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Research subject: Permeability and high selectivity are two important factors of gas separation membranes. To achieve such parameters, gas separation membranes can be modified and improved in terms of material type, material ratio, structure, and etc. For this purpose, in this research, the performance of chitosan-gallic acid/polysulfone thin film composite membranes (TFC) has been improved in CO₂ gas separation.
Research approach: To prepare chitosan-gallic acid/polysulfone TFC membranes, a nanometer-scale thin layer of chitosan-gallic acid was formed on the polysulfone support layer (PSF). Following this, chitosan-gallic acid composite thin layer membranes were synthesized with different mass ratios (1:1, 2:1, and 1:2). Various analytical techniques, including Fourier Transform Infrared Spectrometer (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Photoelectric Spectroscopy )XPS(, were used to examine the structure of the TFC membranes, alongside CO₂/CH₄ and CO₂/N₂ separation tests.
Main results: Examining the chemical structure of the synthesized membranes showed the successful formation of chitosan-gallic acid chains on the PSF surface. The microscopic images of the synthesized membranes showed that a dense thin layer of chitosan-gallic acid was uniformly formed on the PSF support layer. The highest CO₂ separation was achieved with a chitosan-gallic acid mass ratio of 1:2. Increasing the gallic acid content in the selective layer of the thin film composite membrane resulted in improved CO₂ permeability, increasing from 294.4 GPU and 347.2 GPU for the 1:1 and 2:1 membrane, respectively, to 411.1 GPU for the 1:2 membrane. Additionally, the permeability of CH₄ and N₂ gases through the thin film composite (1:2) membrane was measured at 24.6 GPU and 19.2 GPU, respectively. The gas selectivity calculations revealed an increase in selectivity for CO₂/CH₄ and CO₂/N₂, rising from 13.84 and 17.165 in the 1:1 membrane and 9.684 and 12.969 in the 2:1 membrane to 16.711 and 21.411 in the 1:2 membranes. The results showed that the performance of the chitosan-gallic acid thin layer membrane, which was used for the first time in CO₂ separation, was acceptable.
 

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Aims: Carotenoids are a vast group of lipid-soluble pigments, which are produced by variety of microorganisms. The aim of this study was to compare the production of carotenoid pigments by prokaryotic isolates of Iranian saline ecosystems and identify superior isolate.
Materials & Methods: In this the experimental study, isolates were purified by culture-based methods and carotenoid extracts were analyzed by spectrophotometry in wavelength region of 400nm to 600nm. The total carotenoid content was estimated by spectrophotometry at λ_max (490nm). Identity of bands was detremined by purification of bands by Thin Layer Chromatography (TLC) and analysis by High Pressure Liquid Chromatography (HPLC) and Fourier Transform Infrared Spectroscopy (FTIR).
Findings: Fourty-three isolates were obtained. Eight isolates were halotolerant bacteria, 8 isolates were moderately halophile, and 27 isolates were extremely halophile. All of the strains were capable of producing carotenoid compounds. Isolate M24 with 2054μg/g production was selected as superior isolate. Thin layer chromatography exhibited 6 colored bands in colored extract of this strain and the most concentrated band was purified. After purification by TLC and HPLC, spectrophotometry in UV range showed two pics at 530nm and 465nm as the highest absorbances, which were similar to UV absorbance of α-bacterioruberin. Phylogenetic analysis of 16S rRNA gene sequence of strain M24 showed that this strain had 98% similarity with Haloarcula amylolytica BD-3.
Conclusion: From Iranian Saline Ecosystems, 43 isolates are obtained. Eight isolates are halotolerant bacteria, 8 isolates are moderately halophile, and 27 isolates are extremely halophile. All of the isolates are capable of producing carotenoid compounds. Strain M24 is superior isolate, having 98% similarity with Haloarcula amylolytica BD-3.

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This paper peresents a mathematical model for the thin layer drying of the Viliamz cultivar of soybean. The thin layer drying behaviour of soybean was experimentally investigated and the mathematical modelling performed by using thin layer drying models provided in the literature. Experiments were conducted at inlet drying air temperatures of 30, 40, 50, 60 and 70ºC and at a fixed drying air velocity of 1 m s-1. Thirteen different thin layer mathematical drying models were compared according to their r values, RMSE, 2 and EF by non-linear regression analysis. The effect of drying air temperature on the model constants and coefficients was predicted using multiple regression analysis. According to the results, the Midilli et al. model was found to be the best mathematical equation for modelling thin layer drying of soybean.

