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biodegradation
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Degradation behavior of the as-extruded and ECAP-processed Mg-4Zn alloy by Ca addition and hydrothermal coating
, Article Journal of Materials Research and Technology ; Volume 20 , 2022 , Pages 1204-1215 ; 22387854 (ISSN) ; Mohammadi Zerankeshi, M ; Nobakht Farin, F ; Alizadeh, R ; Mahmudi, R ; Sharif University of Technology
Elsevier Editora Ltda
2022
Abstract
Coating is an effective approach to address the high corrosion rate of biodegradable Mg alloys, as their main challenge toward their extensive use. In this regard, it was tried to control the degradation process of an Mg-4Zn alloy by Ca addition, equal channel angular pressing (ECAP), and hydrothermal coating. The obtained results indicated that excellent grain refinement induced by Ca incorporation and ECAP simultaneously, improved both mechanical strength and corrosion resistance of the Mg-based substrate. The achieved grain refinement resulted in a thicker, more compact and integrated coating, where the ECAP-processed Mg-4Zn-0.5Ca alloy exhibited the best coating quality with no...
Green composites in bone tissue engineering
, Article Emergent Materials ; Volume 5, Issue 3 , 2022 , Pages 603-620 ; 25225731 (ISSN) ; Vahabi, H ; Rabiee, N ; Rabiee, M ; Bagherzadeh, M ; Saeb, M. R ; Sharif University of Technology
Springer Nature
2022
Abstract
Natural and biodegradable polymers are of particular interest as green sources with low-cost and environmentally friendly features, and have been widely used for polymer composite development. The term “Green Composites” refers to polymer/filler systems in which polymer, filler, or sometimes both components are green in view of sources from which they are yielded or their biodegradability. Natural fibers obtained from plants, animals, and/or geological processes are a big class of green sources widely applied in green composite development. There has also been continued research on recycling of green composite as well as developing hybrid systems for advanced applications. In view of their...
Preparation of biodegradable gelatin/PVA porous scaffolds for skin regeneration
, Article Artificial Cells, Nanomedicine and Biotechnology ; Volume 45, Issue 5 , 2017 , Pages 928-935 ; 21691401 (ISSN) ; Dadbin, S ; Frounchi, M ; Rajabi, S ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
Porous scaffolds composed of gelatin/poly (vinyl alcohol), (Gel/PVA), were prepared using combination of freeze gelation and freeze drying methods. The effect of polymer concentration, gelatin/PVA ratio, and glutaraldehyde/gelatin ratio (GA/Gel) was investigated on morphology of pores, swelling ratio, biodegradation, and skin cell culture. At optimum preparation conditions the scaffolds had uniform pore size distributions showing high swelling ratio of 23.6. The scaffolds were of biodegradable nature and almost degraded in 28 days. Human dermal fibroblast cells (HDF) were cultured on the scaffolds and MTS assay was conducted to evaluate the influence of PVA on growth and proliferation of the...
A novel pathway to produce biodegradable and bioactive PLGA/TiO2 nanocomposite scaffolds for tissue engineering: Air–liquid foaming
, Article Journal of Biomedical Materials Research - Part A ; Volume 108, Issue 6 , 2020 , Pages 1390-1407 ; Madaah Hosseini, H. R ; Samadikuchaksaraei, A ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
Poly (lactate-co-glycolate) (PLGA) is a typical biocompatible and biodegradable synthetic polymer. The addition of TiO2 nanoparticles has shown to improve compressive modulus of PLGA scaffolds and reduced fast degradation. A novel method has been applied to fabricate PLGA/TiO2 scaffolds without using any inorganic solvent, with aim of improving the biocompatibility, macroscale morphology, and well inter-connected pores efficacy: Air–Liquid Foaming. Field Emission Scanning Electron Microscopy (FESEM) revealed an increase in interconnected porosity of up to 98%. As well the compressive testing showed enhancement in modulus. Bioactivity and in vitro degradation were studied with immersion of...
