Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Behnaz Sheikholeslami; Ghasem Sadeghi Bajestani; Reza Yaghoobi Karimui; Reyhaneh Zarifiyan
Volume 15, Issue 1 , May 2021, , Pages 29-46
Abstract
Attention Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that can affect people of all ages in the community, especially children, and cause changes in their behavior. Previous studies have often focused on frequency domain processing or the nonlinear dynamic aspects of EEG signals ...
Read More
Attention Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that can affect people of all ages in the community, especially children, and cause changes in their behavior. Previous studies have often focused on frequency domain processing or the nonlinear dynamic aspects of EEG signals such as correlation dimension, fractal dimension, Lyapunov exponent, entropy, and recurrence rate of brain processes to differentiate individuals with ADHD. In this study, we evaluate the volume of the EEG signal oscillation basin using Poincare sections in the phase space of EEG signals of people with ADHD and healthy people and sort this space as well as extract various geometric features. We present a different perspective of complexity of brain activity and the level of dynamism of people with ADHD compared to healthy individuals. Finally, by evaluating the extracted features and using the SFS algorithm based on the RBF-SVM classifier, we were able to separate people with ADHD from healthy people in the groups of children and adults, with accuracy of 93.20±2.04 and 95.60±1.13. The results of this study showed that the volume of the EEG signal oscillation basin in people with ADHD was significantly higher than healthy people, which indicates an increase in the degree of dynamism and thus a decrease in the complexity of brain activity in these people. It was also identified in this study that the increase in the volume of the EEG signal oscillation basin in children is more than adults, which indicates an increase in the level of dynamism of children compared to adults. Therefore, ADHD and age can be introduced as two important factors in changing the volume of the EEG signal oscillation basin.
Hadi Borjkhani; Samad Sheikhaei; Mehdi Borjkhani
Volume 8, Issue 1 , March 2014, , Pages 31-43
Abstract
Currently need for ultra low power wireless transmitters in medical applications are inevitable. In this paper a new transmitter for body-worn and implantable sensor nodes is presented. Most of the sensor nodes supply their power using energy harvesting instead of a battery, since the power earned by ...
Read More
Currently need for ultra low power wireless transmitters in medical applications are inevitable. In this paper a new transmitter for body-worn and implantable sensor nodes is presented. Most of the sensor nodes supply their power using energy harvesting instead of a battery, since the power earned by harvesting is limited, so the average and the peak power consumption of the sensor node must be minimized. Transmitter blocks which implemented in sensor nodes are too power consuming. So a new low power Binary Frequency Shift Keying (BFSK) transmitter based on sub-harmonic current mode injection locking, and edge combining technique has been proposed. The proposed transmitter was designed to make a mutual communication between sensor node and base station, so there is no need for complexity at receiver side. In order to reduce the consuming power at transmitter side, BFSK modulation is done at reference frequency to prevent usage of power consuming low phase noise oscillator at carrier frequency. A 34MHz reference clock is used and the frequency of reference clock multiplied by 12 for desired carrier frequency. The phase noise of the carrier at 1MHz frequency offset is -117 dBc/Hz. Total power consumption of the transmitter is about 144μW. The output carrier frequency is 408MHz. BFSK modulation scheme is used at the frequency much lower than the carrier frequency in order to reduce the power consumption.
Biomechanics / Biomechanical Engineering
Mahdieh Mosayebi; Afsaneh Mojra
Volume 13, Issue 1 , April 2019, , Pages 31-44
Abstract
Intervertebral disc (IVD) provides flexibility and shock absorption for the spine in the load transmission procedure. Disc degeneration may occur as a result of aging and inappropriate types of loading. Assessing biomechanical parameters of intact IVD in comparison to the degenerated disc with different ...
Read More
Intervertebral disc (IVD) provides flexibility and shock absorption for the spine in the load transmission procedure. Disc degeneration may occur as a result of aging and inappropriate types of loading. Assessing biomechanical parameters of intact IVD in comparison to the degenerated disc with different grades of degeneration can facilitate the detection procedure and planning for suitable therapeutic treatment. In the present study, a real three-dimensional model of cercival IVD ( - with adjacent vertebrae is constructed by using computed tomography (CT-scan) images. In order to accurately define mechanical properties, the disc and the vertebrae are modelled as poroviscoelastic and poroelastic materials, respectively. A porous medium approach is adopted to consider the considerable water content of both media alongside the solid matrix. For the solid phase of the IVD, the related viscoelastic parameters are extracted from an experimental test on a sheep lumbar intervertebral disc and stress vs. time data are fitted to the generalized Maxwell model with two Maxwell arms. By employing the finite element method, time-dependent response of the intact IVD and three different levels of the degenerated IVD (mild, moderate and severe) are studied in a relaxation test. Results indicate that during relaxation procedure, intradiscal fluid velocity decreases as a result of disc degeneration. This may oppositely affect the flexibility of IVD in the load bearing. It is also observed that stress relaxation of the severe degenerated IVD almost increases up to 16% relative to the intact IVD. Assessing the amount of disc bulging under load application shows enhancement for the degenerated disc compared to the intact disc.