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Many research studies have been performed on forced convection (active) solar dryers for fruit and vegetables. A short survey of these showed that applying the forced convection solar dryer not only significantly reduced the drying time but also resulted in many improvements in the quality of the dried products. Active indirect and mixed-mode thin layer solar drying experiments were conducted on Sultana grapes. A combination of a solar air heater and a cabinet dryer was designed, constructed and tested for this product in the Agricultural Engineering Department at Shiraz University, Iran. Three air flow rates (0.085, 0.126 and 0.171 m3 s-1) and two types of drying systems (indirect and mixed-mode) were adopted. The south wall of the drying chamber was covered by a sheet of glass for mixed-mode and the glass sheet was covered with a thick sheet of cloth for an indirect solar drying system. Seven well-known thin layer drying models were used separately to fit the mixed-mode and indirect type experimental data for Sultana grapes. For experimental indirect data, the Modified Page model (r= 0.998, χ2= 0.000241) and for experimental mixed-mode data, the Page model (r= 0.999, χ2= 0.000169) showed the best curve fitting results with highest r (correlation coefficient) and lowest χ2 (reduced chi-square) values. The constants in these models explain the effects of drying parameters, air velocity and temperature. To take account of these effects, the best correlation equations between the constants and drying parameters were also introduced using multiple regression analysis.

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This paper presents mathematical models of thin layer forced convection solar drying of Cuminum cyminum using two drying methods (mixed and indirect) at different operating conditions. The average initial moisture content of the seeds for all tests was about 43% d.b. and the drying was performed continuously, in each test, for a uniform period of 90 minutes drying time in a solar cabinet dryer to obtain an average final moisture content of 8% d.b. Three airflow rates (0.084, 0.127 and 0.155 m3 s-1) were adopted and the experiments were run each sunny day from 11:30 to 13:00 with an average solar intensity of 750 W m-2 (±50 W m-2), ambient air temperature of 27°C (±1°C) and relative humidity of 30% (±1%). In order to find the most suitable form of thin layer solar drying model, eleven different mathematical models were selected using the experimental data to determine the pertinent coefficients for each model by applying the non-linear regression analysis technique. The goodness of fit was evaluated by calculating and comparing the statistical values of the coefficient of determination (R2), reduced chi-square (χ2) and root of mean square error (RMSE) for any model and for the two drying methods. The best results were found for the approximation of diffusion model with R2= 0.995, and RSME= 0.0199 in mixed mode type, and the Midilli model with R2= 0.994, and RSME= 0.0225 in indirect mode type thin layer solar drying.

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Vacuum drying of Salicornia herbacea L. was performed at different drying temperatures (50, 60, 70, and 80C) to evaluate the drying characteristics and the effect of drying temperatures on the quality of Salicornia. As the drying temperature increased, the drying time decreased significantly (P< 0.05). The drying rate decreased with decrease in moisture content and increase in drying time. On the other hand, the drying rate increased with increase in drying temperature. The logarithmic model exhibited the best fit to the experimental drying data among the tested models. The drying constants estimated using the logarithmic model were found to be affected by the drying temperature. The activation energy for drying was 15.02 kJ mol-1. The surface color of the Salicornia herbacea samples was significantly affected by the drying temperature (P< 0.05). CIE L*-, b*-, and Chroma (C*)-values increased significantly, while a*- and hue angle (h*)-values decreased significantly after drying at all of the drying temperatures (P< 0.05).

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Hybrid joints (Metal–Composite) is being used more and more in aerospace industry due to their low weight and high strength. Dynamic study of this joint, owing to limitation of increase in screw’s preload in composite substructure, has certain importance. Effective factors on nonlinear behavior of the joint are low preload of the screw and high excitation force amplitude on the structure. Layer Element Model has been used to better the description of joint’s behavior in recent years. In this study effects of nonlinear behavior of joint on the structure has been investigated using 2D layer element theory in two divisions: increase of damping and decrease of stiffness which result in nonlinearity. Stiffness characteristics of the joint was modeled with normal stiffness and damping characteristics of the joint with structural damping in shear direction. Nonlinear frequency response function for two preload and two excitation force was extracted and nonlinear finite element model for stiffness and damping of the joint is suggested by High-order polynomial approximation in terms of response amplitude. Effects of increase of excitation force amplitude and decrease of screw’s preload on increase of nonlinearity was extracted by this finite element model. Results indicate that presented nonlinear finite element model corresponds closely to nonlinear vibration tests.

