Search for: bioengineering
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    Evaluation of trunk muscle forces and internal loads using kinematics-based modeling

    , Article Proceedings of the IASTED International Conference on Biomedical Engineering, Salzburg, 25 June 2003 through 27 June 2003 ; 2003 , Pages 114-119 ; 0889863539 (ISBN) Shirazi Adl, A ; El-Rich, M ; Parnianpour, M ; Sharif University of Technology
    Trunk muscle forces and internal loads are computed under simulated standing postures while carrying a load using a nonlinear finite element model of the T1-S1 spine with realistic nonlinear load-displacement properties. A novel kinematics-based algorithm is applied that exploits a set of a priori known spinal sagittal rotations to solve the redundant active-passive system. The loads consist of upper body gravity distributed along the spine plus 200 N held in hands either in front or on sides. Predictions are in good agreement with reported measurements of posture, muscle EMG and intradiscal pressure. Minimal changes in posture (posterior pelvic tilt and lumbar flattening) substantially... 

    Bioengineering approaches for corneal regenerative medicine

    , Article Tissue Engineering and Regenerative Medicine ; Volume 17, Issue 5 , July , 2020 , Pages 567-593 Mahdavi, S. S ; Abdekhodaie, M. J ; Mashayekhan, S ; Baradaran Rafii, A ; Djalilian, A. R ; Sharif University of Technology
    Korean Tissue Engineering and Regenerative Medicine Society  2020
    Background:: Since the cornea is responsible for transmitting and focusing light into the eye, injury or pathology affecting any layer of the cornea can cause a detrimental effect on visual acuity. Aging is also a reason for corneal degeneration. Depending on the level of the injury, conservative therapies and donor tissue transplantation are the most common treatments for corneal diseases. Not only is there a lack of donor tissue and risk of infection/rejection, but the inherent ability of corneal cells and layers to regenerate has led to research in regenerative approaches and treatments. Methods:: In this review, we first discussed the anatomy of the cornea and the required properties for... 

    A Systems Dynamics Approach to Simulate Epidemic Spread of Covid-19

    , M.Sc. Thesis Sharif University of Technology Sepehri, Sepehr (Author) ; Roosta Azad, Reza (Supervisor)
    The outbreak of a type of corona virus in 2019, plunged the world into a huge panic. Businesses entered into an unprecedented recession and economic growth was severely reduced. Millions of people have been infected and unfortunately countless numbers have also lost their lives. This which quickly crossed the borders of countries, proved how much a not-so-deadly infectious disease can affect human life. Another point that was revealed was the importance of epidemiology knowledge. Since the beginning of the outbreak of this disease, scientists in this field have tried to predict the state of the disease in the coming days by presenting models. Many countries formed special working groups to... 

    Surface modification for titanium implants by hydroxyapatite nanocomposite

    , Article Caspian Journal of Internal Medicine ; Volume 3, Issue 3 , 2012 , Pages 460-465 ; 20086164 (ISSN) Family, R ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif University of Technology
    Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO... 

    Engineering 3D parallelized microfluidic droplet generators with equal flow profiles by computational fluid dynamics and stereolithographic printing

    , Article Lab on a Chip ; Volume 20, Issue 3 , 2020 , Pages 490-495 Kamperman, T ; Teixeira, L. M ; Salehi, S. S ; Kerckhofs, G ; Guyot, Y ; Geven, M ; Geris, L ; Grijpma, D ; Blanquer, S ; Leijten, J ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Microfluidic droplet generators excel in generating monodisperse micrometer-sized droplets and particles. However, the low throughput of conventional droplet generators hinders their clinical and industrial translation. Current approaches to parallelize microdevices are challenged by the two-dimensional nature of the standard fabrication methods. Here, we report the facile production of three-dimensionally (3D) parallelized microfluidic droplet generators consisting of stacked and radially multiplexed channel designs. Computational fluid dynamics simulations form the design basis for a microflow distributor that ensures similar flow rates through all droplet generators. Stereolithography is... 

    Trapezius muscle activity in using ordinary and ergonomically designed dentistry chairs

    , Article International Journal of Occupational and Environmental Medicine ; Volume 3, Issue 2 , Apr , 2012 , Pages 76-83 ; 20086520 (ISSN) Haddad, O ; Sanjari, M. A ; Amirfazli, A ; Narimani, R ; Parnianpour, M ; Sharif University of Technology
    Background: Most dentists complain of musculoskeletal disorders which can be caused by prolonged static posture lack of suitable rest and other physical and psychological problems. Objective: We evaluated a chair with a new ergonomic design which incorporated forward leaning chest and arm supports. Methods: The chair was evaluated in the laboratory during task simulation and EMG analysis on 12 students and subjectively assessed by 30 professional dentists using an 18-item questionnaire. EMG activity of right and left trapezius muscles for 12 male students with no musculoskeletal disorders was measured while simulating common tasks like working on the teeth of the lower jaw. Results:... 

