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Sample records for surfactant chain length

  1. How Chain Length and Charge Affect Surfactant Denaturation of Acyl Coenzyme A Binding Protein (ACBP)

    DEFF Research Database (Denmark)

    Andersen, Kell Kleiner; Otzen, Daniel

    2009-01-01

    maltoside (DDM). The aim has been to determine how surfactant chain length and micellar charge affect the denaturation mechanism. ACBP denatures in two steps irrespective of surfactant chain length, but with increasing chain length, the potency of the denaturant rises more rapidly than the critical micelle......Using intrinsic tryptophan fluorescence, equilibria and kinetics of unfolding of acyl coenzyme A binding protein (ACBP) have been investigated in sodium alkyl sulfate surfactants of different chain length (8-16 carbon atoms) and with different proportions of the nonionic surfactant dodecyl...... constants increases linearly with denaturant concentration below the cmc but declines at higher concentrations. Both shortening chain length and decreasing micellar charge reduce the overall kinetics of unfolding and makes the dependence of unfolding rate constants on surfactant concentration more complex...

  2. Effect of surfactant chain length on drug release kinetics from microemulsion-laden contact lenses.

    Science.gov (United States)

    Maulvi, Furqan A; Desai, Ankita R; Choksi, Harsh H; Patil, Rahul J; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O

    2017-05-30

    The effect of surfactant chain lengths [sodium caprylate (C 8 ), Tween 20 (C 12 ), Tween 80 (C 18 )] and the molecular weight of block copolymers [Pluronic F68 and Pluronic F 127] were studied to determine the stability of the microemulsion and its effect on release kinetics from cyclosporine-loaded microemulsion-laden hydrogel contact lenses in this work. Globule size and dilution tests (transmittance) suggested that the stability of the microemulsion increases with increase in the carbon chain lengths of surfactants and the molecular weight of pluronics. The optical transmittance of direct drug-laden contact lenses [DL-100] was low due to the precipitation of hydrophobic drugs in the lenses, while in microemulsion-laden lenses, the transmittance was improved when stability of the microemulsion was achieved. The results of in vitro release kinetics revealed that drug release was sustained to a greater extent as the stability of microemulsion was improved as well. This was evident in batch PF127-T80, which showed sustained release for 15days in comparison to batch DL-100, which showed release up to 7days. An in vivo drug release study in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC) with PF-127-T80 lenses (stable microemulsion) in comparison to PF-68-SC lenses (unstable microemulsion) and DL-100 lenses. This study revealed the correlation between the stability of microemulsion and the release kinetics of drugs from contact lenses. Thus, it was inferred that the stable microemulsion batches sustained the release of hydrophobic drugs, such as cyclosporine from contact lenses for an extended period of time without altering critical lens properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: surfactant chain length dependence of the critical micelle concentration.

    Science.gov (United States)

    Inoue, Tohru; Yamakawa, Haruka

    2011-04-15

    Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C(n)E(m)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)). Critical micelle concentration (cmc) was determined from the variation of (1)H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF(4) than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF(4) is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF(4) is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF(4) proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF(4) is much weaker than the hydrophobic effect. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutions.

    Science.gov (United States)

    Toledo-Jaldin, Helen Paola; Blanco-Flores, Alien; Sánchez-Mendieta, Víctor; Martín-Hernández, Osnieski

    2017-08-30

    Removal potentials of a surfactant modified zeolite (SMZ) and clay (SMC) for atrazine adsorption were evaluated. Materials were modified with hexadecyl trimethyl ammonium bromide (HDTMA-Br) and benzyl octadecyl dimethyl ammonium (BODA) chloride considering the critical micellar concentration (CMC) of each one (0.94 and 0.041 meq/L, respectively). The influence of the surfactant was analyzed in detail, particularly the formation of surfactant layers (complete or partial) connected with the length of the surfactant tail (16 and 18 methyl groups or number of carbons in the chain). Raw materials were characterized by XRD and Fourier transform infrared spectroscopy (FTIR), SMZ and SMC were analyzed by FTIR. Results obtained from kinetic adsorption experiments shown that equilibrium time is less for materials modified with HDTMA (8 h) than materials with BODA (10 and 12 h). Materials modified with the largest chain surfactant (BODA) showed more resistance to atrazine masse transference. The chemisorption was presented in the adsorption mechanisms of atrazine and adsorbent materials. Based on the results of adsorption isotherms Langmuir isotherms showed the better correlation coefficients value. The q max is greater for materials modified with BODA (0.9232 and 4.2448 mg/g) than for materials modified with HDTMA (0.6731 and 3.9121 mg/g). Therefore, SMZ and SMC modified with the largest chain surfactant has more affinity for the pesticide. The removal process at high concentration of atrazine depends of the partition process but at lower concentration, it occurs not only by this process but also by absorption process.

  5. Aggregation behavior and intermicellar interactions of cationic Gemini surfactants: Effects of alkyl chain, spacer lengths and temperature

    International Nuclear Information System (INIS)

    Hajy Alimohammadi, Marjan; Javadian, Soheila; Gharibi, Hussein; Tehrani-Bagha, Ali reza; Alavijeh, Mohammad Rashidi; Kakaei, Karim

    2012-01-01

    Graphical abstract: Highlights: → Enthalpy-entropy compensation relation was found between and for gemini surfactants. → The intermicellar interaction parameters are influenced with increasing the lengths of the tail and the spacer of gemini surfactants. → Increasing temperature decreases the intermicellar interaction parameters. → The changes in micellar surface charge density, and phase transition between spherical and rod geometries explain the data. - Abstract: The aggregation behavior of the cationic Gemini surfactants C m H 2m+1 N(CH 3 ) 2 (CH 2 ) S (CH 3 ) 2 N C m H 2m+1 ,2Br - with m = 12, 14 and s = 2, 4 were studied by performing surface tension, electrical conductivity, pulsed field gradient nuclear magnetic resonance (PFG-NMR), and cyclic voltammetry (CV) measurements over the temperature range 298 K to 323 K. The critical micelle concentration (CMC), surface excess (Γ max ), mean molecular surface area (A min ), degree of counter ion dissociation (α), and the thermodynamic parameters of micellization were determined from the surface tension and conductance data. An enthalpy-entropy compensation effect was observed and all the plots of enthalpy-entropy compensation exhibit excellent linearity. The micellar self-diffusion coefficients (D m ) and intermicellar interaction parameters (k d ) were obtained from the PFG-NMR and CV measurements. These results are discussed in terms of the intermicellar interactions, the effects of the chain and spacer lengths on the micellar surface charge density, and the phase transition between spherical and rod geometries. The intermicellar interaction parameters were found to decrease slightly with increasing temperature for 14-4-14, which suggests that the micellar surface charge density decreases with increasing temperature. The mean values of the hydrodynamic radius, R h , and the aggregation number, N agg , of the Gemini surfactants'm-4-m micelles were calculated from the micellar self-diffusion coefficient

  6. Effect of Difference in Fatty Acid Chain Lengths of Medium- Chain Lipids on Lipid/Surfactant/Water Phase Diagrams and Drug Solubility

    Directory of Open Access Journals (Sweden)

    Hetal N. Prajapati

    2011-09-01

    Full Text Available Lipids consisting of medium chain fatty acids are commonly used in the development of lipid-based selfemulsifying and self-microemulsifying drug delivery systems. However, no systematic approach to selecting one lipid over another has been reported in the literature. In this study, propylene glycol (PG monoester (PG monocaprylate, Capmul PG-8® and PG diester (PG dicaprylocaprate, Captex 200P® of C8-fatty acids were compared with PG monoester (PG monolaurate, Capmul PG-12® and PG diester (PG dilaurate, Capmul PG-2L® of C12-fatty acids with respect to their phase diagrams, and especially for their ability to form microemulsions in the presence of a common surfactant, Cremophor EL®, and water. The solubility of two model drugs, danazol and probucol, in the lipids and lipid/surfactant mixtures were also compared. The effect of the chain length of medium-chain fatty acids (C8 versus C12 on the phase diagrams of the lipids was minimal. Both shorter and longer chain lipids formed essentially similar microemulsion and emulsion regions in the presence of Cremophor EL® and water, although the C12-fatty acid esters formed larger gel regions in the phase diagrams than the C8-fatty acid esters. When monoesters were mixed with their respective diesters at 1:1 ratios, larger microemulsion regions with lower lipid particle sizes were observed compared to those obtained with individual lipids alone. While the solubility of both danazol and probucol increased greatly in all lipids studied, compared to their aqueous solubility, the solubility in C12-fatty acid esters was found to be lower than in C8-fatty acid esters when the lipids were used alone. This difference in solubility due to the difference in fatty acid chain length, practically disappeared when the lipids were combined with the surfactant.

  7. Nighttime oxidation of surfactants at the air-water interface: effects of chain length, head group and saturation

    Science.gov (United States)

    Sebastiani, Federica; Campbell, Richard A.; Rastogi, Kunal; Pfrang, Christian

    2018-03-01

    Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air-water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA), palmitoleic acid (POA), methyl oleate (MO) and stearic acid (SA) to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR) to determine the reaction kinetics of organic monolayers with NO3 at the air-water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7) × 10-8, (2.4±0.5) × 10-8and (3.3±0.6) × 10-8 cm2 molecule-1 s-1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5) × 10-3, (1.7±0.3) × 10-3 and (2.1±0.4) × 10-3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1) × 10-12 cm2 molecule-1 s-1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1) × 10-7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air-water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher than that of O3. Furthermore, the relative contributions of NO3 and O3 to the oxidative

  8. Nighttime oxidation of surfactants at the air–water interface: effects of chain length, head group and saturation

    Directory of Open Access Journals (Sweden)

    F. Sebastiani

    2018-03-01

    Full Text Available Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air–water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA, palmitoleic acid (POA, methyl oleate (MO and stearic acid (SA to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR to determine the reaction kinetics of organic monolayers with NO3 at the air–water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7 × 10−8, (2.4±0.5 × 10−8and (3.3±0.6 × 10−8 cm2 molecule−1 s−1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5 × 10−3, (1.7±0.3 × 10−3 and (2.1±0.4 × 10−3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1 × 10−12 cm2 molecule−1 s−1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1 × 10−7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air–water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher

  9. Effect of surfactant alkyl chain length on the dispersion, and thermal and dynamic mechanical properties of LDPE/organo-LDH composites

    Directory of Open Access Journals (Sweden)

    2011-05-01

    Full Text Available Low density polyethylene/layered double hydroxide (LDH composites were prepared via melt compounding using different kinds of organo-LDHs and polyethylene-grafted maleic anhydride as the compatibilizer. The organo-LDHs were successfully prepared by converting a commercial MgAl-carbonate LDH into a MgAl-nitrate LDH, which was later modified by anion exchange with linear and branched sodium alkyl sulfates having different alkyl chain lengths (nc = 6, 12 and 20. It was observed that, depending on the size of the surfactant alkyl chain, different degrees of polymer chain intercalation were achieved, which is a function of the interlayer distance of the organo-LDHs, of the packing level of the alkyl chains, and of the different interaction levels between the surfactant and the polymer chains. In particular, when the number of carbon atoms of the surfactant alkyl chain is larger than 12, the intercalation of polymer chains in the interlayer space and depression of the formation of large aggregates of organo-LDH platelets are favored. A remarkable improvement of the thermal-oxidative degradation was evidenced for all of the composites; whereas only a slight increase of the crystallization temperature and no significant changes of both melting temperature and degree of crystallinity were achieved. By thermodynamic mechanical analysis, it was evidenced that a softening of the matrix is may be due to the plasticizing effect of the surfactant.

  10. Synthetic high-charge organomica: effect of the layer charge and alkyl chain length on the structure of the adsorbed surfactants.

    Science.gov (United States)

    Pazos, M Carolina; Castro, Miguel A; Orta, M Mar; Pavón, Esperanza; Valencia Rios, Jesús S; Alba, María D

    2012-05-15

    A family of organomicas was synthesized using synthetic swelling micas with high layer charge (Na(n)Si(8-n)Al(n)Mg(6)F(4)O(20)·XH(2)O, where n = 2, 3, and 4) exchanged with dodecylammonium and octadecylammonium cations. The molecular arrangement of the surfactant was elucidated on the basis on XRD patterns and DTA. The ordering conformation of the surfactant molecules into the interlayer space of micas was investigated by (13)C, (27)Al, and (29)Si MAS NMR. The arrangement of alkylammonium ions in these high-charge synthetic micas depends on the combined effects of the layer charge of the mica and the chain length of the cation. In the organomicas with dodecylammonium, a transition from a parallel layer to a bilayer-paraffin arrangement is observed when the layer charge of the mica increases. However, when octadecylammonium is the interlayer cation, the molecular arrangement of the surfactant was found to follow the bilayer-paraffin model for all values of layer charge. The amount of ordered conformation all-trans is directly proportional of layer charge.

  11. Optimization of Water/Oil/Surfactant System for Preparation of Medium-Chain-Length Poly-3-Hydroxyalkanoates (mcl-PHA)-Incorporated Nanoparticles via Nanoemulsion Templating Technique.

    Science.gov (United States)

    Ishak, K A; Annuar, M Suffian M; Ahmad, N

    2017-12-01

    Polymeric nanoparticles gain a widespread interest in food and pharmaceutical industries as delivery systems that encapsulate, protect, and release lipophilic compounds such as omega-3 fatty acids, fat-soluble vitamins, carotenoids, carvedilol, cyclosporine, and ketoprofen. In this study, medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA)-incorporated nanoparticle was developed via facile organic solvent-free nanoemulsion templating technique. The water content (W/surfactant-to-oil (S/O)), S/O, and Cremophor EL-to-Span 80 (Cremo/Sp80) ratios were first optimized using response surface methodology (RSM) to obtain nanoemulsion template prior to incorporation of mcl-PHA. Their effects on nanoemulsion formation were investigated. The mcl-PHA-incorporated nanoparticle system showed a good preservation capability of β-carotene and extended storage stability.

  12. Effect of alkyl length of cationic surfactants on desorption of Cs from contaminated clay

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo Hyun; Park, Chan Woo; Yang, Hee Man; Seo, Bum Kyoung; Lee, Kune Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, So Jin [Chungnam National University, Daejeon (Korea, Republic of)

    2017-03-15

    In this study, desorption characteristics of Cs from clay according to the hydrophobic alkyl chain length of the cationic surfactant were investigated. Alkyltrimethylammonium bromide was used as a cationic surfactant, and the length of the hydrophobic alkyl chain of the cationic surfactant was varied from –octyl to –cetyl. The adsorbed amount of the cationic surfactant on montmorillonite increased with the length of the hydrophobic alkyl chain, and intercalation of the cationic surfactant into the clay interlayer increased the interlayer distances. The Cs removal efficiency was also enhanced with increasing alkyl chain length, and the cationic surfactant with the cetyl group showed a maximum Cs removal efficiency of 99±2.9%.

  13. Effect of Amphiphilic Alkyl Chain Length Upon Purified LATEX Stability

    International Nuclear Information System (INIS)

    Amira Amir Hassan; Amir Hashim Mohd Yatim

    2015-01-01

    Rubber particles in purified latex (PL) are stabilized by a film of protein and fatty acid soap (surfactant). Saturated straight-chain fatty acid soaps can assist an enhancement of latex stability. However, whether the alkyl chain length plays an important role in increasing the stability is still an issue. The aim of this study is to investigate the effect of alkyl chain length of anionic surfactant on the stability of purified latex. The fatty acid soap of decanoate (9), laurate (11), sodium dodecyl sulphate (SDS) (12) and palmitate (15) were used. The numbers in parentheses indicating the number of carbon present in alkyl chain of the soap. The results showed that the impact of alkyl chain length on the stability of latex is in the order of laurate > decanoate > SDS > palmitate > purified latex accordingly. The alkyl chain length does giving a significant effect on latex stability after longer stirring time. The particle size of latex with the presence of surfactant is greater compare to a single particle itself due to extension of particles diameter. Thus suitable interaction of the nonpolar tail of surfactant with the hydrophobic regions of latex surface played a major role in maintaining a stable latex system. (author)

  14. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

    Directory of Open Access Journals (Sweden)

    Roza Bouchal

    2016-02-01

    Full Text Available Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of 1H and 13C NMR, differential scanning calorimetry (DSC, and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK, critical micelle concentration (CMC, minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (ΔmicH° were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group.

  15. Phase behaviour of an ionic microemulsion system as a function of the cosurfactant chain length

    NARCIS (Netherlands)

    Kegel, W.K.; Lekkerkerker, H.N.W.

