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Showing 15 results for Rafati


Volume 3, Issue 3 (9-2014)
Abstract

Samples of leaf, twig and fruit from ‘Mexican’ lime (Citrus aurantifolia) and grapefruit (Citrus paradisi) with symptoms of bacterial canker were collected from different provinces throughout Iran during spring and summers of 2010 and 2011. Yellow, gram-negative colonies were isolated from infected tissue samples. Results of pathogenicity assays indicated that some isolates incited tissue hyperplasia, hypertrophy and raised callus-like lesions typical of canker in hosts while other isolates stimulated flat necrotic and water-soaked lesions on leaves. Candidate samples of each group were identified according to morphological and physiological characteristics. Detections were also made using specific primers and partial sequencing of 16SrDNA for Pantoea group and gyrB for Xanthomonas group. Results showed that one group was characterized as the typical Xanthomonas citri subsp. citri strain while the other group containing most of the isolates was identified as Pantoea agglomerans. Samplings done frequently in different seasons revealed the presence of high populations of P. agglomerans with bacterial canker, especially in warmer and drier regions. These bacteria were able to incite canker-like symptoms on grapefruit seedlings and could be reisolated after two months.

Volume 7, Issue 3 (12-2017)
Abstract

Talent management is defined as a system for identifying, hiring, training, promoting and retaining talented people in order to optimize organizational capacity to achieve business outcomes. This study tends to achieve a theory in the field of talent management for better understanding of this phenomenon. Research has been performed in the aviation industry of Islamic Republic of Iran in a combinatorial mode. Theoretical sampling in quality study performed using snowball method while random sampling opted for quantitative study. Community of 13 and 212 personnel have been participated in quality and quantity study respectively. The validity and reliability of research tools were desirable. Measures to keep talented employees have been achieved using data-driven approach. The results showed that the quality of talent-driven architecture plays the key role in the paradigmatic model. The conceptual model using questionnaires data in the quality phase and statistical techniques, descriptive, analytical, PLS and structural equation modeling were analyzed. Finally, the research results presented with regard to the interpretation of the combined methods

Volume 8, Issue 1 (6-2006)
Abstract

Purpose: Evaluation of humoral and cellular immune responses of naturally infected dogs against type I (rCPB) (Recombinant cycsteine proteinase B), and II (rCPA) (Recombinant cycsteine proteinase A) recombinant cysteine proteinases and C-terminal extension (CTE) of Leishmania infantum (L. infantum). Materials and Methods: In this study, fourteen infected dogs (7 with symptoms, 7 asymptomatics) from an endemic area and three uninfected dogs from a nonendemic region were selected and their humoral and cellular responses against type I and II recombinant cysteine proteinases, C-terminal extension (CTE) and F/T of Leishmania infantum were evaluated using the ELISA and lymphocyte proliferation assay, respectively. The level of specific IgG isotypes (IgG1 and IgG2) and lymphocyte proliferative response against rCPA, rCPB, CTE and Freezed/Thawed lysate (F/T) of L. infantum were examined. Results and Discussion: The results showed that in both of the symptomatic and asymptomatic dogs there is a high lymphoproliferative response to F/T antigens and moderate responses were observed when rCPs (Recombinant cycsteine proteinase) (rCPA and rCPB) and CTE were used. The level of antibody (total IgG, IgG1 and IgG2) recognition toward rCPA was low in the both groups of the dogs. In contrast, the CTE stimulates similarly as the CPB both of the humoral and cellular responses of all the infected animals and the level of total IgG and IgG2 isotypes against these antigens compared to the IgG1 was higher in the asymptomatic dogs. Since, the CTE is the terminal fragment of the CPB, it seems that the immunogenicity of the CPB is dependent on the CTE. Conclusion: The results of our investigation indicates that the CPB and CTE stimulate both humoral and cellular immune responses of L. infantum infected dogs, wherase the CPA is a weaker immunogen.

