Abstract  Galactitol dehydrogenase (GatDH) from Rhodobacter sphaeroides is a multifunctional enzyme that catalyzes in the presence of oxidized beta-nicotinamide adenine dinucleotide (NAD(+)) the interconversion of various multivalent aliphatic alcohols to the corresponding ketones. The recombinant GatDH was provided with an N-terminal His(6)-tag to which distally up to three cysteine residues were attached. This protein construct maintained nearly full enzymatic activity, and it could be covalently immobilized via thiol bonds onto the surface of a gold electrode. Binding of GatDH onto the gold electrode was verified by SPR measurements, and residual enzyme activity was measured by cyclic voltammetry using 1,2-hexanediol as substrate, the cofactor NAD(+) and the redox mediator CTFM (4-carboxy-2,5,7-trinitrofluorenyliden-malonnitrile) in solute form. The results demonstrate the possibility of a directed functional immobilization of proteins on gold surfaces, which represents a proof-of-concept for the development of reactors for electrochemical synthon preparation using dehydrogenases.

Abstract  In a previous study, a synergistic retardation effect of 1,4-cyclohexanediol and 1,2-hexanediol on percutaneous absorption and penetration of metronidazole (MTZ) was discovered. A complex formation between 1,4-cyclohexanediol and 1,2-hexanediol was proposed to be responsible for the observed effect. The objective of this study was to investigate the necessity of hydroxyl group and the ring structure in 1,4-cyclohexanediol on percutaneous absorption and penetration of MTZ. Eleven formulations were studied in an in vitro porcine skin model using glass vertical Frans Diffusion Cell. 1,4-Cyclohexanediol was changed into 1,4-cyclohexanedicarboxylic acid, trans (and cis)-1,2-cyclohexanediol and 1,6-hexanediol, respectively, to study if H-bonding or ring structure would influence the retardation effect. MTZ was applied at infinite dose (100 mg), which corresponded to 750 μg of MTZ. Based on modifier ratios (MR) calculated by the flux values, the retardation effect on percutaneous absorption and penetration of MTZ was found in the formulations containing 1,4-cyclohexanedicarboxylic acid or cis-1,2-cyclohexanediol (MR values were 0.47 for which only contains 1,4-cyclohexanedicarboxylic acid, 0.74 for the formulation containing both 1,4-cyclohexanedicarboxylic acid and 1,2-hexanediol, and 0.90 for the formulation containing cis-1,2-cyclohexanediol and 1,2-hexanediol, respectively). The results showed that the hydroxyl group and structure of 1,4-cyclohexanediol played a significant role in retardation effects and provided valuable insight on the mechanisms of retardation effect through structure-activity relationships.

Abstract  The ruthenium aqua complexes [Ru(H(2)O)(2)(bipy)(2)](OTf)(2), [cis-Ru(6,6'-Cl(2)-bipy)(2)(OH(2))(2)](OTf)(2), [Ru(H(2)O)(2)(phen)(2)](OTf)(2), [Ru(H(2)O)(3)(2,2':6',2''-terpy)](OTf)(2) and [Ru(H(2)O)(3)(Phterpy)](OTf)(2) (bipy = 2,2'-bipyridine; OTf(-) = triflate; phen = phenanthroline; terpy = terpyridine; Phterpy = 4'-phenyl-2,2':6',2''-terpyridine) are water- and acid-stable catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOS(O)(2)CF(3) (triflic acid) as a dehydration co-catalyst they directly convert 1,2-hexanediol to n-hexanol and hexane. The terpyridine complexes are stable and active as catalysts at temperatures > or = 250 degrees C and in either aqueous sulfolane solution or pure water convert glycerol into n-propanol and ultimately propane as the final reaction product in up to quantitative yield. For the terpy complexes the active catalyst is postulated to be a carbonyl species [(4'-R-2,2':6',2''-terpy)Ru(CO)(H(2)O)(2)](OTf)(2) (R = H, Ph) formed by the decarbonylation of aldehydes (hexanal for 1,2-hexanediol and 3-hydroxypropanal for glycerol) generated in the reaction mixture through acid-catalyzed dehydration. The structure of the dimeric complex [{(4'-phenyl-2,2':6',2''-terpy)Ru(CO)}(2)(mu-OCH(3))(2)](OTf)(2) has been determined by single crystal X-ray crystallography (Space group P1 (a = 8.2532(17); b = 12.858(3); c = 14.363(3) A; alpha = 64.38(3); beta = 77.26(3); gamma = 87.12(3) degrees, R = 4.36 %).

