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.

Abstract  The comedogenicity of UVA-irradiated and non-irradiated substances (squalene, oleic acid, tetradecane, isopropyl myristate, squalane and liquid paraffin) was evaluated by surface microscopy and histological examination after treating the ventral skin of rabbit ears with these substances. The lipid peroxide levels of these substances were also measured. Squalene itself was scarcely comedogenic but squalene peroxides were highly comedogenic. Both oleic acid and its peroxides were able to induce fairly large comedones and there was a good correlation between the lipid peroxide levels and the size of the comedones. The specimens biopsied from these comedones showed marked hyperplasia and hyperkeratosis of the epithelium in the follicular infundibulum and marked proliferation of the sebaceous glands. Although free fatty acids might play a role in the pathogenesis of acne, it is proposed that squalene and free fatty acids in sebum may be less comedogenic than their peroxides.

Abstract  In laboratory studies of organic aerosol particles reacting with gas-phase oxidants, high concentrations of radicals are often used to study on the timescale of seconds reactions which may be occurring over days or weeks in the troposphere. Implicit in this approach is the assumption that radical concentration and time are interchangeable parameters, though this has not been established. Here, the kinetics of OH-and Cl-initiated oxidation reactions of model single-component liquid (squalane) and supercooled (brassidic acid and 2-octyldodecanoic acid) organic aerosols are studied by varying separately the radical concentration and the reaction time. Two separate flow tubes with residence times of 2 and 66 s are used, and [OH] and [Cl] are varied by adjusting either the laser photolysis fluence or the radical precursor concentration ([O(3)] or [Cl(2)], respectively) used to generate the radicals. It is found that the rates measured by varying the radical concentration and the reaction time are equal only if the precursor concentrations are the same in the two approaches. Further, the rates depend on the concentrations of the precursor species with a Langmuir-type functional form suggesting that O(3) and Cl(2) saturate the surface of the liquid particles. It is believed that the presence of O(3) inhibits the rate of OH reaction, perhaps by reacting with OH radicals or by O(3) or intermediate species blocking surface sites, while Cl(2) enhances the rate of Cl reaction by participating in a radical chain mechanism. These results have important implications for laboratory experiments in which high concentrations of gas-phase oxidants are used to study atmospheric reactions over short timescales and may explain the variability in recent measurements of the reactive uptake of OH on squalane particles in reactor systems used in this and other laboratories.

Abstract  The heterogeneous reaction of OH radicals with sub-micron squalane particles, in the presence of O-2, is used as a model system to explore the fundamental chemical mechanisms that control the oxidative aging of organic aerosols in the atmosphere. Detailed kinetic measurements combined with elemental mass spectrometric analysis reveal that the reaction proceeds sequentially by adding an average of one oxygenated functional group per reactive loss of squalane. The reactive uptake coefficient of OH with squalane particles is determined to be 0.3 +/- 0.07 at an average OH concentration of similar to 1 x 10(10) molecules cm(-3). Based on a comparison between the measured particle mass and model predictions it appears that significant volatilization of a reduced organic particle would be extremely slow in the real atmosphere. However, as the aerosols become more oxygenated, volatilization becomes a significant loss channel for organic material in the particle-phase. Together these results provide a chemical framework in which to understand how heterogeneous chemistry transforms the physiochemical properties of particle-phase organic matter in the troposphere.

Abstract  The adsorption coefficient of Squalane (CAS 111-01-3) has been determined to be greater than 4.27 x 105, log10 Koc greater than 5.63, using the HPLC screening method, designed to be compatible with Method C19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

Abstract  The ready biodegradation of the squalane was determined by the carbon dioxide evolution test method (OCDE guideline 301B). Tests of ready biodegradability are stringent tests that provide limited oppotunity for acclimation and biodegradation to occur. In the CO2 test, inoculated mineral medium was dosed with a known amount of test substance as the nominal sole source of organic carbon and aerated with CO2 -free air. The CO2 produced from the mineralization of organic carbon within the test chambers was displaced by the ow of CO2 -free air and trapped as K2CO3 in KOH trapping solution. The amount of CO2 produced by the test substance is expressed as a percentage of the theoretical amount of CO2 that could have been produced if complete biodegradation of the substance occurred. The test contained a blank control, three reference groups and one treatment group. Each group contained two replicate test chambers. The blank control was used to measure the background CO2 production of the inoculum and was dosed with a carbon source. The reference chambers were dosed with either canola oil, Synuid or Ultra Low Sulfur Diesel at a concentration of 10 mg C/L. The treatment group test chambers were used to evaluate the test substance at concentration of approximately 10 mg C/L. The results indicated that the activated sludge inoculum was active, degrading the canola oil reference 99.9%. The average cumulative percent biodegradation for squalane was 64.7%. However, squalane may be considered inherently biodegradable because it reached 60% of TCO2, though not within a 10 -days window of reaching 10% TCO2.

