Abstract  The dynamics of the gas-liquid interfacial reaction of the first electronically excited state of the oxygen atom, O((1)D), with the surface of a liquid hydrocarbon, squalane (C(30)H(62); 2,6,10,15,19,23-hexamethyltetracosane) has been studied experimentally. Translationally hot O((1)D) atoms were generated by 193 nm photolysis of a low pressure (nominally 1 mTorr) of N(2)O a short distance (mean = 6 mm) above a continually refreshed liquid squalane surface. Nascent OH (X(2)Π, v' = 0) reaction products were detected by laser-induced fluorescence (LIF) on the OH A(2)Σ(+)-X(2)Π (1,0) band at the same distance above the surface. The speed distribution of the recoiling OH was characterized by measuring the appearance profiles as a function of photolysis-probe delay for selected rotational levels, N'. The rotational (and, partially, fine-structure) state distributions were also measured by recording LIF excitation spectra at selected photolysis-probe delays. The OH v' = 0 rotational distribution is bimodal and can be empirically decomposed into near thermal (~300 K) and much hotter (~6000 K) Boltzmann-temperature components. There is a strong positive correlation between rotational excitation and translation energy. However, the colder rotational component still represents a significant fraction (~30%) of the fastest products, which have substantially superthermal speeds. We estimate an approximate upper limit of 3% for the quantum yield of OH per O((1)D) atom that collides with the surface. By comparison with established mechanisms for the corresponding reactions in the gas phase, we conclude that the rotationally and translationally hot products are formed via a nonstatistical insertion mechanism. The rotationally cold but translationally hot component is most likely produced by direct abstraction. Secondary collisions at the liquid surface of products of either of the previous two mechanisms are most likely responsible for the rotationally and translationally cold products. We do not think it likely, a priori, that they could be produced in the observed significant yield via a statistical insertion mechanism for a molecule the size of squalane embedded in a surrounding liquid surface.

Abstract  The residual fractions remaining after microbial degradation of diesel fuel, different deparaffinized raffinates and extracts from long-term contaminated soils were analyzed by liquid chromatography, gas chromatography, infrared spectrometry and mass spectrometry. The quantity of saturated hydrocarbons decreased after the microbial treatment, whereas the portion of polar compounds increased. The total content of aromatics changed only insignificantly. n-Paraffins < C26 were found to be no longer present in mineral oils degraded to exhaustion. Infrared spectrometry revealed oxygen compounds in the residues, mainly ketones, fatty acids and esters. Elementary analysis confirms the presence of nitrogen, oxygen and sulphur compounds in the degraded products. The gas chromatograms of high boiling oils, as well as of residues and extracts, consist mainly of a large base "envelope" (about 95% of the total area); thus gc/ms coupling reaches the limits of its applicability. However, mass spectrometry with direct inlet gives valuable information regarding hydrocarbon type analysis. The results revealed the preferable degradation of alkanes, 1-ring aliphatics and benzenes and an enrichment of condensed cycloaliphatics and aromatics. The latter compounds are known to be resistant to microbial attack.

Abstract  Gas liquid chromatography was used for analysis of a mixture of seven chlorinated hydrocarbons. Experiments were conducted using columns containing the solvents squalane (111024), di-n-butyl-tetrachlorophthalate (3015665) (DBTP), dinonyl-phthalate (84764) (DNP), tricresyl-phosphate (1330785) (TCP), and polyethylene-glycol (25322683) (PEG) as the stationary phase. Chlorinated hydrocarbons in the mixture tested were: 1-chloropropane (540545), tetrachloromethane (56235), dichloromethane (75092), 1,2-dichloroethane (107062), trichloroethylene (79016), cis-1,2-dichloroethylene (156592), and trichloromethane (67663). Carbon-tetrachloride (56235) was used as the reference solute. The extremes of polarity ran from squalane to PEG, from low to high. Combinations of packings with PEG together with squalane, DBTP, DNP, or TCP were evaluated. Order of elution using squalane was 1-chloropropane, tetrachloromethane, dichloromethane, trichloroethylene, cis-1,2-dichloroethylene, trichloromethane, and 1,2-dichloroethane. For squalane, the most difficult pair to separate was cis-1,2-dichloroethylene and trichloromethane. Efficiencies of the combined stationary phase packings were excellent, better than the optimum loaded squalane column. Analysis was completed in 50 percent of the time required with squalane for all solvent combinations except DBTP with PEG. Helium (7440597) or hydrogen (1333740) as carrier gas improved analysis time. The authors conclude that the window technique for the choice of optimum binary solvent composition is used to attain the shortest possible analysis time, rather than the minimum number of separation plates required for baseline separation.

