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BIOTECHNOLOGY (227 journals)                  1 2 | Last

Showing 1 - 200 of 227 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
Advances in Bioscience and Biotechnology     Open Access   (Followers: 14)
Advances in Genetic Engineering & Biotechnology     Hybrid Journal   (Followers: 7)
African Journal of Biotechnology     Open Access   (Followers: 6)
Algal Research     Partially Free   (Followers: 9)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 69)
American Journal of Bioinformatics Research     Open Access   (Followers: 8)
American Journal of Polymer Science     Open Access   (Followers: 30)
Animal Biotechnology     Hybrid Journal   (Followers: 9)
Annales des Sciences Agronomiques     Full-text available via subscription  
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 42)
Applied Bioenergy     Open Access  
Applied Biosafety     Hybrid Journal  
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 62)
Applied Mycology and Biotechnology     Full-text available via subscription   (Followers: 5)
Arthroplasty Today     Open Access   (Followers: 1)
Artificial Cells, Nanomedicine and Biotechnology     Hybrid Journal   (Followers: 2)
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: 4)
Bio-Algorithms and Med-Systems     Hybrid Journal   (Followers: 1)
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: 5)
Biological Cybernetics     Hybrid Journal   (Followers: 10)
Biomarkers and Genomic Medicine     Open Access   (Followers: 5)
Biomarkers in Drug Development     Partially Free   (Followers: 1)
Biomaterials Research     Open Access   (Followers: 4)
BioMed Research International     Open Access   (Followers: 6)
Biomédica     Open Access  
Biomedical Engineering Research     Open Access   (Followers: 7)
Biomedical glasses     Open Access  
Biomedical Reports     Full-text available via subscription  
BioMedicine     Open Access  
Bioprinting     Hybrid Journal  
Bioresource Technology Reports     Hybrid Journal  
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 22)
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: 6)
Biotechnology & Biotechnological Equipment     Open Access   (Followers: 5)
Biotechnology Advances     Hybrid Journal   (Followers: 33)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 160)
Biotechnology and Bioprocess Engineering     Hybrid Journal   (Followers: 6)
Biotechnology and Genetic Engineering Reviews     Hybrid Journal   (Followers: 14)
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: 7)
Biotechnology for Biofuels     Open Access   (Followers: 10)
Biotechnology Frontier     Open Access   (Followers: 2)
Biotechnology Journal     Hybrid Journal   (Followers: 15)
Biotechnology Law Report     Hybrid Journal   (Followers: 4)
Biotechnology Letters     Hybrid Journal   (Followers: 33)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Biotechnology Reports     Open Access  
Biotechnology Research International     Open Access   (Followers: 2)
Biotechnology Techniques     Hybrid Journal   (Followers: 10)
Biotecnología Aplicada     Open Access  
Biotribology     Hybrid Journal  
BMC Biotechnology     Open Access   (Followers: 15)
Chinese Journal of Agricultural Biotechnology     Full-text available via subscription   (Followers: 3)
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: 3)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biotechnology     Hybrid Journal   (Followers: 20)
Crop Breeding and Applied Biotechnology     Open Access   (Followers: 4)
Current Bionanotechnology     Hybrid Journal  
Current Biotechnology     Hybrid Journal   (Followers: 3)
Current Opinion in Biomedical Engineering     Hybrid Journal   (Followers: 1)
Current Opinion in Biotechnology     Hybrid Journal   (Followers: 55)
Current Pharmaceutical Biotechnology     Hybrid Journal   (Followers: 9)
Current Research in Bioinformatics     Open Access   (Followers: 14)
Current trends in Biotechnology and Pharmacy     Open Access   (Followers: 9)
EBioMedicine     Open Access  
Electronic Journal of Biotechnology     Open Access   (Followers: 1)
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: 12)
Food Science and Biotechnology     Hybrid Journal   (Followers: 9)
Frontiers in Bioengineering and Biotechnology     Open Access   (Followers: 6)
Frontiers in Systems Biology     Open Access   (Followers: 2)
Fungal Biology and Biotechnology     Open Access   (Followers: 1)
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: 1)
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: 15)
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: 2)
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: 6)
Journal of Applied Biomedicine     Open Access   (Followers: 3)
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 Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
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: 7)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 3)
Journal of Experimental Biology     Full-text available via subscription   (Followers: 25)
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 Microbiology and Biotechnology     Full-text available via subscription   (Followers: 14)
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: 2)
Journal of Organic and Biomolecular Simulations     Open Access  
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 6)
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: 5)
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: 16)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 3)
Nanobiomedicine     Open Access  
Nanobiotechnology     Hybrid Journal   (Followers: 3)
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: 521)
Network Modeling and Analysis in Health Informatics and Bioinformatics     Hybrid Journal   (Followers: 3)
New Biotechnology     Hybrid Journal   (Followers: 4)
Nigerian Journal of Biotechnology     Open Access  
Nova Biotechnologica et Chimica     Open Access  
NPG Asia Materials     Open Access  
npj Biofilms and Microbiomes     Open Access  
OA Biotechnology     Open Access  
Plant Biotechnology Journal     Open Access   (Followers: 10)
Plant Biotechnology Reports     Hybrid Journal   (Followers: 4)
Preparative Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)