Volume 10, Issue 2 (Spring 2024)
Abstract

Background: Methicillin-resistant staphylococci (MRS) are regarded as a global public health threat. Physicians are restricted in their treatment options due to resistance to aminoglycosides and tetracycline derivatives. This study investigated aminoglycoside and tetracycline derivative resistance among Staphylococcus isolates in Shiraz, southwestern Iran.
Materials & Methods: Totally, 113 staphylococcal isolates were recovered from different clinical samples in Nemazee Teaching Hospital from October 2019 to January 2020. Kirby-Bauer disc diffusion method was performed to assess the antimicrobial susceptibility of the isolates against aminoglycoside and tetracycline antibiotics. Aminoglycoside-modifying enzymes (AMEs) and tet genes were investigated among staphylococci isolates using polymerase chain reactions (PCR).
Findings: MRS prevalence among Staphylococcus isolates was 61% (69 of 113). The majority of MRS isolates were obtained from blood (39.1%; 27 of 69) and urine (17.4%; 12 of 69). The highest prevalence of MRS isolates was among emergency room patients (34.8%; 24 of 69). The highest resistance of MRS isolates was against tobramycin (59.4%; 41 of 69) and tetracycline (55.1%; 38 of 69). The prevalence of tetM and aac (6')-Ie-aph (2'') genes was significantly higher among MRS compared with methicillin-sensitive staphylococci (MSS) (87.5% vs 12.5% and 95.6% vs 6.4%, respectively) (p= .001).
Conclusion: The prevalence of MRS isolates, including methicillin-resistant S. aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (MRCoNS), was remarkable in Shiraz as the center of medical services in the southwest of Iran. Furthermore, these MRS isolates were highly resistant to aminoglycosides and tetracyclines. Therefore, antimicrobial stewardship is necessary to address health conditions.


Volume 11, Issue 0 (بهار و تابستان 87- 2008)
Abstract

Objective: DNA vaccines have been widely used to develop immunity against various pathogens including parasites and viruses. The potential of DNA vaccine to induce an effective immune response is related to the expression levels of the encoded protein in eukaryotic cells. Therefore, optimization of plasmid DNA delivery system is a major concern in protein expression in order to make an efficient DNA vaccination. Non-viral vectors such as polymers and cationic peptides have been recently known as efficient gene delivery systems into eukaryotic cells. In this study, transfection efficiency of HPV16E7 gene was evaluated by two non-viral delivery systems in vitro. Materials and Methods: DNA construct encoding HPV16E7 (pEGFP-E7) was prepared in large scale with high purity. Then, two delivery systems including polymer PEI 25 kDa and polymer-peptide hybrid as PEI600-Tat conjugate were used to compare their efficiency for HPV16E7 DNA transfection in vitro. Results: Our data demonstrated that both delivery systems including PEI 25 kDa and PEI600-Tat are efficient tools for E7 gene transfection. Although the level of transfected COS-7 cells is higher using PEI 25 kDa in comparison with PEI600-Tat. Conclusion: Our study indicated that PEI potency for E7 gene transfection was higher than PEI600-Tat in vitro, but its toxicity was obstacle in vivo. Therefore, with regard to low toxicity of PEI600-Tat delivery system and its potent plasmid DNA delivery, it is critical issue to study its potency as new delivery system in vivo.

Volume 17, Issue 4 (7-2015)
Abstract

The aim of this study was evaluation of phytochemical components, antioxidant activity, and antibacterial effects of basil (Ocimum basilicum L.) essential oil (BEO) in vitro. The lipid oxidation of the meat and antibacterial effects of BEO were also evaluated in beef burger product. In this empirical study, essential oil of the basil was isolated by hydrodistillation. Then, BEO was analyzed by gas chromatography-flame ionization detector (GC-FID) and gas chromatography/mass spectrometry (GC-MS). The effect of different concentrations of BEO (0.00, 0.062, 0.125, and 0.25%) at 4±1ºC temperature and storage time of up to 12 days was evaluated on lipid oxidation, anti Staphylococcus aureus activity, and organoleptic effects in beef burger. The main compounds in BEO were methyl chavicol (85.19%), 1,8 cineol (3.96%), trans-alpha bergamotene (1.18%) and linalool (1.03%). In the storage temperature (4±1ºC), the BEO decreased the growth rate of S. aureus in beef burger (P< 0.05). Also, overall acceptance rate in the beef burger containing 0.125% BEO created a better sense in the product (P< 0.05). No significant differences were observed after adding different concentrations of essential oil to decrease lipid oxidation in raw beef burger (P> 0.05). Therefore, this essential oil might be used as antibacterial agent and flavor enhancer in meat products such as beef burger. 

