Margarine-Like Emulsions Prepared with Coconut and Palm Oils: Analysis of Microstructure and Freeze–Thaw Stability by Differential Scanning Calorimetry

The objective was to study the microstructure and freeze–thaw stability of margarine-like emulsions formulated with vegetable fats using differential scanning calorimetry. Emulsions were prepared with 20% w/w dispersed aqueous phase and a continuous lipid phase composed by coconut oil (CO) and/or palm oil (PO) plus polyglycerol polyricinoleate (PGPR) as emulsifier. Mean temperature (T_M) and crystallization enthalpy (ΔH_c) were obtained from the exothermic peaks corresponding to freezing of aqueous phase. Successive cooling–heating–cooling cycles were applied to analyze changes in the exothermic peak. The emulsion prepared with CO (without PO) and 1% w/w PGPR in lipid phase showed higher water droplets size (T_M = −44.8 ± 0.1 °C) and lower quantity of stabilized aqueous phase (ΔH_c = 28.9 ± 1.2 J g⁻¹) prior to application of temperature cycles, while coalescence and (presumably) water transfer processes occurred during the treatment. The use of 2% w/w PGPR was sufficient to accomplish full stabilization of aqueous phase (T_M = −45.9 ± 0.1 °C; ΔH_c = 42.6 ± 0.3 J g⁻¹) before and after the freeze–thaw treatment. The total or partial (50%) substitution of CO by PO in emulsions with 1% w/w PGPR also improved the stability of the system, exhibiting slight microstructural changes. This enhanced stability would be linked to reduced water droplets size because of more rapid crystallization of lipid phase and immobilization of aqueous phase after emulsion preparation. In conclusion, it is possible to obtain margarine-like emulsions prepared with CO and/or PO using relatively low emulsifier concentration and maintaining a desired microstructure after freeze-thawing if the percentage ratio of both fats is controlled.     

A Study of Thermodynamic Characteristics of the Zn2P2O7–M4P2O7(M= Li and Na) Systems by Differential Scanning Calorimetry

Glasses, crystals, and melts in the Zn₂P₂O₇–M ₄P₂O₇(M= Li and Na) systems are studied by differential scanning calorimetry (DSC). Temperature dependences of the heat capacity and the enthalpies of melting of Zn₂P₂O₇and Na₂ZnP₂O₇crystals are determined. The thermodynamic characteristics obtained are used for calculating the liquidus curve for the Zn₂P₂O₇–Na₂ZnP₂O₇subsystem on the basis of the Schröder relationship with due regard for the temperature dependences of the enthalpy of melting for components and the nonideal behavior of melts. Reasoning from the Hruby empirical formula, the inference is drawn that the crystallization ability of lithium–zinc phosphate glasses is higher than that of sodium–zinc phosphate glasses. The radius of cooperative motion in the glass transition range for glasses in the Zn₂P₂O₇–Na₄P₂O₇system is estimated in the framework of the phenomenological thermokinetic fluctuation theory. It is assumed that an increase in the radius with an increase in the alkali oxide content is associated with an increase in the ionicity of bonds.     

Homogeneous Liquid–Liquid Extraction and Determination of Cobalt,Copper, and Nickel in Water Samples by Flame Atomic Absorption Spectrometry

Abstract

A simple and effective homogeneous liquid–liquid extraction method has been used for the simultaneous extraction and preconcentration of cobalt, copper, and nickel after the formation of complex with 4‐benzylpiperidinedithiocarbamate potassium salt (K‐4‐BPDC), and later they were determined by flame atomic absorption spectrometry (FAAS) using (water/tetrabutylammonium ion (TBA⁺)/chloroform) as a ternary component system. The phase separation phenomenon occurred by an ion‐pair formation of TBA⁺ and perchlorate ion. After the optimization of complexation and extraction conditions ([K‐4‐BPDC]=2.0×10^?4 mol l^?1, [TBA⁺]=2.0×10^?2 mol l^?1, [CHCl₃]=60.0 µl, [ClO₄ ^?]=2.0 ×10^?2 mol l ^?1 and pH=6.0), a preconcentration factor of 200 was obtained for only 10 ml of the sample.

