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Sample records for alkyl chain increases

  1. Vibrational Spectroscopic Study of Imidazolium Dicationic Ionic Liquids: Effect of Cation Alkyl Chain Length

    NASA Astrophysics Data System (ADS)

    Moumene, T.; Belarbi, E. H.; Haddad, B.; Villemin, D.; Abbas, O.; Khelifa, B.; Bresson, S.

    2016-05-01

    Two new dicationic ionic liquids were synthesized: bis-methyl imidazolium methylidene hexafluorophosphate [M(CH2)IM2 +][2PF 6 - ] and bis-methyl imidazolium propylidene hexafluorophosphate [M(CH2)3IM2 +][2PF 6 - ]. Their structures were identified by H, C, P, F NMR, FTIR/ATR, and FT-Raman spectroscopies in order to study the effect of cation alkyl chain length on vibration behaviors. Several changes were recorded, which were related to alkyl chain length. A frequency shift was observed in some modes while others remained insensitive. A greater number of peaks was found in the FTIR/ATR spectra and the FT-Raman spectra with increasing alkyl chain length, which indicated that chain length influences the N-C connection twisting. More peaks with strong intensity appeared for longer alkyl chain lengths.

  2. Vibrational Spectroscopic Study of Imidazolium Dicationic Ionic Liquids: Effect of Cation Alkyl Chain Length

    NASA Astrophysics Data System (ADS)

    Moumene, T.; Belarbi, E. H.; Haddad, B.; Villemin, D.; Abbas, O.; Khelifa, B.; Bresson, S.

    2016-05-01

    Two new dicationic ionic liquids were synthesized: bis-methyl imidazolium methylidene hexafluorophosphate [M(CH2)IM2 +][2PF{6/-}] and bis-methyl imidazolium propylidene hexafluorophosphate [M(CH2)3IM2 +][2PF{6/-}]. Their structures were identified by H, C, P, F NMR, FTIR/ATR, and FT-Raman spectroscopies in order to study the effect of cation alkyl chain length on vibration behaviors. Several changes were recorded, which were related to alkyl chain length. A frequency shift was observed in some modes while others remained insensitive. A greater number of peaks was found in the FTIR/ATR spectra and the FT-Raman spectra with increasing alkyl chain length, which indicated that chain length influences the N-C connection twisting. More peaks with strong intensity appeared for longer alkyl chain lengths.

  3. Immobilization of Lipases on Alkyl Silane Modified Magnetic Nanoparticles: Effect of Alkyl Chain Length on Enzyme Activity

    PubMed Central

    Wang, Jiqian; Meng, Gang; Tao, Kai; Feng, Min; Zhao, Xiubo; Li, Zhen; Xu, Hai; Xia, Daohong; Lu, Jian R.

    2012-01-01

    Background Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification. Methodology/Principal Findings Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18) modified Fe3O4 were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining. Conclusions/Significance The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for enzyme immobilization

  4. Interaction between DNA and Trimethyl-Ammonium Bromides with Different Alkyl Chain Lengths

    PubMed Central

    Cheng, Chao; Ran, Shi-Yong

    2014-01-01

    The interaction between λ—DNA and cationic surfactants with varying alkyl chain lengths was investigated. By dynamic light scattering method, the trimethyl-ammonium bromides-DNA complex formation was shown to be dependent on the length of the surfactant's alkyl chain. For surfactants with sufficient long alkyl chain (CTAB, TTAB, DTAB), the compacted particles exist with a size of ~60–110 nm at low surfactant concentrations. In contrast, high concentration of surfactants leads to aggregates with increased sizes. Atomic force microscope scanning also supports the above observation. Zeta potential measurements show that the potential of the particles decreases with the increase of surfactant concentration (CTAB, TTAB, DTAB), which contributes much to the coagulation of the particles. For OTAB, the surfactant with the shortest chain in this study, it cannot fully neutralize the charges of DNA molecules; consequently, the complex is looser than other surfactant-DNA structures. PMID:24574926

  5. The effect of the cation alkyl chain branching on mutual solubilities with water and toxicities.

    PubMed

    Kurnia, Kiki A; Sintra, Tânia E; Neves, Catarina M S S; Shimizu, Karina; Canongia Lopes, José N; Gonçalves, Fernando; Ventura, Sónia P M; Freire, Mara G; Santos, Luís M N B F; Coutinho, João A P

    2014-10-01

    The design of ionic liquids has been focused on the cation-anion combinations but other more subtle approaches can be used. In this work the effect of the branching of the cation alkyl chain on the design of ionic liquids (ILs) is evaluated. The mutual solubilities with water and toxicities of a series of bis(trifluoromethylsulfonyl)-based ILs, combined with imidazolium, pyridinium, pyrrolidinium, and piperidinium cations with linear or branched alkyl chains, are reported. The mutual solubility measurements were carried out in the temperature range from (288.15 to 323.15) K. From the obtained experimental data, the thermodynamic properties of the solution (in the water-rich phase) were determined and discussed. The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used to predict the liquid-liquid equilibrium. Furthermore, molecular dynamic simulations were also carried out aiming to get a deeper understanding of these fluids at the molecular level. The results show that the increase in the number of atoms at the cation ring (from five to six) leads to a decrease in the mutual solubilities with water while increasing their toxicity, and as expected from the well-established relationship between toxicities and hydrophobicities of ILs. The branching of the alkyl chain was observed to decrease the water solubility in ILs, while increasing the ILs solubility in water. The inability of COSMO-RS to correctly predict the effect of branching alkyl chains toward water solubility on them was confirmed using molecular dynamic simulations to be due to the formation of nano-segregated structures of the ILs that are not taken into account by the COSMO-RS model. In addition, the impact of branched alkyl chains on the toxicity is shown to be not trivial and to depend on the aromatic nature of the ILs. PMID:25119425

  6. The effect of the cation alkyl chain branching on mutual solubilities with water and toxicities

    PubMed Central

    Kurnia, Kiki A.; Sintra, Tânia E.; Neves, Catarina M. S. S.; Shimizu, Karina; Lopes, José N. Canongia; Gonçalves, Fernando; Ventura, Sónia P. M.; Freire, Mara G.; Santos, Luís M. N. B. F.; Coutinho, João A. P.

    2014-01-01

    The design of ionic liquids has been focused on the cation-anion combinations but other more subtle approaches can be used. In this work the effect of the branching of the cation alkyl chain on the design of ionic liquids (ILs) is evaluated. The mutual solubilities with water and toxicities of a series of bis(trifluoromethylsulfonyl)-based ILs, combined with imidazolium, pyridinium, pyrrolidinium, and piperidinium cations with linear or branched alkyl chains, are reported. The mutual solubility measurements were carried out in the temperature range from (288.15 to 323.15) K. From the obtained experimental data, the thermodynamic properties of the solution (in the water-rich phase) were determined and discussed. The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used to predict the liquid-liquid equilibrium. Furthermore, molecular dynamic simulations were also carried out aiming to get a deeper understanding of these fluids at the molecular level. The results show that the increase in the number of atoms at the cation ring (from five to six) leads to a decrease in the mutual solubilities with water while increasing their toxicity, and as expected from the well-established relationship between toxicities and hydrophobicities of ILs. The branching of the alkyl chain was observed to decrease the water solubility in ILs, while increasing the ILs solubility in water. The inability of COSMO-RS to correctly predict the effect of branching alkyl chains toward water solubility on them was confirmed using molecular dynamic simulations to be due to the formation of nano-segregated structures of the ILs that are not taken into account by the COSMO-RS model. In addition, the impact of branched alkyl chains on the toxicity is shown to be not trivial and to depend on the aromatic nature of the ILs. PMID:25119425

  7. Cracking of long-chain alkyl aromatics on USY zeolite catalysts

    SciTech Connect

    Corma, A. ); Miguel, P.J.; Orchilles, A.V. ); Koermer, G.S. )

    1992-05-01

    Long-chain alkyl aromatics are important precursors for FCC gasoline. It is well known that for short-chain alkyl aromatics like cumene the dominant cracking process is simple alkyl aryl cleavage. In contrast the authors have found that for long-chain alkyl aromatics like 1-phenylheptane, cracking over in situ USY catalysts is much more complex. Cracking in a long alkyl side chain results in a carbenium ion that isomerizes easily and gives self-alkylation of the aromatic ring. Self-alkylation produces coke precursors and heavy gasoline aromatics. Product selectivities vary with zeolite unit cell size in ways that are rationalized on the basis of decreasing acid site density and zeolite adsorption properties.

  8. Ultrasonic Relaxation Study of 1-Alkyl-3-methylimidazolium-Based Room-Temperature Ionic Liquids: Probing the Role of Alkyl Chain Length in the Cation.

    PubMed

    Zorębski, Michał; Zorębski, Edward; Dzida, Marzena; Skowronek, Justyna; Jężak, Sylwia; Goodrich, Peter; Jacquemin, Johan

    2016-04-14

    Ultrasound absorption spectra of four 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides were determined as a function of the alkyl chain length on the cation from 1-propyl to 1-hexyl from 293.15 to 323.15 K at ambient pressure. Herein, the ultrasound absorption measurements were carried out using a standard pulse technique within a frequency range from 10 to 300 MHz. Additionally, the speed of sound, density, and viscosity have been measured. The presence of strong dissipative processes during the ultrasound wave propagation was found experimentally, i.e., relaxation processes in the megahertz range were observed for all compounds over the whole temperature range. The relaxation spectra (both relaxation amplitude and relaxation frequency) were shown to be dependent on the alkyl side chain length of the 1-alkyl-3-methylimidazolium ring. In most cases, a single-Debye model described the absorption spectra very well. However, a comparison of the determined spectra with the spectra of a few other imidazolium-based ionic liquids reported in the literature (in part recalculated in this work) shows that the complexity of the spectra increases rapidly with the elongation of the alkyl chain length on the cation. This complexity indicates that both the volume viscosity and the shear viscosity are involved in relaxation processes even in relatively low frequency ranges. As a consequence, the sound velocity dispersion is present at relatively low megahertz frequencies. PMID:26982480

  9. The horizontal transfer of antibiotic resistance genes is enhanced by ionic liquid with different structure of varying alkyl chain length

    PubMed Central

    Wang, Qing; Lu, Qian; Mao, Daqing; Cui, Yuxiao; Luo, Yi

    2015-01-01

    Antibiotic resistance genes (ARGs) have become a global health concern. In our previous study, an ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) had been proven to facilitate the dissemination of ARGs in the environment. However, enhanced alkyl group chain length or the substitution of alkyl groups with the cation ring corresponded with increased antimicrobial effects. In this study, we investigated how different structures of ILs with 4, 6, and 8 C atoms in the longer alkyl chain on the imidazolium cations facilitated the dissemination of ARGs. The promotion of plasmid RP4 transfer frequency decreased with [CnMIM][BF4] increasing the alkyl chain length from 4 carbon atoms to 8 carbon atoms on the imidazolium cations, which is observed with [BMIM][BF4] (n = 4, 5.9 fold) > HMIM][BF4] (n = 6, 2.2 fold) > [OMIM][BF4] (n = 8, 1.7 fold). This illustrates that [CnMIM][BF4] with increasing the alkyl chain length exert decreasing ability in facilitating plasmid RP4 horizontal transfer, which is possibly related to IL-structure dependent toxicity. The IL-structure dependent plasmid RP4 transfer frequency was attributable to bacterial cell membrane permeability weaken with increasing alkyl chain length of [CnMIM][PF4], which was evidenced by flow cytometry. In freshwater microcosm, [CnMIm][BF4] promoted the relative abundance of the sulI and intI genes for 4.6 folds, aphA and traF for 5.2 folds higher than the untreated groups, promoting the propagation of ARGs in the aquatic environment. This is the first report that ILs with different structure of varying alkyl chain length facilitate horizontal transfer of plasmid RP4 which is widely distributed in the environment, and thus add the adverse effects of the environmental risk of ILs. PMID:26379641

  10. Alkyl Chain Length and Temperature Effects on Structural Properties of Pyrrolidinium-Based Ionic Liquids: A Combined Atomistic Simulation and Small-Angle X-ray Scattering Study

    SciTech Connect

    Li, Song; Bañuelos, José Leobardo; Guo, Jianchang; Anovitz, Lawrence; Rother, Gernot; Shaw, Robert W.; Hillesheim, Patrick C.; Dai, Sheng; Baker, Gary A.; Cummings, Peter T.

    2011-12-21

    Molecular dynamics (MD) simulations of 1-alkyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([CnMPy][Tf₂N], n = 3, 4, 6, 8, 10) were conducted using an all-atom model. Radial distribution functions (RDF) were computed and structure functions were generated to compare with new X-ray scattering experimental results, reported herein. The scattering peaks in the structure functions generally shift to lower Q values with increased temperature for all the liquids in this series. However, the first sharp diffraction peak (FSDP) in the longer alkyl chain liquids displays a marked shift to higher Q values with increasing temperature. Alkyl chain-dependent ordering of the polar groups and increased tail aggregation with increasing alkyl chain length were observed in the partial pair correlation functions and the structure functions. The reasons for the observed alkyl chain-dependent phenomena and temperature effects were explored.

  11. Alkyl Chain Length and Temperature Effects on Structural Properties of Pyrrolidinium-Based Ionic Liquids: A Combined Atomistic Simulation and Small-Angle X-ray Scattering Study.

    SciTech Connect

    Li, Song; Banuelos, Jose Leo; Guo, Jianchang; Anovitz, Lawrence {Larry} M; Rother, Gernot; Shaw, Robert W; Hillesheim, Patrick C; Dai, Sheng; Baker, Gary A; Cummings, Peter T

    2011-01-01

    Molecular dynamics (MD) simulations of 1-alkyl-1-methylpyrrolidinium 12 bis(trifluoromethanesulfonyl)imide ([CnMPy][Tf2N], n = 3, 4, 6, 8, 10) were conducted 13 using an all-atom model. Radial distribution functions (RDF) were computed and structure 14 functions were generated to compare with new X-ray scattering experimental results, 15 reported herein. The scattering peaks in the structure functions generally shift to lower Q 16 values with increased temperature for all the liquids in this series. However, the first sharp 17 diffraction peak (FSDP) in the longer alkyl chain liquids displays a marked shift to higher Q 18 values with increasing temperature. Alkyl chain-dependent ordering of the polar groups and 19 increased tail aggregation with increasing alkyl chain length were observed in the partial pair 20 correlation functions and the structure functions. The reasons for the observed alkyl chain- 21 dependent phenomena and temperature effects were explored.

  12. The effect of the cation alkyl chain length on density and diffusion in dialkylpyrrolidinium bis(mandelato)borate ionic liquids.

    PubMed

    Filippov, Andrei; Taher, Mamoun; Shah, Faiz Ullah; Glavatskih, Sergei; Antzutkin, Oleg N

    2014-12-28

    The physicochemical properties of ionic liquids are strongly affected by the selective combination of the cations and anions comprising the ionic liquid. In particular, the length of the alkyl chains of ions has a clear influence on the ionic liquid's performance. In this paper, we study the self-diffusion of ions in a series of halogen-free boron-based ionic liquids (hf-BILs) containing bis(mandelato)borate anions and dialkylpyrrolidinium cations with long alkyl chains CnH2n+1 with n from 4 to 14 within a temperature range of 293-373 K. It was found that the hf-BILs with n = 4-7 have very similar diffusion coefficients, while hf-BILs with n = 10-14 exhibit two liquid sub-phases in almost the entire temperature range studied (293-353 K). Both liquid sub-phases differ in their diffusion coefficients, while values of the slower diffusion coefficients are close to those of hf-BILs with shorter alkyl chains. To explain the particular dependence of diffusion on the alkyl chain length, we examined the densities of the hf-BILs studied here. It was shown that the dependence of the density on the number of CH2 groups in long alkyl chains of cations can be accurately described using a "mosaic type" model, where regions of long alkyl chains of cations (named 'aliphatic' regions) and the residual chemical moieties in both cations and anions (named 'ionic' regions) give additive contributions. Changes in density due to an increase in temperature and the number of CH2 groups in the long alkyl chains of cations are determined predominantly by changes in the free volume of the 'ionic' regions, while 'aliphatic' regions are already highly compressed by van der Waals forces, which results in only infinitesimal changes in their free volumes with temperature. PMID:25372279

  13. Growth of Highly Oriented Ultrathin Crystalline Organic Microstripes: Effect of Alkyl Chain Length.

    PubMed

    Zhu, Tao; Xiao, Chengliang; Wang, Binghao; Hu, Xiaorong; Wang, Zi; Fan, Jian; Huang, Lizhen; Yan, Donghang; Chi, Lifeng

    2016-09-13

    The growth of organic semiconductor with controllable morphology is a crucial issue for achieving high-performance devices. Here we present the systematic study of the effect of the alkyl chain attached to the functional entity on controlling the growth of oriented microcrystals by dip-coating. Alkylated DTBDT-based molecules with variable chain lengths from n-butyl to n-dodecyl formed into one-dimensional micro- or nanostripe crystals at different pulling speeds. The alignment and ordering are significantly varied with alkyl chain length, as is the transistor performance. Highly uniform oriented and higher-molecular-order crystalline stripes with improved field-effect mobility can be achieved with an alkyl-chain length of around 6. We attribute this effect to the alkyl-chain-length-dependent packing, solubility, and self-assembly behavior. PMID:27548053

  14. Photoinitiated electron transfer to selected physisorbed alkyl bromides: The effects of alkyl chain length on dissociation cross sections

    SciTech Connect

    Khan, K.A.; Camillone, N. III; Osgood, R.M. Jr.

    1999-06-01

    We report the results of measurements of the cross section as a function of wavelength (351, 248, and 193 nm) for photoinitiated dissociative electron attachment to three normal alkyl bromides [CH{sub 3}(CH{sub 2}){sub n{minus}1}Br, n=1, 2, and 3] physisorbed on GaAs(110). Upon UV exposure, the molecules undergo C{endash}Br bond cleavage due to a substrate-mediated electron-transfer process. The cross sections for all three molecules increase monotonically with decreasing wavelength. Our results suggest a {approximately}1 eV higher threshold for dissociation of ethyl and propyl bromide than for methyl bromide. A simple model of the electron-transfer process is employed to estimate the peak per-electron cross section for dissociative attachment in the monolayer. We find that the cross sections for the physisorbed molecules are approximately five times smaller than those for gas-phase molecules, due to a reduction in the lifetime of the molecular anion in the vicinity of the surface. In addition, we also find an increase in cross section with chain length very similar to that observed in the gas phase; the gas-phase behavior has been explained by an increase in the anion lifetime with chain length. Our results suggest that while quenching of the molecular anion at the surface is important, it does not eliminate the progression of anion lifetime with chain length. {copyright} {ital 1999 American Institute of Physics.}

  15. Confinement-induced order of tethered alkyl chains at the water/vapor interface.

    PubMed

    Fukuto, M; Heilmann, R K; Pershan, P S; Yu, S M; Soto, C M; Tirrell, D A

    2002-07-01

    Packing of tethered alkyl chains in Langmuir monolayers of a hairy-rod polypeptide poly[gamma-4-(n-hexadecyloxy)benzyl alpha,L-glutamate] on water has been studied by x-ray scattering measurements at room temperature. The rods lie parallel to the surface while the alkyl side chains segregate toward the vapor. Results indicate that the herringbone order of the alkyl chains is established initially by one-dimensionally confined chains between aligned rods and grows laterally with compression. PMID:12241332

  16. Adsorption of quinolone antibiotics in spherical mesoporous silica: Effects of the retained template and its alkyl chain length.

    PubMed

    Liang, Zhijie; Zhaob, Zhiwei; Sun, Tianyi; Shi, Wenxin; Cui, Fuyi

    2016-03-15

    In this study, mesoporous silica (meso-silica) MCM-41 and those with the templates retained were synthesized and characterized. Adsorption capacities of the synthesized materials towards typical quinolone antibiotic pollutants, enrofloxacin and norfloxacin as representative, were investigated, and effects of the alkyl chain length of the templates on the adsorption capacity were evaluated. The results of this study indicated that the retained templates enhanced the adsorption capacities (Qmax) of the meso-silica MCM-41 toward hydrophobic enrofloxacin, but had an inhibitory effect on that towards hydrophilic norfloxacin, which were attributed to the hydrophobic inter-environment created by the long alkyl chains of the retained templates. Importantly, the adsorption capacity increased with the increase of the alkyl chain length of the retained templates. PMID:26642441

  17. Mössbauer study of novel iron(II)-dioxime complexes with branched alkyl chains

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Lengyel, A.; Homonnay, Z.; Várhelyi, Cs.; Klencsár, Z.; Kubuki, S.; Szalay, R.

    2014-04-01

    Novel iron(II) oxime complexes with dimethyl-glyoxime, methyl-ethyl-glyoxime, methyl-isopropyl-glyoxime, [Fe(DioxH)2L2] with and without axial ligands have been synthesized. 57Fe Mössbauer spectroscopy showed different spin states in complexes with short alkyl chain and with branched alkyl chain, respectively. It was shown that the asymmetry observed in the doublet line intensity of iron-bis-glyoximes is due to the texture effect. The effect of back-coordination was also studied in the case of iron-bis-dioxime complexes with branched alkyl chains, having different axial ligands.

  18. Molecular dynamics study of the effect of alkyl chain length on melting points of [CnMIM][PF6] ionic liquids

    SciTech Connect

    Zhang, Y; Maginn, EJ

    2014-01-01

    Based on molecular dynamics simulations, the melting points T-m of a series of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids [CnMIM][PF6] with n = 2, 4, 10, 12, and 14 were studied using the free energy-based pseudosupercritical path (PSCP) method. The experimental trend that the Tm decreases with increasing alkyl chain length for ILs with short alkyl chains and increases for the ones with long alkyl chains was correctly captured. Further analysis revealed that the different trends are the results of the balance between fusion enthalpy and fusion entropy. For the ILs with short alkyl chains (ethyl and butyl groups), fusion entropy plays the dominant role so that [C4MIM][PF6], which has a larger fusion entropy due to its higher liquid phase entropy has the lower melting temperature. As for the ILs with long alkyl chains, due to the enhanced van der Waals interactions brought about by the long non-polar alkyl chains, enthalpy becomes the deciding factor and the melting points increase when the alkyl chain goes from C10 to C14. While the melting points for [C2MIM][PF6] and [C4MIM][PF6] were quantitatively predicted and the trends for the long chain ILs were captured correctly, the absolute melting points for [C10MIM][PF6], [C12MIM][PF6] and [C14MIM][PF6] were systematically overestimated in the simulations. Three possible reasons for the overestimation were studied but all ruled out. Further simulation or experimental studies are needed to explain the difference.

  19. Surfactant properties of ionic liquids containing short alkyl chain imidazolium cations and ibuprofenate anions.

    PubMed

    Tourné-Péteilh, Corine; Devoisselle, Jean-Marie; Vioux, André; Judeinstein, Patrick; In, Martin; Viau, Lydie

    2011-09-14

    Interfacial tension, electrical conductivity, NMR self-diffusion and DLS experiments have been used to investigate the self-aggregation in water of ionic liquids associating an ibuprofenate anion and 1-alkyl-3-methylimidazolium [C(n)MIm](+) (n = 4, 6, 8) cations. Despite the short alkyl chain on imidazolium cations (n ≤ 8), these ionic liquids exhibit particularly low Critical Aggregation Concentrations (CAC), significantly lower than their parent 1-alkyl-3-methylimidazolium chloride salts. This behaviour is attributed to the formation of catanionic pairs between ibuprofenate and imidazolium. PMID:21799958

  20. Controlling the reversible thermochromism of polydiacetylene/zinc oxide nanocomposites by varying alkyl chain length.

    PubMed

    Chanakul, Amornsak; Traiphol, Nisanart; Traiphol, Rakchart

    2013-01-01

    In this work, polydiacetylene (PDA)/ZnO nanocomposites are successfully fabricated by using three types of monomers with different alkyl chain length, 5,7-hexadecadiynoic acid, 10,12-tricosadiynoic acid, and 10,12-pentacosadiynoic acid. The monomers dispersed in aqueous medium spontaneously assemble onto the surface of ZnO nanoparticles, promoted by strong interfacial interactions. The PDA/ZnO nanocomposites obtained via photopolymerization process are characterized by scanning electron microscopy, laser light scattering, infrared spectroscopy, and uv/vis absorption spectroscopy. The strength of interfacial interactions and morphologies of the nanocomposites are found to vary with alkyl chain length of the monomers. The PDA/ZnO nanocomposites also exhibit rather different thermochromic behaviors compared to their pure PDA counterparts. All nanocomposites show reversible blue/purple color transition upon multiple heating/cooling cycles, while the irreversible blue/red color transition is observed in the systems of pure PDAs. The shortening of alkyl side chain in PDA/ZnO nanocomposites leads to a systematic decrease in their color-transition temperatures. Colors of the nanocomposites at elevated temperature also vary with the alkyl chain length. Our results provide a simple route for controlling the reversible thermochromism of PDA-based materials, allowing their utilization in a wider range of applications. PMID:23058980

  1. Helix-Coil Transition and Association Behavior of Water-Soluble Polypeptides Having Hydrophobic Alkyl Side Chains

    NASA Astrophysics Data System (ADS)

    Inomata, Katsuhiro; Takai, Tomokazu; Ohno, Noriyoshi; Yamaji, Yoshiaki; Yamada, Erina; Sugimoto, Hideki; Nakanishi, Eiji

    Water soluble polypeptide, poly[N 5-(2-hydroxyethyl) L-glutamine] (PHEG), was hydrophobiocally modified partially along the main chain by long alkyl groups -(CH2) n-1CH3 (Cn) as side chains. Association and viscoelastic behavior of solutions of these self-assembling polymers (PHEG-g-Cn, n = 12, 16 and 18) were investigated by means of steady-flow viscosity and linear dynamic viscoelasticity measurements. In the mixed solvent of water/ethylene glycol (EG), the main chain of PHEG-g-Cn changed its conformation from flexible random coil to rodlike α-helix with the increase in EG content of the solvent. When the solvent was pure water, existence of the associative alkyl chains induced a drastic increase in shear flow viscosity (η) than PHEG homopolymer, probably because of formation of self-assembled large aggregates via intermolecular association. When EG was used as solvent, η and the elastic storage modulus (G') of the solution revealed a unique concentration dependence, i.e., η and G' of PHEG-g-C18 solution at 20 wt% were smaller than those at 15 wt%. These viscoelastic behaviors may be described by the α-helical rodlike conformation of PHEG main chain, which is suitable to form an ordered anisotropic phase like lyotropic liquid crystal, with destruction of a physically crosslinked network structure.

  2. U. S. refiners must increase alkylation capacity to meet demand

    SciTech Connect

    Rhodes, A.

    1994-08-22

    Alkylation is one of the most important refinery processes for producing conventional gasoline. And alkylate will continue to be a preferred blending stock in the reformulated-gasoline era. US alkylation units are operating at more than 90% of capacity, and additional capacity will be required to meet projected demand in 1998 and beyond. This capacity will come primarily through debottlenecking existing units, but new capacity will be required in the U.S., particularly after the year 2000. This paper briefly discusses industry trends, supply and demand, and solid acid catalyst technology.

  3. Effect of alkyl chain length on the conformation and order of simple ionic surfactants adsorbed at the D{sub 2}O/CCl{sub 4} interface as studied by sum-frequency vibrational spectroscopy

    SciTech Connect

    Conboy, J.C.; Messmer, M.C.; Richmond, G.L.

    1998-11-10

    The conformational order of three alkanesulfonates, sodium hexanesulfonate (HS), sodium undecanesulfonate (UDS), and sodium dodecanesulfonate (DDS), adsorbed at the D{sub 2}O/CCl{sub 4} interface are examined in detail by sum-frequency vibrational spectroscopy. An increase in surfactant concentration at the interface results in the reduction of gauche defects in the hydrocarbon chains as determined from the intensity ratio of the methyl to methylene symmetric stretch vibrational modes. The degree of disorder in the alkyl chains varies greatly with alkyl chain length. The alkyl chain of HS displays the fewest gauche defects while DDS and UDS display more disorder in their hydrocarbon chains at similar surface concentrations. This observation is interpreted as a reduction in the possible number of gauche conformations for the shorter alkyl chain.

  4. Effect of alkyl side-chain length on the photophysical, morphology and photoresponse properties of poly(3-alkylthiophene)

    NASA Astrophysics Data System (ADS)

    Xu, Wei-Long; Yang, Xiao-Yu; Zheng, Fei; Jin, Han-Dong; Hao, Xiao-Tao

    2015-12-01

    The effect of alkyl side-chain length on the photophysical, morphology and photoresponse properties of poly (3-alkylthiophene) (P3AT) has been investigated. Butyl, hexyl, octyl, decyl, and dodecyl side chains have been studied. In solution state, the average lifetime of poly (3-octylthiophene) (P3OT) is the shortest among P3AT solution owing to the strong intrachain interaction. The fluorescence lifetime of P3AT solution increases with the side-chain length increasing. A similar trend occurs in the P3AT films. This phenomenon illustrates conformation ‘memory’ property evolving from solution state to solid film. The four lifetimes represent different photophysical processes and have been systematically analyzed. The photodetector based on P3DDT is a suitable candidate for practical application owing to the fast, reversible photoresponse and photostability. The high performance of P3DDT-based photodetector is correlated to the optimized morphology and strong interchain interaction which promotes the exciton delocalization.

  5. Nanostructure of mixtures of protic ionic liquids and lithium salts: effect of alkyl chain length.

    PubMed

    Méndez-Morales, Trinidad; Carrete, Jesús; Rodríguez, Julio R; Cabeza, Óscar; Gallego, Luis J; Russina, Olga; Varela, Luis M

    2015-02-21

    The bulk structure of mixtures of two protic ionic liquids, propylammonium nitrate and butylammonium nitrate, with a salt with a common anion, is analyzed at room temperature by means of small angle X-ray scattering and classical molecular dynamics simulations. The study of several structural properties, such as density, radial distribution functions, spatial distribution functions, hydrogen bonds, coordination numbers and velocity autocorrelation functions, demonstrates that increasing the alkyl chain length of the alkylammonium cation results in more segregated, better defined polar and apolar domains, the latter having a larger size. This increase, ascribed to the erosion of the H-bond network in the ionic liquid polar regions as salt is added, is confirmed by means of small angle X-ray scattering measurements, which show a clear linear increase of the characteristic spatial sizes of the studied protic ionic liquids with salt concentration, similar to that previously reported for ethylammonium nitrate (J. Phys. Chem. B, 2014, 118, 761-770). In addition, larger ionic liquid cations lead to a lower degree of hydrogen bonding and to more sparsely packed three-dimensional structures, which are more easily perturbed by the addition of lithium salts. PMID:25609558

  6. Thermodynamic Interactions between Polystyrene and Long-Chain Poly(n-Alkyl Acrylates) Derived from Plant Oils.

    PubMed

    Wang, Shu; Robertson, Megan L

    2015-06-10

    Vegetable oils and their fatty acids are promising sources for the derivation of polymers. Long-chain poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) are readily derived from fatty acids through conversion of the carboxylic acid end-group to an acrylate or methacrylate group. The resulting polymers contain long alkyl side-chains with around 10-22 carbon atoms. Regardless of the monomer source, the presence of alkyl side-chains in poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) provides a convenient mechanism for tuning their physical properties. The development of structured multicomponent materials, including block copolymers and blends, containing poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) requires knowledge of the thermodynamic interactions governing their self-assembly, typically described by the Flory-Huggins interaction parameter χ. We have investigated the χ parameter between polystyrene and long-chain poly(n-alkyl acrylate) homopolymers and copolymers: specifically we have included poly(stearyl acrylate), poly(lauryl acrylate), and their random copolymers. Lauryl and stearyl acrylate were chosen as model alkyl acrylates derived from vegetable oils and have alkyl side-chain lengths of 12 and 18 carbon atoms, respectively. Polystyrene is included in this study as a model petroleum-sourced polymer, which has wide applicability in commercially relevant multicomponent polymeric materials. Two independent methods were employed to measure the χ parameter: cloud point measurements on binary blends and characterization of the order-disorder transition of triblock copolymers, which were in relatively good agreement with one another. The χ parameter was found to be independent of the alkyl side-chain length (n) for large values of n (i.e., n > 10). This behavior is in stark contrast to the n-dependence of the χ parameter predicted from solubility parameter theory. Our study complements prior work investigating the interactions between

  7. Microwave heating in peptide side chain modification via cysteine alkylation.

    PubMed

    Calce, Enrica; De Luca, Stefania

    2016-09-01

    Microwave irradiation has been successfully applied to a selective synthetic procedure for introducing molecular substituents on peptides, providing a noticeable reduction of the reaction time and also an increased crude peptide purity for some compounds. PMID:27351201

  8. Alkyl Chain Growth on a Transition Metal Center: How Does Iron Compare to Ruthenium and Osmium?

    PubMed

    Sainna, Mala A; de Visser, Sam P

    2015-01-01

    Industrial Fischer-Tropsch processes involve the synthesis of hydrocarbons usually on metal surface catalysts. On the other hand, very few homogeneous catalysts are known to perform a Fischer-Tropsch style of reaction. In recent work, we established the catalytic properties of a diruthenium-platinum carbene complex, [(CpRu)₂(μ²-H) (μ²-NHCH₃)(μ³-C)PtCH₃(P(CH₃)₃)₂](CO)n⁺ with n=0, 2 and Cp=η⁵-C₅(CH₃)₅, and showed it to react efficiently by initial hydrogen atom transfer followed by methyl transfer to form an alkyl chain on the Ru-center. In particular, the catalytic efficiency was shown to increase after the addition of two CO molecules. As such, this system could be viewed as a potential homogeneous Fischer-Tropsch catalyst. Herein, we have engineered the catalytic center of the catalyst and investigated the reactivity of trimetal carbene complexes of the same type using iron, ruthenium and osmium at the central metal scaffold. The work shows that the reactivity should increase from diosmium to diruthenium to diiron; however, a non-linear trend is observed due to multiple factors contributing to the individual barrier heights. We identified all individual components of these reaction steps in detail and established the difference in reactivity of the various complexes. PMID:26426009

  9. Alkyl Chain Growth on a Transition Metal Center: How Does Iron Compare to Ruthenium and Osmium?

    PubMed Central

    Sainna, Mala A.; de Visser, Sam P.

    2015-01-01

    Industrial Fischer-Tropsch processes involve the synthesis of hydrocarbons usually on metal surface catalysts. On the other hand, very few homogeneous catalysts are known to perform a Fischer-Tropsch style of reaction. In recent work, we established the catalytic properties of a diruthenium-platinum carbene complex, [(CpRu)2(μ2-H)(μ2-NHCH3)(μ3-C)PtCH3(P(CH3)3)2](CO)n+ with n = 0, 2 and Cp = η5-C5(CH3)5, and showed it to react efficiently by initial hydrogen atom transfer followed by methyl transfer to form an alkyl chain on the Ru-center. In particular, the catalytic efficiency was shown to increase after the addition of two CO molecules. As such, this system could be viewed as a potential homogeneous Fischer-Tropsch catalyst. Herein, we have engineered the catalytic center of the catalyst and investigated the reactivity of trimetal carbene complexes of the same type using iron, ruthenium and osmium at the central metal scaffold. The work shows that the reactivity should increase from diosmium to diruthenium to diiron; however, a non-linear trend is observed due to multiple factors contributing to the individual barrier heights. We identified all individual components of these reaction steps in detail and established the difference in reactivity of the various complexes. PMID:26426009

  10. Theoretical investigation on the kinetics and mechanisms of hydroxyl radical-induced transformation of parabens and its consequences for toxicity: Influence of alkyl-chain length.

    PubMed

    Gao, Yanpeng; Ji, Yuemeng; Li, Guiying; An, Taicheng

    2016-03-15

    As emerging organic contaminants (EOCs), the ubiquitous presence of preservative parabens in water causes a serious environmental concern. Hydroxyl radical ((•)OH) is a strong oxidant that can degrade EOCs through photochemistry in surface water environments as well as in advanced oxidation processes (AOPs). To better understand the degradation mechanisms, kinetics, and products toxicity of the preservative parabens in aquatic environments and AOPs, the (•)OH-initiated degradation reactions of the four parabens were investigated systematically using a computational approach. The four studied parabens with increase of alkyl-chain length were methylparaben (MPB), ethylparaben (EPB), propylparaben (PPB), and dibutylparaben (BPB). Results showed that the four parabens can be initially attacked by (•)OH through (•)OH-addition and H-abstraction routes. The (•)OH-addition route was more important for the degradation of shorter alkyl-chain parabens like MPB and EPB, while the H-abstraction route was predominant for the degradation of parabens with longer alkyl-chain for example PPB and BPB. In assessing the aquatic toxicity of parabens and their degradation products using the model calculations, the products of the (•)OH-addition route were found to be more toxic to green algae than original parabens. Although all degradation products were less toxic to daphnia and fish than corresponding parental parabens, they could be still harmful to these aquatic organisms. Furthermore, as alkyl-chain length increased, the ecotoxicity of parabens and their degradation products was found to be also increased. PMID:26773489

  11. Rotational dynamics of coumarin-153 and 4-aminophthalimide in 1-ethyl-3-methylimidazolium alkylsulfate ionic liquids: effect of alkyl chain length on the rotational dynamics.

    PubMed

    Das, Sudhir Kumar; Sarkar, Moloy

    2012-01-12

    Rotational dynamics of two neutral organic solutes, coumarin-153 (C-153) and 4-aminophthalimide (AP), with only the latter having hydrogen-bond-donating ability, has been investigated in a series of 1-ethyl-3-methylimidazolium alkyl sulfate ionic liquids as a function of temperature. The ionic liquids differ only in the length of the linear alkyl side chain (alkyl = ethyl, butyl, hexyl, and octyl) on the anionic moiety. The present study has been undertaken to examine the role of alkyl side chains on the rotational dynamics of the two solutes in these ionic liquids. Analysis of the results using Stokes-Einstein-Debye hydrodynamic theory indicates that the rotational dynamics of C-153 lies between the stick and slip boundary condition in the ethyl analogue and finally reaches subslip condition as in case of the octyl substituent. The observed rotational behavior of C-153 has been explained on the basis of an increase in the size of the solvent, which offers lower friction for solute rotation. On the other hand, AP shows superstick behavior in the ethyl system and exceeds the stick limit in the octyl derivative. Superstick behavior of AP has been attributed to the specific hydrogen-bonding interaction between AP and the sulfate moiety. Proton NMR investigation confirms the hydrogen-bonding interaction between the N-H hydrogen of AP and the ionic liquid. The decrease in rotational coupling constant values for AP with increasing length of alkyl side chains has been attributed to the decrease in the solute-solvent-specific interaction with an increase in the alkyl side chain length on the sulfate moiety. PMID:22112024

  12. Probing the effects of the ester functional group, alkyl side chain length and anions on the bulk nanostructure of ionic liquids: a computational study.

    PubMed

    Fakhraee, Mostafa; Gholami, Mohammad Reza

    2016-04-14

    The effects of ester addition on nanostructural properties of biodegradable ILs composed of 1-alkoxycarbonyl-3-alkyl-imidazolium cations ([C1COOCnC1im](+), n = 1, 2, 4) combined with [Br](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) were explored by using the molecular dynamics (MD) simulations and quantum theory of atoms in molecules (QTAIM) analysis at 400 K. Various thermodynamic properties of these ILs were extensively computed in our earlier work (Ind. Eng. Chem. Res., 2015, 54, 11678-11700). Nano-scale segregation analysis demonstrates the formation of a small spherical island-like hydrocarbon within the continuous ionic domain for ILs with short alkyl side chain ([C1COOC1C1im]), and a sponge-like nanostructure for the compound with long alkyl side chain ([C1COOC4C1im]). Ester-functionalized ILs with ethyl side chain ([C1COOC2C1im]) are the turning point between two different morphologies. Non-polar channels were observed for [C1COOC4C1im] ILs composed of smaller anions such as [Br] and [NO3], whereas clustering organization was found for the other anions. Formation of the spherical micelle-like nanostructure was seen for lengthened cations. Finally, the incorporation of an ester group into the alkyl side chain of the cation leads to stronger segregation between charged and uncharged networks, which consequently increased the possibility of self-assembly and micelle formation. PMID:27001746

  13. Sources and proxy potential of long chain alkyl diols in lacustrine environments

    NASA Astrophysics Data System (ADS)

    Rampen, Sebastiaan W.; Datema, Mariska; Rodrigo-Gámiz, Marta; Schouten, Stefan; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.

    2014-11-01

    Long chain 1,13- and 1,15-alkyl diols form the base of a number of recently proposed proxies used for climate reconstruction. However, the sources of these lipids and environmental controls on their distribution are still poorly constrained. We have analyzed the long chain alkyl diol (LCD) composition of cultures of ten eustigmatophyte species, with three species from different families grown at various temperatures, to identify the effect of species composition and growth temperature on the LCD distribution. The results were compared with the LCD distribution of sixty-two lake surface sediments, and with previously reported LCD distributions from marine environments. The different families within the Eustigmatophyceae show distinct LCD patterns, with the freshwater family Eustigmataceae most closely resembling LCD distributions in both marine and lake environments. Unlike the other two eustigmatophyte families analyzed (Monodopsidaceae and Goniochloridaceae), C28 and C30 1,13-alkyl diols and C30 and C32 1,15-alkyl diols are all relatively abundant in the family Eustigmataceae, while the mono-unsaturated C32 1,15-alkyl diol was below detection limit. In contrast to the marine environment, LCD distributions in lakes did not show a clear relationship with temperature. The Long chain Diol Index (LDI), a proxy previously proposed for sea surface temperature reconstruction, showed a relatively weak correlation (R2 = 0.33) with mean annual air temperature used as an approximation for annual mean surface temperature of the lakes. A much-improved correlation (R2 = 0.74, p-value <0.001) was observed applying a multiple linear regression analysis between LCD distributions and lake temperatures reconstructed using branched tetraether lipid distributions. The obtained regression model provides good estimates of temperatures for cultures of the family Eustigmataceae, suggesting that algae belonging to this family have an important role as a source for LCDs in lacustrine

  14. Layered structure and Xe sorption and diffusion properties of low-density liquid-crystalline polyesters with n-alkyl side chains

    NASA Astrophysics Data System (ADS)

    Yoshimizu, Hiroaki; Tsukahara, Mitsuhiro; Suzuki, Tomoyuki; Toida, Jiro; Ando, Aisuke; Watanabe, Junji; Tsujita, Yoshiharu

    2005-04-01

    Four low-density liquid-crystalline polyesters with n-alkyl side chains, B-C n ( n is a carbon number of n-alkyl group), were synthesized from the 1,4-di-( n-alkyl ester) of 1,2,4,5-benzenetetracarboxylic acid and 4,4'-biphenol, to clarify the effect of side chain length on higher ordered structure in the solid state and gas sorption and diffusion properties of these polyesters. All the B-C n ( n=6, 10, 14, 18) samples behaved as a thermotropic liquid crystal and formed a layered structure composed of alternating rigid aromatic main chain layers and flexible n-alkyl side chain layers. In the crystal phase, the distance between the rigid aromatic main chain layers, namely the layer spacing, linearly increased with n, indicating that the conformational feature of n-alkyl side chains was trans-rich. This finding was supported from the 13C NMR chemical shift values of methylene carbons in B-C14 and B-C18. Xe sorption of B-C n was restricted to the side chain layer, which is almost a liquid-like environment, and these sorption isotherms obeyed Henry's law. The density of side chain layers was estimated from experimental values of layer spacing and density, under some speculate assumptions, but that determined individually by 129Xe NMR spectroscopy was coincidence. The estimated density of side chain layers became higher with increasing n, as well as n-alkane liquid, and closed to that of the polyethylene in rubbery state. Xe solubility coefficient corrected with the estimated side chain layer's density decreased with increasing n. On the other hand, the diffusion coefficient of Xe in B-C n increased with n, and this was supported from the NMR spectral width of the 129Xe in B-C n. These results also indicate that the main chain layers of B-C n were very dense and could not sorb Xe.

  15. Effect of cation type, alkyl chain length, adsorbate size on adsorption kinetics and isotherms of bromide ionic liquids from aqueous solutions onto microporous fabric and granulated activated carbons.

    PubMed

    Hassan, Safia; Duclaux, Laurent; Lévêque, Jean-Marc; Reinert, Laurence; Farooq, Amjad; Yasin, Tariq

    2014-11-01

    The adsorption from aqueous solution of imidazolium, pyrrolidinium and pyridinium based bromide ionic liquids (ILs) having different alkyl chain lengths was investigated on two types of microporous activated carbons: a fabric and a granulated one, well characterized in terms of surface chemistry by "Boehm" titrations and pH of point of zero charge measurements and of porosity by N2 adsorption at 77 K and CO2 adsorption at 273 K. The influence of cation type, alkyl chain length and adsorbate size on the adsorption properties was analyzed by studying kinetics and isotherms of eight different ILs using conductivity measurements. Equilibrium studies were carried out at different temperatures in the range [25-55 °C]. The incorporation of ILs on the AC porosity was studied by N2 adsorption-desorption measurements at 77 K. The experimental adsorption isotherms data showed a good correlation with the Langmuir model. Thermodynamic studies indicated that the adsorption of ILs onto activated carbons was an exothermic process, and that the removal efficiency increased with increase in alkyl chain length, due to the increase in hydrophobicity of long chain ILs cations determined with the evolution of the calculated octanol-water constant (Kow). The negative values of free energies indicated that adsorption of ILs with long chain lengths having hydrophobic cations was more spontaneous at the investigated temperatures. PMID:24929502

  16. Synthetic Method for Oligonucleotide Block by Using Alkyl-Chain-Soluble Support.

    PubMed

    Matsuno, Yuki; Shoji, Takao; Kim, Shokaku; Chiba, Kazuhiro

    2016-02-19

    A straightforward method for the synthesis of oligonucleotide blocks using a Cbz-type alkyl-chain-soluble support (Z-ACSS) attached to the 3'-OH group of 3'-terminal nucleosides was developed. The Z-ACSS allowed for the preparation of fully protected deoxyribo- and ribo-oligonucleotides without chromatographic purification and released dimer- to tetramer-size oligonucleotide blocks via hydrogenation using a Pd/C catalyst without significant loss or migration of protective groups such as 5'-end 4,4'-dimethoxtrityl, 2-cyanoethyl on internucleotide bonds, or 2'-TBS. PMID:26845521

  17. Triazatriangulenium adlayers on Au(111): Superstructure as a function of alkyl side chain length

    NASA Astrophysics Data System (ADS)

    Lemke, Sonja; Ulrich, Sandra; Claußen, Frauke; Bloedorn, Andreas; Jung, Ulrich; Herges, Rainer; Magnussen, Olaf M.

    2015-02-01

    The structure of organic adlayers, formed by self-assembly of molecular platforms of triazatriangulenium ions on Au(111), was systematically studied by scanning tunneling microscopy as a function of the length of the lateral ligands for alkyl side chains from propyl to dodecyl. A series of hexagonally-ordered adlayers with spacings from 10.7 Å (propyl) to 13.6 Å (dodecyl) was found which are commensurate to the Au(111) substrate lattice, indicating localized bonding of the molecules to the metal.

  18. Antiallergic activity of rosmarinic acid esters is modulated by hydrophobicity, and bulkiness of alkyl side chain.

    PubMed

    Zhu, Fengxian; Xu, Zhongming; Yonekura, Lina; Yang, Ronghua; Tamura, Hirotoshi

    2015-01-01

    Methyl, propyl and hexyl esters of rosmarinic, caffeic and p-coumaric acids were tested for antiallergic activity, and rosmarinic acid propyl ester exhibited the greatest β-hexosaminidase release suppression (IC50, 23.7 μM). Quadratic correlations between pIC50 and cLogP (r(2) = 0.94, 0.98, and 1.00, respectively) were observed in each acid ester series. The antiallergic activity is modulated by hydrophobicity, and alkyl chain bulkiness. PMID:25686361

  19. Alkyl chain length-dependent surface reaction of dodecahydro-N-alkylcarbazoles on Pt model catalysts

    SciTech Connect

    Gleichweit, Christoph; Amende, Max; Bauer, Udo; Schernich, Stefan; Höfert, Oliver; Lorenz, Michael P. A.; Zhao, Wei; Bachmann, Philipp; Papp, Christian; Müller, Michael; Koch, Marcus; Wasserscheid, Peter; Libuda, Jörg; Steinrück, Hans-Peter

    2014-05-28

    The concept of liquid organic hydrogen carriers (LOHC) holds the potential for large scale chemical storage of hydrogen at ambient conditions. Herein, we compare the dehydrogenation and decomposition of three alkylated carbazole-based LOHCs, dodecahydro-N-ethylcarbazole (H{sub 12}-NEC), dodecahydro-N-propylcarbazole (H{sub 12}-NPC), and dodecahydro-N-butylcarbazole (H{sub 12}-NBC), on Pt(111) and on Al{sub 2}O{sub 3}-supported Pt nanoparticles. We follow the thermal evolution of these systems quantitatively by in situ high-resolution X-ray photoelectron spectroscopy. We show that on Pt(111) the relevant reaction steps are not affected by the different alkyl substituents: for all LOHCs, stepwise dehydrogenation to NEC, NPC, and NBC is followed by cleavage of the C–N bond of the alkyl chain starting at 380–390 K. On Pt/Al{sub 2}O{sub 3}, we discern dealkylation on defect sites already at 350 K, and on ordered, (111)-like facets at 390 K. The dealkylation process at the defects is most pronounced for NEC and least pronounced for NBC.

  20. Fluoroalkyl and Alkyl Chains Have Similar Hydrophobicities in Binding to the “Hydrophobic Wall” of Carbonic Anhydrase

    SciTech Connect

    J Mecinovic; P Snyder; K Mirica; S Bai; E Mack; R Kwant; D Moustakas; A Heroux; G Whitesides

    2011-12-31

    The hydrophobic effect, the free-energetically favorable association of nonpolar solutes in water, makes a dominant contribution to binding of many systems of ligands and proteins. The objective of this study was to examine the hydrophobic effect in biomolecular recognition using two chemically different but structurally similar hydrophobic groups, aliphatic hydrocarbons and aliphatic fluorocarbons, and to determine whether the hydrophobicity of the two groups could be distinguished by thermodynamic and biostructural analysis. This paper uses isothermal titration calorimetry (ITC) to examine the thermodynamics of binding of benzenesulfonamides substituted in the para position with alkyl and fluoroalkyl chains (H{sub 2}NSO{sub 2}C{sub 6}H{sub 4}-CONHCH{sub 2}(CX{sub 2}){sub n}CX{sub 3}, n = 0-4, X = H, F) to human carbonic anhydrase II (HCA II). Both alkyl and fluoroalkyl substituents contribute favorably to the enthalpy and the entropy of binding; these contributions increase as the length of chain of the hydrophobic substituent increases. Crystallography of the protein-ligand complexes indicates that the benzenesulfonamide groups of all ligands examined bind with similar geometry, that the tail groups associate with the hydrophobic wall of HCA II (which is made up of the side chains of residues Phe131, Val135, Pro202, and Leu204), and that the structure of the protein is indistinguishable for all but one of the complexes (the longest member of the fluoroalkyl series). Analysis of the thermodynamics of binding as a function of structure is compatible with the hypothesis that hydrophobic binding of both alkyl and fluoroalkyl chains to hydrophobic surface of carbonic anhydrase is due primarily to the release of nonoptimally hydrogen-bonded water molecules that hydrate the binding cavity (including the hydrophobic wall) of HCA II and to the release of water molecules that surround the hydrophobic chain of the ligands. This study defines the balance of enthalpic and

  1. Influence of Solute Charge and Pyrrolidinium Ionic Liquid Alkyl Chain Length on Probe Rotational Reorientation Dynamics

    SciTech Connect

    Guo, Jianchang; Mahurin, Shannon Mark; Baker, Gary A; Hillesheim, Patrick C; Dai, Sheng; Shaw, Robert W

    2014-01-01

    In recent years, the effect of molecular charge on the rotational dynamics of probe solutes in room temperature ionic liquids (RTILs) has been a subject of growing interest. For the purpose of extending our understanding of charged solute behavior within RTILs, we have studied the rotational dynamics of three illustrative xanthene fluorescent probes within a series of N-alkylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Cnmpyr][Tf2N]) RTILs with different n-alkyl chain lengths (n = 3, 4, 6, 8, or 10) using time-resolved fluorescence anisotropy decay. The rotational dynamics of the neutral probe rhodamine B dye lies between the stick and slip boundary conditions due to the influence of specific hydrogen bonding interactions. The rotation of the negatively-charged sulforhodamine 640 is slower than that of its positively-charged counterpart rhodamine 6G. An analysis based upon Stokes-Einstein-Debye hydrodynamics indicates that SR640 adheres to stick boundary conditions due to specific interactions, whereas the faster rotation of R6G is attributed to weaker electrostatic interactions. No dependence of the rotational dynamics on the solvent alkyl chain length was observed for any of the three dyes, suggesting that the specific interactions between dyes and RTILs are independent of this solvent parameter.

  2. Chain-length dependence of the dissociation dynamics of oriented molecular adsorbates: n-alkyl bromides on GaAs(110)

    SciTech Connect

    Khan, K.A.; Camillone, N. III; Osgood, R.M. Jr.

    1999-07-01

    Brominated hydrocarbons adsorbed on semiconductor surfaces serve as ideal model systems for investigating the photoinduced chemistry of oriented molecules in the condensed phase. Under UV irradiation these adsorbates dissociate via attachment of photoexcited substrate electrons giving rise to energetic alkyl and surface-bound bromine fragments. In this report the authors describe the effect on the fragmentation dynamics due to systematic variation of the complexity (alkyl chain length) of the adsorbate. Increasing the length of the alkyl chain leads to distinct changes in the alkyl fragment angular distributions. For methyl bromide, the angular distribution is dominated by a focused beam of directly ejected hyperthermal methyl radicals at 44{degree} (in the [0{bar 1}] direction) from the surface normal. While a similar direct beam is observed for ethyl and propyl bromide, inelastic scattering of these fragments is found to result in increased importance of a slower diffuse cos{sup n} {theta} desorption. In addition, significant retention of alkyl fragments is detected by postirradiation thermal desorption measurements for these longer-chain homologues. Increasing the number of degrees of freedom of the adsorbate is also observed to dramatically alter the energetics of the ejection of the photofragments from the surface. As the number of carbons in the fragment is increased from one to three, the average energy of the directly ejected radicals decreases from 1.48 to 1.1 to 0.69 eV (UV incident at {lambda} = 193 nm). Variations in the energy and angular distributions are discussed in terms of initial adsorbate orientation, energy partitioning into rovibrational modes, and influence of radical-surface interactions.

  3. Structural and Rotational Dynamics of Carbon Dioxide in 1-Alkyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids: The Effect of Chain Length.

    PubMed

    Giammanco, Chiara H; Yamada, Steven A; Kramer, Patrick L; Tamimi, Amr; Fayer, Michael D

    2016-07-14

    Ionic liquids (ILs) have been proposed as possible carbon dioxide (CO2) capture media; thus, it is useful to understand the dynamics of both the dissolved gas and its IL environment as well as how altering an IL affects these dynamics. With increasing alkyl chain length, it is well-established that ILs obtain a mesoscopic structural feature assigned to polar-apolar segregation, and the change in structure with chain length affects the dynamics. Here, the dynamics of CO2 in a series of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ILs, in which the alkyl group is ethyl, butyl, hexyl, or decyl, were investigated using ultrafast infrared spectroscopy by measuring the reorientation and spectral diffusion of carbon dioxide in the ILs. It was found that reorientation of the carbon dioxide occurs on three time scales, which correspond to two different time scales of restricted wobbling-in-a-cone motions and a long-time complete diffusive reorientation. Complete reorientation slows with increasing chain length but less than the increases in viscosity of the bulk liquids. Spectral diffusion, measured with two-dimensional IR spectroscopy, is caused by a combination of the liquids' structural fluctuations and reorientation of the CO2. The data were analyzed using a recent theory that takes into account both contributions to spectral diffusion and extracts the structural spectral diffusion. Different components of the structural fluctuations have distinct dependences on the alkyl chain length. All of the dynamics are fast compared to the complete orientational randomization of the bulk ILs, as measured with optical heterodyne-detected optical Kerr effect measurements. The results indicate a hierarchy of constraint releases in the liquids that give rise to increasingly slower dynamics. PMID:27264965

  4. Highly Crystalline Films of Organic Small Molecules with Alkyl Chains Fabricated by Weak Epitaxy Growth.

    PubMed

    Zhu, Yangjie; Chen, Weiping; Wang, Tong; Wang, Haibo; Wang, Yue; Yan, Donghang

    2016-05-12

    Because side-chain engineering of organic conjugated molecules has been widely utilized to tune organic solid-state optoelectronic properties, the achievement of their high-quality films is important for realizing high-performance devices. Here, highly crystalline films of an organic molecule with short alkyl chains, 5,8,15,18-tetrabutyl-5,8,15,18-tetrahydroindolo[3,2-a]indole[30,20:5,6]quinacridone (C4-IDQA), are fabricated by weak epitaxy growth, and highly oriented, large-area, and continuous films are obtained. Because of the soft matter properties, the C4-IDQA molecules can adjust themselves to realize commensurate epitaxy growth on the inducing layers and exhibited good lattice matching in the thin film phase. The crystalline phase is also observed in thicker C4-IDQA films. The growth behavior of C4-IDQA on the inducing layer is further investigated, including the strong dependence of film morphologies on substrate temperatures and deposition rates due to the poor diffusion ability of C4-IDQA molecules. Moreover, highly crystalline films and high electron field-effect mobility are also obtained for the small molecule N,N'-dioctyl-3,4:9,10-perylene tetracarboxylic diimide (C8-PTCDI), which demonstrate that the weak epitaxy growth method could be an effective way to fabricate highly crystalline films of organic small molecules with flexible side chains. PMID:27116036

  5. Normal and shear forces between charged solid surfaces immersed in cationic surfactant solution: the role of the alkyl chain length.

    PubMed

    Silbert, Gilad; Kampf, Nir; Klein, Jacob

    2014-05-13

    Using a surface force balance (SFB), we measured the boundary friction and the normal forces between mica surfaces immersed in a series of alkyltrimethylammonium chloride (TAC) surfactant solutions well above the critical micelle concentration (CMC). The surfactants that were used--C14TAC, C16TAC, and C18TAC--varied by the length of the alkyl chain. The structures of the adsorbed layers on the mica were obtained using AFM imaging and ranged from flat bilayers to rodlike micelles. Despite the difference in alkyl chain, all the surfactant solutions reduce the friction between the two mica surfaces enormously relative to immersion in water, and have similar friction coefficients (μ ≈ 0.001). The pressure at which such lubrication breaks down is higher for the surfactants with longer chain lengths and indicates that an important role of the chain length is to provide a more robust structure of the adsorbed layers which maintains its integrity to higher pressures. PMID:24720712

  6. Effect of fluorination and size of the alkyl side-chain on the solubility of carbon dioxide in 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids.

    PubMed

    Almantariotis, D; Gefflaut, T; Pádua, A A H; Coxam, J-Y; Costa Gomes, M F

    2010-03-18

    It is proven in this work that it is possible to significantly increase the carbon dioxide uptake by an ionic liquid relying on physical interactions only. The solubility and thermodynamics of solvation of carbon dioxide in the ionic liquids 1-octyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide [C(8)mim][Ntf(2)], 1-decyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide [C(10)mim][Ntf(2)], and 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-3-methylimidazolium bis[trifluoromethylsulfonyl]amide [C(8)H(4)F(13)mim][Ntf(2)] were determined experimentally between 298 and 343 K at pressures close to atmospheric. The solubility of carbon dioxide is significantly higher in the fluorine-substituted ionic liquid with Henry's law constants at 303 K of 33.3 and 30.7 bar for [C(8)mim][Ntf(2)] and [C(10)mim][Ntf(2)], respectively, and of 28.0 bar for [C(8)H(4)F(13)mim][Ntf(2)]. Molecular simulation was used for interpreting the molecular mechanisms of solvation of carbon dioxide in the studied ionic liquids and coherent molecular mechanisms of solvation are proposed in light of the solute-solvent radial distribution functions. It is shown that the increase of the size of the hydrogenated or fluorinated alkyl chain in the imidazolium cation does not lead to a steady augmentation of the gaseous uptake by the liquid probably due to an increase of the nonpolar domains of the ionic liquid, carbon dioxide being solvated preferentially in the charged regions of the solvent. PMID:20178327

  7. Density functional theory with van der waals corrections study of the adsorption of alkyl, alkylthiol, alkoxyl, and amino-alkyl chains on the H:Si(111) surface.

    PubMed

    Arefi, Hadi H; Nolan, Michael; Fagas, Giorgos

    2014-11-11

    Surface modification of silicon with organic monolayers tethered to the surface by different linkers is an important process in realizing future miniaturized electronic and sensor devices. Understanding the roles played by the nature of the linking group and the chain length on the adsorption structures and stabilities of these assemblies is vital to advance this technology. This paper presents a density functional theory (DFT) study of the hydrogen passivated Si(111) surface modified with alkyl chains of the general formula H:Si-(CH2)n-CH2 and H:Si-X-(CH2)n-CH3, where X = NH, O, S and n = (0, 1, 3, 5, 7, 9, 11), at half coverage. For (X)-hexane and (X)-dodecane functionalization, we also examined various coverages up to full monolayer grafting in order to validate the result of half covered surface and the linker effect on the coverage. We find that it is necessary to take into account the van der Waals interaction between the alkyl chains. The strongest binding is for the oxygen linker, followed by S, N, and C, irrespective of chain length. The result revealed that the sequence of the stability is independent of coverage; however, linkers other than carbon can shift the optimum coverage considerably and allow further packing density. For all linkers apart from sulfur, structural properties, in particular, surface-linker-chain angles, saturate to a single value once n > 3. For sulfur, we identify three regimes, namely, n = 0-3, n = 5-7, and n = 9-11, each with its own characteristic adsorption structures. Where possible, our computational results are shown to be consistent with the available experimental data and show how the fundamental structural properties of modified Si surfaces can be controlled by the choice of linking group and chain length. PMID:25260071

  8. Vapor pressures of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with long alkyl chains

    SciTech Connect

    Rocha, Marisa A. A. E-mail: marisa.alexandra.rocha@gmail.com; Coutinho, João A. P.; Santos, Luís M. N. B. F. E-mail: marisa.alexandra.rocha@gmail.com

    2014-10-07

    This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [C{sub N-1}C{sub 1}im][NTf{sub 2}]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C{sub 6}C{sub 6}im][NTf{sub 2}], was detected. An intensification of the odd-even effect was observed starting from [C{sub 6}C{sub 6}im][NTf{sub 2}], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C{sub 7}C{sub 7}im][NTf{sub 2}] and [C{sub 9}C{sub 9}im][NTf{sub 2}]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C{sub 6}C{sub 1}and C{sub 6}C{sub 6}) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length.

  9. Designing greener plasticizers: Effects of alkyl chain length and branching on the biodegradation of maleate based plasticizers.

    PubMed

    Erythropel, Hanno C; Brown, Tobin; Maric, Milan; Nicell, Jim A; Cooper, David G; Leask, Richard L

    2015-09-01

    The ubiquitous presence of the plasticizer di (2-ethylhexyl) phthalate (DEHP) in the environment is of concern due to negative biological effects associated with it and its metabolites. In particular, the metabolite mono (2-ethylhexyl) phthalate (MEHP) is a potential endocrine disruptor. Earlier work had identified the diester di (2-ethylhexyl) maleate (DEHM) as a potential greener candidate plasticizer to replace DEHP, yet its biodegradation rate was reported to be slow. In this study, we modified the side chains of maleate diesters to be linear (i.e., unbranched) alkyl chains that varied in length from ethyl to n-octyl. The plasticization efficiency of these compounds blended into PVC at 29 wt.% increased with the overall length of the molecule, but all compounds performed as well as or better than comparable samples with DEHP. Tests conducted with the equally long DEHM and dihexyl maleate (DHM) showed that branching has no effect on glass transition temperature (Tg) reduction efficiency. Biodegradation experiments with the common soil bacterium Rhodococcus rhodocrous in the presence of the plasticizer showed acceptable hydrolysis rates of maleates with unbranched side chains, while the branched DEHM showed almost no degradation. The addition of hexadecane as auxiliary carbon source improved hydrolysis rates. Temporary buildup of the respective monoester of the compounds were observed, but only in the case of the longest molecule, dioctyl maleate (DOM), did this buildup lead to growth inhibition of the bacteria. Maleates with linear side chains, if designed and tested properly, show promise as potential candidate plasticizers as replacements for DEHP. PMID:25917507

  10. Side chain variations radically alter the diffusion of poly(2-alkyl-2-oxazoline) functionalised nanoparticles through a mucosal barrier.

    PubMed

    Mansfield, Edward D H; de la Rosa, Victor R; Kowalczyk, Radoslaw M; Grillo, Isabelle; Hoogenboom, Richard; Sillence, Katy; Hole, Patrick; Williams, Adrian C; Khutoryanskiy, Vitaliy V

    2016-08-16

    Functionalised nanomaterials are gaining popularity for use as drug delivery vehicles and, in particular, mucus penetrating nanoparticles may improve drug bioavailability via the oral route. To date, few polymers have been investigated for their muco-penetration, and the effects of systematic structural changes to polymer architectures on the penetration and diffusion of functionalised nanomaterials through mucosal tissue have not been reported. We investigated the influence of poly(2-oxazoline) alkyl side chain length on nanoparticle diffusion; poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline), and poly(2-n-propyl-2-oxazoline) were grafted onto the surface of thiolated silica nanoparticles and characterised by FT-IR, Raman and NMR spectroscopy, thermogravimetric analysis, and small angle neutron scattering. Diffusion coefficients were determined in water and in a mucin dispersion (using Nanoparticle Tracking Analysis), and penetration through a mucosal barrier was assessed using an ex vivo fluorescence technique. The addition of a single methylene group in the side chain significantly altered the penetration and diffusion of the materials in both mucin dispersions and mucosal tissue. Nanoparticles functionalised with poly(2-methyl-2-oxazoline) were significantly more diffusive than particles with poly(2-ethyl-2-oxazoline) while particles with poly(2-n-propyl-2-oxazoline) showed no significant increase compared to the unfunctionalised particles. These data show that variations in the polymer structure can radically alter their diffusive properties with clear implications for the future design of mucus penetrating systems. PMID:27400181

  11. Thermal stability and ordering study of long- and short-alkyl chain phosphonic acid multilayers.

    PubMed

    de Pauli, Muriel; Prado, Mariana de Castro; Matos, Matheus Josue Souza; Fontes, Giselle Nogueira; Perez, Carlos Alberto; Mazzoni, Mario Sergio Carvalho; Neves, Bernardo Ruegger Almeida; Malachias, Angelo

    2012-10-30

    Long-range order evolution of self-assembled phosphonic acid multilayers as a function of temperature is studied here for two molecules with different alkyl chain length. By using synchrotron conventional diffraction, distinct order configurations are retrieved on phosphonic acid multilayers and their thermodynamic behavior monitored by energy-dispersive diffraction. This later technique allows us to observe the system behavior near order-disorder temperatures, as well as to determine the most stable configurations in the range from room temperature up to 120 °C. Planar order is also addressed by wide-angle X-ray scattering (WAXS) transmission experiments. Order parameter phase diagrams are built based on the experimental results, showing the dominant configuration at each temperature. The multilayer molecular long-range order retrieved from the experiments is corroborated by first principles calculations based on the Density Functional Theory. The bulk configurations depicted in this work are produced by molecule-molecule interactions and allow for future comparisons with the behavior of ordered molecules in few-monolayers configurations, commonly used in organic devices, where the presence of surfaces and interfaces strongly affects the molecule packing. PMID:23009090

  12. High-performance polymer semiconducting heterostructure devices by nitrene-mediated photocrosslinking of alkyl side chains.

    PubMed

    Png, Rui-Qi; Chia, Perq-Jon; Tang, Jie-Cong; Liu, Bo; Sivaramakrishnan, Sankaran; Zhou, Mi; Khong, Siong-Hee; Chan, Hardy S O; Burroughes, Jeremy H; Chua, Lay-Lay; Friend, Richard H; Ho, Peter K H

    2010-02-01

    Heterostructures are central to the efficient manipulation of charge carriers, excitons and photons for high-performance semiconductor devices. Although these can be formed by stepwise evaporation of molecular semiconductors, they are a considerable challenge for polymers owing to re-dissolution of the underlying layers. Here we demonstrate a simple and versatile photocrosslinking methodology based on sterically hindered bis(fluorophenyl azide)s. The photocrosslinking efficiency is high and dominated by alkyl side-chain insertion reactions, which do not degrade semiconductor properties. We demonstrate two new back-infiltrated and contiguous interpenetrating donor-acceptor heterostructures for photovoltaic applications that inherently overcome internal recombination losses by ensuring path continuity to give high carrier-collection efficiency. This provides the appropriate morphology for high-efficiency polymer-based photovoltaics. We also demonstrate photopatternable polymer-based field-effect transistors and light-emitting diodes, and highly efficient separate-confinement-heterostructure light-emitting diodes. These results open the way to the general development of high-performance polymer semiconductor heterostructures that have not previously been thought possible. PMID:19966791

  13. Effect of Structure on Transport Properties (Viscosity, Ionic Conductivity, and Self-Diffusion Coefficient) of Aprotic Heterocyclic Anion (AHA) Room Temperature Ionic Liquids. 2. Variation of Alkyl Chain Length in the Phosphonium Cation.