Neuro-Muscular Engineering
Mohsen Abedi; Majid Mohammadi Moghaddam; Mohammad Firoozabadi
Volume 9, Issue 1 , April 2015, , Pages 33-48
Abstract
In this paper the simulation of pathological behavior in gait locomotion of central nervous system (CNS) diseases and effects of rehabilitation techniques are investigated. These simulations noticeably deepen the knowledge of researches in neurorehabilitation realm about the neuroscientific basis of ...
Read More
In this paper the simulation of pathological behavior in gait locomotion of central nervous system (CNS) diseases and effects of rehabilitation techniques are investigated. These simulations noticeably deepen the knowledge of researches in neurorehabilitation realm about the neuroscientific basis of CNS treatment after a neural disorder. However, only a limited number of these simulations have been proposed in the previous works that issued some aspects of CNS diseases. Due to this limitation, in this paper, a more efficient simulation has been done on pathological behavior of neural disorders with including the brain signal disruption in the models. To do this, combinations of neural reflexes and central pattern generator (CPG) has been incorporated in the neuromuscular system and examined on two different msculoskeletal system containing two leg-one segment and one leg-two segment systems. Then, the locomotion of hemiplegia and paraplegia patients are simulated by inserting a malfunction in the supraspinal signal coming into the CPG. Moreover, the effects of rehabilitation effects on paraplegia patients have been investigated and qualititatively compared to the experimental data.
Fluid-Structure Interaction in Biological Media / FSI
shahrokh shojaei; Shahrokh Shojaei
Volume 16, Issue 4 , March 2023, , Pages 41-50
Abstract
The pathological effects of the tumor on the respiratory airway have always been the focus of researchers. So, these effects will lead to the suffocation of the patient in acute cases. This study presents a computational model to investigate the effect of a tumor on the airflow in the larynx area with ...
Read More
The pathological effects of the tumor on the respiratory airway have always been the focus of researchers. So, these effects will lead to the suffocation of the patient in acute cases. This study presents a computational model to investigate the effect of a tumor on the airflow in the larynx area with the help of Ansys software. The presented model is able to numerically calculate the effect of tumor presence on airspeed and pressure in the upper air system. This study considered the simulation of steady airflow for exhalation in three respiratory flow rates of 15 L/min, 26 L/min, and 30 L/min. The maximum speed limit in the respiratory flow of L/min 15, L/min 26, and L/min 30, respectively, 6.26 m/s, 10.58 m/s, and 12.14 m/s, appears in the larynx. Also, the highest pressure occurs in the trachea, so the maximum pressure in the respiratory rate is 15 L/min, 26 L/min, and 30 L/min, respectively, equal 19.6 Pa, 51.01 Pa, and 65.8 Pa. On the other hand, most deformation occurs in the area of narrowing of the respiratory tract. With the increase in the flow rate, the amount of deformation also increases. The maximum deformation on the wall at the respiratory flow rate of 15 L/min, 26 L/min, and 30 L/min is equal to 0.07mm, 0.2mm, and 0.27mm, respectively. Due to the presence of a tumor in this respiratory model, velocity and WSS reach their maximum in the larynx region. The presence of a tumor can gradually lead to airway obstruction. Moreover, the risk of airway obstruction increases even in a slight reduction in respiratory capacity. Providing a numerical model for the respiratory system can effectively lead to a better treatment approach.
Rehabilitation Engineering
Hamed Ghomashchi; Ali Esteki; Ali Motie Nasrabadi
Volume 2, Issue 2 , June 2008, , Pages 95-107
Abstract
In this study, the underlying dynamics of postural control system during quiet standing were investigated. Single-subject (SS) analysis was used as the statistical technique to compare the results. Center of pressure (COP) trajectories of 21 trials of a standing healthy subject and 24 trials of a cerebrovascular ...
Read More
In this study, the underlying dynamics of postural control system during quiet standing were investigated. Single-subject (SS) analysis was used as the statistical technique to compare the results. Center of pressure (COP) trajectories of 21 trials of a standing healthy subject and 24 trials of a cerebrovascular attacked (CVA) patient were considered in our analysis. Complexity, dimensionality and stability of postural balance control system were evaluated using the first local minimum of auto mutual information (AMI) function, correlation dimension (Dc) and largest lyapunov exponent (LLE), respectively. The results indicated higher time delays (higher determinism), lower correlation dimension (lower active dynamical degrees of freedom) and lower LLE (increase of local stability) in the postural steadiness time series of the CVA patient in compare with the normal subject. The results showed that these measures not only can be used as pathologic measures to distinguish healthy subjects from CVA patient but also provide us new openings to disclose the postural control mechanism during a quiet standing.