    1993-01-01

    The phase behaviour of a microemulsion system consisting of equal volumes of brine and oil, sodium dodecyl sulphate (SDS) as surfactant and alcohols of different chain lengths (pentanol, hexanol and heptanol) as cosurfactant was studied. In the case of pentanol, at low surfactant concentrations and

  16. Superhydrophilic surfaces from short and medium chain solvo-surfactants

    Directory of Open Access Journals (Sweden)

    Valentin Romain

    2013-01-01

    Full Text Available Pure monoglycerides (GM-Cs and glycerol carbonate esters (GCE-Cs are two families of oleochemical molecules composed of a polar part, glycerol for GM-Cs, glycerol carbonate for GCE-Cs, and a fatty acid lipophilic part. From a chemical point of view, GM-Cs include two free oxygen atoms in the hydroxyl functions and one ester function between the fatty acid and the glycerol parts. GCE-Cs contain two blocked oxygen atoms in the cyclic carbonate backbone and three esters functions: two endocyclic in the five-membered cyclic carbonate function, one exocyclic between the fatty acid and glycerol carbonate parts. At the physico-chemical level, GMCs and GCE-Cs are multifunctional molecules with amphiphilic structures: a common hydrophobic chain to the both families and a polar head, glycerol for GMs and glycerol carbonate for GCE-Cs. Physicochemical properties depend on chain lengths, odd or even carbon numbers on the chain, and glyceryl or cyclocarbonic polar heads. The solvo-surfactant character of GM-Cs and overall GCE-Cs were discussed through the measurements of critical micellar concentration (CMC or critical aggregation concentration (CAC. These surface active glycerol esters/glycerol carbonate esters were classified following their hydrophilic/hydrophobic character correlated to their chain length (LogPoctanol/water = f(atom carbon number. Differential scanning calorimetry and optical polarized light microscopy allow us to highlight the selfassembling properties of the glycerol carbonate esters alone and in presence of water. We studied by thermal analysis the polymorphic behaviour of GCE-Cs, and the correlation between their melting points versus the chain lengths. Coupling the self-aggregation and crystallization properties, superhydrophilic surfaces were obtained by formulating GM-Cs and GCE-Cs. An efficient durable water-repellent coating of various metallic and polymeric surfaces was allowed. Such surfaces coated by self-assembled fatty acid

  17. Persistence length of wormlike micelles composed of ionic surfactants: self-consistent-field predictions

    NARCIS (Netherlands)

    Lauw, Y.; Leermakers, F.A.M.; Cohen Stuart, M.A.

    2007-01-01

    The persistence length of a wormlike micelle composed of ionic surfactants CnEmXk in an aqueous solvent is predicted by means of the self-consistent-field theory where CnEm is the conventional nonionic surfactant and X-k is an additional sequence of k weakly charged (pH-dependent) segments. By

  18. Neutron chain length distributions in subcritical systems

    International Nuclear Information System (INIS)

    Nolen, S.D.; Spriggs, G.

    1999-01-01

    In this paper, the authors present the results of the chain-length distribution as a function of k in subcritical systems. These results were obtained from a point Monte Carlo code and a three-dimensional Monte Carlo code, MC++. Based on these results, they then attempt to explain why several of the common neutron noise techniques, such as the Rossi-α and Feynman's variance-to-mean techniques, are difficult to perform in highly subcritical systems using low-efficiency detectors

  19. Finite fission chain length and symmetry around prompt-criticality

    International Nuclear Information System (INIS)

    Xie Qilin; Yin Yanpeng; Gao Hui; Huang Po; Fang Xiaoqiang

    2012-01-01

    Probability distribution of finite fission chain length was derived by assuming that all neutrons behave identically. Finite fission chain length was also calculated using a zero-dimension Monte-Carlo method based on point kinetics. Then symmetry of finite fission chain length probability distribution around prompt-criticality was deduced, which helps understanding the emission rate of delayed neutrons and initiation of fission chain in super-prompt-critical system. (authors)

  20. Interactions of short chain phenylalkanoic acids within ionic surfactant micelles in aqueous media

    Directory of Open Access Journals (Sweden)

    Naeem Kashif

    2012-01-01

    Full Text Available % SDS KR nema Solubilization and interactions of phenylalkanoic acids induced by cationic surfactant, cetyltrimethylammonium bromide (CTAB and an anionic surfactant, sodium dodecyl sulfate (SDS was investigated spectrophotometrically at 25.0°C. The UV spectra of the additives (acids were measured with and without surfactant above and below critical micelle concentration (cmc of the surfactant. The presence of alkyl chain in phenylalkanoic acids is responsible for hydrophobic interaction resulting in shift of the spectra towards longer wavelength (red shift. The value of partition coefficient (Kx between the bulk water and surfactant micelles and in turn standard free energy change of solubilization (ΔGpº were also estimated by measuring the differential absorbance (ΔA of the additives in micellar solutions.

  1. Micellar dipolar rearrangement is sensitive to hydrophobic chain length: Implication for structural switchover of piroxicam.

    Science.gov (United States)

    Sethy, Dasaratha; Chakraborty, Hirak

    2016-10-01

    The interfacial properties of the membrane are exceptionally vital in drug-membrane interaction. They not only select out a particular prototropic form of the drug molecule for incorporation, but are also potent enough to induce structural switchover of these drugs in several cases. In this work, we quantitatively monitored the change in dipolar rearrangement of the micellar interface (as a simplified membrane mimic) by measuring the dielectric constant and dipole potential with the micellization of SDS at pH 3.6. The dielectric constant and dipole potential were measured utilizing the fluorescence of polarity sensitive probe, pyrene and potential-sensitive probe, di-8-ANEPPS, respectively. Our study demonstrates that the change in dipolar rearrangement directly influences the switchover equilibrium between the anionic and neutral from of piroxicam. We have further extended our work to evaluate the effect of hydrophobic chain length of the surfactants on the dipolar rearrangement and its effect on the structural switchover of piroxicam. It is interesting that the extent of switchover of piroxicam is directly correlated with the dipolar rearrangement induced bythe varying hydrophobic chain length of the surfactants. To the best of our knowledge, our results constitute the first report to show the dependence of dipole potential on the hydrophobic chain length of the surfactant and demonstrate that the dipolar rearrangement directly tunes the extent of structural switchover of piroxicam, which was so far only intuitive. We consider that this new finding would have promising implication in drug distribution and drug efficacy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  2. Constraints on food chain length arising from regional metacommunity dynamics

    Science.gov (United States)

    Calcagno, Vincent; Massol, François; Mouquet, Nicolas; Jarne, Philippe; David, Patrice

    2011-01-01

    Classical ecological theory has proposed several determinants of food chain length, but the role of metacommunity dynamics has not yet been fully considered. By modelling patchy predator–prey metacommunities with extinction–colonization dynamics, we identify two distinct constraints on food chain length. First, finite colonization rates limit predator occupancy to a subset of prey-occupied sites. Second, intrinsic extinction rates accumulate along trophic chains. We show how both processes concur to decrease maximal and average food chain length in metacommunities. This decrease is mitigated if predators track their prey during colonization (habitat selection) and can be reinforced by top-down control of prey vital rates (especially extinction). Moreover, top-down control of colonization and habitat selection can interact to produce a counterintuitive positive relationship between perturbation rate and food chain length. Our results show how novel limits to food chain length emerge in spatially structured communities. We discuss the connections between these constraints and the ones commonly discussed, and suggest ways to test for metacommunity effects in food webs. PMID:21367786

  3. Novel Pyridinium Surfactants with Unsaturated Alkyl Chains : Aggregation Behavior and Interactions with Methyl Orange in Aqueous Solution

    NARCIS (Netherlands)

    Kuiper, Johanna M.; Buwalda, Rixt T.; Hulst, Ron; Engberts, Jan B.F.N.

    2001-01-01

    This paper presents the synthesis and a study of the aggregation behavior of 4-undecyl-1-methyl- and 4-undecenyl-1-methylpyridinium iodide surfactants. The effect of the position of the double bond in the alkyl chain of the surfactant on the critical micelle concentration (cmc), degree of counterion

  4. The Chain-Length Distribution in Subcritical Systems

    International Nuclear Information System (INIS)

    Nolen, Steven Douglas

    2000-01-01

    The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated

  5. The Chain-Length Distribution in Subcritical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, Steven Douglas [Texas A & M Univ., College Station, TX (United States)

    2000-06-01

    The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Desorption of hydrocarbon chains by association with ionic and nonionic surfactants under flow as a mechanism for enhanced oil recovery.

    Science.gov (United States)

    Terrón-Mejía, Ketzasmin A; López-Rendón, Roberto; Goicochea, Armando Gama

    2017-08-29

    The need to extract oil from wells where it is embedded on the surfaces of rocks has led to the development of new and improved enhanced oil recovery techniques. One of those is the injection of surfactants with water vapor, which promotes desorption of oil that can then be extracted using pumps, as the surfactants encapsulate the oil in foams. However, the mechanisms that lead to the optimal desorption of oil and the best type of surfactants to carry out desorption are not well known yet, which warrants the need to carry out basic research on this topic. In this work, we report non equilibrium dissipative particle dynamics simulations of model surfactants and oil molecules adsorbed on surfaces, with the purpose of studying the efficiency of the surfactants to desorb hydrocarbon chains, that are found adsorbed over flat surfaces. The model surfactants studied correspond to nonionic and cationic surfactants, and the hydrocarbon desorption is studied as a function of surfactant concentration under increasing Poiseuille flow. We obtain various hydrocarbon desorption isotherms for every model of surfactant proposed, under flow. Nonionic surfactants are found to be the most effective to desorb oil and the mechanisms that lead to this phenomenon are presented and discussed.

  8. Stochastic Simulation of a Full-Chain Reptation Model with Constraint Release, Chain-Length Fluctuations and Chain Stretching

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Schieber, Jay D.

    1999-01-01

    A self-consistent reptation model that includes chain stretching, chain-length fluctuations, segment connectivity and constraint release is used to predict transient and steady flows. Quantitative comparisons are made with entangledsolution data. The model is able to capture quantitatively all...

  9. Phase Behavior and Evaporation Profile of Tween 20 - Eugenol System. Effect of Different Alkane Chain Length and Solvent System

    International Nuclear Information System (INIS)

    Kassim, A.; Lim, W.H.; Kuangl, D.; Rusmawati, W.W.M.; Abdullah, A.H.; Teoh, S.P.

    2003-01-01

    The isotropic region of Tween 20/eugenol/n-alkane in aqueous systems was determined. The solubilisation trend of isotropic solution formed in the presence of eugenol was studied as a function of different alkyl chain length of n-alkane. The solubility of solvent in surfactant solution is dependent on their molecular polarity. An increase in n-alkane chain length (lower polarity) lead to smaller isotropic region which will affect the surfactant partitioning between the interface, the oil phase and the aqueous phase of the microemulsion as the oil chain length is varied. The changes of evaporation behaviour were affected strongly by the types of phases existed in the systems. The increment of n-alkane and water content led to higher evaporation rate. But the formation of w/o microemulsion would lower the evaporation rate because water molecules were trapped in the core of aggregates. In solubilisation system, evaporation rate is dependent on the solvent content and the interaction between Tween 20 and solvent molecules in the mixed composition. (author)

  10. Expected value of finite fission chain lengths of pulse reactors

    International Nuclear Information System (INIS)

    Liu Jianjun; Zhou Zhigao; Zhang Ben'ai

    2007-01-01

    The average neutron population necessary for sponsoring a persistent fission chain in a multiplying system, is discussed. In the point reactor model, the probability function θ(n, t 0 , t) of a source neutron at time t 0 leading to n neutrons at time t is dealt with. The non-linear partial differential equation for the probability generating function G(z; t 0 , t) is derived. By solving the equation, we have obtained an approximate analytic solution for a slightly prompt supercritical system. For the pulse reactor Godiva-II, the mean value of finite fission chain lengths is estimated in this work and shows that the estimated value is reasonable for the experimental analysis. (authors)

  11. Glycogen with short average chain length enhances bacterial durability

    Science.gov (United States)

    Wang, Liang; Wise, Michael J.

    2011-09-01

    Glycogen is conventionally viewed as an energy reserve that can be rapidly mobilized for ATP production in higher organisms. However, several studies have noted that glycogen with short average chain length in some bacteria is degraded very slowly. In addition, slow utilization of glycogen is correlated with bacterial viability, that is, the slower the glycogen breakdown rate, the longer the bacterial survival time in the external environment under starvation conditions. We call that a durable energy storage mechanism (DESM). In this review, evidence from microbiology, biochemistry, and molecular biology will be assembled to support the hypothesis of glycogen as a durable energy storage compound. One method for testing the DESM hypothesis is proposed.

  12. Topological analysis of polymeric melts: chain-length effects and fast-converging estimators for entanglement length.

    Science.gov (United States)

    Hoy, Robert S; Foteinopoulou, Katerina; Kröger, Martin

    2009-09-01

    Primitive path analyses of entanglements are performed over a wide range of chain lengths for both bead spring and atomistic polyethylene polymer melts. Estimators for the entanglement length N_{e} which operate on results for a single chain length N are shown to produce systematic O(1/N) errors. The mathematical roots of these errors are identified as (a) treating chain ends as entanglements and (b) neglecting non-Gaussian corrections to chain and primitive path dimensions. The prefactors for the O(1/N) errors may be large; in general their magnitude depends both on the polymer model and the method used to obtain primitive paths. We propose, derive, and test new estimators which eliminate these systematic errors using information obtainable from the variation in entanglement characteristics with chain length. The new estimators produce accurate results for N_{e} from marginally entangled systems. Formulas based on direct enumeration of entanglements appear to converge faster and are simpler to apply.

  13. Synthesis and properties evaluation of sulfobetaine surfactant with double hydroxyl

    Science.gov (United States)

    Zhou, Ming; Luo, Gang; Zhang, Ze; Li, Sisi; Wang, Chengwen

    2017-09-01

    A series of sulfobetaine surfactants {N-[(3-alkoxy-2-hydroxyl)propoxy] ethyl-N,N-dimethyl-N-(2-hydroxyl)propyl sulfonate} ammonium chloride were synthesized with raw materials containing linear saturated alcohol, N,N-dimethylethanolamine, sodium 3-chloro-2-hydroxyl propane sulfonic acid and epichlorohydrin. The molecule structures of sulfobetaine surfactants were characterized by FTIR, 1HNMR and elemental analysis. Surface tension measurements can provide us information about the surface tension at the CMC (γCMC), pC20, Γmax and Amin. The pC20 values of sulfobetaine surfactants increase with the hydrophobic chain length increasing. Amin values of the surfactants decrease with increasing hydrophobic chain length from 10 to 14. The critical micelle concentration (CMC) and surface tension (γCMC) values of the sulfobetaine surfactants decrease with increasing hydrophobic chain length from 10 to 16. The lipophilicity of surfactant was enhanced with the increase of the carbon chain, however, the ability of anti-hard water was weakened. The minimum oil/water interfacial tension of four kinds of sulfobetaine surfactants is 10-2-10-3 mN/m magnitude, which indicates that the synthesized bis-hydroxy sulfobetaine surfactants have a great ability to reduce interfacial tension in the surfactant flooding system. The surface tension (γCMC) values of synthesized surfactants were lower compared with conventional anionic surfactant sodium dodecyl sulfonate.

  14. Effect of temperature on atom-atom collision chain length in metals

    International Nuclear Information System (INIS)

    Makarov, A.A.; Demkin, N.A.; Lyashchenko, B.G.

    1981-01-01

    Focused atom-atom collision chain lengths are calculated for fcc-crystals with account of thermal oscillations. The model of solid spheres with the Born-Merier potential has been used in the calculations. The dependence of chain lengths on the temperature, energy and movement direction of the first chain atom for Cu, Au, Ag, Pb, Ni is considered. The plot presented shows that the chain lengths strongly decrease with temperature growth, for example, for the gold at T=100 K the chain length equals up to 37 interatomic spacings, whereas at T=1000 K their length decreases down to 5 interatomic distances. The dependence of the energy loss by the chain atoms on the atom number in the chain is obtained in a wide range of crystal temperature and the primary chain atom energy [ru

  15. Distinct changes in pulmonary surfactant homeostasis in common beta-chain-and GM-CSF-deficient mice

    NARCIS (Netherlands)

    Reed, JA; Ikegami, M; Robb, L; Begley, CG; Ross, G; Whitsett, JA

    Pulmonary alveolar proteinosis (PAP) is caused by inactivation of either granulocyte-macrophage colony-stimulating factor (GMCSF) or GM receptor common beta-chain (beta(c)) genes in mice [GM(-/-), beta(c)(-/-)], demonstrating a critical role of GM-CSF signaling in surfactant homeostasis. To

  16. Polycation–sodium lauryl ether sulfate-type surfactant complexes : influence of ethylene oxide length

    NARCIS (Netherlands)

    Vleugels, L.F.W.; Pollet, J.; Tuinier, R.

    2015-01-01

    Polyelectrolyte-surfactant complexes (PESC) are a class of materials which form spontaneously by self-assembly driven by electrostatic and hydrophobic interactions. PESC containing sodium lauryl ether sulfates (SLES) have found wide application in hair care products like shampoo. Typically, SLES

  17. Polycation-Sodium Lauryl Ether Sulfate-Type Surfactant Complexes : Influence of Ethylene Oxide Length

    NARCIS (Netherlands)

    Vleugels, Leo F. W.; Pollet, Jennifer; Tuinier, Remco

    2015-01-01

    Poiyelectrolyte-surfactant complexes (PESC) are a class of materials which form spontaneously by self-assembly driven by electrostatic and hydrophobic interactions. PESC containing sodium lauryl ether Sulfates (SLES) have found wide application in hair care products like shampoo. Typically, SLES

  18. Self-Assembly of Alkylammonium Chains on Montmorillonite: Effect of Interlayer Cations, CEC, and Chain Length

    Science.gov (United States)

    Chen, Hua; Li, Yingjun; Zhou, Yuanlin; Wang, Shanqiang; Zheng, Jian; He, Jiacai

    2017-12-01

    Recently, polymeric materials have been filled with synthetic or natural inorganic compounds in order to improve their properties. Especially, polymer clay nanocomposites have attracted both academic and industrial attention. Currently, the structure and physical phenomena of organoclays at molecular level are difficultly explained by existing experimental techniques. In this work, molecular dynamics (MD) simulation was executed using the CLAYFF and CHARMM force fields to evaluate the structural properties of organoclay such as basal spacing, interlayer density, energy and the arrangement of alkyl chains in the interlayer spacing. Our results are in good agreement with available experimental or other simulation data. The effects of interlayer cations (Na+, K+, Ca2+), the cation exchange capacity, and the alkyl chain length on the basal spacing and the structural properties are estimated. These simulations are expected to presage the microstructure of organo-montmorillonite and lead relevant engineering applications.

