Biomechanics / Biomechanical Engineering
Nima Sarrafzadeh Ghadimi; Farzan Ghalichi; Hanieh Niroomand-Oscuii; Nasser Fatouraee
Volume 15, Issue 4 , March 2022, , Pages 299-312
Abstract
Considering the common diseases that occur in the heart valves, it is possible that these valves can be replaced with artificial valves. This article examines different types of polymeric valves for the possibility of replacement in the human body. Different models are compared and the optimal valve ...
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Considering the common diseases that occur in the heart valves, it is possible that these valves can be replaced with artificial valves. This article examines different types of polymeric valves for the possibility of replacement in the human body. Different models are compared and the optimal valve is presented. For complete information, refer to the text of the article.
Behrouz Jafarzadeh; Hanieh Niroomand-Oscuii; Farzan Ghalichi
Volume 12, Issue 4 , January 2019, , Pages 287-297
Abstract
Mock circulation systems are necessary for in vitro experiments and development of the ventricular assist devices, heart valves, total artificial hearts, artificial lungs, vascular grafts and intra-aortic balloon pumps. Tissue engineering of heart valves and other preliminary studies on the cardiovascular ...
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Mock circulation systems are necessary for in vitro experiments and development of the ventricular assist devices, heart valves, total artificial hearts, artificial lungs, vascular grafts and intra-aortic balloon pumps. Tissue engineering of heart valves and other preliminary studies on the cardiovascular system can also achieve with mock circulation systems. One of the major parts of these systems is generating of pulsatile flows like heart. In this study a mock circulation system with ability of physiological pressure and flow simulation in both healthy and diseases heart has been designed and manufactured. This setup can produce pressure and flow pulse by using a positive displacement pump with programing of movement pattern of stepper motor. This pump was manufactured after designing by Solid-works software for using in the mock circulation system. For testing this setup, several experiments with different values of peripheral resistance and arterial compliance and changing the pattern of the stepper motor have been performed. The results show modifying the pattern of the stepper motor from uniform speed to variable speed in one cycle (360 degree), as well as changing in arterial compliance and peripheral resistance, can produce waveform of physiological pressure and flow. The results confirm the reliable performance of this system in simulating physiological conditions. The designed system has the software capability to generate different waveforms.
Gait Analysis
Maryam Hajizadeh; Alireza Hashemi Oskouei; Farzan Ghalichi
Volume 11, Issue 3 , September 2017, , Pages 201-210
Abstract
Anterior cruciate ligament (ACL) rupture is one of the most costly knee injuries, usually occurring to young athletes, often leading to functional instability, inability to return to previous levels of physical activity, and premature osteoarthritis (OA). The main function of ACL is controlling anterior ...
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Anterior cruciate ligament (ACL) rupture is one of the most costly knee injuries, usually occurring to young athletes, often leading to functional instability, inability to return to previous levels of physical activity, and premature osteoarthritis (OA). The main function of ACL is controlling anterior tibia translation as well as axial tibia rotation. Therefore, patients with ACL deficiency (ACLD) have to use different compensatory mechanisms and kinematic changes to maintain their stability during different activities. The study aims to measure the reliability of knee kinematics and ground reaction force during stair negotiation. Fifteen participants with unilateral ACLD ascended 4-step staircase, where 8-10 reflective markers was inserted on each segment of lower extremity. Five-camera VICON system and 10-camera VICON system were used in the first and second phase of study, respectively. Intra-class correlation coefficient (ICC) and standard error of measurement (SEM) was calculated for each parameter in the knee events during stair climbing. The results showed high consistency of kinematic parameters and GRF components was handled through reliability and repeatability calculations. ICC (2,5) showed similar values in injured and healthy contralateral leg with the range of (0.59-0.98) for all knee joint rotation and GRF components.
Biomechanics / Biomechanical Engineering
Mehran Ashrafi; Farzan Ghalichi; Behnam Mirzakouchaki
Volume 10, Issue 2 , August 2016, , Pages 113-121
Abstract
Nowadays, the use of dental implants in people with osteoporosis is increasing. The consequences of osteoporosis can be important to the success of osteosynthesis devices, prosthetics and dental implants. Using bisphosphonates, which with impressing bone remodeling and decreasing bone catabolic activity ...
