Showing 7 results for yaghmaei
Volume 2, Issue 1 (Spring 2018)
Abstract
Electronic wastes are known as the most important solid wastes in 21th century. They are producing two or three time faster than other solid waste streams. Many researchers studied bioleaching of e-wastes using Acidithiobacillus ferrooxidans. The presence of alkaline metals cause e-wastes show an alkalinity nature. By adding e-wastes to the environment the pH of solution increases sensibly. Many researchers supposed the optimal pH range of A. ferrooxidans which is 1.5-2.5 as the optimal pH range to reach maximum recovery. So in the bioleaching process by daily pH adjusting in the range and using sensible amount of sulfuric acid, control the pH of solution about 2. In this research two same experiments, just the pH of one of them was adjusted daily, were done. In both experiments the environmental situation including pulp density of 15 g/l, inoculum 10% (v/v), the temperature of 30ºC, and shaking rate of 130 rpm was the same. For 25 days Cu recovery, bacterial count, pH, and Eh were examined. The results showed the maximum Cu recovery at the sample without pH adjusting was about 100% but at the sample with pH adjusting recovery was reduced to 90%. The bacterial count diagram showed the bacterium is well active in both experiments. To maximize recovery, reducing acid consumption, and increasing process economy there is no need to adjust the pH of solution.
Reza Rasoolzadeh, F. Mehrnejad, Majid Taghdir, Parichehreh yaghmaei,
Volume 11, Issue 1 (Winter 2020)
Abstract
The interactions between carbon nanotubes (CNTs) and proteins were considered much attention. Advanced CNT applied biomolecules require mutual understanding of their interactions with biological molecules. Enhanced biomedical applications of CNTs have necessitated the need for the understanding their interaction with biomolecules. Non-covalent interactions of blood peptides, such as hepcidin, with carbon nanotubes, have important effects in a wide range of biological applications that are detected by analyzing the thermodynamic parameters of the interaction between CNTs and peptides. In addition, the effects of different parameters in order to evaluate how the interaction of CNTs with peptide affects and structural changes and stability of peptides were studied. In this study, based on molecular dynamics (MD) simulation, the structural changes of hepcidin 20 in interaction with multi walled carbon nanotubes (MWCNTs-COOH ) were investigated. The simulation results revealed that carbon nanotubes cause to loose the hepcidin structure and make structural changes in this peptide. On the other hand, the loose of the hepcidin structure may lead to a change in its activity. The results indicated that significant changes were made in the structure of hepcidin 20 in the presence of carbon nanotubes. The difference of parameter amounts calculated in heptidine 20 is related to their N-terminal, and loop regions.
Volume 15, Issue 10 (1-2016)
Abstract
The dominant excitation forces are generally measurable during the forced vibration tests of structures unlike the ambient vibration tests. Not considering of input forces in the system identification is one of the main sources for error generation in the Operational Modal Analysis (OMA). Therefore, some non-structural dynamic characteristics obtained due to the excitations effects can be eliminated by considering the input forces. In this paper, a special modal analysis is presented in the subspace method that removes the excitation effect of the measured input forces from the test data using orthogonal decomposition and identifies the system with an optimal subspace method based on canonical correlation analysis (SSI-CCA). To evaluate the proposed method, the seismic response of the Pacoima dam and forced vibration test results of the Alamosa Canyon Bridge are used. Non-structural and noisy pole removal, and increased accuracy of the extracted modal properties, specially damping ratios, can be mentioned as one of the important results of this study. Four non-structural modes are identified using the SSI-Data method while the first two modes without any noises, the same as previous results, are extracted using the proposed method. In addition, the damping ratios of the Alamosa Bridge are obtained by Hammer test, which are not obtained in the previous investigations.
Volume 17, Issue 1 (5-2017)
Abstract
Finite element model is the conventional method used for static and dynamic analysis of widely used structures such as dams and bridges, since it is cheap and requires no special tools. Nevertheless, these models are not able to describe the accurate behavior of structures against dynamic loads because of simplifying assumptions used in numerical modeling process, including loading, boundary conditions and flexibility. Nowadays, modal testing is used to solve these problems. The dynamic tests used to identify civil structures’ system usually include forced, free and environment vibration tests. Considering either unknown nature of inputs or failure to measure them, some methods have been developed to analyze the results of dynamic tests which are based on measuring only output data and are known as operational modal analysis. Some of such methods are Peak Picking (PP), Frequency Domain Decomposition (FDD) and stochastic subspace methods. However, unknown nature of applied forces, the presence of environmental noise and measurement errors contribute to some uncertainties within the results of these tests. In this article, a modal analysis is presented within a stochastic subspace which is among the most robust and accurate system identification techniques. In contrast to the previous methodologies, this analysis identifies dynamic properties in optimized space instead of data space by extracting ortho-normal vector of data space. Given the optimum nature of the proposed method, more accuracy in detection and removal of unstable poles as well as high-speed analysis can be served as its advantages. In order to evaluate the proposed method in terms of civil systems detection, seismic data (being among the most real and strong environmental vibrations) and steady-state sinusoidal excitation (which is among the most precise forced vibration tests) were used. In the first step, 2001 San Fernando earthquake data were analyzed using SSI-CCA and SSI-data methods, the results of which are presented in the following. Data processing rate in the SSI-CCA method is almost twice that in SSI-data method which is because of processing in an optimum space while lowering the use of least squares method to compute system vector. Furthermore, there is one unstable pole in the results of the proposed method while 4 noisy characteristics were recognized in the results of SSI-Data method. Estimated damping ratios comprised the major difference observed in this analysis using above-mentioned two methods. Modal damping ratios estimated by the proposed method were 60% closer to the previous results when compared to those of the previous subspace method. Mode shapes of both subspace methods with MAC value of 92% and 75% for the first and the second modes, respectively, are well correlated with each other. Due to lack of access to the mode shape vectors of Alves’s method, it was not feasible to calculate the corresponding MAC value. In the following, forced vibration test results of Rajai Dam conducted by steady sine excitation in 2000 and analyzed by a method known as four spectral, are re-processed Using the SSI-CCA method. As results indicate, using the proposed method the first three modes are obtained that were not on the preliminary results. In addition, other modes are of great fit with the values of the finite element.
