Showing 24 results for Malekzadeh
Volume 3, Issue 2 (, (Articles in Persian) 2012)
Abstract
With the advent of the World War ІІ, foreign language teaching entered a new period of its tempestuous history. The purpose of most foreign language schools and institutes in this period and the forthcoming years was to enable communication via a foreign language and, at the center of this skill, there was an attention to proper pronunciation of sounds and words. Since that time, there has been a great number of ideas and viewpoints proposed by researchers and authorities about the nature of pronunciation teaching, each of which contributed to the expansion of this field. In order to discover how these ups and downs have affected the teaching, of foreign language pronunciation in Iran, large-scale and comprehensive research is needed. The aim of this article is to inspect the place and the method of pronunciation teaching in high-school English textbooks in Iran in order to figure out the quality of teaching pronunciation and the way it is presented in the textbooks. The findings of this study are useful to improve the quality of teaching pronunciation in high-school English textbooks. Finally, some recommendations have been given.
Volume 8, Issue 1 (4-2017)
Abstract
Due to the wide applications of gold nanoparticles, there have been great demands for their synthesis recently. Chemical methods produce pure and Non-dispersive nanoparticles, but these are quite expensive and potentially toxic to the environment. It has been suggested that the use of biological organisms and their components could be a suitable alternative for the production of nanoparticle in an eco-friendly manner (green synthesis). Using plant extracts for nanoparticle synthesis can be advantageous over other biological processes because it eliminates the elaborate process of maintaining cell cultures and can also be suitably scaled up for large-scale synthesis. In this study leaf extracts of Water cress, were used for green synthesis of gold nanoparticles. Gold nanoparticles were formed by treating an aqueous HAuCl4 solution by different amount of plant leaf extract as reducing agent at different temperatures. UV–visible spectroscopy was used for monitoring of the reaction progress. The synthesized gold nanoparticles were characterized with Dynamic light scattering (DLS) size analyzer, Transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). The results show that only a few minutes were required for the synthesis of gold nanoparticles at 60 °C and 80 °C by 1000 μl of plant extract, suggesting appropriate reaction rates in comparable to those of nanoparticle synthesis by chemical methods. TEM images showed that spherical nanoparticles (size, 10–50 nm) were obtained at higher temperatures and leaf broth concentrations. The analysis of FTIR bands show that the Polysaccharides and proteins are probably involved in the bio reduction and synthesis of nanoparticles.
Volume 9, Issue 3 (Summer 2018)
Abstract
Aims: Sunflower (Helianthus annuus L.) is mainly cultivated for the extraction of edible oil, and Sclerotinia sclerotiorum is a pathogen in sunflower fields. The aim of this study was to indetify markers associated with resistance to Sclerotnia Scleritiorum diseases in sunflower, using association analysis.
Materials and Methods: In the present experimental research, a population including 100 lines of oily sunflower was cultivated. Traits such as contamination progress after 4, 8, and 12 days, 100 seeds weight of contaminated and non-contaminated plants, contaminated and non-contaminated plant yield, 100 seeds weight loss, and yield loss were studied. The molecular profiles of germplasm were prepred with 30 microsatellite primer pairs. Genetic structure analysis of population was performed based on Bayesian model.
Findings: The highest coefficient of variation was related to the yield loss (86.41%) and weight loss (78.48%), and the lowest was contamination progression after 8 and 12 days (26.47% and 20.44%), respectively. Based on the mixed linear model (MLM), 6 microsatellite markers related to traits were identified at the level of p≤0.01. The highest number of markers was associated with contamination progression after 8 days. The P733, P807, and P1256 markers were simultaneously associated with 3 traits.
Conclusion: Four lines including RHA274, H100A-83HR4, B45-03, and Iranian line with code 28 were identified with different genetic origins and high resistance levels. According to the general linear model (GLM) and MLM, 24 and 15 SSR markers are related to the traits, respectively. The P733, P807, and P1256 markers are simultaneously associated with 3 traits.
