Showing 36 results for Sohrabi
Volume 15, Issue 8 (10-2015)
Abstract
Inconel 625 is a nickel-base supper alloy that is widely used in power plants industry, aerospace systems, and mineral industries due to its properties such as high tensile strength, high corrosion resistance and excellent fabricability. Resistance spot welding (RSW) is one of the important joining processes for assembling supper alloy sheets, because of accuracy and high production rates. In the present research, the influences of electrode tip diameter and other RSW parameters on distribution of temperature and nugget formation are investigated by the finite element method for Inconel 625 superalloy. The process is simulated with a 2D axisymmetric coupled electro-thermal and uncoupled mechanical finite element model by using ABAQUS software package. In order to improve accuracy of simulation, material properties including physical, thermal and mechanical properties is supposed to be temperature-dependent. The diameter of computed weld nuggets is compared with experimental results and good agreement is observed. So, FE model developed in this paper provides prediction of quality and shape of the weld nuggets and temperature distributions with variation of each process parameter, suitably. The results show that increasing electrode tip diameter decreases weld nugget diameter, in constant welding current, but in general, the electrode tip diameter cannot be selected less than a distinct value.
Volume 16, Issue 13 (Conference Special Issue 2017)
Abstract
Volume 16, Issue 94 (December 2019)
Abstract
Packaging films are one of the common ways to maintain the quality of food and agricultural products. The effect of PVC and HDPE packaging films, storage and temperature on some mechanical properties, including: the firmness force, yield strain, energy of rupture and modulus of elasticity and also, the viscoelastic behavior of the strawberry fruit was investigated. The mechanical test and relaxation test were done using a texture analyzer. In this study, the stress versus time graph was plotted and three-component Maxwell model coefficients were obtained. According to the results of this study, the use of these films had a positive impact on the yield strain. On the other hand, products in the packaging films were able to store products until the 40th day. In this study, the firmness force of HDPE packaging fruits in 4℃ and 20℃ from 2.17 to 1.10 N, 2.16 to 1.85 N, decrease respectively, during storage. The results show that Maxwell model (RMSE<0.6818 and R2 >0.9158) fits the experimental data. Also, with a retention time, the elastic component of the model is relatively reduced and the application of the packaging prevents the decrease in relaxation time.
Volume 17, Issue 7 (Supplementary Issue - 2015)
Abstract
In the present study, the effect of two species of AMF, Glomus mosseae and Glomus intraradices, alone and in combination, was evaluated on the growth criteria, chlorophyll content, and root rot disease caused by Fusarium solani f. sp. pisi, on chickpea (Cicer arietinum L.) under greenhouse conditions. Chickpea seeds were sown into pots containing 100 g of AMF inoculum (more than 1,000 propagules g-1) and, after four weeks, root of seedlings were inoculated with conidia suspension (106 conidia mL-1) of F. solani f. sp. pisi. Six weeks after pathogen inoculation, shoot and root dry weight, shoot height, chlorophyll content and mycorrhizal and Fusarium colonization were measured. Results showed that inoculation of G. mosseae was more effective than G. intraradices and dual inoculations (G. intraradices+G. mosseae) on the above criteria. Inoculation of F. solani f. sp. pisi without AMF treatments reduced shoot height, shoot and root dry weight, and chlorophyll content significantly compared with the control. In the presence of AMF, root colonization by F. solani f. sp. pisi and disease severity decreased and individual inoculation with G. mosseae was more effective than the other treatments. Inoculation of G. mosseae and G. intraradices caused a significant increase in plant height, shoot and root dry weight, and chlorophyll content of pathogen-inoculated plants compared with inoculated chickpea plants with F. solani f. sp. pisi. Based on the results, application of G. mosseae was found to be the best for reducing the root rot disease and improving plant growth parameters of chickpea, followed by G. intraradices and dual inoculations.
