Showing 14 results for Mahdizadeh
Volume 2, Issue 2 (Summer 2018)
Abstract
Fiber production in nanoscale prepares high surface contact for fibers and leads to the improvement of their properties with respect to other fibers. A convenient and effective method for nanofiber production with different diameters is electrospinning. Various effective parameters on electrospinning processes, including environmental, equipment, and solution variables can produce fibers with different morphologies. PVA has been used in various fields of applied research because of its high thermal stability, biocompatibility, non-toxic and solubility in water. The published reports indicated that properties of the PVA are improved with the addition of bentonite. In this research, to prepare PVA/nano-bentonite nanofiber membrane, the optimum amounts of three effective variables on the above-mentioned processes were determined. According to the obtained results, the voltage of 11 kV, the feeding rate of 0.5 mL/h and bentonite concentration of 3% w/w were optimum conditions for the process of PVA/nano-bentonite nanofiber composite production. In this condition, the average diameter of produced nanofibers was 243 nm with the standard deviation of 0.0551 and the tensile strength of 7.64 MPa. The results showed that the addition of bentonite to PVA increase intensity of nanofibers and decrease the diameter of nanofibers from 308 nm to 243nm.Therfore, the produced PVA/bentonite nanofiber composite is a good membrane for water treatment.
Volume 4, Issue 3 (9-2015)
Abstract
In vitro antifungal activity of silver nanoparticles, at concentrations of 6, 8, 10, 12, 14 and 16 ppm, was studied on five phytopathogenic fungi, and a biocontrol agent. Then effect of silver nanoparticle at 6 ppm (optimum concentration) was evaluated on Macrophomina phaseolina in greenhouse. For in vitro experiment, the fungal isolates were grown on potato dextrose agar medium amended with silver nanoparticles. Radial fungal growth was recorded after 1, 2, 3, 5 and 10 days and mycelial growth inhibition rates were calculated. The most sensitive fungus to nanoparticles was Pythium aphanidermatum, since all tested concentrations showed 100% inhibition during the 10 days of observation.The second most sensitive fungus was Sclerotinia sclerotiorum, since it was able to grow only at concentration of 6 ppm and M. phaseolina was the third in sensitivity since its growth was inhibited in all concentrations after three days. In greenhouse experiments, five treatments including no nanosilver-no pathogen (Negative control), no nanosilver +pathogen (Positive control), 6 ppm nanosilver– no pathogen, 6 ppm nanosilver +pathogen, Carboxin-Thiram (0.15%) +pathogen were compared. Four characters viz shoot and root fresh and dry weights were measured. Based on the greenhouse experimental results, treatments with nanosilver and fungicide gave higher yields than the positive control. The chemical control treatment had the highest measured parameters, while 6 ppm nanosilver +pathogen treatment had the same parameters as negative control. It may therefore be suggested to use nanosilver as a safer alternative to chemical fungicides for control of M. phaseolina.
Volume 8, Issue 2 (Spring 2023)
Abstract
Aims: Transportation of patients in hospitals is one of the main reasons for the prevalence of musculoskeletal diseases among health care workers. Considering that the practical action of recognizing and evaluating the studies has been done, therefore the present study has been conducted with the aim of determining the prevalence of musculoskeletal diseases and the determinants affecting the disorders in a systematic manner in Iran.
Method and Materials: In this systematic review, English databases of Web of Science, Scopus, Proquest, PubMed as well as databases Magiran, SID in Iran, and also Google Scholar search engine in the period Jan 1990 to Jan 2020 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement were done. Study process was conducted from 28th September to the end of October. Cochrane (adapted for evaluating interventional studies) and Strengthening the Reporting of Observation Studies in Epidemiology (STROBE) checklists (adapted for evaluating cross-sectional studies) were used to evaluate the quality of the articles. To avoid bias in the study, the data were analyzed by two researchers entirely independently. Any disagreement between the researchers was examined by a third party.
Findings: Out of 93 articles, finally, 10 articles2 (interventional and 8 cross-sectional articles) entered the final list of studies. Thus, the final articles were performed on health system staff (nurse, nurse’s assistance, helper nurse’s assistance and service workers). In all studies, the prevalence of musculoskeletal diseases were highly reported among those responsible for transporting the patient.
Conclusions: Considering the high prevalence of musculoskeletal disorders among the medical staff, the interventions carried out in the field of teaching the correct method of patient transportation in Iran seem insufficient, so that there is a need for better planning and designing more practical interventions. Also, often enough tools and equipment are not available for easy transportation, which should be considered by hospital managers.