        1 2 | Last

Journal Cover Biotribology
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 2352-5738
   Published by Elsevier Homepage  [3177 journals]
  • Friction measurements with yoghurt in a simulated tongue-palate contact
    • Authors: S. Tsui; J. Tandy; C. Myant; M. Masen; P.M. Cann
      Pages: 1 - 11
      Abstract: Publication date: December 2016
      Source:Biotribology, Volume 8
      Author(s): S. Tsui, J. Tandy, C. Myant, M. Masen, P.M. Cann
      The perception of many food attributes is related to mechanical stimulation and friction experienced in the tongue-palate contact during mastication. Friction in the tongue-palate is determined by the changing film properties (composition, component distribution, thickness) in the conjunction. We suggest this evolution is essentially determined by tongue-palate film loss rather than shear flow entrainment which predominates in conventional bearing lubrication. The paper reports friction measurements in a simulated tongue-palate contact for a range of high and low fat dairy foods. A reciprocating, sliding contact with restricted stroke length (<contact width) was used; under these conditions there is negligible shear-entrainment of fluid from outside the contact area. The tongue-palate contact was simulated by a PDMS ball and glass surface. The effect of hydrophobic and hydrophilic surfaces on friction was investigated for different fat contents (0, 4.2, 9.5%wt fat). Friction was measured over 60s of rubbing. Significant differences were observed in the friction change with time for different fat contents (μ 9.5<μ 4.2<μ 0wt%) and for different surface energy conditions (μ hydrophilic<μ hydrophobic). Post-test visualisation of the rubbed films showed that low friction coefficient was associated with the formation of a thin oil film on deposited particulate solids.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.02.001
      Issue No: Vol. 8 (2018)
  • Multi-physics modelling and experimental validation of electrovibration
           based haptic devices
    • Authors: Teja Vodlak; Zlatko Vidrih; Eric Vezzoli; Betty Lemaire-Semail; Djordje Peric
      Pages: 12 - 25
      Abstract: Publication date: December 2016
      Source:Biotribology, Volume 8
      Author(s): Teja Vodlak, Zlatko Vidrih, Eric Vezzoli, Betty Lemaire-Semail, Djordje Peric
      Electrovibration tactile displays exploit the polarisation of the finger pad, caused by an insulated high voltage supplied plate. This results in electrostatic attraction, which can be used to modulate the users' perception of an essentially flat surface and induce texture sensation. Two analytical models of electrovibration, based on parallel plate capacitor assumption, are demonstrably taken and assessed by comparisons with experimental results published in literature. In addition, an experimental setup was developed to measure the electrostatic force between the finger pad and a high voltage supplied plate in a static and out-of-contact state in order to support the use of parallel plate capacitor model. Development, validation, and application of a computational framework for modelling tactile scenarios on real and virtual surfaces rendered by electrovibration technique is presented. The framework incorporates fully parametric model in terms of materials and geometry of the finger pad, virtual and real surfaces, and can serve as a tool for virtual prototyping and haptic rendering in electrovibration tactile displays. This is achieved by controlling the applied voltage signal in order to guarantee similar lateral force cues in real and simulated surfaces.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.09.001
      Issue No: Vol. 8 (2018)
  • Mesenchymal Stem Cells Enhance Lubrication of Engineered Meniscus Through
           Lubricin Localization in Collagen Gels
    • Authors: Edward D. Bonnevie; Mary Clare McCorry; Lawrence J. Bonassar
      Pages: 26 - 32
      Abstract: Publication date: December 2016
      Source:Biotribology, Volume 8
      Author(s): Edward D. Bonnevie, Mary Clare McCorry, Lawrence J. Bonassar
      This study evaluated the role of cell source in the boundary lubrication of engineered meniscus tissue. To accomplish this, both primary meniscal fibrochondrocytes (FCC) and bone marrow-derived mesenchymal stem cells (MSC) were obtained from neonatal bovine, seeded in high density collagen gels (20mg/mL collagen with 25×106 totalcells/mL) at various MSC:FCC ratios, and cultured for two weeks. After culture, the boundary friction coefficient, mechanical properties, surface roughness, and lubricin localization were all evaluated for engineered constructs. A strong correlation between MSC content and boundary friction coefficient was found (R2 =0.948). Aggregate modulus, permeability, and surface roughness revealed insignificant trends with MSC content; however, lubricin localization was highly correlated with increasing MSC content (R2 =0.902). Similarly, boundary friction coefficient had no significant trends with modulus, permeability, or roughness, but lubricin localization was significantly correlated with the boundary friction coefficient (R2 =0.800). Collectively, these data revealed a structure-function relationship in meniscus tissue engineering that is dictated by cell source. Specifically, the connection between MSC content, lubricin localization, and boundary friction coefficient reveal a method through which tuning the lubricating properties of engineered tissue is possible.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.11.001
      Issue No: Vol. 8 (2018)
  • Tribological behavior of hydrogenated diamond-like carbon on polished
           alumina substrate with chromium interlayer for biomedical application
    • Authors: Ay Ching Hee; Yue Zhao; Dipankar Choudhury; Subir Ghosh; Qiang Zhu; Hongtao Zhu
      Pages: 1 - 10
      Abstract: Publication date: September 2016
      Source:Biotribology, Volume 7
      Author(s): Ay Ching Hee, Yue Zhao, Dipankar Choudhury, Subir Ghosh, Qiang Zhu, Hongtao Zhu
      Diamond-like carbon (DLC) is a promising material for wear resistant films because of its high hardness and moderate elastic modulus. To enhance its performance in orthopedic implant applications, a better understanding of the tribological effect of DLC coating is essential. DLC with hydrogen, that is: hydrogenated amorphous carbon (a-C:H) was deposited on the polished alumina (Al2O3) substrate by magnetron sputtering. X-ray diffraction, energy dispersive spectroscopy and transmission electron microscopy were used to determine the phase compositions in the films. The a-C:H coated surface exhibits hydrophilic characteristic for protein absorption, with low water contact angles of 69.5°. It was found that the a-C:H, which has high hardness and moderate elastic modulus resulted in a relatively high H/E ratio of around 0.133. This result enables the film to conform well with the substrate and provide good wear resistance. The tribology test showed a significant reduction in the friction coefficient of the coated layer as compared to the uncoated surface rubbing on the Al2O3 counterface. The a-C:H coated pin against a-C:H coated block showed a stable and low friction coefficient under all loading conditions.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.06.001
      Issue No: Vol. 7 (2018)
  • Evaluation of catheter-induced tribological damage to porcine aorta using
           infra-red spectroscopy
    • Authors: Kiran H.J. Dellimore; Arjan J.G. Mank; Jacek Wojnowski; Christopher Noble; Steven E. Franklin
      Pages: 11 - 21
      Abstract: Publication date: September 2016
      Source:Biotribology, Volume 7
      Author(s): Kiran H.J. Dellimore, Arjan J.G. Mank, Jacek Wojnowski, Christopher Noble, Steven E. Franklin
      Studies were carried out to assess the potential of attenuated total internal reflection Fourier transform infrared (ATR)-FTIR spectroscopy as a tool for evaluating mechanical-tribological damage to the blood vessel wall occurring during simulated endovascular catheterization on fresh ex-vivo porcine aortic tissue. It is envisaged that this method could be used in laboratory tests to quantitatively compare catheters or catheterization approaches with regard to their effect on damage to the aorta wall. Tribological damage was induced on the tissue. Obvious changes were visible in the FTIR spectra as well as the friction coefficient as a function of increasing damage. In particular, the spectral changes due to damage to the outermost layer of the tissue were significant, provided appropriate sample conditioning was performed. These changes, which correlated with a reduction in friction coefficient, can be attributed to the removal of successive layers of tissue as a result of a wear process. In conclusion, FTIR spectroscopy was found to be a reliable and effective measurement technique for quantifying catheter-induced tissue damage, allowing very repeatable spectra to be obtained from the tissue up to 36h after excision with no major spectral changes observed during this time frame due to tissue age.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.07.002
      Issue No: Vol. 7 (2018)
  • The effect of engineered surface topography on the tribology of CFR-PEEK
           for novel hip implant materials
    • Authors: Hayley Wyatt; Marc Elliott; Paul Revill; Alastair Clarke
      Pages: 22 - 30
      Abstract: Publication date: September 2016
      Source:Biotribology, Volume 7
      Author(s): Hayley Wyatt, Marc Elliott, Paul Revill, Alastair Clarke
      Carbon-fibre-reinforced polyether ether ketone (CFR PEEK) has the potential to improve the wear resistance of orthopaedic implants and its performance can be further enhanced by surface texturing. This scoping study investigates the effects of surface textures on the friction behaviour of CFR PEEK, using screening testing to identify textures suitable for development for acetabular cup applications. Six surface textures were designed and applied to CFR PEEK discs using laser surface texturing, with the dimple diameter and area coverage being varied. These textures were tested using pin on disc testing, with a cobalt chrome pin representing the femoral head. Coefficient of friction and surface characterisation were used to assess the performance of each texture. The results from the study demonstrated that all textures reduced the coefficient of friction compared to the plain material. The variation in the performance of the different textures highlighted a need for optimum texture characteristics to be found. 150μm circular dimples, spaced 175–200μm apart with an area coverage of 10–15% gave the best performance in saline lubrication at a contact pressure of 2MPa and sliding speed of 50mm/s. Tests should be repeated in a proteinaceous testing medium at various contact pressures and speeds.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.08.001
      Issue No: Vol. 7 (2018)
  • Correlation between signalment and the biphasic hyperelastic mechanical
           properties of equine articular cartilage
    • Authors: Hyeon Lee; William D. Campbell; Margaret E. Canning; Kelcie M. Theis; Hannah Y. Ennis; Robert L. Jackson; James C. Wright; R. Reid Hanson
      Pages: 31 - 37
      Abstract: Publication date: September 2016
      Source:Biotribology, Volume 7
      Author(s): Hyeon Lee, William D. Campbell, Margaret E. Canning, Kelcie M. Theis, Hannah Y. Ennis, Robert L. Jackson, James C. Wright, R. Reid Hanson
      The correlation between mechanical properties from the equine articular cartilage and signalment was investigated. Fresh articular cartilage of fetlock, carpus, and stifle were harvested from 12 deceased horses with information on the breed, age, sex, and weight within 4h of euthanasia for measurements. Seven indentation tests at different normalized displacements of 10, 20, 30, 35, 40, 45, and 50% of the cartilage thickness were performed with a spherical probe indenting at 0.1mm/s velocity. The solid matrix of the cartilage was found to follow a hyper-elastic material behavior defined by Ogden; the solid phase aggregate modulus (E a), hyperelastic material constant (α), and fluid load fraction (F′) of the cartilage were characterized. The characterized material properties were statistically analyzed using a mixed model ANOVA and Scheffe's test to check the correlation between the properties and signalment variables (breed, age, sex, and weight). There were correlations between both the solid phase aggregate modulus and age (p <0.0392) and weight (p <0.0375). The fluid load fraction also correlated with both age (p <0.0146) and weight (p <0.0003). Breed and sex were not statistically significant variables affecting the variation of theses material properties. No statistically significant correlations between the hyperelastic material constant and the signalment variables were observed.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.07.001
      Issue No: Vol. 7 (2018)
  • Increasing of functionality of c.p. titanium/UHMWPE tribo-pairs by
           thermodiffusion nitriding of titanium component
    • Authors: I.M. Pohrelyuk; S.E. Sheykin; S.M. Dub; A.G. Mamalis; I.Yu. Rostotskii; O.V. Tkachuk; S.M. Lavrys
      Pages: 38 - 45
      Abstract: Publication date: September 2016
      Source:Biotribology, Volume 7
      Author(s): I.M. Pohrelyuk, S.E. Sheykin, S.M. Dub, A.G. Mamalis, I.Yu. Rostotskii, O.V. Tkachuk, S.M. Lavrys
      The tribological characteristics of GRADE 2 commercially pure titanium-ultrahigh molecular weight polyethylene (UHMWPE) medical friction pairs in artificial hip-joints, the titanium working surface of which has been modified by thermodiffusion nitriding to ensure its service ability, have been studied. The efficiency of this pair is mainly related to the fact that, pure titanium, practically, is a material biocompatible with human body tissues. It has been shown that, the use of a step-by-step regime of nitriding, with subsequent polishing of the nitrided GRADE 2 titanium surface for surface hardening, decreases the wear of the UHMWPE component by a factor of more than two orders of magnitude and the friction coefficient by a factor of 6. In this case, the service efficiency of the nitrided GRADE 2 commercially pure titanium-UHMWPE tribo-component is at the level of the ZrO2 zirconium ceramics, which exceeds the traditionally used in endoprosthetics the CoCrMo-UHMWPE and stainless steel-UHMWPE pairs.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.08.002
      Issue No: Vol. 7 (2018)
  • A tribological approach to understand the behavior of oral-care silica
           during tooth brushing
    • Authors: M. Popa; F. Peditto; L. Guy; A.-M. Sfarghiu; Y. Berthier; S. Descartes
      Pages: 1 - 11
      Abstract: Publication date: June 2016
      Source:Biotribology, Volume 6
      Author(s): M. Popa, F. Peditto, L. Guy, A.-M. Sfarghiu, Y. Berthier, S. Descartes
      This study focuses on the tribological behavior of oral care silica on the acquired enamel pellicle reproduced ex vivo. The work presents a simplified biomimetic model of the protein coated enamel. It highlights the complexity of toothbrushing mechanisms and helps to understand them. Toothbrushing reciprocating-motion tests were performed with a custom-made tribometer allowing an in situ visualization of glass samples (functionalized with a protein layer or not), toothbrush, and silica-based slurry. Samples were analyzed by correlating ESEM imaging and AFM in tapping mode measurements, adopting the third body approach. Third body behavior was correlated with the evolution of the friction coefficient, in order to establish the velocity accommodation mechanisms. The possible modifications/damages of the biomimetic enamel pellicle are identified and described.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.03.001
      Issue No: Vol. 6 (2018)
  • Cationic astringents alter the tribological and rheological properties of
           human saliva and salivary mucin solutions
    • Authors: Max Biegler; Judith Delius; Benjamin T. Käsdorf; Thomas Hofmann; Oliver Lieleg
      Pages: 12 - 20
      Abstract: Publication date: June 2016
      Source:Biotribology, Volume 6
      Author(s): Max Biegler, Judith Delius, Benjamin T. Käsdorf, Thomas Hofmann, Oliver Lieleg
      Oral astringency, typically described as a dry, puckering perception, arises upon ingestion of cationic or polyphenolic compounds. Although understanding the origin of this astringency sensation would be important for the gustatory optimization of food and beverages, the molecular mechanism remains to date unclear. This is in part due to the limited amount of experimental data on the interaction of cationic astringents with salivary proteins. We here demonstrate that different cationic astringents entail a loss in saliva lubricity which we quantify with rotational tribology. Since saliva lubricity is governed by mucin glycoproteins, purified salivary mucin solutions reproduce this behavior very well. We show that the loss of lubricity of salivary mucin solutions results from mucin aggregation which we quantify by HPLC-UV. Our results demonstrate that purified salivary mucins constitute a suitable model system for studying the molecular mechanisms governing alterations in the lubricity of native saliva as e.g. induced by astringents.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.03.002
      Issue No: Vol. 6 (2018)
  • Influence of the relative humidity and the temperature on the in-vivo
           friction behaviour of human skin
    • Authors: M. Klaassen; D.J. Schipper; M.A. Masen
      Pages: 21 - 28
      Abstract: Publication date: June 2016
      Source:Biotribology, Volume 6
      Author(s): M. Klaassen, D.J. Schipper, M.A. Masen
      Both temperature and relative humidity are known to influence the frictional behaviour of human skin. However, literature does not completely cover to what extent both parameters play a role. Measurements were conducted using an in-house built reciprocating tribometer inside an enclosure in which both the humidity and the temperature can be controlled independently. Friction measurements were performed in varying climates ranging from 25°C and 40% RH to 37°C and 80% RH at respectively 3°C and 10% RH intervals. Using the obtained results a ‘friction map’ was created which shows that the coefficient of friction increases by a factor of two when the environment is changed from ‘cold and dry’ to ‘warm and moist’. A statistical analysis shows that the product of the temperature and relative humidity appears to be the driving factor describing the observed frictional behaviour. Results indeed show a more pronounced effect of either parameter at the warmer, moister conditions, in contrast to the colder, drier conditions where a smaller effect on the coefficient of friction is observed. The findings will be of importance, e.g. for bedridden patients who are prone to pressure ulcer development as it indicates the importance of maintaining a healthy microclimate.

