Abstract    The solute retention mechanism in gas-liquid chromatography was studied for the hydrocarbon solute-nonpolar stationary liquid phase (squalane) system. The retention volume of the solute and the specific surface area of the liquid-coated, modified alumina were determined as a function of the liquid loading. On the basis of the previous reasoning, distribution constants for the bulk solution partition and some adsorption equilibria taking part in the solute retention could be estimated. The results prove to be quite different from those of the polar liquid phases used previously: that is, squalane formed a bulk liquid layer on the modified alumina after the solid support was completely covered with the monolayer.

Abstract  Squalane and Squalene have been identified as natural components of human sebum. Both ingredients are used in a variety of cosmetics at concentrations ranging from 5 0.1 to > 504b. Animal studies indicate Squalene is slowly absorbed through the skin, while both compounds are poorly absorbed from the gastrointestinal tract. The acute animal toxicity of these ingredients by all routes is low. Both compounds are nonirritants to rabbit skin and eye at 100% concentration. Formulations containing Squalene indicate it is not a significant human skin irritant or sensitizer. limited contact sensitization tests indicate Squalene is not a significant contact allergen or irritant. It is concluded that both Squalane and Squalene are safe as cosmetic ingredients in the present practices of use and concentration.

Abstract  We have used friction force microscopy to probe friction laws for nanoasperities sliding on atomically flat substrates under controlled atmosphere and liquid environment, respectively. A power law relates friction force and normal load in dry air, whereas a linear relationship, i.e., Amontons' law, is observed for junctions fully immersed in model lubricants, namely, octamethylciclotetrasiloxane and squalane. Lubricated contacts display a remarkable friction reduction, with liquid and substrate specific friction coefficients. Comparison with molecular dynamics simulations suggests that load-bearing boundary layers at junction entrance cause the appearance of Amontons' law and impart atomic-scale character to the sliding process; continuum friction models are on the contrary of limited predictive power when applied to lubrication effects. An attempt is done to define general working conditions leading to the manifestation of nanoscale lubricity due to adsorbed boundary layers.

Abstract  Collisions of hyperthermal oxygen atoms, with an average translational energy of 520 kJ mol(-1), on continuously refreshed ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([emim][NTf2]) and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([C(12)mim][NTf2]), were studied with the use of a beam-surface scattering technique. Time-of-flight and angular distributions of inelastically scattered O and reactively scattered OH and H2O were collected for various angles of incidence with the use of a rotatable mass spectrometer detector. For both O and OH, two distinct scattering processes were identified, which can be empirically categorized as thermal and non-thermal. Non-thermal scattering is more probable for both O and OH products. The observation of OH confirms that at least some reactive sites, presumably alkyl groups, must be exposed at the surface. The ionic liquid with the longer alkyl chain, [C(12)mim][NTf2], is substantially more reactive than the liquid with the shorter alkyl chain, [emim][NTf2], and proportionately much more so than would be predicted simply from stoichiometry based on the number of abstractable hydrogen atoms. Molecular dynamics models of these surfaces shed light on this change in reactivity. The scattering behavior of O is distinctly different from that of OH. However, no such differences between inelastic and reactive scattering dynamics have been seen in previous work on pure hydrocarbon liquids, in particular the benchmark, partially branched hydrocarbon, squalane (C30H62). The comparison between inelastic and reactive scattering dynamics indicates that inelastic scattering from the ionic liquid surfaces takes place predominantly at non-reactive sites that are effectively stiffer than the reactive alkyl chains, with a higher proportion of collisions sampling such sites for [emim][NTf2] than for [C(12)mitn][NTf2].

Abstract  A new approach was undertaken to increase the bifunctionality of USY zeolite based catalyst. Nickel metallic phase was first impregnated onto USY zeolite and composite catalysts NiMo/[gamma-Al2O3+ (Ni)/USY] were prepared from these zeolites. Catalytic properties in toluene hydrogenation and squalane (2,6,10,15,19,23-hexamethyltetracosane) hydrocracking (HCK) were investigated.

