Bio-Medical Materials and Engineering - Volume 28, issue 2
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Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: Background: Existing knee cartilage segmentation methods have reported several technical drawbacks. In essence, graph cuts remains highly susceptible to image noise despite extended research interest; active shape model is often constraint by the selection of training data while shortest path have demonstrated shortcut problem in the presence of weak boundary, which is a common problem in medical images. Objectives: The aims of this study is to investigate the capability of random walks as knee cartilage segmentation method. Methods: Experts would scribble on knee cartilage image to initialize random walks segmentation. Then, reproducibility of the method is…assessed against manual segmentation by using Dice Similarity Index. The evaluation consists of normal cartilage and diseased cartilage sections which is divided into whole and single cartilage categories. Results: A total of 15 normal images and 10 osteoarthritic images were included. The results showed that random walks method has demonstrated high reproducibility in both normal cartilage (observer 1: 0.83 ± 0.028 and observer 2: 0.82 ± 0.026 ) and osteoarthritic cartilage (observer 1: 0.80 ± 0.069 and observer 2: 0.83 ± 0.029 ). Besides, results from both experts were found to be consistent with each other, suggesting the inter-observer variation is insignificant (Normal: P = 0.21 ; Diseased: P = 0.15 ). Conclusion: The proposed segmentation model has overcame technical problems reported by existing semi-automated techniques and demonstrated highly reproducible and consistent results against manual segmentation method.
Keywords: Knee cartilage, random walks, segmentation, semi-automated, osteoarthritis
Abstract: Background: Osteoporosis is a common metabolic disease, with mesenchymal stem cells discussed to play an important role in its pathomechanism. For in vitro osteoporosis studies, selection of adequate culture conditions is mandatory so as to preserve cell properties as far as possible. A suitable cell culture surface would ideally provide reproducible experimental conditions by resembling those in-vivo. Objective: Generating an improved growth surface for osteogenic differentiation of human bone marrow derived mesenchymal stem cells (hBMSCs). Methods: We modified electrospun gelatine meshes with hydroxyapatite nanopowder. The potential beneficial impact of the ensuing culture conditions were evaluated by…cultivating and comparing the growth of cells from osteoporotic and non-osteoporotic donors on either hydroxyapatite-gelatine (HA) meshes, pure gelatine meshes, or 2D standard tissue culture surfaces. Results: After 21 days of differentiation, cells grown on pure or HA-gelatine meshes showed significantly higher mineralization levels compared to cells cultured in standard conditions. The amount of mineralization varied considerably in hBMSC cultures of individual patients but showed no significant difference between stem cells obtained from osteoporotic or non-osteoporotic donors. Conclusions: Overall, these results indicate that the use of HA-gelatine meshes as growth surfaces may serve as a valuable tool for cultivation and differentiation of mesenchymal stem cells along the osteogenic lineage, facilitating future research on osteoporosis and related issues.
Abstract: Background: Clinical scales such as Fugl-Meyer Assessment (FMA) and Motor Assessment Scale (MAS) are widely used to evaluate stroke patient’s motor performance. However, there are several limitations with these assessment scales such as subjectivity, lack of repeatability, time-consuming and highly depend on the ability of the physiotherapy. In contrast, robot-based assessments are objective, repeatable, and could potentially reduce the assessment time. However, robot-based assessments are not as well established as conventional assessment scale and the correlation to conventional assessment scale is unclear. Objective: This study was carried out to identify important parameters in designing tasks that efficiently assess…hand function of stroke patients and to quantify potential benefits of robotic assessment modules to predict the conventional assessment score with iRest. Methods: Twelve predictive variables were explored, relating to movement time, velocity, strategy, accuracy and smoothness from three robotic assessment modules which are Draw I, Draw Diamond and Draw Circle. Regression models using up to four predictors were developed to describe the MAS. Results: Results show that the time given should be not too long and it would affect the trajectory error. Besides, result also shows that it is possible to use iRest in predicting MAS score. Conclusion: There is a potential of using iRest, a non-motorized device in predicting MAS score.
