Pseudoternary System Research Articles

Investigation of surfactant/cosurfactant synergism impact on ibuprofen solubilization capacity and drug release characteristics of nonionic microemulsions

The current study investigates the performances of the multicomponent mixtures of nonionic surfactants regarding the microemulsion stabilisation, drug solubilization and in vitro drug release kinetic. The primary surfactant was PEG-8 caprylic/capric glycerides (Labrasol®). The cosurfactants were commercially available mixtures of octoxynol-12 and polysorbate 20 without or with the addition of PEG-40 hydrogenated castor oil (Solubilisant gamma® 2421 and Solubilisant gamma® 2429, respectively). The oil phase of microemulsions was isopropyl myristate. Phase behaviour study of the pseudo-ternary systems Labrasol®/cosurfactant/oil/water at surfactant-to-cosurfactant weight ratios (Km) 40:60, 50:50 and 60:40, revealed a strong synergism in the investigated tensides mixtures for stabilisation of microemulsions containing up to 80% (w/w) of water phase at surfactant +cosurfactant-to-oil weight ratio (SCoS/O) 90:10. Solubilization of a model drug ibuprofen in concentration common for topical application (5%, w/w) was achieved at the water contents below 50% (w/w). Drug free and ibuprofen-loaded microemulsions M1–M6, containing 45% (w/w) of water phase, were prepared and characterized by polarized light microscopy, conductivity, pH, rheological and droplet size measurements. In vitro ibuprofen release kinetics from the microemulsions was investigated using paddle-over-enhancer cell method and compared with the commercial 5% (w/w) ibuprofen hydrogel product (Deep Relief®, Mentholatum Company Ltd., USA). The investigated microemulsions were isotropic, low viscous Bingham-type liquids with the pH value (4.70–6.61) suitable for topical application. The different efficiency of the tensides mixtures for microemulsion stabilisation was observed, depending on the cosurfactant type and Km value. Solubilisant gamma® 2429 as well as higher Km (i.e., lower relative content of the cosurfactant) provided higher surfactant/cosurfactant synergism. The drug molecules were predominantly solubilized within the interface film. The amount of drug released from the formulations M3 (10.75%, w/w) and M6 (13.45%, w/w) (Km 60:40) was limited in comparison with the reference (22.22%, w/w) and follows the Higuchi model. Microemulsions M2 and M5 (Km 50:50) gave zero order drug release pattern and ∼15% (w/w) ibuprofen released. The release profiles from microemulsions M1 and M4 (Km 40:60) did not fit well with the models used for analysis, although the amounts of ibuprofen released (24.47%, w/w) and 17.99% (w/w), respectively) were comparable to that of the reference hydrogel. The drug release mechanism was related with the surfactant/cosurfactant synergism, thus the lower efficiency of the tensides corresponded to the faster drug release.

Phase equilibria in the “SnO”–SiO2–“FeO” system in equilibrium with tin–iron alloy and the potential application for electronic scrap recycling

Abstract Experimental studies have been conducted to determine the primary phases and liquidus temperatures in the pseudo-binary system “SnO”–“FeO” and the pseudo-ternary system “SnO”–SiO2–“FeO” in equilibrium with tin–iron alloy between 1148 and 1673 K, using a high-temperature equilibration and quenching technique followed by electron probe X-ray microanalysis of the phase compositions in the quenched samples. The following primary phase fields were identified: wustite (FeO x ), spinel (Fe( 3 – x )Sn x O4), fayalite (Fe2SiO4), tridymite (SiO2), tin iron silicate (Fe4Si2Sn7O16), and cassiterite (SnO2). With this new information on the chemistry of the “SnO”–SiO2–“FeO” slag this system may potentially be used for the processing and recycling of electronic scrap and the recovery of valuable minor elements.

