Chemical Stability of α‐Tocopherol in Colloidal Lipid Particles with Various Morphologies

Colloidal lipid particles (CLPs) are promising encapsulation systems for lipophilic bioactives, such as oil‐soluble antioxidants that are applied in food and pharmaceutical formulations. Currently, there is no clear consensus regarding the relation between particle structure and the chemical stability of such bioactives. Using α‐tocopherol as a model antioxidant, it is shown that emulsifier type (Tween 20 or 40, or sodium caseinate) and lipid composition (tripalmitin, tricaprylin, or combinations thereof) modulated particle morphology and antioxidant stability. The emulsifier affects particle shape, with the polysorbates facilitating tripalmitin crystallization into highly ordered lath‐like particles, and sodium caseinate resulting in less ordered spherical particles. The fastest degradation of α‐tocopherol is observed in tripalmitin‐based CLPs, which may be attributed to its expulsion to the particle surface induced by lipid crystallization. This effect is stronger in CLPs stabilized by Tween 40, which may act as a template for crystallization. This work not only shows how the architecture of CLPs can be controlled through the type of lipid and emulsifier used, but also gives evidence that lipid crystallization does not necessarily protect entrapped lipophilic bioactives, which is an important clue for encapsulation system design. Practical Applications: Interest in enriching food and pharmaceutical products with lipophilic bioactives such as antioxidants through encapsulation in lipid particles is growing rapidly. This research suggests that for efficient encapsulation, the particle architecture plays an important role; to tailor this, the contribution of both the lipid carrier and the emulsifier needs to be considered.     

Lead recovery from aqueous environment by using porous carbon of citrus fruits waste: equilibrium,kinetics and thermodynamic studies

ABSTRACT

The mixture of citrus fruits (orange, grapefruit, mandarin, and lemon) wastes was utilized to obtain high surface area activated carbon (AC) by H₃PO₄ activation. The production conditions were optimized and the optimum conditions were determined. The optimal-activated carbon (CFWAC) was characterized by various physicochemical techniques. CFWAC was also used as a sorbent for Pb (II) ions from water. Batch experiments were performed to explore the adsorption capacity and mechanism. The Langmuir isotherm and pseudo-second-order kinetic model showed good fitness to the experimental data. The maximum Pb (II) adsorption capacity of CFWAC was found to be 163.93 mg/g.     

Surface analysis and adsorption behavior of caffeine as an environmentally friendly corrosion inhibitor at the copper/aqueous chloride solution interface

Abstract

Corrosion inhibitors based on environmentally friendly and harmless products are currently being studied and developed. The corrosion inhibition properties of caffeine (1,3,7-trimethylxanthine) on copper corrosion in aqueous chloride solution (3.5?wt.% NaCl) are analysed here using stationary and transient electrochemical methods, and a theoretical study based on density functional theory is carried out. Caffeine is a very competitive compared to the chemical inhibitors that are often used for copper protection. Electrochemical and impedance experiments reveal that the protective efficiency of caffeine reaches a value of 96% at a concentration of 10^?2?mol L^?1. Based on these results, the Langmuir model appears to be the best representation of the adsorption of caffeine onto the copper surface. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used to determine the surface morphology and the chemical composition of the copper surface in chloride media, in the absence and presence of caffeine. The results show the development of a mechanism of corrosion inhibition. In order to confirm the correlation between the inhibitory effect and the molecular structure of caffeine, quantum chemical parameters are used to calculate its electronic properties.     

Inactivation of Fusarium oxysporum Conidia in Soil with Gaseous Ozone – Preliminary Studies

ABSTRACT

In this study, the efficiency of gaseous ozone (O₃) injected in the soil as an oxidizing agent for the inactivation of F. oxysporum was evaluated under laboratory conditions. The results show the treatment reached an inactivation efficiency of 76% after an applied dose of 0.40 g O₃ kg ^?1 soil. This shows that the injection of O₃ can be a viable alternative to control pathogenic organisms in the soils. Nevertheless, it is clear that more studies on determining the effects of this treatment on soil quality are needed.     

