Journal of Biomechanical Science and Engineering
Online ISSN : 1880-9863
ISSN-L : 1880-9863
Volume 8, Issue 4
Displaying 1-6 of 6 articles from this issue
Papers
  • Jonas A. PRAMUDITA, Kyoji WATANABE, Yuji TANABE
    2013 Volume 8 Issue 4 Pages 293-305
    Published: 2013
    Released on J-STAGE: December 09, 2013
    JOURNAL FREE ACCESS
    Whiplash Associated Disorder (WAD) in rear collision accident is difficult to recognize from X-ray images. However, recent clinical studies have mentioned that this injury occurs due to minor rupture in the cervical facet joint capsular ligament. In this study, porcine cervical facet joint capsular ligaments were subjected to quasi-static tensile loading to determine their strength at different loading rates and cervical segment location. Test specimens were obtained by dividing half-cut porcine cervical spine into five cervical segments (C2-C3 to C6-C7) and cutting off all of the soft connective tissues, except the facet joint capsular ligament. These specimens were fixed at both ends inside the cup-like jigs filled with polyurethane resin, and were then subject to tensile loading on the axial direction of the vertebrae at three different loading rates (50, 250 and 500 mm/min) using a universal testing machine. Influence of loading rate and cervical segment location on the strength and stiffness of the ligament were found to be insignificant. Furthermore, tensile strength and stiffness of the porcine cervical facet joint capsular ligament were considered to be similar to the cervical facet joint capsular ligament of human cadaver reported in other studies. It indicates that porcine cervical facet joint capsular ligament is suitable for replacing human cervical facet joint capsular ligament during mechanical testing.
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  • Kosaku KURATA, Ryo UENO, Masahiro MATSUSHITA, Takanobu FUKUNAGA, Hiros ...
    2013 Volume 8 Issue 4 Pages 306-318
    Published: 2013
    Released on J-STAGE: December 09, 2013
    JOURNAL FREE ACCESS
    Irreversible electroporation (IRE) is attracting much attention as a less-invasive therapy to ablate abnormal tissues. With a pair of electrodes inserted into the tissue, the IRE perforates the targeted cells non-thermally by a train of intensive electric pulses that exceeds a certain threshold. Since only the cells are necrotized percutaneously, the extracellular matrix is kept intact in the IRE, which is favorable for prompt tissue regeneration. In this study, we demonstrated that the IRE is also applicable to treat superficial targets such as melanoma, nevus, and tumors on gastrointestinal surface. A pair of 1-mm dia. stainless steel rods fixed 5 mm apart in an acrylic plate was contacted on an agarose gel containing fibroblasts. A sequence of 15 to 90 pulses of 1 kV was then applied to the gel via electrodes. All pulses were 10 μs in length and oscillated at 100 ms intervals. The boundary between dead and alive cell regions was determined at the surface and vertical cross section by using fluorescent staining. The necrotic cell area was also predicted by a numerical solution to the equation of electric field. Those determined with an assumption that the potential difference of 1 V between the cell membrane induces irreversible cell breakdown agreed well with the necrotic cell area and maximal depth in the experiment at low pulse number. However, the experiment showed the increase in the necrotic area with increasing the pulse repetition. Since application of multiple pulses perforates the highly resistive cell membrane, our study indicated the importance of taking into account the change in the electrical properties due to cell destruction.
