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Search Results: 1 - 10 of 714537 matches for " M. A. Golozar "
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Electrochemical and Oxidation Behavior of Yttria Stabilized Zirconia Coating on Zircaloy-4 Synthesized via Sol-Gel Process
S. Rezaee,Gh. R. Rashed,M. A. Golozar
International Journal of Corrosion , 2013, DOI: 10.1155/2013/453835
Abstract: Sol-gel 8?wt.% Yttria Stabilized Zirconia (YSZ) thin films were prepared on zirconium (zircaloy-4?alloy) by dip-coating technique followed by heat treating at various temperatures (200°C, 400°C, and 700°C) in order to improve both electrochemical corrosion and high temperature oxidation properties of the substrate. Differential thermal analysis and thermogravimetric analysis (DTA-TG) revealed the coating formation process. X-ray diffraction (XRD) was used to determine the crystalline phase structure transformation. The morphological characterization of the coatings was carried out using scanning electron microscopy (SEM). The electrochemical behavior of the coated and uncoated samples was investigated by means of open circuit potential, Tafel, and electrochemical impedance spectroscopy (EIS) in a 3.5?wt.% NaCl solution. The homogeneity and surface appearance of coatings produced was affected by the heat treatment temperature. According to the corrosion parameters, the YSZ coatings showed a considerable increase in the corrosion resistance, especially at higher heat treatment temperatures. The coating with the best quality, from the surface and corrosion point of view, was subjected to oxidation test in air at 800°C. The coated sample presented a 25% reduction in oxidation rate in comparison with bare substrate. 1. Introduction Because of many excellent bulk properties like low thermal neutron capture cross section, favorable mechanical properties and good corrosion resistance even at high temperatures, zirconium and its alloys are widely used in nuclear reactors as fuel cladding and as reactor structural elements, chemical engineering, and lately in biomedical applications. For fuel cladding applications, the alloys of choice are zircaloy-2 (Zr-2) and zircaloy-4 (Zr-4). In fuel deep geological repository, used fuel bundles and the associated Zr cladding are encapsulated in durable containers and the containers are sealed in an engineered vault at a depth of hundreds of meters in a stable low permeability rock mass. Ground water composition especially in crystalline and sedimentary rock types contains NaCl. In a failed container, zirconium is in contact with NaCl solution [1–4]. So, they are somehow subject to corrosion and their specific surface properties (e.g., corrosion, oxidation, etc.) should be improved [2, 4]. Surface modification of materials permits independent optimization of bulk and surface properties. Among all surface modification techniques such as chemical vapor deposition [5, 6], physical vapor deposition [7], plasma [8], ion
Diabetes Mellitus and Its Correlates in an Iranian Adult Population
Asieh Golozar, Hooman Khademi, Farin Kamangar, Hossein Poutschi, Farhad Islami, Christian C. Abnet, Neal D. Freedman, Philip R. Taylor, Paul Pharoah, Paolo Boffetta, Paul J. Brennan, Sanford M. Dawsey, Reza Malekzadeh, Arash Etemadi
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0026725
Abstract: The rising epidemic of diabetes imposes a substantial economic burden on the Middle East. Using baseline data from a population based cohort study, we aimed to identify the correlates of diabetes mellitus (DM) in a mainly rural population from Iran. Between 2004 and 2007, 50044 adults between 30 and 87 years old from Golestan Province located in Northeast Iran were enrolled in the Golestan Cohort Study. Demographic and health-related information was collected using questionnaires. Individuals' body sizes at ages 15 and 30 were assessed by validated pictograms ranging from 1 (very lean) to 7 in men and 9 in women. DM diagnosis was based on the self-report of a physician's diagnosis. The accuracy of self-reported DM was evaluated in a subcohort of 3811 individuals using fasting plasma glucose level and medical records. Poisson regression with robust variance estimator was used to estimate prevalence ratios (PR's). The prevalence of self-reported DM standardized to the national and world population was 5.7% and 6.2%, respectively. Self-reported DM had 61.5% sensitivity and 97.6% specificity. Socioeconomic status was inversely associated with DM prevalence. Green tea and opium consumption increased the prevalence of DM. Obesity at all ages and extreme leanness in childhood increased diabetes prevalence. Being obese throughout life doubled DM prevalence in women (PR: 2.1; 95% CI: 1.8, 2.4). These findings emphasize the importance of improving DM awareness, improving general living conditions, and early lifestyle modifications in diabetes prevention.