Volume 17, Issue 103 (September 2020)
Abstract
Various methods have been developed to detect the presence of contamination with Coliforms and E. coli in foods. The pour plate technique using VRBA medium is confirmed as a standard method in Iran. The biggest disadvantage of this method is the need to spend a lot of time, high volume of laboratory operations, multiple stages and ultimately long time to achieve the results. Today, due to the mass production of various foodstuffs, the need for faster methods with high sensitivity to control the quality of food is necessary for the responsible oversight centers. The use of chromogenic medias is also one of the fastest diagnostic methods that have been developed. According to this matter, a comparative study was considered from the results of application of three chromogenic media and reference method in food quality control. Totally 100 samples of foodstuffs were evaluated for contamination to Coliform and E.coli using standard method and three chromogenic medias. Based on the obtained results, 86, 79, 85 and 80 samples were contaminated to Coliform using the standard method, Coliform Agar ES, ChromAgar ECC and Rapid E.coli 2/Agar respectively. Also, using four mentioned methods, contamination to E.coli was reported at 66, 80, 84 and 80, respectively. Cochrane test showed that there was no significant difference between the four methods in Coliform diagnosis (p>0.05). However, four methods did not have the same function in the detection of E. coli so that the chromogenic methods showed significant difference with the standard method (p< 0/001). But there was no significant difference between these chromogenic methods in detecting E.coli (p>0.05). According to the statistical analysis of present study, three chromogenic medias can be used instead of the standard method for the detection of Coliform, but the use of these chromogenic medias is not recommended for the identification of E.coli.
Volume 18, Issue 1 (5-2014)
Abstract
In recent years, continuing growth in technology and strengthening competitiveness through the business environment have led websites to be a key instrument to communicate with stakeholders. Therefore, website effectiveness is considered as a vital factor to attract and retain customers. It is worthy to mention that despite of investing heavily in establishing websites by most of organizations, they do not attain their initial objectives, and the performance of websites is not satisfying. One of the critical reasons of such failures is the lack of proper website evaluation framework for practical use.
In this vein, many studies have been conducted to identify the critical factors influencing on the website performance or quality ranging from Internet marketing researches to information systems design and human–computer interactions. This study identifies the factors, which must be taken into account in evaluating a website, using content analysis of 130 relative articles published between 1995 to 2011. We used Shannon Entropy to prioritize the most cited factors and their measurements based on computing the entropy of information and frequencies of addressing them in these articles. Based on the obtained results, we proposed a conceptual framework including 6 major factors: information quality, visual appearance, usability, customer support, technical features, and vendor's specific quality and reputation.
Volume 18, Issue 6 (11-2016)
Abstract
Regarding hemodialysis patients’ limitations in consuming different foods, providing them with a product with health-promoting effects is important. The objective of this study was to develop a functional food from whey protein for this disease condition and assess its sensory, chemical, and nutritional characteristics. Fermented and unfermented beverages were prepared as a mixture of whey protein concentrate (8.5%), permeate (1.4 % for fermented), mint flavor (0.01%), vitamin E (0.18%), and water. Ty17A starter was used for the fermented blend. After pasteurization, and homogenization, the blends were stored until the sensory, chemical, and nutritional evaluations were done. Data were analyzed by SPSS Software (version 16). The pH values of the fermented and unfermented beverages were 3.8 and 6.02, respectively. The medians of all sensory attributes were greater than 4 for the fermented and less than 3 for the unfermented beverages (except color). All sensory attributes other than the color were significantly different between beverages (P< 0.05). The overall acceptability of the unfermented beverage was less. No significant nutritional differences were seen between beverages. Some of the nutrients values in the beverages are desirable for hemodialysis patients (Protein: 7.9-8 g 100 g-1, Fat: 0.4%, Trans fatty acids: 2%, Saturated fatty acids: 56.15% Phosphorus: 9.25-9.35 mg 100 g-1, Potassium: 0.0295 %, Sodium: 62.5 mg 100 g-1, and vitamin E: 400 mg 220 mL-1). The microbial counts of both were safe. Vitamin E fortified fermented whey beverage might be a good recommendation for hemodialysis patients because of its protein quality, low fat, phosphorus, sodium, and potassium and high vitamin E contents.