Abstract  We performed several test methods for safety evaluation of cosmetic ingredients and products. Now we chose guinea pig closed patch test method. This study were performed in the 3 different laboratories. The test mamterials were propylene glycol, 1, 3-butylene glycol, glycerin, liquid paraffin, squalane, and pristane. We chose 100% propylene glycol and pristane as positive control, and distilled water as negative control. We performed this test with the same procedure in each laboratory. The results of this study were as following: (1) In three polyols, only 100% propylene glycol reacted but 1, 3-butylene glycol and glycerin showed no reactions. (2) In three hydrocarbons, the order of positive rate was pristane

Abstract  As the safety evaluation method of cosmetic ingredients and products, we performed human patch tests. The test materials were propylene glycol, 1, 3-butylene glyool, glycerirl, pristane, Iiquid paraffin and squalane We chose propylene glycol and pristane as positive control, and distilled water as negative control. The members of this study were 3 dermatologists in one dermatological office and 2 universities, and 9 researchersin the different cosmetic companies. We performed the tests with the same procedure in each laboratory We could obtain the same results about the order of test materialspositive rates. But test seasons, especially high temperature and high humidity influenced on the reactions of test materials. We have to take a control material when we are going to test the skin irritancy of some chemicals using closed patch test method.

Abstract  We investigated the stimulating effect of dietary fiber on fecal excretion of PCDF and PCDD stored in the rat body. Twenty-eight male rats (71-74g body weight) were orally administered with 1ml of the causal rice oil of Yusho desease. The rice oil was contaminated with 2, 3, 4, 7, 8-pentaCDF (691.4ng), 1, 2, 3, 4, 7, 8-hexaCDF (708.6ng), 1, 2, 3, 6, 7, 8-hexaCDF (128.4ng), 1, 2, 3, 7, 8-pentaCDD (7.2ng), 1, 2, 3, 6, 7, 8-hexaCDD (34.1ng), 1, 2, 3, 7, 8, 9-hexaCDD (20.1ng) and 1, 2, 3, 4, 6, 7, 8-heptaCDD (115.9ng). The animals were fed a control diet containing 10% cellulose for seven days. Twenty-eight rats consisting of four rats a group were housed and rats of each group were given a treatment diet containing 10% rice-bran-fiber (RBF), 5% cholestyramine, 10% RBF + 5% cholestyramine, 10% RBF + 5% cholestyramine + 1% squalane, 10% burdock-fiber, 10% corn-fiber and 10% soybean-fiber during a period from eight to twenty-one days. The remaining four rats served as controls. PCDF and PCDD in feces, liver, small intestine and gastrointestinal tract were analyzed by high resolution gas chromatography-mass spectrometry. PCDF level in small intestine of rats administered with RBF + cholestyramine showed a decrease of 40% over the level of control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Abstract  Here we report a new method for measuring the heterogeneous chemistry of sub-micron organic aerosol particles using a continuous flow stirred tank reactor. This approach is designed to quantify the real time heterogeneous kinetics, using a relative rate method, under conditions of low oxidant concentration and long reaction times that more closely mimic the real atmosphere than the conditions used in a typical flow tube reactor. A general analytical expression, which couples the aerosol chemistry with the flow dynamics in the chamber is developed and applied to the heterogeneous oxidation of squalane particles by hydroxyl radicals (OH) in the presence of O(2). The particle phase reaction is monitored via photoionization aerosol mass spectrometry and yields a reactive uptake coefficient of 0.51 +/- 0.10, using OH concentrations of 1-7 x 10(8) molecule cm(-3) and reaction times of 1.5-3 h. In general, this approach provides a new way to connect the chemical aging of organic particles measured at short reaction times and high oxidant concentrations in flow tubes with the long reaction times and low oxidant conditions in smog chambers and the real atmosphere.