Enhanced conversion and middle distillate (MD) selectivity was obtained for catalysts on which nickel has been impregnated on the zeolite powder. These enhancements are ascribed to an increased proximity between the hydrogenation/dehydrogenation (H/DH) function and the acid sites resulting in a more efficient synergy between these two functions. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  Squalane, an emollient used in cosmetics, will be the first product of a biotechnology pilot plant now being started up by Nucelis Inc, a spin-off from Cibus. The plant will use Cibus' Rapid Trait Development System (RTDS), a new gene-editing technology to enable naturally occurring yeast to increase their production of squalene, the precursor of squalane. RTDS differs from genetically modified organisms in that it does not involve the introduction of foreign genes into a microorganism, says Sean O'Connor, president of Nucelis.

Abstract  Liquid-liquid extraction was investigated for use with surfactant enhanced subsurface remediation. A surfactant liquid-liquid extraction model (SLLEM) was developed for batch equilibrium conditions based on contaminant partitioning between micellar, water, and solvent phases. The accuracy of this fundamental model was corroborated with experimental results (using naphthalene and phenanthrene as contaminants and squalane as the extracting solvent). The SLLEM model was then expanded to nonequilibrium conditions. The effectiveness of this nonequilibrium model was corroborated with experimental results from continuous flow hollow fiber membrane systems. The validated models were used to conduct a sensitivity analysis evaluating the effects of surfactants on the removal of the contaminants in liquid-liquid extraction systems. In addition, liquid-liquid extraction is compared to air stripping for surfactant-contaminant separation. Finally, conclusions are drawn as to the impact of surfactants on liquid-liquid extraction processes, and the significance of these impacts on the optimization of surfactant-enhanced subsurface remediation.

Abstract  PURPOSETo develop a multi-compartmental vaccine delivery system for safe and efficient delivery of the gp100 peptide antigen in melanoma immunotherapy.METHODSWater-in-oil-in-water (W/O/W) multiple emulsion-based multi-compartmental vaccine delivery system containing the gp100 peptide was prepared by a two-step emulsification method. In vivo prophylactic and active immunization effectiveness of the novel squalane oil-containing gp100 vaccine was evaluated in the murine B16 melanoma model and compared with that of an incomplete Freund's adjuvant (IFA)-based vaccine.RESULTSMorphological evaluation of the W/O/W multiple emulsions showed that the oil-droplets were homogenously dispersed with the gp100 peptide encapsulated in an inner aqueous phase. Immunization with the gp100 peptide delivered in the W/O/W multiple emulsions-based vaccine resulted in increased protection against tumor challenge compared to IFA-based vaccine (p < 0.05, n = 8) signifying induction of enhanced anti-tumor immunity. In addition, serum Th1 cytokine levels and immuno-histochemistry of excised tumor tissues indicated activation and local infiltration of antigen specific cytotoxic T-lymphocytes into and/or surrounding the tumor mass. Moreover, the newly developed vaccine formulation did not induce any overt systemic toxicity.CONCLUSIONNovel W/O/W multiple emulsions-based vaccine efficiently delivers the gp100 peptide antigen to induce cell-mediated anti-tumor immunity and offers an alternate, safe vaccine delivery system.

Abstract  A series of Miocene/Pliocene halite deposits (with extremely low organic carbon contents) from the Sdom Formation (Dead Sea Basin, Israel) have been studied. Distributions and delta(13)C contents of biomarkers have been determined using GC-MS and irm-GCMS analyses, respectively. The hydrocarbon fractions consist mainly of pristane, phytane and C-21 to C-25 regular isoprenoids. The predominance of C21+ regular isoprenoids in the Dead Sea halites and other hypersaline deposits indicate that these components could be derived from ether-bound membrane lipids of halophilic archaea. The lack of intact ether-bound lipids in the polar fractions indirectly infers that such components have already been released at early stages of diagenesis. Their delta(13)C contents are enriched in C-13, by UP to 7 parts per thousand, compared to the biomarkers of presumed phytoplanktonic origin (i.e. steranes and hopanes) within the same sediment sample, in agreement with a source other than algae and cyanobacteria, thus, tentatively assigned as halophilic archaea. Based on biomarker distributions, delta(13)C contents and mineral compositions, these sediments appear to have been deposited in a salinity stratified water body with a bottom water brine. Continual evaporation and deposition of the higher salts (i.e. carnallites) are favourable conditions for the growth of halophilic archaeal communities. (C) 1998 Elsevier Science Ltd. All rights reserved.

