Search for: scanning-electron-microscopy-image
Total 34 records
Article Analytical Methods ; Vol. 6, issue. 15 , 2014 , Pages 5838-5846 ; ISSN: 17599660 ; Roostaie, A ; Daliri, R ; Sharif University of Technology
A magnetic polyurethane (PU) nanocomposite was synthesized by an electrospinning technique and applied for isolation and preconcentration of fluoxetine from aquatic and biological samples. The nanocomposite was electrospun using a PU polymer solution containing the dispersed magnetic nanoparticles. The magnetic properties of iron nanoparticles, along with the use of an electrospinning technique, led to the formation of a suitable sorbent toward isolation of fluoxetine. The magnetic PU nanofibers could be subsequently removed from the sample solution by applying a permanent magnet. The scanning electron microscopy (SEM) image of the magnetic PU nanofibers confirms that their diameters are in...
Article Polymer Composites ; Vol. 35, issue. 1 , January , 2014 , pp. 37-44 ; ISSN: 02728397 ; Ahmad Ramazani, S. A ; Jafariesfad, N ; Sharif University of Technology
We present the preparation of polypropylene (PP)/fumed silica (FS) nanocomposites via in situ polymerization in this article. The approach includes preparation and utilization of a bisupported Ziegler-Natta catalytic system in which magnesium ethoxide and FS are used as conjugate supports of the catalyst. Catalyst preparation and polymerization processes are carried out in the slurry phase and under argon atmosphere. Scanning electron microscopy images show a good dispersion of the FS throughout the PP matrix. Results from differential scanning calorimetry reveal that the crystallization temperature of prepared nanocomposites increases by increasing FS loading. Also, crystal content of...
Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 1 , 2014 , pp. 361-370 ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
In this study, we attempt to characterize the microstructural evolution during friction stir butt welding of Al-Cu-laminated composites and its effect on the fracture behavior of the joint. Emphasis is on the material flow and particle distribution in the stir zone. For this purpose, optical microscopy and scanning electron microscopy (SEM) images, energy-dispersive spectroscopy EDS and XRD analyses, hardness measurements, and tensile tests are carried out on the joints. It is shown that intermetallic compounds exist in lamellas of banding structure formed in the advancing side of the welds. In samples welded from the Cu side, the banding structure in the advancing side and the hook...
Article ECS Transactions, 1 May 2011 through 6 May 2011 ; Volume 35, Issue 35 , May , 2011 , Pages 63-69 ; 19385862 (ISSN) ; 9781607682950 (ISBN) ; Mahshid, S ; Ghahremaninezhad, A ; Dolati, A ; Ghorbani, M ; Luo, S ; Yang, L ; Cai, Q ; Sharif University of Technology
The catalytic activity of Pt/Ni/TiO 2 nanotubes electrode toward glucose has been studied. Fabrication of Pt/Ni nanostructures was done in a single-bath solution through electrochemical pulse method by changing the deposition potential between -0.3 and -4 V vs. SCE, respectively. The resulting modified electrode represented high conductivity due to the effective presence of metallic components and uniform surface area caused by dispersion of Pt and Ni nanostructures. The scanning electron microscopy images also confirmed that a large amount of metals colonies were well-dispersed at the edge of the TiO 2 nanotubes. In addition, the Pt/Ni TiO 2 nanotubes modified electrode exhibited an...
Improvements in permeation and fouling resistance of PVC ultrafiltration membranes via addition of Tetronic-1107 and Triton X-100 as two non-ionic and hydrophilic surfactants, Article Water Science and Technology ; Volume 74, Issue 6 , 2016 , Pages 1469-1483 ; 02731223 (ISSN) ; Seyedi, S. M ; Rabiei, H ; Alvandifar, N ; Sharif University of Technology
Two non-ionic and hydrophilic surfactant additives, Tetronic-1107 and Triton X-100, were added to poly(vinyl chloride)/NMP polymeric solution to prepare ultrafiltration membranes via immersion precipitation. Surfactants at three different weight percentages up to 6 wt% were added, and the fabricated membranes were characterized and their performance for water treatment in the presence of bovine serum albumin (BSA) as a foulant was assessed. The scanning electron microscopy images indicated remarkable changes in morphology due to higher thermodynamic instability after surfactant addition. The membranes are more porous with more macro-voids in the sub-layer. Plus, the membranes become more...
