Sharif Digital Repository

In this research, low density polyethylene (LDPE) and poly(ethylene-co-vinyl acetate) (EVA) were used as polymeric materials. The methods used to produce LDPE and EVA was film blowing and thermal-dry phase inversion. The amount of permeability, diffusivity and solubility of O2 and CO2 through above polymers were obtained and also the effect of temperature, pressure and film thickness for LDPE was measured. To study film cross-section morphology in EVA, scanning electron microscopy (SEM) was applied. The results showed that the amount of permeability and solubility were decreased by increasing film thickness but diffusivity was increased. However, by increasing temperature, permeability,... 

The absolute free energy of solvation of methane (CH4) and its fluorinated forms (CH3F, CH2F2, CHF3 and CF4) have been computed via statistical perturbation theory (SPT) in the NPT ensemble at four thermodynamical states (whitin liquid and supercritical regions), in the context of Monte Carlo Simulations. Thermodynamical interpretation of the observed trend in the absolute free energy of solvation in different states reveals an exothermic solvation with ΔSslv < 0 (entropically unfavorable solvation) that the intermolecular interactions play an important role in the solvation process. The fluorinated methanes are confirmed to control the mutual arrangement of neighboring CO2 molecules and the... 

In this research, low density polyethylene (LDPE) and poly ethylene-co-vinyl acetate (EVA) were used as polymeric materials. The methods used to produce LDPE and EVA was Film Blowing and ThermalDry Phase Inversion. The amount of permeability, diffusivity and solubility of O2 and CO2 through above polymers were obtained and also the effect of temperature, pressure and film thickness for LDPE was measured. The Barometric method was considered and measurements were based on ASTM standard. To study film cross-section morphology in EVA, Scanning Electron Microscopy (SEM) was applied. From results we considered that the amount of permeability and solubility were decreased by increasing film... 

An experimental flow-type apparatus has been tested for the separation of phenanthrene from a mixture of solids (phenanthrene, anthracene, and carbazole) and also from anthracene oil of the Isfahan Coal Tar Refining Company based on retrograde crystallization phenomena in supercritical carbon dioxide. The results show that by exploiting the crossover effect it is possible to obtain (82 and 24) mass % of phenanthrene from the solid mixture and anthracene oil, respectively, with a single temperature cycle  

Tetraphenylthiophene diamine (TPTDA) was prepared through a modified three-step route to achieve an improved overall yield. TPTDA reacted with succinic, adipic, suberic, sebasic, and fumaric acids via the Yamazaki phosphorylation method to yield novel partially aromatic polyamides (TPT series). A counterpart polyamide series based on p-phenylene diamine (Ph series) was also synthesized under the same conditions. All of the polymers were characterized by means of spectrochemical (Fourier transform infrared spectroscopy. 1H-nuclear magnetic resonance (NMR), and 13C-NMR) and thermal (differential scanning calorimetry and thermogravimetric) methods of analysis. Solubility of TPT polyamides was... 

Precipitation of strontium sulfate (or SrSO4) has already been distinguished as one of the most costly and critical problems which may occur in process industries and oilfield operations. Costs due to scaling and remedial actions that need to be taken afterward are generally high owing to low solubility of SrSO4 in aqueous solutions. Therefore, a thorough understanding of the SrSO4 thermodynamic behavior under various operating conditions is vital to predict or even avoid the overall damage caused by scaling. The primary aim of this work is to develop a model based on Least Squares Support Vector Machine (LSSVM) and Coupled Simulated Annealing (CSA) referred to as CSA-LSSVM to predict... 

In this study, biodegradation of corn starch/glycerol/Na-MMT nanocomposites by soil burial tests were carried out for up to 6 months. Films were prepared by casting method according to central composite design and response surface methodology was applied for analysis of the results. The effects of formulation on the water solubility, contact angle and tensile strength of starch films were investigated. Increasing in Na-MMT content decreased biodegradability; while presence of glycerol, increased it. The effect of nanoparticles content might have been attributed to interactions between starch and Na-MMT that further prevented enzymatic attack on the biopolymer. In addition, the films with... 

Absorption of carbon dioxide (CO2) in aqueous solutions can be improved by the addition of other compounds. However, this requires a large amount of equilibrium data for solubility estimation in a wide ranges of temperature, pressure and concentration. In this paper, a model based on an artificial neural network (ANN) was proposed and developed with mixtures containing monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), methanol, triethanolamine (TEA), piperazine (PZ), diisopropanolamine (DIPA) and tetramethylensulfone (TMS) to predict solubility of CO2 in mixed aqueous solution (especially in binary and ternary mixtures) over wide... 

A feed forward multi-layer perceptron neural network was developed to predict carbon dioxide loading capacity of chemical absorbents over wide ranges of temperature, pressure, and concentration based on the molecular weight of solution. To verify the suggested artificial neural network (ANN), regression analysis was conducted on the estimated and experimental values of CO2 solubility in various aqueous solutions. Furthermore, a comparison was performed between results of the proposed neural network and experimental data that were not previously used for network training, as well as a set of data for binary solutions. Comparison between the proposed multi-layer perceptron (MLP) network and... 

New experimental results are presented for the solubility of carbon dioxide, hydrogen sulfide in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) at temperatures range from (303.15 to 353.15) K and pressures up to about 2 MPa. The solubility of the mixture of CO2/H2S in [C8mim][PF6] under various feed compositions were also measured at temperatures of (303.15, 323.15 and 343.15) K and the pressure up to 1 MPa. The solubility of carbon dioxide and hydrogen sulfide increased with increasing pressure and decreased with increasing temperature and the solubility of H2S is about three times that of CO2 in the particular ionic liquid studied. The measured data were... 

