Abstract  We investigated the effect of dielectric properties of the aqueous medium on the novel type of hydrogel composed of a crude lecithin mixture (PC70) and hexadecanol (HD), in which charged sheet-like bilayers are kept far apart due to interbilayer repulsive interaction. We used dipropylene glycol (DPG) as a modifier of the dielectric properties and examined its effect on the hydrogel by synchrotron X-ray diffraction, differential scanning calorimetry (DSC), polarized optical microscopy, and freeze-fracture electron microscopy. We found that at a DPG weight fraction in the aqueous medium WDPG ≈ 0.4, the bilayer organization is transformed into unusually large flat bilayer stacks with a regular lamellar spacing of 6.25 nm and consequently disintegration of the hydrogel takes place. Semiquantitative calculation of the interbilayer interaction energy based on the Deyaguin-Landau-Verwey-Overbeek (DLVO) theory suggested that the reduction of the aqueous medium dielectric constant ε by DPG may lower the energy barrier preventing flat bilayers from coming closer together. We inferred that the size of the bilayer sheet increases because the reduction of ε promotes protonation of acidic lipids that work as edge-capping molecules.

Abstract  Resilon (RealSeal; SybronEndo, Orange, CA) has been developed as an alternative to gutta percha, but its advantages over gutta percha remain controversial. In this study, we developed a novel zinc oxide/thermoplastic polyurethane (ZnO/TPU) composite root canal-filling material and a visible-light curable urethane-acrylate/tripropylene glycol diacrylate (UA/TPGDA) root canal sealer. The mechanical and thermal properties of the ZnO/TPU composite were compared with those of gutta percha and Resilon. Results showed that the tensile strength and elastic modulus of the ZnO/TPU composite were markedly higher than those of gutta percha and Resilon. The melting points of all three materials were similar; however, the enthalpy change and specific heat of ZnO/TPU (9.4 J/g, 0.7 J/g degrees C) were close to those of gutta percha (10.9 J/g, 0.7 J/g degrees C) but lower than those of Resilon (28.9 J/g, 1.3 J/g degrees C). The results indicate that ZnO/TPU composite exhibits better mechanical strength than Resilon, and its combination with UA/TPGDA sealer has excellent potential to be used as a root canal-filling material.

Abstract  We present shear mechanical and dielectric measurements taken on seven liquids: triphenylethylene, tetramethyltetra-phenyltrisiloxane (Dow Corning 704 diffusion pump fluid), polyphenyl ether (Santovac 5 vacuum pump fluid), perhydrosqualene, polybutadiene, decahydroisoquinoline (DHIQ), and tripropylene glycol. The shear mechanical and dielectric measurements are for each liquid performed under identical thermal conditions close to the glass transition temperature. The liquids span four orders of magnitude in dielectric relaxation strength and include liquids with and without Johari-Goldstein beta relaxation. The shear mechanical data are obtained by the piezoelectric shear modulus gauge method giving a large frequency span (10(-3)-10(4.5) Hz). This allows us to resolve the shear mechanical Johari-Goldstein beta peak in the equilibrium DHIQ liquid. We moreover report a signature (a pronounced rise in the shear mechanical loss at frequencies above the alpha relaxation) of a Johari-Goldstein beta relaxation in the shear mechanical spectra for all the liquids which show a beta relaxation in the dielectric spectrum. It is found that both the alpha and beta loss peaks are shifted to higher frequencies in the shear mechanical spectrum compared to the dielectric spectrum. It is in both the shear and dielectric responses found that liquids obeying time-temperature superposition also have a high-frequency power law with exponent close to -12. It is moreover seen that the less temperature dependent the spectral shape is, the closer it is to the universal -12 power-law behavior. The deviation from this universal power-law behavior and the temperature dependencies of the spectral shape are rationalized as coming from interactions between the alpha and beta relaxations.

Abstract  Using 15O-butanol positron emission tomography (PET), we measured regional cerebral blood flow changes in five healthy young women during exposure to androstadienone, a putative human pheromone, as well as pleasant (gamma-methyl-ionone), unpleasant (methyl-thio-butanoate), and neutral (dipropylene glycol; vehicle compound) odours. Compared with the odorous substances, androstadienone activated a widely distributed neuronal network. Two large cortical fields exhibited consistent activation in each contrast: the anterior part of the inferior lateral prefrontal cortex (PFC) and the posterior part of the superior temporal cortex (STP). Intriguingly, these areas were deactivated by gamma-methyl-ionone and methyl-thio-butanoate. These brain regions can be identified as cortical fields underlying other than olfactory functions, including various aspects of social cognition and attention.