Volume 10, Issue 1 (10-2021)
Abstract
Genus Lentinula comprises some of the most important edible and medicinal fungal species of the world. To compare growth rate of the strains of this genus, samples were collected from different regions of the world including Iran during 2017-2018. Investigation of the growth of 40 strains on two substrates containing malt and wheat straw extracts showed their relatively excellent performance on both media. Based on preliminary growth characteristics of the strains, 20 strains were selected to study their growth rate on natural substrate containing defined proportion of straw (40%) + sawdust (40%) + wheat bran (20%). Three strains including VM230 (UK strain), VM267 (Belgium strain) and VM353 (Japanese strain) showed high growth rate (65.25, 63.75 and 64.50 mm d-1, respectively), and were identified as Lentinula edodes by ITS4 and ITS5 sequencing. Growth rate of the best strain (VM230) was evaluated on different substrates containing different proportions of straw, sawdust and wheat bran. The highest growth rate (58.75 mm d-1) for VM230 was recorded on wheat straw (80%) + wheat bran (20%). These three strains are promising for commercial production of Shiitake.
Volume 11, Issue 2 (Vol. 11, No. 2 (Tome 56), (Articles in Persian) 2020)
Abstract
This article examines the reproduction of gender identity in Dowlatabadi’s short story “The Man” in the light of Judith Butler’s theory of Gender Performativity. It investigates the cultural function of identity and the way language discursively reflects the role of the unestablished identity in the story. It also presents new outlooks towards language performativity of the male/female dichotomy. What this article focuses on is an individual's identity, and language, exploring the concept of gender performativity.
Butler asserts that performativity is a ritualized production and a constrained reiteration of cultural intelligibility under the compulsory prohibition pressed by the power regimes. The culturally-acquired gender is crafted based on the socially recognizable standards, which form the directionality of the self-representation. A Gender is an act that requires a repeated performance in ritual and social dramas. She declares that one is not born but rather becomes a subject whose gender is a discursive construction that defines his/her body. Moreover, the gendered subjects were subordinated to the language that interpellated them, so that each individual became a linguistically stylized occasion.
Dowlatabadi’s main character in this story undergoes transfiguration from childhood to adulthood affected by the social upheavals leading him towards his crafted and gendered identity formation. His father’s roles are resignified through the reiteration and imitation of the gendered and naturalized regulations. Surveying “The Man” elucidates that gender identity is an imitation, which leads the character to resignify and recontextualize the parodic gender reproductions. Therefore, the established discourses gave the agent the feasibility to establish his intelligible social existence.
Springing from the discussion about gender performativity of Dowlatabadi’s character, the article concluded that identity is a phantasmatic construction. What an individual performes is a non-intrinsic parody of the culturally constructed regulations. It can be concluded that identity is established by the power of language that interpellates the subjects.
Sadegh Moodi, Hossein Mahdizadeh, Mehdi Azhdary Moghaddam,
Volume 17, Issue 4 (6-2017)
Abstract
Accurate investigation of physical phenomena is one of the important challenges in engineering fields. The present study is about a wet tank which entrance of water is investigated in three cases. When the water wave moves into a tank, complex flow regimes are created. This complexity is mainly associated with different flow mechanisms during the entrance of water and propagation of waves at the bottom bed that should be modelled by means of Navier-Stokes equations with free-surface capability and in 3D phase. Due to complexity and time consuming of Navier-Stokes equations modelling, Shallow water equations are used with the assumption of hydrostatic pressure. First case is about efflux over a wet bed. Second, water influx from the middle top is investigated and then influx from top edges is modelled. A dimensionless number is introduced for each case based on water velocity, gap length and drop height which shows acceptable domain for appropriate compatibility between results. Finally, results of numerical modelling are compared with Navier-Stokes solutions which are obtained from STAR-CD software. Results show admissible compatibility with each other based on observations and inspections.