Volume 18, Issue 115 (September 2021)
Abstract

In the present study, the optimization process of phenolic compounds extraction and antioxidant activity (DPPH radical-scavenging assay, FRAP test, and oxidative stability index) of Pistacia khinjuk fruits was evaluated using ultrasound waves through response surface methodology (RSM). To optimize the extraction process from the central composite design with three independent variables including time (5, 27.5 and 50 minutes), temperature (25, 45 and 65 ° C) and ethanol ratio in water-ethanol solvent (0, 50 and 100% ) was used. Significant effects of independent variables on the extraction of phenol compound, DPPH radical scavenging power, FRAP test and OSI of P.khinjuk fruit extract, with the regression coefficients of 97.65, 98.09, 98.62 and 98.38 %, respectively, were noted. Among the independent parameters, ethanol concentration was the most effective parameter because two effects of quadratic and linear were observed in the proposed models of different tests. The interaction effect between different paprameters was not observed in the models of this study, too. It was also the strongest model for the phenolic compounds extraction test; because in this test, in addition to the linear effect of independent parameters that were common to all tests, a quadratic effect was also observed in the parameters of time and ethanol concentration. Also, the best antioxidant activity of P.khinjuk fruit was obtained by using the ultrasonic wave for 50 minutes at 65 ºC and with 57.7% v/v ethanol/water solution. Finally, it was found that the results of experimental tests were close to the values predicted by the response level method.

Volume 19, Issue 2 (February 2019)
Abstract

Controlling the gas turbine emissions has led the manufacturers to use new technologies. Nitrogen oxides (NOx) are one of the major pollutants of gas turbines with natural gas as fuel. Thermal NOx is the main cause of NOx formation in gas turbines at high temperatures. So, water injection can be useful in reducing the NOx emission. In addition to NOx reduction, water injection causes an increase in carbon monoxide emission and damage to combustion chamber. Therefore, it is desirable to find the optimum amount of water injected to the combustion chamber to meet the regulations. To find the optimal water mass flow rate, we numerically investigated the combustion inside the chamber for full load and part load before and after water injection. Then, the effect of water injection at different flow rates was studied to obtain optimal water flow rate. The results showed that for the full load, the optimal water flow rate was 100% of the fuel flow rate and the upstream pressure of the feed water system was 24.45 bar. For the part load (fuel flow rate equals to 75% of the full load), the optimum water injection rate is 80% of the fuel flow rate. In this case, the pressure required for water injection is about 16.5 bar. Results also show that the change in water temperature in the range of 10-80˚C has no significant effect on NOx formation and water can be injected at the ambient temperature.


Volume 19, Issue 5 (May 2019)
Abstract

Orthopedic implants are one of the most reliable methods for bone injuries treatment. An important issue, which must be considered in the design of orthopedic implants, is that the Young's modulus of implants should be near to the host bone to prevent complications such as stress shielding. Porous implants are considered as one of the new and effective methods for this issue and recent technologies such as metal 3D printing made it possible to manufacture different porous structures with various geometries, which could be used to reach the goal. Porous geometries are used to approaching the elastic modulus of implantation with a porous structure to the bone. Mechanical properties of Diamond porous structure have been investigated in this study and an equation for obtaining the modulus of elasticity is presented in terms of the geometric parameters of this structure. Based on the results, the error between finite element analysis and experimental data is between 3.64% and 18.51% and it has been shown that the Young's modulus obtained from finite element method is more in line with the existing experimental data than the analytical results; by the increase of relative density, the error would be decreased. Furthermore, in the relative density between 0.06 and 0.16, the Young's modulus of titanium Diamond structure would be the same as bone Young’s modulus, which is an effective feature in design of orthopedic implants.


