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  Subjects -> BIOLOGY (Total: 3134 journals)
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BIOTECHNOLOGY (236 journals)                  1 2 | Last

Showing 1 - 200 of 237 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
Advanced Biomedical Research     Open Access  
Advances in Bioscience and Biotechnology     Open Access   (Followers: 14)
Advances in Genetic Engineering & Biotechnology     Hybrid Journal   (Followers: 8)
African Journal of Biotechnology     Open Access   (Followers: 6)
Algal Research     Partially Free   (Followers: 10)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 65)
American Journal of Bioinformatics Research     Open Access   (Followers: 7)
American Journal of Polymer Science     Open Access   (Followers: 31)
Anadolu University Journal of Science and Technology : C Life Sciences and Biotechnology     Open Access  
Animal Biotechnology     Hybrid Journal   (Followers: 8)
Annales des Sciences Agronomiques     Full-text available via subscription  
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 43)
Applied Bioenergy     Open Access  
Applied Biosafety     Hybrid Journal  
Applied Food Biotechnology     Open Access   (Followers: 3)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 63)
Applied Mycology and Biotechnology     Full-text available via subscription   (Followers: 4)
Arthroplasty Today     Open Access   (Followers: 1)
Artificial Cells, Nanomedicine and Biotechnology     Hybrid Journal   (Followers: 1)
Asia Pacific Biotech News     Hybrid Journal   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Pacific Journal of Tropical Biomedicine     Open Access   (Followers: 2)
Australasian Biotechnology     Full-text available via subscription   (Followers: 1)
Banat's Journal of Biotechnology     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 5)
Bio-Algorithms and Med-Systems     Hybrid Journal   (Followers: 2)
Bio-Research     Full-text available via subscription   (Followers: 2)
Bioactive Materials     Open Access   (Followers: 1)
Biocatalysis and Agricultural Biotechnology     Hybrid Journal   (Followers: 4)
Biocybernetics and Biological Engineering     Full-text available via subscription   (Followers: 5)
Bioethics UPdate     Hybrid Journal  
Biofuels     Hybrid Journal   (Followers: 11)
Biofuels Engineering     Open Access   (Followers: 1)
Biological & Pharmaceutical Bulletin     Full-text available via subscription   (Followers: 4)
Biological Cybernetics     Hybrid Journal   (Followers: 10)
Biomarkers and Genomic Medicine     Open Access   (Followers: 3)
Biomarkers in Drug Development     Partially Free   (Followers: 1)
Biomaterials Research     Open Access   (Followers: 4)
BioMed Research International     Open Access   (Followers: 4)
Biomédica     Open Access  
Biomedical and Biotechnology Research Journal     Open Access  
Biomedical Engineering Research     Open Access   (Followers: 6)
Biomedical glasses     Open Access  
Biomedical Reports     Full-text available via subscription  
BioMedicine     Open Access  
Biomedika     Open Access  
Bioprinting     Hybrid Journal   (Followers: 1)
Bioresource Technology Reports     Hybrid Journal   (Followers: 1)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 21)
Biosimilars     Open Access   (Followers: 1)
Biosurface and Biotribology     Open Access  
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
BioTechniques : The International Journal of Life Science Methods     Full-text available via subscription   (Followers: 28)
Biotechnologia Acta     Open Access   (Followers: 1)
Biotechnologie, Agronomie, Société et Environnement     Open Access   (Followers: 2)
Biotechnology     Open Access   (Followers: 5)
Biotechnology & Biotechnological Equipment     Open Access   (Followers: 4)
Biotechnology Advances     Hybrid Journal   (Followers: 33)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 157)
Biotechnology and Bioprocess Engineering     Hybrid Journal   (Followers: 5)
Biotechnology and Genetic Engineering Reviews     Hybrid Journal   (Followers: 13)
Biotechnology and Health Sciences     Open Access   (Followers: 1)
Biotechnology and Molecular Biology Reviews     Open Access   (Followers: 1)
Biotechnology Annual Review     Full-text available via subscription   (Followers: 5)
Biotechnology for Biofuels     Open Access   (Followers: 10)
Biotechnology Frontier     Open Access   (Followers: 2)
Biotechnology Journal     Hybrid Journal   (Followers: 16)
Biotechnology Law Report     Hybrid Journal   (Followers: 4)
Biotechnology Letters     Hybrid Journal   (Followers: 34)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Biotechnology Reports     Open Access  
Biotechnology Research International     Open Access   (Followers: 1)
Biotechnology Techniques     Hybrid Journal   (Followers: 10)
Biotecnología Aplicada     Open Access  
Bioteknologi (Biotechnological Studies)     Open Access  
Biotribology     Hybrid Journal   (Followers: 1)
BMC Biotechnology     Open Access   (Followers: 16)
Cell Biology and Development     Open Access  
Chinese Journal of Agricultural Biotechnology     Full-text available via subscription   (Followers: 4)
Communications in Mathematical Biology and Neuroscience     Open Access  
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computer Methods and Programs in Biomedicine     Hybrid Journal   (Followers: 8)
Contributions to Tobacco Research     Open Access   (Followers: 2)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biotechnology     Hybrid Journal   (Followers: 20)
Crop Breeding and Applied Biotechnology     Open Access   (Followers: 3)
Current Bionanotechnology     Hybrid Journal  
Current Biotechnology     Hybrid Journal   (Followers: 4)
Current Opinion in Biomedical Engineering     Hybrid Journal   (Followers: 1)
Current Opinion in Biotechnology     Hybrid Journal   (Followers: 56)
Current Pharmaceutical Biotechnology     Hybrid Journal   (Followers: 9)
Current Research in Bioinformatics     Open Access   (Followers: 12)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Current trends in Biotechnology and Pharmacy     Open Access   (Followers: 8)
EBioMedicine     Open Access  
Electronic Journal of Biotechnology     Open Access  
Entomologia Generalis     Full-text available via subscription  
Environmental Science : Processes & Impacts     Full-text available via subscription   (Followers: 4)
Experimental Biology and Medicine     Hybrid Journal   (Followers: 3)
Folia Medica Indonesiana     Open Access  
Food Bioscience     Hybrid Journal  
Food Biotechnology     Hybrid Journal   (Followers: 9)
Food Science and Biotechnology     Hybrid Journal   (Followers: 8)
Frontiers in Bioengineering and Biotechnology     Open Access   (Followers: 6)
Frontiers in Systems Biology     Open Access   (Followers: 2)
Fungal Biology and Biotechnology     Open Access   (Followers: 2)
GM Crops and Food: Biotechnology in Agriculture and the Food Chain     Full-text available via subscription   (Followers: 1)
GSTF Journal of BioSciences     Open Access  
HAYATI Journal of Biosciences     Open Access  
Horticulture, Environment, and Biotechnology     Hybrid Journal   (Followers: 11)
IEEE Transactions on Molecular, Biological and Multi-Scale Communications     Hybrid Journal   (Followers: 1)
IET Nanobiotechnology     Hybrid Journal   (Followers: 2)
IIOAB Letters     Open Access  
IN VIVO     Full-text available via subscription   (Followers: 4)
Indian Journal of Biotechnology (IJBT)     Open Access   (Followers: 2)
Indonesia Journal of Biomedical Science     Open Access   (Followers: 2)
Indonesian Journal of Biotechnology     Open Access   (Followers: 1)
Industrial Biotechnology     Hybrid Journal   (Followers: 18)
International Biomechanics     Open Access  
International Journal of Bioinformatics Research and Applications     Hybrid Journal   (Followers: 13)
International Journal of Biomechatronics and Biomedical Robotics     Hybrid Journal   (Followers: 4)
International Journal of Biomedical Research     Open Access   (Followers: 2)
International Journal of Biotechnology     Hybrid Journal   (Followers: 5)
International Journal of Biotechnology and Molecular Biology Research     Open Access   (Followers: 2)
International Journal of Biotechnology for Wellness Industries     Partially Free   (Followers: 1)
International Journal of Environment, Agriculture and Biotechnology     Open Access   (Followers: 5)
International Journal of Functional Informatics and Personalised Medicine     Hybrid Journal   (Followers: 4)
International Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
International Journal of Nanotechnology and Molecular Computation     Full-text available via subscription   (Followers: 3)
International Journal of Radiation Biology     Hybrid Journal   (Followers: 4)
Iranian Journal of Biotechnology     Open Access  
ISABB Journal of Biotechnology and Bioinformatics     Open Access  
Italian Journal of Food Science     Open Access   (Followers: 1)
Journal of Biometrics & Biostatistics     Open Access   (Followers: 3)
Journal of Bioterrorism & Biodefense     Open Access   (Followers: 6)
Journal of Petroleum & Environmental Biotechnology     Open Access   (Followers: 1)
Journal of Advanced Therapies and Medical Innovation Sciences     Open Access  
Journal of Advances in Biotechnology     Open Access   (Followers: 5)
Journal Of Agrobiotechnology     Open Access  
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 7)
Journal of Animal Science and Biotechnology     Open Access   (Followers: 4)
Journal of Applied Biomedicine     Open Access   (Followers: 2)
Journal of Applied Biotechnology     Open Access   (Followers: 2)
Journal of Applied Biotechnology Reports     Open Access   (Followers: 2)
Journal of Applied Mathematics & Bioinformatics     Open Access   (Followers: 5)
Journal of Biologically Active Products from Nature     Hybrid Journal   (Followers: 1)
Journal of Biomaterials and Nanobiotechnology     Open Access   (Followers: 6)
Journal of Biomedical Photonics & Engineering     Open Access  
Journal of Biomedical Practitioners     Open Access  
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Bioprocessing & Biotechniques     Open Access  
Journal of Biosecurity, Biosafety and Biodefense Law     Hybrid Journal   (Followers: 3)
Journal of Biotechnology     Hybrid Journal   (Followers: 68)
Journal of Biotechnology and Strategic Health Research     Open Access  
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 9)
Journal of Chitin and Chitosan Science     Full-text available via subscription  
Journal of Colloid Science and Biotechnology     Full-text available via subscription  
Journal of Commercial Biotechnology     Full-text available via subscription   (Followers: 6)
Journal of Crop Science and Biotechnology     Hybrid Journal   (Followers: 3)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 2)
Journal of Experimental Biology     Full-text available via subscription   (Followers: 24)
Journal of Genetic Engineering and Biotechnology     Open Access   (Followers: 5)
Journal of Ginseng Research     Open Access  
Journal of Industrial Microbiology and Biotechnology     Hybrid Journal   (Followers: 16)
Journal of Integrative Bioinformatics     Open Access  
Journal of International Biotechnology Law     Hybrid Journal   (Followers: 3)
Journal of Medical Imaging and Health Informatics     Full-text available via subscription  
Journal of Molecular Biology and Biotechnology     Open Access  
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 11)
Journal of Nano Education     Full-text available via subscription  
Journal of Nanobiotechnology     Open Access   (Followers: 4)
Journal of Nanofluids     Full-text available via subscription   (Followers: 1)
Journal of Organic and Biomolecular Simulations     Open Access  
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)
Journal of Science and Applications : Biomedicine     Open Access  
Journal of the Mechanical Behavior of Biomedical Materials     Hybrid Journal   (Followers: 11)
Journal of Trace Elements in Medicine and Biology     Hybrid Journal   (Followers: 1)
Journal of Tropical Microbiology and Biotechnology     Full-text available via subscription  
Journal of Yeast and Fungal Research     Open Access   (Followers: 1)
Marine Biotechnology     Hybrid Journal   (Followers: 4)
Messenger     Full-text available via subscription  
Metabolic Engineering Communications     Open Access   (Followers: 4)
Metalloproteinases In Medicine     Open Access  
Microalgae Biotechnology     Open Access   (Followers: 2)
Microbial Biotechnology     Open Access   (Followers: 9)
MicroMedicine     Open Access   (Followers: 3)
Molecular and Cellular Biomedical Sciences     Open Access  
Molecular Biotechnology     Hybrid Journal   (Followers: 13)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 3)
Nanobiomedicine     Open Access  
Nanobiotechnology     Hybrid Journal   (Followers: 2)
Nanomaterials and Nanotechnology     Open Access  
Nanomaterials and Tissue Regeneration     Open Access  
Nanomedicine and Nanobiology     Full-text available via subscription  
Nanomedicine Research Journal     Open Access  
Nanotechnology Reviews     Hybrid Journal   (Followers: 5)
Nature Biotechnology     Full-text available via subscription   (Followers: 535)

