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  • Continuous functionally graded porous titanium scaffolds manufactured by selective laser melting for bone implants
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-12
    Changjun Han, Yan Li, Qian Wang, Shifeng Wen, Qingsong Wei, Chunze Yan, Liang Hao, Jie Liu, Yusheng Shi
    更新日期:2018-01-12
  • How proteolytic inhibitors interact with dentin on glass-fiber post luting over 6 months
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-11
    Larissa Pinceli Chaves, Thales Lippi Ciantelli, Diana Ferreira Gadelha de Araújo, Marina Ciccone Giacomini, Leo Tjäderhane, Polliana Mendes Candia Scaffa, Heitor Marques Honório, Linda Wang

    Objectives Enzyme inhibitors minimize the degradation of unprotected collagen of dentin promoted by matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs). As the evidence of their effect on the root canal is limited, this study aimed to evaluate the role of EDTA, chlorhexidine and E-64 as antiproteolytic agents on the bond strength (BS) of glass-fiber posts in root canals. Materials and Methods Ninety-six bovine roots were distributed in groups for each time point (n=8). Adper Scotchbond Multipurpose (MP)/ RelyX ARC system was used to lute the post according to the treatment: negative control (NC)- water, EDTA- 17% ethylenediaminetetraacetic acid, CHX- 2% digluconate chlorhexidine, E-64-5- 5 μM E-64, E-64-10- 10 μM E-64 and positive control (PC)- MP associated with activator/ catalyst. Then, slices were subjected to push-out test (0.5 mm/min) after 24 h/6 mons. Data were analyzed by three-way ANOVA/Tukey tests. Failure modes were analyzed (40×). Results The factors treatment, time, root canal third and the interaction between treatment and time were statistically significant. At 24 h, no negative interactions were observed among the root dentin, bonding system and post. At 6 mons, CHX improved the BS for middle and apical root thirds. Conclusions CHX was able to promote beneficial BS after 6 mons, which was not noted for any other tested enzyme inhibitors.

    更新日期:2018-01-12
  • Temporal and spatial variations of pressure within intervertebral disc nuclei
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-11
    Hendrik Schmidt, Aboulfazl Shirazi-Adl
    更新日期:2018-01-12
  • The Impact of Development of Atherosclerosis on Delamination Resistance of the Thoracic Aortic Wall
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-11
    Marta Kozuń, Magdalena Kobielarz, Agnieszka Chwiłkowska, Celina Pezowicz

    The aim of this work is to determine the impact of development of atherosclerosis on dissection of the human thoracic aorta on the basis of an analysis of the mechanical properties of the interfaces between its layers. The research material consisted of 17 pathologically unchanged aortae and 74 blood vessels with atherosclerotic lesions, which were classified according to the histological classification by Stary. The subject of the analysis were the interfaces between the adventitia and the media-intima complex (A-MIC) and between the intima and the media-adventitia complex (I - MAC). The mechanical properties of the above interfaces were determined by the peeling test in the longitudinal and circumferential directions. The results indicate that development of atherosclerosis reduces vessel wall resistance to delamination. The greatest risk of dissection occurs at stage IV of the disease. In this case, energy values are lower by about 28% for the I-MAC interface and by 39% for the A-MIC interface compared with normal tissues. Lower values of mean force and energy were obtained for the I-MAC interface, indicating that this interface is more susceptible to delamination. The mechanical properties of the A-MIC interfaces are directional.

    更新日期:2018-01-11
  • Mechanical Viability of a Thermoplastic Elastomer Hydrogel as a Soft Tissue Replacement Material
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-10
    Kristine M. Fischenich, Jackson T. Lewis, Travis S. Bailey, Tammy L. Haut Donahue
    更新日期:2018-01-11
  • Preparation and characterization of silane-modified SiO2 particles reinforced resin composites with fluorinated acrylate polymer
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-10
    Xue Liu, Zengyao Wang, Chengji Zhao, Wenhuan Bu, Hui Na

    A series of fluorinated dental resin composites were prepared with two kinds of SiO2 particles. Bis-GMA (bisphenol A-glycerolate dimethacrylate)/4-TF-PQEA (fluorinated acrylate monomer)/TEGDMA (triethylene glycol dimethacrylate) (40/30/30, wt/wt/wt) was introduced as resin matrix. SiO2 nanopartices (30 nm) and SiO2 microparticles (0.3 μm) were silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) and used as fillers. After mixing the resin matrix with 0%, 10%, 20%, 30% SiO2 nanopartices and 0%, 10%, 20%, 30%, 40%, 50% SiO2 microparticles, respectively, the fluorinated resin composites were obtained. Properties including double bond conversion (DC), polymerization shrinkage (PS), water sorption (Wp), water solubility (Wy), mechanical properties and cytotoxicity were investigated in comparison with those of neat resin system. The results showed that, filler particles could improve the overall performance of resin composites, particularly in improving mechanical properties and reducing PS of composites along with the addition of filler loading. Compared to resin composites containing SiO2 microparticles, SiO2 nanoparticles resin composites had higher DC, higher mechanical properties, lower PS and lower Wp under the same filler content. Especially, 50% SiO2 microparticles reinforced resins exhibited the best flexural strength (104.04 ± 7.40 MPa), flexural modulus (5.62 ± 0.16 GPa), vickers microhardness (37.34 ± 1.13 HV), compressive strength (301.54 ± 5.66 MPa) and the lowest polymerization (3.42 ± 0.22%).

    更新日期:2018-01-11
  • 更新日期:2018-01-11
  • Effects of alumina nanoparticles on the microstructure, strength and wear resistance of poly(methyl methacrylate)-based nanocomposites prepared by friction stir processing
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-10
    Hamed Aghajani Derazkola, Abdolreza Simchi

    In this study, alumina-reinforced poly(methyl methacrylate) nanocomposites (PMMA/Al2O3) containing up to 20vol.% nanoparticles with an average diameter of 50 nm were prepared by friction stir processing. The effects of nanoparticle volume fraction on the microstructural features and mechanical properties of PMMA were studied. It is shown that by using a frustum pin tool and employing an appropriate processing condition, i.e. a rotational speed of 1600 rpm/min and transverse velocity of 120 mm/min, defect free nanocomposites at microscale with fine distribution of the nanoparticles can successfully been prepared. Mechanical evaluations including tensile, flexural, hardness and impact tests indicate that the strength and toughness of the material gradually increases with the nanoparticle concentration and reach to a flexural strength of 129 MPa, hardness of 101 Shore D, and impact energy 2 kJ/m2 for the nanocomposite containing 20vol.% alumina. These values are about 10% and 20% better than untreated and FSP-treated PMMA (without alumina addition). Fractographic studies indicate typical brittle features with crack deflection around the nanoparticles. More interestingly, the sliding wear rate in a pin-on-disc configuration and the friction coefficient are reduced up to 50% by addition of alumina nanoparticles. The worn surfaces exhibit typical sliding and ploughing features.