Microstructure and mechanical behavior of alumina-zirconia-mullite refractory materials

The synthesis of Al₂O₃-ZrO₂-SiO₂ (AZS) refractory materials for use in furnace chambers for glass melting has been studied in this work. Several mixtures with different alumina-zirconia-silica ratios, corresponding to compositions selected within the ternary phase diagram Al₂O₃-ZrO₂-SiO₂, were processed by attrition milling followed by pressing and reactive sintering at different temperatures (1450, 1550 and 1650 °C). The density of the sintered samples varied significantly with respect to that of the green materials, with increases of up to 90% in this property after sintering at 1650 °C. The X-ray diffraction patterns revealed the formation of the predicted phases (ZrO₂, Al₆Si₂O₁₃ and Al₂O₃) according to the ternary phase diagram for all compositions studied, with varying amounts of each formed phase. SEM characterization showed that the sintering temperature employed made a significant difference regarding the final microstructure of the sintered materials. For the studied compositions, the maximum resistance to fracture (MRF) was 185 MPa, with the highest values of fracture toughness obtained at 1650 °C.     

Preliminary study of saffron (Crocus sativus L. stigmas) color extraction in a dairy matrix

Saffron spice has been used for decades as an ingredient in many dairy products but changes in its coloring properties related to milk characteristics have not been paid appropriate attention. Saffron color was studied in ewes’ milk at different fat levels and saffron concentrations using tristimulus colorimetry. In order to evaluate saffron extraction, different temperatures and extraction times were tested. Color changes were demonstrated to be statistically significant when increasing the fat content in milk, as well as saffron concentration. The higher milk fat content, turned the extracts brighter and yellower, while less red and vivid, opposite to results obtained by increasing saffron concentration. Extraction time was not significant for color extraction. Milk extracts resulted slightly brighter and yellower when increasing temperature, probably due to crocetin esters degradation or isomerization from trans to cis configuration. Temperatures between 37 and 70 °C are recommended to avoid structural changes in milk or saffron. Color changes could be due to interactions mediated by phospholipids between milk fat globules and crocetin esters, as well as minor saffron carotenoids.     

Study of the structure directing effect of the chiral cation (1S,2S)-2-hydroxymethyl-1-benzyl-1-methylpyrrolidinium in aluminosilicate preparations in the presence of co-structure directing agents

We explore the structure directing role of the chiral cation (1S,2S)-2-hydroxymethyl-1-benzyl-1-methylpyrrolidinium (SS-bmpm) in the synthesis of Al-containing zeolite materials in the presence of co-structure directing agents (co-SDAs). Three different co-SDAs are studied: tetramethylammonium (TMA), quinuclidine and sodium. Synthesis with TMA as co-SDA yields a ferrierite related phase and a material from the MWW family, where the SS-bmpm and the TMA cations are incorporated intact within the samples. Quinuclidine produces instead amorphous solids, while the use of Na⁺ leads to crystalline phases that crystallized as a result of the degradation of the SS-bmpm cation. A subsequent computational study based on molecular mechanics was performed in an attempt to unravel the location of TMA and SS-bmpm cations within the void space of the complex MWW structure. The results suggest that the sinusoidal channels are exclusively filled by TMA, while the bulky SS-bmpm cations can only be accommodated within the MWW super-cages, thus providing a new example of cooperative structure-directing effects of small and bulky cations in the synthesis of complex zeolite structures.     

Structural and physical properties of microwave synthesized orthorhombic perovskite erbium chromite ErCrO3

Rare-earth chromite ErCrO₃ powder was synthesized from metal nitrate precursors using microwave synthesis. (Micro-) structural characterizations were performed using X-ray diffraction, Rietveld refinement, High Resolution Transmission Electron Microscopy and Electron Micro-Diffraction. Magnetization vs. temperature measurements revealed anti-ferromagnetism with T_Neel ≈ 135 K. An anti-ferrimagnetic moment of ≈0.4 μ_B was determined from magnetization vs. applied field measurements. Temperature dependent impedance spectroscopy (IS) indicated 3 dielectric relaxation processes: electrode interface, grain boundary and bulk. The intrinsic bulk activation energy was found to be 0.27 eV and the dielectric permittivity ?_r was ≈23 in excellent agreement with Clausius-Mossotti predictions and showed no perceptible temperature dependence. This and the low ?_r value suggested that ErCrO₃ is a dielectric rather than ferroelectric compound. IS measurements with applied dc bias revealed the signs of an unconventional type of Schottky barrier at the metallic Au electrode/ceramic ErCrO₃ interface.