The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade. This review takes stock of the recent advances in ...research pertaining to different aspects of tribology within the last 2 to 3 years. Different aspects of tribology that have been reviewed including lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology. This review attempts to highlight recent research and also presents future outlook pertaining to these aspects. It may however be noted that there are limitations of this review. One of the most important of these is that tribology being a highly multidisciplinary field, the research results are widely spread across various disciplines and there can be omissions because of this. Secondly, the topics dealt with in the field of tribology include only some of the salient topics (such as lubrication, wear, surface engineering, biotribology, high temperature tribology, and computational tribology) but there are many more aspects of tribology that have not been covered in this review. Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.
Poly-ether-ether-ketone (PEEK) fabricated by fused deposition modeling for medical applications was evaluated in terms of mechanical strength and in vitro cytotoxicity in this study. Orthogonal ...experiments were firstly designed to investigate the significant factors on tensile strength. Nozzle temperature, platform temperature, and the filament diameter were tightly controlled for improved mechanical strength performance. These sensitive parameters affected the interlayer bonding and solid condition in the samples. Fourier transform infrared (FTIR) spectrometry analysis was secondly conducted to compare the functional groups in PEEK granules, filaments, and printed parts. In vitro cytotoxicity test was carried out at last, and no toxic substances were introduced during the printing process.
The pore size of porous scaffold plays a critical role in bone regeneration, but its mechanism and optimal value remain unclear. This study investigated the effect of pore size on hydromechanical ...properties of porous scaffold and its correlation with cellular response and bone regeneration. Porous titanium scaffolds with similar porosity and different pore sizes (400, 650, 850, and 1100 μm) were fabricated by selective laser melting. Their hydromechanical properties were derived by computational fluid dynamics analysis. The MC3T3 cells were dynamic seeded and cultured on the scaffolds to evaluate the cellular response. The rabbit distal femoral condyle implantation models were used to assess the bone ingrowth. Results indicated that the permeability, flow velocity, and the inflow of fluid linearly increased with the pore size. The wall shear stress evaluated from 400 to 650 μm and then dropped. These changes induced various performances in cell penetration, adhesion, proliferation, and differentiation, and finally induced best bone ingrowth in scaffold with pore size of 650 μm. This study provided a new understanding of the effect of pore size on bone regeneration of porous scaffold from the perspective of hydromechanics and indicated the potential of combining computational simulation and laboratory experiments in future studies.
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•Increasing the pore size linearly increased the permeability, flow velocity, and inflow of fluid.•The shear stress first increased and then decreased with the increase in pore size.•The pore size significantly affected the cell penetration, adhesion, proliferation, differentiation, and bone ingrowth.•The hydromechanical properties closely correlated with the cellular response and bone regeneration
Numerous medical devices have been applied for the treatment or alleviation of various diseases. Tribological issues widely exist in those medical devices and play vital roles in determining their ...performance and service life. In this review, the bio-tribological issues involved in commonly used medical devices are identified, including artificial joints, fracture fixation devices, skin-related devices, dental restoration devices, cardiovascular devices, and surgical instruments. The current understanding of the bio-tribological behavior and mechanism involved in those devices is summarized. Recent advances in the improvement of tribological properties are examined. Challenges and future developments for the prospective of bio-tribological performance are highlighted.
Phytoremediation is an effective approach to control soil heavy metal pollution. This study isolated a fungus strain from soils contaminated by cadmium (Cd) and lead (Pb) in Zhalong Wetland (China), ...which was identified as Simplicillium chinense QD10 via both genotypic and phenotypic analysis. The performance and mechanism of S. chinense QD10 in Cd and Pb adsorption was unraveled by morphological analysis and biosorption test, and its roles in ameliorating phytoremediation by Phragmites communis were tested in pot-experiments. Cd biosorption was attributed to the formation of Cd-chelate, whereas Pb was predominantly adsorbed by extracellular polymeric substances. Metal biosorption followed Langmuir isotherm, and the maximum biosorption capacity was 88.5 and 57.8 g/kg for Cd and Pb, respectively. Colonized in soils, such biosorption behavior of S. chinense QD10 can generate gradients of available Cr or Pb and drive their enrichment. Accordingly, S. chinense QD10 amendment significantly enhanced the phytoextraction of Cd and Pb by P. communis, possibly attributing to rhizospheric enrichment of Cd or Pb and defending effects on plants, explained by the significant removal of acid-extractable and reducible metals in soils and the increase of Cd and Pb content in P. communis tissues. The present study explored the mechanisms of S. chinense QD10 in Cd and Pb biosorption and proved its potential in ameliorating the phytoremediation performance at metal contaminated sites.
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•First study on metal biosorption capability of fungus Simplicillium chinense•Difference in Cd and Pb biosorption mechanisms by Simplicillium chinense•28.6–48.0% more metal removal from soils via fungi-mediated phytoremediation•Rhizosphere-fungi interaction explains the enhanced phytoremediation performance.