Phase separation and thermoelectric properties of the Pb0.25Sn0.25Ge0.5Te compound

The Pb0.25Sn0.25Ge0.5Te compound is a promising p-type thermoelectric material. It is single phased at elevated temperature and undergoes upon cooling an allotropic transformation from the cubic Geβ, to the rhombohedral Geα structure. In addition, a phase separation takes place in the course of aging treatments within the miscibility gap at lower temperature. The phase separation in this pseudo-ternary system takes place by a discontinuous precipitation process, giving rise to a heterogeneously nucleated coupled structure of Pb- and Ge-rich lamellae, with 102nm to 2μm wide spacing. The presence of Sn atoms in the structure tends to suppress the spinodal decomposition and is characteristic of the low Sn content compounds. The phase separation by discontinuous precipitation follows the Johnson–Mehl–Avrami kinetics. In the course of further lengthy aging treatments at 390°C, the microstructure consists of spheroidized Ge-rich precipitates in a Pb-rich telluride matrix. The thermoelectric transport properties undergo significant changes in the initial stages of the phase separation process, leading to a stable and relatively elevated figure of merit, ZT=0.95±0.07 at 400°C.

Application of the CBSM method for selected ternary and pseudo-ternary L + L systems, and novel criterion for extractants capability

This paper presents the Component Binding by Saturation Model (CBSM) method for correlation of LLE phase composition data for 23 ternary systems and 1 pseudo-ternary system, including both polar and non-polar solutes. In focus on extraction water systems, partition and binding isotherms are proposed, and their parameters are found. Tie-line data are correlated, and critical point data for the example LLE are estimated. To select suitable extractants for the example extraction systems, particularly for the group of water+ethanol+extractant systems, the integral and relative integral capacity criterion is introduced and applied. To assess and/or predict the concentration extent of extractants using, the integral capacity is defined. To predict the capability of the extractants to bind the partitioning component, the relative integral capacity is defined. For the systems with a basic partition mechanism, the general relationship between relative integral capacity and partition constant is expressed and verified. For the extraction systems with associative partition mechanism from the ethanol group ternaries, the empirical relation between the multiparametric variable formed from the partition isotherm parameters and the relative integral capacity is found.

Phase equilibria in the Ag2Se-As2Se3-Bi2Se3 system

We have studied phase equilibria in the pseudoternary system Ag2Se-As2Se3-Bi2Se3 and constructed the 300-, 600-, and 800-K isothermal sections, a number of partial phase diagrams, and the liquidus projection of this system. The AgAsSe2-AgBiSe2 and As2Se3-AgBiSe2 joins are shown to be pseudobinary, and the Ag3AsSe3-AgBiSe2 and AgAs3Se5-AgAsSe2 joins are pseudobinary below the liquidus. Several in- and univariant peritectic, eutectic, and eutectoid equilibria and a broad region of AgBiSe2-based solid solutions are identified. The homogeneity region of the AgBiSe2-based phase has the largest extent along the AgAsSe2-AgBiSe2 join: 40 mol % (650 K) for the high-temperature form of AgBiSe2 and 20 mol % (300 K) for its low-temperature form.

Progress in lead-based ferroelectric and antiferroelectric single crystals: composition modification, crystal growth and properties

Ferroelectric and antiferroelectric materials, with complex perovskite structures, have experienced wide interest due to their peculiar structure and properties. In this highlight, recent advances of these two types of materials are reviewed, with particular emphasis on piezoelectrics/ferroelectric and antiferroelectric single crystals, owing to their ultra-high electric properties for practical application. Relaxor ferroelectric single crystals, represented by Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) at compositions near the morphotropic phase boundary (MPB), possess a high piezoelectric constant d33 (>2000 pC N−1) and electromechanical coupling factors k33 (90–92%). However, a low ferroelectric phase transition temperature Tr-t, far below the Curie temperature Tc restricts its further application in a broad temperature range. Some work on the design of a new pseudo-ternary system of Pb(Mg1/3Nb2/3)O3–PbZrO3–PbTiO3 (PMN-PZ-PT) and Pb(Mg1/3Nb2/3)O3–Pb(Fe1/2Nb1/2)O3–PbTiO3 (PMN-PFN-PT) have been demonstrated with emphasis on the composition modification and crystal growth. Moreover, for relaxor antiferroelectrics represented by (Pb,La)(Zr,Sn,Ti)O3 (PLZST) it is very difficult to grow bulk and high quality single crystals because of its incongruent melting. Our recent investigations on the flux growth of PLZST single crystals, especially the flux selection, compositions optimization, and defect analysis of as-grown single crystals are also described in this highlight.