    更新日期:2018-01-10
  • Micromechanisms of Fatigue Crack Growth in Polycarbonate Polyurethane: Time Dependent and Hydration Effects
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-10
    Audrey C. Ford, Hannah Gramling, Samuel C. Li, Jessica V. Sov, Amrita Srinivasan, Lisa A. Pruitt

    Polycarbonate polyurethane has cartilage-like, hygroscopic, and elastomeric properties that make it an attractive material for orthopedic joint replacement application. However, little data exists on the cyclic loading and fracture behavior of polycarbonate polyurethane. This study investigates the mechanisms of fatigue crack growth in polycarbonate polyurethane with respect to time dependent effects and conditioning. We studied two commercially available polycarbonate polyurethanes, Bionate® 75D and 80 A. Tension testing was performed on specimens at variable time points after being removed from hydration and variable strain rates. Fatigue crack propagation characterized three aspects of loading. Study 1 investigated the impact of continuous loading (24 hours/day) versus intermittent loading (8 – 10 hours/day) allowing for relaxation overnight. Study 2 evaluated the effect of frequency and study 3 examined the impact of hydration on the fatigue crack propagation in polycarbonate polyurethane. Samples loaded intermittently failed instantaneously and prematurely upon reloading while samples loaded continuously sustained longer stable cracks. Crack growth for samples tested at 2 and 5 Hz was largely planar with little crack deflection. However, samples tested at 10 Hz showed high degrees of crack tip deflection and multiple crack fronts. Crack growth in hydrated samples proceeded with much greater ductile crack mouth opening displacement than dry samples. An understanding of the failure mechanisms of this polymer is important to assess the long-term structural integrity of this material for use in load-bearing orthopedic implant applications.

    更新日期:2018-01-10
  • Characterization and Mechanical Behavior of Reinforced Hydroxyapatite Coatings Deposited by Vacuum Plasma Spray on SS-316L Alloy
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-10
    Amardeep Singh, Gurbhinder Singh, Vikas Chawla

    Hydroxyapatite powder reinforced individually with 10 weight percentage (wt%) of Al2O3 and ZrO2 (HA + 10 wt% Al2O3 and HA + 10 wt% ZrO2) was thermally sprayed onto SS-316L substrate with a bond coat of Zirconia by vacuum plasma spray (VPS) technique. The resulted coatings were heat treated at 700 °C for 1 h to study its effects on microstructural and mechanical properties of the deposited coatings. The characterization of the coatings was carried out using scanning electron microscope, x-ray diffraction, porosity, surface roughness and crystallinity using Rietveld analysis. The results indicated that after post coating heat treatment substantial decrease in porosity was witnessed along with significant improvement in crystallinity. Besides, the hardness across the cross-section of the coatings and bond strength was considerably improved; however the hardness of top coat was reduced owing to the loosening of un-melted and partially melted particles by diffusion process which takes place during heat treatment.

    更新日期:2018-01-10
  • Prediction of circumferential compliance and burst strength of polymeric vascular grafts
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-06
    O. Castillo-Cruz, C. Pérez-Aranda, F. Gamboa, J.V. Cauich-Rodríguez, D. Mantovani, F. Avilés
    更新日期:2018-01-07
  • Mechanical Wear and Oxidative Degradation Analysis of Retrieved Ultra High Molecular Weight Polyethylene Acetabular Cups
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-06
    Dipankar Choudhury, Matúš Ranuša, Robert A. Fleming, Martin Vrbka, Ivan Křupka, Matthew G. Teeter, Josh Goss, Min Zou

    The number of revision joint replacements has been increasing substantially over the last few years. Understanding their failure mechanism is extremely important for improving the design and material selection of current implants. This study includes ten retrieved and four new mildly cross-linked ultra-high molecular weight polyethylene (UHMWPE) acetabular liners. Among them, most of the prostheses (n=5) were reported to be revised and replaced due to aseptic loosening, followed by painful joint (n=2), dislocation (n=1), and intra articular ossification (n=1) and combination of wear (liner) and osteolysis (stem). Surface deviations (wear, material inflation and roughness), oxidative degradation and change of material properties were measured using micro-computer topography (micro-CT) scan, 3D laser scanning microscopy, Raman spectroscopy and nanoindentation, respectively. Prostheses having eccentric worn areas had much higher linear wear rates (228.011 ± 35.51 µm/year) compared to that of centrically worn prostheses (96.706 ± 10.83 µm/year). Oxidation index (OI) showed similar trends to the surface penetration depth. Among them, sample 10 exhibited the highest OI across the contact area and the rim of the cup liners. It also had the lowest hardness/elasticity ratio. Overall, wear and creep, oxidative degradation and reduced hardness/elasticity ratio all contributed to the premature failure of the UHMWPE acetabular cup liners.

    更新日期:2018-01-07
  • Influence of custom foot orthoses on venous status: a quasi-experimental study
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-05
    Daniel López López, Romeu Araujo, Marta Elena Losa Iglesias, Ricardo Becerro de Bengoa Vallejo, António Santos, David Rodríguez Sanz, Cesar Calvo Lobo

    Background Customized foot orthoses (CFO) have been widely accepted to reduce the frequency of foot problems and postural disorders. The purpose of the research was to compare the influence of CFO utilization on the venous status among healthy females and males. Methods This was a quasi-experimental study (NCT03329430), which included 20 healthy subjects that completed all the stages of the process. The subjects showed an age mean of 20.00 ± 1.62 years and were recruited in a foot and ankle specialist center. Self-reported data were medical records and venous function which were evaluated by plethysmography with or without utilization of CFO. Results A sample of 40 feet was studied, showing statistically significant differences between venous filling time (P<0.001) and in the ejection fraction (P<0.001) with CFO utilization versus without use of CFO. Conclusions Healthy people who utilize CFO evidenced an increased venous return in the feet.

    更新日期:2018-01-06
  • Development of a new ex vivo model for evaluation of endoscopic submucosal injection materials performance
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-05
    Ryohei Hirose, Takaaki Nakaya, Yuji Naito, Tomo Daidoji, Hiroaki Yasuda, Hideyuki Konishi, Yoshito Itoh
    更新日期:2018-01-06
  • Setting Mechanism of a New Injectable Dicalcium Phosphate Dihydrate (DCPD) Forming Cement
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-04
    Weiping Ren, Wei Song, Sally Yurgelevic, David C. Markel

    We previously described the gelation mechanism of calcium polyphosphate (CPP) in the presence of water. In this study, we developed novel and injectable poly-dicalcium phosphate dihydrate (P-DCPD) forming cement by the reaction of acidic CPP gel with alkali tetracalcium phosphate (TTCP). The setting reaction mechanism of P-DCPD is due to the intermolecular interaction between CPP gel and TTCP that was supported by XRD, AFM, Raman spectra analysis and SEM. The setting mechanism of P-DCPD is completely different from the classical calcium phosphate cement (CPC) that achieves crystallization by monophosphates reaction. P-DCPD represents a new type of poly-CPCs with significant advantages, including strong mechanical strength, excellent cohesion and easy of handling. More extensive experiments are currently underway to further evaluate the performance of P-DCPD cements, including biocompatibility, degradation behavior and bone defect hearing efficacy, among others.