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Nowadays, the use of dental implants in people with osteoporosis is increasing. The consequences of osteoporosis can be important to the success of osteosynthesis devices, prosthetics and dental implants. Using bisphosphonates, which with impressing bone remodeling and decreasing bone catabolic activity lead to increase bone formation can be used as a solution to increase bone density in patients with osteoporosis, which normally osteoporosis is considered as a risk to the acceptance of dental implants by alveolar bone. This study examines the effect of different concentrations of bisphosphonates on bone remodeling. By improving bone remodeling model and taking into account the drug concentration effect on bone resorption, drug effect will be considered. For this purpose, 5, 10 and 20 mg of alendronate per implant and control sample are simulated for a period of 360 days. By comparing the results with control sample, with increasing the drug dose, decrease in bone stress, increase in bone density and thus increase in young's modulus was observed.
Artificial Organs
Erfan Nammakie; Hanieh Niroomand Oscuii; Farzan Ghalichi; Mojtaba Koochaki
Volume 9, Issue 2 , July 2015, , Pages 133-142
Abstract
Myocardial diseases are on the rise all over the world and due to lack of sufficient donors, heart transplants are not the perfect solutions to treat all patients with heart failure. Therefore, in recent years, blood pumps have received a worldwide admissibility and have become the unrivalled tools for ...
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Myocardial diseases are on the rise all over the world and due to lack of sufficient donors, heart transplants are not the perfect solutions to treat all patients with heart failure. Therefore, in recent years, blood pumps have received a worldwide admissibility and have become the unrivalled tools for replacing a failed heart. In addition to biological needs such as sufficient head and flow rate, an assist blood pump should be in an acceptable margin of safety in terms of blood injuries such as hemolysis and thrombosis. Reducing blood damages, minimizing dimensions, reducing exposure time and simulating blood flow of natural heart are amongst the greatest challenges in designing assist blood pumps. One of the most important factors in determining the amount of blood injuries inside the pump is the blades’ shape of different parts of the pump. Studies have been conducted about heart pumps show that it is feasible to increase the efficiency of the pump and reduce the stagnation points that lead tothrombus formation by changing the type of blades of the impeller. The purpose of this study is to compare the performance of several airfoils for the blades of the impeller of an assist heart pump in order to optimize the performance and efficiency of the pump and reduce blood damages.
Gait Analysis
Maryam Hajizade; Alireza Hashemi Oskouei; Farzan Ghalichi; Farhad Tabatabai Ghomshe; Mohammad Razi; Gisela Solo
Volume 9, Issue 1 , April 2015, , Pages 17-31
Abstract
Patients with ACL deficiency (ACLD) have to use different compensatory mechanisms to maintain their stability during daily activities. The aim of this study is to determine the differences in 3D kinematics and peak ground reaction forces (GRF) between ACL deficient legs and healthy contralateral legs ...
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Patients with ACL deficiency (ACLD) have to use different compensatory mechanisms to maintain their stability during daily activities. The aim of this study is to determine the differences in 3D kinematics and peak ground reaction forces (GRF) between ACL deficient legs and healthy contralateral legs during stair ascent. Eight subjects with unilateral ACL deficiency participated in this study. Healthy contralateral legs were considered as control group for further comparisons to ACL deficient legs. A six camera VICON motion analysis system and 2 portable force plates were used to record the locomotion while walking up custom-made stairs with two different step heights. Advanced OSSCA technique was used to assess tibiofemoral knee kinematics, a combination of symmetrical axis of rotation (SARA), symmetrical center of rotation estimation (SCoRE) and optimal common shape technique (OCST). The results of this study show that participants with ACLD experienced different kinematics and peak GRFs in different step heights (p<0.05). During ascending stairs with 17cm height, legs with ACLD exhibited less varus, more external rotation and less impact peak in pre-swing stance and early swing phase compared to contralateral healthy leg (p<0.05). The other stair height, 20 cm, resulted in more extension, more valgus and more external tibia rotation in injured leg compared to contralateral leg during terminal extension of stance phase (p<0.05). In both step heights, injured leg reached it maximum extension peak at an earlier time. The results of this study imply that participants with ACLD make use of different 3D rotational tiobiofemoral kinematics and different GRF compared to healthy contralateral leg. These compensatory mechanisms would finally bring about different knee joint loading, which provides the potential of cartilage degeneration and early osteoarthritis.
