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Research subject: Superabsorbents are hydrophilic hydrogels that can accommodate large amounts of water in their three-dimensional structures and have wide applications in various sciences such as pharmaceuticals, medicine, and agriculture. These materials are hydrophilic polymers that are physically or chemically cross-linked. Conversion and swelling ratio of synthesized hydrogels are two counter effects. Therefore, determining the appropriate conditions for polymerization to achieve optimal properties and swelling rate of hydrogels is a challenge for researchers.
Research approach: In this study, optimizing the synthesis conditions of semi-interpenetrating poly (acrylic acid)/xanthan hydrogels, the response surface methodology (RSM) was used by Box-Behnken design (BBD). The variables of this method were the molar ratio of the cross-linking agent (X₁), the weight percentage of xanthan gum (X₂) as the reaction medium, and the amount of initiator (X₃), each of which was considered at three levels. The evaluated responses in RSM were the rate of polymerization conversion (Y₁) and the rate of swelling (Y₂) of the hydrogels in the water.
 
Main results: Based on the 17 experiments proposed by RSM (BBD), the cross-linker, xanthan gum, and initiator were combined and radical polymerization was performed into silicone molds at 65 ° C. The results of ANOVA analysis showed that the data error of this study was small and the coefficient of determination (R2) of both proposed models for the responses Y₁ and Y₂ was higher than 0.9. The 46 experiments proposed for the optimal point by RSM (BBD) with the desirability of more than 50% indicate the synthesis of hydrogels that have both a good conversion rate and an optimal amount of swelling. For example, by 13% of cross-linking agent, 0.043 g of initiator and 1% wt. the solution of xanthan, hydrogels with a 95% conversion rate, and 102% water uptake were prepared. These hydrogels can be used in a variety of fields, including the treatment of colored wastes in factories, agriculture, pharmaceutical systems, medical attractions, and more.

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The response surface methodology was employed to optimize the effects of pH, temperature (˚C), time (min) and the ratio of enzyme to substrate (% of substrate) on the hydrolysis process of cuttlefish muscle by alcalase. Central composite rotatable design with 5 levels and 4 factors and α=2 was used for the optimization of the process to gain the highest degree of hydrolysis. pH, temperature, time, enzyme concentration, interaction of temperature-enzyme concentration, square of pH, temperature, time and enzyme concentration had significant effects on the process. The R2 = 0.95, lack of fit < 0.05 and adeq-Precision of 14.16 for the model showed that the model could explain the variability within the range of values. The optimum condition for 42.0117 % of degree of hydrolysis was determined by Design Expert as pH 8.19, temperature 50.23, time 129.62 and enzyme2.15%.

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Production of recombinant proteins in Escherichia coli has been very common in recent decades. Many studies and experiments have been done in order to optimize the production and expression of recombinant proteins in E.coli. One strategy is using high cell density to increase recombinant protein production such as β-NGF in the cell. Therefore, in this study for the first time bacterial cell culture in high cell density was done using glycerol and yeast extract as carbon and nitrogen sources and MgCl2 as a growth effective factor. Also the effects of overnight culture conditions on bacterial growth were evaluated. Meanwhile culture conditions were optimized using response surface methodology (RSM) and the optimum conditions were as follows: 18/23 g/lit glycerol, 14.44 g/lit yeast extract and 10mM MgCl2. Also the obtained results indicated that the 14 hours incubation at 37 °C and 180 rpm were optimum conditions for the overnight culture. Our results showed that the rate of cell growth and recombinant β-NGF production in optimized condition is significantly higher than in basic medium.

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Aims: The increasing development of microalgae applications has led to the concentration of new multidisciplinary studies to facilitate commercial cultivation of these organisms due to cost reduction and productivity enhancement. The aim of this study was the growth and quality optimization of Spirulina biomass by changing the dilution of medium and using the aeration cycle.
Materials and Methods: In this experimental study, the effect of concentration of Zarrouk medium (0 to 100% dilution) and aeration cycle on specific growth rate and dry weight, as well as the content of chlorophyll and carotenoids of Spirulina were investigated, using response surface method, central design. A total duration of 16 hours was aerated in any 24-hour period; the interval time between these aerated periods varied between 1 to 8 hours. The data were analyzed by SPSS 16 software, using multiple regression test.
Findings: The highest biomass (0.659mg/ml) was obtained at 80% concentration of culture media and aeration cycle of 2.75 hours and the highest specific growth rate (0.230 daily) was obtained at 60% concentration and aeration cycle of 4.5 hours. The highest aeration cycle (8 hours) resulted in a significant and simultaneous increase in the content of chlorophyll and carotenoids (11.65 and 2.67 mg/g, respectively).
Conclusion: The growth and quality optimization of Spirulina biomass can be accomplished by changing the dilution of the medium and using the aeration cycle.