    PubMed

    Sun, Liyuan; Morales-Collazo, Oscar; Xia, Han; Brennecke, Joan F

    2016-06-30

    A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)phosphonium cations paired with three different aprotic heterocyclic anions (AHAs) (alkyl = butyl ([P2224](+)) and octyl ([P2228](+))) were prepared to investigate the effect of cationic alkyl chain length on transport properties. The transport properties and density of these ILs were measured from 283.15 to 343.15 K at ambient pressure. The dependence of the transport properties (viscosity, ionic conductivity, diffusivity, and molar conductivity) on temperature can be described by the Vogel-Fulcher-Tamman (VFT) equation. The ratio of the molar conductivity obtained from the molar concentration and ionic conductivity measurements to that calculated from self-diffusion coefficients (measured by pulsed gradient spin-echo nuclear magnetic resonance spectroscopy) using the Nernst-Einstein equation was used to quantify the ionicity of these ILs. The molar conductivity ratio decreases with increasing number of carbon atoms in the alkyl chain, indicating that the reduced Coulombic interactions resulting from lower density are more than balanced by the increased van der Waals interactions between the alkyl chains. The results of this study may provide insight into the design of ILs with enhanced dynamics that may be suitable as electrolytes in lithium ion batteries and other electrochemical applications. PMID:27243107

  14. Comprehensive Study on the Impact of the Cation Alkyl Side Chain Length on the Solubility of Water in Ionic Liquids

    PubMed Central

    Kurnia, Kiki A.; Neves, Catarina M. S. S.; Freire, Mara G.; Santos, Luís M. N. B. F.; Coutinho, João A. P.

    2015-01-01

    A comprehensive study on the phase behaviour of two sets of ionic liquids (ILs) and their interactions with water is here presented through combining experimental and theoretical approaches. The impact of the alkyl side chain length and the cation symmetry on the water solubility in the asymmetric [CN-1C1im][NTf2] and symmetric [CN-1CN-1im][NTf2] series of ILs (N up to 22), from 288.15 K to 318.15 K and at atmospheric pressure, was studied. The experimental data reveal that the solubility of water in ILs with an asymmetric cation is higher than in those with the symmetric isomer. Several trend shifts on the water solubility as a function of the alkyl side chain length were identified, namely at [C6C1im][NTf2] for asymmetric ILs and at [C4C4im][NTf2] and [C7C7im][NTf2] for the symmetric ILs. To complement the experimental data and to further investigate the molecular-level mechanisms behind the dissolution process, Density Functional Theory calculations, using the Conductor-like Screening Model for Real Solvents (COSMO-RS) and the Electrostatic potential-derived CHelpG, were performed. The COSMO-RS model is able to qualitatively predict water solubility as function of temperature and alkyl chain lengths of both symmetric and asymmetric cations. Furthermore, the model is also capable to predict the somewhat higher water solubility in the asymmetric cation, as well as the trend shift as function of alkyl chain lengths experimentally observed. Both COSMO-RS and the electrostatic potential-derived CHelpG show that the interactions of water and the IL cation take place on the IL polar region, namely on the aromatic head and adjacent methylene groups what explains the differences in water solubility observed for cations with different chain lengths. Furthermore, the CHelpG calculations for the isolated cations in the gas phase indicates that the trend shift of water solubility as function of alkyl chain lengths and the difference of water solubility in symmetric may also

  15. Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: dependence on alkyl chain-length, temperature, and anion identity.

    PubMed

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit

    2014-03-14

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH2) considered are acetamide (CH3CONH2), propionamide (CH3CH2CONH2), and butyramide (CH3CH2CH2CONH2); the electrolytes (LiX) are lithium perchlorate (LiClO4), lithium bromide (LiBr), and lithium nitrate (LiNO3). Differential scanning calorimetric measurements reveal glass transition temperatures (T(g)) of these DEs are ~195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ~100-150 K above their individual T(g)s. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH3CONH2 + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi-component melts. PMID:24628189

  16. Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

    NASA Astrophysics Data System (ADS)

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit

    2014-03-01

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH2) considered are acetamide (CH3CONH2), propionamide (CH3CH2CONH2), and butyramide (CH3CH2CH2CONH2); the electrolytes (LiX) are lithium perchlorate (LiClO4), lithium bromide (LiBr), and lithium nitrate (LiNO3). Differential scanning calorimetric measurements reveal glass transition temperatures (Tg) of these DEs are ˜195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ˜100-150 K above their individual Tgs. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH3CONH2 + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi-component melts.

  17. Effect of Sophorolipid n-Alkyl Ester Chain Length on Its Interfacial Properties at the Almond Oil-Water Interface.

    PubMed

    Koh, Amanda; Linhardt, Robert J; Gross, Richard

    2016-06-01

    Sophorolipids (SLs), produced by Candida bombicola, are of interest as potential replacements for hazardous commercial surfactants. For the first time, a series of molecularly edited SLs with ethyl (EE), n-hexyl (HE), and n-decyl (DE) esters were evaluated at an oil (almond oil)-water interface for their ability to reduce interfacial tension (IFT) and generate stable emulsions. An increase in the n-alkyl ester chain length from ethyl to hexyl resulted in a maximum % decrease in the IFT from 86.1 to 95.3, respectively. Furthermore, the critical aggregation concentrations (CACs) decreased from 0.035 to 0.011 and 0.006 mg/mL as the ester chain length was increased from ethyl to n-hexyl and n-decyl, respectively. In contrast, the CAC of natural SL, composed of 50/50 acidic and LSL, is 0.142 mg/mL. Dynamic IFT analysis showed significant differences in diffusion coefficients for all SLs studied. Almond oil emulsions with up to 200:1 (by weight) oil/SL-DE were stable against oil separation for up to 1 week with average droplet sizes below 5 μm. Emulsions of almond oil with natural SLs showed consistent oil separation 24 h after emulsification. A unique connection between IFT and emulsification was found as SL-DE has both the lowest CAC and the best emulsification performance of all natural and modified SLs studied herein. This connection between CAC and emulsification may be generally applicable, providing a tool for the prediction of optimal surfactants in other oil-water interfacial applications. PMID:27159768

  18. Water-mediated recognition of simple alkyl chains by heart-type fatty-acid-binding protein.

    PubMed

    Matsuoka, Shigeru; Sugiyama, Shigeru; Matsuoka, Daisuke; Hirose, Mika; Lethu, Sébastien; Ano, Hikaru; Hara, Toshiaki; Ichihara, Osamu; Kimura, S Roy; Murakami, Satoshi; Ishida, Hanako; Mizohata, Eiichi; Inoue, Tsuyoshi; Murata, Michio

    2015-01-26

    Long-chain fatty acids (FAs) with low water solubility require fatty-acid-binding proteins (FABPs) to transport them from cytoplasm to the mitochondria for energy production. However, the precise mechanism by which these proteins recognize the various lengths of simple alkyl chains of FAs with similar high affinity remains unknown. To address this question, we employed a newly developed calorimetric method for comprehensively evaluating the affinity of FAs, sub-Angstrom X-ray crystallography to accurately determine their 3D structure, and energy calculations of the coexisting water molecules using the computer program WaterMap. Our results clearly showed that the heart-type FABP (FABP3) preferentially incorporates a U-shaped FA of C10-C18 using a lipid-compatible water cluster, and excludes longer FAs using a chain-length-limiting water cluster. These mechanisms could help us gain a general understanding of how proteins recognize diverse lipids with different chain lengths. PMID:25491543

  19. Surface active molecules: preparation and properties of long chain n-acyl-l-alpha-amino-omega-guanidine alkyl acid derivatives.

    PubMed

    Infante, R; Dominguez, J G; Erra, P; Julia, R; Prats, M

    1984-12-01

    Synopsis A new route for the synthesis of long chain N(alpha)-acyl-l-alpha-amino-omega-guamdine alkyl acid derivatives, with cationic or amphoteric character has been established. The general formula of these compounds is shown below. A physico-chemical and antimicrobial study of these products as a function of the alkyl ester or sodium salt (R), the straight chain length of the fatty acid residue (x) and the number of carbons between the omega-guanidine and omega-carboxyl group (n) has been investigated. The water solubility, surface tension, critical micelle concentration (c.m.c.) and minimum inhibitory concentration (MIC) against Gram-positive and Gram-negative bacteria (including Pseudomonas) has been determined. Dicyclohexylcarbodiimide has been used to condense fatty acids and alpha-amino-omega-guanidine alkyl acids. In these conditions protection of the omega-guanidine group is not necessary. The main characteristic of this synthetic procedure is the use of very mild experimental conditions (temperature, pH) to form the amide linkage which leads to pure optical compounds in high yield in the absence of electrolytes. The results show that some structural modifications, particularly the protection of the carboxyl group, promote variations of the surfactant and antimicrobial properties. Only those molecules with the blocked carboxyl group (cationic molecules, where R = Me, Et or Pr) showed a good surfactant and antimicrobial activity. When the carboxyl group was unprotected (amphoteric molecules, where R = Na(+)) the resulting compounds were inactive. PMID:19467126

  20. Synthesis and Photophysical Properties of Soluble Low-Bandgap Thienothiophene Polymers with Various Alkyl Side-Chain Lengths

    SciTech Connect

    Bae, W. J.; Scilla, C.; Duzhko, V. V.; Jo, Jang; Coughlin, E. B.

    2011-05-27

    We report the facile synthesis and characterization of a class of thienothiophene polymers with various lengths of alkyl side chains. A series of 2-alkylthieno[3,4-b]thiophene monomers (Ttx) have been synthesized in a two-step protocol in an overall yield of 28–37%. Poly(2-alkylthieno[3,4-b]thiophenes) (PTtx, alkyl: pentyl, hexyl, heptyl, octyl, and tridecyl) were synthesized by oxidative polymerization with FeCl₃ or via Grignard metathesis (GRIM) polymerization methods. The polymers are readily soluble in common organic solvents. The polymers synthesized by GRIM polymerization method (PTtx-G) have narrower molecular weight distribution (Ð) with lower molecular weight (Mn) than those synthesized by oxidative polymerization (PTtx-O). The band structures of the polymers with various lengths of alkyl side chains were investigated by UV–vis spectroscopy, cyclic voltammetry, and ultraviolet photoelectron spectroscopy. These low-bandgap polymers are good candidates for organic transistors, organic light-emitting diodes, and organic photovoltaic cells.

  1. Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent.

    PubMed

    Kavitha, T; Attri, Pankaj; Venkatesu, Pannuru; Devi, R S Rama; Hofman, T

    2012-04-19

    Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R(4)N](+) with commonly used anion hydroxide [OH](-) were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R(4)N](+)[OH](-) are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH(3))(4)N](+)[OH](-) (TMAH), tetraethyl ammonium hydroxide [(C(2)H(5))(4)N](+)[OH](-) (TEAH), tetrapropyl ammonium hydroxide [(C(3)H(7))(4)N](+)[OH](-) (TPAH) and tetrabutyl ammonium hydroxide [(C(4)H(9))(4)N](+)[OH](-) (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (V(E)), the deviation in isentropic compressibility (Δκ(s)) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich-Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7. PMID:22443087

  2. Dielectric relaxation of alkyl chains in graphite oxide and n-alkylammonium halides

    NASA Astrophysics Data System (ADS)

    Ai, Xiaoqian; Tian, Yuchen; Gu, Min; Yu, Ji; Tang, Tong B.

    2016-05-01

    The dynamic of n-alkylammonium halides and n-alkylammonium cations (n = 12, 14, 16, 18) intercalated in graphite oxide (GO) have been investigated with complex impedance spectroscopy. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, elemental analysis and thermogravimetry served to characterize the materials. The intercalated alkylammonium cations distributes as monolayers (when n = 12, 14 or 16) or bilayers (when n = 18), with their long axis parallel to GO layers, and with cations of headgroups bonded ionically to C-O- groups of GO; backbones of the confined molecules remain free. All halides and intercalation compounds suffer dielectric loss at low temperature. Arrhenius plots of the thermal dependence of the loss peaks, which are asymmetric, produce apparent activation energies that rise with increasing n. Ngai's correlated-state model helps to correct for effects of dipole-dipole interaction, leading to virtually identical values for actual activation energy of 110 meV ± 5%; the values are also almost the same as the barrier energy for internal rotation in the alkyl macromolecule. We conclude that the relaxation of the alkylammonium cations arises not from C3 reorientation of the CH3 at its headgroup, but from small-angle wobbling around its major axis, an intrinsic motion.

  3. Radical Hydrodeiodination of Aryl, Alkenyl, Alkynyl, and Alkyl Iodides with an Alcoholate as Organic Chain Reductant through Electron Catalysis.

    PubMed

    Dewanji, Abhishek; Mück-Lichtenfeld, Christian; Studer, Armido

    2016-06-01

    A simple and efficient method for radical hydrodeiodination is reported. The novel approach uses electron catalysis. In situ generated Na-alcoholates are introduced as radical chain reducing reagents and reactions work with O2 as cheap initiator. Hydrodeiodination works on aryl, alkenyl, alkynyl iodides and a tert-alkyl iodide also gets reduced applying the method. Albeit less general, the method is also applicable to the reduction of aryl bromides. The novel reagent is successfully used to conduct typical reductive radical cyclization reactions and mechanistic studies are reported. PMID:27101530

  4. The Branched-Chain Dodecylbenzene Sulfonate Degradation Pathway of Pseudomonas aeruginosa W51D Involves a Novel Route for Degradation of the Surfactant Lateral Alkyl Chain

    PubMed Central

    Campos-García, Jesús; Esteve, Abraham; Vázquez-Duhalt, Rafael; Ramos, Juán Luis; Soberón-Chávez, Gloria

    1999-01-01

    Pseudomonas aeruginosa W51D is able to grow by using branched-chain dodecylbenzene sulfonates (B-DBS) or the terpenic alcohol citronellol as a sole source of carbon. A mutant derived from this strain (W51M1) is unable to degrade citronellol but still grows on B-DBS, showing that the citronellol degradation route is not the main pathway involved in the degradation of the surfactant alkyl moiety. The structures of the main B-DBS isomers and of some intermediates were identified by gas chromatography-mass spectrometric analysis, and a possible catabolic route is proposed. PMID:10427075

  5. Theoretical study of chain transfer to solvent reactions of alkyl acrylates.

    PubMed

    Moghadam, Nazanin; Srinivasan, Sriraj; Grady, Michael C; Rappe, Andrew M; Soroush, Masoud

    2014-07-24

    This computational and theoretical study deals with chain transfer to solvent (CTS) reactions of methyl acrylate (MA), ethyl acrylate (EA), and n-butyl acrylate (n-BA) self-initiated homopolymerization in solvents such as butanol (polar, protic), methyl ethyl ketone (MEK) (polar, aprotic), and p-xylene (nonpolar). The results indicate that abstraction of a hydrogen atom from the methylene group next to the oxygen atom in n-butanol, from the methylene group in MEK, and from a methyl group in p-xylene by a live polymer chain are the most likely mechanisms of CTS reactions in MA, EA, and n-BA. Energy barriers and molecular geometries of reactants, products, and transition states are predicted. The sensitivity of the predictions to three hybrid functionals (B3LYP, X3LYP, and M06-2X) and three different basis sets (6-31G(d,p), 6-311G(d), and 6-311G(d,p)) is investigated. Among n-butanol, sec-butanol, and tert-butanol, tert-butanol has the highest CTS energy barrier and the lowest rate constant. Although the application of the conductor-like screening model (COSMO) does not affect the predicted CTS kinetic parameter values, the application of the polarizable continuum model (PCM) results in higher CTS energy barriers. This increase in the predicted CTS energy barriers is larger for butanol and MEK than for p-xylene. The higher rate constants of chain transfer to n-butanol reactions compared to those of chain transfer to MEK and p-xylene reactions suggest the higher CTS reactivity of n-butanol. PMID:24971646

  6. N-methylpurine DNA glycosylase overexpression increases alkylation sensitivity by rapidly removing non-toxic 7-methylguanine adducts

    PubMed Central

    Rinne, M. L.; He, Y.; Pachkowski, B. F.; Nakamura, J.; Kelley, M. R.

    2005-01-01

    Previous studies indicate that overexpression of N-methylpurine DNA glycosylase (MPG) dramatically sensitizes cells to alkylating agent-induced cytotoxicity. We recently demonstrated that this sensitivity is preceded by an increased production of AP sites and strand breaks, confirming that overexpression of MPG disrupts normal base excision repair and causes cell death through overproduction of toxic repair intermediates. Here we establish through site-directed mutagenesis that MPG-induced sensitivity to alkylation is dependent on enzyme glycosylase activity. However, in contrast to the sensitivity seen to heterogeneous alkylating agents, MPG overexpression generates no cellular sensitivity to MeOSO2(CH2)2-lexitropsin, an alkylator which exclusively induces 3-meA lesions. Indeed, MPG overexpression has been shown to increase the toxicity of alkylating agents that produce 7-meG adducts, and here we demonstrate that MPG-overexpressing cells have dramatically increased removal of 7-meG from their DNA. These data suggest that the mechanism of MPG-induced cytotoxicity involves the conversion of non-toxic 7-meG lesions into highly toxic repair intermediates. This study establishes a mechanism by which a benign DNA modification can be made toxic through the overexpression of an otherwise well-tolerated gene product, and the application of this principle could lead to improved chemotherapeutic strategies that reduce the peripheral toxicity of alkylating agents. PMID:15905475

  7. Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

    SciTech Connect

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit

    2014-03-14

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH{sub 2} + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH{sub 2}) considered are acetamide (CH{sub 3}CONH{sub 2}), propionamide (CH{sub 3}CH{sub 2}CONH{sub 2}), and butyramide (CH{sub 3}CH{sub 2}CH{sub 2}CONH{sub 2}); the electrolytes (LiX) are lithium perchlorate (LiClO{sub 4}), lithium bromide (LiBr), and lithium nitrate (LiNO{sub 3}). Differential scanning calorimetric measurements reveal glass transition temperatures (T{sub g}) of these DEs are ∼195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ∼100–150 K above their individual T{sub g}s. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH{sub 3}CONH{sub 2} + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in

  8. Alkyl-chain-grafted hexagonal boron nitride nanoplatelets as oil-dispersible additives for friction and wear reduction.

    PubMed

    Kumari, Sangita; Sharma, Om P; Gusain, Rashi; Mungse, Harshal P; Kukrety, Aruna; Kumar, Niranjan; Sugimura, Hiroyuki; Khatri, Om P

    2015-02-18

    Hexagonal boron nitride (h-BN), an isoelectric analogous to graphene multilayer, can easily shear at the contact interfaces and exhibits excellent mechanical strength, higher thermal stability, and resistance toward oxidation, which makes it a promising material for potential lubricant applications. However, the poor dispersibility of h-BN in lube base oil has been a major obstacle. Herein, h-BN powder was exfoliated into h-BN nanoplatelets (h-BNNPs), and then long alkyl chains were chemically grafted, targeting the basal plane defect and edge sites of h-BNNPs. The chemical and structural features of octadecyltriethoxysilane-functionalized h-BNNPs (h-BNNPs-ODTES) were studied by FTIR, XPS, XRD, HRTEM, and TGA analyses. The h-BNNPs-ODTES exhibit long-term dispersion stability in synthetic polyol ester lube base oil because of van der Waals interaction between the octadecyl chains of h-BNNPs-ODTES and alkyl functionalities of polyol ester. Micro- and macrotribology results showed that h-BNNPs-ODTES, as an additive to synthetic polyol ester, significantly reduced both the friction and wear of steel disks. Elemental mapping of the worn area explicitly demonstrates the transfer of h-BNNPs-ODTES on the contact interfaces. Furthermore, insight into the lubrication mechanism for reduction in both friction and wear is deduced based on the experimental results. PMID:25625695

  9. Radiolytic crosslinking and chain scission in aliphatic and alkyl-aromatic polyamides—II

    NASA Astrophysics Data System (ADS)

    Lyons, Bernard J.; Glover, Leon C.

    Regression analysis of the radiation parameters of nine aliphatic polyamides exposed to ionizing radiation leads to the conclusion that the decline in the ratio of chain scission to crosslinking in higher aliphatic polyamides is best related to the linear increase in the methylene content of, or the number of methylene groups in, the polyamide repeat unit. G(crosslink) [ G(X)] and G(chain scission) [ G(CS)] values, however, do not correlate well with either of these parameters. Rather it is found that the major determinant of yields [about 80-85% of the variation for G(X), 70% for G(CS)] is the number of hydrogen atoms or methylene groups in the amine residue. A minor determinant [15% of the variation for G(X) and 30% for G(CS)] is the number of hydrogen atoms or methylene groups in the acid residue of the repeat unit. Significantly, although there was little sign of a decrease in G(CS) in the higher aliphatic homologues (up to 11 methylene residues per amide group), G(CS) is found to be positively related to the number of methylene groups in the amine residue but negatively related to the number of methylene groups in the acid residue. Thus although the amine residue dominates the radiolytic response, the acid residue plays a critical if lesser role in determining chain scission yields in polyamides. Thus a polyamide with the repeat unit —(CH 2) 3 nCONH(CH 2) nNHCO— would be predicted to have a very low or zero G(CS) and, if n is 10 or more, a G(X) comparable to that of polyethylene. Although, logically, the yields of crosslinks and chain scissions in polyamides would be expected to tend to that of polyethylene as the number of methylene groups in the repeat unit increases, use of two models assuming an exponential trend to the G(X) value characteristic of polyethylene in the analysis did not provide better fits to the data than the simple linear model referred to above. Indeed, the assumption of a significant exponential trend factor led to a marked drop in

  10. Liquid crystal alignment on ion-beam-treated polyimide with a long alkyl side chain: near edge X-ray absorption fine structure spectroscopy analysis.

    PubMed

    Seo, Joo-Hong; Hwang, Soo Won; Song, Dong Han; Shin, Jae Hoon; Yoon, Tae-Hoon; Kim, Jae Chang; Yi, Mi Hye

    2009-02-19

    Liquid crystal alignment on ion-beam-treated polyimides with a long alkyl side chain was investigated using near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The long alkyl side chains and the asymmetric distribution and orientational order of the pi-bonds of the polyimide surface can be determined by analyzing the angular dependent resonance intensities of the NEXAFS measurements. Herein, we demonstrate that the pretilt angle of the LC cell made by our method decreases as more long alkyl side chains are destroyed. Additionally, the tilt direction of the LC molecules can be determined from the asymmetric distribution of pi-bonds of the polyimide created by the ion beam irradiation. PMID:19161281

  11. Solubility of n-butane and 2-methylpropane (isobutane) in 1-alkyl-3-methylimidazolium-based ionic liquids with linear and branched alkyl side-chains.

    PubMed

    Pison, Laure; Shimizu, Karina; Tamas, George; Lopes, José Nuno Canongia; Quitevis, Edward L; Gomes, Margarida F Costa

    2015-11-11

    The solubility of n-butane and 2-methylpropane (isobutane) in three ionic liquids - 1-(2-methylpropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(2mC3)C1im][Ntf2], 1-(3-methylbutyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(3mC4)C1im][Ntf2] and 1-methyl-3-pentylimidazolium bis(trifluoromethylsulfonyl)imide [C5C1im][Ntf2] - has been measured at atmospheric pressure from 303 to 343 K. Isobutane is less soluble than n-butane in all the ionic liquids. Henry's constant values range from 13.8 × 10(5) Pa for n-butane in [C5C1im][Ntf2] at 303 K to 64.5 × 10(5) Pa for isobutane in [(2mC3)C1im][Ntf2] at 343 K. The difference in solubility between the two gases can be explained by a more negative enthalpy of solvation for n-butane. A structural analysis of the pure solvents and of the solutions of the gases, probed by molecular dynamics simulations, could explain the differences found in the systems: (i) the nonpolar domains of the ionic liquids accommodate better the long and more flexible n-butane solute; (ii) the small differences in solubility of each gas in the ionic liquids with the same number of carbon atoms in the alkyl side-chains are explained by the absence of large structural differences in the pure solvents. In all cases, the structural analysis of the four ionic liquids confirms that the studied gases can act as probes of the molecular structure of the ionic liquids, the simulations being always compatible with the experimental solubility data. PMID:26506981

  12. Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin.

    PubMed

    Vishvakarma, Vijay K; Kumari, Kamlesh; Patel, Rajan; Dixit, V S; Singh, Prashant; Mehrotra, Gopal K; Chandra, Ramesh; Chakrawarty, Anand Kumar

    2015-05-15

    Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation. PMID:25766242

  13. Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Vishvakarma, Vijay K.; Kumari, Kamlesh; Patel, Rajan; Dixit, V. S.; Singh, Prashant; Mehrotra, Gopal K.; Chandra, Ramesh; Chakrawarty, Anand Kumar

    2015-05-01

    Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation.

  14. Mathematical modeling of the aquatic macrophyte inputs of mid-chain n-alkyl lipids to lake sediments: Implications for interpreting compound specific hydrogen isotopic records

    NASA Astrophysics Data System (ADS)

    Gao, Li; Hou, Juzhi; Toney, Jaime; MacDonald, Dana; Huang, Yongsong

    2011-07-01

    We present a systematic study of chain-length distributions and D/H ratios of n-alkyl lipids (both n-alkanes and n-alkanoic acids) in a wide range of terrestrial and aquatic plants around and in Blood Pond, Massachusetts, USA. The primary goal is to establish a model to quantitatively assess the aquatic plant inputs of the mid-chain length n-alkyl lipids to lake sediments and to determine the average hydrogen isotopic ratios of these lipids in different plants. Our results show that middle-chain n-alkyl lipids (C 21-C 23n-alkanes and C 20-C 24n-alkanoic acids) are exceptionally abundant in floating and submerged aquatic plants, in contrast to the dominance of long-chain n-alkyl lipids (C 27-C 31n-alkanes and C 26-C 32n-alkanoic acids) in other plant types, which are consistent with previously published data from Mountain Kenya and the Tibetan Plateau. Combining available data in different environmental settings allows us to establish statistically robust model distributions of n-alkyl lipids in floating/submerged macrophytes relative to other plant types. Based on the model distributions, we established a multi-source mixing model using a linear algebra approach, in order to quantify the aquatic inputs of mid-chain n-alkyl lipids in lake sediments. The results show that ˜97% of the mid-chain n-alkyl lipids (C 23n-alkane and C 22n-acid (behenic acid)) in Blood Pond sediments are derived from floating and submerged macrophytes. In addition, D/H ratios of C 22n-acid and C 23n-alkane in the floating and submerged plants from Blood Pond display relatively narrow ranges of variation (-161 ± 16‰ and -183 ± 18‰, respectively). Our study demonstrates that mid-chain n-alkyl lipids such as C 23n-alkane and C 22n-acid could be excellent recorders of past lake water isotopic ratios in lakes with abundant floating and submerged macrophyte inputs.

  15. Impact of chain length on antibacterial activity and hemocompatibility of quaternary N-alkyl and n,n-dialkyl chitosan derivatives.

    PubMed

    Sahariah, Priyanka; Benediktssdóttir, Berglind E; Hjálmarsdóttir, Martha Á; Sigurjonsson, Olafur E; Sørensen, Kasper K; Thygesen, Mikkel B; Jensen, Knud J; Másson, Már

    2015-05-11

    A highly efficient method for chemical modification of chitosan biopolymers by reductive amination to yield N,N-dialkyl chitosan derivatives was developed. The use of 3,6-O-di-tert-butyldimethylsilylchitosan as a precursor enabled the first 100% disubstitution of the amino groups with long alkyl chains. The corresponding mono N-alkyl derivatives were also synthesized, and all the alkyl compounds were then quaternized using an optimized procedure. These well-defined derivatives were studied for antibacterial activity against Gram positive S. aureus, E. faecalis, and Gram negative E. coli, P. aeruginosa, which could be correlated to the length of the alkyl chain, but the order was dependent on the bacterial strain. Toxicity against human red blood cells and human epithelial Caco-2 cells was found to be proportional to the length of the alkyl chain. The most active chitosan derivatives were found to be more selective for killing bacteria than the quaternary ammonium disinfectants cetylpyridinium chloride and benzalkonium chloride, as well as the antimicrobial peptides melittin and LL-37. PMID:25830631

  16. Novel polymer electrolytes based on cationic polyurethane with different alkyl chain length

    NASA Astrophysics Data System (ADS)

    Liu, Libin; Wu, Xiwen; Li, Tianduo

    2014-03-01

    A series of comb-like cationic polyurethanes (PUs) were synthesized by quaternizing different bromoalkane (C2H5Br, C8H17Br, and C14H29Br) with polyurethane. Solid polymer electrolytes were prepared by complexes cationic PUs with different content of LiClO4. All the solid polymer electrolytes had sufficient thermal stability as confirmed by TGA and exhibited a single-phase behavior evidenced by DSC results. For these electrolytes, FT-IR spectra indicated the formation of polymer-ion complexes. The ac impedance spectra show that the conductivity of the electrolytes follow the Arrhenius behavior, and ionic conductivity is associated with both the charge migration of ions between coordination sites and transmission between aggregates, as confirmed by FT-IR and SEM. Alkyl quaternary ammonium salts in the polymer backbone are recognized as inherent plasticizers, which make the electrolytes exhibit liquid-like behavior. The plasticizing effect of PU-C8 and PU-C14 electrolytes are more effective than that of PU-C2 electrolyte. Maximum ionic conductivity at room temperature for PU-C8 electrolytes containing 50 wt% LiClO4 reached 1.1 × 10-4 S cm-1. This work provides a new research clue that alkyl quaternary ammonium salts could be used as inherent plasticizers and hence make the system behave like a liquid with high ionic conductivity, while preserving the dimensional stability of the solids.

  17. Uncoupling and Toxic Action of Alkyltriphenylphosphonium Cations on Mitochondria and the Bacterium Bacillus subtilis as a Function of Alkyl Chain Length.

    PubMed

    Khailova, L S; Nazarov, P A; Sumbatyan, N V; Korshunova, G A; Rokitskaya, T I; Dedukhova, V I; Antonenko, Yu N; Skulachev, V P

    2015-12-01

    A series of permeating cations based on alkyl derivatives of triphenylphosphonium (C(n)-TPP(+)) containing linear hydrocarbon chains (butyl, octyl, decyl, and dodecyl) was investigated in systems of isolated mitochondria, bacteria, and liposomes. In contrast to some derivatives (esters) of rhodamine-19, wherein butyl rhodamine possessed the maximum activity, in the case of C(n)-TPP a stimulatory effect on mitochondrial respiration steadily increased with growing length of the alkyl radical. Tetraphenylphosphonium and butyl-TPP(+) at a dose of several hundred micromoles exhibited an uncoupling effect, which might be related to interaction between C(n)-TPP(+) and endogenous fatty acids and induction of their own cyclic transfer, resulting in transport of protons across the mitochondrial membrane. Such a mechanism was investigated by measuring efflux of carboxyfluorescein from liposomes influenced by C(n)-TPP(+). Experiments with bacteria demonstrated that dodecyl-TPP(+), decyl-TPP(+), and octyl-TPP(+) similarly to quinone-containing analog (SkQ1) inhibited growth of the Gram-positive bacterium Bacillus subtilis, wherein the inhibitory effect was upregulated with growing lipophilicity. These cations did not display toxic effect on growth of the Gram-negative bacterium Escherichia coli. It is assumed that the difference in toxic action on various bacterial species might be related to different permeability of bacterial coats for the examined triphenylphosphonium cations. PMID:26638684

  18. Effect of the alkyl chains and of the headgroups on the thermal behavior of ascorbic acid surfactants mixtures.

    PubMed

    Venturini, Chiara; Pomposi, Cristina; Ambrosi, Moira; Carretti, Emiliano; Fratini, Emiliano; Lo Nostro, Pierandrea; Baglioni, Piero

    2014-03-20

    The role of the alkyl chain length and of the headgroup on the thermal behavior of mixtures of ASC8 (ascorbyl octanoate) and ASC16 (ascorbyl hexadecanoate) was investigated through differential scanning calorimetry, small- and wide-angle X-ray scattering, and Fourier transform infrared spectroscopy experiments. The formation of two eutectics and of a peritectic point was found from the phase diagram, and their structural properties were studied. The results were compared by investigating the thermal behavior of mixtures of octanoic acid and hexadecanoic acid. The findings provide insights into the role of the ascorbyl headgroups on the intermolecular interactions that determine the phase behavior of the two ascorbic acid based surfactants in the solid state. PMID:24555769

  19. Aquatic Macrophytes Inputs of Middle Chain Length n-alkyl Lipids into Lake Sediments: a Linear Algebra Approach

    NASA Astrophysics Data System (ADS)

    Gao, L.; Huang, Y.

    2009-12-01

    Quantitatively delineating multiple source inputs is a common but often difficult task in geological and environmental researches. Binary mixing model works well for simple two-component mixing problems when the two end members can be accurately defined. However, real world mixing problems usually involve more than two source components, and each component may have many composite profiles. Therefore, binary model is inadequate to provide an accurate estimate of contribution of all the end member sources. In such cases, linear combination model by solving linear algebra equations will have to be developed. In this study, we demonstrate the application of the linear algebra method to accurately calculate the percentage inputs of leaf waxes from different plant groups to lake sediments of Blood Pond and Rocky Pond in Massachusetts. We systematically sampled 28 species, including 6 tree species, 6 grass species, 7 emergent plants, 4 floating and 3 submerged aquatic plants around Blood Pond as well as 6 sediments samples of different depth. The distributions of these plants leaf waxes (n-alkanes and n-alkanoic acids) show distinctively different patterns, but also significant overlaps. To accurately quantify the percentage source inputs, we develop the 4-end member linear combination model. As we have an equation for each of the total 6 n-alkane compounds we use (C23 alkane ~C33 alkane), a 'least square fitting' is applied to solved the overdetermined linear system. Our results show that 91.7% of the total C23 alkane in sediments is derived from floating and submerged plants. We also applied our approach to Rocky Pond in southeastern Massachusetts and found >92 % of mid chain n-alkyl lipids are contributed by floating and submerged plants. Our results provide critical basis for using D/H ratios of mid-chain n-alkyl lipids (such as behenic acid) in lake sediments for reconstructing lake water D/H ratios.

  20. Ultrafast charge-transfer reactions of indoline dyes with anchoring alkyl chains of varying length in mesoporous ZnO solar cells.

    PubMed

    Rohwer, Egmont; Minda, Iulia; Tauscher, Gabriele; Richter, Christoph; Miura, Hidetoshi; Schlettwein, Derck; Schwoerer, Heinrich

    2015-04-01

    Dye-sensitized solar cells based on a mesoporous ZnO substrate were sensitized with the indoline derivatives DN91, DN216 and DN285. The chromophore is the same for each of these dyes. They differ from each other in the length of an alkyl chain, which provides a second anchor to the ZnO surface and prolongs cell lifetime. Ultrafast transient absorption measurements reveal a correlation between the length of the alkyl chain and the fastest electron-injection process. The depopulation of the excited state and the associated emergence of the oxidized molecules are dominant spectral features in the transient absorption of the dyes with shorter alkyl chains. A slower picosecond-scale decay proceeds at constant rate for all three derivatives and is assigned to electron transfer into the trap states of ZnO. All assignments are in good agreement with a higher quantum efficiency of charge injection leading to higher short-circuit currents J(sc) for dyes with shorter alkyl chains. PMID:25652263

  1. Cholesterol Analogs with Degradation-resistant Alkyl Side Chains Are Effective Mycobacterium tuberculosis Growth Inhibitors.

    PubMed

    Frank, Daniel J; Zhao, Yan; Wong, Siew Hoon; Basudhar, Debashree; De Voss, James J; Ortiz de Montellano, Paul R

    2016-04-01

    Cholest-4-en-3-one, whether added exogenously or generated intracellularly from cholesterol, inhibits the growth ofMycobacterium tuberculosiswhen CYP125A1 and CYP142A1, the cytochrome P450 enzymes that initiate degradation of the sterol side chain, are disabled. Here we demonstrate that a 16-hydroxy derivative of cholesterol, which was previously reported to inhibit growth ofM. tuberculosis, acts by preventing the oxidation of the sterol side chain even in the presence of the relevant cytochrome P450 enzymes. The finding that (25R)-cholest-5-en-3β,16β,26-triol (1) (and its 3-keto metabolite) inhibit growth suggests that cholesterol analogs with non-degradable side chains represent a novel class of anti-mycobacterial agents. In accord with this, two cholesterol analogs with truncated, fluorinated side chains have been synthesized and shown to similarly block the growth in culture ofM. tuberculosis. PMID:26833565

  2. In vitro analysis of the effect of alkyl-chain length of anionic surfactants on the skin by using a reconstructed human epidermal model.

    PubMed

    Yamaguchi, Fumiko; Watanabe, Shin-Ichi; Harada, Fusae; Miyake, Miyuki; Yoshida, Masaki; Okano, Tomomichi

    2014-01-01

    We investigated the effect of the alkyl-chain length of anionic surfactants on the skin using an in vitro model. The evaluated anionic surfactants were sodium alkyl sulfate (AS) and sodium fatty acid methyl ester sulfonate (MES), which had different alkyl-chain lengths (C8-C14). Skin tissue damage and permeability were examined using a reconstructed human epidermal model, LabCyte EPI-MODEL24. Skin tissue damage was examined by measuring cytotoxicity with an MTT assay. Liquid chromatography/tandem mass spectrometry (LC/MS-MS) and liquid chromatography/mass spectrometry (LC/MS) were used to detect surfactants that permeated into the assay medium through an epidermal model. To assess the permeation mechanism and cell damage caused by the surfactants through the epidermis, we evaluated the structural changes of Bovine Serum Albumin (BSA), used as a simple model protein, and the fluidity of 1,2-dipalmitoyl-sn-glycero-3-phosphpcholine (DPPC) liposome, which serves as one of the most abundant phospholipid models of living cell membranes in the epidermis. The effects of the surfactants on the proteins were measured using Circular Dichroism (CD) spectroscopy, while the effects on membrane fluidity were investigated by electron spin resonance (ESR) spectroscopy. ET50 (the 50% median effective time) increased as follows: C10 < C12 < C8 < C14 in AS and C8, C10 < C12 < C14 in MES. The order of permeation through the LabCyte EPI-MODEL24 was C10 > C12 > C14, for both AS and MES. For both AS and MES, the order parameter, which is the criteria for the microscopic viscosity of lipid bilayers, increased as follows: C10 < C12 < C14, which means the membrane fluidity is C10 > C12 > C14. It was determined that the difference in skin tissue damage in the LabCyte EPI-MODEL24 with C10 to C14 AS and MES was caused by the difference in permeation and cell membrane fluidity through the lipid bilayer path in the epidermis. PMID:25213449

  3. Effect of alkyl chain length and hydroxyl group functionalization on the surface properties of imidazolium ionic liquids.

    PubMed

    Pensado, Alfonso S; Costa Gomes, Margarida F; Canongia Lopes, José N; Malfreyt, Patrice; Pádua, Agílio A H

    2011-08-14

    Properties of the surface of ionic liquids, such as surface tension, ordering, and charge and density profiles, were studied using molecular simulation. Two types of modification in the molecular structure of imidazolium cations were studied: the length of the alkyl side chain and the presence of a polar hydroxyl group at the end of the side chain. Four ionic liquids were considered: 1-ethyl-3-methylimidazolium tetrafluoroborate, [C(2)C(1)im][BF(4)]; 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate, [C(2)OHC(1)im][BF(4)]; 1-octyl-3-methylimidazolium tetrafluoroborate, [C(8)C(1)im][BF(4)] and 1-(8-hydroxyoctyl)-3-methylimidazolium tetrafluoroborate, [C(8)OHC(1)im][BF(4)]. The surface tension was calculated using both mechanical and thermodynamic definitions, with consistent treatment of the long-range corrections. The simulations reproduce the available experimental values of surface tension with a maximum deviation of ±10%. This energetic characterization of the interface is completed by microscopic structural analysis of orientational ordering at the interface and density profiles along the direction normal to the interface. The presence of the hydroxyl group modifies the local structure at the interface, leading to a less organized liquid phase. The results allow us to relate the surface tension to the structural ordering at the liquid-vacuum interface. PMID:21643581

  4. Contrasting Effects of a Rigid Core and an Alkyl Chain in nCB on the Phase Behavior of Lipid Bilayers.

    PubMed

    Usuda, Hatsuho; Hishida, Mafumi; Yamamura, Yasuhisa; Saito, Kazuya

    2016-06-14

    Molecules incorporated into biomembranes often bear both a core and an alkyl chain in a single molecule (e.g., sterols). To clarify the effects of these two parts of a molecule, the phase behavior of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayer containing 4-n-alkyl-4'-cyanobiphenyl (nCB) (n = 0-8) was investigated. The trends of the main transition temperature (Tm) with respect to n and of the pretransition temperature (Tp) with respect to nCB content changed at n = 3. It was therefore suggested that the two parts of the molecule had opposing effects on the phase behavior of DPPC bilayers. The core appears to perturb molecular ordering in the gel phase and lowers Tm (like cholesterol), while alkyl chains appear to order the lipids in the gel phase and raise Tm (like n-alkanes). In addition, Tm exhibits the so-called odd-even effect based on the alkyl chain length of the minor component, nCB. Depending on the value of n, the variation in Tp was dependent on the additive content, although the pretransition was rarely observed at high contents. PMID:27219128

  5. Investigating the Influence of Alkyl Chain Length in Poly(3-alkylthiophene)s Over the Thin Film Morphology by Optical and Electrical Characterization.

    PubMed

    Bhargava, Kshitij; Bilgaiyan, Anubha; Mohan, S Raj; Itoop, M O; Joshi, Mukesh P; Kukreja, L M; Singh, Vipul

    2016-04-01

    This paper studies the influence of alkyl-chain length in poly(3-alkylthiophene)s over the morphology of thin films and electrical parameters of the devices based on it. Regioregular poly(3-hexylthiophene) and poly(3-octylthiophene) were chosen as the semiconducting materials for the study. The morphological variations were studied by absorption spectroscopy, photoluminescence spectroscopy and X-ray diffraction study. The absorption and photoluminescence showed decreased coplanarity of main chain in poly(3-octylthiophene) over poly(3-hexylthiophene) and which was later confirmed using X-ray diffraction studies which clearly showed increased interchain spacing in case of poly(3-octylthiophene). The schottky diodes fabricated using these materials showed decreased mobility in poly(3-octylthiophene) based diodes as measured by space-charge limiting current method and photo-induced charge carrier extraction by linearly increasing voltage technique. Moreover, we observed a negative field dependence of mobility at room temperature in both the devices and attributed this to the presence of dominant positional disorder in poly(3-alkylthiophene)s. Furthermore, the photocurrent dependence on electric field too showed inferior mobility of poly(3-octylthiophene) based diodes. PMID:27451611

  6. Characterization of alkylphenol degradation gene cluster in Pseudomonas putida MT4 and evidence of oxidation of alkylphenols and alkylcatechols with medium-length alkyl chain.

    PubMed

    Takeo, Masahiro; Prabu, Subbuswamy K; Kitamura, Chitoshi; Hirai, Makoto; Takahashi, Hana; Kato, Dai-Ichiro; Negoro, Seiji

    2006-10-01

    Alkylphenols (APs) are ubiquitous contaminants in aquatic environments and have endocrine disrupting and toxic effects on aquatic organisms. To investigate biodegradation mechanisms of APs, an AP degradation gene cluster was cloned from a butylphenol (BP)-degrading bacterium, Pseudomonas putida MT4. The gene cluster consisted of 13 genes named bupBA1A2A3A4A5A6CEHIFG. From the nucleotide sequences, bupA1A2A3A4A5A6 were predicted to encode a multicomponent phenol hydroxylase (PH), whereas bupBCEHIFG were expected to encode meta-cleavage pathway enzymes. A partial sequence of a putative NtrC-type regulatory gene, bupR, was also found upstream of the gene bupB. This result indicates that APs can be initially oxidized into alkylcatechols (ACs), followed by the meta-cleavage of the aromatic rings. To confirm this pathway, AP degradation tests were carried out using the recombinant P. putida KT2440 harboring the PH genes (bupA1A2A3A4A5A6). The recombinant strain oxidized 4-n-APs with an alkyl chain of up to C7 (< or = C7) efficiently and also several BPs including those with an alkyl chain with some degree of branching. Therefore, it was found that PH had a broad substrate specificity for APs with a medium-length alkyl chain (C3-C7). Moreover, the cell extract of a recombinant Escherichia coli harboring bupB (a catechol 2,3-dioxygenase gene) converted 4-n-ACs with an alkyl chain of < or = C9 into yellow meta-cleavage products with a maximum absorbance at 379 nm, indicating that the second step enzyme in this pathway is also responsible for the degradation of ACs with a medium-length alkyl chain. These results suggest that MT4 is a very useful strain in the biodegradation of a wide range of APs with a medium-length alkyl chain, which known nonylphenol-degrading Sphingomonas strains have never degraded. PMID:17116584

  7. Effects of alkyl chain length on the adsorption of an N-alkylated acridine orange cation by colloidally dispersed zirconium phosphate

    SciTech Connect

    Taniguchi, Masahiro; Yamagishi, Akihiko; Iwamoto, Toschitake )

    1990-03-22

    The adsorption of N-alkylated acridine orange derivatives (AO-C{sub n}; n = the number of carbon atoms in an alkyl group) by colloidally dispersed zirconium phosphate (ZrP) was studied by spectrophotometry and electric dichroism. An AO-C{sub n} cation was bound to ZrP by releasing a proton in the phosphate group of ZrP. The electronic spectrum of bound AO-C{sub n} showed that the dye cations formed an aggregate on the polymer. The reduced linear dichroism of a bound dye molecule, {rho}, was determined as a function of n: {rho} = 1.3-1.0 for n = 0-2, while {rho} = {minus}0.3 to {minus}0.4 for n = 3-9.

  8. Impact of the Crystalline Packing Structures on Charge Transport and Recombination via Alkyl Chain Tunability of DPP-Based Small Molecules in Bulk Heterojunction Solar Cells.

    PubMed

    Song, Chang Eun; Kim, Yu Jin; Suranagi, Sanjaykumar R; Kini, Gururaj P; Park, Sangheon; Lee, Sang Kyu; Shin, Won Suk; Moon, Sang-Jin; Kang, In-Nam; Park, Chan Eon; Lee, Jong-Cheol

    2016-05-25

    A series of small compound materials based on benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) with three different alkyl side chains were synthesized and used for organic photovoltaics. These small compounds had different alkyl branches (i.e., 2-ethylhexyl (EH), 2-butyloctyl (BO), and 2-hexyldecyl (HD)) attached to DPP units. Thin films made of these compounds were characterized and their solar cell parameters were measured in order to systematically analyze influences of the different side chains of compounds on the film microstructure, molecular packing, and hence, charge-transport and recombination properties. The relatively shorter side chains in the small molecules enabled more ordered packing structures with higher crystallinities, which resulted in higher carrier mobilities and less recombination factors; the small molecule with the EH branches exhibited the best semiconducting properties with a power conversion efficiency of up to 5.54% in solar cell devices. Our study suggested that tuning the alkyl chain length of semiconducting molecules is a powerful strategy for achieving high performance of organic photovoltaics. PMID:27156705

  9. Computational analysis of molecular properties and spectral characteristics of cyano-containing liquid crystals: Role of alkyl chains

    NASA Astrophysics Data System (ADS)

    Praveen, P. Lakshmi; Ojha, Durga P.

    2011-05-01

    The electronic transitions in the uv-visible range of 4'-n-alkyl-4-cyanobiphenyl (nCB) with propyl, pentyl, and heptyl groups, which are of commercial and application interests, have been studied. The uv-visible and circular dichroism spectra of nCB (n = 3,5,7) molecules have been simulated using the time dependent density functional theory Becke3-Lee-Yang-Parr hybrid functional-6-31 + G (d) method. Mulliken atomic charges for each molecule have been compared with Loewdin atomic charges to analyze the molecular charge distribution and phase stability. The highest occupied molecular orbital and lowest unoccupied molecular orbital energies corresponding to the electronic transitions in the uv-visible range have been reported. Excited states have been calculated via the configuration interaction single level with a semiempirical Hamiltonian (intermediate neglect of differential overlap method, as parametrized by Zerner and co-workers). Further, two types of calculations have been performed for model systems containing single and double molecules of nCB. Furthermore, the dimer complexes during the different modes of molecular interactions have also been studied. The interaction energies of dimer complexes have been taken into consideration in order to investigate the most energetically stable configuration. These studies are helpful for understanding the role and flexibility of end chains, in particular, phase behavior and stability.

  10. Ethylbenzene Dehydrogenase and Related Molybdenum Enzymes Involved in Oxygen-Independent Alkyl Chain Hydroxylation.

    PubMed

    Heider, Johann; Szaleniec, Maciej; Sünwoldt, Katharina; Boll, Matthias

    2016-01-01

    Ethylbenzene dehydrogenase initiates the anaerobic bacterial degradation of ethylbenzene and propylbenzene. Although the enzyme is currently only known from a few closely related denitrifying bacterial strains affiliated to the Rhodocyclaceae, it clearly marks a universally occurring mechanism used for attacking recalcitrant substrates in the absence of oxygen. Ethylbenzene dehydrogenase belongs to subfamily 2 of the DMSO reductase-type molybdenum enzymes together with paralogous enzymes involved in the oxygen-independent hydroxylation of p-cymene, the isoprenoid side chains of sterols and even possibly n-alkanes; the subfamily also extends to dimethylsulfide dehydrogenases, selenite, chlorate and perchlorate reductases and, most significantly, dissimilatory nitrate reductases. The biochemical, spectroscopic and structural properties of the oxygen-independent hydroxylases among these enzymes are summarized and compared. All of them consist of three subunits, contain a molybdenum-bis-molybdopterin guanine dinucleotide cofactor, five Fe-S clusters and a heme b cofactor of unusual ligation, and are localized in the periplasmic space as soluble enzymes. In the case of ethylbenzene dehydrogenase, it has been determined that the heme b cofactor has a rather high redox potential, which may also be inferred for the paralogous hydroxylases. The known structure of ethylbenzene dehydrogenase allowed the calculation of detailed models of the reaction mechanism based on the density function theory as well as QM-MM (quantum mechanics - molecular mechanics) methods, which yield predictions of mechanistic properties such as kinetic isotope effects that appeared consistent with experimental data. PMID:26960184

  11. Cu sbnd Al sbnd Fe layered double hydroxides with CO32- and anionic surfactants with different alkyl chains in the interlayer

    NASA Astrophysics Data System (ADS)

    Trujillano, Raquel; Holgado, María Jesús; González, José Luis; Rives, Vicente

    2005-08-01

    Layered double hydroxides (LDHs), with the hydrotalcite-like structure containing Cu(II), Al(III) and Fe(III) in the layers, and different alkyl sulfonates in the interlayer, have been prepared and characterized by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Pure crystalline phases have been obtained in all cases. Upon heating, combustion of the organic chain takes place at lower temperature than the corresponding sodium salts.

  12. Alkyl rearrangement processes in organozirconium complexes. Observation of internal alkyl complexes during hydrozirconation

    SciTech Connect

    Chirik, P.J.; Day, M.W.; Labinger, J.A.; Bercaw, J.E.

    1999-11-10

    Isotopically labeled alkyl zirconocene complexes of the form (CpR{sub n}){sub 2}Zr(CH{sub 2}CDR{sub 2}{prime})(X) (CpR{sub n} = alkyl-substituted cyclopentadienyl; R{prime} = H, alkyl group; X = H, D, Me) undergo isomerization of the alkyl ligand as well as exchange with free olefin in solution under ambient conditions. Increasing the substitution on the Cp ring results in slower isomerization reactions, but these steric effects are small. In contrast, changing X has a very large effect on the rate of isomerization. Pure {sigma}-bonding ligands such as methyl and hydride promote rapid isomerization, whereas {pi}-donor ligands inhibit {beta}-H elimination and hence alkyl isomerization. For ({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}Zr(R)(Cl), internal alkyl complexes have been observed for the first time. The rate of isomerization depends on the length of the alkyl group: longer alkyl chains (heptyl, hexyl) isomerize faster than shorter chains (butyl). The transient intermediate species have been identified by a combination of isotopic labeling and {sup 1}H, {sup 2}H, and {sup 13}C NMR experiments. The solid-state structure of the zirconocene cyclopentyl chloride complex, Cp{sub 2}Zr(cyclo-C{sub 5}H{sub 9})(Cl), has been determined by X-ray diffraction.

  13. Structure-Antibacterial Activity Relationships of Imidazolium-Type Ionic Liquid Monomers, Poly(ionic liquids) and Poly(ionic liquid) Membranes: Effect of Alkyl Chain Length and Cations.

    PubMed

    Zheng, Zhiqiang; Xu, Qiming; Guo, Jiangna; Qin, Jing; Mao, Hailei; Wang, Bin; Yan, Feng

    2016-05-25

    The structure-antibacterial activity relationship between the small molecular compounds and polymers are still elusive. Here, imidazolium-type ionic liquid (IL) monomers and their corresponding poly(ionic liquids) (PILs) and poly(ionic liquid) membranes were synthesized. The effect of chemical structure, including carbon chain length of substitution at the N3 position and charge density of cations (mono- or bis-imidazolium) on the antimicrobial activities against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was investigated by determination of minimum inhibitory concentration (MIC). The antibacterial activities of both ILs and PILs were improved with the increase of the alkyl chain length and higher charge density (bis-cations) of imidazolium cations. Moreover, PILs exhibited lower MIC values relative to the IL monomers. However, the antibacterial activities of PIL membranes showed no correlation to those of their analogous small molecule IL monomers and PILs, which increased with the charge density (bis-cations) while decreasing with the increase of alkyl chain length. The results indicated that antibacterial property studies on small molecules and homopolymers may not provide a solid basis for evaluating that in corresponding polymer membranes. PMID:27145107

  14. Workshop on the Increased Use of Ethanol and Alkylates in Automotive Fuels in California

    SciTech Connect

    Rice, D W

    2001-05-04

    The goals of the Workshop are to: (1) Review the existing state of knowledge on (a) physicochemical properties, multi-media transport and fate, exposure mechanisms and (b) release scenarios associated with the production, distribution, and use of ethanol and alkylates in gasoline; (2) Identify key regulatory, environmental, and resource management issues and knowledge gaps associated with anticipated changes in gasoline formulation in California; and (3) Develop a roadmap for addressing issues/knowledge gaps.

  15. Stenotrophomonas maltophilia OleC-Catalyzed ATP-Dependent Formation of Long-Chain Z-Olefins from 2-Alkyl-3-hydroxyalkanoic Acids.

    PubMed

    Kancharla, Papireddy; Bonnett, Shilah A; Reynolds, Kevin A

    2016-08-01

    The bacterial pathway of olefin biosynthesis starts with OleA catalyzed "head-to-head" condensation of two CoA-activated long-chain fatty acids to generate (R)-2-alkyl-3-ketoalkanoic acids. A subsequent OleD-catalyzed reduction generates (2R,3S)-2-alkyl-3-hydroxyalkanoic acids. We now show that the final step in the pathway is an OleC-catalyzed ATP-dependent decarboxylative dehydration to form the corresponding Z olefins. Higher kcat /Km values were seen for substrates with longer alkyl chains. All four stereoisomers of 2-hexyl-3-hydroxydecanoic acid were shown to be substrates, and GC-MS and NMR analyses confirmed that the product in each case was (Z)-pentadec-7-ene. LC-MS analysis supported the formation of AMP adduct as an intermediate. The enzymatic and stereochemical course of olefin biosynthesis from long-chain fatty acids by OleA, OleD and OleC is now established. PMID:27238740

  16. Diacyltransferase Activity and Chain Length Specificity of Mycobacterium tuberculosis PapA5 in the Synthesis of Alkyl β-Diol Lipids

    SciTech Connect

    Touchette, Megan H.; Bommineni, Gopal R.; Delle Bovi, Richard J.; Gadbery, John; Nicora, Carrie D.; Shukla, Anil K.; Kyle, Jennifer E.; Metz, Thomas O.; Martin, Dwight W.; Sampson, Nicole S.; Miller, W. T.; Tonge, Peter J.; Seeliger, Jessica C.

    2015-09-08

    Although classified as Gram-positive bacteria, Corynebacterineae possess an asymmetric outer membrane that imparts structural and thereby physiological similarity to more distantly related Gram-negative bacteria. Like lipopolysaccharide in Gram-negative bacteria, lipids in the outer membrane of Corynebacterineae have been associated with the virulence of pathogenic species such as Mycobacterium tuberculosis (Mtb). For example, Mtb strains that lack long, branched-chain alkyl esters known as dimycocerosates (DIMs) are significantly attenuated in model infections. The resultant interest in the biosynthetic pathway of these unusual virulence factors has led to the elucidation of many of the steps leading to the final esterification of the alkyl beta-diol, phthiocerol, with branched-chain fatty acids know as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. We here show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl beta-diol substrate analogues. Applying these analogues to a series of PapA5 mutants, we also revise a model for the substrate binding within PapA5. Finally, we demonstrate that the Mtb Ser/Thr kinase PknB modifies PapA5 on three Thr residues, including two (T196, T198) located on an unresolved loop. These results clarify the DIM biosynthetic pathway and suggest possible mechanisms by which DIM biosynthesis may be regulated by the post-translational modification of PapA5.

  17. Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production.

    PubMed

    Furukawa, Tomohiro; Iimura, Kurin; Kimura, Taichi; Yamamoto, Toshiyoshi; Sakuda, Shohei

    2016-01-01

    Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control. PMID:27338472

  18. Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production

    PubMed Central

    Furukawa, Tomohiro; Iimura, Kurin; Kimura, Taichi; Yamamoto, Toshiyoshi; Sakuda, Shohei

    2016-01-01

    Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control. PMID:27338472

  19. Structure-reactivity relationships for the inhibition mechanism at the second alkyl-chain-binding site of cholesterol esterase and lipase.

    PubMed

    Lin, G; Shieh, C T; Ho, H C; Chouhwang, J Y; Lin, W Y; Lu, C P

    1999-08-01

    Alkyl-N-phenyl carbamates (2-8) (see Figure 1), alkyl-N-phenyl thiocarbamates (9-15), 2,2'-biphenyl-2-ol-2'-N-substituted carbamates (16-23), and 2, 2'-biphenyl-2-N-octadecylcarbamate-2'-N-substituted carbamates (24-31) are prepared and evaluated for their inhibition effects on porcine pancreatic cholesterol esterase and Pseudomona species lipase. All inhibitors are characterized as transient or pseudo substrate inhibitors for both enzymes. Both enzymes are not protected from inhibition and further inactivated by carbamates 2-8 and thiocarbamates 9-15 in the presence of trifluoroacetophenone. Therefore, carbamates 2-8 and thiocarbamates 9-15 are exceptions for active site binding inhibitors and are probably the second alkyl-chain binding-site-directed inhibitors for both enzymes. The inhibition data for carbamates 2-8 and thiocarbamates 9-15 are correlated with the steric constant, E(s), and the hydrophobicity constant, pi; however, the inhibition data are not correlated with the Taft substituent constant, sigma. A comparison of the inhibition data for carbamates 2-8 and thiocarbamates 9-15 toward both enzymes indicates that thiocarbamates 9-15 are more potent inhibitors than carbamates 2-8. A comparison of the inhibition data for cholesterol esterase and Pseudomona species lipase by carbamates 2-8 or thiocarbamates 9-15 indicates that cholesterol esterase is more sensitive to the E(s) and pi values than Pseudomona species lipase. The negative slope values for the logarithms of inhibition data for Pseudomona species lipase by carbamates 2-8 and thiocarbamates 9-15 versus E(s) and pi indicate that the second alkyl-chain-binding site of Pseudomona species lipase is huge, hydrophilic, compared to that of cholesterol esterase, and prefers to interact with a bulky, hydrophilic inhibitor rather than a small, hydrophobic one. On the contrary, the second alkyl-chain-binding site of cholesterol esterase prefers to bind to a small, hydrophobic inhibitor. Both enzymes are

  20. Water-AOT-alkylbenzene microemulsions: influence of alkyl chain length on structure and percolation behavior.

    PubMed

    Appel, Markus; Spehr, Tinka Luise; Wipf, Robert; Stühn, Bernd

    2012-06-15

    We study the percolation behavior of the water-in-oil (w/o) droplet phase of AOT (sodium bis[2-ethylhexyl] sulfosuccinate)-based microemulsions with different alkylbenzenes (toluene, ethylbenzene, butylbenzene or octylbenzene) as oil phase. We use microemulsions of varying composition with molar water to surfactant ratios 0≤W≤ 50 and droplet (water plus surfactant) volume fractions 10%≤φ≤50%. Using dielectric spectroscopy, a percolation transition is observed in w/o microemulsions with butylbenzene or octylbenzene. With increasing molecular weight of the alkylbenzene, the percolation temperature T(P) decreases. The structure of the microemulsions is determined by small angle X-ray scattering (SAXS). With increasing molar weight of the alkylbenzene, the stability range of the L(2) droplet phase extends to higher W. The larger amount of solubilizable water can be related to variable oil penetration of the AOT monolayer, which affects the spontaneous curvature of the surfactant shell. PMID:22446149

  1. Interaction of a long alkyl chain protic ionic liquid and water

    NASA Astrophysics Data System (ADS)

    Bodo, Enrico; Mangialardo, Sara; Capitani, Francesco; Gontrani, Lorenzo; Leonelli, Francesca; Postorino, Paolo

    2014-05-01

    A combined experimental/theoretical approach has been used to investigate the role of water in modifying the microscopic interactions characterizing the optical response of 1-butyl-ammonium nitrate (BAN) water solutions. Raman spectra, dominated by the signal from the protic ionic liquid, were collected as a function of the water content, and the corresponding spatial organization of the ionic couples, as well as their local arrangement with water molecules, was studied exploiting classical molecular dynamics calculations. High quality spectroscopic data, combined with a careful analysis, revealed that water affects the vibrational spectrum BAN in solution: as the water concentration is increased, peaks assigned to stretching modes show a frequency hardening together with a shape narrowing, whereas the opposite behavior is observed for peaks assigned to bending modes. Calculation results clearly show a nanometric spatial organization of the ionic couples that is not destroyed on increasing the water content at least within an intermediate range. Our combined results show indeed that small water concentrations even increase the local order. Water molecules are located among ionic couples and are closer to the anion than the cation, as confirmed by the computation of the number of H-bonds which is greater for water-anion than for water-cation. The whole results set thus clarifies the microscopic scenario of the BAN-water interaction and underlines the main role of the extended hydrogen bond network among water molecules and nitrate anions.

  2. Increased Chain Length Promotes Pneumococcal Adherence and Colonization

    PubMed Central

    Rodriguez, Jesse L.; Dalia, Ankur B.

    2012-01-01

    Streptococcus pneumoniae is a mucosal pathogen that grows in chains of variable lengths. Short-chain forms are less likely to activate complement, and as a consequence they evade opsonophagocytic clearance more effectively during invasive disease. When grown in human nasal airway surface fluid, pneumococci exhibited both short- and long-chain forms. Here, we determined whether longer chains provide an advantage during colonization when the organism is attached to the epithelial surface. Chain-forming mutants and the parental strain grown under conditions to promote chain formation showed increased adherence to human epithelial cells (A549 cells) in vitro. Additionally, adherence to A549 cells selected for longer chains within the wild-type strain. In vivo in a murine model of colonization, chain-forming mutants outcompeted the parental strain. Together, our results demonstrate that morphological heterogeneity in the pneumococcus may promote colonization of the upper respiratory tract by enhancing the ability of the organism to bind to the epithelial surface. PMID:22825449

  3. Structure and aggregation in the 1,3-dialkyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid family: 2. From single to double long alkyl side chains.

    PubMed

    Bernardes, Carlos E S; Shimizu, Karina; Lobo Ferreira, Ana I M C; Santos, Luís M N B F; Canongia Lopes, José N

    2014-06-19

    A systematic molecular dynamics study using large simulation boxes has been performed in order to extend the analysis of the mesoscopic segregation behavior observed in ionic liquids of the 1,3-dialkyl-imidazolium bis(trifluoromethylsulfonyl)imide homologous series, [C(n)C(mim)][Ntf2] (2 ≤ n ≤ 10, 2 ≤ m ≤ n). The analyses include the discussion of the structure factors, S(q), in the low-q range (1.6 ≤ q/nm(-1) ≤ 20); the confirmation of the periodicity of the polar network of the ionic liquid and its relation to the so-called intermediate peaks; and the characterization of the polar network and the nonpolar regions that are formed along the series using aggregate analyses by means of five different statistical tools. The analyses confirmed that the percolation of the nonpolar regions into a continuous domain occurs when the total number of carbon atoms in the alkyl chains exceeds six but that this is not a sufficient condition for the emergence of a distinct and intense prepeak. The existence of such a peak also requires that the longer alkyl chain contains more than a critical alkyl length (CAL) of five carbon atoms. PMID:24873822

  4. Effect of alkyl chain length, head group and nature of the surfactant on the hydrolysis of 1,3-benzoxazine-2,4-dione and its derivatives.

    PubMed

    Al-Ayed, Abdullah S; Ali, Mohd Sajid; Al-Lohedan, Hamad A; Al-Sulaim, Adel M; Issa, Zuheir A

    2011-09-01

    The alkaline hydrolysis of carsalam (2H-1,3-benzoxazine-2,4(3H)-dione), denoted as I, and its N-substituted derivatives i.e., N-methyl-1,3-benzoxazine-2,4-dione (II) and N-benzoyl-1,3-benzoxazine-2,4-dione (III) was studied spectrophotometrically at physiological temperature. The rate of hydrolysis was found to be independent on the substrate concentration. In case of I, the reaction was fractional order with respect to [OH(-)] while for II and III, reaction obeyed the first order kinetics. Effect of cationic surfactants with varying hydrophobic chains (cetyltrimethylammonium bromide, CTAB, tetradecyltrimethylammonium bromide, TTAB and dodecyltrimethylammonium bromide, DTAB) and with different head-group (cetyl pyridinium chloride, CPC) and anionic surfactant (sodium dodecyl sulfate, SDS) was also seen on the rate of alkaline hydrolysis of the carsalam and its derivatives. Cationic surfactants first catalyzed the rate of hydrolysis at lower concentrations followed by the inhibition at higher concentrations. The length of the alkyl chain had remarkable effect on the catalytic efficiency of the surfactants. Similarly N-substitution on substrate also increased the catalysis by micelles. The anionic surfactant SDS inhibited the rate of hydrolysis at all of the concentrations studied. The catalysis by cationic micelles followed by inhibition was treated in terms of the pseudophase ion-exchange model, while for the inhibition by SDS micelles the Menger-Portnoy model was used to fit the data. The effect of salts (NaCl, NaBr and (CH(3))(4)NBr) was also seen on the hydrolysis of II and it was found that all salts inhibited the rate of reaction. The inhibition follows the trend NaCl

  5. Increasing Capacity Exploitation in Food Supply Chains Using Grid Concepts

    NASA Astrophysics Data System (ADS)

    Volk, Eugen; Müller, Marcus; Jacob, Ansger; Racz, Peter; Waldburger, Martin

    Food supply chains today are characterized by fixed trade relations with long term contracts established between heterogeneous supply chain companies. Production and logistics capacities of these companies are often utilized in an economically inefficient manner only. In addition, increased consumer awareness in food safety issues renders supply chain management even more challenging, since integrated tracking and tracing along the whole food supply chain is needed. Facing these issues of supply chain management complexity and completely documented product quality, this paper proposes a full lifecycle solution for dynamic capacity markets based on concepts used in the field of Grid [1], like management of Virtual Organization (VO) combined with Service Level Agreement (SLA). The solution enables the cost-efficient utilization of real world capacities (e.g., production capacities or logistics facilities) by using a simple, browser-based portal. Users are able to enter into product-specific negotiations with buyers and suppliers of a food supply chain, and to obtain real-time access to product information including SLA evaluation reports. Thus, business opportunities in wider market access, process innovation, and trustworthy food products are offered for participating supply chain companies.

