Health & Environmental Research Online (HERO)


Squalane (111-01-3)


134 References Were Found:

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Formation of environmentally persistent free radicals from the heterogeneous reaction of ozone and polycyclic aromatic compounds

Authors: Borrowman, CK; Zhou, S; Burrow, TE; Abbatt, JP (2016) Physical Chemistry Chemical Physics 18:205-212. HERO ID: 3075503

[Less] In the 1980s long-lived radical species were identified in cigarette tar. Since then, environmentally . . . [More] In the 1980s long-lived radical species were identified in cigarette tar. Since then, environmentally persistent free radicals (EPFRs) have been observed in ambient particulate matter, and have been generated in particulate matter generated from internal combustion engines. For the first time, we measure in situ the formation and decay of EPFRs through the heterogeneous reaction of ozone and several polycyclic aromatic compounds (PAC). Solid anthracene (ANT), pyrene (PY), benzo[a]pyrene (BAP), benzo[ghi]perylene (BGHIP), 1,4-naphthoquinone (1,4NQ), and 9,10-anthraquinone (AQ) were reacted with gas-phase ozone in a flow system placed in the active cavity of an electron paramagnetic resonance (EPR) spectrometer, and the formation of radicals was measured on the timescale of tens of minutes at ambient levels of ozone down to 30 ppb. For most substrates the net radical production is initially rapid, slows at intermediate times, and is followed by a slow decay. For oxidized solid BAP, radical signal persists for many days in the absence of ozone. To evaluate the effect of substrate phase, the solid PAHs were also dissolved in squalane, an organic oil inert to ozone, which yielded a much higher maximum radical concentration and faster radical decay when exposed to ozone. With higher mobility, reactants were apparently able to more easily diffuse and react with each other, yielding the higher radical concentrations. The EPR spectra exhibit three radicals types, two of which have been assigned to semiquinone species and one to a PAH-derived, carbon-centered radical. Although our system uses levels of PAC not typically found in the environment it is worth noting that the amounts of radical formed, on the order of 10(18) radicals per g, are comparable to those observed in ambient particulate matter.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

The Reactive-Diffusive Length of OH and Ozone in Model Organic Aerosols

Authors: Lee, L; Wilson, K (2016) Journal of Physical Chemistry A 120:6800-6812. HERO ID: 3457694

[Less] A key step in the heterogeneous oxidation of atmospheric aerosols is the reaction of ozone (O3) and . . . [More] A key step in the heterogeneous oxidation of atmospheric aerosols is the reaction of ozone (O3) and hydroxyl radicals (OH) at the gas-particle interface. The formation of reaction products and free radical intermediates and their spatial distribution inside the particle is a sensitive function of the length over which these oxidants diffuse prior to reaction. The reactive-diffusive length of OH and ozone at organic aerosol interfaces is determined by observing the change in the effective uptake coefficient for size-selected model aerosols comprising a reactive core and a thin nanometer-sized (0-12 nm) organic shell. The core and shell materials are selected so that they are immiscible and adopt an assumed core-shell configuration. The results indicate a reactive-diffusive length of 1.4 nm for hydroxyl (OH) radicals in squalane and 1.0 nm for ozone in squalene. Measurements for a purely diffusive system allow for an estimate for diffusion constant (1.6 × 10(-6) cm(2)/s) of ozone in squalane to be determined. The reactive-diffusive length offers a simple first order estimate of how shielding of aerosols by immiscible layers can alter estimates of oxidative lifetimes of aerosols in the atmosphere.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Palladium-Nanoparticles-Intercalated Montmorillonite Clay: A Green Catalyst for the Solvent-Free Chemoselective Hydrogenation of Squalene