Hossein Mahdizadeh, Hadi Cheharbidi, Sadegh Moodi,
Volume 17, Issue 7 (9-2017)
Abstract
Modelling of flood waves within surface and subsurface network is quite complicated. This complexity is mainly with respect to different flow regimes propagation into the sewer network which interacts with each other at connections between underground networks. The main purpose of the present paper is modelling and hydrodynamic prediction of these types of bore interactions using the shallow water equations. The shallow water equations are then solved using a second-order accurate HLLC Riemann which is able to model the wave propagation over wet and dry states based upon a combination of particular Riemann wave speeds. Friction terms are treated in a separate way within the associated source terms. First, the numerical solver is employed to model the shock and rarefaction waves over the wet and dry states and the achieved numerical results are compared with the exact solution. Then, the effect of friction terms for the one-dimensional dam failure propagation over wet and dry bed is considered and the computed results are compared with the STAR-CD which is a Navier-Stokes solver. Finally, two-dimensional flood wave propagation is modelled within a rectangular sewage section and the obtained results are validated with the three-dimensional STAR-CD results. The numerical results demonstrate that the defined numerical solver in both one and two-dimensional provides very good agreement with the exact solution and Navier-Stokes solver.
Mina Barzgaran, Hossein Mahdizadeh, Salman Pouresmaeil,
Volume 17, Issue 9 (11-2017)
Abstract
In this paper a Godunov-type finite volume method is used for the solution of bedload sediment transport dynamics. The utilised equations for this modelling comprise the shallow water equations used for the hydrodynamic phase and also the Exner equation applied for the morphodynamic variations. These set of equations are then solved using a weakly-coupled scheme based on an augmented Riemann solver. In this approach the morphodynamic equation is first solved and the updated bedload changes with the same Riemann structure are used as a source term within the shallow water equations. The proposed numerical model is first used for the simulation of the parabolic sediment layer and the obtained numerical results are validated with the exact solution. Then, a bedload hump propagation with an initial subcritical condition which is able to create both mild and strong sediment and free-surface interactions is considered and the computed results are compared with the reference solution. These numerical results indicate that the defined weakly coupled method developed based on an augmented Riemann technique is able to be used for modelling bedload sediment transport for all flow regimes and exhibits a very good agreement with analytical or reference solutions for the given test cases.
Mina Barzgaran, Hossein Mahdizadeh, Salman Pouresmael,
Volume 18, Issue 5 (9-2018)
Abstract
Various numerical methods have been developed for solving morphodynamic systems, among which the finite-volume method has been widely employed in recent years. This paper presents an efficient finite volume technique for simulation of bedload sediment transport near dry interfaces. The equations governing sediment transport in channels and rivers comprise the shallow water equations and Exner equation. By considering a novel velocity for Riemann waves, shallow water and Exner equations are solved using a weakly-coupled scheme based on an augmented Riemann solver. In this approach the morphodynamic equation is first solved and the updated bedload changes with the same Riemann structure are used as a source term within the shallow water equations. Augmented Riemann solver is based on a decomposition of an augmented vector—the depth, momentum as well as momentum flux and bottom surface. The proposed numerical model is first used for the simulation dam break flow over a mobile bed. Then, dam failure due to over-topping flow is considered and the computed results are compared with the experimental data.These numerical results indicate that the defined weakly coupled method developed based on an augmented Riemann technique is able to be used for modelling bedload sediment transport near dry interfaces with highly accurate and exhibits a very good agreement with the experimental data for test cases.
Sadegh Moodi, Hossein Mahdizadeh,
Volume 18, Issue 6 (10-2018)
Abstract
In this paper a modified Godunov-type wave propagation algorithm is utilised for the modelling of falling water wave over a dry bed. The defined numerical model is well-balanced and is capable to treat the influx/efflux source terms and also the friction term within the flux-differencing of the finite volume neighbouring cells. Additionally, the method employs a rather simple HLLE wave speed for the propagation over dry-state. First the efflux flow from the bed of a reservoir is analyzed. Then, the entrance of falling water wave from the middle and edge sides of the reservoir over a dry bottom is simulated. In order to validate the achieved numerical results for the non-hydrostatic pressure situations a dimensionless number based upon the inflow velocity, the slot length and the falling height is introduced. The obtained results of the defined numerical solver are then compared with the numerical prediction of the STAR-CD which is a commercial Navier-Stokes package. The numerical results demonstrate that the introduced flux-wave solver is able to simulate the falling water waves over the dry-state for a given range of the dimensionless number.