      PubDate: 2018-01-05T18:34:43Z
      DOI: 10.1016/j.biotri.2016.03.003
      Issue No: Vol. 6 (2018)
  • Normal Load Scaling of Friction in Gemini Hydrogels
    • Authors: Juan Manuel Urueña; Eric O. McGhee; Thomas E. Angelini; Duncan Dowson; W. Gregory Sawyer; Angela A. Pitenis
      Pages: 30 - 35
      Abstract: Publication date: March 2018
      Source:Biotribology, Volume 13
      Author(s): Juan Manuel Urueña, Eric O. McGhee, Thomas E. Angelini, Duncan Dowson, W. Gregory Sawyer, Angela A. Pitenis
      Health and physiology are critically dependent on the ability of soft, permeable, and aqueous materials (e.g. cartilage, cells, and extracellular matrix) to provide lubrication over a wide range of speeds and contact stresses. Living cells and tissues present tremendous handling and experimental challenges for fundamental biotribology studies. Synthetic high water content hydrogels, designed to share similar mechanical and transport properties of biomaterials, can provide fundamental insights into the basic dissipative mechanisms associated with aqueous lubrication. Recent studies investigating the response of self-mated (Gemini) hydrogels to a wide range of sliding speeds under constant load conditions revealed transitions in friction behavior that may be associated with polymer relaxation time and contact time for a surface mesh during sliding (mesh size divided by the sliding speed). Here, the extent to which contact pressure and contact area affect hydrogel friction behavior was explored by changing the applied load over two orders of magnitude (0.1–20 mN) and the sliding speed over four orders of magnitude (10 μm/s–100 mm/s). Oscillating pin-on-disk microtribological experiments were performed in ultrapure water for Gemini polyacrylamide hydrogels (average mesh size ~7 nm). Friction coefficient decreased across all ranges of sliding speed with increasing applied load, consistent with predictions of contact area scaling non-linearly with applied load and pressure-independent surface shear stresses. The contact area for Gemini hydrogel interfaces under these conditions has been shown to follow Hertzian contact mechanics theory, and supports the scaling of friction coefficient in the speed-independent regime that follows μ ~ F n −1/3.

      PubDate: 2018-02-07T07:58:23Z
      DOI: 10.1016/j.biotri.2018.01.002
      Issue No: Vol. 13 (2018)
  • Shoulder Simulator Wear Test of Five Contemporary Total Shoulder
           Prostheses With Three Axes of Rotation and Sliding Motion
    • Authors: Simon L. Smith; Emma Kennard; Thomas J. Joyce
      Pages: 36 - 41
      Abstract: Publication date: March 2018
      Source:Biotribology, Volume 13
      Author(s): Simon L. Smith, Emma Kennard, Thomas J. Joyce
      Shoulder joint replacement generally utilizes ultra-high molecular weight polyethylene (UHMWPE) as a bearing surface. Long term survival of such implants is recognized to be limited by wear of the UHMWPE. Commercially available JRI 42 mm diameter VAIOS Total shoulders were wear tested in diluted bovine serum for five million cycles in a unique Shoulder Wear Simulator. Five Total shoulders were subject to rotational and translational motion, and loading, to replicate the “Mug to Mouth” activity of daily living. A sixth Total shoulder was subject to loading only in a control station. Wear was measured gravimetrically and surface roughness was measured with a non-contacting profilometer. Mean wear rate of the UHMWPE components was 21.5 ± 5.4 mm3/million cycles. The humeral heads roughened, from 19 ± 3 nm Sa to 43 ± 13 nm Sa over the five million cycles of the test, while the UHMWPE glenoid components became smoother, from 959 ± 230 nm Sa to 77 ± 17 nm Sa. This is the first reported wear test of multiple samples of a commercially available Total shoulder in a dedicated shoulder simulator.

      PubDate: 2018-02-07T07:58:23Z
      DOI: 10.1016/j.biotri.2018.01.001
      Issue No: Vol. 13 (2018)
  • Tribological Analysis of UHMWPE Tibial Implants in Unicompartmental Knee
           Replacements: From Retrieved to In Vitro Studies
    • Authors: M.M. Sava; B. Munteanu; E. Renault; Y. Berthier; A.M. Trunfio-Sfarghiu
      Pages: 1 - 15
      Abstract: Publication date: March 2018
      Source:Biotribology, Volume 13
      Author(s): M.M. Sava, B. Munteanu, E. Renault, Y. Berthier, A.M. Trunfio-Sfarghiu
      This study focuses on the identification of velocity accommodation mechanisms of UHMWPE tibial implants from unicompartmental knee replacements. A tribological analysis of two retrieved medial unicompartmental knee implants was performed. The first implant presented a high wear rate at 7years follow-up with the velocity accommodation mechanisms characterized by the formation of a plasticized thin and smooth 3rd body layer which was drawn until small UHMWPE particles were detached. The second implant presented good performances at 11years follow-up with a lower wear rate, with the velocity accommodation mechanisms characterized by the formation of a discontinuous 3rd body layer composed of small UHMWPE wear particles and biological molecules from synovial fluid. An important finding of the tribological analysis of the two retrieved UHMWPE tibial implants is that the 3rd body layer plays a key role in the wear rates, influencing the velocity accommodation mechanisms. An in vitro study of two identical UHMWPE tibial implants using two lubricating solutions, with different compositions and structures (a calf serum and a Gel-IN calf serum) was performed to explain the root causes of the major difference between the 3rd body layers formed in vivo. It was observed that the calf serum led to a high friction factor, as the molecules were unable to bind to the UHMWPE surface. However, the Gel-IN calf serum led to a lower friction factor, with the formation of a 3rd body layer on the UHMWPE surface due to protein and lipid adsorption.

      PubDate: 2017-12-10T17:22:19Z
      DOI: 10.1016/j.biotri.2017.11.001
      Issue No: Vol. 13 (2017)
  • Biomechanical Evaluation of the Fatigue Performance, the Taper Corrosion
           and the Metal Ion Release of a Dual Taper Hip Prosthesis under
           Physiological Environmental Conditions
    • Authors: M. Baxmann; A.M. Pfaff; C. Schilling; T.M. Grupp; M.M. Morlock
      Pages: 1 - 7
      Abstract: Publication date: December 2017
      Source:Biotribology, Volume 12
      Author(s): M. Baxmann, A.M. Pfaff, C. Schilling, T.M. Grupp, M.M. Morlock
      Besides numerous advantages of dual taper hip prosthesis such as the intraoperative flexibility and the improved reconstruction of the patient anatomy, the additional neck-stem taper interface is vulnerable to mechanical failure, taper corrosion and release of metal ions. One modular short stem hip implant design was used to pre-clinically evaluate the risk of neck component fracture and metal debris produced at the taper connection in various loading conditions resembling in-vivo situations. Three different fluids were used (Ringer's solution, bovine serum and iron-chloride solution). The usage of bovine calf serum instead of Ringer's solution significantly decreased the endurance limit of the taper connection due to lubrication effects of proteins and other organic components in the contact between stem and neck adapter. The metal ion release increased with increasing chloride concentration and reduced pH-values in the testing fluids. The failures reported for several pre-clinically validated modular hip implant designs are an indicator that an expansion of the current testing procedures according to ISO and ASTM is required to reliably assess the performance of taper junctions prior to clinical use. The developed experimental two-stage testing method, using bovine serum and the adapted iron-chloride solution, is a promising approach to simulate the complex physiological environment in vitro.