Recent advancements, trends, fundamental challenges and opportunities in spray deposited cellulose nanofibril films for packaging applications
, Article Science of the Total Environment ; Volume 836 , 2022 ; 00489697 (ISSN) ; Athar, M ; Dehghani, M ; Garnier, G ; Batchelor, W ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Plastic packaging is causing a serious environmental concern owing to its difficulty in degrading and micro-particulates' emissions. Developing biodegradable films has gained research attention to overcome ecological and health issues associated with plastic based packaging. One alternative substitute for petroleum-based plastic is nanocellulose based films, having distinguishing characteristics such as biodegradability, renewability, and non-toxicity. Nanocellulose is classified into three major types, i.e., cellulose nanofibril, cellulose nanocrystals, and bacterial nanocellulose. However, the scope of this review is limited to cellulose nanofibril (CNF) because this is the only one of...
Fabrication of Porous Gelatin-based Scaffold and Evaluation of Effect of Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Forounchi, Massoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Biocompatible porous polymeric scaffolds provide a suitable 3-D environment for proliferation of stem cells in human body. For instance, growth and proliferation concurrent with differentiation of stem cells in such scaffolds can regenerate the tissues or organs. In this attitude we fabricated a porous Gelatin-based scaffold using both of freeze-drying and freeze-extraction methods.Also, effect fo gamma irradiation on microstructure of scaffolds was investigated. In addition, poly(ethylene glycol) was employed to make the scaffold softer. Moreover, effects of various parameters including freezing temperature, cross-linking agent concentration, gelatin and PEG concentrations and their...
An Investigation into the Microstructure and Mechanical Properties of Biodegradable Magnesium Alloys Composite-carbon Nanotube Produced by the Mechanical Alloying and Powders Pressing Processes
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
Properties of biomaterials, especially in application as planting, can be controlled and optimized by alloying and hardening sedimentation. In recent years, the study on the simultaneous improvement of mechanical properties, toughness and corrosion behavior of magnesium composite by carbon nanotubes (CNTs) is very limited. In this study, the behavior of mechanical properties and corrosion of magnesium alloy composites with different percentages of CNTs have been investigated. The production of magnesium alloy composite by powder metallurgy and aging process have been used as effective methods for improving mechanical properties and increasing the corrosion resistance of magnesium alloys. For...
Synthesis & Characterization of All-Cellulose Nanocomposites Containing Natural Extracts for Smart Packaging Applications
, M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza (Supervisor)
Abstract
In this project, all-cellulose nanocomposites for smart packaging of meat products were synthesized via film casing method. These nanocomposites were aimed to provide visual response to pH change, which occurs due to decay of the meat products. The prepared nanocomposites would be placed inside the packages to be in direct contact with the products and could improve shelf life the products with the help of antibacterial natural extracts incorporated in the samples.Synthesis of the samples started with cellulose nano whiskers synthesis via acid hydrolysis. The prepared nanoparticles were then characterized with XRD, DLS, and Zeta potential analysis. It was shown that a big portion of the...
Synthesis and Characterization of Nano Hydroxyapatite/Acrylated Polyurethane Nanocomposites
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Abdekhodai, Mohammad Jafar (Supervisor)
Abstract
In the present study, the acrylated polyurethane/nanohydroxyapatite (APU/n-HAp) nanocomposites were fabricated for use in bone tissue regeneration. The APU was synthesized based on poly(ε-caprolactone) diol (PCL), aliphatic 1,6- hexamethylene diisocyanate (HDI) and hydroxyethyl methyl acrylate (HEMA). The effect of HAp nanoparticles on the physicochemical properties of APU was evaluated. The APU/n-HAp nanocomposites were characterized using X-ray diffraction (XRD), dynamic mechanical thermal analyses (DMTA), scanning electron microscopy (SEM) and mechanical tests including tensile strength and elongation at break. The increase in physical properties achieved by incorporation of n-HAp...
Investigation of Highly Concentrated Phenolic Wastewater Treatment in a Membrane Biological Reactor (MBR), and Evaluation of Furfural upon Phenol Biodegradation by an Acclimated Activated Sludge
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mehdi (Supervisor)
Abstract
Phenolic compounds are hazardous pollutants that are released into environment through wastewater discharges from variety of industries. Although good biodegradability has been reported at low concentrations, but at higher concentrations phenols are known to be antibacterial. In this study the Membrane Biological Reactor (MBR) with submerged hallow fiber membrane was operated at 25±2 ºC and pH=7.5±0.5 to treat a synthetic wastewater containing high phenol concentration (up to 5.9 g/l). Removal efficiency of phenol and COD were evaluated at four various “Hydraulic Retention Times” (HRT) of 24, 12, 8 and 4 hours. To test the tolerance of the bioreactor to phenol concentration various loading...
