; this is the fundamental reason according to which we are more and more interested in mastering the growth and germination of such alloys, as well as the developing structures, at the time of solidification process. The modeling reveals as a valuable aid in the mastery of the formation of such heterogeneousness: segregation cells that are incompatible with industrial requirements.   The whole work focuses upon the modeling of the segregation phenomenon of the four hypoeutectic alloys, Al1%Cu, Al2%Cu, Al3%Cu et Al4%Cu, as well as the copper effect upon certain mechanical properties of aluminum. Usually, the microstructure and mechanical behavior of such alloys as Al-Cu are directly influenced by some parameters such as composition, cooling velocity and homogenization process.

scholarly journals Experimental and Numerical Evaluation of Mechanical Properties of 3D-Printed Stainless Steel 316L Lattice Structures

2021 ◽  
Author(s):  
M. Carraturo ◽  
G. Alaimo ◽  
S. Marconi ◽  
E. Negrello ◽  
E. Sgambitterra ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Mechanical Behavior ◽  
Numerical Simulations ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Lattice Structures ◽  
Stainless Steel 316L ◽  
Research Attention ◽  
Octet Truss

AbstractAdditive manufacturing (AM), and in particular selective laser melting (SLM) technology, allows to produce structural components made of lattice structures. These kinds of structures have received a lot of research attention over recent years due to their capacity to generate easy-to-manufacture and lightweight components with enhanced mechanical properties. Despite a large amount of work available in the literature, the prediction of the mechanical behavior of lattice structures is still an open issue for researchers. Numerical simulations can help to better understand the mechanical behavior of such a kind of structure without undergoing long and expensive experimental campaigns. In this work, we compare numerical and experimental results of a uniaxial tensile test for stainless steel 316L octet-truss lattice specimen. Numerical simulations are based on both the nominal as-designed geometry and the as-build geometry obtained through the analysis of µ-CT images. We find that the use of the as-build geometry is fundamental for an accurate prediction of the mechanical behavior of lattice structures.

scholarly journals Superior Alignment of Human iPSC-Osteoblasts Associated with Focal Adhesion Formation Stimulated by Oriented Collagen Scaffold

2021 ◽  
Vol 22 (12) ◽  
pp. 6232
Author(s):  
Ryosuke Ozasa ◽  
Aira Matsugaki ◽  
Tadaaki Matsuzaka ◽  
Takuya Ishimoto ◽  
Hui-Suk Yun ◽  
...  
Keyword(s):  
Bone Tissue ◽  
Structural Organization ◽  
Critical Role ◽  
Bone Matrix ◽  
Adhesion Formation ◽  
Focal Adhesions ◽  
Collagen Scaffold ◽  
Patient Specific ◽  
Specific Cell ◽  
Adhesion Behavior

Human-induced pluripotent stem cells (hiPSCs) can be applied in patient-specific cell therapy to regenerate lost tissue or organ function. Anisotropic control of the structural organization in the newly generated bone matrix is pivotal for functional reconstruction during bone tissue regeneration. Recently, we revealed that hiPSC-derived osteoblasts (hiPSC-Obs) exhibit preferential alignment and organize in highly ordered bone matrices along a bone-mimetic collagen scaffold, indicating their critical role in regulating the unidirectional cellular arrangement, as well as the structural organization of regenerated bone tissue. However, it remains unclear how hiPSCs exhibit the cell properties required for oriented tissue construction. The present study aimed to characterize the properties of hiPSCs-Obs and those of their focal adhesions (FAs), which mediate the structural relationship between cells and the matrix. Our in vitro anisotropic cell culture system revealed the superior adhesion behavior of hiPSC-Obs, which exhibited accelerated cell proliferation and better cell alignment along the collagen axis compared to normal human osteoblasts. Notably, the oriented collagen scaffold stimulated FA formation along the scaffold collagen orientation. This is the first report of the superior cell adhesion behavior of hiPSC-Obs associated with the promotion of FA assembly along an anisotropic scaffold. These findings suggest a promising role for hiPSCs in enabling anisotropic bone microstructural regeneration.

scholarly journals Development of Biopolymeric Hybrid Scaffold-Based on AAc/GO/nHAp/TiO2 Nanocomposite for Bone Tissue Engineering: In-Vitro Analysis

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1319
Author(s):  
Muhammad Umar Aslam Khan ◽  
Wafa Shamsan Al-Arjan ◽  
Mona Saad Binkadem ◽  
Hassan Mehboob ◽  
Adnan Haider ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Guar Gum ◽  
Porous Scaffolds ◽  
Vitro Assay ◽  
Vitro Analysis ◽  
Nanocomposite Scaffolds