  19. Effects of hydrophobic helix length and side chain chemistry on biomimicry in peptoid analogues of SP-C.

    Science.gov (United States)

    Brown, Nathan J; Wu, Cindy W; Seurynck-Servoss, Shannon L; Barron, Annelise E

    2008-02-12

    The hydrophobic proteins of lung surfactant (LS), SP-B and SP-C, are critical constituents of an effective surfactant replacement therapy for the treatment of respiratory distress syndrome. Because of concerns and difficulties associated with animal-derived surfactants, recent investigations have focused on the creation of synthetic analogues of the LS proteins. However, creating an accurate mimic of SP-C that retains its biophysical surface activity is extraordinarily challenging given the lipopeptide's extreme hydrophobicity and propensity to misfold and aggregate. One successful approach that overcomes these difficulties is the use of poly-N-substituted glycines, or peptoids, to mimic SP-C. To develop a non-natural, bioactive mimic of SP-C and to investigate the effects of side chain chemistry and length of the helical hydrophobic region, we synthesized, purified, and performed in vitro testing of two classes of peptoid SP-C mimics: those having a rigid alpha-chiral aromatic helix and those having a biomimetic alpha-chiral aliphatic helix. The length of the two classes of mimics was also systematically altered. Circular dichroism spectroscopy gave evidence that all of the peptoid-based mimics studied here emulated SP-C's secondary structure, forming stable helical structures in solution. Langmuir-Wilhelmy surface balance, fluorescence microscopy, and pulsating bubble surfactometry experiments provide evidence that the aromatic-based SP-C peptoid mimics, in conjunction with a synthetic lipid mixture, have superior surface activity and biomimetic film morphology in comparison to the aliphatic-based mimics and that there is an increase in surface activity corresponding to increasing helical length.

  20. The roles of productivity and ecosystem size in determining food chain length in tropical terrestrial ecosystems.

    Science.gov (United States)

    Young, Hillary S; McCauley, Douglas J; Dunbar, Robert B; Hutson, Michael S; Ter-Kuile, Ana Miller; Dirzo, Rodolfo

    2013-03-01

    Many different drivers, including productivity, ecosystem size, and disturbance, have been considered to explain natural variation in the length of food chains. Much remains unknown about the role of these various drivers in determining food chain length, and particularly about the mechanisms by which they may operate in terrestrial ecosystems, which have quite different ecological constraints than aquatic environments, where most food chain length studies have been thus far conducted. In this study, we tested the relative importance of ecosystem size and productivity in influencing food chain length in a terrestrial setting. We determined that (1) there is no effect of ecosystem size or productive space on food chain length; (2) rather, food chain length increases strongly and linearly with productivity; and (3) the observed changes in food chain length are likely achieved through a combination of changes in predator size, predator behavior, and consumer diversity along gradients in productivity. These results lend new insight into the mechanisms by which productivity can drive changes in food chain length, point to potential for systematic differences in the drivers of food web structure between terrestrial and aquatic systems, and challenge us to consider how ecological context may control the drivers that shape food chain length.

  1. The effect of the head group on branched-alkyl chain surfactants in glycolipid/n-octane/water ternary system.

    Science.gov (United States)

    Nainggolan, Irwana; Radiman, Shahidan; Hamzah, Ahmad Sazali; Hashim, Rauzah

    2009-10-01

    Two novel glycolipids have been synthesized and their phase behaviour studied. They have been characterized using FT-IR, FAB and 13C NMR and 1H NMR to ensure the purity of novel glycolipids. The two glycolipids are distinguished based on the head group of glycolipids (monosaccharide/glucose and disaccharide/maltose). These two novel glycolipids have been used as surfactant to perform two phase diagrams. Phase behaviours that have been investigated are 2-hexyldecyl-beta-D-glucopyranoside (2-HDG)/n-octane/water ternary system and 2-hexyldecyl-beta-D-maltoside (2-HDM)/n-octane/water ternary system. SAXS and polarizing optical microscope have been used to study the phase behaviours of these two surfactants in ternary phase diagram. Study of effect of the head group on branched-alkyl chain surfactants in ternary system is a strategy to derive the structure-property relationship. For comparison, 2-HDM and 2-HDG have been used as surfactant in the same ternary system. The phase diagram of 2-hexyldecyl-beta-D-maltoside/n-octane/water ternary system exhibited a Lalpha phase at a higher concentration regime, followed with two phases and a micellar solution region in a lower concentration regime. The phase diagram of 2-HDG/water/n-octane ternary system shows hexagonal phase, cubic phase, rectangular ribbon phase, lamellar phase, cubic phase as the surfactant concentration increase.

  2. Structure-guided investigation of lipopolysaccharide O-antigen chain length regulators reveals regions critical for modal length control.

    Science.gov (United States)

    Kalynych, Sergei; Ruan, Xiang; Valvano, Miguel A; Cygler, Miroslaw

    2011-08-01

    The O-antigen component of the lipopolysaccharide (LPS) represents a population of polysaccharide molecules with nonrandom (modal) chain length distribution. The number of the repeat O units in each individual O-antigen polymer depends on the Wzz chain length regulator, an inner membrane protein belonging to the polysaccharide copolymerase (PCP) family. Different Wzz proteins confer vastly different ranges of modal lengths (4 to >100 repeat units), despite having remarkably conserved structural folds. The molecular mechanism responsible for the selective preference for a certain number of O units is unknown. Guided by the three-dimensional structures of PCPs, we constructed a panel of chimeric molecules containing parts of two closely related Wzz proteins from Salmonella enterica and Shigella flexneri which confer different O-antigen chain length distributions. Analysis of the O-antigen length distribution imparted by each chimera revealed the region spanning amino acids 67 to 95 (region 67 to 95), region 200 to 255, and region 269 to 274 as primarily affecting the length distribution. We also showed that there is no synergy between these regions. In particular, region 269 to 274 also influenced chain length distribution mediated by two distantly related PCPs, WzzB and FepE. Furthermore, from the 3 regions uncovered in this study, region 269 to 274 appeared to be critical for the stability of the oligomeric form of Wzz, as determined by cross-linking experiments. Together, our data suggest that chain length determination depends on regions that likely contribute to stabilize a supramolecular complex.

  3. Polyurethanes elastomers with amide chain extenders of uniform length

    NARCIS (Netherlands)

    van der Schuur, J.M.; Noordover, B.A.J.; Noordover, Bart; Gaymans, R.J.

    2006-01-01

    Toluene diisocyanate based polyurethanes with amide extenders were synthesized poly(propylene oxide) with a number average molecular weight of 2000 and endcapped with toluene diisocyanate was used as the polyether segment. The chain extenders were based on poly(hexamethylene terephthalamide):

  4. Polyuretehane elastomers with amide chain extenders of uniform length

    NARCIS (Netherlands)

    Schuur, van der M.; Noordover, B.A.J.; Gaymans, R.J.

    2006-01-01

    Toluene diisocyanate based polyurethanes with amide extenders were synthesized poly(propylene oxide) with a number average molecular weight of 2000 and endcapped with toluene diisocyanate was used as the polyether segment. The chain extenders were based on poly(hexamethylene terephthalamide):

  5. Quantum discord length is enhanced while entanglement length is not by introducing disorder in a spin chain.

    Science.gov (United States)

    Sadhukhan, Debasis; Roy, Sudipto Singha; Rakshit, Debraj; Prabhu, R; Sen De, Aditi; Sen, Ujjwal

    2016-01-01

    Classical correlation functions of ground states typically decay exponentially and polynomially, respectively, for gapped and gapless short-range quantum spin systems. In such systems, entanglement decays exponentially even at the quantum critical points. However, quantum discord, an information-theoretic quantum correlation measure, survives long lattice distances. We investigate the effects of quenched disorder on quantum correlation lengths of quenched averaged entanglement and quantum discord, in the anisotropic XY and XYZ spin glass and random field chains. We find that there is virtually neither reduction nor enhancement in entanglement length while quantum discord length increases significantly with the introduction of the quenched disorder.

  6. Polycation-sodium lauryl ether sulfate-type surfactant complexes: influence of ethylene oxide length.

    Science.gov (United States)

    Vleugels, Leo F W; Pollet, Jennifer; Tuinier, Remco

    2015-05-21

    Polyelectrolyte-surfactant complexes (PESC) are a class of materials which form spontaneously by self-assembly driven by electrostatic and hydrophobic interactions. PESC containing sodium lauryl ether sulfates (SLES) have found wide application in hair care products like shampoo. Typically, SLES with only one or two ethylene oxide (EO) groups are used for this application. We have studied the influence of the size of the EO block (ranging from 0 to 30 EO groups) on complexation with two model polycations: linear polyDADMAC and branched PEI. PESC size and electrostatic properties were determined during stepwise titration of buffered polycation solutions. The critical aggregation concentration (CAC) of PESC was determined by surface tension measurements and fluorescence spectroscopy. For polyDADMAC, there is no influence of the size of the EO block on the complexation behavior; the stiff polycation governs the structure formation. For PEI, it was seen that the EO block size does affect the structure of the complexes. The CAC value of the investigated complexes turns out to be rather independent of the EO block size; however, the CMC/CAC ratio decreases with increasing size of the EO block. This latter observation explains why the Lochhead-Goddard effect is most effective for small EO blocks.

  7. Evaluation of full-length, cleaved and nitrosylated serum surfactant protein D as biomarkers for COPD

    DEFF Research Database (Denmark)

    Duvoix, Annelyse; Miranda, Elena; Perez, Juan

    2011-01-01

    . Serum levels of SP-D are raised in individuals with COPD but there is no correlation between the serum level of SP-D and the severity of airflow obstruction. Serum SP-D is present in different forms that may have more utility as a biomarker for COPD. We report here the development of new monoclonal...... antibodies to full length and cleaved SP-D. We have assessed these and existing antibodies in 98 individuals with COPD recruited to the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) cohort. Our data show that neither monoclonal antibodies to full length nor cleaved SP...

  8. Dependence of the product chain-length on detergents for long-chain E-polyprenyl diphosphate synthases

    Science.gov (United States)

    Pan, Jian-Jung; Ramamoorthy, Gurusankar; Poulter, C. Dale

    2013-01-01

    Long-chain E-polyprenyl diphosphate synthases (E-PDS) catalyze repetitive addition of isopentenyl diphosphate (IPP) to the growing prenyl chain of an allylic diphosphate. The polyprenyl diphosphate products are required for the biosynthesis of ubiquinones and menaquinones required for electron transport during oxidative phosphorylation to generate ATP. In vitro, the long-chain PDSs require addition of phospholipids or detergents to the assay buffer to enhance product release and maintain efficient turnover. During preliminary assays of product chain-length with anionic, zwitterionic, and non-ionic detergents, we discovered considerable variability. Examination of a series of non-ionic PEG detergents with several long-chain E-PDSs from different organisms revealed that in vitro incubations with nonaethylene glycol monododecyl ether or Triton X-100 typically gave chain lengths that corresponded to those of the isoprenoid moieties in respiratory quinones synthesized in vivo. In contrast incubations in buffer with n-butanol, CHAPS, DMSO, n-octyl-β-glucopyranoside, or β-cyclodextrin or in buffer without detergent typically proceeded more slowly and gave a broad range of chain lengths. PMID:23802587

  9. Exploring the impact of the side-chain length on peptide/RNA binding events.

    Science.gov (United States)

    Sbicca, Lola; González, Alejandro López; Gresika, Alexandra; Di Giorgio, Audrey; Closa, Jordi Teixido; Tejedor, Roger Estrada; Andréola, Marie-Line; Azoulay, Stéphane; Patino, Nadia

    2017-07-19

    The impact of the amino-acid side-chain length on peptide-RNA binding events has been investigated using HIV-1 Tat derived peptides as ligands and the HIV-1 TAR RNA element as an RNA model. Our studies demonstrate that increasing the length of all peptide side-chains improves unexpectedly the binding affinity (K D ) but reduces the degree of compactness of the peptide-RNA complex. Overall, the side-chain length appears to modulate in an unpredictable way the ability of the peptide to compete with the cognate TAR RNA partner. Beyond the establishment of non-intuitive fundamental relationships, our results open up new perspectives in the design of effective RNA ligand competitors, since a large number of them have already been identified but few studies report on the modulation of the biological activity by modifying in the same way the length of all chains connecting RNA recognition motives to the central scaffold of a ligand.

  10. Novel odd/even effect of alkylene chain length on the photopolymerizability of organogelators.

    Science.gov (United States)

    Aoki, Ken'ichi; Kudo, Masabumi; Tamaoki, Nobuyuki

    2004-10-28

    [reaction: see text] Starting from diactylene diacarboxylic acids, we have synthesized a series of photopolymerizable organogelators that possess simple amide structures, different alkylene chain lengths, and either optically active or racemic 3,7-dimethyl-1-octylamine units. The alkylene chain length of these compounds exhibits a prominent odd/even effect with respect to the photopolymerization in the gel state and is accompanied by a stereostructural effect on the gelation ability.

  11. Adsorption of dimeric surfactants in lamellar silicates

    Energy Technology Data Exchange (ETDEWEB)

    Balcerzak, Mateusz; Pietralik, Zuzanna [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Domka, Ludwik [Department of Metalorganic Chemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań (Poland); Skrzypczak, Andrzej [Institute of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań (Poland); Kozak, Maciej, E-mail: mkozak@amu.edu.pl [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

    2015-12-01

    Highlights: • The intercalation of dimeric surfactants changed the morphology of MMT samples. • XRD indicated structures formed by surfactant molecules in interlayer space. • The four-step thermal decomposition of dimeric surfactant, confirms intercalation. - Abstract: The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay – hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1′-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d{sub 001}) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH{sub 2} and CH{sub 3} groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  12. Effect of Gemini-type surfactant on methane hydrate formation

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, K.E.; Park, J.M.; Kim, C.U.; Chae, H.J.; Jeong, S.Y. [Korea Research Inst. of Chemical Technology, Jang-Dong, Yuseong-Gu, Daejeon (Korea, Republic of)

    2008-07-01

    Natural gas hydrates are formed from water and natural gas molecules at particular temperatures and pressures that become ice-like inclusion compounds. Gas hydrates offer several benefits such as energy resource potential and high storage capacity of natural gas in the form of hydrates. However, the application of natural gas hydrates has been deterred by its low formation rate and low conversion ratio of water into hydrate resulting in low actual storage capacity. This paper presented an experimental study to determine the effect of adding a novel Gemini-type surfactant on methane hydrate formation. The experimental study was described with reference to the properties of prepared diols and properties of prepared disulfonates. Gemini surfactant is the family of surfactant molecules possessing more than one hydrophobic tail and hydrophilic head group. They generally have better surface-active properties than conventional surfactants of equal chain length. The paper presented the results of the study in terms of the reactions of diols with propane sultone; storage capacity of hydrate formed with and without surfactant; and methane hydrate formation with and without disulfonate. It was concluded that the methane hydrate formation was accelerated by the addition of novel anionic Gemini-type surfactants and that hydrate formation was influenced by the surfactant concentration and alkyl chain length. For a given concentration, the surfactant with the highest chain length demonstrated the highest formation rate and storage capacity. 5 refs., 3 tabs., 4 figs.

  13. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    International Nuclear Information System (INIS)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-01-01

    oleylamine (OLAm), but only flat nanoplates are observed in the products in the presence of OTAm at 120 °C. The results indicate that the lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr_3 NCs. This work opens up an alternative approach to controllable-synthesis of perovskite NCs through varying the carbon chain length of organic surfactants, and enlightens the fabrication of different nanostructures via self-assembly methods for further optoelectronic applications.

  14. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei, E-mail: awtang@bjtu.edu.cn

    2017-05-31

    product synthesized in the presence of oleylamine (OLAm), but only flat nanoplates are observed in the products in the presence of OTAm at 120 °C. The results indicate that the lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr{sub 3} NCs. This work opens up an alternative approach to controllable-synthesis of perovskite NCs through varying the carbon chain length of organic surfactants, and enlightens the fabrication of different nanostructures via self-assembly methods for further optoelectronic applications.

  15. Resonance chains in open systems, generalized zeta functions and clustering of the length spectrum

    International Nuclear Information System (INIS)

    Barkhofen, S; Faure, F; Weich, T

    2014-01-01

    In many non-integrable open systems in physics and mathematics, resonances have been found to be surprisingly ordered along curved lines in the complex plane. In this article we provide a unifying approach to these resonance chains by generalizing dynamical zeta functions. By means of a detailed numerical study we show that these generalized zeta functions explain the mechanism that creates the chains of quantum resonance and classical Ruelle resonances for three-disk systems as well as geometric resonances on Schottky surfaces. We also present a direct system-intrinsic definition of the continuous lines on which the resonances are strung together as a projection of an analytic variety. Additionally, this approach shows that the existence of resonance chains is directly related to a clustering of the classical length spectrum on multiples of a base length. Finally, this link is used to construct new examples where several different structures of resonance chains coexist. (paper)

  16. Effect of hydrocarbon chain length of aliphatic diluents on hydrodynamic properties of irradiated solutions of extractant

    International Nuclear Information System (INIS)

    Gumenyuk, V.E.; Pribush, A.G.; Egorov, G.F.