Abstract: The fundamental cause of diabetic limbs’ problem is insufficient blood supply. The aim of the current work was to experimentally and numerically investigate the blood flow velocity and pressure changes in the channel during vibrational excitation. The micro-scale Particle Image Velocimetry (μ PIV) technique as well as corresponding numerical channel model in COMSOL Multiphysics software were used to investigate the influence of external vibrations. Momentum upstream flow were noted on the fluid that was influenced by vibrations. Furthermore, momentum flow velocity increased by more than 3 times in both experimentally and theoretically. These results show that suggested novel low-frequency vibrational…excitation method should be investigated in clinical studies in case of improvement of blood circulation in human limbs.
Abstract: Background: High-performance position control of pneumatic artificial muscles is limited by their inherent nonlinearity and hysteresis. Objective: This study aims to model the length/pressure hysteresis of a single pneumatic artificial muscle and to realize its accurate position tracking control with forward hysteresis compensation. Methods: The classical Prandtl–Ishlinskii model is widely used in hysteresis modelling and compensation. But it is only effective for symmetric hysteresis. Therefore, a modified Prandtl–Ishlinskii model is built to characterize the asymmetric length/pressure hysteresis of a single pneumatic artificial muscle, by replacing the classical play operators with two more flexible elementary operators to…independently describe the ascending branch and descending branch of hysteresis loops. On the basis, a position tracking controller, which is composed of cascade forward hysteresis compensation and simple proportional pressure controller, is designed for the pneumatic artificial muscle. Results: Experiment results show that the MPI model can reproduce the length/pressure hysteresis of the pneumatic artificial muscle, and the proposed controller for the pneumatic artificial muscle can track the reference position signals with high accuracy. Conclusion: By modelling the length/pressure hysteresis with the modified Prandtl–Ishlinskii model and using its inversion for compensation, precise position control of a single pneumatic artificial muscle is achieved.
Keywords: Pneumatic artificial muscle, position control, hysteresis compensation, modified Prandtl–Ishlinskii model
Abstract: Background and objective: Epilepsy is one of the most common neurological disorders caused by recurrent seizures. Electroencephalograms (EEGs) record neural activity and can detect epilepsy. Visual inspection of an EEG signal for epileptic seizure detection is a time-consuming process and may lead to human error; therefore, recently, a number of automated seizure detection frameworks were proposed to replace these traditional methods. Feature extraction and classification are two important steps in these procedures. Feature extraction focuses on finding the informative features that could be used for classification and correct decision-making. Therefore, proposing effective feature extraction techniques for seizure detection is of…great significance. Methods: Principal Component Analysis (PCA) is a dimensionality reduction technique used in different fields of pattern recognition including EEG signal classification. Global modular PCA (GModPCA) is a variation of PCA. In this paper, an effective framework with GModPCA and Support Vector Machine (SVM) is presented for epileptic seizure detection in EEG signals. The feature extraction is performed with GModPCA, whereas SVM trained with radial basis function kernel performed the classification between seizure and nonseizure EEG signals. Seven different experimental cases were conducted on the benchmark epilepsy EEG dataset. The system performance was evaluated using 10-fold cross-validation. In addition, we prove analytically that GModPCA has less time and space complexities as compared to PCA. Results: The experimental results show that EEG signals have strong inter-sub-pattern correlations. GModPCA and SVM have been able to achieve 100% accuracy for the classification between normal and epileptic signals. Along with this, seven different experimental cases were tested. The classification results of the proposed approach were better than were compared the results of some of the existing methods proposed in literature. It is also found that the time and space complexities of GModPCA are less as compared to PCA. Conclusions: This study suggests that GModPCA and SVM could be used for automated epileptic seizure detection in EEG signal.