Bone tissue engineering is an advanced field for treatment of fractured bones to restore/regulate biological functions. Biopolymeric/bioceramic-based hybrid nanocomposite scaffolds are potential biomaterials for bone tissue because of biodegradable and biocompatible characteristics. We report synthesis of nanocomposite based on acrylic acid (AAc)/guar gum (GG), nano-hydroxyapatite (HAp NPs), titanium nanoparticles (TiO2 NPs), and optimum graphene oxide (GO) amount via free radical polymerization method. Porous scaffolds were fabricated through freeze-drying technique and coated with silver sulphadiazine. Different techniques were used to investigate functional group, crystal structural properties, morphology/elemental properties, porosity, and mechanical properties of fabricated scaffolds. Results show that increasing amount of TiO2 in combination with optimized GO has improved physicochemical and microstructural properties, mechanical properties (compressive strength (2.96 to 13.31 MPa) and Young’s modulus (39.56 to 300.81 MPa)), and porous properties (pore size (256.11 to 107.42 μm) and porosity (79.97 to 44.32%)). After 150 min, silver sulfadiazine release was found to be ~94.1%. In vitro assay of scaffolds also exhibited promising results against mouse pre-osteoblast (MC3T3-E1) cell lines. Hence, these fabricated scaffolds would be potential biomaterials for bone tissue engineering in biomedical engineering.

scholarly journals Phosphoproteins of chicken bone matrix. Proof of synthesis in bone tissue.

1984 ◽  
Vol 259 (1) ◽  
pp. 290-293
Author(s):  
M J Glimcher ◽  
D Kossiva ◽  
D Brickley-Parsons
Keyword(s):  
Bone Tissue ◽  
Bone Matrix ◽  
Chicken Bone

scholarly journals Antigen-driven EGR2 expression is required for exhausted CD8+ T cell stability and maintenance

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mayura V. Wagle ◽  
Stephin J. Vervoort ◽  
Madison J. Kelly ◽  
Willem Van Der Byl ◽  
Timothy J. Peters ◽  
...  
Keyword(s):  
T Cells ◽  
Transcription Factor ◽  
Cd8 T Cell ◽  
Chronic Stimulation ◽  
Epigenetic State ◽  
Multiple Differentiation ◽  
Cell Stability ◽  
Substantial Interest ◽  
Transcriptional State ◽  
Stimulation Of

AbstractChronic stimulation of CD8+ T cells triggers exhaustion, a distinct differentiation state with diminished effector function. Exhausted cells exist in multiple differentiation states, from stem-like progenitors that are the key mediators of the response to checkpoint blockade, through to terminally exhausted cells. Due to its clinical relevance, there is substantial interest in defining the pathways that control differentiation and maintenance of these subsets. Here, we show that chronic antigen induces the anergy-associated transcription factor EGR2 selectively within progenitor exhausted cells in both chronic LCMV and tumours. EGR2 enables terminal exhaustion and stabilizes the exhausted transcriptional state by both direct EGR2-dependent control of key exhaustion-associated genes, and indirect maintenance of the exhausted epigenetic state. We show that EGR2 is a regulator of exhaustion that epigenetically and transcriptionally maintains the differentiation competency of progenitor exhausted cells.

scholarly journals A novel gelatin/chitooligosaccharide/demineralized bone matrix composite scaffold and periosteum-derived mesenchymal stem cells for bone tissue engineering

2021 ◽  
Vol 25 (1) ◽  
Author(s):  
Thakoon Thitiset ◽  
Siriporn Damrongsakkul ◽  
Supansa Yodmuang ◽  
Wilairat Leeanansaksiri ◽  
Jirun Apinun ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Bone Formation ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Demineralized Bone Matrix ◽  
Bone Matrix ◽  
Alp Activity