Authors: Soni, VK; Sharma, RK (2016) HERO ID: 4972309

[Less] Squalane is an important ingredient in the cosmetic, nutraceutical, and pharmaceutical industries. It . . . [More] Squalane is an important ingredient in the cosmetic, nutraceutical, and pharmaceutical industries. It has also been used as a model compound for the hydrocracking of crude and microalgae oil. Thus, a series of green heterogeneous metal catalysts were prepared to achieve complete hydrogenation of highly unsaturated squalene into squalane. Surface modification of the clay and metal intercalation simultaneously occurred during wet impregnation. The Pd-nanoparticles-intercalated clay with a dominating Pd(111) facet showed the highest reactivity and selectivity. The catalyst was stable with very low Pd leaching (approximate to 0.03 ppm) and was recyclable without losing any significant catalytic activity.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Nucleation curves of methane - propane mixed gas hydrates in hydrocarbon oil

Author: Maeda, N (2016) Chemical Engineering Science 155:1-9. HERO ID: 4999223

[Less] The second generation High Pressure Automated Lag Time Apparatus (HP-ALTA MkII) was used to measure . . . [More] The second generation High Pressure Automated Lag Time Apparatus (HP-ALTA MkII) was used to measure the nucleation curves of Structure II (sII)-forming methane-propane mixed gas hydrates on the surface of a quasi-free water droplet suspended in involatile hydrocarbon oil, squalane. The measured nucleation curves were then compared to the previously obtained nucleation curves of the same guest gas hydrate on a quasi-free water droplet supported by perfluorodecalin. The comparison of the two sets of data sets showed that the nucleation rates of the two systems were broadly similar to each other. A simple master nucleation curve was derived for each system as a function of the system subcooling. The model-independent empirical equation that relates the nucleation rate to the system subcooling was J(water-guest) (S-1 m(-2))=2.38 x 10(-39) Delta T-26.746 for a quasi-free water droplet suspended in squalane and J(water-guest) (S-1 m(-2))=7.70 x 10(-11) Delta T-7.931 for a quasi-free water droplet supported by perfluorodecalin. The nucleation rates predicted by these empirical equations are then compared to the nucleation rates of other relevant systems in the literature. The model-independent analysis method for the derivation of nucleation curves we have developed can be applied to constant cooling ramp data obtained by any experimental techniques. (C) 2016 Elsevier Ltd. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Polarity and Nonpolarity of Ionic Liquids Viewed from the Rotational Dynamics of Carbon Monoxide

Authors: Yasaka, Y; Kimura, Y (2015) Journal of Physical Chemistry B 119:15493-15501. HERO ID: 4969014

[Less] The rotational dynamics of carbon monoxide (CO) in a molten salt, ionic liquids (ILs), and alkanes were . . . [More] The rotational dynamics of carbon monoxide (CO) in a molten salt, ionic liquids (ILs), and alkanes were investigated by (17)O NMR T1 measurements using labeled C(17)O. The molten salt and the studied ILs have the bis(trifluoromethanesulfonyl)imide anion ([NTf2](-)) in common. In hexane near room temperature, the rotational relaxation times are close to the values predicted from the slip boundary condition in the Stokes-Einstein-Debye (SED) theory. However, in contradiction to the theoretical prediction, the rotational relaxation times decrease as the value of η/T increases, where η and T are the viscosity and absolute temperature, respectively. In other alkanes and ILs used in this study, the rotational relaxation times are much faster than those predicted by SED, and show a unique dependence on the number of alkyl carbons. For the same value of η/T, the CO rotational relaxation times in ILs composed of short-alkyl-chain-length imidazolium cations (1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium) are close to those for a molten salt (Cs[NTf2]). On the other hand, the rotational relaxation times in ILs composed of long-chain-length imidazolium (1-methyl-3-octylimidazolium) and phosphonium (tributylmethylphosphonium and tetraoctylphosphonium) cations are much shorter than the SED predictions. This deviation from theory increases as the alkyl chain length increases. We also found that the rotational relaxation times in dodecane and squalane are similar to those in ILs with a similar number of alkyl carbons. These results are discussed in terms of heterogeneous solvation and in comparison with the translational diffusion of CO in ILs.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Probing Gas-Liquid Interfacial Dynamics by Helium Evaporation from Hydrocarbon Liquids and Jet Fuels

Authors: Lancaster, DK; Johnson, AM; Kappes, K; Nathanson, GM (2015) Journal of Physical Chemistry C 119:14613-14623. HERO ID: 3044681

