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.

Abstract  Biodegradability was conducted according to OECD guideline n°301B. Sample biodegradability was equal to 55.9% after 28 days and 66.3% after 36 days.

Abstract  Compatibility between oligomers and polymers was systematically assessed using differential scanning calorimetry (DSC) and was correlated with similarity in saturation and solubility parameter. These measurements enabled validation of detailed volume of mixing calculations using Statistical Association Fluid Theory (SAFT-γ Mie) and molecular dynamics (MD) simulations, which can be used to predict behaviour beyond the experimentally accessible conditions. These simulations confirmed that squalane is somewhat more compatible with poly(isoprene), "PI" than poly(butadiene), "PB", and further enabled prediction of the temperature dependence of compatibility. Surface and interfacial segregation of a series of deuterated oligomers was quantified in rubbery polymer films: PI, PB and hydrogenated poly(isoprene) "hPI". A striking correlation was established between surface wetting transition and mixtures of low compatibility, such as oligo-dIB in PB or PI. Segregation was quantified normal to the surface by ion beam analysis and neutron reflectometry and in some cases lateral segregation was observable by AFM. While surface segregation is driven by disparity in molecular weight in highly compatible systems this trend reverses as critical point is approached, and surface segregation increases with increasing oligomer molecular weight.

Abstract  Mannosylerythritol lipids (MELs) are secreted by yeasts and are promising glycolipid biosurfactants. In our study on the non-aqueous phase behaviors of MEL homologues, we found that MEL-D (4-O-[2',3'-di-O-alka(e)noyl-β-D-mannopyranosyl]-(2R,3S)-erythritol) forms aggregates in decane. The microscopic observation and the X-ray scattering measurement of these aggregates revealed that they are reverse vesicles that consist of bilayers whose hydrophilic domains are located in the interior of the bilayers. In addition, MEL-D formed reverse vesicles without co-surfactants and co-solvents in various oily solutions, such as n-alkanes, cyclohexane, squalane, squalene, and silicone oils at a concentration below 10 mM. This is the first report on the reverse vesicle formation from biosurfactants.

Abstract  The gel relaxation times of two different poly[styrene-b-(ethylene-altpropylene)-b-styrene] (SEPS) ABA triblock copolymers in squalane at various concentrations has been measured by Theology. These relaxation times were compared with the results of previous time-resolved small-angle neutron scattering (TR-SANS) experiments, which measured chain exchange kinetics in SEP diblock and SEPS triblock micelles in squalane. The gels relaxed up to four orders of magnitude faster than expected based on the chain exchange measurements of equivalent diblock polymers. By accounting for two factors a bias toward shorter end-block lengths in the gel relaxation, and a reduction in the energy barrier to chain pullout caused by the triblock architecture a model is constructed that reconciles the surprisingly short gel relaxation times with the chain exchange times measured via TR-SANS.

Abstract  This study presents first results on angle-resolved, inelastic collision dynamics of thermal and hyperthermal molecular beams of NO at gas-liquid interfaces. Specifically, a collimated incident beam of supersonically cooled NO (2Π1/2, J = 0.5) is directed toward a series of low vapor pressure liquid surfaces ([bmim][Tf2N], squalane, and PFPE) at θinc = 45(1)°, with the scattered molecules detected with quantum state resolution over a series of final angles (θs = -60°, -30°, 0°, 30°, 45°, and 60°) via spatially filtered laser induced fluorescence. At low collision energies [Einc = 2.7(9) kcal/mol], the angle-resolved quantum state distributions reveal (i) cos(θs) probabilities for the scattered NO and (ii) electronic/rotational temperatures independent of final angle (θs), in support of a simple physical picture of angle independent sticking coefficients and all incident NO thermally accommodating on the surface. However, the observed electronic/rotational temperatures for NO scattering reveal cooling below the surface temperature (Telec < Trot < TS) for all three liquids, indicating a significant dependence of the sticking coefficient on NO internal quantum state. Angle-resolved scattering at high collision energies [Einc = 20(2) kcal/mol] has also been explored, for which the NO scattering populations reveal angle-dependent dynamical branching between thermal desorption and impulsive scattering (IS) pathways that depend strongly on θs. Characterization of the data in terms of the final angle, rotational state, spin-orbit electronic state, collision energy, and liquid permit new correlations to be revealed and investigated in detail. For example, the IS rotational distributions reveal an enhanced propensity for higher J/spin-orbit excited states scattered into near specular angles and thus hotter rotational/electronic distributions measured in the forward scattering direction. Even more surprisingly, the average NO scattering angle (⟨θs⟩) exhibits a remarkably strong correlation with final angular momentum, N, which implies a linear scaling between net forward scattering propensity and torque delivered to the NO projectile by the gas-liquid interface.

Abstract  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.