Volume 19, Issue 7 (July 2019)
Abstract

In this study, the geometrical effect of circular cylinder with different sectors on energy harvesting of vortex induced vibration is investigated numerically. According to Von Karman vortex shedding phenomenon, the flow passes over a bluff body and as the results create vibration, can use this phenomenon with energy extraction and converting it into desired energy. In this paper, the focus was on discovering a cylinder geometry with more vibration than the base cylinder (circular cylinder); for this purpose, circular cylinder with different sectors, including  ratio of 0.5, 0.6, 0.7, 0.8, 0.9, and 1 in two direction of arches frontal (AF) incoming flow and flat frontal (FF) incoming flow have been studied at Reynolds numbers of 100 and 200. Investigations have been carried out in the fluid and vibration field. In the fluid field, the aerodynamics forces are obtained on the cylinder with the help of computational fluid dynamics (CFD) and in the vibration field, by writing program in the Maple software, the displacement of the cylinder and, finally, recoverable potential power of the fluid were calculated. The results show that, at Reynolds numbers of 100 and 200, respectively, circular cylinder with and  sectors in the placement direction of FF get the maximum extraction power of fluid and compared to the circular cylinder at Reynolds numbers of 100 and 200, respectively, 3.5 and 5.3 more times power harvesting. Also, in the same sectors cylinder, the cylinder with FF placement direction always has more power generation than the cylinder with AF placement direction.


Volume 19, Issue 12 (December 2019)
Abstract

Casing collapse is major problem of the oil fields which causes increase of costs to oil companies. This problem can be seen not only at drilling time in some formations but also after the completion and production may cause problems. exact prediction of collapse pressure is a very important factor in the casing design. Casing Collapse generaliy is a function of the geomechanical properties of the formation and the properties of the solid mechanics of the casing. One of the properties of solid mechanics that affects the testing of the collapse can be the ovality of the casing and the difference in the thickness of the casing and the existence of residual stress during the construction of the casing. In this paper, using numerical methods, the effect of each of the above-mentioned solid mechanics parameters and formation creep on the collapse of the casing  has been investigated. The results of this study indicate that pipe defects, such as casing ovality, eccentricity and the presence of residual stress, reduce the strength of the casing.
This reduces the resistance to the extent that the casing at the time of installation due to high plastic strain will collapse and also it was found that the pipe imperfections is more effective than rock salt creep in casing collapse.
 


Volume 20, Issue 1 (January 2020)
Abstract

In this study, an example of the results obtained from the combination of the vibration monitoring program and the root cause analysis approach for the electromotor roller element bearings of the cement factory’s mill fan has been presented and examined. By registering the inspectors' reports on the release of abnormal sound from the bearings, the vibration data recorded in the monitoring program were equipped and, by carefully checking the vibration trends of the machine, sensible increase in the bearing condition index (BC) have seen. By matching the fault frequency with the frequency elements of the roller bearing, predicted is failure in the bearing' cage, which will be verified by visited and reviewed. The detect of the root cause of the failure is on the agenda for this purpose, paid investigated the causes of failure in the bearings and due to the inspection history, finally specified the use of the bearing is not suitable due to the velocity factor, as well as the factors of the lubrication interval and the amount of lubrication charged can be explained by the reasons for failure in the machine.

Volume 20, Issue 3 (Fall 2016)
Abstract

Synoptic analysis of the structure of heat waves in Khuzestan province is the main purpose of the present study. Statistical and synoptic analysis and dynamic downscaling technique were used to identify the atmospheric circulation structure in the time of the emergence of a heat wave in the area. To this end, daily maximum temperature during the warm period (June to September) for 13 synoptic stations in the southwest of Iran with different statistical length were taken from the Iran Meteorological Organization. Based on the statistical analysis results, 1 July 2000 was identified as the hottest day in the selected hottest heat wave in the period of study, and therefore this day was selected for exact investigation and dynamic downscaling. The results of synoptic analysis showed that the intense subsidence heating that occurred in the selected day had two causes: At the surface of the earth, a low pressure situation with the origin in thermal low pressures of the Gange, Arabian Peninsula and Persian Gulf and West Asians independent subtropical high pressure at 500 hpa level; and warm air advection fluxes to the study area, both in low latitudes and Iran dry areas. The RegCM4 dynamic downscaling results indicated that at the earth surface, there is a strong low pressure on the Zagros and there exists a strong typical ridge at upper levels. This strong typical ridge caused dry adiabatic subsidence and created intense heating. This study revealed that the Zagros high Pressure (ridge) has obvious role in the emergence of heat waves and intensification in Khuzestan.      