Molecular machinery responsible for graphene oxide's distinct inhibitory effects toward pseudomonas aeruginosa and staphylococcus aureus pathogens, Article ACS Applied Bio Materials ; Volume 4, Issue 1 , 2021 , Pages 660-668 ; 25766422 (ISSN) ; Najafi, F ; Maghsoumi, A ; Huma, K ; Azimi, L ; Karimi, A ; Ejtehadi, M. R ; Gumbart, J. C ; Naseri, N ; Sharif University of Technology
American Chemical Society 2021
Graphene oxide flakes are considered as potential inhibitors for different pathogenic bacteria. However, the efficacy of inhibition changes for different types and strains of bacteria. In this work, we examine Pseudomonas aeruginosa and Staphylococcus aureus, two common hospital-acquired infections, which react quite differently to graphene oxide flakes. The minimum inhibitory tests yield two distinct outcomes: stopped proliferation for S. aureus versus almost no effect for P. aeruginosa. Integrating our experimental evidence with molecular dynamics simulations, we elucidate the molecular machinery involved, explaining the behavior we see in scanning electron microscopy images. According to...
Comparative study of the grown ZnO nanostructures on quartz and alumina substrates by vapor phase transport method without catalyst: Synthesis and acetone sensing properties, Article Sensors and Actuators, A: Physical ; Vol. 212 , 2014 , Pages 80-86 ; ISSN: 09244247 ; Mortezaali, A ; Iraji Zad, A ; Sharif University of Technology
Uniform layers of ZnO nanostructures were formed on quartz and alumina substrates through a simple vapor phase transport (VPT) method without any catalyst or buffer layer by making proper growth conditions. The effect of substrate on morphology, crystalline structure and photoluminescence spectra has been investigated. Scanning electron microscopy images revealed that morphlogical grwoth depends on used substrate, aligned rods with flower-like bundels and entangled rods are vertically aligned rods on the quartz and alumina substrates, respectively. X-ray diffraction studies showed that grown films on the quartz substrates possess stronger c-axis orientation compared to those on the alumina...
Evaluation of ascorbic acid-loaded calcium phosphate bone cements: Physical properties and in vitro release behavior, Article Ceramics International ; Vol. 40, issue. 3 , April , 2014 , pp. 3961-3968 ; ISSN: 02728842 ; Hesaraki, S ; Nemati, A ; Sharif University of Technology
In this study, different concentrations of ascorbic acid (50, 100 and 200 μg/mL) were added to the liquid phase of a calcium phosphate cement (CPC). The cements were immersed in simulated body fluid (SBF) for different intervals and physical, physicochemical and mechanical properties of them were evaluated. The release of added ascorbic acid from CPCs into the SBF solution was also studied. From the results, both setting time and injectability of CPC decreased by adding ascorbic acid, however the compressive strength was sharply increased before soaking in SBF solution. But, the compressive strength values of all cements (with or without ascorbic acid) soaked in SBF solution for more than 7...
Effects of preheating temperature and cooling rate on two-step residual stress in thermal barrier coatings considering real roughness and porosity effect, Article Ceramics International ; Vol. 40, Issue. 10 , December , 2014 , pp. 15925-15940 ; ISSN: 02728842 ; Farrahi, G. H ; Azadi, M ; Ghodrati, M ; Sharif University of Technology
In this research, a finite element model was developed in order to simulate the two-step residual stress distribution of a thermal barrier coating system, considered to be used in diesel engine cylinder head, with a real roughness and real porosity. Two steps including the bond coat and the top coat deposition processes were taken into account. The real geometry of coating layers, including the roughness and the porosity, was also considered based on a scanning electron microscopy image. Then, effects of the convective heat transfer coefficient and initial substrate and substrate/bond coat preheating temperatures on the residual stress were studied. Obtained results illustrate that the...
