Abstract  The reactive uptake coefficients γ, for nitrate radical, NO(3), on ∼100 nm diameter squalane and squalene aerosol were measured (1 atm pressure of N(2) and 293 K). For squalane, a branched alkane, γ(NO(3)) of 2.8 × 10(-3) was estimated. For squalene which contains 6 double bonds, γ(NO(3)) was found to be a function of degree of oxidation with an initial value of 0.18 ± 0.03 on fresh particles increasing to 0.82 ± 0.11 on average of over 3 NO(3) reactions per squalene molecule in the aerosol. Synchrotron VUV-ionization aerosol mass spectrometry was used to detect the particle phase oxidation products that include as many as 3 NO(3) subunits added to the squalene backbone. The fraction of squalene remaining in the aerosol follows first order kinetics under oxidation, even at very high oxidation equivalents, which suggests that the matrix remains a liquid upon oxidation. Our calculation indicates a much shorter chemical lifetime for squalene-like particle with respect to NO(3) than its atmospheric lifetime to deposition or wet removal.

Abstract  This study was conducted to better understand the processes of carbonaceous deposits formation in the piston grooves of direct injection Diesel engines. An experimental investigation of parameters affecting the engine oil degradation in the first groove of a Diesel engine was carried out to shed light on the formation of these carbonaceous deposits. A dedicated reactor was designed to reproduce the parameters that exist in the first groove of a Diesel engine used under exhaust gas recirculation conditions, and squalane was used to model the lubricant. The relationship between oil degradation and environmental conditions (temperature, pressure, time, oxygen content and components of the gas in the groove) was clarified by characterizing the degradation levels of the squalane molecule. A general mechanism was proposed to explain the formation of carbon deposits in the first piston grooves of Diesel engines depending on the surrounding atmosphere. The influence of pressure on degradation conditions usually investigated under atmospheric conditions was proposed for the first time to understand processes responsible for carbonaceous deposit formation.

Abstract  Predisafe (rabbit cornea broblast cells culture) is an alternative method developped by Biopredic to determine the occular irritating potential. Cell layer was exposed to pure solution of perhydrosqualen (animal squalan) and cytotoxicity was evluated by neutral red colorimetric method. The results show an ocular tolerance inferior to 15, the substance is considered as slightly irritant for eyes.

Abstract  Assessment of mutagenic activity of squalane was conduced on "Salmonella typhimurium his-" and "Escherichia coli WP2(uvrA)" strains according to the OECD guideline n°471. There is no signicant difference between the number of spontaneaous reversions, the number of reversions obtained in the positive controls (with or without metabolica cativation), and the mean of corresponding experimental historic values obtained in the laboratory. There is no evidence of any increase of number of revertant colonies in the presence of the test substance (5000, 1000, 500, 100 and 50 µg) with or without metabolic activation for bacterial strains in Salmonella typhimurium TA1535, TA97a, TA98, TA100 and Escherichia coli WP2(uvrA).

Abstract  The reaction of Cl atoms, in the presence of Cl(2) and O(2), with sub-micron squalane particles is used as a model system to explore how surface hydrogen abstraction reactions initiate chain reactions that rapidly transform the chemical composition of an organic particle. The heterogeneous reaction is measured in a photochemical flow tube reactor in which chlorine atoms are produced by the photolysis of Cl(2) at 365 nm. By monitoring the heterogeneous reaction, using a vacuum ultraviolet photoionization aerosol mass spectrometer, the effective reactive uptake coefficient and the distributions of both oxygenated and chlorinated reaction products are measured and found to depend sensitively upon O(2), Cl(2), and Cl concentrations in the flow reactor. In the absence of O(2), the effective reactive uptake coefficient monotonically increases with Cl(2) concentration to a value of ∼3, clearly indicating the presence of secondary chain chemistry occurring in the condensed phase. The effective uptake coefficient decreases with increasing O(2) approaching a diffusion corrected value of 0.65 ± 0.07, when 20% of the total nitrogen flow rate in the reactor is replaced with O(2). Using a kinetic model it is found that the amount of secondary chemistry and the product distributions in the aerosol phase are controlled by the competitive reaction rates of O(2) and Cl(2) with alkyl radicals. The role that a heterogeneous pathway might play in the reaction of alkyl radicals with O(2) and Cl(2) is investigated within a reasonable range of reaction parameters. These results show, more generally, that for heterogeneous reactions involving secondary chain chemistry, time and radical concentration are not interchangeable kinetic quantities, but rather the observed reaction rate and product formation chemistry depends sensitively upon the concentrations and time evolution of radical initiators and those species that propagate or terminate free radical chain reactions.

Abstract  Tetradecane (TD), testosterone (TS), and dimethyl sulfoxide (DMSO) were separately inuncted on rabbit pinnas once a day; the pinnas were biopsied on days 1, 3, 7, and 28. Untreated pinnas and squalane-treated pinnas were used as controls. Three-dimensional images of sebaceous glands were reconstructed from their serial histologic sections using a computer-image analysis system. By stereometry, the sebaceous gland volumes gradually increased during the course of treatments with TS and DMSO, whereas the volumes of TD-treated sebaceous glands increased, reached the maximum on day 7, and then decreased. The acinus number was increased by all the substances, the DMSO-treated sebaceous glands on day 28 showing the largest number of acini. The volumes of individual acini increased until day 28 with TS treatment, whereas with TD and DMSO treatments they increased, reached the maximum on day 7, and then decreased. Stereographically, each untreated control sebaceous gland was composed of 20-30 pear-shaped acini. On day 28, acini of TS-treated sebaceous glands were swollen and ovoid in shape, DMSO-treated sebaceous glands resembled a bunch of grapes, and acini of TD-treated sebaceous glands were widely scattered and showed globular swelling arising from an elongated tube. Hyperplastic responses of sebaceous glands are quite different according to substances applied topically.