The analytical curves were linear in the range of 20–1500, 15–2000, 35–1600 µg l^?1 and the limits of detection were 10, 5, and 15 µg l^?1 for Co²⁺, Cu²⁺, and Ni²⁺, respectively. The proposed method was applied for the extraction and determination of Co²⁺, Cu²⁺, and Ni²⁺ in natural water samples with satisfactory results.     

The Role of Lignin in Surface-Activated Bonding of Lignocellulose—Characterized by Differential Scanning Calorimetryt

The study of surface modification to prepare an optimum surface for bonding is of practical importance for the production of glued materials. Lignocellulosic materials contain many chemical groupings such as phenolic and alcoholic hydroxyls, carbonyl groups, etc., capable of being readily activated by physical or chemical methods. These active sites can then react under heat and pressure, either with active sites from another surface, or through a crosslinking agent to form a glued product.

This paper reports the role of lignin in the reactions between lignocellulosic materials and hydrogen peroxide studied by a differential scanning calorimetry method. The results showed that lignin is much more reactive toward hydrogen peroxide than is cellulose, and that the lignin-hydrogen peroxide reaction yields the highest enthalpy. Correlation between lignin and enthalpy, and enthalpy and bonding will also be discussed.     

Differential Regulation of ABCA1 and Macrophage Cholesterol Efflux by Elaidic and Oleic Acids

Trans fatty acid consumption is associated with an increased risk of coronary heart disease. This increased risk has been attributed to decreased levels of HDL cholesterol and increased levels of LDL cholesterol. However, the mechanism by which trans fatty acid modulates cholesterol transit remains poorly defined. ATP-binding cassette transporter A1 (ABCA1)-mediated macrophage cholesterol efflux is the rate-limiting step initiating apolipoprotein A-I lipidation. In this study, elaidic acid, the most abundant trans fatty acid in partially hydrogenated vegetable oil, was shown to stabilize macrophage ABCA1 protein levels in comparison to that of its cis fatty acid isomer, oleic acid. The mechanism responsible for the disparate effects of oleic and elaidic acid on ABCA1 levels was through accelerated ABCA1 protein degradation in cells treated with oleic acid. In contrast, no apparent differences were observed in ABCA1 mRNA levels, and only minor changes were observed in Liver X receptor/Retinoic X receptor promoter activity in cells treated with elaidic and oleic acid. Efflux of both tracers and cholesterol mass revealed that elaidic acid slightly increased ABCA1-mediated cholesterol efflux, while oleic acid led to decreased ABCA1-mediated efflux. In conclusion, these studies show that cis and trans structural differences in 18 carbon n-9 monoenoic fatty acids variably impact cholesterol efflux through disparate effects on ABCA1 protein degradation.     

Synergism and Interfacial Property Study of Sodium Lauryl Ether Sulfate and Polysorbate 80 at the Air–Water Interface

Adsorption and micellization behavior of sodium lauryl ether sulfate (SLES) and Polysorbate 80 (PS80) was investigated using equilibrium and dynamic surface tension and foaming measurements. Critical micelle concentration (CMC) was determined using surface tension and dye (Sudan red III) solubilization method with the help of the Wilhelmy plate method and ultraviolet–visible spectroscopic method, respectively. The strength of the interaction for micellization and adsorption between the mixtures are calculated using the β interaction parameter. The SLES-PS80 mixture shows synergistic interaction with β = −8.0. The dynamic and foaming behavior at constant bulk concentration showed a higher t ^* value with lowest foaming at 50% mole fraction of SLES. The emulsification index (EI) of pure SLES, pure PS 80, and 1:1 SLES-PS 80 composition was studied using neem, karanja, and sunflower oils. Karanja and sunflower oils show a higher EI for mixture than the pure surfactants, whereas neem shows a lower EI for mixture than pure surfactants.     