Volume 18, Issue 113 (july 2021)
Abstract
Garlic( Allium Satirum L) is one of the most important agricultural products in Iran and one of the major sources of foreign exchange for the country. Due to the high waste in this product to maintain, increase shelf life, and keep its quality, it is necessary to use appropriate storage methods such as drying. In this study, a thin layer of garlic slices was dried at 50, 60, 70 ° C, and in two types of dryers (vacuum and hot air). The most suitable model was developed to describe the drying kinetics of garlic flakes as a thin layer in the temperature range and type of dryer used. Effective moisture penetration coefficient, amount of activation energy, shrinkage, water reabsorption of garlic samples were measured during the drying process. in the present study, by examining 9 different experimental models and calculating the statistical criteria of R2, RMSE, x2 between the experimental data and the results predicted by each model, the most appropriate model describing the drying kinetics of garlic thin slices was the Page model. The results showed that the effective diffusion coefficient of garlic leaf moisture for different temperatures and in two types of dryers was in the range of 1.5* 10-9 to 6.6 * 10 -9 m2/s. Changes in the moisture diffusion coefficient were described as a function of drying air temperature with Arrhenius and the amount of activation energy was calculated between 14.673 and 53.175 kJ / mol. The results also showed that the shrinkage of the product was not dependent on air temperature and the type of dryer and the water re-absorption capacity of garlic samples increased slightly by decreasing their moisture content.
Volume 19, Issue 123 (May 2022)
Abstract
Grape fruit contains some nutrients and high amounts of biologically active phenolic substances, but fungal decay and quality loss are important factors limiting its shelf-life for fresh-consuming and export. Rasheh vine (Vitis vinifera cv. Rasheh) is mainly grown in rainfed vineyards in the western half of Iran, and its berries are rich in anthocyanins, flavonoids and soluble solids. In this study, the effect of natural coatings of nano-chitosan and acetic acid on the post-harvest quality characteristics of Rasheh grape fruit was investigated. Nano-chitosan suspension with a particle size distribution of 5-30 nm was prepared in acetic acid solution by the conventional ionic gelation method. Grape fruits were coated by immersion in the nano-chitosan suspension (0.2%), acetic acid solution (0.5%) or distilled water (control) for 1 min and their microbial, physicochemical and sensory properties were measured during 8 weeks storage at 4 °C and 90% relative humidity. In general, the fruits coated with nano-chitosan or acetic acid had lower aerobic mesophilic bacteria count, mold and yeast count and decay percentage, and higher firmness, soluble solids, titratable acidity and vitamin C, as well as, better sensory properties, compared to the control. The nano-chitosan was more effective than acetic acid in improving the post-harvest quality and shelf life of grape fruit. No significant difference was observed in the weight loss percentage and pH values of the samples. Therefore, the nano-chitosan suspension prepared in acetic acid solution, as a natural and customer-friendly coating, is suitable for improving the shelf-life and post-harvest quality of grape fruit, but some of its beneficial effects are due to acetic acid.
Volume 20, Issue 138 (August 2023)
Abstract
In this research, the effect of storage time on the characteristics of extensibility and consistency of processed cheese samples produced from egg white, corn oil and soy protein was investigated. In this research, firstly, in order to optimize the formulation of processed cheese from the central composite statistical design in three levels for three independent variables including soy protein isolate (0, 7.5, 15%W/V), corn oil (0, 8, 16%V/V) and egg white. Egg (0, 3, 6%V/V) was used. On the other hand, the optimal formulation of processed cheese was obtained with the objective of maximum scores of the two characteristics of extensibility and texture continuity, using the utility function method. Finally, the effect of storage in three time periods (0, 1, and 2 months) on the two characteristics of extensibility and consistency of the optimized sample texture was investigated by relying on physical changes. According to the obtained results, the effect of time on the extensibility characteristic showed that with the passage of time, the extensibility of processed cheese samples increased significantly in the negative direction. According to the results, the interaction effect of egg white/time and corn oil/time; It showed that with the passage of time (in the presence and absence of egg white and corn oil), the expandability of the produced samples increased significantly in the negative direction. Also, the effect of time on consistency properties showed that with the passage of time, the consistency of produced processed cheese samples decreased significantly. The results of this study are favorable for the development of processed cheese production and profitable dairy products containing egg white, corn oil, and soy protein. .
