Abstract  PURPOSE: A genetic neural network (GNN) model was developed to predict the phase behavior of microemulsion (ME), lamellar liquid crystal (LC), and coarse emulsion forming systems (W/O EM and O/W EM) depending on the content of separate components in the system and cosurfactant nature.

METHOD: Eight pseudoternary phase triangles, containing ethyl oleate as the oil component and a mixture of two nonionic surfactants and n-alcohol or 1,2-alkanediol as a cosurfactant, were constructed and used for training, testing, and validation purposes. A total of 21 molecular descriptors were calculated for each cosurfactant. A genetic algorithm was used to select important molecular descriptors, and a supervised artificial neural network with two hidden layers was used to correlate selected descriptors and the weight ratio of components in the system with the observed phase behavior.

RESULTS: The results proved the dominant role of the chemical composition, hydrophile-lipophile balance, length of hydrocarbon chain, molecular volume, and hydrocarbon volume of cosurfactant. The best GNN model, with 14 inputs and two hidden layers with 14 and 9 neurons, predicted the phase behavior for a new set of cosurfactants with 82.2% accuracy for ME, 87.5% for LC, 83.3% for the O/W EM, and 91.5% for the W/O EM region.

CONCLUSIONS: This type of methodology can be applied in the evaluation of the cosurfactants for pharmaceutical formulations to minimize experimental effort.

Abstract    Acne is the most common cutaneous disorder of multifactorial origin with a prevalence of 70-85% in adolescents. The majority of the acne sufferers exhibit mild to moderate acne initially, which progresses to the severe form in certain cases. Topical therapy is employed as first-line treatment in mild acne, whereas for moderate and severe acne, systemic therapy is required in addition to topical therapy. Currently, several topical agents are available that affect at least one of the main pathogenetic factors responsible for the development of acne. Although topical therapy has an important position in acne treatment, side effects associated with various topical antiacne agents and the undesirable physicochemical characteristics of certain important agents like tretinoin and benzoyl peroxide affect their utility and patient compliance. Novel drug delivery strategies can play a pivotal role in improving the topical delivery of antiacne agents by enhancing their dermal localization with a concomitant reduction in their side effects. The current review emphasizes the potential of various novel drug delivery strategies like liposomes, niosomes, aspasomes, microsponges, microemulsions, hydrogels and solid lipid nanoparticles in optimizing and enhancing the topical delivery of antiacne agents. Copyright © 2006 S. Karger AG, Basel   Acne is the most common cutaneous disorder of multifactorial origin with a prevalence of 70-85% in adolescents. The majority of the acne sufferers exhibit mild to moderate acne initially, which progresses to the severe form in certain cases. Topical therapy is employed as first-line treatment in mild acne, whereas for moderate and severe acne, systemic therapy is required in addition to topical therapy. Currently, several topical agents are available that affect at least one of the main pathogenetic factors responsible for the development of acne. Although topical therapy has an important position in acne treatment, side effects associated with various topical antiacne agents and the undesirable physicochemical characteristics of certain important agents like tretinoin and benzoyl peroxide affect their utility and patient compliance. Novel drug delivery strategies can play a pivotal role in improving the topical delivery of antiacne agents by enhancing their dermal localization with a concomitant reduction in their side effects. The current review emphasizes the potential of various novel drug delivery strategies like liposomes, niosomes, aspasomes, microsponges, microemulsions, hydrogels and solid lipid nanoparticles in optimizing and enhancing the topical delivery of antiacne agents.

Abstract    Nail art (creation and decoration of artificial nails) is a growing fashion trend. Proportionally to its popularity, the number of allergic reactions to the materials used has recently increased. We report the case of a nail art operator who developed occupational allergy to acrylates, manifested with the unusual simultaneous presence of asthma and dermatitis. Cutaneous lesions only affected areas not covered by individual protection devices or clothes, even if such areas were not in direct contact with acrylates, suggesting airborne allergic contact dermatitis. While respiratory problems were solved with the correct use of a mask at the workplace, facial dermatitis proved impossible to avoid or control and, for this reason, the patient had to change her work.

