Showing 7 results for Mosadegh
Shadi Mosadegh, Hamid Abtahi, Jafar Amani, Shohreh Zare Karizi, A.h. Salmanian,
Volume 13, Issue 4 (1-2023)
Abstract
Background: Shigella and Enterohemorrhagic Escherichia coli are among the most common causes of bacterial diarrhea, and no effective vaccine candidate for these bacteria have approved yet. Due to the role of IpaD protein and Shigella enterotoxin B subunit (StxB) in Shigella and E. coli O157: H7 pathogenicity, STX1B-IpaD chimeric protein can be used as a suitable molecule to produce a recombinant vaccine candidate. This study aimed to clone, express, and purify STX1B-IpaD chimeric protein to develop an effective vaccine candidate against Shigella and E. coli O157: H7 species. Materials and Methods: IpaD gene with NdeI and BamHI restriction enzyme sites was isolated from a recombinant vector and subcloned into the pET28a -STX1B expression vector. Vector was transferred to E.coli strain Rosetta (DE3) and confirmed by PCR and restriction enzyme digestion. SDS-PAGE and western blotting were used to confirm the recombinant protein. The recombinant STX1B-IpaD protein was purified by affinity chromatography, and its concentration was measured by the Bradford method. Results: The PCR and restriction enzyme digestion showed the accuracy of the gene cloning. The protein electrophoresis showed the proper expression and correct molecular weight (27 kDa) of STX1B-IpaD. The western blot analysis confirmed the recombinant protein. The recombinant protein concentration was estimated at more than 0.3 gr/L. Conclusion: An effective method for the production of recombinant proteins is codon optimization and effective expression in heterologous hosts. After the immunogenicity in the animal model, this recombinant protein can be used as a chimeric vaccine candidate against EHEC and Shigella bacteria.
Volume 14, Issue 2 (5-2014)
Abstract
Parallel piezo-flexural nanopositioning stages are extensively used in advanced nano-scale imaging and manipulation applications such as scanning probe microscopy systems. One of the major deficiencies of these devices is the coupled motion between their different axes. That is, the motion of stage in one direction interferes with motions in the other directions, leading to undesirable disturbances. In this paper, analytical, dynamic, experimental, and finite element analyses are carried out to investigate the major root cause of the cross-coupling effect. Using ABAQUS FEA software, a 3D model of the stage has been developed. Model consists of a central elastic body connected to the fixed frame through four flexural hinges. A cylindrical stack of multiple piezoelectric layers is placed between the moving central body and the fixed frame. Simulations are carried out for two different friction coefficients in the contact surfaces of the piezoelectric layers, and for different frame materials. It is observed that the main cause of the cross-coupling effect is the rotation of piezoelectric stack due to its friction with the stage moving in the tangential direction, concurrent with a change in the geometry of the stage.
Volume 14, Issue 3 (11-2024)
Abstract
Today, service industries have an basic and important role in economic development of countries. in this regard, the role and importance of insurance industry as a supporting industry is undeniable. on the other hand, increasing competition in the insurance industry has caused most managers of this industry to consider a solution for the permanent presence in business .there is no doubt that the insurance industry is backward from the perspective of technological innovations to other financial services such as banks and stock exchanges. accordingly, this study aimed to investigate the digital marketing in insurance industry (opportunities, challenges and solutions) .in order to achieve the main purpose of the study after doing ten interviews and reaching theoretical saturation, three stages of thematic analysis were used. at the first stage of open coding, all interviews were conducted and then open coding were carried out. so that the data collected in the interviews were written down on the paper, then by analyzing the line to the line and paragraph to the paragraph and paragraph to the paragraph of the existing texts and concepts were created. these concepts were adapted from the writings and in some cases the same way that in total, 49 primary codes were created out of ten interviews. then, due to the multiplicity of codes, all similar elements based on the conceptual and semantic similarity in their own group were classified into 37 sub categories. finally, eight major categories of digital marketing opportunities include customer relationship management, product introduction, cost management, marketing management, and four main categories in the challenges of digital marketing challenges, social factors, legal factors and marketing factors were created.
Volume 14, Issue 13 (First Special Issue 2015)
Abstract
Polishing is considered as the last and most important step in the manufacturing of optical component. Computer control polishing (CCP) methods are usually used to polish complex surfaces. In this method, material removal is controlled at each point, depending on error at that point. In contact polishing mechanism, tool feed rate is often controlled to eliminate local errors. It means that the higher tool feed rate, the lower material removal would be and vice versa. Tool influence function (TIF) which is defined as the instantaneous material removal under the polishing tool for a given tool motion, is the most important parameter in CCP and its predictability during the polishing process leads to reliable result. In this study, a new spherical tool which can polish complex surfaces by using a 3- axis CNC machine is presented. Because of spherical geometry of both tool and workpiece, tool material removal rate is variable because of changing the angle between tool axis and surface normal vector that leads to variation of relative speed. Tool influence function which depends on tool engagement’s angle was modeled based on Pereston equation. Moreover, the simulation is modeled based on discretization of tool path. To evaluate the methodology, some polishing experimental testes were performed. The experimental results show that a 130 mm spherical convex lens with initial surface roughness of 1.114 micrometer for PV was decreased to 395 nm for PV using the CCP method developed in this study.
