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Showing 252 results for hashemi
Volume 24, Issue 2 (February 2024)
Abstract
Composite materials are of great interest due to their exceptional strength, hardness-to-density ratio, high corrosion resistance, and low weight. One of the suitable methods for making composite pipes is using the extrusion process. Extrusion is a plastic deformation process that due to the compressive state of stress in extrusion, materials with low plasticity can be formed by this method. This article deals with the experimental-numerical investigation of extrusion, from various methods of forming process. Extrusion is done on a composite tube using aluminum and magnesium alloys. Aluminum is used due to its strength compared to high weight, excellent malleability, and magnesium due to the lightest structural metal, the lowest density among structural materials, machining, welding and casting capabilities, as well as high specific strength. The mentioned process was tested at different extrusion ratio, temperature and speed, and the effect of different process parameters on the properties of the extruded product was investigated. Then the process was simulated in the software and the experimental results obtained from the laboratory work and the numerical results obtained from the simulation were compared and validated with each other and the error percentage between the graphs of the experimental and numerical results was examined.
Volume 24, Issue 4 (April 2024)
Abstract
Meniscus tears, a prevalent knee joint injury, can significantly hinder joint functionality. Thus, the control of meniscus tears holds significant importance in preserving the joint's regular functionality. A non-invasive approach involves the recommendation of off-loading insoles; which therapists often prescribe based on their clinical experience. Based on the variety of meniscus tear types, it is essential to assess the effectiveness of different insoles when interacting with these distinct tears. This evaluation can be achieved through biomechanical investigations. To address this requirement, the present study utilized medical imaging to establish the precise lower limb geometry. To refine the acquired geometry, both longitudinal and radial tears were applied to the meniscus's geometry. The subsequent phase entails reconstructing the design of three off-loading insole models currently available in the Iranian market. The outcomes of these models demonstrate that the three-layer insole without honeycombs leads to a stress reduction of 1.1% at the apex of the radial tear. When dealing with a longitudinal tear situated on the inner meniscus, the application of a three-layer insole equipped with a honeycomb structure results in a 15% stress reduction. Utilizing a single-layer silicone insole results in an 8% decrease in stress on the external meniscus during longitudinal tears. Hence, the three-layer insole incorporating a honeycomb design is effective for managing longitudinal tears on the inner meniscus. Moreover, the research outcomes indicate that, when comparing the two tear types, longitudinal tears carry a greater risk than radial tears, exhibiting an increased likelihood of worsening.
Volume 24, Issue 4 (10-2024)
Abstract
Friction angle of soil is a critical parameter in the geotechnical engineering and has a direct impact on the design of various structures, such as retaining walls, slopes, and piles. This parameter plays a crucial role in determining the overall safety and performance of these structures, making it a key player in the geotechnical analysis and design. In recent years, there have been some impressive advancements in the field of artificial neural networks and deep learning models. These advancements have transformed these models into the highly effective tools for predicting the properties and behavior of soil. By using a powerful deep learning model, it is now possible to save a considerable amount of time and money when it comes to estimating and predicting soil properties. In this particular study, a convolutional neural network was developed to predict the peak friction angle of Firuzkuh sand using some soil images and the dry density as the input parameters. The network itself consisted of five consecutive convolutional layers, as well as a pyramid pooling module that utilized four different pooling sizes arranged in parallel. In addition, two fully connected layers were incorporated into the network's design, which enabled it to satisfactorily process the input parameters of the images and the dry densities with respect to the speed and precision. This network converts the soil image into a scalar (number) by using these 5 convolutional layers, the pyramid pooling module and a fully connected layer. Then, this scalar is concatenated with the dry density of the soil, is passed through a fully connected layer, and the peak friction angle of the soil is obtained as an output. For data generation, a total of ten samples of Firuzkuh sand were prepared. These samples had different gradation curves, which are referred to as S1 to S10 specimens. Each soil specimen was compacted at three different dry densities. The peak friction angle associated with the 30 different densities for the 10 different particle size distributions (S1 to S10 specimens) was determined using the direct shear test apparatus. The direct shear test box was 100 ×100 × 25 mm in size. For network training and testing, the soil specimens were spread on a flat surface and 50 photos in different light environments with varying distances of the camera from the soil surface, were taken from each specimen. Since in the network training process, three dry densities were considered for each sample, a total of 1500 images were prepared for the network database. Of these, 1125 photos were used for training and 375 photos were saved for testing the network. The network was trained for 1000 epochs on the training data, and the mean square error after 1000 epochs was reduced to 1.84. The outcome of the assessment conducted on the designed convolutional neural network in this study, using 375 test data, revealed that the network can predict the peak friction angle of Firuzkuh sand by incorporating the image and dry density of the soil as input variables. The total normalized relative error was 3.0%, while the maximum normalized relative error was 10%. This indicates that the network has the ability to quickly predict the peak friction angle of the Firuzkuh sand with a good accuracy.