      PubDate: 2017-09-10T06:01:14Z
      DOI: 10.1016/j.biotri.2017.07.002
      Issue No: Vol. 12 (2017)
  • In Situ Measurements of Contact Dynamics in Speed-dependent Hydrogel
    • Authors: Eric O. McGhee; Angela A. Pitenis; Juan Manuel Urueña; Kyle D. Schulze; Alexander J. McGhee; Christopher S. O'Bryan; Tapomoy Bhattacharjee; Thomas E. Angelini; W. Gregory Sawyer
      Abstract: Publication date: Available online 24 December 2017
      Author(s): Eric O. McGhee, Angela A. Pitenis, Juan Manuel Urueña, Kyle D. Schulze, Alexander J. McGhee, Christopher S. O'Bryan, Tapomoy Bhattacharjee, Thomas E. Angelini, W. Gregory Sawyer
      The friction behavior of soft, aqueous, biotribological contacts depends on contact geometry, speed, and pressure. Previous efforts to measure the surface profile of soft sliding contacts have been stymied by the matching index of refraction of aqueous materials submerged in water. Here, hydrogel surface deformations were imaged using confocal microscopy to experimentally investigate the contact geometry as a function of sliding speed. In situ fluorescence confocal microscopy measurements of the contact deformation during unidirectional friction experiments revealed the existence of a front/back asymmetry that increased with increasing sliding speed. A polyacrylamide hydrogel disk (96.5% water) was polymerized with fluorescent dyes and used as a rotating countersample below a polished glass hemispherical pin (1mm radius of curvature). All experiments were performed submerged in a dilute (0.7wt%) suspension of 1μm red fluorescent microspheres in ultrapure water. Imaging of the contact was performed using a confocal microscope in situ with unidirectional sliding at 0.1, 1, 10, and 100mm/s. The friction coefficient increased monotonically with increasing speed from μ~0.04 at 0.1mm/s to μ~0.20 at 100mm/s. All imaging was performed relative to the stationary glass probe under steady-state conditions. The contact line measured by connecting the leading and exiting contact points was nearly perpendicular to the loading direction at 0.1mm/s sliding speed, but distorted as sliding speed increased. Consistent with the theories of viscoelastic contributions to polymer friction, the tangent of the contact-line angle correlated with friction.

      PubDate: 2017-12-27T15:32:19Z
      DOI: 10.1016/j.biotri.2017.12.002
  • Wear Mechanisms Characterization Operating in Micro- and Nanoscale of the
           a-C:H Coating Implanted by Ag-Pt
    • Authors: M. Janusz; L. Major; M. Kot; M. Dyner; J.M. Lackner; B. Major
      Abstract: Publication date: Available online 21 December 2017
      Author(s): M. Janusz, L. Major, M. Kot, M. Dyner, J.M. Lackner, B. Major
      Wear mechanisms operating at the nanoscale may directly influence mechanical and biological properties of the advanced protective coatings used in industry. In the present research, the biomechanical properties of the advanced a-C:H coatings reinforced by different metallic crystallites have been characterized. The optimal biomechanical properties were found for the a-C:H implanted by AgPt crystallites. This coating has been selected for the detailed wear mechanism description at the nanoscale by transmission electron microscopy. Five zones of the coating deformation as a function of the distance from the centre of the maximum load during the wear process have been identified and described. Based on the bio-tribological properties, a-C:H coatings implanted by AgPt are the most promising for use in applications.
      Graphical abstract image

      PubDate: 2017-12-22T04:29:17Z
      DOI: 10.1016/j.biotri.2017.12.001
  • Cartilage and Joint Lubrication: New Insights Into the Role of
    • Authors: David L. Burris; Axel C. Moore
      Abstract: Publication date: Available online 8 September 2017
      Author(s): David L. Burris, Axel C. Moore
      Cartilage is slippery when hydrated but it loses hydration and lubricity during loading. However, dehydrated cartilage regains lubricity during high-speed sliding in the stationary contact area; this result is often interpreted as experimental evidence of fluid film lubrication based on theoretical predictions that pre-equilibrated cartilage remains equilibrated during sliding in this testing configuration. In-situ compression measurements were made during variable speed stationary contact area experiments with fully and partially equilibrated osteochondral cores under saline lubrication to test this prediction. Reduced friction coefficients during sliding following equilibration were accompanied by marked cartilage thickening (~160μm) indicative of interstitial fluid recovery; we call this sliding-induced recovery phenomenon tribological rehydration. During sliding near physiological speeds following equilibration, tribological rehydration gradually reduced friction coefficients and strains to values consistent with the response of fully-hydrated cartilage. The results suggest that the marked friction reductions observed during high-speed sliding following equilibration were likely consequences of interstitial fluid recovery rather than the formation of a hydrodynamic fluid film; they also suggest that hydrodynamic pressurization was the likely driving force underlying the tribological rehydration phenomenon. We propose that external hydrodynamic pressures in the convergent wedge near the leading edge of contact pushed fluid into the porous tissue to restore hydration, thickness, mechanical stiffness, and lubrication following periods of static exudation.

      PubDate: 2017-09-10T06:01:14Z
      DOI: 10.1016/j.biotri.2017.09.001
  • The 3rd International Conference on Biotribology (ICoBT) Imperial College
           London, 11-14th September 2016
    • Authors: Philippa Cann; Marc Masen
      Abstract: Publication date: Available online 5 September 2017
      Author(s): Philippa Cann, Marc Masen

      PubDate: 2017-09-10T06:01:14Z
      DOI: 10.1016/j.biotri.2017.08.001
  • New Non-invasive Techniques to Quantify Skin Surface Strain and
           Sub-surface Layer Deformation of Finger-pad during Sliding
    • Authors: X. Liu; R. Maiti; Z.H. Lu; M.J. Carré; S.J. Matcher; R. Lewis
      Abstract: Publication date: Available online 18 July 2017
      Author(s): X. Liu, R. Maiti, Z.H. Lu, M.J. Carré, S.J. Matcher, R. Lewis
      Studies on the variation of skin properties with gender, age and anatomical region, with regards to interaction with different materials have resulted in significant research output. Investigations on skin surface strain and sub-surface layer deformation during sliding, however, have not received as much attention. This novel study uses two non-invasive techniques, optical coherence tomography (OCT) and digital image correlation (DIC), to measure properties of the index finger of a 25year old female when under normal and shear loading. Measurements were taken during static, and for the first time, dynamic phases. It was observed that the number of ridges in contact with a Quartz glass surface, observed under OCT, reduced when the finger started sliding. The sliding also resulted in deformation at the stratum corneum junction. The surface strain, analysed using DIC was higher nearer to the distal interphalangeal joint compared to the fingertip. This newly developed approach provides a powerful and non-invasive method to study the structural changes of finger-pad skin during loading and sliding. This approach can now be repeated at different anatomical locations for medical, bioengineering and consumer applications.

      PubDate: 2017-07-24T08:28:30Z
      DOI: 10.1016/j.biotri.2017.07.001
  • Tribological and Mechanical Properties of Brazilian Hair
    • Authors: A. Elzubair; N.F. de Oliveira; F. Munhoz; C. Flor; F. Fiat; N. Baghdadli; S.S. Camargo; G.S. Luengo
      Abstract: Publication date: Available online 16 June 2017
      Author(s): A. Elzubair, N.F. de Oliveira, F. Munhoz, C. Flor, F. Fiat, N. Baghdadli, S.S. Camargo, G.S. Luengo
      Background The high Brazilian ethnical mixture combined with the country climate conditions make Brazilian hair an uncommon category that is still scarcely studied. Methods Brazilian hair of types II to V was investigated by nanoscratch and nanoindentation techniques. The results were statistically analyzed using ANOVA (p≤0.05 level) and statistical correlation between the measured parameters was studied by linear regression. Results Nanoscratch at low loads showed for hair types II and III a pronounced elastic recovery with little damage, while for types IV and V a more plastic and brittle behavior with higher friction in the direction from tip to root was observed. At high loads the tip reached the cortex and elastoplastic deformation, plowing, fracturing and chipping of cuticle cells occurred in all types. Quasi-static nanoindentation yielded average values H=0.22±0.06GPa and E=4.7±0.8GPa. Dynamic nanoindentation showed increasing H and E values when going from types II to V. Discussion The static H and E values of Brazilian hair are consistent with the high Brazilian ethnical mixture. Nanoscratch failure mechanisms can be explained based on the dynamic H and E values. The scratch resistance in the direction from root to tip is associated to the cuticle mechanical properties, but in the opposite direction increased mechanical property values lead to increased damage. The surface friction behavior is determined by roughness of the fibers, however, when the tip goes into the cortex friction decreases due to its softer nature.