        1 2 | Last

Journal Cover Journal of the Mechanical Behavior of Biomedical Materials
  [SJR: 1.068]   [H-I: 41]   [11 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1751-6161
   Published by Elsevier Homepage  [3162 journals]
  • Dynamic rheological comparison of silicones for podiatry applications
    • Authors: Ana-María Díaz-Díaz; Bárbara Sánchez-Silva; Javier Tarrío-Saavedra; Jorge López-Beceiro; Julia Janeiro-Arocas; Carlos Gracia-Fernández; Ramón Artiaga
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Ana-María Díaz-Díaz, Bárbara Sánchez-Silva, Javier Tarrío-Saavedra, Jorge López-Beceiro, Julia Janeiro-Arocas, Carlos Gracia-Fernández, Ramón Artiaga
      Purpose This work shows an effective methodology to evaluate the dynamic viscoelastic behavior of silicones for application in podiatry. The aim is to characterize, compare their viscoelastic properties according to the dynamic stresses they can be presumably subjected when used in podiatry orthotic applications. These results provide a deeper insight which extends the previous creep-recovery results to the world of dynamic stresses developed in physical activity. In this context, it shoulod be taken into account that an orthoses can subjected to a set of static and dynamic shear and compressive forces. Methods Two different podiatric silicones, Blanda-blanda and Master, from Herbitas, are characterized by dynamic rheological methods. Three kinds of rheological tests are considered: shear stress sweep, compression frequency sweep and shear frequency sweep, all the three with simultaneous control of the static force at three different levels. The static force represents a static load like that produced by the weight of a human body on a shoe insole. In a practical sense, dynamic stresses are related to physical activity and are needed to evaluate the frequency effect on the viscoelastic behavior of the material. It is considered that the dynamic stresses can be applied in compression and shear since, in practice, the way the stresses are applied in real life depends on the orthoses geometry and its exact location with respect to the foot and shoe. The effects of static and dynamic loads are individualized and compared to each other through the relations between the elastic constants for isotropic materials. Conclusions The overall proposed experimental methodology can provide very insightful information for better selection of materials in podiatry applications. This study focuses on the rheological characterization to choose the right silicone for each podiatric application, taking into account the dynamic viscoelastic requirements associated to the physical activity of user. Accordingly, one soft and one hard silicones of common use in podiatry were tested. Each of the two silicones exhibit not only different moduli values, but also, a different kind of dependence of the dynamic moduli with respect to the static load. In the case of the soft sample a linear trend is observed but in the case of of the hard one the dependence is of the power law type. Moreover, these samples exhibit very different Poisson's coefficient values for compression stresses lower than 20 kPa, and almost the same values for stresses above 40 kPa. That different dependence of the Poisson's ratio on the static load should also be taken into account for material selection in customized podiatry applications, where static and dynamic loads are strongly dependent on the individual weight and activity.

      PubDate: 2018-06-01T10:21:26Z
      DOI: 10.1016/j.jmbbm.2018.05.033
      Issue No: Vol. 85 (2018)
       
  • In situ reactive multi-material Ti6Al4V-calcium phosphate-nitride coatings
           for bio-tribological applications
    • Authors: Himanshu Sahasrabudhe; Amit Bandyopadhyay
      Pages: 1 - 11
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Himanshu Sahasrabudhe, Amit Bandyopadhyay
      To reduce the wear related damage of medical grade Ti-6Al-4V alloy, laser engineered net shaping (LENS™) based in situ reactive multi-material additive manufacturing was employed to process a mixed coating of Ti-6Al-4V powder and calcium phosphate (CaP) in an oxygen free, nitrogen-argon environment. The resultant coatings were composite materials of titanium nitrides and calcium titanate in an α-Ti matrix. Hardness was increased by up to ~148% to 868 ± 9 HV as compared to the untreated Ti-6Al-4V substrate. Similarly, when tribological properties were evaluated in deionized (DI) water medium against alumina counter material, the wear damage was reduced by ~91% as compared to the untreated Ti-6Al-4V substrate. Furthermore, the untreated Ti-6Al-4V substrate released Ti ions of ~12.45 ppm concentration during wear whereas the Ti6Al4V-5%CaP coating processed in an argon-nitrogen environment released ions of ~3.17 ppm concentration under similar testing conditions. The overall coefficient of friction was also found to decrease due to the addition of CaP and processing the Ti6Al4V-CaP mixture in an argon-nitrogen environment. Our results indicate that this reactive multi-material additive manufacturing of metal-ceramic composites is an effective way of enhancing the tribological performance of metallic materials.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.020
      Issue No: Vol. 85 (2018)
       
  • Evolution of callus tissue behavior during stable distraction osteogenesis
    • Authors: Nicholaus Meyers; Julian Schülke; Anita Ignatius; Lutz Claes
      Pages: 12 - 19
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Nicholaus Meyers, Julian Schülke, Anita Ignatius, Lutz Claes
      Multiple studies have sought to characterize the mechanical behavior of callus tissue in vivo during distraction osteogenesis. The aims of such studies are to understand the mechanobiology of distraction and elucidate the complex viscoelasticity and evolution of the tissue. The former objective has direct clinical relevance to surgical technique and process control while the latter is necessary for the calibration and validation of the predictive healing models. Such models seek to reduce the researcher's dependence on animal studies and prospectively allow improved surgical planning. To date, no study has been capable of controlling the mechanical conditions sufficiently enough to decouple the distraction process from the secondary mechanical stimulation associated with the finite stiffness of the fixation constructs employed. It is the goal of this work to understand the mechanobiology of pure distraction as well as characterize viscoelastic tissue behavior under precisely defined mechanical conditions. This is achieved using a novel lateral distraction model. The structural integrity of the bone is maintained, allowing the collection of force relaxation data due to a stepwise distraction process without the superimposed influence of secondary mechanical stimulation. The average instantaneous modulus increases from approximately 2 kPa to approximately 1100 kPa while the equilibrium modulus increases from approximately 0 kPa to 200 kPa over the distraction period.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.017
      Issue No: Vol. 85 (2018)
       
  • Influence of post coating heat treatment on microstructural, mechanical
           and electrochemical corrosion behaviour of vacuum plasma sprayed
           reinforced hydroxyapatite coatings
    • Authors: Amardeep Singh; Gurbhinder Singh; Vikas Chawla
      Pages: 20 - 36
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Amardeep Singh, Gurbhinder Singh, Vikas Chawla
      In the present study, reinforced hydroxyapatite (HA) coatings (HA + 10 wt% Al2O3 and HA + 10 wt% ZrO2) were deposited on SS-316 L substrate with an intermediate layer (bond coat) of zirconia by vacuum plasma spray technique. The so-formed reinforced HA coatings were heat treated at 700 °C for 1 h. The influence of post coating heat treatment on phase composition, microstructure, mechanical and electrochemical corrosion properties were investigated. As-sprayed and heat treated coatings were characterized by x-ray diffraction, scanning electron microscope, surface roughness, porosity and crystallinity. Results showed that after post coating heat treatment, the structural integrity of HA has been completely re-established. Moreover, significant drop in porosity has been observed due to the sintering effect produced by heat treatment. Considerable improvement in nanohardness and shear strength was witnessed; however, the nanohardness of top layer was decreased after annealing due to the weak bonding of partially melted and un-melted particles with fully melted splats caused by diffusion process. As-sprayed coatings exhibited higher wear resistance compared to heat treated coatings. Nevertheless, post coating heat treatment effectively enhanced the corrosion resistance of coatings, since, the heat treatment lead to densification of coatings microstructure which further reduces the active sites for dissolution.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.030
      Issue No: Vol. 85 (2018)
       
  • Integrating MRI-based geometry, composition and fiber architecture in a
           finite element model of the human intervertebral disc
    • Authors: Marc A. Stadelmann; Ghislain Maquer; Benjamin Voumard; Aaron Grant; David B. Hackney; Peter Vermathen; Ron N. Alkalay; Philippe K. Zysset
      Pages: 37 - 42
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Marc A. Stadelmann, Ghislain Maquer, Benjamin Voumard, Aaron Grant, David B. Hackney, Peter Vermathen, Ron N. Alkalay, Philippe K. Zysset
      Intervertebral disc degeneration is a common disease that is often related to impaired mechanical function, herniations and chronic back pain. The degenerative process induces alterations of the disc's shape, composition and structure that can be visualized in vivo using magnetic resonance imaging (MRI). Numerical tools such as finite element analysis (FEA) have the potential to relate MRI-based information to the altered mechanical behavior of the disc. However, in terms of geometry, composition and fiber architecture, current FE models rely on observations made on healthy discs and might therefore not be well suited to study the degeneration process. To address the issue, we propose a new, more realistic FE methodology based on diffusion tensor imaging (DTI). For this study, a human disc joint was imaged in a high-field MR scanner with proton-density weighted (PD) and DTI sequences. The PD image was segmented and an anatomy-specific mesh was generated. Assuming accordance between local principal diffusion direction and local mean collagen fiber alignment, corresponding fiber angles were assigned to each element. Those element-wise fiber directions and PD intensities allowed the homogenized model to smoothly account for composition and fibrous structure of the disc. The disc's in vitro mechanical behavior was quantified under tension, compression, flexion, extension, lateral bending and rotation. The six resulting load-displacement curves could be replicated by the FE model, which supports our approach as a first proof of concept towards patient-specific disc modeling.
      Graphical abstract image Highlights fx1

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.005
      Issue No: Vol. 85 (2018)
       
  • Resistance from agar medium impacts the helical growth of Arabidopsis
           primary roots
    • Authors: Jie Yan; Bochu Wang; Yong Zhou; Shilei Hao
      Pages: 43 - 50
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Jie Yan, Bochu Wang, Yong Zhou, Shilei Hao
      Agar is widely used in studies of root growth since it can be mixed at different concentrations to impact mechanical impedance. At high concentrations (1.2–1.5%), growth of Arabidopsis roots has been found to be wavy, but little research has explored this behavior based on a quantitative understanding of mechanical behavior. To this end, agar media with concentration ranging from 0.5% to 1.2% were prepared to produce gradient resistance during root penetration, and Young's moduli and penetrometer resistance were tested. Arabidopsis roots were then cultivated in these agar media with gradient stiffness. The result showed that Young's modulus increased linearly with the increase of concentration of agar media. For Arabidopsis primary roots, it was preferred to develop a helical pattern in agar media with concentration from 0.5% to 1.0%. As stiffness of agar increased, the percentage of helical roots and helix diameters in each agar medium declined; root lengths and auxin distributions showed variety. We demonstrate that the size of helical deformation decreases with agar stiffness as expected by theoretical analysis based on a combination of growth-induced mechanical buckling. In conclusion, the resistance from agar media impacts the properties of root helix, and helical roots growth is driven by growth force. Growth force and external mechanical forces contribute to root phenotypes in Arabidopsis.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.018
      Issue No: Vol. 85 (2018)
       