  6. Influence of alkyl chain length on charge transport in symmetrically substituted poly(2,5-dialkoxy- p -phenylenevinylene) polymers

    NASA Astrophysics Data System (ADS)

    Tuladhar, Sachetan M.; Sims, Marc; Kirkpatrick, James; Maher, Robert C.; Chatten, Amanda J.; Bradley, Donal D. C.; Nelson, Jenny; Etchegoin, Pablo G.; Nielsen, Christian B.; Massiot, Philippe; George, Wayne N.; Steinke, Joachim H. G.

    2009-01-01

    We report on the hole transport characteristics, as measured by time of flight, of a family of symmetrically substituted dialkoxy poly( p -phenylenevinylene) polymers with different side-chain length. As side-chain length is decreased, the magnitude of the hole mobility μh increases while the field dependence of μh becomes more positive and the temperature dependence of μh becomes stronger. For the shortest side-chain derivative studied, μh exceeds 10-4cm2V-1s-1 at electric fields greater than 105Vcm-1 . The trend in magnitude of μh with side-chain length is consistent with the expected increase in electronic wave-function overlap as interchain separation decreases, while the trends in electric-field and temperature dependences of μh are consistent with increasing site energy disorder. We show that the electrostatic contribution to the site energy difference for pairs of oligomers follows the observed trend as a function of interchain separation, although the pairwise contribution is too small to explain the data quantitatively. Nonresonant Raman spectroscopy is used to characterize the microstructure of our films. We construct spatial maps of the Raman ratio I1280/I1581 and confirm an expected decrease in average film density with side-chain extension. The structural heterogeneity in the maps is analyzed but no clear correlation is observed with transport properties, suggesting that the structural variations relevant for charge transport occur on a length scale finer than the resolution of ˜1μm .

  7. Diacyltransferase Activity and Chain Length Specificity of Mycobacterium tuberculosis PapA5 in the Synthesis of Alkyl β-Diol Lipids.

    PubMed

    Touchette, Megan H; Bommineni, Gopal R; Delle Bovi, Richard J; Gadbery, John E; Nicora, Carrie D; Shukla, Anil K; Kyle, Jennifer E; Metz, Thomas O; Martin, Dwight W; Sampson, Nicole S; Miller, W Todd; Tonge, Peter J; Seeliger, Jessica C

    2015-09-01

    Although they are classified as Gram-positive bacteria, Corynebacterineae possess an asymmetric outer membrane that imparts structural and thereby physiological similarity to more distantly related Gram-negative bacteria. Like lipopolysaccharide in Gram-negative bacteria, lipids in the outer membrane of Corynebacterineae have been associated with the virulence of pathogenic species such as Mycobacterium tuberculosis (Mtb). For example, Mtb strains that lack long, branched-chain alkyl esters known as dimycocerosates (DIMs) are significantly attenuated in model infections. The resultant interest in the biosynthetic pathway of these unusual virulence factors has led to the elucidation of many of the steps leading to the final esterification of the alkyl β-diol, phthiocerol, with branched-chain fatty acids known as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. Here, we show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl β-diol substrate analogues. By applying these analogues to a series of PapA5 mutants, we also revise a model for the substrate binding within PapA5. Finally, we demonstrate that the Mtb Ser/Thr kinases PknB and PknE modify PapA5 on three overlapping Thr residues and that a fourth Thr is unique to PknE phosphorylation. These results clarify the DIM biosynthetic pathway and indicate post-translational modifications that warrant further elucidation for their roles in the regulation of DIM biosynthesis. PMID:26271001

  8. Diacyltransferase Activity and Chain Length Specificity of Mycobacterium tuberculosis PapA5 in the Synthesis of Alkyl Beta-Diol Lipids

    PubMed Central

    Touchette, Megan H.; Bommineni, Gopal R.; Delle Bovi, Richard J.; Gadbery, John E.; Nicora, Carrie D.; Shukla, Anil K.; Kyle, Jennifer E.; Metz, Thomas O.; Martin, Dwight W.; Sampson, Nicole S.; Miller, W. Todd; Tonge, Peter J.; Seeliger, Jessica C.

    2015-01-01

    Although classified as Gram-positive bacteria, Corynebacterineae possess an asymmetric outer membrane that imparts structural and thereby physiological similarity to more distantly related Gram-negative bacteria. Like lipopolysaccharide in Gram-negative bacteria, lipids in the outer membrane of Corynebacterineae have been associated with the virulence of pathogenic species such as Mycobacterium tuberculosis (Mtb). For example, Mtb strains that lack long, branched-chain alkyl esters known as dimycocerosates (DIMs) are significantly attenuated in model infections. The resultant interest in the biosynthetic pathway of these unusual virulence factors has led to the elucidation of many of the steps leading to the final esterification of the alkyl beta-diol, phthiocerol, with branched-chain fatty acids known as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. We here show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl beta-diol substrate analogues. Applying these analogues to a series of PapA5 mutants, we also revise a model for the substrate binding within PapA5. Finally, we demonstrate that the Mtb Ser/Thr kinases PknB and PknE modify PapA5 on three overlapping Thr residues and a fourth Thr is unique to PknE phosphorylation. These results clarify the DIM biosynthetic pathway and indicate post-translational modifications that warrant further elucidation for their roles in regulation DIM biosynthesis. PMID:26271001

  9. Solid-Phase synthesis of a library constructed of aromatic phosphate, long alkyl chains and tryptophane components, and identification of potent dipeptide telomerase inhibitors.

    PubMed

    Sasaki, S; Ehara, T; Alam, M R; Fujino, Y; Harada, N; Kimura, J; Nakamura, H; Maeda, M

    2001-10-01

    Telomerase inhibitors are expected as a new candidate of therapeutic agents for cancer. Recently, we have found novel inhibitors based on the bisindole skeleton. In this study, solid-phase synthesis was applied to construct a library of inhibitors having aromatic phosphate, long alkyl chain and tryptophane components, from which a D,D-ditryptophane derivative has been identified as a new potent telomerase inhibitor with IC(50) values of 0.3 microM. A hypothetical binding model for the new inhibitors has been proposed based on the structure-activity relationship. PMID:11551754

  10. Demonstration by real-time polymerase chain reaction that cellular DNA alkylation by novel aminoindoline compounds affects expression of the protooncogene c-myc.

    PubMed

    Nelson, Stephanie M; Ferguson, Lynnette R; Denny, William A

    2005-02-01

    Aminoindolines, analogues of the potent DNA alkylating agent seco-CBI-TMI, bind to and alkylate in the minor groove of AT-rich DNA in vitro. Here we extend the in vitro mechanism of action studies by treating cells in culture and examining the DNA binding patterns within AT-rich regions of the protooncogene locus c-myc, using a real-time polymerase chain reaction (PCR) stop assay. In addition, real-time reverse transcriptase (RT) PCR is used to examine the immediate effects of drug treatment on c-myc expression. These analyses demonstrate a concentration and time dependence for DNA alkylation at the chosen sites within the c-myc locus, as well as a prompt and significant downregulation of c-myc expression. While downregulation of this important growth regulator is likely not the only consequence of aminoindoline treatment, these studies begin to address the cellular pathways that are involved in the potent cytotoxic effects observed and provide insights for the future development of anticancer drugs of this class. PMID:15720128

  11. An efficient nitration of light alkanes and the alkyl side-chain of aromatic compounds with nitrogen dioxide and nitric acid catalyzed by N-hydroxyphthalimide.

    PubMed

    Nishiwaki, Yoshiki; Sakaguchi, Satoshi; Ishii, Yasutaka

    2002-08-01

    Nitration of light alkanes and the alkyl side-chain of aromatic compounds with NO(2) and HNO(3) was successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst under relatively mild conditions. For example, the nitration of propane with NO(2) catalyzed by NHPI at 100 degrees C for 14 h gave 2-nitropropane in good yield without formation of 1-nitropropane and cleaved products such as nitroethane and nitromethane. Various aliphatic nitroalkanes, which are difficult to prepare by conventional methods, could be selectively obtained by means of the present methodology by using NHPI as the key catalyst. In addition, the side-chain nitration of alkylbenzenes such as toluene was selectively carried out to lead to alpha-nitrotoluene without the ring nitration. The present reaction provides an efficient selective method for the nitration of light alkanes and alkylbenzenes, which has been very difficult to carry out so far. PMID:12153265

  12. Quantum chemical clarification of the alkyl chain length threshold of nonionic surfactants for monolayer formation at the air/water interface.

    PubMed

    Vysotsky, Yu B; Kartashynska, E S; Belyaeva, E A; Vollhardt, D; Fainerman, V B; Miller, R

    2016-03-21

    A theoretical basis is provided for the experimental fact that for various surfactant classes the alkyl chain length threshold varies for the formation of condensed monolayers. The existence of the alkyl chain length threshold for a surfactant enabling the formation of monolayers is determined by the entropy increment to the Gibbs' energy, assessed by using the quantum chemical semiempiric method PM3. The value of the clusterization threshold is not stipulated by the surfactant solubility in water, rather by the electron-donor and electron-seeking properties of the head groups. These properties in turn impact the value of the solubility threshold for surfactants. The value of the clusterization threshold depends quadratically on the substituent constants, i.e. it is independent of whether the functional group is a donor or an acceptor of electrons. Rather it depends only on the donor or the acceptor 'force' of the substituent. The square-law dependence of the surface clusterization threshold of the amphiphile on the solubility threshold is evidenced. PMID:26957020

  13. Dielectric properties of liquid-crystal azomethine polymer with a side alkyl-substituted chain, doped with fullerene C60

    NASA Astrophysics Data System (ADS)

    Kovalev, D. S.; Kostromin, S. V.; Musteaţa, V.; Cozan, V.; Bronnikov, S. V.

    2016-04-01

    We studied the actual and imaginary components of the dielectric constant of liquid-crystal azomethine polymer with a side chain, doped with 0.5 wt % of fullerene C60, over a wide range of temperatures and frequencies; measurements were made by means of dielectric spectroscopy. By analyzing the frequency dependence of the dielectric constant, we detected the relaxation processes (α, β1, and β2) in the nanocomposite, corresponding to certain modes of molecular motion and described them by the Arrhenius equations (β1- and β2-processes) and the Vogel-Fulcher-Tamman equation (α-process). An antiplasticization effect is discovered after doping the polymer with fullerene C60, which manifests itself in increasing the glass transition temperature of the nanocomposite compared to this parameter typical of pure polymer.

  14. Hydrocarbon binding by proteins: structures of protein binding sites for ≥C10 linear alkanes or long-chain alkyl and alkenyl groups.

    PubMed

    Park, Jiyong; Pham, Hung V; Mogensen, Kristian; Solling, Theis Ivan; Bennetzen, Martin Vad; Houk, K N

    2015-01-16

    In order to identify potential de novo enzyme templates for the cleavage of C–C single bonds in long-chain hydrocarbons, we analyzed protein structures that bind substrates containing alkyl and alkenyl functional groups. A survey of ligand-containing protein structures deposited in the Protein Data Bank resulted in 874 entries, consisting of 194 unique ligands that have ≥10 carbons in a linear chain. Fatty acids and phospholipids are the most abundant types of ligands. Hydrophobic amino acids forming α-helical structures frequently line the binding pockets. Occupation of these binding sites was evaluated by calculating both the buried surface area and volume employed by the ligands; these quantities are similar to those computed for drug–protein complexes. Surface complementarity is relatively low due to the nonspecific nature of the interaction between the long-chain hydrocarbons and the hydrophobic amino acids. The selected PDB structures were annotated on the basis of their SCOP and EC identification numbers, which will facilitate design template searches based on structural and functional homologies. Relatively low surface complementarity and ∼55% volume occupancy, also observed in synthetic-host, alkane-guest systems, suggest general principles for the recognition of long-chain linear hydrocarbons. PMID:25526284

  15. Effect of heteroatom insertion at the side chain of 5-alkyl-1H-tetrazoles on their properties as catalysts for ester hydrolysis at neutral pH.

    PubMed

    Bhattacharya, Santanu; Vemula, Praveen Kumar

    2005-11-25

    [reaction: see text] Herein we introduce tetrazole and its suitably designed derivatives as powerful ester-cleaving reagents. By first performing a detailed ab initio computational study, we found that, in the side chain of 5-alkyl-1H-tetrazoles, introduction of a heteroatom (e.g., N, O, or S at the alpha-position of the tetrazole ring) raises the charge on the tetrazole nucleus significantly. All calculations have been performed using restricted Hartree-Fock (RHF) and hybrid ab initio/DFT (B3LYP) methods employing 6-31G* and 6-31+G* basis sets. To estimate the nucleophilicity of these reagents, the charges on conjugate bases of various tetrazole derivatives have been calculated using natural population (NBO) analysis in gas phase and in water. Free energy of protonation (fep) of the 1H-tetrazole derivatives (1-7), free energy of solvation, deltaG(aq), and the corresponding pKa values have been calculated by self-consistent reaction field (SCRF) methods applying the polarized continuum model (PCM). Since the calculation indicates that incorporation of heteroatom leads to enhanced nucleophilicity in their deprotonated anionic tetrazole forms, a series of 5-substituted 1H-tetrazole derivatives have been synthesized. These compounds indeed catalyze the hydrolysis of p-nitrophenyl diphenyl phosphate (PNPDPP) and p-nitrophenyl hexanoate (PNPH) efficiently in cationic cetyl trimethylammonium bromide (CTABr) micelles at pH 7.0 and 25 degrees C. The pseudo-first-order rate constants (k(obs)) were determined for each catalyst against both substrates. The experimental and theoretical results show that, to achieve better k(obs) values for the cleavage of PNPDPP and PNPH under micellar conditions, charge on the N- atom (nucleophile) of conjugate base is important. Replacing the alpha-CH2 in alkyl substituent with S (3), NH (4), or O (5) enhances the accumulation of charge on N- in conjugate bases of tetrazoles and subsequently increases their intrinsic nucleophilic reactivity

  16. Effect of alkyl chain length on the interfacial strength of surgical sealants composed of hydrophobically-modified Alaska-pollock-derived gelatins and poly(ethylene)glycol-based four-armed crosslinker.

    PubMed

    Mizuta, Ryo; Ito, Temmei; Taguchi, Tetsushi

    2016-10-01

    Surgical sealants are widely used clinically. Fibrin sealant is a commonly used sealant, but is ineffective under wet conditions during surgery. In this study, we developed surgical sealants composed of hydrophobically modified Alaska-pollock-derived gelatins (hm-ApGltns) with different alkyl chain lengths from C3 to C18 and a poly(ethylene)glycol-based 4-armed crosslinker (4S-PEG). The burst strength of the hm-ApGltns-based sealant was evaluated using a fresh porcine blood vessel and was found to increase with increasing alkyl chain length from 167±22 to 299±43mmHg when the substitution ratio of amino groups of ApGltn was around 10mol%. The maximum burst strength was observed when stearoyl-group modified ApGltn (Ste-ApGltn)/4S-PEG-based sealant was used, displaying 3-fold higher burst strength than the original ApGltn (Org-ApGltn)/4S-PEG sealant, and 10-fold higher than the commercial fibrin sealant. Ste-ApGltn/4S-PEG-based sealant was biodegraded in rat subcutaneous tissue within 8 weeks without severe inflammation. By molecular interaction analysis using surface plasmon resonance, the binding constant of Ste-ApGltn to fibronectin was found to be 9-fold higher than that of Org-ApGltn. Therefore, the developed sealant, in particular the Ste-ApGltn/4S-PEG-based sealant, has potential applications in the field of cardiovascular surgery as well as thoracic surgery. PMID:27341135

  17. Does moving up a food chain increase aggregation in parasites?

    PubMed

    Lester, R J G; McVinish, R

    2016-05-01

    General laws in ecological parasitology are scarce. Here, we evaluate data on numbers of fish parasites published by over 200 authors to determine whether acquiring parasites via prey is associated with an increase in parasite aggregation. Parasite species were grouped taxonomically to produce 20 or more data points per group as far as possible. Most parasites that remained at one trophic level were less aggregated than those that had passed up a food chain. We use a stochastic model to show that high parasite aggregation in predators can be solely the result of the accumulation of parasites in their prey. The model is further developed to show that a change in the predators feeding behaviour with age may further increase parasite aggregation. PMID:27170651

  18. Chain-Length Distribution and Hydrogen Isotopic Fraction of n-alkyl Lipids in Aquatic and Terrestrial Plants: Implications for Paleoclimate Reconstructions

    NASA Astrophysics Data System (ADS)

    Gao, L.; Littlejohn, S.; Hou, J.; Toney, J.; Huang, Y.

    2008-12-01

    Recent studies demonstrate that in lacustrine sediments, aquatic plant lipids (e.g., C22-fatty acid) record lake water D/H ratio variation, while long-chain fatty acids (C26-C32, major components of terrestrial plant leaf waxes), record D/H ratios of precipitation (especially in arid regions). However, there are insufficient literature data for the distribution and hydrogen isotopic fractionation of n-alkyl lipids in aquatic and terrestrial plants. In this study, we determined the chain-length distributions and D/H ratios of n-alkyl lipids from 17 aquatic plant species (9 emergent, 4 floating and 4 submerge species) and 13 terrestrial plant species (7 grasses and 6 trees) from Blood Pond, Massachusetts. Our results are consistent with previous studies and provide a solid basis for the paleoclimatic reconstruction using D/H ratios of aquatic and terrestrial plant biomarkers. In addition, systematic hydrogen isotopic analyses on leaf waxes, leaf, stem and soil waters from trees and grasses significantly advance our understanding of our previously observed large D/H ratio difference between tree and grass leaf waxes. Our data indicate that the observed difference is not due to differences in leaf water D/H ratios. In comparison with grasses, trees use greater proportion of D-enriched residual or stored carbohydrates (as opposed to current photosynthetic carbohydrates) for leaf wax biosynthesis, resulting in higher leaf wax D/H ratios. The residual carbohydrates are enriched in deuterium because of the preferential consumption of light-hydrogen substrates during plant metabolism.

  19. Control over the Self-Assembly Modes of Pt(II) Complexes by Alkyl Chain Variation: From Slipped to Parallel π-Stacks.

    PubMed

    Allampally, Naveen Kumar; Mayoral, María José; Chansai, Sarayute; Lagunas, María Cristina; Hardacre, Christopher; Stepanenko, Vladimir; Albuquerque, Rodrigo Q; Fernández, Gustavo

    2016-06-01

    We report the self-assembly of a new family of hydrophobic, bis(pyridyl) Pt(II) complexes featuring an extended oligophenyleneethynylene-derived π-surface appended with six long (dodecyloxy (2)) or short (methoxy (3)) side groups. Complex 2, containing dodecyloxy chains, forms fibrous assemblies with a slipped arrangement of the monomer units (dPt⋅⋅⋅Pt ≈14 Å) in both nonpolar solvents and the solid state. Dispersion-corrected PM6 calculations suggest that this organization is driven by cooperative π-π, C-H⋅⋅⋅Cl and π-Pt interactions, which is supported by EXAFS and 2D NMR spectroscopic analysis. In contrast, nearly parallel π-stacks (dPt⋅⋅⋅Pt ≈4.4 Å) stabilized by multiple π-π and C-H⋅⋅⋅Cl contacts are obtained in the crystalline state for 3 lacking long side chains, as shown by X-ray analysis and PM6 calculations. Our results reveal not only the key role of alkyl chain length in controlling self-assembly modes but also show the relevance of Pt-bound chlorine ligands as new supramolecular synthons. PMID:27113990

  20. Effect of side-chain asymmetry on the intermolecular structure and order-disorder transition in alkyl-substituted polyfluorenes

    NASA Astrophysics Data System (ADS)

    Knaapila, M.; Stepanyan, R.; Torkkeli, M.; Haase, D.; Fröhlich, N.; Helfer, A.; Forster, M.; Scherf, U.

    2016-04-01

    We study relations among the side-chain asymmetry, structure, and order-disorder transition (ODT) in hairy-rod-type poly(9,9-dihexylfluorene) (PF6) with two identical side chains and atactic poly(9-octyl-9-methyl-fluorene) (PF1-8) with two different side chains per repeat. PF6 and PF1-8 organize into alternating side-chain and backbone layers that transform into an isotropic phase at TODT(PF 6 ) and TbiODT(PF 1 -8 ) . We interpret polymers in terms of monodisperse and bidisperse brushes and predict scenarios TODTchain length above or below the average grafting distance). Calorimetry and x-ray scattering indicate the condition TODT(PF 6 ) ˜TbiODT(PF 1 -8 ) following the low grafting prediction. PF6 side chains coming from the alternating backbone layers appear as two separate layers with thickness H (PF 6 ) , whereas PF1-8 side chains appear as an indistinguishable bilayer with a half thickness Hbilayer(PF 1 -8 ) /2 ≈H (PF 6 ) . The low grafting density region is structurally possible but not certain for PF6 and confirmed for PF1-8.

  1. High Efficiency Antimicrobial Thiazolium and Triazolium Side-Chain Polymethacrylates Obtained by Controlled Alkylation of the Corresponding Azole Derivatives.

    PubMed

    Tejero, Rubén; López, Daniel; López-Fabal, Fátima; Gómez-Garcés, José L; Fernández-García, Marta

    2015-06-01

    Two series of antimicrobial polymethacrylates (PMTAs) bearing mono and bis-cationic quaternary ammonium cations (QUATs) were prepared by controlled N-alkylation of 1,3-thiazole and 1,2,3-triazole pendant groups with butyl iodide (PMTAs-BuI). The degree of quaternization (DQ) of the azole heterocycles was monitored by (1)H NMR spectroscopy over a wide range of reaction times. Spectra analysis of the (1)H NMR aromatic region allowed to characterize and quantify the different species involved and, therefore, to control the chemical composition distribution of the amphiphilic polycations. The polymer charge density and the hydrodynamic sizes were measured by zeta potential and dynamic light scattering (DLS), respectively. Consequently, the relationship between structure and antibacterial properties and toxicity was studied. Interestingly, these polyelectrolytes present excellent selective toxicity against bacteria being nonhemolytic even at low values of DQ. Furthermore, they were also evaluated for their microbial time-killing efficiency, presenting a 3 log-reduction in only 15 min. Additionally, the bacteria cell morphology treated with PMTAs-BuI was analyzed. PMID:25944495

  2. Side-chain-to-tail cyclization of ribosomally derived peptides promoted by aryl and alkyl amino-functionalized unnatural amino acids.

    PubMed

    Frost, John R; Wu, Zhijie; Lam, Yick Chong; Owens, Andrew E; Fasan, Rudi

    2016-06-28

    A strategy for the production of side-chain-to-tail cyclic peptides from ribosomally derived polypeptide precursors is reported. Two genetically encodable unnatural amino acids, bearing either an aryl or alkyl amino group, were investigated for their efficiency toward promoting the formation of medium to large-sized peptide macrocycles via intein-mediated side-chain-to-C-terminus cyclization. While only partial cyclization was observed with precursor proteins containing para-amino-phenylalanine, efficient peptide macrocyclization could be achieved using O-2-aminoethyl-tyrosine as the reactive moiety. Conveniently, the latter was generated upon quantitative, post-translational reduction of the azido-containing counterpart, O-2-azidoethyl-tyrosine, directly in E. coli cells. This methodology could be successfully applied for the production of a 12 mer cyclic peptide with enhanced binding affinity for the model target protein streptavidin as compared to the acyclic counterpart (KD: 5.1 μM vs. 22.4 μM), thus demonstrating its utility toward the creation and investigation of novel, functional macrocyclic peptides. PMID:27064594

  3. Dendronized polyimides bearing long-chain alkyl groups and their application for vertically aligned nematic liquid crystal displays.

    PubMed

    Tsuda, Yusuke; Min, Jae; Kuwahara, Renpei

    2009-11-01

    Polyimides having dendritic side chains were investigated. The terphenylene diamine monomer having a first-generation monodendron, 3,4,5-tris(n-dodecyloxy)-benzoate and the monomer having a second-generation monodendron, 3,4,5-tris[-3',4',5'-tri(n-dodecyloxy)benzyloxy]benzoate were successfully synthesized and the corresponding soluble dendritic polyimides were obtained by polycondensation with conventional tetracarboxylic dianhydride monomers such as benzophenone tertracarboxylic dianhydride (BTDA). The two-step polymerizations in NMP that is a general method for the synthesis of soluble polyimides is difficult; however, the expected dendritic polyimides can be obtained in aromatic polar solvents such as m-cresol and pyridine. The solubility of these dendoronized polyimides is characteristic; soluble in common organic solvents such as dichloromethane, chloroform, toluene and THF. These dendronized polyimides exhibited high glass transition temperatures and good thermal stability in both air and under nitrogen. Their application as alignment layers for LCDs was investigated, and it was found that these polyimides having dendritic side chains were applicable for the vertically aligned nematic liquid crystal displays (VAN-LCDs). PMID:20087476

  4. Effect of the alkyl chain length of secondary amines on the phase transfer of gold nanoparticles from water to toluene.

    PubMed

    Soliwoda, Katarzyna; Tomaszewska, Emilia; Tkacz-Szczesna, Beata; Mackiewicz, Ewelina; Rosowski, Marcin; Bald, Adam; Blanck, Christian; Schmutz, Marc; Novák, Jiří; Schreiber, Frank; Celichowski, Grzegorz; Grobelny, Jaroslaw

    2014-06-17

    In the present paper we describe a phase transfer of aqueous synthesized gold nanoparticles (AuNPs) from water to toluene using secondary amines: dioctylamine, didodecylamine, and dioctadecylamine. The effect of the hydrocarbon chain length and amount of amines on the transfer efficiency were investigated in the case of nanoparticles (NPs) with three different sizes: 5, 9, and 13 nm. Aqueous colloids were precisely characterized before the transfer process using UV-vis spectroscopy, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Nanoparticles were next transferred to toluene and characterized using UV-vis and DLS techniques. It was found that dioctadecylamine provides the most effective transfer of nanoparticles. No time-dependent changes in the NP size were observed after 12 days, showing that the dioctadecylamine-stabilized nanoparticles dispersed in toluene were stable. This indicates that long hydrocarbon chains of dioctadecylamine exhibit sufficiently hydrophobic properties of nanoparticles and consequently their good dispersibility in nonpolar solvent. PMID:24893068

  5. Thermodynamic characterization of the interaction behavior of a hydrophobically modified polyelectrolyte and oppositely charged surfactants in aqueous solution: effect of surfactant alkyl chain length.

    PubMed

    Bai, Guangyue; Nichifor, Marieta; Lopes, António; Bastos, Margarida

    2005-01-13

    We have used a precision isothermal titration microcalorimeter (ITC) to measure the enthalpy curves for the interaction of a hydrophobically modified polyelectrolyte (D40OCT30) with oppositely charged surfactants (SC(n)S) in aqueous solution. D40OCT30 is a newly synthesized polymer based on dextran having pendant N-(2-hydroxypropyl)-N,N-dimethyl-N-octylammonium chloride groups randomly distributed along the polymer backbone with degree of substitution of 28.1%. The employed anionic surfactants are sodium octyl sulfate (SC(8)S) and sodium tetradecyl sulfate (SC(14)S). Microcalorimetric results along with turbidity and kinematic viscosity measurements demonstrate systematically the thermodynamic characterization of the interaction of D40OCT30/SC(n)S. A three-dimensional diagram with the derived phase boundaries is drawn to describe the effect of the alkyl chain length of surfactant and of the ratio between surfactant and pendant groups on the interaction. A more complete picture of the interaction mechanism for D40OCT30/SC(n)S systems is proposed here. PMID:16851043

  6. Alkyl polyglucose enhancing propionic acid enriched short-chain fatty acids production during anaerobic treatment of waste activated sludge and mechanisms.

    PubMed

    Luo, Jingyang; Feng, Leiyu; Chen, Yinguang; Sun, Han; Shen, Qiuting; Li, Xiang; Chen, Hong

    2015-04-15

    Adding alkyl polyglucose (APG) into an anaerobic treatment system of waste activated sludge (WAS) was reported to remarkably improve the production of short-chain fatty acids (SCFAs), especially propionic acid via simultaneously accelerating solubilization and hydrolysis, enhancing acidification, inhibiting methanogenesis and balancing carbon to nitrogen (C/N) ratio of substrate. Not only the production of SCFAs, especially propionic acid, was significantly improved by APG, but also the feasible operation time was shortened. The SCFAs yield at 0.3 g APG per gram of total suspended solids (TSS) within 4 d was 2988 ± 60 mg chemical oxygen demand (COD) per liter, much higher than that those from sole WAS or sole WAS plus sole APG. The corresponding yield of propionic acid was 1312 ± 25 mg COD/L, 7.9-fold of sole WAS. Mechanism investigation showed that during anaerobic treatment of WAS in the presence of APG both the solubilization and hydrolysis were accelerated and the acidification was enhanced, while the methanogenesis was inhibited. Moreover, the activities of key enzymes involved in WAS hydrolysis and acidification were improved through the adjustment of C/N ratio of substrates with APG. The abundance of microorganisms responsible for organic compounds hydrolysis and SCFAs production was also observed to be greatly enhanced with APG via 454 high-throughput pyrosequencing analysis. PMID:25697695

  7. Preparation and evaluation of new Pirkle type chiral stationary phases with long alkyl chains for the separation of amino acid enantiomers derivatized with NBD-F.

    PubMed

    Kato, M; Fukushima, T; Santa, T; Nakashima, K; Nishioka, R; Imai, K

    1998-12-01

    In order to improve the high-performance liquid chromatographic separation of alpha-amino acids derivatized with the fluorogenic reagent 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) on commercially available chiral stationary phases (CSPs) such as SUMICHIRAL OA-2500(S) (CSP 1) and OA-4700 (CSP 3), the preparation of two new CSPs (CSP 2 and CSP 4) having 11-aminoundecanoic acid between the aminopropyl silica gel support and the chiral moiety in CSP 1 and CSP 3 is described. CSP 2 and CSP 4 improved both the mutual and enantiomeric separation of NBD-amino acids compared with CSP 1 and CSP 3. Thus, 17 pairs of NBD-amino acid enantiomers and NBD-glycine were separated on CSP 2 except for six NBD-amino acids (D-Asn, D-Ser, D-Gln, L-Pro, L-Ser and Gly). CSP 2 and CSP 4 also showed better enantiomeric separation of NBD-amino acid esters and amides than CSP 1 and CSP 3. It was considered that the achiral long alkyl chains in the CSPs might form a hydrophobic space which assisted the stereoselective interaction of analytes with the chiral moiety by changing the environment around the chiral moiety. On CSP 1 and CSP 2, NBD-beta-amino acid was also enantiomerically separated. PMID:10435350

  8. Chain architecture and micellization: A mean-field coarse-grained model for poly(ethylene oxide) alkyl ether surfactants

    SciTech Connect

    García Daza, Fabián A.; Mackie, Allan D.; Colville, Alexander J.

    2015-03-21

    Microscopic modeling of surfactant systems is expected to be an important tool to describe, understand, and take full advantage of the micellization process for different molecular architectures. Here, we implement a single chain mean field theory to study the relevant equilibrium properties such as the critical micelle concentration (CMC) and aggregation number for three sets of surfactants with different geometries maintaining constant the number of hydrophobic and hydrophilic monomers. The results demonstrate the direct effect of the block organization for the surfactants under study by means of an analysis of the excess energy and entropy which can be accurately determined from the mean-field scheme. Our analysis reveals that the CMC values are sensitive to branching in the hydrophilic head part of the surfactant and can be observed in the entropy-enthalpy balance, while aggregation numbers are also affected by splitting the hydrophobic tail of the surfactant and are manifested by slight changes in the packing entropy.

  9. Binary functionalization of H:Si(111) surfaces by alkyl monolayers with different linker atoms enhances monolayer stability and packing.

    PubMed

    Arefi, Hadi H; Nolan, Michael; Fagas, Giorgos

    2016-05-14

    Alkyl monolayer modified Si forms a class of inorganic-organic hybrid materials with applications across many technologies such as thin-films, fuel/solar-cells and biosensors. Previous studies have shown that the linker atom, through which the monolayer binds to the Si substrate, and any tail group in the alkyl chain, can tune the monolayer stability and electronic properties. In this paper we study the H:Si(111) surface functionalized with binary SAMs: these are composed of alkyl chains that are linked to the surface by two different linker groups. Aiming to enhance SAM stability and increase coverage over singly functionalized Si, we examine with density functional theory simulations that incorporate vdW interactions, a range of linker groups which we denote as -X-(alkyl) with X = CH2, O(H), S(H) or NH(2) (alkyl = C6 and C12 chains). We show how the stability of the SAM can be enhanced by adsorbing alkyl chains with two different linkers, e.g. Si-[C, NH]-alkyl, through which the adsorption energy is increased compared to functionalization with the individual -X-alkyl chains. Our results show that it is possible to improve stability and optimum coverage of alkyl functionalized SAMs linked through a direct Si-C bond by incorporating alkyl chains linked to Si through a different linker group, while preserving the interface electronic structure that determines key electronic properties. This is important since any enhancement in stability and coverage to give more densely packed monolayers will result in fewer defects. We also show that the work function can be tuned within the interval of 3.65-4.94 eV (4.55 eV for bare H:Si(111)). PMID:27109872

  10. Chemistry of anthracene-acetylene oligomers XXV: on-surface chirality of a self-assembled molecular network of a fan-blade-shaped anthracene-acetylene macrocycle with a long alkyl chain.

    PubMed

    Tsuya, Takuya; Iritani, Kohei; Tahara, Kazukuni; Tobe, Yoshito; Iwanaga, Tetsuo; Toyota, Shinji

    2015-03-27

    An anthracene cyclic dimer with two different linkers and a dodecyl group was synthesized by means of coupling reactions. The calculated structure had a planar macrocyclic π core and a linear alkyl chain. Scanning tunneling microscopy observations at the 1-phenyloctane/graphite interface revealed that the molecules formed a self-assembled monolayer that consisted of linear striped bright and dark bands. In each domain, the molecular network consisted of either Re or Si molecules that differed in the two-dimensional chirality about the macrocyclic faces, which led to a unique conglomerate-type self-assembly. The molecular packing mode and the conformation of the alkyl chains are discussed in terms of the intermolecular interactions and the interactions between the molecules and the graphite surface with the aid of MM3 simulations of a model system. PMID:25688524

  11. How to Increase Value in the Footwear Supply Chain

    NASA Astrophysics Data System (ADS)

    Fornasiero, Rosanna; Tescaro, Mauro; Scarso, Enrico; Gottardi, Giorgio

    The Lean approach has been implemented in many different sectors as a methodology to improve industrial performance at company level. In the latest years this approach has been further developed in literature and in practice to integrate the principles of agility, adaptability and the mass customization paradigm where product and services have to be designed together to meet specific requirements, and where value originated by the supply chain enhance the value of single company thanks to the use of ICT and remote control. In this paper we analyze the Beyond-Lean paradigm and propose a path for companies in the footwear sector to improve their performance based on high-value-added products and processes. A detailed process analysis based on Value Stream Mapping is used to define criticalities and suggest improvements paths both at technological and organizational level.

  12. Selective Ni-P electroless plating on photopatterned cationic adsorption films influenced by alkyl chain lengths of polyelectrolyte adsorbates and additive surfactants.

    PubMed

    Nakagawa, Masaru; Nawa, Nozomi; Iyoda, Tomokazu

    2004-10-26

    We demonstrated that the photopatterned single-layer adsorption film of poly(1-dodecyl-4-pyridinium bromide) on a silica surface was available for a template of nickel-phosphorus (Ni-P) electroless plating through sensitization with a SnCl(2) aqueous solution and activation with a PdCl(2) aqueous solution. Four kinds of poly(1-alkyl-4-vinylpyridinium halide)s bearing methyl, propyl, hexyl, and dodecyl groups were prepared. The cationic polymers were adsorbed by a negatively charged silica surface from their solutions, to form single-layer adsorption films exhibiting desorption-resistance toward deionized water and ethanol. The organic adsorption films could be decomposed completely by exposure to 172 nm deep-UV light. The formation and decomposition of the single-layer films were confirmed by deep-UV absorption spectral measurement and zeta-potential measurement. Ni-P electroless plating was carried out on the photopatterned adsorption films, using three types of SnO(x) colloidal materials without and with cationic or anionic surfactant as catalyst precursors in the sensitization step. In the case of the negatively charged SnO(x) colloids surrounded by anionic surfactant, Ni-deposition took place preferentially on the cationic adsorption films remaining in unexposed regions. The Ni-deposition was accelerated significantly on the cationic adsorption film bearing dodecyl groups. It was obvious by ICP-AES analyses that the hydrophobic long-chain dodecyl groups in the adsorption film could promote the adsorption of the negative SnO(x) colloids on the film surface, followed by much nucleus formation of zerovalent Pd catalysts useful for the electroless plating. The result of our experiment clearly showed that, in addition to electrostatic interaction, van der Waals interaction generating between the hydrophobic long-chain hydrocarbons of the adsorption film and the surfactant improved significantly the adsorption stability of the SnO(x) colloids, resulting in highly

  13. A short-chain alkyl derivative of Rhodamine 19 acts as a mild uncoupler of mitochondria and a neuroprotector.

    PubMed

    Khailova, Ljudmila S; Silachev, Denis N; Rokitskaya, Tatyana I; Avetisyan, Armine V; Lyamsaev, Konstantin G; Severina, Inna I; Il'yasova, Tatyana M; Gulyaev, Mikhail V; Dedukhova, Vera I; Trendeleva, Tatyana A; Plotnikov, Egor Y; Zvyagilskaya, Renata A; Chernyak, Boris V; Zorov, Dmitry B; Antonenko, Yuri N; Skulachev, Vladimir P

    2014-10-01

    Limited uncoupling of oxidative phosphorylation is known to be beneficial in various laboratory models of diseases. The search for cationic uncouplers is promising as their protonophorous effect is self-limiting because these uncouplers lower membrane potential which is the driving force for their accumulation in mitochondria. In this work, the penetrating cation Rhodamine 19 butyl ester (C4R1) was found to decrease membrane potential and to stimulate respiration of mitochondria, appearing to be a stronger uncoupler than its more hydrophobic analog Rhodamine 19 dodecyl ester (C12R1). Surprisingly, C12R1 increased H(+) conductance of artificial bilayer lipid membranes or induced mitochondria swelling in potassium acetate with valinomycin at concentrations lower than C4R1. This paradox might be explained by involvement of mitochondrial proteins in the uncoupling action of C4R1. In experiments with HeLa cells, C4R1 rapidly and selectively accumulated in mitochondria and stimulated oligomycin-sensitive respiration as a mild uncoupler. C4R1 was effective in preventing oxidative stress induced by brain ischemia and reperfusion in rats: it suppressed stroke-induced brain swelling and prevented the decline in neurological status more effectively than C12R1. Thus, C4R1 seems to be a promising example of a mild uncoupler efficient in treatment of brain pathologies related to oxidative stress. PMID:25038514

  14. Polyimides with pendant alkyl groups

    NASA Technical Reports Server (NTRS)

    Jensen, B. J.; Young, P. R.

    1982-01-01

    The effect on selected polyimide properties when pendant alkyl groups were attached to the polymer backbone was investigated. A series of polymers were prepared using benzophenone tetracarboxylic acid dianhydride (BTDA) and seven different p-alkyl-m,p'-diaminobenzophenone monomers. The alkyl groups varied in length from C(1) (methyl) to C(9) (nonyl). The polyimide prepared from BTDA and m,p'-diaminobenzophenone was included as a control. All polymers were characterized by various chromatographic, spectroscopic, thermal, and mechanical techniques. Increasing the length of the pendant alkyl group resulted in a systematic decrease in glass transition temperature (Tg) for vacuum cured films. A 70 C decrease in Tg to 193 C was observed for the nonyl polymer compared to the Tg for the control. A corresponding systematic increase in Tg indicative of crosslinking, was observed for air cured films. Thermogravimetric analysis revealed a slight sacrifice in thermal stability with increasing alkyl length. No improvement in film toughness was observed.

  15. Ionic liquids as refolding additives: N'-alkyl and N'-(omega-hydroxyalkyl) N-methylimidazolium chlorides.

    PubMed

    Lange, Christian; Patil, Ganesh; Rudolph, Rainer

    2005-10-01

    The purpose of this work was to investigate the influence of a series of N'-alkyl and N'-(omega-hydroxy-alkyl)-N-methylimidazolium chlorides on the renaturation of two model proteins, namely hen egg white lysozyme and the single-chain antibody fragment ScFvOx. All tested ionic liquids acted as refolding enhancers, with varying efficacies and efficiencies. The results of the refolding screening could be interpreted by taking into account the effect of the studied ionic liquids on protein aggregation, together with the systematic variations of their influence on the stability of native proteins in solution. More hydrophobic imidazolium cations carrying longer alkyl chains were increasingly destabilizing, while terminal hydroxylation of the alkyl chain made the salts more compatible with protein stability. The studied ionic liquids can be classified as preferentially bound, slightly to moderately chaotropic cosolvents for proteins. PMID:16195554

  16. Synthesis and Antioxidant Activity of Alkyl Nitroderivatives of Hydroxytyrosol.

    PubMed

    Gallardo, Elena; Palma-Valdés, Rocío; Sarriá, Beatriz; Gallardo, Irene; de la Cruz, José P; Bravo, Laura; Mateos, Raquel; Espartero, José L

    2016-01-01

    A series of alkyl nitrohydroxytyrosyl ether derivatives has been synthesized from free hydroxytyrosol (HT), the natural olive oil phenol, in order to increase the assortment of compounds with potential neuroprotective activity in Parkinson's disease. In this work, the antioxidant activity of these novel compounds has been evaluated using Ferric Reducing Antioxidant Power (FRAP), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and Oxygen Radical Scavenging Capacity (ORAC) assays compared to that of nitrohydroxytyrosol (NO₂HT) and free HT. New compounds showed variable antioxidant activity depending on the alkyl side chain length; compounds with short chains (2-4 carbon atoms) maintained or even improved the antioxidant activity compared to NO₂HT and/or HT, whereas those with longer side chains (6-8 carbon atoms) showed lower activity than NO₂HT but higher than HT. PMID:27213306

  17. Reducing Escape Behavior and Increasing Task Completion with Functional Communication Training, Extinction, and Response Chaining.

    ERIC Educational Resources Information Center

    Lalli, Joseph S.; And Others

    1995-01-01

    Functional communication training, extinction, and response chaining decreased escape-maintained aberrant behavior and increased task participation of 3 youth, ages 10 through 15, with moderate mental retardation, 2 of whom also had autism. Task escape was contingent on verbally responding and completing task steps. Behavior chaining also…

  18. Ion-Free and Ion-Pairing Assemblies of Anion-Responsive π-Electronic Systems Possessing Directly Linked Alkyl Chains.

    PubMed

    Haketa, Yohei; Katayama, Daisuke; Fukunaga, Shinya; Bando, Yuya; Sakurai, Tsuneaki; Matsuda, Wakana; Seki, Shu; Maeda, Hiromitsu

    2016-07-20

    Alkyl-substituted pyrrole-based anion-responsive π-electronic systems formed supramolecular gels and liquid crystals through effective π-π stacking and van der Waals interactions. The addition of chloride as a planar cation salt afforded ion-pairing assemblies as soft materials comprising planar receptor-Cl(-) complexes and the cation. PMID:27304212

  19. Structure-activity studies on organoselenium alkylating agents.

    PubMed

    Kang, S I; Spears, C P

    1990-01-01

    A variety of organoselenium alkylating agents were synthesized, using 2-hydroxyethyl and 3-hydroxypropyl selenocyanate intermediates, and studied to determine their chemical reactivities with 4-(4-nitrobenzyl)pyridine (NBP) and cytotoxicities against CCRF-CEM, L1210/0, and L1210/L-PAM cells. The comparison between the 2-chloroethyl sulfides and selenides 1-4 revealed the markedly enhanced nucleophilicity of selenium (Se) over sulfur (S) by two or more orders of magnitude. This finding indicates that a major consideration in the design of antitumor alkylating organoselenides is the reactivity of selenium. A Taft plot of the experimental first-order rate constant, knbp, and sigma* in a series of 2-chloroethylseleno compounds gave a slope of -1.73 (rho*), with the exception of 2-chloroethyl 2-nitrophenyl selenide (10). The anomalous behavior of 10 is explained in terms of the ortho-nitro stabilization effect directly interacting with the selenium atom of ethyleneselenonium ion to form a 5-membered cyclic intermediate. In the same series, a 5000-fold difference in alkylating reactivity offered only a sixfold variation in cytotoxicity against CCRF-CEM cells. Increasing the alkylating chain length from ethlene to propylene units markedly reduced alkylating reactivities. In the CH3Se(CH2)n Cl series, 16 (n = 3) was 1.5 X 10(5) times slower than 2 (n = 2) in NBP alkylation, revealing that 3-chloro-n-propyl selenides are not chemically reactive enough to be biological alkylating agents despite the presence of the highly nucleophilic selenium atom. Replacement of chloride with mesylate in 3-substituted propyl selenides, such as 17 and 20, restored desirable reactivities and cytotoxicities. PMID:2313578

  20. Effects of Increasing Seawater Carbon Dioxide Concentrations on Chain Formation of the Diatom Asterionellopsis glacialis

    PubMed Central

    Barcelos e Ramos, Joana; Schulz, Kai Georg; Brownlee, Colin; Sett, Scarlett; Azevedo, Eduardo Brito

    2014-01-01

    Diatoms can occur as single cells or as chain-forming aggregates. These two strategies affect buoyancy, predator evasion, light absorption and nutrient uptake. Adjacent cells in chains establish connections through various processes that determine strength and flexibility of the bonds, and at distinct cellular locations defining colony structure. Chain length has been found to vary with temperature and nutrient availability as well as being positively correlated with growth rate. However, the potential effect of enhanced carbon dioxide (CO2) concentrations and consequent changes in seawater carbonate chemistry on chain formation is virtually unknown. Here we report on experiments with semi-continuous cultures of the freshly isolated diatom Asterionellopsis glacialis grown under increasing CO2 levels ranging from 320 to 3400 µatm. We show that the number of cells comprising a chain, and therefore chain length, increases with rising CO2 concentrations. We also demonstrate that while cell division rate changes with CO2 concentrations, carbon, nitrogen and phosphorus cellular quotas vary proportionally, evident by unchanged organic matter ratios. Finally, beyond the optimum CO2 concentration for growth, carbon allocation changes from cellular storage to increased exudation of dissolved organic carbon. The observed structural adjustment in colony size could enable growth at high CO2 levels, since longer, spiral-shaped chains are likely to create microclimates with higher pH during the light period. Moreover increased chain length of Asterionellopsis glacialis may influence buoyancy and, consequently, affect competitive fitness as well as sinking rates. This would potentially impact the delicate balance between the microbial loop and export of organic matter, with consequences for atmospheric carbon dioxide. PMID:24618939

  1. Effects of increasing seawater carbon dioxide concentrations on chain formation of the diatom Asterionellopsis glacialis.

    PubMed

    Barcelos e Ramos, Joana; Schulz, Kai Georg; Brownlee, Colin; Sett, Scarlett; Azevedo, Eduardo Brito

    2014-01-01

    Diatoms can occur as single cells or as chain-forming aggregates. These two strategies affect buoyancy, predator evasion, light absorption and nutrient uptake. Adjacent cells in chains establish connections through various processes that determine strength and flexibility of the bonds, and at distinct cellular locations defining colony structure. Chain length has been found to vary with temperature and nutrient availability as well as being positively correlated with growth rate. However, the potential effect of enhanced carbon dioxide (CO2) concentrations and consequent changes in seawater carbonate chemistry on chain formation is virtually unknown. Here we report on experiments with semi-continuous cultures of the freshly isolated diatom Asterionellopsis glacialis grown under increasing CO2 levels ranging from 320 to 3400 µatm. We show that the number of cells comprising a chain, and therefore chain length, increases with rising CO2 concentrations. We also demonstrate that while cell division rate changes with CO2 concentrations, carbon, nitrogen and phosphorus cellular quotas vary proportionally, evident by unchanged organic matter ratios. Finally, beyond the optimum CO2 concentration for growth, carbon allocation changes from cellular storage to increased exudation of dissolved organic carbon. The observed structural adjustment in colony size could enable growth at high CO2 levels, since longer, spiral-shaped chains are likely to create microclimates with higher pH during the light period. Moreover increased chain length of Asterionellopsis glacialis may influence buoyancy and, consequently, affect competitive fitness as well as sinking rates. This would potentially impact the delicate balance between the microbial loop and export of organic matter, with consequences for atmospheric carbon dioxide. PMID:24618939

  2. Theory Of Alkyl Terminated Silicon Quantum Dots

    SciTech Connect

    Reboredo, F; Galli, G

    2004-08-19

    We have carried out a series of ab-initio calculations to investigate changes in the optical properties of Si quantum dots as a function of surface passivation. In particular, we have compared hydrogen passivated dots with those having alkyl groups at the surface. We find that, while on clusters with reconstructed surfaces a complete alkyl passivation is possible, steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. In addition, our calculations show that steric repulsion may have a dominant effect in determining the surface structure, and eventually the stability of alkyl passivated clusters, with results dependent on the length of the carbon chain. Alkyl passivation weakly affects optical gaps of silicon quantum dots, while it substantially decreases ionization potentials and electron affinities and affect their excited state properties. On the basis of our results we propose that alkyl terminated quantum dots may be size selected taking advantage of the change in ionization potential as a function of the cluster size.

  3. Catalytic alkylation apparatus

    SciTech Connect

    Hann, P.D.; VanPool, J.

    1989-09-05

    This patent describes an apparatus. It comprises alkylation reactor means for producing alkylate product; acid catalyst settler means having an upper portion, an intermediate portion and a lower portion; means for withdrawing alkylate product from the alkylation reactor means and for providing alkylate product from the alkylation reactor means to a point of introduction in the intermediate portion of the acid catalyst settler means; and means for establishing a temperature gradient in the upper the gas lines to the detector so that a flow rate of a sample gas passing through the detector is constant.

  4. Synthesis, antibacterial and antioxidant activities of new 1-alkyl-4-(1-alkyl-4-oxo-1,4-dihydroquinolin-2-yl)pyridinium bromides.

    PubMed

    Kahriman, Nuran; Yaylı, Büşra; Aktaş, Ayça; Iskefiyeli, Zeynep; Beriş, Fatih Şaban; Yaylı, Nurettin

    2013-11-01

    New 1-alkyl-4-(1-alkyl-4-oxo-1,4-dihydroquinolin-2-yl)pyridinium bromides (3a-k) were synthesized from 1,4'-diazaflavone [2-pyridin-4-ylquinolin-4(1H)-one] and evaluated for antibacterial and antioxidant activities. A rapid one-pot preparation of 1,4'-diazaflavone (2) was done from 2'-amino substituted chalcone (1) by intramolecular Michael addition using solvent-free microwave heating. New N,N'-dialkyl substituted (C₅-C₁₅) 1,4'-diazaflavonium bromides were synthesized from compound 2 with corresponding alkyl halides. Compounds 3a-k were active against six bacteria (MIC: 7.8-500.0 μg/mL). They also showed good antioxidant activities in DPPH scavenging (SC₅₀: 45-133 μg/mL) and ferric reducing/antioxidant power (14-141 μM TEAC) tests. The biological activities decreased as alkyl chain length increased. The reason behind the obvious negative effect of alkyl chain elongation is unclear and requires investigations about the intermolecular interactions of these pyridinium salts with bioassay components. PMID:24077525

  5. Mastitis: I. In vitro antimicrobial activity of alkyl amines against mastitic bacteria.

    PubMed

    Culler, M D; Bitman, J; Thompson, M J; Robbins, W E; Dutky, S R

    1979-04-01

    The activities of branched and straight chain amines (10 to 18 carbons chain length) were compared in inhibiting the growth of five microorganisms that cause about 95% of bovine mastitis. Three gram-positive (Streptococcus agalactiae, Streptococcus uberis, Staphylococcus aureus) and two gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria were used in a trypticase soy broth tube culture growth assay. Sixty-two compounds were screened at concentrations of 200, 100, 50, 25, 10, 5, and 1 ppm in broth culture to determine the effective minimum inhibitory concentration. Alkyl secondary N-substituted monoethyl [CH3(CH2)nNHCH2CH3] and tertiary N,N-substituted dimethyl [CH3(CH2) nN(CH3)2] amines with chain lengths of 11 to 14 carbon atoms were active against both gram-positive and gram-negative organisms. Antimicrobial activity against gram-positive organisms increased with increasing chain length and carbon-14 to 18 amines were active at 1 to 5 ppm. The carbon-11 to 13 alkyl amines were most active against gram-positive organisms; longer chain amines (more than 14 carbons) were inactive. Branching of the alkyl chain caused a loss of activity against gram-negative but not against gram-positive bacteria. Antimicrobial testing of monoamines, polyamines, and the influence of order substituents were investigated to correlate structure-acitivity relationships. PMID:379061

  6. Alkyl phosphonic acids and sulfonic acids in the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, George W.; Onwo, Wilfred M.; Cronin, John R.

    1992-01-01

    Homologous series of alkyl phosphonic acids and alkyl sulfonic acids, along with inorganic orthophosphate and sulfate, are identified in water extracts of the Murchison meteorite after conversion to their t-butyl dimethylsilyl derivatives. The methyl, ethyl, propyl, and butyl compounds are observed in both series. Five of the eight possible alkyl phosphonic acids and seven of the eight possible alkyl sulfonic acids through C4 are identified. Abundances decrease with increasing carbon number as observed of other homologous series indigenous to Murchison. Concentrations range downward from approximately 380 nmol/gram in the alkyl sulfonic acid series, and from 9 nmol/gram in the alkyl phosphonic acid series.

  7. Dielectric relaxation study of mixtures of alkyl methacrylates and 1-alcohols using time-domain reflectometry

    NASA Astrophysics Data System (ADS)

    Sivagurunathan, P.; Dharmalingam, K.; Ramachandran, K.; Prabhakar Undre, B.; Khirade, P. W.; Mehrotra, S. C.

    2006-05-01

    Dielectric relaxation measurements on alkyl methacrylates (methyl methacrylate, ethyl methacrylate and butyl methacrylate) with 1-alcohols (1-propanol, 1-pentanol, 1-heptanol, 1-octanol and 1-decanol) have been carried out using time-domain reflectometry (TDR) over the frequency range 10 MHz to 20 GHz at 303 K for different concentrations of alcohols. The dielectric parameters, namely the static dielectric constant (ɛ0), the dielectric constant at microwave frequencies (ɛ∞) and the relaxation time (τ) were determined. The Kirkwood correlation factor, which contains information regarding solute-solvent interaction and corresponding structural information, the excess permittivity and the excess inverse relaxation time were also determined. The values of the static dielectric constant and the relaxation time increase with the percentage of alkyl methacrylates in the alcohol, whereas the static dielectric constant decreases and the relaxation time increases with an increase in the alkyl chain length of both the methacrylates and the alcohols.

  8. Repair-deficient 3-methyladenine DNA glycosylase homozygous mutant mouse cells have increased sensitivity to alkylation-induced chromosome damage and cell killing.

    PubMed Central

    Engelward, B P; Dreslin, A; Christensen, J; Huszar, D; Kurahara, C; Samson, L

    1996-01-01

    In Escherichia coli, the repair of 3-methyladenine (3MeA) DNA lesions prevents alkylation-induced cell death because unrepaired 3MeA blocks DNA replication. Whether this lesion is cytotoxic to mammalian cells has been difficult to establish in the absence of 3MeA repair-deficient cell lines. We previously isolated and characterized a mouse 3MeA DNA glycosylase cDNA (Aag) that provides resistance to killing by alkylating agents in E. coli. To determine the in vivo role of Aag, we cloned a large fragment of the Aag gene and used it to create Aag-deficient mouse cells by targeted homologous recombination. Aag null cells have no detectable Aag transcripts or 3MeA DNA glycosylase activity. The loss of Aag renders cells significantly more sensitive to methyl methanesulfonate-induced chromosome damage, and to cell killing induced by two methylating agents, one of which produces almost exclusively 3MeAs. Aag null embryonic stem cells become sensitive to two cancer chemotherapeutic alkylating agents, namely 1,3-bis(2-chloroethyl)-1-nitrosourea and mitomycin C, indicating that Aag status is an important determinant of cellular resistance to these agents. We conclude that this mammalian 3MeA DNA glycosylase plays a pivotal role in preventing alkylation-induced chromosome damage and cytotoxicity. Images PMID:8631315

  9. Alkyl Caffeates Improve the Antioxidant Activity, Antitumor Property and Oxidation Stability of Edible Oil

    PubMed Central

    Wang, Jun; Gu, Shuang-Shuang; Pang, Na; Wang, Fang-Qin; Pang, Fei; Cui, Hong-Sheng; Wu, Xiang-Yang; Wu, Fu-An

    2014-01-01

    Caffeic acid (CA) is distributed widely in nature and possesses strong antioxidant activity. However, CA has lower solubility in non-polar media, which limits its application in fat-soluble food. To increase the lipophilicity of natural antioxidant CA, a series of alkyl caffeates were synthesized and their antioxidant and antitumor activities were investigated. The antioxidant parameters, including the induction period, acid value and unsaturated fatty acid content, of the alkyl caffeates in edible oil were firstly investigated. The results indicated that alkyl caffeates had a lower DPPH IC50 (14–23 µM) compared to CA, dibutyl hydroxy toluene (BHT) and Vitamin C (24–51 µM), and significantly inhibited four human cancer cells (SW620, SW480, SGC7901 and HepG2) with inhibition ratio of 71.4–78.0% by a MTT assay. With regard to the induction period and acid value assays, methyl and butyl caffeates had higher abilities than BHT to restrain the oxidation process and improve the stability of edible oil. The addition of ethyl caffeate to oil allowed maintenance of a higher unsaturated fatty acid methyl ester content (68.53%) at high temperatures. Overall, the alkyl caffeats with short chain length (n<5) assessed better oxidative stability than those with long chain length. To date, this is the first report to the correlations among the antioxidant activity, anticancer activity and oxidative stability of alkyl caffeates. PMID:24760050

  10. Introduction of Peripheral Carboxylates to Decrease the Charge on Tm(3+) DOTAM-Alkyl Complexes: Implications for Detection Sensitivity and in Vivo Toxicity of PARACEST MRI Contrast Agents.

    PubMed

    Suchý, Mojmír; Milne, Mark; Elmehriki, Adam A H; McVicar, Nevin; Li, Alex X; Bartha, Robert; Hudson, Robert H E

    2015-08-27

    A series of structurally modified Tm(3+) DOTAM-alkyl complexes as potential PARACEST MRI contrast agents has been synthesized with the aim to decrease the overall positive charge associated with these molecules and increase their biocompatibility. Two types of structural modification have been performed, an introduction of terminal carboxylate arms to the alkyl side chains and a conjugation of one of the alkyl side chains with aspartic acid. Detailed evaluation of the magnetic resonance imaging chemical exchange contrast associated with the structurally modified contrast agents has been performed. In contrast to the acutely toxic Tm(3+) DOTAM-alkyl complexes, the structurally modified compounds were found to be tolerated well during in vivo MRI studies in mice; however, only the aspartic acid modified chelates produced an amide proton-based PARACEST signal. PMID:26214576

  11. Physicochemical and thermal properties for a series of 1-alkyl-4-methyl-1,2,4-triazolium bis(trifluoromethylsulfonyl)imide ionic liquids.

    PubMed

    De La Hoz, Andreah T; Brauer, Ulises G; Miller, Kevin M

    2014-08-21

    Physicochemical properties and long-term thermal stabilities are reported for a series of 1-alkyl-4-methyl-1,2,4-triazolium [NTf2] ionic liquids, and a Walden plot analysis was conducted in order to determine the ionicity of these materials. In general, viscosities were found to increase with increasing alkyl chain length while densities and molar conductivities were found to decrease. The 1,2,4-triazolium ionic liquids were classified as "good" ionic liquids after analysis of the Walden plot; however, they did not perform as well as the standard imidazolium ionic liquid [bmim][NTf2]. Thermal properties from DSC and TGA experiments were also completed. 1,2,4-Triazolium ionic liquids with an alkyl chain length of octyl (C8) or less exhibited a single Tg transition below -70 °C; however, the decyl (C10) and dodecyl (C12) systems exhibited a Tm value. No correlation between Tonset or Td5% and alkyl chain length was observed during short-term, temperature-ramped TGA experiments. However, long-term, isothermal TGA studies indicated a general increase in T0.01/10 value as the alkyl chain length increased. Both short- and long-term TGA studies indicated that the 1,2,4-triazolium ionic liquids were not as thermally stable as the model imidazolium ionic liquid [bmim][NTf2]. PMID:25079782

  12. Hydrocarbon adsorption in an aqueous environment: A computational study of alkyls on Cu(111).

    PubMed

    Montemore, Matthew M; Andreussi, Oliviero; Medlin, J Will

    2016-08-21

    Hydrocarbon chains are important intermediates in various aqueous-phase surface processes, such as CO2 electroreduction, aqueous Fischer-Tropsch synthesis, and aqueous phase reforming of biomass-derived molecules. Further, the interaction between water and adsorbed hydrocarbons represents a difficult case for modern computational methods. Here, we explore various methods for calculating the energetics of this interaction within the framework of density functional theory and explore trade-offs between the use of low water coverages, molecular dynamics approaches, and minima hopping for identification of low energy structures. An effective methodology for simulating low temperature processes is provided by using a unit cell in which the vacuum space is filled with water, employing the minima hopping algorithm to search for low-lying minima, and including dispersion (van der Waals) interactions. Using this methodology, we show that a high coverage of adsorbed alkyls is destabilized by the presence of water, while a low coverage of alkyls is stabilized. Solvation has a small effect on the energetics of hydrocarbon chain growth, generally decreasing its favorability at low temperatures. We studied higher temperatures by running molecular dynamics simulations starting at the minima found by the minima hopping algorithm and found that increased temperatures facilitate chain growth. The self-consistent continuum solvation method effectively describes the alkyl-water interaction and is in general agreement with the explicit solvation results in most cases, but care should be taken at high alkyl coverage. PMID:27544118

  13. Ischemia/reperfusion-induced myosin light chain 1 phosphorylation increases its degradation by matrix metalloproteinase-2

    PubMed Central

    Cadete, Virgilio J. J.; Sawicka, Jolanta; Jaswal, Jagdip; Lopaschuk, Gary D.; Schulz, Richard; Szczesna-Cordary, Danuta; Sawicki, Grzegorz

    2012-01-01

    Summary Degradation of myosin light chain 1 (MLC1) by matrix metalloproteinase-2 (MMP-2) during myocardial ischemia/reperfusion (I/R) injury has been established. However, the exact mechanisms controlling this process remain unknown. I/R increases the phosphorylation of MLC1, but the consequences of this modification are not known. We hypothesized that phosphorylation of MLC1 plays an important role in its degradation by MMP-2. To examine this, isolated perfused rat hearts were subjected to 20 min global ischemia followed by 30 min of aerobic reperfusion. I/R increased phosphorylation of MLC1 (as measured by mass spectrometry). If hearts were subjected to I/R in the presence of ML-7 (a myosin light chain kinase (MLCK) inhibitor) or doxycycline (a MMP inhibitor) an improved recovery of contractile function was seen compared to aerobic hearts and MLC1 was protected from degradation. Enzyme kinetic studies revealed an increased affinity of MMP-2 for the phosphorylated form of MLC1 compared to non-phosphorylated MLC1. We conclude that MLC1 phosphorylation is important mechanism controlling the intracellular action of MMP-2 and promoting the degradation of MLC1. These results further support previous findings implicating posttranslational modifications of contractile proteins as a key factor in the pathology of cardiac dysfunction during and following ischemia. PMID:22564771

  14. The effect of an increase in chain length on the mechanical properties of polyethylene glycols.

    PubMed

    Al-Nasassrah, M A; Podczeck, F; Newton, J M

    1998-07-01

    The mechanical properties of different molecular weights of polyethylene glycol (PEG) have been determined by formation of compacted tablets and beams, which were subjected to diametral compression and 3-point bending, respectively. From diametral compression, the tensile strength for the different grades of PEG was determined. Flat beams made from powder by compaction were used to determine Young's modulus of elasticity. Beams into which a notch had been introduced after formation allowed the fracture mechanical parameters of critical stress intensity factor, K(IC), and fracture toughness, R, to be determined. Evaluation of these parameters as a function of compact porosity allowed extrapolation to values at zero porosity, providing an estimate of the material properties. The increase in chain length of the PEG was found to have a non-linear effect on tensile strength and Young's modulus. The ductility of the polymer increased proportionally to the increase in chain length, reflected by the linear relationship between K(IC) and the molecular weight. Young's modulus and critical stress intensity factor allowed the estimation of the strain energy release rate, G(IC), which is the driving force in crack propagation. Consequently, the tensile strength at zero porosity was found to be predictable from the values of G(IC) and the molecular weight of the different grades of PEG. PMID:9700020

  15. Poly(ethyleneoxide) functionalization through alkylation

    SciTech Connect

    Sivanandan, Kulandaivelu; Eitouni, Hany Basam; Li, Yan; Pratt, Russell Clayton

    2015-04-21

    A new and efficient method of functionalizing high molecular weight polymers through alkylation using a metal amide base is described. This novel procedure can also be used to synthesize polymer-based macro-initiators containing radical initiating groups at the chain-ends for synthesis of block copolymers.

  16. Spontaneous intercalation of long-chain alkyl ammonium into edge-selectively oxidized graphite to efficiently produce high-quality graphene

    PubMed Central

    Wei, Liangming; Wu, Fei; Shi, Diwen; Hu, Changchen; Li, Xiaolin; Yuan, Weien; Wang, Jian; Zhao, Jiang; Geng, Huijuan; Wei, Hao; Wang, Ying; Hu, Nantao; Zhang, Yafei

    2013-01-01

    Mass production of high-quality graphene nanosheets (GNs) is essential for practical applications. We report that oxidation of graphite by low concentration KMnO4 at relatively high temperature (60°C) leads to edge-selectively oxidized graphite (EOG) which preserves the high crystalline graphitic structure on its basal planes while the edges are functionalized by oxygen-containing groups. Long-chain tetradecyl-ammonium salt (C14N+) could be spontaneously intercalated into EOG to form intercalated EOG-C14N+ compounds. Gentle and short-time sonication of EOG-C14N+ in toluene can full exfoliate EOG into edge-oxidized graphene nanosheets (EOGNs) with concentration of 0.67 mg/ml, monolayer population up to 90% and lateral size from 1 μm to >100 μm. The EOG and EOGN films show excellent electrical conductance, which is far superior to their graphene oxide (GO) counterparts. Our method provides an efficient way to produce high-quality GNs, and the resultant EOG also can be directly used for production of multifunctional materials and devices. PMID:24022463

  17. Disrupted short chain specific β-oxidation and improved synthase expression increase synthesis of short chain fatty acids in Saccharomyces cerevisiae.

