Hydrophilic antioxidants of virgin olive oil. Part 1: Hydrophilic phenols: A key factor for virgin olive oil quality

Virgin olive oil (VOO) consumption is increasing all over the world due to its excellent organoleptic and nutraceutical properties. These beneficial traits stand from a prominent and well‐balanced chemical composition, which is a blend of major (98% of total oil weight) and minor compounds including antioxidants. The main antioxidants are phenolic compounds, which can be divided into lipophilic and hydrophilic phenols. While lipophilic phenols such as tocopherols can be found in other vegetable oils, most hydrophilic phenols in olive oil are exclusive of the Olea europaea species endowing it with a chemotaxonomic interest. This review is focused on VOO antioxidant profile and, particularly, on hydrophilic phenols that are divided into different sub‐families such as phenolic acids and alcohols, hydroxy‐isochromans, flavonoids, secoiridoids, lignans and pigments. Analytical methods for qualitative and/or quantitative determination of these compounds are assessed. The implementation of efficient sample preparation protocols, separation techniques such as liquid chromatography, GC and capillary electrophoresis, as well as detection techniques such as ultraviolet absorption, fluorescence or MS are critical to succeed in the quality of the results. The effects of hydrophilic phenols on increasing VOO stability, its nutraceutical interest and organoleptic properties are also considered.     

Improving the electrical conductivity of ethylene 1‐octene copolymer/cyclic olefin copolymer immiscible blends by interfacial localization of MWCNTs

The localization of multiwall carbon nanotubes (MWCNTs) in the immiscible blends of ethylene–1‐octene copolymer (EOC) and cyclic olefin copolymer (COC) with the sea–island morphology and electrical conductivity of resulting nanocomposites were investigated. Depending on the feeding orders, as the MWCNTs were located in the COC droplet, the electrical conductivity was obtained as high as 5.71 × 10^?7 S/cm, while the MWCNTs were located in EOC/COC interface, the electrical conductivity increased significantly up to 1.72 × 10^?2 S/cm. The improved electrical conductivity in EOE/COC/MWCNTs nanocomposite is attributed to the interfacial localization of MWCNTs which is resulted from thermodynamic affinity of MWCNTs to COC, as well as an interconnected structure via deformed and swelled COC droplets. Thermodynamic affinity of MWCNTs to COC and established interconnected structure are confirmed by rheological characterization, microscopic observations, dynamic mechanical analysis, and electrical conductivity measurements. Therefore, as a result of selective localization of MWCNTs and well‐designed phase morphology, lower rheological and especially electrical percolation thresholds could be obtained in the ternary nanocomposites compared to the binary systems. POLYM. ENG. SCI., 59:447–456, 2019. © 2018 Society of Plastics Engineers     

Design of 3‐aminophenol‐grafted polymer‐modified zinc sulphide nanoparticles as drug delivery system

Zinc sulphide (ZnS) nanoparticles were synthesized by the coprecipitation method. The ZnS nanoparticle surface was polymerized with allyl glycidyl ether (AGE), and 3‐aminophenol was then deposited as a ligand on nanosorbent. The modified nanosorbent was investigated with Fourier transform infrared spectroscopy and thermogravimetric analysis. The particle size of the modified nanosorbent was studied with scanning electron microscopy. Some characteristic factors of the adsorption process such as pH and time were investigated for famotidine using the modified nanosorbent. The equilibrium adsorption study of famotidine by 3‐aminophenol‐grafted AGE/ZnS was analysed by adsorption isotherms of the Langmuir, Freundlich, and Temkin models. The famotidine‐releasing process was investigated in simulated biological fluids (intestinal fluid at pH of 7.4 and gastric fluid at pH of 1.2) and demonstrated 65% and 73% famotidine release during periods of 30 h (pH = 7.4) and 60 min (pH = 1.2), respectively. These results reveal the optimal performance of 3‐aminophenol‐grafted AGE/ZnS for sustained drug delivery.     

An evaluation of modified silica nanoparticles’ efficiency in enhancing oil recovery of light and intermediate oil reservoirs

The role of nanoparticles in enhancing oil recovery from oil reservoirs is an increasingly important topic of research. Nanoparticles have the properties that are potentially useful for enhanced oil recovery processes, as they are solid and two orders of magnitude smaller than colloidal particles. This paper presents a comparison between the efficiency of modified silica nanoparticles in enhancing oil recovery from two different Iranian light and intermediate oil reservoirs. The mechanisms used to recover additional oil would be oil–water interfacial tension reduction and wettability alteration. Oil phase contact angles and oil–water interfacial tensions were measured in the absence and the presence of nano fluids’ different concentrations (1–4 g/L). Results showed that the interfacial tension reduces dramatically in the presence of nanoparticles for both light and intermediate oil. In addition oil phase contact angle results showed a transformation of rock wettability from water-wet toward oil-wet condition. However, these nanoparticles are more capable in the reduction of the interfacial tension and the alteration of wettability in the case of light oil reservoir. A comparison between recovery results indicated that these nanoparticles are more efficient in light oil reservoirs and produce more incremental amount of oil after primary and secondary processes.     