    1990-01-01

    To optimize the composition of n-paraffin mixtures with different molecular weight, used as a diluent (D) of extractant during extraction reprocessing of spent fuel, interrelation between D hydrocarbon chain length and change in hydrodynamic properties of extraction mixture on D basis depending on the dose has been considered. It is shown that the value of threshold dose loading (D crit ), at which a sharp change in hydrodynamic properties of tri-n-butyl phosphate solutions in D is observed, decreases with hydrocarbon chain length growth. Empiric ratio relating D crit value and the number of carbon atoms of D is obtained

  17. Knotting dynamics of DNA chains of different length confined in nanochannels

    International Nuclear Information System (INIS)

    Suma, Antonio; Micheletti, Cristian; Orlandini, Enzo

    2015-01-01

    Langevin dynamics simulations are used to characterize the typical mechanisms governing the spontaneous tying, untying and the dynamical evolution of knots in coarse-grained models of DNA chains confined in nanochannels. In particular we focus on how these mechanisms depend on the chain contour length, L c , at a fixed channel width D = 56 nm corresponding to the onset of the Odijk scaling regime where chain backfoldings and hence knots are disfavoured but not suppressed altogether. We find that the lifetime of knots grows significantly with L c , while that of unknots varies to a lesser extent. The underlying kinetic mechanisms are clarified by analysing the evolution of the knot position along the chain. At the considered confinement, in fact, knots are typically tied by local backfoldings of the chain termini where they are eventually untied after a stochastic motion along the chain. Consequently, the lifetime of unknots is mostly controlled by backfoldings events at the chain ends, which is largely independent of L c . The lifetime of knots, instead, increases significantly with L c because knots can, on average, travel farther along the chain before being untied. The observed interplay of knots and unknots lifetimes underpins the growth of the equilibrium knotting probability of longer and longer chains at fixed channel confinement. (paper)

  18. Direct observation of the edge spin structure and chain length dependence of a finite haldane chain by high field ESR measurements

    International Nuclear Information System (INIS)

    Yoshida, Makoto; Ohta, Hitoshi; Ito, Toshimitsu; Ajiro, Yoshitami

    2006-01-01

    We have performed high field and multi-frequency ESR measurements of finite length S=1 antiferromagnetic chains in Y 2 BaNi 0.96 Mg 0.04 O 5 . Owing to the high spectral resolution by high fields and high frequencies, observed ESR signals can be separated into the contributions of the finite chains with various chain lengths. Our results clearly show that the edge spins actually interact with each other through the quantum spin chain and the interaction depends on the chain length N. (author)

  19. Effect of surfactant types and their concentration on the structural characteristics of nanoclay

    Science.gov (United States)

    Zawrah, M. F.; Khattab, R. M.; Saad, E. M.; Gado, R. A.

    2014-03-01

    A series of organo-modified nanoclays was synthesized using three different surfactants having different alkyl chain lengths and concentrations [0.5-5.0 cation exchange capacity (CEC)]. These surfactants were Ethanolamine (EA), Cetyltrimethylammoniumbromide (CTAB) and Tetraoctadecylammoniumbromide (TO). The obtained modified nanoclays were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) and compared with unmodified nanoclay. The results of XRD analysis indicated that the basal d-spacing has increased with increasing alkyl chain length and surfactant concentration. From the obtained microstructures of these organo-modified nanoclays, the mechanism of surfactant adsorption was proposed. At relatively low loading of surfactant, most of surfactant entered the spacing by an ion-exchange mechanism and is adsorbed onto the interlayer cation sites. When the concentration of the surfactant exceeds the CEC of clay, the surfactant molecules then adhere to the surface adsorbed surfactant. Some surfactants entered the interlayers, whereas the others were attached to the clay surface. When the concentration of surfactant increased further beyond 2.0 CEC, the surfactants might occupy the inter-particle space within the house-of-cards aggregate structure.

  20. Characterization of Binary Organogels Based on Some Azobenzene Compounds and Alkyloxybenzoic Acids with Different Chain Lengths

    Directory of Open Access Journals (Sweden)

    Yongmei Hu

    2014-01-01

    Full Text Available In this work the gelation behaviors of binary organogels composed of azobenzene amino derivatives and alkyloxybenzoic acids with different lengths of alkyl chains in various organic solvents were investigated and characterized. The corresponding gelation behaviors in 20 solvents were characterized and shown as new binary organic systems. It showed that the lengths of substituent alkyl chains in compounds have played an important role in the gelation formation of gelator mixtures in present tested organic solvents. Longer methylene chains in molecular skeletons in these gelators seem more suitable for the gelation of present solvents. Morphological characterization showed that these gelator molecules have the tendency to self-assemble into various aggregates from lamella, wrinkle, and belt to dot with change of solvents and gelator mixtures. Spectral characterization demonstrated different H-bond formation and hydrophobic force existing in gels, depending on different substituent chains in molecular skeletons. Meanwhile, these organogels can self-assemble to form monomolecular or multilayer nanostructures owing to the different lengths of due to alkyl substituent chains. Possible assembly modes for present xerogels were proposed. The present investigation is perspective to provide new clues for the design of new nanomaterials and functional textile materials with special microstructures.

  1. Vaporization enthalpies of imidazolium based ionic liquids. A thermogravimetric study of the alkyl chain length dependence

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Zaitsau, Dzmitry H.; Emel’yanenko, Vladimir N.; Ralys, Ricardas V.; Yermalayeu, Andrei V.; Schick, Christoph

    2012-01-01

    Highlights: ► Enthalpies of vaporization of ionic liquids were measured with thermogravimetry. ► We studied 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide. ► The linear alkyl chain length was 4, 6, 8, 10, 12, 14, 16, and 18 C-atoms. ► A linear dependence on the chain length of the alkyl-imidazolium cation was found. - Abstract: Vaporization enthalpies for a series of ten ionic liquids (ILs) 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide [C n mim][NTf 2 ], with the alkyl chain length n = 4, 6, 8, 10, 12, 14, 16, and 18 were determined using the thermogravimetric method. An internally consistent set of experimental data and vaporization enthalpies at 540 K was obtained. Vaporization enthalpies at 540 K have shown a linear dependence on the chain length of the alkyl-imidazolium cation in agreement with the experimental results measured previously with a quartz crystal microbalance. Ambiguity of Δ l g C pm o -values required for the extrapolation of experimental vaporization enthalpies to the reference temperature 298 K has been discussed.

  2. Biosynthesis of medium chain length alkanes for bio-aviation fuel by metabolic engineered Escherichia coli.

    Science.gov (United States)

    Wang, Meng; Nie, Kaili; Cao, Hao; Xu, Haijun; Fang, Yunming; Tan, Tianwei; Baeyens, Jan; Liu, Luo

    2017-09-01

    The aim of this work was to study the synthesis of medium-chain length alkanes (MCLA), as bio-aviation product. To control the chain length of alkanes and increase the production of MCLA, Escherichia coli cells were engineered by incorporating (i) a chain length specific thioesterase from Umbellularia californica (UC), (ii) a plant origin acyl carrier protein (ACP) gene and (iii) the whole fatty acid synthesis system (FASs) from Jatropha curcas (JC). The genetic combination was designed to control the product spectrum towards optimum MCLA. Decanoic, lauric and myristic acid were produced at concentrations of 0.011, 0.093 and 1.657mg/g, respectively. The concentration of final products nonane, undecane and tridecane were 0.00062mg/g, 0.0052mg/g, and 0.249mg/g respectively. Thioesterase from UC controlled the fatty acid chain length in a range of 10-14 carbons and the ACP gene with whole FASs from JC significantly increased the production of MCLA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. The effect of chain length and lipid phase transitions on the selective permeability properties of liposomes

    NARCIS (Netherlands)

    Blok, M.C.; Neut-Kok, E.C.M. van der; Deenen, L.L.M. van; Gier, J. de

    1975-01-01

    This paper describes experiments showing the importance of the fatty acid chain length on the barrier properties of liposomal bilayers, prepared from saturated lecithins, under conditions of lateral phase separation. 1. 1.|Above the gel to liquid crystalline phase transition temperature,

  4. The importance of chain length for the polyphosphate enhancement of acidic potassium permanganate chemiluminescence.

    Science.gov (United States)

    Holland, Brendan J; Adcock, Jacqui L; Nesterenko, Pavel N; Peristyy, Anton; Stevenson, Paul G; Barnett, Neil W; Conlan, Xavier A; Francis, Paul S

    2014-09-09

    Sodium polyphosphate is commonly used to enhance chemiluminescence reactions with acidic potassium permanganate through a dual enhancement mechanism, but commercially available polyphosphates vary greatly in composition. We have examined the influence of polyphosphate composition and concentration on both the dual enhancement mechanism of chemiluminescence intensity and the stability of the reagent under analytically useful conditions. The average chain length (n) provides a convenient characterisation, but materials with similar values can exhibit markedly different distributions of phosphate oligomers. There is a minimum polyphosphate chain length (∼6) required for a large enhancement of the emission intensity, but no further advantage was obtained using polyphosphate materials with much longer average chain lengths. Providing there is a sufficient average chain length, the optimum concentration of polyphosphate is dependent on the analyte and in some cases, may be lower than the quantities previously used in routine detection. However, the concentration of polyphosphate should not be lowered in permanganate reagents that have been partially reduced to form high concentrations of the key manganese(III) co-reactant, as this intermediate needs to be stabilised to prevent formation of insoluble manganese(IV). Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Modification of eucalyptus pulp fiber using silane coupling agents with aliphatic side chains of different length

    Science.gov (United States)

    The objective of this work was to evaluate the effect of three silane coupling agents with different aliphatic chain lengths on the hydrophobicity of eucalyptus pulp fiber. The three silanes coupling agents used (isobutyltrimethoxysilane, methyltrimethoxysilane, and n-octyltriethoxysilane [OTES]) we...

  6. effect of side chain length on the stability and structural properties of 3

    African Journals Online (AJOL)

    Preferred Customer

    We report on the effect of the alkoxy chain length on the thermodynamic ... studied by Hartree-Fock (HF) and Density Functional Theory (DFT) methods. ..... with longer alkoxy substituents on the phenyl ring have lesser value of change in Gibbs ...

  7. Chain length distribution and kinetic characteristics of an enzymatically produced polymer

    NARCIS (Netherlands)

    Mulders, K.J.M.; Beeftink, H.H.

    2013-01-01

    Non-processive enzymatic polymerization leads to a distribution of polymer chain lengths. A polymerization model was developed to investigate the relation between the extent of this distribution on one hand, and the polymerization start conditions and reaction kinetics on the other hand. The model

  8. Characterization of amylose nanoparticles prepared via nanoprecipitation: Influence of chain length distribution.

    Science.gov (United States)

    Chang, Yanjiao; Yang, Jingde; Ren, Lili; Zhou, Jiang

    2018-08-15

    The influence of chain length distribution of amylose on size and structure of the amylose nanoparticles (ANPs) prepared through nanoprecipitation was investigated. Amylose with different chain length distributions was obtained by β-amylase treating amylose paste for different times and measured by size exclusion chromatography (SEC) and fluorophore-assisted carbohydrate electrophoresis (FACE). ANPs prepared via precipitation were characterized by using dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that the β-amylase treatments led to decrease in chain length of amylose, and it was the most important factor affecting size of ANPs. When hydrolysis degree of amylose was 52.8%, mean size of ANPs decreased from 206.4 nm to 102.7 nm. All the ANPs displayed a V-type crystalline structure and the effect of amylose chain length on crystallinity of the precipitated ANPs was negligible in the investigated range. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Phase transitions in surfactant monolayers

    International Nuclear Information System (INIS)

    Casson, B.D.

    1998-01-01

    Two-dimensional phase transitions have been studied in surfactant monolayers at the air/water interface by sum-frequency spectroscopy and ellipsometry. In equilibrium monolayers of medium-chain alcohols C n H 2n+1 OH (n = 9-14) a transition from a two-dimensional crystalline phase to a liquid was observed at temperatures above the bulk melting point. The small population of gauche defects in the solid phase increased only slightly at the phase transition. A model of the hydrocarbon chains as freely rotating rigid rods allowed the area per molecule and chain tilt in the liquid phase to be determined. The area per molecule, chain tilt and density of the liquid phase all increased with increasing chain length, but for each chain length the density was higher than in a bulk liquid hydrocarbon. In a monolayer of decanol adsorbed at the air/water interface a transition from a two-dimensional liquid to a gas was observed. A clear discontinuity in the coefficient of ellipticity as a function of temperature showed that the transition is first-order. This result suggests that liquid-gas phase transitions in surfactant monolayers may be more widespread than once thought. A solid-liquid phase transition has also been studied in mixed monolayers of dodecanol with an anionic surfactant (sodium dodecyl sulphate) and with a homologous series of cationic surfactants (alkyltrimethylammonium bromides: C n TABs, n = 12, 14, 16). The composition and structure of the mixed monolayers was studied above and below the phase transition. At low temperatures the mixed monolayers were as densely packed as a monolayer of pure dodecanol in its solid phase. At a fixed temperature the monolayers under-went a first-order phase transition to form a phase that was less dense and more conformationally disordered. The proportion of ionic surfactant in the mixed monolayer was greatest in the high temperature phase. As the chain length of the C n TAB increased the number of conformational defects

  10. Photoluminescence decay lifetime measurements of hemicyanine derivatives of different alkyl chain lengths

    International Nuclear Information System (INIS)

    Shim, Taekyu; Lee, Myounghee; Kim, Sungho; Sung, Jaeho; Rhee, Bum Ku; Kim, Doseok; Kim, Hyunsung; Yoon, Kyung Byung

    2004-01-01

    The fluorescence upconversion setup for the detection of photoluminescence (PL) decay lifetime with subpicosecond time resolution was constructed, and the photoluminescence phenomena of several hemicyanine dyes with alkyl chains of different chain lengths tethered to the N atom of the pyridine moiety (HC-n, n=6, 15, 22) in methanol were investigated. The average decay lifetimes of the solutions determined from the measured data by multi-order exponential decay curve fitting were ∼27 ps at the PL peak wavelength. It was found that the PL decay properties did not depend on the alkyl chain length in the molecule, implying that the twist of the alkylpyridinium ring of the molecule is not possible as a nonfluorescing relaxation pathway. The time-dependent PL spectra constructed from the PL lifetime data showed the dynamic Stokes shift of ∼1000 cm -1

  11. Infinite coherence time of edge spins in finite-length chains

    Science.gov (United States)

    Maceira, Ivo A.; Mila, Frédéric

    2018-02-01

    Motivated by the recent observation that exponentially long coherence times can be achieved for edge spins in models with strong zero modes, we study the impact of level crossings in finite-length spin chains on the dynamics of the edge spins. Focusing on the X Y spin-1 /2 chain with a transverse or longitudinal magnetic field, two models relevant to understanding recent experimental results on cobalt adatoms, we show that the edge spins can remain coherent for an infinite time even for a finite-length chain if the magnetic field is tuned to a value at which there is a level crossing. Furthermore, we show that the edge spins remain coherent for any initial state for the integrable case of a transverse field because all states have level crossings at the same value of the field, while the coherence time is increasingly large for lower temperatures in the case of a longitudinal field, which is nonintegrable.