      PubDate: 2017-06-19T22:52:42Z
      DOI: 10.1016/j.biotri.2017.06.001
  • Quantification of cartilage wear morphologies in unidirectional sliding
           experiments: Influence of different macromolecular lubricants
    • Authors: Kathrin Boettcher; Benjamin Winkeljann; Tannin A. Schmidt; Oliver Lieleg
      Abstract: Publication date: Available online 13 June 2017
      Author(s): Kathrin Boettcher, Benjamin Winkeljann, Tannin A. Schmidt, Oliver Lieleg
      Quantifying surface damage on articular cartilage after exposure of the tissue to extreme or prolonged mechanical stress is not only relevant for evaluating clinically relevant alterations, e.g. when the physiological lubrication mechanisms fail, but also useful for assessing the suitability of artificial cartilage replacement materials, implants or synovia-mimetic lubricants. Here, we establish a systematic quantification method for cartilage wear formation which is based on optical profilometry – a variant of confocal microscopy. With this approach, we compare three different macromolecular lubricants, i.e. solutions containing either hyaluronic acid, lubricin or porcine gastric mucin. Depending on the counter material used for tribological testing and the macromolecule used for lubrication, we detect different types of tissue damage which we quantify with suitable topographical parameters. In our setup, mucin solutions outperform the other two lubricants: when using mucin solutions for lubrication, we do not find any signs of topographical alterations on the cartilage surface. Our results underscore the supreme protective abilities of mucin solutions - even on biological surfaces where they do not occur physiologically.

      PubDate: 2017-06-14T19:47:02Z
      DOI: 10.1016/j.biotri.2017.06.002
  • Wear pattern on a retrieved Total Knee Replacement: The “fourth body
    • Authors: Charles Garabedian; Maxence Bigerelle; Denis Najjar; Henri Migaud
      Abstract: Publication date: Available online 29 May 2017
      Author(s): Charles Garabedian, Maxence Bigerelle, Denis Najjar, Henri Migaud
      Released debris in a replaced knee, such as bone loose, bone cement debris and metallic particles, are responsible for a third body abrasion of the Polyethylene (PE) mobile bearing superior surface and therefore compromise the Total Knee Replacement (TKR) implant longevity. To analyze the upstream and the downstream mechanisms of such abrasion mode, a set of randomized topographical measurements of the PE surface was performed. A Monte Carlo simulation demonstrated two periods of bead loosening from the porous coating. The released coating beads are then entrapped in the articulating interface. The relative motion between the PE insert and the Cobalt-Chromium (CoCr) femoral component and the load transmitting through the knee drive the bead to roll and to generate large scratches (mean width of 200μm) in the PE matrix. Once embedded, the beads are abraded by the upper metallic surface, releasing metallic debris tending to spread on the entire PE surface. These CoCr particles act in the PE wear as the coating beads at a smaller scale, as suggested by a fine scratching pattern (mean width of 30μm) and PE debris agglomerate generation. As a result, these metallic debris are responsible for a PE “fourth body abrasion”.
      Graphical abstract image

      PubDate: 2017-05-30T17:21:22Z
      DOI: 10.1016/j.biotri.2017.05.003
  • The static friction response of non-glabrous skin as a function of surface
           energy and environmental conditions
    • Authors: M. Klaassen; E.G. de Vries; M.A. Masen
      Abstract: Publication date: Available online 28 May 2017
      Author(s): M. Klaassen, E.G. de Vries, M.A. Masen
      The (local) environmental conditions have a significant effect on the interaction between skin and products. Plasticisation of the stratum corneum occurs at high humidity, causing this layer to soften and change its surface free energy. In this work we study the effects of the micro-climate on the frictional behaviour of skin in contact with materials with varying wettability. Friction measurements are performed under a range of micro-climate conditions using four different materials with a smooth surface finish. All measurements are performed twice on a single subject in order to minimise variation in skin properties. Results show that materials with a higher wettability show a larger increase in friction coefficient when exposed to warm, moist conditions. The friction force is modelled using the skin micro-relief, the elastic properties of the different skin layers, the surface chemistry of both skin and counter surface, and the environment, as input parameters.

      PubDate: 2017-05-30T17:21:22Z
      DOI: 10.1016/j.biotri.2017.05.004
  • Influence of molybdate ion and pH on the fretting corrosion of a CoCrMo
           – Titanium alloy couple
    • Authors: Johnny Dufils; Markus A. Wimmer; Joachim Kunze; Mathew T. Mathew; Michel P. Laurent
      Abstract: Publication date: Available online 16 May 2017
      Author(s): Johnny Dufils, Markus A. Wimmer, Joachim Kunze, Mathew T. Mathew, Michel P. Laurent
      Recent findings suggest that during wear CoCrMo alloys develop a protein-rich protective tribochemical film formed by interaction of released molybdate ion with proteins in the lubricant. The purpose of this study was to determine the effect of adding molybdate ions directly to the medium on the fretting corrosion of a high carbon CoCrMo alloy in contact with a Ti6Al4V alloy. We also examined the effect of lowered pH to simulate acidification that may occur in enclosed areas, as within a modular joint. High-carbon CoCrMo cylindrical pins underwent fretting (±50μm, 17N, 60MPa) against a Ti6Al4V rod in a flat-on-cylinder configuration in a custom-designed fretting corrosion set-up that included a standard three-electrode configuration for electrochemical measurements. Four electrolytes were used, consisting of diluted bovine serum (30g/L of proteins), with or without added sodium molybdate (32mM), and at pH4.5 or 7.6. All the tests were performed potentiostatically at −0.25V versus SCE. Total Co, Cr, and Ti release to the media was determined by ICP-MS. The addition of molybdate ion decreased the release of cobalt by 32% and increased the after-to-before ratio of the polarization resistance by 8× at pH4.5, but had not effect on these parameters at pH7.6. Film deposits in the wear scar were more pronounced in the presence of molybdate ion. The addition of molybdate ion to the medium had a significant protective effect for the CoCrMo only at pH4.5, possibly because the lower pH allowed for more molybdate-induced protein film formation.

      PubDate: 2017-05-20T16:35:50Z
      DOI: 10.1016/j.biotri.2017.05.002
  • Spherically Capped Membrane Probes for Low Contact Pressure Tribology
    • Authors: Samantha L. Marshall; Kyle D. Schulze; Samuel M. Hart; Juan Manuel Urueña; Eric O. McGhee; Alexander I. Bennett; Angela A. Pitenis; Christopher S. O'Bryan; Thomas E. Angelini; W. Gregory Sawyer
      Abstract: Publication date: Available online 15 May 2017
      Author(s): Samantha L. Marshall, Kyle D. Schulze, Samuel M. Hart, Juan Manuel Urueña, Eric O. McGhee, Alexander I. Bennett, Angela A. Pitenis, Christopher S. O'Bryan, Thomas E. Angelini, W. Gregory Sawyer
      Low contact pressure measurements are needed for biotribology studies on cells, cell layers, and tissues. Such studies typically require low forces to achieve kPa range contact pressures, but such methods frequently come at the expense of contact area and, in turn, relevance. In seeking lower contact pressures, the corresponding contact areas can become too small to be physiologically relevant or important. The recently developed method creates probes that are thin spherical shells, specifically designed to create low contact pressures. These polyethylene glycol and polyacrylamide hydrogels probes were polymerized with embedded fluorescent nanoparticles, and indentation experiments were performed in situ on a confocal microscope to determine the deformation mechanics. The indentation load versus contact width behavior revealed that this design has the ability to achieve pressures in the kPa range at macroscopic contact areas that are independent of the applied load (i.e., the area grows linearly with the applied load, leading to a constant contact pressure).

      PubDate: 2017-05-20T16:35:50Z
      DOI: 10.1016/j.biotri.2017.03.008
  • Feeling fine - the effect of topography and friction on perceived
           roughness and slipperiness
    • Authors: Martin Arvidsson; Lovisa Ringstad; Lisa Skedung; Kenneth Duvefelt; Mark W. Rutland
      Abstract: Publication date: Available online 15 May 2017
      Author(s): Martin Arvidsson, Lovisa Ringstad, Lisa Skedung, Kenneth Duvefelt, Mark W. Rutland
      (1) Background. To design materials with specific haptic qualities, it is important to understand both the contribution of physical attributes from the materials surfaces and the perceptions that are involved in the haptic interaction. (2) Methods. A series of 16 wrinkled surfaces consisting of two similar materials, of different elastic modulus and 8 different wrinkle wavelengths were thus characterized in terms of surface roughness and tactile friction coefficient. Sixteen participants scaled the perceived Roughness and Slipperiness of the surfaces using free magnitude estimation. Friction experiments were performed both by participants and by a trained experimenter with higher control. (3) Results and discussion. The trends in friction properties were similar for the group of participants performing the friction measurements in an uncontrolled way and the experiments performed under well-defined conditions, showing that the latter type of measurements represent the general friction properties well. The results point to slipperiness as the key perception dimension for textures below 100μm and roughness above 100μm. Furthermore, it is apparent that roughness and slipperiness perception of these types of structures are not independent. The friction is related to contact area between finger and material. Somewhat surprising was that the material with the higher elastic modulus was perceived as more slippery. A concluding finding was that the flat (high friction) references surfaces were scaled as rough, supporting the theory that perceived roughness itself is a multidimensional construct with both surface roughness and friction components.

