Showing 20 results for Sepehri
Volume 2, Issue 4 (12-2013)
Abstract
Fusarium graminearum is one of the most important causes of FHB or wheat scab in different part of the world. This fungus is able to produce widespread Trichothecene mycotoxins such as Nivalenol (NIV) and Deoxynivalenol (DON) which are harmful for both human and animals. To determine chemotypes of Trichothecene, a total of 100 isolates from different fields of Golestan province in Iran including Gorgan, Kordkuy, Bandaregaz, Gonbad, Minodasht, Kalaleh and Azadshahr were identified as F. graminearum using morphological features then 96 isolates were confirmed by polymerase chain reaction (PCR) assay using F. graminearum species-specific primers (Fg16F/Fg16R). Based on sequences of Tri13 gene involved in the mycotoxin biosynthetic pathway, PCR assays was used to detect Nivalenol (NIV) and Deoxynivalenol (DON) chemotypes. Of the 96 tested isolates with Tri13 PCR assays, 70 classified as NIV chemotype and the remaining 26 isolates as DON producers. These results indicated that NIV chemotype was the most dominant chemotype in studied zones. A greater proportion of NIV chemotype was found in Gorgan fields (P < 0.05, P < 0.0001), whereas greater proportion of DON was detected in Gorgan and Gonbad fields (P < 0.05, P < 0.0001). Chemotyping by PCR assay were confirmed using HPLC method. These results demonstrated that PCR assay and HPLC could be used as rapid, reliable and cost-effective methods for the detection and identification of mycotoxin-producing Fusarium-species and may thus help to develop strategies to avoid or reduce mycotoxin contamination of cereals.
Volume 3, Issue 2 (Summer 2019)
Abstract
In order to develop the scope of application of polymer materials in the preparation of drilling fluids, in this study, various blends of wheat starch and copolymer of sulfonated polyacrylamide were prepared and the rheology and compatibility behavior of samples under different salinity and aging conditions were evaluated. The rheological behavior of starch-polyacrylamide blends in tap water and saturated brine water showed that the viscosity of the samples increased with increasing concentration of polyacrylamide copolymer in the both media. However, starch-polyacrylamide blends in saturated brine had less viscosity than tap water. It was observed that in both tap water and salt water saturated conditions after 4 hours of aging at 90 ° C, the viscosity of most samples increased. Comparison of the curves for empirical viscosity data and prediction of the mixing rule showed that in both of tap water and salt saturated water, positive deviation from the mixing rule is observed, which indicates the compatibility between the blend components. By performing the aging process, although positive deviation was still observed, this positive deviation slightly decreased, which means the negative effect of aging on the compatibility of the starch- copolymer of sulfonated polyacrylamide blend.
In conclusion, the results of this study showed that the blend of starch- sulfonated polyacrylamide copolymer is compatible at high temperature (90 °C) and saturated NaCl salt wate. Moreover, in some samples, this compatibility exists even after aging.
Volume 5, Issue 2 (8-2014)
Abstract
Analysis of signed biological networks has been an interest of some researchers in recent years. We consider communities and balanced clusters as two structural patterns that may reveal different structures in the networks. Although biological networks tend to structural balance, this study clarifies adhesive communities in some transcriptional networks of ecoli and yeast differ from the balanced clusters and have significantly more negative links in their structure. This difference may be used as an index in categorizing various systems' structure and function. Also we study the important role of the positive links between balanced clusters, even though the links between these clusters are mostly negative. Analyzing data of some Gene Regulatory Networks, shows that perturbing the genes located at these links, has a larger effect on the system and causes more distance from the initial equilibrium state. So, signed clustering and detecting the links between these clusters can be considered as an effective approach in detecting the functional units and the key components in the system. This can be useful in applications like gene targeting in drug synthesis.
Volume 5, Issue 3 (9-2017)
Abstract
Aim: The objective of this paper is to design nutrient-adequate, varied and cost-efficient diets for diabetes patients.
Methods: A new multi-objective mixed integer linear programming model under uncertainty is developed to design diet plans for diabetes patients.
Findings: The analysis is conducted on the population of 30 years old men and women in 24.99 and 18.5 body mass index, 1.50, 1.65 and 1.80 (m) height categorized in 4 physical activity levels (sedentary, low, active and very active). The objectives of the model are the minimization of the total amount of saturated fat, sugar and cholesterol and the total cost of the diet plans. The constraints of the model are fulfilling the body's nutrient requirements and the diversity control of each patient’s diet. In order to get closer to the real world, fuzzy parameters are considered in the model. To solve the model, a new hybrid solution methodology (Jimenez and epsilon-constraint method) is used to offer the optimal Pareto of non-dominated solutions. Each optimal Pareto of the model consists of diet plans that each patient can choose the proper food based on the taste, availability and cost.