  • Stiffness and energy dissipation across the superficial and deeper third
           metacarpal subchondral bone in Thoroughbred racehorses under high-rate
           compression
    • Authors: Fatemeh Malekipour; Chris R. Whitton; Peter Vee-Sin Lee
      Pages: 51 - 56
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Fatemeh Malekipour, Chris R. Whitton, Peter Vee-Sin Lee
      Subchondral bone injury due to high magnitude and repetition of compressive loading is common in humans and athletic animals such as Thoroughbred racehorses. Repeated loading of the joint surface may alter the subchondral bone microstructure and initiate microdamage in the bone adjacent to the articular cartilage. Understanding the relationship between microdamage, microstructure and mechanical properties of the subchondral bone adjacent to the articular cartilage is, therefore, essential in understanding the mechanism of subchondral bone injury. In this study, we used high-resolution µCT scanning, a digital image-based strain measurement technique, and mechanical testing to evaluate the three-dimensional pre-existing microcracks, bone volume fraction (BVF) and bone mineral density (BMD), and mechanical properties (stiffness and hysteresis) of subchondral bone (n = 10) from the distopalmar aspect of the third metacarpal (MC3) condyles of Thoroughbred racehorses under high-rate compression. We specifically compared the properties of two regions of interest in the subchondral bone: the 2 mm superficial subchondral bone (SSB) and its underlying 2 mm deep subchondral bone (DSB). The DSB region was 3.0 ± 1.2 times stiffer than its overlying SSB, yet it dissipated much less energy compared to the SSB. There was no correlation between structural properties (BVF and BMD) and mechanical properties (stiffness and energy loss), except for BMD and energy loss in SSB. The lower stiffness of the most superficial subchondral bone in the distal metacarpal condyles may protect the overlying cartilage and the underlying subchondral bone from damage under the high-rate compression experienced during galloping. However, repeated high-rate loading over time has the potential to inhibit bone turnover and induce bone fatigue, consistent with the high prevalence of subchondral bone injury and fractures in athletic humans and racehorses.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.031
      Issue No: Vol. 85 (2018)
       
  • Scaling effect on the fracture toughness of bone materials using MMTS
           criterion
    • Authors: Javad Akbardoost; Reza Amirafshari; Omid Mohsenzade; Filippo Berto
      Pages: 72 - 79
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Javad Akbardoost, Reza Amirafshari, Omid Mohsenzade, Filippo Berto
      The aim of this study is to present a stress based approach for investigating the effect of specimen size on the fracture toughness of bone materials. The proposed approach is a modified form of the classical fracture criterion called maximum tangential stress (MTS). The mechanical properties of bone are different in longitudinal and transverse directions and hence the tangential stress component in the proposed approach should be determined in the orthotropic media. Since only the singular terms of series expansions were obtained in the previous studies, the tangential stress is measured from finite element analysis. In this study, the critical distance is also assumed to be size dependent and a semi-empirical formulation is used for describing the size dependency of the critical distance. By comparing the results predicted by the proposed approach and those reported in the previous studies, it is shown that the proposed approach can predict the fracture resistance of cracked bone by taking into account the effect of specimen size.

      PubDate: 2018-06-01T10:21:26Z
      DOI: 10.1016/j.jmbbm.2018.05.028
      Issue No: Vol. 85 (2018)
       
  • A transverse isotropic constitutive model for the aortic valve tissue
           incorporating rate-dependency and fibre dispersion: Application to biaxial
           deformation
    • Authors: Afshin Anssari-Benam; Yuan-Tsan Tseng; Andrea Bucchi
      Pages: 80 - 93
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Afshin Anssari-Benam, Yuan-Tsan Tseng, Andrea Bucchi
      This paper presents a continuum-based transverse isotropic model incorporating rate-dependency and fibre dispersion, applied to the planar biaxial deformation of aortic valve (AV) specimens under various stretch rates. The rate dependency of the mechanical behaviour of the AV tissue under biaxial deformation, the (pseudo-) invariants of the right Cauchy-Green deformation-rate tensor C ̇ associated with fibre dispersion, and a new fibre orientation density function motivated by fibre kinematics are presented for the first time. It is shown that the model captures the experimentally observed deformation of the specimens, and characterises a shear-thinning behaviour associated with the dissipative (viscous) kinematics of the matrix and the fibres. The application of the model for predicting the deformation behaviour of the AV under physiological rates is illustrated and an example of the predicted σ − λ curves is presented. While the development of the model was principally motivated by the AV biomechanics requisites, the comprehensive theoretical approach employed in the study renders the model suitable for application to other fibrous soft tissues that possess similar rate-dependent and structural attributes.

      PubDate: 2018-06-01T10:21:26Z
      DOI: 10.1016/j.jmbbm.2018.05.035
      Issue No: Vol. 85 (2018)
       
  • Development of biomimetic in vitro fatigue assessment for UHMWPE implant
           materials
    • Authors: Ronja Scholz; Marina Knyazeva; Dario Porchetta; Nils Wegner; Fedor Senatov; Alexey Salimon; Sergey Kaloshkin; Frank Walther
      Pages: 94 - 101
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Ronja Scholz, Marina Knyazeva, Dario Porchetta, Nils Wegner, Fedor Senatov, Alexey Salimon, Sergey Kaloshkin, Frank Walther
      An important research goal in the field of biomaterials lies in the progressive amendment of in vivo tests with suitable in vitro experiments. Such approaches are gaining more significance nowadays because of an increasing demand on life sciences and the ethical issues bound to the sacrifice of animals for the sake of scientific research. Another advantage of transferring the experiments to the in vitro field is the possibility of accurately control the boundary conditions and experimental parameters in order to reduce the need of validation tests involving animals. With the aim to reduce the amount of needed in vivo studies for this cause, a short-time in vitro test procedure using instrumented load increase tests with superimposed environmental loading has been developed at TUD to assess the mechanical long-term durability of ultra-high molecular weight polyethylene (UHMWPE) under fatigue loading in a biological environment.

      PubDate: 2018-06-04T08:10:11Z
      DOI: 10.1016/j.jmbbm.2018.05.034
      Issue No: Vol. 85 (2018)
       
  • Tensile biomechanical properties and constitutive parameters of human
           corneal stroma extracted by SMILE procedure
    • Authors: Yaoqi Xiang; Min Shen; Chao Xue; Di Wu; Yan Wang
      Pages: 102 - 108
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Yaoqi Xiang, Min Shen, Chao Xue, Di Wu, Yan Wang
      The biomechanical behavior of human corneal stroma under uniaxial tension was investigated by the experimental analysis of cornea stromal lenticules taken out by corneal refractive surgery. Uniaxial tests were conducted to determine their stress-strain relationship and tensile strength. The Gasser-Ogden-Holzapfel (GOH) model was used to describe biomechanical behavior of the corneal stroma. The theoretical stress-strain relationship of the GOH model in the uniaxial tensile test was deduced. The corneal specimens were collected from ten patients (4 male and 6 female), aged from 17 to 36. The differences between corneal stress-strain relationship in the horizontal and vertical direction were compared. The constitutive parameters C 10, k 1 and k 2 were evaluated through least squares curve-fitting of experimental data.

      PubDate: 2018-06-07T08:14:03Z
      DOI: 10.1016/j.jmbbm.2018.05.042
      Issue No: Vol. 85 (2018)
       
  • Comparison of five viscoelastic models for estimating viscoelastic
           parameters using ultrasound shear wave elastography
    • Authors: Boran Zhou; Xiaoming Zhang
      Pages: 109 - 116
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Boran Zhou, Xiaoming Zhang
      The purpose of this study is to compare five viscoelastic models (Voigt, Maxwell, standard linear solid, spring-pot, and fractional Voigt models) for estimating viscoelastic properties based on ultrasound shear wave elastography measurements. We performed the forward problem analysis, the inverse problem analysis, and experiments. In the forward problem analysis, the shear wave speeds at different frequencies were calculated using the Voigt model for given shear elasticity and varying shear viscosity. In the inverse problem analysis, the viscoelastic parameters were estimated from the given wave speeds for the five viscoelastic models using the least-square regression. The experiment was performed in a tissue-mimicking phantom. A local harmonic vibration was generated via a mechanical shaker on the phantom at five frequencies (100, 150, 200, 250, and 300 Hz) and an ultrasound transducer was used to capture the tissue motion. Shear wave speed of the phantom was measured using the ultrasound shear wave elastography technique. The parameters for different viscoelastic models for the phantom were identified. For both analytical and experimental studies, ratios of storage to loss modulus as a function of excitation frequency for different viscoelastic models were calculated. We found that the Voigt and fractional Voigt models fit well with the shear wave speed - frequency and ratio of storage to loss modulus – frequency relationships both in analytical and experimental studies.

      PubDate: 2018-06-07T08:14:03Z
      DOI: 10.1016/j.jmbbm.2018.05.041
      Issue No: Vol. 85 (2018)
       
  • Effects of subpressure on the sealing ability of dental sealant in vitro
    • Authors: Y.M. Tian; R.S. Zhuge; Z.T. Zhang; D.X. Zheng; N. Ding; Y.M. Li
      Pages: 117 - 123
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Y.M. Tian, R.S. Zhuge, Z.T. Zhang, D.X. Zheng, N. Ding, Y.M. Li
      Objectives Pits and fissures sealing with flowable materials is a popular method for preventing caries in preventive dentistry while there is still microleakage existed. This in vitro study aimed to explore the effects of subpressure technique on the sealing ability of pit and fissure sealant. Materials and methods One hundred and forty-one extracted human premolars were collected in this study and treated with different pressure (atmosphere pressure as group C, −0.04 MPa as group S4 and −0.08 MPa as group S8). Thermocycling (×5000) was also performed. Penetration percentage, microleakage, cross-sectional microhardness (Knoop, KMH) and mineral loss were evaluated. Kappa tests, Friedman nonparametric and two-way ANOVA were used for data analysis. Results Penetration percentages of group S4 and S8 were significant higher compared to that of group C. Microleakage of groups was similar before thermocycling, while subpressure groups showed lower scale of microleakage after thermocycling. Data of KMH and mineral loss showed significant differences between subpressure and thermocycling groups. Significance Subpressure technique could increase the penetration of pit and fissure sealant, decrease microleakage and increase resistance of demineralization after thermocycling. This novel technique may have great potential for preventing from secondary caries.
      Graphical abstract image

      PubDate: 2018-06-07T08:14:03Z
      DOI: 10.1016/j.jmbbm.2018.05.023
      Issue No: Vol. 85 (2018)
       
  • Bone healing response in cyclically loaded implants: Comparing zero, one,
           and two loading sessions per day
    • Authors: Renan de Barros e Lima Bueno; Ana Paula Dias; Katia J. Ponce; Rima Wazen; John B. Brunski; Antonio Nanci
      Pages: 152 - 161
      Abstract: Publication date: September 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 85
      Author(s): Renan de Barros e Lima Bueno, Ana Paula Dias, Katia J. Ponce, Rima Wazen, John B. Brunski, Antonio Nanci
      When bone implants are loaded, they are inevitably subjected to displacement relative to bone. Such micromotion generates stress/strain states at the interface that can cause beneficial or detrimental sequels. The objective of this study is to better understand the mechanobiology of bone healing at the tissue-implant interface during repeated loading. Machined screw shaped Ti implants were placed in rat tibiae in a hole slightly bigger than the implant diameter. Implants were held stable by a specially-designed bone plate that permits controlled loading. Three loading regimens were applied, (a) zero loading, (b) one daily loading session of 60 cycles with an axial force of 1.5 N/cycle for 7 days, and (c) two such daily sessions with the same axial force also for 7 days. Finite element analysis was used to characterize the mechanobiological conditions produced by the loading sessions. After 7 days, the implants with surrounding interfacial tissue were harvested and processed for histological, histomorphometric and DNA microarray analyses. Histomorphometric analyses revealed that the group subjected to repeated loading sessions exhibited a significant decrease in bone-implant contact and increase in bone-implant distance, as compared to unloaded implants and those subjected to only one loading session. Gene expression profiles differed during osseointegration between all groups mainly with respect to inflammatory and unidentified gene categories. The results indicate that increasing the daily cyclic loading of implants induces deleterious changes in the bone healing response, most likely due to the accumulation of tissue damage and associated inflammatory reaction at the bone-implant interface.
      Graphical abstract image