Volume 10, Issue 0 (بهار 86- 2008)
Abstract
Objectives: Tissue homeostasis is the result of strict regulatory mechanisms, which control self-renewal, differentiation, prevention of premature senescence and apoptosis of stem cells. Bmi-1, a Polycomb group repressor protein, represses genes that induce cellular senescence and cell death, and can contribute to cancer when improperly expressed.
Material and methods: Bladder tumoral and nontumoral samples were collected from Labbafi-Nejad hospital. RNA was extracted from each sample, reverse transcribed and amplified by RT-PCR technique, using specific primers for Bmi-1 and β2-microglobolin, as an internal control. The production and distribution of Bmi-1 protein was also examined by western blotting and immunohistochemistry technique.
Results: To clarify the role of Bmi-1 in bladder tumors, we examined the expression of Bmi-1 in tumoral and nontumoral samples. RT-PCR generated a 683 bp product, corresponding to the expected size of the Bmi-1 amplified region. The identity of the amplified fragment was then confirmed by direct DNA sequencing. The mean of expression of the Bmi-1 detected in tumoral tissues was significantly higher than the non-tumoral tissues and there is also a significant correlation between the mean of gene expression with stage of malignancy
(p < 0.05). The expression of Bmi-1 at protein level was further confirmed by western blotting and immunohistochemistry.
Conclusion: The tumor suppressor locus Cdkn2a (Ink4a/Arf locus) codes for two proteins, p16ink4a and p14arf. Ink4a and Arf are playing important roles in the retinoblastoma (pRB) and p53 pathways, respectively. Bmi-1 is a potent repressor of both pathways and hence elucidating its role in tumorigenisis is very important. Here, for the first time we are reporting the expression of Bmi-1 and its correlation with malignancy in bladder tumors.
Volume 12, Issue 4 (Fall 2024)
Abstract
Aims: Hypertension is a critical health condition requiring consistent medical adherence to prevent complications. This study aimed to evaluate the effects of a cardiovascular risk assessment and an educational intervention grounded in the Health Belief Model (HBM) on medication adherence among patients with hypertension.
Materials & Methods: A semi-experimental study was conducted with three groups: a combined risk assessment and education group, a risk assessment-only group, and a control group, each consisting of 40 patients. Cardiovascular risk was individually assessed in both intervention groups using the Framingham model, with risk categories (low, moderate, high) explained to personalize the intervention and enhance perceived susceptibility. Additionally, patients in the combined intervention group received an educational booklet structured around HBM components. All participants completed questionnaires measuring knowledge, HBM constructs, the Morisky Medication Adherence Questionnaire, and treatment compliance (measured by the ratio of consumed to prescribed medications) at baseline and after three months. Data analysis was performed using SPSS software version 26.
Findings: The three groups were demographically comparable. Over time, the combined intervention group showed significant improvements in all HBM constructs. The risk assessment-only group demonstrated improvements in perceived barriers, perceived benefits, self-efficacy, and awareness. Both intervention groups exhibited enhanced treatment compliance and medication adherence compared to the control group.
Conclusion: The combined educational and risk assessment intervention proved more effective in improving awareness and strengthening HBM constructs than risk assessment alone.
Volume 14, Issue 1 (4-2014)
Abstract
Dynamic response of fully-clamped laminated plate subjected to small mass and low-velocity impact studied in this paper by using the suitable Algebraic Polynomials and Galerkin method. The first-order deformation theory as well as the displacement filed is used to solve the governing equations of the composite plate analytically. The interaction between the impactor and the target are considered in the impact analysis. This interaction is modeled with the help of a two degrees-of-freedom system, consisting of springs-masses. The results indicated that some of parameters like mass and velocity of the impactor in a constant impact energy level, mass of the plate (target), increasing the length-to-width ratio of the plate (a/b ratio) and orientation of composite fibers of plate are important factors affecting the impact process and the design of structures.