Abstract  Cymbidium kanran, an orchid exclusively distributed in Northeast Asia, has been highly valued as a decorative plant and traditional herbal medicine. Here, C. kanran extracts were prepared in 70% aqueous methanol using ultrasound-assisted extraction (UAE) and subjected to liquid chromatography-photodiode array detection and ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry analysis, which were used for quantitative and qualitative analysis, respectively. It was found that the extracts were rich in flavone C-glycosides including vicenin-2, vicenin-3, schaftoside, vitexin, and isovitexin. Ten deep eutectic solvents (DESs) were synthesized by combining choline chloride (hydrogen bond acceptor) with various polyols and diols (hydrogen bond donors) and were tested as a medium for the efficient production of extracts enriched with potentially bioactive flavone C-glycosides from C. kanran. A DES named ChCl:DPG, composed of choline chloride and dipropylene glycol at a 1:4 molar ratio, exhibited the best extraction yields. Then, the effects of extraction conditions on the extraction efficiency were investigated by response surface methodology. Lower water content in the extraction solvent and longer extraction time during UAE were desirable for higher extraction yields. Under the statistically optimized conditions, in which 100 mg of C. kanran powder were extracted in 0.53 mL of a mixture of ChCl:DPG and water (74:26, w/w) for 86 min, a total of 3.441 mg g-1 flavone C-glycosides including 1.933 mg g-1 vicenin-2 was obtained. This total yield was 196%, 131%, and 71% more than those obtained using 100% methanol, water, and 70% methanol, respectively.

Abstract  The kinetics of the biodegradation of two commercial plasticizers, diethylene glycol dibenzoate (D(EG)DB) and dipropylene glycol dibenzoate (D(PG)DB), as well as two alternative plasticizers, 1,3-propanediol dibenzoate and 2,2-methyl-propyl-1,3-propanediol dibenzoate, were investigated in an aerated bioreactor. The experiments were conducted with resting cells of Rhodococcus rhodochrous, which had been grown with hexadecane as the substrate. The first step in the biodegradation was always the hydrolysis of an ester bond, releasing the corresponding monobenzoate and benzoic acid. Biodegradation of plasticizers and their associated metabolites were modeled using a Monod-type kinetic model. Significant differences between the biodegradation of commercial and alternative plasticizers were observed both in the biodegradation pathway and the biodegradation rates of monobenzoate metabolites. At a selected concentration of 0.4 g/L, the monobenzoates released from the biodegradation of 1,3-propanediol dibenzoate and 2,2-methyl-propyl-1,3-propanediol dibenzoate were degraded approximately 13 and 4 times more quickly, respectively, than the monobenzoate released from the biodegradation of D(PG)DB. The rapid biodegradation of monobenzoates released from microbial hydrolysis of alternative dibenzoate plasticizers was attributed to the lack of an ether bond in these compounds. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  The micro fluid segment technique is used for the continuous-flow synthesis for small silver nanoparticles by reduction of silver ions with sodium borohydride in aqueous solution and for the growth of triangular silver nanoprisms. In result, triangular nanoprisms are obtained in very high yield and high homogeneity. The tuning of the in-plane dipole plasmon resonance can easily be controlled by choosing suited flow rate ratios of silver salt solution and colloidal solution of seed nanoparticles or by different silver salt concentrations. The colloidal aqueous solutions of metal nanoparticles can be used for the preparation of mixtures with water-soluble monomers as acrylamide and for the formation of hydrogel-polymer composite particles in a droplet-based photopolymerization process. Beside spherical composite particles, Janus particles with a hydrophilic nanoparticle-containing composite part are prepared by a combined photopolymerization of the aqueous acrylamide reaction mixture together with embedded droplets of an acrylate-based monomer (Tripropylene Glycol Diacrylate, TPGDA) mixture in a micro co-flow twin arrangement. The components of the mushroom-like particles can easily be distinguished by optical microscopy due to their light-scattering and fluorescence behavior. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Ethyl lauroyl arginate (LAE, ethyl-N-dodecanoyl-L-arginate hydrochloride) is a strong antimicrobial agent that was included as an active compound in an antimicrobial food packaging material. The potential existence of non-intentionally added substances (NIASs) such as impurities must therefore be checked before launching any food contact material onto the market. For this reason, an untargeted analysis of the migration was performed in both food simulants and fresh chicken breast fillets wrapped with the active material. The analysis was performed by liquid chromatography coupled to mass spectrometry detection with a quadrupole-time-of-flight analyzer, LC-MS(QTOF), for the identification of nonvolatile substances. The migration values found for LAE were 0.94±0.14 and 1.62±0.70 μg/g in ethanol 10% v/v (simulant A) and in ethanol 95% v/v (simulant D), respectively, and 0.93±0.17 μg/g in chicken. Other migrants such as dipropylene glycol methyl ether or tributyl-o-acetylcitrate, both coming from the coating were also found, but none of them have potential adverse effects. Bioaccessibility studies showed that after a simulated gastrointestinal digestion, LAE was not available anymore for subsequent intestinal absorption and new toxic compounds were not formed.