Abstract  OBJECTIVE: This study was to investigate the topical skin targeting effects and mechanism of combination penetration modifiers of 1,2-hexanediol (or 1,2-heptanediol) and 1,4-cyclohexanediol on transdermal absorption of metronidazole (MTZ) in different skin models.

METHODS: Six formulations were applied to pig abdominal skin and pig ear skin models, respectively, and the results were compared with the previous data on hairless mouse skin worked out by our laboratory. Four parameters (flux, Tlag, Q24 and targeting ratio) were used to evaluate permeability and targeting effect in skin.

RESULTS: The combined penetration modifiers played a general role on decreasing permeability without reducing skin retention. The most significant skin permeability decrement to MTZ was pig abdominal skin (permeability decrement was ∼20% for hairless mouse skin, 60% for pig abdominal skin and 40% for pig ear skin, respectively) while the strongest skin targeting effect appeared in hairless mouse skin (targeting ratios were 1.79 for hairless mouse skin, 1.24 for pig abdominal skin and 1.05 for pig ear skin, respectively) under the role of penetration modifiers.

CONCLUSIONS: Thickness of stratum corneum (SC) was the major factor impact on skin targeting effect. Selection criteria of skin models also have been discussed in this study.

Abstract  The lipase from Candida cylindracea catalyzes the enantioselective esterification of 2-hydroxy acids in nearly anhydrous organic solvents with primary alcohols as nucleophiles. The nature of the 2-hydroxy acid and organic reaction medium affects the efficiency of catalysis and the enantioselectivity. Straight-chain 2-hydroxy acids are highly reactive and give nearly 100% enantioselectivities in esterification reactions with 1-butanol. Slight branching with a methyl group adjacent to the 2-hydroxy moiety in toluene causes a substantial loss (up to 200-fold) in the lipase's catalytic efficiency with a concomitant loss in enantioselectivity. Losses in catalytic efficiency and enantioselectivity are also observed when the lipase is employed in hydrophilic organic media such as dioxane or tetrahydrofuran as compared to hydrophobic solvents such as toluene. With straight-chain substrates, the lipase is over 100-fold more active in toluene than in tetrahydrofuran or dioxane, while optimal enantioselectivity is observed in toluene. The loss in enantioselectivity in hydrophilic solvents is mainly due to a drop in the catalytic efficiencies of the S isomers, as the R isomers' catalytic efficiencies remain largely unchanged. In highly apolar solvents, such as cyclohexane, enantioselective relaxation occurs due to an increase in the reactivity of the R isomers relative to that of their S counterparts. These findings enabled a rational selection of substrates and solvents for a two-step, chemoenzymatic synthesis of optically active 1,2-diols to be carried out, the first step being the aforementioned enantioselective esterification of 2-hydroxy acids followed by reduction with LiAl(OCH3)3H to give the optically active 1,2-diol. Diols such as (S)-(+)-1,2-propanediol, (S)-(-)1,2-butanediol, (S)-(-)-1,2-hexanediol, and (S)-(-)-4-methyl-1,2-pentanediol were produced in high optical purities (at least 98% enantiomeric excess (ee)).