Volume 18, Issue 113 (july 2021)
Abstract
In this study, the effect of various concentrations of date syrup as a sugar substitute in ratios of 0, 50 and 100% on quality characteristics of dairy dessert was evaluated. Properties of dairy dessert such as pH, acidity, rheological properties, sensory properties and viability of probiotics in 5 ˚c were determined. Results showed that by increasing date syrup concentration and amount of probiotic bacteria, pH decreased and as the storage progressed significant trend in the pH was observed for all treatments. Studied treatments had statistically effect on viscosity. Addition of date syrup decreased apparent viscosity, consistency coefficient and increased flow behavior index. The most and lowest viscosity was observed in control (1364.1 mPa.s) and 100% date syrup treatments (599 mPa.s), respectively. Sensory properties were affected by date syrup concentrations. Treatment with 50% date syrup had higher scores than others. The number of viable cells of probiotic bacteria was reduced significantly during storage period. The lowest and highest of viability of probiotic bacterial was observed in 100 and 50 % date syrup treatments, respectively. The results suggest that using of date syrup at concentrations of 50% improve sensory and physical properties and can increase viability of probiotic bacteria of dairy dessert samples.
V. Hoseini, M. Shariati, M. Mahdizadeh Rokhi,
Volume 20, Issue 6 (June 2020)
Abstract
In this research, the behavior of conical and hemispherical shells, made of steel and aluminum, respectively, subject to impact loading has been investigated using experimental and numerical methods. The energy absorption capacity of these adsorbers has been calculated and the effect of foam injection on the collapse behavior and energy absorption capacity of aluminum hemispherical shells has been determined. The effect of geometrical parameters on the collapse behavior and adsorption capacity of steel conical adsorbers has also been investigated. Numerical simulations have been performed using the Abaqus finite element software and the results have been compared with the results of the experiments. In Numerical analysis, three damage models, Johnson-Cook, GTN, and modified Rousselier have been used. The Johnson-Cook damage model is available in Abaqus software but the GTN and the modified Rousselier damage models have been created through programming in Abaqus software. The results show that the modified Rousselier damage model is more accurate than the other damage models. Also, in this research, the effect of thickness of conical shells on their efficiency has been investigated and it becomes clear that increasing the thickness of absorber increases efficiency. In addition, foam injection does not a positive effect on the hemispherical absorber performance.
Mona Sadat Ashrafi, Mostafa Nazari, Naserodin Sepehry, Masoud Mahdizadeh Rokhi, Parsa Samimi, Matin Attarchi,
Volume 22, Issue 8 (August 2022)
Abstract
The series elastic actuators make more comfort in the use of assistive exoskeletons. In this paper, an assistive controller is designed for a series-elastic-actuator-driven knee exoskeleton to restore normative mobility of individuals with weak muscles. The main target of the proposed controller is to modify the dynamics performance of the coupled human-exoskeleton system. In other words, the proposed controller modifies the relationship between the net muscle torque exerted by the human and the resulting angular motion. There are fewer sensors in the proposed intent-independent method relative to other methods. Moreover, there are less controller coefficients to regulate where these coefficients are extracted from a type zero
Takagi-Sugeno-Kang fuzzy system. The performance of the controller is evaluated by simulations and experiments. The amplitude of the EMG signals decreased in a healthy person worn the SUT-KneeExo. Moreover, the proposed algorithm has a better performance in comparison with integral admittance shaping mothed and output feedback assistive controller. In other words, the amplitude of the integral admittance is more and the phase lag is less than other methods.
Volume 24, Issue 2 (6-2024)
Abstract
Rapid growth of population is leading to high water consumption and producing large amount of waste water which needs to be treated and being reutilized for reusing purposes. Among sewage treatment methods, the use of integrated activated sludge and membrane separation is increasing due to advantages such as higher quality effluents, lower ecological footprint, less sludge production, and lower operational costs. Despite the many benefits, the problem of membrane fouling due to deposition and adsorption of colloidal and soluble material on the surface of membrane has limited the use of this method. There are several methods for eliminating and mitigating membrane fouling, each with disadvantages such as increasing costs, producing secondary pollutants, increasing sludge production, reducing the membrane life and durability, etc. In recent years, the use of electrical coagulation as a method to reduce membrane fouling in the MBR system has been taken into account. Submerged Membrane Electro Bioreactors (SMEBR) is a new approach that reduces clogging of the membrane by combining the MBR system with the electric field. In the forthcoming research, the effects of electric field on the system were investigated by applying a low voltage electric field (1.5 volts per cm) in the MBR reactor. The results of the experiments showed that applying the electric field in this case improves the characteristics of the wastewater (reducing the concentration of COD, nitrate and phosphate) and reducing the concentration of external polymeric substance (EPS) and soluble material product (SMP) protein. Also, the application of an electric field in MBR reactors reduces fouling and improves the output flux more than the conventional membrane.
Key words: Membrane bioreactor, Electric Field, Biofouling
