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Search Results: 1 - 10 of 200513 matches for " P Tayyebi "
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Comparison of physical sputtering and ion plating methods for investigation of hydrogen distribution into the hydrogen targets
P Tayyebi,F Abbasi Davani
Iranian Journal of Physics Research , 2011,
Abstract: In this paper, selection of proper method for titanium coating on copper substrate is studied to construct nuclear targets for neutron production in particle accelerators. In order to construct such targets, it is necessary to deposit, through the coating methods, the proper coating of titanium on copper. Among different coating methods, ion plating and sputtering, due to the high coating yield and stability of titanium layers, has been selected. To compare different amounts of hydrogen absorption, two series of targets, different in the coating methods, were exposed to the similar conditions under 40 bar hydrogen gas. Comparison of elastic recoil particles (ERD) results of two series of the targets showed that hydrogen atoms permeated in deeper layer of targets, which were deposited by ion plating, than the targets deposited by sputtering. Hence, it was concluded that the ion plating method is more suitable to make nuclear targets.
The Availability of Universal Grammar to Second Language Learners: A Case of Wh-movement
Ghasem Tayyebi
International Journal of English Linguistics , 2012, DOI: 10.5539/ijel.v2n3p34
Abstract: In this experimental study, the researcher examined the accessibility of Universal Grammar to adult Persian learners of English with respect to the Empty Category Principle and the Subjacency. These principles are not operative in Persian as it is a Wh-in situ language. A 5-point Likert scale acceptability judgment task, which included both grammatical and ungrammatical extractions, was given to a group of 35 advanced Iranian EFL learners. The control group consisted of 30 adult native speakers of English. Their responses provided the baseline against which we measured the performance of non-native speakers. The categorical performance of natives and non-natives on both types of grammatical and ungrammatical extractions was revealed through within-group comparisons. Similarly, between-group comparisons displayed that the performance of Iranian EFL learners did not differ significantly from that of the natives in the ungrammatical constructions. In general, the findings of this study led the researcher to conclude that Universal Grammar constrains adult EFL learners’ competence.
Functional Analysis of Small Towns Economic Role in Rural Development, Case Study: Zahedshahr, Iran  [PDF]
Issa Ebrahimzadeh, Najmeh Tayyebi, Yousef Shafei
Journal of Service Science and Management (JSSM) , 2012, DOI: 10.4236/jssm.2012.53032
Abstract: The growing increase in the number of small towns, brought about as a result of Iran’s demographic changes in recent decades, has necessitated due consideration of these towns in the country’s hierarchical urban system on the one hand and their economic function in their immediate periphery on the other. In the present article, an analysis has been conducted of the economic role Zahedshahr has played as a small town in its rural periphery by using the Jacqueline Beaujeu Garnier and George Shapou’s Model, as well as the Locational Coefficient and the Abscissa-Ordinate Graphic Models. Results obtained from the analysis showed that the above town, in spite of its small size, has played an effective role in providing services to the inhabitants of its surrounding areas, as well as acting as a center for sale of surplus agricultural products, thanks to its relatively equipped administrative, educational, commercial, etc., centers. The find- ings of this research also showed the development of Zahedshahr to be directly dependent on the social and economic conditions of its periphery, so that rural population and agricultural products stability can influence such development.
Microstructure and mechanical properties of SiC-particle-strengthening tri-metal Al/Cu/Ni composite produced by accumulative roll bonding process
Moslem Tayyebi,Beitallah Eghbali
- , 2018, DOI: https://doi.org/10.1007/s12613-018-1579-6
Abstract: In this study, a multilayer Al/Ni/Cu composite reinforced with SiC particles was produced using an accumulative roll bonding (ARB) process with different cycles. The microstructure and mechanical properties of this composite were investigated using optical and scanning microscopy and hardness and tensile testing. The results show that by increasing the applied strain, the Al/Ni/Cu multilayer composite converted from layer features to near a particle-strengthening characteristic. After the fifth ARB cycle, a composite with a uniform distribution of reinforcements (Cu, Ni, and SiC) was fabricated. The tensile strength of the composite increased from the initial sandwich structure to the first ARB cycle and then decreased from the first to the third ARB cycle. Upon reaching five ARB cycles, the tensile strength of the composite increased again. The variation in the elongation of the composite exhibited a tendency similar to that of its tensile strength. It is observed that with increasing strain, the microhardness values of the Al, Cu, and Ni layers increased, and that the dominant fracture mechanisms of Al and Cu were dimple formation and ductile fracture. In contrast, brittle fracture in specific plains was the main characteristic of Ni fractures.
Applying Neural Network to Dynamic Modeling of Biosurfactant Production Using Soybean Oil Refinery Wastes
Shokoufe Tayyebi,Tayebe Bagheri Lotfabad,Reza Roostaazad
Iranica Journal of Energy and Environment (IJEE) , 2013, DOI: 10.5829/idosi.ijee.2013.04.02.14
Abstract: Biosurfactants are surface active compounds produced by various microorganisms. Production of biosurfactants via fermentation of immiscible wastes has the dual benefit of creating economic opportunities for manufacturers, while improving environmental health. A predictor system, recommended in such processes, must be scaled-up. Hence, four neural networks were developed for the dynamic modeling of the biosurfactant production kinetics, in presence of soybean oil or refinery wastes including acid oil, deodorizer distillate and soap stock. Each proposed feed forward neural network consists of three layers which are not fully connected. The input and output data for the training and validation of the neural network models were gathered from batch fermentation experiments. The proposed neural network models were evaluated by three statistical criteria (R2, RMSE and SE). The typical regression analysis showed high correlation coefficients greater than 0.971, demonstrating that the neural network is an excellent estimator for prediction of biosurfactant production kinetic data in a two phase liquid-liquid batch fermentation system. In addition, sensitivity analysis indicates that residual oil has the significant effect (i.e. 49%) on the biosurfactant in the process.
