Selective degradation of mixed dye pollutant in aqueous phase in the presence of ZnO/Al2O3 as sonophotocatalysis based on central composite design

Reza Mahdavi,Seyed Siamak Ashraf Talesh 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.6

The selective sono/photocatalytic degradation of methyl orange (MO) in a mixture of methylene blue (MB) by synthesized ZnO/Al2O3 nanocomposites via ultrasound-assisted sol-gel method was studied. The synthesized samples were analyzed by XRD, TEM, EDX, BET, FTIR, UV-vis and Zeta potential analysis. The results showed that the ZnO nanoparticles were hexagonal wurtzite structures that changed to a flake-like quadrilateral morphology by enhancing the Al2O3 dosage. To optimize the selective removal efficiency of MO, response surface methodology (RSM) based on the central composite design (CCD) was applied to study the influence of Al2O3 dosage, catalyst amount, dye concentration and reaction time. A reliability prediction based on a second-order model was achieved with a high coefficient of determination (R2) and adjusted R2 of 0.9914 and 0.9834 for the optimized removal process, respectively. The MO optimal conditions of selective removal efficiency were found at 6.39 wt% of Al2O3 dosage, 32.2mg catalyst amount, 7mg/L of dye concentration and reaction time of 150min to achieve 91.42% removal of MO dye. In the optimal conditions of selective removal, the advanced sono/photocatalytic technique was used to investigate the complete degradation of the adsorbed MO on the catalyst surface. The FTIR spectrum of the MO degradation shows complete removal of some bands compared to the initial control dye, which confirms the degradation of MO after ultrasonic (US) and ultraviolet (UV) irradiation. The use of ZnO/Al2O3 nanocomposites in sonocatalysis process leads to producing electron/hole pairs, whereby the production of reactive oxygen species, MO selected molecules were oxidized quickly.

Platelet volume indices in patients with varicocele

Mahdavi-Zafarghandi, Reza,Shakiba, Behnam,Keramati, Mohammad Reza,Tavakkoli, Mahmoud The Korean Society for Reproductive Medicine 2014 Clinical and Experimental Reproductive Medicine Vol.41 No.2

Objective: This study sought to evaluate platelet volume indices (mean platelet volume [MPV], platelet distribution width [PDW], and platelet large cell ratio [P-LCR]) in varicocele patients, and compare it with platelet volume parameters in healthy controls. Methods: This cross-sectional study involved 2 groups: group 1 included 51 varicocele subjects and group 2 consisted of 50 healthy control subjects of similar ages. Peripheral venous blood samples were collected with ethylenediaminetetraacetic acid-K2 anticoagulant between 8:30 AM and 10 AM following an overnight fast. Platelet volume parameters (MPV, PDW, and P-LCR) were measured in both groups within 2 hours of sampling. Results: The mean PDW, MPV, and P-LCR were $13.9{\pm}2.5%$, $10.1{\pm}1.3fL$, and $27.3{\pm}7.8%$ in varicocele patients, respectively, and were $12.6{\pm}2.4%$, $9.3{\pm}1.1fL$, and $21.9{\pm}6.4%$ in the control group, respectively. The mean PDW, MPV, and P-LCR were significantly higher in the varicocele group than the control group. Conclusion: The results of the present study suggest that vascular components may play an important role in the pathophysiology of varicocele; therefore, there is a great need for prospective studies to confirm this relationship.

Stabilization of [BMIM][PF6] ionic liquid membrane in structurally optimized multilayer ceramic support through aqueous DEA solution for CO2/CH4 separation

Hamid Reza Mahdavi,Mehran Arzani,Hamed Faramarzi,Omid Bakhtiari,Toraj Mohammadi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

The stability of the ceramic supported liquid membranes (SLMs) is one of the most interesting researchsubjects. In this work, the SLMs’ stability for CO2/CH4 separation was investigated. Following pressing a-Al2O3 substrates at 400, 600, and 800 bar, colloidal and polymeric TiO2 intermediate and top layers werecoated. Aqueous diethanolamine (DEA) solution was used as solvent in the SLM to optimize supportstructure based on CO2/CH4 separation performance. The pressed support at 800 bar and coated withTiO2 demonstrated best performance and selected for further study. Subsequently, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) ionic liquid (IL) was immobilized inside theselected support and used as the supported ionic liquid membrane (SILM) for CO2/CH4 separation. TheSILM separation performance was evaluated under different pressures and temperatures. Temperaturewas found to has greater effect than pressure due to a decrease in IL’s viscosity and an increase in penetrantdiffusivity. At 25 C and 1 bar, SILM exhibited consistent and reliable performance as CO2 and CH4permeabilities of 244.0 and 7.4 Barrer, respectively, and CO2/CH4 selectivity of 33.0 over 6 h. The findingscontribute to understanding the implementation of multilayer ceramic SILMs for CO2/CH4 separation andhighlight its potential along with opening up new avenues.