Conclusion: Mathematical modeling of diet planning and study of its optimal solutions can be considered as a decision support tool for the professionals to design the most proper diet plans.
Volume 9, Issue 4 (winter 2020)
Abstract
The natural environment is one of the most valuable properties of the human being, but its real cost has not been recognized yet. Therefore, the valuation of natural ecosystems that provide various social, cultural and environmental services to urban fabric collections has received special attention in recent years. In this study, after a review of valuation systems of cultural services in several countries, as well as exploratory interviews with relevant experts and researchers in Iran, some criteria, sub-criteria, and indicators for valuing cultural services have been suggested by applying Delphi method. After studying the available resources and reviewing the interviews 5 main indexes with 17 sub-indexes and 56 indicators were extracted and introduced for evaluation of cultural services of natural ecosystems. Five main indexes include aesthetic, outgoing, cultural, spiritual, and education. These indexes have sub-indexes named diversity of perspectives, natural life, specific species and protection significance for the aesthetic index. An outgoing index has two sub-indexes namely natural parks and entertainment facilities. Cultural indexes have five sub-indexes namely historical sites, cultural heritage, nature as an intuition source for an artistic activities, religious locations, and cultural occurrences. A spiritual index has only one sub-indexes named religious beliefs. Eventually, education index has five sub-indexes namely knowledge about an ecosystem, traditional knowledge, knowledge management, knowledge of stakeholders and experiencing nature. It is possible to identify criteria and indicators and match them with cultural values in planning.
Volume 10, Issue 4 (11-2021)
Abstract
Beans are major feed crops belonging to the family Leguminosae, representing one of the most consumed legumes in Iran. Root rot diseases account for high yield losses in bean crops annually, driving the need to identify causative pathogenic agents. During the cropping season of 2019, samples were collected from rhizosphere and infected plant tissues in Khomein county. Of the total 80 purified isolates, 19 fungal isolates were selected for morphological and molecular identification studies. Fusarium equiseti, Fusarium acuminatum, and Macrophomina phaseolina were isolated from the infected crown and root tissues. Their pathogenicity on bean cultivars (Yaghout, Dorsa, and Koosha) is reported for the first time from Markazi province. However, the pathogenicity of fifteen saprophytic and pathogenic fungi species that are isolated from the rhizosphere needs to be confirmed in further studies. Disease symptoms were found to be more severe on pinto beans than red and white beans. In all cases, molecular studies using ITS and tef genomic region confirmed the morphological results. Briefly, these fungal species are introduced as bean root rot causal agents in Khoemin county, which needs to be considered in upcoming breeding programs.
Volume 11, Issue 1 (4-2011)
Abstract
Abstract:
The influence of cement content increase on corrosion resistant behavior in concretes
containing nano-SiO2 was experimentally studied. For comparison, the chloride diffusion of
plain concrete and the concrete containing nano-SiO2 was also experimentally studied. The
test results indicated that the corrosion resistance of concretes containing nano-particles is
significantly improved. However, the index of diffusion chloride ion in the concretes
containing nano-SiO2 is directly related to cement content in the mix. The SEM oservations
revealed that the microstructure of concrete with nano-SiO2 is more uniform and compact
than that of normal concrete, but higher pore size distribution was observed when cement
content is increased, which in turn leads to the increase in the diffusion of choloride ion.
Volume 12, Issue 4 (3-2013)
Abstract
This paper develops new results on the use of model predictive control to regulate the attitude of a ground station antenna. Two degree of freedom AZ-EL pedestal is considered as ground station antenna. Permanent Magnet Synchronous Motors are taken into consideration as the best choice for satisfaction of control objectives as actuators. The design is based on a two cascade controller consist of MPC and a simple feedback linearization, respectively. The proposed approach provides more smooth tracking and lower energy consumption with respect to analogous works. The model predictive controller employs integral action, resulting in zero steady-state error and load torque disturbance rejection. Realistic disturbances caused by wind and load is considered and applied to an industry-sized pedestal. The reference data of azimuth and elevation angles are chosen from a real tracking mission. The comparison of simulation results by typical PI controller, verify the effectiveness of the proposed method.