      PubDate: 2018-06-10T08:28:08Z
      DOI: 10.1016/j.jmbbm.2018.05.044
      Issue No: Vol. 85 (2018)
       
  • Osteogenesis of 3D printed porous Ti6Al4V implants with different pore
           sizes
    • Authors: Qichun Ran; Weihu Yang; Yan Hu; Xinkun Shen; Yonglin Yu; Yang Xiang; Kaiyong Cai
      Pages: 1 - 11
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Qichun Ran, Weihu Yang, Yan Hu, Xinkun Shen, Yonglin Yu, Yang Xiang, Kaiyong Cai
      Selective laser melting (SLM) is one of the three-dimensional (3D) printing techniques that manufacturing versatile porous scaffolds with precise architectures for potential orthopedic application. To understand how the pore sizes of porous Ti6Al4V scaffolds affect their biological performances, we designed and fabricated porous Ti6Al4V implants with straightforward pore dimensions (500, 700, and 900 µm) via SLM, termed as p500, p700, and p900 respectively. The morphological characteristics of Ti6Al4V scaffolds were assessed showing that the actual pore sizes of these scaffolds were 401 ± 26 µm, 607 ± 24 µm, 801 ± 33 µm, respectively. The mechanical properties of Ti6Al4V scaffolds were also evaluated showing that they were comparable to that of bone tissues. Meanwhile, the effect of pore size on biological responses was systematically investigated in vitro and in vivo. It was verified that 3D printing technique was able to fabricate porous Ti6Al4V implants with proper mechanical properties analogous to human bone. The in vitro results revealed that scaffolds with appropriate pore dimension were conducive to cell adhesion, proliferation and early differentiation. Furthermore, the porous Ti6Al4V scaffolds were implanted into the rabbit femur to investigate bone regeneration performance, the in vivo experiment showed the p700 sample was in favor of bone ingrowth into implant pores and bone-implant fixation stability. Taken together, the biological performance of p700 group with actual pore size of about 600 µm was superior to other two groups. The obtained findings provide basis to individually design and fabricate suitable porous Ti6Al4V with specific geometries for orthopedic application.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.010
      Issue No: Vol. 84 (2018)
       
  • A catheter friction tester using balance sensor: Combined evaluation of
           the effects of mechanical properties of tubing materials and surface
           coatings
    • Authors: Troels Røn; Kristina Pilgaard Jacobsen; Seunghwan Lee
      Pages: 12 - 21
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Troels Røn, Kristina Pilgaard Jacobsen, Seunghwan Lee
      In this study, we introduce a new experimental approach to characterize the forces emerging from simulated catherization. This setup allows for a linear translation of urinary catheters in vertical direction as controlled by an actuator. By employing silicone-based elastomer with a duct of comparable diameter with catheters as urethra model, sliding contacts during the translation of catheters along the duct is generated. A most unique design and operation feature of this setup is that a digital balance was employed as the sensor to detect emerging forces from simulated catherization. Moreover, the possibility to give a variation in environment (ambient air vs. water), clearance, elasticity, and curvature of silicone-based urethra model allows for the detection of forces arising from diverse simulated catherization conditions. Two types of commercially available catheters varying in tubing materials and surface coatings were tested together with their respective uncoated catheter tubing. The first set of testing on the catheter samples showed that this setup can probe the combined effect from flexural strain of bulk tubing materials and slipperiness of surface coatings, both of which are expected to affect the comfort and smooth gliding in clinical catherization. We argue that this new experimental setup can provide unique and valuable information in preclinical friction testing of urinary catheters.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.023
      Issue No: Vol. 84 (2018)
       
  • Effect of two-step and one-step surface conditioning of glass ceramic on
           adhesion strength of orthodontic bracket and effect of thermo-cycling on
           adhesion strength
    • Authors: Moshabab A. Asiry; Ibrahim AlShahrani; Samer M. Alaqeel; Bangalore H. Durgesh; Ravikumar Ramakrishnaiah
      Pages: 22 - 27
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Moshabab A. Asiry, Ibrahim AlShahrani, Samer M. Alaqeel, Bangalore H. Durgesh, Ravikumar Ramakrishnaiah
      Purpose The adhesion strength of orthodontic brackets bonded to dental glass ceramics was evaluated after ceramic surface was treated with two-step and one-step surface conditioning systems, and subjecting to thermo-cycling. Materials and method A total of forty specimens were fabricated from silica based glass ceramic (lithium disilicate) by duplicating the buccal surface of maxillary first premolar. The specimens were randomly assigned to two experimental groups (n = 20), group one specimens were treated with two-step surface conditioning system (IPS ceramic etching gel™ and Monobond plus™) and group two specimens were treated with one-step surface conditioning system (Monobond etch and prime™). The surface roughness of the specimens after treatment with two-step and one-step surface conditioning system was measured using non-contact surface profilometer. Ten randomly selected specimens from each group were subjected to thermo-cycling and the remaining ten served as baseline. The shear bond strength of the specimens was measured using universal material testing machine. The adhesive remnant index score was calculated, and the results of surface roughness and bond strength were tabulated and subjected to analysis of variance and post hoc tukey's test at a significance level of p < 0.05. Results The results of the study showed that the specimens treated with two-step conditioning system had higher surface roughness and bond strength than one-step conditioning system. The majority of the specimens treated with both two-step and one-step conditioned specimens showed adhesive failure after subjecting thermo-cycling. Conclusions Traditional two-step conditioning provides better bond strength. The clinical importance of the study is that, the silane promoted adhesion significantly reduces on exposure to thermo-cycling.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.021
      Issue No: Vol. 84 (2018)
       
  • Uncoupled poroelastic and intrinsic viscoelastic dissipation in cartilage
    • Authors: Guebum Han; Cole Hess; Melih Eriten; Corinne R. Henak
      Pages: 28 - 34
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Guebum Han, Cole Hess, Melih Eriten, Corinne R. Henak
      This paper studies uncoupled poroelastic (flow-dependent) and intrinsic viscoelastic (flow-independent) energy dissipation mechanisms via their dependence on characteristic lengths to understand the root of cartilage's broadband dissipation behavior. Phase shift and dynamic modulus were measured from dynamic microindentation tests conducted on hydrated cartilage at different contact radii, as well as on dehydrated cartilage. Cartilage weight and thickness were recorded during dehydration. Phase shifts revealed poroelastic- and viscoelastic-dominant dissipation regimes in hydrated cartilage. Specifically, phase shift at a relatively small radius was governed by poroviscoelasticity, while phase shift at a relatively large radius was dominantly governed by intrinsic viscoelasticity. The uncoupled dissipation mechanisms demonstrated that intrinsic viscoelastic dissipation provided sustained broadband dissipation for all length scales, and additional poroelastic dissipation increased total dissipation at small length scales. Dehydration decreased intrinsic viscoelastic dissipation of cartilage. The findings demonstrated a possibility to measure poroelastic and intrinsic viscoelastic properties of cartilage at similar microscale lengths. Also they encouraged development of broadband cartilage like-dampers and provided important design parameters to maximize their performance.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.024
      Issue No: Vol. 84 (2018)
       
  • Enhancing the mechanical and in vitro performance of robocast bioglass
           scaffolds by polymeric coatings: Effect of polymer composition
    • Authors: Azadeh Motealleh; Siamak Eqtesadi; Antonia Pajares; Pedro Miranda
      Pages: 35 - 45
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Azadeh Motealleh, Siamak Eqtesadi, Antonia Pajares, Pedro Miranda
      The effect of different polymeric coatings, including natural and synthetic compositions, on the mechanical performance of 45S5 bioglass robocast scaffolds is systematically analyzed in this work. Fully amorphous 45S5 bioglass robocast scaffolds sintered at 550 °C were impregnated with natural (gelatin, alginate, and chitosan) and synthetic (polycaprolactone, PCL and poly-lactic acid, PLA) polymers through a dip-coating process. Mechanical enhancement provided by these coatings in terms of both compressive strength and strain energy density was evaluated. Natural polymers, in general, and chitosan, in particular, were found to produce the greater reinforcement. The effect of these coatings on the in vitro bioactivity and degradation behavior of 45S5 bioglass robocast scaffolds was also investigated through immersion tests in simulated body fluid (SBF). Coatings from natural polymers, especially chitosan, are shown to have a positive effect on the bioactivity of 45S5 bioglass, accelerating the formation of an apatite-like layer. Besides, most coating compositions reduced the degradation (weight loss) rate of the scaffold, which has a positive impact on the evolution of their mechanical properties.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.022
      Issue No: Vol. 84 (2018)
       
  • Attachment and spatial organisation of human mesenchymal stem cells on
           poly(ethylene glycol) hydrogels
    • Authors: Aman S. Chahal; Manuel Schweikle; Catherine A. Heyward; Hanna Tiainen
      Pages: 46 - 53
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Aman S. Chahal, Manuel Schweikle, Catherine A. Heyward, Hanna Tiainen
      Strategies that enable hydrogel substrates to support cell attachment typically incorporate either entire extracellular matrix proteins or synthetic peptide fragments such as the RGD (arginine–glycine–aspartic acid) motif. Previous studies have carefully analysed how material characteristics can affect single cell morphologies. However, the influence of substrate stiffness and ligand presentation on the spatial organisation of human mesenchymal stem cells (hMSCs) have not yet been examined. In this study, we assessed how hMSCs organise themselves on soft (E = 7.4–11.2 kPa) and stiff (E = 27.3–36.8 kPa) poly(ethylene glycol) (PEG) hydrogels with varying concentrations of RGD (0.05–2.5 mM). Our results indicate that hMSCs seeded on soft hydrogels clustered with reduced cell attachment and spreading area, irrespective of RGD concentration and isoform. On stiff hydrogels, in contrast, cells spread with high spatial coverage for RGD concentrations of 0.5 mM or higher. In conclusion, we identified that an interplay of hydrogel stiffness and the availability of cell attachment motifs are important factors in regulating hMSC organisation on PEG hydrogels. Understanding how cells initially interact and colonise the surface of this material is a fundamental prerequisite for the design of controlled platforms for tissue engineering and mechanobiology studies.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.025
      Issue No: Vol. 84 (2018)
       
  • Zebrafish as a model to study bone maturation: Nanoscale structural and
           mechanical characterization of age-related changes in the zebrafish
           vertebral column
    • Authors: Zhuo Chang; Po-Yu Chen; Yung-Jen Chuang; Riaz Akhtar
      Pages: 54 - 63
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Zhuo Chang, Po-Yu Chen, Yung-Jen Chuang, Riaz Akhtar
      Zebrafish (Danio rerio) is a useful model for understanding biomedical properties of bone and are widely employed in developmental and genetics studies. Here, we have studied the development of zebrafish vertebral bone at the nanoscale from adolescence (6 months), early adulthood (10 months) to mid-life (14 months). Characterization of the bone was conducted using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and PeakForce QNM atomic force microscopy (AFM) techniques. SEM and AFM revealed a lamellar structure with mineralized collagen fibrils. There was a significant increase in the wall thickness from 6 to 10 months (76%) and 10 months to 14 months (26%), which is positively correlated with nanomechanical behavior. An increase in the Ca/P ratio was found which was also positively correlated with nanomechanical properties. The change in mechanical properties and Ca/P are similar to those expected in humans when transitioning from adolescence to mid-life. We suggest that zebrafish serve as a suitable model for further studies on age-related changes in bone ultrastructure.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.004
      Issue No: Vol. 84 (2018)
       