Volume 14, Issue 13 (First Special Issue 2015)
Abstract
In this paper, the free vibration and low velocity impact response of a sandwich plate with a Magneto Rheological (MR) flexible core have been studied. The rectangular sandwich plate contains a Magneto Rheological (MR) flexible core and two constrained layers. The MR materials have different properties with respect to different magnetic field intensities. The governing equations of motion have been derived using Hamilton principles. The solution of these equations was obtained using Fourier series and analytical systematic procedure. Using the proposed solution method, the natural frequencies, structural loss factors, impact load and transverse deflection of the plate were calculated. Also, the contact force history was derived using a two degrees of freedom spring mass model analytically. The effects of variations of magnetic field intensity on the natural frequency, loss factors, contact force and deformations of the plate and impactor were investigated. In ordre to calculate the equivalent mass of the plate, the obtained fundamental natural frequency from solution of eigen value problem was used. The obtained equivalent mass of the plate was used in analytical spring mass model. The results show that with systematic variation of magnetic field, the magnitudes of transverse stiffness, structural loss factors and maximum contact force can be changed and controlled, respectively.
Volume 14, Issue 15 (Third Special Issue 2015)
Abstract
In this study, single-objective and multi-objective optimization of curved sandwich panel with composite face sheets and magneto-rheological core have been done to maximize the first modal loss factor and minimize the mass by using genetic algorithm. The studied sandwich panel was curved with simply support boundary condition. In order to derive the governing equations of motion, an improved high order sandwich panel theory and Hamilton's principle were used for the first time. The face sheet thickness, core thickness, fiber angles and intensity of the magnetic field have been considered as optimization variables. In single-objective optimization, the optimized values of variables were calculated. The results showed that the structures tend to have thick core and thin face sheets which seems physically true. As the magneto-rheological fluid placed in the core, it has a significant effect on the increasing of the modal loss factor. For the multi-objective optimization the Pareto front of optimal technique was presented. Then for the first time at this field, the set of optimal points are selected based on TOPSIS method and it was showed that in the case of similar size and mass, modal loss factor of double-curved panel is more than sigle-curved.
Volume 14, Issue 15 (Third Special Issue 2015)
Abstract
In this paper, the effect of the reaction wheel dynamics as controller actuator in multi axis attitude maneuver of a 3D nonlinear flexible spacecraft is considered. In modeling of the actuator dynamic, friction, inertia and electrical subsystems are considered. The nonlinear robust control approach is composed of dynamic inversion and µ-synthesis schemes. To overcome the non-minimum phase characteristics, the controllers are designed by utilizing the modified output re-definition approach. In the design of controllers actuator saturation is considered. It is assumed that only three reaction wheels in three directions on the hub are used. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. In the disturbance modeling all terms such as constant, sinusoidal and impulse are considered. Simulation results show the effects of actuator dynamics and confirm the ability of the proposed controller in tracking the attitude trajectory while damping the panel vibration.
Volume 15, Issue 1 (3-2015)
Abstract
In this article, the physical and Geometrical effective parameters on free vibration and Force impact a three-layer sandwich plate in the middle layer with magneto rheological (core) Under cross-shot with low speed is investigated. The first natural frequency and loss factor of comparable modal for the first four vibrative modes for Core thickness, magnetic fields and different sheet’s geometrical parameters, is founded. The MR material shows variations in the rheological properties when subjected to varying magnetic fields. These materials with fast response time (in milliseconds) Through a detailed with variation in Magnetic field can be controlled. The governing equations of motion were obtained using Hamilton̕s principle. The results were obtained by the systematic analytical solution. Using the two degrees of freedom mass-spring model, the contact force function can be obtained analytically. The obtained natural frequency from eigen value problem, was used for calculating of equivalent mass of the plate in spring mass model. The results show that with systematic variation of magnetic field and with increasing the ratio of core thickness to the layer thickness and also with increasing the ratio of length to the whole of sheet thickness, we can in order, the stiffness, structural loss factor coefficient and maximum contact force can be changed and controlled.