[Less] We have monitored the speeds of evaporating helium atoms dissolved in liquid octane, isooctane, 1-methylnaphthalene, . . . [More] We have monitored the speeds of evaporating helium atoms dissolved in liquid octane, isooctane, 1-methylnaphthalene, dodecane, squalane, ethylene glycol, and two jet fuels. In all cases, the average kinetic energies of the evaporating He atoms exceed the Maxwellian value of 2RT. The energies roughly track solvent surface tensions; this correlation may reflect the tighter packing and attractions of interfacial solvent molecules that restrict the gaps through which He atoms escape. Mixtures of dodecane, squalane, and 1-methylnaphthalene generate He evaporation energies that lie between the pure liquid values. We find, however, that He atoms evaporate from pure 1-methylnaphthalene with kinetic energies lower than expected based on its high surface tension, perhaps because the sideways packing of the aromatic rings provides more direct channels for the escaping He atoms. Additionally, He evaporates from two complex fuel mixtures, Jet A and JP-8, with nearly identical energies, implying that the extra additives in JP-8 do not segregate to the surface in ways that alter the dynamics of evaporation.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Probing the Evaporation Dynamics of Mixed SOA/Squalane Particles Using Size-Resolved Composition and Single-Particle Measurements

Authors: Robinson, ES; Saleh, R; Donahue, NM (2015) Environmental Science and Technology 49:9724-9732. HERO ID: 3009638

[Less] An analysis of the formation and evaporation of mixed-particles containing squalane (a surrogate for . . . [More] An analysis of the formation and evaporation of mixed-particles containing squalane (a surrogate for hydrophobic primary organic aerosol, POA) and secondary organic aerosol (SOA) is presented. In these experiments, one material (D62-squalane or SOA from α-pinene + O3) was prepared first to serve as surface area for condensation of the other, forming the mixed-particles. The mixed-particles were then subjected to a heating-ramp from 22 to 44 °C. We were able to determine that (1) almost all of the SOA mass is comprised of material less volatile than D62-squalane; (2) AMS collection efficiency in these mixed-particle systems can be parametrized as a function of the relative mass fraction of the components; and (3) the vast majority of D62-squalane is able to evaporate from the mixed particles, and does so on the same time scale regardless of the order of preparation. We also performed two-population mixing experiments to directly test whether D62-squalane and SOA from α-pinene + O3 form a single solution or two separate phases. We find that these two OA types are immiscible, which informs our inference of the morphology of the mixed-particles. If the morphology is core-shell and dictated by the order of preparation, these data indicate that squalane is able to diffuse relatively quickly through the SOA shell, implying that there are no major diffusion limitations.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Viscous Calibration Liquids for Self-Diffusion Measurements

Author: Harris, KR (2015) Journal of Chemical and Engineering Data 60:3506-3517. HERO ID: 3579588

[Less] Self-diffusion measurements made by steady or pulsed field gradient spin echo NMR are not absolute and . . . [More] Self-diffusion measurements made by steady or pulsed field gradient spin echo NMR are not absolute and the magnetic field gradients employed must normally be determined by calibration with liquids with known self-diffusion coefficients. The primary calibrant is water, with self-diffusion coefficient values having been extrapolated from the tracer diffusion of HDO and of HTO in ordinary water by Mills,(1) with a relative standard uncertainty of 0.2 %. This and other liquids presently used for calibration all have low viscosities. Current work on ionic liquids, which are generally quite viscous, suggests there may be problems with the pulsed field gradient (PGSE) techniques usually employed as results dependent on the time interval between gradient pulses have been reported by Hayamizu et al.(2) In this work, self-diffusion coefficients, obtained by a steady gradient (SG) technique, are reported for the viscous molecular liquids squalane, ethylhexyl benzoate, and bis(ethylhexyl) phthalate (DEHP), and it is suggested that these substances may be suitable secondary reference materials for the calibration of spin echo NMR apparatus when self-diffusion in viscous liquids is to be measured. New PGSE measurements for squalane and DEHP are in good agreement with the SG results. We also report on systematic errors found in the secondary calibration data of Holz et al.(3) for cyclohexane, n-dodecane, dirnethyl sulfoxide, and pentan-l-ol (though not for 1,4-dioxane) and suggest toluene in their place as a more convenient low-viscosity calibrant that is also suitable for low temperature work.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Biomarker evidence for Botryococcus and a methane cycle in the Eocene Huadian oil shale, NE China

