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مرکز اطلاعات علمی SID1
اسکوپوس
مرکز اطلاعات علمی SID
ریسرچگیت
strs
Issue Info: 
  • Year: 

    2009
  • Volume: 

    17
  • Issue: 

    3
  • Pages: 

    1-9
Measures: 
  • Citations: 

    0
  • Views: 

    1417
  • Downloads: 

    443
Abstract: 

Introduction: Salmonella Bacterium is not only a causative factor of typhoid fever, enterocolitis, and salmonellosis, but it is also a zoonotic infection. This bacterium is a major health problem throughout the world, and is especially prevalent in developing countries. Therefore, rapid diagnosis of salmonella can prevent its outbreak. Different techniques are used for the diagnosis of  Salmonella bacteria, such as; culture, biochemical, serological, ELISA, Widal, immunofluorescence and molecular methods like PCR and Real time PCR,all of which are difficult, time-consuming, and expensive. Thus, our study was designed to evaluate the LAMP (Loop-mediated Isothermal DNA amplification method) for detection of salmonella bacteria.Materials & Methods: In this study, we examined 7 different strains of salmonella.  The DNA was extracted by standard methods and amplified with specific primers by PCR and set of primers for LAMP in single temperature in very simple thermal block made in Iran. The amplified products were detected by gel electrophoresis and LAMP products were visualized by their turbidity with naked eye.Findings: Conventional PCR method for detection of Salmonella needs standard thermocylcer and takes 3 hours, but using  LAMP method, we were able to amplify and detect salmonella in simple thermoblock, taking much less time. After optimization of the process, it was, soon, possible to detect and identify Salmonella typhi bacteria within 90 minutes. This method is also 10 times more sensitive than that of the PCR.Discussion & Conclusion: According to the results, comparing LAMP method for detection and identification of Salmonella with conventional PCR, we have been able to determine the simplicity, speed and the superior sensitivity of the LAMP method. This Method is more simple, faster and cheaper. Non-dependence of cycle's temperature and thermo-cycling and replacement with one thermo block which is very simple, inexpensive and made inside the country, can be considered another advantage of the LAMP method.

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Issue Info: 
  • Year: 

    2017
  • Volume: 

    26
  • Issue: 

    145
  • Pages: 

    45-53
Measures: 
  • Citations: 

    0
  • Views: 

    478
  • Downloads: 

    446
Abstract: 

Background and purpose: Fasciola hepatica and Fasciola gigantica are common liver flukes which affect both human and livestock worldwide. In this study we evaluated the loop-mediated Isothermal amplification (LAMP) assay for detection and discrimination of Fasciola species.Materials and methods: Fifty adults of Fasciola worms were isolated from sheep and cattle liver form abattoirs in Mazandaran province. A total of 8 primer sets for LAMP was designed to amplify the 28S ribosomal RNA gene of Fasciola sp. Conventional LAMP was carried out in a 20mI reaction mixture under Isothermal condition at 60oC for 90 minutes. Amplification result was observed by monitoring the turbidity by naked-eye, using fluorescent dye and gel electrophoresis. The specificity of LAMP method for detecting Fasciola sp. was tested by amplification of Dicrocoelium dendriticum, Trichostrongylus colubriformis, and Echinococcus granulosus DNA templates. To evaluate the detection limit of LAMP assay in detecting Fasciola genus, serial dilution of the extracted DNA was used.Results: A positive LAMP reaction by the specific primers of two species produced many bands of different sizes in 600C after 90 min. The optimal assay conditions were established with no reaction with other parasites’ DNA. The detection limit of this LAMP assay was 1 pg DNA/tube. The result of turbidity and fluorescent dye detection were consistent with agarose gel electrophoresis. Conclusion: Our results demonstrated that LAMP is a rapid, cost-effective, highly specific, easy, and reliable method for differentiation of Fasciola sp. in epidemiological and clinical researches on human and domestic animals in endemic regions of fasciolosis.

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Author(s): 

AZADI M. | FARRAHI G.H.