      PubDate: 2017-05-20T16:35:50Z
      DOI: 10.1016/j.biotri.2017.01.002
  • Shear Strength of Protein Film Formed by Friction of SiC/SiC Sliding Pair
           in Plasma Environment
    • Authors: Koki Kanda; Koshi Adachi
      Abstract: Publication date: Available online 15 May 2017
      Author(s): Koki Kanda, Koshi Adachi
      This study aimed to clarify the shear strength of a protein film formed by friction of a SiC/SiC sliding pair in a plasma environment. A ball/disk-type tribometer was utilised to obtain the relationship between the friction force in the plasma and the area of protein aggregates formed on the textured SiC disk sliding against the SiC ball in the plasma. To control the area of protein aggregates adsorbed onto the SiC disk surface, different surface textures and ultraviolet (UV) irradiation for the SiC disk were introduced based on past research. Protein aggregates formed owing to protein denaturation and were adsorbed onto the fabricated surface texture of the SiC disk. A broad protein film formed on the SiC disk surface through conjugation of multiple protein films formed from closely distributed concaves. Therefore, the distribution of fabricated concaves determines the conjugation of the protein film formed from each concave, and the trends of frictional force for each SiC/SiC frictional pair in the plasma depends on the area of protein aggregates. In other words, the area of protein aggregates and the frictional force show an almost linear relationship, regardless of the surface texture on the SiC disk or UV irradiation. Finally, the shear strength of the protein aggregates against the sliding SiC ball in plasma was 7.14MPa, as determined from the relationship between the area of the protein aggregates and the frictional force in the plasma environment.

      PubDate: 2017-05-20T16:35:50Z
      DOI: 10.1016/j.biotri.2017.01.003
  • Corneal cell friction: Survival, lubricity, tear films, and mucin
           production over extended duration in vitro studies
    • Authors: Angela A. Pitenis; Juan Manuel Urueña; Tristan T. Hormel; Tapomoy Bhattacharjee; Sean R. Niemi; Samantha L. Marshall; Samuel M. Hart; Kyle D. Schulze; Thomas E. Angelini; W. Gregory Sawyer
      Abstract: Publication date: Available online 12 May 2017
      Author(s): Angela A. Pitenis, Juan Manuel Urueña, Tristan T. Hormel, Tapomoy Bhattacharjee, Sean R. Niemi, Samantha L. Marshall, Samuel M. Hart, Kyle D. Schulze, Thomas E. Angelini, W. Gregory Sawyer
      The tear film is a thin, aqueous, mucin-rich layer on the ocular surface that provides hydration and lubrication for healthy vision. The ability of the tear film to provide a highly lubricious interface during ocular movement is largely attributed to its entangled network of mucins secreted from the corneal and conjunctival epithelia. However, the extent to which these mucin networks can provide lubricity and protect the epithelia over extended durations of contact lens interactions is unknown. In vitro tribological experiments were performed against a monolayer of mucin-producing human corneal epithelial cells (hTCEpi) for 10,000 reciprocating cycles at physiologically-relevant contact pressures and deliberately low and tribologically-challenging sliding speeds. The use of a polyacrylamide hydrogel probe with a spherically-capped shell geometry enabled average normal forces of FN ~200μN and contact pressures on the order of 1kPa, resulting in an average friction coefficient of μ=0.058±0.008 over 10,000 reciprocating cycles. Cell survival after extended duration tribological experimentation was approximately 99.8%. Mucin was observed to accumulate during the experiment. From these in vitro studies, we postulate that mucin production may be a cellular process driven in part by frictional shear stress.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.04.003
  • In-situ Generated Tribomaterial in Metal/Metal Contacts: Current
           understanding and future implications for implants
    • Authors: N. Espallargas; A. Fischer; A. Igual Muñoz; S. Mischler; M.A. Wimmer
      Abstract: Publication date: Available online 12 May 2017
      Author(s): N. Espallargas, A. Fischer, A. Igual Muñoz, S. Mischler, M.A. Wimmer
      Artificial hip joints operate in aqueous biofluids that are highly reactive towards metallic surfaces. The reactivity at the metal interface is enhanced by mechanical interaction due to friction, which can change the near-surface structure of the metal and surface chemistry. There are now several reports in the literature about the in-situ generation of reaction films and tribo-metallurgical transformations on metal-on-metal hip joints. This paper summarizes current knowledge and provides a mechanistic interpretation of the surface chemical and metallurgical phenomena. Basic concepts of corrosion and wear are illustrated and used to interpret available literature on in-vitro and in-vivo studies of metal-on-metal hip joints. Based on this review, three forms of tribomaterial, characterized by different combinations of oxide films and organic layers, can be determined. It is shown that the generation of these tribofilms can be related to specific electrochemical and mechanical phenomena in the metal interface. It is suggested that the generation of this surface reaction layer constitutes a way to minimize (mechanical) wear of MoM hip implants.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.03.006
  • A Confocal Fluorescence Microscopy Method for Measuring Mucous Layer
           Growth on Living Corneal Epithelia
    • Authors: Tristan T. Hormel; Tapomoy Bhattacharjee; Angela A. Pitenis; Juan M. Urueña; W. Gregory Sawyer; Thomas E. Angelini
      Abstract: Publication date: Available online 11 May 2017
      Author(s): Tristan T. Hormel, Tapomoy Bhattacharjee, Angela A. Pitenis, Juan M. Urueña, W. Gregory Sawyer, Thomas E. Angelini
      Mucous layers at corneal epithelial cell surfaces perform a variety of tribological roles and are integral to the function of associated biological structures. The primary component of these layers are mucin glycosylated proteins, a broad and diverse class of biological macromolecules that influence tribological and rheological characteristics of the eye's tear film. The tear film composition is incessantly modulated by environmental conditions, active production by living cells, and passive processes such as degradation or wear. Quantitative investigation of mucin production and accumulation at the corneal surface will improve current understanding of tear film stability and function. Here, we present fluorescence microscopy and image analysis techniques capable of capturing the dynamics of mucous layer growth. Using this technique, we observe a non-monotonically thickening mucin layer at the apical surface of a corneal epithelial cell monolayer, while the total amount of mucin increases at a rate indicative of diffusion limited growth.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.04.004
  • Influence of the machining cooling strategies on the dental tribocorrosion
           behaviour of wrought and additive manufactured Ti6Al4V
    • Authors: R. Bertolini; S. Bruschi; A. Ghiotti; L. Pezzato; M. Dabalà
      Abstract: Publication date: Available online 11 May 2017
      Author(s): R. Bertolini, S. Bruschi, A. Ghiotti, L. Pezzato, M. Dabalà