Authors: Volkman, JK; Zhang, Z; Xie, X; Qin, J; Borjigin, T (2015) Organic Geochemistry 78:121-134. HERO ID: 4968905

[Less] The saturated and unsaturated hydrocarbons of two samples (HD-19 and HD-21) from the same section of . . . [More] The saturated and unsaturated hydrocarbons of two samples (HD-19 and HD-21) from the same section of the Middle Eocene lacustrine Huadian oil shale in NE China were identified and shown to be mainly from algal and bacterial sources. Comparison of the two samples provided an opportunity to explore the contribution from telalginite to the hydrocarbon profiles. Cells identified from microscopy as Botryococcus in the telalginite of HD-21 were confirmed as belonging to the L race of B. braunii from the presence of monoaromatic lycopane derivatives and small amounts of several lycopadienes. Lycopane was abundant and was probably derived from biohydrogenation of lycopadienes and related lipids on the basis of delta C-13 values. Hopane distributions showed a dominance of those with the biological 17 beta, 21 beta-stereochemistry, as expected for an immature shale, with low amounts of 17 beta, 21 alpha-hopanes (moretanes) and 17 alpha,21 beta-hopanes. Two hopenes were also abundant and assigned as C-29 and C-30 neohop-13(18)-enes, which occurred together with the C-29 and C-30 hop-17(21)-enes. These had depleted carbon isotope values (-43.7% to -50.8%), indicative of production by methane oxidizing bacteria (methanotrophs). The high proportion of hopanoids with carbon numbers < C-32 indicates extensive post-depositional diagenetic alteration of bacteriohopanepolyols as well as a direct input of C-30 hopanoids. The data clearly indicate that there was active utilization of methane in this lacustrine depositional setting, but isoprenoid hydrocarbon biomarkers for methanogens, such as pentamethylicosane (PMI) and squalane, were in surprisingly low abundance. It is possible that these bacterial contributions were present as polar lipids. The origins of an unusual C-38 isoprenoid alkane assigned as bipristane are uncertain, but may be from methanogens. Steranes and sterenes were relatively minor components, but abundant diasterenes and 4-methyldiasterenes were present, reflecting significant conversion of the original lipid composition by way of clay-catalysed diagenesis. The biomarker data suggest that the bottom waters in the original depositional environment had low O-2 content, but the sediments were probably neither sulfidic nor strongly reducing. The high content of organic matter in the shale likely reflects both high (but fluctuating) productivity due to eutrophic conditions in the overlying water and good preservation in the sediments. (C) 2014 Elsevier Ltd. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Structure and friction of stearic acid and oleic acid films adsorbed on iron oxide surfaces in squalane

Authors: Doig, M; Warrens, CP; Camp, PJ (2014) Langmuir 30:186-195. HERO ID: 4969015

[Less] The structure and friction of fatty acid surfactant films adsorbed on iron oxide surfaces lubricated . . . [More] The structure and friction of fatty acid surfactant films adsorbed on iron oxide surfaces lubricated by squalane are examined using large-scale molecular dynamics simulations. The structures of stearic acid and oleic acid films under static and shear conditions, and at various surface coverages, are described in detail, and the effects of unsaturation in the tail group are highlighted. At high surface coverage, the measured properties of stearic acid and oleic acid films are seen to be very similar. At low and intermediate surface coverages, the presence of a double bond, as in oleic acid, is seen to give rise to less penetration of lubricant in to the surfactant film and less layering of the lubricant near to the film. The kinetic friction coefficient is measured as a function of shear rate within the hydrodynamic (high shear rate) lubrication regime. Lubricant penetration and layering are observed to be correlated with friction coefficient. The friction coefficient with oleic acid depends only weakly on surface coverage, while stearic acid admits more lubricant penetration, and its friction coefficient increases significantly with decreasing surface coverage. Connections between film structure and friction are discussed.