Acta of bioengineering and biomechanics最新文献

Purpose: The aim of this study was to reveal the first time synergistic effect of GP and selenium (Se) on 3T3 cells seeded on natural and non-cytotoxic porous scaffolds with poly(vinyl alcohol) (PVA) and gelatin (GE).

Methods: Electrospinning scaffolds were produced as PVA/GE/GA crosslinked with glutaraldehyde (GA) and freeze/dried scaffolds crosslinked with genipin (GP) were divided into two groups as PVA/GE/GP5 and PVA/GE/GP8. The scaffolds were investigated in terms of pore morphology, swell ratio, biodegradation, and biocompatibility. The biocompatibility of the material was tested in vitro by MTT assay on 1, 2, and 3 days to test the cell viability of 3T3 cells.

Results: It was observed that Se triggered the excellent cell growth and proliferation on electrospinning and freeze drying PVA/GE scaffolds.

Conclusions: Selenium with PVA/GE scaffolds can be a promising candidate for wound healing application, as it significantly increases cell viability on scaffolds. It is thought that the synergistic effect of selenium with genipin may be an important step in tissue engineering applications. The preliminary study can be supported by in vivo studies in the future.

Purpose: This study examined the use of nonlinear measures - sample entropy (SampEn), fractal dimension (FD), and the Lyapunov exponent (LyE) - to evaluate postural control in adults during standing on an unstable surface, with and without visual feedback.

Methods: 14 healthy young adults (24.07 ± 7.32 years) completed bipedal standing trials on an unstable-plate Biodex Balance System (BBS) connected to a Vicon system, with eyes open and closed. Each trial lasted 20 sec. Analysis was performed based on the center of mass (CoM), for which the three nonlinear measures were calculated.

Results: Excluding visual feedback was found to cause a significant increase in linear and nonlinear parameters. Moreover, SampEn and FD values were found to be significantly higher in the PD direction, compared to AP or ML, whereas LyE values in this direction were minimal.

Conclusions: Results show that the three nonlinear measures provide a useful way of evaluating postural control in healthy adults. Moreover, it seems that introducing an unstable surface meant that the projection of the CoM was not perpendicular to the surface, but rather set at a certain continually changing angle, forcing the whole system to adapt to chaotic and unpredictable conditions. Such refined changes in conditions can be evaluated in a precise way only by using nonlinear measures.

As it is widely stated in the literature, biofilms are responsible for most chronic infections, which have grown exponentially over the past three decades. The use of so-called alloys, as a new generation of materials, enables us to find the golden mean in the arena widely known as implantology. The use of the surface layer, using the chosen Atomic Layer Deposition method, is to be the basis for minimizing the risk of an organism reactions. Therefore, the primary objective of this study was to observe the impact of physicochemical properties of the surface layers (bactericidal) on the processes that occur on the implants surface made of titanium biomaterials used in bone structures. The study also attempted to evaluate the physicochemical properties of the ZnO coatings, deposited on the substrate of one of the new generation Ti13Nb13Zr alloys, using the ALD method. Included in the assessment of the physicochemical properties of the surface layers formed in this manner, we perform pitting corrosion resistance tests, scratch tests, tribological tests and surface wettability tests. Based on the obtained data, the differing physicochemical properties of the alloy with ZnO coatings are found to be dependent on the applied surface modification. For the conducted tests, differences are determined for the tests on the corrosion resistance, surface wettability and the abrasion resistance for samples with and without the ZnO coating. In addition, tests show that the coating applied to the alloy, which is previously subjected to the sand-blasted process, is characterized by improved adhesion.

Poly(3-hydroxybutyrate) (P3HB) is the most important of the polyhydroxyalkanoates. It is biosynthesized, biodegradable, biocompatible, and shows no cytotoxicity and mutagenicity. P3HB is a natural metabolite in the human body and, therefore, it could replace the synthetic, hard-to-degrade polymers used in the production of implants. However, P3HB is a brittle material with limited thermal stability. Therefore, in order to improve its mechanical properties and processing parameters by separating its melting point and degradation temperature, P3HB-based composites can be produced using, for example, linear aliphatic polyurethanes as modifiers. The aim of the study is a modification of P3HB properties with the use of linear aliphatic polyurethanes synthesized in reaction of hexamethylene diisocyanate (HDI) and polypropylene glycols (PPG) by producing their composites. Prepared biocomposites were tested by the scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TGA). Furthermore, selected mechanical properties were evaluated. It has been confirmed that new biocomposites showed an increase in impact strength, relative strain at break, decrease of hardness and higher degradation temperature compared to the unfilled P3HB. The biocomposites also showed a decrease in the glass transition temperature and the degree of crystallinity. Biocomposites obtained with 10 wt. % polyurethane synthesized with polypropylene glycol having 1000 g ⋅ mole-1 and HDI have the best thermal and mechanical properties.

Purpose: Although inertial measurement unit (IMU)-based systems have been validated against optoelectronic systems for recording joint kinematics, the accuracy of each system must be evaluated, and measurements from different systems cannot be easily compared. Therefore, this study compared the joint angles recorded using the IMU-based MyoMotion system and the optoelectronic BTS Smart-DX 700 system during Nordic walking.

Methods: The study subject, a long-time Nordic walking instructor, was assigned to walk 12 m/trial (14 trials with 5 sampled gait cycles) at a velocity preferred for Nordic walking. The trials were simultaneously recorded by both systems. The instantaneous lower (ankle, knee, hip) and upper (shoulder, elbow, wrist) limb joint angles were recorded.

Results: The joint angles from MyoMotion were significantly larger or smaller (depending on the joint and plane) than those from BTS.

Conclusions: Joint angles measured by MyoMotion are not interchangeable with values from BTS, and IMU-recorded values should be interpreted carefully. However, MyoMotion can still provide information about intra-individual changes based on the joint angle profiles, e.g., following Nordic walking training.

Purpose: The present study aims to investigate the effect of incline and decline walking on ground and joint reaction forces (JRF) of lower extremity and plantar fascia strain (PFS) under certain surface inclination angles.

Methods: Twenty-three male subjects walked on a customized platform with four different surface inclinations (i.e., 0, 5, 7.5 and 10°) with inclined and declined directions. The motion of the ten reflective markers was captured using Qualysis motion capture system (Qualysis, Gothenburg, Sweden) and exported to a visual three-dimensional (3D) software (C-motion, Germantown, USA) in order to analyze the GRF, JRF and PFS.

Results: The results found that the peak vertical GRF is almost consistent for 0 and 5° inclination slope but started to decrease at 7.5° onwards during decline walking. The most affected JRF was found on knee at medial-lateral direction even as low as 5 to 10° inclination for both walking conditions. Furthermore, the findings also show that the JRF of lower extremity was more affected during declined walking compared to inclined walking based on the number of significant differences observed in each inclination angle. The PFS was found increased with the increase of surface inclination.

Conclusions: The findings could provide a new insight on the relationship of joint reaction forces and strain parameter in response to the incline and decline walking. It would benefit in providing a better precaution that should be considered during hiking activity, especially in medial-lateral direction in order to prevent injury or fall risk.