Influence of Characteristics of Nickel Complex Compounds on the Rate of Chemical Deposition and Composition of Nickel–Phosphorus Alloy

Theoretical Foundations of Chemical Engineering - The influence of characteristics of ligands and nickel complex compounds on the rate of the autocatalytic (chemical) deposition of...     

Thermal Expansion of Melts and Glasses in the As–Se System

The bulk thermal expansion coefficients of glasses and melts in the As–Se system are measured in the temperature range 298–1200 K. In glass-forming melts containing 40–60 mol % As, an increase in the density is found at temperatures above 1000 K, which is assumed to be associated with changes in the structure and character of the chemical bonding.     

Corrosion and Infrared Study of Some γ-Irradiated Lead-Phosphate Glasses Doped with MoO3

In this study we compared the effect of three different concentrations of MoO₃ on the corrosion of sodium phosphate glass containing lead and aluminum oxides to develop its durability. The corrosion was studied in deionized water and acidic solution of 0.1 N HCl. The dissolution mechanism is interpreted depending on the glass weight loss versus time and change in the glass surface. MoO₃ had a stabilizing effect on the glass, causing a decrease in the glass dissolution rate. Acidic medium was found to strongly enhance the glass dissolution. The pH decrease in water with increase in acidic solution gives evidence of the release of some phosphorous ions to form phosphoric acid. The consequent enhancement of the glass durability was influenced by the presence of MoO₃ and showed a remarkable advance by doping with 3 wt% of MoO₃. FT-infrared absorption spectra of the studied glasses show IR vibrational bands due to phosphate groups mainly of the metaphosphate and pyrophosphate units together with the sharing and interference of IR vibrations due to Pb–O bonds. Gamma irradiation produces a minor effect on the IR spectra, and enhances the base glass durability at the beginning of the corrosion process, which can be related to the shielding behavior of the high lead glass. However, glass containing 3% MoO₃ has the best durability and is the least affected by irradiation. The glass durability corresponding to its structure is verified by IR spectroscopy.

     

A Study of Ionic Conductivity of Glasses in the PbCl2–PbO · B2O3 and PbCl2–2PbO · B2O3 Systems

The steady-state electrical conductivity of oxychloride glasses in the PbCl₂–PbO · B₂O₃ and PbCl₂–2PbO · B₂O₃ systems is investigated. In the temperature range from 190 to 380°C, the dependence of log on the reciprocal of the temperature exhibits a linear behavior. The nature of charge carriers is studied using the Hittorf technique. It is demonstrated that protons and chlorine ions are charge carriers in solid glasses. The concentration dependence of the transport numbers of chlorine ions is examined by the Tubandt method. The contribution of the electronic component to the total electrical conductivity is estimated with the use of the Liang–Wagner technique. The concentration dependences of the electrical conductivity and the transport numbers of chlorine ions are interpreted in terms of the microinhomogeneous glass structure associated with the selective interaction of components during synthesis of glasses.     

Comparative Study of Approaches based on the Taguchi and ANOVA for Optimising the Leaching of Copper–Cobalt Flotation Tailings

Approaches based on Taguchi and analysis of variance (ANOVA) methods have been proposed for studying the leaching of copper–cobalt flotation tailings. Taguchi method was used to determine the optimum leaching conditions as well the most influential operating parameters. ANOVA was used to determine the relationship between the experimental conditions and yield levels, as well as to define the significances of parameters on the leaching yields. An L₂₅(5⁵) orthogonal array experimental plan was used to assess the effects of initial acidity (25, 50 , 75, 100, and 125?g/L), leaching time (30, 60, 90, 120, and 150?min), temperature (25, 35, 45, 55, and 65°C), pulp density (S/L?=?10, 15, 20, 25, and 30 solid percent), and ferrous iron concentration (0.0, 1.0, 2.5, 5.0, and 7.5?g/L) on individual dissolution of Cu and Co. Under the optimum conditions (50?g/L, 60?min, 45°C, 15%, 2.5?g/L for Cu; and 100?g/L, 60?min, 65°C, 15% and 2.5?g/L for Co), leaching yields were 95.98% Cu and 97.74% Co. pH and Fe²⁺ were found to be key influential parameters of Cu and Co, respectively.     