Biomechanics of Bone / Bone Biomechanics
Seyed Mahmoud Rabiei; Fathollah Moztarzadeh; Mehran Solati Hashjin; Saeed Hesaraki
Volume 1, Issue 2 , June 2007, , Pages 105-110
Abstract
In this research, the influence of NaH2PO4.2H2O with different concentrations on setting time and compressive strength of bone cement based on hydroxyapatite was investigated. Hydroxyapatite cement is of calcium phosphate bone cements, which can be considered as the best substitute for hard tissues. ...
Read More
In this research, the influence of NaH2PO4.2H2O with different concentrations on setting time and compressive strength of bone cement based on hydroxyapatite was investigated. Hydroxyapatite cement is of calcium phosphate bone cements, which can be considered as the best substitute for hard tissues. The powder phase of the cement was prepared from various compositions of calcium phosphates such: tricalcium phosphate (TCP), calcium carbonate (CaCO3) and montite (CaHPO4) as constant and the liquid part using NaH2PO4.2H2O solution with different concentrations. The influences of liquid/powder ratio L/P (ml/g) was investigated on the initial and final setting times and compressive strengths of the cement. According to the obtained results, with optimum concentrations of the liquid phase, this cement seems suitable for clinical applications.
Bioelectromagnetics
Susan Kohzad; Bahram Bolouri; Farnaz Nikbakht; Zahra Kohzad
Volume 6, Issue 2 , June 2012, , Pages 107-111
Abstract
There is a growing public concern that the extremely low frequency (ELF) range of the environmental electromagnetic fields may have adverse biological effects. In this frequency range, 217Hz is the modulating signal being used in Global System of Mobile. This study investigated the possible effects of ...
Read More
There is a growing public concern that the extremely low frequency (ELF) range of the environmental electromagnetic fields may have adverse biological effects. In this frequency range, 217Hz is the modulating signal being used in Global System of Mobile. This study investigated the possible effects of 217 Hz pulsed electromagnetic field on the anxiety and the cortisol level in rats. Twenty four male Wistar rat (200 - 250 g) were randomly grouped into test, sham and control. Using a pair of Helmholtz coil system, the test group was exposed to a uniform pulsed EMF of 200µT intensity for 4 h/day for 21 days. A similar procedure with no field was repeated for the sham group. All groups were tested in an `Elevated- plus` maze system. Then via the heart puncture scheme, the blood samples were collected. The serum cortisol levels were evaluated using ELISA method.The ANOVA test revealed no significant differences for the Elevated- plus maze test. Serum cortisol level was significantly higher in test group compared to the control group.These findings were in consistent with the work of others indicating that low frequency band of EMF might not have any effect on the anxiety but it increases the cortisol levels as a stress marker.
Neuro-Muscular Engineering
Mehdi Borjkhani; Farzad Towhidkhah
Volume 4, Issue 2 , June 2010, , Pages 109-122
Abstract
Writing is one of the high practiced and complex movement skills of human. Most of the proposed models for writing are bottom-up models, and therefore they could not reflect the biological aspects of movements in this process. Also there is not any model for illustrating the role of different parts of ...
Read More
Writing is one of the high practiced and complex movement skills of human. Most of the proposed models for writing are bottom-up models, and therefore they could not reflect the biological aspects of movements in this process. Also there is not any model for illustrating the role of different parts of the brain in this task. In this paper we are going to describe some neurological and physiological aspects of the brain operation in the writing task. Then some evidence of prediction in writing and existence of internal models for limbs such as hand are presented. According to these, modeling of writing using model predictive control (MPC) is possible. Based on the presented simulations and experimental results it seems that the modeling of writing by MPC is very similar to the real skill, The proposed model has some advantages such as being consistent with the biological evidence, modeling prediction in writing and high correlation of the statical and dynamical features of the generated letters with those written by human.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Maryam Dorvashi; Neda Behzadfar; Ghazanfar Shahgholian
Volume 14, Issue 2 , July 2020, , Pages 109-119
Abstract
Consumption of alcohol contributes to disorders in brain. In this study, in order to detect the consumption of alcohol, electroencephalogram (EEG) signal of 20 participants (10 alcoholic and 10 control subjects) recorded by 64 channels was investigated. Frequency and non-frequency features of EEG signal ...