    更新日期:2018-01-05
  • Isolated and modulated effects of topology and material type on the mechanical properties of additively manufactured porous biomaterials
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-04
    R. Hedayati, S.M. Ahmadi, K. Lietaert, B. Pouran, Y. Li, H. Weinans, C.D. Rans, A.A. Zadpoor

    In this study, we tried to quantify the isolated and modulated effects of topological design and material type on the mechanical properties of AM porous biomaterials. Towards this aim, we assembled a large dataset comprising the mechanical properties of AM porous biomaterials with different topological designs (i.e. different unit cell types and relative densities) and material types. Porous structures were additively manufactured from Co-Cr using a selective laser melting (SLM) machine and tested under quasi-static compression. The normalized mechanical properties obtained from those structures were compared with mechanical properties available from our previous studies for porous structures made from Ti-6Al-4V and pure titanium as well as with analytical solutions. The normalized values of elastic modulus and yield stress were found to be relatively close to each other as well as in agreement with analytical solutions regardless of material type. However, the material type was found to systematically affect the mechanical properties of AM porous biomaterials in general and the post-elastic/post-yield range (plateau stress and energy absorption capacity) in particular. To put this in perspective, topological design could cause up to 10-fold difference in the mechanical properties of AM porous biomaterials while up to 2-fold difference was observed as a consequence of changing the material type.

    更新日期:2018-01-04
  • Energy Absorption Characteristics of Bio-Inspired Honeycomb Column Thin-Walled Structure Under Impact Loading
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2018-01-04
    Peng Hao, Jianxun Du

    Beetles have developed the elytra that are interesting and impressive strategy for thriving in their native environments. The elytra, although formed from simple biopolymer constituents, take on many effective designs. In present work, internal structure of elytra is discussed and three bionic structures named as the bio-inspired honeycomb column thin-walled structure (BHTS) are proposed. Then the crushing behavior and energy absorption characteristics of the BHTS under axial impact loading are investigated by numerical simulation. This study reveals not only the relationship between the adding mode and energy absorption characteristics, but also the influence of column diameter on the BHTS. The findings show that the BHTS represents a significant improvement over honeycomb structures and show potential applications in the field of protective equipment.

    更新日期:2018-01-04
  • A Constitutive Model Description of the In Vivo Material Properties of Lower Birth Canal Tissue During the First Stage of Labor
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-30
    Paige V. Tracy, Alan S. Wineman, Francisco J. Orejuela, Susan M. Ramin, John O.L. DeLancey, James A. Ashton-Miller
    更新日期:2017-12-31
  • Effect of freezing conditions on β-Tricalcium Phosphate /Camphene scaffold with micro sized particles fabricated by freeze casting
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-30
    Gurdev Singh, S. Soundarapandian

    The long standing need of the implant manufacturing industries is to fabricate multi-matrix, customized porous scaffold as cost-effectively. In recent years, freeze casting has shown greater opportunity in the fabrication of porous scaffolds (tricalcium phosphate, hydroxyapatite, bioglass, alumina, etc.) such as at ease and good control over pore size, porosity, a range of materials and economic feasibility. In particular, tricalcium phosphate (TCP) has proved as it possesses good biocompatible (osteoinduction, osteoconduction, etc.) and biodegradability hence beta-tricalcium phosphate (β-TCP, particle size of 10 µm) was used as base material and camphene was used as a freezing vehicle in this study. Both freezing conditions such as constant freezing temperature (CFT) and constant freezing rate (CFR) were used for six different conditional samples (CFT: 30, 35 and 40 vol.% solid loading; similarly CFR: 30, 35 and 40 vol.% solid loading) to study and understand the effect of various properties (pore size, porosity and compressive strength) of the freeze-cast porous scaffold. It was observed that the average size of the pore was varying linearly as from lower to higher when the solid loading was varying higher to lower. With the help of scanning electron micrographs (SEM), it was observed that the average size of pore during CFR (9.7/ 6.5/ 4.9 µm) was comparatively higher than the process of CFT (6.0/ 4.8/ 2.6 µm) with respect to the same solid loading (30/ 35/ 40 vol.%) conditions. From the Gas pycnometer analysis, it was found that the porosity in both freezing conditions (CFT, CFR) were almost near values such as 32.8% and 28.5%. Further to be observed that with the increase in solid loading, the total porosity value has decreased due to the reduction in the concentration of the freezing vehicle. Hence, the freezing vehicle was found as responsible for the formation of appropriate size and orientation of pores during freeze casting. The compressive strength (CS) testing was clearly indicated that the CS was majorly depending on the size of pore which was depending on solid loading. The CS of CFT-based samples (smaller pore sizes and higher resistance to the propagation of crack) were higher due to the higher solid content (pore size) in compared with CFR-based samples on the similar solid loading conditions. As evidently, it was noted that the CFT-based sample with 40% solid loading has given the compressive strength which has come in the range of cancellous bone. The positive note was that the ratio of Ca/P has come as 1.68 (natural bone) after sintering and that was the required value recommended by the food and drug administration (FDI) for manufacturing of bone implants.

    更新日期:2017-12-31
  • A phospholipid polymer graft layer affords high resistance for wear and oxidation under load bearing conditions
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-30
    Masayuki Kyomoto, Toru Moro, Shihori Yamane, Kenichi Watanabe, Masami Hashimoto, Sakae Tanaka, Kazuhiko Ishihara
    更新日期:2017-12-31
  • Fabrication and characterization of highly porous barium titanate based scaffold coated by Gel/HA nanocomposite with high piezoelectric coefficient for Bone Tissue Engineering Applications
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-30
    Arian Ehterami, Mansure Kazemi, Bahareh Nazari, Payam Saraeian, Mahmoud Azami

    It is well established that the piezoelectric effect plays an important physiological role in bone growth, remodeling and fracture healing. Barium titanate, as a well-known piezoelectric ceramic, is especially an attractive material as a scaffold for bone tissue engineering applications. In this regard, we tried to fabricate a highly porous barium titanate based scaffolds by foam replication method and polarize them by applying an external electric field. In order to enhance the mechanical and biological properties, polarized/non-polarized scaffolds were coated with gelatin and nanostructured HA and characterized for their morphologies, porosities, piezoelectric and mechanical properties. The results showed that the compressive strength and piezoelectric coefficient of porous scaffolds increased with the increase of sintering temperature. After being coated with Gel/HA nanocomposite, the interconnected porous structure and pore size of the scaffolds almost remain unchanged while the Gel/nHA-coated scaffolds exhibited enhanced compressive strength and elastic modulus compared with the uncoated samples. Also, the effect of polarizing and coating of optimal scaffolds on adhesion, viability, and proliferation of the MG63 osteoblast-like cell line was evaluated by scanning electron microscope (SEM) and MTT assay. The cell culture experiments revealed that developed scaffolds had good biocompatibility and cells were able to adhere, proliferate and migrate into pores of the scaffolds. Furthermore, cell density was significantly higher in the coated scaffolds at all tested time-points. These results indicated that highly porous barium titanate scaffolds coated with Gel/HA nanocomposite has great potential in tissue engineering applications for bone tissue repair and regeneration.