Abstract  Computerized gas chromatography-mass spectrometry of biomarkers in crude oils of East Siberia (eastern Siberian Platform, Nepa-Botuobiya dome) permitted revealing different types of primary organic matter on the basis of biochemistry and deposition environment, which correspond to a number of successive oil and gas sources.

All commercial Upper Proterozoic and Lower Cambrian oils of the study region are rich in 12-13-monomethylalkanes, tricyclic heilanthanes, and homohopane C-35 as compared with lower homolog C-34. This oil family, apparently, originates From plankton- or bacteria-derived organic matter buried in anoxic basins favorable for preservation of homohopane, among Riphean and Vendian carbonate, carbonate-argillaceous (as evidenced by scarce or absent diasteranes), and carbonaceous silts on the passive margin of the Siberian craton.

The Upper Permian and Mesozoic oils of the Vilyui basin show fairly high contents of diasteranes and rearranged hopanes (17 alpha(H)-diahopane and 18 alpha(H)-norneohopane), possibly originated from bacterial precursors which were oxidized and rearranged by acidic clay catalysis. The presence of diasteranes and diahopane attests to terrigenous (and possibly, coaliferous) source rock deposited, mast likely, in Permian fluvial, lacustrine, and marshy environments.

Considerable amounts of gammacerane, squalane, and pregnane in the Permian oils of the Yuzhno-Tigyanskoe deposit (Anabar-Khatanga saddle) are indicative of hypersaline environment of source-rock deposition. The oil may have been genetically related to Devonian salt-bearing deposition of the Lena-Anabar basin.

Abstract  Direct configurational-bias Monte Carlo simulations in the Gibbs ensemble have been used to determine the vapor-liquid coexistence curves and critical points of three C30H62 isomers: n-triacontane (T-c = 851 K, rho(c) = 0.202 g cm(-3)), 11-nonylheneicosane (T-c = 835 K, rho(c) = 0.208 g cm(-3)), and 2,6,10,15,19,23-hexamethyltetracosane, also called 'squalane' (T-c = 807 K, rho(c) = 0.244 g cm(-3)). The calculations show that the molecular shape can have a substantial influence on the phase diagrams of isomeric alkanes and that, in particular, squalane deviates significantly from the principle of corresponding states. (C) 1997 Elsevier Science B.V.

Abstract  Coupled-decoupled configurational-bias Monte Carlo (CD-CBMC) simulations in the Gibbs ensemble were carried out to determine the vapor-liquid coexistence curves for n-triacontane and 2,6,10,15,19,23-hexamethyltetra-cosane (squalane). The transferable potentials for phase equilibria-united atom (TraPPE-UA) force field was used for these simulations. The simulated systems consisted of 200 molecules and the production periods extended to 100,000 Monte Carlo cycles, a system size about twice as large and a simulation length about one order of magnitude longer than used in previous simulations, The simulation results are in satisfactory agreement with the available experimental data. Examination of the coexistence curves in reduced units for the two triacontane isomers and for n-octane and 2,5 -dimethylhexane shows that both molecular weight and branching can lead to deviations from the principle of corresponding states. Analysis of the molecular structures in the vapor and liquid phases points to a partial collapse (self-solvation) of the triacontane isomers as the likely origin of the deviations from the principle of corresponding states. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract  Percutaneous absorption of ethyl-alcohol (64175), perhydrosqualene (111013), and p-cymene (99876) was investigated. Male albino-mice were treated topically with 0.1 milliliter of radio labeled solutions of one of the test agents. In some tests with ethyl-alcohol and perhydrosqualene, the stratum corneum was removed before treatment. At selected times, the skin was removed and analyzed for radioactivity. Absorption rates were 10.5 and 0.12 nanomoles per square centimeter per minute for ethyl-alcohol and perhydrosqualene, respectively, for nonabraded skin. When the stratum corneum was removed, ethyl-alcohol penetration rate increased to 200 nanomoles per square centimeter per minute, but the rate for perhydrosqualene did not change. The penetration rate of p-cymene was 32 nanomoles per square centimeter per minute over 1 hour. The authors conclude that dermal absorption is affected by the epidermal barrier and the removal capacity of the blood. The liposolubility of the agent also affects its penetration through the epidermal stratum.