Volume 18, Issue 2 (6-2015)
Abstract
Objective: Drug delivery systems related to different cancer therapies is now expanding. Chitosan (CS) is currently receiving enormous interest for medical and pharmaceutical applications due to its biocompatibility in animal tissues. In this study, two nanogels were prepared from CS. Some of the critical factors such as controlling the release, adsorption and specially targeting drug delivery are considered while preparing the nanogels.
Methods: Phosphorylated CS (PCS) and Myristilated CS (MCS) nanogels were prepared by reacting CS with tripolyphosphate (TPP) and Myristate as cross-linking agents respectively and then were loaded with Doxorubicin (DOX). The nanogels were characterized by different techniques such as scanning electron microscopy, dynamic light scattering and Fourier-transform infrared. The cytotoxicity of free DOX, MCS nanogels and DOX loaded MCS was evaluated by the MTT assay.
Results: The result of DOX loading and releasing of the nanogels showed high loading capacity and drug loading efficiency of about 97%. Results indicated slow release of about 16-28% of DOX from PCS within 5 days and 18-40% from MCS within 15 days. DOX and MCS-DOX showed the same toxic effect on the prostate cancer cells (LNCaP).
Conclusion: Both PCS and MCS nanogels were qualified on the basis of size, loading and releasing capacity.
Volume 19, Issue 2 (7-2019)
Abstract
Nowadays, reinforced concrete structures are widely being constructed all over the world and some of them need to be strengthened for variety of reasons such as poor design, damages caused by earthquakes, etc. Nowadays, engineering attitude toward demolition and renovation of structures have been changed to retrofitting and upgrading. By retrofitting, the structural reliability increases and saves both time and cost. In some of special cases that the structure can not be demolished and rebuilt, retrofitting plays an important role. The columns of the structures are one of the main elements that are subjected to axial, shear forces, and bending moments, and their strength and ductility have an important impact on their seismic capacity. Different methods are used for strengthening of columns. These methods include concrete jacketing, steel jacketing and composite jacketing (FRP). Among the various retrofitting methods of reinforced concrete columns, steel jacketing is one of the methods used to strengthening of RC structures, especially for confining RC columns with rectangular and square cross sections. Steel cage is a type of steel jacket and because of its effectiveness, ease of use, light weight and the availability of material, it has become an affordable, effective, economic and simple option. This method involves the use of four longitudinal angle steel profiles fixed to the corners of the RC columns, to which some transverse steel strips are welded. The gap between steel cage and column is filled with cement or epoxy mortar. Different parameters affect the behavior of the column reinforced with steel cage. Studies carried out on this strengthening method have mostly focused on the axially loaded columns. The parameters have been studied are the number of steel strips, the size of the steel strips, the size of the steel angels, the thickness of the steel strips, the yield stress of the steel of the cage, the compressive strength of the concrete used in the column, and, finally, the use of capitals in the beam-column connection joint zone. Capitals are welded to the steel cage and located at each end of the cage, loads applied to the beam are transmitted to the steel cage through the capitals. Loads from an upper floor of the building are also transmitted to the cage through the beam via the capitals. Current study investigates the behavior of RC columns strengthened with steel cage under axial force and bending moment. In this regard, the strengthened RC column with steel cage was modeled using finite element method using ABAQUS software and calibrated by experimental results obtained from other laboratory research works. Then, the parameters affecting the behavior of the strengthened columns were examined. The results of this study show a good agreement with experimental results and demonstrate a considerable increase in the ultimate axial force and bending moment.
Volume 20, Issue 80 (4-2023)
Abstract
This research aims to analyze and investigate the two-way relationship between love and morality in the character of women of Khosrow's and Shirin Nizami's systems in a descriptive-analytical way and with a library method. By examining the poem of Khosrow and Shirin, we can conclude that this poem is based on the love between people and the topic of ethics and moral virtues has a high position in this story. According to the structure of the story, Nizami has written the story in a suitable format for indirectly projecting ideas and teaching moral issues to the readers.