Volume 15, Issue 3 (5-2015)
Abstract
This paper talked about spacecraft formation flying control. Leader-flower structure is used in formation flying. A non-linear PID controller is designed based on predictive control. The formation relative equation is obtained from nonlinear Hill equation. First, the frequency control is achieved with the using of predictive control algorithm. In control frequency, disturbances have been replaced from disturbance observer. Equations are rewritten in the form of PID gains. Stability of the closed-loop system is proven by closed-loop error dynamics. Nonlinear PID controller performance in the pursuit of desired arrangement has been tested in simulations. Also effects of various factors on the quality of controller results are studied. It is shown that choosing predictive horizon time and disturbance observer gains have the most effect on system response. It is shown that if predictive time increase the settling time increase and the control effort decrease. if disturbance observer gain increase from a limit, it has no effect on settling time but control effort increase. As shown in simulation, the tracking response show the controller method ability. the simulation show the ability of this nonlinear control method in tracking.
Volume 15, Issue 8 (10-2015)
Abstract
In this paper, the spacecraft formation flying using virtual structure algorithm is studied. In spacecraft formations flying, several small spacecraft have been used instead of employing a single one to achieve the same goal. In virtual structure method, the position and orientation of each spacecraft is measured with respect to the position and attitude of a virtual node in every moment. Two robust control methods are proposed to control formation. At first, the robust μ synthesis controller is used to attenuate the influence of the sensor noises, environment disturbances and parametric uncertainties but it is done with heavy computations. The second method is in the standard form of optimization problem. It is composed of state feedback controller and lyapanov stability theory. The LMI controller Computations are very efficient and the controller is robust against parametric uncertainties and most of the disturbances. The implementations of control methods on virtual center guarantees robust stability and performance. Concerning with Actuator constraints, Simulation example is provided to show the effectiveness of the proposed control schemes to track the desired attitude and position trajectories despite system uncertainties.
Volume 16, Issue 7 (9-2016)
Abstract
This study dealt with the flutter and biaxial buckling of composite sandwich panels based on a higher order theory. The formulation was based on an enhanced higher order sandwich panel theory that the vertical displacement component of the face sheets were assumed as quadratic one while a cubic pattern was used for the in-plane displacement components of the face sheets and the all displacement components of the core. The transverse normal stress in the face sheets and the in-plane stresses in the core were considered. For the first time, the continuity conditions of the displacements, transverse shear and normal stress at the layer interfaces, as well as the conditions of zero transverse shear stresses on the upper and lower surfaces of the sandwich panel are simultaneously satisfied. The aerodynamic loading was obtained by the first-order piston theory. The equations of motion and boundary conditions were derived via the Hamilton principle. Moreover, effects of some important parameters like lay-up of the face sheets, length to width ratio, length to panel thickness ratio, thickness ratio of the face sheets to panel, fiber angle, elastic modulus ratio and thickness ratio of the face sheets on the stability boundaries were investigated. The results were validated by those published in the literature. The results revealed that by increasing length to width ratio, length to panel thickness ratio and elastic modulus ratio of the face sheets, the stability boundaries were decreased and the largest nondimensional buckling load was occurred at the angle ply sandwich panel.
Volume 16, Issue 7 (9-2016)
Abstract
In this paper optimized the arrangement of the fiber metal laminate for cylindrical shells to achieve the maximum natural frequencies. In order to maximize the FML shell natural frequencies the sequence of the composite –metal layers and fiber orientation are changed frequently and for each case, the sample natural frequency is calculated. Finally FML shell with maximum natural frequencies is found. Hamilton‘s principle and energy method is used to define the equation of motion and First order shear deformation theory (FSDT) is utilized for vibration analysis in the shell’s equilibrium equation .In order to solve free vibration problem the double Fourier series is used to obtained the eigenvalue problem. For this purpose, through a MATLAB program linked to the finite element software of ABAQUS .different shells with various layer sequence and fiber orientation are created and studied from optimization aspect. This comprehensive program is able to analyses the FML shells with various arrangements of composite –metal layers, fiber orientation and boundary condition. The simply-simply and clamp-clamp boundary conditions are applied on edges. The applicable fiber orientations are 0,30,60,90 degrees.