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.03.002
  • The Influence of Molybdenum on the Fretting Corrosion Behavior of
           CoCr/TiAlV Couples
    • Authors: A. Fischer; D. Janssen; M.A. Wimmer
      Abstract: Publication date: Available online 10 May 2017
      Author(s): A. Fischer, D. Janssen, M.A. Wimmer
      Fretting corrosion in biomedical taper junctions is of concern for possible adverse tissue reactions. But the exact interaction of the different metals in such tapers is still unknown. A proteinaceous tribofilm is beneficial, since it can act as boundary lubricant as well as hinder corrosive attack. Such tribofilm can be generated by mechanical mixing and consists of denatured proteins and nano-size wear particles. Still, it has also been shown that one can produce such a film by releasing Mo ions into the serum: the addition of molybdates into the lubricant enhances the tribological properties under fretting. The question remains whether the release of Mo ions out of the worn surfaces also provides such a beneficial effect. Fretting tests using cobalt-chromium alloys with and without molybdenum against titanium alloy in bovine calf serum (BCS) were conducted. During the tests the frictional work as well as the open-corrosion potential was recorded. After the tests the depths of the wear scars were investigated, as well as the wear appearances before and after removing any remains of a proteinaceous tribofilm. A metal content analysis of the bovine serum as well as the cleaning fluid is discussed in relation to wear mechanisms. This brought about that Mo ions released from the surfaces hinder corrosive attack and, therefore, lower the wear loss. While this positive effect of Mo is evident, the beneficial influence on the tribofilm is not as obvious. Mechanically-dominated wear mechanisms did not allow for a substantial contribution of the tribofilm.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.01.001
  • Effects of Material Thickness and Surface Modification of Cross-linked
           Polyethylene with Poly(2-Methacryloyloxyetheyl Phosphorylcholine) on Its
           Deformation Behavior, Wear Resistance and Durability Under Repetitive
           Impact-to-sliding Motion
    • Authors: Kenichi Saiga; Masayuki Kyomoto; Kenichi Watanabe; Shuji Taketomi; Yuho Kadono; Yoshio Takatori; Sakae Tanaka; Kazuhiko Ishihara; Toru Moro
      Abstract: Publication date: Available online 10 May 2017
      Author(s): Kenichi Saiga, Masayuki Kyomoto, Kenichi Watanabe, Shuji Taketomi, Yuho Kadono, Yoshio Takatori, Sakae Tanaka, Kazuhiko Ishihara, Toru Moro
      Background Large femoral heads and thin cross-linked polyethylene (CLPE) acetabular liners are required for preventing dislocation in total hip arthroplasty (THA). However, the wear resistance and durability of thin CLPE liners in severe physiological conditions has not been fully understood. Methods In this study, we investigated the wear and fatigue properties of untreated CLPE (50kGy gamma-ray irradiated and annealed) and poly(2-methacryloyloxyethyl phosphorylcholine)-grafted CLPE (PMPC-grafted CLPE) disks that were 3mm and 6mm in thickness and subjected to a repetitive impact-to-wear test using a pin-on-disk testing machine. Results PMPC grafting reduced the gravimetric wear of 3mm and 6mm thick CLPE disks, but did not affect volumetric changes at the impact area. However, the volumetric change for 6mm thick PMPC-grafted CLPE disks in areas subjected to high pressure was significantly less than that for CLPE. The thickness of CLPE did not affect its gravimetric wear, whereas volumetric changes at both bearing and backside surfaces of 3mm thick disks were significantly larger than those of 6mm thick disks. The results of finite element analysis indicated that the maximum von Mises stress of 3mm thick CLPE disks near the backside hole was greater than its yield stress, which resulted in cold flow. Delamination and fracture did not occur for any disks. Discussion Under impact-to-wear conditions, PMPC grafting and CLPE substrate with sufficient thickness brought wear and fatigue resistance; those are favorable candidates for bearing material under the severe physiological conditions present in reconstructed hip joints.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.03.005
  • Rheology and Tribology Study of the Sensory Perception of Oral Care
    • Authors: Huifang Cai; Yujun Li; Jianshe Chen
      Abstract: Publication date: Available online 10 May 2017
      Author(s): Huifang Cai, Yujun Li, Jianshe Chen
      The texture sensation is an important contribute to consumers' acceptance and preference of oral care products (e.g. toothpaste). A product's rheological properties and its oral tribological behaviour have strong influences on sensory perception, but the mechanisms underpinning such processes are still little known. In this work, a simple experimental set up was used to measure lubricating properties (friction coefficient) as a function of speed for toothpaste samples and their mixtures with either artificial saliva or water. Particle size distribution and rheological properties were also measured along with the lubrication properties. Sensory smoothness and granularity were assessed by a panel using both fingers and tongue. The lubricating properties show significant differences in the boundary regime giving effective discrimination of sample systems. Results from tribological measurements showed a strong linear correlation with the sensory smoothness obtained from taste panel. Further data analysis showed that both rheological properties (viscosity) and particle size distribution strongly influenced the lubrication behaviour and therefore, contributes to smoothness perception. Results from this work show that combination of rheological and tribological techniques could be a feasible instrumental approach to assess sensory properties of oral care products.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.03.001
  • Tactile Discrimination of Randomly Textured Surfaces: Effect of Friction
           and Surface Parameters
    • Authors: G.P. Chimata; C.J. Schwartz
      Abstract: Publication date: Available online 10 May 2017
      Author(s): G.P. Chimata, C.J. Schwartz
      The aim of the current study is to identify the physical factors that could potentially be indicative of the tactile discriminability of textured surfaces. To this end, the tactile discrimination sensitivity for fine randomly textured surfaces was evaluated and its relation to the surface parameters and the coefficient of friction was investigated. Discrimination tasks were performed using a two-interval forced choice technique and the mean probability of perceiving a difference was measured for pairwise combinations of six fine-grit abrasive papers. The surface roughness parameters of the abrasive papers were measured using a contact profilometer and scanning electron microscopy images helped observe the surface microstructure. The coefficient of friction for each of the abrasive papers against human finger was measured for two sliding orientation of the finger: an ‘aligned’ orientation along the length of the finger and a ‘transverse’ orientation perpendicular to the length of the finger. Possible cases of theoretical probabilities of perceiving a difference for a given pair of tactile samples were proposed and the experimental probabilities were discussed within this context. Based on the evidence in existing literature, three measurable properties were chosen to investigate possible correlation with the mean discrimination probability: root mean square roughness, mean spacing of the profile peaks, and the mean coefficient of friction. Experimental evidence suggests that of the three parameters investigated, differences in the mean spacing and the mean friction coefficients were more indicative of the probability of perceiving difference between a pair of fine textured samples.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.01.004
  • Measurement of Friction-induced Changes in Pig Aorta Fibre Organization by
           Non-invasive Imaging as a Model for Detecting the Tissue Response to
           Endovascular Catheters
    • Authors: Luciana E. Bostan; Christopher Noble; Nicole Smulders; Roger Lewis; Matt J. Carré; Steve Franklin; Nicola H. Green; Sheila MacNeil
      Abstract: Publication date: Available online 10 May 2017
      Author(s): Luciana E. Bostan, Christopher Noble, Nicole Smulders, Roger Lewis, Matt J. Carré, Steve Franklin, Nicola H. Green, Sheila MacNeil
      Alterations in quantity or architecture of elastin and collagen fibres are associated with some blood vessel pathologies. Also some medical interventions such as endovascular catheterization have the potential to damage blood vessels. This study reports the use of porcine aorta as a model system for studying the physical impact of catheters on vasculature, in conjunction with non-invasive imaging techniques to analyse collagen and elastin fibre organization and assess load-induced changes. Porcine aorta was exposed to frictional trauma and elastin and collagen fibre orientation evaluated by destructive, histochemical methods and non-invasive imaging. The latter allowed the immediate impact of force on fibre orientation and fibre recovery to be evaluated longitudinally. In normal aorta, elastin fibres are aligned at the surface, but become less aligned with increasing depth, showing no alignment by ~30μm. Collagen fibres meanwhile appear aligned down to a depth of 35μm. Changes in collagen and elastin fibre orientation in healthy pig aorta were detected by conventional destructive histology within 5min of application of a sliding 10N load, while lesser loads had less impact. Good recovery of fibre orientation was observed within 20min. Non-invasive imaging of ex vivo aorta tissue provides a good indication of the extent of fibre re-organization following frictional stress, at loads similar to those encountered during medical interventions such as catheterization. These results indicate that tissue deformation can occur from these procedures, even in healthy tissue, and highlight the potential for the development of an in vivo probe capable of monitoring vascular changes in patients.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.02.003
  • The Influence of Proteins and Speed on Friction and Adsorption of
           Metal/UHMWPE Contact Pair
    • Authors: D. Nečas; Y. Sawae; T. Fujisawa; K. Nakashima; T. Morita; T. Yamaguchi; M. Vrbka; I. Křupka; M. Hartl
      Abstract: Publication date: Available online 10 May 2017
      Author(s): D. Nečas, Y. Sawae, T. Fujisawa, K. Nakashima, T. Morita, T. Yamaguchi, M. Vrbka, I. Křupka, M. Hartl
      It was reported in several studies that friction and wear of joint prosthesis are apparently influenced by the proteins contained in the synovial fluid. However, detailed mechanisms of these tribological processes have not been clarified yet. The present study aims on the effect of adsorbed protein film on frictional behaviour of metal/polyethylene contact pair. Reciprocating pin-on-plate test was conducted, while the CoCrMo pin was sliding against UHMWPE plate. The contact was lubricated by various solutions of albumin and γ-globulin solved in PBS. After the friction test, the thickness of adsorbed film was evaluated using spectroscopic ellipsometry. Structure of the adsorbed proteins was later examined by FT-IR. The results showed that at low sliding speed equal to 10mm/s, there was a linear correlation between the friction coefficient and the thickness of the adsorbed protein film. An increase of friction was thus accompanied by the evolution of protein film. In that case, both proteins undergone substantial conformational changes, losing their original structure. On the contrary, proteins could sustain their secondary structure to some extent at higher sliding speed (50mm/s), when different behaviour of the both proteins could be observed. This phenomenon was attributed to different structure of albumin and γ-globulin in its native state. It might be concluded that friction coefficient of metal-on-polyethylene joint prosthesis is influenced by protein content, as well as kinematic conditions, since the sliding conditions have a certain effect on both the adsorbed film formation and structure of the adsorbed molecules.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.03.003
  • Polymer Osmotic Pressure in Hydrogel Contact Mechanics
    • Authors: Kyle D. Schulze; Samuel M. Hart; Samantha L. Marshall; Christopher S. O'Bryan; Juan M. Urueña; Angela A. Pitenis; W. Gregory Sawyer; Thomas E. Angelini
      Abstract: Publication date: Available online 10 May 2017
      Author(s): Kyle D. Schulze, Samuel M. Hart, Samantha L. Marshall, Christopher S. O'Bryan, Juan M. Urueña, Angela A. Pitenis, W. Gregory Sawyer, Thomas E. Angelini
      Simple, semi-dilute hydrogels made from flexible polymers are often used as material surrogates for biological tissues, despite the dramatic differences between gels and tissues in their micro- and nano-structure, osmotic properties, and fluid permeability. Moreover, these simple hydrogels are often treated as poroelastic, even when applied pressures are below the hydrogel's osmotic pressure. Here we investigate the role of polymer osmotic pressure in hydrogel contact mechanics with a series of local indentation tests and bulk compression tests. Performing hydrogel indentation atop an inverted confocal microscope and applying surface pressures less than the hydrogel osmotic pressure, we find that hydrogel deformation behavior agrees with the Hertz model, observing no evidence of fluid flow or volumetric gel compression. A long-time creep of the hydrogel is also found, which can be predicted from a model of diffusive relaxations within the gel. In bulk compression tests, the gel is found to be incompressible, and therefore water cannot be driven out of the gel, unless the applied pressure exceeds the hydrogel osmotic pressure.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.03.004
  • Wear Evaluation of Nanostructured Ti Cermets for Joint Reconstruction
    • Authors: E.P. Georgiou; D. Drees; S. Dosta; P. Matteazzi; J. Kusinski; J.-P. Celis
      Abstract: Publication date: Available online 10 May 2017
      Author(s): E.P. Georgiou, D. Drees, S. Dosta, P. Matteazzi, J. Kusinski, J.-P. Celis
      Nanostructured cermet coatings consisting of titanium carbides dispersed in a titanium matrix were deposited by supersonic spraying. The aim is to develop novel wear resistant materials that can be applied in joint reconstruction. Structural analysis was performed by Scanning Electron Microscopy, Transition Electron Microscopy, and X-ray Diffraction, whereas the mechanical properties of each phase were determined by nanoindentation technique. In addition, in order to evaluate the friction and wear behavior of these Ti-TiC nanostructured cermet coatings, a two-step tribological approach was applied. This approach consists of two test series. First, pre-screening sliding wear tests were performed in order to provide a ranking of the coatings and a comparison with commonly used biomedical benchmarks. Subsequently parallel wear tests that simulate the joint contact conditions were used to evaluate the reliability of these coatings and the wear loss of the actual tribosystem (coatings vs polyethylene). The experimental results indicated that Ti-TiC cermets possess superior tribological properties, thanks to the appropriate balance of hard carbide and soft titanium phases, and the nanostructuring of the titanium matrix. The wear mechanism was investigated in order to establish a ‘structure–property’ relationship for these coatings.