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The combustion of fossil fuels containing sulfur results in the release of sulfur dioxide into the atmosphere and environmental pollution. Hence, the researchers focused on the biological desulfurization method. Dibenzothiophene is used as the model molecule to study the ability of the desulfurization of microorganisms. The most suitable sources of carbon, nitrogen and sulfur concentration optimized by response surface method to obtain the highest cell growth and biological desulfurization activity. The performance of iron nanoparticles on the growth and biodesulfurization activity of thermophilic bacterium Bacillus thermoamylovorans strain EAMYO was investigated. Characterization of starch-modified iron nanoparticles was performed by TEM, SEM. The images of TEM and SEM of starch / Iron nanoparticles showed that the Fe₃O₄ and Fe0 nanoparticles were 20 and 30 nm, respectively. The investigating the growth of microorganism in the presence of iron nanoparticles showed that these nanoparticles not only did not have a toxic effect on microorganism growth, but also increased the growth of microorganism in 96 h (OD 660 = 1.864, 1.896 respectively in the presence of nanoparticles Fe₀ and Fe₃O₄), while the highest rate of growth in the absence of nanoparticles in 96 h (OD660 = 1.51). Also, the activity of desulfurization in the presence of starch/Fe₀ nanoparticles and starch/Fe₃O₄ / starch increased by 26.52% and 10.75%, respectively, compared to the cells without the coating of iron nanoparticles.
 

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Hyaluronic acid (HA) is a natural and linear polymer that finds a wide-range of applications in medicine, cosmetics, and nutraceuticals because of excellent viscoelasticity, high moisture retention capacity, high biocompatibility and non-toxicity. HA has been recently produced in industrial scale by Streptococcal species. Streptococci are nutritionally fastidious lactic acid bacteria and cannot synthesize some amino acids. Therefore, it is necessary to study and select some commercial culture media for their growth. In this study, HA production and hyaluronidase activity of S. zooepidemicus ATCC 43079 in three culture media were investigated. Regarding the detrimental effect of this enzyme on HA amount, 6-O-Palmitoyl-L-ascorbic acid as hyaluronidase inhibitor was added to culture medium during fermentation. The effect of three variables consisted of glucose concentration, yeast extract concentration and medium pH each at 3 levels were considered and (response surface methodology (RSM) was used for statistical design of experiments to study the HA production by this strain. The results showed that maximum HA production was obtained when glucose concentration, yeast extract concentration and pH were 21.2 g L^-1, 43.6 g L^-1 and 6.6, respectively. Under optimum conditions, HA was produced as 370±15 mg L^-1 which was ~150% more than of HA concentration in basal medium (150±10 mg L^-1) and productivity reached 56.74 g L^-1 h^-1 that was increased 2 fold compared to central point.

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Phenolic compounds, especially those of plant origin, constitute an essential part of the human diet, and are of considerable interest due to their antioxidant properties. In this study, Ultrasound-Assisted Extraction (UAE), Microwave-Assisted Extraction (MAE), as well as Maceration Extraction (ME) methods were applied for phenolic compounds’ extraction from pistachio green hull. Response surface methodology was employed to optimize the extraction conditions as regards the yield of the compounds. A Central Composite Design (CCD) was employed to investigate the effects of three independent variables, namely liquid-to-solid ratio (8-20 times), temperature (25-65 °C) and time (5-45 minutes) on the dependent variable (level of total phenolic compounds). The results indicated that within the same extraction time, the extraction yield through UAE was higher than those in ME and MAE methods. Correlation coefficients (R2) of the models for UAE, MAE and ME methods were 0.95, 0.96 and 0.94, respectively. The optimal conditions for extraction of phenolic compounds from pistachio green hull through ME, UAE, and MAE methods were 20(v/w), 65°C, 45 minutes; 20(v/w), 65°C, 25 minutes; and 20(v/w), 65°C, 45 minutes, respectively. Under optimized conditions the experimental values well agreed with the values predicted by the proposed models.