TEMPERATURE-INDEPENDENT DIELECTRIC PROPERTIES OF 0.82[0.94Bi0.5Na0.5TiO3–0.06BaTiO3]–0.18K0.5Na0.5NbO3 CERAMICS

In order to explore the high temperature stability of ceramic capacitor, we present temperature-independent dielectric properties of 0.82[0.94Bi0.5Na0.5TiO3–0.06BaTiO3]–0.18K0.5Na0.5NbO3 (BNT–BT–18KNN) ceramics. For different sintered temperature and annealing treatment, the pseudoternary system showed a εr of 2265 at 1 kHz at 35°C with a normalized permittivity ε/ε35°C varying less than ±15% from 11°C to 382°C. This pure perovskite phase with slimmer and heat proof P–E loops possessed energy density of 0.616 J/cm3 with a tolerance of about ±3% in a temperature interval ranging from 20°C to 120°C, which is higher and more temperature stable than most ceramic capacitors, such as PLZST and 0.89BNT–0.06BT–0.05KNN. This relaxor ferroelectric (at room temperature) with parabolic bipolar strain–electric (S(E)) curve showed a quite low temperature dependence of positive strain with less than ±6.5% tolerance from the average value of 0.091% between 20°C and 120°C, which is also more temperature stable than the same composition Zhang et al. reported. These merits demonstrate that the newly produced BNT–BT–18KNN ceramics should be a promising candidate for the development of high-temperature capacitor and actuator materials.

A combinatorial approach to microstructure and thermopower of bulk thermoelectric materials: the pseudo-ternary PbTe–Ag2Te–Sb2Te3 system

The microstructures and Seebeck coefficients of thermoelectric alloys in the pseudo-ternary PbTe–Ag2Te–Sb2Te3 system were examined using samples that were compositionally graded by unidirectional solidification by the Bridgman method and diffusion couples. At compositions near the middle of the pseudo-binary PbTe–AgSbTe2 line, a compositionally modulated microstructure has been found. From diffusion couple experiments, it is found that the PbTe–AgSbTe2 system exhibits a miscibility gap at low temperatures while it forms a complete solid solution at high temperatures; the critical temperature is between 400 °C and 450 °C. The modulated microstructure originates from the decomposition of the high-temperature solid solution during cooling. Scanning Seebeck coefficient measurement on these samples covers a wide compositional space of the pseudo-ternary system. The Seebeck coefficient transitions from positive values at AgSbTe2-rich compositions to negative values at PbTe-rich compositions on the pseudo-binary PbTe–AgSbTe2 line. Composition-graded samples prepared by the Bridgman method are thus useful to investigate thermoelectric materials in multi-component systems.

Gel Formulation Containing Mixed Surfactant and Lipids Associating with Carboplatin

The interaction of amphiphilic molecules such as lipids and surfactants with the hydrophilic drug carboplatin was investigated to identify suitable self-assembling components for a potential gel-based delivery formulation. (1) H-NMR Studies in sodium bis(2-ethylhexyl) sulfosuccinate (aerosol-OT, AOT)-based reverse micelles show that carboplatin associates and at least partially penetrates the surfactant interface. Langmuir monolayers formed by dipalmitoyl(phosphatidyl)choline are penetrated by carboplatin. Carboplatin was found to also penetrate the more rigid monolayers containing cholesterol. A combined mixed surfactant gel formulation containing carboplatin and cholesterol for lymphatic tissue targeting was investigated for the intracavitary treatment of cancer. This formulation consists of a blend of the surfactants lecithin and AOT (1 : 3 ratio), an oil phase of isopropyl myristate, and an aqueous component. The phases of the system were defined within a pseudo-ternary phase diagram. At low oil content, this formulation produces a gel-like system over a wide range of H(2) O content. The carboplatin release from the formulation displays a prolonged discharge with a rate three to five times slower than that of the control. Rheological properties of the formulation exhibit pseudoplastic behavior. Microemulsion and Langmuir monolayer studies support the interactions between carboplatin and amphiphilic components used in this formulation. To target delivery of carboplatin, two formulations containing cholesterol were characterized. These two formulations with cholesterol showed that, although cholesterol does little to alter the phases in the pseudo-ternary system or to increase the initial release of the drug, it contributes significantly to the structure of the formulation under physiological temperature, as well as increases the rate of steady-state discharge of carboplatin.