Mehran Ashrafi; Farzan Ghalichi; Behnam Mirzakouchaki
Volume 9, Issue 1 , April 2015, , Pages 49-57
Abstract
Periodontal ligament (PDL) is a soft fibrous tissuewhich is located between tooth and alveolar bone. Because the tissue is softer than the surrounding tissue, tooth movement is forced to follow the movement of the soft tissue. The goal of this study is comparison of periodentium related to single and ...
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Periodontal ligament (PDL) is a soft fibrous tissuewhich is located between tooth and alveolar bone. Because the tissue is softer than the surrounding tissue, tooth movement is forced to follow the movement of the soft tissue. The goal of this study is comparison of periodentium related to single and two root teeth behavior with applying different loads. The modeling of the real 3D geometry of incisor and premolar periodentium is carried out using micro CT scan. PDL is considered as hyperelastic material and stress-strain distribution was investigated by applying different loads. The results of finite element simulation show that tooth displacement with different loading is not necessarily in direction of loading and also stress distribution show that PDL absorbs the stresses, consequently alveolar carry less stresses. Strain distribution in PDL and alveolar bone stress represents uniform distribution of force in two root tooth. The analogy of results shows the accommodation with pervious studies.
Orthotics & Prosthesis
Mostafa Lashgari; Farzan Ghalichi; Behnam Mirzakouchaki
Volume 7, Issue 4 , June 2013, , Pages 341-349
Abstract
Orthodontic specialists interest in study of tooth movement mechanic, such as the relationship between applied force and the rate of tooth movement in orthodontic treatment. It is because of the complexity and variety of factors that can affect orthodontic treatment. The friction force at the contact ...
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Orthodontic specialists interest in study of tooth movement mechanic, such as the relationship between applied force and the rate of tooth movement in orthodontic treatment. It is because of the complexity and variety of factors that can affect orthodontic treatment. The friction force at the contact surfaces with an undetermined magnitude, makes the orthodontic treatment unpredictable. In this study, friction coefficient and forces were investigated in new designed bracket that had beveled edge which has been modeled based on standard bracket. Torque, tip and angulations angles of the brackets slot are designed. Arch wires were modeled by two rectangular and circular cross-sections and the effect of geometry on the stress distribution and the friction force was investigated using Finite Element Method (FEM). The results have showed that the stress concentration generated in the bracket which has been the most curvature, decreased compared to the standard bracket at the contact wire and bracket braces. In addition, results have showed that friction in the beveled edge bracket was significantly decline compared to the standard bracket and also are less than the type with minor curvature. Results of investigation of friction between the two types of round and square wire, have revealed that the round wire has lower friction and confirmed previous studies. Finally, due to the reduced friction in the brackets which have been the most curvature, this type of design is appropriate to decrease friction force.
Cardiovascular Biomechanics
Hamed Khalesi; Hanie Niroomand Oscuii; Farzan Ghalichi
Volume 5, Issue 2 , June 2011, , Pages 143-149
Abstract
Prediction of the relationship between different types of mechanical loading and the failure of the intervertebral disc is so important to identify the risk factors which are difficult to study in vivo and in vitro. On the basis of finite element methods some of these issues may be overcome enabling ...
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Prediction of the relationship between different types of mechanical loading and the failure of the intervertebral disc is so important to identify the risk factors which are difficult to study in vivo and in vitro. On the basis of finite element methods some of these issues may be overcome enabling more detailed assessment of the biomechanical behavior of the intervertebral disc. The objective of this paper is to develop a nonlinear axisymmetric poroelastic finite element model of lumbar motion segment and show its capability for studying the time-dependent response of disc. After comparison of the response of different models in quasi-static analysis, the poroelastic model of intervertebral disc is presented and the results of short-term, long-term creep tests and cyclic loading were investigated. The results of the poroelastic model are in agreement with experimental ones reported in the literature. Hence, this model can be used to study how different dynamic loading regimes are important as risk factors for initiation of intervertebral disc degeneration.
