Investigation of Surface Nanostructuring, Mechanical Performance and Deformation Mechanisms of AISI 316L Stainless Steel Treated by Surface Mechanical Impact Treatment

Milad Rostami,Reza Miresmaeili,Asghar Heydari Astaraee 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4

Nanostructured materials exhibit superior properties with respect to their bulk counterpart. Recently, a new processingmethod for surface nanostructuring of metallic materials called surface mechanical impact treatment (SMIT) was developed. In this study, the surface microstructural features due to the refinement process of AISI 316L stainless steel by means ofSMIT and subsequent mechanical performance were investigated. The effects of SMIT processing parameters, i.e. ball sizeand treatment duration, were studied in terms of microstructural evolutions using X-ray diffraction, transmission electronmicroscopy, optical microscopy, and field emission scanning electron microscopy analyses, and mechanical propertiesthrough hardness and tensile tests. A gradient nanostructured surface layer was successfully formed on the surface of thetreated samples. The mean grain size was measured to be ~ 20 nm in the topmost surface layer and increased with increasingdepth. Microstructural examinations showed that the twins and their intersections (rhombic blocks) formed in the surfacelayers. It was found that the mechanical performance of the treated samples is effectively enhanced. The surface hardnessof the treated samples increased about 3 times while the yield strength of the samples increased with increasing SMIT timeand size of the ball up to 2.5 times. The grain refinement mechanisms, mechanical properties, and fracture behavior weresubsequently analyzed and discussed.

Applying SVM framework for modeling of CO₂ solubility in oil during CO₂ flooding

Rostami, Alireza,Arabloo, Milad,Lee, Moonyong,Bahadori, Alireza Elsevier 2018 Fuel Vol.214 No.-

<P><B>Abstract</B></P> <P>CO<SUB>2</SUB> solubility is one of the most important parameters that affects CO<SUB>2</SUB> flooding, because gas dissolution into crude oil results in oil swelling, viscosity reduction, IFT reduction, oil mobilization, and oil recovery improvement. Therefore, a better understanding of CO<SUB>2</SUB> solubility mechanisms and its influence on physical properties of crude oil are essential to any effective CO<SUB>2</SUB> flooding process. In this study, Least-Square Support Vector Machine (LSSVM) as a newly established soft computing algorithm is applied for developing a new correlative model for CO<SUB>2</SUB> solubility in both dead and live oil systems. CO<SUB>2</SUB> solubility in dead oil is basically affected by the oil saturation pressure (P<SUB>s</SUB>), oil specific gravity (<I>γ</I>), oil molecular weight (MW), and reservoir temperature (T). Moreover, the impact of bubble point pressure is considered in constructing the LSSVM model for the live oil. A number of statistical quality measures are utilized to assess and demonstrate the superior capability of the newly developed LSSVM model in comparison with the previous empirically derived correlations. The average absolute relative deviation (AARD) and coefficient of determination (R<SUP>2</SUP>) of 2.2783% and 0.9933 for the dead oil system, and 1.7432% and 0.9958 for the live oil system, respectively, verify the acceptable accuracy and efficient performance of the proposed LSSVM model over a wide range of dataset used in this study within the range of the used databank. However, the impact of CO<SUB>2</SUB> liquefaction pressure is ignored, the LSSVM model gives the best result. In conclusion, it is worth mentioning that the proposed LSSVM model can serve as an accurate correlative tool for fast and effective estimation of CO<SUB>2</SUB> solubility in both dead and live crude oils.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new soft computing model is established for CO<SUB>2</SUB> solubility prediction in both dead and live oil systems. </LI> <LI> Several statistical parameters are utilized to demonstrate the superiority of the suggested SVM model. </LI> <LI> The performance of the developed model is compared with other literature correlations. </LI> <LI> The proposed model can serve as accurate tool for effective estimation of CO<SUB>2</SUB>-crude oil solubility. </LI> <LI> The impact of all input variables on the target values based on different techniques is determined. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A systematic review and meta-analysis of the prevalence of toxoplasmosis in hemodialysis patients in Iran