Abstract  The gas-phase reaction of iodine atoms with hydrocarbon molecules is energetically unfavorable, and there is no direct evidence for iodinated product formation by either H abstraction or I addition reactions at ambient temperature. Here we consider the possible heterogeneous reaction of I atoms with submicrometer droplets composed of a saturated alkane, squalane (Sq), and an unsaturated alkene, squalene (Sqe). The investigations are performed in an atmospheric pressure photochemical flow tube reactor in conjunction with a vacuum ultraviolet photoionization aerosol mass spectrometer and a scanning mobility particle sizer. Squalane, a branched alkane, is unreactive toward I atoms within the signal-to-noise, and an upper limit of the effective reactive uptake coefficient is estimated to be γI(Sq) ≤ 8.58 × 10(–7). In contrast, the reaction of I atoms with unsaturated submicrometer squalene droplets results in observable iodinated squalene products. The effective reactive uptake coefficient of I atom with squalene particles is determined to be γI(Sqe) = (1.20 ± 0.52) × 10(–4) at an average I concentration of 1.5 × 10(14) molecules·cm(–3).

Abstract  The development of a non-toxic selective cytoprotective agent that preferentially protects normal tissues from chemotherapy toxicity, without protecting malignant tissues, is a major challenge in cancer chemotherapy research. The available cytoprotective agents are either toxic or lack selective cytoprotective activity. Here, we report the in vitro selective cytoprotective activity of squalene, an isoprenoid molecule with antioxidant properties. Normal human bone marrow (BM) derived colony-forming unit (CFU) growth was increased by squalene in a dose-dependent manner. Squalene (12.5-25 muM) treatment significantly protected the CFUs from cisplatin-induced toxicity; the protective effect was equivalent to reduced glutathione (GSH), a known cytoprotective agent. Squalene also increased the long-term survival of cisplatin-treated 4-week-old CFUs. Cisplatin-induced apoptosis of CFUs as measured by the TUNEL assay was reduced by squalene. To examine the squalene-induced protection of tumours, several neuroblastoma cell lines, including five MYCN-amplified cell lines, were grown in monolayers, as well as in anchorage-independent cultures, in the presence of squalene and cisplatin. Squalene did not protect the neuroblastoma (NBL) cell lines from cisplatin-induced toxicity. In addition, squalene did not protect the NBL cells from carboplatin, cyclophosphamide, etoposide and doxorubicin-induced toxicity. In conclusion, our results suggest that squalene has a selective in vitro cytoprotective effect on BM-derived haematopoietic stem cells that is equipotent to GSH. (C) 2003 Elsevier Ltd. All rights reserved.

Abstract  Symmetrical peaks, with sample size independent retention times, are obtained when alkanols are chromatographed in columns packed with alkane stationary phases coated on a deactivated solid obtained by coating Chromosorb W with Carbowax 20M, followed by thermal treatment in inert atmosphere and exhaustive extraction with methanol. Adsorption on the solid support/alkane interface is precluded by this deactivation method, but adsorption on the gas/alkane interface persists as a non-negligible contribution to solute retention. Retention volumes of ten alkanols with three to five carbon atoms were measured at five temperatures within the 30-50 degrees C interval in columns containing between 2 and 12 wt.% of squalane or of n-octadecane on the deactivated support. Partition and adsorption coefficients were obtained from the dependence of retention volumes on wt.% of stationary phase. Alkanols infinite dilution activity coefficients were calculated from partition coefficients; it is demonstrated that important errors are introduced on neglecting adsorption contributions. An indirect proof of consistency between calculated adsorption and partition parameters is given by comparing results obtained with both stationary phases. It is furthermore demonstrated that non-combinatorial contributions to the activity coefficients are independent of the alkane solvent.

Abstract  A biochemical method was employed to study the response of rabbit skin to isopropyl myristate, squalane, and decane. The results showed that decane damaged the skin so severely that the biosyntheses of lipids, RNA and DNA were reduced markedly for the first 3 days after application, but increased rapidly after that due to the repair. The effect of squalane was found to be weaker than that of isopropyl myristate, though both oils induced the stimulation of biosynthese in the epidermis. The magnitude of the biochemical effects of the 3 oils on the skin was increased in the order of squalane, isopropyl myristate and decane, which was consistent with the results of macroscopic and histological observations. From the profiles of the effects, it is postulated that the repairing processes are controlled by some feedback mechanisms.