Read More
Consumption of alcohol contributes to disorders in brain. In this study, in order to detect the consumption of alcohol, electroencephalogram (EEG) signal of 20 participants (10 alcoholic and 10 control subjects) recorded by 64 channels was investigated. Frequency and non-frequency features of EEG signal including power spectrum of signal, permutation entropy, approximate entropy, Katz fractal dimension and Petrosion fractal dimension were extracted to analyses the EEG signal. Statistical analysis was used to investigate the significant differences between the alcohol and control groups. The Davis-Bouldin (DB) criterion was used to select the best channel distinguishing between the alcoholic and non-alcoholic EEG signal. Results showed that between frequency features, power of lower2 alpha frequency decreased in alcoholic individuals and regarding the DB criterion, the CP3 channel (DB=1.7638) showed the best discrimination between the alcohol and control groups. Also, among the non-frequency features, the Katz fractal dimension increased in the control group and FP2 channel (DB = 0.862) had the best discrimination. Eventually, power of Lower2-alpha frequency band and Katz fractal dimension fed into the nearest neighbor classifier (KNN), 71% and 93% accuracy were achieved, respectively. According to the results, it can be concluded that the best feature and channel discriminating between alcohol and control groups is the Katz fractal dimension and FP2 channel.
Mehrnoush Zare; Jafar Khalil Allafi; Behnam Amin Ahmadi; Seyed Mohammad Mehdi Hadavi
Volume 3, Issue 2 , June 2009, , Pages 111-118
Abstract
Ni-Ti shape memory alloys display unique properties such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior. They also are suitable materials for medical applications. In spite of high Ni content (above 50%) of Ni-Ti shape memory alloys, these materials represent ...
Read More
Ni-Ti shape memory alloys display unique properties such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior. They also are suitable materials for medical applications. In spite of high Ni content (above 50%) of Ni-Ti shape memory alloys, these materials represent good biocompatibility due to formation of Titanium oxide (TiO2) passive layer. Although TiO2 passive layer in these alloys can prevent releasing nickel to the environment, high nickel content and stability of passive layer in these alloys are very debatable subjects. In this study a Ni-Ti shape memory alloy with nominal composition of 50.7 atom% Ni was produced by vacuum induction melting (VIM) process. Homogenization treatments of samples were performed at 1050C for 24 hours. Microstructure and chemical composition of specimens were analyzed. Electrochemical tests were performed in two physiological environments of Ringer solution and NaCl 0.9% solution. In order to determine the amount of released Ni, the solution after potentiostatic tests was analyzed by atomic absorption spectroscopy. The samples after corrosion tests were investigated using Scanning Electron Microscopy (SEM). Furthermore corrosion products were analyzed by X-Ray Diffraction (XRD). Results indicate that the breakdown potential of the Ni-Ti alloy in NaCl 0.9% solution is higher than that in ringer solution. Topographical evaluations show that corrosion products are nearly the same in all samples.
Biomedical Image Processing / Medical Image Processing
Fateme Bagheri; Hamid Behnam; Jahangir Tavakoli; Siavash Rahimian
Volume 5, Issue 2 , June 2011, , Pages 117-125
Abstract
In this study we evaluate parameter of nonlinearity and parameter of h by measuring of the amplitude of the second harmonic component and the fundamental component.This method is a variation of the finiteamplitude that has been adopted for pulse echo measurements. We used normal and cooked pork muscle ...
Read More
In this study we evaluate parameter of nonlinearity and parameter of h by measuring of the amplitude of the second harmonic component and the fundamental component.This method is a variation of the finiteamplitude that has been adopted for pulse echo measurements. We used normal and cooked pork muscle in-vitro. For B/A the result is showed as image and for h the result obtain as absolute mean.The result showed that these parameters can distinguish between normal and cooked tissue.This method was considered to be usable for control and monitoring HIFU.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Somayeh Raiesdana; Samaneh Safari
Volume 13, Issue 2 , August 2019, , Pages 117-134
Abstract
In this study, a neuromarketing project was conducted via EEG signal processing in which the individuals’ interest for buying a relatively luxurious decorative product (which has a relative advantage in exports based on commonly evaluated criteria and indicators in economic) was evaluated. EEG ...
Read More
In this study, a neuromarketing project was conducted via EEG signal processing in which the individuals’ interest for buying a relatively luxurious decorative product (which has a relative advantage in exports based on commonly evaluated criteria and indicators in economic) was evaluated. EEG signals of 24 participants during observing and selecting gemstone images were recorded and processed in order to analyze statistical significance of brain activity variations involved in the emotional (liking) and the decision making (choosing) processes. The recorded signals during the stimulation and selection phases were pre-processed in several steps to remove the existing noises and artifacts. Then, the 19-channel EEGs were processed via multiple tools to indicate active brain regions while watching gemstones. Brain mapping and regional analysis indicated that the occipital>frontal>limbic regions were more activated than other regions. Moreover, the left hemisphere has been more active than the right hemisphere. At the next step, nonlinear entropy feature of each signal segment was extracted to be used for training a neurofuzzy system which is an automatic classifier that learns to classify the individuals’ choices. The classification has resulted in 86.25% precision and 87.4% accuracy in a three-class classification task (including two pleasant selections and one unpleasant selection). At the final step, using a questionnaire filled by participants following the recording session, a number of statistical analyses were performed over the self-conscious and unconscious by means of statistical tools including t-test, analysis of variance and regression. The results of statistical tests indicated that there are significant differences for the cognition of liking or preferring among different choices and based on the selections made by women and men. Furthermore, the lack of existence of a significant difference between conscious and unconscious choices were rejected.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Safa Rafieivand; Mohammad Hasan Moradi; Hosein Asl Soleimani; Zahra Momayez Sanat
Volume 17, Issue 2 , September 2023, , Pages 120-130
Abstract
Esophageal mobility disorders are a type of digestive system problem characterized by abnormal bolus movement in the esophagus. The standard diagnostic method for these kinds of disorders is High-Resolution Manometry (HRM). Despite the availability of guidelines like “Chicago” for the analysis ...
