Insights into the Mechanical Properties and Correlation Between Strain Path and Crystallographic Texture of the AA2024 Alloy During Severe Plastic Deformation

Majid Naseri,Mohsen Reihanian,Ahmad Ostovari Moghaddam,Davood Gholami,Mohammad Alvand,Ehsan Borhani,Evgeny Trofimov 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2

This study examined mechanical properties of AA2024 alloy and its correlation between strain path and crystallographictexture. Accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB) were used to severely deformAA2024 alloys. Electron backscatter diffraction (EBSD) studies demonstrated that nano/ultrafine grains were formed by thestrain routes after eight cycles. It was also found that the lamellar boundary spacing and the mean boundary spacing were~ 360 ± 10 nm and 845 ± 10 nm after eight ARB cycles. In contrast to the ARB, the CARB specimen had equiaxed microstructurescharacterized by grains with a size of 150 and 100 nm. The CARB processed specimen exhibited a mean misorientationangle of 41.83° and a fraction of high angle grain boundaries of 78%, these values were 34.57° and 67% for ARB treatedspecimen, respectively. It was observed that the evolved texture is greatly affected by the strain paths. The ARB processedspecimen revealed strong Copper {112} <111>, Dillamor {4 4 11} <11 11 8>, S {123} <634>, and Brass {011} <211>components. In contrast, the CARB processed specimen showed major texture with prominent Copper {112} <111>, Brass{011} <211>, Rotated Cube {001} <110>, S {123} <634>, and Goss {011} <100> components. In the CARB specimen, theGoss/Brass texture ratio was intensified and the mechanical properties were superior (tensile strength: 535 MPa, microhardness:182 HV, elongation: 11.9%) compared with the ARB processed specimen (tensile strength: 455 MPa, microhardness:145 HV, elongation: 9.2%). Further, the change in strain path did not significantly affect the intensity of Goss and Cubecomponents, ruling out any further recrystallization tendency.

Naringin-loaded Poly(ε-caprolactone)/Gelatin Electrospun Mat as a Potential Wound Dressing: In vitro and In vivo Evaluation

Majid Salehi,Ahmad Vaez,Mahdi Naseri-Nosar,Saeed Farzamfar,Arman Ai,Jafar Ai,Shima Tavakol,Mehrdad Khakbiz,Somayeh Ebrahimi-Barough 한국섬유공학회 2018 Fibers and polymers Vol.19 No.1

In the present study, naringin, a flavonoid isolated from the grape and citrus fruit species, was incorporated with poly(ε-caprolactone)/gelatin composite mats in order to develop a potential wound dressing. The composite mats were prepared by electrospinning of poly(ε-caprolactone)/gelatin (1:1 (w/w)) solution incorporated with 1.50 %, 3 % and 6 % (w/w) of naringin. The electrospun mats were evaluated regarding their morphology, contact angle, water-uptake capacity, water vapor transmission rate, tensile properties, drug release, cellular response and in vivo wound healing activity. The study showed that after 2 weeks, the full-thickness excisional wounds of Wistar rats treated with the naringin-loaded dressings achieved a wound closure of higher than 94 % and the dressing containing 6 % (w/w) naringin had almost 100 %wound closure. The sterile gauze, as the control group, showed nearly 86 % of wound closure after this period of time. Our results provided evidence that supports the possible applicability of naringin-loaded wound dressing for successful wound treatment.

Comparative Study of Poly(L-Lactic Acid) Scaffolds Coated with Chitosan Nanoparticles Prepared via Ultrasonication and Ionic Gelation Techniques

Majid Salehi,Mahdi Naseri-Nosar,Mahmoud Azami,Saeedeh Jafari Nodooshan,Javad Arish 한국조직공학과 재생의학회 2016 조직공학과 재생의학 Vol.13 No.5