      PubDate: 2017-05-15T16:16:50Z
      DOI: 10.1016/j.biotri.2017.03.007
  • Formation and Tribology of Fucoidan/Chitosan Polyelectrolyte Multilayers
           on PDMS Substrates
    • Authors: Tracey T.M. Ho; Nichola Selway; Marta Krasowska; Gleb E. Yakubov; Jason R. Stokes; David A. Beattie
      Abstract: Publication date: Available online 10 May 2017
      Author(s): Tracey T.M. Ho, Nichola Selway, Marta Krasowska, Gleb E. Yakubov, Jason R. Stokes, David A. Beattie
      Polysaccharide polyelectrolyte multilayers (PEMs) based on fucoidan and chitosan were formed by Layer-by-Layer (LbL) assembly on polydimethylsiloxane (PDMS) substrates. The surface and aqueous lubrication properties of the PEM films are evaluated for two types of fucoidan extracted from separate seaweed species (Fucus vesiculosus – FV and Undaria pinnatifida – UP). Zeta potential and atomic force microscopy (AFM) imaging reveal that the PEM layers are formed with consistent charge reversal as each polysaccharide layer is adsorbed to the PDMS substrate, and that there is an associated increase in thickness of the multilayer. The multilayers containing FV fucoidan are found to be thicker than those containing UP fucoidan. Soft tribology measurements using matching PDMS tribo-pairs are used to show that the films are robust under rolling/sliding contacts and effective under aqueous lubricating conditions. The friction in the boundary lubrication regime is substantially decreased (relative to native hydrophobic PDMS) by the presence of the multilayers, with some dependence on whether fucoidan or chitosan is in the outer layer (5 or 5.5 bilayers) for FV fucoidan. The lowest friction coefficient is obtained for the multilayer with the thickest (and likely most hydrated) coating – the (FV/chitosan) 5.5 bilayer system. The results suggest that PEMs involving naturally derived polysaccharides such as fucoidan, which has notable antimicrobial properties and is resistant to enzymatic degradation, may provide opportunities in surface coating design in biomaterials applications for friction reduction.
      Graphical abstract image

      PubDate: 2017-05-10T15:53:27Z
      DOI: 10.1016/j.biotri.2017.04.002
  • Oral Parameters Affecting Ex-vivo Tribology
    • Authors: Marie-Anne van Stee; Els de Hoog; Fred van de Velde
      Abstract: Publication date: Available online 8 May 2017
      Author(s): Marie-Anne van Stee, Els de Hoog, Fred van de Velde
      Lubrication behaviour of foods has been explored in recent years and resulted in a better understanding of mouthfeel attributes, such as creaminess. Oral processing is a dynamic process that transfers the food into a bolus that is safe to swallow. This process is accompanied by a transition from rheology-dominant processes to tribology-dominant processes. In order to translate the oral movements into instrumental settings of analytical equipment a more precise quantification of the oral processing conditions is required. In recent years, several studies have delivered information about the oral movements. In this study, we focus on the lubrication behaviour of emulsions with different fat content and the role of instrumental settings on the measured lubrication behaviour. We found an effect of the type of movement performed with the tribometer. The oil concentration dependency of the measured friction was different when measured with a semi-ellipse movement compared to a linear or rotational movement. The deformation of the silicone and PDMS surfaces plays a role, replacing the silicone surface with a glass surface resulted in a different lubrication behaviour. Small changes in surface roughness of the PDMS surface affected the lubrication measured to a large extend. The impact of type of movement, type of surface and roughness of surface was not specific for the emulsions used; similar impact was found for rice starch dispersions. This investigation showed that subtle differences in the measuring conditions of the friction force can lead to different lubrication behaviour of (food) products and therefore conclusions.

      PubDate: 2017-05-10T15:53:27Z
      DOI: 10.1016/j.biotri.2017.05.001
  • Implications of Multi-asperity Contact for Shear Stress Distribution in
           the Viable Epidermis – An Image-based Finite Element Study
    • Authors: Maria F. Leyva-Mendivil; Jakub Lengiewicz; Anton Page; Neil W. Bressloff; Georges Limbert
      Abstract: Publication date: Available online 5 May 2017
      Author(s): Maria F. Leyva-Mendivil, Jakub Lengiewicz, Anton Page, Neil W. Bressloff, Georges Limbert
      Understanding load transfer mechanisms from the surface of the skin to its deeper layers is crucial in gaining a fundamental insight into damage phenomena related to skin tears, blisters and superficial/deep tissue ulcers. It is unknown how shear stresses in the viable epidermis are conditioned by the skin surface topography and internal microstructure and to which extent their propagation is conditioned by the size of a contacting asperities. In this computational study, these questions were addressed by conducting a series of contact finite element analyses simulating normal indentation of an anatomically-based two-dimensional multi-layer model of the skin by rigid indenters of various sizes and sliding of these indenters over the skin surface. Indentation depths, local (i.e. microscopic) coefficients of friction and Young's modulus of the stratum corneum were also varied. For comparison purpose and for isolating effects arising purely from the skin microstructure, a geometrically-idealised equivalent multi-layer model of the skin was also considered. The multi-asperity contact induced by the skin topographic features in combination with a non-idealised geometry of the skin layers lead to levels of shear stresses much higher than those produced in the geometrically-idealised case. These effects are also modulated by other system parameters (e.g. local coefficient of friction, indenter radius). These findings have major implications for the design and analyses of finite element studies aiming at modelling the tribology of skin, particularly if the focus is on how surface shear stress leads to damage initiation which is a process known to occur across several length scales.

      PubDate: 2017-05-10T15:53:27Z
      DOI: 10.1016/j.biotri.2017.04.001
  • Surface and subsurface changes as a result of tribocorrosion at the
           stem-neck interface of bi-modular prosthesis
    • Authors: M.G. Bryant; D. Buente; A. Oladokun; M. Ward; G. Huber; M. Morlock; A. Neville
      Abstract: Publication date: Available online 6 March 2017
      Author(s): M.G. Bryant, D. Buente, A. Oladokun, M. Ward, G. Huber, M. Morlock, A. Neville
      This study presents a detailed multi-scale analysis of the degradation processes occurring on both the CoCrMo and TMZF alloy surfaces at different regions across the taper interface. Co-ordinate measurement machine, scanning electron microscopy, transmission electron microscopy and X-ray diffraction methods have been utilised to identify the roles of degradation from the mm to nm scale. Depending on the region of interest, varying topographies and subsurface morphologies were observed across both surfaces. In regions where high pressures are expected, retention of the surface topography was seen on the CoCrMo trunnion. This was complimented by gross shear and plastic deformation of the subsurface material. In regions where maximum penetration was seen, evidence of fretting-corrosion was seen and a loss of the nano-crystalline layer. For the TMZF surface, refinement of the alloy was seen in the top 5μm, with fatigue cracks within the bulk present. Precipitation and formation of oxide species were observed at depths of 2μm. The degradation of a bi-modular prosthesis is a complex multifactorial process. It is hypothesised that this formation of oxide species at the interface and within the bulk alloy plays an important role in the degradation through a combined work-hardening and corrosion process.

      PubDate: 2017-03-10T07:25:05Z
      DOI: 10.1016/j.biotri.2017.02.002
  • Tunable Lubricin-mimetics for Boundary Lubrication of Cartilage
    • Authors: Kirk J. Samaroo; Mingchee Tan; Roberto C. Andresen Eguiluz; Delphine Gourdon; David Putnam; Lawrence J. Bonassar
      Abstract: Publication date: Available online 20 February 2017
      Author(s): Kirk J. Samaroo, Mingchee Tan, Roberto C. Andresen Eguiluz, Delphine Gourdon, David Putnam, Lawrence J. Bonassar
      The glycoprotein lubricin is the primary boundary lubricant of articular cartilage. Its boundary lubricating abilities arise from two key structural features: i) a dense mucin-like domain consisting of hydrophilic oligosaccharides and ii) an end terminus that anchors the molecule to articulating surfaces. When bound, lubricin molecules attract and trap water near a surface, reducing friction and facilitating glide. Synthetic analogues were previously created to mimic lubricin using thiol-terminated polyacrylic acid-graft-polyethylene glycol (pAA-g-PEG) brush copolymers. The PEG moiety was designed to mimic the mucin-like domain of lubricin and the thiol-terminus was designed to anchor the molecules to cartilage surfaces, mimicking the binding domain. In this study, these synthetic lubricin-mimetics were bound to gold-coated surfaces to characterize the relationship between the polymers' molecular architecture and their lubricating capacity. A library of nine copolymer brushes was synthesized using different sizes of pAA and PEG. Larger molecular weight polymers created smoother, more densely covered surfaces (p<0.05). Additionally, the hydrodynamic sizes of the polymers in solution were correlated with their lubricating abilities (p<0.05). Friction coefficients of cartilage against polymer-treated gold surfaces were lower than cartilage against untreated surfaces (Δμeq =−0.065±0.050 to −0.093±0.045, p<0.05).

      PubDate: 2017-02-25T20:13:51Z
      DOI: 10.1016/j.biotri.2017.02.001
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