Use of “Chopstick” Technique for Enhanced Visualization of the Vitrectomy Port in Endophthalmitis Patients

Sepehr Bahadorani,JeongHyeon Sohn 대한안과학회 2020 Korean Journal of Ophthalmology Vol.34 No.5

Correlation Between Microstructure, Mechanical Properties, and Corrosion Characteristics of AZ31 Mg Alloy Processed by Accumulative Roll Bonding Process

Sepehr Samiei,Ghasem Dini,Mehdi Ebrahimian‑Hosseinabadi 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.1

In this work, the effect of the accumulative roll bonding (ARB) process on the microstructure, mechanical properties, andcorrosion characteristics of AZ31 Mg alloy was investigated. First, the ARB process up to 3 cycles at 350 °C was applied toannealed AZ31 Mg alloy sheets. Then, all samples were characterized via microstructure observations, mechanical investigations,and also, electrochemical analyses, and immersion tests in simulated body fluid (SBF) solution. In addition, the L929cell line was used to evaluate the cytotoxicity of the samples. The obtained results showed that after the third ARB cycle, theaverage grain size in the annealed sample decreased from ~ 14 to ~ 3 μm. Some ultra-fine grained (UFG) microstructures thathad a grain size of fewer than 1 μm were also observed in the 3-cycle ARB-processed sample. This grain refinement led to anincrease in the yield strength and micro-hardness values of the annealed sample from ~ 153 MPa, and ~ 55 Hv to ~ 214 MPa,and ~ 76 Hv. However, the ARB process had an adverse effect on the corrosion characteristics of samples, and the corrosionrate increased after the ARB process. Moreover, the viability of L929 cells in culture media containing extracts obtained fromthe annealed sample was higher than that for the 3-cycle ARB-processed sample after 3 days of incubation. The influenceof microstructural evolution in the ARB-processed AZ31 Mg alloy on the corresponding mechanical properties, corrosionbehaviors, and cytotoxicity results was discussed in detail.

Percutaneous Decortication of Cystic Renal Disease

Sepehr Hamedanchi,Ali Tehranchi 대한비뇨의학회 2011 Investigative and Clinical Urology Vol.52 No.10

Purpose: To assess the efficacy of percutaneous unroofing in the treatment of simple renal cysts instead of laparoscopic decortication and open surgeries. Materials and Methods: From November 2009 to October 2010 at our department, 11 patients with 12 simple cyst units were managed by percutaneous unroofing. All cysts were evaluated with ultrasonography and abdominal computed tomography. If there were no contraindications, cyst wall resection was performed. A standard transurethral resectoscope was used to resect the cyst wall, and the parenchymal portion of the cyst was subsequently cauterized. The drain was left in place for 2 days. Results: At the 5-month follow-up, patients were asked about their symptoms and ultrasonography was performed. From 12 cyst units, 8 were completely resolved, 3 were reduced to less than 50%, and 1 was persistent to near its original size. Success was defined as a more than 50% reduction in cyst volume. Conclusions: Simple renal cysts can be safely managed by percutaneous unroofing with a success rate of more than 90%. This technique can offer several advantages over open surgery, such as decreased length of hospital stay, improved convalescence, and reduced risk of complications. Percutaneous resection also avoids the multiple trocar sites, extensive dissection, and technical difficulty associated with laparoscopy. Purpose: To assess the efficacy of percutaneous unroofing in the treatment of simple renal cysts instead of laparoscopic decortication and open surgeries. Materials and Methods: From November 2009 to October 2010 at our department, 11 patients with 12 simple cyst units were managed by percutaneous unroofing. All cysts were evaluated with ultrasonography and abdominal computed tomography. If there were no contraindications, cyst wall resection was performed. A standard transurethral resectoscope was used to resect the cyst wall, and the parenchymal portion of the cyst was subsequently cauterized. The drain was left in place for 2 days. Results: At the 5-month follow-up, patients were asked about their symptoms and ultrasonography was performed. From 12 cyst units, 8 were completely resolved, 3 were reduced to less than 50%, and 1 was persistent to near its original size. Success was defined as a more than 50% reduction in cyst volume. Conclusions: Simple renal cysts can be safely managed by percutaneous unroofing with a success rate of more than 90%. This technique can offer several advantages over open surgery, such as decreased length of hospital stay, improved convalescence, and reduced risk of complications. Percutaneous resection also avoids the multiple trocar sites, extensive dissection, and technical difficulty associated with laparoscopy.