Volume 13, Issue 1 (3-2022)
Abstract
Transforming growth factor beta (TGF-β), is a small homodimeric signaling protein. The TGF-β isoforms (TGFβ1, β2 and β3) are involved in many cellular processes including growth inhibition, extracellular matrix remodeling, tissue development, cell migration, invasion and immune regulation. For research aims, TGFβs are overexpressed using recombinant eukaryotic cell or bacterial expression systems. For achieving an efficient purification of TGF-β by immobilized metal ion affinity chromatography (IMAC), a histidine tag was placed either at the C-terminal (C-TGFβ) or N-terminal (N-TGFβ) region of the sequence and the effect of His-tag on TGF-β structure has been studied by computational tools. Proteins 3D structures were modeled using MODELLER software and molecular dynamics simulation of native TGF-β and modelled proteins, N-TGFβ and C-TGFβ were studied in water by GROMACS package. Protein dynamics modeling indicated that the His-tag attached at the C-terminus but not at the N-terminus of the TGF-β can affect the fluctuations of amino acids and protein structure. It is concluded that the C-terminal tagging may cause distortion and misfolding in the structure.
Volume 13, Issue 3 (8-2010)
Abstract
Objective: Escherichia coli is the most prevalent etiologic agent of urinary tract infections which is the cause of about 80% of cases. Enzymatic inactivation of aminoglycosides by aminoglycoside-modifying enzymes is the main mechanism of resistance to these antibiotics in Escherichia coli. The aim of this study was the detection of aac(3)-IIa gene among aminoglycoside resistant clinical isolates of E. coli using PCR method.
Materials and Methods: After collection of 250 clinical isolates of E. coli, antibiotic susceptibility patterns of isolates were determined by disk diffusion method for gentamicin, amikacin, tobramycin, kanamycin and netilmicin by considering the CLSI principles. Chromosomal and plasmid DNA of the isolates were extracted using DNA extraction Kits and PCR method was used for detection of the aac(3)-IIa gene.
Results: Results show that 96% of E. coli isolates were resistant to tobramycin, 90% resistant to kanamycin, 82% resistant to gentamicin, 30% resistant to netilmicin and 8% resistant to amikacin. aac(3)-IIa gene was detected in 54.83% of E. coli isolates.
Conclusion: Because of high prevalence of resistance toward aminoglycoside antibiotics which is due to its transfer among bacteria by transferable elements such as transposons and plasmids. Therefor, tracing transfer routs among different bacteria is very important.
Behrooz Sepehri, Morteza Rameshi,
Volume 14, Issue 11 (2-2015)
Abstract
Orthopedic plates are currently used in bone healing process. However they cause density loss because of the change in natural stress patterns.The aim of this study was to evaluate a newly developed bone plate using functional graded material in term of stress pattern. In the present study, 3D finite element models of tibial bone plate with variable stiffness of a graded material and traditional bone plates made of stainless steel and Ti alloy have been developed by using the ABAQUS software. Effects on the predicted stresses at the fracture site in the presence of a distance between the plate and fractured bone were also studied. For this purpose, a 3D model of tibia was created with the exact geometry of the real bone geometry by using CT scan images of a human left leg. Results showed that the bone plate with graded material offers less stress-shielding to the bone, providing a higher compressive stress at bone to induce accelerated healing in comparison with Ti alloy and stainless-steel bone plate. Results also showed that the use of non-contact plates provide a favorable mechanical environment for the following fracture healing.
Volume 15, Issue 4 (2-2012)
Abstract
Customer churn management consist of three main phases: identifying churners, discovering the causes of churn and adapting appropriate strategies against this problem. Most of studies in this field focused on prediction of customer churn. Few studies about discovering causes of churn are just about testing primary hypothesis about probable causes. This study because of the shortage of previous studies in this field has made lots of innovations. Some of these innovations are: designing a new framework for discovering causes of churn and designing a hybrid approach from data mining and survey techniques which carried out without benchmarking from any similar study. Proposed framework includes four main steps: feature construction and selection, identification of churners, discovering the causes of churn, and validating the results. Current account customers of Keshavarzi Bank are selected as casestudy of this research and the required data is gathered trough questionnaire. The approach used for discovering causes of churn is extracting the rules which lead to churn in various clusters of customers. For this purpose, decision tree technique with target variable of churn label is utilized. Validating the results is carried out by testing it on validation data set and calculating the top lift and overall error rate. The extracted rules represent that there is a tendency to churn among big segment of keshavarzi's customers. The most important reason (specially among higher salary customers) is about manner of bank agents not reasons expressed by experts such as the way of lending or the profit of backup accounts.