  • Age-related mechanical strength evolution of trabecular bone under fatigue
           damage for both genders: Fracture risk evaluation
    • Authors: Rabeb Ben Kahla; Abdelwahed Barkaoui; Tarek Merzouki
      Pages: 64 - 73
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Rabeb Ben Kahla, Abdelwahed Barkaoui, Tarek Merzouki
      Bone tissue is a living composite material, providing mechanical and homeostatic functions, and able to constantly adapt its microstructure to changes in long term loading. This adaptation is conducted by a physiological process, known as "bone remodeling". This latter is manifested by interactions between osteoclasts and osteoblasts, and can be influenced by many local factors, via effects on bone cell differentiation and proliferation. In the current work, age and gender effects on damage rate evolution, throughout life, have been investigated using a mechanobiological finite element modeling. To achieve the aim, a mathematical model has been developed, coupling both cell activities and mechanical behavior of trabecular bone, under cyclic loadings. A series of computational simulations (ABAQUS/UMAT) has been performed on a 3D human proximal femur, allowing to investigate the effects of mechanical and biological parameters on mechanical strength of trabecular bone, in order to evaluate the fracture risk resulting from fatigue damage. The obtained results revealed that mechanical stimulus amplitude affects bone resorption and formation rates, and indicated that age and gender are major factors in bone response to the applied loadings.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.006
      Issue No: Vol. 84 (2018)
       
  • Engineering mesenchymal stem cell spheroids by incorporation of
           mechanoregulator microparticles
    • Authors: Fatemeh Abbasi; Mohammad Hossein Ghanian; Hossein Baharvand; Bahman Vahidi; Mohamadreza Baghaban Eslaminejad
      Pages: 74 - 87
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Fatemeh Abbasi, Mohammad Hossein Ghanian, Hossein Baharvand, Bahman Vahidi, Mohamadreza Baghaban Eslaminejad
      Mechanical forces throughout human mesenchymal stem cell (hMSC) spheroids (mesenspheres) play a predominant role in determining cellular functions of cell growth, proliferation, and differentiation through mechanotransductional mechanisms. Here, we introduce microparticle (MP) incorporation as a mechanical intervention method to alter tensional homeostasis of the mesensphere and explore MSC differentiation in response to MP stiffness. The microparticulate mechanoregulators with different elastic modulus (34 kPa, 0.6 MPa, and 2.2 MPa) were prepared by controlled crosslinking cell-sized microdroplets of polydimethylsiloxane (PDMS). Preparation of MP-MSC composite spheroids enabled us to study the possible effects of MPs through experimental and computational assays. Our results showed that MP incorporation selectively primed MSCs toward osteogenesis, yet hindered adipogenesis. Interestingly, this behavior depended on MP mechanics, as the spheroids that contained MPs with intermediate stiffness behaved similar to control MP-free mesenspheres with more tendencies toward chondrogenesis. However, by using the soft or stiff MPs, the MP-mesenspheres significantly showed signs of osteogenesis. This could be explained by the complex of forces which acted in the cell spheroid and, totally, provided a homeostasis situation. Incorporation of cell-sized polymer MPs as mechanoregulators of cell spheroids could be utilized as a new engineering toolkit for multicellular organoids in disease modeling and tissue engineering applications.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.026
      Issue No: Vol. 84 (2018)
       
  • Brain stiffens post mortem
    • Authors: J. Weickenmeier; M. Kurt; E. Ozkaya; R. de Rooij; T.C. Ovaert; R.L. Ehman; K. Butts Pauly; E. Kuhl
      Pages: 88 - 98
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): J. Weickenmeier, M. Kurt, E. Ozkaya, R. de Rooij, T.C. Ovaert, R.L. Ehman, K. Butts Pauly, E. Kuhl
      Alterations in brain rheology are increasingly recognized as a diagnostic marker for various neurological conditions. Magnetic resonance elastography now allows us to assess brain rheology repeatably, reproducibly, and non-invasively in vivo. Recent elastography studies suggest that brain stiffness decreases one percent per year during normal aging, and is significantly reduced in Alzheimer's disease and multiple sclerosis. While existing studies successfully compare brain stiffnesses across different populations, they fail to provide insight into changes within the same brain. Here we characterize rheological alterations in one and the same brain under extreme metabolic changes: alive and dead. Strikingly, the storage and loss moduli of the cerebrum increased by 26% and 60% within only three minutes post mortem and continued to increase by 40% and 103% within 45 minutes. Immediate post mortem stiffening displayed pronounced regional variations; it was largest in the corpus callosum and smallest in the brainstem. We postulate that post mortem stiffening is a manifestation of alterations in polarization, oxidation, perfusion, and metabolism immediately after death. Our results suggest that the stiffness of our brain–unlike any other organ–is a dynamic property that is highly sensitive to the metabolic environment. Our findings emphasize the importance of characterizing brain tissue in vivo and question the relevance of ex vivo brain tissue testing as a whole. Knowing the true stiffness of the living brain has important consequences in diagnosing neurological conditions, planning neurosurgical procedures, and modeling the brain's response to high impact loading.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.009
      Issue No: Vol. 84 (2018)
       
  • Relationships of bone characteristics in MYO9B deficient femurs
    • Authors: Do-Gyoon Kim; Yong-Hoon Jeong; Brooke K. McMichael; Martin Bähler; Kyle Bodnyk; Ryan Sedlar; Beth S. Lee
      Pages: 99 - 107
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Do-Gyoon Kim, Yong-Hoon Jeong, Brooke K. McMichael, Martin Bähler, Kyle Bodnyk, Ryan Sedlar, Beth S. Lee
      The objective of this study was to examine relationships among a variety of bone characteristics, including volumetric, mineral density, geometric, dynamic mechanical analysis, and static fracture mechanical properties. As MYO9B is an unconventional myosin in bone cells responsible for normal skeletal growth, bone characteristics of wild-type (WT), heterozygous (HET), and MYO9B knockout (KO) mice groups were compared as an animal model to express different bone quantity and quality. Forty-five sex-matched 12-week-old mice were used in this study. After euthanization, femurs were isolated and scanned using microcomputed tomography (micro-CT) to assess bone volumetric, tissue mineral density (TMD), and geometric parameters. Then, a non-destructive dynamic mechanical analysis (DMA) was performed by applying oscillatory bending displacement on the femur. Finally, the same femur was subject to static fracture testing. KO group had significantly lower length, bone mineral density (BMD), bone mass and volume, dynamic and static stiffness, and strength than WT and HET groups (p < 0.019). On the other hand, TMD parameters of KO group were comparable with those of WT group. HET group showed volumetric, geometric, and mechanical properties similar to WT group, but had lower TMD (p < 0.014). Non-destructive micro-CT and DMA parameters had significant positive correlations with strength (p < 0.015) without combined effect of groups and sex on the correlations (p > 0.077). This comprehensive characterization provides a better understanding of interactive behavior between the tissue- and organ-level of the same femur. The current findings elucidate that MYO9B is responsible for controlling bone volume to determine the growth rate and fracture risk of bone.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.003
      Issue No: Vol. 84 (2018)
       
  • Facile preparation of biocompatible poly (lactic acid)-reinforced
           poly(ε-caprolactone) fibers via graphite nanoplatelets -aided melt
           spinning
    • Authors: Ivan Kelnar; Alexander Zhigunov; Ludmila Kaprálková; Ivan Fortelný; Jiří Dybal; Jaroslav Kratochvíl; Martina Nevoralová; Marcela Hricová; Viera Khunová
      Pages: 108 - 115
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Ivan Kelnar, Alexander Zhigunov, Ludmila Kaprálková, Ivan Fortelný, Jiří Dybal, Jaroslav Kratochvíl, Martina Nevoralová, Marcela Hricová, Viera Khunová
      Addition of high-aspect-ratio (AR) nanofillers can markedly influence flow behavior of polymer systems. As a result, application of graphite nanoplatelets (GNP) allows preparation of microfibrillar composites (MFC) based on PCL matrix reinforced with in-situ generated PLA fibrils. This work deals, for the first time, with preparation of analogous melt-drawn fibers. Unlike other blend-based fibers, the spinning and melt drawing leads to structure of deformed inclusions due to unfavorable ratio of rheological parameters of components. Subsequent moderate cold drawing of the system with dissimilar deformability of components causes strengthening with PLA fibrils. Unexpectedly, high velocity and extent of cold drawing leads to structure with low-AR inclusions, similar to the original melt-drawn blend. Extensive fast deformation of the soft PCL matrix does not allow sufficient stress transfer to rigid PLA. In spite of peculiarities found, the GNP-aided melt spinning allows facile preparation of biodegradable biocompatible fibers with wide range of diameters (80–400 µm) and parameters (2.35–18 cN/tex).
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.013
      Issue No: Vol. 84 (2018)
       
  • Optimization of collagen-elastin-like polypeptide composite tissue
           engineering scaffolds using response surface methodology
    • Authors: Bhuvaneswari Gurumurthy; Jason A. Griggs; Amol V. Janorkar
      Pages: 116 - 125
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Bhuvaneswari Gurumurthy, Jason A. Griggs, Amol V. Janorkar
      The ability of a tissue-engineered scaffold to regenerate functional tissues depends on its mechanical and biochemical properties. Though the commonly used collagen scaffolds have good biochemical properties, they fail due to their poor mechanical and physical properties. We have reinforced the collagen matrix with elastin-like polypeptide (ELP) to improve the mechanical and physical properties and optimized the composite composition using a novel statistical method of response surface methodology (RSM). RSM used a central composite design to correlate the 2 input factor variables (collagen and ELP concentrations) and 3 output objectives (tensile strength, elastic modulus, and toughness) using a second order polynomial equation. Upon uniaxial tensile testing and subsequent RSM optimization, a composite prepared using 6 mg/mL collagen and 18 mg/mL ELP was identified as having an optimal combination of all the three tensile properties. Physical properties of the 6:18 mg/mL composite versus the 6:0 mg/mL collagen-only hydrogel characterized by swelling ratio, differential scanning calorimetry, and FTIR spectroscopy revealed that the addition of ELP reduced the residual water content in the composites and provided evidence of the presence of collagen-ELP interactions. Scanning electron microscopy images of the collagen-only hydrogel showed porous fibrillar and dense afibrillar collagenous microstructure, but the collagen-ELP composite showed a dense collagenous microstructure with characteristic ELP aggregates. We surmise that because of the low water content and dense microstructure, the 6:18 mg/mL collagen-ELP composite had improved mechanical properties. Taken together, the composites prepared in this research can form good quality, rigid porous structures required for tissue engineering applications.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.04.019
      Issue No: Vol. 84 (2018)
       
  • Composite self-expanding bioresorbable prototype stents with reinforced
           compression performance for congenital heart disease application:
           Computational and experimental investigation
    • Authors: Fan Zhao; Wen Xue; Fujun Wang; Laijun Liu; Haoqin Shi; Lu Wang
      Pages: 126 - 134
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Fan Zhao, Wen Xue, Fujun Wang, Laijun Liu, Haoqin Shi, Lu Wang
      Stents are vital devices to treat vascular stenosis in pediatric patients with congenital heart disease. Bioresorbable stents (BRSs) have been applied to reduce challenging complications caused by permanent metal stents. However, it remains almost a total lack of BRSs with satisfactory compression performance specifically for children with congenital heart disease, leading to importantly suboptimal effects. In this work, composite bioresorbable prototype stents with superior compression resistance were designed by braiding and annealing technology, incorporating poly (p-dioxanone) (PPDO) monofilaments and polycaprolactone (PCL) multifilament. Stent prototype compression properties were investigated. The results revealed that novel composite prototype stents showed superior compression force compared to the control ones, as well as recovery ability. Furthermore, deformation mechanisms were analyzed by computational simulation, which revealed bonded interlacing points among yarns play an important role. This research presents important clinical implications in bioresorbable stent manufacture and provides further study with an innovative stent design.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.009
      Issue No: Vol. 84 (2018)
       