Abstract  A bacterium was isolated from the abscess pus of a 72-year-old patient with Warthin's tumor and parotid abscess. The cells were aerobic, non-motile, Gram-negative but difficult to be destained, non-sporulating, coccobacillus. The bacterium grew poorly on sheep blood agar and MacConkey agar as non-hemolytic colonies of 0.5 mm in diameter after 24h of incubation at 37 degrees C in ambient air. Growth was enhanced by Tween 80. It produces catalase but not cytochrome oxidase. Sequencing of the cloned 16S rRNA PCR products of the bacterium revealed three different 16S rRNA gene sequences, with 12 - 31 bp differences among them. Phylogenetic analysis showed that the bacterium is closely related to Alkanindiges illinoisensis, with 5.0 - 5.9% differences between the 16S rRNA gene sequence of the bacterium and that of A. illinoisensis. Tryptophan auxotrophic strain of Acinetobacter trpE27 transformed with DNA extracted from the bacterium was unable to grow on tryptophan deficient medium, indicating that the bacterium was not a strain of Acinetobacter. The G+C content of the bacterium (mean +/-SD) was 46.9+4.3%. A new species, Alkanindiges hongkongensis sp. nov., is proposed, for which HKU9T is the type strain. Isolates with "small colonies" that are apparently Acinetobacter-like species should be carefully identified. Growth enhancement with aliphatic hydrocarbons should be looked for and 16S rRNA gene sequencing performed in order to find more potential cases of Alkanindiges infections, as well as to define the epidemiology, clinical spectrum, and outcome of infections associated with this genus.

Abstract  While numerous studies have examined modern hypersaline ecosystems, their equivalents in the geologic past, particularly in the Precambrian, are poorly understood. In this study, biomarkers from ~820 million year (Ma)-old evaporites from the Gillen Formation of the mid-Neoproterozoic Bitter Springs Group, central Australia, are investigated to elucidate the antiquity and paleoecology of halophiles. The sediments were composed of alternating laminae of dolomitized microbial mats and up to 90% anhydrite. Solvent extraction of these samples yielded thermally well-preserved hydrocarbon biomarkers. The regularly branched C25 isoprenoid 2,6,10,14,18-pentamethylicosane, the tail-to-tail linked C30 isoprenoid squalane, and breakdown products of the head-to-head linked C40 isoprenoid biphytane, were particularly abundant in the most anhydrite-rich sediments and mark the oldest current evidence for halophilic archaea. Linear correlations between isoprenoid concentrations (normalized to n-alkanes) and the anhydrite/dolomite ratio reveal microbial consortia that fluctuated with changing salinity levels. Halophilic archaea were the dominant organisms during periods of high salinity and gypsum precipitation, while bacteria were prevalent during stages of carbonate formation. The irregularly branched C25 isoprenoid 2,6,10,15,19-pentamethylicosane (PMI), with a central tail-to-tail link, was also abundant during periods of elevated salinity, highlighting the activity of methanogens. By contrast, the irregularly branched C20 isoprenoid 2,6,11,15-tetramethylhexadecane (crocetane) was more common in dolomite-rich facies, revealing that an alternate group of archaea was active during less saline periods. Elevated concentrations of isotopically depleted heptadecane (n-C17 ) revealed the presence of cyanobacteria under all salinity regimes. The combination of biomarkers in the mid-Neoproterozoic Gillen Formation resembles lipid compositions from modern hypersaline cyanobacterial mats, pointing to a community composition that remained broadly constant since at least the Neoproterozoic. However, as a major contrast to most modern hypersaline environments, the Gillen evaporites did not yield any evidence for algae or other eukaryotes.

Abstract    This study is based on the analysis of the retention behavior of some anhydro-D-aldose derivatives in reversed-phase thin-layer chromatography (RP-TLC). Chromatographic separations were achieved applying a methanol/water mobile phase and three different stationary phases: C18-bonded silica gel, silica gel impregnated with paraffin oil, and silica gel impregnated with squalane. Retention behavior of the analyzed molecules was defined by [Formula omitted.] constant and correlated with in silico molecular descriptors. According to the statistical validation parameters, obtained results showed that the established multiple-linear quantitative structure-retention relationship models (MLR-QSRR) can successfully predict the chromatographic lipophilicity of structurally similar compounds. In the present study the influence of some functional groups on the total lipophilicity of studied derivatives was determined as well. Principal component analysis (PCA) was applied in order to obtain an overview of similarity or dissimilarity among the analyzed compounds and hierarchical cluster analysis (HCA) was applied in order to compare separation characteristics of the applied stationary phases.