Biological soil crusts impress vegetation patches and fertile islands over an arid pediment, Iran

Sepehr Adel,Hosseini Asma,Naseri Kamal,Gholamhosseinian Atoosa 한국생태학회 2022 Journal of Ecology and Environment Vol.46 No.1

Background: Plant vegetation appears in heterogeneous and patchy forms in arid and semi-arid regions. In these regions, underneath the plant patches and the empty spaces between them are covered by biological soil crusts (moss, lichen, cyanobacteria, and fungi). Biological soil crusts lead to the formation and development of fertile islands in between vegetation patches via nitrogen and carbon fixation and the permeation of runoff water and nutrients in the soil. Results: The present study has investigated the association of biological soil crusts, the development of fertile islands, and the formation of plant patches in part of the Takht-e Soltan protected area, located in Khorasan Razavi Province, Iran. Three sites were randomly selected as the working units and differentiated based on their geomorphological characteristics to the alluvial fan, hillslope, and fluvial terrace landforms. Two-step systematic random sampling was conducted along a 100-meter transect using a 5 m2 plot at a 0–5 cm depth in three repetitions. Fifteen samplings were carried out at each site with a total of 45 samples taken. The results showed that the difference in altitude has a significant relationship with species diversity and decreases with decreasing altitude. Results have revealed that the moisture content of the site, with biocrust has had a considerable increase compared to the other sites, helping to form vegetation patterns and fertile islands. Conclusions: The findings indicated that biological crusts had impacted the allocation of soil parameters. They affect the formation of plant patches by increasing the soil’s organic carbon, nitrogen, moisture and nutrient content provide a suitable space for plant growth by increasing the soil fertility in the inter-patch space.

Effects of Iron Supplementation on Attention Deficit Hyperactivity Disorder in Children Treated with Methylphenidate

Sepehr Tohidi,Elham Bidabadi,Mohammad-Javad Khosousi,Melika Amoukhteh,Maryam Kousha,Parham Mashouf,Tamkin Shahraki 대한정신약물학회 2021 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.19 No.4

Objective: To evaluate the effect of iron on the attention deficit hyperactivity disorder, treated with methylphenidate. Methods: This double-blind, randomized placebo-controlled clinical trial was performed on 50 children with attention deficit hyperactivity disorder under the treatment of methylphenidate, with ferritin levels below 30 ng/ml and absence of anemia. They were randomly assigned into two groups of ferrous sulfate and placebo, for 12 weeks. Conners' Parent Rating Scale (CPRS) was used to assess the outcome in the first, sixth, and twelfth weeks. Results: Almost all CPRS subscales improved in the ferrous sulfate group from the baseline to the endpoint, although only the changes in conduct subscale scores were significant (p = 0.003). There was no significant difference in score changes between two groups in intergroup comparison. Also, the score of learning problems (p = 0.007) in the first six weeks, and conduct (p = 0.023) and psychosomatic (p = 0.018) subscales in the second six weeks were improved in the ferrous sulfate group compared with the placebo group. Conclusion: Our study showed promising effects of iron supplementation in the improvement of subscales of the CPRS.

4-Lump kinetic model for vacuum gas oil hydrocracker involving hydrogen consumption

Sepehr Sadighi,Arshad Ahmad,Mehdi Rashidzadeh 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4