Abstract    Microemulsions are thermodynamically stable colloidal dispersions of water and oil stabilized by a surfactant and, in many cases, also a cosurfactant. In the pharmaceutical field, microemulsions have been used as drug carriers for percutaneous, ocular, oral and parenteral administration. This review discusses some of the applications of microemulsions specifically for topical and transdermal applications. Microemulsion nomenclature and composition, with particular emphasis on choice of surfactant and cosurfactant, is discussed. Methods used to characterize microemulsions are reviewed. Microemulsion formulations for dermal and transdermal delivery of pharmaceutical agents with particular emphasis on anti-inflammatory and anaesthetic agents are critically evaluated. Finally, the issues which warrant further investigation by researchers in order to realize the full potential of the technology are discussed. Copyright © 2008 S. Karger AG, Basel [PUBLICATION ABSTRACT]   Microemulsions are thermodynamically stable colloidal dispersions of water and oil stabilized by a surfactant and, in many cases, also a cosurfactant. In the pharmaceutical field, microemulsions have been used as drug carriers for percutaneous, ocular, oral and parenteral administration. This review discusses some of the applications of microemulsions specifically for topical and transdermal applications. Microemulsion nomenclature and composition, with particular emphasis on choice of surfactant and cosurfactant, is discussed. Methods used to characterize microemulsions are reviewed. Microemulsion formulations for dermal and transdermal delivery of pharmaceutical agents with particular emphasis on anti-inflammatory and anaesthetic agents are critically evaluated. Finally, the issues which warrant further investigation by researchers in order to realize the full potential of the technology are discussed.

Abstract  This article describes the formation of microemulsions by utilising fatty acid methyl esters (FAME) and a surfactant or mixed surfactant system derived from palm oil-based oleochemicals. The effects of 1,2 hexanediol as a conventional non-toxic co-surfactant were investigated by observing the ternary phase behaviour of palm oil-based microemulsions for three types of surfactant systems, i.e., fatty alcohol ethoxylates 7EO (FAE 7); mixed surfactants FAE 7 and fatty alcohol ethoxylates 2EO (FAE 2) in a 75:25 ratio; and mixed surfactants FAE 7, FAE 2 and methyl ester sulphonate (MES) in a 60:20:20 ratio. The microemulsion (mu E) solutions formed were characterised by conductivity, viscosity and droplet-size measurements. The cleaning performance of selected palm oil-based microemulsions as all-purpose spray liquid cleaners for hard surfaces is also reported.

Abstract  Experimental data are presented for liquid-liquid equilibria of mixtures of the room-temperature ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([C2MIM][NTf2]) with the three alcohols propan-1-ol, butan-1-ol, and pentan-1-ol and for the 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([C4MIM] [NTf2]) with cyclohexanol and 1,2-hexanediol in the temperature range of 275 K to 345 K at ambient pressure. The synthetic method has been used. Cloud points at a given composition were observed by varying the temperature and using light scattering to detect the phase splitting. In addition, the influence of small amounts of water on the demixing temperatures of binary mixtures of [C2MIM][NTf2] and propan-1-ol, butan-1-ol, and pentan-1-ol was investigated.

Abstract  We present small-angle neutron scattered intensity measurements in heavy water binary solutions of some short-chain glycols (diols and triols) at room temperature. The spectra were analyzed in terms of a model which takes into account the simultaneous presence of spherical aggregates and concentration fluctuations. We found that hydrated micelle-like aggregates are present in some bi- and trivalent alcohols (e.g., 1,2-hexanediol, 1,2,3-octanetriol) and are absent in others (e.g., 2,5-hexanediol, 1,2,3-hexanetriol). Results are discussed in terms of location of the polar hydroxyl groups in the short hydrocarbon chain. The size and aggregation numbers of the found aggregates are compared with those of other short-chain nonionic surfactants.