Abstract  The dynamics of the interfacial reactions of O(P-3) with the hydrocarbon liquids squalane (C30H62, 2,6,10,15,19,23-hexamethyltetracosane) and squalene (C30H50, trans-2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22- hexaene) have been studied experimentally. Laser-induced fluorescence (LIF) was used to detect the nascent gas-phase OH products. The O(P-3) atoms are acutely sensitive to the chemical differences of the squalane and squalene surfaces. The larger exothermicity of abstraction from allylic C-H sites in squalene is reflected in markedly hotter OH rotational and vibrational distributions. There is a more modest increase in translational energy release. A larger fraction of the available energy is deposited in the liquid for squalene than for squalane, consistent with a more extensive geometry change on formation of the allylic radical co-product. Although the dominant reaction mechanism is direct, impulsive scattering, there is some evidence for OH being accommodated at both liquid surfaces, resulting in thermalised translation and rotational distributions. Despite the H-abstraction reaction being strongly favoured energetically for squalene, the yield of OH is substantially lower than for squalane. This is very likely due to competitive addition of O(P-3) to the unsaturated sites in squalene, implying that double bonds are extensively exposed at the liquid surface.

Abstract  Environmental investigation of the Early Cambrian is assessed through molecular fossils based from three core samples drilled in the Three Gorges area, South China. The core samples record environmental information dating from the earliest part of the Early Cambrian to nearly the end of the Early Cambrian, making this investigation unique from previous investigations because a more far-reaching temporal record is assessed. This record includes unusually high abundance of longer chain n-alkanes (LCA) around C-n(27), having been recognized in the earliest Cambrian strata. Based on no odd-even preference of the LCA and comparisons to hydrocarbons in cultured cells of microorganisms, the LCA may be derived from hydrocarbons of sulfate reducing bacteria. On the other hand, a phototrophic origin of the SCA is supported by a clear positive correlation with pristane. The relative abundance of LCA to SCA increased in the earliest Cambrian, suggesting predominance of sulfate reducers against phototrophs. This LCA abundance with simultaneous decrease of pristane/phytane may indicate a euxinic condition, where sulfate reducers remineralize organic carbon in the water column. This is consistent with the concomitant decrease of the delta C-13(carb) value probably due to a massive reoxidation of organic carbon. The inferred reducing condition is further supported by the enhanced appearance of squalane that could be derived from an Archeal lipid. Our results suggest the euxinia of the Yangtze platform in the earliest Cambrian that may relate to the emergence of the large nektonic animals which require sufficient level of free oxygen. (C) 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Using a data set for 39 base oils, formulated oil products and pure compounds it was demonstrated that there was a good positive relationship between biodegradation in CEC L-33-T-82 and mineralisation to CO2 in the modified Sturm test. A mathematical model was developed which described this correlation for most of the materials tested. One outlier from the model was di-iso tridecyl adipate (DITA), the well-degradable calibration oil for the CEC test. The measured mineralisation of DITA was much lower than that predicted by the model based on the compound's high biodegradability in the CEC test. A possible reason for this is given and the implications of this result discussed.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. The biodegradation of polycyclic aromatic hydrocarbon pollutants is constrained, in part, by their solid physical state and very low water solubility. Searching for ways to overcome these limitations, we isolated from soil a bacterium capable of growing on pyrene as a sole source of carbon and energy. Acid-fast stain, morphology, and fatty acid profile identified it as a Mycobacterium sp. In a mineral salts solution, the isolate mineralized 50% of a 250-mug/ml concentration of (14C) pyrene in 2 to 3 days. Detergent below the critical micelle concentration increased the pyrene mineralization rate to 154%, but above the critical micelle concentration, the detergent severely inhibited pyrene mineralization. The water-miscible solvent polyethylene glycol was inhibitory. The hydrophobic solvents heptamethylnonane, decalin, phenyldecane, and diphenylmethane were also inhibitory at several concentrations tested, but the addition of paraffin oil, squalene, squalane, tridecylcyc