Abstract  Molecular dynamics (MD) simulations were applied to investigate the liquid-liquid equilibria of water and dipropylene glycol dimethyl ether (DMM) based on all-atom OPLS force fields and simple point charge (SPC) water model. The default combining rules (geometric means) for describing interactions between water and ether molecules were modified by fitting hydration free energies of dimethyl ether and diethyl ether. The difference of Gibbs free energies (Delta G) was calculated using the thermodynamic integration (TI) method. Extensive simulations were carried out in order to reach high precision in the predicted free energies. The average uncertainties in calculated Delta G are 0.8 kJ/mol for DMM and 0.3 kJ/mol for water. From the calculated Delta G(mix), the mutual solubility of the binary mixture was predicted using the double tangent method at four temperatures ranging from 283 K to 353 K and 1 atm. (c) 2011 Elsevier B.V. All rights reserved.

Abstract  In this work densities, rho, ultrasonic speeds, u, and viscosities, eta, have been measured over the whole composition range for the binary mixtures of dipropylene glycol dimethyl ether (DPGDME) with ethanol, 1-propanol, 1-pentanol, and 1-heptanol at 298.15 K along with the properties of the pure components. By using the experimental values of rho, u, and eta, excess molar volume, V-m(E), deviations in viscosity, Delta eta, excess free energy of activation for viscous flow, Delta G*(E), excess molar isentropic compressibility, K-S,m(E), deviation of the speeds of sound, u(D), from their ideal values u(id) in an ideal mixtures, apparent molar volume, and apparent molar compressibility, (V) over bar (0)(phi,i) and (K) over bar (0)(phi,i). of the components at infinite dilution have been calculated. Finally, the experimental viscosity data have been correlated by the methods of Grunberg-Nissan, Hind, Tamura-Kurata, Chaudhry, Auslaender, Heric, and with McAllister correlations. (c) 2008 Elsevier Ltd. All rights reserved.

Abstract  Liquid densities and heat capacities at 1 MPa, and kinematic viscosities at atmospheric pressure of monoethylene glycol diethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dibutyl ether, and dipropylene glycol dimethyl ether were measured in the temperature range (283.15 to 423.15) K. For each substance, experimental data were correlated with temperature using empirical polynomial equations. The experimental data of kinematic viscosity and heat capacity were used to evaluate the predictive capability of some estimation methods of the literature.

Abstract  Polyolallylcarbonate networks were synthesized in a vacuum at room temperature, with gamma irradiation, in a quiescent radical crosslinking polymerization. The polyfunctional monomers studied here were: diallylcarbonate (DAC), monoethylene glycol bis-allylcarbonate (MEGBAC), propylene glycol bis-allylcarbonate (PGBAC), dipropylene glycol bis-allylcarbonate (DPGBAC) and tris-allylcarbonate of glycerol (TACG). The results of the sol-gel analysis of irradiated monomers and characterization by IR, elemental analysis and GPC of different extracted fractions were that polyol(allylcarbonate) undergoes crosslinking via their pi-bonds (allylic group). The gelation doses are a function of the monomer reactivities, and of the monomer's chemical composition. TACG was the most reactive, while DAC crosslinked at the highest irradiation doses.

Abstract  Relative permittivities (epsilon) at five temperatures, between 293.15 and 313.15K, of binary mixtures of dipropylene glycol monomethyl ether + water and dipropylene glycol monomethyl ether + 2-methoxyethanof are reported in this article. The relative permittivity deviations (Deltaepsilon) were calculated from these experimental data. The results are discussed in terms of intermolecular interactions.

