Research Output
Articles
Alkhafaji A.,
Camas D.,
Al-Asadi H.,
Mahdavi, E.,
Motamedi, M.,
Salarian S.,
Jafarian amiri s.m., ,
Ali, M.,
Vahed R.,
Nikzad, M.H. Publication Date: 2025
Materials (19961944)(2)pp. 829-849
Friction stir spot welding (FSSW) technology relies on the generation of frictional heat during the rotation of the welding tool in contact with the workpiece as well as the stirring effect of the tool pin to produce solid-state spot joints, especially for lightweight materials. Although FSSW offers significant advantages over traditional fusion welding, the oxidation of the interfacial bond line remains one of the most challenging issues, affecting the quality and strength of the joint under both static and cyclic loading conditions. In this experimental study, inert argon gas was employed to surround the joint, aiming to prevent or minimize the formation of the interfacial oxides. Two welding processes were conducted with identical welding process parameters and welding tool geometry: the conventional process and another that employs an inert gas cover. Micrographs of as-welded specimens were analyzed using a computerized optical microscope to characterize the interfacial bond lines and an energy-dispersive spectroscope (EDS) was used to quantify the interfacial oxides. Specimens from both welding conditions were tested under static and cyclic loads to investigate the static and fatigue behaviors, respectively. The fatigue tested specimens were examined under different load levels to investigate the fatigue crack behavior and the modes of failure at low-cycle and high-cycle fatigue conditions. The optical micrographs showed significant improvement in bond line morphologies (33% enlarged fully bonded area) and both static and fatigue strengths (35% reduced partially bonded area) when the inert gas cover was used. The EDS analysis revealed a maximum reduction of the interfacial oxide of 41% in the bond line achieved in the argon-surrounded joints compared to specimens of the conventional welding process. Accordingly, an improvement of 14% in the static strength was reached, along with 60% and 26% in the fatigue strengths at low- and high-cycle fatigue conditions, respectively. © 2025 by the authors.
Nejat Dehkordi A.,
Maddahi M.,
Vafa P.,
Ebrahimi, N.,
Aref A.R.,
Abbasi, M.,
Motamedi, M.,
Mahboubi-rabbani, M.,
Ali, M.,
Kashfi, K.,
Nikzad, M.H.,
Sadeghi-aliabadi, H. Publication Date: 2025
Clinical and Translational Oncology (1699048X)(5)pp. 1887-1920
Head and neck cancers, including cancers of the mouth, throat, voice box, salivary glands, and nose, are a significant global health issue. Radiotherapy and surgery are commonly used treatments. However, due to treatment resistance and disease recurrence, new approaches such as immunotherapy are being explored. Immune checkpoint inhibitors (ICIs) have shown promise, but patient responses vary, necessitating predictive markers to guide appropriate treatment selection. This study investigates the potential of non-invasive biomarkers found in saliva, oral rinses, and tumor-derived exosomes to predict ICI response in head and neck cancer patients. The tumor microenvironment significantly impacts immunotherapy efficacy. Oral biomarkers can provide valuable information on composition, such as immune cell presence and checkpoint expression. Elevated tumor mutation load is also associated with heightened immunogenicity and ICI responsiveness. Furthermore, the oral microbiota may influence treatment outcomes. Current research aims to identify predictive salivary biomarkers. Initial studies indicate that tumor-derived exosomes and miRNAs present in saliva could identify immunosuppressive pathways and predict ICI response. While tissue-based markers like PD-L1 have limitations, combining multiple oral fluid biomarkers could create a robust panel to guide treatment decisions and advance personalized immunotherapy for head and neck cancer patients. © The Author(s), under exclusive licence to Federación de Sociedades Españolas de Oncología (FESEO) 2024.
Publication Date: 2024
Journal of Materials Engineering and Performance (10599495)33(6)pp. 2616-2622
CMSX-4 nickel base superalloy is the second-generation alloy of this single crystal, which has improved its mechanical properties due to the lack of grain boundaries. According to the working conditions in using this superalloy, achieving less surface defects and lower surface roughness after the manufacturing process is very important. Therefore, the comparison of the surface of this superalloy after grinding, wire electro discharge machining (WEDM) and electrochemical machining (ECM) has been investigated by scanning electron microscope (SEM) and surface roughness. Surface roughness after WEDM, ECM and grinding are 3.337, 0.549, and 0.458 micro-meter, respectively. ECM and grinding processes are suitable from the point of view of surface roughness. On the other hand, in the SEM images after ECM, the defects caused by this process were not observed (compared to the other two processes). Besides, hardness after WEDM, ECM and grinding are 38.9, 39.7 and 40.1 HRC respectively. To conclude, the ECM process has desirable results and is a suitable alternative process for manufacturing parts with smooth surface and less surface defects. © ASM International 2023.
Publication Date: 2024
Scientia Iranica (23453605)31(20)pp. 1880-1888
Modeling and determining the optimal conditions for the Jet Electrochemical Machining (Jet-ECM) process is critical. In this study, a hybrid approach combining numerical and Design of Experiments (DOE) methods have been applied to model and determine the optimal conditions for Jet-ECM. The voltage (V), inner tool diameter (I), initial machining gap (G), and electrolyte conductivity (C) are considered input variables. Additionally, dimensional accuracy (E) and machining depth (D) are response variables. Twenty-seven numerical simulations have been performed using the Box–Behnken design to implement the Response Surface Methodology (RSM). Consequently, two mathematical models have been obtained for these response variables. The effects of the input variables on the response variables are investigated using statistical techniques such as variance analysis. Furthermore, the desirability function approach has been applied to determine the optimal conditions for dimensional accuracy and depth of machining. The results show that the optimal values for achieving maximum depth of machining while maintaining a dimensional accuracy of 0.05 mm are as follows: electrolyte conductivity of 8 S/m, voltage of 36.9 V, initial machining gap of 200 μm, and inner tool diameter of 0.4 mm. © 2024 Sharif University of Technology.
Publication Date: 2023
Computational Particle Mechanics (21964386)10(1)pp. 143-153
Nowadays, various methods are being formed on new composites and nanocomposite compounds. Investigating the properties of nanocomposites and finding their optimal properties pave the way for a better use of them. In this study, first, mechanical molecular dynamics method is used to investigate mechanical properties of aluminum/carbon nanotubes (Al-CNT) nanocomposite, then, the effect of temperature change, strain rate, and chirality of nanotubes on the elastic modulus and ultimate stress of nanocomposite have been investigated. However, in order to simultaneously investigate these three parameters on the properties of nanocomposite and to find an optimal point for the elastic modulus and ultimate stress, the experimental design method for optimization was used. Derringer method was used to determine optimal parameters for simultaneous optimization of two response variables, namely elastic modulus and ultimate stress. It can be concluded that the optimal conditions occur simultaneously at 50 K, strain rate 0.01, and chirality (5,5), in which the value of the elastic modulus is 156 GPa and the ultimate strain value is 13.7 GPa and simultaneous minimum value of elastic modulus and ultimate stress occur at 650 K, strain rate 0.0205, chirality (3,3), in which the value of elastic module is 94 GPa and the ultimate strain value is 6.44 GPa. © 2022, The Author(s) under exclusive licence to OWZ.