Abstract  Production of biosurfactants by acidophilic mycobacteria was demonstrated in the course of aerobic degradation of hydrocarbons (n-tridecane, n-tricosane, n-hexacosane, model mixtures of D-14-D-17, D(12)aEuro'D-19, and D-9-D-21 n-alkanes, 2,2,4,4,6,8,8-heptamethylnonane, squalane, and butylcyclohexane) and their complex mixtures (hydrocarbon gas condensate, kerosene, black oil, and paraffin oil) under extremely acidic conditions (pH 2.5). When grown on hydrocarbons, the studied bacterial culture AG(S10) caused a decrease in the surface and interfacial tension of the solutions (to the lowest observed values of 26.0 and 1.3 mN/m, respectively) compared to the bacteria-free control. The rheological characteristics of the culture changed only when mycobacteria were grown on hydrocarbons. Neither the medium nor the cell-free culture liquid had the surfactant activity, which indicated formation of an endotype biosurfactant by mycobacteria. Biodegradation of n-alkanes was accompanied by an increase in cell numbers, surfactant production, and changes in the hydrophobicity of bacterial cell surface and in associated phenomena of adsorption and desorption to the hydrocarbon phase. Research on AGS10 culture liquids containing the raw biosurfactant demonstrated the preservation of its activity within a broad range of pH, temperature, and salinity.

Abstract    In order to characterize the state of aggregation, dielectric relaxation due to interfacial polarization of a system of aqueous agarose gel particles dispersed in a squalane medium jellified by hydrophobic colloidal silica (denoted below as G/(S·O) emulsion) was investigated over a frequency range from 10kHz to 3MHz. The value of the parameter α, a measure of the distribution of relaxation frequency determined from complex plane plots, was zero when there was no aggregation. It was positive while aggregation was progressing and fell toward zero as the aggregation approached the steady state during storage. When the dependence of α on the uniformity of particle size was taken into account, the transient characteristics of dielectric relaxation represented by the positive value of α seemed to indicate that the mode of ion diffusion through the interface layer between particles in contact changed depending on the magnitude and particle size variation of particle clusters. Microscopic observation during aggregation supported the hypothesis that positive α appeared during the progressive stage of aggregation as a result of a transient deviation from uniformity of aggregation. The influence of aggregation on other dielectric parameters is also discussed.

Abstract  In this work, we carried out a comparative study of four different niosome formulations based on the same cationic lipid and non-ionic tensoactive. The niosomes prepared by oil-in-water emulsion technique (o/w) only differed in the helper lipid composition: squalene, cholesterol, squalane or no helper lipid. Niosomes and nioplexes elaborated upon the addition of pCMS-EGFP reporter plasmid were characterized in terms of size, zeta potential and polydispersity index. The capacity of the niosomes to condense, release and protect the DNA against enzymatic degradation was evaluated by agarose gel electrophoresis. In vitro experiments were carried out to evaluate transfection efficiency and cell viability in retinal pigment epithelial cells. Moreover, uptake and intracellular trafficking studies were performed to further understand the role of the helper lipids in the transfection process. Interestingly, among all tested formulations, niosomes elaborated with squalene as helper lipid were the most efficient transfecting cells. Such transfection efficiency could be attributed to their higher cellular uptake and the particular entry pathways used, where macropinocytosis pathway and lysosomal release played an important role. Therefore, these results suggest that helper lipid composition is a crucial step to be considered in the design of niosome formulation for retinal gene delivery applications since clearly modulates the cellular uptake, internalization mechanism and consequently, the final transfection efficiency.