Soft Switching Three Phase Inverter with Two Auxiliary Switches

Mahdavi, Mohammad,Amini, Mohammad Reza,Emrani, Amin,Farzanehfa, Hosein The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.6

In this paper, a new three phase soft switching inverter is presented. All of the semiconductor elements of this converter are soft switched. Employing only two auxiliary switches as DC-link switches and a simple control circuit are the advantages of the proposed inverter. The analytical equations and operating modes of the presented inverter are explained in details. The design considerations are presented and the experimental results verify the theoretical analysis.

The effects of viscosity, surface tension, and flow rate on gasoil-water flow pattern in microchannels

Reza Gheshlaghi,Rahman Sadeghi Boogar,Mahmood Akhavan Mahdavi 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.1

A microchannel was fabricated with glass tubes to investigate the effect of viscosity, surface tension, and flow rate on the liquid-liquid two-phase flow regime. Water and gasoil were selected as aqueous and organic working fluids, respectively. The two fluids were injected into the microchannel and created either slug or parallel profile depending on the applied conditions. The range of Reynolds and capillary numbers was chosen in such a way that neither inertia nor interfacial tension forces were negligible. Xanthan gum was used to increase viscosity and Triton X-100(TX-100) and Sodium Dodecyl Sulfate (SDS) were used to reduce the interfacial tension. The results demonstrated that higher value of viscosity and flow rate increased interfacial area, but slug flow regime remained unchanged. The two surfactants showed different effects on the flow regime and interfacial area. Addition of TX-100 did not change the slug flow but decreased the interfacial area. In contrast, addition of SDS increased interfacial area by decreasing the slug’s length in the low concentrations and by switching from slug to parallel regime at high concentrations.

Seismic mitigation of substation cable connected equipment using friction pendulum systems

Reza Karami Mohammadi,Masoud Mirtaheri,Mojtaba Salkhordeh,Erfan Mosaffa,Golsa Mahdavi,Mohammad Amin Hariri-Ardebili 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.6

Power transmission substations are susceptible to potential damage under seismic excitations. Two of the major seismic failure modes in substation supplies are: the breakage of brittle insulator, and conductor end fittings. This paper presents efficient isolation strategies for seismically strengthening of a two-item set of equipment including capacitive voltage transformer (CVT) adjacent to a Lightning Arrester (LA). Two different strategies are proposed, Case A: implementation of base isolation at the base of the CVT, while the LA is kept fixed-base, and Case B: implementation of base isolation at the base of the LA, while the CVT is kept fixed-base. Both CVT and LA are connected to each other using a cable during the dynamic excitation. The probabilistic seismic behavior is measured by Incremental Dynamic Analysis (IDA), and a series of appropriate damage states are proposed. Finally, the fragility curves are derived for both the systems. It is found that Friction Pendulum System (FPS) isolator has the potential of decreasing flexural stresses caused by intense ground motions. The research has shown that when the FPS is placed under LA, i.e. Case B (as oppose to Case A), the efficiency of the system is improved in terms of reducing the forces and stresses at the bottom of the porcelain. Several parametric studies are also performed to determine the optimum physical properties of the FPS.

Efficient parameters to predict the nonlinear behavior of FRP retrofitted RC columns

Navideh Mahdavi,Hamid Reza Ahmadi,Mahmoud Bayat 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.70 No.6