    更新日期:2017-12-31
  • Thermomechanical processing of In-containing β-type Ti-Nb alloys
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-29
    Stefan Pilz, David Geissler, Mariana Calin, Jürgen Eckert, Martina Zimmermann, Jens Freudenberger, Annett Gebert

    In this study, the effect of thermomechanical processing on microstructure evolution of the indium-containing β-type Ti alloys (Ti-40Nb)-3.5In and (Ti-36Nb)-3.5In was examined. Both alloys show an increased β-phase stability compared to binary alloys due to In additions. This leads to a reduced α’’-phase fraction in the solution treated and recrystallized state in the case of (Ti-36Nb)-3.5In and to the suppression of stress-induced α’’ formation and deformation twinning for (Ti-40Nb)-3.5In. The mechanical properties of the alloys were subsequently studied by quasistatic tensile tests in the recrystallized state, revealing reduced Young's modulus values of 58 GPa ((Ti-40Nb)-3.5In) and 56 GPa ((Ti-36Nb)-3.5In) compared to 60 GPa as determined for Ti-40Nb. For both In-containing alloys the ultimate tensile strength is in the range of 560 MPa. Due to the suppressed α’’ formation, (Ti-40Nb)-3.5In exhibits a linear elastic deformation behavior during tensile loading together with a low Young's modulus and is therefore promising for load-bearing implants.

    更新日期:2017-12-31
  • Spatial variation of bone biomechanical properties around a dental implant using nanoindentation: a case study
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-28
    Hyung-In Yoon, Min-Jeong Jeon, Hye-Lee Kim, Do-Gyoon Kim, Jung-Suk Han
    更新日期:2017-12-31
  • “Force-from-lipids” gating of mechanosensitive channels modulated by PUFAs
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-28
    Pietro Ridone, Stephan L. Grage, Amrutha Patkunarajah, Andrew R. Battle, Anne S. Ulrich, Boris Martinac
    更新日期:2017-12-31
  • Approach towards the porous fibrous structure of the periodontal ligament using micro-computerized tomography and finite element analysis
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-28
    J. Ortún-Terrazas, J. Cegoñino, U. Santana-Penín, U. Santana-Mora, A. Pérez del Palomar
    更新日期:2017-12-31
  • Biomechanical characterization of human dura mater
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-26
    Dries De Kegel, Julie Vastmans, Heleen Fehervary, Bart Depreitere, Jos Vander Sloten, Nele Famaey

    A reliable computational model of the human head is necessary for better understanding of the physical mechanisms of traumatic brain injury (TBI), car-crash investigation, development of protective head gear and advancement of dural replacement materials. The performance and biofidelity of these models depend largely on the material description of the different structures present in the head. One of these structures is the dura mater, the protective layer around the brain. We tested five human dura mater specimens, with samples at different locations, using planar biaxial tests. We describe the resulting stress-strain curves using both the anisotropic Gasser-Ogden-Holzapfel (GOH) model and the isotropic one-term Ogden model. The low-strain section of the curves is also described using a Neo-Hookean formulation. The obtained stress-strain curves reveal highly nonlinear but isotropic behaviour. A significant amount of inter- and intra-specimen variability is noticed, whereby the latter does not seem to be influenced by location. The GOH model achieves the best fit of the individual test data. A simple Neo-Hookean model can only be used with extreme caution, as it does not manage to capture the nonlinear effects present even at low strains.

    更新日期:2017-12-27
  • Quasi-static tensile properties of the Cranial Cruciate Ligament (CrCL) in adult cattle: towards the design of a prosthetic CrCL
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-26
    Lucien Diotalevi, Yvan Petit, Vladimir Brailovski, Sylvain Nichols, Emma Marchionatti, Éric Wagnac
    更新日期:2017-12-27
  • Damage mechanisms in bioactive glass matrix composites under uniaxial compression
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-24
    Qifeng Jiang, Jewan Ismail, Fahmi Zaïri, Zhengwei Qu, Xiaobing Liu, Fahed Zaïri

    The damage and crack resistance improvement of bioactive glass is of prime importance, particularly when applied to the repair of load-bearing bones. The present contribution is focused on the prediction of damage mechanisms and crack resistance under uniaxial compression of bioactive glass matrix composites reinforced with a particulate phase. In order to characterize the effects of voids and particles on the damage mechanisms and the macro-response, a two-step homogenization is performed by considering the two phases existing at two different scales: micro/meso through the homogenization of the porous matrix and then meso/macro through the periodic micro-field approach. The damage in the bioactive glass matrix is computed via an anisotropic stress-based damage model, implemented into a finite element program. Failure resulting of excessive damage accumulation in the bioactive glass matrix is predicted by a critical damage criterion combined with a vanishing element technique. The implication of particles in the toughening mechanism as well as the damage and crack resistance improvement in this class of porous biomaterials is highlighted via a parametric study using the proposed numerical model.

    更新日期:2017-12-27
  • Rate Dependent Anisotropic Constitutive Modeling of Brain Tissue Undergoing Large Deformation
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-24
    Krishnendu Haldar, Chinmoy Pal

    This study aims constitutive modeling of rate dependent anisotropic viscoelastic brain tissue that experiences large deformation during accidental impact. Many experimental studies confirm that brain parenchyma mechanisms are strongly influenced by anisotropy, nonlinear viscoelasticity, rate dependent loading/unloading and tension-compression asymmetry of the soft brain tissues. We present a rigorous thermodynamically consistent phenomenological approach to capture these mechanisms in a single model. Model parameters are calibrated from the experiments, and mechanical responses are predicted for different loading conditions. We consider a 2-D fibrous circular tube geometry, an idealized form of a human head, to simulate shear stress distribution for a given boundary condition. Different orientations of the fibers are considered to investigate the influence of anisotropy on the shear stress. Finally, stretch rate dependency of stress responses for a particular fiber orientation is demonstrated.

    更新日期:2017-12-27
  • Generalization of exponential based hyperelastic to hyper-viscoelastic model for investigation of mechanical behavior of rate dependent materials
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-23
    K. Narooei, M. Arman

    In this research, the exponential stretched based hyperelastic strain energy was generalized to the hyper-viscoelastic model using the heredity integral of deformation history to take into account the strain rate effects on the mechanical behavior of materials. The heredity integral was approximated by the approach of Goh et al. to determine the model parameters and the same estimation was used for constitutive modeling. To present the ability of the proposed hyper-viscoelastic model, the stress-strain response of the thermoplastic elastomer gel tissue at different strain rates from 0.001 to 100 /s was studied. In addition to better agreement between the current model and experimental data in comparison to the extended Mooney-Rivlin hyper-viscoelastic model, a stable material behavior was predicted for pure shear and balance biaxial deformation modes. To present the engineering application of current model, the Kolsky bars impact test of gel tissue was simulated and the effects of specimen size and inertia on the uniform deformation were investigated. As the mechanical response of polyurea was provided over wide strain rates of 0.0016 to 6500 /s, the current model was applied to fit the experimental data. The results were shown more accuracy could be expected from the current research than the extended Ogden hyper-viscoelastic model. In the final verification example, the pig skin experimental data was used to determine parameters of the hyper-viscoelastic model. Subsequently, a specimen of pig skin at different strain rates was loaded to a fixed strain and the change of stress with time (stress relaxation) was obtained. The stress relaxation results were revealed the peak stress increases by applied strain rate until the saturated loading rate and the equilibrium stress with magnitude of 0.281 MPa could be reached.