Abstract  This thesis explores the microbial ecology of depositional environments in order to shed light on the 40[per range of organic-carbon isotope compositions recognized in the global record of the late Archean. Kerogen-carbon isotopic compositions (d super(13)C sub(ker)) for a 150 Ma record from the Hamersley Province, Western Australia show a -58 to -27[per spread in d super(13)C sub(ker). Lithofacies association with d super(13)C sub(ker) patterns for the entire period indicate that shallow-water carbonate facies received relatively greater inputs of photosynthate biomass relative to biomass from recycled organic carbon (i.e. methane recycling and chemoautotrophic recycling of super( 13)C-depleted CO sub(2)). In addition, results indicate that a "methane signature" (extreme super(13)C-depletion; <-45[per) is strongly associated with restricted and deep-water environments and that in other environments, particularly open, shallow-water carbonates, the relative proportion of recycled organic carbon was lower and declined further over time. Molecular analysis of both extracted free biomarkers and thermally cleaved bound-biomarkers provides strong supporting evidence for the syngenicity of molecular fossils in these late Archean rocks. Biomarkers indicate microbial diversity including evidence for oxygenic photosynthesizing cyanobacteria, eukaryotic algae, aerobic methylotrophs, and, possibly, green sulfur bacteria. The discovery of >C sub(20) acyclic isoprenoids, including squalane, in these bitumens provides the first molecular evidence for the Archaea Domain at 2.72 Ga. Moreover, the presence of quaternary-branched alkanes suggests input from chemoautotrophic sulfide-oxidizing bacteria in slope environments. Both isotopic and molecular results support the onset and expansion of marine oxygenation during the late Archean prior to the rise of atmospheric oxygen at 62.3 Ga. The extreme super(13)C-depletion is attributed to recycling of organic carbon, potentially by anaerobic methane oxidation, despite molecular evidence for the activities of aerobic methylotrophs in late Archean environments.

Abstract  We demonstrate the first capture and analysis of secondary organic aerosol (SOA) on a droplet suspended in an aerosol optical tweezers (AOT). We examine three initial chemical systems of aqueous NaCl, aqueous glycerol, and squalane at ∼75% relative humidity. For each system we added α-pinene SOA-generated directly in the AOT chamber-to the trapped droplet. The resulting morphology was always observed to be a core of the original droplet phase surrounded by a shell of the added SOA. We also observed a stable emulsion of SOA particles when added to an aqueous NaCl core phase, in addition to the shell of SOA. The persistence of the emulsified SOA particles suspended in the aqueous core suggests that this metastable state may persist for a significant fraction of the aerosol lifecycle for mixed SOA/aqueous particle systems. We conclude that the α-pinene SOA shell creates no major diffusion limitations for water, glycerol, and squalane core phases under humid conditions. These experimental results support the current prompt-partitioning framework used to describe organic aerosol in most atmospheric chemical transport models and highlight the prominence of core-shell morphologies for SOA on a range of core chemical phases.

Abstract  The reaction kinetics of the three-phase CO2 methanation for a commercial Ni/SiO2 catalyst suspended in a liquid phase is studied in a continuous stirred-tank slurry reactor at a CO2 partial pressure of 1 bar and temperatures from 220 degrees C to 320 degrees C. By applying different liquids, namely squalane, octadecane, and dibenzyltoluene, showing different gas solubilities, it is found that the gas concentration in the liquid phase and not the partial pressure in the gas phase is the driving force for the CO2 methanation reaction kinetics. The liquid phase does not influence the reaction kinetics but reduces the available gas concentrations and H-2/CO2 ratio on the catalyst surface. Based on these findings, a kinetic rate equation for the three-phase CO2 methanation is developed additionally incorporating the chemical equilibrium limitations relevant in the temperature regime.

Abstract  Double oxide,SrxCa1-xCuOy has a layered structure in which Ca(Sr) is sandwiched between CuO2 layers. This crystal structure is expected to give low friction due to its low shear strength between laminas, In this work, various kind of SrxCa1-xCuOy with x=0.0 to 1.0 were prepared from SrCO3, CaCO3 and CuO by sintering method. The compositions of these products were examined by X-ray diffraction. The sample powders were blended in oil (squalane) and grease, and their load carrying capacities were evaluated by a cylinder-on-plate type tribometer and a four-ball machine, respectively. As a result of the tests, SrxCa1-xCuOy with x=0.0, 0.14, 0.90 and 1.0 showed low friction (about 0.1) and high load carrying capacity (4900 N). It was found from SEM and EPMA results that the worn surface was smooth, and that a thin solid lubricating him containing Ca, Sr and Cu was formed on the rubbing counterface. Also, the oxides with x=0.9 and 1.0 showed superior properties under extreme pressure in four-ball machine testing.