    PubMed

    Leber, Christopher; Choi, Jin Wook; Polson, Brian; Da Silva, Nancy A

    2016-04-01

    Biologically derived fatty acids have gained tremendous interest as an alternative to petroleum-derived fuels and chemical precursors. We previously demonstrated the synthesis of short chain fatty acids in Saccharomyces cerevisiae by introduction of the Homo sapiens fatty acid synthase (hFAS) with heterologous phosphopantetheine transferases and heterologous thioesterases. In this study, short chain fatty acid production was improved by combining a variety of novel enzyme and metabolic engineering strategies. The use of a H. sapiens-derived thioesterase and phosphopantetheine transferase were evaluated. In addition, strains were engineered to disrupt either the full β-oxidation (by deleting FAA2, PXA1, and POX1) or short chain-specific β-oxidation (by deleting FAA2, ANT1, and PEX11) pathways. Prohibiting full β-oxidation increased hexanoic and octanoic acid levels by 8- and 79-fold relative to the parent strain expressing hFAS. However, by targeting only short chain β-oxidation, hexanoic and octanoic acid levels increased further to 31- and 140-fold over the parent. In addition, an optimized hFAS gene increased hexanoic, octanoic, decanoic and total short chain fatty acid levels by 2.9-, 2.0-, 2.3-, and 2.2-fold, respectively, relative to the non-optimized counterpart. By combining these unique enzyme and metabolic engineering strategies, octanoic acid was increased more than 181-fold over the parent strain expressing hFAS. PMID:26388428

  18. Density fluctuations in saturated phospholipid bilayers increase as the acyl-chain length decreases.

    PubMed Central

    Ipsen, J H; Jørgensen, K; Mouritsen, O G

    1990-01-01

    A systematic computer simulation study is conducted for a model of the main phase transition of fully hydrated saturated diacyl phosphatidylcholine bilayers (DMPC, DPPC, and DSPC). With particular focus on the fluctuation effects on the thermal properties in the transition region, the study yields data for the specific heat, the lateral compressibility, and the lipid-domain size distribution. Via a simple model assumption the transmembrane passive ion permeability is derived from the lipid-domain interfacial measure. A comparative analysis of the various data shows, in agreement with a number of experiments, that the lateral density fluctuations and hence the response functions increase as the acyl-chain length is decreased. Images FIGURE 2 PMID:2291936

  19. Separation and quantitative analysis of alkyl sulfate ethoxymers by HPLC.

    PubMed

    Morvan, Julien; Hubert-Roux, Marie; Agasse, Valérie; Cardinael, Pascal; Barbot, Florence; Decock, Gautier; Bouillon, Jean-Philippe

    2008-01-01

    Separation of alkyl sulfate ethoxymers is investigated on various high-performance liquid chromatography (HPLC) stationary phases: Acclaim C18 Surfactant, Surfactant C8, and Hypercarb. For a fixed alkyl chain length, ethoxymers are eluted in the order of increasing number of ethoxylated units on Acclaim C18 Surfactant, whereas a reversed elution order is observed on Surfactant C8 and Hypercarb. Moreover, on an Acclaim C18 Surfactant column, non-ethoxylated compounds are eluted in their ethoxymers distribution and the use of sodium acetate additive in mobile phase leads to a co-elution of ethoxymers. HPLC stationary phases dedicated to surfactants analysis are evaluated by means of the Tanaka test. Surfactant C8 presents a great silanol activity whereas Acclaim C18 Surfactant shows a high steric selectivity. For alkyl sulfates, linearity of the calibration curve and limits of detection and quantitation are evaluated. The amount of sodium laureth sulfate raw material found in commercial body product is in agreement with the specification of the manufacturer. PMID:19007494

  20. Diabetes Mellitus and Increased Tuberculosis Susceptibility: The Role of Short-Chain Fatty Acids.

    PubMed

    Lachmandas, Ekta; van den Heuvel, Corina N A M; Damen, Michelle S M A; Cleophas, Maartje C P; Netea, Mihai G; van Crevel, Reinout

    2016-01-01

    Type 2 diabetes mellitus confers a threefold increased risk for tuberculosis, but the underlying immunological mechanisms are still largely unknown. Possible mediators of this increased susceptibility are short-chain fatty acids, levels of which have been shown to be altered in individuals with diabetes. We examined the influence of physiological concentrations of butyrate on cytokine responses to Mycobacterium tuberculosis (Mtb) in human peripheral blood mononuclear cells (PBMCs). Butyrate decreased Mtb-induced proinflammatory cytokine responses, while it increased production of IL-10. This anti-inflammatory effect was independent of butyrate's well-characterised inhibition of HDAC activity and was not accompanied by changes in Toll-like receptor signalling pathways, the eicosanoid pathway, or cellular metabolism. In contrast blocking IL-10 activity reversed the effects of butyrate on Mtb-induced inflammation. Alteration of the gut microbiota, thereby increasing butyrate concentrations, can reduce insulin resistance and obesity, but further studies are needed to determine how this affects susceptibility to tuberculosis. PMID:27057552

  1. Diabetes Mellitus and Increased Tuberculosis Susceptibility: The Role of Short-Chain Fatty Acids

    PubMed Central

    Lachmandas, Ekta; van den Heuvel, Corina N. A. M.; Damen, Michelle S. M. A.; Cleophas, Maartje C. P.; Netea, Mihai G.; van Crevel, Reinout

    2016-01-01

    Type 2 diabetes mellitus confers a threefold increased risk for tuberculosis, but the underlying immunological mechanisms are still largely unknown. Possible mediators of this increased susceptibility are short-chain fatty acids, levels of which have been shown to be altered in individuals with diabetes. We examined the influence of physiological concentrations of butyrate on cytokine responses to Mycobacterium tuberculosis (Mtb) in human peripheral blood mononuclear cells (PBMCs). Butyrate decreased Mtb-induced proinflammatory cytokine responses, while it increased production of IL-10. This anti-inflammatory effect was independent of butyrate's well-characterised inhibition of HDAC activity and was not accompanied by changes in Toll-like receptor signalling pathways, the eicosanoid pathway, or cellular metabolism. In contrast blocking IL-10 activity reversed the effects of butyrate on Mtb-induced inflammation. Alteration of the gut microbiota, thereby increasing butyrate concentrations, can reduce insulin resistance and obesity, but further studies are needed to determine how this affects susceptibility to tuberculosis. PMID:27057552

  2. Effects of increased anionic charge in the beta-globin chain on assembly of hemoglobin in vitro.

    PubMed

    Adachi, K; Yamaguchi, T; Pang, J; Surrey, S

    1998-02-15

    Studies on assembly in vitro of alpha-globin chains with recombinant beta16 Gly-->Asp, beta95 Lys-->Glu, beta120 Lys-->Glu and beta16 Gly-->Asp, 120 Lys-->Glu human beta-globin chain variants in addition to human betaA- and betaS-globin chains were performed to evaluate effects of increased anionic charge in the beta chain on hemoglobin assembly using soluble recombinant beta-globin chains expressed in bacteria. A beta112 Cys-->Asp change was also engineered to monitor effects on assembly of increased negative charge at alpha1beta1 interaction sites. Order of tetramer formation in vitro under limiting alpha-globin chain conditions showed Hb betaG16D, K120E = Hb betaK120E = Hb betaK95E > Hb betaG16D > Hb A > Hb S > Hb betaC112D. In addition, beta112 Cys-->Asp chains exist as monomers rather than beta4 tetramers in the absence of alpha chains, and the beta chain in Hb betaC112D tetramers was readily exchanged by addition of betas. These results suggest that affinity between alpha and beta chains is promoted by negatively-charged beta chains up to a maximum of two additional net negative charges and is independent of location on the surface except at the alpha1beta1 interaction site. In addition, our findings show that beta112 Cys on the G helix is critical for facilitating formation of stable alphabeta dimers, which then form functional hemoglobin tetramers, and that beta112 Cys-->Asp inhibits formation of stable alpha1beta1 and beta1beta2 interactions in alpha2beta2 and beta4 tetramers, respectively. PMID:9454775

  3. Disulfiram is a direct and potent inhibitor of human O6-methylguanine-DNA methyltransferase (MGMT) in brain tumor cells and mouse brain and markedly increases the alkylating DNA damage

    PubMed Central

    Srivenugopal, Kalkunte S.

    2014-01-01

    The alcohol aversion drug disulfiram (DSF) reacts and conjugates with the protein-bound nucleophilic cysteines and is known to elicit anticancer effects alone or improve the efficacy of many cancer drugs. We investigated the effects of DSF on human O6-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein and chemotherapy target that removes the mutagenic O6-akyl groups from guanines, and thus confers resistance to alkylating agents in brain tumors. We used DSF, copper-chelated DSF or CuCl2–DSF combination and found that all treatments inhibited the MGMT activity in two brain tumor cell lines in a rapid and dose-dependent manner. The drug treatments resulted in the loss of MGMT protein from tumor cells through the ubiquitin-proteasome pathway. Evidence showed that Cys145, a reactive cysteine, critical for DNA repair was the sole site of DSF modification in the MGMT protein. DSF was a weaker inhibitor of MGMT, compared with the established O6-benzylguanine; nevertheless, the 24–36h suppression of MGMT activity in cell cultures vastly increased the alkylation-induced DNA interstrand cross-linking, G2/M cell cycle blockade, cytotoxicity and the levels of apoptotic markers. Normal mice treated with DSF showed significantly attenuated levels of MGMT activity and protein in the liver and brain tissues. In nude mice bearing T98 glioblastoma xenografts, there was a preferential inhibition of tumor MGMT. Our studies demonstrate a strong and direct inhibition of MGMT by DSF and support the repurposing of this brain penetrating drug for glioma therapy. The findings also imply an increased risk for alkylation damage in alcoholic patients taking DSF. PMID:24193513

  4. The structure and photophysics of di-iodo-zinc(II) complexes of long alkyl chain substituted imidazolyl motif of arylazoimidazoles and the DFT computation.

    PubMed

    Sen, Chandana; Chowdhuri, Bharati; Patra, Chiranjit; Mallick, Debashis; Sinha, Chittaranjan

    2015-12-01

    Distorted tetrahedral structure of [Zn(Haai-C10H21)2I2] (Haai-C10H21, 1-decayl-2-(arylazo)imidazole) has been supported by single crystal X-ray diffraction study. The structures of other complexes, [Zn(Raai-CnH2n+1)2I2] (n=10, 12, 14, 16, 18, 20, 22) have been determined by spectroscopic data (FT-IR, UV-vis, (1)H NMR). The complexes show light induced photoisomerisation, E-to-Z (trans-to-cis) of coordinated, Raai-CnH2n+1. The Z-to-E (cis-to-trans) isomerisation is also carried out by thermal activation route. The quantum yields of the E→Z progression (ϕE→Z) of the complexes are less than that of free ligand, which could be due to increase in molar mass and molar volume of the complexes than that of free ligands. The activation energy (Ea) of Z→E isomerisation of the complexes is is less than that of free ligands. This observation is also consistent with femtosecond transient absorption results which suggests that the E(trans)→Z(cis) isomerization occurs through the motion of pendant NNAr of the molecule. The temporal profiles of free ligand shows three decay processes corresponds to 0.24ps (S2 state) and subsequent decay, 0.85ps of the S1 state and finally 5ps to the hot ground state at 500nm. The complexes also show three decay periods approximately at 0.25ps, 1.3ps and 13ps. The spectral property and photochromic efficiency have been explained by DFT computation of optimized geometry of the complexes. PMID:26151433

  5. Increased correlation range of seismicity before large events manifested by earthquake chains

    NASA Astrophysics Data System (ADS)

    Shebalin, P.

    2006-10-01

    "Earthquake chains" are clusters of moderate-size earthquakes which extend over large distances and are formed by statistically rare pairs of events that are close in space and time ("neighbors"). Earthquake chains are supposed to be precursors of large earthquakes with lead times of a few months. Here we substantiate this hypothesis by mass testing it using a random earthquake catalog. Also, we study stability under variation of parameters and some properties of the chains. We found two invariant parameters: they characterize the spatial and energy scales of earthquake correlation. Both parameters of the chains show good correlation with the magnitudes of the earthquakes they precede. Earthquake chains are known as the first stage of the earthquake prediction algorithm reverse tracing of precursors (RTP) now tested in forward prediction. A discussion of the complete RTP algorithm is outside the scope of this paper, but the results presented here are important to substantiate the RTP approach.

  6. Thiophene-Diketopyrrolopyrrole-Based Quinoidal Small Molecules as Solution-Processable and Air-Stable Organic Semiconductors: Tuning of the Length and Branching Position of the Alkyl Side Chain toward a High-Performance n-Channel Organic Field-Effect Transistor.

    PubMed

    Wang, Chao; Qin, Yunke; Sun, Yuanhui; Guan, Ying-Shi; Xu, Wei; Zhu, Daoben

    2015-07-29

    A series of thiophene-diketopyrrolopyrrole-based quinoidal small molecules (TDPPQ-2-TDPPQ-5) bearing branched alkyl chains with different side-chain lengths and varied branching positions are synthesized. Field-effect transistor (FET) measurement combined with thin-film characterization is utilized to systematically probe the influence of the side-chain length and branching position on the film microstructure, molecular packing, and, hence, charge-transport property. All of these TDPPQ derivatives show air-stable n-channel transporting behavior in spin-coated FET devices, which exhibit no significant decrease in mobility even after being stored in air for 2 months. Most notably, TDPPQ-3 exhibits an outstanding n-channel semiconducting property with electron mobilities up to 0.72 cm(2) V(-1) s(-1), which is an unprecedented value for spin-coated DPP-based n-type semiconducting small molecules. A balance of high crystallinity, satisfactory thickness uniformity and continuity, and strong intermolecular interaction accounts for the superior charge-transport characteristics of TDPPQ-3 films. Our study demonstrates that tuning the length and branching position of alkyl side chains of semiconducting molecules is a powerful strategy for achieving high FET performance. PMID:26134920

  7. Alkylating potential of oxetanes.

    PubMed

    Gómez-Bombarelli, Rafael; Palma, Bernardo Brito; Martins, Célia; Kranendonk, Michel; Rodrigues, Antonio S; Calle, Emilio; Rueff, José; Casado, Julio

    2010-07-19

    Small, highly strained heterocycles are archetypical alkylating agents (oxiranes, beta-lactones, aziridinium, and thiirinium ions). Oxetanes, which are tetragonal ethers, are higher homologues of oxiranes and reduced counterparts of beta-lactones, and would therefore be expected to be active alkylating agents. Oxetanes are widely used in the manufacture of polymers, especially in organic light-emitting diodes (OLEDs), and are present, as a substructure, in compounds such as the widely used antimitotic taxol. Whereas the results of animal tests suggest that trimethylene oxide (TMO), the parent compound, and beta,beta-dimethyloxetane (DMOX) are active carcinogens at the site of injection, no studies have explored the alkylating ability and genotoxicity of oxetanes. This work addresses the issue using a mixed methodology: a kinetic study of the alkylation reaction of 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilicity similar to that of DNA bases, by three oxetanes (TMO, DMOX, and methyloxetanemethanol), and a mutagenicity, genotoxicity, and cell viability study (Salmonella microsome test, BTC E. coli test, alkaline comet assay, and MTT assay). The results suggest either that oxetanes lack genotoxic capacity or that their mode of action is very different from that of epoxides and beta-lactones. PMID:20550097

  8. ALKYL PYROPHOSPHATE METAL SOLVENT EXTRACTANTS AND PROCESS

    DOEpatents

    Long, R.L.

    1958-09-30

    A process is presented for the recovery of uranium from aqueous mineral acidic solutions by solvent extraction. The extractant is a synmmetrical dialkyl pyrophosphate in which the alkyl substituents have a chain length of from 4 to 17 carbon atoms. Mentioned as a preferred extractant is dioctyl pyrophosphate. The uranium is precipitated irom the organic extractant phase with an agent such as HF, fluoride salts. alcohol, or ammonia.

  9. Selective downregulation of mitochondrial electron transport chain activity and increased oxidative stress in human atrial fibrillation.

    PubMed

    Emelyanova, Larisa; Ashary, Zain; Cosic, Milanka; Negmadjanov, Ulugbek; Ross, Gracious; Rizvi, Farhan; Olet, Susan; Kress, David; Sra, Jasbir; Tajik, A Jamil; Holmuhamedov, Ekhson L; Shi, Yang; Jahangir, Arshad

    2016-07-01

    Mitochondria are critical for maintaining normal cardiac function, and a deficit in mitochondrial energetics can lead to the development of the substrate that promotes atrial fibrillation (AF) and its progression. However, the link between mitochondrial dysfunction and AF in humans is still not fully defined. The aim of this study was to elucidate differences in the functional activity of mitochondrial oxidative phosphorylation (OXPHOS) complexes and oxidative stress in right atrial tissue from patients without (non-AF) and with AF (AF) who were undergoing open-heart surgery and were not significantly different for age, sex, major comorbidities, and medications. The overall functional activity of the electron transport chain (ETC), NADH:O2 oxidoreductase activity, was reduced by 30% in atrial tissue from AF compared with non-AF patients. This was predominantly due to a selective reduction in complex I (0.06 ± 0.007 vs. 0.09 ± 0.006 nmol·min(-1)·citrate synthase activity(-1), P = 0.02) and II (0.11 ± 0.012 vs. 0.16 ± 0.012 nmol·min(-1)·citrate synthase activity(-1), P = 0.003) functional activity in AF patients. Conversely, complex V activity was significantly increased in AF patients (0.21 ± 0.027 vs. 0.12 ± 0.01 nmol·min(-1)·citrate synthase activity(-1), P = 0.005). In addition, AF patients exhibited a higher oxidative stress with increased production of mitochondrial superoxide (73 ± 17 vs. 11 ± 2 arbitrary units, P = 0.03) and 4-hydroxynonenal level (77.64 ± 30.2 vs. 9.83 ± 2.83 ng·mg(-1) protein, P = 0.048). Our findings suggest that AF is associated with selective downregulation of ETC activity and increased oxidative stress that can contribute to the progression of the substrate for AF. PMID:27199126

  10. Structure-dependent and receptor-independent increase in osmotic fragility of rat erythrocytes by short-chain fatty acids.

    PubMed

    Mineo, Hitoshi; Hara, Hiroshi

    2005-07-30

    We examined short-chain fatty acids (SCFAs) with 1 (C1) to 5 (C5) carbon atoms for osmotic fragility (OF) in isolated red blood cells (RBCs) in rats. The RBCs were used as prototypical plasma membrane model. The dense packed RBC was incubated in a phosphate-NaCl buffer solution containing each SCFA at 0 to 100 mM. The RBC suspensions were transferred into the OF test tubes containing NaCl from 0.2 to 0.9%. The hemoglobin concentration was determined and the EC50 in hemolysis was calculated. The OF in RBCs was dose-dependently increased by exposure to SCFAs, except for C1, with an increasing number of carbon atoms. Branched-chain fatty acids (isomers of C4 and C5) have a smaller effect on OF than straight-chain fatty acids (C4 and C5). The SCFA-induced increases in OF were not affected by pretreatment of RBCs with trypsin. The response of the RBC membrane to SCFAs depends on their concentration, carbon chain length and chain structure (straight or branched). The SCFAs probably disturb the lipid bilayer of the RBC membrane and result in a decrease in osmotic resistance. The plasma membrane in rat RBCs could respond to the structure of the SCFAs in detail by using the OF as an indicator. PMID:15963944

  11. Fluoride Increases Superoxide Production and Impairs the Respiratory Chain in ROS 17/2.8 Osteoblastic Cells

    PubMed Central

    Fina, Brenda Lorena; Lombarte, Mercedes; Rigalli, Juan Pablo; Rigalli, Alfredo

    2014-01-01

    It is known that fluoride produces oxidative stress. Inflammation in bone tissue and an impairment of the respiratory chain of liver have been described in treatments with fluoride. Whether the impairment of the respiratory chain and oxidative stress are related is not known. The aim of this work was to study the effects of fluoride on the production of superoxide radical, the function of the respiratory chain and the increase in oxidative stress in ROS 17/2.8 osteoblastic cells. We measured the effect of fluoride (100 µM) on superoxide production, oxygen consumption, lipid peroxidation and antioxidant enzymes activities of cultured cells following the treatment with fluoride. Fluoride decreased oxygen consumption and increased superoxide production immediately after its addition. Furthermore, chronic treatment with fluoride increased oxidative stress status in osteoblastic cells. These results indicate that fluoride could damage bone tissue by inhibiting the respiratory chain, increasing the production of superoxide radicals and thus of the others reactive oxygen species. PMID:24964137

  12. Polyimide characterization studies - Effect of pendant alkyl groups

    NASA Technical Reports Server (NTRS)

    Jensen, B. J.; Young, P. R.

    1984-01-01

    The effect on selected polyimide properties when pendant alkyl groups were attached to the polymer backbone was investigated. A series of polymers were prepared using benzophenone tetracarboxylic acid dianhydride (BTDA) and seven different p-alkyl-m,p'-diaminobenzophenone monomers. The alkyl groups varied in length from C(1) (methyl) to C(9) (nonyl). The polyimide prepared from BTDA and m,p'-diaminobenzophenone was included as a control. All polymers were characterized by various chromatographic, spectroscopic, thermal, and mechanical techniques. Increasing the length of the pendant alkyl group resulted in a systematic decrease in glass transition temperature (Tg) for vacuum cured films. A 70 C decrease in Tg to 193 C was observed for the nonyl polymer compared to the Tg for the control. A corresponding systematic increase in Tg indicative of crosslinking, was observed for air cured films. Thermogravimetric analysis revealed a slight sacrifice in thermal stability with increasing alkyl length. No improvement in film toughness was observed.

  13. Peanut consumption increases levels of plasma very long chain fatty acids in humans.

    PubMed

    Lam, Christina; Wong, Derek; Cederbaum, Stephen; Lim, Bennie; Qu, Yong

    2012-11-01

    Peanut consumption has been suspected of raising plasma very long chain fatty acid (VLCFA) levels in humans. The effect of peanut consumption on VLCFAs was studied in six human subjects. After 3 to 4h of peanut butter ingestion, plasma C26:0 and C26:0/C22:0 were found to be significantly elevated to levels seen in patients with peroxisomal disorders. These levels returned to normal within 12h. Peanut consumption needs to be accounted for when interpreting VLCFAs. PMID:22864056

  14. Trophic assimilation efficiency markedly increases at higher trophic levels in four-level host-parasitoid food chain.

    PubMed

    Sanders, Dirk; Moser, Andrea; Newton, Jason; van Veen, F J Frank

    2016-03-16

    Trophic assimilation efficiency (conversion of resource biomass into consumer biomass) is thought to be a limiting factor for food chain length in natural communities. In host-parasitoid systems, which account for the majority of terrestrial consumer interactions, a high trophic assimilation efficiency may be expected at higher trophic levels because of the close match of resource composition of host tissue and the consumer's resource requirements, which would allow for longer food chains. We measured efficiency of biomass transfer along an aphid-primary-secondary-tertiary parasitoid food chain and used stable isotope analysis to confirm trophic levels. We show high efficiency in biomass transfer along the food chain. From the third to the fourth trophic level, the proportion of host biomass transferred was 45%, 65% and 73%, respectively, for three secondary parasitoid species. For two parasitoid species that can act at the fourth and fifth trophic levels, we show markedly increased trophic assimilation efficiencies at the higher trophic level, which increased from 45 to 63% and 73 to 93%, respectively. In common with other food chains, δ(15)N increased with trophic level, with trophic discrimination factors (Δ(15)N) 1.34 and 1.49‰ from primary parasitoids to endoparasitic and ectoparasitic secondary parasitoids, respectively, and 0.78‰ from secondary to tertiary parasitoids. Owing to the extraordinarily high efficiency of hyperparasitoids, cryptic higher trophic levels may exist in host-parasitoid communities, which could alter our understanding of the dynamics and drivers of community structure of these important systems. PMID:26962141

  15. Trophic assimilation efficiency markedly increases at higher trophic levels in four-level host–parasitoid food chain

    PubMed Central

    Moser, Andrea; van Veen, F. J. Frank

    2016-01-01

    Trophic assimilation efficiency (conversion of resource biomass into consumer biomass) is thought to be a limiting factor for food chain length in natural communities. In host–parasitoid systems, which account for the majority of terrestrial consumer interactions, a high trophic assimilation efficiency may be expected at higher trophic levels because of the close match of resource composition of host tissue and the consumer's resource requirements, which would allow for longer food chains. We measured efficiency of biomass transfer along an aphid-primary–secondary–tertiary parasitoid food chain and used stable isotope analysis to confirm trophic levels. We show high efficiency in biomass transfer along the food chain. From the third to the fourth trophic level, the proportion of host biomass transferred was 45%, 65% and 73%, respectively, for three secondary parasitoid species. For two parasitoid species that can act at the fourth and fifth trophic levels, we show markedly increased trophic assimilation efficiencies at the higher trophic level, which increased from 45 to 63% and 73 to 93%, respectively. In common with other food chains, δ15N increased with trophic level, with trophic discrimination factors (Δ15N) 1.34 and 1.49‰ from primary parasitoids to endoparasitic and ectoparasitic secondary parasitoids, respectively, and 0.78‰ from secondary to tertiary parasitoids. Owing to the extraordinarily high efficiency of hyperparasitoids, cryptic higher trophic levels may exist in host–parasitoid communities, which could alter our understanding of the dynamics and drivers of community structure of these important systems. PMID:26962141

  16. Formulation of solid lipid nanoparticles (SLN): the value of different alkyl polyglucoside surfactants.

    PubMed

    Keck, Cornelia M; Kovačević, Andjelka; Müller, Rainer H; Savić, Snežana; Vuleta, Gordana; Milić, Jela

    2014-10-20

    Alkyl polyglycosides (APGs) represent a group of nonionic tensides with excellent skin compatibility. Thus they seem to be excellent stabilizers for lipid nanoparticles for dermal application. To investigate this, different APGs were selected to evaluate their influence on the formation and characteristics of solid lipid nanoparticles (SLN). Contact angle analysis of the aqueous solutions/dispersions of the APGs on cetyl palmitate films revealed good wettability for all APG surfactants. Cetyl palmitate based SLN were prepared by hot high pressure homogenization and subjected to particle size, charge and inner structure analysis. 1% of each APG was sufficient to obtain SLN with a mean size between 150 nm and 175 nm and a narrow size distribution. The zeta potential in water was ∼ -50 mV; the values in the original medium were distinctly lower, but still sufficient high to provide good physical stability. Physical stability at different temperatures (5°C, 25°C and 40°C) was confirmed by a constant particle size over an observation period of 90 days in all dispersions. In comparison to SLN stabilized with classical surfactants, e.g., Polysorbate, APG stabilized SLN possess a smaller size, improved physical stability and contain less surfactant. Therefore, the use of APGs for the stabilization of lipid nanoparticles is superior in comparison to classical stabilizers. Further, the results indicate that the length of the alkyl chain of the APG influences the diminution efficacy, the final particle size and the crystallinity of the particles. APGs with short alkyl chain led to a faster reduction in size during high pressure homogenization, to a smaller particle size of the SLN and to a lower recrystallization index, i.e., to a lower crystallinity of the SLN. The crystallinity of the SLN increased with an increase in the alkyl chain length of APGs. Therefore, by using the tested APGs differing in the alkyl chain length, not only small sized and physically stable but

  17. Synthesis and antifungal activity of natural product-based 6-alkyl-2 3 4 5-tetrahydropyridines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven 6-alkyl-2,3,4,5-tetrahydropyridines (5a–5g) that mimic the natural products piperideines that were recently identified in the fire ant venom have been synthesized. Compounds 5c–5g with the C-6 alkyl chain lengths from C14 to C18 showed varying degrees of antifungal activities, with 5e (6-hexa...

  18. Alkyl-π engineering in state control toward versatile optoelectronic soft materials

    NASA Astrophysics Data System (ADS)

    Lu, Fengniu; Nakanishi, Takashi

    2015-02-01

    Organic π-conjugated molecules with extremely rich and tailorable electronic and optical properties are frequently utilized for the fabrication of optoelectronic devices. To achieve high solubility for facile solution processing and desirable softness for flexible device fabrication, the rigid π units were in most cases attached by alkyl chains through chemical modification. Considerable numbers of alkylated-π molecular systems with versatile applications have been reported. However, a profound understanding of the molecular state control through proper alkyl chain substitution is still highly demanded because effective applications of these molecules are closely related to their physical states. To explore the underlying rule, we review a large number of alkylated-π molecules with emphasis on the interplay of van der Waals interactions (vdW) of the alkyl chains and π-π interactions of the π moieties. Based on our comprehensive investigations of the two interactions’ impacts on the physical states of the molecules, a clear guidance for state control by alkyl-π engineering is proposed. Specifically, either with proper alkyl chain substitution or favorable additives, the vdW and π-π interactions can be adjusted, resulting in modulation of the physical states and optoelectronic properties of the molecules. We believe the strategy summarized here will significantly benefit the alkyl-π chemistry toward wide-spread applications in optoelectronic devices.

  19. The role of cellular structure on increasing the detonability limits of three-step chain-branching detonations

    SciTech Connect

    Short, Mark; Kiyanda, Charles B; Quirk, James J; Sharpe, Gary J

    2011-01-27

    In [1], the dynamics of a pulsating three-step chain-branching detonation were studied. The reaction model consists of, sequentially, chain-initiation, chain-branching and chain-termination steps. The chain-initiation and chain-branching steps are taken to be thermally neutral, with chemical energy release occuring in the chain-termination stage. The purpose of the present study is to examine whether cellular detonation structure can increase the value of the chain-branching cross-over temperature T{sub b} at which fully coupled detonation solutions are observed over those in 1 D. The basic concept is straightforward and has been discussed in [1] and [3]; if T{sub s} drops below T{sub b} at the lead shock, the passage of a transverse shock can increase both the lead shock temperature and the temperature behind the transverse wave back above T{sub b}, thus sustaining an unstable cellular detonation for values of T{sub b} for which a one-dimensional pulsating detonation will fail. Experiments potentially supporting this hypothesis with irregular detonations have been shown in [3] in a shock tube with acoustically absorbing walls. Removal of the transverse waves results in detonation failure, giving way to a decoupled shock-flame complex. A number of questions remain to be addressed regarding the possibility of such a mechanism, and, if so, about the precise mechanisms driving the cellular structure for large T{sub b}. For instance, one might ask what sets the cell size in a chain-branching detonation, particularly could the characteristic cell size be set by the chain-branching cross-over temperature T{sub b}: after a transverse wave shock collision, the strength of the transverse wave weakens as it propagates along the front. If the spacing between shock collisions is too large (cell size), then the transverse shocks may weaken to the extent that the lead shock temperature or that behind the transverse waves is not raised above T{sub b}, losing chemical energy to

  20. Increased sensitivity of lymphocytes from patients with systemic autoimmune diseases to DNA alkylation by the methylating carcinogen N-methyl-N-nitrosourea.

    PubMed Central

    Lawley, P D; Topper, R; Denman, A M; Hylton, W; Hill, I D; Harris, G

    1988-01-01

    Lymphocytes from patients with various diseases associated with autoimmunity showed both impaired capacity to repair O6-methylguanine (a powerful, promutagenic, directly miscoding base lesion) and increased sensitivity to the cytocidal effects of cellular methylation by N-methyl-N-nitrosourea (MNU) compared with normal controls and patients with other disorders. Defective repair of O6-methylguanine was significantly associated with arthritis and myositis in the group with systemic lupus erythematosus (SLE), and increased sensitivity to the toxic action of MNU was associated with the presence of immune complexes and the administration of steroids to patients with Behçet's syndrome. The results indicate that lymphocytes from patients with the autoimmune diseases studied are more susceptible to DNA damage with possible relevance to aetiopathogenesis. PMID:3382263

  1. RFID in the blood supply chain--increasing productivity, quality and patient safety.

    PubMed

    Briggs, Lynne; Davis, Rodeina; Gutierrez, Alfonso; Kopetsky, Matthew; Young, Kassandra; Veeramani, Raj

    2009-01-01

    As part of an overall design of a new, standardized RFID-enabled blood transfusion medicine supply chain, an assessment was conducted for two hospitals: the University of Iowa Hospital and Clinics (UIHC) and Mississippi Baptist Health System (MBHS). The main objectives of the study were to assess RFID technological and economic feasibility, along with possible impacts to productivity, quality and patient safety. A step-by-step process analysis focused on the factors contributing to process "pain points" (errors, inefficiency, product losses). A process re-engineering exercise produced blueprints of RFID-enabled processes to alleviate or eliminate those pain-points. In addition, an innovative model quantifying the potential reduction in adverse patient effects as a result of RFID implementation was created, allowing improvement initiatives to focus on process areas with the greatest potential impact to patient safety. The study concluded that it is feasible to implement RFID-enabled processes, with tangible improvements to productivity and safety expected. Based on a comprehensive cost/benefit model, it is estimated for a large hospital (UIHC) to recover investment from implementation within two to three years, while smaller hospitals may need longer to realize ROI. More importantly, the study estimated that RFID technology could reduce morbidity and mortality effects substantially among patients receiving transfusions. PMID:19894488

  2. Method of making alkyl esters

    DOEpatents

    Elliott, Brian

    2010-09-14

    Methods of making alkyl esters are described herein. The methods are capable of using raw, unprocessed, low-cost feedstocks and waste grease. Generally, the method involves converting a glyceride source to a fatty acid composition and esterifying the fatty acid composition to make alkyl esters. In an embodiment, a method of making alkyl esters comprises providing a glyceride source. The method further comprises converting the glyceride source to a fatty acid composition comprising free fatty acids and less than about 1% glyceride by mass. Moreover, the method comprises esterifying the fatty acid composition in the presence of a solid acid catalyst at a temperature ranging firm about 70.degree. C. to about 120.degree. C. to produce alkyl esters, such that at least 85% of the free fatty acids are converted to alkyl esters. The method also incorporates the use of packed bed reactors for glyceride conversion and/or fatty acid esterification to make alkyl esters.

  3. Age‐related remodeling of small arteries is accompanied by increased sphingomyelinase activity and accumulation of long‐chain ceramides

    PubMed Central

    Ohanian, Jacqueline; Liao, Aiyin; Forman, Simon P.; Ohanian, Vasken

    2014-01-01

    Abstract The structure and function of large arteries alters with age leading to increased risk of cardiovascular disease. Age‐related large artery remodeling and arteriosclerosis is associated with increased collagen deposition, inflammation, and endothelial dysfunction. Bioactive sphingolipids are known to regulate these processes, and are also involved in aging and cellular senescence. However, less is known about age‐associated alterations in small artery morphology and function or whether changes in arterial sphingolipids occur in aging. We show that mesenteric small arteries from old sheep have increased lumen diameter and media thickness without a change in media to lumen ratio, indicative of outward hypertrophic remodeling. This remodeling occurred without overt changes in blood pressure or pulse pressure indicating it was a consequence of aging per se. There was no age‐associated change in mechanical properties of the arteries despite an increase in total collagen content and deposition of collagen in a thickened intima layer in arteries from old animals. Analysis of the sphingolipid profile showed an increase in long‐chain ceramide (C14–C20), but no change in the levels of sphingosine or sphingosine‐1‐phosphate in arteries from old compared to young animals. This was accompanied by a parallel increase in acid and neutral sphingomyelinase activity in old arteries compared to young. This study demonstrates remodeling of small arteries during aging that is accompanied by accumulation of long‐chain ceramides. This suggests that sphingolipids may be important mediators of vascular aging. PMID:24872355

  4. Abuse potential and dopaminergic effect of alkyl nitrites.

    PubMed

    Jeon, Seo Young; Kim, Yun Ji; Kim, Young-Hoon; Shin, Jisoon; Yun, Jaesuk; Han, Kyoungmoon; Park, Hye-Kyung; Kim, Hyung Soo; Cha, Hye Jin

    2016-08-26

    The abuse of alkyl nitrites is common among adolescents and young adults worldwide. However, the information regarding the effects of alkyl nitrites on the central nervous system and the associated psychological abuse potential is scarce. The abuse potential of 3 representative alkyl nitrites - isobutyl nitrite, isoamyl nitrite, and butyl nitrite - was evaluated in mice using conditioned place preference tests with an unbiased method. The dopamine levels released by synaptosomes extracted from the striatal region were measured using high performance liquid chromatography. Mice treated with the test substances (50mg/kg, i.p.) exhibited a significantly increased drug-paired place preference. Moreover, greater levels of dopamine were released by striatal region synaptosomes in response to isobutyl nitrite treatment in mice. Thus, our findings suggest that alkyl nitrites could lead to psychological dependence and dopaminergic effects. Furthermore, these results provide scientific evidence to support the regulation of alkyl nitrites as psychoactive substances in the future. PMID:27369324

  5. Transesterified tyrosol and hydroxytyrosol alkyl esters from cuphea oil – antioxidant behavior in Liposomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tyrosol and hydroxytyrosol are the antioxidant molecules abundantly found in olive oil. Transesterification of tyrosol and hydroxytyrosol with cuphea oil results in medium chain alkyl esters with antioxidant properties. Membrane partitioning, antioxidant capacity, and membrane location of these nove...

  6. Surface adsorption of zwitterionic surfactants: n-alkyl phosphocholines characterised by surface tensiometry and neutron reflection.

    PubMed

    Yaseen, M; Wang, Y; Su, T J; Lu, J R

    2005-08-15

    The surface adsorption of n-dodecyl phosphocholine (C12PC) has been characterised by a combined measurement of surface tension and neutron reflectivity. The critical micellar concentration (CMC) was found to be 0.91 mM at 25 degrees C in pure water. At the CMC, the limiting area per molecule (A(cmc)) was found to be 52+/-3 A2 and the surface tension (gamma(cmc)) to be ca. 40.0+/-0.5 mN/m. The parallel study of chain isomer n-hexadecyl phosphocholine (C16PC) showed a decrease of the CMC to 0.012 mM and a drop of gamma(cmc) to 38.1+/-0.5 mN/m. However, A(cmc) for C16PC was found to be 54+/-3 A2, showing that increase in alkyl chain length by four methylene groups has little effect on A(cmc). The almost constant A(cmc) suggested that the limiting area per molecule was determined by the bulky PC head group. It was further found that the surface tension and related key physical parameters did not vary much with temperature, salt addition, solution pH or any combination of these, thus showing that surface adsorption and solution aggregation from PC surfactants is largely similar to the zwitterionic betaine surfactants and is distinctly different from ionic and non-ionic surfactants. The thickness of the adsorbed monolayers measured from both dC12hPC and dC16hPC was found to be 20-22 A at the CMC from neutron reflectivity. Neither A(cmc) nor layer thickness varied with alkyl chain length, indicating that as the alkyl chain length became longer it was further tilted away from the surface normal direction and the layer packing density increased. It was also observed that the thickness of the layer varied little with surfactant concentration, indicating that the average conformational orientation of the alkyl chain remained unchanged against varying surface coverage. PMID:15927600

  7. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl...

  8. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl...

  9. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl...

  10. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl...

  11. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl...

  12. Solid-phase extraction-gas chromatography and solid-phase extraction-gas chromatography-mass spectrometry determination of corrosion inhibiting long-chain primary alkyl amines in chemical treatment of boiler water in water-steam systems of power plants.

    PubMed

    Kusch, Peter; Knupp, Gerd; Hergarten, Marcus; Kozupa, Marian; Majchrzak, Maria

    2006-04-28

    Gas chromatography with simultaneous flame-ionization detection (FID) and a nitrogen-phosphorus detection (NPD) as well as gas chromatography-mass spectrometry (GC/MS) has been used to characterize long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and negative chemical ionization (NCI) mass spectra of trifluoroacetylated derivatives of the identified tert-octadecylamines are presented for the first time. The corrosion inhibiting alkyl amines were applied in a water-steam circuit of energy systems in the power industry. Solid-phase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated tert-octadecylamines in boiler water, superheated steam and condensate samples from the power plant. The estimated values were: 89 microg l(-1)(n = 5, RSD = 7.8%), 45 microg l(-1) (n = 5, RSD = 5.4%) and 37 microg l(-1)(n = 5, RSD = 2.3%), respectively. PMID:16483586

  13. Discovery and identification of a series of alkyl decalin isomers in petroleum geological samples.

    PubMed

    Wang, Huitong; Zhang, Shuichang; Weng, Na; Zhang, Bin; Zhu, Guangyou; Liu, Lingyan

    2015-07-01

    The comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOFMS) has been used to characterize a crude oil and a source rock extract sample. During the process, a series of pairwise components between monocyclic alkanes and mono-aromatics have been discovered. After tentative assignments of decahydronaphthalene isomers, a series of alkyl decalin isomers have been synthesized and used for identification and validation of these petroleum compounds. From both the MS and chromatography information, these pairwise compounds were identified as 2-alkyl-decahydronaphthalenes and 1-alkyl-decahydronaphthalenes. The polarity of 1-alkyl-decahydronaphthalenes was stronger. Their long chain alkyl substituent groups may be due to bacterial transformation or different oil cracking events. This systematic profiling of alkyl-decahydronaphthalene isomers provides further understanding and recognition of these potential petroleum biomarkers. PMID:25945366

  14. Synthesis of alkylated deoxynojirimycin and 1,5-dideoxy-1,5-iminoxylitol analogues: polar side-chain modification, sulfonium and selenonium heteroatom variants, conformational analysis, and evaluation as glycosidase inhibitors.

    PubMed

    Szczepina, Monica G; Johnston, Blair D; Yuan, Yue; Svensson, Birte; Pinto, B Mario

    2004-10-01

    The syntheses of N-alkylated deoxynojirimycin and 1,5-dideoxy-1,5-iminoxylitol derivatives having either a D- or an L-erythritol-3-sulfate functionalized N-substituent are reported. The alkylating agent used was a cyclic sulfate derivative, whereby selective attack of the nitrogen atom at the least hindered primary center afforded the desired ammonium salt. In aqueous solution, these salts were configurationally labile at the ammonium center. Sulfonium and/or selenonium analogues of the ammonium salts were prepared by analogous reactions. The chalcogen salts were obtained as mixtures of diastereomers, separable in some cases, differing only in the stereochemistry at the configurationally stable sulfur or selenium atoms. Proof of configuration and conformation of each compound was obtained by detailed NMR experiments. The compounds are six-membered ring analogues of salacinol, a known sulfonium-salt glucosidase inhibitor. Evaluation of the target compounds for enzyme inhibition of the glucosidase enzyme glucoamylase G2 indicated that these compounds were either inactive or, at best, only weak inhibitors of maltose hydrolysis. PMID:15453780

  15. Assessing and Increasing Staff Preference for Job Tasks Using Concurrent-Chains Schedules and Probabilistic Outcomes

    ERIC Educational Resources Information Center

    Reed, Derek D.; DiGennaro Reed, Florence D.; Campisano, Natalie; Lacourse, Kristen; Azulay, Richard L.

    2012-01-01

    The assessment and improvement of staff members' subjective valuation of nonpreferred work tasks may be one way to increase the quality of staff members' work life. The Task Enjoyment Motivation Protocol (Green, Reid, Passante, & Canipe, 2008) provides a process for supervisors to identify the aversive qualities of nonpreferred job tasks. Through…

  16. Accelerated increase in mercury contamination in north Atlantic mesopelagic food chains as indicated by time series of seabird feathers

    SciTech Connect

    Monteiro, L.R.; Furness, R.W.

    1997-12-01

    Concentrations of mercury in the environment have increased manyfold since preindustrial times as a result of anthropogenic emissions of gaseous mercury to the atmosphere. However, most records of historical change are affected by regional inputs and evidence of global impact of human activities at pristine oceanic sites is scanty. Seabird feathers contain a valuable record showing historical trends in methylmercury contamination. Some seabirds are top predators in epipelagic and others in mesopelagic food chains and thus reflect methylmercury contamination of these ecosystems. Here, the authors report the first measurements of mercury concentrations in a time series of animals from the subtropical northeast Atlantic over the last 100 years. These data show increases in mercury levels by 1.1 to 1.9%/year in epipelagic foodchains and by 3.5 to 4.8%/year in mesopelagic food chains. While the rate of increase in the epipelagic ecosystem is in close agreement with model predictions, the higher rate in the mesopelagic ecosystem has not previously been detected. However, the latter concurs with methylmercury production below the thermocline and conveys new insights into the understanding of the anthropogenic impact in the marine cycle of mercury.

  17. Polygas spells relief from alkylation ills

    SciTech Connect

    Weismantel, G.E.

    1980-06-16

    Tight supplies and soaring prices of isobutane (for olefin alkylation), are causing renewed interest in the olefin ''polymerization'' (i.e., dimerization), route to high-octane gasoline-blending components. Modern polymerization processes, intended to supplement rather than replace alkylation offer considerable energy and capital savings, compared with alkylation-only schemes. In addition to the Institut Francais du Petrole's Dimersol ''polymerization'' tecnique which is already being used or will be used by 1981 in at least five U.S. refineries, with six more units in the planning stage, a low-cost process to ''polymerize'' excess refinery olefins, developed by International Energy Consultants Inc., is nearing commercialization. A third route to process C/sub 3//C/sub 4/ refinery streams with high conversion rates has been proposed by UOP Inc. The low motor octane number (MON) of the product gasoline (approx. 13 numbers lower than a typical alkylate), was recently confirmed in Total Petroleum Inc.'s studies, but Good Hope Refineries Inc. plans to increase its polymer gasoline MON by adding methyl tert.-butyl ether.

  18. Perfluorinated Alkyl Compounds: Challenges To Develop Robust And Reliable Methods

    EPA Science Inventory

    An increasing number of studies have been conducted to investigate the environmental distribution of perfluorinated alkyl compounds (PFCs), some of which are known to be toxic in laboratory studies. Despite growing public concerns, environmental monitoring data are still limited...

  19. Adipose tissue fatty acid chain length and mono-unsaturation increases with obesity and insulin resistance

    PubMed Central

    Yew Tan, Chong; Virtue, Samuel; Murfitt, Steven; Robert, Lee D.; Phua, Yi Hui; Dale, Martin; Griffin, Julian L.; Tinahones, Francisco; Scherer, Philipp E.; Vidal-Puig, Antonio

    2015-01-01

    The non-essential fatty acids, C18:1n9, C16:0, C16:1n7, C18:0 and C18:1n7 account for over 75% of fatty acids in white adipose (WAT) triacylglycerol (TAG). The relative composition of these fatty acids (FA) is influenced by the desaturases, SCD1-4 and the elongase, ELOVL6. In knock-out models, loss of SCD1 or ELOVL6 results in reduced Δ9 desaturated and reduced 18-carbon non-essential FA respectively. Both Elovl6 KO and SCD1 KO mice exhibit improved insulin sensitivity. Here we describe the relationship between WAT TAG composition in obese mouse models and obese humans stratified for insulin resistance. In mouse models with increasing obesity and insulin resistance, there was an increase in scWAT Δ9 desaturated FAs (SCD ratio) and FAs with 18-carbons (Elovl6 ratio) in mice. Data from mouse models discordant for obesity and insulin resistance (AKT2 KO, Adiponectin aP2-transgenic), suggested that scWAT TAG Elovl6 ratio was associated with insulin sensitivity, whereas SCD1 ratio was associated with fat mass. In humans, a greater SCD1 and Elovl6 ratio was found in metabolically more harmful visceral adipose tissue when compared to subcutaneous adipose tissue. PMID:26679101

  20. Bovine serum albumin-sodium alkyl sulfates bioconjugates as drug delivery systems.

    PubMed

    Benkő, M; Varga, N; Sebők, D; Bohus, G; Juhász, Á; Dékány, I

    2015-06-01

    Precipitation of bovine serum albumin (BSA) by anionic surfactants with alkyl chains of increasing lengths (octyl, decyl, dodecyl sulfates) was studied at room temperature, at pH 3.0, in isotonic sodium chloride solution. The particle size of albumin, the zeta potential, the surface charge and fluorescent properties of BSA-surfactant composites were investigated concerning addition of increasing amount of surfactant. The thermal stability of the systems was monitored by calorimetric analysis (DSC). The formation of the well-ordered structure in the self-assembly process in liquid phase was studied by XRD measurement. The structure of the precipitated BSA-surfactant nanocomposites was characterized by small-angle X-ray scattering (SAXS). Finally, ibuprofen (IBU) molecules were enclosed in BSA-surfactant bioconjugate systems and the release properties of the drug were investigated. It has been found out that, as a consequence to the increasing number of carbon atoms in the alkyl chains of the surfactant, the structure and the fluorescent properties of the aggregates formed can be controlled due to the increase in the hydrophobicity of BSA-surfactant composites. The bioconjugates are well applicable as carrier to realize controlled release of drug molecules. PMID:25935562

  1. Acute Carnosine Administration Increases Respiratory Chain Complexes and Citric Acid Cycle Enzyme Activities in Cerebral Cortex of Young Rats.

    PubMed

    Macedo, Levy W; Cararo, José H; Maravai, Soliany G; Gonçalves, Cinara L; Oliveira, Giovanna M T; Kist, Luiza W; Guerra Martinez, Camila; Kurtenbach, Eleonora; Bogo, Maurício R; Hipkiss, Alan R; Streck, Emilio L; Schuck, Patrícia F; Ferreira, Gustavo C

    2016-10-01

    Carnosine (β-alanyl-L-histidine) is an imidazole dipeptide synthesized in excitable tissues of many animals, whose biochemical properties include carbonyl scavenger, anti-oxidant, bivalent metal ion chelator, proton buffer, and immunomodulating agent, although its precise physiological role(s) in skeletal muscle and brain tissues in vivo remain unclear. The aim of the present study was to investigate the in vivo effects of acute carnosine administration on various aspects of brain bioenergetics of young Wistar rats. The activity of mitochondrial enzymes in cerebral cortex was assessed using a spectrophotometer, and it was found that there was an increase in the activities of complexes I-III and II-III and succinate dehydrogenase in carnosine-treated rats, as compared to vehicle-treated animals. However, quantitative real-time RT-PCR (RT-qPCR) data on mRNA levels of mitochondrial biogenesis-related proteins (nuclear respiratory factor 1 (Nrf1), peroxisome proliferator-activated receptor-γ coactivator 1-α (Ppargc1α), and mitochondrial transcription factor A (Tfam)) were not altered significantly and therefore suggest that short-term carnosine administration does not affect mitochondrial biogenesis. It was in agreement with the finding that immunocontent of respiratory chain complexes was not altered in animals receiving carnosine. These observations indicate that acute carnosine administration increases the respiratory chain and citric acid cycle enzyme activities in cerebral cortex of young rats, substantiating, at least in part, a neuroprotector effect assigned to carnosine against oxidative-driven disorders. PMID:26476839

  2. Determining cysteine oxidation status using differential alkylation

    NASA Astrophysics Data System (ADS)

    Schilling, Birgit; Yoo, Chris B.; Collins, Christopher J.; Gibson, Bradford W.

    2004-08-01

    Oxidative damage to proteins plays a major role in aging and in the pathology of many degenerative diseases. Under conditions of oxidative stress, reactive oxygen and nitrogen species can modify key redox sensitive amino acid side chains leading to altered biological activities or structures of the targeted proteins. This in turn can affect signaling or regulatory control pathways as well as protein turnover and degradation efficiency in the proteasome. Cysteine residues are particularly susceptible to oxidation, primarily through reversible modifications (e.g., thiolation and nitrosylation), although irreversible oxidation can lead to products that cannot be repaired in vivo such as sulfonic acid. This report describes a strategy to determine the overall level of reversible cysteine oxidation using a stable isotope differential alkylation approach in combination with mass spectrometric analysis. This method employs 13C-labeled alkylating reagents, such as N-ethyl-[1,4-13C2]-maleimide, bromo-[1,2-13C2]-acetic acid and their non-labeled counterparts to quantitatively assess the level of cysteine oxidation at specific sites in oxidized proteins. The differential alkylation protocol was evaluated using standard peptides and proteins, and then applied to monitor and determine the level of oxidative damage induced by diamide, a mild oxidant. The formation and mass spectrometric analysis of irreversible cysteine acid modification will also be discussed as several such modifications have been identified in subunits of the mitochondrial electron transport chain complexes. This strategy will hopefully contribute to our understanding of the role that cysteine oxidation plays in such chronic diseases such as Parkinson's disease, where studies in animal and cell models have shown oxidative damage to mitochondrial Complex I to be a specific and early target.

  3. Magnified Sediment Export of Small Mountainous Rivers in Taiwan: Chain Reactions from Increased Rainfall Intensity under Global Warming

    PubMed Central

    Lee, Tsung-Yu; Huang, Jr-Chuan; Lee, Jun-Yi; Jien, Shih-Hao; Zehetner, Franz; Kao, Shuh-Ji

    2015-01-01

    Fluvial sediment export from small mountainous rivers in Oceania has global biogeochemical significance affecting the turnover rate and export of terrestrial carbon, which might be speeding up at the recognized conditions of increased rainfall intensity. In this study, the historical runoff and sediment export from 16 major rivers in Taiwan are investigated and separated into an early stage (1970–1989) and a recent stage (1990–2010) to illustrate the changes of both runoff and sediment export. The mean daily sediment export from Taiwan Island in the recent stage significantly increased by >80% with subtle increase in daily runoff, indicating more sediment being delivered to the ocean per unit of runoff in the recent stage. The medians of the runoff depth and sediment yield extremes (99.0–99.9 percentiles) among the 16 rivers increased by 6.5%-37% and 62%-94%, respectively, reflecting the disproportionately magnified response of sediment export to the increased runoff. Taiwan is facing increasing event rainfall intensity which has resulted in chain reactions on magnified runoff and sediment export responses. As the globe is warming, rainfall extremes, which are proved to be temperature-dependent, very likely intensify runoff and trigger more sediment associated hazards. Such impacts might occur globally because significant increases of high-intensity precipitation have been observed not only in Taiwan but over most land areas of the globe. PMID:26372356

  4. Magnified Sediment Export of Small Mountainous Rivers in Taiwan: Chain Reactions from Increased Rainfall Intensity under Global Warming.

    PubMed

    Lee, Tsung-Yu; Huang, Jr-Chuan; Lee, Jun-Yi; Jien, Shih-Hao; Zehetner, Franz; Kao, Shuh-Ji

    2015-01-01

    Fluvial sediment export from small mountainous rivers in Oceania has global biogeochemical significance affecting the turnover rate and export of terrestrial carbon, which might be speeding up at the recognized conditions of increased rainfall intensity. In this study, the historical runoff and sediment export from 16 major rivers in Taiwan are investigated and separated into an early stage (1970-1989) and a recent stage (1990-2010) to illustrate the changes of both runoff and sediment export. The mean daily sediment export from Taiwan Island in the recent stage significantly increased by >80% with subtle increase in daily runoff, indicating more sediment being delivered to the ocean per unit of runoff in the recent stage. The medians of the runoff depth and sediment yield extremes (99.0-99.9 percentiles) among the 16 rivers increased by 6.5%-37% and 62%-94%, respectively, reflecting the disproportionately magnified response of sediment export to the increased runoff. Taiwan is facing increasing event rainfall intensity which has resulted in chain reactions on magnified runoff and sediment export responses. As the globe is warming, rainfall extremes, which are proved to be temperature-dependent, very likely intensify runoff and trigger more sediment associated hazards. Such impacts might occur globally because significant increases of high-intensity precipitation have been observed not only in Taiwan but over most land areas of the globe. PMID:26372356

  5. Very long O-antigen chains enhance fitness during Salmonella-induced colitis by increasing bile resistance.

    PubMed

    Crawford, Robert W; Keestra, A Marijke; Winter, Sebastian E; Xavier, Mariana N; Tsolis, Renée M; Tolstikov, Vladimir; Bäumler, Andreas J

    2012-09-01

    Intestinal inflammation changes the luminal habitat for microbes through mechanisms that have not been fully resolved. We noticed that the FepE regulator of very long O-antigen chain assembly in the enteric pathogen Salmonella enterica serotype Typhimurium (S. Typhimurium) conferred a luminal fitness advantage in the mouse colitis model. However, a fepE mutant was not defective for survival in tissue, resistance to complement or resistance to polymyxin B. We performed metabolite profiling to identify changes in the luminal habitat that accompany S. Typhimurium-induced colitis. This analysis suggested that S. Typhimurium-induced colitis increased the luminal concentrations of total bile acids. A mutation in fepE significantly reduced the minimal inhibitory concentration (MIC) of S. Typhimurium for bile acids in vitro. Oral administration of the bile acid sequestrant cholestyramine resin lowered the concentrations of total bile acids in colon contents during S. Typhimurium infection and significantly reduced the luminal fitness advantage conferred by the fepE gene in the mouse colitis model. Collectively, these data suggested that very long O-antigen chains function in bile acid resistance of S. Typhimurium, a property conferring a fitness advantage during luminal growth in the inflamed intestine. PMID:23028318

  6. Very Long O-antigen Chains Enhance Fitness during Salmonella-induced Colitis by Increasing Bile Resistance

    PubMed Central

    Crawford, Robert W.; Keestra, A. Marijke; Winter, Sebastian E.; Xavier, Mariana N.; Tsolis, Renée M.; Tolstikov, Vladimir; Bäumler, Andreas J.

    2012-01-01

    Intestinal inflammation changes the luminal habitat for microbes through mechanisms that have not been fully resolved. We noticed that the FepE regulator of very long O-antigen chain assembly in the enteric pathogen Salmonella enterica serotype Typhimurium (S. Typhimurium) conferred a luminal fitness advantage in the mouse colitis model. However, a fepE mutant was not defective for survival in tissue, resistance to complement or resistance to polymyxin B. We performed metabolite profiling to identify changes in the luminal habitat that accompany S. Typhimurium-induced colitis. This analysis suggested that S. Typhimurium-induced colitis increased the luminal concentrations of total bile acids. A mutation in fepE significantly reduced the minimal inhibitory concentration (MIC) of S. Typhimurium for bile acids in vitro. Oral administration of the bile acid sequestrant cholestyramine resin lowered the concentrations of total bile acids in colon contents during S. Typhimurium infection and significantly reduced the luminal fitness advantage conferred by the fepE gene in the mouse colitis model. Collectively, these data suggested that very long O-antigen chains function in bile acid resistance of S. Typhimurium, a property conferring a fitness advantage during luminal growth in the inflamed intestine. PMID:23028318

  7. Acute Administration of Branched-Chain Amino Acids Increases the Pro-BDNF/Total-BDNF Ratio in the Rat Brain.

    PubMed

    Scaini, Giselli; Morais, Meline O S; Furlanetto, Camila B; Kist, Luiza W; Pereira, Talita C B; Schuck, Patrícia F; Ferreira, Gustavo C; Pasquali, Matheus A B; Gelain, Daniel P; Moreira, José Cláudio F; Bogo, Maurício R; Streck, Emilio L

    2015-05-01

    Maple syrup urine disease (MSUD) is caused by an inborn error in metabolism resulting from a deficiency in the branched-chain α-keto acid dehydrogenase complex activity. This blockage leads to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine and valine, as well as their corresponding α-keto acids and α-hydroxy acids. High levels of BCAAs are associated with neurological dysfunction and the role of pro- and mature brain-derived neurotrophic factor (BDNF) in the neurological dysfunction of MSUD is still unclear. Thus, in the present study we investigated the effect of an acute BCAA pool administration on BDNF levels and on the pro-BDNF cleavage-related proteins S100A10 and tissue plasminogen activator (tPA) in rat brains. Our results demonstrated that acute Hyper-BCAA (H-BCAA) exposure during the early postnatal period increases pro-BDNF and total-BDNF levels in the hippocampus and striatum. Moreover, tPA levels were significantly decreased, without modifications in the tPA transcript levels in the hippocampus and striatum. On the other hand, the S100A10 mRNA and S100A10 protein levels were not changed in the hippocampus and striatum. In the 30-day-old rats, we observed increased pro-BDNF, total-BDNF and tPA levels only in the striatum, whereas the tPA and S100A10 mRNA expression and the immunocontent of S100A10 were not altered. In conclusion, we demonstrated that acute H-BCAA administration increases the pro-BDNF/total-BDNF ratio and decreases the tPA levels in animals, suggesting that the BCAA effect may depend, at least in part, on changes in BDNF post-translational processing. PMID:25681161

  8. Entropy effects in the collective dynamic behavior of alkyl monolayers tethered to Si(111)

    PubMed Central

    2015-01-01

    Summary Dynamic properties of n-alkyl monolayers covalently bonded to Si(111) were studied by broadband admittance spectroscopy as a function of the temperature and the applied voltage using rectifying Hg/C12H25/n-type Si junctions. Partial substitution of methyl end groups by polar (carboxylic acid) moieties was used to enhance the chain end relaxation response. Two thermally activated dissipation mechanisms (B1 and B2, with f B1 < f B2) are evidenced for all reverse bias values. The strong decrease of both relaxation frequencies with increasing reverse dc bias reveals increasing motional constraints, attributed to electrostatic pressure applied to the densely-packed nanometer-thick monolayer. Spectral decomposition of the frequency response shows a power-law dependence of their activation energies on |V DC|. A large reverse bias reversibly increases the B2 response attributed to the distribution of gauche defects, in contrast with the constant strength of the acid dipole loss (B1). A trans–gauche isomerization energy of 50 meV is derived from the temperature dependence of the B2 dipolar strength. For both dissipation mechanisms, the observed linear correlation between activation energy and logarithm of pre-exponential factor is consistent with a multi-excitation entropy model, in which the molecular reorientation path is strongly coupled with a large number of low energy excitations (here the n-alkyl bending vibrational mode) collected from the thermal bath. This collective dynamic behavior of alkyl chains tethered to Si is also confirmed by the asymmetric relaxation peak shape related to many-body interactions in complex systems. PMID:25821699

  9. 40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to...

  10. 40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to...

  11. 40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to...

  12. 40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to...

  13. 40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to...

  14. Alkylation and acylation of cyclotriphosphazenes.

    PubMed

    Benson, Mark A; Zacchini, Stefano; Boomishankar, Ramamoorthy; Chan, Yuri; Steiner, Alexander

    2007-08-20

    Phosphazenes (RNH)6P3N3 (R = n-propyl, isobutyl, isopropyl, cyclohexyl, tert-butyl, benzyl) are readily alkylated at ring N sites by alkyl halides forming N-alkyl phosphazenium cations. Alkylation of two ring N sites occurred after prolonged heating in the presence of methyl iodide or immediately at room temperature with methyl triflate yielding N,N'-dimethyl phosphazenium dications. Geminal dichloro derivatives Cl2(RNH)4P3N3 are methylated by methyl iodide at the ring N site adjacent to both P centers carrying four RNH groups. X-ray crystal structures showed that the alkylation of ring N sites leads to substantial elongation of the associated P-N bonds. Both N-alkyl and N,N'-dialkyl phosphazenium salts form complex supramolecular networks in the solid state via NH...X interactions. Systems carrying less-bulky RNH groups show additional NH...N bonds between N-alkyl phosphazenium ions. N-Alkyl phosphazenium halides form complexes with silver ions upon treatment with silver nitrate. Depending on the steric demand of RNH substituents, either one or both of the vacant ring N sites engage in coordination to silver ions. Treatment of (RNH)6P3N3 (R = isopropyl) with acetyl chloride and benzoyl chloride, respectively, yielded N-acyl phosphazenium ions. X-ray crystal structures revealed that elongation of P-N bonds adjacent to the acylated ring N site is more pronounced than it is in the case of N-alkylated species. Salts containing N-alkyl phosphazenium ions are stable toward water and other mild nucleophiles, while N,N'-dialkyl and N-acyl phosphazenium salts are readily hydrolyzed. The reaction of (RNH)6P3N3 with bromoacetic acid led to N-alkylation at one ring N site in addition to formation of an amide via condensation of an adjacent RNH substituent with the carboxylic acid group. The resulting bromide salt contains mono cations of composition (RNH)5P3N3CH2CONR in which a CH2-C(O) unit is embedded between a ring N and an exocyclic N site of the phosphazene. PMID

  15. Antibacterial activity of alkyl gallates is a combination of direct targeting of FtsZ and permeabilization of bacterial membranes

    PubMed Central

    Król, Ewa; de Sousa Borges, Anabela; da Silva, Isabel; Polaquini, Carlos R.; Regasini, Luis O.; Ferreira, Henrique; Scheffers, Dirk-Jan

    2015-01-01

    Alkyl gallates are compounds with reported antibacterial activity. One of the modes of action is binding of the alkyl gallates to the bacterial membrane and interference with membrane integrity. However, alkyl gallates also cause cell elongation and disruption of cell division in the important plant pathogen Xanthomonas citri subsp. citri, suggesting that cell division proteins may be targeted by alkyl gallates. Here, we use Bacillus subtilis and purified B. subtilis FtsZ to demonstrate that FtsZ is a direct target of alkyl gallates. Alkyl gallates disrupt the FtsZ-ring in vivo, and cause cell elongation. In vitro, alkyl gallates bind with high affinity to FtsZ, causing it to cluster and lose its capacity to polymerize. The activities of a homologous series of alkyl gallates with alkyl side chain lengths ranging from five to eight carbons (C5–C8) were compared and heptyl gallate was found to be the most potent FtsZ inhibitor. Next to the direct effect on FtsZ, alkyl gallates also target B. subtilis membrane integrity—however the observed anti-FtsZ activity is not a secondary effect of the disruption of membrane integrity. We propose that both modes of action, membrane disruption and anti-FtsZ activity, contribute to the antibacterial activity of the alkyl gallates. We propose that heptyl gallate is a promising hit for the further development of antibacterials that specifically target FtsZ. PMID:25972861

  16. Antibacterial activity of alkyl gallates is a combination of direct targeting of FtsZ and permeabilization of bacterial membranes.

    PubMed

    Król, Ewa; de Sousa Borges, Anabela; da Silva, Isabel; Polaquini, Carlos R; Regasini, Luis O; Ferreira, Henrique; Scheffers, Dirk-Jan

    2015-01-01

    Alkyl gallates are compounds with reported antibacterial activity. One of the modes of action is binding of the alkyl gallates to the bacterial membrane and interference with membrane integrity. However, alkyl gallates also cause cell elongation and disruption of cell division in the important plant pathogen Xanthomonas citri subsp. citri, suggesting that cell division proteins may be targeted by alkyl gallates. Here, we use Bacillus subtilis and purified B. subtilis FtsZ to demonstrate that FtsZ is a direct target of alkyl gallates. Alkyl gallates disrupt the FtsZ-ring in vivo, and cause cell elongation. In vitro, alkyl gallates bind with high affinity to FtsZ, causing it to cluster and lose its capacity to polymerize. The activities of a homologous series of alkyl gallates with alkyl side chain lengths ranging from five to eight carbons (C5-C8) were compared and heptyl gallate was found to be the most potent FtsZ inhibitor. Next to the direct effect on FtsZ, alkyl gallates also target B. subtilis membrane integrity-however the observed anti-FtsZ activity is not a secondary effect of the disruption of membrane integrity. We propose that both modes of action, membrane disruption and anti-FtsZ activity, contribute to the antibacterial activity of the alkyl gallates. We propose that heptyl gallate is a promising hit for the further development of antibacterials that specifically target FtsZ. PMID:25972861

  17. ALBUMIN CAUSES INCREASED MYOSIN LIGHT CHAIN KINASE EXPRESSION IN ASTROCYTES VIA P38 MITOGEN ACTIVATED PROTEIN KINASE

    PubMed Central

    Rossi, Janet L.; Ralay Ranaivo, Hantamala; Patel, Fatima; Chrzaszcz, MaryAnn; Venkatesan, Charu; Wainwright, Mark S.

    2011-01-01

    Myosin light chain kinase (MLCK) plays an important role in the reorganization of the cytoskeleton leading to disruption of vascular barrier integrity in multiple organs including the blood brain barrier (BBB) after traumatic brain injury (TBI). MLCK has been linked to transforming growth factor (TGF) and rho kinase signaling pathways, but the mechanisms regulating MLCK expression following TBI are not well understood. Albumin leaks into the brain parenchyma following TBI, activates glia and has been linked to TGF-β receptor signaling. We investigated the role of albumin in the increase in MLCK in astrocytes and the signaling pathways involved in this increase. Following midline closed-skull TBI in mice, there was a significant increase in MLCK-immunoreactive (IR) cells and albumin extravasation, which was prevented by treatment with the MLCK inhibitor ML-7. Using immunohistochemical methods, we identified the MCLK-IR cells as astrocytes. In primary astrocytes, exposure to albumin increased both isoforms of MLCK, 130 and 210. Inhibition of the TGF-β receptor partially prevented the albumin-induced increase in both isoforms, which was not prevented by inhibition of smad3. Inhibition of p38 MAPK, but not ERK, JNK or rho kinase also prevented this increase. These results are further evidence of a role of MCLK in the mechanisms of BBB compromise following TBI, and identify astrocytes as a cell type, in addition to endothelium in the BBB which express MLCK. These findings implicate albumin, acting through p38 MAPK, in a novel mechanism by which activation of MLCK following TBI may lead to compromise of the BBB. PMID:21360574

  18. Familial mutations in fibrinogen Aα (FGA) chain identified in renal amyloidosis increase in vitro amyloidogenicity of FGA fragment.

    PubMed

    Sivalingam, Vishwanath; Patel, Basant K

    2016-08-01

    Amyloidoses are clinical disorders where deposition of β-sheet rich, misfolded protein aggregates called amyloid occurs in vital organs like brain, kidney, liver or heart etc. Aggregation of several proteins such as immunoglobulin light chain, fibrinogen Aα chain (FGA) and lysozyme have been found to be associated with renal amyloidosis. Fibrinogen amyloidosis (AFib) is predominantly familial and is associated with the deposition of mutant FGA amyloid, primarily in kidneys. Over ten substitution and frame-shift mutations in FGA have been identified from AFib patients. Whether wild-type FGA is also involved in AFib is yet unknown. The affected tissues from AFib patients usually show ∼10 kDA peptide from C-terminal 80 amino acid residues of mutant FGA. Notably, this region also encompasses all known disease-related mutations. Whether these point mutations increase the amyloidogenicity of FGA leading to disease progression, have not been studied yet. Here, we have investigated the role of two disease-related mutations in affecting amyloidogenic propensity of an FGA(496-581) fragment. We found that at physiological pH, the wild-type FGA(496-581) fragment remains monomeric, whereas its E540V mutant forms amyloid-like fibrils as observed by AFM. Also, FGA(496-581) harbouring another familial mutation, R554L, converts in vitro into globular, β-sheet rich aggregates, showing amyloid-like properties. These findings suggest that familial mutations in FGA may have role in renal amyloidosis via enhanced amyloid formation. PMID:27126074

  19. fadD deletion and fadL overexpression in Escherichia coli increase hydroxy long-chain fatty acid productivity.