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  The dependence of the adjusted retention volume, VD, in gas liquid chromatograph on carrier gas flow rate, u, was stu8ied for several solutes using 5% squalane statioyary phase and 40-60 mesh fluoropak 8 as support. In all cases VD increases in a stypwise fashion as u increases. In each step the rate of increase of Vplis intitially high, but gradually decreases until VD levels off. V R is further shown to be directly proportional to n, he number of adsorbant sites in the stationary phase recognised by a single analyte molecule during its paysage through the column and, based on this relationship between VD and n, a new model of gas chromatography applying the kinetics 6f gaseous adsorption at surfaces, and whose predictions are consistent with the experimental data above, is presented.

Abstract  The antibody and cell mediated immune responses induced by BHV-1 were analysed in cattle after vaccination and challenge exposure to the virulent strain LA of BHV-1. Animals were vaccinated intramuscularly (IM) with inactivated virus vaccines against BHV-1 containing either a water in mineral oil adjuvant (W/O), a water in mineral oil adjuvant plus Avridine (W/O O + Avridine) or sulfolipo-cyclodextrin in squalane in-water emulsion (SL-CD/S/W). No significant differences were registered in the antibody response induced by the three evaluated vaccines. However, the BHV-1 specific cell-mediated immunite response was stronger and appeared earlier when SL-CD/S/W was included in the formulation. The efficacy of the vaccines was also evaluated after intranasal challenge of the calves with a virulent BHV-1 LA strain. Animals vaccinated with SL-CD/S/W had reduced virus excretion and clinical symptoms compared with the mock-vaccinated animals. Comparison of levels of BHV-1 specific IgG2 and IgG1 with virus shedding revealed that, regardless of the adjuvant administered, animals showing BHV-1 specific IgG2/IgG1 ratios higher than 1 were those with a significant lower number of individuals shedding virus. Additionally, animals vaccinated with SL-CD/S/W presented no post-vaccinal reactions. These factors, combined with the higher efficacy and the ease of manipulation of the biodegradable oil, makes the vaccine formulated with this new adjuvant an important contribution for the veterinary vaccines industry. (C) 2000 Elsevier Science Ltd. All rights reserved.

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  Active oxygen has been implicated in the pathogenesis of Parkinson's disease (PD); therefore, antioxidants have attracted attention as a potential way to prevent this disease. Squalene, a natural triterpene and an intermediate in the biosynthesis of cholesterol, is known to have active oxygen scavenging activities. Squalane, synthesized by complete hydrogenation of squalene, does not have active oxygen scavenging activities. We examined the effects of oral administration of squalene or squalane on a PD mouse model, which was developed by intracerebroventricular injection of 6-hydroxydopamine (6-OHDA). Squalene administration 7 days before and 7 days after one 6-OHDA injection prevented a reduction in striatal dopamine (DA) levels, while the same administration of squalane enhanced the levels. Neither squalene nor squalane administration for 7 days changed the levels of catalase, glutathione peroxidase, or superoxide dismutase activities in the striatum. Squalane increased thiobarbituric acid reactive substances, a marker of lipid peroxidation, in the striatum. Both squalane and squalene increased the ratio of linoleic acid/linolenic acid in the striatum. These results suggest that the administration of squalene or squalane induces similar changes in the composition of fatty acids and has no effect on the activities of active oxygen scavenging enzymes in the striatum. However, squalane increases oxidative damage in the striatum and exacerbates the toxicity of 6-OHDA, while squalene prevents it. The effects of squalene or squalane treatment in this model suggest their possible uses and risks in the treatment of PD.

Abstract  The work in part 6 of this series (J. Phys. Chem. A 2009, 113, 4930), addressing the task of separating the effects of Heisenberg spin exchange (HSE) and dipole-dipole interactions (DD) on electron paramagnetic resonance (EPR) spectra of nitroxide spin probes in solution, is extended experimentally and theoretically. Comprehensive measurements of perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (pDT) in squalane, a viscous alkane, paying special attention to lower temperatures and lower concentrations, were carried out in an attempt to focus on DD, the lesser understood of the two interactions. Theoretically, the analysis has been extended to include the recent comprehensive treatment by Salikhov (Appl. Magn. Reson. 2010, 38, 237). In dilute solutions, both interactions (1) introduce a dispersion component, (2) broaden the lines, and (3) shift the lines. DD introduces a dispersion component proportional to the concentration and of opposite sign to that of HSE. Equations relating the EPR spectral parameters to the rate constants due to HSE and DD have been derived. By employing nonlinear least-squares fitting of theoretical spectra to a simple analytical function and the proposed equations, the contributions of the two interactions to items 1-3 may be quantified and compared with the same parameters obtained by fitting experimental spectra. This comparison supports the theory in its broad predictions; however, at low temperatures, the DD contribution to the experimental dispersion amplitude does not increase linearly with concentration. We are unable to deduce whether this discrepancy is due to inadequate analysis of the experimental data or an incomplete theory. A new key aspect of the more comprehensive theory is that there is enough information in the experimental spectra to find items 1-3 due to both interactions; however, in principle, appeal must be made to a model of molecular diffusion to separate the two. The permanent diffusion model is used to illustrate the separation in this work. In practice, because the effects of DD are dominated by HSE, negligible error is incurred by using the model-independent extreme DD limit of the spectral density functions, which means that DD and HSE may be separated without appealing to a particular model.