Abstract  The aim of this investigation is to clarify the types and concentrations of VOCs present in various commercial household water-based hand pump spray products used in Japan, and to estimate their average concentrations in indoor air when the spray product is used. We selected glycol and glycol ethers as the main target compounds, as these chemicals were detected at high frequencies and concentrations in a national survey of Japanese indoor air pollution. The extraction of these chemicals using graphite carbon cartridges was examined, with good recoveries and reproducibilities being obtained. Eighteen chemicals were analyzed in 54 commercial products and 8 chemicals were detected. More specifically, dipropylene glycol (DPG) was present in 44 samples (1.1 × 101-1.8 × 104 μg/mL); propylene glycol (PG) was present in 22 samples (1.5 × 101-2.9 × 104 μg/mL); diethylene glycol monoethyl ether (DGMEE) was found in 15 samples (trace amount-1.9 × 103 μg/mL); diethylene glycol (DEG) was present in 9 samples (1.0 × 101-2.4 × 103 μg/mL); 1,3-butandiol (13BG) was found in 5 samples (trace amount-7.4 × 103 μg/mL); 2-ethyl-1-hexanol (2E1H) was detected in 5 samples (3.2 × 10-1-4.4 × 101 μg/mL); diethylene glycol monobutyl ether (DGMBE) was present in 4 samples (2.1 × 101-7.1 × 101 μg/mL); and 3-methoxy-3-methylbutanol (MMB) was found in 2 samples (2.4 × 101-4.7 × 102 μg/mL). In addition, the average concentrations of these chemicals in indoor air were estimated using their maximum concentrations observed in the spray product. The estimated average concentrations of the chemicals in indoor air were determined to range between 1.0 × 10-2 and 1.0 mg/m3, with the exception of 2E1H and DGMBE. Furthermore, the estimated average concentrations of PG, 13BG, and DGMEE in indoor air were comparable to or higher than those reported in a national survey of Japanese indoor air pollution. It therefore appeared that household water-based hand pump sprays may contribute to the presence of these chemicals in indoor air. In contrast, estimated average concentrations of 2E1H in indoor air were low, its concentrations observed in a national survey of Japanese indoor air pollution are likely due to the use of plasticizers and paints.

Abstract  In a prior study on electronic cigarette (EC) refill fluids, Cinnamon Ceylon was the most cytotoxic of 36 products tested. The purpose of the current study was to determine if high cytotoxicity is a general feature of cinnamon-flavored EC refill fluids and to identify the toxicant(s) in Cinnamon Ceylon. Eight cinnamon-flavored refill fluids, which were screened using the MTT assay, varied in their cytotoxicity with most being cytotoxic. Human embryonic stem cells were generally more sensitive than human adult pulmonary fibroblasts. Most products were highly volatile and produced vapors that impaired survival of cells in adjacent wells. Cinnamaldehyde (CAD), 2-methoxycinnamaldehyde (2MOCA), dipropylene glycol, and vanillin were identified in the cinnamon-flavored refill fluids using gas chromatography–mass spectrometry and high-pressure liquid chromatography (HPLC). When authentic standards of each chemical were tested using the MTT assay, only CAD and 2MOCA were highly cytotoxic. The amount of each chemical in the refill fluids was quantified using HPLC, and cytotoxicity correlated with the amount of CAD/product. Duplicate bottles of the same product were similar, but varied in their concentrations of 2MOCA. These data show that the cinnamon flavorings in refill fluids are linked to cytotoxicity, which could adversely affect EC users.

Abstract  Abstract: A new bimolecular photoinitiator system consisting of a ferrocenium salt (Fc) and N-methyl-2-pyrrolidone (NMP) is developed for free radical photopolymerization under visible light irradiation, which was delivered by a halogen lamp. Photopolymerization profiles of tripropylene glycol diacrylate (TPGDA) show that high conversion can be easily achieved. The processes associated with the Fc/NMP system are investigated by photochemical and electrochemical experiments. The results show that the photoinitiation mechanism of this bimolecular system could occur through charge transfers between Fc and NMP. ds: Internet resource her supplied data e field[29]: NMP