Read More
Esophageal mobility disorders are a type of digestive system problem characterized by abnormal bolus movement in the esophagus. The standard diagnostic method for these kinds of disorders is High-Resolution Manometry (HRM). Despite the availability of guidelines like “Chicago” for the analysis of HRM results, diagnosis is still a challenging task that relies on the physician's skills or requires additional assessment modalities. Additionally, it is typical for esophageal mobility disorders to co-occur in one person, leading to a more complex situation for problem identification.The current study focuses on cases who suffering from more than one disorder simultaneously. Then the problem of disorder identification can be interpreted as a multi-label classification problem. Consequently, the fuzzy classifier architecture that was previously introduced for automatic single-disorder diagnosis by the authors is modified. The presented classifier in this paper not only learns the input space from the samples but also utilizes the co-morbidity of disorders to enhance the prediction results. The outcomes show that adding this information to the learning procedure of the base classifier enhances its performance and generates a new fuzzy classifier that overcomes other multi-label classifiers. The presented method is able to differentiate esophageal mobility disorders with an average Hamming loss of 0.18 ± 0.08 which is better than other competitor methods.
Rehabilitation Engineering
Mohammad Salehi Amini; Siavash Kazemirad; Saman Mohammadi; Roya Narimani; Farzam Farahmand
Volume 7, Issue 2 , June 2013, , Pages 121-132
Abstract
The purpose of this study was to design, analyze and evaluate an effective low-cost driving mechanism for gait trainer. The crank-rocker mechanism was favored for reproducing the path of foot during gait cycle, considering the type of motion and design parameters such as adjustability for different anthropometries, ...
Read More
The purpose of this study was to design, analyze and evaluate an effective low-cost driving mechanism for gait trainer. The crank-rocker mechanism was favored for reproducing the path of foot during gait cycle, considering the type of motion and design parameters such as adjustability for different anthropometries, providing sufficient space for interactions with physical therapist, and simplicity of execution. The dimensions of the mechanism were determined using optimization method while applying appropriate constraints so that the normal gait pattern, particularly of stance phase, was obtained. A 2-D model of the lower limb was developed to simulate the gait of a patient when using the mechanism. Results indicated that with appropriate positioning of the patient, the kinematic and kinetic patterns of the normal gait are reconstructed with no risk of injury. However, there is a high risk of injury of the knee articular surfaces and ligaments, if the patient is positioned only 3 cm higher than designed height.
Biomechanics / Biomechanical Engineering
Aminreza Noghrehabadi; Mohammad Hosein Heidarshenas; Reza Bahoosh
Volume 10, Issue 2 , August 2016, , Pages 123-136
Abstract
A two-dimensional-in-space mathematical model of amperometric micro biosensors with selective and perforated membranes has been proposed and analyzed. The model involves the geometry of micro or nano meter holes partially or fully filled with an enzyme. The model is based on a system of the reaction-diffusion ...
Read More
A two-dimensional-in-space mathematical model of amperometric micro biosensors with selective and perforated membranes has been proposed and analyzed. The model involves the geometry of micro or nano meter holes partially or fully filled with an enzyme. The model is based on a system of the reaction-diffusion equations containing a nonlinear term related to the Michaelis-Menten enzymatic reaction. In this study, in order to generate general equation, first, dimensionless parameters are introduced and then by replacing them into governing equation are converted to dimensionless equations.The general equations have been solved numerically in 2D space.. Using numerical simulation of the biosensor action, the influence of the geometry of the holes as well as of the filling level of the enzyme in the holes on the biosensor response was investigated. For this purpose three different geometries including cylindrical, upright circular and downright circular cone for cavities are considered and the impact of these geometries on the response of the biosensor in different levels of enzyme are obtained. Biosensor's respond based on rate of enzyme level variations to slope of the cone variations are determined. In the biosensor, as the level of enzyme rises in all three geometries, the biosensor output current increases. Under the same conditions, the sensitivity of biosensor in upright circular cone is more than the other two geometries and increases with a decrease in conical gradient. As long as the enzymatic properties are the same, the more biosensor's number, the more sensitivity.Moreover, a concept known as reduced dimensionless current is introduced by providing and calculating dimensionless current in the biosensor.