    PubMed

    Bae, Jin H; Park, Beom Gi; Jung, Eunok; Lee, Pyung-Gang; Kim, Byung-Gee

    2014-11-01

    A major problem of long-chain fatty acid (LCFA) hydroxylation using Escherichia coli is that FadD (long-chain fatty acyl-CoA synthetase), which is necessary for exogenous LCFA transport, also initiates cellular consumption of LCFA. In this study, an effective method to prevent the cellular consumption of LCFA without impairing its transport is proposed. The main idea is that a heterologous enzyme which consumes LCFA can replace FadD in LCFA transport. For the model heterologous enzyme, CYP153A from Marinobacter aquaeolei, which converts palmitic acid into ω-hydroxy palmitic acid, was expressed in E. coli. When fadD was deleted from an E. coli strain, CYP153A indeed maintained the ability to transport LCFA. A disadvantage of fadD deletion mutant is the fact that FadD deficiency downregulates the transcription of fadL (outer membrane LCFA transporter) via FadR (fatty acid metabolism regulator protein), was solved by fadL overexpression from a plasmid. In addition, the overexpression of fadL was able to offset catabolite repression on fadL, allowing glucose to be used as the primary carbon source. In conclusion, the strain with fadD deletion and fadL overexpression showed 5.5-fold increase in productivity compared to the wild-type strain, converting 2.6 g/L (10.0 mM) of palmitic acid into 2.4 g/L (8.8 mM) of ω-hydroxy palmitic acid in a shake flask. This simple genetic manipulation can be applied to any LCFA hydroxylation using E. coli. PMID:25117545

  20. Microbial degradation of n-alkyl tetrahydrothiophenes found in petroleum.

    PubMed Central

    Fedorak, P M; Payzant, J D; Montgomery, D S; Westlake, D W

    1988-01-01

    Although n-alkyl-substituted tetrahydrothiophenes are found in nonbiodegraded petroleums, they are not found in petroleums which have undergone biodegradation in their reservoirs. These observations suggested that this group of compounds with alkyl chain lengths from approximately C10 to at least C30 is biodegradable. Two of these sulfides, 2-n-dodecyltetrahydrothiophene (DTHT) and 2-n-undecyltetrahydrothiophene, were synthesized, and their biodegradabilities were tested by using five gram-positive, n-alkane-degrading bacterial isolates. The alkyl side chains of these compounds were oxidized, and the major intermediates found in 2-n-undecyltetrahydrothiophene- and DTHT-metabolizing cultures were 2-tetrahydrothiophenecarboxylic acid (THTC) and 2-tetrahydrothiopheneacetic acid (THTA), respectively. Four n-alkane-degrading fungi were also shown to degrade DTHT, yielding both THTA and THTC. Quantitation of tetrahydrothiophene ring-containing products in 28-day-old bacterial and fungal cultures suggested that THTC and THTA were metabolized further to unidentified products. In addition, two of the bacterial isolates were shown to degrade a mixture of n-alkyl tetrahydrothiophenes isolated from Bellshill Lake crude oil. PMID:3389816

  1. Mild Catalytic methods for Alkyl-Alkyl Bond Formation

    SciTech Connect

    Vicic, David A

    2009-08-10

    Overview of Research Goals and Accomplishments for the Period 07/01/06 – 06/30/07: Our overall research goal is to transform the rapidly emerging synthetic chemistry involving alkyl-alkyl cross-couplings into more of a mechanism-based field so that that new, rationally-designed catalysts can be performed under energy efficient conditions. Our specific objectives for the previous year were 1) to obtain a proper electronic description of an active catalyst for alkyl-alkyl cross-coupling reactions and 2) to determine the effect of ligand structure on the rate, scope, selectivity, and functional group compatibility of C(sp3)-C(sp3) cross-coupling catalysis. We have completed both of these initial objectives and established a firm base for further studies. The specific significant achievements of the current grant period include: 1) we have performed magnetic and computational studies on (terpyridine)NiMe, an active catalyst for alkyl-alkyl cross couplings, and have discovered that the unpaired electron resides heavily on the terpyridine ligand and that the proper electronic description of this nickel complex is a Ni(II)-methyl cation bound to a reduced terpyridine ligand; 2) we have for the first time shown that alkyl halide reduction by terpyridyl nickel catalysts is substantially ligand based; 3) we have shown by isotopic labeling studies that the active catalyst (terpyridine)NiMe is not produced via a mechanism that involves the formation of methyl radicals when (TMEDA)NiMe2 is used as the catalyst precursor; 4) we have performed an extensive ligand survey for the alkyl-alkyl cross-coupling reactions and have found that electronic factors only moderately influence reactivity in the terpyridine-based catalysis and that the most dramatic effects arise from steric and solubility factors; 5) we have found that the use of bis(dialkylphosphino)methanes as ligands for nickel does not produce active catalysts for cross-coupling but rather leads to bridging hydride

  2. Ablation of smooth muscle myosin heavy chain SM2 increases smooth muscle contraction and results in postnatal death in mice.

    PubMed

    Chi, Mei; Zhou, Yingbi; Vedamoorthyrao, Srikanth; Babu, Gopal J; Periasamy, Muthu

    2008-11-25

    The physiological relevance of smooth muscle myosin isoforms SM1 and SM2 has not been understood. In this study we generated a mouse model specifically deficient in SM2 myosin isoform but expressing SM1, using an exon-specific gene targeting strategy. The SM2 homozygous knockout (SM2(-/-)) mice died within 30 days after birth, showing pathologies including segmental distention of alimentary tract, retention of urine in renal pelvis, distension of bladder, and the development of end-stage hydronephrosis. In contrast, the heterozygous (SM2(+/-)) mice appeared normal and reproduced well. In SM2(-/-) bladder smooth muscle the loss of SM2 myosin was accompanied by a concomitant down-regulation of SM1 and a reduced number of thick filaments. However, muscle strips from SM2(-/-) bladder showed increased contraction to K(+) depolarization or in response to M3 receptor agonist Carbachol. An increase of contraction was also observed in SM2(-/-) aorta. However, the SM2(-/-) bladder was associated with unaltered regulatory myosin light chain (MLC20) phosphorylation. Moreover, other contractile proteins, such as alpha-actin and tropomyosin, were not altered in SM2(-/-) bladder. Therefore, the loss of SM2 myosin alone could have induced hypercontractility in smooth muscle, suggesting that distinctly from SM1, SM2 may negatively modulate force development during smooth muscle contraction. Also, because SM2(-/-) mice develop lethal multiorgan dysfunctions, we propose this regulatory property of SM2 is essential for normal contractile activity in postnatal smooth muscle physiology. PMID:19011095

  3. Dielectric effects of step-increased pressure on the mass- and diffusion-controlled linear chain and network macromolecules growth

    NASA Astrophysics Data System (ADS)

    Wasylyshyn, D. A.; Johari, G. P.

    1998-10-01

    The dielectric properties of four stoichiometric liquid mixtures of a diepoxide with two monoamines and two diamines have been studied in real time during the mixture's polymerization isothermally to a linear-chain polymer in two cases and a network polymer in the other two cases, at 1 and 200 bar. The pressure was applied: (a) at the beginning of polymerization, (b) after a small extent of polymerization when the viscosity was low, and (c) after a relatively large extent of polymerization when the viscosity was high. For a fixed polymerization period, pressure increased the dielectric relaxation time much more than any other quantity in all cases, without a change in the distribution of relaxation times. Contributions to the dielectric permittivity and loss from physical and chemical effects have been considered and related to the changes in the dielectric relaxation time, viscosity and polymerization-rate constant as the extent of polymerization increased with time. Pressure is expected to decrease the polymerization rate for all conditions, but the decrease is relatively insignificant at the early stage, when polymerization is mass-controlled. Here other effects override the effect of viscosity increase, and the polymerization rate instead increases. The decrease in the rate becomes significant and predominates only when polymerization becomes diffusion-controlled. Since theories of diffusion-controlled reactions do not consider the mutual slowing of the molecular diffusion and the rate of chemical reactions leading to a macromolecule's growth until its vitrification isothermally, a method for determining the onset of diffusion control was needed. It is shown that this onset can be determined from plotting the rate of polymerization against the dielectric relaxation time. Expressed in terms of the dielectric loss, these plots cross each other. The cross-over point indicates the onset of diffusion control. Thus, the effect of pressure on the dielectric behaviour

  4. Medium-chain triglycerides and conjugated linoleic acids in beverage form increase satiety and reduce food intake in humans.

    PubMed

    Coleman, Hannah; Quinn, Paul; Clegg, Miriam E

    2016-06-01

    Both developed and developing countries are seeing increasing trends of obesity in people young and old. It is thought that satiety may play a role in the prevention of obesity by increasing satiety and reducing energy intake. We hypothesized that medium-chain triglycerides (MCT) would increase satiety and decrease food intake compared with conjugated linoleic acid (CLA) and a control oil. Nineteen healthy participants were tested on 3 separate occasions, where they consumed a beverage test breakfast containing (1) vegetable oil (control), (2) CLA, or (3) MCT. Participants self-requested an ad libitum sandwich buffet lunch. Time between meals, satiety from visual analog scales, energy intake at lunch, and intake for the rest of the day using weighed food diaries were measured. The results indicated that the time until a meal request was significantly different between the 3 meals (P=.016); however, there were no differences in intakes at the ad libitum lunch (P>.05). The CLA breakfast generated the greatest delay in meal time request. There was a difference between the control lipid compared with both the CLA and MCT for energy intake over the remainder of the test day and for total energy intake on the test day (P<.001 for both), with the CLA and MCT resulting in a lower intake than the control throughout the day. There were no significant differences in satiety from visual analog scale scores (P>.05). Both CLA and MCT increased satiety and reduced energy intake, indicating a potential role in aiding the maintenance of energy balance. PMID:27188898

  5. Thermally induced alkylation of diamond.

    PubMed

    Hoeb, Marco; Auernhammer, Marianne; Schoell, Sebastian J; Brandt, Martin S; Garrido, Jose A; Stutzmann, Martin; Sharp, Ian D

    2010-12-21

    We present an approach for the thermally activated formation of alkene-derived self-assembled monolayers on oxygen-terminated single and polycrystalline diamond surfaces. Chemical modification of the oxygen and hydrogen plasma-treated samples was achieved by heating in 1-octadecene. The resulting layers were characterized using X-ray photoelectron spectroscopy, thermal desorption spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and water contact angle measurements. This investigation reveals that alkenes selectively attach to the oxygen-terminated sites via covalent C-O-C bonds. The hydrophilic oxygen-terminated diamond is rendered strongly hydrophobic following this reaction. The nature of the process limits the organic layer growth to a single monolayer, and FTIR measurements reveal that such monolayers are dense and well ordered. In contrast, hydrogen-terminated diamond sites remain unaffected by this process. This method is thus complementary to the UV-initiated reaction of alkenes with diamond, which exhibits the opposite reactivity contrast. Thermal alkylation increases the range of available diamond functionalization strategies and provides a means of straightforwardly forming single organic layers in order to engineer the surface properties of diamond. PMID:21090790

  6. HPLC and TLC characterisation of ecdysteroid alkyl ethers.

    PubMed

    Lapenna, Silvia; Dinan, Laurence

    2009-10-01

    Semi-synthetic ecdysteroid alkyl ethers have increased potential over natural ecdysteroids as actuators of ligand-inducible gene-expression systems based on the ecdysteroid receptor for in vivo applications. However, a scalable synthesis of these compounds has yet to be developed. We report a set of reversed-phase (RP; C(18) and C(6)) and normal-phase (NP; diol) HPLC systems which can be used to analyse and separate ecdysteroid ethers with single or multiple O-methyl substitutions at the 2alpha-, 3beta-, 14alpha-, 22- and 25-positions. The elution order of methyl ether analogues of the prototypical ecdysteroid 20-hydroxyecdysone (20E) was 3-methyl<2-methyl<14-methyl<25-methyl<22-methyl with both C(18)- and C(6)-RP-HPLC, when eluted with methanol/water mixtures. Further, the elution order of 20E 22-O-alkyl ethers was methylalkyl ethers can also be adequately resolved by NP-HPLC and silica HPTLC. On the latter, detection of ecdysteroid O-alkyl ethers with the p-anisaldehyde/sulphuric acid reagent distinguishes 22-O-alkyl ethers from non-22-O-alkyl ether analogues by the colour of the resulting spot. PMID:19648067

  7. Final Technical Report [Development of Catalytic Alkylation and Fluoroalkylation Methods

    SciTech Connect

    Vicic, David A.

    2014-05-01

    In the early stages of this DOE-funded research project, we sought to prepare and study a well-defined nickel-alkyl complex containing tridentate nitrogen donor ligands. We found that reaction of (TMEDA)NiMe2 (1) with terpyridine ligand cleanly led to the formation of (terpyridyl)NiMe (2), which we also determined to be an active alkylation catalyst. The thermal stability of 2 was unlike that seen for any of the active pybox ligands, and enabled a number of key studies on alkyl transfer reactions to be performed, providing new insights into the mechanism of nickel-mediated alkyl-alkyl cross-coupling reactions. In addition to the mechanistic studies, we showed that the terpyridyl nickel compounds can catalytically cross-couple alkyl iodides in yields up to 98% and bromides in yields up to 46 %. The yields for the bromides can be increased up to 67 % when the new palladium catalyst [(tpy’)Pd-Ph]I is used. The best route to the targeted [(tpy)NiBr] (1) was found to involve the comproportionation reaction of [(dme)NiBr{sub 2}] and [Ni(COD){sub 2}] in the presence of two equivalents of terpyridine. This reaction was driven to high yields of product formation (72 % isolated) by the precipitation of 1 from THF solvent.

  8. Alcohols as alkylating agents in heteroarene C-H functionalization

    NASA Astrophysics Data System (ADS)

    Jin, Jian; MacMillan, David W. C.

    2015-09-01

    Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of `spin-centre shift', during which an alcohol C-O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based alkylation methods require the use of stoichiometric oxidants, increased temperatures or peroxides, a mild protocol using simple and abundant alkylating agents would have considerable use in the synthesis of diversely functionalized pharmacophores. Here we describe the development of a dual catalytic alkylation of heteroarenes, using alcohols as mild alkylating reagents. This method represents the first, to our knowledge, broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer catalysis. The value of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone.

  9. Alcohols as alkylating agents in heteroarene C-H functionalization.

    PubMed

    Jin, Jian; MacMillan, David W C

    2015-09-01

    Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of 'spin-centre shift', during which an alcohol C-O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based alkylation methods require the use of stoichiometric oxidants, increased temperatures or peroxides, a mild protocol using simple and abundant alkylating agents would have considerable use in the synthesis of diversely functionalized pharmacophores. Here we describe the development of a dual catalytic alkylation of heteroarenes, using alcohols as mild alkylating reagents. This method represents the first, to our knowledge, broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer catalysis. The value of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone. PMID:26308895

  10. Modeling of alkyl quaternary ammonium cations intercalated into montmorillonite lattice

    SciTech Connect

    Daoudi, El Mehdi; Boughaleb, Yahia; El Gaini, Layla; Meghea, Irina; Bakasse, Mina

    2013-05-15

    Highlights: ► The modification of montmorillonites by three surfactants increases the basal spacing. ► The model proposed show a bilayer conformation for the surfactant ODTMA. ► The DODMA and TOMA surfactants adopt a paraffin type arrangement. ► Behavior of surfactants in interlayer space was confirmed by TGA and ATR analysis. - Abstract: The objective of this work was to study the conformation of the quaternary ammonium cations viz., octadecyl trimethyl ammonium (ODTMA), dioctadecyl dimethyl ammonium (DMDOA) and trioctadecyl methyl ammonium (TOMA) intercalated within montmorillonite. The modified montmorillonite was characterized by X-ray diffraction in small angle (SAXS), thermal analysis (TGA) and infrared spectroscopy of attenuated total reflection (ATR). The modification of organophilic montmorillonites by the three surfactants ODTMA, DMDOA and TOMA increases the basal spacing from their respective intercalated distances of 1.9 nm, 2.6 nm and 3.4 nm respectively. The increase in the spacing due to the basic organic modification was confirmed by the results of thermal analysis (TGA) and infrared spectroscopy (ATR), and also supported by theoretical calculations of longitudinal and transversal chain sizes of these alkyl quaternary ammonium cations.

  11. Kinetic study of the anaerobic biodegradation of alkyl polyglucosides and the influence of their structural parameters.

    PubMed

    Ríos, Francisco; Fernández-Arteaga, Alejandro; Lechuga, Manuela; Jurado, Encarnación; Fernández-Serrano, Mercedes

    2016-05-01

    This paper reports a study of the anaerobic biodegradation of non-ionic surfactants alkyl polyglucosides applying the method by measurement of the biogas production in digested sludge. Three alkyl polyglucosides with different length alkyl chain and degree of polymerization of the glucose units were tested. The influence of their structural parameters was evaluated, and the characteristics parameters of the anaerobic biodegradation were determined. Results show that alkyl polyglucosides, at the standard initial concentration of 100 mgC L(-1), are not completely biodegradable in anaerobic conditions because they inhibit the biogas production. The alkyl polyglucoside having the shortest alkyl chain showed the fastest biodegradability and reached the higher percentage of final mineralization. The anaerobic process was well adjusted to a pseudo first-order equation using the carbon produced as gas during the test; also, kinetics parameters and a global rate constant for all the involved metabolic process were determined. This modeling is helpful to evaluate the biodegradation or the persistence of alkyl polyglucosides under anaerobic conditions in the environment and in the wastewater treatment. PMID:26820643

  12. An effective strategy to increase hydroxide-ion conductivity through microphase separation induced by hydrophobic-side chains

    NASA Astrophysics Data System (ADS)

    Zeng, L.; Zhao, T. S.

    2016-01-01

    A highly conductive and durable anion exchange membrane (AEM) is an essential component for alkaline electrochemical conversion and storage systems. Contrary to the conventional wisdom that the ionic conductivity can be improved by increasing the ion exchange capacity (IEC) through a cross-linking process, in this work, a new approach to improve the ionic conductivity by enhancing the ionic mobility is adopted. The microstructure of quaternary ammonia poly (2, 6-dimethyl-1, 4-phenylene oxide) (QAPPO) is manipulated through grafting with hydrophobic side chains, which will drive the well-established hydrophilic/hydrophobic domains and nano-phase separated, well-connected ionic channels. As a result, the local hydroxide concentration is enhanced by the novel microstructure, thereby improving the ionic conductivity of the as-prepared ionomers. The as-prepared ionomers, denoted as self-aggregated QAPPO-CF, with an intermediate IEC value achieved an ionic conductivity of 65 mS cm-1 at 80 °C, outperforming the QAPPO with an even higher IEC value. This result suggests that the microphase separation is an effective approach to enhance the ionic conductivity.

  13. Hesperetin Modifies the Composition of Fecal Microbiota and Increases Cecal Levels of Short-Chain Fatty Acids in Rats.

    PubMed

    Unno, Tomonori; Hisada, Takayoshi; Takahashi, Shunsuke

    2015-09-16

    There has been particular interest in the prebiotic-like effects of commonly consumed polyphenols. This study aimed to evaluate the effects of hesperidin (HD) and its aglycone hesperetin (HT), major flavonoids in citrus fruits, on the structure and activity of gut microbiota in rats. Rats ingested an assigned diet (a control diet, a 0.5% HT diet, or a 1.0% HD diet) for 3 weeks. Terminal restriction fragment length polymorphism analysis revealed that the proportion of Clostridium subcluster XIVa in the feces collected at the third week of feeding was significantly reduced by the HT diet: 19.8 ± 4.3% for the control diet versus 5.3 ± 1.5% for the HT diet (P < 0.01). There was a significant difference in the cecal pool of short-chain fatty acids (SCFA), the sum of acetic, propionic, and butyric acids, between the control diet (212 ± 71 μmol) and the HT diet (310 ± 51 μmol) (P < 0.05), whereas the HD diet exhibited no effects (245 ± 51 μmol). Interestingly, dietary HT resulted in a significant increase in the excretion of starch in the feces. HT, but not HD, might reduce starch digestion, and parts of undigested starch were utilized to produce SCFA by microbial fermentation in the large intestine. PMID:26306898

  14. Enantioselective toxicities of chiral ionic liquids 1-alkyl-3-methylimidazolium lactate to aquatic algae.

    PubMed

    Chen, Hui; Zou, Yuqin; Zhang, Lijuan; Wen, Yuezhong; Liu, Weiping

    2014-09-01

    With the wide application of chiral ionic liquids (CILs) as green solvents, their threats to the aquatic environment cannot be ignored. Thus, risk assessment and the prospective design of inherently safe CILs have become more urgent. However, whether enantioselectivity is a feature of the aquatic toxicity of CILs is poorly understood. Herein, we describe the first investigation into the ecotoxicities of CILs toward green algae Scenedesmus obliquus and Euglena gracilis. A series of methylimidazolium lactic ionic liquids, which cation parts with different alkyl chains and anion part is enantiomers of lactate, are used as representative CILs. The results of S. obliquus showed that the EC50 value of L-(+)-1-ethyl-3-methylimidazolium lactate (L-(+)-EMIM L) was more than 5000 μM, while the EC50 value of D-(-)-1-ethyl-3-methylimidazolium lactate (D-(-)-EMIM L) was 2255.21 μM. Such a distinct difference indicates the enantioselective toxicity of CILs to algae. This enantioselectivity initially persisted with increasing carbon chain length, but no longer exhibited when with greater carbon chain lengths, due to changes in the toxicity weightings of the cation parts. Further research showed that the enantioselective effects of CILs resulted from the differences in the production of reactive oxygen species, the damage to cell membrane integrity and cell wall after exposure to CILs. Results from this study showed that monitoring for the racemate CILs will give an inadequate or misleading environmental risk assessment. Thus, we should improve our ability to predict their effects in natural environments. In the meantime, non-selective use of CILs will do harm to aquatic organisms. Therefore, to minimize their potential for environmental impact, the enantioselective toxicities of CILs with short alkyl chains should be taken into consideration. PMID:24880783

  15. Silencing of StKCS6 in potato periderm leads to reduced chain lengths of suberin and wax compounds and increased peridermal transpiration

    PubMed Central

    Serra, Olga; Soler, Marçal; Hohn, Carolin; Franke, Rochus; Schreiber, Lukas; Prat, Salomé; Molinas, Marisa; Figueras, Mercè

    2009-01-01

    Very long chain aliphatic compounds occur in the suberin polymer and associated wax. Up to now only few genes involved in suberin biosynthesis have been identified. This is a report on the isolation of a potato (Solanum tuberosum) 3-ketoacyl-CoA synthase (KCS) gene and the study of its molecular and physiological relevance by means of a reverse genetic approach. This gene, called StKCS6, was stably silenced by RNA interference (RNAi) in potato. Analysis of the chemical composition of silenced potato tuber periderms indicated that StKCS6 down-regulation has a significant and fairly specific effect on the chain length distribution of very long-chain fatty acids (VLCFAs) and derivatives, occurring in the suberin polymer and peridermal wax. All compounds with chain lengths of C28 and higher were significantly reduced in silenced periderms, whereas compounds with chain lengths of C26 and lower accumulated. Thus, StKCS6 is preferentially involved in the formation of suberin and wax lipidic monomers with chain lengths of C28 and higher. As a result, peridermal transpiration of the silenced lines was about 1.5-times higher than that of the wild type. Our results convincingly show that StKCS6 is involved in both suberin and wax biosynthesis and that a reduction of the monomeric carbon chain lengths leads to increased rates of peridermal transpiration. PMID:19112170

  16. Probing the Aggregation Behavior of Neat Imidazolium-Based Alkyl Sulfate (Alkyl = Ethyl, Butyl, Hexyl, and Octyl) Ionic Liquids through Time Resolved Florescence Anisotropy and NMR and Fluorescence Correlation Spectroscopy Study.

    PubMed

    Majhi, Debashis; Pabbathi, Ashok; Sarkar, Moloy

    2016-01-14

    Aggregation behavior of a series of neat 1-ethyl 3-methylimidazolium alkyl sulfate (alkyl = ethyl, butyl, hexyl, and octyl) ionic liquids has been investigated through combined time-resolved fluorescence spectroscopy, 1-D and 2-D NMR spectroscopy, and fluorescence correlation spectroscopy (FCS). Interestingly, experimentally measured rotational relaxation times (τr) for ethyl, butyl, hexyl and octyl systems are measured to be 2.25, 1.64, 1.36, and 1.32 times higher than the estimated (from Stokes-Einstein-Debye theory) values for the same respective systems. This indicates that the emitting species is not the monomeric imidazolium moiety rather an associated species, and volume of the rotating fluorescing species decreases even though the length of the alkyl moiety on the anions is increased. The shift in the (1)H proton signal as well as a change in the width of the same signal upon dilution of the neat ionic liquids indicates that ionic liquids exist in the aggregated form. Further investigation through the 2D-ROESY experiment shows that interaction between imidazolium and sulfate is relatively stronger in the ethyl system than that of the longer octyl system. FCS measurements independently show that the hydrodynamic volume decreases with an increase in the anion chain length. The NMR and FCS results are consistent with the findings of the fluorescence anisotropy study. PMID:26654730

  17. Synthesis and Antioxidant Activity of Hydroxytyrosol Alkyl-Carbonate Derivatives.

    PubMed

    Fernandez-Pastor, Ignacio; Fernandez-Hernandez, Antonia; Rivas, Francisco; Martinez, Antonio; Garcia-Granados, Andres; Parra, Andres

    2016-07-22

    Three procedures have been investigated for the isolation of tyrosol (1) and hydroxytyrosol (2) from a phenolic extract obtained from the solid residue of olive milling. These three methods, which facilitated the recovery of these phenols, were chemical or enzymatic acetylation, benzylation, and carbomethoxylation, and subsequent carbonylation or acetonation reactions. Several new lipophilic alkyl-carbonate derivatives of hydroxytyrosol have been synthesized, coupling the primary hydroxy group of this phenol, through a carbonate linker, using alcohols with different chain lengths. The antioxidant properties of these lipophilic derivatives have been evaluated by different methods and compared with free hydroxytyrosol (2) and also with the well-known antioxidants BHT and α-tocopherol. Three methods were used for the determination of this antioxidant activity: FRAP and ABTS assays, to test the antioxidant power in hydrophilic media, and the Rancimat test, to evaluate the antioxidant capacity in a lipophilic matrix. These new alkyl-carbonate derivatives of hydroxytyrosol enhanced the antioxidant activity of this natural phenol, with their antioxidant properties also being higher than those of the commercial antioxidants BHT and α-tocopherol. There was no clear influence of the side-chain length on the antioxidant properties of the alkyl-carbonate derivatives of 2, although the best results were achieved mainly by the compounds with a longer chain on the primary hydroxy group of this natural phenolic substance. PMID:27337069

  18. Alkylation of toluene with ethanol

    SciTech Connect

    Walendziewski, J.; Trawczynski, J.

    1996-10-01

    A series of Y and ZSM-5 zeolite based catalysts was prepared. Zeolites were cation exchanged and formed with 50% of aluminum hydroxide as a binder, and the obtained catalysts were finally thermally treated. Activity tests in alkylation of toluene with ethanol were carried out in the temperature range of 325--400 C, in nitrogen or hydrogen stream, and a pressure up to 3 MPa. The feed consisted of toluene and ethanol mixed in a mole ratio 1/1 or 2/1. The obtained results showed that among the studied catalysts the highest activity in the alkylation reaction was attained by ZSM-5 zeolite based catalyst with a moderate acidity and medium silica to alumina ratio, i.e., {approximately}50. Activity and selectivity of the most active catalyst as well as conversion of the feed components were similar to those reported in other papers. The content of p-ethyltoluene in alkylation products attained ca. 60%.

  19. A biological source of oceanic alkyl nitrates

    NASA Astrophysics Data System (ADS)

    Dahl, E. E.; Lewis, C. B.; Velasco, F. L.; Escobar, C.; Kellogg, D.; Velcamp, M.

    2013-12-01

    Alkyl nitrates are an important component of reactive nitrogen in the troposphere. The oceans are a source of alkyl nitrates to the atmosphere, however the source of alkyl nitrates in the oceans is unknown. It has been demonstrated that the reaction of alkyl peroxy radicals (ROO) with nitric oxide (NO) produces alkyl nitrates in the aqueous phase. We hypothesize that alkyl nitrates may be formed by organisms through the same reaction and therefore biological production could be a source of alkyl nitrates to the troposphere. This work focuses on the production of alkyl nitrates by the diatoms Chaetoceros muelleri and Thalassiosira weisfloggi. Using chemostats, we measure alkyl nitrates formed under nitrate limited conditions. We also use triggers and inhibitors of nitric oxide formation to determine if alkyl nitrate formation is affected by changes in NO production. To date, the rates of production of alkyl nitrates in our cultures, lead us to estimate a production rate on the order of femtomolar/day for C1-C3 alkyl nitrates by diatom species in the equatorial Pacific Ocean. This suggests that diatoms may contribute to the overall ocean source of alkyl nitrates; however, it is possible that other types of phytoplankton, such as cyanobacteria, that are more abundant in the open ocean, may contribute to a greater extent.

  20. Phosphine-alkene ligand-mediated alkyl-alkyl and alkyl-halide elimination processes from palladium(II).

    PubMed

    Tuxworth, Luke; Baiget, Lise; Phanopoulos, Andreas; Metters, Owen J; Batsanov, Andrei S; Fox, Mark A; Howard, Judith A K; Dyer, Philip W

    2012-10-28

    N-Diphenylphosphino-7-aza-benzobicyclo[2.2.1]hept-2-ene (2) behaves as a chelating phosphine-alkene ligand for Pd(0) and Pd(II), promoting direct alkyl-alkyl and indirect alkyl-halide reductive elimination reactions due to the stabilisation of the resulting bis(phosphine-alkene)Pd(0) complex. PMID:22986447

  1. Studies of structural, dynamical, and interfacial properties of 1-alkyl-3-methylimidazolium iodide ionic liquids by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Ghatee, Mohammad Hadi; Zolghadr, Amin Reza; Moosavi, Fatemeh; Ansari, Younes

    2012-03-01

    Bulk and surface properties of the ionic liquids 1-alkyl-3-methyl-imidazolium iodides ([Cnmim]I) were simulated by classical molecular dynamics using all atom non-polarizable force field (n = 4, butyl; 6, hexyl; 8, octyl). The structure of ionic liquids were initially optimized by density functional theory and atomic charges obtained by CHELPG method. Reduction of partial atomic charges (by 20% for simulation of density and surface tension, and by 10% for viscosity) found to improve the accuracy, while a non-polarizable force field was applied. Additionally, the simulation ensembles approach the equilibrium faster when the charge reduction is applied. By these refined force field parameters, simulated surface tensions in the range of 323-393 k are quite in agreement with the experiments. Simulation of temperature dependent surface tension of [C4mim]I well beyond room temperature (up to 700 K) permits prediction of the critical temperature in agreement with that predicted from experimental surface tension data. Simulated densities in the range of 298-450 K for the three ionic liquids are within 0.8% of the experimental data. Structural properties for [C4mim]I were found to be in agreement with the results of Car-Parrinello molecular dynamics simulation we performed, which indicates a rather well-structured cation-anion interaction and occurs essentially through the imidazolium ring cation. Diffusion coefficient changes with alkyl chain length in the order of [C8mim]I > [C6mim]I > [C4mim]I for the cation and the anion. Formation of a dense domain in subsurface region is quite evident, and progressively becomes denser as the alkyl chain length increases. Bivariate orientational analysis was used to determine the average orientation of molecule in ionic liquids surface, subsurface, and bulk regions. Dynamic bisector-wise and side-wise movement of the imodazolium ring cation in the surface region can be deduced from the bivariate maps. Atom-atom density profile and

  2. Chemistry of alkali cation exchanged faujasite and mesoporous NaX using alkyl halides and phosphates

    NASA Astrophysics Data System (ADS)

    Lee, Min-Hong

    the length of the alkyl chain. Although introduced mesopores alleviated the limited reagent diffusion to reactive sites due to the microporosity of the NaX zeolites, no marked improvement in the product yields was achieved with either the 1-chloroalkanes or the trialkyl phosphates test compounds, regardless of alkyl chain length. The disappointing results have been attributed to lack of substantial net increase in the numbers of zeolite nucleophilic sites accompanying mesopore introduction.

  3. Self-organization of surfactant molecules on solid surface: an STM study of sodium alkyl sulfonates [rapid communication

    NASA Astrophysics Data System (ADS)

    Yin, Xiu-Li; Wan, Li-Jun; Yang, Zheng-Yu; Yu, Jia-Yong

    2005-02-01

    Adsorption and self-organization of sodium alkyl sulfonates (STS and SHS) on HOPG have been studied by using in situ scanning tunneling microscopy (STM). Both SHS and STS molecules adsorb on HOPG surface and form long-range well-ordered monolayers. The molecular rows and the axes of alkyl chain of the molecules cross each other at angles of 60° and 90° in the STS and SHS layers, respectively. Molecular details such as sulfonate functional group (head) and alkyl chain are clearly imaged. The neighboring molecules in different rows form a "head to head" configuration. Structural models for the molecular arrangement of the two adlayers are proposed.

  4. Reduced cardiolipin content decreases respiratory chain capacities and increases ATP synthesis yield in the human HepaRG cells.

    PubMed

    Peyta, Laure; Jarnouen, Kathleen; Pinault, Michelle; Guimaraes, Cyrille; Pais de Barros, Jean-Paul; Chevalier, Stephan; Dumas, Jean-François; Maillot, François; Hatch, Grant M; Loyer, Pascal; Servais, Stephane

    2016-04-01

    Cardiolipin (CL) is a unique mitochondrial phospholipid potentially affecting many aspects of mitochondrial function/processes, i.e. energy production through oxidative phosphorylation. Most data focusing on implication of CL content and mitochondrial bioenergetics were performed in yeast or in cellular models of Barth syndrome. Previous work reported that increase in CL content leads to decrease in liver mitochondrial ATP synthesis yield. Therefore the aim of this study was to determine the effects of moderate decrease in CL content on mitochondrial bioenergetics in human hepatocytes. For this purpose, we generated a cardiolipin synthase knockdown (shCLS) in HepaRG hepatoma cells showing bioenergetics features similar to primary human hepatocytes. shCLS cells exhibited a 55% reduction in CLS gene and a 40% decrease in protein expression resulting in a 45% lower content in CL compared to control (shCTL) cells. Oxygen consumption was significantly reduced in shCLS cells compared to shCTL regardless of substrate used and energy state analyzed. Mitochondrial low molecular weight supercomplex content was higher in shCLS cells (+60%) compared to shCTL. Significant fragmentation of the mitochondrial network was observed in shCLS cells compared to shCTL cells. Surprisingly, mitochondrial ATP synthesis was unchanged in shCLS compared to shCTL cells but exhibited a higher ATP:O ratio (+46%) in shCLS cells. Our results suggest that lowered respiratory chain activity induced by moderate reduction in CL content may be due to both destabilization of supercomplexes and mitochondrial network fragmentation. In addition, CL content may regulate mitochondrial ATP synthesis yield. PMID:26768115

  5. Enantioselective toxicities of chiral ionic liquids 1-alkyl-3-methyl imidazolium tartrate on Scenedesmus obliquus.

    PubMed

    Liu, Huijun; Zhang, Xiaoqiang; Dong, Ying; Chen, Caidong; Zhu, Shimin; Ma, Xiangjuan

    2015-12-01

    Ionic liquids (ILs) are being used in various industries during the last few decades, while the good solubility and high stability of ILs may pose a potential threat to the aquatic environment. Effect of chiral ionic liquids (CILs) 1-alkyl-3-methyl imidazolium tartrate (RMIM T) on Scenedesmus obliquus (S.obliquus) was studied. The growth rate inhibition and cell membrane permeability increased with increasing RMIM T concentration and increasing alkyl chain lengths. The IC50 values of D-(-)-tartrate 1-hexyl-3-methyl imidazolium (D-(-)-HMIM T) were 28.30, 12.23,10.15 and 14.41 mg/L, respectively, at 24, 48, 72 and 96h. While that of L-(+)-tartrate 1-hexyl-3-methyl imidazolium (L-(+)-HMIM T) were 15.97, 7.91, 9.43 and 12.04 mg/L respectively. The concentration of chl a, chl b and chl (a+b) decreased with increasing RMIM T concentration. The chlorophyll fluorescence parameters (F0, Fv/Fm, Fv/F0, Y(II), ETR and NPQ) were affected by RMIM T, indicating that the RMIM T will damage the PSII, inhibit the transmission of excitation energy, decrease the efficiency of photosynthesis. The results showed that there were enantioselective toxicity of RMIM T to algae, and the toxicity of L-(+)-RMIM T was greater than that of D-(-)-RMIM T, but the enantioselective difference becomes smaller with increasing exposure time, and with the increasing carbon chain length of cation, indicating that cation properties may have a larger effect on toxicity than anion properties. PMID:26554523

  6. 40 CFR 721.9892 - Alkylated urea.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under...

  7. 40 CFR 721.9892 - Alkylated urea.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under...

  8. 40 CFR 721.9892 - Alkylated urea.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under...

  9. 40 CFR 721.9892 - Alkylated urea.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under...

  10. 40 CFR 721.9892 - Alkylated urea.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under...

  11. Oil compositions containing alkyl amine or alkyl mercaptan derivatives of copolymers of an alpha olefin or an alkyl vinyl ether

    SciTech Connect

    Le, H.T.

    1990-02-13

    This patent describes an oil composition. It comprises a major amount of an oil selected from a crude oil or fuel oil and a minor amount of an alkyl amine or alkyl mercaptan derivative of an alpha olefin or alkyl vinyl ether and an unsaturated alpha, beta-dicarboxylic compound copolymer having pour point depressant ;properties. The copolymer comprising the reaction product of an alpha olefin having from about 2 to about 30 carbon atoms or mixtures of alpha olefins having from about 2 to about 30 carbon atoms or an alkyl vinyl ether or mixture of alkyl vinyl ethers.

  12. Extended 3{beta}-alkyl steranes and 3-alkyl triaromatic steroids in crude oils and rock extracts

    SciTech Connect

    Dahl, J.; Moldowan, J.M.; Summons, R.E.

    1995-09-01

    In oils and Precambian- to Miocene-age source rocks from varying depositional environments, we have conclusively identified several novel 3-alkyl sterane and triaromatic steroid series, including (1) 3{beta}-n-pentyl steranes, (2) 3{beta}-isopentyl steranes, (3) 3{beta}-n-hexyl steranes, (4) 3{beta}-n-hepatyl steranes, (5) 3,4-dimethyl steranes, (6) 3{beta}-butyl,4-methyl steranes, (7) triaromatic 3-n-pentyl steroids, and (8) triaromatic 3-isopentyl steroids. We have also tentatively identified additional homologs with 3-alkyl substituents as large as C{sub 11}. The relative abundances of these compounds vary substantially between samples, as indicated by (1) the ratio of 3{beta}-n-pentyl steranes to 3{beta}-isopentyl steranes and (2) the ratio of 3-n-pentyl triaromatic steroids to 3-isopentyl triaromatic steroids. These data suggest possible utility for these parameters as tools for oil-source rock correlations and reconstruction of depositional environments. Although no 3-alkyl steroid natural products are currently known, several lines of evidence suggest that 3{beta}-alkyl steroids result from bacterial side-chain additions to diagenetic {delta}{sup 2}-sterenes.

  13. Permeability profile of poly(alkyl cyanoacrylate) nanocapsules.

    PubMed

    Erdmann, Christian; Mayer, Christian

    2016-09-15

    The permeability profile of poly(alkyl cyanoacrylate) nanocapsules is studied using pulsed-field gradient NMR on a variety of tracer molecules of different size and polarity. In addition, the influence of the surfactant layer and of organic tracer molecules on the capsule membrane permeability for water is examined. The aim of the study is a detailed understanding of the dependencies between molecular properties of a given tracer and its capability to permeate the polymer membrane. As expected, the results clearly show that the capsule membrane permeability depends on the size of the tracer molecule: the exchange rate of polyethylene glycols continuously decreases with increasing chain length. However, the permeation rate also varies with the polarity of the tracer molecule: molecules of lower polarity exchange faster than more polar ones. In turn, the capsule membrane permeability is influenced by added organic compounds. Focusing on water as a characteristic permeate and depending on the type of the additive, the permeability can be varied by almost an order of magnitude, offering an opportunity to reversibly switch the uptake and release properties of the capsules. PMID:27343463

  14. Alkylation of imidazole under ultrasound irradiation over alkaline carbons

    NASA Astrophysics Data System (ADS)

    Costarrosa, L.; Calvino-Casilda, V.; Ferrera-Escudero, S.; Durán-Valle, C. J.; Martín-Aranda, R. M.

    2006-06-01

    N-Alkyl-imidazole has been synthesized by sonochemical irradiation of imidazole and 1-bromobutane using alkaline-promoted carbons (exchanged with the binary combinations of Na, K and Cs). The catalysts were characterized by X-ray photoelectron spectroscopy, thermal analysis and N 2 adsorption isotherms. Under the experimental conditions, N-alkyl-imidazoles can be prepared with a high activity and selectivity. It is observed that imidazole conversion increases in parallel with increasing the basicity of the catalyst. The influence of the alkaline promoter, the reaction temperature, and the amount of catalyst on the catalytic activity has been studied. For comparison, the alkylation of imidazole has also been performed in a batch reactor system under thermal activation.

  15. Microemulsions containing long-chain oil ethyl oleate improve the oral bioavailability of piroxicam by increasing drug solubility and lymphatic transportation simultaneously.

    PubMed

    Xing, Qiao; Song, Jia; You, Xiuhua; Xu, Dongling; Wang, Kexin; Song, Jiaqi; Guo, Qin; Li, Pengyu; Wu, Chuanbin; Hu, Haiyan

    2016-09-25

    Drug solubility and lymphatic transport enhancements are two main pathways to improve drug oral bioavailability for microemulsions. However, it is not easy to have both achieved simultaneously because excipients used for improving lymphatic transport were usually insufficient in forming microemulsions and solubilizing drugs. Our research is to explore whether ethyl oleate, an oil effective in developing microemulsions with desired solubilizing capability, could increase bioavailability to a higher extent by enhancing lymphatic transport. As a long-chain oil, ethyl oleate won larger microemulsion area than short-chain tributyrin and medium-chain GTCC. In contrast, long-chain soybean oil failed to prepare microemulsions. The solubility of piroxicam in ethyl oleate microemulsions (ME-C) increased by about 30 times than in water. ME-C also won significantly higher AUC0-t compared with tributyrin microemulsions (ME-A) and GTCC microemulsions (ME-B). Oral bioavailability in ME-C decreased by 38% after lymphatic transport was blocked by cycloheximide, severer than those in ME-A and ME-B (8% and 34%). These results suggest that improving lymphatic transport and solubility simultaneously might be a novel strategy to increase drug oral bioavailability to a higher extent than increasing solubility only. Ethyl oleate is a preferred oil candidate due to its integrated advantages of high solubilizing capability, large microemulsion area and effective lymphatic transport. PMID:27473280

  16. Depletion of Phosphatidylcholine in Yeast Induces Shortening and Increased Saturation of the Lipid Acyl Chains: Evidence for Regulation of Intrinsic Membrane Curvature in a Eukaryote

    PubMed Central

    Boumann, Henry A.; Gubbens, Jacob; Koorengevel, Martijn C.; Oh, Chan-Seok; Martin, Charles E.; Heck, Albert J.R.; Patton-Vogt, Jana; Henry, Susan A.; de Kruijff, Ben; de Kroon, Anton I.P.M.

    2006-01-01

    To study the consequences of depleting the major membrane phospholipid phosphatidylcholine (PC), exponentially growing cells of a yeast cho2opi3 double deletion mutant were transferred from medium containing choline to choline-free medium. Cell growth did not cease until the PC level had dropped below 2% of total phospholipids after four to five generations. Increasing contents of phosphatidylethanolamine (PE) and phosphatidylinositol made up for the loss of PC. During PC depletion, the remaining PC was subject to acyl chain remodeling with monounsaturated species replacing diunsaturated species, as shown by mass spectrometry. The remodeling of PC did not require turnover by the SPO14-encoded phospholipase D. The changes in the PC species profile were found to reflect an overall shift in the cellular acyl chain composition that exhibited a 40% increase in the ratio of C16 over C18 acyl chains, and a 10% increase in the degree of saturation. The shift was stronger in the phospholipid than in the neutral lipid fraction and strongest in the species profile of PE. The shortening and increased saturation of the PE acyl chains were shown to decrease the nonbilayer propensity of PE. The results point to a regulatory mechanism in yeast that maintains intrinsic membrane curvature in an optimal range. PMID:16339082

  17. Depletion of phosphatidylcholine in yeast induces shortening and increased saturation of the lipid acyl chains: evidence for regulation of intrinsic membrane curvature in a eukaryote.

    PubMed

    Boumann, Henry A; Gubbens, Jacob; Koorengevel, Martijn C; Oh, Chan-Seok; Martin, Charles E; Heck, Albert J R; Patton-Vogt, Jana; Henry, Susan A; de Kruijff, Ben; de Kroon, Anton I P M

    2006-02-01

    To study the consequences of depleting the major membrane phospholipid phosphatidylcholine (PC), exponentially growing cells of a yeast cho2opi3 double deletion mutant were transferred from medium containing choline to choline-free medium. Cell growth did not cease until the PC level had dropped below 2% of total phospholipids after four to five generations. Increasing contents of phosphatidylethanolamine (PE) and phosphatidylinositol made up for the loss of PC. During PC depletion, the remaining PC was subject to acyl chain remodeling with monounsaturated species replacing diunsaturated species, as shown by mass spectrometry. The remodeling of PC did not require turnover by the SPO14-encoded phospholipase D. The changes in the PC species profile were found to reflect an overall shift in the cellular acyl chain composition that exhibited a 40% increase in the ratio of C16 over C18 acyl chains, and a 10% increase in the degree of saturation. The shift was stronger in the phospholipid than in the neutral lipid fraction and strongest in the species profile of PE. The shortening and increased saturation of the PE acyl chains were shown to decrease the nonbilayer propensity of PE. The results point to a regulatory mechanism in yeast that maintains intrinsic membrane curvature in an optimal range. PMID:16339082

  18. A novel iridium/acid co-catalyzed transfer hydrogenative C(sp(3))-H bond alkylation to access functionalized N-heteroaromatics.

    PubMed

    Tan, Zhenda; Jiang, Huanfeng; Zhang, Min

    2016-08-01

    A novel iridium/acid co-catalysed transfer hydrogenative coupling strategy, enabling direct alkylation of C(sp(3))-H bonds and atom-economic access to alkyl chain-lengthened N-heteroaromatics from six-membered 2-alkyl cyclic amines and aldehydes, has been demonstrated. This work has built an important basis to convert cyclic amines, a class of bulk chemical raw materials, into functionalized products. PMID:27355181

  19. Morphology of 1-alkyl-3-methylimidazolium hexafluorophosphate room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Triolo, Alessandro; Russina, Olga; Fazio, Barbara; Triolo, Roberto; Di Cola, Emanuela

    2008-05-01

    The structural organization in selected room temperature ionic liquids, namely (a) butyl-, (b) hexyl- and (c) octyl-3-methylimidazolium hexafluorophosphate, is investigated by means of X-ray diffraction. We find novel experimental evidences of the existence of a high degree of intermediate range order that is associated to nanoscale segregation of the alkyl chains into the charged matrix. The size of these structural heterogeneities depends linearly from the alkyl chain length. A similar behaviour had been observed in other systems, such as normal alcohols. The slope of such dependence provides hints on the nature of the structural organization of these segregated domains.

  20. Alkyl polycyclic aromatic hydrocarbons emissions in diesel/biodiesel exhaust

    NASA Astrophysics Data System (ADS)

    Casal, Carina S.; Arbilla, Graciela; Corrêa, Sergio M.

    2014-10-01

    Polycyclic aromatic hydrocarbons (PAHs) are widely studied in environmental matrices, such as air, water, soil and sediment, because of their toxicity, mutagenicity and carcinogenicity. Because of these properties, the environmental agencies of developed countries have listed sixteen PAHs as priority pollutants. Few countries have limits for these compounds for ambient air, but they only limit emissions from stationary and mobile sources and occupational areas. There are several studies to specifically address the 16 priority PAHs and very little for the alkyl PAHs. These compounds are more abundant, more persistent and frequently more toxic than the non-alkylated PAHs, and the toxicity increases with the number of alkyl substitutions on the aromatic ring. In this study, a method was developed for the analysis of PAHs and alkyl PAHs by using a GC-MS and large injection volume injection coupled with program temperature vaporisation, which allows for limits of detection below 1.0 ng μL-1. Several variables were tested, such as the injection volume, injection velocity, injector initial temperature, duration of the solvent split and others. This method was evaluated in samples from particulate matter from the emissions of engines employing standard diesel, commercial diesel and biodiesel B20. Samples were collected on a dynamometer bench for a diesel engine cycle and the results ranged from 0.5 to 96.9 ng mL-1, indicating that diesel/biodiesel makes a significant contribution to the formation of PAHs and alkyl PAHs.

  1. Kinetics of the reactions of trichlorosilane with alkyl chlorides in the gas phase

    SciTech Connect

    Chernishev, E.A.; Bykovchenko, V.G.; Kisileva, T.S.; Silkina, N.N.

    1987-04-01

    The kinetics of vapor phase reactions of trichlorosilane (TCS) with alkyl chlorides, namely, CCl/sub 4/, HCCl/sub 3/, and H/sub 2/CCl/sub 2/, have been studied. The indicated reactions have been found to be first order with respect to TCS and half-order with respect to alkyl chlorides. The Arrhenius kinetic parameters for these reactions have also been determined. Within the temperature range 400-580/sup 0/C, the reactivity of alkyl chlorides with TCS has been shown to decrease in the order: CCl/sub 4/ > HCCl/sub 3/ > H/sub 2/CCl/sub 2/. A radical chain mechanism, which is assumed to operate in the reactions of TCS with alkyl chlorides, is examined in the case of the reaction of TCS with CCl/sub 4/.

  2. Bacteria-driven production of alkyl nitrates in seawater

    NASA Astrophysics Data System (ADS)

    Kim, Michelle J.; Michaud, Jennifer M.; Williams, Renee; Sherwood, Byron Pedler; Pomeroy, Robert; Azam, Farooq; Burkart, Michael; Bertram, Timothy H.

    2015-01-01

    and ship-borne measurements have shown that the ocean is a large, diffuse source for short chain (C1-C3) gas phase alkyl nitrates (RONO2). Photochemical production of RONO2 has been demonstrated previously as a viable mechanism in surface waters; however, it cannot account for the observed depth profile of RONO2, suggesting an additional, dark RONO2 production mechanism. We present measurements of gas phase C1-C5 alkyl nitrates emitted from seawater in a controlled mesocosm experiment conducted under low-light conditions in a glass-walled wave channel. Ethyl and butyl nitrate emission rates from seawater are strongly correlated with the abundance of heterotrophic bacteria (R2 ≥ 0.89) and show no correlation to chlorophyll a concentration. Controlled flask experiments conducted using ambient and sterile seawater, inoculated with a heterotrophic bacterium, confirm that bacterial driven production of select RONO2 can proceed efficiently in the absence of light.

  3. Levels and pattern of alkyl nitrates, multifunctional alkyl nitrates, and halocarbons in the air over the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Fischer, Ralf G.; Kastler, Jürgen; Ballschmiter, Karlheinz

    2000-06-01

    The Albatross Campaign was a research cruise of the German research vessel RV Polarstern (cruise ANT XFV/1) in October and November 1996 across the Atlantic Ocean. The cruise started in Bremerhaven, Germany, reached the polar region at 67°N, followed the 30°W meridian longitude, crossed the equatorial region, and ended at 50°S at Punta Quilla, Argentina. A second cruise leg closer to the African continent started from Capetown, South Africa, passed the Canary Island, and ended through the English Channel at Bremerhaven, Germany, in May/June 1998. Measurements of atmospheric levels of C1-C13 alkyl mononitrates, 24 alkyl dinitrates (C3-C6), 19 hydroxy alkyl nitrates (C2-C6), and benzyl nitrate, as well as the halocarbons tetrachloroethene, hexachloroethane, and bromoform are presented in this work. The halocarbons are used to assess the origin of the air parcels analyzed. Levels and patterns of multifunctional alkyl nitrates in the marine air are described here for the first time. The air masses include polluted air from the northern Europe, as well as highly degraded air masses of the South Atlantic trade wind region that represent global baseline levels. Two independent analytical methods were used in combination to cover the whole range of organic nitrates. First, the low-volume adsorptive enrichment of organic traces on Tenax, followed by thermodesorption cold trap HRGC-ECD and thermodesorption cold trap HRGC-(EI)MSD was used. Second, high-volume adsorptive enrichment of organic traces on silica gel was applied followed by solvent desorption, NP-HPLC group separation, and HRGC-(EI)-MSD. Short-chain alkyl nitrates (C4-C6) showed mixing ratios in the range of 0.2-2.5 parts per trillion by volume (pptv), with a local minimum for the tropical regions and significantly lower ratios for the Southern Hemisphere. The mixing ratio of the sum of 36 long-chain alkyl mononitrates (C7-C13) ranged from 0.02-0.43 pptv, the mixing ratio of the sum of 23 alkyl dinitrates (C3-C

  4. Methods of making alkyl esters

    DOEpatents

    Elliott, Brian

    2010-08-03

    A method comprising contacting an alcohol, a feed comprising one or more glycerides and equal to or greater than 2 wt % of one or more free fatty acids, and a solid acid catalyst, a nanostructured polymer catalyst, or a sulfated zirconia catalyst in one or more reactors, and recovering from the one or more reactors an effluent comprising equal to or greater than about 75 wt % alkyl ester and equal to or less than about 5 wt % glyceride.

  5. PREPARATION OF ALKYL PYROPHOSPHATE EXTRACTANTS

    DOEpatents

    Levine, C.A.; Skiens, W.E.; Moore, G.R.

    1960-08-01

    A process for providing superior solvent extractants for metal recovery processes is given wherein the extractant comprises an alkyl pyrophosphoric acid ester dissolved in an organic solvent diluent. Finely divided solid P/sub 2/O/ sub 5/ is slurried in an organic solvent-diluent selected from organic solvents such as kerosene, benzene, chlorobenzene, toluene, etc. An alcohol selected from the higher alcohols having 4 to 17 carbon atoms. e.g.. hexanol-1. heptanol-3, octanol-1. 2.6-dimethyl-heptanol-4, and decanol-1, is rapidly added to the P/sub 2/O/sub 5/ slurry in the amount of about 2 moles of alcohol to 1 mole of P/sub 2/ O/sub 5/. The temperature is maintained below about 110 deg C during the course of the P/sub 2/O/sub 5/-alcohol reaction. An alkyl pyrophosphate extractant compound is formed as a consequence of the reaction process. The alkyl pyrophosphate solvent-diluent extractant phase is useful in solvent extraction metal recovery processes.

  6. Alkyl substituent effect on density, viscosity and chemical behavior of 1-alkyl-3-methylimidazolium chloride.

    PubMed

    Olmo, Lourdes del; Lage-Estebanez, Isabel; López, Rafael; García de la Vega, José M

    2014-09-01

    Molecular structure of the conformers of 1-C n -3-methylimidazolium chloride (n = 1 to 4) ionic liquids has been explored and the relationships with density and viscosity have been studied using COSMO related methodologies. Effects of the number of conformers, ionic character, anion-cation relative positions and the alkyl chain length of the cation on predictions of properties have been analyzed. The quality of the predictions has been tested by comparing with experimental results. Moreover, COSMO polarization charge densities, σ-profiles and σ-potentials of the conformers have been analyzed. Predictions on the chemical behavior based on the values of these properties in the conformers have been used to elucidate the affinity for electrophilic and nucleophilic reagents of ionic liquids. PMID:25149437

  7. Polymerization of aniline and alkyl ring-substituted anilines in the presence of aromatic additives

    SciTech Connect

    Wei, Yen; Jang, Guangway; Chan, Chicheung; Hsueh, K.F.; Hariharan, R.; Patel, S.A.; Whitecar, C.K. )

    1990-09-20

    A new synthetic method for the preparation of electrically conductive polyaniline and alkyl ring-substituted polyanilines is presented, in which a small amount of aromatic additives is introduced into both chemical and electrochemical polymerization systems. In the presence of the additives, such as p-aminodiphenylamine, benzidine, and p-phenoxyaniline, the rate of polyaniline formation increases greatly; and lower applied potentials, e.g., 0.55 V vs SCE, or milder oxidants, e.g., O{sub 2}, can be effectively employed in the polymerization. All of these additives have lower oxidation potentials than the aniline monomers and at least one sterically accessible aromatic amino group which allow their incorporation into polymer chains as a part of the structural backbones. In contrast, addition of N,N-diphenylamine or hydroquinone to the polymerization system reduces the rate of polymer formation. The results are consistent with the proposed mechanism of polymerization.

  8. The effect of ultrasound on the catalytic activity of alkaline carbons: preparation of N-alkyl imidazoles

    NASA Astrophysics Data System (ADS)

    Durán-Valle, C. J.; Ferrera-Escudero, S.; Calvino-Casilda, V.; Díaz-Terán, J.; Martín-Aranda, R. M.

    2004-11-01

    N-Alkyl imidazoles have been prepared by sonochemical irradiation of imidazole and 1-bromobutane using alkaline promoted carbons. Under the experimental conditions, N-alkyl imidazoles can be prepared with a high activity and selectivity. It is observed that imidazole conversion increases in parallel with increasing basicity of the catalyst. For comparison, the alkylation of imidazole has also been performed in a batch reactor system under thermal activation.

  9. ESCHERICHIA COLI Gene Induction by Alkylation Treatment

    PubMed Central

    Volkert, Michael R.; Nguyen, Dinh C.; Beard, K. Christopher

    1986-01-01

    Searches for alkylation-inducible (aid) genes of Escherichia coli have been conducted by screening random fusions of the Mu-dl(ApR lac) phage for fusions showing increased β-galactosidase activity after treatment with methylating agents, but not after treatments with UV-irradiation. In this report we describe gene fusions that are specifically induced by alkylation treatments. Nine new mutants are described, and their properties are compared with the five mutants described previously. The total of 14 fusion mutants map at five distinct genetic loci. They can be further subdivided on the basis of their induction by methyl methanesulfonate (MMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). alkA, aidB and aidD are induced by both agents and appear to be regulated by ada. Neither aidC nor aidI is regulated by ada. Moreover, since aidC is induced only by MNNG and aidI is induced only by MMS, these two genes are likely to be individually regulated. Thus, there appear to be at least three different regulatory mechanisms controlling aid genes. PMID:3080354

  10. Platelet-activating factor acetylhydrolase: selective inhibition by potent n-alkyl methylphosphonofluoridates.

    PubMed

    Quistad, Gary B; Fisher, Karl J; Owen, Sarah C; Klintenberg, Rebecka; Casida, John E

    2005-06-01

    Platelet-activating factor (PAF) is a potent endogenous phospholipid modulator of diverse biological activities, including inflammation and shock. PAF levels are primarily regulated by PAF acetylhydrolases (PAF-AHs). These enzymes are candidate secondary targets of organophosphorus (OP) pesticides and related toxicants. Previously known OP inhibitors of other serine hydrolases were tested with PAF-AH from mouse brain and testes of established functional importance compared with the structurally different human plasma enzyme. Several key OP pesticides and their oxon metabolites were very poor inhibitors of mouse brain and human plasma PAF-AH in vitro but moderately active for mouse brain and blood PAF-AH in vivo (e.g., tribufos defoliant and profenofos insecticide, presumably following oxidative bioactivation). OP compounds were then designed for maximum in vitro potency and selectivity for mouse brain PAF-AH vs. acetylcholinesterase (AChE). Lead compounds were found in a series of benzodioxaphosphorin 2-oxides. Ultrahigh potency and selectivity were achieved with n-alkyl methylphosphonofluoridates (long-chain sarin analogs): mouse brain and testes IC50 < or = 5 nM for C(8)-C(18) analogs and 0.1-0.6 nM for C(13) and C(14) compounds; human plasma IC50 < or = 2 nM for C(13)-C(18) analogs. AChE inhibitory potency decreased as chain length increased with maximum brain PAF-AH/AChE selectivity (>3000-fold) for C(13)-C(18) compounds. The toxicity of i.p.-administered PAF (LD50 ca. 0.5 mg/kg) was increased less than 2-fold by pretreatment with tribufos or the C(13)n-alkyl methylphosphonofluoridate. These studies with a mouse model indicate that PAF-AH is not a major secondary target of OP pesticide poisoning. The optimized PAF-AH inhibitors may facilitate investigations on other aspects of PAF metabolism and action. PMID:15893542

  11. Oxidation of Alkyl-substituted Cyclic Hydrocarbons by a Nocardia during Growth on n-Alkanes

    PubMed Central

    Davis, J. B.; Raymond, R. L.

    1961-01-01

    Nocardia 107-332, a soil isolate, oxidizes short-chain alkyl-substituted cyclic hydrocarbons to cyclic acids while growing on n-alkanes. Cyclic acids are produced also from relatively long-chain alkyl-substituted cyclics such as n-nonylbenzene or n-dodecylbenzene which alone support growth in a mineral-salts medium. ω-Oxidation of the alkyl substituents is followed by β-oxidation. It is of particular interest that cyclic acids such as cyclohexaneacetic and phenylacetic with C2 residual carboxylic acid substituents are resistant to further oxidation by the nocardia but cyclic acids with C1 or C3 substituents are readily oxidized and utilized for growth. The specificity of microbial oxidations is demonstrated by the conversion of p-isopropyltoluene (p-cymene) to p-isopropylbenzoic acid in n-alkane, growth-supported nocardia cultures. PMID:13720182

  12. Lateral diffusion of specific antibodies bound to lipid monolayers on alkylated substrates.

    PubMed Central

    Subramaniam, S; Seul, M; McConnell, H M

    1986-01-01

    We have measured the lateral mobility of fluoresceinated monoclonal IgG antibodies bound specifically to a spin label lipid hapten in phospholipid monolayers supported on alkylated silicon oxide surfaces. Dimyristoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine monolayers containing 5 mol% of the lipid hapten were transferred by conventional Langmuir-Blodgett techniques onto substrates alkylated with hydrocarbon chains containing 10, 16, and 18 carbon atoms. We show that the diffusion of the bound antibodies depends on their lateral density, the composition of the lipid monolayer, and the nature of lipid coupling to hydrocarbon chains on the alkylated substrate. Antibody diffusion coefficients at low antibody densities are within a factor of 2 of those displayed by the lipid hapten in the absence of the bound antibody. High antibody densities result in reduced antibody mobility, but the lateral diffusion of unbound lipids is unaffected. Images PMID:3006037

  13. Methods and Mechanisms for Cross-Electrophile Coupling of Csp(2) Halides with Alkyl Electrophiles.

    PubMed

    Weix, Daniel J

    2015-06-16

    Cross-electrophile coupling, the cross-coupling of two different electrophiles, avoids the need for preformed carbon nucleophiles, but development of general methods has lagged behind cross-coupling and C-H functionalization. A central reason for this slow development is the challenge of selectively coupling two substrates that are alike in reactivity. This Account describes the discovery of generally cross-selective reactions of aryl halides and acyl halides with alkyl halides, the mechanistic studies that illuminated the underlying principles of these reactions, and the use of these fundamental principles in the rational design of new cross-electrophile coupling reactions. Although the coupling of two different electrophiles under reducing conditions often leads primarily to symmetric dimers, the subtle differences in reactivity of aryl halides and alkyl halides with nickel catalysts allowed for generally cross-selective coupling reactions. These conditions could also be extended to the coupling of acyl halides with alkyl halides. These reactions are exceptionally functional group tolerant and can be assembled on the benchtop. A combination of stoichiometric and catalytic studies on the mechanism of these reactions revealed an unusual radical-chain mechanism and suggests that selectivity arises from (1) the preference of nickel(0) for oxidative addition to aryl halides and acyl halides over alkyl halides and (2) the greater propensity of alkyl halides to form free radicals. Bipyridine-ligated arylnickel intermediates react with alkyl radicals to efficiently form, after reductive elimination, new C-C bonds. Finally, the resulting nickel(I) species is proposed to regenerate an alkyl radical to carry the chain. Examples of new reactions designed using these principles include carbonylative coupling of aryl halides with alkyl halides to form ketones, arylation of epoxides to form β-aryl alcohols, and coupling of benzyl sulfonate esters with aryl halides to form

  14. Methods and Mechanisms for Cross-Electrophile Coupling of Csp2 Halides with Alkyl Electrophiles

    PubMed Central

    2016-01-01

    Conspectus Cross-electrophile coupling, the cross-coupling of two different electrophiles, avoids the need for preformed carbon nucleophiles, but development of general methods has lagged behind cross-coupling and C–H functionalization. A central reason for this slow development is the challenge of selectively coupling two substrates that are alike in reactivity. This Account describes the discovery of generally cross-selective reactions of aryl halides and acyl halides with alkyl halides, the mechanistic studies that illuminated the underlying principles of these reactions, and the use of these fundamental principles in the rational design of new cross-electrophile coupling reactions. Although the coupling of two different electrophiles under reducing conditions often leads primarily to symmetric dimers, the subtle differences in reactivity of aryl halides and alkyl halides with nickel catalysts allowed for generally cross-selective coupling reactions. These conditions could also be extended to the coupling of acyl halides with alkyl halides. These reactions are exceptionally functional group tolerant and can be assembled on the benchtop. A combination of stoichiometric and catalytic studies on the mechanism of these reactions revealed an unusual radical-chain mechanism and suggests that selectivity arises from (1) the preference of nickel(0) for oxidative addition to aryl halides and acyl halides over alkyl halides and (2) the greater propensity of alkyl halides to form free radicals. Bipyridine-ligated arylnickel intermediates react with alkyl radicals to efficiently form, after reductive elimination, new C–C bonds. Finally, the resulting nickel(I) species is proposed to regenerate an alkyl radical to carry the chain. Examples of new reactions designed using these principles include carbonylative coupling of aryl halides with alkyl halides to form ketones, arylation of epoxides to form β-aryl alcohols, and coupling of benzyl sulfonate esters with aryl

  15. Activation of protein phosphatase 2A is responsible for increased content and inactivation of respiratory chain complex i induced by all-trans retinoic acid in human keratinocytes.

    PubMed

    Papa, F; Sardaro, N; Lippolis, R; Panelli, D; Scacco, S

    2016-01-01

    This study presents the effect of all-trans retinoic acid (ATRA) on cell growth and respiratory chain complex I in human keratinocyte cultures. Keratinocyte treatment results in increased level of GRIM-19 and other subunits of complex I, in particular of their carbonylated forms, associated with inhibition of its enzymatic activity. The results show that in keratinocytes ATRA-promoted phosphatase activity controls the proteostasis and activity of complex I. PMID:27358125

  16. 40 CFR 721.8673 - [(Disubstituted phenyl)]azo dihydro hydroxy alkyl oxo alkyl-substituted-pyridines (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false azo dihydro hydroxy alkyl oxo alkyl... Significant New Uses for Specific Chemical Substances § 721.8673 azo dihydro hydroxy alkyl oxo alkyl...) The chemical substances identified generically as azo dihydro hydroxy alkyl oxo...

  17. 40 CFR 721.8673 - [(Disubstituted phenyl)]azo dihydro hydroxy alkyl oxo alkyl-substituted-pyridines (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false azo dihydro hydroxy alkyl oxo alkyl... Significant New Uses for Specific Chemical Substances § 721.8673 azo dihydro hydroxy alkyl oxo alkyl...) The chemical substances identified generically as azo dihydro hydroxy alkyl oxo...

  18. 40 CFR 721.8673 - [(Disubstituted phenyl)]azo dihydro hydroxy alkyl oxo alkyl-substituted-pyridines (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false azo dihydro hydroxy alkyl oxo alkyl... Significant New Uses for Specific Chemical Substances § 721.8673 azo dihydro hydroxy alkyl oxo alkyl...) The chemical substances identified generically as azo dihydro hydroxy alkyl oxo...

  19. Brain white matter development is associated with a human-specific haplotype increasing the synthesis of long chain fatty acids.