  12. PEGylation on mixed monolayer gold nanoparticles: Effect of grafting density, chain length, and surface curvature.

    Science.gov (United States)

    Lin, Jiaqi; Zhang, Heng; Morovati, Vahid; Dargazany, Roozbeh

    2017-10-15

    PEGylation on nanoparticles (NPs) is widely used to prevent aggregation and to mask NPs from the fast clearance system in the body. Understanding the molecular details of the PEG layer could facilitate rational design of PEGylated NPs that maximize their solubility and stealth ability without significantly compromising the targeting efficiency and cellular uptake. Here, we use molecular dynamics (MD) simulation to understand the structural and dynamic the PEG coating of mixed monolayer gold NPs. Specifically, we modeled gold NPs with PEG grafting densities ranging from 0-2.76chain/nm 2 , chain length with 0-10 PEG monomers, NP core diameter from 5nm to 500nm. It is found that the area accessed by individual PEG chains gradually transits from a "mushroom" to a "brush" conformation as NP surface curvature become flatter, whereas such a transition is not evident on small NPs when grafting density increases. It is shown that moderate grafting density (∼1.0chain/nm 2 ) and short chain length are sufficient enough to prevent NPs from aggregating in an aqueous medium. The effect of grafting density on solubility is also validated by dynamic light scattering measurements of PEGylated 5nm gold NPs. With respect to the shielding ability, simulations predict that increase either grafting density, chain length, or NP diameter will reduce the accessibility of the protected content to a certain size molecule. Interestingly, reducing NP surface curvature is estimated to be most effective in promoting shielding ability. For shielding against small molecules, increasing PEG grafting density is more effective than increasing chain length. A simple model that includes these three investigated parameters is developed based on the simulations to roughly estimate the shielding ability of the PEG layer with respect to molecules of different sizes. The findings can help expand our current understanding of the PEG layer and guide rational design of PEGylated gold NPs for a particular

  13. Optimization of the alkyl side chain length of fluorine-18-labeled 7α-alkyl-fluoroestradiol

    International Nuclear Information System (INIS)

    Okamoto, Mayumi; Shibayama, Hiromitsu; Naka, Kyosuke; Kitagawa, Yuya; Ishiwata, Kiichi; Shimizu, Isao; Toyohara, Jun

    2016-01-01

    Introduction: Several lines of evidence suggest that 7α-substituted estradiol derivatives bind to the estrogen receptor (ER). In line with this hypothesis, we designed and synthesized 18 F-labeled 7α-fluoroalkylestradiol (Cn-7α-[ 18 F]FES) derivatives as molecular probes for visualizing ERs. Previously, we successfully synthesized 7α-(3-[ 18 F]fluoropropyl)estradiol (C3-7α-[ 18 F]FES) and showed promising results for quantification of ER density in vivo, although extensive metabolism was observed in rodents. Therefore, optimization of the alkyl side chain length is needed to obtain suitable radioligands based on Cn-7α-substituted estradiol pharmacophores. Methods: We synthesized fluoromethyl (23; C1-7α-[ 18 F]FES) to fluorohexyl (26; C6-7α-[ 18 F]FES) derivatives, except fluoropropyl (C3-7α-[ 18 F]FES) and fluoropentyl derivatives (C5-7α-[ 18 F]FES), which have been previously synthesized. In vitro binding to the α-subtype (ERα) isoform of ERs and in vivo biodistribution studies in mature female mice were carried out. Results: The in vitro IC 50 value of Cn-7α-FES tended to gradually decrease depending on the alkyl side chain length. C1-7α-[ 18 F]FES (23) showed the highest uptake in ER-rich tissues such as the uterus. Uterus uptake also gradually decreased depending on the alkyl side chain length. As a result, in vivo uterus uptake reflected the in vitro ERα affinity of each compound. Bone uptake, which indicates de-fluorination, was marked in 7α-(2-[ 18 F]fluoroethyl)estradiol (C2-7α-[ 18 F]FES) (24) and 7α-(4-[ 18 F]fluorobutyl)estradiol (C4-7α-[ 18 F]FES) (25) derivatives. However, C1-7α-[ 18 F]FES (23) and C6-7α-[ 18 F]FES (26) showed limited uptake in bone. As a result, in vivo bone uptake (de-fluorination) showed a bell-shaped pattern, depending on the alkyl side chain length. C1-7α-[ 18 F]FES (23) showed the same levels of uptake in uterus and bone compared with those of 16α-[ 18 F]fluoro-17β-estradiol. Conclusions: The optimal alkyl

  14. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Science.gov (United States)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-05-01

    All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr3 NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55-80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr3 NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of oleylamine (OLAm), but only flat nanoplates are observed in the products in the presence of OTAm at 120 °C. The results indicate that the lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr3 NCs. This work opens up an alternative approach to controllable-synthesis of perovskite NCs through varying the carbon chain length of organic surfactants, and enlightens

  15. Dependence of adenine isolation efficiency on the chain length evidenced using paramagnetic particles and voltammetry measurements

    Energy Technology Data Exchange (ETDEWEB)

    Huska, Dalibor [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Adam, Vojtech [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Department of Animal Nutrition and Forage Production, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Trnkova, Libuse [Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Kizek, Rene [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic)], E-mail: kizek@sci.muni.cz

    2009-05-15

    The main aim of this work was to study the dependence of oligoadenine isolation efficiency on the chain length by using paramagnetic particles covered by homo-deoxythymidines ((dT)25) with subsequent detection by adsorptive transfer technique coupled with square wave voltammetry. For this purpose, the oligonucleotides of the length A5, A10, A15, A20, A25, A30, A35, A40 and poly(A) in various concentrations were chosen. We determined that the isolation efficiency defined as 'isolated oligonucleotide concentration'/'given oligonucleotide concentration' was about 55% on average. Sequence A25 demonstrated the best binding onto microparticles surface.

  16. Dependence of adenine isolation efficiency on the chain length evidenced using paramagnetic particles and voltammetry measurements

    International Nuclear Information System (INIS)

    Huska, Dalibor; Adam, Vojtech; Trnkova, Libuse; Kizek, Rene

    2009-01-01

    The main aim of this work was to study the dependence of oligoadenine isolation efficiency on the chain length by using paramagnetic particles covered by homo-deoxythymidines ((dT)25) with subsequent detection by adsorptive transfer technique coupled with square wave voltammetry. For this purpose, the oligonucleotides of the length A5, A10, A15, A20, A25, A30, A35, A40 and poly(A) in various concentrations were chosen. We determined that the isolation efficiency defined as 'isolated oligonucleotide concentration'/'given oligonucleotide concentration' was about 55% on average. Sequence A25 demonstrated the best binding onto microparticles surface.

  17. Influence of the chain length on the biological behaviour of 131I fatty acids

    International Nuclear Information System (INIS)

    Riche, F.; Mathieu, J.P.; Comet, M.; Vidal, M.; Pernin, C.; Marti-Batlle, D.; Busquet, G.; Bardy, A.

    1983-01-01

    Saturated and acetylenic fatty acids labeled with 131 I in ω position, differing by their chain length (C8 to C20) and the number odd or even of their carbon atoms are injected in mice. The evolution of the activity in myocardium, blood, liver and kidney is measured until 10 minutes after injection. The myocardial activity increases with chain length from C8 to C16 then decreases for C18 and C20. The odd or even number of carbon atoms does not influence myocardial activity but in the liver, activity is inferior with the odd fatty acids. The presence of a triple bond accelerates the output of activity from the myocardium and these fatty acids are not well suited for the study of myocardial metabolism [fr

  18. Influence of the chain length on the biological behaviour of /sup 131/I fatty acids

    Energy Technology Data Exchange (ETDEWEB)

    Riche, F.; Mathieu, J.P.; Comet, M.; Vidal, M.; Pernin, C.; Marti-Batlle, D.; Busquet, G. (Universite de Grenoble, 38 (France)); Bardy, A. (C.E.A.-ORIS, 91 - Gif-sur-Yvette (France))

    1983-01-01

    Saturated and acetylenic fatty acids labeled with /sup 131/I in ..omega.. position, differing by their chain length (C8 to C20) and the number odd or even of their carbon atoms are injected in mice. The evolution of the activity in myocardium, blood, liver and kidney is measured until 10 minutes after injection. The myocardial activity increases with chain length from C8 to C16 then decreases for C18 and C20. The odd or even number of carbon atoms does not influence myocardial activity but in the liver, activity is inferior with the odd fatty acids. The presence of a triple bond accelerates the output of activity from the myocardium and these fatty acids are not well suited for the study of myocardial metabolism.

  19. Communication disruption of guava moth (Coscinoptycha improbana) using a pheromone analog based on chain length.

    Science.gov (United States)

    Suckling, D M; Dymock, J J; Park, K C; Wakelin, R H; Jamieson, L E

    2013-09-01

    The guava moth, Coscinoptycha improbana, an Australian species that infests fruit crops in commercial and home orchards, was first detected in New Zealand in 1997. A four-component pheromone blend was identified but is not yet commercially available. Using single sensillum recordings from male antennae, we established that the same olfactory receptor neurons responded to two guava moth sex pheromone components, (Z)-11-octadecen-8-one and (Z)-12-nonadecen-9-one, and to a chain length analog, (Z)-13-eicosen-10-one, the sex pheromone of the related peach fruit moth, Carposina sasakii. We then field tested whether this non-specificity of the olfactory neurons might enable disruption of sexual communication by the commercially available analog, using male catch to synthetic lures in traps in single-tree, nine-tree and 2-ha plots. A disruptive pheromone analog, based on chain length, is reported for the first time. Trap catches for guava moth were disrupted by three polyethylene tubing dispensers releasing the analog in single-tree plots (86% disruption of control catches) and in a plots of nine trees (99% disruption). Where peach fruit moth pheromone dispensers were deployed at a density of 1000/ha in two 2-ha areas, pheromone traps for guava moth were completely disrupted for an extended period (up to 470 days in peri-urban gardens in Mangonui and 422 days in macadamia nut orchards in Kerikeri). In contrast, traps in untreated areas over 100 m away caught 302.8 ± 128.1 moths/trap in Mangonui and 327.5 ± 78.5 moths/ trap in Kerikeri. The longer chain length in the pheromone analog has greater longevity than the natural pheromone due to its lower volatility. Chain length analogs may warrant further investigation for mating disruption in Lepidoptera, and screening using single-sensillum recording is recommended.

  20. Productivity, Disturbance and Ecosystem Size Have No Influence on Food Chain Length in Seasonally Connected Rivers

    OpenAIRE

    Warfe, Danielle M.; Jardine, Timothy D.; Pettit, Neil E.; Hamilton, Stephen K.; Pusey, Bradley J.; Bunn, Stuart E.; Davies, Peter M.; Douglas, Michael M.

    2013-01-01

    The food web is one of the oldest and most central organising concepts in ecology and for decades, food chain length has been hypothesised to be controlled by productivity, disturbance, and/or ecosystem size; each of which may be mediated by the functional trophic role of the top predator. We characterised aquatic food webs using carbon and nitrogen stable isotopes from 66 river and floodplain sites across the wet-dry tropics of northern Australia to determine the relative importance of produ...

  1. The Effect of the Chain Length on MMA Free Radicl Polymerization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the polymerization process of methyl methacrylate (MMA), the Arrhenius parameters (activation energy and frequency factor) of propagating reaction monotonically decrease with increasing monomer conversion. At the beginning and middle stage of the propagating reaction, the increase of radical chain length is the main reason of above mentioned change. And at the end stage, the sharp decrease of kp indicates that the activation energy is approximately incline to zero and the propagating reaction is controlled by molecular diffusion motion.

  2. Effect of side chain length on charge transport, morphology, and photovoltaic performance of conjugated polymers in bulk heterojunction solar cells

    NARCIS (Netherlands)

    Duan, C.; Willems, R.E.M.; van Franeker, J.J.; Bruijnaers, B.J.; Wienk, M.M.; Janssen, R.A.J.

    2016-01-01

    The effect of side chain length on the photovoltaic properties of conjugated polymers is systematically investigated with two sets of polymers that bear different alkyl side chain lengths based on benzodithiophene and benzo[2,1,3]thiadiazole or 5,6-difluorobenzo[2,1,3]thiadiazole. Characterization

  3. The interactions between ionic surfactants and phosphatidylcholine vesicles: Conductometry

    Science.gov (United States)

    Tsao, Heng-Kwong; Tseng, Wen Liang

    2001-11-01

    The interaction between ionic surfactants and phosphatidylcholine vesicles, which are prepared without addition of buffer and salt, is investigated by conductivity measurements. On the basis of the vesicle acting as a trap of charge carriers, the bilayer/aqueous phase partition coefficient K and the surfactant/lipid molar ratio Re of nine surfactants are determined. The thermodynamic consistency is satisfied by the measured parameters. The effects of the alkyl chain length (C10-C16) and ionic head group are then studied. The inverse partition coefficient K-1 is linearly related to the critical micelle concentration. The solubilizing ability Reb is a consequence of the competition between the surfactant incorporation into the bilayer and the formation of micelles. Consequently, the K parameter rises whereas the Reb parameter declines as the chain length is increased. The influence due to addition of salt is also discussed.

  4. Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease.

    Science.gov (United States)

    Nitschke, Felix; Sullivan, Mitchell A; Wang, Peixiang; Zhao, Xiaochu; Chown, Erin E; Perri, Ami M; Israelian, Lori; Juana-López, Lucia; Bovolenta, Paola; Rodríguez de Córdoba, Santiago; Steup, Martin; Minassian, Berge A

    2017-07-01

    Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss-of-function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bodies (LBs). The leading LD hypothesis that hyperphosphorylation causes the insolubility was recently challenged by the observation that phosphatase-inactive laforin rescues the laforin-deficient LD mouse model, apparently through correction of a general autophagy impairment. We were for the first time able to quantify brain glycogen phosphate. We also measured glycogen content and chain lengths, LBs, and autophagy markers in several laforin- or malin-deficient mouse lines expressing phosphatase-inactive laforin. We find that: (i) in laforin-deficient mice, phosphatase-inactive laforin corrects glycogen chain lengths, and not hyperphosphorylation, which leads to correction of glycogen amounts and prevention of LBs; (ii) in malin-deficient mice, phosphatase-inactive laforin confers no correction; (iii) general impairment of autophagy is not necessary in LD We conclude that laforin's principle function is to control glycogen chain lengths, in a malin-dependent fashion, and that loss of this control underlies LD. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  5. Productivity, disturbance and ecosystem size have no influence on food chain length in seasonally connected rivers.

    Science.gov (United States)

    Warfe, Danielle M; Jardine, Timothy D; Pettit, Neil E; Hamilton, Stephen K; Pusey, Bradley J; Bunn, Stuart E; Davies, Peter M; Douglas, Michael M

    2013-01-01

    The food web is one of the oldest and most central organising concepts in ecology and for decades, food chain length has been hypothesised to be controlled by productivity, disturbance, and/or ecosystem size; each of which may be mediated by the functional trophic role of the top predator. We characterised aquatic food webs using carbon and nitrogen stable isotopes from 66 river and floodplain sites across the wet-dry tropics of northern Australia to determine the relative importance of productivity (indicated by nutrient concentrations), disturbance (indicated by hydrological isolation) and ecosystem size, and how they may be affected by food web architecture. We show that variation in food chain length was unrelated to these classic environmental determinants, and unrelated to the trophic role of the top predator. This finding is a striking exception to the literature and is the first published example of food chain length being unaffected by any of these determinants. We suggest the distinctive seasonal hydrology of northern Australia allows the movement of fish predators, linking isolated food webs and potentially creating a regional food web that overrides local effects of productivity, disturbance and ecosystem size. This finding supports ecological theory suggesting that mobile consumers promote more stable food webs. It also illustrates how food webs, and energy transfer, may function in the absence of the human modifications to landscape hydrological connectivity that are ubiquitous in more populated regions.

  6. Effect of the alkyl chain length of the ionic liquid anion on polymer electrolytes properties

    International Nuclear Information System (INIS)

    Leones, Rita; Sentanin, Franciani; Nunes, Sílvia Cristina; Esperança, José M.S.S.; Gonçalves, Maria Cristina

    2015-01-01

    New polymer electrolytes (PEs) based on chitosan and three ionic liquid (IL) families ([C 2 mim][C n SO 3 ], [C 2 mim][C n SO 4 ] and [C 2 mim][diC n PO 4 ]) were synthesized by the solvent casting method. The effect of the length of the alkyl chain of the IL anion on the thermal, morphological and electrochemical properties of the PEs was studied. The solid polymer electrolytes SPE membranes were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), polarized optical microscopy (POM), atomic force microscopy (AFM), complex impedance spectroscopy (ionic conductivity) and cyclic voltammetry (CV). The obtained results evidenced an influence of the alkyl chain length of the IL anion on the temperature of degradation, birefringence, surface roughness and ionic conductivity of the membranes. The DSC, XRD and CV results showed independency from the length of the IL-anion-alkyl chain. The PEs displayed an predominantly amorphous morphology, a minimum temperature of degradation of 135 °C, a room temperature (T = 25 °C) ionic conductivity of 7.78 × 10 −4 S cm −1 and a wide electrochemical window of ∼ 4.0 V.

  7. Productivity, disturbance and ecosystem size have no influence on food chain length in seasonally connected rivers.

    Directory of Open Access Journals (Sweden)

    Danielle M Warfe

    Full Text Available The food web is one of the oldest and most central organising concepts in ecology and for decades, food chain length has been hypothesised to be controlled by productivity, disturbance, and/or ecosystem size; each of which may be mediated by the functional trophic role of the top predator. We characterised aquatic food webs using carbon and nitrogen stable isotopes from 66 river and floodplain sites across the wet-dry tropics of northern Australia to determine the relative importance of productivity (indicated by nutrient concentrations, disturbance (indicated by hydrological isolation and ecosystem size, and how they may be affected by food web architecture. We show that variation in food chain length was unrelated to these classic environmental determinants, and unrelated to the trophic role of the top predator. This finding is a striking exception to the literature and is the first published example of food chain length being unaffected by any of these determinants. We suggest the distinctive seasonal hydrology of northern Australia allows the movement of fish predators, linking isolated food webs and potentially creating a regional food web that overrides local effects of productivity, disturbance and ecosystem size. This finding supports ecological theory suggesting that mobile consumers promote more stable food webs. It also illustrates how food webs, and energy transfer, may function in the absence of the human modifications to landscape hydrological connectivity that are ubiquitous in more populated regions.