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The Juice clarification is an important operation in the fruit processing industry. Sour Orange is a source of vitamin C that is cultivated in the north of Iran. Since turbidity of this fruit after juice extraction affects on quality, shelf-life and concentration of juice; clarification and removing of turbidity-causing factors is important. In this study, the effect of membrane parameters including pressure (1.2-2.2 bar) and temperature (25-35 ºC) on the quality characteristics of sour orange during membrane clarification was investigated. The response surface methodology (RSM) by Design-Expert Software was used to optimize the clarification conditions. Results of the experiments showed that the Browning index was raised by increasing of temperature, but vitamin C content, Total antioxidant activity value and clarity was decreased in this condition. The Browning index was decreased by increasing of pressure; however, no significant effect was observed on the other quality characteristics. Results of process optimization indicated that the best condition to maximize of vitamin C content, total antioxidant and clarity and to minimize of Browning index achieved at 25 ºC and 1.7 bar. In this condition the vitamin C content, Browning index, Total antioxidant activity and clarity was 24.9 (mg/100 cc juice), 0.106, 87.97% and 97.1%, respectively.

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   Ice cream is a complex food colloid including fat droplet and air cells that dispersed on the relatively frosted aqueous phase. In this research work, the effect of the fat at the four level  ( 2.5, 5, 7.5, 10 % ) , pekmez  at the three level ( 0, 9, 18 %) ,  two types of hydrocolloids (Carboxyl Methyl Cellulose and balangu ) each at the four level ( 0.1, 0.3 ,0 .5 , 0.7 % ) on the viscous flow properties and total acceptance of  ice cream by response surface methodology (RSM) was investigated.  The flow behavior of all samples using Power law, Casson, Bingham and Herschel- Bulkley models was investigated. According to the R² (≥0.99) and RMSE (≤0.9314) values, it is obvious that the Power law model is highly appreciated for describe flow behavior of ice cream samples. Also the Result indicated that casson plastic model was highly significant for evaluate yield stress of ice cream samples. Samples containing Balangu gum has higher consistency coefficient and yield stress and lower flow behavior index than samples containing CMC. Its worth to mention that Herschel-Bulkley model gave negative values for yield stress which has no physical meaning. Balangu seed gum (BSG) in comparison to carboxyl methyl cellulose did not have a significant effect (P > 0.05) on the total acceptance. The Desirability function has been achieved as 0.93 which, itself, indicates the accuracy of optimization. The optimum formulation has been found as following: fat of 5.6%, BSG of 0.6% , Pekmez of 18%, respectively.

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    By irradiation as Food processing method, Food quality is maintained and control of microorganism causes prevention of corruption. Simultaneously, Methods of drying, which leads to maintaining the quality and texture, are used. In this study, optimal conditions were determined by drying gamma rays irradiated potatoes with response surface method. For sample, the source of 60 Co irradiation (Gamma Cell 220) was used. Samples with 0, 2, 5 and 8 kGy doses were irradiated. Drying using microwave power at 200, 400 and 600 W and in three thicknesses of 5, 7 and 9 mm of sample was performed. Optimal conditions for radiation dose of 5 kGy, sample thickness of 7 mm and a microwave power of 400 W and L*, a*, b*, color changing, hue angle, Croma and browning index were proposed to 57.87, -0.95, 42.19, 10.73, -1.53, 42.22 and 113.59, respectively. In addition to the effects of radiation variables, the thickness of the sample and the microwave drying effect on indicators such as L*, a*, b*, browning index, Croma and hue angle was investigated.Type text or a website address or translate a document.Did you mean: شرایط بهینه مربوط به دز پرتودهی 5 کیلو گیری، ضخامت نمونه 7 میلی متر و توان مایکروویو 400 وات و برای ‏L*‎، ‏a*‎، ‏b*‎، ‏تغییرات رنگ، زاویه هیو، کروما و شاخص قهوه ای شدن به ترتیب، 87/57، 95/0-، 19/42، 73/10، 53/1-، 22/42 و 59/113 ‏پیشنهاد شد With increasing irradiation dose, increasing the thickness of the sample and the microwave power, the color index decrease, Hue angle color and color density increases and decrease, respectively. Finally, using the neural network model, drying of irradiated potato was modeling and ability of the model to predict of the color changes in regression and response surface method was compared. In this comparison the neural network model was capable for prediction higher than the regression model ( ).  

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In the present research work, response surface methodology was used to achieve optimum condition to prepare orange peel oil – quince seed mucilage (QSM) and maltodextrin (MD) emulsion and using this emulsion in microencapsulation. For this purpose and in order to access stable emulsion, effect of three independent variables including orange peel oil concentration (15-25% w/w), QSM/MD (0.015-0.02) and solid concentration (QSM+MD)(25-35% w/w) on the three dependent variables including droplet size, creaming index and viscosity were investigated. Optimized emulsion (25% solid concentration, 0.02 QSM/MD and 0.025 orange peel oil concentration) were dried by freeze dryer, and were kept in three temperature (4, 25 and 42 °C) in order to investigation its stability during 6 week storage. The results showed that rheological properties of QSM, in particular its viscosity, had the highest effect on the stability and properties of emulsions and QSM could make quite stable emulsion over time. Also, our results revealed that half-life and release rate of encapsulated samples were significantly lower than control samples.

