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RISS 인기검색어
- 검색키워드
- 저자 : Nasser Fatouraee (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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A model for mass diffusion in infarcted tissues by using LBM
Mina Alafzadeh,Ebrahim Shirani,Effat Yahaghi,Nasser Fatouraee 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11
In the present study, a new mathematical model for mass transfer in extra-vascular space is presented to indicate the effect of dead cells in infarcted tissues. This model is useful for predicting the results of experiments which are designed to distinguish normal from infarcted tissues and it can be used to approximate the percent of damaged cells in the infarcted tissue. The increase of permeability due to existence of dead cells caused by infarction is modeled as a sink term. The present model is validated for two different solutes by comparing their results with the existing experimental data. It is shown that the presented model is an appropriate model for simulating mass transfer in tissues. Furthermore, the sensitivity of the model to the effective diffusion coefficient, Schmidt number, porosity and Damkohler number is examined. The simulations show that permeability of dead cells significantly affects the volume of the contrast agent in the infarcted tissue. The results also indicate that the Schmidt number not only affects the mass diffusion through damaged tissues, but also influences the partition coefficient. The other parameters mentioned above have effects on the amount of mass diffusion into the infarcted tissue when the extent of damage in tissues is changed.
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A novel model for effective diffusion coefficient in brain capillary
Mina Alafzadeh,Ebrahim Shirani,Effat Yahaghi,Nasser Fatouraee 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6
A new and rather accurate correlation for prediction of effective diffusion coefficient is proposed for the biological tissue in the brain. Blood flow in brain capillaries and mass diffusion process in the tissues as a porous media, surrounding the capillaries, are simulated byusing the random nature of tissue structure and the lattice Boltzmann method. The present correlation which is obtained from the latticeBoltzmann method and is taken into account the effects of the pore or cell structure is validated by comparing it with that of theoretical,statistical and experimental data. A very good coincidence between experimental data and present results have been found. So, the resultsshow that the new model for the effective diffusion coefficient is a good choice for normal and damaged brain tissue and it producesmore accurate results than existing models.
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Effat Soleimani,Manijhe Mokhtari-Dizaji,Nasser Fatouraee,Hazhir Saberi 대한초음파의학회 2017 ULTRASONOGRAPHY Vol.36 No.2
Purpose: The aim of this study was to introduce and implement a noninvasive method to derive the carotid artery pressure waveform directly by processing diagnostic sonograms of the carotid artery. Methods: Ultrasound image sequences of 20 healthy male subjects (age, 36±9 years) were recorded during three cardiac cycles. The internal diameter and blood velocity waveforms were extracted from consecutive sonograms over the cardiac cycles by using custom analysis programs written in MATLAB. Finally, the application of a mathematical equation resulted in time changes of the arterial pressure. The resulting pressures were calibrated using the mean and the diastolic pressure of the radial artery. Results: A good correlation was found between the mean carotid blood pressure obtained from the ultrasound image processing and the mean radial blood pressure obtained using a standard digital sphygmomanometer (R=0.91). The mean absolute difference between the carotid calibrated pulse pressures and those measured clinically was -1.333±6.548 mm Hg. Conclusion: The results of this study suggest that consecutive sonograms of the carotid artery can be used for estimating a blood pressure waveform. We believe that our results promote a noninvasive technique for clinical applications that overcomes the reproducibility problems of common carotid artery tonometry with technical and anatomical causes.
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Effat Soleimani,Manijhe Mokhtari-Dizaji,Nasser Fatouraee,Hazhir Saberi 대한초음파의학회 2021 ULTRASONOGRAPHY Vol.40 No.3
Purpose: This study investigated the accuracy of models reconstructed from ultrasound image processing by comparing the radial displacement waveforms of a subject-specific artery model and evaluated stress changes in the proximal shoulder, throat, and distal shoulder of the plaques depending on the degree of carotid artery stenosis. Methods: Three groups of subjects (healthy and with less than 50% or more carotid stenosis) were evaluated with ultrasonography. Two-dimensional transverse imaging of the common carotid artery was performed to reconstruct the geometry. A longitudinal view of the same region was recorded to extract the Kelvin viscoelastic model parameters. The pulse pressure waveform and the effective pressure of perivascular tissue were loaded onto the internal and external walls of the model. Effective, circumferential, and principal stresses applied to the plaque throat, proximal shoulder, and distal shoulder in the transverse planes were extracted. Results: The radial displacement waveforms of the model were closely correlated with those of image processing in all three groups. The mean of the effective, circumferential, and principal stresses of the healthy arteries were 15.01±4.93, 12.97±5.07, and 12.39±2.86 kPa, respectively. As stenosis increased from mild to significant, the mean values of the effective, circumferential, and first principal stresses increased significantly (97%, 74%, and 103% at the plaque throat, respectively) (P<0.05). The minimum effective stress was at the lipid pool. The effective stress in calcified areas was higher than in other parts of the artery wall. Conclusion: This model can discriminate differences in stresses applied to mildly and severely stenotic plaques.
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