Volume 23, Issue 2 (Summer 2019)
Abstract

Introduction
Global warming and climate change are nowadays significant challenges for humankind. It is widely and generally accepted that the increase of greenhouse gases emissions (GHGs) in the atmosphere are caused by anthropogenic effects especially in modernized and industrialized countries. Consequently, cleaner energy generation is needed in order to reduce global GHGs emissions (Waewsak et al., 2014). Wind energy becomes today a promising option to complement the conventional energy source, especially in region where the existing power plants are not sufficient to match the increasing electricity demand. This success is principally due the rapid growth of the wind technology which led the wind power to be more competitive by reducing the cost of electricity produced (Djamai and Merzouk, 2011). Since there has no comprehensive wind potential study in Kermanshah province, it is necessary to pay this important subject to reply for increased demand of electricity. Thus this paper aimed to assess economical usage of wind power in Kermanshah province.   
Methodology
In this study we assessed economic feasibility of wind energy usage at 13 sites in Kermanshah province. In order to carry out the research, 3-hour wind speed data in 2009 to 2013, topography, land cover and obstacle maps were used, and ten models of wind turbines with different rated power were investigated. It has been calculated Capacity Factor, Operating Probability of wind turbines, and Annual Energy Production for selected turbines in 0.03m surface roughness using WAsP and Windographer software. Economical evaluation was down by Net Present value method and benefit costs analysis (B/C) in 13 sits and 10 models of wind turbines. Also in this research it was used Extra Investment Analysis (EIA) method to choose the best project from the initial Selected Projects. After investigation of cost analysis, it was determined the most economical wind turbine and site for utilization wind energy in Kermanshah province.
Results and discussion
The maximum Capacity Factor of selected turbines has calculated in Gilanqarb (46.4%), Tazeabad (44.2%) and Somar (39.2%). This is because of different wind climatology of these sites in comparison with the other sites in the Kermanshah province. In the other words orography characteristics of these sites leads to more nocturnally mean wind speed.
The costs of the construction and maintenance of a wind farm include initial Capital Costs (turbine price and costs civil work), and also operation, maintenance and Repair costs. On the other hand, the proceeds from the sale of electricity generated should be borne by the costs incurred. The cheapest turbine is 500- kW machine with 707 thousand dollars and the most expensive is 2000- kW machine with 2900 thousand dollars.
Benefit costs analysis indicated wind power plant construction in Gilanqarb area is more economical than other areas with all turbines except for 1300- kW machines which is more  economical in Tazeabad. Also the most economical machine is 2000- kW turbine in Gilanqarb area. The cost of wind power plant construction whit one 2000- kW turbine is 15.4 Billion toman right now, while the proceeds from the sale of electricity generated is 21.49 Billion toman in life time of machine. So this project is the most economical with benefit-cost ratio equal to 1.4 in comparison with other project in the study area. Obviously, the results of economic analysis will also be different if the prices used in economic analysis, such as the price of a turbine, the price of electricity or the exchange rate change.
Conclusion
 The results showed 750- kW and 800- kW machines have maximum Operating Probability of wind turbines and also it was the highest in Tazeabad site with 80 to 89%. While Capacity Factor has the highest value for 500- kW machine in all sites. Of course this turbine has the highest value in Gilanqarb (46.4%), Tazeabad (44.2%) and Somar (39.2%) sites. The most Annual Energy Production (AEP) acquired for 2000- kW turbine which is due to its high rated capacity. Calculated AEP for selected turbines vary between about 2 GWh in Kangavar to 6.7 GWh in Gilanqarb in the year.
Benefit-Cost index showed that wind power plant construction in Gilanqarb area is more economical than other areas with more turbines, and also the most economical machine is 2000- kW turbine in this area. Finally Calculations showed that usage of wind energy is not economical with any turbine in Eslamabad-Qarb, Kangavar, Sarpol-zahab, Ravansar, Sonqor, Harsin, Javanrood and Qasre-Shirin.
 

Volume 24, Issue 4 (Winter 2020)
Abstract

 
 Introduction
Particulate matter is any liquid or solid component (except pure water) that is dispersed in the Earth's atmosphere and is microscopic or sub-microscopic but larger than the molecular size. These particles play an important role in the Earth's climate. Suspended particles are created by various natural or anthropogenic processes and are among the deadliest types of air pollution, especially smaller particles less than 10 micrometers in diameter. Since the number of pollution station is very low, Satellite measurements have been widely used to estimate particulate matters (PMs) on the ground and their effects on human health.
 