  • Simultaneous magnetic resonance and optical elastography acquisitions:
           Comparison of displacement images and shear modulus estimations using a
           single vibration source
    • Authors: Spencer T. Brinker; Steven P. Kearney; Thomas J. Royston; Dieter Klatt
      Pages: 135 - 144
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Spencer T. Brinker, Steven P. Kearney, Thomas J. Royston, Dieter Klatt
      The mechanical properties of tissue are sensitive to pathological changes, which is the basis for using dynamic elastography as a diagnostic tool. The purpose of this study is a concurrent cross-modality comparison of two dynamic elastography methods, Magnetic Resonance Elastography (MRE) and Scanning Laser Doppler Vibrometry (SLDV) using a single vibration source method. Cylindrical soft tissue mimicking specimens of Plastisol and Ecoflex are stimulated with 60, 100, 150, and 250 Hz sinusoidal vibration during imaging. Specimen stiffness was also varied by adjusting the softener amount in each material. Displacement fields acquired using the two methods show similarity in wave front geometry at all frequencies. Magnetic Resonance Elastography (MRE) with 3D inversion and Optical Elastography (OE) with averaged 1D curve fitting were used to derive complex shear moduli from each imaging modality. MRE and OE shear storage modulus (n = 3) results were closest at 150 Hz with Plastisol G’ (MRE) = 9.03 ± 0.43 kPa and G’ (OE) = 8.46 ± 0.14 kPa while Ecoflex was G’ (MRE) = 15.71 ± 0.95 kPa and G’ (OE) = 13.71 ± 0.03 kPa. Correlation between MRE and OE complex shear moduli related by all 36 coupled scans performed during this study yield a Pearson's correlation of ρ = 0.88 with p < 0.001 for G’ (storage modulus) and ρ = 0.85 with p < 0.001 for G” (loss modulus). The simultaneous imaging approach yields stiffness values within the same range and acceptable error margins for MRE and OE.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.010
      Issue No: Vol. 84 (2018)
       
  • Effect of ethanol-dissolved rhodamine B marker on mechanical properties of
           non-simplified adhesives
    • Authors: Camila Moreira Machado; Odair Bim Júnior; Marina Ciccone Giacomini; Márcia Sirlene Zardin Graeff; Fernanda Cristina Pimentel Garcia; Daniela Rios; Heitor Marques Honório; Linda Wang
      Pages: 145 - 150
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Camila Moreira Machado, Odair Bim Júnior, Marina Ciccone Giacomini, Márcia Sirlene Zardin Graeff, Fernanda Cristina Pimentel Garcia, Daniela Rios, Heitor Marques Honório, Linda Wang
      Objectives Rhodamine B (RB) is commonly used to evaluate dental polymers, including dental bonding systems (DBS). For reliability assessments, its effect should not only allow visualization of the dentin-polymer interface but also must not interfere with the bonding of the DBS to dentin as measured by the microtensile bond strength and hardness tests. Material and methods Flat human dentin surfaces were prepared and randomly distributed (n = 10) into six groups: Adper Scotchbond Multi-Purpose (MP) or Clearfil SE Bond (SE) in concentrations of none/control, 0.02 or 0.1 mg/mL. These combinations were prepared through ethanol dissolution to improve their penetration into the dentin. All specimens were fabricated with Filtek Z250 (n = 10) and prepared for a microtensile bond test (μTBS) (0.5 mm/min) after 7 days and 6 months. The failure modes were determined using a stereomicroscope (×40). For the hardness test, flat human dentin blocks were prepared and treated as previously described (n = 6). The specimens were stored at 37 °C/48 h and were tested (Knoop indenter − 25 gF/10 s). Data were analyzed with two-way ANOVA and Tukey tests for multiple comparisons (α = 0.05). The effect of time was evaluated using the Student t-test. Results For 7-day μTBS, both the DBS and RB concentrations were significant factors (p < 0.01). After 6 months, only the RB concentration was significantly different. Adhesive failures were prevalent for all groups. Regarding hardness, the DBS differed only with the use of 0.10 mg/mL of RB. Conclusions Ethanol-dissolved rhodamine B in concentrations of 0.02 and 0.10 mg/mL in non-simplified adhesives can affect the physical-mechanical properties of functional monomer-based systems rather more than those of BisGMA systems.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.012
      Issue No: Vol. 84 (2018)
       
  • Synthesis, microstructure, and mechanical behaviour of a unique porous
           PHBV scaffold manufactured using selective laser sintering
    • Authors: Sven H. Diermann; Mingyuan Lu; Yitian Zhao; Luigi-Jules Vandi; Matthew Dargusch; Han Huang
      Pages: 151 - 160
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Sven H. Diermann, Mingyuan Lu, Yitian Zhao, Luigi-Jules Vandi, Matthew Dargusch, Han Huang
      Selective Laser Sintering (SLS) is a promising technique for manufacturing bio-polymer scaffolds used in bone tissue engineering applications. Conventional scaffolds made using SLS have complex engineered architectures to introduce adequate porosity and pore interconnectivity. This study presents an alternative approach to manufacture scaffolds via SLS without using pre-designed architectures. In this work, a SLS process was developed for fabricating interconnected porous biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) scaffolds with large surface areas and relative porosities of up to 80%. These characteristics provide great potential to enhance cell attachment inside the scaffolds. The scaffold microstructure was dependent on the laser energy density (LED) during the SLS process. An increase in LED led to scaffolds with higher relative densities, stronger inter-layer connections, and a reduced quantity of residual powder trapped inside the pores. An increase in relative density from 20.3% to 41.1% resulted in a higher maximum compressive modulus and strength of 36.4 MPa and 6.7 MPa, respectively.
      Graphical abstract image Highlights fx1

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.007
      Issue No: Vol. 84 (2018)
       
  • Mechanical characterization and ion release of bioactive dental composites
           containing calcium phosphate particles
    • Authors: Livia C. Natale; Marcela C. Rodrigues; Yvette Alania; Marina D.S. Chiari; Leticia C.C. Boaro; Marycel Cotrim; Oscar Vega; Roberto R. Braga
      Pages: 161 - 167
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Livia C. Natale, Marcela C. Rodrigues, Yvette Alania, Marina D.S. Chiari, Leticia C.C. Boaro, Marycel Cotrim, Oscar Vega, Roberto R. Braga
      Objective to verify the effect of the addition of dicalcium phosphate dihydrate (DCPD) particles functionalized with di- or triethylene glycol dimethacrylate (DEGDMA or TEGDMA) on the degree of conversion (DC), post-gel shrinkage (PS), mechanical properties, and ion release of experimental composites. Methods Four composites were prepared containing a BisGMA/TEGDMA matrix and 60 vol% of fillers. The positive control contained only barium glass fillers, while in the other composites 15 vol% of the barium was replaced by DCPD. Besides the functionalized particles, non-functionalized DCPD was also tested. DC after 24 h (n = 3) was determined by FTIR spectroscopy. The strain gage method was used to obtain PS 5 min after photoactivation (n = 5). Flexural strength and modulus (n = 10) were calculated based on the biaxial flexural test results, after specimen storage for 24 h or 60 days in water. The same storage times were used for fracture toughness testing (FT, n = 10). Calcium and phosphate release up to 60 days was quantified by ICP-OES (n = 3). Data were analyzed by ANOVA/Tukey test (alpha: 5%). Results Composites containing functionalized DCPD presented higher DC than the control (p < 0.001). The material containing DEGDMA-functionalized particles showed higher PS than the other composites (p < 0.001). After 60 days, only the composite with DEGDMA-functionalized DCPD presented fracture strength similar to the control, while for flexural modulus only the composite with TEGDMA-functionalized particles was lower than the control (p < 0.001). FT of all composites containing DCPD was higher than the control after 60 days (p < 0.005). Calcium release was higher for the composite with non-functionalized DCPD at 15 days and no significant reductions were observed for composites with functionalized DCPD during the observation period (p < 0.001). For all the tested composites, phosphate release was higher at 15 days than in the subsequent periods, and no difference among them was recorded at 45 and 60 days (p < 0.001). Conclusions DCPD functionalization affected all the studied variables. The composite with DEGDMA-functionalized particles was the only material with strength similar to the control after 60 days in water; however, it also presented the highest shrinkage. The presence of DCPD improved FT, regardless of functionalization. DCPD functionalization reduced ion release only during the first 15 days.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.022
      Issue No: Vol. 84 (2018)
       
  • Chondron curvature mapping in growth plate cartilage under compressive
           loading
    • Authors: Bhavya B. Vendra; Esra Roan; John L. Williams
      Pages: 168 - 177
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Bhavya B. Vendra, Esra Roan, John L. Williams
      The physis, or growth plate, is a layer of cartilage responsible for long bone growth. It is organized into reserve, proliferative and hypertrophic zones. Unlike the reserve zone where chondrocytes are randomly arranged, either singly or in pairs, the proliferative and hypertrophic chondrocytes are arranged within tubular structures called chondrons. In previous studies, the strain patterns within the compressed growth plate have been reported to be nonuniform and inhomogeneous, with an apparent random pattern in compressive strains and a localized appearance of tensile strains. In this study we measured structural deformations along the entire lengths of chondrons when the physis was subjected to physiological (20%) and hyper-physiological (30% and 40%) levels of compression. This provided a means to interpret the apparent random strain patterns seen in texture correlation maps in terms of bending deformations of chondron structures and provided a physical explanation for the inhomogeneous and nonuniform strain patterns reported in previous studies. We observed relatively large bending deformations (kinking) of the chondron structures at the interface of the reserve and proliferative zones during compression. Bending in this region may induce dividing cells to align longitudinally to maintain column formation and drive longitudinal growth.
      Graphical abstract image

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.015
      Issue No: Vol. 84 (2018)
       
  • Lessons from mosquitoes’ painless piercing
    • Authors: Dev Gurera; Bharat Bhushan; Navin Kumar
      Pages: 178 - 187
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Dev Gurera, Bharat Bhushan, Navin Kumar
      Arthropods are the largest group of the living organisms. They attack other organisms by biting, stinging, or piercing and sucking. Among various medically important arthropods, which feed on living hosts, mosquitoes’ piercing spread viruses which have been reported to cause the highest number of deaths annually. The primary cause of the deaths is malaria, which is spread by infected mosquitoes’ piercing. This study aims at elucidating lessons from mosquitoes’ painless piercing. Mosquitoes pierce using their fascicle, which is a bundle of coherently functioning six stylets. Based on experiments and available literature, it is presented that mosquitoes painlessly pierce using a combination of the numbing, the fascicle's serrated design, the vibratory actuation, and the graded and frequency-dependent mechanical properties of the labrum. Based on this understanding, a mosquito-inspired microneedle design has also been proposed.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.025
      Issue No: Vol. 84 (2018)
       
  • Mechanical properties of the human scalp in tension
    • Authors: Lisa Falland-Cheung; Mario Scholze; Pamela F. Lozano; Benjamin Ondruschka; Darryl C. Tong; Paul A. Brunton; J. Neil Waddell; Niels Hammer
      Pages: 188 - 197
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Lisa Falland-Cheung, Mario Scholze, Pamela F. Lozano, Benjamin Ondruschka, Darryl C. Tong, Paul A. Brunton, J. Neil Waddell, Niels Hammer
      Mechanical properties of the human scalp have not been investigated to a great extent with limited information available. The purpose of this study was to provide new baseline material data for human scalp tissue of various ages, which can be applied to experimental and constitutive models, such as in the area of impact biomechanics. This study used specimens from the left and right temporal, fronto-parietal and occipital regions of the human scalp. It investigated the tensile behavior of scalp tissue using tissues harvested from unfixed, fresh cadavers. These samples were subjected to an osmotic stress analysis and upon testing, cyclic loading followed by stretching until failure in a universal testing machine. Strain evaluation was conducted using digital image correlation in a highly standardized approach. Elastic modulus, tensile strength, strain at maximum load and strain to failure were evaluated computationally. No significant differences were observed comparing the tensile strength between males and females. In contrast to that, a sex-dependent difference was found for the elastic modulus of the occipital scalp region and for the elongation properties. Additionally, regional differences within the male group, as well as an age dependent correlation for females were found in the elastic modulus and tensile strength. Scanning electron microscope analyses have shown the ultrastructural failure patterns, indicated by damaged keratin plates, as well as partially disrupted and retraced collagens at the failure site. The novel data obtained in this study could add valuable information to be used for modeling purposes, as well as provide baseline data for simulant materials and comparisons of tissue properties following head injury or forensic investigations.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.024
      Issue No: Vol. 84 (2018)
       