Molecular Dynamics Simulation of Ionic Liquids and Investigation of their Interactions with Nanoclusteres in Different Molecular Solvents using Quantum Chemistry Calculations
, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
Thermodynamic, structural and transport properties of ester-functionalized ionic liquids (ILs), also kwon as biodegradable ILs, were extensively investigated using molecular dynamic simulation. Thermodynamics features of this class of ILs were computed from 1.5 ns simulations. Nanoscale organization of these ILs was evaluated by computing several structural properties. The formations of micelle-like nanostructures were disclosed from the achieved results of structural properties. The obtained results were also confirmed by calculating transport traits. These results suggest that the incorporation of an ester group into the alkyl side chain of the cation promotes the cation–anion interionic...
Biodegradability Studies of Atrazine in Bioreactor Receiving Low-Level COD Wastewater
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mehdi (Supervisor)
Abstract
Atrazine is widely used in the agriculture as an herbicide. Due to its high mobility, Atrazine leaks into the groundwater, surface waters, and drinking water wells. Many physical and chemical methods have been suggested for removing Atrazine from aquatic environments. However, these methods are very costly, have many performance problems, produce a lot of toxic intermediates which are very harmful and dangerous, and cannot completely mineralize Atrazine. In this study, biodegradation of Atrazine by microbial consortium was evaluated in the aquatic environment. In order to assess the Atrazine removal from the aquatic environment, Fixed-Bed biofilm reactor and Moving Bed Biofilm Reactor were...
Manufacture & Design of a Programmable Micro Syringe for Injecting of Biodegradable Photo Polymers
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor) ; Toyserkani, Ehsan (Co-Advisor)
Abstract
The micro-scale channel creation in Osteochondral scaffolds is a prominent issue in tissue engineering. In this project we tried to identify the relevant parameters to obtain the method for injecting a biodegradable photo polymer to achieve a micro channel by predictable size.Due to inadequate accuracy in measuring the properties of the non –Newtonian working fluid, it was decided to use the Newtonian fluid equations in this study. The relevant equations for injecting the liquid under constant pressure were extracted. The modeling and design of micro syringe system was then completed. Using the made set up experiment to measure the fluid viscosity were performed.The next step was the...
Monitoring of Biodegradation of Oxalate in Microfluidic Bioelectrochemical Systems
, M.Sc. Thesis Sharif University of Technology ; Bastani, Daryoush (Supervisor) ; Yaghmaei, Soheila (Supervisor) ; Mardanpour, Mohammad Mehdi (Co-Supervisor)
Abstract
In present study, bioelectrochemical degradation of oxalate as a substance which its concentration in kidney leads to urolithiasis in a microfluidic microbial fuel cell (MFC) was investigated. In addition, to define a novel application for the microfluidic MFC, measurement and monitoring of oxalate concentration were studied. This application can introduce the system as an implantable medical device for medical usage of urolithiasis and hyperoxaluria diseases. In this work, by designing and fabrication of two MFCs including a large-scale and microfluidic one, and measuring the outlet concentration of oxalate in the large-scale system, the outlet concentration of oxalate at microfluidic MFC...
Immobilization of Laccase Using Metal-Organic Framework and its Application in Micropollutant Removal
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheila (Supervisor) ; Ghobadinejad, Zahra (Supervisor)
Abstract
Nowadays, micropollutants present in aquatic environments posses a significant threat to the well-being and health of human beings. Various physicochemical and advanced approaches have been proposed to confront these hazards. In recent years, biological treatment methods have gained great interest for their green approach. One of these biological treatment options is the treatment of polluted waters by enzymes. Enzymatic treatment of micropollutants can be achieved by oxidoreductase enzymes. One of the most important and widely used oxidoreductase enzymes employed for water treatment is Laccase. However, enzyme immobilization is employed to counter the drawbacks of using enzymes, such as...