Abstract  In this work, density and viscosity have been determined for (polyethylene glycol dimethyl ether 250 + 1,2-propanediol, or 1,2-butanediol, or 1,2-pentanediol, or 1,2-hexanediol) binary systems over the whole concentration range at temperatures of (293.15, 303.15, 313.15, 323.15) K and atmospheric pressure. Experimental data of mixtures were used to calculate the excess molar volumes V(E), and viscosity deviations Delta(eta). These results were fitted by the Redlich-Kister polynomial relation to obtain the coefficients and standard deviations. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  The results of positron annihilation experiments in aqueous solutions of 1,2- and 1,6-hexanediols were compared to those of ultrasonic velocity. For the former, the positron annihilation measurement shows strong hydrophobic interactions and formation of clathrate-like hydrates in solution, although their stoichiometries as well as architecture are untypical. Ultrasonic data for this system seem to be strongly influenced by a relaxation process and do not allow to conclude about formation of open-work structures in this system. For the system water + 1,6-hexanediol both the ultrasonic and annihilation methods suggest formation of labile, water-rich hydrates. They are very weak compared to those existing in the water + 1,2-hexanediol, what results from the hydrophilic hydration competing the hydrophobic one.

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  Electronic (e-)cigarettes have emerged in recent years as putative alternative to conventional tobacco cigarettes. These products do not contain typical carcinogens that are present in tobacco smoke, due to the lack of combustion. However, besides nicotine, hazards can also arise from other constituents of liquids, such as solvents, flavors, additives and contaminants. In this study, we have analyzed 28 liquids of seven manufacturers purchased in Germany. We confirm the presence of a wide range of flavors to enhance palatability. Although glycerol and propylene glycol were detected in all samples, these solvents had been replaced by ethylene glycol as dominant compound in five products. Ethylene glycol is associated with markedly enhanced toxicological hazards when compared to conventionally used glycerol and propylene glycol. Additional additives, such as coumarin and acetamide, that raise concerns for human health were detected in certain samples. Ten out of 28 products had been declared "free-of-nicotine" by the manufacturer. Among these ten, seven liquids were identified containing nicotine in the range of 0.1-15 µg/ml. This suggests that "carry over" of ingredients may occur during the production of cartridges. We have further analyzed the formation of carbonylic compounds in one widely distributed nicotine-free brand. Significant amounts of formaldehyde, acetaldehyde and propionaldehyde were only found at 150 °C by headspace GC-MS analysis. In addition, an enhanced formation of aldehydes was found in defined puff fractions, using an adopted machine smoking protocol. However, this effect was delayed and only observed during the last third of the smoking procedure. In the emissions of these fractions, which represent up to 40 % of total vapor volume, similar levels of formaldehyde were detected when compared to conventional tobacco cigarettes. By contrast, carbonylic compounds were hardly detectable in earlier collected fractions. Our data demonstrate the necessity of standardized machine smoking protocols to reliably address putative risks of e-cigarettes for consumers.

Abstract    The aim of the current investigation was to develop and statistically evaluate nanovesicular systems for dermal imiquimod delivery. To this purpose, transethosomes were prepared with phospholipid, ethanol and different permeation enhancers. Conventional ethosomes, with soy phospholipid and ethanol, were used as control. The prepared vesicles were characterized for size, zeta potential, stability and entrapment efficiency. The optimal transethosomal formulation with mean particle size of 82.3 ± 9.5 nm showed the higher entrapment efficiency (68.69 ± 1.7 %). In vitro studies, permeation results of accumulated drug and local accumulation efficiency were significantly higher for transethosomes (24.64 µg/cm^sup 2^ and 6.70, respectively) than control (14.45 µg/cm^sup 2^ and 3.93, respectively). Confocal laser scanning microscopy of rhodamine 6G-loaded transethosomes revealed an enhanced retention into the deeper skin layers as compared to conventional ethosomes. Besides, Fourier-transform infra-red spectroscopy studies were also performed to understand the mechanism of interaction between skin and carriers. What's more, results of in vivo studies indicated the transethosomes of imiquimod providing the most effectiveness for dermal delivery among all of the formulations. These results suggested that transethosomes would be a promising dermal carrier for imiquimod in actinic keratose treatment.

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.