Reaction kinetics to infer the effect of dopants on ion transport - A case study for Mo+6 doped lithium titanates (Li2TiO3-δ and Li4Ti5O12-δ)

In this paper, a unique approach to correlate influence of doping on ionic mobility, through thermo-kinetic analysis, is reported. Formation kinetics of Li₂TiO₃ and Li₄Ti₅O₁₂, with Mo⁺⁶ doping, were successfully analyzed in ultra-pure Ar atmosphere using differential scanning calorimetry. The results were compared with formation kinetics of pure Li₂TiO₃ and Li₄Ti₅O₁₂ under identical conditions. Field emission scanning electron microscopy (FE-SEM) with electron diffraction spectroscopy (EDS), X-ray diffraction and Raman spectroscopy were employed for the characterization of resulting phases and presence of oxygen vacancy. The results indicate that for doped samples, oxygen vacancy concentration was reduced due to the charge compensation mechanism of the doped ion. The activation energy (E_α) of the different reactions with and without Mo⁺⁶ doping was determined by Kissinger-Akahira-Sunose method. The most probable reaction mechanism was predicted through Master plot approach. The reaction rate controlling step shifted from three-dimensional diffusion (D₃) for undoped Li₂TiO₃ to a chemical reaction (F_n) for doped Li₂TiO₃. For Li₄Ti₅O₁₂ the reaction mechanism (or rate controlling step) was a chemical reaction (F_n) for undoped and nucleation (A_n) for doped material. The results show that diffusion of ions becomes faster in the Mo⁺⁶ doped materials by reducing the charge transfer resistance. Finally, the thermodynamic functions of the transition complex were calculated from kinetic triplets and correlated with thermo-kinetic data.     

Heat transfer characteristics of an external-fin-assisted two-phase closed thermosyphon: An experimental study

In the current paper, the performance of an external-fin-assisted thermosyphon is investigated experimentally. The thermosyphon is produced with a copper tube and includes three parts—the evaporator, the adiabatic, and the condenser. The condenser part is enhanced with external longitudinal fins. In this study, different number of fins, filling ratios (FRs), coolant flow rates, a wide range of heat inputs, and initial absolute pressures are considered. The experiments are carried out by measurement of temperature distribution of the thermosyphon's wall and the temperature difference of the coolant. The results depict that increasing the heat input and FR reduces the thermal resistance, while raising the coolant flow rate augments the thermal resistance. Adding external fins to the condenser causes further condensation, which enhances the thermosyphon thermal performance by a reduction of 26.32% in thermal resistance and an increment of 28.55% in the thermosyphon efficiency.     

Heat capacity of the AuZr compound obtained by high-temperature drop calorimetry

The enthalpy increments of the Zr_0.50Au_0.50 phase have been measured by high-temperature drop calorimetry in the temperature range 372–1245 K. From these results, heat capacities of ZrAu have been derived and two changes of the C_p values have been observed, in agreement with the existence of three crystalline forms of ZrAu. No latent heat was observed for the low-temperature (564 K) transition, whereas the enthalpy change at high temperature (841 K) was estimated at 1.55 kJ·mol^?1, from enthalpy increments obtained by drop calorimetry. These results are discussed in relation to the crystal modifications already reported for the ZrAu compound.     

Application of sepiolite in clarification of pomegranate juice: changes on quality characteristics during process

In this study, for the first time, the function of acid‐activated sepiolite clay was evaluated for clarification of pomegranate juice. The optimum conditions of clarification process were achieved using response surface methodology based on juice turbidity as a response. After that, under optimal condition, efficiency of sepiolite, bentonite and combination of these fining agents with gelatin and kieselgel was compared for clarifying pomegranate juice. The results showed that the best conditions for juice clarification were 0.05% (w/v) clay concentration, temperature of 50 °C and time of 2 h. The results revealed that treatments of bentonite–gelatin–kieselgel and sepiolite–gelatin–kieselgel were the most active fining agents that their use led to a reduction of 99.7% in turbidity of pomegranate juice. Kinetic study for different features was performed, and the results indicated that rate of changes in turbidity, viscosity, total phenolic contents and colour with time followed first‐, first‐, zero‐ and zero‐order kinetic models, respectively.