Volume 24, Issue 5 (May 2024)
Abstract
Thermomechanical steels are widely used in oil and gas pipelines due to their high toughness and high resitance against crak growth. A large part of the steel pipelines used in the oil and gas industry in Iran is made of API X65 steel. The fluctuations of internal gas pressure in steel pipes can cause fatigue failure and lead to gas leakage and explosion. So, the control of damage initiation and structural integrity of gas pipelines is of great importance. In this study, the S-N curve and the fatigue strength of the base metal of the API X65 steel were estimated by performing fatigue tests. For this purpose, 24 and 25 test specimens along the seam weld in the coil transverse direction, and perpendicular to the seam weld along the coil rolling direction were prepared according to ISO 1143 standard, respectively. All test samples were cut from an spirally welded pipe with 1219mm outside diameter and 14.3mm wall thickness and were tested on a completely reverse rotating-bending fatigue machine. Statistical analysis of the results was performed by considering the normal logarithmic distribution. The mean curve, characteristic curve, and confidence interval of the results were obtained both in the finite fatigue life range and in the fatigue resistance. The mean endurance limit of the base metal perpendicular to and parallel to the seam seam were 305 and 291 MPa, respectively which were in the range of 0.4 to 0.6 of material tensile strength and above the seam weld endurance limit (258 MPa).
Volume 24, Issue 12 (December 2024)
Abstract
Biogas is a low-calorie fuel comprises 50-70% methane and 30-50% carbon dioxide, with small amounts of other particles. Combustion of low-calorie fuels often involves significant challenges related to flame stability in most burners. Combustion of porous media is an effective method of directing flame heat to the input mixture, which can increase flame stability. In most studies, biogas has been used in experimentaly work or numerical simulation with simple geometry. In this paper, researchers simulate a two-layer porous burner with biogas fuel, based on an experimental design, in two dimensions. They evaluate the effect of the burner geometry, which was not investigated in previous researches, on the temperature distribution and the radiation efficiency. The results show that reducing the amount of carbon dioxide increases the burner surface temperature. Additionally, changes in the interface of the porous layers, simulated in two conical and spherical forms in two converging and diverging states, cause changes in the place of flame, the maximum combustion temperature, the temperature of the burner surface, and the radiation efficiency. The maximum combustion temperature and the maximum burner surface temperature occur for the conical geometry in convergent mode. Increasing 10% of carbon dioxide in the biogas fuel reduces the radiation efficiency by 25% on average. The radiation efficiency of the divergent burner is more than the convergent mode, about 37% for conical geometry and about 25% for spherical geometry. The maximum radiation efficiency is achieved when the burner is divergent and the amount of carbon dioxide is 30%.
Volume 25, Issue 2 (Spring 2022)
Abstract
Introduction: Decellularizing testis tissue and recellularizing with spermatogonial stem cells (SSCs) seems to be a promising approach to restore fertility in prepubertal boys who undergoes cytotoxic therapies.
Method: Testis tissue decellularization was performed by adding 1% SDS and confirmed by histological analysis and DNA quantification. The MTT assay was performed for biocompatibility analyses. SSCs were derived from male mice and cultured in αMEM medium for two weeks. Expanded SSCs were seeded onto the DTM scaffold. The recellularized DTM scaffold disc was cultured in a static cultivation system for one week, then transferred in a dynamic mini-perfusion bioreactor for two weeks. The expression of Id4, Plzf, Gfrα, Prm, Sycp3, ABP, Ki67, Bax, and Bcl2 genes were assessed in SSCs and recellularized DTM after static and dynamic cultivations.