A highly thermal-resistant electrospun-based polyetherimide nanofibers coating for solid-phase microextraction Microextraction Techniques, Article Analytical and Bioanalytical Chemistry ; Vol. 406, issue. 8 , March , 2014 , p. 2141-2149 ; Akbarinejad, A ; Aghakhani, A ; Sharif University of Technology
A high-temperature-resisant solid-phase microextraction (SPME) fiber was prepared based on polyetherimide (PEI) by the electrospinning method. The PEI polymeric solution was converted to nanofibers using high voltages and directly coated on a stainless steel SPME needle. The scanning electron microscopy images of PEI coating showed fibers with diameter range of 500-650 nm with a homogeneous and smooth surface morphology. The SPME nanofibers coating was optimized for PEI percentage, electrospinning voltage, and time. The extraction efficiency of the coating was investigated for headspace SPME of some environmentally important polycyclic aromatic hydrocarbons from aqueous samples followed by...
A well-dispersed Pt/Ni/TiO 2 nanotubes modified electrode as an amperometric non-enzymatic glucose biosensor, Article Sensor Letters ; Volume 9, Issue 5 , October , 2011 , Pages 1598-1605 ; 1546198X (ISSN) ; Luo, S ; Yang, L ; Mahshid, S ; Dolati, A ; Ghorbani, M ; Cai, Q ; Sharif University of Technology
In this study a novel Pt/Ni nanostructure consisting of nano-bushes and nanocubes was fabricated onto TiO 2 nanotubes. The scanning electron microscopy images showed that a large amount of well-dispersed nano-architectures had uniformly covered all over the surface which made an electrode with high surface area. It was obviously seen that the nanocube structures mainly consists of Ni had been grown on top of each other while the Pt colonies represented bush-like structures. As a non-enzymatic glucose biosensor, the Pt/Ni TiO 2 nanotubes modified electrode exhibited an excellent performance. The proposed biosensor had two linear ranges for detection of glucose from 0 to 0.12 mM (correlation...
Self-organized titanium oxide nanotubes prepared in phosphate electrolytes: Effect of voltage and fluorine concentration, Article ECS Transactions, 25 April 2010 through 30 April 2010 ; Volume 28, Issue 7 , April , 2010 , Pages 67-74 ; 19385862 (ISSN) ; 9781607681830 (ISBN) ; Dolati, A ; Goodarzi, M ; Askari, M ; Ghahramaninezhad, A ; ECS All Divisions ; Sharif University of Technology
TiO2 a nanotube array was prepared using an anodization process. The process proceeded in a two-electrode cell containing of platinum sheet as the cathode electrode. Two phosphate-base electrolyte solutions containing different amounts of HF and NH4F were prepared. Different concentration of fluorine ions were examined in respected electrolytes. Current transient techniques were used to produce the TiO2 nanotubes at constant voltage of 18-25V. It was revealed that anodization at 18-22V, in so-called electrolytes would end up to nano-tubular structure. However the tubular structure prepared at 20V and from phosphate electrolyte containing of 0.5 wt% NH4F as well as 0.5 wt% HF, was recognized...