    更新日期:2017-12-27
  • In silico design of magnesium implants: macroscopic modelling
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-21
    J.A. Sanz-Herrera, E. Reina-Romo, A.R. Boccaccini

    Magnesium-based biomedical implants offer many advantages versus traditional ones although some challenges are still present. In this context, mathematical modeling and computational simulation may be a useful and complementary tool to evaluate in silico the performance of magnesium biomaterials under different conditions. In this paper, a phenomenologically-based model to simulate magnesium corrosion is developed. The model describes the physico-chemical interactions and evolution of species present in this phenomenon. A set of 7 species is considered in the model, which allows to simulate hydrogen release, pH evolution, corrosion products formation as well as degradation of magnesium. The model is developed under the continuum media theory and is implemented in a finite element framework. In the results section, the effect of model parameters on outcomes is firstly explored. Second, model results are qualitative validated versus two examples of application found in the literature. Two main conclusions are derived from this work: (i) the model captures well the experimental trends and allows to analyze the main variables present in magnesium corrosion, (ii) even though further validation is needed the model may be a useful standard in the design of degradable metal implants.

    更新日期:2017-12-22
  • Mechanical Behaviour of Alginate-Gelatin Hydrogels for 3D Bioprinting
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-21
    Michael Di Guiseppe, Nicholas Law, Braeden Webb, Ryley Macrae, Lawrence J. Liew, Timothy B. Sercombe, Rodney J. Dilley, Barry J. Doyle

    Hydrogels comprised of alginate and gelatin have demonstrated potential as biomaterials in three dimensional (3D) bioprinting applications. However, as with all hydrogel-based biomaterials used in extrusion-based bioprinting, many parameters influence their performance and there is limited data characterising the behaviour of alginate-gelatin (Alg-Gel) hydrogels.Here we investigated nine Alg-Gel blends by varying the individual constituent concentrations. We tested samples for printability and print accuracy, compressive behaviour and change over time, and viability of encapsulated mesenchymal stem cells in bioprinted constructs.Printability tests showed a decrease in strand width with increasing concentrations of Alg-Gel. However due to the increased viscosity associated with the higher Alg-Gel concentrations, the minimum width was found to be 0.32 mm before blends became too viscous to print. Similarly, printing accuracy was increased in higher concentrations, exceeding 90% in some blends. Mechanical properties were assessed through uniaxial compression testing and it was found that increasing concentrations of both Alg and Gel resulted in higher compressive modulus. We also deemed 15 minutes crosslinking in calcium chloride to be sufficient. From our data, we propose a blend of 7%Alg-8%Gel that yields high printability, mechanical strength and stiffness, and cell viability. However, we found the compressive behavior of Alg-Gel to reduce rapidly over time and especially when incubated at 37 °C.Here we have reported relevant data on Alg-Gel hydrogels for bioprinting. We tested for biomaterial properties and show that these hydrogels have many desirable characteristics that are highly tunable. Though further work is needed before practical use in vivo can be achieved.

    更新日期:2017-12-22
  • Deformation regimes of collagen fibrils in cortical bone revealed by in situ morphology and elastic modulus observations under mechanical loading
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-16
    Peng-Fei Yang, Xiao-Tong Nie, Dong-Dong Zhao, Zhe Wang, Li Ren, Hui-Yun Xu, Joern Rittweger, Peng Shang
    更新日期:2017-12-16
  • Tailoring the mechanical and biodegradable properties of binary blends of biomedical thermoplastic elastomer
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-15
    Hui Ying Ang, Jingni Chan, Daniel Toong, Subbu S. Venkatraman, Chia Sing Joo, Ying Ying Huang
    更新日期:2017-12-16
  • Effect of ice-quenching after oxidation treatment on hardening of a Pd-Cu-Ga-Zn alloy for bonding porcelain
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-15
    Min-Jung Kim, Hye-Jeong Shin, Hyung-Il Kim, Yong Hoon Kwon, Hyo-Joung Seol

    This study examined the effect of ice-quenching after oxidation treatment on hardness change of a Pd-Cu-Ga-Zn metal-ceramic alloy during porcelain firing simulation. Although not statistically significant, the alloy was softened slightly during porcelain firing simulation with conventional slow cooling rate. On the other hand, the hardness increased significantly by ice-quenching instead of the slow cooling after oxidation (p<0.001). The gap in the final hardness depending on ice-quenching occurred in the matrix and plate-like precipitates but not in the particle-like structure without plate-like precipitates (p<0.05). The mechanism of ice-quenching after oxidation to prevent softening and induce hardening during porcelain firing simulation involved the more active precipitation and retardation of microstructural coarsening. In conclusion, for practical work on Pd-Cu-Ga-Zn alloys, the oxidation treatment followed by ice-quenching instead of slow cooling is recommended for the simultaneous oxidation and hardening effects on the alloy.

    更新日期:2017-12-16
  • Mathematical Modeling and Experimental Evaluation for the predication of single nanofiber modulus
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-10
    Fatemeh Jahanmard-Hosseinabadi, Mohammad Amani-Tehran, Mohamadreza Baghaban Eslaminejad

    Electrospun nanofibre matrixes are widely used as scaffolds for the regeneration of different tissues due to similarities with fibrous components of the extracellular matrix. These scaffolds could act as a substrate for inducing mechanical stimuli to cells. The main mechanical stimuli factor in nanofiber scaffolds for determining the cell behaviors is stiffness of single nanofibers. This paper especially highlights the finding that the young's modulus of single nanofibers can be obtained from aligned nanofibers matrix. It is assume that, the modulus of single nanofibers are equal to modulus of completely aligned nanofibers. However, due to difficulty of producing completely aligned nanofibers, the obtained modulus of single nanofiber wouldn’t have significant value. Therefore, we propose a new mathematical model to predict the stiffness of single nanofibers from non-perfectly aligned nanofibers matrix.

    更新日期:2017-12-14
  • Measurement of anisotropic mechanical properties in porcine brain white matter ex vivo using magnetic resonance elastography
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-09
    J.L. Schmidt, D.J. Tweten, A.A. Badachhape, A.J. Reiter, R.J. Okamoto, J.R. Garbow, P.V. Bayly
    更新日期:2017-12-14
  • Acellular dermal matrix collagen responds to strain by intermolecular spacing contraction with fibril extension and rearrangement
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-09
    Hannah C. Wells, Katie H. Sizeland, Nigel Kirby, Adrian Hawley, Stephen Mudie, Richard G. Haverkamp
    更新日期:2017-12-14
  • Fatigue and Damage of Porcine Pars Interarticularis during Asymmetric Loading
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-08
    Colin Bright, Stephen Tiernan, Fiona McEvoy, Pat Kiely
    更新日期:2017-12-14
  • A novel use of 3D printing model demonstrates the effects of deteriorated trabecular bone structure on bone stiffness and strength
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-07
    Meir Max Barak, Margaret Arielle Black

    Trabecular bone structure is crucial to normal mechanical behavior of bones. Studies have shown that osteoporosis negatively affects trabecular bone structure, mainly by reducing bone volume fraction (BV/TV) and thus increasing fracture risk. One major limitation in assessing and quantifying the effect of this structural deterioration is that no two trabecular structures are identical. Thus, when we compare a group of healthy bones against a different group of bones that experienced resorption (i.e. decreased BV/TV) we only discover an “average” mechanical effect. It is impossible to quantify the mechanical effect of individual structural deterioration for each sample, simply because we never have the same sample in both states (intact and deteriorated structure). 3D printing is a new technology that can assist in overcoming this issue. Here we report a preliminary study that compares a healthy 3D printed trabecular bone model with the same model after bone resorption was simulated. Since the deteriorated structural bone model is derived from the healthy one, it is possible to directly estimate (percentage wise) the decrease of tissue stiffness and strength as a result of bone resorption for this specific structure. Our results demonstrate that a relatively small decrease in BV/TV (about 8%) leads to a dramatic decrease in structural strength (24%) and structural stiffness (17%), (P<0.01). Structural strength decreased from an average of 9.14±2.85 MPa to 6.97±2.44 MPa, while structural stiffness decreased from an average of 282.5±63.4 N/mm to 233.8±51.2 N/mm. This study demonstrates that 3D printing is a novel and valuable tool for quantifying the effect of structural deterioration on the mechanical properties of trabecular bone. In the future, this approach may help us attain better personal fracture risk assessments by CT scanning, 3D printing and mechanically testing individual bone replicas from patients suffering excessive bone resorption.