Zahra Mollahoseini; Bahman Vahidi
Volume 12, Issue 2 , September 2018, , Pages 125-136
Abstract
For patients with chronic pulmonary disease, artificial lungs to which right ventricular pumps blood flow is considered as a bridge to lung transplantation. The performance of this device is measured by several criteria, including the efficiency of the device in gas exchange, non-damage to blood cells ...
Read More
For patients with chronic pulmonary disease, artificial lungs to which right ventricular pumps blood flow is considered as a bridge to lung transplantation. The performance of this device is measured by several criteria, including the efficiency of the device in gas exchange, non-damage to blood cells and low impedance compared to normal lung. In this study, the non-Newtonian blood flow around arrays of hollow fibers, as a model of fiber bundles in artificial lungs, was numerically investigated by finite volume. Two types of square and diagonal arrangements for fibers were considered to examine the effect of arrangement, besides the inlet velocity effect on the flow distribution, shear stress and the exchanged oxygen concentration between the surface of the fibers and the blood stream. It was observed that the flow velocity and shear stress in the diagonal arrangement were far more than the square arrangement that for the maximum velocity (10/87 cm/s), the shear stress on the fibers in the diagonal arrangement was about 3.5 times that of the square arrangement. Also, there was a significant difference between the results of this analysis and the results of other studies in which oxygen exchange was ignored, which illustrates the importance of gas exchange modeling. As a measure of the efficiency of the device, from the viewpoint of gas exchange, the mass flow rate of oxygen was investigated in the output of the domain. As a result, the diagonal arrangement is much more efficient in oxygen exchange. However, there was a higher pressure drop across the fibers, for a diagonal arrangement, in comparison with the square arrangement. The results of this simulation can be a good starting point for optimal artificial lung design and can be effective in optimizing the design of clinical trials.
Bioelectrics
Samira Abbasi
Volume 11, Issue 2 , June 2017, , Pages 127-135
Abstract
Neural function depends on the received synapses and the intrinsic properties of the neuron. However, synaptic integration and intrinsic responses can largely depend on the synaptic inputs. In this respect, deep cerebellar nuclei (DCN) neurons which receive inhibitory synapses from Purkinje cells (PCs) ...
Read More
Neural function depends on the received synapses and the intrinsic properties of the neuron. However, synaptic integration and intrinsic responses can largely depend on the synaptic inputs. In this respect, deep cerebellar nuclei (DCN) neurons which receive inhibitory synapses from Purkinje cells (PCs) are of interest. Transmission of behavior from PC to DCN in awake animal and how this information is coded by the deep cerebellar nuclei remain unknown. To investigate this issue, simultaneous recordings from about 50 Purkinje cells converged to each DCN is required, which is impossible in experiments. Therefore, it is required to use modeling techniques. In this study, to explore the effect of Purkinje cells inputs on the power spectral of DCN output, the transmission of behavioral information from the Purkinje cell to the DCN, and behavior coding by the DCN, artificial spike trains (ASTs) of the Purkinje cell were generated, and behavioral modulation (respiration) was added to them, then, ASTs were applied to the DCN model. Power spectral density analysis of the DCN firing in response to the synaptic inputs from Purkinje cells was made and the frequency bands of the DCN output were analyzed. Results showed that the behavioral modulation frequency is reflected in the DCN spectrum and a peak is visible at low-frequencies at the power spectral of the DCN output in response to the behavioral modulation received from Purkinje cells. On the other hand, the previous study has shown that DCN performs frequency coding in response to the behavioral modulation received from Purkinje cells. Results of the present study coud confirm the frequency coding by the DCN. In addition, a high-frequency peak was observed, which coud be due to the tonic firing of the DCN.
Biological System Control / Biocontrol
Amir Veisi; Hadi Delavari
Volume 15, Issue 2 , August 2021, , Pages 127-139
Abstract
Coronavirus, or Covid 19, is a contagious disease caused by the coronavirus and is a threat to the health and economy of countries. Although vaccine production and distribution are currently underway, but non-pharmacological interventions are still being implemented as an important and fundamental strategy ...
Read More
Coronavirus, or Covid 19, is a contagious disease caused by the coronavirus and is a threat to the health and economy of countries. Although vaccine production and distribution are currently underway, but non-pharmacological interventions are still being implemented as an important and fundamental strategy to control the spread of the virus in countries around the world. Now, according to the existing conditions, having a suitable dynamic model of this disease will provide information to the relevant authorities about the behavior, prevalence, speed of transmission, and other parameters. Various mathematical modeling methods have been proposed to analyze the transmission patterns of this new disease. In this paper, using fractional calculus, the dynamics of Covid 19 will be investigated. One of the major advantages of fractional calculus, which can be very effective in modeling and controlling epidemics, is its long-term memory property. With a dynamic model of virus transmission and prevalence, focusing on a control strategy based on non-pharmacological interventions can be important. In this paper, a new adaptive fractional order sliding mode controller is proposed for non-pharmacological decisions. The proposed method in this paper for controlling non-pharmacological interventions is an adaptive fractional order active sliding mode control, which can have a good performance due to its robustness against parameter uncertainty and system disturbances.