Urea and inorganic ions are present in some of the physiological systems, e.g. urine. Understanding the interactions in urea/salt/water is a preliminary step to shed light on more complicated behavior of multi-component physiological systems. State-of-the-art models as well as thermophysical properties can be applied to understand the interactions in these systems. In order to determine such interactions densities, mean ionic activity coefficients (MIACs), osmotic coefficients, and solubility were measured in aqueous solutions of urea and different salts. Densities were determined at temperatures 293.15, 303.15, and 313.15K for urea concentrations up to 3molal and up to 1molal for NaCl.... 

Perovskite solar cells have been constructed under ambient conditions by using 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD) mixed with a small quantity of soluble tetra-n-butyl substituted copper phthalocyanine as hole transporting material. The introduction of the phthalocyanine derivative resulted in an impressive increase of cell efficiency, which changed from 10.4% in the absence to 15.4% in the presence of phthalocyanine. This effect is related to the creation of deep traps in the hole transporting phase which block back-travelling electrons as well as to the improvement of the structural quality of the spiro-OMeTAD film in the presence of... 

In this research, organic solvent composed of hexane and methanol was used for lipid extraction from dry and wet biomass of Chlorella vulgaris. The results indicated that lipid and fatty acid extraction yield was decreased by increasing the moisture content of biomass. However, the maximum extraction efficiency was attained by applying equivolume mixture of hexane and methanol for both dry and wet biomass. Thermodynamic modeling was employed to estimate the effect of hexane/methanol ratio and moisture content on fatty acid extraction yield. Hansen solubility parameter was used in adjusting the interaction parameters of the model, which led to decrease the number of tuning parameters from 6... 

Perovskite solar cells have been constructed under ambient conditions by using 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD) mixed with a small quantity of soluble tetra-n-butyl substituted copper phthalocyanine as hole transporting material. The introduction of the phthalocyanine derivative resulted in an impressive increase of cell efficiency, which changed from 10.4% in the absence to 15.4% in the presence of phthalocyanine. This effect is related to the creation of deep traps in the hole transporting phase which block back-travelling electrons as well as to the improvement of the structural quality of the spiro-OMeTAD film in the presence of... 

Classical molecular dynamics simulations are used to compute the solvation free energy of two pharmaceutical solids, namely ibuprofen and acetaminophen in carbon dioxide (CO2), over the density range of interest in supercritical processes. In order to examine the influence of the solvent model on the resulting free energies, three popular CO2 models (Zhang, EPM2, and TraPPE) are studied. Relatively large discrepancies for the solvation free energy exist between these CO2 models, suggesting that the former is sensitive to the different balances between dispersive and electrostatic forces used in these models. In particular, for the solvation of the highly polar (dipole moment of ∼5.2 Debye)... 

In this research, the IFT behavior of two different specimens of W/O emulsion with distinctive soluble ingredients of water in contact with CO2 and N2 was examined. The Minimum Miscibility Pressure (MMP) of the mentioned gases with emulsion specimens were measured and compared with the case of the original crude oil with no water content. This study focuses on the quantity of water in the W/O emulsion specimens and its effects on IFT and MMP values. The IFT behavior of W/O emulsions was surveyed for two different cases of distinctive water soluble ingredients, i.e. sea water and reservoir brine. The tests were performed under high pressure-high temperature (HPHT) conditions utilizing... 

Since most of the anticancer drugs have low solubility in water, the clinical use of them is limited unless by some modification the solubility increases or the drug is carried with a soluble compartment. To solve this problem, we prepared a magnetic nanocarrier with a hydrophobic surface based on oleic acid chains in which hydrophobic drug molecules such as doxorubicin hydrochloride (DOX) and paclitaxel (PTX) are easily adsorbed onto the surface. Since the drug molecules are physically adsorbed on the surface, large amounts of DOX (282 mg·g-1) and PTX (316 mg·g-1) were immobilized onto the nanocarrier. Then, the surface of the drug loaded magnetic core was covered by a smart pH-sensitive... 

This paper introduces the genetic algorithm-kernel partial least square (GA-KPLS), as a novel nonlinear feature selection method. This technique combines genetic algorithms (GAs) as powerful optimization methods with KPLS as a robust nonlinear statistical method for variable selection. This feature selection method is combined with artificial neural network to develop a nonlinear QSAR model for predicting activities of a series of substituted aromatic sulfonamides as carbonic anhydrase II (CA II) inhibitors. Eight simple one- and two-dimensional descriptors were selected by GA-KPLS and considered as inputs for developing artificial neural networks (ANNs). These parameters represent the role... 

The formation constants for 1:1 molecular complex formation between water-soluble cobalt(II) tetradentate Schiff base complex, disodium[{bis(4- methoxy-5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-4-meosal-4,5-dmophen)], and nucleotides, adenosine-5′-triphosphate (ATP) and cytidine-5′-triphosphate (CTP), in mixed solvent systems of ethanol and water with different volume fractions of ethanol and water have been determined spectrophotometrically at constant ionic strength (I = 0.2 mol dm-3 NaClO4) and temperature 278 K. Trends in the values of formation constants according to the volume fractions of ethanol and water in ethanol and water mixed solvent...