Liquid–liquid extraction of toluene from n-heptane using binary mixtures of N-butylpyridinium tetrafluoroborate and N-butylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquids

Liquid–liquid extraction of toluene from heptane using binary mixtures of the ionic liquids N-butylpyridinium bis(trifluoromethylsulfonyl)imide ([bpy][Tf 2N]) and N-butylpyridinium tetrafluoroborate ([bpy][BF 4]) have been investigated at 313.2 K and atmospheric pressure. On the basis of the experimental liquid–liquid equilibrium data for the pseudoternary system n-heptane + toluene + mixed ionic liquids, the values of the distribution ratio and selectivity were calculated and compared to those for the pure ionic liquids, for sulfolane, and those predicted by an ideal mixing rule. The results showed that the use of binary mixture of {[bpy][BF 4] + [bpy][Tf 2N]} at a mole solvent composition of 0.7 for [bpy][BF 4] improves both the distribution ratio of toluene and the selectivity with respect to those of sulfolane. Thus, this mixed ionic liquid could be considered an environmentally benign alternative solvent for the aromatic extraction process.

Stimulation de la consolidation osseuse (adulte et enfant) : BMP, courant électrique, ultrasons

Sulfide chalcopyrites Cu(In,Ga)S2 (CIGS) have been proposed as top cell for tandem solar devices with silicon as bottom cell. In that context, the knowledge of the Cu2S-In2S3-Ga2S3 pseudo-ternary system is of prime importance. This study presents an overall investigation of this system on the basis of a chemical crystallographic approach on bulk materials. Particular attention was paid on the copper-poor side of the so-called stoichiometric CuInS2-CuGaS2 line. Based on our investigations, it turns out that the sulfide CIGS system is much more structurally complex than the selenide Cu(In,Ga)Se2 one (CIGSe). Especially, the adaptability of the chalcopyrite structure toward Cu deficiency is significantly lower for the sulfides than for the selenide counterparts. Correlatively, a large 2-phase domain exists between the CuInS2-CuGaS2 line and the very copper-poor region (Cu(In,Ga)3S5 and Cu(In,Ga)5S8). Additionally, the crystal structures of these very copper-poor compounds contain [InS6] octahedra and then are totally different than the chalcopyrite structure. These features could explain why CIGS-based-solar cells are, up to now, less efficient than the CIGSe ones.

VOCs removal from dilute vapour streams by adsorption onto activated carbon

Methyl tert-butyl ether (MTBE) is the basic oxygenated motor fuel additive in Europe and is a volatile organic compound (VOC). Many studies have been devoted to identify the sources of this polluting compound in the environment, with special concern to shallow groundwater contamination.In this work, original experimental data from the adsorption of vapours mixtures of MTBE, cyclohexane and air onto commercial activated carbon are reported. Equilibrium adsorption data for MTBE+air and cyclohexane+air systems have been obtained from breakthrough curves and have been correlated by means of the Langmuir isotherm. Furthermore, the pseudoternary system MTBE+cyclohexane+air has been studied and the experimental competitive equilibrium data have been successfully compared with those obtained from theory of adsorption for an ideal solution.The results showed that MTBE adsorption capacity of activated carbon is strongly reduced in the presence of cyclohexane. Information on the kinetics of the adsorption operation are also reported. In particular, MTBE showed a maximum excess concentration caused by the displacement of adsorbed MTBE by cyclohexane.