Cardiovascular Biomechanics
Faramarz Firouzi; Nasser Fatouraee; Siamak Najarian
Volume -1, Issue 2 , June 2005, , Pages 129-142
Abstract
Nowadays in the industrial world, because of increase of heart transplantation demand, long-term ventricular assist devices (VAD) are more needed. Implantable sac-type is one of the newest of them producing pulsatile flow. In this research, three different models of sac-type VAD are numerically simulated. ...
Read More
Nowadays in the industrial world, because of increase of heart transplantation demand, long-term ventricular assist devices (VAD) are more needed. Implantable sac-type is one of the newest of them producing pulsatile flow. In this research, three different models of sac-type VAD are numerically simulated. Simple motion is supposed for moving wall in model 1. In model 2, the motion of moving wall is assumed wavy form to study the effect of moving wall form on blood flow. In model 3, the pressure boundary condition is added to model 2. In this model, the effect of actual blood pressure on flow pattern is considered. Results of each model demonstrate the viscose term of blood flow stresses applied to the membrane is negligible, and only pressure term is effective. However, the motional pattern of membrane and also applied pressure on boundary are approximately ineffective on blood flow pattern.
Biodynamics & Biocinematics
Amirhosein Javanfar; Mahdi Bamdad
Volume 16, Issue 2 , September 2022, , Pages 133-145
Abstract
Biomechanical modeling of human joints has been considered for a long time by researchers due to its high importance and application. Therefore, methods of modeling joints, and kinematic and dynamic analysis of human movement have continuously been developing. In this paper, a biomechanical human knee ...
Read More
Biomechanical modeling of human joints has been considered for a long time by researchers due to its high importance and application. Therefore, methods of modeling joints, and kinematic and dynamic analysis of human movement have continuously been developing. In this paper, a biomechanical human knee model is developed, and a generic procedure for dynamic analysis of contact problems in combination with the musculoskeletal model is introduced. The development of this knee dynamic model includes the geometric expression of collision curves and an algorithm for determining collision points. This presentation addresses cartilage penetration depth and contact force calculation through nonlinear discontinuous contact law. Therefore, the femur and tibia's relative motion is modeled through the combined collision reactions of cartilage and bone in the knee. Moreover, two knee models, the novel curve fitted-plane contact model, and the spherical-plane contact model, have been compared, and a personalized model has been developed for such cases as knee osteoarthritis. There is a difference (average 12%) between the results of the enhanced model and the sphere on the plane model in the cartilage penetration. In the simulation, maximum penetration depth in a healthy knee is reported to be 0.705 mm, while in a 75% KOA is 0.521 mm, including 0.5 mm cartilage-cartilage contact and 0.021 mm bone-bone contact. The contact force is not increased in KOA despite the general belief. The cartilage penetration depth exceeds cartilage thickness, and the bone-bone contact leads to pain. It is a suitable tool for the analysis and control of the auxiliary device in order to control the relative motion of the tibia femur and their separation in patients with osteoarthritis of the knee.
Tissue Engineering
Zakieh Alihemmati; Bahman Vahidi; Nooshin Haghighipour
Volume 8, Issue 2 , June 2014, , Pages 135-149
Abstract
Body cells, including mesenchymal stem cells are subject to a lot of mechanical forces. The type and magnitude of these forces are different in different physiological and pathological conditions. They cause a wide variety of cell responses and are able to change metabolisms and functions of the cell. ...
Read More
Body cells, including mesenchymal stem cells are subject to a lot of mechanical forces. The type and magnitude of these forces are different in different physiological and pathological conditions. They cause a wide variety of cell responses and are able to change metabolisms and functions of the cell. Analysis of stem cell response to mechanical stimulation is very important in recognizing healthy and diseased condition of tissues and cells. Differentiation potential of mesenchymal stem cells to specialized cells makes them important cell sources in tissue engineering. In this study, atomic force microscopy and finite element method and used mechanical effects on a stem cellaresimulated which includes cell behavior due to strain andstress distributions in internal components of the cell. In this study, the ADINA software used to simulate mechanical behavior of the cell components (cell membrane, cytoplasm and nucleus) under a compressiveload. Results indicate mechanical response of stem cells in the body through which they can differentiate into bone cells and cartilage under compressive loads in the physiological range. This study has some considerable innovations as compared with the similar studies in the literature which is because of the kind of cells has been used (adipose-derived stem cells) as well as and also using precise material models for cell components based on the data extracted from laboratory tests for mechanical properties of the cell. Furthermore, this study can be considered as an important initial step for future studies on different patho-cells and analyzing their responses to mechanical loading using a similar method of this study to find new diagnostic methods. Also, it can be used to deepen pathological studies of the cells and the tissues.