Abstract Background A novel biodegradable scaffold including gelatin (G), chitooligosaccharide (COS), and demineralized bone matrix (DBM) could play a significant part in bone tissue engineering. The present study aimed to investigate the biological characteristics of composite scaffolds in combination of G, COS, and DBM for in vitro cell culture and in vivo animal bioassays. Methods Three-dimensional scaffolds from the mixture of G, COS, and DBM were fabricated into 3 groups, namely, G, GC, and GCD using a lyophilization technique. The scaffolds were cultured with mesenchymal stem cells (MSCs) for 4 weeks to determine biological responses such as cell attachment and cell proliferation, alkaline phosphatase (ALP) activity, calcium deposition, cell morphology, and cell surface elemental composition. For the in vivo bioassay, G, GC, and GCD, acellular scaffolds were implanted subcutaneously in 8-week-old male Wistar rats for 4 weeks and 8 weeks. The explants were assessed for new bone formation using hematoxylin and eosin (H&E) staining and von Kossa staining. Results The MSCs could attach and proliferate on all three groups of scaffolds. Interestingly, the ALP activity of MSCs reached the greatest value on day 7 after cultured on the scaffolds, whereas the calcium assay displayed the highest level of calcium in MSCs on day 28. Furthermore, weight percentages of calcium and phosphorus on the surface of MSCs after cultivation on the GCD scaffolds increased when compared to those on other scaffolds. The scanning electron microscopy images showed that MSCs attached and proliferated on the scaffold surface thoroughly over the cultivation time. Mineral crystal aggregation was evident in GC and greatly in GCD scaffolds. H&E staining illustrated that G, GC, and GCD scaffolds displayed osteoid after 4 weeks of implantation and von Kossa staining confirmed the mineralization at 8 weeks in G, GC, and GCD scaffolds. Conclusion The MSCs cultured in GCD scaffolds revealed greater osteogenic differentiation than those cultured in G and GC scaffolds. Additionally, the G, GC, and GCD scaffolds could promote in vivo ectopic bone formation in rat model. The GCD scaffolds exhibited maximum osteoinductive capability compared with others and may be potentially used for bone regeneration.

scholarly journals Decoupling of Mechanical and Transport Properties in Organogels via Solvent Variation

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 61
Author(s):  
Kenneth P. Mineart ◽  
Cameron Hong ◽  
Lucas A. Rankin
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Transdermal Drug Delivery ◽  
Triblock Copolymer ◽  
Polymer Concentration ◽  
Mineral Oil ◽  
Solute Diffusion ◽  
Oil Viscosity ◽  
Chain Entanglement ◽  
Mineral Oils

Organogels have recently been considered as materials for transdermal drug delivery media, wherein their transport and mechanical properties are among the most important considerations. Transport through organogels has only recently been investigated and findings highlight an inextricable link between gels’ transport and mechanical properties based upon the formulated polymer concentration. Here, organogels composed of styrenic triblock copolymer and different aliphatic mineral oils, each with a unique dynamic viscosity, are characterized in terms of their quasi-static uniaxial mechanical behavior and the internal diffusion of two unique solute penetrants. Mechanical testing results indicate that variation of mineral oil viscosity does not affect gel mechanical behavior. This likely stems from negligible changes in the interactions between mineral oils and the block copolymer, which leads to consistent crosslinked network structure and chain entanglement (at a fixed polymer concentration). Conversely, results from diffusion experiments highlight that two penetrants—oleic acid (OA) and aggregated aerosol-OT (AOT)—diffuse through gels at a rate inversely proportional to mineral oil viscosity. The inverse dependence is theoretically supported by the hydrodynamic model of solute diffusion through gels. Collectively, our results show that organogel solvent variation can be used as a design parameter to tailor solute transport through gels while maintaining fixed mechanical properties.

scholarly journals Understanding the Barrier and Mechanical Behavior of Different Nanofillers in Chitosan Films for Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 721 ◽  
Author(s):  
João Pires ◽  
Camila Damásio de Paula ◽  
Victor Gomes Lauriano Souza ◽  
Ana Luísa Fernando ◽  
Isabel Coelhoso
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Food Packaging ◽  
Scientific Research ◽  
Barrier Properties ◽  
Plastic Pollution ◽  
Functional Attributes ◽  
Chitosan Films ◽  
Commercial Applications ◽  
Innovative Techniques

The continuous petroleum-based plastics manufacturing generates disposal issues, spreading the problem of plastic pollution and its rise in the environment. Recently, innovative techniques and scientific research promoted biopolymers as the primary alternative for traditional plastics, raising and expanding global bioplastic production. Due to its unmatched biological and functional attributes, chitosan (Ch) has been substantially explored and employed as a biopolymeric matrix. Nevertheless, the hydrophilicity and the weak mechanical properties associated with this biopolymer represent a significant intrinsic restriction to its implementation into some commercial applications, namely, in food packaging industries. Distinct methodologies have been utilized to upgrade the mechanical and barrier properties of Ch, such as using organic or inorganic nanofillers, crosslinkers, or blends with other polymers. This review intends to analyze the most recent works that combine the action of different nanoparticle types with Ch films to reinforce their mechanical and barrier properties.

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