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In this study, the drying process of pumpkin thin layers was investigated by cast tape drying (CTD) and convective hot air drying (CHD) methods and the effect of temperature and drying kinetics of the pumpkin was determined along with  the best mathematical model to fit the changes on moisture content to time ratio. At first, Pumpkin slices were prepared with 3, 5 and 7 mm thicknesses. Drying was performed at 75, 85 and 95 (°C) by CTD method and at 55, 65 and 75(°C) by CHT method in triplicate. Based on the kinetic model evaluated by Hii, Law and Cloke, the 7 mm thickness was selected as an optimum thickness in both drying methods. The optimal drying temperature ranges were 55 and 95 (°C) by CHD method and CTD method, respectively. Five mathematical kinetic models were fitted on the experimental data using four criteria including, Determination of Coefficient (R²), Root Mean Square Error (RMSE), Sum of Squares (SSE) and Chi-square (χ²). Also, effective diffusion coefficient (D) and activation energy (Ea) were calculated. The results showed that Hii, Law and Cloke’s model predicted the drying behavior during CTD. Activation energy of 37.5310588kJ/mol and 20.32657 kJ/mol was calculated for CHD and CTD methods respectively. The best mathematical model for drying a thin layer of pumpkin by CTD and CHD method was proposed Hii, Law and Cloke’s model.

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According to the growing trend of consumption of artificial colors in the food industry as well as their destructive effects on public health, information on the type and consumption of artificial colors which are allowed, as well as increasing the health and safety knowledge of producers and sellers of food. And frequent monitoring by health officials is essential. Therefore, in this study, the status and frequency of synthetic dyes (Sunset Yellow, Tartrazine, Quinoline Yellow and Carmoisine, etc.) in food supplied in Torbat-e-Heydarieh city was investigated using thin layer chromatography method. In current study, 251 samples including processed chicken, Zoolbia and okra, various types of sweets and traditional ice cream were analyzed. Among 66 processed chicken samples, 11 samples had no color, 6 samples had natural color and 50 samples had artificial color which among those that found synthetic dyes, the prevalence of tartrazine and sunset yellow were higher. Among 70 samples of zoolbia and okra, 32 were colorless, 4 and 34 samples had natural and synthetic dyes, respectively, that using of tartrazine, sunset yellow and quinoline yellow was higher than the others. Among 90 samples of sweets which were investigated, 6 samples were colorless, 2 and 82 samples had natural and artificial colors, respectively, which sunset yellow, tartrazine and carmoisine were more common. Finally, among 25 ice cream samples, 15 samples had natural dyes and 10 samples had artificial dyes, that sunset yellow, tartrazine and carmoisine were common than the others.

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Gamma aminobutyric acid (GABA) is a non-protein bioactive compound that can be effective in controlling many diseases such as Alzheimerchrs, hypertension, stress, etc. The main stimulus for the production of GABA is the enzyme glutamic acid decarboxylase (GAD), which is highly active in lactic acid bacteria. Also, the presence of monosodium glutamate (MSG) can act as a substrate for this enzyme and increase its activity. In this study, the production potential of gamma aminobutyric acid by Lactobacillus brevis PML1 in MRS medium was investigated. In order to optimize the fermentation process, culture medium containing MSG (1, 3 and 5%) was examined at 24, 48 and 72 hours.  after fermentation, thin layer chromatography method was used to identify GABA produced by bacteria. Spectrophotometric method was used to quantify the bands in thin layer chromatography. The results of studies at the level of 95% significance showed that the optimal treatment included a culture medium containing 5% monosodium glutamate and a time of 72 hours at 37 ° C, in which the amount of GABA production was approximately 300 ppm; Therefore, the desired strain not only has the potential to produce gamma aminobutyric acid under normal conditions (control sample) but also by adding different percentages of monosodium glutamate to the culture medium, the amount of this production can be increased.