Abstract    Squalene (SQ), a precursor of sterols and terpenoids is a functional lipid of high importance in the food and pharmaceutical sectors. SQ oxidation studies are rather limited compared with those for other olefins. The aim of the present study was to monitor the formation of SQ oxidation products under different conditions (temperature, air supply), to characterise the most abundant of them by spectroscopic techniques and then examine their pro-oxidant activity in a model lipid substrate. Squalane (SQA), the saturated analogue of SQ, was used as a reference compound. FT-MIR analysis indicated the presence of alcohols, epoxides, aldehydes, and ketones. GC-MS was used to characterise SQ primary oxidation and scission products. The presence of epoxides was further confirmed by means of 1H NMR and 13C NMR spectroscopy. It could be argued that SQ stability is due to its stereochemistry and specifically to the presence of methyl groups next to the double bonds. The pro-oxidant activity of SQ oxidation products was evident at 62 and 40°C and suppressed only in the presence of primary antioxidants, not of SQ. The present work adds to the characterisation of SQ oxidised products. To our knowledge their pro-oxidant activity has never been examined before. Practical applications: Characterisation of squalene oxidation products and assessment of their activity as pro-oxidants present both scientific interest regarding the kinetics and product identity as well as a practical impact in case this bioactive lipid is provided for consumption as a functional product. In the past, cholesterol oxidation products and more recently phytosterol ones attracted the interest of researchers, who studied the stability of the respective parent compounds for food safety reasons. Monitoring of the formation of SQ oxidation products under different conditions (temperature, air supply) and chemical characterisation of the most abundant of them by spectroscopic techniques. Examination of their pro-oxidant activity in a model lipid substrate. Squalene may exert a weak antioxidant activity due to competitive oxidation phenomena with the lipid substrate while its oxidation products have a pro-oxidant activity on purified olive oil model substrate that was suppressed only in the presence of primary antioxidants. [PUBLICATION ABSTRACT]

Abstract  Squalene is a natural triterpenoid present virtually in all taxonomic groups. Its use for improving human health is rooted in ancient human history as several Pacific nations consumed the oil from livers of deep-sea sharks with high squalene content to improve their health and extend the life. In addition to the use as nutritional supplement, this molecule finds today many applications in pharmacology and cosmetics, or as a valuable industrial lubricant. Broad application potential of squalene is related to its physico-chemical characteristics, antioxidant activity and to its ability to interact with cell membranes. The industrial use of squalene is limited by short natural resources. Even today squalene is acquired mainly from shark liver oil; however, this source is no more tenable from the environmental viewpoint. Plant sources (e.g. olives, amaranth seeds) and particularly microbial production are thus gaining importance as promising alternatives for extended industrial use of squalene.

Abstract  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.

Abstract  The particle/gas partition coefficient Kp is an important parameter affecting the fate and transport of indoor semivolatile organic compounds (SVOCs) and resulting human exposure. Unfortunately, experimental measurements of Kp exist almost exclusively for atmospheric polycyclic aromatic hydrocarbons, with very few studies focusing on SVOCs that occur in indoor environments. A specially designed tube chamber operating in the laminar flow regime was developed to measure Kp of the plasticizer di-2-ethylhexyl phthalate (DEHP) for one inorganic (ammonium sulfate) and two organic (oleic acid and squalane) particles. The values of Kp for the organic particles (0.23 ± 0.13 m3/μg for oleic acid and 0.11 ± 0.10 m3/μg for squalane) are an order of magnitude higher than those for the inorganic particles (0.011 ± 0.004 m3/μg), suggesting that the process by which the particles accumulate SVOCs is different. A mechanistic model based on the experimental design reveals that the presence of the particles increases the gas-phase concentration gradient in the boundary layer, resulting in enhanced mass transfer from the emission source into the air. This novel approach provides new insight into experimental designs for rapid Kp measurement and a sound basis for investigating particle-mediated mass transfer of SVOCs.

Abstract  We conducted the guinea pig three days repeated open patch test using the samples of three polyols (propylene glycol, 1, 3-butylene glycol and glycerin) as is and 10% in distilled water and of three hydrocarbons (liquid paraffin #72, squalane and pristane). Tests were performed in three labolatories. Comparing the mean reaction of each three laboratories based on Japanese standard, the all samples of the polyols were weak in the skin reactions and no clear differences of reactions were seen. On the other hand, hydrocarbons showed irritant reactions and the order of irritancy was pristane, liquid paraffin #72 and squalane. By the Draize standard, polyols showed slight erythema and no edema, and hydrocarbons showed parallel score between erythema and edema, and the irritation order of three hydrocarbons was the same as that of the Japanese standard. Though some differences were shown in the grade of reactions between three laboratories, there was shown the same order as to the irritation grade of three chemicals.