Fluid-Structure Interaction in Biological Media / FSI
Hamed Khalesi; Hanie Niroomand Oscuii; Farzan Ghalichi
Volume 5, Issue 1 , June 2011, , Pages 67-78
Abstract
Biomechanics believe that, the arteries are remodeled under the influence of hemodynamic and mechanical factors. Biomechanical factors such as Opening Angle and the Tethering could have important effects on this phenomenon. The effects of various Opening Angle and Tethering during thoracic aorta aging ...
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Biomechanics believe that, the arteries are remodeled under the influence of hemodynamic and mechanical factors. Biomechanical factors such as Opening Angle and the Tethering could have important effects on this phenomenon. The effects of various Opening Angle and Tethering during thoracic aorta aging on arterial wall stress have been studied. ADINA software is used for numerical simulation.In this study, for the first time, numerical methods of Fluid-Structure Interaction have been used to study and simulate effects of Opening Angle and the Tethering in elastic artery remodeling due to age. Large deformation theory has been used for modeling changes of arterial radius; furthermore, behavior of Newtonian fluid has been used for blood. Pulsatile pressure and physiological Pulsatile flow waveforms have been applied to simulate transient behavior of arterial system. The results show that opening angle has further effect on circumferential stress so smooth distribution of circumferential stress on the wall accrued. Also, increasing Opening Angle with age reverses the circumferential stress distribution slop across the arterial wall. Tethering has further effect on axial stress. Decreasing Tethering in remodeling process over age leads to increase stress levels in the aged artery. Also, arterial wall shear stress in remodeled artery shows significant reduction in maximum, mean and amplitude values that caused reduction of pathological effects of endothelial cells.
Cardiovascular Biomechanics
Ahmad Ramezani Saadatabadi; Majid Ahmadlouy Darab; Farzan Ghalichi; Ataollah Kamyabi
Volume 4, Issue 1 , June 2010, , Pages 65-72
Abstract
This study aimed to simulate three dimensional pulsatile Newtonian blood flow in End-to-Side anastomosis of Aorta-coronary bypass using ascending aorta velocity flow wave as graft inlet and left anterior descending coronary artery (LAD) velocity flow wave as coronary inlet for 50% symmetric stenosis. ...
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This study aimed to simulate three dimensional pulsatile Newtonian blood flow in End-to-Side anastomosis of Aorta-coronary bypass using ascending aorta velocity flow wave as graft inlet and left anterior descending coronary artery (LAD) velocity flow wave as coronary inlet for 50% symmetric stenosis. We have supposed that LAD walls were rigid and had no spatial mobility due to heart beats. In order to investigate the graft angles effects on blood flow, especially on the wall shear stress magnitudes, 20, 30 and 40 degrees graft angles were used. Using ascending aorta and LAD pulses simultaneously as boundary conditions for the first time is one of the important features of this study because already these boundary conditions have not been used simultaneously. We considered prograde flow effects. Appearance of recirculation flows in various degrees of grafting angles, existence of secondary flows and increased in their effects specially in pulses deceleration phase, existence of double core helical flows and increase in their intensify specially at the systole peak and the rise in the spatial wall shear stress gradient by increasing in the graft angle are some of important results of this study. Finally, according to our assumptions we suggest 20 to 30 degrees as desired angles for grafting.
Fluid-Structure Interaction in Biological Media / FSI
Hanie Niroomand Oscuii; Farzan Ghalichi; Mohammad Tafazzoli Shadpour
Volume 2, Issue 1 , June 2008, , Pages 1-8
Abstract
In this paper, we studied the effect of mechanical loading on remodeling process with aging in muscular arteries. Based on the gathered experimental data, the brachial artery was selected for simulation. In this simulation, pulsatile pressure and flow waves were considered as boundary conditions to study ...