Result: DNA qualification indicated that approximately 99% of the DNA components were removed from DTMs. Hematoxylin-eosin, Masson's trichrome, and DAPI staining confirmed the effective recellularization. Dynamic cultivation of recellularized DTMs at the flow rate of 10 ml/h provided optimum conditions. The expression of SSCs-specific genes of Id4, Plzf, and Gfrα-1 and post-meiosis genes of Scp3, prm1, and ABP was insignificantly higher in the DTMs group than in the control group. Ki67 expression was shown no difference between groups. An insignificant lower expression of the Bax and higher expression of Bcl2 genes was detected in the DTMs group compared to the control.
Conclusion: Our results indicated that SSCs could successfully be attached to the DTMs and effectively proliferate in the mini-perfusion bioreactor.
Volume 25, Issue 3 (5-2023)
Abstract
Three different levels of biochar addition in soil (0, 1, 2 kg m-2) and simultaneous irrigation treatments (50, 85, and 120% of crop Evapotranspiration (ETc)) were applied to basil (Ocimum basilicum L.) for two consecutive years (2018 and 2019). Central Composite Design (CCD) was used as an experimental optimization method, and 13 given experiments were carried out. The study was performed at the research farm of the Ferdowsi University of Mashhad, Iran. The effects of these treatments were evaluated on biochemical attributes (total chlorophyll, total phenol, and total soluble carbohydrates) and morphological criteria (biological yield, height, seed yield, and harvest index). Then, all the results were statistically analyzed. The results revealed that biochar amendment in the soil decreased all examined biochemical characteristics. Meanwhile, biochar in the soil strengthened the morphological properties of the basil plant. Also, the basil plant significantly responded to the amount of irrigation levels. High levels of water treatments reduced total phenol and total soluble carbohydrates and raised all other measured factors. Statistical analysis shows no significant relationship between 2-way-interaction (biochar×irrigation) and measured factors, except total soluble carbohydrates.
Volume 26, Issue 4 (Fall 2023)
Abstract
Introduction: Gentamicin (GM) is a widely used aminoglycoside antibiotic. The nephrotoxicity of gentamicin causes reducing renal blood flow via vasoconstriction. Given PGE2's vasodilatory effects and the mechanisms of tissue damage in GM-induced nephrotoxicity, such as vasoconstriction, the aim of this study was to investigate the protective role of PGE2 in GM-induced nephrotoxicity. The diclofenac sodium was used to assess the direct effects of exogenous PGE2 by blocking endogenous production.
Materials and methods: The experiment was conducted on 56 male Wistar rats (200–250 g). Renal nephrotoxicity was induced by intraperitoneal (i.p.) injection of gentamicin (100 mg/kg). The therapeutic effects of PGE2 (0.2 µg/kg) and diclofenac (0.5 mg/kg) were assessed. The rats were placed in individual metabolic cages to collect urine. The systolic blood pressure and renal blood flow were measured. Levels of urea, creatinine, sodium, potassium, magnesium, and osmolarity were analyzed in plasma and urine samples. The left kidney was used for histological analysis.
Results: Administration of gentamicin for eight consecutive days resulted in a significant increase (p<0.001) in serum creatinine, blood urea nitrogen (BUN), absolute sodium excretion (UNaV), and fractional excretion of sodium and potassium (FENa and FEK), while creatinine clearance, urine osmolarity, and renal blood flow significantly decreased (p<0.001) compared to the control group.
Treatment with PGE2 significantly reducing serum creatinine, UNaV, FENa, FEK (p<0.001), and BUN (p<0.05), while significantly increasing creatinine clearance, urine osmolarity, and renal blood flow (p<0.001).
Conclusion: Prostaglandin E2 provided substantial protective effects against gentamicin induced acute nephrotoxicity in rats.
Volume 28, Issue 1 (Winter 2025)
Abstract
Introduction: Diazinon is an organophosphate pesticide that has widespread applications in both agriculture and household settings. Diazinon poisoning can have detrimental effects on the cardiovascular, gastrointestinal, and central nervous systems. The aim of this study was to investigate the effects of chronic exposure to diazinon on histological features of the liver and kidney of rats.
