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Search Results: 1 - 10 of 403137 matches for " Seyed M. Navid Khatami "
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Effect of Composition and Morphology on Sensor Properties of Aerosol Deposited Nanostructured ZnO+In2 O3 Films  [PDF]
Leonid I. Trakhtenberg, Seyed M. Navid Khatami, Genrikh N. Gerasimov, Olusegun J. Ilegbusi
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.63026
Abstract: The structural characteristics are investigated of nanoheterogeneous films comprising ZnO, In2 O3 and ZnO + In2 O3 composite produced by aerosol spray pyrolysis technique (SPT). The process utilizes water solutions of zinc chloride and indium nitrate precursors. The X-ray diffraction data show that the SPT process results in polycrystalline films of hexagonal wurtzite type ZnO, and In2 O3 crystals of cubic structure. SPT-synthesized ZnO + In2 O3composites contain mixtures of these crystals. The morphology of the synthesized films is studied by scanning electron microscopy as well as the dependence of morphology on the synthesis conditions, specifically the temperature of the aerosol precipitation and the concentration of the precursors in solutions. The characteristics of nucleation and growth of oxide crystals during the synthesis of ZnO + In2 O3 composite films are also considered. The film with the composition 25 wt% ZnO + 75 wt% In2 O3 contains a large number of small crystal aggregates of arbitrary shape with a high density of contacts between the aggregates and are characterized by a homogeneous structure with high dispersion. Such morphology has high specific surface, which favors high sensory response. In addition, in this range of aggregate composition the relationship between the particles of the catalytically active component- ZnO, cleavage of hydrogen molecule, and In2 O3particles with a high concentration of conduction electrons is close to optimal for the maximum sensory effect in the detection of hydrogen.
Mathematical Modeling and Experimental Validation of Mixed Metal Oxide Thin Film Deposition by Spray Pyrolysis  [PDF]
S. M. Navid Khatami, Olusegun J. Ilegbusi, Leonid I. Trakhtenberg
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.61009
Abstract: The deposition of metal oxide films using Spray Pyrolysis Technique (SPT) is investigated through mathematical and physical modeling. A comprehensive model is developed in the processes including atomization, spray, evaporation, chemical reaction and deposition. The predicted results including particle size and film thickness are compared with the experimental data obtained in a complementary study. The predicted film thickness is in a good agreement with the measurements when the temperature is high enough for the chemical reaction to proceed. The model also adequately predicts the size distribution when the nanocrystals are well-structured at controlled temperature and concentration.
Spray Pyrolysis Deposition of Single and Mixed Oxide Thin Films  [PDF]
Olusegun J. Ilegbusi, S. M. Navid Khatami, Leonid I. Trakhtenberg
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.82010
Abstract: The influence of processing parameters is investigated on the structural characteristics of single and mixed oxides produced by spray pyrolysis technique. The films were synthesized by spraying precursor solutions through a noz-zle onto a heated alumina substrate. The precursor consisted separately of aqueous solutions of tin chloride for SnO2 and zinc chloride for ZnO for single oxide cases, and aqueous solutions of tin chloride and indium nitrate for SnO2 + In2O3 and zinc chloride and indium nitrate solutions for ZnO + In2O3 for mixed oxide cases. The substrate temperature was varied accordingly for each single and mixed case. The films produced were characterized by X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy. The results indicate that a non-homogenous film is formed at low temperature for both single oxides considered. The temperature has significant effect on the composition of the synthesized films of both single oxides below 450. The results for mixed oxides show that the best homogeneous films are obtained for 80 wt% ZnO + 20 wt% In2O3, and 80 wt% SnO2 + 20 wt% In2O3.