Constructing BiVO4/Graphene/TiO2 nanocomposite photoanode for photoelectrochemical conversion applications, Article Journal of Electroanalytical Chemistry ; Volume 763 , 2016 , Pages 1-9 ; 15726657 (ISSN) ; Faraji, M ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier B.V 2016
BiVO4/Graphene/TiO2 as a novel nanocomposite photoanode was designed, synthesized and characterized for photoelectrochemical application. BiVO4/Graphene nanocomposite was initially synthesized by photocatalytic process and then, BiVO4/Graphene/TiO2 nanocomposite thin film was prepared by deposition of the BiVO4/Graphene solution onto the surface of sol-gel derived TiO2 thin film. Morphology, crystal structure, surface chemical composition and optical properties of the synthesized BiVO4/Graphene/TiO2 nanocomposite thin film were characterized and compared with the BiVO4/Graphene and pure TiO2 samples. Observations of scanning electron microscopy (SEM) images revealed that the surface of the...
Structural and corrosion characterization of hydroxyapatite/zirconium nitride-coated AZ91 magnesium alloy by ion beam sputtering, Article Applied Surface Science ; Volume 401 , 2017 , Pages 172-180 ; 01694332 (ISSN) ; Afshar, A ; Mojtahedzadeh Larijani, M ; Yousefpour, M ; Sharif University of Technology
The adhesion of hydroxyapatite (HA) as a coating for the AZ91 magnesium alloy substrate can be improved by using the sputtering method and an intermediate layer, such as ZrN. In this study, HA coatings were applied on ZrN intermediate layers at a temperature of 300 °C for 180, 240, 300, 360, and 420 min by ion beam sputtering. A profilometer device was used to study the HA coating thickness, which changed from 2 μm for the 180-min deposition to 4.7 μm for 420-min deposition. The grazing incidence X-ray diffraction analysis method and the Williamson–Hall analysis were used for structural investigation. As the deposition time increased, the crystalline size increased from 50 nm to 690 nm....
Green high strength concrete containing recycled waste ceramic aggregates and waste carpet fibers: Mechanical, durability, and microstructural properties, Article Journal of Building Engineering ; Volume 26 , 2019 ; 23527102 (ISSN) ; Ameri, F ; Bahrami, N ; Shoaei, P ; Musaeei, H. R ; Nurian, F ; Sharif University of Technology
Elsevier Ltd 2019
This paper investigated the combined utilization of recycled waste ceramic aggregate (RWCA) and waste carpet fibers (WCFs) in high strength concrete (HSC). Concrete mixes containing different percentages of RWCA including 20%, 40%, 60% (by weight) as partial replacement of natural coarse aggregate (NCA) were prepared. To enhance the tensile and flexural strength of concrete, 1.0% (by volume) WCF was added to the mixes. The slump and density of the fresh concrete were evaluated, both of which demonstrated a decreasing trend with incorporation of RWCA and WCF. With regard to the hardened concrete, replacing 40% of NCA with RWCA led to the optimum mechanical properties and increased the...
Microstructure and characteristic properties of gelatin/chitosan scaffold prepared by the freeze-gelation method, Article Materials Research Express ; Volume 6, Issue 11 , 2019 ; 20531591 (ISSN) ; Kamali, A ; Bahrani Fard, M. R ; Sharif University of Technology
Institute of Physics Publishing 2019
Three-dimensional porous scaffolds are essential in tissue engineering applications. One of the most conventional methods to form porosity in scaffolds is freeze-drying, which is not energy efficient and cost effective. Therefore in this work, it was experimentally investigated whether gelatin, with its unique mechanical properties and cell binding applications, could be used as a comprising polymer of scaffolds with porous structure made by the freeze-gelation method. Chitosan, gelatin and chitosan/gelatin scaffolds were fabricated by the freeze-gelation method and their behaviors, determined by analysis of scanning electron microscopy images, Fourier transform infrared spectroscopy,...
Poly(lactic acid)/coplasticized thermoplastic starch blend: Effect of plasticizer migration on rheological and mechanical properties, Article Polymers for Advanced Technologies ; Volume 30, Issue 4 , 2019 , Pages 839-851 ; 10427147 (ISSN) ; Pircheraghi, G ; Bagheri, R ; Altstädt, V ; Sharif University of Technology
John Wiley and Sons Ltd 2019
Polylactic acid (PLA) and thermoplastic starch (TPS) are known as bio-based and biodegradable thermoplastic polymers that can be used in different applications owing to their inherent physical and mechanical properties. In order to reduce the higher costs of PLA and tuning its physical and mechanical properties suitable for short life packaging applications, blending of PLA with the TPS, more economical biodegradable polymer, has been considered in academic and industrial researches. However, melt blending of PLA with TPS without compatibilization process caused some drawbacks such as coarsening morphology and declining mechanical properties and ductility because of thermodynamic...
Sustained release of CIP from TiO2-PVDF/starch nanocomposite mats with potential application in wound dressing, Article Journal of Applied Polymer Science ; Volume 137, Issue 30 , 2020 ; Haddadi, S. A ; Amini, M ; Hasany, M ; Ramazani SaadatAbadi, A ; Sharif University of Technology
John Wiley and Sons Inc 2020
Electrospinning is an economical and alluring method to fabricate wound dressing mats from a variety of natural and synthetic materials. In this study, polyvinylidene fluoride (PVDF) and starch composite mats containing ciprofloxacin (CIP) loaded on titanium dioxide nanoparticles (TiO2) were prepared. Fourier Transform Infrared spectra of CIP, synthesized TiO2 NPs, TiO2/CIP, and PVDF/starch composite mats are analyzed. Scanning electron microscopy images revealed that the fiber diameter of PVDF nanofibers thickens by increasing starch, which varies between 180 nm and 550 nm. Strain at break of PVDF, starch, PVDF/starch (2:1 w:w; P2S1), PVDF/starch (1:1 w:w; P1S1), PVDF/starch (1:2 w:w;...
Oxidation behavior and electrical properties of de-siliconized aisi 430 alloy with mn1.5co1.5o4 coating for solid oxide fuel cell interconnect, Article Oxidation of Metals ; Volume 93, Issue 3-4 , 2020 , Pages 401-415 ; Salmani, S ; Faghihi Sani, M. A ; Abdoli, H ; Jalili, N ; Sharif University of Technology
Abstract: The effect of de-siliconization on the oxidation behavior of AISI 430 stainless steel used for solid oxide fuel cell interconnect application was investigated. De-siliconization treatment was conducted via heating steel parts in an H2 environment. The de-siliconized substrates were then coated with a Mn1.5Co1.5O4 spinel coating, using wet spray method. For comparison, a similar coating process was applied on the as-received AISI 430 stainless steel specimens. Oxidation kinetics of coated interconnects were evaluated at 700, 800 and 900 °C in air. Results showed that the de-siliconization surface treatment decreased oxidation rates, with kinetic rates (g2 cm−4 s−1) of 4.39 × 10−14...
Both tough and soft double network hydrogel nanocomposite based on o-carboxymethyl chitosan/poly(vinyl alcohol) and graphene oxide: a promising alternative for tissue engineering, Article Polymer Engineering and Science ; Volume 60, Issue 5 , 2020 , Pages 889-899 ; Mazaheri Tehrani, Z ; Salami, H ; Seidi, F ; Motamedi, A ; Amanzadi, A ; Zayerzadeh, E ; Shabanian, M ; Sharif University of Technology
John Wiley and Sons Inc 2020
A reinforced double network (DN) hydrogel as a candidate for skin scaffold was prepared. It consists of O-carboxymethyl chitosan, polyvinyl alcohol, honey, CaCl2, and graphene oxide. The various concentrations of CaCl2, namely, 30, 45, and 60 wt% were investigated. Besides, the GO content was studied as 3, 5, and 10 wt%. The structure of the DN was characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, energy dispersive X-ray and Brunauer-Emmett-Teller were evaluated. The mechanical properties were studied, too. It showed that the DN with 45 wt% CaCl2 was optimized. Also, swelling mechanism was investigated....