Masoud Foroutan,Ali Rostami,Hamidreza Majidiani,Seyed Mohammad Riahi,Sasan Khazaei,Milad Badri,Elham Yousefi 한국역학회 2018 Epidemiology and Health Vol.40 No.-

OBJECTIVES: Toxoplasmosis is a parasitic disease that occurs worldwide, with a wide range of complications in immunocompromised patients. This systematic review and meta-analysis was performed to evaluate the seroprevalence of Toxoplasma gondii among patients undergoing hemodialysis in Iran. METHODS: We searched English and Persian databases for studies reporting T. gondii seroprevalence in Iranian hemodialysis patients through December 31, 2017. Inclusion and exclusion criteria were applied. RESULTS: A total of 10 studies containing 1,865 participants (1,048 patients and 817 controls) met the eligibility criteria. Immunoglobulin G (IgG) antibodies against T. gondii were found in 58% (95% confidence interval [CI], 46 to 70) of hemodialysis patients and 40% (95% CI, 31 to 50) of healthy controls, while immunoglobulin M (IgM) antibodies were found in 2% (95% CI, 0 to 6) of hemodialysis patients and 0% (95% CI, 0 to 1) of healthy controls. The meta-analysis showed that hemodialysis patients were significantly more likely to be seropositive for IgG (odds ratio [OR], 2.04; 95% CI, 1.54 to 2.70; p<0.001) and IgM (OR, 2.53; 95% CI, 1.23 to 5.22; p<0.001) antibodies against T. gondii infection than healthy individuals. CONCLUSIONS: The current study revealed a high prevalence of T. gondii infection in hemodialysis patients. Since hemodialysis patients are immunocompromised and T. gondii can cause serious clinical complications, we recommend that periodic screenings for T. gondii infection should be incorporated into the routine clinical care of these patients.

The Impact of Rigid Cervical Collars on Outcome of Patients Who Underwent Posterior Cervical Laminectomy and Fusion: A Retrospective Comparative Study

Khadivi Masoud,Moghadam Navid,Saghebdoust Sajjad,Khan Furqan Mohammed Yaseen,Eslamian Mohammad,Jouibari Morteza Faghih,Shafizadeh Milad,Moosavi Mersad,Zarei Mohammad,Kordi Ramin,Rostami Mohsen 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.2

Study Design: Retrospective cohort study.Purpose: This study aimed to investigate the cervical collar impact on the functional outcomes of patients after posterior cervical laminectomy and lateral mass screw fixation (PCLF) surgery.Overview of Literature: The safety and possible benefits of implementing rigid cervical collars subsequent to PCLF are insufficiently investigated.Methods: Patients who underwent PCLF and received postoperative cervical collars from 2018 to 2020 were included in this retrospective cohort study. Their data were compared with an age- and sex-matched group of subjects who did not receive collars after PCLF during the same period. Pain intensity (using the Visual Analog Scale), Neck Disability Index, and quality of life (using 36-item Short Form Health Survey) of the patients were compared at baseline, 1, 3, 6, and 12 months postoperatively.Results: A total of 36 patients who received cervical collars after surgery and 40 controls were included. At baseline and 1-month follow-up, there were no differences in pain intensity, functional status, and quality of life between the groups. However, at 3 months postoperatively, the quality of life of the subjects with no orthosis was higher than those who received cervical collars (p =0.01). At 6- and 12-month follow-up, there were no differences between the groups in pain intensity, functional status, and quality of life.Conclusions: No difference in the pain intensity and functional status of patients who used cervical collars and controls was shown in our study. Patients who did not wear cervical collars had a higher quality of life during the 3-month postoperative evaluation. Future prospective, well-controlled studies with longer follow-ups are needed to further investigate the effects of cervical orthosis on the clinical outcome of patients after PCLF.