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    ★Paper of the Year 2013

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  • Jason SANDERSON, Nobuki MURAYAMA, Yoshitaka NAKANISHI
    2013 Volume 8 Issue 4 Pages 319-327
    Published: 2013
    Released on J-STAGE: December 09, 2013
    JOURNAL FREE ACCESS
    The present study uses finite element analysis (FEA) to compare an original long bone plate design consisting of a titanium alloy reinforced polyetheretherketone (PEEK) biomaterial with fracture plates made from a standard titanium alloy. The original plate design consists of carbon reinforced PEEK with several independent, cylindrical, titanium reinforcements spanning the length and width of the plate. Standard plates are equivalent in dimension to reinforced PEEK plates but are made of solid titanium alloy. An anatomically correct human tibia model is used to create two bone fragments, proximal and distal, simulating a simple transverse fracture. The construct is loaded proximally upon the medial and lateral tibia plateaus and fixed distally at the talocrural joint surface. Screw-plate contact conditions are defined as “bonded” to simulate locking screws, and screw-bone contacts are “separation-no sliding” to simulate the ability of the screw to pull away from but not slide along the bone-screw interface. The FEM analysis showed that the reinforced PEEK implants are successful in reducing stress shielding and average screw stress across all constructs when compared to standard Ti-alloy plates. The reinforced plates also allow micro-motion, which is conducive to secondary healing, whereas the standard plates inhibit this type of motion.
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  • Satoko HIRABAYASHI, Tomonari TSUCHIDA, Eiichi TANAKA, Koji MIZUNO
    2013 Volume 8 Issue 4 Pages 328-343
    Published: 2013
    Released on J-STAGE: December 24, 2013
    JOURNAL FREE ACCESS
    Past researches that evaluated hip fracture risk had focused on sideways falls, while backward falls were also reported to cause as many hip fractures as the sideways falls do. To understand the mechanism of hip fracture during a backward fall, we conducted fall simulations using a “Multi-body and Finite-element Coupled Human Model”. This model was effective and efficient in simulating both the kinematic behavior of the whole body and the stress distribution around the femoral neck simultaneously and in evaluating hip fracture risk resulting from the fall. In the simulations, the lateral area of the greater trochanter contacted the floor in the sideways fall, and the proximal top of the greater trochanter contacted the floor in the backward fall with the upper body tilted laterally. In the backward fall, the impact velocity and the contact force with the floor were low. However, as the geometrical relationship among the femur, hip joint, and pelvis made the contact force work more efficiently, the shearing force and the torsional moment in the femoral neck were large and the maximum values of each stress were the same or higher as compared to that of the sideways fall. Besides, the pubic rami are likely to break and thereby prevent a femoral neck fracture in the sideways fall, but not while in the backward fall. This result shows that the risk of a hip fracture in the backward fall is the same or even higher than that in the sideways fall.
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  • Masateru MAEDA, Hao LIU
    2013 Volume 8 Issue 4 Pages 344-355
    Published: 2013
    Released on J-STAGE: December 24, 2013
    JOURNAL FREE ACCESS
    In very few studies it is shown that an increase in vertical force can be achieved when a flapping-wing hovers in ground effect (IGE). The body, however, has usually been neglected and its influence on three-dimensional vortex structures and consequent aerodynamic forces is still unclear. In this study we carried out a computational fluid dynamic study of a fruit fly (Drosophila melanogaster) hovering for two cases: “in ground effect” and “out of ground effect” (OGE), where the heights from the ground are less than one and more than five times the wing length, respectively. The wings in the IGE computation generated merely 0.7% larger wingbeat cycle-averaged vertical force than in the OGE condition. The body, in contrast, exhibited a significant increase in the vertical force: when out of ground effect, the average vertical force of the body was almost zero (-0.0025 μN); whereas in ground effect, the force increased to 0.78 μN, which is the major contributor to the 8.5% increase in the total vertical force (from 9.9 μN at OGE to 10.8 μN at IGE). Meanwhile, the aerodynamic power of the wings decreased by 1.6%, resulting in a 10% improvement in the overall vertical force-to-aerodynamic power ratio. The flow-field visualization revealed that the downwashes generated by the wings create a high pressure “air cushion” underneath the body, which should be responsible for the enhancement of the body vertical force production. Our results point to the importance of the presence of body in predicting the vertical forces in flapping flights in ground effect.
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    ★Graphics of the Year 2013

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