A 4-lump kinetic model including hydrogen consumption for hydrocracking of vacuum gas oil in a pilot scale reactor is proposed. The advantage of this work over the previous ones is consideration of hydrogen consumption,imposed by converting vacuum gas oil to light products, which is implemented in the kinetic model by a quadratic expression as similar as response surface modeling. This approach considers vacuum gas oil (VGO) and unconverted oil as one lump whilst others are distillate, naphtha and gas. The pilot reactor bed is divided into hydrotreating and hydrocracking sections which are loaded with different types of catalysts. The aim of this paper is modeling the hydrocracking section, but the effect of hydrotreating is considered on the boundary condition of the hydrocracking part. The hydrocracking bed is considered as a plug flow reactor and it is modeled by the cellular network approach. Initially,a kinetic network with twelve coefficients and six paths is considered. But following evaluation using measured data and order of magnitude analysis, the three route passes and one activation energy coefficient are omitted; thus the number of coefficients is reduced to five. This approach improves the average absolute deviation of prediction from 7.2%to 5.92%. Furthermore, the model can predict the hydrogen consumption for hydrocracking with average absolute deviation about 8.59% in comparison to those calculated from experimental data.

A two-dimensional discrete lumped model for a trickle-bed vacuum gas oil hydrocracking reactor

Sepehr Sadighi 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.9

A two-dimensional (2D) computational fluid dynamics model based on discrete lumping approach was used to predict the product yields of a pilot scale vacuum gas oil (VGO) hydrocracking reactor. This model was developed by solving mass conservation equations in conjunction with the continuity and momentum balances in the z-r cylindrical plane. The kinetic parameters of the model were estimated from the experimental data, and validated by using actual values. Results show that the proposed model can appreciably improve the accuracy of the yield prediction in comparison to the predicted value using the 1D model. Moreover, it is confirmed that the order of magnitude of the radial liquid velocity against the axial one is considerably low, and there is no significant pressure drop along the r-direction. Additionally, results show that two-dimensional model is a reliable tool for evaluating the catalyst performance and also for designing commercial reactors.

Post-Automobility Futures: Technology, Power, and Imaginaries

Pouya Sepehr Academy of Mobility Humanities 2023 Mobility Humanities Vol.2 No.1

In response to increasing worldwide interest in movement, access, and mobility justice, fed above all by recent experiences caused by Covid-19; this book is a valuable contribution to think about moving over the past century automobility discourse. Robert Braun and Richard Randell are both key scholars in the field of mobility studies. Their research interest stands at the intersection of STS, political philosophy, and mobility studies; where they raise democratic enquiry into decision making about the future of automobility and the forms of violence that automobility causes.

Effect of curing conditions on mode-II debonding between FRP and concrete: A prediction model

Pengcheng Jiao,Sepehr Soleimani,Quan Xu,Lulu Cai,Yuanhong Wang 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.6

The rehabilitation and strengthening of concrete structures using Fiber-Reinforced Polymer (FRP) materials have been widely investigated. As a priority issue, however, the effect of curing conditions on the bonding behavior between FRP and concrete structures is still elusive. This study aims at developing a prediction model to accurately capture the mode-II interfacial debonding between FRP strips and concrete under different curing conditions. Single shear debonding experiments were conducted on FRP-concrete samples with respect to different curing time t and temperatures T. The J-integral formulation and constrained least square minimization are carried out to calibrate the parameters, i.e., the maximum slip s ̅ and stretch factor n. The prediction model is developed based on the cohesive model and Arrhenius relationship. The experimental data are then analyzed using the proposed model to predict the debonding between FRP and concrete, i.e., the interfacial shear stress-slip relationship. A Finite Element (FE) model is developed to validate the theoretical predictions. Satisfactory agreements are obtained. The prediction model can be used to accurately capture the bonding performance of FRP-concrete structures.

Plastic properties determination using virtual dynamic spherical indentation test and machine learning algorithms

Mohammad Kashfi,Sepehr Goodarzi,Mostafa Rastgou 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

Nondestructive experiments are widely employed for determining mechanical properties. In this work, a spherical impact test is virtually performed to determine the plastic properties of a thick aluminum plate. The finite element model is validated experimentally, and several simulations are then performed in accordance with the design of the experiment program. Several algorithms, including support vector machine, Gaussian process regression (GPR), and nonlinear regressions (second- and third-order polynomials) as machine learning techniques, are employed to estimate the material plastic properties. The indentation depth and indentation radius are considered as input variables to predict the tangent modulus (TM) and yield stress (YS). Results reveal that the second-order polynomial and GPR methods realize better performance in terms of determination coefficient and root mean square error criteria in assessing YS.