While fiber-reinforced plastic (FRP) materials have been largely used in the retrofitting of concrete buildings, its application has been limited because of some problems such as de-bonding of FRP layers from the concrete surface. This paper is the part of a wide experimental and analytical investigation about flexural retrofitting of reinforced concrete (RC) columns using FRP and mechanical fasteners (MF). A new generation of MF is proposed, which is applicable for retrofitting of RC columns. Furthermore, generally, to evaluate a retrofitted structure the nonlinear static and dynamic analyses are the most accurate methods to estimate the performance of a structure. In the nonlinear analysis of a structure, accurate modeling of structural elements is necessary for estimation the reasonable results. So for nonlinear analysis of a structure, modeling parameters for beams, columns, and beam-column joints are essential. According to the concentrated hinge method, which is one of the most popular nonlinear modeling methods, structural members shall be modeled using concentrated or distributed plastic hinge models using modeling parameters. The nonlinear models of members should be capable of representing the inelastic response of the component. On the other hand, in performance based design to make a decision about a structure or design a new one, numerical acceptance should be determined. Modeling parameters and numerical acceptance criteria are different for buildings of different types and for different performance levels. In this paper, a new method was proposed for FRP retrofitted columns to avoid FRP debonding. For this purpose, mechanical fasteners were used to achieve the composite behavior of FRP and concrete columns. The experimental results showed that the use of the new method proposed in this paper increased the flexural strength and lateral load capacity of the columns significantly, and a good composition of FRP and RC column was achieved. Moreover, the modeling parameters and acceptance criteria were presented, which were derived from the experimental study in order to use in nonlinear analysis and performance-based design approach.

Development of Gold-Coated Magnetic Nanoparticles as a Potential MRI Contrast Agent

Ali Reza Montazerabadi,Mohammad Ali Oghabian,Rasoul Irajirad,Samad Muhammadnejad,Davoud Ahmadvand,Hamid Delavari H,Seyed Rabie Mahdavi 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.4

Gold-coated superparamagnetic iron oxide nanoparticles (SPIONs) coated with methylpolyethylene glycol (mPEG) are synthesized and investigated as a magnetic resonance (MR) imaging contrast agent. The synthesized mPEG-core@shells are characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometry (VSM), zeta-potential analysis and X-ray diffraction (XRD). In addition, the transverse relaxivity of the mPEG-core@shells is measured using a 3 T MRI scanner. The cytotoxicity of the mPEG-core@shells is tested in the LNCaP cell line using an 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results show that the mPEG-core@shell particles are semispherical with hydrodynamic size of ~65 nm and a transverse relaxivity of 162.3 mM-1 S-1. The mPEG-core@shell particles demonstrate good stability in biological media without any significant in vitro cytotoxicity under high cellular uptake conditions. Finally, in vivo imaging shows that mPEG-core@shells are a potential contrast agent for use in early-stage detection.

Soft Switching Three Phase Inverter with Two Auxiliary Switches

Mohammad Mahdavi,Mohammad Reza Amini,Amin Emrani,Hosein Farzanehfard 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.6

In this paper, a new three phase soft switching inverter is presented. All of the semiconductor elements of this converter are soft switched. Employing only two auxiliary switches as DC-link switches and a simple control circuit are the advantages of the proposed inverter. The analytical equations and operating modes of the presented inverter are explained in details. The design considerations are presented and the experimental results verify the theoretical analysis.

Oxidative Stress-Induced Apoptosis in Chronic Myelogenous Leukemia K562 Cells by an Active Compound from the Dithio-Carbamate Family

Khoshtabiat, Laya,Mahdavi, Majid,Dehghan, Gholamreza,Rashidi, Mohammad Reza Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.9

Previous studies suggested that dithio-carbamates are potent apoptosis and anti-apoptosis inducing agents in various cancer cells. Here, the anti-proliferative and apoptosis inducing effects of a new derivative (2-NDC) from the dithio-carbamate family was examined in human leukemia K562 cells. We use thiazolyl blue tetrazolium bromide (MTT) to measure viability and cell growth inhibition. The 2-NDC showed effects on viability in a dose and time-dependent manner, inhibiting proliferation at concentrations of $10-30{\mu}M$ after 24-48 hours of treatment and increasing values after 72 hours at $40-120{\mu}M$. The cytotoxic effect of the compound was calculated with an $IC_{50}$ of $30{\mu}M$ after 24-hour. Apoptosis induction was confirmed by acridine orange-ethidium bromide (AO/EtBr) staining, DNA fragmentation assay, flow cytometric assessment and also caspase-3 activation assay. Furthermore, enzymes level such as superoxide dismutase (SOD) and catalase (CAT) involved in oxidative stress were evaluated. The results of this study demonstrated insignificant increase of intracellular ROS levels for 24 hours and reduction after 48-72 hours. In addition to reduction of intracellular thiol, caspase-3 like activity was also decreased in a time-dependent manner in cells treated with 2-NDC. Thus 2-NDC can be considered as a good candidate for further pharmaceutical evaluations.