Development of a novel nanocomposite consisting of 3-(4-methoxyphenyl)propionic acid and magnesium layered hydroxide for controlled-release formulation

ABSTRACT

Magnesium layered hydroxide (MLH) intercalated with anionic 3-(4-methoxyphenyl)propionic acid (MPP) was synthesised by a direct reaction method using magnesium oxide and MPP as precursors. A further coating of chitosan was applied on the external surface of MLH–MPP nanocomposite to form a new material, named MLH–MPP/chitosan nanocomposite. The XRD pattern showed an intense and sharp peak at basal spacing 18.9 Å, proving that MPP anions were successfully intercalated into the interlayer gallery of MLH in a monolayer arrangement. The XRD pattern of the MLH–MPP/chitosan nanocomposite shows similar peaks with the MLH–MPP nanocomposite. The result was also supported by FTIR spectra and elemental analysis. TGA/DTG spectra showed that the thermal stabilities of the guest anion in the both nanocomposites were markedly enhanced. A controlled-release study of the MPP ion from the MLH–MPP/chitosan nanocomposite showed a slower release compared to MLH–MPP nanocomposite with an initial rapid release and slow release thereafter. Meanwhile, the release behaviours of MPP ions from both nanocomposites were governed by pseudo-second order kinetics. This result highlights the potential of the nanocomposite as an encapsulated material for the controlled-release formulation of MPP anions.     

Use of a Reflectance Spectroscopy Accessory for Optical Characterization of ZnO-Bi(2)O(3)-TiO(2) Ceramics

The optical band-gap energy (E(g)) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. E(g) of the ceramic ZnO + xBi(2)O(3) + xTiO(2), where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. E(g) was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.     

Prediction of Air Specific Heat Ratios at Elevated Pressures Using a Novel Modeling Approach

An accurate and efficient model based on least‐squares support vector machines (LSSVM) is developed for the determination of air specific heat ratios at elevated pressures. Additionally, the coupled simulated annealing optimization strategy is used to calculate the optimal values of the LSSVM parameters. A large dataset of air specific heat ratios as a function of temperature and pressure for about 170 samples is used to develop and validate the model. The leverage approach (Williams plot) is used to determine the applicability domain of the model and to detect probably erroneous data points. Comparison of the obtained results with a previously published correlation as well as an intelligent method demonstrates that the performance of the presented model is more satisfactory than that of other methods.     

Is subcooling the right driving force for testing low-dosage hydrate inhibitors?

The degree of subcooling is usually used as the driving force for hydrate formation; however, it does not encompass the effect of pressure. A comprehensive driving force for hydrate formation is a function of pressure, temperature, and gas composition; however, its calculation is not as simple as that of subcooling. In this work, by application of the two latest driving force expressions for hydrate formation, the relationships between subcooling and the true driving force at different conditions for pure gas-water and natural gas-water systems are analysed. The effect of pressure on the induction time in the presence and absence of a kinetic inhibitor have been tested at similar degrees of subcooling.The results show that for pure gas-water systems subcooling is proportional to the driving force, with a good approximation over a wide pressure range at isothermal conditions. However, for multicomponent systems (e.g., natural gases), the driving force is more than that suggested by subcooling at some pressures. Changes of driving force with pressure at a constant degree of subcooling for the above systems have been presented. The results show that the pressure has no significant effect on the driving force (at a constant degree of subcooling) above a certain pressure range. The experimental results show that in a natural gas-water system at constant degree of subcooling the induction time is not significantly affected by pressure. However, in the presence of the kinetic inhibitor tested in this study, high-pressure conditions decreased the induction time.     

Parametric optimization of NiFe2O4 nanoparticles synthesized by mechanical alloying

In this study, the Taguchi robust design method is used for optimizing ball milling parameters including milling time, rotation speed and ball to powder weight ratio in the planetary ball milling of nanostructured nickel ferrite powder. In fact, the current work deals with NiFe₂O₄ nanoparticles mechanochemically synthesized from NiO and Fe₂O₃ powders. The Taguchi robust design technique of system optimization with the L9 orthogonal array is performed to verify the best experimental levels and contribution percentages (% ρ) of each parameter. Particle size measurement using SEM gives the average particle size value in the range of 59–67 nm. X-ray diffraction using Cu Kα radiation is also carried out to identify the formation of NiFe₂O₄ single phase. The XRD results suggest that NiFe₂O₄ with a crystallite size of about 12 nm is present in 30 h activated specimens. Furthermore, based on the results of the Taguchi approach the greatest effect on particle size (42.10 %) is found to be due to rotation speed followed by milling time (37.08 %) while ball to powder weight ratio exhibits the least influence.     

A Two-parameter Model for the Determination of Optimum Liquefied Petroleum Gasses (LPG) Storage Volume

In this work, a mathematical-based methodology is employed to develop a reliable model for the prediction of safe volume for liquefied petroleum gases (LPG) storage vessels. To this end, a novel soft computing approach namely least square support vector machine (LSSVM) modeling optimized with coupled simulated annealing (CSA) optimization technique is utilized. To evaluate the performance and accuracy of the LSSVM model, graphical (cross plot and error distribution curve) and statistical (error parameters) analyses have been utilized. Additionally, comparative studies are conducted between the LSSVM model and a multilayer perceptron artificial neural network (MLP-ANN) model. Obtained results prove that the proposed CSA-LSSVM model is more robust, reliable and efficient than the developed MLP-ANN model for the prediction of liquid volume correction factor. Consequently, the developed LSSVM model results indicate an average absolute relative deviation equals to 0.02782% from the corresponding liquid volume correction factor literature values, and a squared correlation coefficient of 0.9999.     

The Evaluation of the Impact of Wettability Alteration and Oil Relative Permeability Changes With Temperature During Cyclic Steam Injection in Naturally Fractured Reservoirs Using Horizontal Wells

In this communication, first, cyclic steam injection process in an Iranian heavy oil reservoir was simulated using three horizontal wells and the effect of various operational parameters on the performance was studied. This study has been done on the fractured reservoirs, as there are few studies on cyclic steam injection and the effect of temperature changes on the oil relative permeability in such reservoirs. Then, some practical values of irreducible water saturation and residual oil saturation at different temperatures have been considered for study of their effects on the oil recovery and oil relative permeability, because these practical values are so useful for prediction of production performance. The conclusions indicate that irreducible water saturation and residual oil saturation have significant impact on recovery factor and cumulative steam oil ratio. Comparison of four various methods show the difference in calculated oil relative permeability at various water saturations.     

An Efficient Approach for the Determination of Oil Production Rate During the Water-flooding Recovery Method

In this work, a mathematical methodology namely, least square support vector machine (LSSVM) is implemented to predict the variation of oil production rate as a function of oil water viscosity ratio and water injection rate for water-flooding. Furthermore, the coupled simulated annealing (CSA) optimization technique is coupled with LSSVM to find the optimal architecture and parameters of the LSSVM. The obtained results demonstrate that the CSA-LSSVM estimations are in a satisfactory agreement with literature-reported data and the previously published correlation. Consequently, the R² and average absolute relative deviation of CSA-LSSVM model in testing phase are reported 0.979 and 8.15, respectively.