Issue Info: 
  • Year: 

    2016
  • Volume: 

    9
  • Issue: 

    3
  • Pages: 

    517-530
Measures: 
  • Citations: 

    0
  • Views: 

    586
  • Downloads: 

    262
Abstract: 

In this article, failure and fracture mechanisms in an aluminum alloy (which has been used in diesel internal combustion engines), with and without ceramic thermal barrier coatings, have been investigated under Isothermal and non-Isothermal fatigue loadings. In this research, the base material is an aluminum-silicon-magnesium alloy and the thermal barrier coating includes a metallic bond coat layer with 150 mm thickness and a top coat layer, made of zirconia stabilized 8%wt. yttria with 350 mm thickness, which is applied on the substrate by the plasma thermal spray method. In order to study the failure and the sensitivity analysis, Isothermal fatigue tests (or low-cycle fatigue tests at constant temperatures) and non-Isothermal fatigue tests (or out-of-phase thermo-mechanical fatigue tests) were performed on test specimens. Then, fracture mechanisms in the aluminum alloy, were investigated by the scanning electron microscopy. After checking the fatigue damage and the failure analysis, the sensitivity of the material lifetime was studied based on different parameters (the temperature and the strain). Based on obtained results, the fracture surface of the aluminum alloy had dimples and therefore, its fracture was ductile. In thermal barrier coating, the damage mechanism was the separation between the substrate and the bond coat layer. The highest sensitivity was related to the strain parameter in fatigue tests of the aluminum alloy (with and without coating).

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گارگاه ها آموزشی
Author(s): 

KADKHODA N. | JAFARI H.

Issue Info: 
  • Year: 

    2016
  • Volume: 

    6
  • Issue: 

    1
  • Pages: 

    43-52
Measures: 
  • Citations: 

    0
  • Views: 

    336
  • Downloads: 

    166
Abstract: 

The Kudryashov method to look for the exact solutions of the nonlineardifferential equations is presented. The Kudryashov method is applied tosearch for the exact solutions of the Liouville equation and the Sinh-Poissonequation. The equations of magnetohydrostatic equilibria for a plasma in agravitational eld are investigated analytically. An investigation of a familyof Isothermal magnetostatic atmospheres with one ignorable coordinate cor-responding to a uniform gravitational eld in a plane geometry is carried out. The distributed current in the model J is directed along the x-axis where xis the horizontal ignorable coordinate. These equations transform to a singlenonlinear elliptic equation for the magnetic vector potential u. This equationdepends on an arbitrary function of u that must be speci ed.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-6
Measures: 
  • Citations: 

    0
  • Views: 

    59691
  • Downloads: 

    18420
Abstract: 

Swirl flame stabilization is widespread among burners’ manufacturers, but the complex flow patterns are not yet fully understood. The interaction of two confined swirling jets leads to the formation of two recirculation zones being the flame located on the shear layer between the both zones. In such conditions, the lean mixtures can be burned producing low emissions. In the present study, flow structure and turbulent mixing of two Isothermal coaxial jets are investigated using Large Eddy Simulation (LES).This is a challenging tool to achieve accuracy but it requests demanding spatial resolution and special treatment of results. By contrasting time-averaged radial profiles with experimental data of a classical benchmark, the model is validated. Results show that LES is able to reproduce the basic features of the flow pattern. Besides, the spectra analysis of instantaneous flow fields provides not only the energy decay but also the most energetic flow structures.

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    97-102
Measures: 
  • Citations: 

    0
  • Views: 

    26739
  • Downloads: 

    11629
Abstract: 

A thorough study has been performed on FINEMET type of ribbons with nominal composition of Fe70.5Cr3Cu1Nb3Si13.5B9 synthesized by rapid solidification technique. X- ray diffraction studies have been performed to identify the phases and to determine the grain size using Scherrer’s formula. Grain size increased with increasing annealing time and annealing temperature when the amorphous ribbon is annealed close to the crystallization temperature. The soft magnetic properties of this nanocrystalline alloy annealed at 425-560°C for 1 to 60 minutes at regular interval are investigated. Annealing time has great influence on permeability. The permeability increases gradually from 1 to 25 minutes then decreases. Curie temperature of the amorphous sample was found to be 276°C, which increased to 292°C gradually with increasing annealing temperature up to 475°C and then decreases for further increases. The results of the experimental observations are explained on the basis of existing theories of nanocrystalline amorphous metallic ribbons.