    PubMed

    Peters, Bart D; Voineskos, Aristotle N; Szeszko, Philip R; Lett, Tristram A; DeRosse, Pamela; Guha, Saurav; Karlsgodt, Katherine H; Ikuta, Toshikazu; Felsky, Daniel; John, Majnu; Rotenberg, David J; Kennedy, James L; Lencz, Todd; Malhotra, Anil K

    2014-04-30

    The genetic and molecular pathways driving human brain white matter (WM) development are only beginning to be discovered. Long chain polyunsaturated fatty acids (LC-PUFAs) have been implicated in myelination in animal models and humans. The biosynthesis of LC-PUFAs is regulated by the fatty acid desaturase (FADS) genes, of which a human-specific haplotype is strongly associated with ω-3 and ω-6 LC-PUFA concentrations in blood. To investigate the relationship between LC-PUFA synthesis and human brain WM development, we examined whether this FADS haplotype is associated with age-related WM differences across the life span in healthy individuals 9-86 years of age (n = 207). Diffusion tensor imaging was performed to measure fractional anisotropy (FA), a putative measure of myelination, of the cerebral WM tracts. FADS haplotype status was determined with a single nucleotide polymorphism (rs174583) that tags this haplotype. Overall, normal age-related WM differences were observed, including higher FA values in early adulthood compared with childhood, followed by lower FA values across older age ranges. However, individuals homozygous for the minor allele (associated with lower LC-PUFA concentrations) did not display these normal age-related WM differences (significant age × genotype interactions, p(corrected) < 0.05). These findings suggest that LC-PUFAs are involved in human brain WM development from childhood into adulthood. This haplotype and LC-PUFAs may play a role in myelin-related disorders of neurodevelopmental origin. PMID:24790207

  20. 13C NMR relaxation in neutral and charged tetra- n-alkyl compounds

    NASA Astrophysics Data System (ADS)

    Bordes, B.; Coletta, F.; Ferrarini, A.; Gottardi, F.; Nordio, P. L.

    1998-05-01

    NMR T1 relaxation times have been measured for 13C nuclei in the alkyl chains of symmetric tetra- n-alkylstannanes dissolved in CDCl 3. The results are interpreted in terms of conformational transitions occurring in the aliphatic chains superimposed to rotational diffusion of the whole molecule. A comparison with analogous tetra- n-alkylammonium salts is performed. Differences are ascribed to changes in the overall rotational diffusion deriving from effects of charge upon formation of ion-pairs and larger aggregates.

  1. Supramolecular aggregation of regioregular poly(4-alkyl-2,6-quinoline)s.

    PubMed

    Chen, S H; Zhu, Yan; Jenekhe, Samson A; Su, A C; Chen, S A

    2007-11-01

    Phase behavior and morphological features of regioregular, n-type semiconducting poly(4-alkyl-2,6-quinoline)s were examined in detail via a combination of thermal, microscopic, and diffraction methods. Two members (P4OQ and P4DQ, with n-octyl and n-decyl substitutions, respectively) in this series were selected as representatives. Results indicate the dominance of lamellar mesophase throughout the experimentally accessed temperature range (from ambient to above 300 degrees C), with lamellar spacing well-correlated with side-chain length and temperature. Optical textures observed via polarized light microscopy reveal clear domain-wall features in P4OQ but more solid-like characteristics for P4DQ; improved lamellar order was also observed for P4DQ as compared to P4OQ. These signify stronger tendency toward supramolecular self-assembly with increasing side-chain length. A model of molecular arrangement in the lamellar mesophase in which the free volume is identified as the gap between tips of extended (and interdigitated) side chains and the backbone of the neighboring chain is proposed to account for the observed variation of layer spacing with side-chain length and temperature. The presence of nanodomains (similar to those previously reported for p-type conjugated polymers) is also identified in the present n-type series, implying general existence of this inherent morphological heterogeneity in semiconducting hairy-rod polymers. This means that molecular aggregation is determined solely by ground-state intermolecular forces; differences in carrier transport characteristics are irrelevant during morphological development. Origins of these nanodomains are discussed in terms of backbone folding (via inherent chemical defects or elastic bending) as well as fringed-micelle aggregates. PMID:17929859

  2. Increasing the sensitivity of NMR diffusion measurements by paramagnetic longitudinal relaxation enhancement, with application to ribosome–nascent chain complexes

    PubMed Central

    Cassaignau, Anaïs M. E.; Cabrita, Lisa D.

    2016-01-01

    The translational diffusion of macromolecules can be examined non-invasively by stimulated echo (STE) NMR experiments to accurately determine their molecular sizes. These measurements can be important probes of intermolecular interactions and protein folding and unfolding, and are crucial in monitoring the integrity of large macromolecular assemblies such as ribosome–nascent chain complexes (RNCs). However, NMR studies of these complexes can be severely constrained by their slow tumbling, low solubility (with maximum concentrations of up to 10 μM), and short lifetimes resulting in weak signal, and therefore continuing improvements in experimental sensitivity are essential. Here we explore the use of the paramagnetic longitudinal relaxation enhancement (PLRE) agent NiDO2A on the sensitivity of 15N XSTE and SORDID heteronuclear STE experiments, which can be used to monitor the integrity of these unstable complexes. We exploit the dependence of the PLRE effect on the gyromagnetic ratio and electronic relaxation time to accelerate recovery of 1H magnetization without adversely affecting storage on Nz during diffusion delays or introducing significant transverse relaxation line broadening. By applying the longitudinal relaxation-optimized SORDID pulse sequence together with NiDO2A to 70S Escherichia coli ribosomes and RNCs, NMR diffusion sensitivity enhancements of up to 4.5-fold relative to XSTE are achieved, alongside ~1.9-fold improvements in two-dimensional NMR sensitivity, without compromising the sample integrity. We anticipate these results will significantly advance the use of NMR to probe dynamic regions of ribosomes and other large, unstable macromolecular assemblies. PMID:26253948

  3. Leukemia after therapy with alkylating agents for childhood cancer

    SciTech Connect

    Tucker, M.A.; Meadows, A.T.; Boice, J.D. Jr.; Stovall, M.; Oberlin, O.; Stone, B.J.; Birch, J.; Voute, P.A.; Hoover, R.N.; Fraumeni, J.F. Jr.

    1987-03-01

    The risk of leukemia was evaluated in 9,170 2-or-more-year survivors of childhood cancer in the 13 institutions of the Late Effects Study Group. Secondary leukemia occurred in 22 nonreferred individuals compared to 1.52 expected, based on general population rates (relative risk (RR) = 14; 95% confidence interval (CI), 9-22). The influence of therapy for the first cancer on subsequent leukemia risk was determined by a case-control study conducted on 25 cases and 90 matched controls. Treatment with alkylating agents was associated with a significantly elevated risk of leukemia (RR = 4.8; 95% CI, 1.2-18.9). A strong dose-response relationship was also observed between leukemia risk and total dose of alkylating agents, estimated by an alkylator score. The RR of leukemia reached 23 in the highest dose category. Radiation therapy, however, did not increase risk. Although doxorubicin was also identified as a possible risk factor, the excess risk of leukemia following treatment for childhood cancer appears almost entirely due to alkylating agents.

  4. Occupational asthma due to alkyl cyanoacrylate

    SciTech Connect

    Nakazawa, T. )

    1990-08-01

    A case of bronchial asthma induced by occupational exposure to alkyl cyanoacrylate, an adhesive, occurred in an assembly operation. Provocative exposure testing induced immediate and delayed asthmatic responses. Alkyl cyanoacrylate seemed to act as an allergen or as an irritant, resulting in the development of asthma.

  5. Stabilized dialkyl aluminum complexes as alkylating agents

    SciTech Connect

    Blum, J.; Baidossi, W.; Rosenfeld, A.

    1995-12-31

    Although trialkylaluminum derivatives are widely used as Ziegler-Natta polymerization co-catalysts, their application as routine alkylating agents is limited owing to their pyrophoric nature. The authors have now found that substitution of one of the alkyl moieties by a chelating group reduces the sensitivity of the organoaluminum compounds to air, and enables one to utilize them under normal laboratory conditions.

  6. Synthesis and characterization of side-chain cholesterol derivatives based on double bond

    NASA Astrophysics Data System (ADS)

    Yu, Yun-Long; Bai, Jun-Wei; Zhang, Jun-Hua

    2012-07-01

    After steps of esterification, epoxidation and ring-opening, a series of novel monomers of 5-hydroxyl-6-methacryloyloxy-3-alkylate, CnCOOCh (n = 1, 2, 3, 4, 5) were synthesized. After that, the corresponding polymers (PnCOOCh, n = 1, 2, 3, 4, 5) were obtained by free radical polymerization. The molecular structure, composition and thermal behaviors of monomers and polymers were confirmed by 1H NMR, FTIR, single crystal diffractometer, GPC, DSC and TGA. The results indicate that although their molecular weights are not high, all the polymers have high glass transition (Tg) and degradation temperature. In addition, Tg gradually decreases with increasing of alkyl chain lengths, and the degradation temperature increases with the increase of carbon number.

  7. Alkylating reactivity and herbicidal activity of chloroacetamides.

    PubMed

    Jablonkai, Istvan

    2003-04-01

    The relationship between S- and N-alkylating reactivity and herbicidal activity within a series of chloroacetamides, including several commercial herbicides and newly synthesised analogues was studied. The S-alkylating reactivity of selected chloroacetamides, as well as those of atrazine and chlorfenprop-methyl, was determined by in vitro GSH conjugation at a ratio of GSH to alkylating agent of 25:1. A spectrophotometric reaction using 4-(4-nitrobenzyl)pyridine was used to characterise the N-alkylating reactivity of the chemicals. Our results indicate that a reduced level of N-alkylating reactivity correlates with an improved herbicidal efficacy at a practical rate. However, the phytoxicity of the molecules is not simply dependent on chemical reactivities, but strictly related to the molecular structure, indicating that lipophilicity, uptake, mobility and induction of detoxifying enzymes may also be decisive factors in the mode of action. PMID:12701706

  8. C-Alkylation by Hydrogen Autotransfer Reactions.

    PubMed

    Obora, Yasushi

    2016-04-01

    The development of practical, efficient, and atom-economical methods for the formation of carbon-carbon bonds remains a topic of considerable interest in current synthetic organic chemistry. In this review, we have summarized selected topics from the recent literature with particular emphasis on C-alkylation processes involving hydrogen transfer using alcohols as alkylation reagents. This review includes selected highlights concerning recent progress towards the modification of catalytic systems for the α-alkylation of ketones, nitriles, and esters. Furthermore, we have devoted a significant portion of this review to the methylation of ketones, alcohols, and indoles using methanol. Lastly, we have also documented recent advances in β-alkylation methods involving the dimerization of alcohols (Guerbet reaction), as well as new developments in C-alkylation methods based on sp (3) C-H activation. PMID:27573136

  9. Chronic administration of branched-chain amino acids impairs spatial memory and increases brain-derived neurotrophic factor in a rat model.

    PubMed

    Scaini, Giselli; Comim, Clarissa M; Oliveira, Giovanna M T; Pasquali, Matheus A B; Quevedo, João; Gelain, Daniel P; Moreira, José Cláudio F; Schuck, Patrícia F; Ferreira, Gustavo C; Bogo, Maurício R; Streck, Emilio L

    2013-09-01

    Maple syrup urine disease (MSUD) is a neurometabolic disorder that leads to the accumulation of branched-chain amino acids (BCAAs) and their α-keto branched-chain by-products. Because the neurotoxic mechanisms of MSUD are poorly understood, this study aimed to evaluate the effects of chronic administration of a BCAA pool (leucine, isoleucine and valine). This study examined the effects of BCAA administration on spatial memory and the levels of brain-derived neurotrophic factor (BNDF). We examined both pro-BDNF and bdnf mRNA expression levels after administration of BCAAs. Furthermore, this study examined whether antioxidant treatment prevented the alterations induced by BCAA administration. Our results demonstrated an increase in BDNF in the hippocampus and cerebral cortex, accompanied by memory impairment in spatial memory tasks. Additionally, chronic administration of BCAAs did not induce a detectable change in pro-BDNF levels. Treatment with N-acetylcysteine and deferoxamine prevented both the memory deficit and the increase in the BDNF levels induced by BCAA administration. In conclusion, these results suggest that when the brain is chronically exposed to high concentrations of BCAA (at millimolar concentrations) an increase in BDNF levels occurs. This increase in BDNF may be related to the impairment of spatial memory. In addition, we demonstrated that antioxidant treatment prevented the negative consequences related to BCAA administration, suggesting that oxidative stress might be involved in the pathophysiological mechanism(s) underlying the brain damage observed in MSUD. PMID:23109061

  10. Biochemical and gene expression effects of 1-alkyl-3-methylimidazolium tetrafluoroborate on Vibrio qinghaiensis sp.-Q67.

    PubMed

    Yu, ZhenYang; Zhang, Jing; Liu, ShuShen

    2015-12-30

    Applications of 1-alkyl-3-methylimidazolium salts ([amim]X) in pharmaceuticals call for studies on the biological effects. Previously, [amim]Cl and [amim]Br caused time-dependent stimulatory effects on Vibrio qinghaiensis sp.-Q67 (Q67). Further studies are still needed to answer the question whether [amim]X with other anions have similar effects, and to explain such stimulatory effects. Here, effects of four [amim]BF4 with different alkyl side chains on Q67 were investigated. At the apical level, they inhibited luminescence at high concentrations and the toxicities decreased with time increasing from 0.25 to 12h. Meanwhile, they stimulated luminescence at low concentrations, and the stimulations increased over time. The maximum stimulations followed an order of [emim]BF4>[bmim]BF4>[hmim]BF4>[omim]BF4. Compared with [emim]BF4, imidazole caused lower stimulations, while NaBF4 caused significantly higher ones. Overview on effects of [amim]BF4, imidazole and NaBF4 indicated significant anionic contributions. At biochemical and molecular levels, favin mono-nucleotide (FMN) and nicotinamide adenine dinucleotide (NADH) increased over time, and expressions of luxA and luxB (encoding luciferase that catalyzes FMN:NADH reaction) in Q67 showed up-regulations, suggesting an overall enhancement of the bioactivities. Moreover, superoxide dismutase and catalase showed inductions with up-regulations on their encoding genes, indicating improved antioxidant responses. PMID:26225488

  11. Effect of increase in orientational order of lipid chains and head group spacing on non steroidal anti-inflammatory drug induced membrane fusion.

    PubMed

    Roy, Sutapa Mondal; Bansode, Amol S; Sarkar, Munna

    2010-12-21

    Membrane fusion is a key event in many biological processes. The fusion process, both in vivo and in vitro, is induced by different agents which include mainly proteins and peptides. For protein- and peptide-mediated membrane fusion, conformational reorganization serves as a driving force. Small drug molecules do not share this advantage; hence, drug induced membrane fusion occurring in absence of any other fusogenic agent and at physiologically relevant concentration of the drugs is a very rare event. To date, only three drugs, namely, meloxicam (Mx), piroxicam (Px), and tenoxicam (Tx), belonging to the oxicam group of non steroidal anti-inflammatory drugs (NSAIDs), have been shown by us to induce fusion at very low drug to lipid ratio without the aid of any other fusogenic agent. In our continued effort to understand the interplay of different physical and chemical parameters of both the participating drugs and the membrane on the mechanism of this drug induced membrane fusion, we present here the effect of increase in orientational order of the lipid chains and increase in head group spacing. This is achieved by studying the effect of low concentration cholesterol (<10 mol %) at temperatures above the chain-melting transition. Low concentration cholesterol (<10 mol %), above the gel to fluid transition temperature, is mainly known to increase orientational order of the lipid chains and increase head group spacing. To isolate the effect of these parameters, small unilameller vesicles (SUVs) formed by dimyristoylphosphatidylcholine (DMPC) with an average diameter of 50-60 nm were used as simple model membranes. Fluorescence assays were used to probe the time dependence of lipid mixing, content mixing, and leakage and also used to determine the partitioning of the drugs in the membrane bilayer. Differential scanning calorimetry (DSC) was used to study the effect of drugs in the presence of cholesterol on the chain-melting temperature which reflects the fluidization

  12. Increasing the persistence of a heterogeneous behavior chain: Studies of extinction in a rat model of search behavior of working dogs.

    PubMed

    Thrailkill, Eric A; Kacelnik, Alex; Porritt, Fay; Bouton, Mark E

    2016-08-01

    Dogs trained to search for contraband perform a chain of behavior in which they first search for a target and then make a separate response that indicates to the trainer that they have found one. The dogs often conduct multiple searches without encountering a target and receiving the reinforcer (i.e., no contraband is present). Understanding extinction (i.e., the decline in work rate when reinforcers are no longer encountered) may assist in training dogs to work in conditions where targets are rare. We therefore trained rats on a search-target behavior chain modeled on the search behavior of working dogs. A discriminative stimulus signaled that a search response (e.g., chain pull) led to a second stimulus that set the occasion for a target response (e.g., lever press) that was reinforced by a food pellet. In Experiment 1 training with longer search durations and intermittent (partial) reinforcement of searching (i.e. some trials had no target present) both led to more persistent search responding in extinction. The loss of search behavior in extinction was primarily dependent on the number of non-reinforced searches rather than time searching without reinforcement. In Experiments 2 and 3, delivery of non-contingent reinforcers during extinction increased search persistence provided they had also been presented during training. Thus, results with rats suggest that the persistence of working dog performance (or chained behavior generally) may be improved by training with partial reinforcement of searching and non-contingent reinforcement during both training and work (extinction). PMID:27306694

  13. Increased Stability and DNA Site Discrimination of Single Chain Variants of the Dimeric beta-Barrel DNA Binding Domain of the Human Papillomavirus E2 Transcriptional Regulator

    SciTech Connect

    Dellarole,M.; Sanchez, I.; Freire, E.; de Prat-Gay, G.

    2007-01-01

    Human papillomavirus infects millions of people worldwide and is a causal agent of cervical cancer in women. The HPV E2 protein controls the expression of all viral genes through binding of its dimeric C-terminal domain (E2C) to its target DNA site. We engineered monomeric versions of the HPV16 E2C, in order to probe the link of the dimeric {beta}-barrel fold to stability, dimerization, and DNA binding. Two single-chain variants, with 6 and 12 residue linkers (scE2C-6 and scE2C-12), were purified and characterized. Spectroscopy and crystallography show that the native structure is unperturbed in scE2C-12. The single chain variants are stabilized with respect to E2C, with effective concentrations of 0.6 to 6 mM. The early folding events of the E2C dimer and scE2C-12 are very similar and include formation of a compact species in the submillisecond time scale and a non-native monomeric intermediate with a half-life of 25 ms. However, monomerization changes the unfolding mechanism of the linked species from two-state to three-state, with a high-energy intermediate. Binding to the specific target site is up to 5-fold tighter in the single chain variants. Nonspecific DNA binding is up to 7-fold weaker in the single chain variants, leading to an overall 10-fold increased site discrimination capacity, the largest described so far for linked DNA binding domains. Titration calorimetric binding analysis, however, shows almost identical behavior for dimer and single-chain species, suggesting very subtle changes behind the increased specificity. Global analysis of the mechanisms probed suggests that the dynamics of the E2C domain, rather than the structure, are responsible for the differential properties. Thus, the plastic and dimeric nature of the domain did not evolve for a maximum affinity, specificity, and stability of the quaternary structure, likely because of regulatory reasons and for roles other than DNA binding played by partly folded dimeric or monomeric conformers.

  14. Saturation properties of 1-alkyl-3-methylimidazolium based ionic liquids.

    PubMed

    Rane, Kaustubh S; Errington, Jeffrey R

    2014-07-24

    We study the liquid-vapor saturation properties of room temperature ionic liquids (RTILs) belonging to the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) using Monte Carlo simulation. We examine the effect of temperature and cation alkyl chain length n on the saturated densities, vapor pressures, and enthalpies of vaporization. These properties are explicitly calculated for temperatures spanning from 280 to 1000 K for RTILs with n = 2, 4, 6, 8, 10, and 12. We also explore how the identity of the anion influences saturation properties. Specifically, we compare results for [C(4)mim][NTf2] with those for 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]). Simulations are completed with a recently developed realistic united-atom force field. A combination of direct grand canonical and isothermal-isobaric temperature expanded ensemble simulations are used to construct phase diagrams. Our results are compared with experimental data and Gibbs ensemble simulation data. Overall, we find good agreement between our results and those measured experimentally. We find that the vapor pressures and enthalpies of vaporization show a strong dependence on the size of the alkyl chain at low temperatures, whereas no particular trend is observed at high temperatures. Finally, we also discuss the effect of temperature on liquid phase nanodomains observed in RTILs with large hydrophobic groups. We do not observe a drastic change in liquid phase structure upon variation of the temperature, which suggests there is not a sharp phase transition between a nanostructured and homogeneous liquid, as has been suggested in earlier studies. PMID:24986360

  15. Single particle dynamics in ionic liquids of 1-alkyl-3-methylimidazolium cations.

    PubMed

    Urahata, Sérgio M; Ribeiro, Mauro C C

    2005-01-01

    Ionic dynamics in room temperature molten salts (ionic liquids) containing 1-alkyl-3-methylimidazolium cations is investigated by molecular-dynamics simulations. Calculations were performed with united atom models, which were used in a previous detailed study of the equilibrium structure of ionic liquids [S. M. Urahata and M. C. C. Ribeiro, J. Chem. Phys. 120, 1855 (2004)]. The models were used in a systematic study of the dependency of several single particle time correlation functions on anion size (F-, Cl-, Br-, and PF6-) and alkyl chain length (1-methyl-, 1-ethyl-, 1-butyl-, and 1-octyl-). Despite of large mass and size of imidazolium cations, they exhibit larger mean-square displacement than anions. A further detailed picture of ionic motions is obtained by using appropriate projections of displacements along the plane or perpendicular to the plane of the imidazolium ring. A clear anisotropy in ionic displacement is revealed, the motion on the ring plane and almost perpendicular to the 1-alkyl chain being the less hindered one. Similar projections were performed on velocity correlation functions, whose spectra were used to relate short time ionic rattling with the corresponding long time diffusive regime. Time correlation functions of cation reorientation and dihedral angles of the alkyl chains are discussed, the latter decaying much faster than the former. A comparative physical picture of time scales for distinct dynamical processes in ionic liquids is provided. PMID:15638602

  16. Single particle dynamics in ionic liquids of 1-alkyl-3-methylimidazolium cations

    NASA Astrophysics Data System (ADS)

    Urahata, Sérgio M.; Ribeiro, Mauro C. C.

    2005-01-01

    Ionic dynamics in room temperature molten salts (ionic liquids) containing 1-alkyl-3-methylimidazolium cations is investigated by molecular-dynamics simulations. Calculations were performed with united atom models, which were used in a previous detailed study of the equilibrium structure of ionic liquids [S. M. Urahata and M. C. C. Ribeiro, J. Chem. Phys. 120, 1855 (2004)]. The models were used in a systematic study of the dependency of several single particle time correlation functions on anion size (F-, Cl-, Br-, and PF6-) and alkyl chain length (1-methyl-, 1-ethyl-, 1-butyl-, and 1-octyl-). Despite of large mass and size of imidazolium cations, they exhibit larger mean-square displacement than anions. A further detailed picture of ionic motions is obtained by using appropriate projections of displacements along the plane or perpendicular to the plane of the imidazolium ring. A clear anisotropy in ionic displacement is revealed, the motion on the ring plane and almost perpendicular to the 1-alkyl chain being the less hindered one. Similar projections were performed on velocity correlation functions, whose spectra were used to relate short time ionic rattling with the corresponding long time diffusive regime. Time correlation functions of cation reorientation and dihedral angles of the alkyl chains are discussed, the latter decaying much faster than the former. A comparative physical picture of time scales for distinct dynamical processes in ionic liquids is provided.

  17. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1993-01-05

    Aromatic compounds are alkylated in a combination reactor/distillation column comprising a vessel suitable for operating between 70 C and 500 C and from 0.5 to 20 atmospheres pressure; an inert distillation packing in the lower one-third of said vessel; solid acidic catalytic material such as zeolites or an acidic cation exchange resin supported in the middle one-third of said vessel; and inert distillation packing in the upper one-third of said vessel. A benzene inlet is located near the upper end of the vessel; an olefin inlet is juxtaposed with said solid acidic catalytic material; a bottoms outlet is positioned near the bottom of said vessel for removing said cumene and ethyl benzene; and an overhead outlet is placed at the top of said vessel for removing any unreacted benzene and olefin.

  18. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1993-09-07

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a molecular sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene to about the mid point of the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 figures.

  19. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1994-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  20. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1994-06-14

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a molecular sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 fig.

  1. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.

    1989-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  2. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1993-01-01

    Aromatic compounds are alkylated in a combination reactor/distillation column comprising a vessel suitable for operating between 70.degree. C. and 500.degree. C. and from 0.5 to 20 atmospheres pressure; an inert distillation packing in the lower one-third of said vessel; solid acidic catalytic material such as zeolites or an acidic cation exchange resin supported in the middle one-third of said vessel; and inert distillation packing in the upper one-third of said vessel. A benzene inlet is located near the upper end of the vessel; an olefin inlet is juxtaposed with said solid acidic catalytic material; a bottoms outlet is positioned near the bottom of said vessel for removing said cumene and ethyl benzene; and an overhead outlet is placed at the top of said vessel for removing any unreacted benzene and olefin.

  3. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1993-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene to about the mid point of the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  4. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.

    1989-07-18

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 fig.

  5. Partitioning solvophobic and dispersion forces in alkyl and perfluoroalkyl cohesion.

    PubMed

    Adam, Catherine; Yang, Lixu; Cockroft, Scott L

    2015-01-19

    Fluorocarbons often have distinct miscibility properties compared to their nonfluorinated analogues. These differences may be attributed to van der Waals dispersion forces or solvophobic effects, but their contributions are notoriously difficult to separate in molecular recognition processes. Here, molecular torsion balances were used to compare cohesive alkyl and perfluoroalkyl interactions in a range of solvents. A simple linear regression enabled the energetic partitioning of solvophobic and van der Waals forces in the self-association of apolar chains. The contributions of dispersion interactions in apolar cohesion were found to be strongly attenuated in solution compared to the gas phase, but still play a major role in fluorous and organic solvents. In contrast, solvophobic effects were found to be dominant in driving the association of apolar chains in aqueous solution. The results are expected to assist the computational modelling of van der Waals forces in solution. PMID:25413159

  6. Tetrahydrocannabinol induces brain mitochondrial respiratory chain dysfunction and increases oxidative stress: a potential mechanism involved in cannabis-related stroke.

    PubMed

    Wolff, Valérie; Schlagowski, Anna-Isabel; Rouyer, Olivier; Charles, Anne-Laure; Singh, François; Auger, Cyril; Schini-Kerth, Valérie; Marescaux, Christian; Raul, Jean-Sébastien; Zoll, Joffrey; Geny, Bernard

    2015-01-01

    Cannabis has potential therapeutic use but tetrahydrocannabinol (THC), its main psychoactive component, appears as a risk factor for ischemic stroke in young adults. We therefore evaluate the effects of THC on brain mitochondrial function and oxidative stress, key factors involved in stroke. Maximal oxidative capacities V max (complexes I, III, and IV activities), V succ (complexes II, III, and IV activities), V tmpd (complex IV activity), together with mitochondrial coupling (V max/V 0), were determined in control conditions and after exposure to THC in isolated mitochondria extracted from rat brain, using differential centrifugations. Oxidative stress was also assessed through hydrogen peroxide (H2O2) production, measured with Amplex Red. THC significantly decreased V max (-71%; P < 0.0001), V succ (-65%; P < 0.0001), and V tmpd (-3.5%; P < 0.001). Mitochondrial coupling (V max/V 0) was also significantly decreased after THC exposure (1.8±0.2 versus 6.3±0.7; P < 0.001). Furthermore, THC significantly enhanced H2O2 production by cerebral mitochondria (+171%; P < 0.05) and mitochondrial free radical leak was increased from 0.01±0.01 to 0.10±0.01% (P < 0.001). Thus, THC increases oxidative stress and induces cerebral mitochondrial dysfunction. This mechanism may be involved in young cannabis users who develop ischemic stroke since THC might increase patient's vulnerability to stroke. PMID:25654095

  7. Fast rotational motion of water molecules increases ordering of hydrophobes in solutions and may cause hydrophobic chains to collapse

    NASA Astrophysics Data System (ADS)

    Mohorič, Tomaž; Bren, Urban; Vlachy, Vojko

    2015-12-01

    Using the molecular dynamics simulations with separate thermostats for translational and rotational degrees of freedom, we investigate the effects of water's rotational motion on the interaction among Lennard-Jones solutes. The situation with rotational temperature higher than the translational one (TR > TT) is mimicking the effects of microwaves on model solutions. Molecular dynamics simulations suggest that solutions of Lennard-Jones solutes become increasingly more structured with the rise in TR, while keeping the TT constant. This is evidenced by an increase of the first and the second peak of the solute-solute radial distribution function. In addition, the first peak moves toward slightly larger distances; the effect seems to be caused by the destabilization of water molecules in the first hydration shell around hydrophobic solutes. More evidence of strong effects of the rotationally excited water is provided by the simulations of short hydrophobic polymers, which upon an increase in TR assume more compact conformations. In these simulations, we see the re-distribution of water molecules, which escape from hydrophobic "pockets" to better solvate the solvent exposed monomers.

  8. Fast rotational motion of water molecules increases ordering of hydrophobes in solutions and may cause hydrophobic chains to collapse.

    PubMed

    Mohorič, Tomaž; Bren, Urban; Vlachy, Vojko

    2015-12-28

    Using the molecular dynamics simulations with separate thermostats for translational and rotational degrees of freedom, we investigate the effects of water's rotational motion on the interaction among Lennard-Jones solutes. The situation with rotational temperature higher than the translational one (TR > TT) is mimicking the effects of microwaves on model solutions. Molecular dynamics simulations suggest that solutions of Lennard-Jones solutes become increasingly more structured with the rise in TR, while keeping the TT constant. This is evidenced by an increase of the first and the second peak of the solute-solute radial distribution function. In addition, the first peak moves toward slightly larger distances; the effect seems to be caused by the destabilization of water molecules in the first hydration shell around hydrophobic solutes. More evidence of strong effects of the rotationally excited water is provided by the simulations of short hydrophobic polymers, which upon an increase in TR assume more compact conformations. In these simulations, we see the re-distribution of water molecules, which escape from hydrophobic "pockets" to better solvate the solvent exposed monomers. PMID:26723695

  9. Tetrahydrocannabinol Induces Brain Mitochondrial Respiratory Chain Dysfunction and Increases Oxidative Stress: A Potential Mechanism Involved in Cannabis-Related Stroke

    PubMed Central

    Wolff, Valérie; Schlagowski, Anna-Isabel; Rouyer, Olivier; Charles, Anne-Laure; Singh, François; Auger, Cyril; Schini-Kerth, Valérie; Marescaux, Christian; Raul, Jean-Sébastien; Zoll, Joffrey; Geny, Bernard

    2015-01-01

    Cannabis has potential therapeutic use but tetrahydrocannabinol (THC), its main psychoactive component, appears as a risk factor for ischemic stroke in young adults. We therefore evaluate the effects of THC on brain mitochondrial function and oxidative stress, key factors involved in stroke. Maximal oxidative capacities Vmax (complexes I, III, and IV activities), Vsucc (complexes II, III, and IV activities), Vtmpd (complex IV activity), together with mitochondrial coupling (Vmax/V0), were determined in control conditions and after exposure to THC in isolated mitochondria extracted from rat brain, using differential centrifugations. Oxidative stress was also assessed through hydrogen peroxide (H2O2) production, measured with Amplex Red. THC significantly decreased Vmax (−71%; P < 0.0001), Vsucc (−65%; P < 0.0001), and Vtmpd (−3.5%; P < 0.001). Mitochondrial coupling (Vmax/V0) was also significantly decreased after THC exposure (1.8±0.2 versus 6.3±0.7; P < 0.001). Furthermore, THC significantly enhanced H2O2 production by cerebral mitochondria (+171%; P < 0.05) and mitochondrial free radical leak was increased from 0.01±0.01 to 0.10±0.01% (P < 0.001). Thus, THC increases oxidative stress and induces cerebral mitochondrial dysfunction. This mechanism may be involved in young cannabis users who develop ischemic stroke since THC might increase patient's vulnerability to stroke. PMID:25654095

  10. Tyrosine-selective protein alkylation using pi-allylpalladium complexes.

    PubMed

    Tilley, S David; Francis, Matthew B

    2006-02-01

    A new protein modification reaction has been developed based on a palladium-catalyzed allylic alkylation of tyrosine residues. This technique employs electrophilic pi-allyl intermediates derived from allylic acetate and carbamate precursors and can be used to modify proteins in aqueous solution at room temperature. To facilitate the detection of modified proteins using SDS-PAGE analysis, a fluorescent allyl acetate was synthesized and coupled to chymotrypsinogen A and bacteriophage MS2. The tyrosine selectivity of the reaction was confirmed through trypsin digest analysis. The utility of the reaction was demonstrated by using taurine-derived carbamates as water solubilizing groups that are cleaved upon protein functionalization. This solubility switching technique was used to install hydrophobic farnesyl and C(17) chains on chymotrypsinogen A in water using little or no cosolvent. Following this, the C(17) alkylated proteins were found to associate with lipid vesicles. In addition to providing a new protein modification strategy targeting an under-utilized amino acid side chain, this method provides convenient access to synthetic lipoproteins. PMID:16433516

  11. Metformin-induced inhibition of the mitochondrial respiratory chain increases FGF21 expression via ATF4 activation

    SciTech Connect

    Kim, Kook Hwan; Jeong, Yeon Taek; Kim, Seong Hun; Jung, Hye Seung; Park, Kyong Soo; Lee, Hae-Youn; Lee, Myung-Shik

    2013-10-11

    Highlights: •Metformin induces FGF21 expression in an AMPK independent manner. •Metformin enhances FGF21 expression by inhibiting mitochondrial complex I activity. •The PERK-eIF2α-ATF4 axis is required for metformin-induced FGF21 expression. •Metformin activates the ATF4-FGF21 axis in the liver of mouse. •Metformin increases serum FGF21 level in diabetic human subjects. -- Abstract: Fibroblast growth factor 21 (FGF21) is an endocrine hormone that exhibits anti-obesity and anti-diabetes effects. Because metformin is widely used as a glucose-lowering agent in patients with type 2 diabetes (T2D), we investigated whether metformin modulates FGF21 expression in cell lines, and in mice or human subjects. We found that metformin increased the expression and release of FGF21 in a diverse set of cell types, including rat hepatoma FaO, primary mouse hepatocytes, and mouse embryonic fibroblasts (MEFs). Intriguingly, AMP-activated protein kinase (AMPK) was dispensable for the induction of FGF21 by metformin. Mammalian target of rapamycin complex 1 (mTORC1) and peroxisome proliferator-activated receptor α (PPARα), which are additional targets of metformin, were not involved in metformin-induced FGF21 expression. Importantly, inhibition of mitochondrial complex I activity by metformin resulted in FGF21 induction through PKR-like ER kinase (PERK)-eukaryotic translation factor 2α (eIF2α)-activating transcription factor 4 (ATF4). We showed that metformin activated ATF4 and increased FGF21 expression in the livers of mice, which led to increased serum levels of FGF21. We also found that serum FGF21 level was increased in human subjects with T2D after metformin therapy for 6 months. In conclusion, our results indicate that metformin induced expression of FGF21 through an ATF4-dependent mechanism by inhibiting mitochondrial respiration independently of AMPK. Therefore, FGF21 induction by metformin might explain a portion of the beneficial metabolic effects of metformin.

  12. Postgraduate Symposium: Long-chain n-3 PUFA: intakes in the UK and the potential of a chicken meat prototype to increase them.

    PubMed

    Gibbs, Rachael A; Rymer, Caroline; Givens, D Ian

    2010-02-01

    With the wide acceptance of the long-chain (LC) n-3 PUFA EPA and DHA as important nutrients playing a role in the amelioration of certain diseases, efforts to understand factors affecting intakes of these fatty acids along with potential strategies to increase them are vital. Widespread aversion to oil-rich fish, the richest natural source of EPA and DHA, highlights both the highly suboptimal current intakes in males and females across all age-groups and the critical need for an alternative supply of EPA and DHA. Poultry meat is a popular and versatile food eaten in large quantities relative to other meats and is open to increased LC n-3 PUFA content through manipulation of the chicken's diet to modify fatty acid deposition and therefore lipid composition of the edible tissues. It is therefore seen as a favourable prototype food for increasing human dietary supply of LC n-3 PUFA. Enrichment of chicken breast and leg tissue is well established using fish oil or fishmeal, but concerns about sustainability have led to recent consideration of algal biomass as an alternative source of LC n-3 PUFA. Further advances have also been made in the quality of the resulting meat, including achieving acceptable flavour and storage properties as well as understanding the impact of cooking on the retention of fatty acids. Based on these considerations it may be concluded that EPA- and DHA-enriched poultry meat has a very positive potential future in the food chain. PMID:19954567

  13. Increasing the Thermal Conductivity of Graphene-Polyamide-6,6 Nanocomposites by Surface-Grafted Polymer Chains: Calculation with Molecular Dynamics and Effective-Medium Approximation.

    PubMed

    Gao, Yangyang; Müller-Plathe, Florian

    2016-02-25

    By employing reverse nonequilibrium molecular dynamics simulations in a full atomistic resolution, the effect of surface-grafted chains on the thermal conductivity of graphene-polyamide-6.6 (PA) nanocomposites has been investigated. The interfacial thermal conductivity perpendicular to the graphene plane is proportional to the grafting density, while it first increases and then saturates with the grafting length. Meanwhile, the intrinsic in-plane thermal conductivity of graphene drops sharply as the grafting density increases. The maximum overall thermal conductivity of nanocomposites appears at an intermediate grafting density because of these two competing effects. The thermal conductivity of the composite parallel to the graphene plane increases with the grafting density and grafting length which is attributed to better interfacial coupling between graphene and PA. There exists an optimal balance between grafting density and grafting length to obtain the highest interfacial and parallel thermal conductivity. Two empirical formulas are suggested, which quantitatively account for the effects of grafting length and density on the interfacial and parallel thermal conductivity. Combined with effective medium approximation, for ungrafted graphene in random orientation, the model overestimates the thermal conductivity at low graphene volume fraction (f < 10%) compared with experiments, while it underestimates it at high graphene volume fraction (f > 10%). For unoriented grafted graphene, the model matches the experimental results well. In short, this work provides some valuable guides to obtain the nanocomposites with high thermal conductivity by grafting chain on the surface of graphene. PMID:26800434

  14. Combustion pathways of the alkylated heteroaromatics: bond dissociation enthalpies and alkyl group fragmentations

    SciTech Connect

    Hayes, C.J.; Hadad, C.M.

    2009-11-15

    The bond dissociation enthalpies (BDEs) of the alkyl groups of the alkyl-substituted heterocycles have been studied and compiled using DFT methodology, with the intent of modeling the larger heterocyclic functionalities found in coal. DFT results were calibrated against CBS-QB3 calculations, and qualitative trends were reproduced between these methods. Loss of hydrogen at the benzylic position provided the most favorable route to radical formation, for both the azabenzenes and five-membered heterocycles. The ethyl derivatives had lower BDE values than the methyl derivatives due to increased stabilization of the corresponding radicals. Calculated spin densities correlated well with bond dissociation enthalpies for these compounds, while geometric effects were minimal with respect to the heterocycles themselves. Temperature effects on the bond dissociation enthalpies were minor, ranging by about 5 kcal/mol from 298 to 2000 K; the free energies of reaction dropped significantly over the same range due to entropic effects. Monocyclic heteroaromatic rings were seen to replicate the chemistry of multicyclic heteroaromatic systems.

  15. High feeding intensity increases the severity of fatty liver in the American mink (Neovison vison) with potential ameliorating role for long-chain n-3 polyunsaturated fatty acids

    PubMed Central

    2014-01-01

    Background Rapid body fat mobilization, obesity, and an inadequate supply of n-3 polyunsaturated fatty acids (PUFA) have been suggested to play roles in the etiology of fatty liver in the American mink (Neovison vison). This study examined the effects of feeding intensity and dietary fat source on fatty liver induced by fasting. In a multi-factorial design, 3 different fat sources (herring oil, rich in n-3 PUFA, soya oil, rich in n-6 PUFA, and canola oil, rich in n-9 monounsaturated fatty acids) were fed to mink at a low and high feeding intensity for 10 weeks, followed by an overnight or a 5-day fasting treatment to induce fatty liver. Results Fasting led to the development of fatty liver with increased severity in the mink fed at the high feeding intensity. The herring oil diet, high in long-chain n-3 PUFA, was found to decrease the severity of fatty liver in the mink at the high feeding intensity. Conclusion Preventing excessive weight gain and increasing dietary intake of n-3 long-chain PUFA may help prevent excessive lipid accumulation during prolonged periods of fasting or inappetence by promoting hepatic fatty acid oxidation. PMID:24438337

  16. Alkylation of lignites and peat in low-temperature plasma

    SciTech Connect

    L.I. Shchukin; S.I. Zherebtsov; M.V. Kornievich; O.A. Skutina

    2007-02-15

    The alkylation of lignites and peat was carried out at 50-270{sup o}C in different plasmas. The degree of conversion determined as the yield of the alcohol-benzene extract increases on passing from methane to alcohol plasma. The dependence of the extract yield on the plasma temperature, treatment time, and sample grinding degree was studied. 5 refs., 4 figs., 2 tabs.

  17. Increased Long Chain acyl-Coa Synthetase Activity and Fatty Acid Import Is Linked to Membrane Synthesis for Development of Picornavirus Replication Organelles

    PubMed Central

    Scott, Alison J.; Ford, Lauren A.; Pei, Zhengtong; Watkins, Paul A.; Ernst, Robert K.; Belov, George A.

    2013-01-01

    All positive strand (+RNA) viruses of eukaryotes replicate their genomes in association with membranes. The mechanisms of membrane remodeling in infected cells represent attractive targets for designing future therapeutics, but our understanding of this process is very limited. Elements of autophagy and/or the secretory pathway were proposed to be hijacked for building of picornavirus replication organelles. However, even closely related viruses differ significantly in their requirements for components of these pathways. We demonstrate here that infection with diverse picornaviruses rapidly activates import of long chain fatty acids. While in non-infected cells the imported fatty acids are channeled to lipid droplets, in infected cells the synthesis of neutral lipids is shut down and the fatty acids are utilized in highly up-regulated phosphatidylcholine synthesis. Thus the replication organelles are likely built from de novo synthesized membrane material, rather than from the remodeled pre-existing membranes. We show that activation of fatty acid import is linked to the up-regulation of cellular long chain acyl-CoA synthetase activity and identify the long chain acyl-CoA syntheatse3 (Acsl3) as a novel host factor required for polio replication. Poliovirus protein 2A is required to trigger the activation of import of fatty acids independent of its protease activity. Shift in fatty acid import preferences by infected cells results in synthesis of phosphatidylcholines different from those in uninfected cells, arguing that the viral replication organelles possess unique properties compared to the pre-existing membranes. Our data show how poliovirus can change the overall cellular membrane homeostasis by targeting one critical process. They explain earlier observations of increased phospholipid synthesis in infected cells and suggest a simple model of the structural development of the membranous scaffold of replication complexes of picorna-like viruses, that may be

  18. The behaviour of linear alkyl benzene sulphonate under direct discharge conditions in Vientiane, Lao PDR.

    PubMed

    Whelan, M J; Van Egmond, R; Guymer, I; Lacoursière, J O; Vought, L M B; Finnegan, C; Fox, K K; Sparham, C; O'Connor, S; Vaughan, M; Pearson, J M

    2007-12-01

    Direct discharge of untreated sewage to surface waters is a common practice in many parts of the world. However, relatively little is known about the behaviour of synthetic organic pollutants under these conditions. This paper describes a sampling campaign designed to track changes in water quality in a surface water system in Vientiane (Lao PDR) receiving significant quantities of untreated waste water. The study was based on following in-channel transport using a fluorescent tracer injected as a pulse, with a focus on the anionic surfactant linear alkylbenzene sulphonate (LAS) and ammonia. Water samples were collected at a number of stations with sampling times estimated to coincide with solute time-of-travel. The reduction in LAS concentration with flow-time could be approximated by first-order kinetics with a half life of about 7 h. Free ammonia concentrations decreased more slowly than LAS and remained above the level believed to be toxic for sensitive aquatic species along the entire channel. Changes in the ratios of LAS alkyl chain homologues to total LAS concentrations suggest a preferential removal of longer chain lengths. The role of biodegradation in the removal of LAS was confirmed by the presence of LAS metabolites (sulphophenylcarboxylates, SPCs) which increased systematically (as a fraction of LAS remaining) with flow-time. PMID:17658579

  19. Insertional Inactivation of Branched-Chain α-Keto Acid Dehydrogenase in Staphylococcus aureus Leads to Decreased Branched-Chain Membrane Fatty Acid Content and Increased Susceptibility to Certain Stresses▿

    PubMed Central

    Singh, Vineet K.; Hattangady, Dipti S.; Giotis, Efstathios S.; Singh, Atul K.; Chamberlain, Neal R.; Stuart, Melissa K.; Wilkinson, Brian J.

    2008-01-01

    Staphylococcus aureus is a major community and nosocomial pathogen. Its ability to withstand multiple stress conditions and quickly develop resistance to antibiotics complicates the control of staphylococcal infections. Adaptation to lower temperatures is a key for the survival of bacterial species outside the host. Branched-chain α-keto acid dehydrogenase (BKD) is an enzyme complex that catalyzes the early stages of branched-chain fatty acid (BCFA) production. In this study, BKD was inactivated, resulting in reduced levels of BCFAs in the membrane of S. aureus. Growth of the BKD-inactivated mutant was progressively more impaired than that of wild-type S. aureus with decreasing temperature, to the point that the mutant could not grow at 12°C. The growth of the mutant was markedly stimulated by the inclusion of 2-methylbutyrate in the growth medium at all temperatures tested. 2-Methylbutyrate is a precursor of odd-numbered anteiso fatty acids and bypasses BKD. Interestingly, growth of wild-type S. aureus was also stimulated by including 2-methylbutyrate in the medium, especially at lower temperatures. The anteiso fatty acid content of the BKD-inactivated mutant was restored by the inclusion of 2-methylbutyrate in the medium. Fluorescence polarization measurements indicated that the membrane of the BKD-inactivated mutant was significantly less fluid than that of wild-type S. aureus. Consistent with this result, the mutant showed decreased toluene tolerance that could be increased by the inclusion of 2-methylbutyrate in the medium. The BKD-inactivated mutant was more susceptible to alkaline pH and oxidative stress conditions. Inactivation of the BKD enzyme complex in S. aureus also led to a reduction in adherence of the mutant to eukaryotic cells and its survival in a mouse host. In addition, the mutant offers a tool to study the role of membrane fluidity in the interaction of S. aureus with antimicrobial substances. PMID:18689519

  20. Towards understanding the mechanism of action of antibacterial N-alkyl-3-hydroxypyridinium salts: Biological activities, molecular modeling and QSAR studies.

    PubMed

    Dolezal, Rafael; Soukup, Ondrej; Malinak, David; Savedra, Ranylson M L; Marek, Jan; Dolezalova, Marie; Pasdiorova, Marketa; Salajkova, Sarka; Korabecny, Jan; Honegr, Jan; Ramalho, Teodorico C; Kuca, Kamil

    2016-10-01

    In this study, we have carried out a combined experimental and computational investigation to elucidate several bred-in-the-bone ideas standing out in rational design of novel cationic surfactants as antibacterial agents. Five 3-hydroxypyridinium salts differing in the length of N-alkyl side chain have been synthesized, analyzed by high performance liquid chromatography, tested for in vitro activity against a panel of pathogenic bacterial and fungal strains, computationally modeled in water by a SCRF B3LYP/6-311++G(d,p) method, and evaluated by a systematic QSAR analysis. Given the results of this work, the hypothesis suggesting that higher positive charge of the quaternary nitrogen should increase antimicrobial efficacy can be rejected since 3-hydroxyl group does increase the positive charge on the nitrogen but, simultaneously, it significantly derogates the antimicrobial activity by lowering the lipophilicity and by escalating the desolvation energy of the compounds in comparison with non-hydroxylated analogues. Herein, the majority of the prepared 3-hydroxylated substances showed notably lower potency than the parent pyridinium structures, although compound 8 with C12 alkyl chain proved a distinctly better antimicrobial activity in submicromolar range. Focusing on this anomaly, we have made an effort to reveal the reason of the observed activity through a molecular dynamics simulation of the interaction between the bacterial membrane and compound 8 in GROMACS software. PMID:27341309

  1. Genetic adaptation of fatty-acid metabolism: a human-specific haplotype increasing the biosynthesis of long-chain omega-3 and omega-6 fatty acids.

    PubMed

    Ameur, Adam; Enroth, Stefan; Johansson, Asa; Zaboli, Ghazal; Igl, Wilmar; Johansson, Anna C V; Rivas, Manuel A; Daly, Mark J; Schmitz, Gerd; Hicks, Andrew A; Meitinger, Thomas; Feuk, Lars; van Duijn, Cornelia; Oostra, Ben; Pramstaller, Peter P; Rudan, Igor; Wright, Alan F; Wilson, James F; Campbell, Harry; Gyllensten, Ulf

    2012-05-01

    Omega-3 and omega-6 long-chain polyunsaturated fatty acids (LC-PUFAs) are essential for the development and function of the human brain. They can be obtained directly from food, e.g., fish, or synthesized from precursor molecules found in vegetable oils. To determine the importance of genetic variability to fatty-acid biosynthesis, we studied FADS1 and FADS2, which encode rate-limiting enzymes for fatty-acid conversion. We performed genome-wide genotyping (n = 5,652 individuals) and targeted resequencing (n = 960 individuals) of the FADS region in five European population cohorts. We also analyzed available genomic data from human populations, archaic hominins, and more distant primates. Our results show that present-day humans have two common FADS haplotypes-defined by 28 closely linked SNPs across 38.9 kb-that differ dramatically in their ability to generate LC-PUFAs. No independent effects on FADS activity were seen for rare SNPs detected by targeted resequencing. The more efficient, evolutionarily derived haplotype appeared after the lineage split leading to modern humans and Neanderthals and shows evidence of positive selection. This human-specific haplotype increases the efficiency of synthesizing essential long-chain fatty acids from precursors and thereby might have provided an advantage in environments with limited access to dietary LC-PUFAs. In the modern world, this haplotype has been associated with lifestyle-related diseases, such as coronary artery disease. PMID:22503634

  2. Self-assembly of a series of random copolymers bearing amphiphilic side chains.

    PubMed

    Wu, Xu; Qiao, Yingjie; Yang, Hui; Wang, Jinben

    2010-09-15

    A novel series of comb-like random copolymers were prepared by polymerization of amphiphilic macromonomers, 2-(acrylamido)-octane sulfonic acid (AMC(8)S), 2-(acrylamido)-dodecane sulfonic acid (AMC(12)S), and 2-(acrylamido)-hexadecane sulfonic acid (AMC(16)S), with 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS) respectively. The synthesis of the polymers with the same contents of amphiphilic units as side chains, but different chain length, enabled us to study the chain length dependence of their association in salt solution. Steady-state fluorescence measurements with pyrene as a polarity probe, quasielastic light scattering techniques (QELS) and transmission electron micrograph (TEM) were employed to investigate the associative properties of the system. The above investigations showed that all kinds of side chains begin to assemble at certain polymer concentrations and the critical aggregation concentration (CAC) decrease dramatically with the increase in the length and content of alkyl. An interesting phenomenon is that the assembly tends more favorably to occur among different molecules rather than within single molecule when the number of carbon atoms in the alkyl groups or the polymer concentration increases, leading to the formation of larger multimolecular micelle-like aggregate. The aim of the present work is to establish the fundamental preconditions of intramolecular and intermolecular association fashions for the polymers, which is useful for the exploitation of functional groups and contributes to the development of amphiphilic random polymers. PMID:20576273

  3. Motor fuel alkylation process utilizing low acid

    SciTech Connect

    Kocal, J.A.; Imai, T.

    1987-01-06

    A process is described for the alkylation of an isoparaffin with an olefin acting agent comprising contacting the isoparaffin with the olefin acting agent at alkylation conditions in the presence of a catalyst. The catalyst consists essentially of an anhydrous, nonalcoholic mixture of from about 5 to 15 wt. % methyl tert-butyl ether and from 85 to 95 wt. % hydrofluoric acid. The volumetric ratio of hydrofluoric acid to isoparaffin and olefin acting agent is less than 0.75.

  4. Rat long chain acyl-CoA synthetase 5 increases fatty acid uptake and partitioning to cellular triacylglycerol in McArdle-RH7777 cells.

    PubMed

    Mashek, Douglas G; McKenzie, Michelle A; Van Horn, Cynthia G; Coleman, Rosalind A

    2006-01-13

    Long chain acyl-CoA synthetase (ACSL) catalyzes the initial step in long chain fatty acid metabolism. Of the five mammalian ACSL isoforms cloned and characterized, ACSL5 is the only isoform found to be located, in part, on mitochondria and thus was hypothesized to be involved in fatty acid oxidation. To elucidate the specific roles of ACSL5 in fatty acid metabolism, we used adenoviral-mediated overexpression of ACSL5 (Ad-ACSL5) in rat hepatoma McArdle-RH7777 cells. Confocal microscopy revealed that Ad-ACSL5 colocalized to both mitochondria and endoplasmic reticulum. When compared with cells infected with Ad-GFP, Ad-ACSL5-infected cells at 24 h after infection had 2-fold higher acyl-CoA synthetase activities and 30% higher rates of fatty acid uptake when incubated with 500 microM [1-(14)C]oleic acid. Metabolism of [1-(14)C]oleic acid to cellular triacylglycerol (TAG) increased 42% in Ad-ACSL5-infected cells, but when compared with control cells, metabolism to acid-soluble metabolites, phospholipids, and medium TAG did not differ substantially. The incorporation of [1-(14)C]oleate and [1,2,3-(3)H]glycerol into TAG was similar in Ad-ACSL5-infected cells, thus indicating that Ad-ACSL5 increased TAG synthesis through both de novo and reacylation pathways. However, [1-(14)C]acetic acid incorporation into cellular lipids showed that, when compared with control cells, Ad-ACSL5-infected cells did not increase the metabolism of fatty acids that were derived from de novo synthesis. These results suggest that uptake of fatty acids into cells is regulated by metabolism and that overexpressed ACSL5 partitions exogenously derived fatty acids toward TAG synthesis and storage. PMID:16263710

  5. Computational investigation of the hydration of alkyl diammonium chlorides and their effect on THF/water phase separation.

    PubMed

    Jahangiri, Soran; Mercer, Sean M; Jessop, Philip G; Peslherbe, Gilles H

    2013-07-01

    The solvation behavior of alkyl diammonium chlorides of varying alkyl chain length and the molecular details of their effect on the salting-out of organic molecules in aqueous phase have been investigated by classical molecular dynamics simulations. More specifically, systems containing water, tetrahydrofuran (THF), and their mixtures with α,ω-alkyl diammonium chlorides [H3N(CH2)nNH3]Cl2 (n = 2, 4, 6, 8, and 10) were simulated at ambient temperature and pressure. Various force fields were tested and one was chosen based on its ability to reproduce the physical properties of the pure THF solution and its mixture with water. Structural and thermodynamic analyses of the simulated salt-solvent mixtures reveal different extents of hydration of the dications depending on the alkyl chain length and indicate that the hydrophobic interactions between the dication alkyl chain and organic molecules play a key role in the solvation of the latter species. In fact, shorter dications are shown to promote THF/water phase separation, in agreement with previous experimental findings. PMID:23789929

  6. The alkyl linkers in tandem-homodimers of a β-sheet-forming nonapeptide affect the self-assembled nanostructures.

    PubMed

    Tomizaki, Kin-Ya; Tanaka, Atsushi; Shimada, Hiroki; Nishizawa, Koki; Wada, Tsubasa; Imai, Takahito

    2016-06-01

    There is increasing interest in designing smart biomaterials by employing the self-assembly characteristics of synthetic peptides. The use of amyloid-like fibrils is one approach to nanometer- and micrometer-sized supramolecular structures. However, it is generally difficult to predict and/or analyze peptide conformations in nanostructures generated by the self-assembly of β-sheet-forming peptides such as amyloid-β peptide because each peptide experiences a slightly different environment. Therefore, a methodology for rationally designing peptide-based smart materials is required. In this study, we demonstrate the design and synthesis of tandem-homodimers of a β-sheet-forming peptide where the amino acid sequence is duplicated in series and joined via alkyl linkers of different chain length. The conformations of these tandem-homodimers within the self-assembled nanoarchitectures in aqueous solution were characterized. Our findings demonstrate that the hydrophobicity and/or flexibility of the alkyl linkers significantly affect the peptide conformation (extended or bent) of the self-assembled peptide nanostructures. We believe that the present tandem-homodimerization method represents a new direction for the rational design of peptide-based smart biomaterials. PMID:27117426

  7. N-Alkylation by Hydrogen Autotransfer Reactions.

    PubMed

    Ma, Xiantao; Su, Chenliang; Xu, Qing

    2016-06-01

    Owing to the importance of amine/amide derivatives in all fields of chemistry, and also the green and environmentally benign features of using alcohols as alkylating reagents, the relatively high atom economic dehydrative N-alkylation reactions of amines/amides with alcohols through hydrogen autotransfer processes have received much attention and have developed rapidly in recent decades. Various efficient homogeneous and heterogeneous transition metal catalysts, nano materials, electrochemical methods, biomimetic methods, asymmetric N-alkylation reactions, aerobic oxidative methods, and even certain transition metal-free, catalyst-free, or autocatalyzed methods, have also been developed in recent years. With a brief introduction to the background and developments in this area of research, this chapter focuses mainly on recent progress and technical and conceptual advances contributing to the development of this research in the last decade. In addition to mainstream research on homogeneous and heterogeneous transition metal-catalyzed reactions, possible mechanistic routes for hydrogen transfer and alcohol activation, which are key processes in N-alkylation reactions but seldom discussed in the past, the recent reports on computational mechanistic studies of the N-alkylation reactions, and the newly emerged N-alkylation methods based on novel alcohol activation protocols such as air-promoted reactions and transition metal-free methods, are also reviewed in this chapter. Problems and bottlenecks that remained to be solved in the field, and promising new research that deserves greater future attention and effort, are also reviewed and discussed. PMID:27573267

  8. Alkyl triazole glycosides (ATGs)--a new class of bio-related surfactants.

    PubMed

    Sani, Faramarz Aliasghari; Heidelberg, Thorsten; Hashim, Rauzah; Farhanullah

    2012-09-01

    A series of glucose based surfactants varying in chain length and anomeric configuration were synthesized and investigated on their surfactant properties. The synthesis applied glycosylation of propargyl alcohol followed by cycloaddition with alkyl azides in CLICK chemistry fashion. This approach enables a homogeneous coupling of hydrophilic unprotected sugars and hydrophobic paraffin components in low molecular weight alcohols without solvent side reactions, as commonly found for APGs. The combination of alcohols as inert medium with practically quantitative coupling of the surfactant domains avoids particularly hydrophobic contaminations of the surfactant, thus providing access to pure surfactants. ATGs with chain lengths up to 12 carbons exhibit Krafft points below room temperature and no cloud points were detected. The values for the CMC of ATGs with 12 carbon alkyl chains and above were in good agreement with those of corresponding alkyl glucosides. However, lower homologues exhibited significantly smaller CMCs, and the trend of the CMC upon the chain length did not match common surfactant behavior. This deviation may be related to the triazole that links the two surfactant domains. PMID:22609603

  9. Production of n-alkyl lipids in living plants and implications for the geologic past

    NASA Astrophysics Data System (ADS)

    Diefendorf, Aaron F.; Freeman, Katherine H.; Wing, Scott L.; Graham, Heather V.

    2011-12-01

    Leaf waxes (i.e., n-alkyl lipids or n-alkanes) are land-plant biomarkers widely used to reconstruct changes in climate and the carbon isotopic composition of the atmosphere. There is little information available, however, on how the production of leaf waxes by different kinds of plants might influence the abundance and isotopic composition of n-alkanes in sedimentary archives. This lack of information increases uncertainty in interpreting n-alkyl lipid abundance and δ 13C signals in ancient settings. We provide here n-alkyl abundance distributions and carbon isotope fractionation data for deciduous and evergreen angiosperm and gymnosperm leaves from 46 tree species, representing 24 families. n-Alkane abundances are significantly higher in angiosperms than gymnosperms; many of the gymnosperm species investigated did not produce any n-alkanes. On average, deciduous angiosperms produce 200 times more n-alkanes than deciduous gymnosperms. Although differences between angiosperms and gymnosperms dominate the variance in n-alkane abundance, leaf life-span is also important, with higher n-alkane abundances in longer-lived leaves. n-Alkanol abundances covary with n-alkanes, but n-alkanoic acids have similar abundances across all plant groups. Isotopic fractionation between leaf tissue and individual alkanes ( ɛlipid) varies by as much as 10‰ among different chain lengths. Overall, ɛlipid values are slightly lower (-4.5‰) for angiosperm than for gymnosperm (-2.5‰) n-alkanes. Angiosperms commonly express slightly higher Δleaf (photosynthetic discrimination) relative to gymnosperms under similar growth conditions. As a result, angiosperm n-alkanes are expected to be generally 3-5‰ more depleted in 13C relative to gymnosperm alkanes for the same locality. Differences in n-alkane production indicate the biomarker record will largely (but not exclusively) reflect angiosperms if both groups were present, and also that evergreen plants will likely be overrepresented

  10. A mutation in the dynein heavy chain gene compensates for energy deficit of mutant SOD1 mice and increases potentially neuroprotective IGF-1

    PubMed Central

    2011-01-01

    Background Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by a progressive loss of motor neurons. ALS patients, as well as animal models such as mice overexpressing mutant SOD1s, are characterized by increased energy expenditure. In mice, this hypermetabolism leads to energy deficit and precipitates motor neuron degeneration. Recent studies have shown that mutations in the gene encoding the dynein heavy chain protein are able to extend lifespan of mutant SOD1 mice. It remains unknown whether the protection offered by these dynein mutations relies on a compensation of energy metabolism defects. Results SOD1(G93A) mice were crossbred with mice harboring the dynein mutant Cramping allele (Cra/+ mice). Dynein mutation increased adipose stores in compound transgenic mice through increasing carbohydrate oxidation and sparing lipids. Metabolic changes that occurred in double transgenic mice were accompanied by the normalization of the expression of key mRNAs in the white adipose tissue and liver. Furthermore, Dynein Cra mutation rescued decreased post-prandial plasma triglycerides and decreased non esterified fatty acids upon fasting. In SOD1(G93A) mice, the dynein Cra mutation led to increased expression of IGF-1 in the liver, increased systemic IGF-1 and, most importantly, to increased spinal IGF-1 levels that are potentially neuroprotective. Conclusions These findings suggest that the protection against SOD1(G93A) offered by the Cramping mutation in the dynein gene is, at least partially, mediated by a reversal in energy deficit and increased IGF-1 availability to motor neurons. PMID:21521523

  11. Impact of Hydrophobic Chain Composition on Amphiphilic Macromolecule Antiatherogenic Bioactivity

    PubMed Central

    2015-01-01

    Amphiphilic macromolecules (AMs) composed of sugar backbones modified with branched aliphatic chains and a poly(ethylene glycol) (PEG) tail can inhibit macrophage uptake of oxidized low-density lipoproteins (oxLDL), a major event underlying atherosclerosis development. Previous studies indicate that AM hydrophobic domains influence this bioactivity through interacting with macrophage scavenger receptors, which can contain basic and/or hydrophobic residues within their binding pockets. In this study, we compare two classes of AMs to investigate their ability to promote athero-protective potency via hydrogen-bonding or hydrophobic interactions with scavenger receptors. A series of ether-AMs, containing methoxy-terminated aliphatic arms capable of hydrogen-bonding, was synthesized. Compared to analogous AMs containing no ether moieties (alkyl-AMs), ether-AMs showed improved cytotoxicity profiles. Increasing AM hydrophobicity via incorporation of longer and/or alkyl-terminated hydrophobic chains yielded macromolecules with enhanced oxLDL uptake inhibition. These findings indicate that hydrophobic interactions and the length of AM aliphatic arms more significantly influence AM bioactivity than hydrogen-bonding. PMID:25070717

  12. Blend of alkyl phenol ethoxylates and alkyl phenol glycoxylates and their use as surfactants

    SciTech Connect

    Grolitzer, M. A.

    1985-11-12

    Nonionic surfactant compositions useful in forming stable emulsions with oil in saline solutions comprising a blend of: at least one alkyl phenol ethoxylate and at least one alkyl phenol glycoxylate. These surfactant compositions may be employed in enhanced oil recovery processes and other applications where good emulsification and high salinity tolerances are required such as textiles, leather, dairy, concrete grinding aids and drilling muds.

  13. Differential alkylation-based redox proteomics--Lessons learnt.

    PubMed

    Wojdyla, Katarzyna; Rogowska-Wrzesinska, Adelina

    2015-12-01

    Cysteine is one of the most reactive amino acids. This is due to the electronegativity of sulphur atom in the side chain of thiolate group. It results in cysteine being present in several distinct redox forms inside the cell. Amongst these, reversible oxidations, S-nitrosylation and S-sulfenylation are crucial mediators of intracellular redox signalling, with known associations to health and disease. Study of their functionalities has intensified thanks to the development of various analytical strategies, with particular contribution from differential alkylation-based proteomics methods. Presented here is a critical evaluation of differential alkylation-based strategies for the analysis of S-nitrosylation and S-sulfenylation. The aim is to assess the current status and to provide insights for future directions in the dynamically evolving field of redox proteomics. To achieve that we collected 35 original research articles published since 2010 and analysed them considering the following parameters, (i) resolution of modification site, (ii) quantitative information, including correction of modification levels by protein abundance changes and determination of modification site occupancy, (iii) throughput, including the amount of starting material required for analysis. The results of this meta-analysis are the core of this review, complemented by issues related to biological models and sample preparation in redox proteomics, including conditions for free thiol blocking and labelling of target cysteine oxoforms. PMID:26282677

  14. Differential alkylation-based redox proteomics – Lessons learnt

    PubMed Central

    Wojdyla, Katarzyna; Rogowska-Wrzesinska, Adelina

    2015-01-01

    Cysteine is one of the most reactive amino acids. This is due to the electronegativity of sulphur atom in the side chain of thiolate group. It results in cysteine being present in several distinct redox forms inside the cell. Amongst these, reversible oxidations, S-nitrosylation and S-sulfenylation are crucial mediators of intracellular redox signalling, with known associations to health and disease. Study of their functionalities has intensified thanks to the development of various analytical strategies, with particular contribution from differential alkylation-based proteomics methods. Presented here is a critical evaluation of differential alkylation-based strategies for the analysis of S-nitrosylation and S-sulfenylation. The aim is to assess the current status and to provide insights for future directions in the dynamically evolving field of redox proteomics. To achieve that we collected 35 original research articles published since 2010 and analysed them considering the following parameters, (i) resolution of modification site, (ii) quantitative information, including correction of modification levels by protein abundance changes and determination of modification site occupancy, (iii) throughput, including the amount of starting material required for analysis. The results of this meta-analysis are the core of this review, complemented by issues related to biological models and sample preparation in redox proteomics, including conditions for free thiol blocking and labelling of target cysteine oxoforms. PMID:26282677

  15. Long chain n-3 polyunsaturated fatty acids increase the efficacy of docetaxel in mammary cancer cells by downregulating Akt and PKCε/δ-induced ERK pathways.