    更新日期:2017-12-14
  • Normalized Frontal Impact Biofidelity Kinematic Corridors Using Post Mortem Human Surrogates
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-07
    Mike W.J. Arun, Prasannaah Hadagali, Frank Pintar, Narayan Yoganandan

    Due to reducing cost and powerful computing resources and the ability of finite element human body models (FEHBM) to predict human body response more realistically, they are gaining acceptance to be a substitute for mechanical surrogates. Unlike mechanical surrogates, FEHBM can realistically simulate human kinematics and kinetics. Moreover, an array of quantities can be directly measured from FEHBMs. However, similar to ATDs, in order to evaluate the biofidelity, these models must be validated using PMHS response corridors. Therefore, availability of such PMHS corridors that can be used to validate both ATD and FEHBM kinematics is of primary importance. The current study presents normalized biofidelity corridors of head CG, T1, T12, and sacrum accelerations using PMHS frontal sled tests that were previously conducted. In addition, rotational accelerations and displacements of the head are also presented. The experimental data were collected using four specimens. Each specimens were tested with non-injurious pulses using two different velocities (low: 3.6 m/s and medium: 6.9 m/s). These data were normalized using mass-based technique to represent mid-sized United States population. Using the normalized data, average and plus/minus one standard deviation response corridors were generated that can be used to evaluate the biofidelity of ATDs and FEHBMs.

    更新日期:2017-12-14
  • 更新日期:2017-12-14
  • Impact of strain rate on the hardness and elastic modulus of human tooth enamel
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-07
    Y.F. Zhang, J. Zheng, J.X. Yu, H.T. He

    Human tooth enamel is a natural biocomposite consisting of mineral units surrounded by a soft protein shell. The mechanical behaviors of enamel are closely associated with its structure. In this paper, the strain-rate dependent mechanical properties of enamel were investigated with nanoindentation techniques. Five constant strain rates (0.01 s−1, 0.03 s−1, 0.05 s−1, 0.1 s−1, 0.3 s−1) were used in this study. Results showed that the hardness and elastic modulus of enamel increased with increasing strain rate. These results indicate that the variation of hardness under different stain rates is associated with creep behavior of organic matrix in enamel. And indentation creep rate sensitivity of human enamel was measured with a value of 0.062. Moreover, the elastic module of enamel is dependent upon strain rate. Such rate dependence originates from the organic matrix which is sensitive to the strain rate. This behavior may be important in explaining the excellent toughness and energy absorption abilities of natural tooth structure.

    更新日期:2017-12-14
  • Fatigue performance of a high-strength, degradable calcium phosphate bone cement
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-06
    Ingrid Ajaxon, Anders Holmberg, Caroline Öhman-Mägi Cecilia Persson

    Calcium phosphate cements (CPCs) are clinically used as injectable materials to fill bone voids and to improve hardware fixation in fracture surgery. In vivo they are dynamically loaded; nonetheless little is known about their fatigue properties. The aim of this study was to, for the first time, investigate the fatigue performance of a high-strength, degradable (brushitic) CPC, and also evaluate the effect of cement porosity (by varying the liquid to powder ratio, L/P) and the environment (air at room temperature or in a phosphate buffered saline solution, PBS, at 37°C) on the fatigue life. At a maximum compressive stress level of 15 MPa, the cements prepared with an L/P-ratio of 0.22 and 0.28 ml/g, corresponding to porosities of approximately 12 and 20%, had a 100% probability of survival until run-out of 5 million cycles, in air. When the maximum stress level, or the L/P-ratio, was increased, the probability of survival decreased. Testing in PBS at 37°C led to more rapid failure of the specimens. However, the high-strength cement had a 100% probability of survival up to approximately 2.5 million cycles at a maximum compressive stress level of 10 MPa in PBS, which is substantially higher than some in vivo stress levels, e.g., those found in the spine. At 5 MPa in PBS, all specimens survived to run-out. The results found herein are important if clinical use of the material is to increase, as characterisation of the fatigue performance of CPCs is largely lacking from the literature.

    更新日期:2017-12-14
  • Porous architected biomaterial for a tibial-knee implant with minimum bone resorption and bone-implant interface micromotion
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-05
    Amirmohammad Rahimizadeh, Zahra Nourmohammadi, Sajad Arabnejad, Michael Tanzer, Damiano Pasini

    This investigation presents the numerical development of a fully porous tibial knee implant that is suggested to alleviate the clinical problems associated with current prostheses that are fully solid. A scheme combining multiscale mechanics and topology optimization is proposed to handle the homogenized analysis and property tailoring of the porous architecture with the aim of reducing the stiffness mismatch between the implant and surrounding bone. The outcome of applying this scheme is a graded lattice microarchitecture that can potentially offer the implant an improved degree of load bearing capacity while reducing concurrently bone resorption and interface micromotion. Asymptotic Homogenization theory is used to characterize the mechanics of its building block, a tetrahedron based unit cell, and the Soderberg fatigue criterion to represent the implant fatigue resistance under multiaxial physiological loadings. The numerical results suggest that the overall amount of bone resorption around the graded porous tibial stem is 26% lower than that around a conventional, commercially available, fully dense titanium implant of identical shape and size. In addition, an improved interface micromotion is observed along the tibial stem, with values at the tip of the stem as low as 17 μm during gait cycle and 22 μm for deep bend compared to a fully dense implant. This decrease in micromotion compared to that of an identical solid implant made of titanium can reasonably be expected to alleviate post-operative end of stem pain suffered by some patients undergoing surgery at the present time.

    更新日期:2017-12-14
  • Underbody blast effect on the pelvis and lumbar spine: A computational study
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-05
    Jianyin Lei, Feng Zhu, Binhui Jiang, Zhihua Wang

    Explosion from an anti-tank landmine under a military vehicle, known as underbody blast (UBB), may cause severe injury or even death for the occupants inside the vehicle. Severity and patterns of lower extremity, pelvis and lumbar spine injuries subjected to UBB have been found highly related to loading conditions, i.e. the vertical acceleration pulse. A computational human model has been developed and successfully simulated the tibia fracture under UBB in the previous study. In the present study, it was further improved by building a detailed lumbar spine and pelvis model with high biofidelity. The newly developed pelvis and lumbar spine were validated against component level test data in the literature. Then, the whole body model was validated with the published cadaver sled test data. Using the validated whole body model, parametric studies were conducted by adjusting the peak acceleration and time duration of pulses produced in the UBB to investigate the effect of waveform on the injury response. The critical values of these two parameters for pelvis and lumbar spine fracture were determined, and the relationship between injury pattern and loading conditions was established.