Volume 16, Issue 9 (11-2016)
Abstract
In this paper, the behavior of curved sandwich beam with a soft flexible core, under low-velocity impact, loaded with environmental thermal effects by pursuing the use of the high order shear deformation theory of sandwich structures is investigated. The Sandwich beam is comprised of composite sheets and foam core. The boundary condition is simply supported by probability of circumferential deflection. Two degrees of freedom for mass- spring model was used for modeling the impact phenomena. In the presented formulation, the first order of shearing deformation theory is used for sheets,the core Displacement field is considered unknown and then by using elasticity theory and compatible condition in the core, sheets common face and the relation of stress-strain core deflection are determined. In order to derive the governing equations of beam structure, the Hamilton principle was used. For validation, the results obtained from this research are compared with the results of other researchers and also the numerical result of ABAQUS software. The comparison of results shows good agreement. The effects of various parameters like impact velocity and mass, environmental temperature, core and sheets thickness and materials on core and sheets deflection and core stress and impact force were studied. The obtained results showed that increasing environmental temperature has a slight effect on impact force, but more effect on beam dynamic response. It is also shown that with increasing the hardness of beam, the energy absorption is reduced.
Volume 16, Issue 12 (2-2017)
Abstract
One of the common ways to reduce vibration in the structures is to add a thin viscoelastic material layer to the structure. By appropriate using of viscoelastic materials one may increase modal loss factor of the structure and reduce unfavorable structural vibration which is a main cause of fatigue and failure in the structures. In this paper, low velocity impact response of sandwich plate with magnetorheological fluid core is investigated. Hamilton principal is used to obtain the governing equation of motion for sandwich plate. Free vibration problem of the sandwich plate is solved using the Navier solution method. Classical lamination theory is used to analyze the mechanical behavior of the composite laminate in the facesheets. Only shear strain energy of the core is considered and viscoelastic behavior of the MR material was described by complex shear modulus approach as a function of magnetic field intensity. Furthermore, analytical solution for impact force is obtained by a two degree of freedom spring mass model. For three different stacking sequence of face layers, contact for history and variation of maximum impact force and it’s corresponding time by magnetic field intensity is investigated. The results show considerable effect of variation in magnetic field intensity on maximum impact force and it’s corresponding time.
Volume 17, Issue 3 (5-2017)
Abstract
In this paper, the behavior of free vibrations and buckling of the thick cylindrical sandwich panel with a flexible core and simply supported boundary conditions using a new improved high-order sandwich panel theory were investigated. An axial compressive load is applied on the edges of the top and bottom face sheets simultaneously. The formulation used the third-order polynomial description for the displacement fields of thick composite face sheets and for the displacement fields in the core layer based on the displacement field of Frostig's second model. In this model, there are twenty seven degree of freedom. The transverse normal stress in the face sheets and the in-plane stresses in the core were considered .For calculated exact solution, according to thick face sheets, all of the stress components were engaged. The equations of motion and boundary conditions were derived via the Hamilton principle. Moreover, the effect of some important parameters such as those of thickness ratio of the core to panel, the length to radius ratio of the core, cumferential wave number and composite lay-up sequences on free vibration response and buckling of the panel were investigated. In order to validate the results, the obtained results were compared with those obtained using finite element ABAQUS software. The advantage of this paper is simplicity, considering face sheets as thick, exact solution and the considering of important terms such as (1+z_c/R_c ) in equations.
Volume 18, Issue 2 (4-2018)
Abstract
In this study, the strain ratcheting behavior of piping branch under the influence dynamic bending moments are evaluated. The Chaboche nonlinear kinematic hardening model and combined Armstrong-Fredrick model with isotropic rule are used to predict the plastic behavior of the piping branches. The results of FE method by using the hardening models have been compared with the results of the experimental method and Armstrong-Fredrick kinematic hardening results. The constant parameters of the hardening model and stress-strain data have been obtained from several stabilized cycles of specimens that are subjected to simulated seismic bending cycles. Both the FE and experimental results showed that the maximum strain ratcheting occurred on the flanks in the piping branch hoop stress direction just above the junction. The ratcheting strain rate increases with increase of the dynamic moment levels. The FE results show that initial rate of ratcheting is large and then it decreases with the increasing of loading cycles. In BMS1 sample, the FE hoop strain ratcheting data by using chaboche nonlinear kinematic hardening model comparing with the other hardening models to be near that found experimentally values. In BMS2 and BMS3 components, the FE hoop strain ratcheting data by using chaboche nonlinear kinematic hardening model and combined hardening model comparing with the A-F hardening model to be near that found experimentally values. The hoop strain ratcheting rate by Armstrong-Fredrick model gives overestimated values comparing with the experimental data.