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strs
Author(s): 

MASHAK AREZOU | GHAEE AZADEH

Issue Info: 
  • Year: 

    2015
  • Volume: 

    49
  • Issue: 

    1
  • Pages: 

    21-29
Measures: 
  • Citations: 

    0
  • Views: 

    20000
  • Downloads: 

    18390
Abstract: 

Isothermal melt crystallization kinetics of PVDF was investigated by differential scanning calorimetry. Thin PVDF film has been fabricated by the solvent casting technique using dimethylformamide (DMF). Then, the samples were melted and subsequently crystallized in the range of the crystallization temperature (Tc) between 138 and 145oC. The crystallization kinetics was derived from Avrami equation. Avrami parameter (n) was found in a range from 1.5 to 2.4 and the values of the crystallization rate parameters (k) increased with decreasing Tc. So the crystallization rate parameters suggested that PVDF crystallize slower with increasing of Tc. The Hoffman–Weeks equation has used to approximate the equilibrium melting point of PVDF which was concluded to be 182oC. Likewise, the activation energy was estimated to be 103.2 kJ/mol for Isothermal crystallization. In this research, Lauritzen- Hoffmann theory was employed to analyze crystallization kinetics. Accordingly, regime "I" found appropriate to describe the present case of PVDF crystallization.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    33
  • Issue: 

    4
  • Pages: 

    89-97
Measures: 
  • Citations: 

    0
  • Views: 

    40910
  • Downloads: 

    20089
Abstract: 

In this paper, a reaction system consisting of two parallel, non-Isothermal autocatalytic reactions in a Continuous Stirred Tank Reactor (CSTR) has been considered. Reactor chaotic behavior is possible for a certain values of system parameters. Two types of controllers are designed and compared in order to control both the reactor temperature and the product concentration. The first controller is a linear state feedback type, designed based on the linearized model of the process and the second one is designed based on the Global Linearizing Control (GLC) strategy. Since the system states are not measured completely, a nonlinear observer has been used to estimate the system states. Finally, computer simulation is performed to show the effectiveness of the proposed schemes. Simulation results indicate that the GLC-based control scheme is more effective for set point tracking, while the control scheme obtained using the linearized model of the process is more efficient for load rejection purposes.

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Author(s): 

Roy Jagannath | MAITRA SAIKAT

Issue Info: 
  • Year: 

    2019
  • Volume: 

    38
  • Issue: 

    4
  • Pages: 

    91-100
Measures: 
  • Citations: 

    0
  • Views: 

    23483
  • Downloads: 

    20293
Abstract: 

Aluminosilicate gel precursor having mullite composition was synthesized from inorganic salts of aluminum and silicon by employing the sol-gel method. Chemical analysis, surface area and bulk density measurements were performed to characterize the dried gel. The course of the mullitization was examined by FT-IR analysis which confirmed the diphasic nature of the gel. SEM and XRD analysis were preformed to study microstructure and phase development. ThermoGravimetric (TG) analysis of the dried gel was performed at multiple heating rates and from the results obtained; kinetics of thermal dehydration was studied by applying Friedman differential and Kissinger-Akahira-Sunose integral isoconversional procedures. It was observed that the total dehydration process of the gel was accomplished by two different stages and both the stages followed second order rate kinetics. The first stage was assigned to the dehydration of silicon hydroxide gel whereas the second stage was associated with aluminum hydroxide gel dehydration.

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Author(s): 

RAZAVI NOURI M. | HAY J.N.

Issue Info: 
  • Year: 

    2007
  • Volume: 

    16
  • Issue: 

    2 (80)
  • Pages: 

    105-112
Measures: 
  • Citations: 

    0
  • Views: 

    39025
  • Downloads: 

    40832
Abstract: 

Acomparative study has been made on the Isothermal crystallization kinetics and melting behaviour of a metallocene linear low density polyethylene (m-LLDPE) and a metallocene very low density polyethylene (m-VLDPE). The end-surface free energy of the crystal and the lamella thickness distribution were determined for m-LLDPE and m-VLDPE by using the Isothermal crystallization rate constants. The degree of short chain branching of both polyethylenes was then calculated and found to be in agreement with the data obtained previously using other methods. Moreover, no distinction could be made between primary and secondary nucleations of the both polymers using the equation proposed by Turnbull and Fisher. Crystallization at a temperature for different time periods has also showed the existence of molecular segregation for both polymers.

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