    更新日期:2017-12-14
  • Manipulating the Structure and Mechanical Properties of Thermoplastic Polyurethane/Polycaprolactone Hybrid Small Diameter Vascular Scaffolds Fabricated Via Electrospinning Using an Assembled Rotating Collector
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-01
    Hao-Yang Mi, Xin Jing, Emily Yu, Xiaofeng Wang, Qian Li, Lih-Sheng Turng

    The success of blood vessel transplants with vascular scaffolds (VSs) highly depends on their structure and mechanical properties. The fabrication of small diameter vascular scaffolds (SDVSs) mimicking the properties of native blood vessels has been a challenge. Herein, we propose a facile method to fabricate thermoplastic polyurethane (TPU)/polycaprolactone (PCL) hybrid SDVSs via electrospinning using a modified rotating collector. By varying the ratio between the TPU and the PCL, and changing the electrospinning volume, SDVSs with a wavy configuration and different properties could be obtained. Detailed investigation revealed that certain TPU/PCL hybrid SDVSs closely resembled the mechanical behaviors of blood vessels due to the presence of a wavy region and the combination of flexible TPU and rigid PCL, which mimicked the properties of elastin and collagen in blood vessels. The fabricated TPU/PCL SDVSs achieved lumen diameters of 1 ~ 3 mm, wall thicknesses of 100 ~ 570 μm, circumferential moduli of 1 ~ 6 MPa, ultimate strengths of 2 ~ 8 MPa, over 250% elongation-at-break values, toe regions of 5.3 ~ 9.4%, high recoverability, and compliances close to those of human veins. Moreover, these TPU/PCL SDVSs possessed sufficient suture retention strength and burst pressure to fulfill transplantation requirements and maintain normal blood flow. Human endothelial cell culture revealed good biocompatibility of the scaffolds, and cells were able to grow on the inner surface of the tubular scaffolds, indicating promising prospects for use as tissue-engineered vascular grafts.

    更新日期:2017-12-14
  • Bladder wall biomechanics: A comprehensive study on fresh porcine urinary bladder
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-11-28
    Maryam Sami Jokandan, Fatemeh Ajalloueian, Magnus Edinger, Peter Reimer Stubbe, Stefania Baldursdottir, Ioannis S. Chronakis
    更新日期:2017-12-14
  • Hybrid micro/nanostructural surface offering improved stress distribution and enhanced osseointegration properties of the biomedical titanium implant
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-11-27
    Ping-Jen Hou, Hsin-Hua Chou, Chin-Chieh Wang, Chiung-Fang Huang, Erwan Sugiatno, Tzu-Sen Yang, Keng-Liang Ou

    Objectives The aim of the present study was to investigate the surface characteristic, biomechanical behavior, hemocompatibility, bone tissue response and osseointegration of the optimal micro-arc oxidation surface-treated titanium (MST-Ti) dental implant. Materials and Methods The surface characteristic, biomechanical behavior and hemocompatibility of the MST-Ti dental implant were performed using scanning electron microscope, finite element method, blood dripping and immersion tests. The mini-pig model was utilized to evaluate the bone tissue response and osseointegration of the MST-Ti dental implant in vivo. Data were analyzed by analysis of variance using the Student's t-test (P ≤ 0.05). Results The hybrid volcano-like micro/nanoporous structure was formed on the surface of the MST-Ti dental implant. The hybrid volcano-like micro/nanoporous surface played an important role to improve the stress transfer between fixture, cortical bone and cancellous bone for the MST-Ti dental implant. Moreover, the MST-Ti implant was considered to have the outstanding hemocompatibility. In vivo testing results showed that the bone-to-implant contact (BIC) ratio significantly altered as the implant with micro/nanoporous surface. After 12 weeks of implantation, the MST-Ti dental implant group exhibited significantly higher BIC ratio than the untreated dental implant group. In addition, the MST-Ti dental implant group also presented an enhancing osseointegration, particularly in the early stages of bone healing. Conclusion It can be concluded that the micro-arc oxidation approach induced the formation of micro/nanoporous surface is a promising and reliable alternative surface modification for Ti dental implant applications.

    更新日期:2017-12-14
  • Surface Structure and Tribology of Legless Squamate Reptiles
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-11-08
    Hisham A. Abdel-Aal

    Squamate reptiles (around 10,000 species of snakes and lizards) comprise a myriad of distinct terrestrial vertebrates. The diversity within this biological group offers a great opportunity for customized bio-inspired solutions that address a variety of current technological problems especially within the realm of surface engineering and tribology. One subgroup within squamata is of interest in that context, namely the legless reptiles (mainly snakes and few lizards). The promise of that group lies within their functional adaptation as manifested in optimized surface designs and locomotion that is distinguished by economy of effort even when functioning within hostile tribological environments. Legless reptiles are spread over a wide range in the planet, this geographical diversity demands customized response to local habitats. Customization, in turn, is facilitated through specialized surface design features. In legless reptiles, micro elements of texture, their geometry and topological layout advance mitigation of frictional effects both in locomotion and in general function. Lately, the synergy between functional traits and intrinsic surface features has emerged as focus of research across disciplines. Many investigations have sought to characterize the structural as well as the tribological response of legless species from an engineering point of view. Despite the sizable amount of data that have accumulated in the literature over the past two decades or so, no effort to review the available information, whence this review. This manuscript, therefore, endeavors to assess available data on surface metrology and tribological behavior of legless reptiles and to define aspects of that performance necessary to formulate an advanced paradigm for bio-inspired surface engineering.

    更新日期:2017-12-14
  • Investigation of micromechanical properties of hard sphere filled composite hydrogels by atomic force microscopy and finite element simulations
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-10-31
    Guanlin Tang, Massimiliano Galluzzi, Chandra Sekhar Biswas, Florian J. Stadler

    Atomic force microscopy (AFM) indentation is the most suitable way to characterize micromechanical properties of soft materials such as bio tissues. However, the mechanical data obtained from force-indentation measurement are still not well understood due to complex geometry of the bio tissue, nonlinearity of indentation contact, and constitutive relation of hyperelastic soft material. Poly-N-isopropyl acrylamide (PNIPAM) filled with 5 wt. % polystyrene (PS) sphere particles material system can be utilized as a simplified model for mimicking a whole host of soft materials. Finite element model has been constructed to simulate indentation as in AFM experiments using colloidal probes for a parametric study, with the main purpose of understanding the effect of particles on overall behavior of mechanical data and local deformation field under indentation contact. Direct comparison between finite element simulation and indentation data from AFM experiments provides a powerful method to characterize soft materials properties quantitatively, addressing the lack of analytical solutions for hard-soft composites, both biological and synthetic ones. In this framework, quantitative relations are found between the depth, at which the particle was embedded, the particle size and the elastic modulus of the overall composite. Comprehensive characterizations were established to distinguish indentation on a particle residing on top of the hydrogel from a particle embedded inside the hydrogel matrix. Finally, different assumptions of interface friction at the boundary between the particle and the hydrogel have been tested and directly compared with experimental measurements.