Abstract  N,N-Dimethyldodecylamine N-oxide (DDAO), PVP and PVA capped supported AuPd bimetallic nanoparticles (NPs) were prepared, and their catalytic activities were evaluated for the oxidation of 1,6-hexanediol (HDO) to 6-hydroxycaproic acid (HCA) using H2O2 in basic aqueous solution. Among three catalysts, DDAO capped AuPd bimetallic NPs catalysts exhibited superior selectivity for HCA formation than PVP and PVA capped catalysts. To explain the difference in the catalytic behavior, the catalysts were characterized thoroughly. XRD, TEM and STEM-HAADF-EDS studies were employed to identify the structure and morphology of capped AuPd-NPs, respectively. The chemical and electronic states were elucidated using XPS and XAS methods. The characterization data revealed that the capping agent significantly influences the electron density on metals and extent of alloying between Au and Pd metals. It was revealed that DDAO-capped catalyst induces appropriate negatively charged Au species with a few numbers of Au-Pd interfaces for the highly selective formation of HCA via HDO oxidation in basic aqueous media. Furthermore, other aliphatic diols, 1,7-heptanediol, 1,8-octanediol and 1,2-hexanediol, were also selectively oxidized on AuPd-DDAO catalysts toward the corresponding omega-hydroxycarboxylic acids in high yields. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  Hydrogenolysis of alcohols was carried out using n-heptane solvent and Ir-ReOx/SiO2 catalyst, which has been known to be active in water solvent. Hydrogenolysis of trans-1,2-cyclohexanediol proceeded more smoothly in n-heptane than in water. The maximum yield of cyclohexanol was 74%, and at longer reaction time cyclohexane was selectively formed (>80% yield). Stronger adsorption of substrate on catalyst surface in n-heptane than in water is one of factors in obtaining the good yields. Alkane solvent was also advantageous to water solvent in hydrogenolysis of mono-alcohols. The reaction route via acid-catalyzed dehydration and subsequent hydrogenation is enhanced in alkane solvent. On the other hand, the "direct" hydrogenolysis driven by the hydride-like species is suppressed in alkane solvent, leading lower activity in n-heptane for hydrogenolysis of tetrahydrofurfuryl alcohol or 1,2-hexanediol, which smoothly react over Ir-ReOx/SiO2 catalyst in water. (C) 2013 Elsevier B.V. All rights reserved.

Abstract  The extraction of 1,2-hexanediol from aqueous solution by dihydroxyphenylborane was studied in the absence and presence of tri-n-octylmethylammonium chloride (TOMAC) to establish a process of microbial kinetic resolution of epoxides. Dihydroxyphenylborane alone could extract 1,2-hexanediol except at high pH. Addition of TOMAC to the extractant solution significantly improved the distribution of 1,2-hexanediol to the organic solution at high pH. The extraction mechanisms of 1,2-hexanediol in these systems were elucidated and extraction equilibrium constants were determined.

Abstract  The dielectric spectra of binary liquid mixtures of the following alcohols with N,N-dimethylformamide (DMFA) have been measured between 5 MHz and 72 GHz at 20 degrees C:1-Hexanol, 1,2-hexanediol and 1,4-butanediol. The analysis of the spectra, which is particularly aimed at information on hetero-association, gives evidence for the formation of mixed aggregations, indicated by a minimum in the 'free' DMFA relaxation contribution at a mixture ratio of about 1:1 for hexanol/DMFA and about 1:2 in case of the dihydric alcohol/DMFA systems.

Abstract  Aqueous solutions of 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol and 1,6-hexanediol have been studied by small-angle neutron scattering over a wide range of concentrations and temperatures. The structure of the solutions on the mesoscopic length scale, corresponding to the intermolecular distances, was analysed with the help of the Kirkwood-Buff formalism. 1,2-Hexanediol solutions exhibited a strong attractive diol-diol interaction, a weak diol-diol attraction was found for 1,6-hexanediol and 1,2-pentanediol, and an extremely weak diol-diol attraction was found in 1,5-pentanediol solutions. The general tendencies are the following: aggregation is stronger as the length of the hydrophobic hydrocarbon chain increases and the 1,2-diols exhibit much stronger attraction then the 1,omega-diols. The temperature dependence of the aggregation is weak for the 1,2-diols but strong for the 1,omega-diols, indicating in the latter case the hydrophobic character of the interaction.