Studies on the Thermodynamic and the Miscibility Gap of the Cu<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> Pseudo-Ternary System

Cu2O-Al2O3-SiO2 ternary system of given compositions can be used as a kind of thermal shock resistance sealing materials for electronic devices. So far, little systematic work was reported on the phase behavior and phase equilibrium at a high temperature, except the isothermal section of a CuO-Al2O3–SiO2 ternary system at 950 and 1150°C. We have investigated the thermodynamic behavior and the microstructure of the compositions in the miscibility gap of the Cu2O-Al2O3-SiO2 pseudo-ternary system on the basis of the reported isothermal section of this system at 1150°C based on the analyzing of the differential scanning calorimeter and the observing of the scanning electronic microscope. The eutectic point of the Cu2O-Al2O3-SiO2 pseudo-ternary system was determined by the thermal analysis. Then, the changing rule of the microstructures with different compositions was investigated. The results indicated that large differences existed among the different compositions in the miscibility gap of Cu2O-Al2O3-SiO2 ternary system.

Application of High Temperature Quantitative X-Ray Powder Diffraction on Determination of Ternary System

This paper has put forward a high-temperature quantitative X-ray powder diffraction analysis method for the determination of an isothermal section of a ternary system in comparison with a conventional method. In a three-phase region of the isothermal section at 1150 °C of Cu2O(CuO)-Al2O3-SiO2 pseudo-ternary system, the compositions of the solid phase points of three system points are determined according to the quantitative analysis of the crystalline phases in the samples carried out by Rietveld method. Then the liquid phase point of the three-phase region is determined according to the crosspoints of the tie lines of every pair of system point and solid phase point. The precisions of the analytical results have reached to be 0.1 ~ 5.0 %. By comparison, a good result is obtained for the determination of the liquid phase point of the three-phase region in the isothermal section at 1150 °C when the analytical results of high-temperature RQA analysis are used in determination of the isothermal section of the pseudo-ternary system.

A novel concept for the preparation of alloy nanowires

AbstractA novel concept for the preparation of alloy nanowires has been developed. By combining two pseudobinary eutectic systems NiAl–W and NiAl–Cr with a completely miscible system Cr–W, a pseudoternary system was created in which there is large two‐phase field between NiAl and W(Cr) solid solutions, separated by a eutectic trough. This enables the fabrication of nanowires with compositions from pure W to pure Cr allowing a free change of the ratio. The directional solidification in the pseudoternary system has been carried out. For the first time alloy nanowires in the W–Cr system have been reported. In addition, nanowires of pure W and Cr were fabricated as well. Moreover, an electrochemical procedure for the release of nanowires from the matrix has been established. magnified image High yield of W–Cr alloy nanowires with equiatomic composition.

Phase behaviour of a mixed ionic/nonionic surfactant system used to prepare stable oil-in-water paraffin emulsions

The phase behaviour of a mixed surfactant system was studied in order to determine the role of surfactants in the stability of paraffin emulsions. The study was carried out by means of phase diagrams. The different phases were characterized by Small and Wide Angle X-ray Scattering (SAXS/WAXS), Polarized Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC). The results showed that the nonionic and ionic surfactants, used in industry for paraffin emulsions, possess high Krafft points and both form lamellar interdigitated gel structures. Phase behaviour of the water/mixed surfactant pseudoternary system indicated that, lamellar liquid crystalline aggregates are formed at very diluted surfactant concentrations (≈98 wt% water), even at low nonionic/ionic surfactant weight ratio (10/90). Therefore, lamellar liquid crystalline aggregates coexist with excess water, at the surfactant compositions used to obtain stable paraffin emulsions (2–4 wt% of mixed surfactant). Theses aggregates could contribute to the high kinetic stability of the paraffin emulsions.