Behroz Sepehri, Ali Asadi,
Volume 15, Issue 4 (6-2015)
Abstract
Human bones experience different modes of loading including tension, compression, bending, and torsion. The modes of loading depend on the activities done by the body. Regarding the crack shape and loading modes, by the time only the first mode of fracture has been studied in order to analyze the fracture toughness. However, it is necessary to analyze different modes of fracture in order to find more reliable results. In this research, finite element analysis and calculations for geometric coefficients were done to obtain the toughness of bone. Hence, first, second, and combined modes of fracture in cortical samples having cracks were studied numerically and experimentally. To this end, bovine tibia was used to make standard tensile samples for implementation in Arkan’s device. Some optimizations were made on the Arcan’s device. These were included of bone fixation in the device and ability of performing tests in different angels. Stress intensity factor (Kc) was obtained for different fracture modes. Results showed a decrease in KIc respect to change in loading angle while KIIc acted vice versa. Performing some extra optimizations, the device can be used for tortional fracture mode in a torsional test device.
Behrooz Sepehri, Hojat Mohammadi Esfahani, Faramarz Firouzi,
Volume 16, Issue 8 (10-2016)
Abstract
Mechanical behavior of articular cartilage is affected by many factors. Inhomogeneous distribution of proteoglycans and collagen fibers through the thickness causes some depth-wise behavior. Mechanical properties directly affect stress and deformation of the tissue. In previous studies complexities and variation in mechanical properties were ignored. The aim of the present study is to create a model close to real anatomy of articular cartilage in knee joint and to simulate its behavior under dynamic gate in the stance phase. A 3D finite element (FE) model was created. It was constructed considering femur and tibial cartilages as well as medial and lateral meniscus. In the FE model, a nonlinear isotropic viscoelastic material model used for cartilages and a linear anisotropic elastic one was chosen for meniscuses. As well, cartilages assumed saturated . Numerical simulations on the model showed that peak of maximum principal stress occurred in superficial layer. It was decreased through thickness. These expressed why osteoarthritis fall out in the exterior layers such superficial . The present study showed that hydraulic permeability variation in cartilage as a strain-dependent variable was negligible in dynamic loading. Also, results had a good agreement with experimental ones
Volume 17, Issue 4 (1-2014)
Abstract
Determining how to assess learners and contents of e-learning are essential activities in its processes. These activities are conducted by a professor or teaching assistant and they determine student assessment methods, such as holding an online test or periodic homework assignment. if the organizers can be aware of the effectiveness of each activity in the quality of learning,then besides saving considerable time and resources to stakeholders courses, which transfer the content useful and realistic assessment of students and will ultimately improve e-learning. In this paper, first we use unsupervised techniques of data mining for clustering and describe the present status of learners, and extract hidden rules in e-learning data using rule mining and will discover the effective contents in desired results. Next, using supervised methods we predict results of courses. Using real data of an electronic course provided and with designing four different methods for data sampling and training system, predictions were performed and the methods were validated with an accuracy rate of 92.86%. We have shown that the methods of this study can help teachers for a better understanding of learners and impact of such training activities required, such as describe characteristics of learners based on the discovery of hidden patterns in the scores of their acquired and determine the most effective learning activities and decide about real measures of learners.
S.m. Zareei, M. Jamshidian, Sh. Sepehrirahnama , S. Ziaei-Rad,
Volume 19, Issue 2 (February 2019)
Abstract
Acoustofluidics, the study of acoustics in microfluidic systems, is the basis for analyzing many laboratory applications including the separation of particles, particle sorting, cleaning, and mixing multiphase systems. In this research, a three-dimensional finite element model for particle motion under acoustic radiation force in acoustic microchannels is developed and the interaction of the incident waves with a suspended particle in microchannel is investigated. Using finite element method, the first-order fields due to an applied standing wave are initially calculated and, then, the acoustic radiation force is directly calculated from the second-order perturbation equations. The simulation results for radiation force are first verified against the analytical solution in the Rayleigh limit and, then, examined beyond this limit, for which there is no explicit analytical solution. In addition, the quasi-static motion of a particle under the influence of an applied acoustic standing wave in microchannel is simulated. For simulating particle motion, the acoustic stress on particle surface is calculated and transferred as an input to the laminar flow equations. Then, the drag force is estimated based on the shear stress due to the flow around the particle. The simulation results demonstrate that the particle velocity depends on its position with respect to the wave node at the center of the microchannel. As the particle approaches to the center of microchannel, its velocity decreases until it stops at the center of microchannel.