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In this paper, we studied the effect of mechanical loading on remodeling process with aging in muscular arteries. Based on the gathered experimental data, the brachial artery was selected for simulation. In this simulation, pulsatile pressure and flow waves were considered as boundary conditions to study the effect of circumferential stress and wall shear stress on the remodeling process. FSI based transient numerical simulation was used to solve the fluid and solid equations. The results of three remodeling schemes showed that inward eutrophic scheme is an optimum algorithm for brachia! Artery remodeling with aging. Such remodeling scheme causes the most optimized outcome to keep circumferential stress with minimal alteration.
Fluid-Structure Interaction in Biological Media / FSI
Hamed Avari; Farzan Ghalichi; Majid Ahmadlouy Darab
Volume 2, Issue 1 , June 2008, , Pages 39-46
Abstract
Adjusting the rhythm of breath is one of the important parameters that a successful athlete must consider. In this paper, the relationship between man's activity and respiration rhythm is studied. A numerical simulation is carried out on a 2D axi-symmetric model using computational fluid dynamics (CFD) ...
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Adjusting the rhythm of breath is one of the important parameters that a successful athlete must consider. In this paper, the relationship between man's activity and respiration rhythm is studied. A numerical simulation is carried out on a 2D axi-symmetric model using computational fluid dynamics (CFD) method. The model considers the oxygen uptake in the pulmonary capillaries in alveolar microcirculation system. The geometry consists of three main parts: a stationary capillary membrane, a moving plasma region and four semi-circular-shaped RBCs. Results show an inverse relationship between saturation time of RBCs and respiration rhythm. Using an inversion factor, a relationship is presented to assess the proper respiration rhythm for different exercise states.
Bioheat Transfer
Farzan Ghalichi; Sohrab Behnia
Volume 1, Issue 1 , June 2007, , Pages 1-8
Abstract
The methods of focusing ultrasonic waves in order to apply hyperthermia cancer therapy have studied and a transducer capable of focusing waves on cancerous tissues with the aid of its piezoelectricelements has introduced. The amount of absorbed energy was computed by solving numerically the acoustic ...
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The methods of focusing ultrasonic waves in order to apply hyperthermia cancer therapy have studied and a transducer capable of focusing waves on cancerous tissues with the aid of its piezoelectricelements has introduced. The amount of absorbed energy was computed by solving numerically the acoustic pressure equation using Rayleigh-Summerfield Integral, with the intention to determine the optimum spatial array of piezoelectric elements for energy concentration. In order to control the treatment procedure, the numerical solution of Bio-heat Transfer Equation (BHTE), along with the finite-element simulation of thermal energy distribution in a cervix cancerous tissue is considered.
Fluid-Structure Interaction in Biological Media / FSI
Farzan Ghalichi; Majid Ahmadlouy Darab; Ahmad Ramezani Saadatabadi
Volume 1, Issue 2 , June 2007, , Pages 111-117
Abstract
In order to compare the aorta-coronary and coronary-coronary bypasses blood flow fields in the Endto-Side Anastomosis, we carried out numerical simulation of three dimensional pulsatile blood flow for 50% stenosis by using FLUENT 5.2.3 software. In this study, the blood was assumed to be as the Newtonian, ...
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In order to compare the aorta-coronary and coronary-coronary bypasses blood flow fields in the Endto-Side Anastomosis, we carried out numerical simulation of three dimensional pulsatile blood flow for 50% stenosis by using FLUENT 5.2.3 software. In this study, the blood was assumed to be as the Newtonian, incompressible and homogeneous fluid. The arterial wall was also considered to be rigid. Non-existence of the secondary flows in the coronary-coronary bypass blood flow fields for various degrees of bypass grafting angles against the aorta-coronary-coronary bypass, return of total blood flow toward upstream in the coronary-coronary bypass three times over a heart cycle, high temporary oscillation in the wall shear stress magnitudes for the aorta-coronary bypass and low wall shear stress magnitudes for the coronary-coronary bypass were of the important results.