Liquid––liquid phase equilibrium in saturated hydrocarbon – arenes C6-C8 – mixed extractant systems

Experimental data are reported on liquid–liquid equilibrium in saturated hydrocarbon – C6-C8 arene – mixed extractant (triethylene glycol–sulfolane–water) pseudoternary systems of varying composition at 50°C. It was shown that increasing the sulfolane:TEG ratio from 21.7:78.3 to 60:40 changes the character of the bimodal curve in the phase diagram from the open to the closed type. As a result, for the same ratio of extractant and feedstock, all of the extraction indices – the degree of extraction, distribution coefficients, and arene content in the extractant – improved and the hydrocarbon fractionation factors increased.

Glass formation in the Sb2O3–CdCl2–SrCl2 ternary system

Vitreous systems based on antimony oxide Sb2O3 have been investigated. The limits for glass formation are reported in the Sb2O3–CdCl2–SrCl2 ternary system, and in the Sb2O3–SrCl2–(0.5CdCl2+0.5ZnCl2) pseudo ternary system. Amorphous state is confirmed by XRD patterns. Thermal measurements implemented by differential scanning calorimetry show that Tg is above 300°C. As a general trend, Tg increases with chloride content. These glasses have an extended transmission in the mid-infrared spectrum with a refractive index larger than 2. The influence of the CdCl2/Sb2O3 substitution on the physical properties has been studied in the (90−x)Sb2O3–xCdCl2–10SrCl2 system: thermal expansion, Vickers microhardness, Young and bulk modulus decrease as cadmium concentration increases. An inverse dependence is observed for shear modulus. This behaviour is discussed in relation to structural hypothesis.

Preparation and third-order optical nonlinearity of glass ceramics based on GeS 2–Ga 2S 3–CsCl pseudo-ternary system

Chalcohalide glass-ceramics based on GeS 2–Ga 2S 3–CsCl pseudo-ternary system were prepared by heat treatment method. X-ray diffraction and scanning electron microscope studies confirmed the formations of Ga 2S 3 and GeS 2 phase grains with sizes of 2–5 and 80 nm, respectively. Z-scan technology was employed to investigate the third-order nonlinear optical characteristics of both precursor glass and its glass ceramics at 800 nm. The results show that nonlinear refractive index n 2 as well as nonlinear absorption coefficient β increase after heat treatment, which is due to quantum effects, and the largest n 2 of the glass ceramics is 4.3 × 10 − 11 esu which is 4 times larger than that of the host.

Modeling the phase behavior of heavy oil and solvent mixtures

The capability of conventional oil characterization methods combined with a cubic equation of state to predict the phase behavior of heavy oil and solvent mixtures was evaluated using data for mixtures of bitumen, propane, and carbon dioxide. The bitumen was characterized based on simulated distillation (SimDist) data extrapolated using six different approaches. Each curve was divided into temperature-based pseudo-components with physical and critical properties determined from established correlations. Four sets of correlations were evaluated and modifications were proposed to extend the Twu critical property correlations to pseudo-components with normal boiling points higher than 730 °C. The phase behavior of the oil was modeled using the advanced Peng–Robinson equation of state and the interaction parameters were optimized to fit experimental saturation pressures of pseudo-binary mixtures of each solvent with the bitumen. The model was then used to predict saturation pressures and liquid–liquid phase boundaries of pseudo-ternary systems as well as asphaltene precipitation from n-heptane diluted bitumen. The best characterization of the bitumen was a Gaussian distribution of boiling points from the SimDist for the maltenes plus a Gamma distribution of the molecular weight of the asphaltene fraction. Characterizations with boiling points above 800 °C failed. Both the Lee–Kesler and Twu property correlations could be applied to heavy fractions but the Lee–Kesler correlations provided a better fit to the data. The model correctly predicted the saturation pressures and liquid–liquid boundaries for pseudo-ternary mixtures of propane–CO 2–bitumen with an AARD of less than 6%. However, the model could not correctly predict asphaltene precipitation yields from bitumen at high dilution with n-heptane.