Abstract  The purpose of the present study was to determinate the significance of ion pairing on the topical permeation of retinoic acid (R.A) using microemulsions as delivery vehicles. Phenylalanine methyl ester, phenylalanine ethylester, histidine methyl ester, tryptophan methyl ester and valine methyl ester were used as counter ions. Results of diffusion studies through polydimethylsiloxane membrane (PDMS) indicate that retinoic acid permeation from ethanol-pH 6.4 buffer mixture significantly increased in the presence of counter ions. A linear relationship was found between apparent partition coefficients and permeation coefficients. The highest values were with valine methyl ester and phenylalanine ethyl ester. In order to develop alternative formulations for topical administration of R.A, microemulsions were evaluated as delivery vehicles. Oil-in-water (O/W) and water-in-oil (W/O) microemulsion formulations were prepared using water, isopropyl myristate, lecithin, caprylyl-capryl glucoside and ethanol or 1,2 hexanediol. Experiments with PDMS membranes showed decreasing permeabilities of R.A from microemulsions in the presence of counter ions. This was related to the increased lipophilicity and different vehicle membrane affinity of the ion pairs The ability of the systems to deliver R.A through the skin was evaluated in vitro using pig-skin. R.A permeabilities were much lower with microemulsions than with solution, while a large increase in R.A skin deposition was observed only from O/W microemulsions in the presence of counter ions. The depth of skin accumulation was below 100 mum after 24 h application. The results suggest that O/W microemulsions containing a counter ion can be used to optimise drug targeting without a concomitant increase in systemic absorption. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract  Excess molar volumes V-m(E) and partial molar volumes (V) over bar (2) have been determined from density measurements for dilute aqueous solution of 1.2-hexanediol, 1.5-hexanediol, 1,6-hexanediol, and 2,5-hexanediol at (283.15, 288.15, 293.15, 298.15, 303.15, and 308.15) K as a function of composition. The infinite dilution partial molar volumes (V) over bar (infinity)(2) of alcohols in aqueous solution are evaluated through extrapolation. Interactions of the different solutes with water are discussed in terms of the effect of the position of the hydroxyl groups in the hexanediol molecule. The limiting slope of the partial molar volumes is interpreted in terms of alkanediol hydration. (c) 2007 Elsevier Ltd. All rights reserved.

Abstract  Blends of immiscible polymers are often stabilized by block copolymers which can form non-aqueous micelles and microemulsions in the liquid polymers. The phase diagrams, apparent volumes and apparent heat capacities of model non-aqueous binary and ternary systems were studied in order to investigate the conditions under which such self-assembly systems could form. 1,2-Hexanediol, which can cosolubilize hexane and ethyleneglycol forms inverse micelles in hexane and weak microaggregates in ethyleneglycol. Genapol X-060, a commercial alcoholic surfactant containing on the average an aliphatic chain of 13 carbons and 6 oxyethylenes (C13E6), forms microaggregates in poly(ethyleneglycol) 400. Them self-assembly systems are strengthen in the presence of a third component which has an affinity for the inner phase.

Abstract  Epoxide hydrolase catalysed resolution of aliphatic terminal epoxides has been demonstrated for the hydrolysis of a homologous range of unbranched 1,2-epoxyalkanes by the yeast Rhodotorula glutinis. Both enantioselectivity and reaction rate were strongly influenced by the chain length of the epoxide used. Enantioselectivity showed an optimum in the hydrolysis of 1,2-epoxyhexane (E=84), Resolution of (+/-)-1,2-epoxyhexane resulted in (S)-1,2-epoxyhexane (e.e.>98%, yield=48%) and (R)-1,2-hexanediol (e.e.=83%, yield=47%). (C) 1998 Elsevier Science Ltd. All rights reserved.

Abstract  Continuing our research work on ionic liquids new results for liquid-liquid equilibria (LLE) of binary mixtures of the ionic liquids 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4MIM][NTf2]) or 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6MIM][NTf2]) and hexan-1-ol are presented. For the mixture [C4MIM][NTf2]+1,2-hexanediol the interfacial tension gamma between the two liquid phases being in equilibrium has been measured as a function of temperature using a pendant-drop tensiometer.

Additionally, for systems [C4MIM][NTf2]+alcohol the influence of impurities like 1-methylimidazole and water on the demixing temperature was investigated. (C) 2006 Elsevier B.V. All rights reserved.