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•Parametric anisotropic Gyroid cellular structure (GCS) was designed.•Geometry and mechanical properties of anisotropic GCS were analysed.•The mathematical relationship between the ...geometric parameters and the elastic modulus was determined.
Triply periodic minimal surface (TPMS) isidentifiedas a suitable model for designing porous structures. Gyroid cellular structure (GCS) is the most widely studied type of TPMS structure. The majority of previous studies on GCS have focused on its isotropic structure. However, as a potential candidate for bone repair, anisotropic structures need to be considered. This study presented a strategy to control the anisotropy of GCS by changing its geometrical parameters. The finite element method was subsequently applied to determine the elastic response of anisotropic GCS under compression. The degree of anisotropic (DA) of GCS was evaluated in terms of the ratio of equivalent elastic modulus in vertical and horizontal directions. Within the parameters considered, the DA of GCS varied from 0.17 to 3.6, as compared with 0.2 to 4 for human bones. The main factors affecting the anisotropic elastic response of GCS were structure anisotropy, porosity, and loading direction. The elastic modulus of the anisotropic GCS was in the range 0.03 to 5.6GPa for titanium alloy, as compared with 0.1 to 4.5GPa for human trabecular bone. Combining the porosity and anisotropic models of GCS can offer a scaffold that matches closely the human bone mechanical environment.
High tibial osteotomy becomes increasingly important in the treatment of cartilage damage or osteoarthritis of the medial compartment with concurrent varus deformity. HTO produces a postoperative ...valgus limb alignment with shifting the load-bearing axis of the lower limb laterally. However, maximizing procedural success and postoperative knee function still possess many difficulties. The key to improve the postoperative satisfaction and long-term survival is the understanding of the vital biomechanics of HTO in essence. This review article discussed the alignment principles, surgical technique, and fixation plate of HTO as well as the postoperative gait, musculoskeletal dynamics, and contact mechanics of the knee joint. We aimed to highlight the recent findings and progresses on the biomechanics of HTO. The biomechanical studies on HTO are still insufficient in the areas of gait analysis, joint kinematics, and joint contact mechanics. Combining musculoskeletal dynamics modelling and finite element analysis will help comprehensively understand in vivo patient-specific biomechanics after HTO.
•WNN is proposed as a real-time surrogate for joint moment prediction.•WNN predicts joint moments based on GRFs and EMG signals.•Generalization ability is tested for a new subject and a new gait ...pattern.
Joint moment is one of the most important factors in human gait analysis. It can be calculated using multi body dynamics but might not be straight forward. This study had two main purposes; firstly, to develop a generic multi-dimensional wavelet neural network (WNN) as a real-time surrogate model to calculate lower extremity joint moments and compare with those determined by multi body dynamics approach, secondly, to compare the calculation accuracy of WNN with feed forward artificial neural network (FFANN) as a traditional intelligent predictive structure in biomechanics.
To aim these purposes, data of four patients walked with three different conditions were obtained from the literature. A total of 10 inputs including eight electromyography (EMG) signals and two ground reaction force (GRF) components were determined as the most informative inputs for the WNN based on the mutual information technique. Prediction ability of the network was tested at two different levels of inter-subject generalization. The WNN predictions were validated against outputs from multi body dynamics method in terms of normalized root mean square error (NRMSE (%)) and cross correlation coefficient (ρ).
Results showed that WNN can predict joint moments to a high level of accuracy (NRMSE<10%, ρ>0.94) compared to FFANN (NRMSE<16%, ρ>0.89). A generic WNN could also calculate joint moments much faster and easier than multi body dynamics approach based on GRFs and EMG signals which released the necessity of motion capture. It is therefore indicated that the WNN can be a surrogate model for real-time gait biomechanics evaluation.
Zirconia ceramic is a widely used material for dental restoration. Stabilized zirconia all-ceramic teeth have excellent mechanical properties, biocompatibility, and aesthetic properties. At present, ...the CAD/CAM technique for zirconia all-ceramic dental prosthesis leads to low material efficiency and high tool wear. Although restorations fabricated using additive manufacturing are gaining attention, it is still very challenging to obtain accurate shapes and proper mechanical properties in zirconia restorations. In this investigation, a type of three-part auxiliary support was adopted and added to the occlusal surface to fabricate a typical molar crown bridge. A ceramic solid content of 40 vol% acrylic-based slurry was prepared, and a molar crown bridge was fabricated using mask projection stereolithography. The experimental results showed that the average dimensional error of the printed green body was ±150 μm. The density of the sintered ceramic parts was 6.026 g/cm3, and the three-point bending strength was 541 ± 160 MPa, which is higher than that of human dentin (160 MPa), but lower than that of CAD/CAM zirconia (900–1200 MPa). Although the proposed process still needs to be optimized to improve the mechanical properties and reliability of the crown bridge, the mask projection process combined with the adopted three-part auxiliary supports are capable of individualized manufacturing of complex zirconia crown bridges.
Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the ...development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.
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