Volume 19, Issue 3 (9-2015)
Abstract
Petroleum industry of Iran has provided one of the best opportunities for employees, but occupational exposures leading to chronic diseases such as cancer are high in the field. Ministry of Petroleum has owned an organization, which covers the personnel with health insurance, called “Petroleum Industry Health Organization” (PIHO). PIHO and Health, Safety & Environment (HSE) units play significant roles in providing the employees with health services. However, there is lack of a unique system specifying occupational cancer control. Cancer is a major cause of morbidity and mortality worldwide. On the other hand, negative impressions of cancer and heavy costs of patient’s treatment have forced the ministry to pay appropriate attention to this chronic disease. This paper aims to identify structure and design a framework for a system to occupational cancer control in Iranian petroleum industry. Due to the vast dynamic complexities (multi-dimension nature of cancer, joint exposures, and the delay between exposure and incidence) and behavioral complexities (various stakeholders and actors) in the problem, we have adopted Soft System Methodology (SSM) in order to study the current situation. We reached an agreement with the problem owner on a rich picture, CATWOE analysis, and a root definition on how this surveillance system would be considering the real world circumstances.The results were obtained through many sessions with problem stakeholders even with conflicting interests. The results revealed that it is necessary to make some changes in the actors’ information systems (occupational hygiene and medicine, hospitals and the ministry’s Pension Organization), with an emphasis on identifying and analyzing carcinogens and cancer patients in order to improve the problem situation.
Alireza Barani, Peiman Mosaddegh, Shaghayegh Haghjooy Javanmard, Shahrokh Sepehrirahnama,
Volume 21, Issue 10 (October 2021)
Abstract
These days, investigation on using acoustofluidic microchannels in separation of microparticles and cells is under consideration. Working under optimum efficiency, these microchannels should be designed and manufactured truly. In this work, a new methodology for designing and manufacturing of acoustofluidic microchannels are explained. Then, a metallic microchannel with 2-nodes of pressure wave based on this method was developed. For mass production purpose, a low cost and reliable method which is CNC micromachining is used. Also, to conduct the heat generated by the wave, this microchannel was made out of aluminum and then polishing technique is applied. Then, the performance of this microchannel in agglomerating of human blood cells and BT-20 breast cancer cells to nodal lines was experimentally studied. The results showed that the applied design and manufacturing technique are suitable. Although some tests were performed to find temperature rise of microchannel due to damping effect, it was found that true design method and also using metals with high thermal conductivity can prevent the temperature increase to the point beyond which living cells will be hurt.
Volume 22, Issue 3 (7-2015)
Abstract
In the past four decades, new approaches and methodologies have been developed to solve unstructured and messy problems with various stakeholders. Among these methods, soft system methodologies, cognitive mapping, and strategic choice approach are specifically worthy to be heeded. The methods mentioned above, which have a precise structure and clear framework, are often categorized as soft operations research or problem structuring methods. Today, there is ample literature on soft research and it is taught in many operations research/management science courses of reputable universities. Methods of research on soft OR are rooted in soft system thinking and belong to the interpretative/learning paradigm. Nonetheless, assigning a clear and precise boundary between hard and soft OR techniques is not easily feasible, for most of these techniques– based on their application in different situations – can be classified as both hard and soft. The aim of this research is to investigate the origins and current position of soft methodology of operations research and probe into its theoretical basis. A comparison between the trend of OR in the US and UK clearly demonstrates the differences in soft and hard approaches. Generally, it can be concluded that soft and hard approaches of OR are complementary: soft methods are exploited in forming the structure (configuration) of a problem and hard methods are utilized in solving it.
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Volume 24, Issue 2 (Summer 2021)
Abstract
Maternal separation (MS) is a model to induce early life stress (CNS) and is related to increased levels of anxiety and cognitive deficiencies. Voluntary exercise has been shown to be associated with learning and memory improvement in behavioral tests and electrophysiological experiments. Since it plays a significant role in learning and memory and enhances synaptic plasticity, the authors hypothesized that voluntary exercise may affect MS-induced changes in synaptic plasticity and cognitive performance.
Rat pups underwent the MS protocol for 180 min/day from postnatal day (PND) 1 to 21. Voluntary exercise was performed in the exercise (Ex and MS + Ex groups from PND 29 to 49. Anxiety-like behavior, learning and memory were measured in adolescent rats. In addition, evoked field excitatory postsynaptic potentials (fEPSP) were recorded from the CA1 region of the hippocampus.
MS induced higher anxiety-like behavior as well as impaired learning and memory, but did not affect locomotor activity. Voluntary exercise improved MS-induced deficits and increased the learning and memory of MS rats. It also decreased anxiety-like behavior in the open field test. The results revealed that long-term potentiation (LTP) was induced in all groups, except for MS. However, voluntary exercise induced LTP and had maintenance in MS + Ex.