Volume 21, Issue 154 (December 2024)
Abstract
Plant extracts and nanoparticles prepared from them due to their antimicrobial and antioxidant properties can be used to increase the shelf life of meat. In the present study, the biodegradable film of polylactic acid containing silver nanoparticles synthesized from Satureja rechingeri extract on the physicochemical and microbial properties of chicken fillet at refrigerated temperature was investigated. So that the control sample (code 1), chicken fillet coated with biodegradable film of polylactic acid (code 2), chicken fillet coated with biodegradable film of polylactic acid containing Satureja rechingeri extract (code 3) and the Chicken fillet coated with biodegradable polylactic acid film containing silver nanoparticles synthesized from Satureja rechingeri extract (code 4) at 4°C in chemical, microbial and sensory properties at intervals of 0, 3, 7 and 14 The days were examined. The results showed that the mean diameter of the growth inhibition zone against Staphylococcus aureus and Escherichia coli bacteria for Satureja rechingeri extract containing silver nanoparticles was significantly higher than Satureja rechingeri extract (p≤0.05). In all the studied days except the first day, the lowest pH of thiobarbituric acid belonged to sample 4 (p≤0.05). Also, on the third and seventh days, the highest L* color component belonged to sample 4 (p≤0.05). On all the examined days, except on the first day, the lowest population of mesophilic bacteria, psychrophilic bacteria, coliform, Staphylococcus aureus, mold and yeast, and mold and yeast, as well as the highest score of all sensory factors (odor, color, texture, overall acceptance) belonged to sample 4 (p≤0.05).Sample 4 was selected as the superior treatment for higher sensory score and more desirable microbial properties.
Volume 22, Issue 3 (12-2018)
Abstract
Destructive organizational behaviors are emerging in various forms. Organizational bullying, with negative effects on work environments, directly and negatively affects people's health and imposes a high cost on the organization and results in a reduction in productivity. Therefore, the main objective of this research is to investigate the role of organizational bullying in occupational psychological characteristics (job engagement, job stress and job insecurity). This research is applied and descriptive - correlation method was used. The statistical population of queue staff was divided into five service organizations with 800 individual. The sample was determined according to the Morgan table and stage sampling method of 261. Data collected by questionnaire which its validity and reliability were confirmed and Cronbach's alpha coefficient was 0.849. Results of tentative analysis and data analysis by structural equation modeling showed that organizational bullying has a positive effect on job stress and job insecurity in employees. Also, the results showed that organizational bullying reduced job engagement among employees
Volume 24, Issue 4 (7-2022)
Abstract
The Tomato Leaf Miner (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a cosmopolitan tomato pest that has driven a renewed reliance on pesticides in tomato production, negatively affecting biological control of other pests and creating environmental and health hazards. We tested five locally important Iranian tomato cultivars (TD, Karon, Petoprid, Matin, and 8320) for constituitive resistance to TLM by comparing its biological performance and life table parameters under standardized laboratory conditions (27.5±1°C, 65±5% RH, 16 L:8 D hours photoperiod). Survival and developmental rates of immature stages varied significantly among cultivars, as did female fecundity and main parameters of the life table. Karon was most suceptible, affording 90% juvenile TLM survival, the fastest development, and the highest female fecundity, with cultivar 8320 not significantly different in these regards. By contrast, Matin ranked most resistant; i.e. only 59% of larvae survived, and female fecundity was almost halved. TD was the next most resistant, being not significantly different from Matin in these metrics. The intrinsic rates of increase (r), in descending order, were Karon (0.178), 8320 (0.169), TD (0.146), Petoprid (0.138), and Matin (0.111). Matin and TD had the highest densities of glandular trichomes on adaxial leaf surfaces. These findings indicate that the Matin, Petoprid and TD are more resistant than the other cultivars and have potential as one component of an IPM strategy to manage T. absoluta.