An Investigation on Dislocation Density in Cold-Rolled Copper Using Electrochemical Impedance Spectroscopy
Elyas Rafiee,Mansour Farzam,Mohammad Ali Golozar,Ali Ashrafi
ISRN Corrosion , 2013, DOI: 10.1155/2013/921825
Abstract:
An Investigation on Dislocation Density in Cold-Rolled Copper Using Electrochemical Impedance Spectroscopy
Elyas Rafiee,Mansour Farzam,Mohammad Ali Golozar,Ali Ashrafi
ISRN Corrosion , 2013, DOI: 10.1155/2013/921825
Abstract: Variation of electrochemical impedance with dislocation density was investigated using electrochemical impedance spectroscopy (EIS). For this purpose, EIS measurements were carried out on 10, 20, 30, 40, and 50% cold-rolled commercially pure copper in 0.1?M NaCl (pH = 2) solution. Nyquist plots illustrated that the electrochemical reactions are controlled by both charge transfer and diffusion process. Increasing dislocation density, the magnitude of electrochemical impedance of samples was decreased. Decreasing magnitude of impedance at intermediate frequencies indicated increasing double-layer capacitance. Charge transfer resistance decreased from value 329.6??cm2 for annealed sample to 186.3??cm2 for sample with maximum dislocation density ( ? ). Phase angles were lower for samples that contained more dislocation density, indicating more tendencies to loss of electrons and releasing atoms into electrolyte. 1. Introduction It has been reported that after deformation of a metal more than yield limit, hardening occurs which is due to multiplication and rearrangement of dislocations and the more severe the cold deformation, the more generation of dislocations [1–4]. Tensile properties of metals such as yield strength, ultimate tensile strength, and ductility depend heavily on density of dislocations. Also, dislocation density plays a significant role on brittle to ductile transition, fatigue, hardness, work hardening, and plastic behavior of metals and alloys [5–8]. Furthermore, dislocations have considerable effect on physical properties of metals such as density [9–12], thermal conductivity [13, 14], and electrical resistivity [9, 13, 14]. In this respect, some researchers [5, 15, 16] have investigated density of dislocations by ultrasound waves and have proposed some relationships between dislocation density and changes in the speed of elastic waves propagation. Sablik and Landgraf [17, 18], Kobayashi et al. [19], and Yaegashi [20] reported some relationships between dislocation density and magnetic properties. Kikuchi et al. [21] investigated the relation between AC permeability and dislocation density in pure iron as well. Also, other researchers tried to correlate dislocation density with stored energy and critical transformation temperatures using differential scanning calorimetry [4, 7, 22] and high-resolution dilatometry [23], respectively. The strain field and energy of dislocation line intersects with metal surface increase the susceptibility of the metal to corrosion [24–26]. Since corrosion is an electrochemical degradation, electrochemical
Study on Parasexual Recombination between Pyricularia oryzae and Pyricularia grisea  [PDF]
M. A. Monsur, M. Kusaba
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.93023
Abstract: Rice blast fungus is notorious for changeability in pathogenicity, but it lacks sexual life cycle. It can be postulated that such an imperfect fungus has another mechanism for generating genetic variations. Recent studies concerning comparative genomics reveal that parasexual recombination may play important role in the evolution of rice blast fungus. To observe the parasexualism of rice blast (Pyricularia oryzae) and crabgrass blast (Pyricularia grisea) fungus double inoculation and punch method were applied in this experiment. A total of 520 isolates collected from the double inoculated lesions was subjected to PCR-RFLP analysis of the ITS region to identify subcultures of the inoculated rice blast isolates. As a result, four isolates from the three double inoculated lesions with SA13-1ME and TP106 were identified as subcultures of TP106. To access the recombination genotypes, a total of 17 isolates from the three lesions was subjected to MAGGY-DNA fingerprint analysis. However, recombinant DNA fingerprint patterns between TP106 and SA13-1ME were not detected among the 17 isolates. Although TP022 was not recovered from the double inoculated lesions, the fact that TP106 was recovered from the double inoculated lesion indicates that rice blast fungus can invade and colonized in blast lesion on crabgrass. The opportunistic infection on the double inoculated lesions observed in this study potentially provides new insight into the life cycle of rice blast pathogen.