Volume 16, Issue 3 (10-2016)
Abstract
The two most common causes of embankment failure are embankment overtopping and internal erosion. Internal erosion of soil resulting from seepage flow is the main cause of serious hydraulic work (dykes, dams) failure, in terms of the risk of flooding areas located downstream. The erosion characteristics are described by the Erosion Rate Index, which measures the increase of erosion rate with respect to an increase in the hydraulic shear stress; and the Initial Shear Stress, which represents the minimum hydraulic shear stress when erosion starts. Values of the Erosion Rate Index span from 0 to 6, indicating that the changes in erosion rates in response to changes in hydraulic shear stress can differ by up to 106 times across different soils. Coarse-grained, noncohesive soils, in general, erode more rapidly and have lower Initial Shear Stresses than fine-grained soils. The challenge in predicting failure due to internal erosion is characterizing the material properties relevant to the rate of failure. Therefore, it is very important to improve the erosion resistance of soils using appropriate and cost effective techniques. In order to control internal erosion and treated erodbile soil, important point is use of modern stabilizers instead of traditional stabilizers which is harmful. In this study, polyvinyl acetate polymer material has been used for treatment erodibility of kaolinity clay sand. To conduct this research, kaolinity clay sand has been treated with different percentages of polyvinyl acetate polymer and it has been tested with hole erosion apparatus in different hydraulic gradients. The hole erosion test (HET) is one of several available procedures for characterizing the erodibility of cohesive soils that might be susceptible to internal erosion investigations of dams and levees. It was first developed in a constant-flow configuration (Lefebvre et al. 1984) and more recently in a constant-head configuration by Wan and Fell (2004). The HET utilizes an internal flow through a hole pre-drilled in the specimen, a flow condition similar to that occurring during piping erosion of embankment dams. In the constant-head configuration, the test head is typically doubled, starting from 50 mm, until progressive erosion of the pre-drilled hole is produced. Measurements of accelerating flow rate through an eroding pre-drilled hole in a test specimen yield estimates of the critical shear stress and erosion rate coefficient. The initial and final eroded hole diameters are used to compute initial and final friction factors, and intermediate hole diameters are then computed from flow rates measured during the course of the test. The result showed that erosion rate of kaolinity clay sand is extremely rapid and polyvinyl acetate polymer stabilizer increased the resistance of kaolinity clay sand to erosion. It was also found that with the addition of polyvinyl acetate polymer and its description has been changed from extremely rapid to moderately slow erosion. While adding polyvinyl acetate polymer kaolinity clay sand caused the increase 60 percent unconfined compression strength.
Volume 17, Issue 2 (3-2017)
Abstract
In this paper, fracture behavior of functionally graded material weakened by U-notches under mode I loading has been investigated. Electro slag remelting process has been used to produce functionally graded specimens in a notch arrester configuration. Hardness test has been utilized to define the position of each layer. Mechanical properties, including elastic modulus and poisson's ratio, vary along the width of U-notched specimens. The critical fracture load (Fcr) was achieved by performing three point bending examination and using force-displacement curve.
Then, the process simulation was done by finite element software. Firstly, Jcr of each specimen was calculated by using critical value of strain energy averaged over a well-defined control volume. Then the critical fracture load was evaluated by means of the J Integral criterion. In this research, the effect of the notch root radius, for a fixed notch depth, on the Jcr value as well as the critical fracture load has been studied. To compare fracture behavior of the FG specimens with the corresponding homogeneous ones, have the same properties with the notch root layer in FG specimen, Fcr and Jcr value of each have been investigated. The average difference between the predicted Fcr by J integral criteria and experimental results is 17.84%. Finally, the effect of number of graded area layers on Jcr and Fcr has been investigated. The results shows, the value of Jcr and Fcr do not be affected while the number the number of layers more than 20.
Volume 17, Issue 12 (2-2018)
Abstract
This study investigates the effect of injection parameters on the geometric and optical quality of a Bi-convex lens injected with PMMA polymer. An important part of this research is the effect of each parameter on the geometric and optical quality of the lens and the obtaining of optimal quantities for injection. According to the results of this study, the effective factors simultaneously on the geometric quality and the optical quality of these types of lenses are melt temperature, packing time, injection pressure and packing pressure, respectively. These factors indicate that the simultaneous control of the pressure, in the mold cavity both during the injection and at the packing stage, can represent a suitable injection with minimal optical errors. According to the collected data, the average volumetric shrinkage check is 5.847% singly, in this case the refractive index is equivalent to 7.12E-05. The refractive index analysis is 6.28E-05 singly. In this case, the minimum average volume contraction is 9.1%. Therefore, optimizing and minimizing one of the geometric or optical factors will not produce the proper values of the other factor. Using the multi response Taguchi method, is obtained the minimum average volumetric shrinkage is 5.503% and the minimum refractive index is 6.96E-05.