Methodology
In this research, we tried to estimate PM10 using the regression model based on the Aerosols optical depth. Because the AOD value recorded by satellite sensors is affected by the weather conditions, to increase the accuracy of the PM10 estimation, meteorological parameters were also used in the AOD to PM10 conversion model. The used meteorological parameters include surface wind speed, surface temperature, relative humidity, visibility, and planetary boundary layer height.
Since the data used were extracted from four different sources with different temporal and spatial resolution, it is necessary to apply a method for integration and synchronization in space and time. To generate AOD and PM10 data from the Aqua satellite, pollution stations were mapped onto satellite images and AOD values ​​for the nearest neighbor pixels as well as values ​​for a 3 by 3 window were extracted. So, two pairs of AOD and PM10 were formed, one with the nearest neighbor values ​​and the other with the weighted average AOD values ​​in a 3 by 3 window. Because the PM10 values ​​were more closely related to the AOD values ​​than the nearest neighbor, the pair of the weighted average was excluded from the calculations. There  were extracted 100 samples in warm season (June, July, August and September) for model development (Shokoufa station data) and 65 samples for validation (Cheshmeh and Atisaz station data) and 140 samples in cold season (November, December, February and March) for model development, and 50 samples for validation. In the last step, the accuracy of the model was evaluated using indices such as coefficient of determination, mean error deviation (Bias), and mean square error (RMSE).
 
Results and Discussion
The results showed that AOD and PM10 have a better relationship with each other in the warm season than in the cold season. Only two variables of AOD and wind speed were included as independent variables in the best model presented for the warm season; both of which have a direct relationship with PM10, that is, with increasing of both variables the value of PM10 increases. The results showed that the regression model of warm season can only predict 16% of the PM10 variations correctly, which is not a satisfactory result.
In the multivariate cold season regression model, only the visibility remained, and other variables that had no significant effect on model improvement were excluded from the regression model. Multivariate correlation coefficient of this model was estimated to be 0.59. Therefore, the cold season regression model, at best can predict 35% of the PM10 variations correctly. By deleting the visibility variable, it was attempted to measure the impact of other variables such as AOD on PM10 estimation. In this model, the boundary layer height, AOD and temperature variables were retained. The boundary layer height variable has a negative relationship and the other two variables have a positive relationship with PM10. The maximum effect of temperature on PM10 is justified by the increase in boundary layer and the relationship of these two dependent variables which decreases PM10 density, but since this role of temperature element is represented by the same boundary layer height variable, what remains is the secondary role. Temperature is in the PM10 particle production. However, the latter model is weaker than the previous model and its multivariate correlation coefficient is 0.45 and accounts for 20% of the PM10 variations.
In the evaluation of the model in the warm season, the root mean square error at the Cheshmeh station was 31.76 µg / m3 and at the Atisaz station was 33.56 µg / m3. In the cold season, the root mean square error was estimated to be 47.10 µg / m3 at the Cheshmeh station and 49.81 µg / m3 at the Atisaz station, respectively. However, using the model with independent variables AOD, boundary layer height and temperature, the root mean square error was estimated to be 38.42 μg / m3 at the Cheshmeh station and 39.11 μg / m3 at the Atisaz station. The former shows a decrease of approximately 10 micrograms per cubic meter. Therefore, although the latter model with independent variables of boundary layer height, AOD and temperature had less multivariate correlation coefficients and determination coefficients than the model with independent observational variables in cold season, it yielded better results based on evaluation of the model for different locations and days from modeling location and days.
 
Conclusion
Generally, based on the results, it can be stated that regression models of warm and cold seasons are statistically acceptable at a confidence level of 99%. Therefore, the amount of PM10 fluctuations that is justifiable by the model is not accidental, although the modifications justified by models are low. The calculated errors in the evaluation section showed that the proposed models are not very accurate. It was also found that in the warm season, the wind speed can improve the results of the regression model of the relationship between AOD and PM10, and in the cold season, the variables of the boundary layer height and temperature in the regression model are statistically acceptable and improve the results of the model.
 


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