  8. Photoactivation and perturbation of photoluminescent properties of aqueous ZnS nanoparticles: Probing the surfactant-semiconductor interfaces

    International Nuclear Information System (INIS)

    Mehta, S.K.; Kumar, Sanjay

    2011-01-01

    Graphical abstract: The variation in PL emission intensity of growing ZnS NPs during first hour of their growth depends upon the nature of surfactants used for their stabilization. Highlights: ► Photoluminescence (PL) intensity of growing ZnS NPs increases linearly with time. ► Significant PL enhancement in anionic surfactant stabilized ZnS NPs on irradiation. ► PL decay with delay time after removing from UV-irradiation in all the surfactants. ► Better PL stability of ZnS NPs stabilized in anionic surfactants than cationic ones. - Abstract: The in situ photochemistry of aqueous colloidal ZnS has been studied in relation to variety of the surfactants as surface passivating agents. The photoluminescence (PL) intensity of ZnS nanoparticles (NPs) has been drastically enhanced as compared to their bare counterparts due to surface passivation by surfactants depending upon their molecular structure. Cationic surfactants of alkyltrimethylammonium bromide series with different chain lengths (C 16 , C 14 and C 12 ) have been tested. The PL emission of ZnS NPs decreases with decrease in chain length because of ineffective stabilization and passivation of surface because the larger sized NPs were produced in the surfactant with smaller chain length. On the other hand, three anionic surfactants with C 12 chain length with different head groups have been capable of comparatively effective passivation to produce stable NPs with better luminescence. The changing nature of surface states during growth and long time ripening of ZnS NPs has also been monitored by comparing time evolution PL emission in different surfactants. The influence of UV-light irradiation in enhancing the PL emission has been found to be surfactant structure dependent with maximum enhancement observed with the surfactants having π-electrons in their head group functionalities. The anionic surfactants also display better tendency to retain the enhanced PL of ZnS NPs for longer time durations.

  9. Does alkyl chain length really matter? Structure–property relationships in thermochemistry of ionic liquids

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Zaitsau, Dzmitry H.; Emel’yanenko, Vladimir N.; Ralys, Ricardas V.; Yermalayeu, Andrei V.; Schick, Christoph

    2013-01-01

    Graphical abstract: We have shown that enthalpies of formation, enthalpies of vaporization, and lattice potential energies of alkylsubstituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with Cl and Br anions are linearly dependant on the alkyl chain length. The thermochemical properties of ILs are generally obey the group additivity rules and the values of the additivity parameters for enthalpies of formation and vaporization are very close to those for molecular compounds. - Highlights: • Alkyl substituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with anions [Cl] and [Br] were studied using DSC and ab initio methods. • The thermochemical properties of ILs generally obey the group additivity rules. • A linear dependence on the chain length of the alkyl chain of cation was found. - Abstract: DSC was used for determination of reaction enthalpies of synthesis of ionic liquids [C n mim][Cl]. A combination of DSC with quantum chemical calculations presents an indirect way to study thermodynamics of ionic liquids. The indirect procedure for vaporization enthalpy was validated with the direct experimental measurements by using thermogravimetry. First-principles calculations of the enthalpy of formation in the gaseous phase have been performed for the ionic species using the CBS-QB3 and G3 (MP2) theory. Experimental DSC data for homologous series of alkyl substituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with anions [Cl] and [Br] were collected from the literature. We have shown that enthalpies of formation, enthalpies of vaporization, and lattice potential energies are linearly dependant on the alkyl chain length. The thermochemical properties of ILs generally obey the group additivity rules and the values of the additivity parameters for enthalpies of formation and vaporization seem to be very close to those for molecular compounds

  10. Liposomes coated with hydrophobically modified hydroxyethyl cellulose: Influence of hydrophobic chain length and degree of modification.

    Science.gov (United States)

    Smistad, Gro; Nyström, Bo; Zhu, Kaizheng; Grønvold, Marthe Karoline; Røv-Johnsen, Anne; Hiorth, Marianne

    2017-08-01

    Nanoparticulate systems with an uncharged hydrophilic surface may have a great potential in mucosal drug delivery. In the present study liposomes were coated with hydrophobically modified hydroxyethyl cellulose (HM-HEC) to create a sterically stabilized liposomal system with an uncharged surface. The aim was to clarify the influence of the amount of hydrophobic modification of HEC and the length of the hydrophobic moiety, on the stability of the system and on the release properties. HM-HEC with different degrees of hydrophobic modification (1 and 2mol%) and hydrophobic groups with different chain lengths (C8, C12, C16) were included in the study, as well as fluid phase and gel phase liposomes. Both types of liposomes were successfully coated with HM-HEC containing 1mol% of hydrophobic groups, while 2mol% did not work for the intended pharmaceutical applications. The polymer coated gel phase liposomes were stable (size, zeta potential, leakage) for 24 weeks at 4°C, with no differences between the C8 and C16 HM-HEC coating. For the fluid phase liposomes a size increase was observed after 24 weeks at 4°C for all formulations; the C8 HM-HEC coated liposomes increased the most. No differences in the leakage during storage at 4°C or in the release at 35°C were observed between the fluid phase formulations. To conclude; HM-HEC with a shorter hydrophobic chain length resulted in a less stable product for the fluid phase liposomes, while no influence of the chain length was observed for the gel phase liposomes (1mol% HM). Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Photophysical properties of a surfactive long-chain styryl merocyanine dye as fluorescent probe

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, L.F.M., E-mail: Lailafmi@yahoo.com [Al-Azhar University, Faculty of Science, Chemistry Department, Nasr City, 12 Ibrahim El-Nagar, El-Hegaz Sq. Heliopolis, Cairo 11315 (Egypt)

    2012-09-15

    This work deals with detailed investigations of the photophysical properties of a styryl merocyanine dye, namely 1-cetyl-4-[4 Prime -(methoxy) styryl]-pyridinium bromide (CMSPB) of molecular rotor type. The solvatochromic analyses of the data in different solvents using the Kamlet-Taft parameters ({alpha}, {beta}, {pi}{sup Low-Asterisk }) were discussed. Optical excitation of the studied merocyanine dye populates a CT S{sub 1} state with about 22.64 folds higher dipole moment value relative to that in the S{sub 0} state. Moreover, the effect of solvent viscosity (glycerol at various temperatures (299.0-351.0 K)) on CMSPB fluorescent properties is analyzed to understand the molecular mechanisms of the characteristic increase in CMSPB fluorescence intensity. The results indicate that CMSPB exhibits fluorescent properties typical for molecular rotors. The results show that torsional relaxation dynamics of molecular rotors in high-viscosity solvents cannot be described by the simple stick boundary hydrodynamics defined by the Debye-Stokes-Einstein (DSE) equation. The fluorescence depolarization behavior in glycerol at various temperatures (299.0-351.0 K) shows that the molecular rotational diffusion is controlled by the free volume of the medium. Furthermore, excited state studies in ethanol/chloroform mixture revealed the formation of weak complex with chloroform of stoichiometry 1:1 with formation constant of 0.004l mol{sup -1}. Moreover, the increase of the quantum yield values in micellar solutions of CTAB and SDS relative to that of water indicates that the guest dye molecules are microencapsulated into the hydrophobic interior of host micelle. The obtained non-zero values of fluorescence polarization in micellar solution imply reduced rotational depolarization of dye molecules via association with the surfactant. Upon comparing the spectral data in micelles with those in homogeneous solvent systems, more can be learned of the structural details of the micellar

  12. Diversion of phagosome trafficking by pathogenic Rhodococcus equi depends on mycolic acid chain length.

    Science.gov (United States)

    Sydor, Tobias; von Bargen, Kristine; Hsu, Fong-Fu; Huth, Gitta; Holst, Otto; Wohlmann, Jens; Becken, Ulrike; Dykstra, Tobias; Söhl, Kristina; Lindner, Buko; Prescott, John F; Schaible, Ulrich E; Utermöhlen, Olaf; Haas, Albert

    2013-03-01

    Rhodococcus equi is a close relative of Mycobacterium spp. and a facultative intracellular pathogen which arrests phagosome maturation in macrophages before the late endocytic stage. We have screened a transposon mutant library of R. equi for mutants with decreased capability to prevent phagolysosome formation. This screen yielded a mutant in the gene for β-ketoacyl-(acyl carrier protein)-synthase A (KasA), a key enzyme of the long-chain mycolic acid synthesizing FAS-II system. The longest kasA mutant mycolic acid chains were 10 carbon units shorter than those of wild-type bacteria. Coating of non-pathogenic E. coli with purified wild-type trehalose dimycolate reduced phagolysosome formation substantially which was not the case with shorter kasA mutant-derived trehalose dimycolate. The mutant was moderately attenuated in macrophages and in a mouse infection model, but was fully cytotoxic.Whereas loss of KasA is lethal in mycobacteria, R. equi kasA mutant multiplication in broth was normal proving that long-chain mycolic acid compounds are not necessarily required for cellular integrity and viability of the bacteria that typically produce them. This study demonstrates a central role of mycolic acid chain length in diversion of trafficking by R. equi. © 2012 Blackwell Publishing Ltd.

  13. The role of discharge variation in scaling of drainage area and food chain length in rivers

    Science.gov (United States)

    Sabo, John L.; Finlay, Jacques C.; Kennedy, Theodore A.; Post, David M.

    2010-01-01

    Food chain length (FCL) is a fundamental component of food web structure. Studies in a variety of ecosystems suggest that FCL is determined by energy supply, environmental stability, and/or ecosystem size, but the nature of the relationship between environmental stability and FCL, and the mechanism linking ecosystem size to FCL, remain unclear. Here we show that FCL increases with drainage area and decreases with hydrologic variability and intermittency across 36 North American rivers. Our analysis further suggests that hydrologic variability is the mechanism underlying the correlation between ecosystem size and FCL in rivers. Ecosystem size lengthens river food chains by integrating and attenuating discharge variation through stream networks, thereby enhancing environmental stability in larger river systems.

  14. Dependence of micelle size and shape on detergent alkyl chain length and head group.

    Directory of Open Access Journals (Sweden)

    Ryan C Oliver

    Full Text Available Micelle-forming detergents provide an amphipathic environment that can mimic lipid bilayers and are important tools for solubilizing membrane proteins for functional and structural investigations in vitro. However, the formation of a soluble protein-detergent complex (PDC currently relies on empirical screening of detergents, and a stable and functional PDC is often not obtained. To provide a foundation for systematic comparisons between the properties of the detergent micelle and the resulting PDC, a comprehensive set of detergents commonly used for membrane protein studies are systematically investigated. Using small-angle X-ray scattering (SAXS, micelle shapes and sizes are determined for phosphocholines with 10, 12, and 14 alkyl carbons, glucosides with 8, 9, and 10 alkyl carbons, maltosides with 8, 10, and 12 alkyl carbons, and lysophosphatidyl glycerols with 14 and 16 alkyl carbons. The SAXS profiles are well described by two-component ellipsoid models, with an electron rich outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core composed of the alkyl chains. The minor axis of the elliptical micelle core from these models is constrained by the length of the alkyl chain, and increases by 1.2-1.5 Å per carbon addition to the alkyl chain. The major elliptical axis also increases with chain length; however, the ellipticity remains approximately constant for each detergent series. In addition, the aggregation number of these detergents increases by ∼16 monomers per micelle for each alkyl carbon added. The data provide a comprehensive view of the determinants of micelle shape and size and provide a baseline for correlating micelle properties with protein-detergent interactions.

  15. Lipid polymorphism of mixtures of dioleoylphosphatidylethanolamine and saturated and monounsaturated phosphatidylcholines of various chain lengths

    International Nuclear Information System (INIS)

    Tate, M.W.; Gruner, S.M.

    1987-01-01

    The L/sub α/-H/sub II/ phase transition behavior of many lipid-water liquid crystals is dominated by the competition between the tendency to curl the lipid layers to an intrinsic radius of curvature and opposing hydrocarbon packing constraints. In particular, packing constraints can increase the free energy of the inverted hexagonal (H/sub II/) phase as compared to that of the lamellar (L/sub α/) phase. This is especially true where the lipid molecule is not long enough to reach into the corners of the lattice in large hexagonal structures necessitated by a large radius of curvature.In this paper it is shown that the addition of a minor fraction long-chain lipid to a system of otherwise uniform chain composition can also relax packing constraints, thereby lowering the lamellar to hexagonal transition temperature. For the specific systems used, dioleoylphosphatidylethanolamine (di-18:1/sub c/-PE) with minor fractions of 1,2-diacyl-sn-glycero-3-phosphocholines [di-n:1/sub c/-PC (n = 14, 18, 22, and 24)], the observed H/sub II/lattices systematically increased in size with increasing chain length suggesting that the chain length also may affect the intrinsic curvature of the mixture. These experiments demonstrate that the lipid shape concept, which is a qualitative expression of the concept quantitatively described by the intrinsic radius of curvature, is insufficient to understand the L/sub α/-H/sub II/ transition. It is necessary to, at least, consider the competition between curvature and packing

  16. Alkyl chain length impacts the antioxidative effect of lipophilized ferulic acid in fish oil enriched milk

    DEFF Research Database (Denmark)

    Sørensen, Ann-Dorit Moltke; Lyneborg, Karina Sieron; Villeneuve, Pierre

    2015-01-01

    Lipophilization of phenolics by esterification with fatty alcohols may alter their localization in an emulsion and thereby their antioxidant efficacy. In this study, synthesized unbranched alkyl ferulates were evaluated as antioxidants in fish oil enriched milk. Lipid oxidation was determined...... by peroxide values and concentration of volatile oxidation products. A cut-off effect in the antioxidant efficacy in relation to the alkyl chain length was observed. The most efficient alkyl ferulate was methyl ferulate followed by ferulic acid and butyl ferulate, whereas octyl ferulate was prooxidative...

  17. Perspectives of medium chain length poly(hydroxyalkanoates), a versatile set of bacterial bioplastics

    Science.gov (United States)

    Witholt; Kessler

    1999-06-01

    Medium chain length (mcl) poly(hydroxyalkanoic acids) (PHAs) are polyesters accumulated by fluorescent Pseudomonads and other bacteria. Work on the genetics of mcl-PHA formation has led to polymer synthesis in recombinant bacteria and plants. Several high and medium cost applications are now emerging. With optimized bacterial mcl-PHA synthesis on inexpensive agro-substrates and the development of plant-based mcl-PHAs in the next decade, the production economics of these bioplastics will ultimately permit their sustainable production for bulk applications.

  18. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    International Nuclear Information System (INIS)

    Ngoi, Kuan Hoon; Chia, Chin-Hua; Zakaria, Sarani; Chiu, Wee Siong

    2015-01-01

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature

  19. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    Energy Technology Data Exchange (ETDEWEB)

    Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani [School of Applied Physics, Faculty Science and Technology, University Kebangsaan Malaysia 43600 UKM Bangi, Selangor (Malaysia); Chiu, Wee Siong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Lembah Pantai, Kuala Lumpur (Malaysia)

    2015-09-25

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

  20. Effect of Chain Length Compatibility of Alcohols on Muscovite Flotation by Dodecyl Amine

    Directory of Open Access Journals (Sweden)

    Li Wang

    2018-04-01

    Full Text Available A portion of dodecyl amine (DDA in a muscovite flotation system was replaced with alcohols with different carbon-chain lengths. These alcohols included octanol (OCT; decanol (DEC; dodecanol (DOD; and tetradecanol (TER. The muscovite adsorption behavior of the mixed DDA and alcohol systems were investigated through zeta potential; contact angle; and adsorption quantity tests. Single-mineral flotation tests showed that the muscovite-collecting power of the mixed DDA/alcohol (OCT, DEC, or DOD system was stronger than that of the pure DDA system. The muscovite-collecting power of the collector systems decreased in the following order: DDA/DEC > DDA/OCT > DDA/DEC > DDA > DDA/TER. Zeta potential and contact angle analysis indicated that when combined with DDA; alcohols physically adsorbed on the surfaces of muscovite. This behavior improved the hydrophobicity of muscovite. Furthermore, adsorption analysis revealed that synergy between DDA and alcohol enhanced the adsorption of alcohol on muscovite. DDA has a dominant role in synergistic adsorption; whereas alcohol has a supporting role. Among all tested alcohols; DDA and DOD exhibit the highest synergetic adsorption effect because of their similar carbon-chain lengths. This similarity promotes the formation of a compact adsorption layer on the muscovite surface.

  1. Effect of the Alkyl Chain Length on the Adsorption Properties of Malonamide Chelating Resins

    International Nuclear Information System (INIS)

    Ismail, I.M.; Nogami, M.; Suzuki, K.

    2004-01-01

    In order to investigate the effect of the alkyl chain length of malonamide chelating resins on the rate of uptake of U(VI) ions and Ce(III) Ions, lV,N,N',N'-tetraethyl malonamide (TEMA), N,N,N',N'-tetra-n-propyl malonamide (TPrMA), lV,lV,N',N'-tetra-n-butyl malonamide (TBMA) and N,l V,N',N'-tetra-n-pentyl malonamide (Tamp) chelating resins were synthesized by chemically bonding these function groups to CMS-DVB co-polymer beads. N,lV,N',N'-tetraphenyl malonamide (TPhMA) chelating resin was also investigated and the results of these resins were compared with those of N,lY,N',N-tetra methylmalonamide (TMMA) previously reported. The batch technique was used to study the thermodynamic equilibrium, in terms of distribution coefficient, and the kinetics of the adsorption U(VI) and Ce(III) ions from 3 M HNO 3 , Acid, and 3 M NaNO 3 + 0.05 M HNO 3 , Salt, media. The introduction ratio of the function group into the polymer base and the uptake of U(VI) ions and C(III) ions were found to decrease with the increase in the alkyl chain length. The uptake was found to diminish in case of TPhMA resin due to the decrease of the function group ratio and the steric-hinder effect

  2. Pruned-enriched Rosenbluth method: Simulations of θ polymers of chain length up to 1000000

    International Nuclear Information System (INIS)

    Grassberger, P.