Biological Computer Modeling / Biological Computer Simulation
Mahdie Roghani Yazdi; Nadia Naghavi; Faride Sadat Hosseini
Volume 9, Issue 2 , July 2015, , Pages 143-161
Abstract
A tumor cannot grow more than a few millimeters without a blood supply (avascular tumor), and for further growth it must initiate angiogenesis process. A vascularized tumor, which is permeated with blood vessels, rapidly increases in mass because of the new source of oxygen. In this study, a discrete ...
Read More
A tumor cannot grow more than a few millimeters without a blood supply (avascular tumor), and for further growth it must initiate angiogenesis process. A vascularized tumor, which is permeated with blood vessels, rapidly increases in mass because of the new source of oxygen. In this study, a discrete mathematical model of angiogenesis process with considering the penetration of blood flow through the vessels in the two-dimensional network is presented. This structure is coupled with an adaptive model of sprouts spacing along the parent blood vessel at the beginning of the angiogenesis process. Then, progression of these sprouts in the extracellular matrix and their penetration into the tumor as well as penetration of blood flow through the capillary structure is presented. This model incorporates three steps of adaptive sprout spacing along the parent blood vessel, sprout progression, and blood flow and network remodeling. Then, based on the simulated vasculature network, oxygentransmission and other vital chemicals needed for continuous tumor growth are simulated. In this model we assumed that the growth of the tumor is driven by cell division. The tumor growth and angiogenesis are coupled by the changes of micro environment including oxygen, tumor growth factor, and the extracellular matrix concentration. Also, we have tried to create space and time adaptations in parameters of the model.
Nano-Biomaterials
Zeynab Fereshteh; Mohammad Hossein Fathi; Reza Mozaffarinia
Volume 6, Issue 3 , June 2012, , Pages 177-193
Abstract
The aim of this study was to prepare and characterize the novel poly (ε-caprolactone) / Mg-doped fluorapatite nanoparticles (PCL / nMg-FA) composite scaffolds by electrospinning method. The optimized composite was achieved by changing of electrospinning parameters such as solvent, polymer concentration, ...
Read More
The aim of this study was to prepare and characterize the novel poly (ε-caprolactone) / Mg-doped fluorapatite nanoparticles (PCL / nMg-FA) composite scaffolds by electrospinning method. The optimized composite was achieved by changing of electrospinning parameters such as solvent, polymer concentration, applied voltage, nozzle to collector distance and content of ceramic. It was shown that the diameter size of fibers decreased by adjusting the viscosity and conductivity solution. Optimal samples were studied with transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA). According to TEM and the X-ray maps of the scaffolds, Mg-FA particles were homogeneously dispersed into the nanofibers without any agglomeration. It is noteworthy that was not any surfactant in this study. Also results of XRD show no chemical reactions between polymeric solution components. Mechanical properties of the scaffolds were also evaluated. Results showed that tensional strength of scaffolds and also thermal stability increased by increasing the weight ratio of nanoparticles up to 5 wt. %.
Biomechanics of Bone / Bone Biomechanics
Ahmad Raeisi Najafi; Ahmad Reza Arshi; Mohammad Reza Eslami; Shahriar Fariborz; Mansour Moeinzadeh
Volume 1, Issue 3 , June 2007, , Pages 177-188
Abstract
A two dimensional finite element model for the human Haversian cortical bone is represented. The interstitial bone tissue, the osteons and the cement line were modeled as the matrix, the fibers and the interface, respectively. This was due to similarities between fiber-ceramic composite materials and ...
Read More
A two dimensional finite element model for the human Haversian cortical bone is represented. The interstitial bone tissue, the osteons and the cement line were modeled as the matrix, the fibers and the interface, respectively. This was due to similarities between fiber-ceramic composite materials and the human Haversian cortical bone. The stress intensity factor in the microcrack tips vicinity was computed using the linear elastic fracture mechanics theory and assuming a plane strain condition. It was therefore possible to study the effect of microstructure and mechanical properties of Haversian cortical bone on microcrack propagation trajectory. The results indicated that this effect was limited to the vicinity of the osteon. If both osteon and cement line were assumed to be softer than the interstitial tissue, the stress intensity factor was increased when the crack distance to the osteon reduced. The stress intensity factor decreased if both osteon and cement line were assumed to be stiffer than the interstitial tissue. The resulting simulation indicated that the effect of existence of osteon on the stress intensity factor was no significance, if both the interstitial tissue and cement line were assumed either stiffer or softer than the osteon. Microcrack trajectory was observed to deviate from the osteon under tensile loading; indicating an independence from the mechanical properties of various tissues. In fact, the microcrack adopts a trajectory between the osteons, thereby increasing the necessary absorbed energy for fracture. This results in an increase in the human Haversian cortical bone toughness. The result of this finite element modeling has been confirmed by through evaluation and comparison made with experimental results.