Economic Valuation of Sea Level Rise Impacts on Agricultural Sector: Damietta Governorate, Egypt  [PDF]
M. A. Abdrabo, M. A. Hassaan
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.52012
Abstract:

The Nile Delta is considered to be one of the most vulnerable river deltas to Sea Level Rise (SLR) in the world. SLR is expected to affect large agricultural areas of the Nile Delta, either through inundation or higher levels and salinity of groundwater. It could be argued that such impacts would augment the problems experienced already in the area in terms of high groundwater table and salinity levels. In order to guide policy and decision making, especially in terms of assessing the economics of various adaptation options, there is a need to provide estimates of potential economic damage that could result from such changes. The paper in hand aims to estimate the economic value of potential primary impacts of higher levels of groundwater table due to expected SLR on agriculture productivity in Damietta Governorate as one of the Nile Delta coastal governorates. To conduct such an assessment, relationship between groundwater table level and agricultural productivity was first investigated in relevant literature. This was followed by reviewing prevailing conditions in the agricultural sector in the study area. Thereafter, a regression analysis for the main crops in the study area, between crop yield and groundwater table levels, was conducted. Based on the developed regression, a GIS (Geographic Information System)-based hydrological model, and a production economic model, were employed to assess economic value of higher levels of groundwater table impacts on agriculture productivity. It was found that future accumulative crop yield loss was estimated, using segmented linear regression, up to the year 2100 to be as much as L.E. 6.43 billion. It is worth mentioning that these

Contribution of Animal Agriculture to Greenhouse Gases Production in Swaziland  [PDF]
A. M. Dlamini, M. A. Dube
American Journal of Climate Change (AJCC) , 2014, DOI: 10.4236/ajcc.2014.33024
Abstract: The economy of Swaziland is depended on agriculture. In 2009, it was reported that agriculture, forestry, and manufacturing contributed 42% of Swaziland’s Gross Domestic Product (GDP). Besides economic importance, animal agriculture is important for food production and life sustenance. It is also viewed as a symbol of wealth and high social status particularly for the rural folks. Despite the merits of agricultural activities, agricultural production, particularly animal production, has been incriminated for an accelerated emission of greenhouse gases. These gases are responsible for global warming and climate change. The aim of this study was to determine the contribution of animal agriculture to greenhouse gases production and to elicit adaptation strategies to climate change and the role of modern technologies as mitigating measures. The minor and major greenhouse gases produced by farm animals were computed using the IPCC spread sheet for calculation of greenhouse gases emissions. The minor greenhouse gases produced by farm animals were NOx and CO2 and the major gasses included CH4 and N2O. The greenhouse gas that was emitted the most by farm animals was CH4, 24 Gg or 600 CO2e per annum. Ruminants were the major producers of methane. The producers of the least greenhouse gases emissions were non ruminants. Livestock produced 0.87 Gg of N2O per annum, a global warming potential of 259 CO2e. Feeding ammoniated straw and silage inoculating with transgenic rumen bacteria, animal breeding and manure storage techniques, use of biogas digester with methane gas recovery and emphasis on non ruminant production were possible strategies that could be employed to reduce greenhouse gases production from the livestock sector. It was recommended that feed preservation technologies, selection strategies, water harvesting, storage and recycling strategies and intensive livestock production systems could be used as adaptation strategies to climate change in livestock production.
