Abstract  Phase diagrams of the ternary system water/poly(12-hydroxystearic acid)-poly(ethylene oxide)-poly(12-hydroxystearic acid) (PHS-PEO-PHS)/isopropyl myristate and the quaternary system water/PHS-PEO-PHS/1,2-alkanediol/isopropyl myristate were investigated at 25 degreesC. The alkanediols tested in this work are 1,2-hexanediol and 1,2-octanediol. The different phases formed have been examined by optical (phase contrast and polarizing) microscopy. The nature of the continuous media has been determined by conductivity. Particular attention was paid to the L-2 (water-in-oil micoremulsion). The amount of water solubilized in this region increases as the surfactant concentration increases. The minimum. content of polymeric surfactant and cosurfactant for maximum water solubilization is about 37%. The present investigation has also shown the relation between the oil polarity and the maximum water content that can be solubilized in microemulsions.

Abstract  Microemulsions formed with water, isopropyl myristate, poly (12-hydroxystearic acid)-poly(ethylene oxide)-poly( 12-hydroxystearic acid) polymeric surfactant and alkanediol have been investigated using small-angle X-ray scattering (SAXS), conductivity and static light scattering measurements at 25 degrees C. The SAXS spectra exhibit two different behaviors depending on which compositions are kept constant. If surfactant and oil concentrations are constant, the peak position remains constant as the volume fraction increases. On the other hand, if surfactant and cosurfactant concentrations are constant, the peak position shifts to lower cl values as the volume fraction increases. From a certain volume fraction, the peak position stops shifting and remains constant as the volume fraction continues increasing. It is interesting to note that the constant peak position is the same for both behaviors. The microemulsion structure is difficult to ascertain solely on the basis of the X-ray spectra but, from the conductivity and static light scattering measurements, we can conclude that the structure probably changes from disconnected water domains to some type of connected water domains. From the SAXS measurements self-association of 1,2-hexanediol is observed.

Abstract  Bis(methoxy oxalic)-1,2-haxenediester and bis(ethoxy oxalic)-1,2-haxenediester were synthesized by modifying the end groups of 1,2-hexanediol with methyl oxalyl chloride and ethyl oxalyl monochloride. The solubilities of all three compounds in supercritical carbon dioxide were determined at different conditions of pressures (8.8 to 18.8) MPa and temperatures (313, 333, and 353) K. Then, the solubility data were correlated with the Bartle model and the Chrastil model. The average absolute relative deviation (AARD) for the Bartle model was in the range of (3.89 to 25.46)% which is within a good approximation. The Chrastil model also showed satisfactory agreement and the AARD was in the range of (3.70 to 16.92)%. Furthermore, the partial molar volumes of those compounds were estimated following the theory developed by Kumar and Johnston. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract  Molar enthalpies of vaporization of 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. The measured data sets were successfully checked for internal consistency. A large number of the primary experimental results on temperature dependences of vapor pressures have been collected from the literature and have been treated uniform in order to derive vaporization enthalpies at the reference temperature 298.15 K. This collection together with the experimental results reported here has helped to resolve some contradictions which have been met in the available literature. (C) 2004 Elsevier B.V. All rights reserved.

Abstract  The by-products of olive oil production can be used as sources of microbial strains. Penicillium sp., Aspergillus terreus, Penicillium aurantiogriseum, Aspergillus tubingensis and Aspergillus niger were selected on the basis of their epoxide-hydrolyzing activity towards racemic rac-glycidyl phenyl ether. We studied the effect on enzymatic activity of adding styrene oxide to the growth medium. It induced the biosynthesis of epoxide hydrolases and reduced cell growth. The resolution capacity of the five fungi was tested on rac-glycidyl phenyl ether, rac-benzyl glycidyl ether, rac-1,2-epoxyhexane and rac-1,2-epoxyoctane. The resolution of rac-glycidyl phenyl ether by A. niger, rac-benzyl glycidyl ether by P. aurantiogriseum and A. terreus, rac-1,2-epoxyhexane by A. tubingensis and rac-1,2-epoxyoctane by A. terreus provided (S)-3-phenoxy-1,2-propanediol (45.1% yield, 51.4% ee), (R)-3-benzyloxy-1,2-propanediol (40.8% yield, 43.3% ee), (S)-3-benzyloxy1,2-propanediol (45.4% yield, 45.6% ee), (R)-1,2-hexanediol (70.4% yield, 24.4% ee) and (R)-1,2-octanediol (21.4% yield, 27.5% ee), respectively. The (R)-enantiopreference of the epoxide hydrolases from P. aurantiogriseum is unprecedented.