Keywords: Electroencephalogram signal (EEG), Modular Principal Component Analysis (MPCA), Global Modular Principal Component Analysis (GModPCA), Support Vector Machine (SVM)
Abstract: Background: Syntesizing alternative bone graft materials are important in biomedical applications. Their morphology, mechanical properties and cell viability plays an important role in tissue engineering. Objective: Bioglass (B) based bone grafts with Gelatin (G) substitution were syntesized via the sol-gel method and were compared with various Gelatin and Bioglass concentrations (wt%). Methods: Syntesized bone grafts were characterized by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) to show the structural and morphological changes of the fabricated B-based bone grafts. Results: It was demonstrated that the concentration of pore size increased with increasing amounts of…Gelatin in wt%. The biograft-B40G20 produced the highest flexture strength and hardness. Increasing the pore size caused a decrease in hardness and flexture stress of B-based biografts. Conclusions: Cell viability tests were conducted on the fabricated biografts and it was shown that the cell viability increased in fabricated B-based bone grafts.
Keywords: Bioglass, sol gel, mechanical properties, cell viability
Abstract: Objective: The purpose of this study was to evaluate the effect of double-application coats and times on microtensile bond strength (μ TBS) and adhesive-dentin interfaces created by dentin adhesive systems after 6 months of storage in water. Materials and methods: Two-hundred sixteen extracted non-carious human third molars were selected for the study. Single-Bond Universal (SU) and All-Bond Universal (AU), Adper Easy One (Eo) Self-Etch adhesive and Adper Single-Bond 2 (Sb) etch-and-rinse adhesive were applied to a flat dentin surface using three methods (1): dentin adhesives were applied as recommended by the manufacturers; (2): two consecutive coats of dentin adhesives…were applied before photo-polymerization; and (3): a single coat of adhesive was applied but with twice the manufacturers recommended application time. Microtensile bond strength was determined either immediately or after 6 months of water storage. Data were analyzed using one-way analysis of variance and Tukey’s post-hoc tests. Results: At 24 h, groups 1, 2, and 3 exhibited statistically similar results for all dentin adhesive systems. For AU-Er, group 3 showed significantly higher bond strength than all group of AU-Se after 6 months. Conclusion: Universal adhesives seemed more stable against water degradation than traditional two-step etch-and-rinse and all-in-one systems within the 6-month period.
Keywords: Bond durability, double-application coat, double-application time, universal adhesive
Abstract: The finite element (FE) method has been widely used to investigate the mechanism of traumatic brain injuries (TBIs), because it is technically difficult to quantify the responses of the brain tissues to the impact in experiments. One of technical challenges to build a FE model of a human head is the modeling of the cerebrospinal fluid (CSF) of the brain. In the current study, we propose to use membrane elements to construct the CSF layer. Using the proposed approach, we demonstrate that a head model can be built by using existing meshes available in commercial databases, without using any advanced…meshing software tool, and with the sole use of native functions of the FE package Abaqus. The calculated time histories of the intracranial pressures at frontal, posterior fossa, parietal, and occipital positions agree well with the experimental data and the simulations in the literature, indicating that the physical effects of the CSF layer have been accounted for in the proposed modeling approach. The proposed modeling approach would be useful for bioengineers to solve practical problems.
Keywords: Biomechanics of impact, finite element analysis, head-brain impact, cerebrospinal fluid, traumatic brain injury
Abstract: Coring is a surgical procedure in bone biopsy retrieval and dental/orthopaedic procedures, which may cause thermal damage to bone tissues adjacent to the coring zone. This study was performed to determine the temperature rise in bone by coring using a semi-empirical thermocouple approach. Concurrently, a custom-made dynamometer was used to measure the cutting and thrust forces during coring bovine cortical bone samples. The experimental results indicated that the cutting force, cutting speed, and depth of cut significantly affect the temperature rise in the cutting zone during coring process. In addition, acute temperature rises in the cutting zone occurred when the…cutting speed exceeded threshold levels. The limited capacity of heat dissipation during coring is most likely responsible for such a sharp temperature rise with increasing cutting speed. Moreover, it was observed that the maximum size of potential thermal damage zone could reach to 3.0 mm in depth from the surface of the coring hole, assuming that thermal damage would occur when the temperature is greater than 47°C. Thus, proper cutting conditions need to be selected to avoid the potential thermal damage to bone during the coring procedures.
Keywords: Bone, coring, thermal damage, cutting temperature, cutting force