Volume 24, Issue 12 (December 2024)
Abstract
This study investigates the combustion of hydrogen-methane mixtures in the annular combustion chamber of a C30 microturbine. The primary objective is to evaluate the impact of premixed methane-hydrogen combustion on pollutant emissions and outlet temperature in an annular combustion chamber. Simulations were performed using a partially premixed combustion model and the k-ε turbulence model, employing the Probability Density Function (PDF) approach for chemical reaction modeling. To ensure a detailed analysis of pollutant emissions, comparisons were conducted at a constant turbine inlet temperature. The results indicate that adding hydrogen to methane increases NOx emissions due to the higher flame temperature compared to pure methane, even at constant turbine inlet temperatures. However, this blend can reduce fuel consumption by up to 35%. Additionally, a fuel mixture of 60% methane and 40% hydrogen results in a 61% reduction in CO2 emissions. The study further revealed that, owing to the premixed nature of the fuel-air mixture, the annular geometry, and the swirling flow pattern within the combustion chamber, a fuel blend containing 30% hydrogen can lower NOx emissions to 16.1 ppm—significantly less than the 46 ppm reported in previous studies. Moreover, increasing the hydrogen fraction in the fuel reduced CO emissions by 16%. These findings demonstrate that annular combustion chambers with premixed flows and hydrogen-methane fuel blends have considerable potential for reducing pollutant emissions and optimizing fuel consumption
Volume 25, Issue 1 (1-2023)
Abstract
The objective of this study was to assess changes in proline, Glycine Betaine (GB), photosynthetic pigment concentration, Membrane Stability Index (MSI), and grain yield of wheat cultivars induced by Supplemental Irrigation (SI) in the terminal growth stages. Two field experiments with four irrigation levels (rainfed, SI at booting stage, SI at booting and anthesis stages, SI at booting, anthesis, and grain filling stages) and five cultivars (Rejaw, Sardari, Homa, Azar2, and Sirwan) were conducted during the 2015-2017 growing seasons. Results indicated that, overall, SI increased cultivars' chlorophyll concentration, MSI, and grain yield. Proline and GB highly accumulated under drought stress, but rapidly decreased after SI; the severity of the decrease in proline concentration was more remarkable. Sardari and Azar2 cultivars exhibited greater MSI, proline, and GB accumulation during drought stress and more rapid recovery from drought. Our results suggest that the ability of the wheat cultivars to maintain functions during drought and recover after SI during the terminal growth stage is essential for determining final grain yield.
Volume 25, Issue 5 (9-2023)
Abstract
Bacterial endophytes associated with algae represent a rich source of bioactive metabolites and biostimulants that can be used practically in agriculture as biofertilizer. We carried out a series of experiments to study the diversity of bacterial endophytes associated with seaweed species of the Persian Gulf (PG) and Oman Sea (OS) and their capability in nourishing Mexican lime seedlings. We collected samples of brown, red, and green seaweed species (62 samples of brown, 79 of red and 49 of green) from intertidal zones of PG and OS in southern coastlines of Iran. The isolated bacteria were identified molecularly, morphologically and physiologically. Among 12 bacterial genera identified, the genus Bacillus had the highest frequency (51.51%). In addition to identification, results showed that all bacterial endophytes isolates were negative oxidase, most isolates (81.25 %) were positive catalase and could produce HCN, and all isolates produced IAA, from 0.897 μg mL-1 in Empedobacter falsenii to 0.085 μg mL-1 in Bacillus zhangzhouensis. Most isolates (96.77%) were able to grow on medium incorporated with different NaCl concentrations. Results of inoculation showed that lime seedlings colonized by B. aquimaris (MT278260), B. megaterium (MN626631) and B. zhangzhouensis (MN611359) had more growth and intended morphological characteristics than those lacking endophytes.