In this study, an attempt was made to develop bi-functional constructs serving both as scaffolds and potential delivery systems for application in neural tissue engineering. The constructs were prepared in two steps. In the first step, the bulks of poly (L-lactic acid) (PLLA) in 1, 4-dioxane/water (87:13) were fabricated using liquid-liquid thermally induced phase separation technique. In the next step, the prepared bulks were coated with chitosan nanoparticles produced by two different techniques of ultrasonication and ionic gelation by grafting-coating technique. In ultrasonication technique, the chitosan solution (2 mg/mL) in acetic acid/sodium acetate buffer (90:10) was irradiated by an ultrasound generator at 20 kHz and power output of 750 W for 100 s. In ionic gelation technique, the tripolyphosphate in water solution (1 mg/mL) was added to the same chitosan solution. The physicochemical properties of the products were characterized by Scanning Electron Microscopy, Attenuated Total Reflection Fourier Transform-Infrared, liquid displacement technique, contact angle measurement, compressive and tensile tests, as well as zeta potential and particle size analysis using dynamic light scattering. Moreover, the cell proliferation and attachment on the scaffolds were evaluated through human glioblastoma cell line (U-87 MG) and human neuroblastoma cell line [BE (2)-C] culture respectively. The results showed that the samples coated with chitosan nanoparticles prepared by ultrasonication possessed enhanced hydrophilicity, biodegradation and cytocompatibility compared with pure PLLA and PLLA coated with chitosan nanoparticles prepared by ionic gelation. This study suggests successful nanoparticles-scaffold systems which can act simultaneously as potential delivery systems and tissue engineering scaffolds.

Synthesis and characterization of physicochemical properties of hydrophilic imidazolium-based ionic liquids

Maryam Yousefi,Majid Abdouss,Ali Akbar Miran Beigi,Ali Naseri 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.9

A series of ionic liquids based on Octyl and Decyl methylimidazolium with different anions such as chloride, glycinate, dihydrogen phosphate and trihydrogen diphosphate, were synthesized and characterized by 1HNMR and elemental analysis. IL containing trihydrogen diphosphate anion, was synthesized for the first time. Physicochemical properties, including density, viscosity, surface tension, refractive index, and pH, were measured in temperature range 283.15 to 363.15 K and atmospheric pressure. The effects of temperature, alkyl chain, and anion type on physicochemical properties were investigated. The results revealed that the physicochemical properties decreased as a function of temperature. Unlike viscosity, other properties, such as density, surface tension, refractive index and pH values, decreased, while alkyl chain length increased. Understanding ILs properties and determining their unique abilities helps researchers to use them in new applications. These long alkyl chain ILs, are being used as surfactants to reduce Oil/Water interfacial tension in EOR process.

Promotion of excisional wound repair by a menstrual blood-derived stem cell-seeded decellularized human amniotic membrane

Saeed Farzamfar,Majid Salehi,Arian Ehterami,Mahdi Naseri-Nosar,Ahmad Vaez,Amir-Hassan Zarnani,Hamed Sahrapeyma,Mohammad Reza Shokri,Mehdi Aleahmad 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.4

This is the first study demonstrating the efficacy of menstrual blood-derived stem cell (MenSC) transplantation viadecellularized human amniotic membrane (DAM), for the promotion of skin excisional wound repair. The DAM wasseeded with MenSCs at the density of 3 9 104 cells/cm2 and implanted onto a rat’s 1.50 9 1.50 cm2 full-thicknessexcisional wound defect. The results of wound closure and histopathological examinations demonstrated that the MenSCseededDAM could significantly improve the wound healing compared with DAM-treatment. All in all, our data indicatedthat the MenSCs can be a potential source for cell-based therapies to regenerate skin injuries.

Effects of Atorvastatin in Patients with Acute Spinal Cord Injury

Javad Aghazadeh,Parviz Samadi Motlagh,Firooz Salehpour,Ali Meshkini,Majid Fatehi,Farhad Mirzaei,Seyed Ahmad Naseri Alavi 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.6

Study Design: Clinical trial study. Purpose: The aim of this study was to evaluate the effect of atorvastatin on sensory and motor function in patients with acute spinal cord injury. Overview of Literature: The prevalence and incidence of traumatic spinal cord injury are increasing. Statins are well established for use in hypercholesterolemia as well as during anti-inflammatory events. Methods: This clinical trial study included 60 patients with acute spinal cord injury. These were randomly divided into two groups: the case group which received atorvastatin and also underwent surgical therapy and the control group which only underwent surgical therapy. Results: The severity of spinal cord lesions was evaluated based on the Frankel grade at three periods; this showed no significant difference between the two groups. Comparisons of the levels of pain between the groups based on a Visual Analog Scale system showed no significant difference at the three periods. Conclusions: We observed no improvement at the 3- and 6-month follow-up in patients who were administered atorvastatin. However, a comparison of the two groups based on pain severity demonstrated a significant difference, suggesting that atorvastatin had a positive effect on patients with spinal cord injury.