Abstract  Assessment of acute toxicity of squalan in rats was conduced according "guidelines for toxicity studies issued by Ministry of Health and Welfare of Japan (MHW) - 1993. The test item was administered orally to rats (male and female) at the unique dose of 2000 mg/kg and its acute toxicity was assessed. Observation period was conduced from J0 (administration) to J14. No deaths occurred throughout the observation period, no abnormality was observed and the body weight gain increased normally. Based on these results, it is concluded that the oral LDL0 (lethal dose lowest) of squalan is greater than 2 000mg/kg.

Abstract  The test has been realized according OCDE 84/449 L251 method on 10 animals (wistar rats - 5 females and 5 males). The test item was administrated by oral gavage at the unique dose of 2 ml/kg. Animals were observed from J0 (oral administration) to J14. No mortality, neither no clinical sign were observed after oral administration of 2 ml/kg. In the test conditions, the substance is considered as nontoxic after oral administration of a unique dose 2 ml/kg.

Abstract  Insights into the influence of molecular structure and thermodynamic phase on the chemical mechanisms of hydroxyl radical-initiated heterogeneous oxidation are obtained by identifying reaction products of submicrometer particles composed of either n-octacosane (C28H58, a linear alkane) or squalane (C30H62, a highly branched alkane) and OH. A common pattern is observed in the positional isomers of octacosanone and octacosanol, with functionalization enhanced toward the end of the molecule. This suggests that relatively large linear alkanes are structured in submicrometer particles such that their ends are oriented toward the surface. For squalane, positional isomers of first-generation ketones and alcohols also form in distinct patterns. Ketones are favored on carbons adjacent to tertiary carbons, while hydroxyl groups are primarily found on tertiary carbons but also tend to form toward the end of the molecule. Some first-generation products, viz., hydroxycarbonyls and diols, contain two oxygen atoms. These results suggest that alkoxy radicals are important intermediates and undergo both intramolecular and intermolecular (chain propagation) hydrogen abstraction reactions. Oxidation products with carbon number less than the parent alkane's are observed to a much greater extent for squalane than for n-octacosane oxidation and can be explained by the preferential cleavage of bonds involving tertiary carbons.

Abstract  Recent work has established that secondary organic aerosol (SOA) can exist as an amorphous solid, leading to various suggestions that the addition of SOA coatings to existing particles will decrease the reactivity of those particles toward common atmospheric oxidants. Experimental evidence suggests that O3 is unable to physically diffuse through an exterior semisolid or solid layer thus inhibiting reaction with the core. The extent to which this suppression in reactivity occurs for OH has not been established, nor has this been demonstrated specifically for SOA. Here, measurements of the influence of adding a coating of α-pinene+O3 SOA onto squalane particles on the OH-initiated heterogeneous oxidation rate are reported. The chemical composition of the oxidized internally mixed particles was monitored online using a vacuum ultraviolet-aerosol mass spectrometer. Variations in the squalane oxidation rate with particle composition were quantified by measurement of the effective uptake coefficient, γeff, which is the loss rate of a species relative to the oxidant-particle collision rate. Instead of decreasing, the measured γeff increased continuously as the SOA coating thickness increased, by a factor of ∼2 for a SOA coating thickness of 42 nm (corresponding to ca. two-thirds of the particle mass). These results indicate that heterogeneous oxidation of ambient aerosol by OH radicals is not inhibited by SOA coatings, and further that condensed phase chemical pathways and rates in organic particles depend importantly on composition.

Abstract  IPA COPYRIGHT: ASHP The toxicity of 26 cosmetics excipients was evaluated using a rabbit test. The ocular and cutaneous effects were evaluated using official French methods with some additions. The results show that 13 samples gave adverse reactions after repeated skin exposures; 8 of them appeared to be significantly more irritant--4 isopropyl myristates and 4 oleyl alcohols each from different sources. Eleven excipients were well tolerated when applied undiluted during 60 days and 2 gave uncertain results. Compounds tested included squalane, caprylic triglycerides, isopropyl myristate and palmitate, decyl oleate, octyl palmitate and stearate, oleyl alcohol and polyoxyethylene sorbitan stearate.

Abstract  Biological oil hydrocarbons degradation is a complicated process, influenced by hydrocarbons properties, microorganisms and environmental conditions. The aim of this work was to select microbial strain, capable of degrading heavy branched hydrocarbons for further application in environment remediation and bio-cracking. Also, it was necessary to select optimal conditions (temperature, pH, concentration and etc.) for selected microbial strain degrading heavy branched hydrocarbons. Since crude oil and its products are mixtures of various hydrocarbons, at the first step of selection the ability of the strains to degrade individual hydrocarbons was investigated. Squalane was used as a test substrate. 10 microbial cultures belonging to genus Arthrobacter and obtained from culture collection of JSC "Biocentras" were used for the investigations. Gas chromatography analysis revealed that Arthrobacter sp NJ5 strain had the highest effectiveness (67%) in degradation of heavy branched oil hydrocarbon (Squalane) to shorter chain intermediates. So, Arthrobacter sp NJ5 could be applied in bio-cracking. For the application in industry, more detailed analyses are needed.