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  Free-standing, ZnO surface decorated Cu nanoparticles of 1-3 nm size were obtained by sequential co-pyrolysis of [Cu(OCHMeCH2NMe2)2] and ZnEt2 in squalane in the absence of additional surfactants and proved to be highly active quasi homogeneous catalysts for methanol synthesis from CO and H2.

Abstract  We have used a squalane adsorbed C-18 phase as presumably a bulk-like stationary phase to secure a simple partition mechanism for solute retention in reversed phase liquid chromatography, and have evaluated the nondispersive (specific) functional group-solvent interaction separately by measuring the retention data of carefully selected solutes in 60/40, 70/30, and 80/20 (v/v%) methanol/water eluents at 25,30,35,40,45, and 50 degrees C. We have found that the absolute magnitude of the carbonyl group (in acetophenone)-mobile phase specific interaction enthalpy is much greater than that of the hydroxyl group (in phenol)-mobile phase specific interaction enthalpy. If we consider the overall differential solute transfer free energy for a pair of polar and nonpolar solutes of the same size, the entropic contribution is dominant for the BT/phenol pair, and the enthalpic contribution, for the ethylbenzene/acetophenone pair. On the other hand, for a pair of nonpolar solutes, the entropic contribution to the differential free energy of solute transfer is much lower than the enthalpic contribution, and the variation in the differential entropy of solute transfer with respect to mobile phase composition is much smaller than the variation in the differential enthalpy, too.

Abstract  The kinetics of the three-phase methanol synthesis over a commercial Cu-Zn-Al2O3 catalyst were studied in an apolar solvent, squalane and a polar solvent, tetraethylene glycol dimethylether (TEGDME). Experimental conditions were varied as follows: P = 3.0-5.3 MPa, T = 488-533 K and Phi(vG)/w =7.5 x 10(-3)-8 x 10(-3) Nm(3) s(-1) kg(cat)(-1). The nature of the slurry-liquid influences the activation energy and the kinetic rate constant by interaction between adsorbed species and solvent and by competitive adsorption of the solvent on the catalyst surface. The rate of reaction to methanol observed in TEGDME appeared to be about 10 times lower than in squalane. TEGDME reduces the reaction rate, which is a disadvantage for its use as a solvent. (C) 1999 Elsevier Science B.V. All rights reserved.

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  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  Chlorine species used as disinfectants in tap water have a deteriorating effect on many materials including polyethylene. There are only very few scientific reports on the effect on polyethylene pipes of water containing chlorine dioxide. Medium-density polyethylene pipes stabilized with hindered phenol and phosphite antioxidants were pressure tested with water containing 4 ppm chlorine dioxide at 90 degrees C and pH = 6.8 as internal medium. The stabilizers were rapidly consumed towards the inner pipe wall; the rate of consumption was four times greater than in chlorinated water (4 ppm, pH = 6.8) at the same temperature. The depletion of stabilizer occurred far into the pipe wall. A supplementary study on a polymer analogue (squalane) containing the same stabilizer package showed that the consumption of the phenolic antioxidant was 2.5 times faster when exposed water containing chlorine dioxide than on exposure to chlorinated water. The subsequent polymer degradation was an immediate surface reaction. It was confirmed by differential scanning calorimetry, infrared spectroscopy and size exclusion chromatography that in the surface layer which came into contact with the oxidising medium, the amorphous component of the polymer was heavily oxidized leaving a highly crystalline powder with many carboxylic acid chain ends in extended and once-folded chains. Scanning electron microscopy showed that propagation of cracks through the pipe wall was assisted by polymer degradation. (C) 2011 Elsevier Ltd. All rights reserved.

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  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 factors influencing the separation of monosubstituted phenols on silicone oil, poly(ethylene glycol) (1500), Apiezon L + Bentone 34, squalane, Versamide and diethylhexyl sebacate are discussed. Specific retention volumes, height equivalent to a theoretical plate and thermodynamic quantities are reported. Diethylhexyl sebacate and Versamide are selective for quantitative separation of all the isomers studied.

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 calculation of retention times, retention indices, and partition constants is a long sought-after goal for theoretical studies in gas chromatography. Although advances in computational chemistry have improved our understanding of molecular interactions, little attention has been focused on chromatography, let alone calculations of retention properties. Configurational-bias Monte Carlo simulations in the Gibbs ensemble have been used to calculate single and multi-component phase diagrams for a variety of hydrocarbon systems. Transferable force fields for linear and branched alkanes have been derived from these simulations. Using calculations for helium/n-heptane/n-pentane systems, it is demonstrated that this approach yields very precise partition constants and free energies of transfer. Thereafter, the partitioning of linear and branched alkane solutes (with five to eight carbon atoms) between a squalane liquid phase and a helium vapor phase is investigated. The Kovats retention indices of the solutes are calculated directly from the partition constants.

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  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  We synthesized new cationic lipids, analogue to N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and 1,2-dimyristyloxypropyl-3-dimethyl-hydroxyethylammonium bromide (DMRIE), in order to compare those containing a dodecyl chain with those having a relatively long chain with two or five double bonds, such as squalenyl and dihydrofarnesyl derivatives, or complex saturated structures, such as squalane derivatives. The fusogenic helper lipid dioleoylphosphatidylethanolamine (DOPE) was added to cationic lipids to form a stable complex. Liposomes composed of 50:50 w/w cationic lipid/DOPE were prepared and incubated with plasmidic DNA at various charge ratios and the diameter and zeta potential of the complexes were measured. The surface charge of the DNA/lipid complexes can be controlled by adjusting the cationic lipid/DNA ratio. Finally, we tested the in vitro transfection efficiency of the cationic lipid/DNA complexes using different cell lines. The transfection efficiency was highest for the dodecyloxy derivative containing a single hydroxyethyl group in the head, followed by the dodecyloxy and the farnesyloxy trimethylammonium derivatives. Instead the C27 squalenyl and C27 squalanyl derivatives resulted inactive.

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.