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The lipase is used broadly in different industries such as food, drug, petroleum and detergent industry due to the catalyst ability of wide range of conversion reactions such as hydrolyzed, esterification and transesterification . Yeasts are one of the main generators of lipases. In this paper, we use RSM and CCD in order to examine the effect of PH (5.5-7.5), time incubator (3-7days) and sesame meal extracts added to experimental medium (0-100%) on lipase generation and activity, generated biomass of Cryptococcus albidusand optimization of lipase generation process and generated biomass. The results showed that the percentages of sesame meal extracts added to experimental medium and time incubator are the most effective factors on lipase generation and activity and amount of generated biomass, respectively. Based on conducted experiments, optimized conditions of lipase generation and amount of generated biomass are determined PH 5.56 time incubator 7 days and percentages of sesame meal extracts added to experimental medium 100 percent in order to achieve maximum lipase activity (98.96 unit enzyme) and cell dry weight (1.14 gram per 100 mili liter medium).

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In this paper, dry electro-discharge machining (Dry EDM), one of the newest machining processes which differs mainly from conventional EDM in using gaseous dielectric along with tool electrode rotation, has been studied. Gap voltage, discharge current, pulse-on-time, pulse-off time, dielectric gas pressure, and electrode rotational speed have been considered as effective input parameters. Response surface methodology (RSM) has been used to optimize the machining performance with respect to material removal rate (MRR). Base on the results and analysis of running experiments, it can be concluded that MRR increases by increasing gap voltage, discharge current, the ratio of pulse-on time over pulse-off time, input gas pressure, and electrode rotational speed. There also exists an optimum amount of pulse-on time determined according to the machining circumstances. Also the material removal rate in dry EDM has been improved compared with that in conventional EDM in identical conditions. Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM) Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM) Keywords: Dry electro-discharge machining (Dry EDM), Gaseous dielectric, Response surface methodology (RSM)

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Superalloys are extensively used in various industries like aerospace, chemical and petrochemical industries due to their properties such as high strength at elevated temperature and good corrosion resistance. On the other hand, owing to these properties, superalloys are classified as difficult to cut materials. In the present work, the effect of cutting parameters on tool life in turning of N-155 iron-nickel-base superalloy is investigated. Cutting speed and feed rate each at five level were selected as cutting variables. Relationship between cutting parameters and output variable i.e. tool life was modeled by using response surface methodology (RSM). The results showed that there was a good agreement between the experimental results and the predicted values using the developed mathematical model. Additionally, analysis of variance was implemented to evaluate the adequacy of the regression model and respective variables. ANOVA results indicated that the cutting speed had more effect on tool life than feed rate. Moreover, wear mechanisms and failure modes of the cutting edges were analyzed by using the images of scanning electron microscope (SEM) at different cutting speeds and feed rates. It was observed that abrasion and adhesion were the most dominant wear mechanisms in this study. Finally, desirability function was used so as to predict optimum cutting parameters for achieving maximum tool life.

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Kermanshah province is the main producer of various chickpea cultivars in Iran. In this study a laboratory peg-tooth thresher was employed for chickpea threshing. The effect of cylinder speed (9, 12, 15 m/s), concave clearance (12, 14, 16 mm), feed rate (80, 160, 240 kg/h) and material moisture content (5, 10, 15% w.b.) was studied on percentage of grain damage, threshing efficiency and percentage of seed germination. The experimental plan for optimization was prepared with response surface methodology technique with composite experiment design. The effects of all independent variables on the response variables were significant. The effect of cylinder speed was the most significant and followed by the moisture content. With increasing cylinder speed in the range of 9 to 15 m/s, the grain damage increased from 4.98 to 47.97%, threshing efficiency increased from 96.81 to 99.69% and seed germination decreased from 85.75 to 55.98%. With increasing moisture content, grain damage and threshing efficiency decreased but seed germination increased. With increasing feed rate and concave clearance, grain damage and threshing efficiency decreased while, seed germination increased. The optimized point was determined at the cylinder speed of 10.63 m/s, concave clearance of 13.74 mm, feed rate of 240 kg/h and moisture content of 12% (w.b.). In this condition, the optimum values of grain damage, threshing efficiency and seed germination were 3%, 98.3% and 84.29%, respectively.