Abstract  The dermal penetration of undiluted monopropylene glycol (MPG) and dipropylene glycol (DPG) has been measured in vitro using human abdominal skin under conditions of infinite dose application, and the results compared with predictions from the SKINPERM QSAR model (ten Berge, 2009). The measured steady-state penetration rates (J(ss)) for MPG and DPG were 97.6 and 39.3 mu g/cm(2)/h, respectively, and the permeability coefficients (K(p)) were 9.48 x 10(-5) cm/h for MPG and 3.85 x 10(-5) cm/h for DPG. In comparison, the SKINPERM model slightly over-predicted J(ss) and K(p) for MPG and DPG by between 2.6- and 5.1-fold, respectively. The model predictions of 254 mu g/cm(2)/h and 24.6 x 10(-5) cm/h for MPG, and 202 mu g/cm(2)/h and 19.8 x 10(-5) cm/h for DPG were in fairly good agreement with the measured values. Further, the model predicted a J(ss) of 101 mu g/cm(2)/h and a Kp of 9.9 x 10(-5) cm/h for the homologue tripropylene glycol. Assuming that the measured J(ss) was the same under conditions of finite dose application (taken to be 10 mu L/cm(2)) and was maintained over a 24-h period (both conservative assumptions), the relative dermal absorption of the applied dose was estimated to be 23% (0.96%/h) for MPG and 9% (0.39%/h) for DPG. However, the extrapolation for MPG may be further overestimated due to possible residence in the stratum corneum under infinite conditions of exposure that would not be applicable to a finite loading dose. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract  Propylene glycol ethers are a class of solvents used in a wide array of industrial, commercial and consumer applications, such as in paints, cleaners and inks. A robust toxicity database exists for the propylene glycol ethers that provide strong product safety support. Standard toxicity studies conducted under good laboratory practices indicate a lack of genotoxic, developmental and reproductive hazards. Recent testing efforts have primarily focused in two areas: (1) examination of the chronic toxicity/oncogenicity potential of propylene glycol monomethyl ether (PGME) in rats and mice and (2) expansion of the developmental toxicity database to higher molecular weight P-series glycol ether derivatives (i.e. propylene glycol n-propyl ether (PGPE), propylene glycol n-butyl ether (PGBE) and dipropylene glycol n-butyl ether (DPGBE)). In PGME chronic toxicity/oncogenicity studies no treatment-related increases in the incidence of tumors occurred in either species. Like other previously tested P-series derivatives, PGPE, PGBE and DPGBE were negative in rodent and rabbit developmental toxicity studies. Collectively, the toxicity database for P-series glycol ether products continues to support the lack of significant health effects with proper use of the commercial products. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Abstract  1,3-Dioxane diphenyl, a novel photoinitiator for free-radical polymerization, was synthesized and characterized. UV-Vis absorption spectroscopy was used to investigate its photochemical behavior during the photophysical process. The photopolymerization kinetics of 1,3-dioxane diphenyl was studied by realtime infrared spectroscopy. There was an optimum curing rate with the increase of 1,3-dioxane diphenyl concentration. Both the polymerization rate and final conversion increased with the increase in light intensity. 1,3-Dioxane diphenyl was the most efficient photoinitiator for tripropylene glycol diacrylate and other acrylate monomers. 1,3-Dioxane diphenyl was a more effective photoinitiator than benzophenone/ethyl-4-dimethylaminobenzoate.

Abstract  Various novel porous organic-based monoliths with the mode of hydrophobicity were synthesized by in situ free-radical crosslinking copolymerization and optimized for the separations of small molecules and high-performance reversed-phase chromatography (RP-chromatography). These monoliths contained co-polymers based on glycidyl methacrylate (GMA)/ethylene glycol dimethacrylate (EDMA)/tripropylene glycol diacrylate (TPGDA) or EDMA/TPGDA. A mixture of cetanol, methanol and poly (ethylene glycol) (PEG) was used as the porogen, with the ratio of these solvents being varied along with the polymerization temperature to generate a library of monoliths. The conditions were optimized and the resulting poly (GMA-co-TPGDA-co-EDMA) monolith was investigated by infrared spectrometer (IR), field emission scanning electron microscope (FESEM), and mercury intrusion porosimetry (MIP), respectively. The column performance was assessed by the separation of a series of neutral solutes of benzene derivatives. The result demonstrated that the prepared monolith exhibited an RP-chromatographic behavior and relatively homogeneous structure, good permeability and separation performance. Moreover, the relative standard deviations (RSDs) of the retention factor values for benzene derivatives were less than 1.5% (n=7, column-to-column). The approach used in this study was extended to the separation of anilines.