The Influence of Copper–Copper Interaction on the Structure and Applications of a Metal–Organic Framework Based on Cyanide and 3-Chloropyridine

The structure of the new metal–organic framework, [(CuCN)₂·(3-Clpy)], 1, was characterized by IR, UV–visible, TGA and X-ray single crystal analysis. The structure of 1 consists of CuCN building blocks, which are connected by CN group to form two different chains; one puckered chain with TP-3 geometry around Cu(1) and a linear Cu(2)(CN)₂ chain. The two kinds of chains are bonded by cuprophilic interactions creating a 3D-network. The network structure of 1 is further close-backed by π–π stacking and hydrogen bonds. The electronic absorption and emission spectra as well as the thermodynamic parameters from TGA of the MOF 1 are discussed. MOF 1 was used as an effective heterogeneous catalyst for the oxidative discoloration of methylene blue dye by dilute solution of hydrogen peroxide as the oxidant. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the in vitro antitumor activity of MOF 1 on human breast cancer cell line, MCF7.     

Extraction of cadmium by TODGA–dodecane and TBP–dodecane: A comparative study by MD simulation

Molecular dynamics (MD) simulation of [Cd(II)] along with nitrate ions and water in dodecane was carried out for different nitric acid concentrations. The extraction process using N,N,N’,N’-tetraoctyldiglycolamide (TODGA) and tributyl phosphate (TBP), in biphasic systems, is also simulated at three nitric acid concentrations. In the TBP-based system, the formation of a third phase was observed at 3 M nitric acid concentration. Cd(II) ions form reverse micelles-like clusters with TODGA as an extractant in dodecane. The mass percentage of TODGA in these clusters decreases with increase in the acid concentration while increasing the size of the aggregates at the same time.     

Spectroscopic Study on the Nature of Active Entities in Copper–Ceria CO-PROX Catalysts

A series of oxidised copper-ceria catalysts with varying copper loadings and prepared by two different methods (impregnation of ceria and coprecipitation of the two components within reverse microemulsions) have been examined with the aim of determining the nature of active entities for the two main (CO and H₂) competing oxidation reactions that take place during preferential oxidation of CO in H₂-rich streams over this type of catalysts. The analysis is mainly based on operando spectroscopic exploration by DRIFTS and XANES as well as in situ analysis by Raman. The results allow establishing a model of the catalytic behaviour of this type of catalysts which can provide keys to control their CO-PROX catalytic properties.     

Study of the Selectivity of Binary Agents by Gas–Liquid Chromatography

Theoretical Foundations of Chemical Engineering - The selective properties of individual and binary agents are compared according to data obtained by gas–liquid chromatography (GLC). The...     

Inward and Outward Diffusion of Modifying Ions and its Impact on the Properties of Glasses and Glass–Ceramics

In this paper, we review our recent findings about both the cationic inward and outward diffusion processes in glasses and glass–ceramics caused by redox reactions. We provide new insights into these findings by mapping the diffusion depth, the thermal reduction temperature, and time in a three dimensional diagram and by looking into the correlation among the glass composition, structure, topology, and the diffusion process in the polyvalent elements containing glasses. We illustrate the link between glassy dynamics (via the liquid fragility index m) and activation energy of diffusion. Furthermore, the inward diffusion approach is used to study percolation phenomena in glass–ceramics. Finally, we show that the diffusion approaches are potential tools for tailoring the surface performances of bulk glasses and glass fibers.