    Fabrication and characterization of maleic anhydride grafted polypropylene membranes with high antifouling properties

    , Article Journal of Applied Polymer Science ; Volume 133, Issue 36 , 2016 ; 00218995 (ISSN) Jahanbakhshi, N ; Mousavi, S. A ; Farhadi, F ; Sharif University of Technology
    John Wiley and Sons Inc  2016
    In this study, maleic anhydride grafted polypropylene microporous flat-sheet membranes were prepared via a thermally induced phase separation method with a mixture of dibutyl phthalate and dioctyl phthalate as a diluent. The effects of the polymer composition and coagulation bath temperature on the morphology and performance of the fabricated membranes were investigated. The hydrophilicity results of the membranes demonstrated that membrane modification reduced the water contact angle by about 45°, whereas the pure water flux was enhanced about four times. The antifouling behavior of the fabricated membranes was also investigated in a membrane bioreactor. The results show that the pure water... 

    Mechanical reinforcement of urinary bladder matrix by electrospun polycaprolactone nanofibers

    , Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 3476-3480 ; 10263098 (ISSN) Ghafari, A. M ; Rajabi Zeleti, S ; Naji, M ; Ghanian, M. H ; Baharvand, H ; Sharif University of Technology
    For a successful repair and reconstruction of bladder tissue, fabrication of scaffolds with proper biochemical and biomechanical characteristics is necessary. Decellularized bladder tissue has been proposed in previous studies as a gold standard material for scaffold fabrication. However, weak mechanical properties of such a load-bearing tissue has remained a challenge. Incorporation of both biological and synthetic materials has been known as an effective strategy for improving mechanical and biological properties of the scaffolds. In the present work, a simple process was developed to fabricate hybrid hydrogel scaffolds with a biomimetic architecture from the natural urinary bladder... 

    Developmental barcoding of whole mouse via homing CRISPR

    , Article Science ; Volume 361, Issue 6405 , 2018 ; 00368075 (ISSN) Kalhor, R ; Kalhor, K ; Mejia, L ; Leeper, K ; Graveline, A ; Mali, P ; Church, G. M ; Sharif University of Technology

    Simulation of the effects of oxygen carriers and scaffold geometry on oxygen distribution and cell growth in a channeled scaffold for engineering myocardium

    , Article Mathematical Biosciences ; Volume 294 , 2017 , Pages 160-171 ; 00255564 (ISSN) Zehi Mofrad, A ; Mashayekhan, S ; Bastani, D ; Sharif University of Technology
    This study proposes a mathematical model to evaluate the impact of oxygen carriers and scaffold geometry on oxygen distribution and cell growth in a 3D cardiac construct using computational fluid dynamics (CFD). Flow equations, oxygen balance equation and cell balance equation were solved using special initial and boundary conditions. The modeling results revealed that 55% increase in cardiac cell density occurred by using 6.4% perfluorocarbon oxygen carrier (PFC) compared to pure culture medium without PFC supplementation. Moreover, the effects of the scaffold geometry on cell density were examined by changing the channel numbers and the construct length. A 30% increase in the average cells... 

    Stereolithography 3D bioprinting method for fabrication of human corneal stroma equivalent

    , Article Annals of Biomedical Engineering ; Volume 48, Issue 7 , June , 2020 , Pages 1955-1970 Mahdavi, S. S ; Abdekhodaie, M. J ; Kumar, H ; Mashayekhan, S ; Baradaran Rafii, A ; Kim, K ; Sharif University of Technology
    Springer  2020
    Abstract: 3D bioprinting technology is a promising approach for corneal stromal tissue regeneration. In this study, gelatin methacrylate (GelMA) mixed with corneal stromal cells was used as a bioink. The visible light-based stereolithography (SLA) 3D bioprinting method was utilized to print the anatomically similar dome-shaped structure of the human corneal stroma. Two different concentrations of GelMA macromer (7.5 and 12.5%) were tested for corneal stroma bioprinting. Due to high macromer concentrations, 12.5% GelMA was stiffer than 7.5% GelMA, which made it easier to handle. In terms of water content and optical transmittance of the bioprinted scaffolds, we observed that scaffold with...