Biomedical Engineering: Applications, Basis and Communications

Walking inclined ground surfaces presents a number of challenges to the human locomotor system, especially for those with neuromusculoskeletal injuries or diseases. The purpose of the current study was to perform a complete 3D kinetics analysis of the locomotor system during uphill walking on surfaces of different inclinations in order to reveal interactions of the joints and the trunk motion, and the related mechanical demands for future clinical applications. Fifteen young adults were asked to walk on inclined sloped walkways with 0, 5, 10, 15 degrees of slopes while kinematic and kinetic data were collected and analyzed. The results showed that the subjects increased the anterior tilt of the pelvis and the flexion of the trunk with increased inclination angles, maintaining more or less constant moments at the ankle, but modulating the moments at the hip and knee during the first half of the stance phase, and the moments at the hip only during the second half of the stance phase. In response to weight acceptance and propulsion of the body's COM, differences in the peak inter-segmental joint resultant force magnitudes at different inclination angles occurred primarily in the anterioposterior direction for all the joints of the lower extremities. The angular extensor impulses at all the joints increased linearly with increased slope, suggesting an overall linear joint angular impulse control during uphill walking. The current data and findings may serve as baseline data for future clinical purposes and may be helpful for other ergonomic applications.

Sensorimotor rhythm (SMR) neurofeedback training (NFT) has an important role in improvement of cognitive functions in both clinical and healthy individuals. It is very possible that in SMR NFT adjacent frequency bands, such as alpha and beta1, be affected by SMR enhancing neurofeedback. Therefore, the adjacent frequency bands, in addition to SMR, may be associated with the improvement of the cognitive functions. Eight sessions of NFT were applied to healthy individuals to enhance their SMR activity. In order to investigate the effect of SMR enhancing neurofeedback on the power of adjacent frequency bands, correlation between the change in SMR activity and the change in alpha or beta1 activity was computed. The results revealed that there is a highly significant positive correlation between the change in SMR and beta1 activities. The given outcome suggests that during SMR NFT, the effect of both SMR and beta1 be considered together on the improvement of the cognitive functions.

A novel Electrical Impedance Tomography system with rectangular electrodes array and back electrode is proposed. This system could reconstruct a deeper target and is easy to operate. By studying different reconstructed algorithms: Tikhonov regularization and the Newton's One-step Error Reconstructor (NOSER), a combined regularization algorithm is proposed. The L-curve and posteriori method are used to choose Tikhonov and NOSER regularization parameter. Two evaluation parameters of reconstructed algorithm: normalization mean square distance criterion (NMSD), normalized mean absolute distance criterion (NMAD) are used to evaluate the result's precision of inverse problem quantificationally. The comparison among Tikhonov regularization, NOSER and the combined regularization shows that the ill-condition and the error of inverse problem are reduced. This new algorithm can decrease condition number by 70%, NMSD by 51%, and NMAD by 41% at least. Simulate results show that the combined regularization algorithm could reconstructed the target image in the depth from 10–40 mm. The experimental results show that a 15 mm × 9 mm × 9 mm cuboids whose depth is 35 mm could be distinguished. The performance of this system and the combined regularization algorithm demonstrate significantly better spatial resolution and minor reconstructed error.

Vascular support structures are important devices for treating valve stenosis. Large population of patients is treated for valvular disease and the principal mode of treatment is the use of percutaneous valvuloplasty. Stent devices are proving to be an improved technology in minimal invasive cardiac surgery. This technology now accounts for 20% of treatments in Europe. This new technology provides highly effective results at minimal cost and short duration of hospitalization. During the development process, a number of specific designs and materials have come and gone, and a few have remained. Many design changes were successful, and many were not. This paper discusses the physical behavior of a hooked percutaneous aortic valve stent design using finite element analysis using a new Titanium alloy. The analysis performed in this paper may aid in understanding the stent's displacement ranges when subjected to the physiological pressures exerted by the heart and cardiac blood flow during abnormal cardiovascular conditions. It may also help to evaluate the suitability of a new titanium alloy for fabrication purposes.

The aim of this study is to visualize and analyze the mucous layer effects towards the nasal airflow. Mucous layer had been neglected in previous works as it is considered a very thin layer along the nasal passageway. This paper discussed the effects in nasal airflow caused by the micrometer changes of the mucous layer thickness along the nasal passageway. Differences in maximum velocities caused by the mucous layer and visualization of the nasal airflow were studied. Computational fluid dynamics (CFD) was used to study three-dimensional nasal cavity of an adult Malaysian female. Six different models with various thickness of mucous layer within the range of 5–50 μm were implemented in the analysis with mass flow rate of 7.5 and 20 L/min. Mucous layer is assumed to be uniform, solid, and also stationary for this study. The results from all the six models were compared with the model with non-mucous effects. Based on both laminar and turbulent airflow simulations, it is shown that the addition of mucous layer thickness in analysis increased the maximum velocities at the four cross sections along the nasal cavity.