On the compactness property of extensions of first-order G?del logic
Seyed Mohammad Amin Khatami
Mathematics , 2014,
Abstract: We study three kinds of compactness in some variants of G\"odel logic: compactness, entailment compactness, and approximate entailment compactness. For countable first-order underlying language we use the Henkin construction to prove the compactness property of extensions of first-order G\"odel logic enriched by nullary connective or the Baaz's projection connective. In the case of uncountable first-order language we use the ultraproduct method to derive the compactness theorem
Additive G?del Logic
Seyed Mohammad Amin Khatami,Massoud Pourmahdian
Mathematics , 2015,
Abstract: In this paper, we further develop ideas initiated in [Khatami, Pourmahdian, and Tavana "From rational G\"{o}del logic to ultrametric logic", J. Logic and computation, 10.1093/logcom/exu065] to study extensions of first-order G\"{o}del Logic, called Additive G\"{o}del Logic. A relevant model theory is developed for this logic to show that it enjoys some nice properties such as Robinson joint consistency theorem. Moreover, it is shown that the class of (ultrametric exhaustive) models with respect to elementary substructure forms an abstract elementary class.
Novel Mitochondrial Homoplasmic T4216C Mutation in Iranian Patients with Friedreich Ataxia
M Heidari,M Khatami
Journal of Shahid Sadoughi University of Medical Sciences , 2010,
Abstract: Introduction: The mitochondrial defects in Friedreich ataxia (FRDA) have been reported in many researches. Friedreich ataxia is an autosomal recessive neurodegenerative disorder caused by decreased expression of the Frataxin protein. Frataxin deficiency leads to excessive free radical production and dysfunction of respiratory chain complexes. Mitochondrial DNA (mtDNA) could be considered as a candidate modifier factor for FRDA disease. It prompted us to focus on the mtDNA and monitor the nucleotide changes of genome which are probably the cause of respiratory chain defects and reduced ATP generation. Methods: We searched the mitochondrial NADH dehydroganase I (ND1) gene by PCR-TTGE and DNA fragments showing abnormal banding patterns were sequenced for the identification of exact mutations. Results: In 20 patients, we detected 3 mtDNA mutations which is novel in Friedreich ataxia. T4216C mutation results in conversion of Tyrosine to Histidine in 313 amino acid locations in ND1 and bioinformatics studies show that ND1 protein loses sixth intramembrane α chain. Conclusion: Our results showed that ND1 gene mutations in FRDA samples are higher than normal controls (P<0.001). It is possible that mutations in mtDNA could constitute a predisposing factor in combination with environmental risk factors that could affect the age of onset and rate of disease progression.
Identification of a Large-scale Mitochondrial DNA Deletion in Iranian Heart Arrhythmia Patients(LQT Syndrome)
M Khatami,M Heidari
Journal of Shahid Sadoughi University of Medical Sciences , 2011,
Abstract: Introduction: Long QT Syndrome is one of the arrhythmic disorders of the heart that causes sudden cardiac death in patients. Most of the investigations have focused on nuclear genome for finding genetic defects in these disorders, but some of the cases with LQTS cannot be explained by mutations of identified genes. It prompted the authors to focus on the mitochondrial DNA and monitor rearrangements which are probably the cause of respiratory chain defects and reduced ATP generation. Methods: The region of the mitochondrial DNA(from 5461 to 15000 nt) was screened by PCR amplification and southern blot followed by DNA sequence analysis. Results: For the first time, a large scale deletion(~8.7 kb) was identified in 30 of the39 patients (76.3%) using Multiplex PCR and Southern blot analysis and demonstrated that this deletion is flanked by 9bp direct repeat. The results also showed that this deletion in patient samples was higher than normal controls(P<0.001). Of the total,8 aged subjects(> 45 years old) had multiple deletions in the region between 5461 and 16150 that may be an age effect on the occurrence of rearrangements on mitochondrial genome. Conclusion: Since heart is highly dependent on oxidative energy generated in mitochondria, such a large scale deletion may be the link between these diseases and dysfunctions of mitochondria.