  • Energy dissipation in quasi-linear viscoelastic tissues, cells, and
           extracellular matrix
    • Authors: Behzad Babaei; A.J. Velasquez-Mao; Kenneth M. Pryse; William B. McConnaughey; Elliot L. Elson; Guy M. Genin
      Pages: 198 - 207
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Behzad Babaei, A.J. Velasquez-Mao, Kenneth M. Pryse, William B. McConnaughey, Elliot L. Elson, Guy M. Genin
      Characterizing how a tissue's constituents give rise to its viscoelasticity is important for uncovering how hidden timescales underlie multiscale biomechanics. These constituents are viscoelastic in nature, and their mechanics must typically be assessed from the uniaxial behavior of a tissue. Confounding the challenge is that tissue viscoelasticity is typically associated with nonlinear elastic responses. Here, we experimentally assessed how fibroblasts and extracellular matrix (ECM) within engineered tissue constructs give rise to the nonlinear viscoelastic responses of a tissue. We applied a constant strain rate, “triangular-wave” loading and interpreted responses using the Fung quasi-linear viscoelastic (QLV) material model. Although the Fung QLV model has several well-known weaknesses, it was well suited to the behaviors of the tissue constructs, cells, and ECM tested. Cells showed relatively high damping over certain loading frequency ranges. Analysis revealed that, even in cases where the Fung QLV model provided an excellent fit to data, the the time constant derived from the model was not in general a material parameter. Results have implications for design of protocols for the mechanical characterization of biological materials, and for the mechanobiology of cells within viscoelastic tissues.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.011
      Issue No: Vol. 84 (2018)
       
  • Botulinum toxin type-A affects mechanics of non-injected antagonistic rat
           muscles
    • Authors: Filiz Ateş; Can A. Yucesoy
      Pages: 208 - 216
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Filiz Ateş, Can A. Yucesoy
      Botulinum toxin type A (BTX-A) effects on the mechanics of non-injected antagonistic muscles are unknown. The aim was to test the following hypotheses in a rat model: BTX-A injected into gastrocnemius medialis (GM) and lateralis (GL) (1) decreases forces of the antagonistic tibialis anterior (TA) and extensor digitorum longus (EDL), (2) reduces length range of force exertion and (3) increases passive forces of the TA, and (4) changes inter-antagonistic and inter-synergistic epimuscular myofascial force transmission (EMFT). Two groups of Wistar rats were tested: BTX (0.1 units of BTX-A were injected to the GM and GL, each) and Control (saline injected). Five-days post, TA, EDL, GM-GL, and soleus distal and EDL proximal isometric forces were measured after TA lengthening. BTX-A exposure caused forces of all muscles to decrease significantly. TA and EDL active force drops (maximally by 37.3%) show inter-compartmental spread. Length range of force exertion of the TA did not change, but its passive force increased significantly (by 25%). The percentages of intramuscular connective tissue content of the TA and EDL was higher (BTX: 20.0 ± 4.9% and 19.3 ± 4.1% vs. control: 13.1 ± 5.4% and 14.5 ± 4.0%, respectively). Calf muscles’ forces were not affected by TA length changes for both groups indicating lacking inter-antagonistic EMFT. However, BTX-A altered EDL proximo-distal force differences hence, inter-synergistic EMFT. A major novel finding is that BTX-A affects mechanics of non-injected antagonistic muscles in test conditions involving only limited EMFT. The effects indicating a stiffer muscle with no length range increase contradict some treatment aims, which require clinical testing.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.027
      Issue No: Vol. 84 (2018)
       
  • Modal analysis of nanoindentation data, confirming that reduced bone
           turnover may cause increased tissue mineralization/elasticity
    • Authors: Maria-Ioana Pastrama; Romane Blanchard; John G. Clement; Peter Pivonka; Christian Hellmich
      Pages: 217 - 224
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Maria-Ioana Pastrama, Romane Blanchard, John G. Clement, Peter Pivonka, Christian Hellmich
      It is widely believed that the activities of bone cells at the tissue scale not only govern the size of the vascular pore spaces (and hence, the amount of bone tissue available for actually carrying the loads), but also the characteristics of the extracellular bone matrix itself. In this context, increased mechanical stimulation (in mediolateral regions of human femora, as compared to anteroposterior regions) may lead to increased bone turnover, lower bone matrix mineralization, and therefore lower tissue modulus. On the other hand, resorption-only processes (in endosteal versus periosteal regions) may have the opposite effect. A modal analysis of nanoindentation data obtained on femurs from the Melbourne Femur Research Collection (MFRC) indeed confirms that bone is stiffer in endosteal regions compared to periosteal regions ( E ̅ endost = 29.34 ± 0.75 GPa > E ̅ periost = 24.67 ± 1.63 GPa), most likely due to the aging-related increase in resorption modeling on endosteal surfaces resulting in trabecularization of cortical bone. The results also show that bone is stiffer along the anteroposterior direction compared the mediolateral direction ( E ̅ anteropost = 28.89 ± 1.08 GPa > E ̅ mediolat = 26.03 ± 2.31 GPa), the former being aligned with the neutral bending axis of the femur and, thus, undergoing more resorption modeling and consequently being more mineralized.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.014
      Issue No: Vol. 84 (2018)
       
  • Influence of laser structuring of PEEK, PEEK-GF30 and PEEK-CF30 surfaces
           on the shear bond strength to a resin cement
    • Authors: Bruno Henriques; Douglas Fabris; Joana Mesquita-Guimarães; Anne C. Sousa; Nathalia Hammes; Júlio C.M. Souza; Filipe S. Silva; Márcio C. Fredel
      Pages: 225 - 234
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Bruno Henriques, Douglas Fabris, Joana Mesquita-Guimarães, Anne C. Sousa, Nathalia Hammes, Júlio C.M. Souza, Filipe S. Silva, Márcio C. Fredel
      Objectives The aim of this study was to evaluate the influence of a surface conditioning technique using laser ablation and acid etching on PEEK substrate on its bonding strength to a resin cement. Materials and methods Cylindrical specimens of unfilled PEEK, 30% glass fiber reinforced PEEK and 30% carbon fiber reinforced PEEK were separated in four groups according to the following surface treatments: acid etching with H2SO4, laser ablation with 200 µm holes spaced 400 µm apart (D2E4), laser ablation with 200 µm holes spaced 600 µm apart (D2E6), and laser ablation (D2E4) followed by acid etching. A dual-curing resin cement (Allcem CORE) was then applied to the PEEK surface. Specimens were aged in distilled water at 37 °C for 24 h. Shear bond strength tests were performed to the fracture of the samples. Two-way ANOVA statistical analysis was performed with a significance level of 0.05. Scanning electron microscopy analysis was performed to analyse the conditioned and fracture surfaces. Results SEM images of the test interfaces showed that the resin cement could not flow in the holes designed by the laser ablation on the PEEK surface. The shear bond strength of PEEK to resin cement was not improved by the surface modification of the PEEK. Also, there was a statistically significant decrease in shear bond strength for unfilled PEEK specimens. On carbon or glass reinforced PEEK, the change was not significant. SEM images of the fracture surfaces revealed that the failure mode was mainly adhesive. Conclusions Although laser ablation promoted the PEEK surface modification by the formation of retentive holes, the test resin cement could not thoroughly flow on the rough modified surfaces to establish an effective mechanical interlocking. That negatively affected the shear bonding strength of PEEK to the resin cement. Further studies should be carried out to increase the bonding between PEEK and resin cements.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.008
      Issue No: Vol. 84 (2018)
       
  • Factors influencing the effectiveness of occupant retention under far-side
           impacts: A parametric study
    • Authors: Sagar Umale; Narayan Yoganandan; Frank A. Pintar; Mike W.J. Arun
      Pages: 235 - 248
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Sagar Umale, Narayan Yoganandan, Frank A. Pintar, Mike W.J. Arun
      The occupant retention and injuries under far-side impact are invariably dependent upon the effectiveness of the seatbelt restraint system, which is largely driven by parameters such as seatbelt pre-tensioner limiting load, D-ring position above and behind the shoulder, and friction coefficient between the torso and the seatbelt. The cumulative effect of systematic variation of these parameters on occupant kinematics under far-side is rarely studied in the literature. In this study, a systematic and detailed analysis was performed to understand the effect of these parameters on occupant retention. A rigid buck assembly with Global Human Body Model Consortium Human Body Model, validated with post mortem human surrogate experiments was used under two different impact scenarios—lateral and oblique. A simulation matrix of 16 cases was designed by varying the magnitude of the parameters for each impact scenario. Each case was graded as good, moderate, or poor retention based on the position of the shoulder seatbelt at the time of rebound. Head accelerations and excursions, chest compression, rib fractures, and neck moments of the HBM were analyzed to understand the effect of improved retention on occupant kinematics. Results showed that higher pre-tensioner limiting load, higher seatbelt friction, and backward position of D-ring improved retention in both lateral and oblique scenarios. Head acceleration, and excursions and chest compression decreased from poor retention cases to good retention cases for both impact scenarios. Rib fractures were higher in cases with poor retention as compared to those with good retention. The peak lateral neck moments changed marginally from poor to good retention; however, the rate of loading of the neck was significantly higher in good retention. Thus, the current study suggested that the backward D-ring position coupled with higher pretensioner limiting load and friction is likely to improve retention in far-side impacts and prevent injuries from the occupant slipping out of the restraint system. Better retention reduced occupant acceleration, excursion, chest compression and number of rib fractures, on the contrary it might instill higher injury vulnerability to neck and brain.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.021
      Issue No: Vol. 84 (2018)
       
  • The rib cage stiffens the thoracic spine in a cadaveric model with body
           weight load under dynamic moments
    • Authors: Erin M. Mannen; Elizabeth A. Friis; Hadley L. Sis; Benjamin M. Wong; Eileen S. Cadel; Dennis E. Anderson
      Pages: 258 - 264
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Erin M. Mannen, Elizabeth A. Friis, Hadley L. Sis, Benjamin M. Wong, Eileen S. Cadel, Dennis E. Anderson
      The thoracic spine presents a challenge for biomechanical testing. With more segments than the lumbar and cervical regions and the integration with the rib cage, experimental approaches to evaluate the mechanical behavior of cadaveric thoracic spines have varied widely. Some researchers are now including the rib cage intact during testing, and some are incorporating follower load techniques in the thoracic spine. Both of these approaches aim to more closely model physiological conditions. To date, no studies have examined the impact of the rib cage on thoracic spine motion and stiffness in conjunction with follower loads. The purpose of this research was to quantify the mechanical effect of the rib cage on cadaveric thoracic spine motion and stiffness with a follower load under dynamic moments. It was hypothesized that the rib cage would increase stiffness and decrease motion of the thoracic spine with a follower load. Eight fresh-frozen human cadaveric thoracic spines with rib cages (T1–T12) were loaded with a 400 N compressive follower load. Dynamic moments of ± 5 N m were applied in lateral bending, flexion/extension, and axial rotation, and the motion and stiffness of the specimens with the rib cage intact have been previously reported. This study evaluated the motion and stiffness of the specimens after rib cage removal, and compared the data to the rib cage intact condition. Range-of-motion and stiffness were calculated for the upper, middle, and lower segments of the thoracic spine. Range-of-motion significantly increased with the removal of the rib cage in lateral bending, flexion/extension, and axial rotation by 63.5%, 63.0%, and 58.8%, respectively (p < 0.05). Neutral and elastic zones increased in flexion/extension and axial rotation, and neutral zone stiffness decreased in axial rotation with rib cage removal. Overall, the removal of the rib cage increases the range-of-motion and decreases the stiffness of cadaveric thoracic spines under compressive follower loads in vitro. This study suggests that the rib cage should be included when testing a cadaveric thoracic spine with a follower load to optimize clinical relevance.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.019
      Issue No: Vol. 84 (2018)
       