    PubMed

    Chauvin, Lucie; Goupille, Caroline; Blanc, Charly; Pinault, Michelle; Domingo, Isabelle; Guimaraes, Cyrille; Bougnoux, Philippe; Chevalier, Stephan; Mahéo, Karine

    2016-04-01

    Taxanes can induce drug resistance by increasing signaling pathways such as PI3K/Akt and ERK, which promote survival and cell growth in human cancer cells. We have previously shown that long chain n-3 polyunsaturated fatty acids, such as docosahexaenoic acid (DHA, 22:6n-3) decrease resistance of experimental mammary tumors to anticancer drugs. Our objective was to determine whether DHA could increase tumor sensitivity to docetaxel by down-regulating these survival pathways. In docetaxel-treated MDA-MB-231 cells, phosphorylated-ERK1/2 levels were increased by 60% in membrane and nuclear compartments, compared to untreated cells. Our data showed that ERK1/2 activation depended on PKC activation since: i) enzastaurin (a pan-PKC inhibitor) blocked docetaxel-induced ERK1/2 phosphorylation ii) docetaxel increased PKC activity by 30% and phosphatidic acid level by 1.6-fold iii) inhibition of PKCε and PKCδ by siRNA resulted in reduced phosphorylated ERK1/2 levels. In DHA-supplemented cells, docetaxel was unable to increase PKCε and δ levels in membrane and nuclear fractions, resulting in diminished ERK1/2 phosphorylation and increased docetaxel efficacy. Reduced membrane level of PKCε and PKCδ was associated with significant incorporation of DHA in all phospholipids, including phosphatidylcholine which is a major source of phosphatidic acid. Additionally, examination of the Akt pathway showed that DHA could repress docetaxel-induced Ser473Akt phosphorylation. In rat mammary tumors, dietary DHA supplementation during docetaxel chemotherapy repressed ERK and Akt survival pathways and in turn strongly improved taxane efficacy. The P-ERK level was negatively correlated with tumor regression. These findings are of potential clinical importance in treating chemotherapy-refractory cancer. PMID:26821209

  16. The Salivary IgA Flow Rate Is Increased by High Concentrations of Short-Chain Fatty Acids in the Cecum of Rats Ingesting Fructooligosaccharides

    PubMed Central

    Yamamoto, Yuko; Takahahi, Toru; To, Masahiro; Nakagawa, Yusuke; Hayashi, Takashi; Shimizu, Tomoko; Kamata, Yohei; Saruta, Juri; Tsukinoki, Keiichi

    2016-01-01

    Salivary immunoglobulin A (IgA) serves as a major effector in mucosal immunity by preventing submucosal invasion of pathogens. However, the mechanism by which consumption of fermentable fibers increases IgA in saliva was not fully elucidated. This study investigated the effects of fructooligosaccharides (FOS) intake and time after feeding on IgA levels in the saliva and cecal digesta and on the concentration of short-chain fatty acids (SCFA) in the cecum in rats. Five-week-old rats were fed a fiber-free diet or a diet with 50 g/kg FOS for zero, one, four, and eight weeks. Ingestion of FOS at one and eight weeks led to a higher IgA flow rate of saliva per weight of submandibular gland tissue (p < 0.05), which positively correlated with the concentration of SCFA in the cecal digesta (rs = 0.86, p = 0.0006, n = 12), but showed no correlation with the concentration of IgA in the cecal digesta (rs = 0.15, p = 0.3, n = 48). These results suggested that ingestion of FOS increased salivary IgA secretion through high levels of SCFA in the large intestine, which was produced by fermentation of FOS. Thus, continuously ingesting FOS for more than one week could increase secretion of salivary IgA. PMID:27548207

  17. The Salivary IgA Flow Rate Is Increased by High Concentrations of Short-Chain Fatty Acids in the Cecum of Rats Ingesting Fructooligosaccharides.

    PubMed

    Yamamoto, Yuko; Takahahi, Toru; To, Masahiro; Nakagawa, Yusuke; Hayashi, Takashi; Shimizu, Tomoko; Kamata, Yohei; Saruta, Juri; Tsukinoki, Keiichi

    2016-01-01

    Salivary immunoglobulin A (IgA) serves as a major effector in mucosal immunity by preventing submucosal invasion of pathogens. However, the mechanism by which consumption of fermentable fibers increases IgA in saliva was not fully elucidated. This study investigated the effects of fructooligosaccharides (FOS) intake and time after feeding on IgA levels in the saliva and cecal digesta and on the concentration of short-chain fatty acids (SCFA) in the cecum in rats. Five-week-old rats were fed a fiber-free diet or a diet with 50 g/kg FOS for zero, one, four, and eight weeks. Ingestion of FOS at one and eight weeks led to a higher IgA flow rate of saliva per weight of submandibular gland tissue (p < 0.05), which positively correlated with the concentration of SCFA in the cecal digesta (rs = 0.86, p = 0.0006, n = 12), but showed no correlation with the concentration of IgA in the cecal digesta (rs = 0.15, p = 0.3, n = 48). These results suggested that ingestion of FOS increased salivary IgA secretion through high levels of SCFA in the large intestine, which was produced by fermentation of FOS. Thus, continuously ingesting FOS for more than one week could increase secretion of salivary IgA. PMID:27548207

  18. A low omega-6 polyunsaturated fatty acid (n-6 PUFA) diet increases omega-3 (n-3) long chain PUFA status in plasma phospholipids in humans.

    PubMed

    Wood, K E; Lau, A; Mantzioris, E; Gibson, R A; Ramsden, C E; Muhlhausler, B S

    2014-04-01

    This study aimed to determine the effect of reducing the dietary linoleic acid (LA) intake from ~5% to <2.5% energy (%E) on n-3 long chain PUFA (LCPUFA) status in humans. Thirty-six participants followed a <2.5%E LA diet for 4 weeks. Nutrient intakes were estimated from diet diaries and blood samples were collected for assessment of fatty acid composition in plasma and erythrocyte phospholipids. LA intakes were reduced from 4.6%E to 2%E during the low LA intervention (P<0.001) while n-3 LCPUFA intakes were unchanged. LA and total n-6 PUFA content of plasma and erythrocyte phospholipids were significantly reduced after the low LA diet phase (P<0.001). The n-3 LCPUFA content of plasma phospholipids was significantly increased after the low LA diet compared to baseline (6.22% vs. 5.53%, P<0.001). These data demonstrate that reducing LA intake for 4 weeks increases n-3 LCPUFA status in humans in the absence of increased n-3 LCPUFA intake. PMID:24456663

  19. Decreased stability of DNA in cells treated with alkylating agents

    SciTech Connect

    Frankfurt, O.S. )

    1990-12-01

    A modified highly sensitive procedure for the evaluation of DNA damage in individual cells treated with alkylating agents is reported. The new methodology is based on the amplification of single-strandedness in alkylated DNA by heating in the presence of Mg{sup 2+}. Human ovarian carcinoma cells A2780 were treated with nitrogen mustard (HN2), fixed in methanol, and stained with monoclonal antibody (MOAB) F7-26 generated against HN2-treated DNA. Binding of MOAB was measured by flow cytometry with indirect immunofluorescence. Intensive binding of MOAB to control and drug-treated cells was observed after heating in Tris buffer supplemented with MgCl{sub 2}. Thus, the presence of phosphates and MgCl{sub 2} during heating was necessary for the detection of HN2-induced changes in DNA stability. Fluorescence of HN2-treated cells decreased to background levels after treatment with single-strand-specific S{sub 1} nuclease. MOAB F7-26 interacted with single-stranded regions in DNA and did not bind to dsDNA or other cellular antigens. It is suggested that alkylation of guanines decreased the stability of the DNA molecule and increased the access of MOAB F7-26 to deoxycytidines on the opposite DNA strand.

  20. Alkylation of isobutane with light olefins: Yields of alkylates for different olefins

    SciTech Connect

    Albright, L.F.; Kranz, K.E.; Masters, K.R.

    1993-12-01

    For alkylation of isobutane with C{sub 3}-C{sub 5} olefins using sulfuric acid as the catalyst, the yields of alkylates with different olefins are compared as the operating conditions are changed. The results of recent pilot plant experiments with propylene, C{sub 4} olefins, and C{sub 5} olefins permit such comparisons. The yields expressed as weight of alkylate produced per 100 wt of olefin consumed varied from about 201:100 to 220:100. Weight ratios of the isobutane consumed per olefin consumed vary from about 101:100 to 120:100. differences of yield values are explained by the changes in the overall chemistry. The procedure employed to calculate yields with good accuracy is based on the analysis of the alkylate and the amount of conjunct polymers produced. Based on literature data, yields are also reported for alkylations using HF as the catalyst.

  1. PKC activation increases Ca2+ sensitivity of permeabilized lymphatic muscle via myosin light chain 20 phosphorylation-dependent and -independent mechanisms

    PubMed Central

    Dougherty, Patrick J.; Nepiyushchikh, Zhanna V.; Chakraborty, Sanjukta; Wang, Wei; Davis, Michael J.; Zawieja, David C.

    2014-01-01

    The contractile activity of muscle cells lining the walls of collecting lymphatics is responsible for generating and regulating flow within the lymphatic system. Activation of PKC signaling contributes to the regulation of smooth muscle contraction by enhancing sensitivity of the contractile apparatus to Ca2+. It is currently unknown whether PKC signaling contributes to the regulation of lymphatic muscle contraction. We hypothesized that the activation of PKC signaling would increase the sensitivity of the lymphatic myofilament to Ca2+. To test this hypothesis, we determined the effects of PKC activation with phorbol esters [PMA or phorbol dibutyrate (PDBu)] on the contractile behavior of α-toxin-permeabilized rat mesenteric and cervical lymphatics or the thoracic duct. The addition of PMA or PDBu induced a significant increase in the contractile force of submaximally activated α-toxin-permeabilized lymphatic muscle independent of a change in intracellular Ca2+ concentration, and the Ca2+-force relationship of lymphatic muscle was significantly left shifted, indicating greater myofilament Ca2+ sensitivity. Phorbol esters increased the maximal rate of force development, whereas the rate of relaxation was reduced. Western blot and immunohistochemistry data indicated that the initial rapid increase in tension development after stimulation by PDBu was associated with myosin light chain (MLC)20 phosphorylation; however, the later, steady-state Ca2+ sensitization of permeabilized lymphatic muscle was not associated with increased phosphorylation of MLC20 at Ser19, 17-kDa C-kinase-potentiated protein phosphatase-1 inhibitor at Thr38, or caldesmon at Ser789. Thus, these data indicate that PKC-dependent Ca2+ sensitization of lymphatic muscle may involve MLC20 phosphorylation-dependent and -independent mechanism(s). PMID:24414065

  2. Synthesis and calcium channel blocker activity of alkyl 1,4-dihydro-2,6-dimethyl-4-nitrobenzyl thioimidazolyl-3,5-pyridinedicarboxylates.

    PubMed

    Zarghi, A; Faizi, M; Abdolahnejad, R; Fassihi, A

    2003-05-01

    New alkyl ester analogues of nifedipine, in which the orthonitrophenyl group of position 4 is replaced by 1-methyl 2-(p-nitrobenzyl)thio-5-imidazolyl substituent, were synthesized and evaluated as calcium-channel antagonists using the high K+ contraction of guinea-pig ileal longitudinal smooth muscle. The results for the symmetrical esters showed that increasing the length of methylen chain in C3 and C5 ester substituents decreased activity. When the presence of bulky lipophilic esters increased activity. In unsymmetrical diester series, the results showed when R1 is a small substituent (R1 = Me), increasing of the lipophilic property in R2 substituent increased the activity if this high lipophilicity don't accompany with steric hinderance. Our results demonstrate that the most active compound was diphenyl ester derivative and it was almost seven times more active than the reference drug nifedipine. PMID:12918227

  3. Lewis Acid Assisted Nickel-Catalyzed Cross-Coupling of Aryl Methyl Ethers by C-O Bond-Cleaving Alkylation: Prevention of Undesired β-Hydride Elimination.

    PubMed

    Liu, Xiangqian; Hsiao, Chien-Chi; Kalvet, Indrek; Leiendecker, Matthias; Guo, Lin; Schoenebeck, Franziska; Rueping, Magnus

    2016-05-10

    In the presence of trialkylaluminum reagents, diverse aryl methyl ethers can be transformed into valuable products by C-O bond-cleaving alkylation, for the first time without the limiting β-hydride elimination. This new nickel-catalyzed dealkoxylative alkylation method enables powerful orthogonal synthetic strategies for the transformation of a variety of naturally occurring and easily accessible anisole derivatives. The directing and/or activating properties of aromatic methoxy groups are utilized first, before they are replaced by alkyl chains in a subsequent coupling process. PMID:27062726

  4. Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide

    NASA Astrophysics Data System (ADS)

    Belloche, Arnaud; Garrod, Robin T.; Müller, Holger S. P.; Menten, Karl M.

    2014-09-01

    The largest noncyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times that of its straight-chain structural isomer. This detection suggests that branched carbon-chain molecules may be generally abundant in the ISM. Our astrochemical model indicates that both isomers are produced within or upon dust grain ice mantles through the addition of molecular radicals, albeit via differing reaction pathways. The production of iso-propyl cyanide appears to require the addition of a functional group to a nonterminal carbon in the chain. Its detection therefore bodes well for the presence in the ISM of amino acids, for which such side-chain structure is a key characteristic.

  5. Targeted delivery of a model immunomodulator to the lymphatic system: comparison of alkyl ester versus triglyceride mimetic lipid prodrug strategies.

    PubMed

    Han, Sifei; Quach, Tim; Hu, Luojuan; Wahab, Anisa; Charman, William N; Stella, Valentino J; Trevaskis, Natalie L; Simpson, Jamie S; Porter, Christopher J H

    2014-03-10

    A lipophilic prodrug approach has been used to promote the delivery of a model immunomodulator, mycophenolic acid (MPA), to the lymphatic system after oral administration. Lymphatic transport was employed to facilitate enhanced drug uptake into lymphocytes, as recent studies demonstrate that targeted drug delivery to lymph resident lymphocytes may enhance immunomodulatory effects. Two classes of lymph-directing prodrugs were synthesised. Alkyl chain derivatives (octyl mycophenolate, MPA-C8E; octadecyl mycophenolate, MPA-C18E; and octadecyl mycophenolamide, MPA-C18AM), to promote passive partitioning into lipids in lymphatic transport pathways, and a triglyceride mimetic prodrug (1,3-dipalmitoyl-2-mycophenoloyl glycerol, 2-MPA-TG) to facilitate metabolic integration into triglyceride deacylation-reacylation pathways. Lymphatic transport, lymphocyte uptake and plasma pharmacokinetics were assessed in mesenteric lymph and carotid artery cannulated rats following intraduodenal infusion of lipid-based formulations containing MPA or MPA prodrugs. Patterns of prodrug hydrolysis in rat digestive fluid, and cellular re-esterification in vivo, were evaluated to examine the mechanisms responsible for lymphatic transport. Poor enzyme stability and low absorption appeared to limit lymphatic transport of the alkyl derivatives, although two of the three alkyl chain prodrugs - MPA-C18AM (6-fold) and MPA-C18E (13-fold) still increased lymphatic drug transport when compared to MPA. In contrast, 2-MPA-TG markedly increased lymphatic drug transport (80-fold) and drug concentrations in lymphocytes (103-fold), and this was achieved via biochemical incorporation into triglyceride deacylation-reacylation pathways. The prodrug was hydrolysed rapidly to 2-mycophenoloyl glycerol (2-MPA-MG) in the presence of rat digestive fluid, and 2-MPA-MG was subsequently re-esterified in the enterocyte with oleic acid (most likely originating from the co-administered formulation) prior to accessing the

  6. Naturally Extended CT · AG Repeats Increase H-DNA Structures and Promoter Activity in the Smooth Muscle Myosin Light Chain Kinase Gene▿

    PubMed Central

    Han, Yoo-Jeong; de Lanerolle, Primal

    2008-01-01

    Naturally occurring repeat sequences capable of adopting H-DNA structures are abundant in promoters of disease-related genes. In support of this, we found (CT)22 · (AG)22 repeats in the promoter of smooth muscle myosin light chain kinase (smMLCK), a key regulator of vascular smooth muscle function. We also found an insertion mutation that adds another six pairs of CT · AG repeats and increases smMLCK promoter activity in spontaneously hypertensive rats (SHR). Therefore, we used the smMLCK promoters from normotensive and hypertensive rats as a model system to determine how CT · AG repeats form H-DNA, an intramolecular triplex, and regulate promoter activity. High-resolution mapping with a chemical probe selective for H-DNA showed that the CT · AG repeats adopt H-DNA structures at a neutral pH. Importantly, the SHR promoter forms longer H-DNA structures than the promoter from normotensive rats. Reconstituting nucleosomes on the promoters, in vitro, showed no difference in nucleosome positioning between the two promoters. However, chromatin immunoprecipitation analyses revealed that histone acetylations are greater in the hypertensive promoter. Thus, our findings suggest that the extended CT · AG repeats in the SHR promoter increase H-DNA structures, histone modifications, and promoter activity of the smMLCK, perhaps contributing to vascular disorders in hypertension. PMID:17991897

  7. A poly(alkyl methacrylate-divinylbenzene-vinylbenzyl trimethylammonium chloride) monolithic column for solid-phase microextraction.

    PubMed

    Liu, Wan-Ling; Lirio, Stephen; Yang, Yicong; Wu, Lin-Tai; Hsiao, Shu-Ying; Huang, Hsi-Ya

    2015-05-22

    In this study, an organic polymer monolithic columns, which were prepared via in situ polymerization of alkyl methacrylate-ester (AMA), divinylbenzene (DVB) and vinylbenzyl trimethylammonium chloride (VBTA, charged monomer), were developed as adsorbent for solid-phase microextraction (SPME). Different parameters affecting the extraction efficiency for nine (9) non-steroidal anti-inflammatory drugs (NSAIDs) such as the ratio of the stearyl methacrylate (SMA) to DVB monomer, column length, sample pH, extraction flow rate and desorption solvent were investigated to obtain the optimal SPME condition. Also, the permeability for each poly(AMA-DVB-VBTA) monolithic column was investigated by adding porogenic solvent (poly(ethylene glycol), PEG). Using the optimized condition, a series of AMA-based poly(AMA-DVB-VBTA) monolith columns were developed to determine the effect the extraction efficiency of NSAIDs by varying the alkyl chain length of the methacrylate ester (methyl-, butyl-, octyl-, or lauryl-methacrylate; (MMA, BMA, OMA, LMA)). Results showed that decreasing the AMA chain length increases the extraction efficiency of some NSAIDs (i.e. sulindac (sul), naproxen (nap), ketoprofen (ket) and indomethacin (idm)). Among the poly(AMA-DVB-VBTA) monolithic columns, poly(BMA-DVB-VBTA) showed a highly repeatable extraction efficiency for NSAIDs with recoveries ranging from 85.0 to 100.2% with relative standard deviation (RSD) less than 6.8% (n=3). The poly(BMA-DVB-VBTA) can also be reused for at least 50 times without any significant effect in extraction efficiency for NSAIDs. Finally, using the established conditions, the poly(BMA-DVB-VBTA) was used to extract trace-level NSAIDs (100μgL(-1)) in river water with good recoveries ranging from 75.8 to 90.8% (RSD<14.9%). PMID:25869799

  8. Increase of EPA-derived hydroxy, epoxy and dihydroxy fatty acid levels in human plasma after a single dose of long-chain omega-3 PUFA

    PubMed Central

    Schuchardt, Jan Philipp; Schneider, Inga; Willenberg, Ina; Yang, Jun; Hammock, Bruce D.; Hahn, Andreas; Schebb, Nils Helge

    2014-01-01

    Introduction Several supplementation studies with long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) describe an increase of EPA-derived hydroxy, epoxy and dihydroxy fatty acids in blood, while changes in levels of other LC n-3 and n-6 PUFA-derived oxylipins were minor. In order to investigate the kinetics of changes in oxylipin levels in response to LC n-3 PUFA ingestion, we conducted a single dose treatment study with healthy subjects. Subjects and methods In the present kinetic study, we compared patterns of hydroxy, epoxy and dihydroxy fatty acids in plasma of 6 healthy men before and after 6, 8, 24, and 48 h of fish oil (1008 mg EPA and 672 mg DHA) ingestion. Levels of EPA- as well as other LC PUFA-derived hydroxy, epoxy and dihydroxy fatty acids were analyzed in plasma by LC–MS. Additionally, levels of these oxylipins were compared with their parent PUFA levels in plasma phospholipids. Results All EPA-derived oxylipin levels were significantly increased 6 h after LC n-3 PUFA ingestion and gradually drop thereafter reaching the baseline levels about 48 h after treatment. The relative increase in EPA plasma phospholipid levels highly correlated with the increase of plasma EPA-derived oxylipin levels at different time points. In contrast, plasma levels of arachidonic acid- and DHA-derived oxylipins as well as parent PUFA levels in plasma phospholipids were hardly changed. Discussion and conclusions Our findings demonstrate that a single dose of LC n-3 PUFAs can rapidly induce a shift in the EPA oxylipin profile of healthy subjects within a few hours. Taking the high biological activity of the EPA-derived epoxy fatty acids into account, even short-term treatment with LC n-3 PUFAs may cause systemic effects, which warrant further investigation. PMID:24667634

  9. Base catalysis by alkali modified zeolites. III. Alkylation with methanol

    SciTech Connect

    Hathaway, P.E.; Davis, M.E. )

    1989-10-01

    Ion exchanged CsNaX and CsNaY, cesium acetate impregnated CsNaX (CsAce/CsNaX) and CsNaY (CsAce/CsNaY), and MgO have been reacted with isopropanol at 425 C and atmospheric pressure to assess their acid/base properties at a temperature consistent with that used in the side chain alkylation of toluene with methanol. The results suggest that the ability of the catalysts tested here to promote a base mediated reaction follow the order of MgO > CsAce/CsNaY > CsAce/CsNaX {approx equal} CsNaY > CsNaX. Selectivities to acetone measured at 4.73% conversion follow this order as well, ranging from 95.7% and 93.9% for MgO and CsAce/CsNaY, respectively, to 17.6% for the CsNaX. Thus, these catalysts can be grouped into two categories: (i) catalysts which vary in acid/base properties yet possess identical topology (e.g., the zeolites) and (ii) catalysts which vary in topology yet have similar acid/base properties (e.g., MgO and CsAce/CsNaY). These catalysts were compared using the side chain alkylation of toluene, ethane, methane, and acetone with methanol. For the impregnated zeolites, similar toluene conversions were observed. No formaldehyde was observed in the product stream of the impregnated Y zeolite. Both MgO and CsAce/CsNaY had similar methanol decomposition products; i.e., no formaldehyde and high CO formation, yet unlike CsAce/CsNaY no toluene conversion was observed for MgO. No conversion of ethane or methane was observed for either impregnated zeolite at 425 C.

  10. Synthesis of prostaglandins by conjugate addition and alkylation of a directed enolate ion. 4,5-allenyl prostaglandins

    SciTech Connect

    Patterson, J.W. )

    1990-09-28

    Over the previous two decades many elegant syntheses of prostaglandins, which in more sophisticated forms, allow the stereospecific introduction of the various asymmetric carbons have been accomplished. However, among these approaches the cuprate addition/enolate alkylation of suitable cyclopentenone {sup 2} stands out because of brevity and convergence. The recent reports by Noyori{sup 3} and Corey{sup 4} and their colleagues have reduced to practice the conversion of 4-alkoxycyclopentenones to prostaglandin E{sub 2} (PGE{sub 2}) by conjugate addition of an organocopper derivative of the lower side chain followed by alkylation of the resulting carbanion with methyl 7-halohept-2-enoate. The subject of this paper is application of the Tardella tin enolate alkylation developed by Noyori to the synthesis of 4, 5-allenic prostaglandins, a pharmacologically important class of compounds. The authors results demonstrate that the tandem alkylation of an enone precursor with a cuprate reagent followed by alkylation of the corresponding tin enolate with bromide reagent is a viable synthetic method for 4,5-didehydro-PGE{sub 2}. Because the optically active forms of 1 and the vinyl iodide precursor of the PGE{sub 2} lower side chain have been employed to produce a single enantiomer of PGE{sub 2}, the extension of the methodology described here to the synthesis of single enantiomers of 4a awaits only the preparation of the separate enantiomers of allene 14.

  11. Solid-state 13C NMR study of banana liquid crystals - 3: Alkyl-tail-group packing environments of an acute-angle bent-core molecule in the hexagonal columnar and cubic phases

    NASA Astrophysics Data System (ADS)

    Kurosu, Hiromichi; Endo, Yumi; Kimura, Saori; Hashimoto, Tomoko; Harada, Motoi; Lee, Eun-Woo; Sone, Masato; Watanabe, Junji; Kang, Sungmin

    2016-02-01

    Solid-state 13C nuclear magnetic resonance (NMR) measurements were performed on the hexagonal columnar and cubic phases of an acute-angle banana-shaped molecule, N(1,7)-S30. In the hexagonal columnar phase, three peaks appear at the NMR chemical shifts assigned to the internal methylene carbons of alkyl tails, indicating that the two alkyl tails have different packing structures, and one of the tails has two different conformations within a single molecule. Combined cross-polarization/magic-angle spinning and pulse saturation transfer/magic-angle spinning measurements show that one of the alkyl chains is located inside and the other is located outside the columnar structure. In the cubic phase, pulse saturation transfer/magic-angle spinning measurement shows that only one peak appears at the NMR chemical shifts assigned to the internal methylene carbons of alkyl tails, indicating that both of the alkyl chains are located outside the cubic structure.

  12. N-alkylated and O-alkylated regioisomers of 5-(hydroxyalkyl)pyrimidines: Synthesis and structural study

    NASA Astrophysics Data System (ADS)

    Meščić, Andrijana; Glavač, Danijel; Osmanović, Amar; Završnik, Davorka; Cetina, Mario; Makuc, Damjan; Plavec, Janez; Ametamey, Simon M.; Raić-Malić, Silvana

    2013-05-01

    Synthesis of novel 5-(2-hydroxyethyl) and 5-(3-hydroxypropyl) acyclic pyrimidine nucleosides is described. Introduction of penciclovir-like side chain in C-5 substituted pyrimidines occurred both at N-1 and O-2 position of pyrimidine moiety that was corroborated by correlation of signals in 2D HMBC spectra. Therefore, alkylation of 5-(acetoxyethyl)-4-methoxypyrimidin-2-one (2a) and 5-(acetoxypropyl)-4-methoxypyrimidin-2-one (2b) afforded mixture of N- and O-acyclic pyrimidine nucleosides in the ratio of 49: 45 (4a: 5a) and 41: 21 (4b: 5b). Structures of 5-(acetoxyalkyl)-4-methoxypyrimidin-2-ones, as the first examples of 4-methoxypyrimidin-2-ones, were unambiguously confirmed by single crystal X-ray diffraction analysis.

  13. Cytochrome P450 2C8 ω3-Long-Chain Polyunsaturated Fatty Acid Metabolites Increase Mouse Retinal Pathologic Neovascularization—Brief Report

    PubMed Central

    Shao, Zhuo; Fu, Zhongjie; Stahl, Andreas; Joyal, Jean-Sébastien; Hatton, Colman; Juan, Aimee; Hurst, Christian; Evans, Lucy; Cui, Zhenghao; Pei, Dorothy; Gong, Yan; Xu, Dan; Tian, Katherine; Bogardus, Hannah; Edin, Matthew L.; Lih, Fred; Sapieha, Przemyslaw; Chen, Jing; Panigrahy, Dipak; Hellstrom, Ann; Zeldin, Darryl C.; Smith, Lois E.H.

    2014-01-01

    Objective Regulation of angiogenesis is critical for many diseases. Specifically, pathological retinal neovascularization, a major cause of blindness, is suppressed with dietary ω3-long-chain polyunsaturated fatty acids (ω3LCPUFAs) through antiangiogenic metabolites of cyclooxygenase and lipoxygenase. Cytochrome P450 epoxygenases (CYP2C8) also metabolize LCPUFAs, producing bioactive epoxides, which are inactivated by soluble epoxide hydrolase (sEH) to transdihydrodiols. The effect of these enzymes and their metabolites on neovascularization is unknown. Approach and Results The mouse model of oxygen-induced retinopathy was used to investigate retinal neovascularization. We found that CYP2C (localized in wild-type monocytes/macrophages) is upregulated in oxygen-induced retinopathy, whereas sEH is suppressed, resulting in an increased retinal epoxide:diol ratio. With a ω3LCPUFA-enriched diet, retinal neovascularization increases in Tie2-driven human-CYP2C8–overexpressing mice (Tie2-CYP2C8-Tg), associated with increased plasma 19,20-epoxydocosapentaenoic acid and retinal epoxide:diol ratio. 19,20-Epoxydocosapentaenoic acids and the epoxide:diol ratio are decreased with overexpression of sEH (Tie2-sEH-Tg). Overexpression of CYP2C8 or sEH in mice does not change normal retinal vascular development compared with their wild-type littermate controls. The proangiogenic role in retina of CYP2C8 with both ω3LCPUFA and ω6LCPUFA and antiangiogenic role of sEH in ω3LCPUFA metabolism were corroborated in aortic ring assays. Conclusions Our results suggest that CYP2C ω3LCPUFA metabolites promote retinal pathological angiogenesis. CYP2C8 is part of a novel lipid metabolic pathway influencing retinal neovascularization. PMID:24458713

  14. Palladium-Catalyzed, Ring-Forming Aromatic C–H Alkylations with Unactivated Alkyl Halides

    PubMed Central

    Venning, Alexander R. O.; Bohan, Patrick T.; Alexanian, Erik J.

    2015-01-01

    A catalytic C–H alkylation using unactivated alkyl halides and a variety of arenes and heteroarenes is described. This ring-forming process is successful with a variety of unactivated primary and secondary alkyl halides, including those with β-hydrogens. In contrast to standard polar or radical cyclizations of aromatic systems, electronic activation of the substrate is not required. The mild, catalytic reaction conditions are highly functional group tolerant and facilitate access to a diverse range of synthetically and medicinally important carbocyclic and heterocyclic systems. PMID:25746442

  15. Enhancement of alkylation catalysts for improved supercritical fluid regeneration

    DOEpatents

    Ginosar, Daniel M.; Petkovic, Lucia

    2009-09-22

    A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

  16. Enhancement of alkylation catalysts for improved supercritical fluid regeneration

    DOEpatents

    Ginosar, Daniel M.; Petkovic, Lucia M.

    2010-12-28

    A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

  17. Polyethylene composites containing a phase change material having a C14 straight chain hydrocarbon

    DOEpatents

    Salyer, Ival O.

    1987-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyethylene matrix having a straight chain alkyl hydrocarbon incorporated therein, said polyethylene being crosslinked to such a degree that said polyethylene matrix is form stable and said polyethylene matrix is capable of absorbing at least 10% by weight of said straight chain alkyl hydrocarbon; the composite is useful in forming pellets or sheets having thermal energy storage characteristics.

  18. Density functional theory investigation of the alkylating strength of organoaluminum co-catalysts for Ziegler-Natta polymerization

    NASA Astrophysics Data System (ADS)

    Champagne, Benoît; Cavillot, Valérie; André, Jean-Marie; François, Philippe; Momtaz, Ardéchir

    The ability of the Et2Al-R co-catalyst series [with R = Et, Cl, O-Me, O-iPr, NH-Me, S-Me, and S-iPr] to alkylate titanum chloride has been evaluated at the B3LYP/6-31G* level of approximation. The impact of dimerization and complexation by Lewis bases on their alkylating strength has been tackled. It turns out that both the dimerization and the complexation reactions increase the exothermicity of the global alkylation process. Nevertheless, these reactions can also annihilate the alkylating strength of these co-catalysts due to the formation of highly stable species. In particular, we have found that (i) the alkylating strength of Et2Al-R co-catalysts with R = O-R' and NH-R' is weak due to the formation of very stable dimers; (ii) the alkylating strength of Et2Al-S-R' increases upon adding Lewis bases, whereas Lewis bases make Et3Al less alkylating; and (iii) Et2Al-Cl is less affected by the presence of Lewis bases.

  19. Increase in cardiac myosin heavy-chain (MyHC) alpha protein isoform in hibernating ground squirrels, with echocardiographic visualization of ventricular wall hypertrophy and prolonged contraction

    PubMed Central

    Nelson, O. Lynne; Rourke, Bryan C.

    2013-01-01

    myosin heavy-chain (MyHC) isoforms in a separate cohort of squirrels over 5 months, including time points before hibernation, during hibernation and just prior to emergence. Hibernating individuals were maintained in both a 4°C cold room and a 20°C warm room. Measured by SDS-PAGE, relative percentages of cardiac MyHC alpha were increased during hibernation, at both hibernacula temperatures. A potential increase in contractile speed, and power, from more abundant MyHC alpha may aid force generation at low temperature and at low heart rates. Unlike many models of cardiomyopathies where the alpha isoform is replaced by the beta isoform in order to reduce oxygen consumption, ground squirrels demonstrate a potential cardioprotective mechanism to maintain cardiac output during torpor. PMID:24072796

  20. C18-unsaturated branched-chain fatty acid isomers: characterization and physical properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iso-oleic acid is a mixture of C18-unsaturated branched-chain fatty acid isomers with a methyl group on various positions of the alkyl chain, which is the product of the skeletal isomerization reaction of oleic acid and is the intermediate used to make isostearic acid (C18-saturated branched-chain f...

  1. Effect of alkyl glycerophosphate on the activation of peroxisome proliferator-activated receptor gamma and glucose uptake in C2C12 cells

    SciTech Connect

    Tsukahara, Tamotsu; Haniu, Hisao; Matsuda, Yoshikazu

    2013-04-12

    Highlights: •Alkyl-LPA specifically interacts with PPARγ. •Alkyl-LPA treatments induces lipid accumulation in C2C12 cells. •Alkyl-LPA enhanced glucose uptake in C2C12 cells. •Alkyl-LPA-treated C2C12 cells express increased amounts of GLUT4 mRNA. •Alkyl-LPA is a novel therapeutic agent that can be used for the treatment of obesity and diabetes. -- Abstract: Studies on the effects of lipids on skeletal muscle cells rarely examine the effects of lysophospholipids. Through our recent studies, we identified select forms of phospholipids, such as alkyl-LPA, as ligands for the intracellular receptor peroxisome proliferator-activated receptor gamma (PPARγ). PPARγ is a nuclear hormone receptor implicated in many human diseases, including diabetes and obesity. We previously showed that alkyl-LPA is a specific agonist of PPARγ. However, the mechanism by which the alkyl-LPA–PPARγ axis affects skeletal muscle cells is poorly defined. Our objective in the present study was to determine whether alkyl-LPA and PPARγ activation promotes glucose uptake in skeletal muscle cells. Our findings indicate that PPARγ1 mRNA is more abundant than PPARγ2 mRNA in C2C12 cells. We showed that alkyl-LPA (3 μM) significantly activated PPARγ and increased intracellular glucose levels in skeletal muscle cells. We also showed that incubation of C2C12 cells with alkyl-LPA led to lipid accumulation in the cells. These findings suggest that alkyl-LPA activates PPARγ and stimulates glucose uptake in the absence of insulin in C2C12 cells. This may contribute to the plasma glucose-lowering effect in the treatment of insulin resistance.

  2. Engineering a Disulfide Bond in the Lid Hinge Region of Rhizopus chinensis Lipase: Increased Thermostability and Altered Acyl Chain Length Specificity

    PubMed Central

    Yu, Xiao-Wei; Tan, Nian-Jiang; Xiao, Rong; Xu, Yan

    2012-01-01

    The key to enzyme function is the maintenance of an appropriate balance between molecular stability and structural flexibility. The lid domain which is very important for “interfacial activation” is the most flexible part in the lipase structure. In this work, rational design was applied to explore the relationship between lid rigidity and lipase activity by introducing a disulfide bond in the hinge region of the lid, in the hope of improving the thermostability of R. chinensis lipase through stabilization of the lid domain without interfering with its catalytic performance. A disulfide bridge between F95C and F214C was introduced into the lipase from R. chinensis in the hinge region of the lid according to the prediction of the “Disulfide by Design” algorithm. The disulfide variant showed substantially improved thermostability with an eleven-fold increase in the t1/2 value at 60°C and a 7°C increase of Tm compared with the parent enzyme, probably contributed by the stabilization of the geometric structure of the lid region. The additional disulfide bond did not interfere with the catalytic rate (kcat) and the catalytic efficiency towards the short-chain fatty acid substrate, however, the catalytic efficiency of the disulfide variant towards pNPP decreased by 1.5-fold probably due to the block of the hydrophobic substrate channel by the disulfide bond. Furthermore, in the synthesis of fatty acid methyl esters, the maximum conversion rate by RCLCYS reached 95% which was 9% higher than that by RCL. This is the first report on improving the thermostability of the lipase from R. chinensis by introduction of a disulfide bond in the lid hinge region without compromising the catalytic rate. PMID:23056295

  3. Glycomacropeptide is a prebiotic that reduces Desulfovibrio bacteria, increases cecal short-chain fatty acids, and is anti-inflammatory in mice.

    PubMed

    Sawin, Emily A; De Wolfe, Travis J; Aktas, Busra; Stroup, Bridget M; Murali, Sangita G; Steele, James L; Ney, Denise M

    2015-10-01

    Glycomacropeptide (GMP) is a 64-amino acid (AA) glycophosphopeptide with application to the nutritional management of phenylketonuria (PKU), obesity, and inflammatory bowel disease (IBD). GMP is a putative prebiotic based on extensive glycosylation with sialic acid, galactose, and galactosamine. Our objective was to determine the prebiotic properties of GMP by characterizing cecal and fecal microbiota populations, short-chain fatty acids (SCFA), and immune responses. Weanling PKU (Pah(enu2)) and wild-type (WT) C57Bl/6 mice were fed isoenergetic AA, GMP, or casein diets for 8 wk. The cecal content and feces were collected for microbial DNA extraction to perform 16S microbiota analysis by Ion Torrent PGM sequencing. SCFA were determined by gas chromatography, plasma cytokines via a Bio-Plex Pro assay, and splenocyte T cell populations by flow cytometry. Changes in cecal and fecal microbiota are primarily diet dependent. The GMP diet resulted in a reduction from 30-35 to 7% in Proteobacteria, genera Desulfovibrio, in both WT and PKU mice with genotype-dependent changes in Bacteroidetes or Firmicutes. Cecal concentrations of the SCFA acetate, propionate, and butyrate were increased with GMP. The percentage of stimulated spleen cells producing interferon-γ (IFN-γ) was significantly reduced in mice fed GMP compared with casein. In summary, plasma concentrations of IFN-γ, TNF-α, IL-1β, and IL-2 were reduced in mice fed GMP. GMP is a prebiotic based on reduction in Desulfovibrio, increased SCFA, and lower indexes of inflammation compared with casein and AA diets in mice. Functional foods made with GMP may be beneficial in the management of PKU, obesity, and IBD. PMID:26251473

  4. Synthesis and Cytostatic Evaluation of 4-N-Alkanoyl and 4-N-Alkyl Gemcitabine Analogues

    PubMed Central

    Pulido, Jesse; Sobczak, Adam J.; Balzarini, Jan; Wnuk, Stanislaw F.

    2014-01-01

    Couplings of gemcitabine with the functionalized carboxylic acids (C9-C13) or reactions of 4-N-tosylgemcitabine with the corresponding alkyl amines afforded 4-N-alkanoyl and 4-N-alkyl gemcitabine derivatives. The analogues with a terminal hydroxyl group on the alkyl chain were efficiently fluorinated under conditions that are compatible with protocols for 18F labeling. The 4-N-alkanoylgemcitabines showed potent cytostatic activities in the low nM range against a panel of tumor cell lines while cytotoxicity of the 4-N-alkylgemcitabines were in the low μM range. The cytotoxicity for the 4-N-alkanoylgemcitabine analogues were reduced approximately by two orders of magnitude in the 2′-deoxycytidine kinase (dCK)-deficient CEM/dCK- cell line whereas cytotoxicity of the 4-N-alkylgemcitabines were only 2-5 times lower. None of the compounds acted as efficient substrates for cytosolic dCK, and therefore, the 4-N-alkanoyl analogues need to be converted first to gemcitabine to display a significant cytostatic potential, while 4-N-alkyl derivatives attain the modest activity without “measurable” conversion to gemcitabine. PMID:24341356

  5. Increased dimeric IgA-producing B cells in tonsils in IgA nephropathy determined by in situ hybridization for J chain mRNA.

    PubMed Central

    Harper, S J; Allen, A C; Béné, M C; Pringle, J H; Faure, G; Lauder, I; Feehally, J

    1995-01-01

    The origin of mesangial IgA deposits in IgA nephropathy (IgAN) remains obscure. A significant proportion of deposited immunoglobulin is dimeric (J chain-positive). Previous studies of J chain expression within lymphoid tissue in IgAN have utilized antibodies which other investigators have found to be non-specific. To address this problem, we have developed and in situ hybridization (ISH) method for the detection of J chain mRNA within IgA plasma cells. Tonsils from 12 patients with IgAN and 12 controls were studied using (i) non-isotopic ISH for J chain mRNA, and (ii) combined immunofluorescence (IF) and fluorescent ISH. J chain mRNA-positive cells were identified in germinal centres, and within the subepithelial and interfollicular zones. A greater number of J chain mRNA-positive cells were found in the germinal centres of patients (mean 57.7 +/- 4.6 cells/10(5) micron2) compared with controls (mean 36.9 +/- 3.5 cells/10(5) micron2) (P < 0.001). Combined IF and fluorescent ISH showed a greater proportion of J chain mRNA-positive interfollicular IgA cells in patient tonsils (32 +/- 3.4%) compared with controls (21 +/- 2.3%; P < 0.02). These results indicate a shift towards dimeric IgA production in the tonsils in IgAN. In addition, the finding of excess numbers of J chain-positive Iga-negative cells within germinal centres suggests that an abnormality may be present at the B cell differentiation stage before IgA switching. These results further highlight immune abnormalities within the tonsil as a central feature of abnormal polymeric IgA biology in this common form of glomerulonephritis. Images Fig. 1 Fig. 2 PMID:7664491

  6. The ejection anisotropy in the Coulomb explosion of some alkyl halide molecules under strong ps laser fields

    NASA Astrophysics Data System (ADS)

    Kaziannis, S.; Kosmidis, C.

    2009-01-01

    The ejection anisotropy of Coulomb explosion fragments released from alkyl halide molecules (C 2H 5X, 1-C 3H 7X and 1-C 4H 9X, where X = Br, Cl) under strong 35 ps laser irradiation is studied by means of time-of-flight mass spectrometry. By comparing the angular distributions widths of the halogen fragment ions originating from multiply charged molecular ions it is concluded that the ejection anisotropy presents a weak dependence on the mass of the halogen atom, observed especially in the case of ethyl halide molecules, while a stronger dependence is found on the size of the alkyl chain.

  7. 40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject...

  8. 40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject...

  9. 40 CFR 721.575 - Substituted alkyl halide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted alkyl halide. 721.575... Substances § 721.575 Substituted alkyl halide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as substituted alkyl halide (PMN P-83-1222)...

  10. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  11. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  12. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  13. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  14. 40 CFR 721.555 - Alkyl amino nitriles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Substances § 721.555 Alkyl amino nitriles (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as alkyl amino nitriles (PMNs P-96... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl amino nitriles (generic)....

  15. 40 CFR 721.3485 - Hydrofluorocarbon alkyl ether.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluorocarbon alkyl ether. 721... Substances § 721.3485 Hydrofluorocarbon alkyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a hydrofluorocarbon alkyl...

  16. 40 CFR 721.3485 - Hydrofluorocarbon alkyl ether.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluorocarbon alkyl ether. 721... Substances § 721.3485 Hydrofluorocarbon alkyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a hydrofluorocarbon alkyl...

  17. 40 CFR 721.10053 - Alkyl silane methacrylate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkyl silane methacrylate (generic... Specific Chemical Substances § 721.10053 Alkyl silane methacrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl...

  18. 40 CFR 721.10053 - Alkyl silane methacrylate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl silane methacrylate (generic... Specific Chemical Substances § 721.10053 Alkyl silane methacrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl...

  19. 40 CFR 721.10053 - Alkyl silane methacrylate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkyl silane methacrylate (generic... Specific Chemical Substances § 721.10053 Alkyl silane methacrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl...

  20. 40 CFR 721.10053 - Alkyl silane methacrylate (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl silane methacrylate (generic... Specific Chemical Substances § 721.10053 Alkyl silane methacrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl...

  1. 40 CFR 721.10053 - Alkyl silane methacrylate (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl silane methacrylate (generic... Specific Chemical Substances § 721.10053 Alkyl silane methacrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl...

  2. 40 CFR 721.555 - Alkyl amino nitriles (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Substances § 721.555 Alkyl amino nitriles (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as alkyl amino nitriles (PMNs P-96... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl amino nitriles (generic)....

  3. IONIC LIQUID-CATALYZED ALKYLATION OF ISOBUTANE WITH 2-BUTENE

    EPA Science Inventory

    A detailed study of the alkylation of isobutane with 2-butene in ionic liquid media has been conducted using 1-alkyl-3-methylimidazolium halides?aluminum chloride encompassing various alkyl groups (butyl-, hexyl-, and octyl-) and halides (Cl, Br, and I) on its cations and anions,...

  4. 40 CFR 721.1852 - Di-alkyl borane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Di-alkyl borane (generic). 721.1852... Substances § 721.1852 Di-alkyl borane (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as di-alkyl borane (PMN P-00-1087) is...

  5. 40 CFR 721.10087 - Substituted alkyl phosphine oxide (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted alkyl phosphine oxide... Specific Chemical Substances § 721.10087 Substituted alkyl phosphine oxide (generic). (a) Chemical... as substituted alkyl phosphine oxide (PMN P-06-332) is subject to reporting under this section...

  6. 40 CFR 721.10087 - Substituted alkyl phosphine oxide (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Substituted alkyl phosphine oxide... Specific Chemical Substances § 721.10087 Substituted alkyl phosphine oxide (generic). (a) Chemical... as substituted alkyl phosphine oxide (PMN P-06-332) is subject to reporting under this section...

  7. 40 CFR 721.9720 - Disubstituted alkyl triazines (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Disubstituted alkyl triazines (generic... Specific Chemical Substances § 721.9720 Disubstituted alkyl triazines (generic name). (a) Chemical... as disubstituted alkyl triazines (PMNs P-85-932 and P-85-933) are subject to reporting under...

  8. 40 CFR 721.10506 - Alkylated phenols (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkylated phenols (generic). 721.10506... Substances § 721.10506 Alkylated phenols (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as alkylated phenols (PMNs...

  9. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  10. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  11. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  12. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  13. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  14. 40 CFR 721.10506 - Alkylated phenols (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkylated phenols (generic). 721.10506... Substances § 721.10506 Alkylated phenols (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as alkylated phenols (PMNs...

  15. 40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327)...

  16. 40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject...

  17. 40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327)...

  18. 40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327)...

  19. 40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327)...

  20. 40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327)...

  1. 40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject...

  2. 40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject...

  3. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl ester (generic name). 721.2825... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkyl ester (PMN P-84-968) is subject to reporting under this...

  4. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl ester (generic name). 721.2825... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkyl ester (PMN P-84-968) is subject to reporting under this...

  5. 40 CFR 721.4136 - Alkyl heteropolycyclic-aniline (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkyl heteropolycyclic-aniline... Specific Chemical Substances § 721.4136 Alkyl heteropolycyclic-aniline (generic). (a) Chemical substance... alkyl heteropolycyclic-aniline (PMN P-00-0067) is subject to reporting under this section for...

  6. 40 CFR 721.4136 - Alkyl heteropolycyclic-aniline (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl heteropolycyclic-aniline... Specific Chemical Substances § 721.4136 Alkyl heteropolycyclic-aniline (generic). (a) Chemical substance... alkyl heteropolycyclic-aniline (PMN P-00-0067) is subject to reporting under this section for...

  7. 40 CFR 721.4136 - Alkyl heteropolycyclic-aniline (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkyl heteropolycyclic-aniline... Specific Chemical Substances § 721.4136 Alkyl heteropolycyclic-aniline (generic). (a) Chemical substance... alkyl heteropolycyclic-aniline (PMN P-00-0067) is subject to reporting under this section for...

  8. 40 CFR 721.4136 - Alkyl heteropolycyclic-aniline (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl heteropolycyclic-aniline... Specific Chemical Substances § 721.4136 Alkyl heteropolycyclic-aniline (generic). (a) Chemical substance... alkyl heteropolycyclic-aniline (PMN P-00-0067) is subject to reporting under this section for...

  9. 40 CFR 721.4136 - Alkyl heteropolycyclic-aniline (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl heteropolycyclic-aniline... Specific Chemical Substances § 721.4136 Alkyl heteropolycyclic-aniline (generic). (a) Chemical substance... alkyl heteropolycyclic-aniline (PMN P-00-0067) is subject to reporting under this section for...

  10. Synthesis and characterization of chitosan alkyl urea.

    PubMed

    Wang, Jing; Jiang, Ji-Zhou; Chen, Wei; Bai, Zheng-Wu

    2016-07-10

    Chitosan is a versatile material employed for various purposes in many fields including the development of chiral stationary phases for enantioseparation. Chitosan alkyl urea is a kind of intermediate used to prepare enantioseparation materials. In order to synthesize the intermediates, in the present work, a new way to prepare chitosan alkyl urea has been established: chitosan was first reacted with methyl chloroformate yielding N-methoxyformylated chitosan, which was then converted to chitosan alkyl urea through amine-ester exchange reaction. With a large excess of methyl chloroformate and primary amine of low stereohindrance, the amino group in chitosan could be almost completely converted to ureido group. The as-prepared chitosan alkyl urea derivatives were characterized by IR, (1)H NMR, (13)C NMR,(1)H-(1)H COSY and (1)H-(13)C HSQC NMR spectra. The chemical shifts of hydrogen and carbon atoms of glucose unit were assigned. It was found that the degree of substitution was obviously lower if cyclopropyl amine, aniline, tert-butyl amine and diethyl amine were used as reactants for the amine-ester exchange reaction. The reason was explained with the aid of theoretical calculations. PMID:27106154

  11. Separate olefin processing in sulfuric acid alkylation

    SciTech Connect

    Imhoff, S.A.; Graves, D.C.

    1995-09-01

    This paper will discuss the effects of alkylating propylene, butylenes and amylenes together and suggest alternative processing schemes which will minimize the negative synergies, improve octane and/or minimize acid consumption. The first option will show the impact of segregating the propylene and amylenes. In the second option, the benefit of alkylating the individual olefins at their optimal acid strengths will be presented. Additionally, each olefin`s optimal reaction conditions will be examined. Unfortunately, many refiners may not have the existing flexibility to take advantage of separate olefin processing. First, the majority of the propylene, butylenes and amylenes must be separate upon entry to the alkylation unit. If the olefins cannot be segregated upstream, separate olefin processing will not be as beneficial. If this is the case, then the benefits of separate olefin processing will have to be weighed versus the capital and energy costs required to separate them. In addition, small units may not have sufficient numbers of Contactors and settlers to achieve adequate segregation. Later in this paper, the modifications required in the alkylation unit for separate olefin processing will be discussed.

  12. Reactions in water: alkyl nitrile coupling reactions using Fenton's reagent.

    PubMed

    Keller, Christopher L; Dalessandro, James D; Hotz, Richard P; Pinhas, Allan R

    2008-05-01

    The coupling reaction of water-soluble alkyl nitriles using Fenton's reagent (Fe(II) and H2O2) is described. The best metal for the reaction is iron(II), and the greatest yields are obtained when the concentration of the metal is kept low. Hydrogen-atom abstraction is selective, preferentially producing the radical alpha to the nitrile. In order to increase the production of dinitrile, in situ reduction of iron(III) to iron(II), using a variety of reducing agents, was investigated. PMID:18363368

  13. Synthesis and pharmacological evaluation of (nitrooxy)alkyl apovincaminates.

    PubMed

    Kawashima, Y; Ikemoto, T; Horiguchi, A; Hayashi, M; Matsumoto, K; Kawarasaki, K; Yamazaki, R; Okuyama, S; Hatayama, K

    1993-04-01

    A series of (nitrooxy)alkyl apovincaminates has been synthesized and evaluated for their effects on vertebral and femoral blood flow. These derivatives were prepared from apovincaminic acid (4). In cerebral circulation, compound 5 (0.03-1.0 mg/kg iv) caused a dose-dependent increase in cerebral blood flow (CerBF) without affecting the blood pressure. It was more potent than vinpocetine (2). The structures of 2 and 5, determined by X-ray crystallography, showed differences in the electrostatic potential image and in the conformation of the ethyl group at the 16-position. PMID:8464035

  14. Characterization and quantitation of mixtures of alkyl ether sulfates and carboxylic acids by capillary electrophoresis with indirect photometric detection.

    PubMed

    Bernabé-Zafón, Virginia; Ortega-Gadea, Silvia; Simó-Alfonso, Ernesto F; Ramis-Ramos, Guillermo

    2003-08-01

    The separation, characterization, and determination of mixtures of alkyl ether sulfates (AES) and fatty acids (C10-C16) in background electrolytes (BGEs) containing acetonitrile (ACN)-water mixtures is addressed. Due to inhibition of the ionization of the carboxylate groups, the migration time and the resolution between the fatty acids decreased when the water content of the BGE was reduced, but efficiency and resolution between the AES oligomers improved. The migration times increased and resolution improved by substituting 5% ACN by an equivalent amount of dioxane. A complete separation of the two surfactant classes, up to the AES oligomers with 8 ethylene oxide units (EOs) with respect to C10, with excellent resolution between the AES oligomers, while preserving a satisfactory resolution between the fatty acids, was achieved with a BGE containing 5 mM trimethoxybenzoic acid, 7 mM dipentylamine, 85% ACN, 5% dioxane, and 10% water. The two surfactant classes were increasingly resolved by further reducing the water content of the BGE. Thus, C2 (acetate) was resolved from the AES oligomers up to 7 EOs using 90% ACN and 5% dioxane, but the resolution between the heavier fatty acids was poor with this BGE. Identification of the AES oligomers was eased by the excellent regularity of the successive migration times; thus, within each AES subclass or series of oligomers with the same number of carbon atoms in the alkyl chain, the migration times decreased following a mild curve as the number of EOs increased. The way how the data obtained by indirect photometry (corrected peak areas that are proportional to the molar concentrations) should be managed to avoid systematic error when the calibration curve is constructed using an AES standard with an oligomer distribution different from that of the samples is discussed and equations are given. Decyl sulfate was successfully used as internal standard. The detection limits (S/N = 3) were of ca. 2 microM for individual AES

  15. ATM regulates 3-Methylpurine-DNA glycosylase and promotes therapeutic resistance to alkylating agents

    PubMed Central

    Agnihotri, Sameer; Burrell, Kelly; Buczkowicz, Pawel; Remke, Marc; Golbourn, Brian; Chornenkyy, Yevgen; Gajadhar, Aaron; Fernandez, Nestor A.; Clarke, Ian D.; Barszczyk, Mark S.; Pajovic, Sanja; Ternamian, Christian; Head, Renee; Sabha, Nesrin; Sobol, Robert W.; Taylor, Michael D; Rutka, James T.; Jones, Chris; Dirks, Peter B.; Zadeh, Gelareh; Hawkins, Cynthia

    2014-01-01

    Alkylating agents are a frontline therapy for the treatment of several aggressive cancers including pediatric glioblastoma, a lethal tumor in children. Unfortunately, many tumors are resistant to this therapy. We sought to identify ways of sensitizing tumor cells to alkylating agents while leaving normal cells unharmed; increasing therapeutic response while minimizing toxicity. Using a siRNA screen targeting over 240 DNA damage response genes, we identified novel sensitizers to alkylating agents. In particular the base excision repair (BER) pathway, including 3-methylpurine-DNA glycosylase (MPG), as well as ataxia telangiectasia mutated (ATM) were identified in our screen. Interestingly, we identified MPG as a direct novel substrate of ATM. ATM-mediated phosphorylation of MPG was required for enhanced MPG function. Importantly, combined inhibition or loss of MPG and ATM resulted in increased alkylating agent-induced cytotoxicity in vitro and prolonged survival in vivo. The discovery of the ATM-MPG axis will lead to improved treatment of alkylating agent-resistant tumors. PMID:25100205

  16. Biodegradation of fluorinated alkyl substances.

    PubMed

    Frömel, Tobias; Knepper, Thomas P

    2010-01-01

    The incorporation of fluorine into organic molecules entails both positive and adverse effects. Although fluorine imparts positive and unique properties such as water-and oil-repellency and chemical stability, adverse effects often pervade members of this compound class. A striking property of long perfluoroalkyl chains is their very pronounced environmental persistence. The present review is the first one designed to summarize recent accomplishments in the field of biodegradation of fluorine-containing surfactants, their metabolites, and structural analogs. The pronounced scientific and public interest in these chemicals has given impetus to undertake numerous degradation studies to assess the sources and origins of different fluorinated analog chemical known to exist in the environment. It was shown that biodegradation plays an important role in understanding how fluorinated substances reach the environment and, once they do, what their fate is. Today, PFOS and PFOA are ubiquitously detected as environmental contaminants. Their prominence as contaminants is mainly due to their extreme persistence, which is linked to their perfluoroalkyl chain length. It appears that desulfonation of a highly fluorinated surfactants can be achieved if an α-situated H atom, in relation to the sulfonate group, is present, at least under sulfur-limiting conditions. Molecules that are less heavily fluorinated can show very complex metabolic behavior, as is the case for fluorotelomer alcohols. These compounds are degraded via different but simultaneous pathways, which produce different stable metabolites, one of which is the respective perfluoroalkanoate (8:2-FTOH is transformed to PFOA). Preliminary screening tests indicate that fluorinated functional groups, such as the trifluoromethoxy group and the p-(trifluoromethyl)phenoxy group, may be useful implementations in novel, environmentally benign fluorosurfactants. More specifically, trifluoromethoxy groups constitute a substitute

  17. Synthesis, docking study and relaxant effect of 2-alkyl and 2-naphthylchromones on rat aorta and guinea-pig trachea through phosphodiesterase inhibition.

    PubMed

    Rodríguez-Ramos, Fernando; Navarrete, Andrés; González-Andrade, Martín; Alarcón, Carlos; Aguilera-Cruz, Alejandro; Reyes-Ramírez, Adelfo

    2013-10-01

    Chromone (4), which form the base structure of various flavonoids isolated as natural products, is capable of relaxing smooth muscle. This is relevant to the treatment of high blood pressure, asthma and chronic obstructive pulmonary disease. The former disorder involves the contraction of vascular smooth muscle (VSM), and the latter two bronchoconstriction of airway smooth muscle (ASM). One of the principal mechanisms by which flavonoids relax muscle tissue is the inhibition of phosphodiesterases (PDEs), present in both VSM and ASM. Therefore, a study was designed to analyze the structure-activity relationship of chromone derivatives in vaso- and bronchorelaxation through the inhibition of PDE. Docking studies showed that these chromones bind at the catalytic site of PDEs. Consequently, we synthesized analogs of chromones substituted at position C-2 with alkyl and naphthyl groups. These compounds were synthesized from 2-hydroxyacetophenone and acyl chlorides in the presence of DBU and pyridine, modifying the methodology reported for the synthesis of 3-acylchromones by changing the reaction temperature from 80 to 30°C and using methylene chloride as solvent, yielding the corresponding phenolic esters 10a-10h. These compounds were cyclized with an equivalent of DBU, pyridine as solvent, and heated at reflux temperature, yielding the chromones 11a-11h. Evaluation of the vasorelaxant effect of 4, 11a-11h on rat aorta demonstrated that potency decreases with branched alkyl groups. Whereas the EC50 of compound 11d (substituted by an n-hexyl group) was 8.64±0.39 μM, that of 11f (substituted by an isobutyl group) was 14.58±0.64 μM. Contrarily, the effectiveness of the compound is directly proportional to the length of the alkyl chain, as evidenced by the increase in maximal effect of compound 11c versus 11d (66% versus 100%) and 11e versus 11f (60% versus 96%). With an aromatic group like naphthyl as the C-2 substituent, the effectiveness was only 43%. All compounds

  18. Mass Balance of Perfluorinated Alkyl Acids in a Pristine Boreal Catchment.

    PubMed

    Filipovic, Marko; Laudon, Hjalmar; McLachlan, Michael S; Berger, Urs

    2015-10-20

    Mass balances of ten individual perfluorinated alkyl acids (PFAAs) in two nested pristine catchments in Northern Sweden with different sizes and hydrological functions were assembled for 2011-2012. Concentrations of PFAAs in rain and snowmelt, as well as in streamwater at the outlet of the two watersheds were measured and used to calculate PFAA atmospheric inputs to and riverine outputs from the catchments. The results generally showed a great excess of PFAA inputs for both catchments over the whole study year. However, during the spring flood period, the inputs and outputs were within a factor of 2 for several PFAAs and the streamwater showed PFAA patterns resembling the patterns in rain (as opposed to snowmelt), suggesting that snowmelt water infiltrating the ground had displaced water from the previous summer. Comparison of PFAA mass balances between the two catchments further suggested that atmospheric inputs of short-chain (replacement) perfluoroalkyl carboxylic acids had increased in the years before sampling, while inputs of the legacy perfluorooctane sulfonic acid had decreased. Overall, the mass balances indicate that a considerable portion of the PFAAs deposited from the atmosphere are stored in soil and may be released to surface and marine water environments in the future. PMID:26390224

  19. What Is the Most Effective Way of Increasing the Bioavailability of Dietary Long Chain Omega-3 Fatty Acids—Daily vs. Weekly Administration of Fish Oil?

    PubMed Central

    Ghasemifard, Samaneh; Sinclair, Andrew J.; Kaur, Gunveen; Lewandowski, Paul; Turchini, Giovanni M.

    2015-01-01

    The recommendations on the intake of long chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFA) vary from eating oily fish (“once to twice per week”) to consuming specified daily amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (“250–500 mg per day”). It is not known if there is a difference in the uptake/bioavailability between regular daily consumption of supplementsvs. consuming fish once or twice per week. In this study, the bioavailability of a daily dose of n-3 LC-PUFA (Constant treatment), representing supplements, vs. a large weekly dose of n-3 LC-PUFA (Spike treatment), representing consuming once or twice per week, was assessed. Six-week old healthy male Sprague-Dawley rats were fed either a Constant treatment, a Spike treatment or Control treatment (no n-3 LC-PUFA), for six weeks. The whole body, tissues and faeces were analysed for fatty acid content. The results showed that the major metabolic fate of the n-3 LC-PUFA (EPA+docosapentaenoic acid (DPA) + DHA) was towards catabolism (β-oxidation) accounting for over 70% of total dietary intake, whereas deposition accounted less than 25% of total dietary intake. It was found that significantly more n-3 LC-PUFA were β-oxidised when originating from the Constant treatment (84% of dose), compared with the Spike treatment (75% of dose). Conversely, it was found that significantly more n-3 LC-PUFA were deposited when originating from the Spike treatment (23% of dose), than from the Constant treatment (15% of dose). These unexpected findings show that a large dose of n-3 LC-PUFA once per week is more effective in increasing whole body n-3 LC-PUFA content in rats compared with a smaller dose delivered daily. PMID:26184297

  20. Measuring the toxicity of alkyl-phenanthrenes to early life stages of medaka (Oryzias latipes) using partition-controlled delivery.

    PubMed

    Turcotte, Dominique; Akhtar, Parveen; Bowerman, Michelle; Kiparissis, Yiannis; Brown, R Stephen; Hodson, Peter V

    2011-02-01

    Alkyl-phenanthrenes are a class of compounds present in crude oil and toxic to developing fish. Most research on alkyl-phenanthrenes has focused on retene (7-isopropyl-1-methyl-phenanthrene), but little is known about the chronic toxicity of related congeners to the early life stages of fish. This project is the first to describe the chronic toxicity of a series of alkyl-phenanthrenes to the embryos of Japanese medaka (Oryzias latipes) using the partition-controlled delivery (PCD) method of exposure and is the first to establish a relationship between toxicity of alkyl-phenanthrenes and log P. With PCD, test concentrations were maintained by equilibrium partitioning of test chemicals from polydimethylsiloxane (PDMS) films containing various concentrations of C1 to C4 phenanthrenes. Log film:solution partition constants (log K(fs)) and aqueous solubility limits were determined for each alkyl-phenanthrene. The prevalence of abnormalities in fish embryos increased in an exposure-dependent manner, with median effective concentration (EC50) values lower than experimental solubility limits of the compounds, and typical of environmental concentrations. Alkyl-phenanthrenes were more toxic to medaka embryos than unsubstituted phenanthrene, with effects resembling those of dioxin and indicating a specific receptor-based mechanism of toxicity. These results extend conclusions for the Exxon Valdez oil spill, suggest a specific mechanism of toxicity for alkyl-phenanthrenes, and provide a model for assessing the risks of mixture toxicity. PMID:21072839

  1. Fluorinated alkyl substances and technical mixtures used in food paper-packaging exhibit endocrine-related activity in vitro.

    PubMed

    Rosenmai, A K; Taxvig, C; Svingen, T; Trier, X; van Vugt-Lussenburg, B M A; Pedersen, M; Lesné, L; Jégou, B; Vinggaard, A M

    2016-07-01

    Migration of chemicals from packaging materials to foods may lead to human exposure. Polyfluoroalkyl substances (PFAS) can be used in technical mixtures (TMs) for use in food packaging of paper and board, and PFAS have been detected in human serum and umbilical cord blood. The specific structures of the PFAS in TMs are often unknown, but polyfluorinated alkyl phosphate esters (PAPs) have been characterized in TMs, food packaging, and in food. PAPs can be metabolized into fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylic acids (PFCAs). Some PFAS have endocrine activities, highlighting the need to investigate these effects. Herein, we studied the endocrine activity of less characterized PFAS, including short-chain PFCAs and FTOHs, PAPs, and TMs of unknown chemical composition. Long-chain PFCAs were also included. We applied seven assays covering effects on estrogen, glucocorticoid, androgen, and peroxisome proliferator-activated receptor (PPAR) activity, as well as steroidogenesis in vitro and ex vivo. In general, PAPs, FTOHs, TMs, and long-chain PFCAs showed estrogenic activity through receptor activation and/or increasing 17β-estradiol levels. Furthermore, short- and long-chain PFCAs activated PPARα and PPARγ. Collectively, this means that (i) PAPs, FTOHs, and PFCAs exhibit endocrine activity through distinct and sometimes different mechanisms, (ii) two out of three tested TMs exhibited estrogenic activity, and (iii) short-chain FTOHs showed estrogenic activity and short-chain PFCAs generally activate both PPARα and PPARγ with similar potency and efficacy as long-chain PFCAs. In conclusion, several new and divergent toxicological targets were identified for different groups of PFAS. PMID:27152447

  2. Efficient Syntheses of Vitamin K Chain-Shortened Acid Metabolites

    PubMed Central

    Teitelbaum, Aaron M.; Scian, Michele; Nelson, Wendel L.; Rettie, Allan E.

    2015-01-01

    Vitamin K sequentially undergoes ω-oxidation followed by successive rounds of β-oxidation to ultimately produce two chain-shortened carboxylic acid metabolites, vitamin K acid 1 and vitamin K acid 2. Two facile syntheses of these acid metabolites are described, each starting from commercially available menadione-cyclopentadiene adduct 3. Vitamin K acid 1 was synthesized in five steps via alkylation with a geranyl halide followed by subsequent oxidation reactions, while fully retaining the trans configuration of the side chain 2’,3’-double bond. Vitamin K acid 2 was synthesized in 5 steps from 3 via alkylation with dimethylallyl chloride and subsequent oxidation reactions. PMID:27003951

  3. Dichloromethyl alkyl ethers and sulfides in the Reformatskii reaction

    SciTech Connect

    Lapkin, I.I.; Fotin, V.V.

    1986-09-10

    A study was carried out on the reaction of dichloromethyl alkyl ethers and sulfides with ..cap alpha..-brominated esters in the presence of zinc resulting in the formation of either ..cap alpha..-alkyl-..beta..-alkoxyacrylates (or ..cap alpha..-alkyl-..beta..-alkylthioacrylates) or ..cap alpha..,..cap alpha..,..cap alpha..',..cap alpha..'-tetramethyl-..beta..-alkoxyglutaric acid (or ..cap alpha..,..cap alpha..,..cap alpha..',..cap alpha..'-tetramethyl-..beta..-alkylthioglutaric acid) depending on the structure of the starting bromoester. PMR and IR spectroscopy indicates the geometry of the ..cap alpha..-alkyl-..beta..-alkoxyacrylates and ..cap alpha..-alkyl-..beta..-alkylthioacrylates.

  4. Molecular dynamics simulations of alkyl substituted nanographene crystals

    NASA Astrophysics Data System (ADS)

    Ziogos, Orestis George; Theodorou, Doros Nicolas

    2015-09-01

    Discotic polyaromatic molecules, similar to nanometric graphene flakes, constitute an interesting class of materials for organic electronic applications. Grafting flexible side chains around the periphery of such molecules enhances their processability and gives rise to diverse behaviours, such as the manifestation of liquid-crystalline character and anisotropic mechanical response. In this work, we examine by means of molecular dynamics simulations the properties of molecular crystals comprised of alkyl-substituted hexa-peri-hexabenzocoronene mesogens. Pristine and mono-substituted systems by hydrogen or iodine atoms are modelled, with variable side chain length. A general structural and mechanical robustness to peripheral substitution is reported, with the mesogens forming tightly packed molecular wires even at elevated temperature and pressure. In their discotic ordering, the molecules present relatively low translational mobility, a beneficial phenomenon for charge transport. A thermotropic dependence of the mechanical response is identified, with the systems behaving differently in their room-temperature crystalline phase and in their liquid-crystalline phase at elevated temperatures. The melting process is also examined, elucidating an initial negative expansion along a high symmetry direction and the existence of a metastable state, before falling into the final liquid-crystalline state. Dedicated to Professor Jean-Pierre Hansen, with deepest appreciation of his outstanding contributions to liquid and soft matter theory.

  5. Swallow-tailed alkyl and linear alkoxy-substituted dibenzocoronene tetracarboxdiimide derivatives: synthesis, photophysical properties, and thermotropic behaviors.