Abstract  The reactivity profiles of glucose (Glc), fructose (Fru), and possible intermediate compounds treated with Pt nanoparticles protected by polyethyleneimine (Pt-PEI) were studied at 403-543 K in subcritical water under a hydrogen atmosphere of 5 MPa. Isomerization between Glc and Fru proceeded at the temperature as low as 403 K and was accelerated by Pt-PEI and H(2). The rate of isomerization from Glc to Fru in the presence of Pt-PEI and H(2) was approximately three times greater than the rate of the reverse reaction. Yields of sorbitol and mannitol were maximized at 443 K and decreased at higher temperatures. Under reaction temperatures of 483-543 K, Glc produced mainly 1,2-propanediol, 1,2-hexanediol, and ethylene glycol, while Fru yielded 1,2-propanediol, 1,2-hexanediol, and glycerol. The molar ratios of C3 compounds to the sum of C2 and C4 compounds in this temperature range were approximately 2:1-1.5:1 in the former and 3:1-4:1 for Fru, indicating that C3 compounds can be preferentially produced from Fru. The reactivity profiles of sorbitol, mannitol, and 1,2-hexanediol were examined in separated experiments at 483-543 K, and it was found that these linear C6 compounds were not converted to the previously mentioned C2-C4 diols and triols. This suggests that there is little possibility for Glc or Fru to form C2-C4 compounds via sorbitol, mannitol, or 1,2-hexanediol on the Pt catalyst, and it is likely that retro-aldol reactions of Glc and Fru are the major routes to these molecules. The temperatures necessary to conduct these reactions on Pt were much lower than those without Pt. (C) 2011 Elsevier B. V. All rights reserved.

Abstract  Effects of varying concentrations of 1,2-ethanediol, 1,2-butanediol and 1,2-hexanediol (glycols) on the micellisation and thermodynamic properties of sodium dodecyl sulphate (SDS) were studied at temperature range 288-313K by conductometry method. Critical micelle concentration (CMC) of SDS increased in 1,2-ethanediol but decreased in the longer carbon chain glycols in the order: 1,2-hexanediol<1,2-butanediol

Abstract  An oil-in-water (O/W) microemulsion was prepared by mixing palm-based methyl esters (PME) with water at a 25:75 by weight ratio. The microemulsion was stabilised with C(12-14)fatty alcohol ethoxylates (FAE) with 7 and 2 moles of ethylene oxide (EO), and palm-methyl ester sulphonate (MES) as mixed surfactants, and glycerol-derived co-surfactant (GTBE) and conventional 1,2-hexanediol as the cosurfactants. The mixtures were agitated vigorously and then stored at ambient temperature and 45 degrees C. Phase behaviour of the ternary-phase systems was periodically observed using the polarised light sheets. The ternary phase diagrams were then mapped. The physical characterisations of any stable microemulsions, such as the conductivity and viscosity solutions were also determined. The optimum concentrations of mixed surfactants (MES/ FAE 7/FAE 2) and GTBE to form stable microemulsions were 20% (w/w) and 10% (w/w), respectively. A larger microemulsion region was also obtained for other system consisting of mixed surfactants (FAE 7/ FAE 2) and GTBE with the optimum concentrations of mixed surfactants and co-surfactant for producing full microemulsions were 15% (w/w) and 10% (wlw), respectively. Physical characterisations of the stable microemulsion solutions showed that the conductivity values depended on the content of aqueous solution, while the viscosity values on the physical structures of microemulsion formation.

Abstract  We use a solution-based hot injection method to synthesize stable, phase pure and highly crystalline cubic iron pyrite (FeS2) nanocrystals, with size varying from similar to 70 to 150 nm. We use iron(II) bromide as an iron precursor, elemental sulfur as the sulfur source, trioctylphosphine oxide (TOPO) and 1,2-hexanediol as capping ligands, and oleylamine (OLA) as a non-coordinating solvent during the synthesis. We report on the influence of hydrazine treatment, and of thermal sintering, on the morphological, electronic, optical, and surface chemical properties of FeS2 films. Four point probe and Hall measurements indicate that these iron pyrite films are highly conductive. Although they are unsuitable as an effective photovoltaic light-absorbing layer, they offer clear potential as a conducting contact layer in photovoltaic and other optoelectronic devices.