Abstract  Experimental and numerical studies have been performed to establish how liquid and vapor distributions of flammable liquids within an insulation matrix and that of residual oxygen may affect the propensity for spontaneous ignition to occur when the insulation is exposed to elevated external temperatures.

The experiments were performed at temperatures up to 500 K when squalane, which is involatile, and tetralin, which is volatile, were doped into 5-cm cubes of a microporous material. The center temperature, oxygen concentration, and liquid mass loss were measured continuously The distinctions between evaporative loss without exothermic oxidation of a volatile fluid and the exothermic oxidation leading to ignition of an involatile fluid were clearly established. There were two principal features. First, oxygen is never excluded completely from the pores of the insulation material even when the block is exposed to an external temperature equal to the normal boiling point of the fluid. In fact, a "plateau temperature," which is below the bailing point, is established at the center of the block, and this is maintained until virtually all evaporation has ceased. Second, only very small proportions of oxygen are consumed during the induction time leading to thermal ignition. Complete consumption occurs within the porous structure only at an advanced stage of combustion.

Numerical simulations were made including the chemical reaction, liquid evaporation, both fuel vapor and oxygen diffusion, and thermal transport through the block. A novel approach to the kinetic representation is used. The subtle interactions between heat and mass transport are explored, and the model is used to predict which of a series of liquid alkanes may be susceptible to ignition if they were to leak into hot lagging materials.

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  Quenching of the recombination fluorescence by an external electric field was investigated in hexane, tetradecane, and squalane solutions of p-terphenyl and 2.5-diphenyloxazole irradiated with X-rays. The kinetics of the recombination fluorescence I(E, t) was measured in a nanosecond time scale and the quenching-efficiency curves Q(E, t) = 1 - I(E, t)/I(0, t) were plotted. The dependence Q(E, t) was shown to have the specific character Q(E, t) = f(pt), where p = AE(2)D/r(c)(2). Here A is a constant dependent on the initial-distance distribution function of the charges, E is the electric field strength, D is a mutual diffusion coefficient of the recombining ions, and r(c), is the Onsager radius. The quadratic dependence of the parameter p on the electric field strength was shown to be a consequence of the diffusion-controlled reaction of ion recombination.

Abstract  Plasma-polymerized acetylene films are excellent primers for bending natural rubber (NR) to steel substrates. The purpose of this research was to determine the mechanisms responsible for adhesion at the NR/primer interface. Interactions between natural rubber and plasma-polymerized acetylene films were simulated using model systems containing squalene (C30H50) or squalane (C30H62), carbon black, sulfur, stearic acid, N, N-dicyclohexyl-benzothiazole-sulfenamide (DCBS), cobalt naphthenate, and diaryl-p-phenylene-diamine. Analysis of plasma-polymerized acetylene films before and after reaction with model rubber systems was accomplished using Fourier transform infrared spectroscopy (FTIR). The importance of the unsaturation in the reaction was demonstrated by comparing the behavior of the two model systems. In the squalane-based system, squalane itself was stable throughout the reaction, with only a slight reaction with the antioxidant and sulfur. No significant reactions occurred between the squalane-based model system and plasma-polymerized acetylene films with the exception of slight adsorption of antioxidant and zinc and/or cobalt stearate onto the films.

Reactions between plasma polymerized primers and the squalene-based model system were complex. Squalene itself went through double-bond migration. ZnO and cobalt naphthenate reacted with stearic acid to form zinc and cobalt stearates which then reacted with DCBS and sulfur to form zinc and cobalt accelerator perthiomercaptide complexes. These complexes reacted with squalene and with the primer film to form accelerator terminated, perthiomercapride pendant groups and, eventually, short polysulfide crosslinks. Since there was little reaction of squalane-based model rubber compounds with plasma polymerized primers but extensive reaction of squalene-based models, it was concluded that an intermediate formed in that reaction was responsible for crosslinking between squalene and the primer in the model system and for adhesion at the NR/primer interface in an actual bond.

Abstract  When beta-ionone-in-water emulsions are mixed with squalane-in-water emulsions, the slightly water-soluble, mobile beta-ionone undergoes mass transfer to the drops of highly water-insoluble, immobile oil squalane. We have investigated this compositional ripening process for emulsions stabilised either by particles or by surfactant molecules. For particle-stabilised emulsions, the swelling of the squalane-containing drops triggers droplet coalescence which causes the final swollen droplet radius to be proportional to the swelling ratio to the power of 1. Surfactant-stabilised emulsions swell without coalescence which causes the final droplet radius to be proportional to the swelling ratio to the power 1/3. Addition of excess, non-adsorbed particles to the particle-stabilised emulsions suppresses the swelling-triggered coalescence and causes a switchover from particle to surfactant behaviour.