    PubMed

    Yang, Tengzhou; Pu, Jialing; Zhang, Jun; Wang, Wenguang

    2013-05-17

    A series of dibenzocoronene tetracarboxdiimide derivatives decorated with alkyl swallow-tail and alkoxy moieties were synthesized, and their structures were characterized. 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an effective oxidant was first used in the benzannulation of perylene diimides with the almost quantitative yield. The thermotropic behavior was investigated using differential scanning calorimetry (DSC) and polarization optical microscopy (POM). The introduction of alkyl swallow-tail and alkoxy substituents facilitates thermotropic liquid crystalline behavior. The branching site of alkyl swallow-tail units at the α position and the longer alkoxy chains played a similar role in lowering the mesophase transition as well as isotropization transition temperatures. The UV-vis absorption spectra of all compounds appeared as absorption in 425-600 nm region, and POM images of certain compounds exhibited characteristic columnar hexagonal (Col(h)) packing and readily self-assembled into a homeotropic alignment toward the substrate. PMID:23600443

  6. Modification of epoxy resin, silicon and glass surfaces with alkyl- or fluoroalkylsilanes for hydrophobic properties

    NASA Astrophysics Data System (ADS)

    Marczak, Jacek; Kargol, Marta; Psarski, Maciej; Celichowski, Grzegorz

    2016-09-01

    Preparation of superhydrophobic materials inspired by nature has attracted a great scientific interest in recent decades. Some of these materials have hierarchical lotus-like structures, i.e. micro- and nano-objects coated by hydrophobic compounds. A major challenge of applying the superhydrophobic surfaces for the self-cleaning coatings preparation is their improved efficiency in varying atmospheric conditions, e.g. UV light. The objective of this research work was to investigate the effect of the different chemical structure and the surface free energy on the hydrophobic and tribological properties of the alkylsilanes and fluoroalkylsilanes deposited on silicon wafers, glass slides and epoxy resin. Tribological and hydrophobic properties of the modified surfaces were correlated with their chemical structures. Chemical structures of the deposited materials were examined by using Fourier transform infrared (FT-IR) spectroscopy and hydrophobic properties were investigated by water contact angle (WCA) and surface free energy (SFE) measurements. The modified surfaces exhibited water contact angles of above 100° for the selected modifiers. It was noticed that the replacement of hydrogen atoms by fluorine atoms in alkyl chain caused an increase in the water contact angle values and a decrease in friction coefficients. The obtained results showed that the carbon chain length of a modifier and its chemical structure can strongly affect the hydrophobic and tribological properties of the modified surfaces. The highest values of WCA, lowest values of SFE and coefficient of friction were obtained for samples covered by fluorinated compounds. Moreover, some preliminary aging test was performed to give an insight into the effectiveness of deposited alkylsilanes and fluoroalkylsilanes coatings. After accelerated UV exposure, no significant changes in the chemical structure, hydrophobic and tribological properties of the modified surfaces were noticed. The samples degradation

  7. Retention behavior of alkyl-substituted polycyclic aromatic sulfur heterocycles in reversed-phase liquid chromatography.

    PubMed

    Wilson, Walter B; Sander, Lane C; de Alda, Miren Lopez; Lee, Milton L; Wise, Stephen A

    2016-08-26

    Retention indices for 79 alkyl-substituted polycyclic aromatic sulfur heterocycles (PASHs) were determined by using reversed-phase liquid chromatography (LC) on a monomeric and polymeric octadecylsilane (C18) stationary phase. Molecular shape parameters [length, breadth, thickness (T), and length-to-breadth ratio (L/B)] were calculated for all the compounds studied. Based on separations of isomeric methylated polycyclic aromatic hydrocarbons on polymeric C18 phases, alkyl-substituted PASHs are expected to elute based on increasing L/B ratios. However, the correlation coefficients had a wide range of values from r=0.43 to r=0.93. Several structural features besides L/B ratios were identified to play an important role in the separation mechanism of PASHs on polymeric C18 phases. First, the location of the sulfur atom in a bay-like-region results in alkylated-PASHs being more retentive than non-bay-like-region alkylated-PASHs, and they elute later than expected based on L/B value. Second, the placement of the alkyl group in the k region of the structure resulted in a later elution than predicted by L/B. Third, highly nonplanar methyl-PASHs (i.e., 1-Me and 11-MeBbN12T) elute prior to the parent PASH (BbN12T). PMID:27477517

  8. Ultra-bright alkylated graphene quantum dots

    NASA Astrophysics Data System (ADS)

    Feng, Lan; Tang, Xing-Yan; Zhong, Yun-Xin; Liu, Yue-Wen; Song, Xue-Huan; Deng, Shun-Liu; Xie, Su-Yuan; Yan, Jia-Wei; Zheng, Lan-Sun

    2014-10-01

    Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The photocatalytic rate is ca. 5.9 times higher than that of pure P25, indicating that AGQDs could harness the visible spectrum of sunlight for energy conversion or environmental therapy.Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The

  9. Gushing metal chain

    NASA Astrophysics Data System (ADS)

    Belyaev, Alexander; Sukhanov, Alexander; Tsvetkov, Alexander

    2016-03-01

    This article addresses the problem in which a chain falls from a glass from some height. This phenomenon demonstrates a paradoxical rise of the chain over the glass. To explain this effect, an initial hypothesis and an appropriate theory are proposed for calculating the steady fall parameters of the chain. For this purpose, the modified Cayley's problem of falling chain given its rise due to the centrifugal force of upward inertia is solved. Results show that the lift caused by an increase in linear density at the part of chain where it is being bent (the upper part) is due to the convergence of the chain balls to one another. The experiments confirm the obtained estimates of the lifting chain.

  10. Sophorolipid-induced dimpling and increased porosity in solvent-cast short-chain polyhydroxyalkanoate films: impact on thermo-mechanical properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sophorolipids (SL; microbial glycolipids) were used as additives in solvent-cast short-chain polyhydroxyalkanoate (sc-PHA) films to enhance surface roughness and porosity. Poly-3-hydroxybutyrate (PHB), poly-(6%)-3-hydroxybutyrate-co-(94%)-3-hydroxyvalerate (PHB/V), and poly-(90%)-3-hydroxybutyrate-c...

  11. Mesoporous organosilicas functionalized by alkyl groups: Synthesis, structure and adsorption properties

    NASA Astrophysics Data System (ADS)

    Barczak, M.; Dąbrowski, A.; Iwan, M.; Rzączyńska, Z.

    2009-01-01

    Mesoporous organosilicas were synthesized by sol-gel co-condensation of tetraethoxysilane and appropriate alkoxysilanes in the presence of Pluronic P123 surfactant. Hexyl, dodecyl, and octadecyl alkyl chains have been incorporated into mesopores by such co-condensation. Obtained materials were characterized by X-ray diffraction, FTIR spectroscopy, nitrogen adsorption measurements and thermogravimetry. Two resulted materials have highly ordered SBA-15 structure (p6m symmetry), other two are less ordered. All the materials exhibit well-developed porous structure (surface areas 500 to 830m2/g, pore volumes 0.65-1.32 cm3/g) and a high content of organic pendant groups introduced during co-condensation. All materials are thermally stable to 180°C, after that thermal decomposition of alkyl pendant groups starts.

  12. Stopped-flow kinetic studies of sphere-to-rod transitions of sodium alkyl sulfate micelles induced by hydrotropic salt.

    PubMed

    Zhang, Jingyan; Ge, Zhishen; Jiang, Xiaoze; Hassan, P A; Liu, Shiyong

    2007-12-15

    The kinetics and mechanism of sphere-to-rod transitions of sodium alkyl sulfate micelles induced by hydrotropic salt, p-toluidine hydrochloride (PTHC), were investigated by stopped-flow with light scattering detection. Spherical sodium dodecyl sulfate (SDS) micelles transform into short ellipsoidal shapes at low salt concentrations ([PTHC]/[SDS], chi(PTHC)=0.3 and 0.4). Upon stopped-flow mixing aqueous solutions of spherical SDS micelles with PTHC, the scattered light intensity gradually increases with time. Single exponential fitting of the dynamic traces leads to characteristic relaxation time, tau(g), for the growth process from spherical to ellipsoidal micelles, and it increases with increasing SDS concentrations. This suggests that ellipsoidal micelles might be produced by successive insertion of unimers into spherical micelles, similar to the case of formation of spherical micelles as suggested by Aniansson-Wall (A-W) theory. At chi(PTHC) > or = 0.5, rod-like micelles with much higher axial ratio form. The scattered light intensity exhibits an initially abrupt increase and then levels off. The dynamic curves can be well fitted with single exponential functions, and the obtained tau(g) decreases with increasing SDS concentration. Thus, the growth from spherical to rod-like micelles might proceed via fusion of spherical micelles, in agreement with mechanism proposed by Ikeda et al. At chi(PTHC)=0.3 and 0.6, the apparent activation energies obtained from temperature dependent kinetic studies for the micellar growth are 40.4 and 3.6 kJ/mol, respectively. The large differences between activation energies for the growth from spherical to ellipsoidal micelles at low chi(PTHC) and the sphere-to-rod transition at high chi(PTHC) further indicate that they should follow different mechanisms. Moreover, the sphere-to-rod transition kinetics of sodium alkyl sulfate with varying hydrophobic chain lengths (n=10, 12, 14, and 16) are also studied. The longer the carbon chain

  13. Intermolecular Photocatalyzed Heck-like Coupling of Unactivated Alkyl Bromides by a Dinuclear Gold Complex.

    PubMed

    Xie, Jin; Li, Jian; Weingand, Vanessa; Rudolph, Matthias; Hashmi, A Stephen K

    2016-08-26

    A practical protocol for a photocatalyzed alkyl-Heck-like reaction of unactivated alkyl bromides and different alkenes promoted by dinuclear gold photoredox catalysis in the presence of an inorganic base is reported. Primary, secondary, and tertiary unactivated alkyl bromides with β-hydrogen can be applied. Esters, aldehydes, ketones, nitriles, alcohols, heterocycles, alkynes, alkenes, ethers, and halogen moieties are all well tolerated. In addition to 1,1-diarylalkenes, silylenolethers and enamides can also be applied, which further increases the synthetic potential of the reaction. The mild reaction conditions, broad substrate scope, and an excellent functional-group tolerance deliver an ideal tool for synthetic chemists that can even be used for challenging late-stage modifications of complex natural products. PMID:27348503

  14. Polymer containing pendant tertiary alkyl amine groups useful in enhanced oil recovery using

    SciTech Connect

    Irani, C.A.; Harris, T.V.; Pretzer, W.R.

    1990-08-07

    This patent describes an improvement in a method for recovering oil from an underground oil-bearing earth formation penetrated by an injection well and a producing well, in which method carbon dioxide is injected into the formation to displace oil towards the producing well from which oil is produced to the surface. It comprises: injecting into the formation carbon dioxide, the viscosity of which is increased at least three-fold by the presence of a sufficient amount of a polymer containing pendant tertiary alkyl amine groups and a sufficient amount of a cosolvent to form a solution of the polymer in the carbon dioxide, wherein the minimum solubility parameter of the polymer is reduced to 6.85 (cal/cc)1/2 or less by control of the number of pendant tertiary alkyl amine groups and by the selection of the tertiary alkyl amine groups.

  15. Liquid-phase alkylation of benzene with light olefins catalyzed by {beta} zeolites

    SciTech Connect

    Bellussi, G.; Pazzuconi, G.; Perego, C.

    1995-11-01

    The catalytic performance of zeolite {beta} in the liquid-phase alkylation of benzene is compared with that of other solid catalysts. Zeolite {beta} is more active and more selective than zeolite Y in the alkylation with propylene and ethylene to cumene and ethylbenzene (EB). In the alkylation with propylene the overall selectivity of {beta} is higher than that of the traditional {open_quotes}solid phosphoric acid.{close_quotes} The catalytic activity is affected by the composition and the particle size of zeolite {beta} samples. Decreasing the framework Al content, by direct synthesis or by partial substitution of Al for B, produces a decrease in both conversion and selectivity in cumene and EB synthesis. A hypothesis to explain this behavior is given. The catalytic activity of zeolite {beta} is limited by intraparticle diffusion, as evidenced by the decreased activity corresponding to the particle size increase. 22 refs., 7 figs., 10 tabs.

  16. Boost refining profits by converting surplus butadiene to valuable feedstocks for MTBE and/or alkylation

    SciTech Connect

    Nocca, J.L. ); Hennico, A.; Cosyns, J.; Torck, B. )

    1994-01-01

    Ethylene plants produce a C4 butadiene-rich cut as a by-product. Although it has been a highly valued chemical intermediate for a long time, butadiene is now in over supply due to the installation of new steam cracking plants and the growing use of naphtha, the main butadiene generator, as feedstock. In the meantime, the demand for alkylate and ethers has increased steadily to produce environmentally friendly gasoline. This paper presents processes developed by IFP to convert surplus butadiene into ethers or alkylate for gasoline production. The first process transforms the butadiene-rich stream into a butenes-rich stream, an ideal alkylation feedstock. The second process generates isobutene from the butenes stream by skeletal isomerization for MTBE production.

  17. PROCESS FOR PRODUCING ALKYL ORTHOPHOSPHORIC ACID EXTRACTANTS

    DOEpatents

    Grinstead, R.R.

    1962-01-23

    A process is given for producing superior alkyl orthophosphoric acid extractants for use in solvent extraction methods to recover and purify various metals such as uranium and vanadium. The process comprises slurrying P/sub 2/O/ sub 5/ in a solvent diluent such as kerosene, benzene, isopropyl ether, and the like. An alipbatic alcohol having from nine to seventeen carbon atoms, and w- hcrein ihc OH group is situated inward of the terminal carbon atoms, is added to the slurry while the reaction temperature is mainiained below 60 deg C. The alcohol is added in the mole ratio of about 2 to l, alcohol to P/sub 2/O/sub 5/. A pyrophosphate reaotion product is formed in the slurry-alcohol mixture. Subsequently, the pyrophosphate reaction product is hydrolyzed with dilute mineral acid to produce the desired alkyl orthophosphoric aeid extractant. The extraetant may then be separated and utilized in metal-recovery, solvent- extraction processes. (AEC)

  18. In pursuit of homoleptic actinide alkyl complexes.

    PubMed

    Seaman, Lani A; Walensky, Justin R; Wu, Guang; Hayton, Trevor W

    2013-04-01

    This Forum Article describes the pursuit of isolable homoleptic actinide alkyl complexes, starting with the pioneering work of Gilman during the Manhattan project. The initial reports in this area suggested that homoleptic uranium alkyls were too unstable to be isolated, but Wilkinson demonstrated that tractable uranium alkyls could be generated by purposeful "ate" complex formation, which serves to saturate the uranium coordination sphere and provide the complexes with greater kinetic stability. More recently, we reported the solid-state molecular structures of several homoleptic uranium alkyl complexes, including [Li(THF)4][U(CH2(t)Bu)5], [Li(TMEDA)]2[UMe6], [K(THF)]3[K(THF)2][U(CH2Ph)6]2, and [Li(THF)4][U(CH2SiMe3)6], by employing Wilkinson's strategy. Herein, we describe our attempts to extend this chemistry to thorium. The treatment of ThCl4(DME)2 with 5 equiv of LiCH2(t)Bu or LiCH2SiMe3 at -25 °C in THF affords [Th(CH2(t)Bu)5] (1) and [Li(DME)2][Th(CH2SiMe3)5 (2), respectively, in moderate yields. Similarly, the treatment of ThCl4(DME)2 with 6 equiv of K(CH2Ph) produces [K(THF)]2[Th(CH2Ph)6] (3), in good yield. Complexes 1-3 have been fully characterized, while the structures of 1 and 3 were confirmed by X-ray crystallography. Additionally, the electronic properties of 1 and 3 were explored by density functional theory. PMID:22716022

  19. Urine of patients with early prostate cancer contains lower levels of light chain fragments of inter-alpha-trypsin inhibitor and saposin B but increased expression of an inter-alpha-trypsin inhibitor heavy chain 4 fragment.

    PubMed

    Jayapalan, Jaime J; Ng, Keng L; Shuib, Adawiyah S; Razack, Azad H A; Hashim, Onn H

    2013-06-01

    The present study was aimed at the identification of proteins that are differentially expressed in the urine of patients with prostate cancer (PCa), those with benign prostatic hyperplasia (BPH) and age-matched healthy male control subjects. Using a combination of 2DE and MS/MS, significantly lower expression of urinary saposin B and two different fragments of inter-alpha-trypsin inhibitor light chain (ITIL) was demonstrated in the PCa patients compared to the controls. However, only one of the ITIL fragments was significantly different between the PCa and BPH patients. When image analysis was performed on urinary proteins that were transferred onto NC membranes and detected using a lectin that binds to O-glycans, a truncated fragment of inter-alpha-trypsin inhibitor heavy chain 4 was the sole protein found to be significantly enhanced in the PCa patients compared to the controls. Together, these urinary peptide fragments might be useful complementary biomarkers to indicate PCa as well as to distinguish it from BPH, although further epidemiological evidence on the specificity and sensitivity of the protein candidates is required. PMID:23417432

  20. Absorption of carbon dioxide, nitrous oxide, ethane and nitrogen by 1-alkyl-3-methylimidazolium (C(n)mim, n = 2,4,6) tris(pentafluoroethyl)trifluorophosphate ionic liquids (eFAP).

    PubMed

    Almantariotis, D; Stevanovic, S; Fandiño, O; Pensado, A S; Padua, A A H; Coxam, J-Y; Costa Gomes, M F

    2012-07-01

    We measured the densities of 1-alkyl-3-methylimidazolium (C(n)mim, n = 2,4,6) tris(pentafluoroethyl)trifluorophosphate ionic liquids (eFAP) as a function of temperature and pressure and their viscosities as a function of temperature. These ionic liquids are less viscous than those based in the same cations but with other anions such as bis(trifluoromethylsulfonyl)imide. The ionic liquids studied are only partially miscible with water, their solubility increasing with the size of the alkyl side-chain of the cation and with temperature (from x(H(2)O) = 0.20 ± 0.03 for [C(4)mim][eFAP] at 303.10 K to x(H(2)O) = 0.49 ± 0.07 for [C(6)mim][eFAP] at 315.10 K). The solubility of carbon dioxide, nitrous oxide, ethane, and nitrogen in the three ionic liquids was measured as a function of temperature and at pressures close to atmospheric. Carbon dioxide and nitrous oxide are the more soluble gases with mole fraction solubilities of the order of 3 × 10(-2) at 303 K. The solubility of these gases does not increase linearly with the size of the alkyl-side chain of the cation. The solubilities of ethane and nitrogen are much lower than those of carbon dioxide and nitrous oxide (mole fractions 60% and 90% lower, respectively). The higher solubility of CO(2) and N(2)O can be explained by more favorable interactions between the solutes and the polar region of the ionic liquids as shown by the enthalpies of solvation determined experimentally and by the calculation of the site-site solute-solvent radial distribution functions using molecular simulation. PMID:22680072

  1. Ultra-bright alkylated graphene quantum dots.

    PubMed

    Feng, Lan; Tang, Xing-Yan; Zhong, Yun-Xin; Liu, Yue-Wen; Song, Xue-Huan; Deng, Shun-Liu; Xie, Su-Yuan; Yan, Jia-Wei; Zheng, Lan-Sun

    2014-11-01

    Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The photocatalytic rate is ca. 5.9 times higher than that of pure P25, indicating that AGQDs could harness the visible spectrum of sunlight for energy conversion or environmental therapy. PMID:25192187

  2. Mutagenic properties of allylic and alpha, beta-unsaturated compounds: consideration of alkylating mechanisms.

    PubMed

    Eder, E; Henschler, D; Neudecker, T

    1982-12-01

    1. Allyl and allylic compounds may exert alkylating activities by SN1, SN2 and SN2' mechanisms. This direct alkylating potential can be determined quantitatively by a modified 4-NBP (4-nitrobenzyl pyridine) test. 2. The alkylating activities in a systematically selected series of allyl and allylic compounds correlate well with the direct mutagenic potential as determined in the Ames test using Salmonella typhimurium TA 100 as tester strain. 3. The allylic structure is a prerequisite for these types of activities since structurally related molecules lacking the allylic moiety are inactive in this respect. 4. The potency of both the alkylating and mutagenic activity is determined by the strength of the leaving group: --OSO2CH3 greater than I greater than Br greater than Cl greater than--NCS. 5. Indirect mutagenicity, through metabolic activation of the olefinic bond (by addition of S9 mix to the tester medium), can be ruled out for practically all compounds, the only exception found being 2,3-dichloro-1-propene where an increase of mutagenicity is encountered after addition of S9 mix; mechanistic explanations for this exception are provided. 6. Analogous activation is demonstrated for benzyl halides, the alkylating potency of which is even higher than that of genuine allylic compounds. 7. A variety of methyl- and chlorine-substituted allyl compounds has been included in the study: both groups increase activity, either by +I (CH3) or by +M effects (Cl). 8. alpha, beta-Unsaturated carbonyl compounds, e.g. acrolein and crotonaldehyde, also display direct mutagenic activity which is due to a completely different mechanism: covalent binding to nucleophilic sites of DNA bases by Michael addition. Methyl and other alkyl substitutions decrease the mutagenic potential in this type of compound. The corresponding alcohols, also displaying mutagenic activity but to a lesser degree, are metabolically activated by ADH (alcohol dehydrogenase) of the tester strain microbes to the

  3. pi-Selective stationary phases: (II) Adsorption behavior of substituted aromatic compounds on n-alkyl-phenyl stationary phases

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A; Mayfield, Kirsty; Dennis, Gary; Shalliker, R. Andrew

    2010-01-01

    The frontal analysis method was used to measure the adsorption isotherms of phenol, 4-chlorophenol, p-cresol, 4-methoxyphenol and caffeine on a series of columns packed with home-made alkyl-phenyl bonded silica particles. These ligands consist of a phenyl ring tethered to the silica support via a carbon chain of length ranging from 0 to 4 atoms. The adsorption isotherm models that fit best to the data account for solute-solute interactions that are likely caused by p-p interactions occurring between aromatic compounds and the phenyl group of the ligand. These interactions are the dominant factor responsible for the separation of low molecular weight aromatic compounds on these phenyl-type stationary phases. The saturation capacities depend on whether the spacer of the ligands have an even or an odd number of carbon atoms, with the even alkyl chain lengths having a greater saturation capacity than the odd alkyl chain lengths. The trends in the adsorption equilibrium constant are also significantly different for the even and the odd chain length ligands.

  4. Use of dynamic simulation to assess the behaviour of linear alkyl benzene sulfonates and their biodegradation intermediates (sulfophenylcarboxylic acids) in estuaries

    NASA Astrophysics Data System (ADS)

    García-Luque, E.; González-Mazo, E.; Forja, J. M.; Gómez-Parra, A.

    2009-02-01

    Dynamic laboratory simulation of processes affecting chemical species in their transit through estuaries is a very useful tool to characterize these littoral systems. To date, laboratory studies concerning biodegradation and sorption (onto suspended particulate matter) of LAS in an estuary are scarce. For this reason, a dynamic automated estuarine simulator has been employed to carry out different experiments in order to assess the biodegradability of linear alkyl benzene sulfonates (LAS) and their biodegradation intermediates (sulfophenylcarboxylic acids, SPCs) using environmentally representative LAS concentrations in estuaries by a continuous injection of LAS into the system. During the experiments, a great affinity of LAS for the solid phase has been found, as well as an increased adsorption in line with increased chain length. On the other hand, the presence of SPCs with chain length between 6 and 13 carbon atoms was detected. Accumulation and persistence of medium chain length SPCs (C 6-C 8) along the experiments show that their degradation constitutes the limiting step for the process of LAS mineralization. In the final zone of the simulated estuarine system, the levels of SPCs were below the limits of detection. Thus, the disappearance of SPCs indicated that LAS biodegradation had been completed along the estuary. Similar results have been described for different Iberian littoral ecosystems. Therefore, the simulator employed in this research appears to be a useful tool to anticipate the behaviour of a xenobiotic chemical in its transit through littoral systems with different salinity gradients.

  5. Synthesis and biotransformation of 2-alkyl-4(1H)-quinolones by recombinant Pseudomonas putida KT2440.

    PubMed

    Niewerth, Heiko; Bergander, Klaus; Chhabra, Siri Ram; Williams, Paul; Fetzner, Susanne

    2011-09-01

    2-Alkyl-4(1H)-quinolones (AQs) and related derivatives, which exhibit a variety of biological properties, are secondary metabolites produced by, e.g., Pseudomonas and Burkholderia spp. Due to their main role as signaling molecules in the quorum sensing system of Pseudomonas aeruginosa, 2-heptyl-4(1H)-quinolone (HHQ) and its 3-hydroxy derivative, termed the "Pseudomonas quinolone signal" (PQS), have received considerable attention. Since chemical synthesis of different AQs is complex, we assessed the applicability of recombinant P. putida KT2440 strains for the biosynthetic production of AQs. In mineral salts medium supplemented with octanoate and anthranilate, batch cultures of P. putida KT2440 [pBBR-pqsABCD] produced about 45 μM HHQ, 30% and 70% of which were localized in the culture supernatant and methanolic cell extract, respectively. 2,4-Dihydroxyquinoline and minor amounts of C₃- to C₁₃-saturated and C₇:₁ to C₁₃:₁ monounsaturated AQs were formed as by-products. Mass spectrometry and nuclear magnetic resonance analyses spectroscopy indicated that unsaturated AQs having the same molecular mass are cis and trans isomers rather than position isomers, with the double bond located between the α and β carbon of the alkyl chain. Supplementing the cultures with hexanoate instead of octanoate shifted the AQ profile towards increased formation of C₅-AQ. Individual AQs can be prepared from concentrated methanolic extracts by preparative high-performance liquid chromatography (HPLC). Regioselective hydroxylation of HHQ to PQS can be achieved in > 90% yield by biotransformation with P. putida KT2440 [pBBR-pqsH]. PQS can be isolated from methanolic cell extracts by HPLC, or be precipitated as Fe(III)-PQS complex. Preparation of a library of AQs will facilitate studies on the biological functions of these compounds. PMID:21670979

  6. Quantitative proteomic analysis reveals metabolic alterations, calcium dysregulation, and increased expression of extracellular matrix proteins in laminin α2 chain-deficient muscle.

    PubMed

    de Oliveira, Bruno Menezes; Matsumura, Cintia Y; Fontes-Oliveira, Cibely C; Gawlik, Kinga I; Acosta, Helena; Wernhoff, Patrik; Durbeej, Madeleine

    2014-11-01

    Congenital muscular dystrophy with laminin α2 chain deficiency (MDC1A) is one of the most severe forms of muscular disease and is characterized by severe muscle weakness and delayed motor milestones. The genetic basis of MDC1A is well known, yet the secondary mechanisms ultimately leading to muscle degeneration and subsequent connective tissue infiltration are not fully understood. In order to obtain new insights into the molecular mechanisms underlying MDC1A, we performed a comparative proteomic analysis of affected muscles (diaphragm and gastrocnemius) from laminin α2 chain-deficient dy(3K)/dy(3K) mice, using multidimensional protein identification technology combined with tandem mass tags. Out of the approximately 700 identified proteins, 113 and 101 proteins, respectively, were differentially expressed in the diseased gastrocnemius and diaphragm muscles compared with normal muscles. A large portion of these proteins are involved in different metabolic processes, bind calcium, or are expressed in the extracellular matrix. Our findings suggest that metabolic alterations and calcium dysregulation could be novel mechanisms that underlie MDC1A and might be targets that should be explored for therapy. Also, detailed knowledge of the composition of fibrotic tissue, rich in extracellular matrix proteins, in laminin α2 chain-deficient muscle might help in the design of future anti-fibrotic treatments. All MS data have been deposited in the ProteomeXchange with identifier PXD000978 (http://proteomecentral.proteomexchange.org/dataset/PXD000978). PMID:24994560

  7. Increased dimeric IgA producing B cells in the bone marrow in IgA nephropathy determined by in situ hybridisation for J chain mRNA.

    PubMed Central

    Harper, S J; Allen, A C; Pringle, J H; Feehally, J

    1996-01-01

    AIM: To investigate the possible role of the systemic IgA immune system in the pathogenesis of IgA nephropathy METHODS: J chain mRNA expression in the IgA cells of the bone marrow was studied. Bone marrow trephine biopsy specimens from seven patients with IgA nephropathy and seven matched controls were examined by (1) non-isotopic in situ hybridisation (ISH) and (2) combined immunofluorescence and non-isotopic ISH to identify the plasma cell type. Serum polymeric IgA was also determined using standard high pressure liquid chromatography and sandwich enzyme linked immunosorbent assay. RESULTS: Non-isotopic ISH revealed a similar number of J chain mRNA positive cells/unit length in biopsy specimens from patients (16.5 +/- 2.7 cells/mm) and controls (17.7 +/- 2.4 cells/mm). Combined immunofluorescence and ISH revealed a greater proportion of J chain mRNA positive IgA cells in patients (7.6 +/- 1.45%) compared with controls (3 +/- 0.8%). Serum polymeric IgA was similar in both patients (91 +/- 22 mg/l) and controls (77 +/- 24 mg/l). CONCLUSION: These data suggest that excess production of dimeric IgA occurs in the bone marrow in IgA nephropathy. Images PMID:8666683

  8. Synthesis of the alkylated active metabolite of tipidogrel.

    PubMed

    Zhi, Shuang; Xia, Guangping; Liu, Ying; Tao, Zunwei; Chen, Ligong; Liu, Dengke

    2015-04-15

    Tipidogrel (3), an effective anti-platelet drug candidate working by irreversibly inhibiting P2Y12 receptor, holds great promise in overcoming clopidogrel resistance and increasing bioavailability. As a prodrug like other thienopyridines, it metabolizes through thiophene ring opening to form active metabolites 3a and 3b, nevertheless they are easily to form disulfide bond. Derivatization of 3a and 3b via alkylation with MPBr can prevent disulfide conjugation and ensure reliable pharmacokinetic results. Thus, in order to support its pre-clinical studies on efficiencies in the formation of tipidogrel active metabolites, 13a and 13b were synthesized via seven steps of chemosynthesis and incubation with MPBr in rat plasma in vitro. The resulting crude productions were purified by semi-preparative HPLC to give Z configuration 13a and E configuration 13b. In LC-MS/MS spectra, they showed identical fragmentation pattern and retention time with M-13a and M-13b, the MPBr-derivatives of active metabolites of tipidogrel in rats. Thus, 13a and 13b were the anticipated alkylated active metabolite of tipidogrel. In addition, in the nucleophilic substitution of thioacetate with compound 11, besides the anticipated compounds 12a and 12b, their isomers compounds 12c and 12d were detected, whose structures were confirmed and the corresponding mechanism was presented. PMID:25801935

  9. Molecular mechanisms of alkylation sensitivity in Indian muntjac cell lines.

    PubMed

    Musk, S R; Hatton, D H; Bouffler, S D; Margison, G P; Johnson, R T

    1989-07-01

    The responses of two Indian muntjac cell lines to two monofunctional alkylating agents were investigated. An SV40-transformed line (SVM) had an increased sensitivity to cell killing when compared to the other, euploid line (DM) after exposure both to methyl nitrosourea (MNU) and to dimethylsulphate (DMS) and also exhibited higher frequencies of sister chromatid exchanges (SCEs) following alkylation. The hypersensitivity of SVM to DMS correlates with the defective repair of single-strand breaks that results in the generation of long-lived breaks in the DNA following exposure, leading eventually to the formation of chromosome aberrations. In contrast no difference is seen in the formation of long-lived breaks in the DNA of SVM and DM after treatment with biologically relevant doses of MNU; in this case hypersensitivity may be due to the loss of O6-alkylguanine-DNA-alkyltransferase activity. The conclusion that the hypersensitivites of SVM to MNU and to DMS have different molecular bases is supported by transfection of SVM with plasmids containing the protein coding region of the Escherichia coli ada+ gene; subsequent expression within the cell corrects its hypersensitivity to the cytotoxic and SCE-inducing effects of MNU but has very little influence upon the lethality, SCE induction or the repair of long-lived DNA strand breaks after exposure to DMS. PMID:2544312

  10. Size and chain length effects on structural behaviors of biphenylcyclohexane-based liquid crystal nanoclusters by a coarse-grained model.

    PubMed

    Liao, Ming-Liang; Ju, Shin-Pon; Chang, Chun-Yi; Huang, Wei-Lin

    2012-06-01

    Size and chain length effects on structural behaviors of liquid crystal nanoclusters were examined by a coarse-grained model and the configurational-bias Monte Carlo (CBMC) simulation. The nanoclusters investigated in this study are composed of the biphenylcyclohexane-based BCH5H liquid crystal molecule and its derivatives. Results of the study show that the average energy decreases (i.e., more negative) as the cluster size (i.e., the number of molecules) increases. With the increasing cluster size, the equilibrium conformation of the nanocluster changes gradually from a pipe-like structure (for the smaller systems) to a ball-like cluster (for the larger systems). The order parameter of the system reduces with the transition of the equilibrium conformation. Regarding the chain length effect, the pipe-like equilibrium conformation (for the smaller systems) was observed more close to a pipe as the length of the tail alkyl chain of the derivatives extended. However, due to the flexibility of the tail alkyl chain, the pipe conformation of the system deflects slightly about its cyclohexyl group as the tail extends further. PMID:21975541

  11. Exploring architectures at the nanoscale: the interplay between hydrophobic twin lipid chains and head groups of designer peptide amphiphiles in the self-assembly process and application.

    PubMed

    Dasgupta, Antara

    2016-05-11

    The self-assembly of peptide amphiphiles (PAs) is found to be governed by the hydrophobic interactions induced by the hydrophobic groups/number of alkyl chains and the hydrophilic head groups. In this study, an assessment of the nanostructures formed by the self-assembly of simple twin chained PAs was carried out and compared to their single chain/short analogues. The spectroscopic and microscopic analysis revealed the fact that the twin chained amphiphiles had a high inclination to form β-sheet nanofibers and further towards hydrogelation. The mixture of twin chained PAs also exhibited cooperative self-assembly with improved aggregation behavior, although not much augmentation in β-type structuring was found. In contrast, the single chain/short analogue containing PAs showed very less of β-sheet type structures to a lesser extent and no hydrogelating behavior but resulted in mostly random conformations. The increase in the number or alteration of polar head groups in double chained PAs induced higher extent of β-type conformation and better gelling capability due to the combined hydrophobic effect of the twin chains. The overall results delineated the dominance of hydrophobic interactions. Finally, calcium phosphate bio-mineralization was done in the hydrogels of twin chained PAs with the aim of developing future biomaterials. PMID:27079384

  12. Lithium perchlorate-nitromethane-promoted alkylation of anilines with arylmethanols.

    PubMed

    Zhou, Jun; Mao, Hai-Feng; Wang, Lu; Zou, Jian-Ping; Zhang, Wei

    2011-11-01

    A new application of lithium perchlorate-nitromethane (LPNM) for the formation of aromatic C-N and C-C bonds is introduced. LPNM-promoted reactions of anilines with diarylmethanols selectively generate N-alkylated anilines or mono and double Friedel-Crafts alkylation products under different conditions by changing the reaction time, reaction temperature, and the ratio of the reactants. This method does not require the use of transition metal catalysts to prepare alkylated aniline derivatives. PMID:21547437

  13. Chain entanglements. I. Theory

    NASA Astrophysics Data System (ADS)

    Fixman, Marshall

    1988-09-01

    A model of concentrated polymer solution dynamics is described. The forces in a linear generalized Langevin equation for the motion of a probe chain are derived on the assumption that all relaxation of the forces is due to motion of the surrounding matrix. Vicinal chain displacements are classified as viscoelastic deformation, reptation, and minor residual fluctuations. The latter provide a torsional relaxation of the primitive path that minimizes the significance of transverse forces on the probe chain. All displacements of vicinal segments are assumed proportional to the forces that they exert on the probe chain. In response to an external force, the displacement of the probe chain relative to a laboratory frame is increased by viscoelastic deformation of the matrix, but reptative diffusion relative to the deforming matrix is slowed down. The net effect on translational diffusion is negligible if the probe and vicinal chains have the same chain length N, but the friction constant for reptative motion is increased by a factor N1-xs. xs=1/2 if Gaussian conformational statistics applies during the disengagement process, while xs =0.6 if excluded volume statistics applies. The translational friction constant is βp ˜N2, as in reptation theory, but the viscosity is η˜N4-xs . The persistence of entanglements during the translational diffusion of the probe chain across many radii of gyration is rationalized pictorially in terms of correlated reptative motion of the probe and vicinal chains.

  14. Highly conductive side chain block copolymer anion exchange membranes.

    PubMed

    Wang, Lizhu; Hickner, Michael A

    2016-06-28

    Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days. PMID:27216558

  15. Synthesis and Antifungal Activity of Natural Product-Based 6-Alkyl-2,3,4,5-tetrahydropyridines

    PubMed Central

    Dai, Liyan; Jacob, Melissa R.; Khan, Shabana I.; Khan, Ikhlas A.; Clark, Alice M.; Li, Xing-Cong

    2011-01-01

    Seven 6-alkyl-2,3,4,5-tetrahydropyridines (5a–5g) that mimic the natural piperideines that were recently identified in the fire ant venom have been synthesized. Compounds 5c–5g with the C-6 alkyl chain lengths from C14 to C18 showed varying degrees of antifungal activities, with 5e (6-hexadecyl-2,3,4,5-tetrahydropyridine) and 5f (6-heptadecyl-2,3,4,5-tetrahydropyridine) being the most active. Compound 5e exhibited minimum fungicidal concentrations (MFCs) of 3.8, 15.0, 7.5, and 7.5 μg/mL against Cryptococcus neoformans, Candida albicans, Candida glabrata, and Candida krusei, respectively. The antifungal activities of these compounds appear to be associated with the C-6 side chain length. This study represents the first effort to evaluate antifungal activities of synthetic analogs of the newly identified fire ant venom alkaloids. PMID:21905650

  16. Structure-activity relationships of C1 and C6 side chains of zaragozic acid A derivatives.

    PubMed

    Ponpipom, M M; Girotra, N N; Bugianesi, R L; Roberts, C D; Berger, G D; Burk, R M; Marquis, R W; Parsons, W H; Bartizal, K F; Bergstom, J D

    1994-11-11

    Systematic modification of the C6 acyl side chain of zaragozic acid A, a potent squalene synthase inhibitor, was undertaken to improve its biological activity. Simplification of the C6 side chain to the octanoyl ester has deleterious effects; increasing the linear chain length improves the in vitro activity up to the tetradecanoyl ester. An omega-phenoxy group is a better activity enhancer than an omega-phenyl group. A number of C6 carbamates, ethers, and carbonates were prepared and found to have similar activity profiles as the C6 esters. In the preparation of C6 ethers, C4 and C4,6 bisethers were also isolated; their relative activity is: C6 > C4 > C4,6. These C6 long-chain derivatives are subnanomolar squalene synthase inhibitors; they are, however, only weakly active in inhibiting hepatic cholesterol synthesis in mice. The C6 short-chain derivatives are much less active in vitro, but they all have improved oral activity in mice. Modification of the C1 alkyl side chain of the n-butanoyl analogue (ED50 4.5 mg/kg) did not improve the po activity further. A number of these C6 long-chain derivatives are also potent antifungal agents in vitro. PMID:7966163

  17. Alkyl Chlorides as Hydrogen Bond Acceptors

    SciTech Connect

    Nadas, Janos I; Vukovic, Sinisa; Hay, Benjamin

    2012-01-01

    To gain an understanding of the role of an alkyl chloride as a hydrogen bond acceptor, geometries and interaction energies were calculated at the MP2/aug-cc-pVDZ level of theory for complexes between ethyl chloride and representative hydrogen donor groups. The results establish that these donors, which include hydrogen cyanide, methanol, nitrobenzene, pyrrole, acetamide, and N-methylurea, form X-H {hor_ellipsis} Cl hydrogen bonds (X = C, N, O) of weak to moderate strength, with {Delta}E values ranging from -2.8 to -5.3 kcal/mol.

  18. (L)-(Trimethylsilyl)alanine synthesis exploiting hydroxypinanone-induced diastereoselective alkylation.

    PubMed

    René, A; Vanthuyne, N; Martinez, J; Cavelier, F

    2013-08-01

    A new and efficient synthesis of (L)-(trimethylsilyl)alanine (TMSAla) with suitable protection for use in Solid Phase Peptide Synthesis (SPPS) has been accomplished starting from glycine tert-butyl ester and using hydroxypinanone as chiral inductor. The silylated side chain was introduced by alkylation of the Schiff base intermediate with iodomethyl(trimethylsilane) at -78 °C. Among the different synthetic routes that were tested including several chiral inductors and different Schiff bases, this strategy was selected and afforded (L)-TMSAla in good chemical overall yield with 98 % ee. PMID:23620077

  19. Characterization of alkyl carbon in forest soils by CPMAS 13C NMR spectroscopy and dipolar dephasing

    USGS Publications Warehouse

    Kogel-Knabner, I.; Hatcher, P.G.

    1989-01-01

    Samples obtained from forest soils at different stages of decomposition were treated sequentially with chloroform/methanol (extraction of lipids), sulfuric acid (hydrolysis), and sodium chlorite (delignification) to enrich them in refractory alkyl carbon. As revealed by NMR spectroscopy, this treatment yielded residues with high contents of alkyl carbon. In the NMR spectra of residues obtained from litter samples, resonances for carbohydrates are also present, indicating that these carbohydrates are tightly bound to the alkyl carbon structures. During decomposition in the soils this resistant carbohydrate fraction is lost almost completely. In the litter samples the alkyl carbon shows a dipolar dephasing behavior indicative of two structural components, a rigid and a more mobile component. As depth and decomposition increase, only the rigid component is observed. This fact could be due to selective degradation of the mobile component or to changes in molecular mobility during decomposition, e.g., because of an increase in cross linking or contact with the mineral matter of the soil.

  20. Fragmentation of Electrospray-Produced Deprotonated Ions of Oligodeoxyribonucleotides Containing an Alkylated or Oxidized Thymidine

    NASA Astrophysics Data System (ADS)

    Wang, Pengcheng; Williams, Renee T.; Guerrero, Candace R.; Ji, Debin; Wang, Yinsheng

    2014-07-01

    Alkylation and oxidation constitute major routes of DNA damage induced by endogenous and exogenous genotoxic agents. Understanding the biological consequences of DNA lesions often necessitates the availability of oligodeoxyribonucleotide (ODN) substrates harboring these lesions, and sensitive and robust methods for validating the identities of these ODNs. Tandem mass spectrometry is well suited for meeting these latter analytical needs. In the present study, we evaluated how the incorporation of an ethyl group to different positions (i.e., O 2, N3, and O 4) of thymine and the oxidation of its 5-methyl carbon impact collisionally activated dissociation (CAD) pathways of electrospray-produced deprotonated ions of ODNs harboring these thymine modifications. Unlike an unmodified thymine, which often manifests poor cleavage of the C3'-O3' bond, the incorporation of an alkyl group to the O 2 position and, to a much lesser extent, the O 4 position, but not the N3 position of thymine, led to facile cleavage of the C3'-O3' bond on the 3' side of the modified thymine. Similar efficient chain cleavage was observed when thymine was oxidized to 5-formyluracil or 5-carboxyluracil, but not 5-hydroxymethyluracil. Additionally, with the support of computational modeling, we revealed that proton affinity and acidity of the modified nucleobases govern the fragmentation of ODNs containing the alkylated and oxidized thymidine derivatives, respectively. These results provided important insights into the effects of thymine modifications on ODN fragmentation.

  1. Protein refolding by N-alkylpyridinium and N-alkyl-N-methylpyrrolidinium ionic liquids.

    PubMed

    Yamamoto, Etsushi; Yamaguchi, Satoshi; Nagamune, Teruyuki

    2011-07-01

    An important property of ionic liquids consisting of cations and anions is that the chemical structures can be easily tuned. To expand the repertoire of effective ionic liquid-based refolding additives, we focused on this tunable property and investigated the effects of new candidates such as N-alkylpyridinium chlorides and N-alkyl-N-methylpyrrolidinium chlorides on protein refolding. Denatured lysozyme (30 mg/mL) was used as a model protein and refolded by 30-fold dilution with various refolding buffers containing different ionic liquids consisting of a systematic variety of alkyl chains. Compared with the refolding yield without additives (lower than 10%), less hydrophobic ionic liquids such as N-ethyl, N-butyl and N-hexylpyridinium chlorides, and N-butyl-N-methylpyrrolidinium chloride were effective in enhancing the refolding yields (46-69%), because they primarily suppressed aggregation because of their chaotropic properties. N-alkylpyridinium cations were more hydrophobic than N-alkyl-N-methylpyrrolidinium cations according to the calculated log P values and prevented aggregation at lower concentrations because of their hydrophobicity. The results provide a range of new effective ionic liquid-based additives for higher protein refolding yields and the knowledge of the effect of chemical structures of additives on protein refolding. PMID:21302144

  2. Diarmed (adamantyl/alkyl) surfactants from nitrilotriacetic acid.

    PubMed

    Trillo, Juan V; Vázquez Tato, José; Jover, Aida; de Frutos, Santiago; Soto, Victor H; Galantini, Luciano; Meijide, Francisco

    2014-11-01

    The compounds presented here constitute a clear example of molecular biomimetics as their design is inspired on the structure and properties of natural phospholipids. Thus novel double-armed surfactants have been obtained in which nitrilotriacetic acid plays the role of glycerol in phospholipids. The hydrophobic arms are linked to the head group through amide bonds (which is also the case of sphingomyelin): (R1NHCOCH2)(R2NHCOCH2)NCH2CO2H (R1 being CH3(CH2)11, CH3(CH2)17, CH3(CH2)7CHCH(CH2)8, and adamantyl, and R2=adamantyl). The dependence of the surface tension with concentration shows the typical profile of surfactants since a breaking point, which corresponds to the critical aggregation concentration (cac), is observed in all cases. The cac of these diarmed derivatives are about 1-3 orders of magnitude lower than those of classical monoalkyl derivatives used as reference compounds. In contrast to conventional surfactants, reversed trends in cac values and molecular areas at the solution-air interface have been observed. This anomalous behavior is tied to the structure of the surfactants and suggests that long and flexible alkyl chains should self-coil previous to the aggregation or adsorption phenomena. Above cac all compounds form large aggregates, globular in shape, which tend to associate forming giant aggregates. PMID:25465758

  3. Coexistent Multiple Myeloma or Increased Bone Marrow Plasma Cells Define Equally High-Risk Populations in Patients With Immunoglobulin Light Chain Amyloidosis

    PubMed Central

    Kourelis, Taxiarchis V.; Kumar, Shaji K.; Gertz, Morie A.; Lacy, Martha Q.; Buadi, Francis K.; Hayman, Suzanne R.; Zeldenrust, Steven; Leung, Nelson; Kyle, Robert A.; Russell, Stephen; Dingli, David; Lust, John A.; Lin, Yi; Kapoor, Prashant; Rajkumar, S. Vincent; McCurdy, Arleigh; Dispenzieri, Angela

    2013-01-01

    Purpose There is consensus that patients with light chain (AL) amyloidosis with hypercalcemia, renal failure, anemia, and lytic bone lesions attributable to clonal expansion of plasma cells (CRAB criteria) also have multiple myeloma (MM). The aim of this study was to examine the spectrum of immunoglobulin AL amyloidosis with and without MM, with a goal of defining the optimal bone marrow plasma cell (BMPC) number to qualify as AL amyloidosis with MM. Patients and Methods We identified 1,255 patients with AL amyloidosis seen within 90 days of diagnosis between January 1, 2000, and December 31, 2010. We defined a population of patients with coexisting MM on the basis of the existence of CRAB criteria (AL-CRAB). Receiver operating characteristic analysis determined the optimal BMPC cut point to predict for 1-year mortality in patients with AL amyloidosis without CRAB to produce two additional groups: AL only (≤ 10% BMPCs) and AL plasma cell MM (AL-PCMM; > 10% BMPCs). Results Among the 1,255 patients, 100 (8%) had AL-CRAB, 476 (38%) had AL-PCMM, and 679 (54%) had AL only. Their respective median overall survival rates were 10.6, 16.2, and 46 months (P < .001). Because the outcomes of AL-CRAB and AL-PCMM were similar, they were pooled for univariate and multivariate analyses. On multivariate analysis, pooled AL-CRAB and AL-PCMM retained negative prognostic value independent of age, Mayo Clinic AL amyloidosis stage, prior autologous stem-cell transplantation, and difference between the involved and uninvolved free light chain. Conclusion Patients with AL amyloidosis who have more than 10% BMPCs have a poor prognosis, similar to that of patients with AL-CRAB, and should therefore be considered together as AL amyloidosis with MM. PMID:24145344

  4. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  5. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  6. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  7. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  8. Rational design of novel N-alkyl-N capped biostable RNA nanostructures for efficient long-term inhibition of gene expression.

    PubMed

    Terrazas, Montserrat; Ivani, Ivan; Villegas, Núria; Paris, Clément; Salvans, Cándida; Brun-Heath, Isabelle; Orozco, Modesto

    2016-05-19

    Computational techniques have been used to design a novel class of RNA architecture with expected improved resistance to nuclease degradation, while showing interference RNA activity. The in silico designed structure consists of a 24-29 bp duplex RNA region linked on both ends by N-alkyl-N dimeric nucleotides (BCn dimers; n = number of carbon atoms of the alkyl chain). A series of N-alkyl-N capped dumbbell-shaped structures were efficiently synthesized by double ligation of BCn-loop hairpins. The resulting BCn-loop dumbbells displayed experimentally higher biostability than their 3'-N-alkyl-N linear version, and were active against a range of mRNA targets. We studied first the effect of the alkyl chain and stem lengths on RNAi activity in a screen involving two series of dumbbell analogues targeting Renilla and Firefly luciferase genes. The best dumbbell design (containing BC6 loops and 29 bp) was successfully used to silence GRB7 expression in HER2+ breast cancer cells for longer periods of time than natural siRNAs and known biostable dumbbells. This BC6-loop dumbbell-shaped structure displayed greater anti-proliferative activity than natural siRNAs. PMID:26975656

  9. Rational design of novel N-alkyl-N capped biostable RNA nanostructures for efficient long-term inhibition of gene expression

    PubMed Central

    Terrazas, Montserrat; Ivani, Ivan; Villegas, Núria; Paris, Clément; Salvans, Cándida; Brun-Heath, Isabelle; Orozco, Modesto

    2016-01-01

    Computational techniques have been used to design a novel class of RNA architecture with expected improved resistance to nuclease degradation, while showing interference RNA activity. The in silico designed structure consists of a 24–29 bp duplex RNA region linked on both ends by N-alkyl-N dimeric nucleotides (BCn dimers; n = number of carbon atoms of the alkyl chain). A series of N-alkyl-N capped dumbbell-shaped structures were efficiently synthesized by double ligation of BCn-loop hairpins. The resulting BCn-loop dumbbells displayed experimentally higher biostability than their 3′-N-alkyl-N linear version, and were active against a range of mRNA targets. We studied first the effect of the alkyl chain and stem lengths on RNAi activity in a screen involving two series of dumbbell analogues targeting Renilla and Firefly luciferase genes. The best dumbbell design (containing BC6 loops and 29 bp) was successfully used to silence GRB7 expression in HER2+ breast cancer cells for longer periods of time than natural siRNAs and known biostable dumbbells. This BC6-loop dumbbell-shaped structure displayed greater anti-proliferative activity than natural siRNAs. PMID:26975656

  10. The photodissociation dynamics of alkyl radicals

    NASA Astrophysics Data System (ADS)

    Giegerich, Jens; Fischer, Ingo

    2015-01-01

    The photodisscociation dynamics of the alkyl radicals i-propyl (CH(CH3)2) and t-butyl (C(CH3)3) are investigated by H-atom photofragment imaging. While i-propyl is excited at 250 nm, the photodynamics of t-butyl are explored over a large energy range using excitation wavelengths between 347 nm and 233 nm. The results are compared to those obtained previously for ethyl, CH3CH2, and to those reported for t-butyl using 248 nm excitation. The translational energy (ET) distribution of the H-atom photofragments is bimodal and appears rather similar for all three radicals. The low ET part of the distribution shows an isotropic photofragment angular distribution, while the high ET part is associated with a considerable anisotropy. Thus, for t-butyl, two H-atom loss channels of roughly equal importance have been identified in addition to the CH3-loss channel reported previously. A mechanism for the photodissociation of alkyl radicals is suggested that is based on interactions between Rydberg- and valence states.

  11. The photodissociation dynamics of alkyl radicals

    SciTech Connect

    Giegerich, Jens; Fischer, Ingo

    2015-01-28

    The photodisscociation dynamics of the alkyl radicals i-propyl (CH(CH{sub 3}){sub 2}) and t-butyl (C(CH{sub 3}){sub 3}) are investigated by H-atom photofragment imaging. While i-propyl is excited at 250 nm, the photodynamics of t-butyl are explored over a large energy range using excitation wavelengths between 347 nm and 233 nm. The results are compared to those obtained previously for ethyl, CH{sub 3}CH{sub 2}, and to those reported for t-butyl using 248 nm excitation. The translational energy (E{sub T}) distribution of the H-atom photofragments is bimodal and appears rather similar for all three radicals. The low E{sub T} part of the distribution shows an isotropic photofragment angular distribution, while the high E{sub T} part is associated with a considerable anisotropy. Thus, for t-butyl, two H-atom loss channels of roughly equal importance have been identified in addition to the CH{sub 3}-loss channel reported previously. A mechanism for the photodissociation of alkyl radicals is suggested that is based on interactions between Rydberg- and valence states.

  12. Escherichia coli gene that controls sensitivity to alkylating agents.

    PubMed Central

    Yamamoto, Y; Katsuki, M; Sekiguchi, M; Otsuji, N

    1978-01-01

    A new type of Escherichia coli mutant which shows increased sensitivity to methyl methane sulfonate but not to UV light or to gamma rays was isolated after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. The mutant is unable to reactivate phage lambdavir or double-stranded phiX174 DNA (replicative form) that had been treated with methyl methane sulfonate. The mutant is sensitive to other alkylating agents, such as ethyl methane sulfonate, mitomycin C, and N-methyl-N'-nitro-N-nitrosoguanidine, as well. It grows normally and exhibits almost normal recombination proficiency. The mutant possesses normal levels of DNA polymerase I, exonuclease I, exonuclease V, endonuclease specific for methyl methane sulfonate-treated DNA, and 3-methyladenine-DNA glycosidase activities. The genetic locus responsible has been named alk and is located near his on the chromosome. PMID:353028

  13. 40 CFR 721.10038 - Trimellitic anhydride, polymer with substituted glycol, alkyl phenols and ethoxylated nonylphenol...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted glycol, alkyl phenols and ethoxylated nonylphenol (generic). 721.10038 Section 721.10038... Trimellitic anhydride, polymer with substituted glycol, alkyl phenols and ethoxylated nonylphenol (generic... identified generically as trimellitic anhydride, polymer with substituted glycol, alkyl phenols...

  14. 40 CFR 721.10038 - Trimellitic anhydride, polymer with substituted glycol, alkyl phenols and ethoxylated nonylphenol...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substituted glycol, alkyl phenols and ethoxylated nonylphenol (generic). 721.10038 Section 721.10038... Trimellitic anhydride, polymer with substituted glycol, alkyl phenols and ethoxylated nonylphenol (generic... identified generically as trimellitic anhydride, polymer with substituted glycol, alkyl phenols...

  15. 40 CFR 721.10038 - Trimellitic anhydride, polymer with substituted glycol, alkyl phenols and ethoxylated nonylphenol...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... substituted glycol, alkyl phenols and ethoxylated nonylphenol (generic). 721.10038 Section 721.10038... Trimellitic anhydride, polymer with substituted glycol, alkyl phenols and ethoxylated nonylphenol (generic... identified generically as trimellitic anhydride, polymer with substituted glycol, alkyl phenols...

  16. Amplification of surface-initiated ring-opening metathesis polymerization of 5-(perfluoro-n-alkyl)norbornenes by macroinitiation.

    PubMed

    Escobar, Carlos A; Harl, Robert R; Maxwell, Kathryn E; Mahfuz, Nur N; Rogers, Bridget R; Jennings, G Kane

    2013-10-01

    This article reports the enhanced rate of the surface-initiated polymerization (SIP) of 5-(perfluoro-n-alkyl)norbornenes (NBFn) by combining two SIP techniques, namely surface-initiated atom-transfer polymerization (SI-ATRP) to grow a macroinitiator and surface-initiated ring-opening metathesis polymerization (SI-ROMP) to produce the final coating. This polymerization approach promotes the rapid growth of dense partially fluorinated coatings that are highly hydrophobic and oleophobic and yield thicknesses from 4-12 μm. Specifically, the growth rate and the limiting thickness of pNBFn with different side chain lengths (n = 4, 6, 8, and 10) at various monomer concentrations and temperatures are evaluated through two approaches: growing the polymer from an initiator-terminated monolayer (control) or from a modified poly(2-hydroxyethyl methacrylate) (PHEMA) macroinitiator. X-ray photoelectron spectroscopy (XPS) analysis shows that 38% of the hydroxyl termini in the macroinitiator react with a norbornenyl diacid chloride (NBDAC) molecule, and 7% of such anchored norbornenyl groups react with a catalyst molecule. The kinetic data have been modeled to determine the propagation velocity and the termination rate constant. The PHEMA macroinitiator provides thicker films and faster growth as compared to the monolayer, achieving a 12 μm thick coating of pNBF8 in 15 min. Increasing the monomer side chain length, n, from 4 to 10 improves the growth rate and the limiting polymer thickness. Performing the polymerization process at higher temperature increases the growth rate and the limiting thickness as evidenced by an increase in the film growth rate constant. Arrhenius plots show that the reactions involved in the macroinitiation process exhibit lower activation energies than those formed from a monolayer. Electrochemical impedance spectroscopy reveals that the films exhibit resistance against ion transport in excess of 1 × 10(10) Ω·cm(2). PMID:24024903

  17. Multi-electron dissociative ionization of clusters under picosecond and femtosecond laser irradiation: the case of alkyl-halide clusters.

    PubMed

    Karras, Gabriel; Kosmidis, Constantine

    2012-09-21

    The multi-electron dissociative ionization (MEDI) of alkyl-halide clusters induced by 35 ps (at 266, 532 and 1064 nm) and 20 fs (at 400 and 800 nm) laser pulses is reported. In most cases, the MEDI of clusters is observed at substantially lower laser intensities than those reported for the monomer molecules, while the fragment ions are released with higher kinetic energies. From the comparative analysis of the experimental data, is concluded that the increase of molecular chain and/or the presence of a lighter halogen (I, Br, Cl) in the molecular skeleton results in the increase of the laser intensity thresholds for the appearance of the singly and multiply charged fragment ions. As far as the angular distributions of the ejected ions are concerned, they are found to be dependent on the laser pulse duration. For the observed experimental data, a physical mechanism is proposed, based on the combined action of the laser and the electric field created within the clusters after their single ionization. PMID:22859215

  18. Synthesis, characterization and chemoprotective activity of polyoxovanadates against DNA alkylation.

    PubMed

    Nunes, Giovana G; Bonatto, Ana C; de Albuquerque, Carla G; Barison, Andersson; Ribeiro, Ronny R; Back, Davi F; Andrade, André Vitor C; de Sá, Eduardo L; Pedrosa, Fábio de O; Soares, Jaísa F; de Souza, Emanuel M

    2012-03-01

    The alkylation of pUC19 plasmid DNA has been employed as a model reaction for the first studies on chemoprotective action by a mixed-valence (+IV/+V) polyoxovanadate. A new, non-hydrothermal route for the high yield preparation of the test compound is described. The deep green, microcrystalline solid A was isolated after a three-day reaction in water at 80°C and 1 atm, while the reaction at 100°C gave green crystals of B. Both solids were structurally characterized by X-ray diffractometry and FTIR, EPR, NMR and Raman spectroscopies. Product A was identified as (NH(4))(2)V(3)O(8), while B corresponds to the spherical polyoxoanion [V(15)O(36)(Cl)](6-), isolated as the NMe(4)(+) salt. The lack of solubility of A in water and buffers prevented its use in DNA interaction studies, which were then carried out with B. Complex B was also tested for its ability to react with DNA alkylating agents by incubation with diethylsulphate (DES) and dimethylsulphate (DMS) in both the absence and presence of pUC19. For DMS, the best results were obtained with 10 mM of B (48% protection); with DES, this percentage increased to 70%. The direct reaction of B with increasing amounts of DMS in both buffered (PIPES 50 mM) and non-buffered aqueous solutions revealed the sequential formation of several vanadium(IV), vanadium(V) and mixed-valence aggregates of different nuclearities, whose relevance to the DNA-protecting activity is discussed. PMID:22265837

  19. DNA-damaging disinfection byproducts: alkylation mechanism of mutagenic mucohalic acids.

    PubMed

    Gómez-Bombarelli, Rafael; González-Pérez, Marina; Arenas-Valgañón, Jorge; Céspedes-Camacho, Isaac Fabián; Calle, Emilio; Casado, Julio

    2011-10-15

    Hydroxyhalofuranones form a group of genotoxic disinfection byproduct (DBP) of increasing interest. Among them, mucohalic acids (3,4-dihalo-5-hydroxyfuran-2(5H)-one, MXA) are known mutagens that react with nucleotides, affording etheno, oxaloetheno, and halopropenal derivatives. Mucohalic acids have also found use in organic synthesis due to their high functionalization. In this work, the alkylation kinetics of mucochloric and mucobromic acids with model nucleophiles aniline and NBP has been studied experimentally. Also, the alkylation mechanism of nucleosides by MXA has been studied in silico. The results described allow us to reach the following conclusions: (i) based on the kinetic and computational evidence obtained, a reaction mechanism was proposed, in which MXA react directly with amino groups in nucleotides, preferentially attacking the exocyclic amino groups over the endocyclic aromatic nitrogen atoms; (ii) the suggested mechanism is in agreement with both the product distribution observed experimentally and the mutational pattern of MXA; (iii) the limiting step in the alkylation reaction is addition to the carbonyl group, subsequent steps occurring rapidly; and (iv) mucoxyhalic acids, the hydrolysis products of MXA, play no role in the alkylation reaction by MXA. PMID:21910489

  20. Clinical applications of quinone-containing alkylating agents.

    PubMed

    Begleiter, A

    2000-11-01

    Quinone-containing alkylating agents are a class of chemical agents that have received considerable interest as anticancer drugs. These agents contain a quinone moiety that can be reduced and an alkylating group that can form covalent bonds with a variety of cellular components. The oxidation state of the quinone element can modulate the activity of the alkylating element, and reduction of the quinone is required for activation of the alkylating activity of many of these agents. The quinone element may also contribute to the cytotoxic activity of quinone-containing alkylating agents through the formation of reactive oxygen species during redox cycling. The natural product, mitomycin C, has been the most widely used quinone-containing alkylating agent in the clinic, but other quinone-containing alkylating agents like porfiromycin, diaziquone, carbazilquinone, triaziquone and EO9 have also been used in the clinic for the treatment of cancer. In addition, many other quinone-containing alkylating agents have been tested in preclinical studies and the development of new agents is being actively pursued. This chapter describes the current and past clinical uses of these agents in the treatment of cancer and discusses new agents that are currently in clinical trials. PMID:11056078

  1. 40 CFR 721.10073 - Modified alkyl acrylamide (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified alkyl acrylamide (generic... Specific Chemical Substances § 721.10073 Modified alkyl acrylamide (generic). (a) Chemical substance and... acrylamide (PMN P-05-536) is subject to reporting under this section for the significant new uses...

  2. 40 CFR 721.840 - Alkyl substituted diaromatic hydrocarbons.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... hydrocarbons. 721.840 Section 721.840 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.840 Alkyl substituted diaromatic hydrocarbons. (a) Chemical substance... alkyl substituted di-aro-matic hydrocarbons (PMN P-91-710) is subject to reporting under this...

  3. 40 CFR 721.840 - Alkyl substituted diaromatic hydrocarbons.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... hydrocarbons. 721.840 Section 721.840 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.840 Alkyl substituted diaromatic hydrocarbons. (a) Chemical substance... alkyl substituted di-aro-matic hydrocarbons (PMN P-91-710) is subject to reporting under this...

  4. 40 CFR 721.840 - Alkyl substituted diaromatic hydrocarbons.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... hydrocarbons. 721.840 Section 721.840 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.840 Alkyl substituted diaromatic hydrocarbons. (a) Chemical substance... alkyl substituted di-aro-matic hydrocarbons (PMN P-91-710) is subject to reporting under this...

  5. 40 CFR 721.840 - Alkyl substituted diaromatic hydrocarbons.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... hydrocarbons. 721.840 Section 721.840 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.840 Alkyl substituted diaromatic hydrocarbons. (a) Chemical substance... alkyl substituted di-aro-matic hydrocarbons (PMN P-91-710) is subject to reporting under this...

  6. 40 CFR 721.840 - Alkyl substituted diaromatic hydrocarbons.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... hydrocarbons. 721.840 Section 721.840 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.840 Alkyl substituted diaromatic hydrocarbons. (a) Chemical substance... alkyl substituted di-aro-matic hydrocarbons (PMN P-91-710) is subject to reporting under this...

  7. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  8. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  9. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  10. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  11. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  12. 40 CFR 721.655 - Ethoxylated alkyl quaternary ammonium compound.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... compound. 721.655 Section 721.655 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.655 Ethoxylated alkyl quaternary ammonium compound. (a) Chemical... as an ethoxylated alkyl quaternary ammonium compound (PMN P-96-573) is subject to reporting...

  13. 40 CFR 721.655 - Ethoxylated alkyl quaternary ammonium compound.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... compound. 721.655 Section 721.655 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.655 Ethoxylated alkyl quaternary ammonium compound. (a) Chemical... as an ethoxylated alkyl quaternary ammonium compound (PMN P-96-573) is subject to reporting...

  14. 40 CFR 721.655 - Ethoxylated alkyl quaternary ammonium compound.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... compound. 721.655 Section 721.655 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.655 Ethoxylated alkyl quaternary ammonium compound. (a) Chemical... as an ethoxylated alkyl quaternary ammonium compound (PMN P-96-573) is subject to reporting...

  15. 40 CFR 721.655 - Ethoxylated alkyl quaternary ammonium compound.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... compound. 721.655 Section 721.655 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.655 Ethoxylated alkyl quaternary ammonium compound. (a) Chemical... as an ethoxylated alkyl quaternary ammonium compound (PMN P-96-573) is subject to reporting...

  16. 40 CFR 721.655 - Ethoxylated alkyl quaternary ammonium compound.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... compound. 721.655 Section 721.655 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.655 Ethoxylated alkyl quaternary ammonium compound. (a) Chemical... as an ethoxylated alkyl quaternary ammonium compound (PMN P-96-573) is subject to reporting...

  17. Alkylation of refinery C5 streams to lower gasoline volatility

    SciTech Connect

    Cronkright, W.A.; Ditz, J.M.; Newsome, D.S. ); Lerner, H. ); Schorfheide, J.J. ); Libbers, D.D. )

    1994-01-01

    A pilot plant program was carried out to provide precise information about the sulfuric acid alkylation of refinery C5 streams under conditions found in commercial operation of the Exxon stirred, autorefrigerated alkylation process. The study used isobutane to alkylate the full range of pentenes in a C5 cut from an FCC unit as well as the linear olefin concentrate in the raffinate that would be obtained after processing this cut in a TAME unit. A few experiments were conducted with a mixture of C5 olefins matching the composition of the refinery feed in order to highlight the effect of impurities. The results showed that hydrocarbon impurities are a principal factor causing the high acid consumption values reported for pentene alkylation. The results also demonstrated that operating variables that affect acid consumption and alkylate quality in butene alkylation produce directionally similar effects in pentene alkylation, but of different magnitude. It is concluded that sulfur acid alkylation of pentenes produces an excellent isoparaffinic blending stock for the gasoline pool while eliminating volatile olefins and reducing gasoline RVP. Combined with the TAME process, a scheme for adding oxygen and achieving maximum RVP reduction at the same time is realized.

  18. Degradable Polymer Composites Fabricated from Starch and Alkyl Cyanoacrylate Monomer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Degradable polymer composites are fabricated from alkyl cyanoacrylate monomer and starch without special equipment. Alkyl cyanoacrylate, which is a major component of “super glue”, is a monomer that polymerizes at room temperature in the presence of initiators. During the fabrication of polymer com...

  19. 40 CFR 721.8700 - Halogenated alkyl pyridine.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated alkyl pyridine. 721.8700 Section 721.8700 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8700 Halogenated alkyl...

  20. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl ester (generic name). 721.2825 Section 721.2825 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject...