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Nemati, N.,Emamy, M.,Penkov, O.V.,Kim, J.,Kim, D.E. Elsevier Ltd 2016 Materials & Design Vol.90 No.-
<P>The mechanical and tribological properties of extruded aluminum matrix composites reinforced with various weight percentages (1, 3, 5, 7, 10 wt.%) of Al13Fe4 complex metallic alloys (CMAs) were investigated. The nano-composites were produced using conventional powder metallurgy and a hot extrusion process. The tribological behavior of the composites was investigated under normal loads in the range of 20-80 N using a reciprocating high-temperature tribo-tester over a temperature range of 25-350 degrees C. At an optimized reinforcing agent concentration of 5 wt.%, the composite showed a significant enhancement in Young's modulus (similar to 108 MPa) and hardness (similar to 1.85 GPa). The lowest coefficient of friction of 0.1 was attained at a temperature of 250 degrees C with a reinforcing agent concentration of 5 wt.%. Also, the wear rate was reduced by a factor of similar to 25 compared to the unreinforced aluminum specimen. The significant improvement in the tribological properties of the nanocomposite was attributed to the enhanced mechanical properties due to severe plastic deformation incurred during the extrusion process and incorporation of well distributed CMA nanoparticles in the matrix which provided oobstacles for dislocation motion. Detailed microstructural analyses revealed that incorporation of the second phase to the Al matrix led to microstructure refinement and increased the hardness up to similar to 2 GPa. Furthermore, the nanoparticles aided in the formation of hard and temperature-resistant tribo-layers which reduced the wear rate of the composite (Al-5 wt.% Al13Fe4) down to 1.5 x 10(-4) at 250 degrees C. (C) 2015 Elsevier Ltd. All rights reserved.</P>
Nemati, Narguess,Bozorg, Mansoor,Penkov, Oleksiy V.,Shin, Dong-Gap,Sadighzadeh, Asghar,Kim, Dae-Eun American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.35
<P>A novel functional multilayer coating with periodically stacked nanolayers of amorphous carbon (a:C)/tungsten carbide (WC) and an adhesion layer of chromium (Cr) was deposited on 304 stainless steel using a dual magnetron sputtering technique. Through process optimization, highly densified coatings with high elasticity and shear modulus, excellent wear resistance, and minimal susceptibility to corrosive and caustic media could be acquired. The structural and mechanical properties of the optimized coatings were studied in detail using a variety of analytical techniques. Furthermore, finite element method simulations indicated that the stress generated due to contact against a steel ball was distributed well within the coating, which allowed the stresses to be lower than the yield threshold of the coating. Thus, an ultralow wear rate of similar to 10(-12)mm(3)/N mm could be achieved in dry sliding conditions under relatively high Hertzian contact pressures of similar to 0.4-0.9 GPa. The amorphous and pinhole-free structure of the individual layers, sufficient number of pairs, and the relatively dense stacked layers resulted in significant polarization resistance (Z '' = 5.5 x 10(6) Omega cm(2)) and increased the corrosion resistance of the coating by 10-fold compared to that of recently reported corrosion-resistant coatings.</P>
Nemati, S.,Ordokhani, Y. The Korean Society for Computational and Applied M 2013 Journal of applied mathematics & informatics Vol.31 No.5
At present, research on providing new methods to solve nonlinear integral equations for minimizing the error in the numerical calculations is in progress. In this paper, necessary conditions for existence and uniqueness of solution for nonlinear 2D Fredholm integral equations are given. Then, two different numerical solutions are presented for this kind of equations using 2D shifted Legendre polynomials. Moreover, some results concerning the error analysis of the best approximation are obtained. Finally, illustrative examples are included to demonstrate the validity and applicability of the new techniques.
Highly efficient removal of toxic ions by the activated carbon derived from Citrus limon tree leaves
Fahime Nemati,Dariush Jafari,Hossein Esmaeili 한국탄소학회 2021 Carbon Letters Vol.31 No.3
The purpose of this study was to remove lead and arsenic ions from aqueous solutions using the activated carbon prepared from Citrus limon tree leaves. Characteristics of the prepared adsorbent were studied thoroughly using BET, SEM, EDS and mapping, XRD, and RAMAN analyses. The results of experiments showed that the highest adsorption efficiencies were 97.67% and 95.89% for Pb (II) and As (III), respectively. Additionally, the adsorbent was successfully regenerated four times and therefore it was able to perform the adsorption and desorption processes well. Moreover, the results of adsorption kinetics showed that the pseudo second-order kinetic model was more effective for the description of adsorption mechanism of both metals. Furthermore, the equilibrium studies indicated that Langmuir and Freundlich isotherm models were desirable for lead and arsenic ions, respectively.
S. Nemati,Y. Ordokhani 한국전산응용수학회 2013 Journal of applied mathematics & informatics Vol.31 No.5
At present, research on providing new methods to solve nonlinear integral equations for minimizing the error in the numerical calculations is in progress. In this paper, necessary conditions for existence and uniqueness of solution for nonlinear 2D Fredholm integral equations are given. Then, two different numerical solutions are presented for this kind of equations using 2D shifted Legendre polynomials. Moreover, some results concerning the error analysis of the best approximation are obtained. Finally, illustrative examples are included to demonstrate the validity and applicability of the new techniques.
Mehdi Nemati Chari,Mohammad Shekarchi,Pouria Ghods,Masoud Moradian 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.3
In this paper, a simple practical method is introduced in which a simple weight measurement of concrete and finite element numerical analysis are used to determine the moisture transfer coefficient of concrete with a satisfactory accuracy. Six concrete mixtures with different water-to-cementitious material (w/cm) ratios and two pozzolanic materials including silica fume and zeolite were examined to validate the proposed method. The comparison between the distribution of the moisture content obtained from the model and the one from the experimental data during both the wetting and drying process properly validated the performance of the method.With the proposed method, it was also shown that the concrete moisture transfer coefficient considerably depends on the pore water saturation degree. The use of pozzolanic materials and also lowering w/cm ratio increased the moisture transfer coefficient during the initial sorption, and then, it significantly decreased with an increase in the water saturation degree.
Mahrokh Nemati,Seyed Rasoul Shahosseini,Peiman Ariaii 한국식품과학회 2024 Food Science and Biotechnology Vol.33 No.8
Marine products have gained popularity due to their valuable components, especially protein, despite generating significant waste. Protein hydrolysates are widely recognized as the most effective method for transforming these low-value raw materials into high-value products. Fish protein hydrolysate (FPH), sourced from various aquatic wastes such as bones, scales, skin, and others, is rich in protein for value-added products. However, the hydrophobic peptides have limitations like an unpleasant taste and high solubility. Microencapsulation techniques provide a scientific approach to address these limitations and safeguard bioactive peptides. This review examines current research on FPH production methods and their antioxidant and antibacterial activities. Enzymatic hydrolysis using commercial enzymes is identified as the optimal method, and the antioxidant and antibacterial properties of FPH are substantiated. Microencapsulation using nanoliposomes effectively extends the inhibitory activity and enhances antioxidant and antibacterial capacities. Nevertheless, more research is needed to mitigate the bitter taste associated with FPH and enhance sensory attributes.
Compressive quasistatic and dynamic behavior of SiC/ZrO2 aluminum-based nanocomposite
Jamshid Nemati,Meysam Toosian,Seyed Shahin Banisdar,Seyed Mahdi Ahmadpour 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8
This research investigated the mechanical properties of aluminum-based nanocomposite. The spark plasma sintering method was adopted to fabricate the samples. The nanoparticles and the base metal powder were mechanically mixed in four volumetric ratios under an argon-gas-neutral atmosphere using a planetary ball milling machine. The dynamic and static compressive behaviors of the samples were studied under three different loading rates, and the microhardness of the specimens was measured. Results revealed significant improvements in microhardness, quasistatic, and the dynamic compressive strength, which can be attributed to several mechanisms, including the load transfer effect, Hall-Patch strengthening, Orowan strengthening, coefficient of thermal expansion, and elastic modulus mismatch effects. The most effective mixture was found to be 92 vol% of Al, 4 vol% of SiC, and 4 vol% of ZrO 2 . This combination of raw materials led to ultimate strengths of 204.517, 396.825, and 572.624 MPa at strain rates of 0.33, 13.33, and 2000 s -1 , respectively.
Mahsa Nemati,Sayed Mohsen Hosseini,Meisam Shabanian 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.6
Highly selective cation exchange membranes were prepared by coating a thin 2-acrylamido-2-methylpropanesulfonic acid based hydrogel layer and super activated carbon nanoparticles-co-hydrogel layer on polyvinyl chloride based cation exchange membranes. FTIR analysis proved hydrogel formation on membrane surface successfully. Scanning electron microscopy images and swelling ratio measurement were used to study the effect of super activated carbon nanoparticles on properties of formed hydrogel. The surface morphology, surface hydrophilicity and roughness analysis were also used in membrane characterization. Membrane water content was increased by formation of modified layer on the membranes surface. Modified membranes showed a remarkable improvement in potential, permselectivity and transport number compared to pristine type. Membrane ionic flux and permeability were improved initially by using modifier layer on membrane surface, and then showed decreasing trend at high nanoparticles loading ratios in hydrogel layer. Modified membranes showed lower electrical resistance compared to unmodified membrane.