    1997-01-01

    We present an algorithm for simulating flexible chain polymers. It combines the Rosenbluth-Rosenbluth method with recursive enrichment. Although it can be applied also in more general situations, it is most efficient for three-dimensional θ polymers on the simple-cubic lattice. There it allows high statistics simulations of chains of length up to N=10 6 . For storage reasons, this is feasable only for polymers in a finite volume. For free θ polymers in infinite volume, we present very high statistics runs with N=10000. These simulations fully agree with previous simulations made by Hegger and Grassberger [J. Chem. Phys. 102, 6681 (1995)] with a similar but less efficient algorithm, showing that logarithmic corrections to mean field behavior are much stronger than predicted by field theory. But the finite volume simulations show that the density inside a collapsed globule scales with the distance from the θ point as predicted by mean field theory, in contrast to claims in the work mentioned above. In addition to the simple-cubic lattice, we also studied two versions of the bond fluctuation model, but with much shorter chains. Finally, we show that our method can be applied also to off-lattice models, and illustrate this with simulations of a model studied in detail by Freire et al. [Macromolecules 19, 452 (1986) and later work]. copyright 1997 The American Physical Society

  3. Alignment-free Transcriptomic and Metatranscriptomic Comparison Using Sequencing Signatures with Variable Length Markov Chains.

    Science.gov (United States)

    Liao, Weinan; Ren, Jie; Wang, Kun; Wang, Shun; Zeng, Feng; Wang, Ying; Sun, Fengzhu

    2016-11-23

    The comparison between microbial sequencing data is critical to understand the dynamics of microbial communities. The alignment-based tools analyzing metagenomic datasets require reference sequences and read alignments. The available alignment-free dissimilarity approaches model the background sequences with Fixed Order Markov Chain (FOMC) yielding promising results for the comparison of microbial communities. However, in FOMC, the number of parameters grows exponentially with the increase of the order of Markov Chain (MC). Under a fixed high order of MC, the parameters might not be accurately estimated owing to the limitation of sequencing depth. In our study, we investigate an alternative to FOMC to model background sequences with the data-driven Variable Length Markov Chain (VLMC) in metatranscriptomic data. The VLMC originally designed for long sequences was extended to apply to high-throughput sequencing reads and the strategies to estimate the corresponding parameters were developed. The flexible number of parameters in VLMC avoids estimating the vast number of parameters of high-order MC under limited sequencing depth. Different from the manual selection in FOMC, VLMC determines the MC order adaptively. Several beta diversity measures based on VLMC were applied to compare the bacterial RNA-Seq and metatranscriptomic datasets. Experiments show that VLMC outperforms FOMC to model the background sequences in transcriptomic and metatranscriptomic samples. A software pipeline is available at https://d2vlmc.codeplex.com.

  4. Characterization of a Novel Subgroup of Extracellular Medium-Chain-Length Polyhydroxyalkanoate Depolymerases from Actinobacteria

    Science.gov (United States)

    Gangoiti, Joana; Santos, Marta; Prieto, María Auxiliadora; de la Mata, Isabel; Llama, María J.

    2012-01-01

    Nineteen medium-chain-length (mcl) poly(3-hydroxyalkanoate) (PHA)-degrading microorganisms were isolated from natural sources. From them, seven Gram-positive and three Gram-negative bacteria were identified. The ability of these microorganisms to hydrolyze other biodegradable plastics, such as short-chain-length (scl) PHA, poly(ε-caprolactone) (PCL), poly(ethylene succinate) (PES), and poly(l-lactide) (PLA), has been studied. On the basis of the great ability to degrade different polyesters, Streptomyces roseolus SL3 was selected, and its extracellular depolymerase was biochemically characterized. The enzyme consisted of one polypeptide chain of 28 kDa with a pI value of 5.2. Its maximum activity was observed at pH 9.5 with chromogenic substrates. The purified enzyme hydrolyzed mcl PHA and PCL but not scl PHA, PES, and PLA. Moreover, the mcl PHA depolymerase can hydrolyze various substrates for esterases, such as tributyrin and p-nitrophenyl (pNP)-alkanoates, with its maximum activity being measured with pNP-octanoate. Interestingly, when poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate [11%]) was used as the substrate, the main hydrolysis product was the monomer (R)-3-hydroxyoctanoate. In addition, the genes of several Actinobacteria strains, including S. roseolus SL3, were identified on the basis of the peptide de novo sequencing of the Streptomyces venezuelae SO1 mcl PHA depolymerase by tandem mass spectrometry. These enzymes did not show significant similarity to mcl PHA depolymerases characterized previously. Our results suggest that these distinct enzymes might represent a new subgroup of mcl PHA depolymerases. PMID:22865072

  5. The effect of carbon chain length of starting materials on the formation of carbon dots and their optical properties

    Science.gov (United States)

    Pan, Xiaohua; Zhang, Yan; Sun, Xiaobo; Pan, Wei; Yu, Guifeng; Si, Shuxin; Wang, Jinping

    2018-04-01

    Carbon dots (CDs) have attracted increasing attention due to their high performances and potential applications in wide range of areas. However, their emission mechanism is not clear so far. In order to reveal more factors contributing to the emission of CDs, the effect of carbon chain length of starting materials on the formation of CDs and their optical properties was experimentally investigated in this work. In order to focus on the effect of carbon chain length, the starting materials with C, O, N in fully identical forms and only carbon chain lengths being different were selected for synthesizing CDs, including citric acid (CA) and adipic acid (AA) as carbon sources, and diamines with different carbon chain lengths (H2N(CH2)nNH2, n = 2, 4, 6) as nitrogen sources, as well as ethylenediamine (EDA) as nitrogen source and diacids with different carbon chain lengths (HOOC(CH2)nCOOH, n = 0, 2, 4, 6) as carbon sources. Therefore, the effect of carbon chain length of starting materials on the formation and optical properties of CDs can be systematically investigated by characterizing and comparing the structures and optical properties of as-prepared nine types of CDs. Moreover, the density of –NH2 on the surface of the CDs was quantitatively detected by a spectrophotometry so as to elucidate the relationship between the –NH2 related surface state and the optical properties.

  6. Soliton scatterings by impurities in a short-length sine-Gordon chain

    International Nuclear Information System (INIS)

    Dikande, A.M.; Kofane, T.C.

    1995-07-01

    The scattering of soliton by impurities at the frontiers of a finite-length region of an infinite sine-Gordon chain is analyzed. The impurities consist of two isotopic inhomogeneities installed at the boundaries of the finite-length region. The soliton solution in the region is found in term of snoidal sine-Gordon soliton which properly takes into account the effects of the boundaries. By contrast, the soliton solutions in the neighboring sides of the region are obtained in terms of the so-called large-amplitude, localized kinks with limiting spatial extensions at x → ± ∞, which is equal ±π. Using the continuity of these soliton solutions at the frontiers as well as appropriate boundary conditions, it is shown that the soliton may be either i) reflected by the incident impurity; ii) trapped (with oscillating motions) between the two impurities (i.e. inside the infinite region); or iii) transmitted by the second impurity into the third, infinitely extended region. The threshold velocities for the reflection and transmission into different regions are found and shown to vary exponentially as a function of the length of the bounded region. The frequency of soliton oscillations between the impurities has also been calculated in some acceptable limit. (author). 28 refs, 1 fig

  7. Chain length effects on the vibrational structure and molecular interactions in the liquid normal alkyl alcohols

    Science.gov (United States)

    Kiefer, Johannes; Wagenfeld, Sabine; Kerlé, Daniela

    2018-01-01

    Alkyl alcohols are widely used in academia, industry, and our everyday lives, e.g. as cleaning agents and solvents. Vibrational spectroscopy is commonly used to identify and quantify these compounds, but also to study their structure and behavior. However, a comprehensive investigation and comparison of all normal alkanols that are liquid at room temperature has not been performed, surprisingly. This study aims at bridging this gap with a combined experimental and computational effort. For this purpose, the alkyl alcohols from methanol to undecan-1-ol have been analyzed using infrared and Raman spectroscopy. A detailed assignment of the individual peaks is presented and the influence of the alkyl chain length on the hydrogen bonding network is discussed. A 2D vibrational mapping allows a straightforward visualization of the effects. The conclusions drawn from the experimental data are backed up with results from Monte Carlo simulations using the simulation package Cassandra.

  8. Synthesis of medium-chain length capsinoids from coconut oil catalyzed by Candida rugosa lipases.

    Science.gov (United States)

    Trbojević Ivić, Jovana; Milosavić, Nenad; Dimitrijević, Aleksandra; Gavrović Jankulović, Marija; Bezbradica, Dejan; Kolarski, Dušan; Veličković, Dušan

    2017-03-01

    A commercial preparation of Candida rugosa lipases (CRL) was tested for the production of capsinoids by esterification of vanillyl alcohol (VA) with free fatty acids (FA) and coconut oil (CO) as acyl donors. Screening of FA chain length indicated that C8-C12 FA (the most common FA found in CO triglycerides) are the best acyl-donors, yielding 80-85% of their specific capsinoids. Hence, when CO, which is rich in these FA, was used as the substrate, a mixture of capsinoids (vanillyl caprylate, vanillyl decanoate and vanillyl laurate) was obtained. The findings presented here suggest that our experimental method can be applied for the enrichment of CO with capsinoids, thus giving it additional health promoting properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. The Role of Chain Length in Nonergodicity Factor and Fragility of Polymers

    DEFF Research Database (Denmark)

    Dalle-Ferrie, Cecile; Niss, Kristine; Sokolov, Alexei

    2010-01-01

    The mechanism that leads to different fragility values upon approaching the glass transition remains a topic of active discussion. Many researchers are trying to find an answer in the properties of the frozen glassy state. Following this approach, we focus here on a previously proposed relationship...... between the fragility of glass-formers and their nonergodicity factor, determined by inelastic X-ray scattering (IXS) in the glass. We extend this molecular liquid study to two model polymers— polystyrene (PS) and polyisobutylene (PIB)—for which we change the molecular weight. Polymers offer...... the opportunity to change the fragility without altering the chemical structure, just by changing the chain length. Thus, we specifically chose PS and PIB because they exhibit opposite dependences of fragility with molecular weight. Our analysis for these two polymers reveals no unique correlation between...

  10. Tuning the Mechanical Properties of Polymer Nanocomposites Filled with Grafted Nanoparticles by Varying the Grafted Chain Length and Flexibility

    Directory of Open Access Journals (Sweden)

    Zixuan Wang

    2016-08-01

    Full Text Available By employing coarse-grained molecular dynamics simulation, we simulate the spatial organization of the polymer-grafted nanoparticles (NPs in homopolymer matrix and the resulting mechanical performance, by particularly regulating the grafted chain length and flexibility. The morphologies ranging from the agglomerate, cylinder, sheet, and string to full dispersion are observed, by gradually increasing the grafted chain length. The radial distribution function and the total interaction energy between NPs are calculated. Meanwhile, the stress–strain behavior of each morphology and the morphological evolution during the uniaxial tension are simulated. In particular, the sheet structure exhibits the best mechanical reinforcement compared to other morphologies. In addition, the change of the grafted chain flexibility to semi-flexibility leads to the variation of the morphology. We also find that at long grafted chain length, the stress–strain behavior of the system with the semi-flexible grafted chain begins to exceed that of the system with the flexible grafted chain, attributed to the physical inter-locking interaction between the matrix and grafted polymer chains. A similar transition trend is as well found in the presence of the interfacial chemical couplings between grafted and matrix polymer chains. In general, this work is expected to help to design and fabricate high performance polymer nanocomposites filled with grafted NPs with excellent and controllable mechanical properties.

  11. Supplemental Dietary Inulin of Variable Chain Lengths Alters Intestinal Bacterial Populations in Young Pigs123

    Science.gov (United States)

    Patterson, Jannine K.; Yasuda, Koji; Welch, Ross M.; Miller, Dennis D.; Lei, Xin Gen

    2010-01-01

    Previously, we showed that supplementation of diets with short-chain inulin (P95), long-chain inulin (HP), and a 50:50 mixture of both (Synergy 1) improved body iron status and altered expression of the genes involved in iron homeostasis and inflammation in young pigs. However, the effects of these 3 types of inulin on intestinal bacteria remain unknown. Applying terminal restriction fragment length polymorphism analysis, we determined the abundances of luminal and adherent bacterial populations from 6 segments of the small and large intestines of pigs (n = 4 for each group) fed an iron-deficient basal diet (BD) or the BD supplemented with 4% of P95, Synergy 1, or HP for 5 wk. Compared with BD, all 3 types of inulin enhanced (P inulin on bacterial populations in the lumen contents were found. Meanwhile, all 3 types of inulin suppressed the less desirable bacteria Clostridium spp. and members of the Enterobacteriaceae in the lumen and mucosa of various gut segments. Our findings suggest that the ability of dietary inulin to alter intestinal bacterial populations may partially account for its iron bioavailability-promoting effect and possibly other health benefits. PMID:20980641

  12. Critical temperatures and a critical chain length in saturated diacylphosphatidylcholines: calorimetric, ultrasonic and Monte Carlo simulation study of chain-melting/ordering in aqueous lipid dispersions.

    Science.gov (United States)

    Kharakoz, Dmitry P; Panchelyuga, Maria S; Tiktopulo, Elizaveta I; Shlyapnikova, Elena A

    2007-12-01

    Chain-ordering/melting transition in a series of saturated diacylphosphatidylcholines (PCs) in aqueous dispersions have been studied experimentally (calorimetric and ultrasonic techniques) and theoretically (an Ising-like lattice model). The shape of the calorimetric curves was compared with the theoretical data and interpreted in terms of the lateral interactions and critical temperatures determined for each lipid studied. A critical chain length has been found (between 16 and 17 C-atoms per chain) which subdivides PCs into two classes with different phase behavior. In shorter lipids, the transition takes place above their critical temperatures meaning that this is an intrinsically continuous transition. In longer lipids, the transition occurs below the critical temperatures of the lipids, meaning that the transition is intrinsically discontinuous (first-order). This conclusion was supported independently by the ultrasonic relaxation sensitive to density fluctuations. Interestingly, it is this length that is the most abundant among the saturated chains in biological membranes.

  13. Well-defined block copolymers for gene delivery to dendritic cells: probing the effect of polycation chain-length.

    Science.gov (United States)

    Tang, Rupei; Palumbo, R Noelle; Nagarajan, Lakshmi; Krogstad, Emily; Wang, Chun

    2010-03-03

    The development of safe and efficient polymer carriers for DNA vaccine delivery requires mechanistic understanding of structure-function relationship of the polymer carriers and their interaction with antigen-presenting cells. Here we have synthesized a series of diblock copolymers with well-defined chain-length using atom transfer radical polymerization and characterized the influence of polycation chain-length on the physico-chemical properties of the polymer/DNA complexes as well as the interaction with dendritic cells. The copolymers consist of a hydrophilic poly(ethylene glycol) block and a cationic poly(aminoethyl methacrylate) (PAEM) block. The average degree of polymerization (DP) of the PAEM block was varied among 19, 39, and 75, with nearly uniform distribution. With increasing PAEM chain-length, polyplexes formed by the diblock copolymers and plasmid DNA had smaller average particle size and showed higher stability against electrostatic destabilization by salt and heparin. The polymers were not toxic to mouse dendritic cells (DCs) and only displayed chain-length-dependent toxicity at a high concentration (1mg/mL). In vitro gene transfection efficiency and polyplex uptake in DCs were also found to correlate with chain-length of the PAEM block with the longer polymer chain favoring transfection and cellular uptake. The polyplexes induced a modest up-regulation of surface markers for DC maturation that was not significantly dependent on PAEM chain-length. Finally, the polyplex prepared from the longest PAEM block (DP of 75) achieved an average of 20% enhancement over non-condensed anionic dextran in terms of uptake by DCs in the draining lymph nodes 24h after subcutaneous injection into mice. Insights gained from studying such structurally well-defined polymer carriers and their interaction with dendritic cells may contribute to improved design of practically useful DNA vaccine delivery systems. Copyright 2009 Elsevier B.V. All rights reserved.

  14. Scaling behaviour of the correlation length for the two-point correlation function in the random field Ising chain

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Adrian; Stinchcombe, Robin [Theoretical Physics, University of Oxford, Oxford (United Kingdom)

    1996-07-07

    We study the general behaviour of the correlation length {zeta}(kT:h) for two-point correlation function of the local fields in an Ising chain with binary distributed fields. At zero field it is shown that {zeta} is the same as the zero-field correlation length for the spin-spin correlation function. For the field-dominated behaviour of {zeta} we find an exponent for the power-law divergence which is smaller than the exponent for the spin-spin correlation length. The entire behaviour of the correlation length can be described by a single crossover scaling function involving the new critical exponent. (author)

  15. Polarization-dependent NEXAFS study of adsorption of long-chain surfactants on mechanically milled iron powder

    Energy Technology Data Exchange (ETDEWEB)

    Syugaev, A.V., E-mail: syual@mail.ru; Maratkanova, A.N.