  • Time-elapsed synchrotron-light microstructural imaging of femoral neck
           fracture
    • Authors: Saulo Martelli; Egon Perilli
      Pages: 265 - 272
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Saulo Martelli, Egon Perilli
      Time-elapsed micro-computed-tomography (μCT) imaging allows studying bone micromechanics. However, no study has yet performed time-elapsed μCT imaging of human femoral neck fractures. We developed a protocol for time-elapsed synchrotron μCT imaging of the microstructure in the entire proximal femur, while inducing clinically-relevant femoral neck fractures. Three human cadaver femora (females, age: 75–80 years) were used. The specimen-specific force to be applied at each load step was based on the specimens’ strength estimated a priori using finite-element analysis of clinical CT images. A radio-transparent compressive stage was designed for loading the specimens while recording the applied load during synchrotron μCT scanning. The total μCT scanning field of view was 146 mm wide and 131 mm high, at 29.81 µm isotropic pixel size. Specimens were first scanned unloaded, then under incremental load steps, each equal to 25% of the estimated specimens’ strength, and ultimately after fracture. Fracture occurred after 4–5 time-elapsed load steps, displaying sub-capital fracturing of the femoral neck, in agreement with finite-element predictions. Time-elapsed μCT images, co-registered to those of the intact specimen, displayed the proximal femur microstructure under progressive deformation up to fracture. The images showed (1) a spatially heterogeneous deformation localized in the proximal femoral head; (2) a predominantly elastic recovery, after load removal, of the diaphyseal and trochanteric regions and; (3) post-fracture residual displacements, mainly localized in the fractured region. The time-elapsed μCT imaging protocol developed and the high resolution images generated, made publicly available, may spur further research into human femur micromechanics and fracture.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.016
      Issue No: Vol. 84 (2018)
       
  • A comparative analysis of the avian skull: Woodpeckers and chickens
    • Authors: Jae-Young Jung; Andrei Pissarenko; Nicholas A. Yaraghi; Steven E. Naleway; David Kisailus; Marc A. Meyers; Joanna McKittrick
      Pages: 273 - 280
      Abstract: Publication date: August 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 84
      Author(s): Jae-Young Jung, Andrei Pissarenko, Nicholas A. Yaraghi, Steven E. Naleway, David Kisailus, Marc A. Meyers, Joanna McKittrick
      Woodpeckers peck at trees without any reported brain injury despite undergoing high impact loads. Amongst the adaptations allowing this is a highly functionalized impact-absorption system consisting of the head, beak, tongue and hyoid bone. This study aims to examine the anatomical structure, composition, and mechanical properties of the skull to determine its potential role in energy absorption and dissipation. An acorn woodpecker and a domestic chicken are compared through micro-computed tomography to analyze and compare two- and three-dimensional bone morphometry. Optical and scanning electron microscopy with energy dispersive X-ray spectroscopy are used to identify the structural and chemical components. Nanoindentation reveals mechanical properties along the transverse cross-section, normal to the direction of impact. Results show two different strategies: the skull bone of the woodpecker shows a relatively small but uniform level of closed porosity, a higher degree of mineralization, and a higher cortical to skull bone ratio. Conversely, the chicken skull bone shows a wide range of both open and closed porosity (volume fraction), a lower degree of mineralization, and a lower cortical to skull bone ratio. This structural difference affects the mechanical properties: the skull bones of woodpeckers are slightly stiffer than those of chickens. Furthermore, the Young's modulus of the woodpecker frontal bone is significantly higher than that of the parietal bone. These new findings may be useful to potential engineered design applications, as well as future work to understand how woodpeckers avoid brain injury.

      PubDate: 2018-05-29T10:15:06Z
      DOI: 10.1016/j.jmbbm.2018.05.001
      Issue No: Vol. 84 (2018)
       
  • Mechanical alterations of the bone-cartilage unit in a rabbit model of
           early osteoarthrosis
    • Authors: Sarah Pragnère; Caroline Boulocher; Ophélie Pollet; Catherine Bosser; Aurélie Levillain; Magali Cruel; Thierry Hoc
      Pages: 1 - 8
      Abstract: Publication date: July 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 83
      Author(s): Sarah Pragnère, Caroline Boulocher, Ophélie Pollet, Catherine Bosser, Aurélie Levillain, Magali Cruel, Thierry Hoc
      Objective The purpose of this study was to assess mechanical properties along with microstructural modifications of the hyaline cartilage (HC), calcified cartilage (CC) and cortical plate (Ct.Pt), in an anterior cruciate ligament transection (ACLT) model. Medial femoral condyles of six healthy rabbits (control group) and of six ACLT rabbits 6 weeks after OA induction were explanted. The zone of interest (ZOI) for all experiments was defined as the weight bearing areas of the samples. Biomechanical properties were measured using nanoindentation and morphological changes were evaluated using biphotonic confocal microscopy (BCM). Results All rabbits of the ACLT group displayed early PTOA. The results indicate an overall decrease in the mechanical properties of the HC, CC and Ct.Pt in the ACLT group. The average equilibrium modulus and elastic fraction of the HC decreased by 42% and 35%, respectively, compared with control group. The elastic moduli of the CC and Ct.Pt decreased by 37% and 16%, respectively, compared with control group. A stiffness gradient between CC and Ct.Pt appeared in the ACLT group. The irregularity of the cement line, quantified by its tortuosity in BCM images, was accentuated in the ACLT group compared with the control group. Conclusions In the ACLT model, weight-bearing stress was modified in the ZOI. This disruption of the stress pattern induced alterations of the tissues composing the bone-cartilage unit. In term of mechanical properties, all tissues exhibited changes. The most affected tissue was the most superficial: hyaline cartilage displayed the strongest relative decrease (42%) followed by calcified cartilage (37%) and cortical plate was slightly modified (16%). This supports the hypotheses that PTOA initiates in the hyaline cartilage.

      PubDate: 2018-04-16T11:21:48Z
      DOI: 10.1016/j.jmbbm.2018.03.033
      Issue No: Vol. 83 (2018)
       
  • Material properties of ultra-high molecular weight polyethylene:
           Comparison of tension, compression, nanomechanics and microstructure
           across clinical formulations
    • Authors: Louis G. Malito; Sofia Arevalo; Adam Kozak; Stephen Spiegelberg; Anuj Bellare; Lisa Pruitt
      Pages: 9 - 19
      Abstract: Publication date: July 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 83
      Author(s): Louis G. Malito, Sofia Arevalo, Adam Kozak, Stephen Spiegelberg, Anuj Bellare, Lisa Pruitt
      This is the first study to simultaneously measure material properties in tension, compression, nanoindentation as well as microstructure (crystallinity and lamellar level properties) across a wide variety of clinically relevant ultra-high molecular weight polyethylene (UHMWPE) formulations. Methodologies for the measurement of UHMWPE mechanical properties—namely elastic modulus, yield stress, yield strain, ultimate strength, energetic toughness, Poisson's ratio, hardness and constitutive variables—are evaluated. Engineering stress-strain behavior is compared to true stress-strain behavior for UHMWPE across a range of cross-linking and antioxidant chemistry. The tensile mechanical properties and constitutive behavior of UHMWPE are affected by resin type, antioxidant source and degree of cross-linking. Poisson's ratio is shown to be affected by resin type, antioxidant addition, and cross-linking dosage. Relationships between bulk mechanical properties from different measurement methodologies as well as microstructure are analyzed across all material formulations using Spearman rank correlation coefficients. Modulus and yield strength correlate in both tension and compression. Similarly, tensile and compressive properties including modulus and yield strength correlate strongly with crystallinity (X c ) and lamellar thickness (D). This work has broad application and provides a basis for interpreting the mechanical behavior of UHMWPE used in orthopedic implants.

      PubDate: 2018-04-16T11:21:48Z
      DOI: 10.1016/j.jmbbm.2018.03.029
      Issue No: Vol. 83 (2018)
       
  • Packing of muscles in the rabbit shank influences three-dimensional
           architecture of M. soleus
    • Authors: Carolin Wick; Markus Böl; Florian Müller; Reinhard Blickhan; Tobias Siebert
      Pages: 20 - 27
      Abstract: Publication date: July 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 83
      Author(s): Carolin Wick, Markus Böl, Florian Müller, Reinhard Blickhan, Tobias Siebert
      Isolated and packed muscles (e.g. in the calf) exhibit different three-dimensional muscle shapes. In packed muscles, cross-sections are more angular compared to the more elliptical ones in isolated muscles. As far as we know, it has not been examined yet, whether the shape of the muscle in its packed condition influences its internal arrangement of muscle fascicles and accordingly the contraction behavior in comparison to the isolated condition. To evaluate the impact of muscle packing, we examined the three-dimensional muscle architecture of isolated and packed rabbit M. soleus for different ankle angles (65°, 75°, 85°, 90°, and 95°) using manual digitization (MicroScribe® MLX). In general, significantly increased values of pennation angle and fascicle curvature were found in packed compared to isolated M. soleus (except for fascicle curvature at 90° ankle angle). On average, fascicle length of isolated muscles exceeded fascicle lengths of packed muscles by 2.6%. Reduction of pennation angle in the packed condition had only marginal influence on force generation (about 1% of maximum isometric force) in longitudinal direction (along the line of action) although an increase of transversal force component (perpendicular to the line of action) of about 26% is expected. Results of this study provide initial evidence that muscle packing limits maximum muscle performance observed in isolated M. soleus. Besides an enhanced understanding of the impact of muscle packing on architectural parameters, the outcomes of this study are essential for realistic three-dimensional muscle modeling and model validation.
      Graphical abstract image

      PubDate: 2018-04-16T11:21:48Z
      DOI: 10.1016/j.jmbbm.2018.04.006
      Issue No: Vol. 83 (2018)
       
  • Comparison of the mechanobiological performance of bone tissue scaffolds
           based on different unit cell geometries
    • Authors: Óscar L. Rodríguez-Montaño; Carlos Julio Cortés-Rodríguez; Antonio E. Uva; Michele Fiorentino; Michele Gattullo; Giuseppe Monno; Antonio Boccaccio
      Pages: 28 - 45
      Abstract: Publication date: July 2018
      Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 83
      Author(s): Óscar L. Rodríguez-Montaño, Carlos Julio Cortés-Rodríguez, Antonio E. Uva, Michele Fiorentino, Michele Gattullo, Giuseppe Monno, Antonio Boccaccio
      Enhancing the performance of scaffolds for bone regeneration requires a multidisciplinary approach involving competences in the fields of Biology, Medicine and Engineering. A number of studies have been conducted to investigate the influence of scaffolds design parameters on their mechanical and biological response. The possibilities offered by the additive manufacturing techniques to fabricate sophisticated and very complex microgeometries that until few years ago were just a geometrical abstraction, led many researchers to design scaffolds made from different unit cell geometries. The aim of this work is to find, based on mechanobiological criteria and for different load regimes, the optimal geometrical parameters of scaffolds made from beam-based repeating unit cells, namely, truncated cuboctahedron, truncated cube, rhombic dodecahedron and diamond. The performance, -expressed in terms of percentage of the scaffold volume occupied by bone-, of the scaffolds based on these unit cells was compared with that of scaffolds based on other unit cell geometries such as: hexahedron and rhombicuboctahedron. A very intriguing behavior was predicted for the truncated cube unit cell that allows the formation of large amounts of bone for low load values and of very small amounts for the medium-high ones. For high values of load, scaffolds made from hexahedron unit cells were predicted to favor the formation of the largest amounts of bone. In a clinical context where medical solutions become more and more customized, this study offers a support to the surgeon in the choice of the best scaffold to be implanted in a patient-specific anatomic region.
      Graphical abstract image

      PubDate: 2018-04-16T11:21:48Z
      DOI: 10.1016/j.jmbbm.2018.04.008
      Issue No: Vol. 83 (2018)
       
 
 
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