Abstract  Absorption, distribution, and release of squalane were studied in rainbow trout fed a diet containing 0.05% of this alkane. Estimated squalane absorption was about 40% of the dose. After three months of exposure, the residues in the whole body reached a steady equilibrium value of about 16- 18 micrograms/g. The most pronounced deposition occurred in the liver (1671 micrograms/g after 10 months), while the concentration of squalane in the adipose tissue was below 2 micrograms/g. During the depuration period, half of the contaminated trout were fed a squalane-free diet, while the others were starved. After two months, the body burden amounted to 65% and 80% of the alkane previously accumulated in starved and fed trout, respectively. In the starved group, 43% of the squalane initially stored in the liver was lost, whereas the loss in the fed fish liver was 52%. These results were compared with existing data on other alkanes. (Author 's abstract)

Abstract  An alkane-degrading bacterium, designated GTI MVAB Hex1(T), was isolated from chronically crude oil-contaminated soil from an oilfield in southern Illinois. The isolate grew very weakly or not at all in minimal or rich media without hydrocarbons. Straight-chain aliphatic hydrocarbons, such as hexadecane and heptadecane, greatly stimulated growth; shorter-chain (

Abstract  A new graphitized carbon black (Carbograph 5) with a specific surface area (560 m(2) g(-1)) greater than those of commercially available graphitized carbons was studied by gas chromatography to determine the enthalpy, entropy, and free energy of adsorption of a series of alkanes (C-2-C-6) The adsorption properties were also investigated by considering changes in the isosteric heats and entropies of adsorption when a nonpolar stationary phase (squalane) was added to the adsorbent. The data obtained are discussed and compared with literature values for other graphitized carbon blacks.

Abstract  The critical temperature and pressure of squalane (2,6,10,15,19,23-hexamethyltetracosane) have been measured using the pulse-heating method. Residence times are from 0.03 to 1 ms. The experimental critical properties are compared with the results of measurement by a flow method, computer-simulation data, and the values calculated by the group-contribution methods. The critical temperature of squalane is about 2.5% lower and the critical pressure is 10% higher than those of its linear isomer-n-triacontane. (c) 2005 Elsevier B.V. All rights reserved.

Abstract  The heterogeneous reaction of hydroxyl radicals with chemically reduced organic aerosol comprised of either squalane or bis(2-ethylhexyl) sebacate are used as model systems to examine how cloud condensation nuclei (CCN) activity evolves with photochemical oxidation. Over the course of the reaction, the critical super-saturation evolves both by the formation of new oxygen functional groups and by changes in aerosol size through the formation of gas phase reaction products. A statistical model of the heterogeneous reaction reveals that it is the formation, volatilization, solubility, and surface activity of many generations of oxidation products that together control the average changes in aerosol hygroscopicity. The experimental observations and model demonstrate the importance of considering the underlying population or subpopulation of species within a particle and how they each uniquely contribute to the average hygroscopicity of a multi-component aerosol. To accurately predict changes in CCN activity upon oxidation requires a reduction in the surface tension of the activating droplet by a subpopulation of squalane reaction products. These results provide additional evidence that surface tension-concentration parameterizations based on macroscopic data should be modified for microscopic droplets.

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  Pyrethroides are an analogous substance group to one of the oldest known, naturally occuring insecticides pyrethrum and have replaced a number of pesticides such as Lindan, DDT and PCP on the market. Biocides are more persistent indoors than in nature, which could lead to permanent health hazards for the people concerned. Within a few days after application pyrethroides are rarely detected in room air but can be traced for a long time on textiles, furniture and in dust particles (3, 8). The investigation results of approx. 100 analyses from dust and carpet samples show that approx. 1/3 of these samples arc positive for at least one pyrcthroidc and contain a concentration of > 2 mg substance per kg sample. The evaluation of 35 air samples taken from rooms where substances containing pyrethroides had been used at least a month prior to the investigation (the samples were sampled on active charcoal or Chromosorb) showed that pyrethroides could no longer be traced above the detection limit of 0.05-0.1 pg/m3. We therefore think that when investigating a contamination of rooms by biocides it is more advisable to determine pyrcthroides and its synergists in the suspended dust portion and corresponding dust sample rather than analysing air by adsorption to active charcoal, Chromosorb or other carrier materials. From the observed concentrations of biocides one could conclude that in an indoor setting secondary contamination by biocidcs plays a more significant role in the total-body-load than that of air contamination.

Abstract  We performed the rabbit skin closed patch tests about the sefety evaluation method of cosmetic ingredients. Test materials include propylene glycol, 1, 3-butylene glycol, glycerin, liquid paraffin, squalane and pristane. This study was performed in three cosmetic companies. The results were as follows. (1) Clear positive reactions were seen only with propylene glycol and pristane. (2) Among the three polyols tested, the score of propylene glycol was the highest in primary irritant.There is no difference between 1, 3-butylene glycol and glycerin, and they showed only weak reactions. Pristane was a strong irritant as expected, but liquid paraffin and squalane showed only weak reactions. (3) As to propylene glycol, strong reactins were seen only with 100% but not with 30% and 10 concentrations. (4) Average score of each materials was different, but the order of irritant was the same in three lavoratories.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. RRM HEXAMETHYLTETRACOSAN METABOLIC-DRUG ANTIDOTE-DRUG POLYCHLOROBIPHENYL POLYCHLORODIBENZOFURAN 3 METHYLCHOLANTHRENE TYPE TOXICITY FOOD CONSUMPTION GROWTH LIVER ENLARGEMENT THYMUS ATROPHY YUSHO RICE OIL

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.