Volume 18, Issue 74 (12-2021)
Abstract
This research seeks to answer the question, what are the semantic foundations in Attar's mystical aesthetics. To answer this question, In style Analytical and descriptive first the basics, beauty, aesthetics and cognition were defined according to philosophical and artistic books. After that, due to the indefinability of beauty, its components were discussed. The semantic foundations of aesthetics in Islamic mysticism include three categories of semantic foundations, epistemology and ontology. In this research, aesthetic semantics has been studied in four works of Attar. The first basis is the definition of beauty in mysticism and from Attar's point of view, which includes the whole universe. Because the world of Nasut is the mirror of the world of divinity and all is a. reflection of divine light. The second basis is the criteria of beauty, and at least eight of Attar's aesthetic criteria were explained. According to it, it can be said that the main basis for recognizing beauty from Attar's point of view is paying attention to God. That is, to reach metaphysics and the source of goodness with the apparent senses of the physical world with the enlightened intellect. And with the tools of the heart and cultivation, to discover the mine of goodness. The third basis is the revelation of the beauties on the screen. The result of inner experience is the discovery of beauty, the creation of joy, hope, astonishment and the joy of understanding time in its discoverer.
Volume 19, Issue 2 (3-2017)
Abstract
The influenza A virus is of global concern for the poultry industry, especially the H5 subtype as it has the potential to become highly pathogenic for poultry and mankind. Recently, plant expression systems have gained interest as an alternative for the production of vaccine antigens. The goal of the present study was to investigate the possibility of expressing the HA1 protein in Nicotiana tabacum via agroinfiltration. In this study, the Hemagglutinin type 1 (HA1) of a high pathogenic avian influenza virus of the H5N1 subtype was synthesized and transiently expressed in Nicotiana tabacum. To examine the possibility of expressing the HA1 protein in N. tabacum, a cDNA fragment encoding the HA1 gene was synthesized de novo, modified with a Kozak sequence, a C-terminal hexa-Histidine (6His) tag, and an endoplasmic retention signal (KDEL). The construct was cloned into vector and the resulting - HA1 plasmid was agro-infiltrated into N. tabacum. The relative gene expression of recombinant plant-produced HA1 was measured by quantitative real-time PCR. Guided by the gene expression profile, HA1 protein was extracted at 3 dpi and subsequently purified utilizing the 6His tag. A recombinant HA1 protein was immunogenically detected by conjugated polyhistidine antibody in western blot, dot blot and ELISA assay. In order to verify the right conformation of HA1 produced in plants, western blot was also done using mouse monoclonal anti-influenza A virus (H5N1/HA1) [2B7]. The results of Real Time PCR assay indicated that the foreign gene was transcribed in transfected leaves. Migration size of protein was detected at 45 kD by Western blotting and demonstrated no discrepancy compared to the positive control (HA1). ELISA results showed that the HA1 was expressed in the transfected leaves in high level as the yield of recombinant protein was 8.8 % of TSP and the yield of purified HA1 was 0.16 g purified protein per kg fresh weight of leaves. This is the first research about the transient expression of the tobacco-made HA1 protein where a synthetic sequence was used for its expression. Here, the efficacy of agro-infiltration for expression of HA1 antigen in tobacco was illustrated. Agro-infiltration expedites the process of recombinant antigens expression in plant tissues. Accordingly, our results provide great opportunity for the exploration of transiently plant-manufactured HA1 as vaccine candidate.