Design of Scaffolds with Multi-scale Engineered Microchannels
, M.Sc. Thesis Sharif University of Technology ; Saadatmand, Maryam (Supervisor)
Abstract
Building complex and functional tissues and organs is very challenging. One of the challenges is building an efficient network of blood vessels that can be used to facilitate the transport of nutrients and oxygen to the host. In addition to using channels for oxygen supply, another solution is to use oxygen-carrying materials. In this study, in addition to designing and simulating scaffolds with multi-scale microchannels, calcium peroxide was used to release oxygen and eliminate hypoxia in the scaffold. Here alginate is used as the main material for scaffolding. In an attempt to build a scaffold using a bio-printer, pluronic acid was also used as a sacrificial material to create canals....
Investigating the Effects of Heat Treatment and Y Addition on the Microstructure, Mechanical Properties and Corrosion Behavior of Bio-Degradable Mg–Si Alloys
, M.Sc. Thesis Sharif University of Technology ; Alizadeh, Reza (Supervisor)
Abstract
In Mg–Si alloys, both primary and eutectic Mg2Si particles normally appear with sharp edges, which can lead to weak mechanical properties as the result of stress concentration at the sharp corners of these brittle particles. On the other hand, the morphology, size and distribution of Mg2Si particles affect corrosion behavior of Mg–Si alloys. Thus, it would be of great importance to modify the morphology of these particles. In this study, microstructure modification mechanisms after 0.5 wt% Y addition and heat treatment (HT) at 420 ◦C for 24 h are comprehensively studied in hypo-eutectic Mg–1Si and hyper-eutectic Mg–2Si alloys. Microstructural observations were performed using optical and...
Improving Mechanical and Biological Behavior of Mg-2ag Alloy: Effects of Y Addition, Heat Treatment and Coating
, M.Sc. Thesis Sharif University of Technology ; Alizadeh, Reza (Supervisor)
Abstract
Biodegradable Mg-Ag alloys are promising implants for bone tissue regeneration due to their unique ability to reduce inflammation and infection after implantation with the presence of silver. However, their biological performance, including biodegradability, needs further improvement. In this regard, the effects of adding yttrium element, solution heat treatment and coating on the microstructure, biodegradability behavior, mechanical properties and biological characteristics of a cast Mg-2Ag alloy were studied. Addition of 1 wt% of yttrium caused grain refinement in the microstructure and solid solution heat treatment led to a significant decrease in the volume fraction of secondary phases....
Investigation into the Effect of Adding Sr on Microstructure, Mechanical Properties and Biodegradability Behavior of Biodegradable Mg-Zn-Sr Alloys
, M.Sc. Thesis Sharif University of Technology ; Alizadeh, Reza (Supervisor)
Abstract
Biodegradable implants are new generation of implants that require no secondary surgery for their removal. Mg exhibits a great potential to be used as the biodegradable implant. However, mechanical properties and biocorrosion behavior of Mg are not suitable for being used as biodegradable implants. In this study, effects of Sr additions, heat treatments (T4 and T6), and multi-directional forging on the microstructural evolution, mechanical properties and biocorrosion behavior of Mg-4Zn-xSr alloys, and also the effect of hydrothermal coating on the biocorrosion behavior of Mg-4Zn-0.3Sr alloy were investigated. Potentiodynamic polarization and hydrogen evolution methods were used to...
Investigating Microstructure, Mechanical Properties and Corrosion Resistance of New Biodegradable Mg-2Zn-xAg-yCu (x=0-0.6,y=0-0.1) Alloys
, M.Sc. Thesis Sharif University of Technology ; Alizadeh, Reza (Supervisor) ; Sadrnezhaad, Khatiboleslam (Co-Supervisor)
Abstract
Magnesium has recently been considered as a biocompatible metal with mechanical properties close to bone for use in biological applications. On the other hand, the degradation properties of this metal in the physiological environment have made this metal superior to permanent biomaterials such as stainless steel, titanium alloys. The most important challenge of using this alkaline earth metal in the body environment is its rapid corrosion, which causes problems such as alkaline toxicity and loss of supporting role before complete tissue repair. In this study, Mg-Zn-Ag-Cu alloys were manufactured to improve mechanical strength, corrosion resistance and antibacterial properties. Finally, after...