Abstract  Different adjuvants were assessed for their role in conferring protection against the rodent malarial parasite P. berghei and compared with the classical Freund's complete adjuvant (FCA). Pretreatment of mice with trehalose dimycolate (TDM) mixed with antigen (Ag), sulpholipids (SL) mixed with Ag, muramyl dipeptide (MDP) alone, liposomes containing Ag and phosphomannoinositides (PIM) mixed with Ag were ineffective in conferring protection. However, MDP given with squalane (Sq) and Ag, MDP with incomplete Freund's adjuvant (IFA) and Ag, palmitoyl-MDP with Sq and Ag, aluminium hydroxide adsorbed Ag, and FCA with Ag were effective in conferring varying degrees of protection to mice. Complete protection in rats was obtained with MDP mixed with Sq and Ag, and FCA mixed with Ag, and a partial protection with liposomes containing Ag.

Abstract  Fossil stromatolites may reveal information about their hydrochemical palaeoenvironment, provided that assignment to a specific microbial community and a corresponding biogeochemical mechanism of formation can be made. Tithonian stromatolites of the Munder Formation at Thuste, north Germany, have traditionally been considered as formed by intertidal cyanobacterial communities. However, thin sections of the stromatolites show elongated angular traces of former gypsum crystals in a dense arrangement, but no algal or cyanobacterial filament traces. Moreover, high Fe(2+) and Mn(2+) contents, oxygen-isotope and sulphur-isotope ratios of carbonate-bound sulphates, and sulphurized hydrocarbon biomarkers of the stromatolitic carbonate indicate that CaCO(3) precipitation occurred near the oxic-anoxic interface as a result of intensive bacterial sulphur cycling rather than photosynthetic activity. Furthermore, anaerobic oxidation of methane by Archaea may have driven CaCO(3) precipitation in deeper parts of the biofilm community, as reflected by high concentrations of squalane with a strongly negative delta(13)C in conjunction with evaporite pseudomorphs showing extremely low delta(13)C(Carb) ratios. Consequently, the Thuste stromatolites are now interpreted as having initially formed by gypsum impregnation of biofilms. Subsequently, early Mg-calcitic calcitization within the biofilms occurred because of combined bacterial iron, manganese and sulphate reduction, with an increasing contribution of anaerobic oxidation of methane with depth. This model plausibly explains the prominent preservation of signals derived from oxygen-independent metabolic pathways, whereas virtually no geochemical record exists for an aerobic community that may, nevertheless, have prevailed at the stromatolite surface. Photic-zone stromatolites with a prominent signal of anaerobic oxidation of methane may be common in, and indicative of, oxygen-depleted sulphate-bearing environments with high rates of methane production, conditions that possibly were fulfilled at the Archaean to Proterozoic transition.

Abstract  An accurate description of the evolution of organic aerosol in the Earth's atmosphere is essential for climate models. However, the complexity of multiphase chemical and physical transformations has been challenging to describe at the level required to predict aerosol lifetimes and changes in chemical composition. In this work a model is presented that reproduces experimental data for the early stages of oxidative aging of squalane aerosol by hydroxyl radical (OH), a process governed by reactive uptake of gas phase species onto the particle surface. Simulations coupling free radical reactions and Fickian diffusion are used to elucidate how the measured uptake coefficient reflects the elementary steps of sticking of OH to the aerosol as a result of a gas-surface collision, followed by very rapid abstraction of hydrogen and subsequent free radical reactions. It is found that the uptake coefficient is not equivalent to a sticking coefficient or an accommodation coefficient: it is an intrinsically emergent process that depends upon particle size, viscosity, and OH concentration. An expression is derived to examine how these factors control reactive uptake over a broad range of atmospheric and laboratory conditions, and is shown to be consistent with simulation results. Well-mixed, liquid behavior is found to depend on the reaction conditions in addition to the nature of the organic species in the aerosol particle.

Abstract  In vivo irritant or corrosive effects of squalan were determined using EPA OPPTS 870.2500 guideline. The test item was applied on rabbit skin during 4h. The test sites were scored for dermal irritation at 60min after removal of wrappings and scored again at 24, 48 and 72h. The modied Primary Irritating Index is 0.22. In conclusion, in this study, the squalan is considered non-irritant.