    更新日期:2017-12-14
  • In vitro biomechanical and hydrodynamic characterisation of decellularised human pulmonary and aortic roots
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-09-14
    A. Desai, T. Vafaee, P. Rooney, J.N. Kearney, H.E. Berry, E. Ingham, J. Fisher, L.M. Jennings

    Background and purpose of the study The use of decellularised biological heart valves in the replacement of damaged heart valves offers a promising solution to reduce the degradation issues associated with existing cryopreserved allografts. The purpose of this study was to assess the effect of low concentration sodium dodecyl sulphate decellularisation on the in vitro biomechanical and hydrodynamic properties of cryopreserved human aortic and pulmonary roots. Method The biomechanical and hydrodynamic properties of cryopreserved decellularised human aortic and pulmonary roots were fully characterised and compared to cellular human aortic and pulmonary roots in an unpaired study. Following review of these results, a further study was performed to investigate the influence of a specific processing step during the decellularisation protocol (‘scraping’) in a paired comparison, and to improve the method of the closed valve competency test by incorporating a more physiological boundary condition. Results The majority of the biomechanical and hydrodynamic characteristics of the decellularised aortic and pulmonary roots were similar compared to their cellular counterparts. However, several differences were noted, particularly in the functional biomechanical parameters of the pulmonary roots. However, in the subsequent paired comparison of pulmonary roots with and without decellularisation, and when a more appropriate physiological test model was used, the functional biomechanical parameters for the decellularised pulmonary roots were similar to the cellular roots. Conclusion Overall, the results demonstrated that the decellularised roots would be a potential choice for clinical application in heart valve replacement.

    更新日期:2017-12-14
  • Indentation of heterogeneous soft tissue: Local constitutive parameter mapping using an inverse method and an automated rig
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-04-02
    B. Pierrat, D.B. MacManus, J.G. Murphy, M.D. Gilchrist

    In the domain of soft tissue biomechanics, the development of numerical simulations has raised the experimental challenge of identifying local internal mechanical constitutive data of heterogeneous organs (e.g. brain tissue). In this context, this paper presents an ex-vivo alternative characterization method to full-field imaging techniques. It is based on automated, multiple indentations of an organ section using a custom-built rig, effectively allowing to map the viscoelastic and hyperelastic constitutive parameters of the tissue at the millimetre scale, under dynamic conditions. In this paper, this technique is described and used to map the constitutive data of three sections from porcine liver, kidney and brain tissues. The results of this mapping present strong evidence of correlation between the organ constituents (e.g. white/grey matter distribution) and the identified constitutive parameters. It was also found that brain and kidney tissues are highly heterogeneous in terms of identified properties, suggesting that such a technique is essential for fully characterizing their mechanical behaviour. This method opens the way to 3D mapping of constitutive parameters to feed finite element models of the organs with region-specific properties.

    更新日期:2017-12-14
  • Normalized Frontal Impact Biofidelity Kinematic Corridors Using Post Mortem Human Surrogates
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-07
    Mike W.J. Arun, Prasannaah Hadagali, Frank Pintar, Narayan Yoganandan

    Due to reducing cost and powerful computing resources and the ability of finite element human body models (FEHBM) to predict human body response more realistically, they are gaining acceptance to be a substitute for mechanical surrogates. Unlike mechanical surrogates, FEHBM can realistically simulate human kinematics and kinetics. Moreover, an array of quantities can be directly measured from FEHBMs. However, similar to ATDs, in order to evaluate the biofidelity, these models must be validated using PMHS response corridors. Therefore, availability of such PMHS corridors that can be used to validate both ATD and FEHBM kinematics is of primary importance. The current study presents normalized biofidelity corridors of head CG, T1, T12, and sacrum accelerations using PMHS frontal sled tests that were previously conducted. In addition, rotational accelerations and displacements of the head are also presented. The experimental data were collected using four specimens. Each specimens were tested with non-injurious pulses using two different velocities (low: 3.6 m/s and medium: 6.9 m/s). These data were normalized using mass-based technique to represent mid-sized United States population. Using the normalized data, average and plus/minus one standard deviation response corridors were generated that can be used to evaluate the biofidelity of ATDs and FEHBMs.

    更新日期:2017-12-08
  • Impact of strain rate on the hardness and elastic modulus of human tooth enamel
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-12-07
    Y.F. Zhang, J. Zheng, J.X. Yu, H.T. He

    Human tooth enamel is a natural biocomposite consisting of mineral units surrounded by a soft protein shell. The mechanical behaviors of enamel are closely associated with its structure. In this paper, the strain-rate dependent mechanical properties of enamel were investigated with nanoindentation techniques. Five constant strain rates (0.01 s−1, 0.03 s−1, 0.05 s−1, 0.1 s−1, 0.3 s−1) were used in this study. Results showed that the hardness and elastic modulus of enamel increased with increasing strain rate. These results indicate that the variation of hardness under different stain rates is associated with creep behavior of organic matrix in enamel. And indentation creep rate sensitivity of human enamel was measured with a value of 0.062. Moreover, the elastic module of enamel is dependent upon strain rate. Such rate dependence originates from the organic matrix which is sensitive to the strain rate. This behavior may be important in explaining the excellent toughness and energy absorption abilities of natural tooth structure.

    更新日期:2017-12-08
  • Mechanical, Corrosion and Biocompatibility Behaviour of Mg-3Zn-HA Biodegradable Composites for Orthopaedic Fixture Accessories
    J. Mech. Behav. Biomed. Mater. (IF 3.11) Pub Date : 2017-11-21
    Satish Jaiswal, R. Manoj Kumar, Pallavi Gupta, Murali Kumaraswamy, Partha Roy, Debrupa Lahiri

    Development of biodegradable implants has grown into one of the important areas in medical science. Degradability becomes more important for orthopaedic accessories used to support fractured and damaged bones, in order to avoid second surgery for their removal after healing. Clinically available biodegradable orthopaedic materials are mainly made of polymers or ceramics. These orthopaedic accessories have an unsatisfactory mechanical strength, when used in load-bearing parts. Magnesium and its alloys can be suitable candidate for this purpose, due to their outstanding strength to weight ratio, biodegradability, non-toxicity and mechanical properties, similar to natural bone. The major drawback of magnesium is its low corrosion resistance, which also influences its mechanical and physical characteristics in service condition. An effort has been taken in this research to improve the corrosion resistance, bioactivity and mechanical strength of biodegradable magnesium alloys by synthesizing Mg-3 wt% Zn matrix composite, reinforced with thermally treated hydroxyapatite(HA) [Ca10(PO4)6(OH)2], a bioactive and osteogenic ceramic. Addition of 5 wt% HA is found effective in reducing the corrosion rate by 42% and improvement in the compressive yield strength of biodegradable magnesium alloy by 23%. In-vitro evaluation, up to 56 days, reveal improved resistance to degradation with HA reinforcement to Mg. Osteoblast cells show better growth and proliferation on HA reinforced surfaces of the composite. Mg-HA composite structure shows impressive potential to be used in orthopaedic fracture fixing accessories.

    更新日期:2017-12-08
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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