Materials and Methods: Twenty adult male Wistar rats, aged 10 - 12 weeks and weighing 150-200 grams, were purchased and divided into two groups of 10. In the treatment group, diazinon was administered at a dose of 20 mg/kg/day to each animal for 3 months, while the control group was maintained on a normal diet and drinking water. After 12 weeks of exposure, the animals were prepared for H & E staining, and the samples were examined under a light microscope.
Findings: The structural integrity of the liver and kidney was preserved in the diazinon-treated group compared to the control group, but mild effects of diazinon were observed in the liver tissue, such as foci of inflammation and hyperplasia of Kupffer cells, and in the kidney, such as the presence of epithelial cells in the distal tubule and cell detachment from the basement membrane.
Conclusion: Based on the results of this study, the rats exposed to diazinon did not show significant changes in histological features in the liver and kidney, and these changes were subtle, possibly indicating a need for higher doses or longer exposure durations to diazinon.
Volume 28, Issue 2 (4-2021)
Abstract
Almost all Islamic classical movements believe that the main task of women is motherhood and housekeeping. However, from the perspective of new Salafist groups, there have been transformations in women’s rights and duties. Studying the political and social role of women from the new Salafist point of views and comparing them with the views of old Salafists was because the issue was unexplored. This paper investigates differences between the perspective of the new and old Salafists regarding the role of women, through examining primary resources such as the works of old and new Salafist ideologues, as well as secondary sources susch as magazines, manifesto, tweets, and websites. Based on the critical discourse analysis, this paper concludes that both the new and old Salafist groups shared the same theological sources and references, but the old ones have a literal (and not a contextual or interpretative) reading of the holy book (the Qur’an) and the Sunna as their fundamental resource and reference. In the new Salafist discourse, women have the right to participate in all social and military activities. Therefore, the big shift created in terms of social and political participation of women through new Salafists is based on new circumstances, ambitions as well as their different understanding and interpretation of theology concerning the role and duty of women.
Volume 31, Issue 2 (5-2024)
Abstract
The rules in the family are the creators of legal relationships, and the implementation of the legal orders is the basis for the organization of the affairs. Sometimes due to the situation where the rights of the family to the spouses are recognized, the parties to each other do harm and use their rights inappropriately and, namely, abuse their rights. In the present paper, using the descriptive-linguistic method, the non-financial rights in spousal relationships and the possibility of their abuse have attracted greater attention. In addition, the explanation of the orientation of the teachings of Islam regarding the abuse of non-financial couples' rights and its prohibition without providing a guarantee of implementation is discussed, which constitutes it among the moral recommendations; the need to develop and determine the guarantee of effective implementations to prevent the abuse of non-financial rights and to control the exercise rights for the realization of the legislator’s goal and the realization of justice in the relationships of couples has been examined and proved, and for certain reasons such as the rule of no loss, the principle of expediency, the rule of maintaining the system (social system) and determining the punishment by the government has been referred to prove the point.
Volume 31, Issue 3 (8-2024)
Abstract
Modernist literature decidedly experiments with such modes of discourse representation as free indirect discourse (FID) to highlight the subjective nature of reality and reflect the estrangement of the modern subject. Accordingly, an analysis of discourse representation has proved to be integral in exploring Modernist narratives. The discourse representation in movies, however, has received little attention from film narratologists. After an overview of discourse representation in literature and film, the present paper examines Virginia Woolf’s modernist masterpiece Mrs Dalloway (1925) and its cinematic adaptation of the same title by Marleen Gorris (1997) and its interconnectedness to present characters’ subjectivities. The basic claim of this study is that the (free) indirect discourses of the novel are turned into free direct discourse in the movie using the technique of internal sound or flashback. Although there are instances of internal focalisation in this movie, they are so disjointed or short that the dominant discourse remains that of the narrator. Therefore, the findings of the present essay demonstrate that Gorris’ film is not creative enough to bring about effects equal to or beyond those produced by Woolf’s or reproduce the underlying forces of “difference” at play in Woolf’s text.