Diagnostic Study of Nickel Plasma Produced by Fundamental (1064 nm) and Second Harmonics (532 nm) of an Nd: YAG Laser  [PDF]
M. Hanif, M. Salik, M. A. Baig
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.330203
Abstract: In the present work, we have studied the spatial evolution of the nickel alloy plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Q-switched Nd: YAG laser by placing the target material in air at atmospheric pressure. The four Ni I lines at 335.10 nm, 394.61 nm, 481.19 nm and 515.57 nm are used for the determination of electron temperature (Te) using Boltzmann plot method. The electron temperature is calculated as a function of distance from the target surface for both modes of Nd: YAG laser. In case of fundamental (1064 nm) mode of laser, the temperature varies from 13700 - 10270 K as the distance is varied from 0 to 2 mm. Whereas, in the case of second (532 nm) mode of laser it varies from 13270 - 9660 K for the same distance variation. The electron temperature has also been determined by varying the energy of the laser from 90 to 116 mJ, for the fundamental (1064 nm) harmonic and from 58 to 79 mJ for the second (532 nm) harmonics of the laser. The temperature increases from 14192 to 15765 K in the first case and from 13170 to 14800 K for the second case. We have also studied the spatial behavior of the electron number density in the plasma plume. The electron number density (Ne) in the case of fundamental (1064 nm) harmonic of the laser having pulse energy 125 mJ varies from 2.81 × 1016 to 9.81 × 1015 cm-3 at distances of 0 mm to 2.0 mm, whereas, in the case of second (532 nm) harmonic, with pulse energy 75 mJ it varies from 3.67 × 1016 to 1.48 × 1016 cm-3 for the same distance variation by taking Ni I line at 227.20 nm in both the cases.
Determination of the Metastable Zone Width, Nucleation Kinetics, Structural and Optical Properties of KCl Doped KAP Crystal  [PDF]
M. A. Rahman, M. M. Rahman
Journal of Crystallization Process and Technology (JCPT) , 2015, DOI: 10.4236/jcpt.2015.52005
Abstract: Slow evaporation method was used to grow pure and KCl (10 mol%) doped KAP single crystal. The solubility and metastable zone width of aqueous solutions of pure and KCl (10 mol%) doped KAP crystal were evaluated to analyze the crystallization process. Measuring the induction period τ, the critical nucleation parameters like interfacial energy (σ), energy of formation of the critical nucleus (ΔG*) were determined using the classical theory of nucleation. The structural properties and optical constants of the grown crystals have been put to test and observed that the addition of KCl results in an enhancement of properties of the crystal. Grown crystals were characterized by powder X-ray diffraction. FTIR spectra confirmed the presence of KCl in pure KAP crystal. UV- Visible spectroscopic studies revealed that addition of KCl in pure KAP crystal increased transparency from 75% to 80%. The analysis of the optical absorption data revealed the presence of both indirect and direct transitions and both of these band gaps increased with the addition of KCl. The transmittance data was analyzed to calculate the refractive index, oscillator energy, dispersion energy, electric susceptibility, zero-frequency dielectric constant and both the real and imaginary parts of the dielectric permittivity as a function of photon energy. The moments of ε(E) were also determined. The dispersion i.e. spectral dependence of the refractive index was discussed according to the single-effective oscillator model proposed by Wemple and DiDomenico.
An Integral Collocation Approach Based on Legendre Polynomials for Solving Riccati, Logistic and Delay Differential Equations  [PDF]
M. M. Khader, A. M. S. Mahdy, M. M. Shehata
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.515228
Abstract:

In this paper, we propose and analyze some schemes of the integral collocation formulation based on Legendre polynomials. We implement these formulae to solve numerically Riccati, Logistic and delay differential equations with variable coefficients. The properties of the Legendre polynomials are used to reduce the proposed problems to the solution of non-linear system of algebraic equations using Newton iteration method. We give numerical results to satisfy the accuracy and the applicability of the proposed schemes.

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