In this report, we generated a ferritin and red fluorescent protein fusion reporter gene that enables the visualization of transgene expression in living animals by magnetic resonance imaging (MRI) and optical imaging. Ferritin heavy chain (FTH) or light chain (FTL) was linked to the N terminus of the monomeric DsRed red fluorescent protein to create FTH-DsRed and FTL-DsRed, MRI-fluorescence dual reporters. Transfection of these dual reporters into cells resulted in increased iron loading and strong red fluorescence in cells. Adenoviral vectors to express FTH-DsRed or FTL-DsRed fusion reporter in infected cells were created, but only the adenovirus expressing FTH-DsRed resulted in a high level of red fluorescence in cells. Delivery and expression of FTH-DsRed in the mouse brain using adenovirus was detected by MRI and fluorescence imaging, revealing a T₂ shortening effect and an increase of contrast in T₂-weighted images at the sites co-localized with strong red fluorescence. While the details of the structure of ferritin-DsRed fusion reporter remains to be solved, this dual reporter is useful for visualizing dynamic processes such as the migration of reporter-transfected stem cells or metastasis of tumors using MRI with the added flexibility of combining optical tools such as fluorescence activated cell sorting and fluorescence microscopy.

The concept of texturing steel surfaces were attempted to ease the surface wear and to prevent the release of harmful ions in the conventional joint replacement systems. The surfaces of the bio-compatible steels were textured by photolithography and electrochemical etching techniques to lower the friction coefficient and hence reduce the wear of the surface. Experimental results confirmed that the surfaces with textures (grooves) showed lower friction coefficient compared to un-textured surfaces at a high load (50 N). The friction coefficient could be further reduced for a lower load (10 N) through optimizing the generated hydrodynamic lift. A significant 47% reduction of friction coefficient was archived by tailoring the orientation and size of the textures on the stainless steel surface. The demonstrated strategy in this study would thus offer exciting avenues for developing artificial joint systems that last the full duration of the patients' life without any side-effect concerns.

In this paper, we propose a fuzzy diagnostic method based on interval-valued intuitionistic fuzzy sets. For this purpose, we developed an interval-valued interview chart with interval fuzzy degree assigned to the relation among symptoms and diseases, and utilized the interval-valued intuitionistic fuzzy weighted arithmetic average operator to aggregate fuzzy information from the symptoms. In addition, we suggest a diagnosis measure using the occurrence proportion of patient's symptoms. Finally, an illustrative example is given to demonstrate its practicality and effectiveness.

Double-stranded DNA (dsDNA) is one of the most used model polymers in studying polymer dynamics. Some recent studies with the experimental data via fluorescence correlation spectroscopy (FCS) proposed that the end-monomer dynamics of dsDNA in dilute solution should be fallen into Rouse-type at intermediate times. This viewpoint is inconsistent with the classical polymer dynamics, therefore arousing controversy. To have a further looking clearly at what else meaning could be revealed from the original data of the FCS measurements, we made a re-calculation by two methods: one is based on Lodge and Wu's model (LWM) modified from the classical bead-spring model, in which parameters used in modeling are needed to be adjusted; and another is a mean field theory (MFT) for semiflexible chain with no parameter fitting needed. In LWM, we find not so weak hydrodynamic interactions (HI) which is not expected in Rouse theory, and the scaling of mean square displacement (MSD) is between Rouse-type and Zimm-type. MFT can reproduce experimental data well at larger time scales, whereas also gives rather different picture in intermediate regime — a dynamical scaling between Rouse-like and Zimm-like rather than Rouse-like scaling is found, indicating there may be sample problems or limitations in the setup for the experiment.

The sEMG (Surface electromyography) signals detected from activated muscles can be used as a control source for prosthesis. So an efficient and accurate method for the classification of sEMG signal patterns has become a hot research in recent years. Artificial neural network is a popular used method in this field, however, most neural networks require large numbers of samples in the training stage to obtain the potential relationships between input feature vectors and the outputs.

In this paper, Integrated back propagation neural network (IBPNN) is used to classify sEMG signals acquired during five different hand motions. The correct classification rates of IBPNN for the five hand movements are significantly higher than that of BPNN and Elman neural network. This reveals that IBPNN achieves the best performance with a small sized training data and can be used in control systems on prosthetic hands and other robotic devices based on electromyography pattern recognition.