Abstract  This article reports experiences gathered from systematic studies on the potential of scanning force microscopy to investigate the interface geometry and the wetting behavior of liquid microstructures placed on mica, glass, gold-coated, and uncoated silicon wafers. The liquids investigated are glycerin, polydimethylsiloxane (PDMS), squalane, pentadecane, hexadecane, heptadecane, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,5-pentanediol. The experiments required fast and repetitive scanning of liquid structures. Different types of surface-modified cantilever/tip assemblies were employed, aiming at reducing the interfacial energy associated with uncoated silicon/silicon oxide cantilevers. Severe challenges concerning the stability and the reproducibility of such experiments are reported. Limitations of this method when applied to the free surface of liquid microstructures due to the small but ever-present interaction forces beta een the tip and the sample are also discussed.

Abstract  The aqueous solution properties and the micellar structure of two short-chain nonionic surfactants containing a hydrocarbon tail, 1,2-hexanediol (HD), and a perfluorinated tail, 3,3,4,4,5,5,6,6,6-nonafluoro-1,2-hexanediol(PFHD), have been compared by using various techniques such as pyrene fluorescence spectroscopy, vapor pressure osmometry,'tensiometry, and dye solubilization. The aggregational behavior of both systems in aqueous medium has been evidenced by the polarity decrease of the pyrene microenvironment with increasing surfactant concentration. The binding coefficient of pyrene with the aggregates was calculated by application of the phase-separation model to the pyrene fluorescence results. The aggregation numbers of the HD (N-H) and PFHD (N-PF) micelles have been evaluated by application of the phase-separation and the mass-action law models to the osmotic coefficients measurements. The N-H value (26 +/- 8), which is in good accordance with previous experimental results (30 +/- 10), is higher than N-PF (15 +/- I). Both compounds exhibit surface-active properties with a maximum surface tension lowering of 42 and 57 mN m(-1) for HD and its perfluorinated homologous compound, respectively. Their solubilizing power toward Orange OT was compared. Critical micelle concentrations (CMCs) have been determined in the temperature range 20-50 degrees C (30-50 degrees C for PFHD insoluble below 30 degrees C), and thermodynamic parameters such as standard enthalpy and entropy changes for micellization have been calculated.

Abstract  In this report, we introduce a new micelle modifier useful to alter selectivity in micellar electrokinetic capillary chromatography (MECC). 1,2-Hexanediol acts as a class I organic modifier in that its effects are on the sodium dodecyl sulfate (SDS) micellar rather than the surrounding aqueous phase. This characteristic allows 1,2-hexanediol to improve resolution when applied at concentrations as low as 20 mM (0.25% v/v) by altering the selectivity observed with SDS alone. The effects of 1,2-hexanediol on the critical micelle concentration of SDS, electroosmotic flow, electrophoretic mobility of the SDS micelle, and reproducibility are presented. 1,2-Hexanediol had little impact on the migration time window at concentrations below 100 mM. Changes in selectivity induced by 1,2-hexanediol for a large set of model compounds are presented. Analytes capable of forming hydrogen bonds tend to decrease their interactions with the micellar phase while nonhydrogen bonding analytes increase their interactions. The usefulness of 1,2-hexanediol was demonstrated by examining its effects on the separation of dansylated amino acids. Eighteen of twenty amino acids could be separated with a resolution greater than 1.6 within 1600 s using a combination of 1,2-hexanediol and isopropanol.

Abstract  The structure of iron oxide was controlled by regulating the hydrolytic polymerization of aquo iron complexes with organic polydentate ligands such as diols. Iron oxides were prepared by calcining the precursor polymers obtained from iron nitrate nonahydrate and diols. When the diols were 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol, alpha-Fe2O3 with corundum structure appeared exclusively or as the main crystalline phase, in spite of the amount of diol used and the calcination temperature. In the case of 1,2-decanediol and 1,2-dodecanediol, when five moles of the diols were used to one mole of iron nitrate and the calcination temperatures were below 400 degrees C, gamma-Fe2O3 with spinel structure appeared as the main phase and, when less than five moles of the diols were used, alpha-Fe2O3 appeared exclusively or as the main phase, irrespective of the calcination temperature. This tendency was also observed in thin films. Thus, a transparent magnetic film composed of gamma-Fe2O3 could be prepared by applying a benzene solution of the iron polymer, obtained with 5 equivalents of 1,2-decanediol, on quartz and calcining the gel him at 350 degrees C.