Incessant Ventricular Tachycardia Acutely Controlled with Off-Pump Coronary Artery Bypass Surgery and Aneurysmal Plication
Alireza Heydari,Asadollah Mirzaie,Mohammad Tayyebi
Journal of Tehran University Heart Center , 2010,
Abstract: There are many treatment modalities available to acutely terminate incessant ventricular tachycardia with variable success rates, but some cases tend to prove refractory to all of them. We report a 59-year-old woman presenting with incessant ventricular tachycardia. Echocardiography revealed a large true apical aneurysm and severe left ventricular dysfunction. The arrhythmia was controlled in the operating room after off-pump coronary artery bypass surgery and plication of the apical aneurysm.
M. leprae inhibits apoptosis in THP-1 cells by downregulation of Bad and Bak and upregulation of Mcl-1 gene expression
Zahra Hasan, Mussarat Ashraf, Ali Tayyebi, Rabia Hussain
BMC Microbiology , 2006, DOI: 10.1186/1471-2180-6-78
Abstract: M. leprae did not induce apoptosis in THP-1 cells, while BCG induced a significant loss of cell viability by 18 h post-infection at both (multiplicity of infection) MOI-10 and 20, with an increase by 48 h. BCG-induced cell death was accompanied by characteristic apoptotic DNA laddering in cells. Non-viable BCG had a limited effect on host cell death suggesting that BCG-induced apoptosis was a function of mycobacterial viability. M. leprae also activated lower levels of TNF-alpha secretion and TNF-alpha mRNA expression than BCG. Mycobacterium-induced activation of apoptotic gene expression was determined over a time course of infection. M. leprae reduced Bad and Bak mRNA expression by 18 h post-stimulation, with a further decrease at 48 h. Outcome of cell viability is determined by the ratio between pro- and anti-apoptotic proteins present in the cell. M. leprae infection resulted in downregulation of gene expression ratios, Bad/Bcl-2 mRNA by 39% and Bak/Bcl-2 mRNA by 23%. In contrast, live BCG increased Bad/Bcl-2 mRNA (29 %) but had a negligible effect on Bak/Bcl-2 mRNA. Heat killed BCG induced only a negligible (1–4 %) change in mRNA expression of either Bak/Bcl-2 or Bad/Bcl-2. Additionally, M. leprae upregulated the expression of anti-apoptotic gene Mcl-1 while, BCG downregulated Mcl-1 mRNA.This study proposes an association between mycobacterium-induced apoptosis in THP-1 cells and the regulation of Bcl-2 family of proteins. M. leprae restricts apoptosis in THP-1 cells by downregulation of Bad and Bak and upregulation of Mcl-1 mRNA expression.Virulent mycobacteria such as Mycobacterium leprae and M. tuberculosis manipulate host cells to persist within them. Apoptosis, or programmed cell death is essential for the homeostatic regulation of cells, restriction of intracellular pathogens and also for stimulation of the host adaptive immune response. Virulent mycobacteria modulate host cell apoptosis to create a protected niche within cells [1-3], and downregulate pro
MT Haghi Ashtiani,M Nakhjavani,A Rabbani,ME Tayyebi
Iranian Journal of Pediatrics , 1992,
Lymphoid papillary hyperplasia in palatine tonsils
Mahdi Bakhshaee,Naser Tayyebi,Mahdi Mouzooni,Navid Noorizadeh
Iranian Journal of Otorhinolaryngology , 2008,
Abstract: Introduction: Lymphoid papillary hyperplasia is a rare benign lesion of the palatine tonsils with a papillary surface configuration so atypical which could clinically be mistaken for a carcinoma or papilloma. Case report: The following report describes a 7-year-old girl with papillomatous lesions of both palatine tonsils.
Common Carotid Artery Intima-media Thickness and Atherosclerotic Plaques in Carotid Bulb in Patients with Chronic Kidney Disease on Hemodialysis: A Case-control Study
Abolhassan Shakeri,Mehdi Abdi,Hamid Tayyebi Khosroshahi,Rohollah Fadaei Fouladi
Pakistan Journal of Biological Sciences , 2011,
Abstract: The Common Carotid artery Intima-Media Thickness (CCIMT) can reflect systemic atherosclerosis in renal patients on hemodialysis. This study aimed to compare CCIMT measured by color Doppler ultrasonography between two groups including dialytic patients and normal subjects. In this case-control setting, 48 patients with Chronic Kidney Disease (CKD) on hemodialysis (case group) and 46 age and sex-matched healthy subjects (control group) were enrolled in this study. Color Doppler ultrasound was used to measure CCIMT and determine presence of atherosclerotic plaques in carotid bulb in both groups. Various laboratory parameters were also determined. Serum levels of triglyceride, total cholesterol, low-density lipoprotein, fasting sugar, ionized calcium, inorganic phosphorus and magnesium were comparable between the two groups. Hypertension and elevated levels of serum C-reactive protein, as well as the mean levels of serum non-fasting homocysteine and phosphate were significantly higher in the case group. Mean levels of serum high-density lipoprotein and albumin were significantly higher in the controls. Mean maximum CCIMT was significantly higher in the case group than in controls (0.730.15 vs. 0.680.08 mm, p = 0.01) even after adjusting for other confounding variables. Frequency of patients with atherosclerotic plaques in carotid bulbs was not significantly different between case and controls. In conclusion, this study showed that CCIMT is significantly higher in CKD patients on hemodialysis comparing with matched normal counterparts. Furthermore, this difference was independent of other conventional risk factors for atherosclerosis.
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