"Incidence And Epidemiology Of Esophagitis In Children Admitted To Endoscopy Unit Medical Center Of Children In Tehran "
Rafeey M,Khatami GH
Tehran University Medical Journal , 2004,
Abstract: Background: There has been a little attention to pediatrics esophagus problems until recent years. The term esoghagitis can be used to described chemical, infectious, inflammatory, ischemic, immunologic and degenerative abnormalities. Prevalence of reflux esophagitis varies between 2 to 5 percent of general population but little data about its incidence in pediatric age groups. The aim of this study was to evaluate the epidemiology and prevalence of esophagitis and study of symptom, diagnostic measures, therapeutic intervention and prevention of its complication. Materials and Methods: In this prospective and cross sectional study 500 patient under16 years with upper digestive complaints or alteration of their state of health under went upper endoscopy, with special attention paid to esophagus. Results: Among 500 children (205 male, 207 female), pathology reported esophagi is in 325 cases. Majority of the patient were 8 to12 years. Most common complaints was abdominal pain (45/7%) and the second complaints was vomiting (13%), but most common complaints in severe esophagitis was melena (66%) and hematemes(18/8%). Most of patient (63% ) had a mild grade of esophagitis. When difference between endoscopy and pathology compared: Mild esophagitis in endoscopy (67%) ,but in pathology was (63%), moderate esophagitis (14/7%) in endoscopy was (17%) in pathology and severe form 2/8% in endoscopy but (4/9%)in pathology. Conclusion: According to results of our study in children age group with chronic abdominal pain ,vomiting ,excessive regurgitation, failure to thrive, we noticed that esophagitis is common etiologic factor. Histological esophagitis frequently occur in the absence of gross endoscopic findings and we need biopsy and histological examination to confirm diagnosis.
Brain-Based Aspects of Cognitive Learning Approaches in Second Language Learning
Alireza Navid Moghaddam,Seyed Mahdi Araghi
English Language Teaching , 2013, DOI: 10.5539/elt.v6n5p55
Abstract: Language learning process is one of the complicated behaviors of human beings which has called many scholars and experts 'attention especially after the middle of last century by the advent of cognitive psychology that later on we see its implication to education. Unlike previous thought of schools, cognitive psychology deals with the way in which the human mind controls learning. Although it was great development on the way of understanding the nature of learning, cognitive psychologists were criticized by other approaches that this caused mush evolution in cognitivism. On the other hand by the rapid growth of technology our understanding of brain has increased, therefore we know its functions and structures even while working. Neuroscience and its implications to educational domain has been increasing time to time, it means neuroscience and education never were so close to each other. Meanwhile, Brain-based researchers can confirm many learning theories that introduced during the educational great efforts of cognitive and non-cognitive approaches. This paper argues in favor of application of those approaches to language classrooms utilizing as guarantee some of the main perception from brain-based learning theories.
Bankruptcy Prediction Using Memetic Algorithm with Fuzzy Approach: Empirical Evidence from Iran
Gholamreza Karami,Seyed Mostafa Seyed Hosseini,Navid Attaran,Seyed Mojtaba Seyed Hosseini
International Journal of Economics and Finance , 2012, DOI: 10.5539/ijef.v4n5p116
Abstract: Several corporate failures have recently occurred, many have suffered from serious losses and most notably public confidence has deteriorated. In order to facilitate investor’s decision making regarding potential investment opportunities, this paper seeks to demonstrate that it is model specific constraints that limits the usefulness of accounting information, not the nature of variables per se. Thus we develop a Hybrid model which is an adaptive Memetic Algorithm combined with fuzzy approach that generates and optimizes a set of if-then rules for bankruptcy prediction. Data are derived from Tehran Stock Exchange (TSE) data bank, adopting 18 variables all of which are accounting ones, between 2001 and 2009. Four out of five models used in this survey have either accomplished high degree of accuracy or low level of type I error; however experimental results show that in terms of both average accuracy in prediction and occurrence of type I and II errors, fuzzy memetic performs better than GA, MLP, C4.5 and LDA in comparison.
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