    2014-08-15

    Highlights: • Plate-like particles modified with surfactant molecules were obtained under high-energy ball milling. • Adsorption layers were studied with polarization-dependent NEXAFS spectroscopy. • For the first time, arrangement of surfactants molecules on the powdered metal surface has been determined. • Tails of surfactant molecules (C-F/C-H) are shown to be oriented perpendicular to the particle surface. • Arrangement of carboxylate groups on the particle surfaces is discussed. - Abstract: In this work we have demonstrated the possibility of using the polarization-dependent NEXAFS spectra to study the structure of organic layers at the surface of powdered materials with plate-like shaped particles. The polarization dependence of the NEXAFS spectra may be easily obtained by just changing the angle between the X-ray beam direction and the substrate onto which the powder particles are set. For the first time, we have carried out a detailed study of the surfactant layers (n-perfluorononanoic and stearic acid), which are formed at the surface of iron plate-like particles under mechanical milling of iron powder with an addition of corresponding surfactants. The surfactant molecules are predominantly oriented perpendicular to the surface of the mechanically milled particles. Such orientation is similar to the arrangement of the molecules in the layers formed under equilibrium conditions, e.g. deposition from solutions. The changes in the chemical environment occurring in the molecule tails (defluorination or dehydrogenation) under mechanochemical treatment, do not result in a significant change in the molecular orientation and disordering of the adsorbed layer.

  16. Control of in vivo disposition and immunogenicity of polymeric micelles by adjusting poly(sarcosine) chain lengths on surface

    Science.gov (United States)

    Kurihara, Kensuke; Ueda, Motoki; Hara, Isao; Ozeki, Eiichi; Togashi, Kaori; Kimura, Shunsaku

    2017-07-01

    Four kinds of A3B-type amphiphilic polydepsipeptides, (poly(sarcosine))3- b-poly( l-lactic acid) (the degree of polymerization of poly(sarcosine) are 10, 33, 55, and 85; S10 3 , S33 3 , S55 3 , and S85 3 ) were synthesized to prepare core-shell type polymeric micelles. Their in vivo dispositions and stimulations to trigger immune system to produce IgM upon multiple administrations to mice were examined. With increasing poly(sarcosine) chain lengths, the hydrophilic shell became thicker and the surface density at the most outer surface decreased on the basis of dynamic and static light scattering measurements. These two physical elements of polymeric micelles elicited opposite effects on the immune response in light of the chain length therefore to show an optimized poly(sarcosine) chain length existing between 33mer and 55mer to suppress the accelerated blood clearance phenomenon associated with polymeric micelles.

  17. On optimal length of hydrocarbon chain of fatty-acid collectors of rare earth ions

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Sazonova, V.F.; Markina, Eh.L.

    1978-01-01

    The mechanism of the effect of the length of alkyl chain in fatty-acid collectors on the efficiency of flotation separation of the ions of rare earth elements (REE) collected by them has been investigated. REE flotation separation was studied on gadolinium chloride. Aqueous solutions of potassium caprinata, indecanate, laurate, tridecanate, myristate, pentadecanate and palmitate were used as collectors of Gd ions. The interaction of Gd ions with these compounds proceeds rapidly and is accompanied by stable colloidal solutions of Gd soaps being formed. Infrared spectra and radiograms of the sublates have been studied. It has been found that, with the number of carbon atoms in the collector molecule increasing from 10 to 16, the rate of flotation separation of Gd ions from solutions with pH 6 and 8 at first practically does not change (for potassium caprinate, undecanate and laurate), then drops sharply (potassium tridecanate and myristate), after which is again increases sharply (potassium pentadecanata and palmitate). The separation rate of Gd ions does not rise in solutions with pH 10. The nature of the sublate is shown to be determined by the solubility of the corresponing fatty acids and gadolinium soaps

  18. The interacting effects of temperature and food chain length on trophic abundance and ecosystem function.

    Science.gov (United States)

    Beveridge, Oliver S; Humphries, Stuart; Petchey, Owen L

    2010-05-01

    1. While much is known about the independent effects of trophic structure and temperature on density and ecosystem processes, less is known about the interaction(s) between the two. 2. We manipulated the temperature of laboratory-based bacteria-protist communities that contained communities with one, two, or three trophic levels, and recorded species' densities and bacterial decomposition. 3. Temperature, food chain length and their interaction produced significant responses in microbial density and bacterial decomposition. Prey and resource density expressed different patterns of temperature dependency during different phases of population dynamics. The addition of a predator altered the temperature-density relationship of prey, from a unimodal trend to a negative one. Bacterial decomposition was greatest in the presence of consumers at higher temperatures. 4. These results are qualitatively consistent with a recent model of direct and indirect temperature effects on resource-consumer population dynamics. Results highlight and reinforce the importance of indirect effects of temperature mediated through trophic interactions. Understanding and predicting the consequences of environmental change will require that indirect effects, trophic structure, and individual species' tolerances be incorporated into theory and models.

  19. Molecular identification of Giardia duodenalis in Ecuador by polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    Richard Atherton

    2013-06-01

    Full Text Available The aim of this study was to determine the genetic diversity of Giardia duodenalis present in a human population living in a northern Ecuadorian rain forest. All Giardia positive samples (based on an ELISA assay were analysed using a semi-nested polymerase chain reaction-restriction fragment length polymorphism assay that targets the glutamate dehydrogenase (gdh gene; those amplified were subsequently genotyped using NlaIV and RsaI enzymes. The gdh gene was successfully amplified in 74 of 154 ELISA positive samples; 69 of the 74 samples were subsequently genotyped. Of these 69 samples, 42 (61% were classified as assemblage B (26 as BIII and 16 as BIV, 22 (32% as assemblage A (3 as AI and 19 as AII and five (7% as mixed AII and BIII types. In this study site we observe similar diversity in genotypes to other regions in Latin America, though in contrast to some previous studies, we found similar levels of diarrheal symptoms in those individuals infected with assemblage B compared with those infected with assemblage A.

  20. Cooperative Effects of Zwitterionic-Ionic Surfactant Mixtures on the Interfacial Water Structure Revealed by Sum Frequency Generation Vibrational Spectroscopy.

    Science.gov (United States)

    Pan, Xuecong; Yang, Fangyuan; Chen, Shunli; Zhu, Xuefeng; Wang, Chuanyi

    2018-05-08

    Cooperative effects of a series of equimolar binary zwitterionic-ionic surfactant mixtures on the interfacial water structure at the air-water interfaces have been studied by sum frequency generation vibrational spectroscopy (SFG-VS). For zwitterionic surfactant palmityl sulfobetaine (SNC 16 ), anionic surfactant sodium hexadecyl sulfate (SHS), and cationic surfactant cetyltrimethylammonium bromide (CTAB) with the same length of alkyl chain, significantly enhanced ordering of interfacial water molecules was observed for the zwitterionic-anionic surfactant mixtures SNC 16 -SHS, indicating that SNC 16 interacts more strongly with SHS than with CTAB because of the strong headgroup-headgroup electrostatic attraction for SNC 16 -SHS. Meanwhile, the SFG amplitude ratio of methyl and methylene symmetric stretching modes was used to verify the stronger interaction between SNC 16 and SHS. The conformational order indicator increased from 0.64 for SNC 16 to 7.17 for SNC 16 -SHS but only 0.94 for SNC 16 -CTAB. In addition, another anionic surfactant sodium dodecyl sulfate (SDS) was introduced to study the influence of chain-chain interaction. Decreased SFG amplitude of interfacial water molecules for SNC 16 -SDS was observed. Therefore, both the headgroup-headgroup electrostatic interaction and chain-chain van der Waals attractive interaction of the surfactants play an important role in enhancing the ordering of interfacial water molecules. The results provided experimental and theoretical bases for practical applications of the surfactants.

  1. Chain length dependence of the helix orientation in Langmuir-Blodgett monolayers of alpha-helical diblock copolypeptides

    NARCIS (Netherlands)

    Nguyen, Le-Thu T.; Ardana, Aditya; Vorenkamp, Eltjo J.; ten Brinke, Gerrit; Schouten, Arend J.

    2010-01-01

    The effect of chain length on the helix orientation of alpha-helical diblock copolypeptides in Langmuir and Langmuir-Blodgett monolayers is reported for the first time. Amphiphilic diblock copolypeptides (PLGA-b-PMLGSLGs) of poly(alpha-L-glutamic acid) (PLGA) and

  2. Biosynthesis of Colabomycin E, a New Manumycin-Family Metabolite, Involves an Unusual Chain-Length Factor

    Czech Academy of Sciences Publication Activity Database

    Petříčková, Kateřina; Pospíšil, Stanislav; Kuzma, Marek; Tylová, Tereza; Jágr, Michal; Tomek, P.; Chroňáková, Alica; Brabcová, E.; Anděra, Ladislav; Krištůfek, Václav; Petříček, Miroslav

    2014-01-01

    Roč. 15, č. 9 (2014), s. 1334-1345 ISSN 1439-4227 R&D Projects: GA MZd(CZ) NT13012 Institutional support: RVO:61388971 ; RVO:60077344 ; RVO:68378050 Keywords : biosynthesis * chain-length factors * manumycins Subject RIV: CE - Biochemistry Impact factor: 3.088, year: 2014

  3. Development of environmentally friendly coatings and paints using medium-chain-length poly(3-hydroxyalkanoates) as the polymer binder

    NARCIS (Netherlands)

    Walle, van der G.A.M.; Buisman, F.J.H.; Weusthuis, R.A.; Eggink, G.

    1999-01-01

    Unsaturated medium-chain-length poly(3-hydroxyalkanoates) (mcl-PHAs) produced by Pseudomonas putida from linseed oil fatty acids (LOFA) and tall oil fatty acids (TOFA), were used as the polymer binder in the formulation of high solid alkyd-like paints. The relatively high concentration of

  4. Pseudomonas aeruginosa cytochrome c551 denaturation by five systematic urea derivatives that differ in the alkyl chain length.

    Science.gov (United States)

    Kobayashi, Shinya; Fujii, Sotaro; Koga, Aya; Wakai, Satoshi; Matubayasi, Nobuyuki; Sambongi, Yoshihiro

    2017-07-01

    Reversible denaturation of Pseudomonas aeruginosa cytochrome c 551 (PAc 551 ) could be followed using five systematic urea derivatives that differ in the alkyl chain length, i.e. urea, N-methylurea (MU), N-ethylurea (EU), N-propylurea (PU), and N-butylurea (BU). The BU concentration was the lowest required for the PAc 551 denaturation, those of PU, EU, MU, and urea being gradually higher. Furthermore, the accessible surface area difference upon PAc 551 denaturation caused by BU was found to be the highest, those by PU, EU, MU, and urea being gradually lower. These findings indicate that urea derivatives with longer alkyl chains are stronger denaturants. In this study, as many as five systematic urea derivatives could be applied for the reversible denaturation of a single protein, PAc 551 , for the first time, and the effects of the alkyl chain length on protein denaturation were systematically verified by means of thermodynamic parameters.

  5. Molecular dynamics simulation of radiation grafted FEP films as proton exchange membranes: Effects of the side chain length

    DEFF Research Database (Denmark)

    Li, Xue; Zhao, Yang; Li, Weiwei

    2017-01-01

    In order to study the microstructure of the prepared potential proton exchange membrane (PEM), molecular dynamics (MD) simulations were used to lucubrate the transport behavior of water molecules and hydronium ions inside the hydrated sulfonated styrene grafted fluorinated ethylene propylene (FEP...... whereas larger water clusters formed. The results of the mean square displacements (MSDs) show that the proton conductivities of the membranes with the proposed side chain lengths were about three fifths of the experimental data, of which the membrane with side chain length of 7 sulfonic styrene units...... was supposed to exhibit the highest proton conductivity, that is 115.69 mS cm-1. All of the supposed membrane models presented good proton conductivity that could definitely meet the application requirements of the proton exchange membranes. The MD simulations can provide an insight to the chain structure...

  6. Effects of cloud-point grafting, chain length, and density of PEG layers on competitive adsorption of ocular proteins

    DEFF Research Database (Denmark)

    Kingshott, P.; Thissen, H.; Griesser, H.J.

    2002-01-01

    The effects of pinning density, chain length, and 'cloud point' (CP) versus non-CP grafting conditions have been studied on the ability of polyethylene glycol (PEG) layers to minimize adsorption from a multicomponent (lysozyme, human serum albumin (HSA), IgG and lactoferrin) protein solution...... density) r.f.g.d. polymer layers. The PEG graft density was varied also by increasing the temperature and salt (K2SO4) content of the grafting solution; it reached a maximum at the CP of the PEGs. The CP reaction conditions were critical for producing PEG layers capable of minimizing protein adsorption. X...... density and chain length are interrelated, but the key factor is optimization of PEG chain density by use of the CP conditions, provided that a sufficient density of pinning sites exists. (C) 2002 Elsevier Science Ltd. Al l rights reserved....

  7. Dual influences of ecosystem size and disturbance on food chain length in streams.

    Science.gov (United States)

    McHugh, Peter A; McIntosh, Angus R; Jellyman, Phillip G

    2010-07-01

    The number of trophic transfers occurring between basal resources and top predators, food chain length (FCL), varies widely in the world's ecosystems for reasons that are poorly understood, particularly for stream ecosystems. Available evidence indicates that FCL is set by energetic constraints, environmental stochasticity, or ecosystem size effects, although no single explanation has yet accounted for FCL patterns in a broad sense. Further, whether environmental disturbance can influence FCL has been debated on both theoretical and empirical grounds for quite some time. Using data from sixteen South Island, New Zealand streams, we determined whether the so-called ecosystem size, disturbance, or resource availability hypotheses could account for FCL variation in high country fluvial environments. Stable isotope-based estimates of maximum trophic position ranged from 2.6 to 4.2 and averaged 3.5, a value on par with the global FCL average for streams. Model-selection results indicated that stream size and disturbance regime best explained across-site patterns in FCL, although resource availability was negatively correlated with our measure of disturbance; FCL approached its maximum in large, stable springs and was disturbed streams. Community data indicate that size influenced FCL, primarily through its influence on local fish species richness (i.e., via trophic level additions and/or insertions), whereas disturbance did so via an effect on the relative availability of intermediate predators (i.e., predatory invertebrates) as prey for fishes. Overall, our results demonstrate that disturbance can have an important food web-structuring role in stream ecosystems, and further imply that pluralistic explanations are needed to fully understand the range of structural variation observed for real food webs.

  8. Relationship between Length and Surface-Enhanced Raman Spectroscopy Signal Strength in Metal Nanoparticle Chains: Ideal Models versus Nanofabrication

    Directory of Open Access Journals (Sweden)

    Kristen D. Alexander

    2012-01-01

    Full Text Available We have employed capillary force deposition on ion beam patterned substrates to fabricate chains of 60 nm gold nanospheres ranging in length from 1 to 9 nanoparticles. Measurements of the surface-averaged SERS enhancement factor strength for these chains were then compared to the numerical predictions. The SERS enhancement conformed to theoretical predictions in the case of only a few chains, with the vast majority of chains tested not matching such behavior. Although all of the nanoparticle chains appear identical under electron microscope observation, the extreme sensitivity of the SERS enhancement to nanoscale morphology renders current nanofabrication methods insufficient for consistent production of coupled nanoparticle chains. Notwithstanding this fact, the aggregate data also confirmed that nanoparticle dimers offer a large improvement over the monomer enhancement while conclusively showing that, within the limitations imposed by current state-of-the-art nanofabrication techniques, chains comprising more than two nanoparticles provide only a marginal signal boost over the already considerable dimer enhancement.

  9. Association mapping of starch chain length distribution and amylose content in pea (Pisum sativum L.) using carbohydrate metabolism candidate genes.

    Science.gov (United States)

    Carpenter, Margaret A; Shaw, Martin; Cooper, Rebecca D; Frew, Tonya J; Butler, Ruth C; Murray, Sarah R; Moya, Leire; Coyne, Clarice J; Timmerman-Vaughan, Gail M

    2017-08-01

    Although starch consists of large macromolecules composed of glucose units linked by α-1,4-glycosidic linkages with α-1,6-glycosidic branchpoints, variation in starch structural and functional properties is found both within and between species. Interest in starch genetics is based on the importance of starch in food and industrial processes, with the potential of genetics to provide novel starches. The starch metabolic pathway is complex but has been characterized in diverse plant species, including pea. To understand how allelic variation in the pea starch metabolic pathway affects starch structure and percent amylose, partial sequences of 25 candidate genes were characterized for polymorphisms using a panel of 92 diverse pea lines. Variation in the percent amylose composition of extracted seed starch and (amylopectin) chain length distribution, one measure of starch structure, were characterized for these lines. Association mapping was undertaken to identify polymorphisms associated with the variation in starch chain length distribution and percent amylose, using a mixed linear model that incorporated population structure and kinship. Associations were found for polymorphisms in seven candidate genes plus Mendel's r locus (which conditions the round versus wrinkled seed phenotype). The genes with associated polymorphisms are involved in the substrate supply, chain elongation and branching stages of the pea carbohydrate and starch metabolic pathways. The association of polymorphisms in carbohydrate and starch metabolic genes with variation in amylopectin chain length distribution and percent amylose may help to guide manipulation of pea seed starch structural and functional properties through plant breeding.

  10. The effect of the chain length distribution of free fatty acids on the mixing properties of stratum corneum model membranes.

    Science.gov (United States)

    Oguri, Masashi; Gooris, Gert S; Bito, Kotatsu; Bouwstra, Joke A

    2014-07-01

    The stratum corneum (SC) plays a fundamental role in the barrier function of the skin. The SC consists of corneocytes embedded in a lipid matrix. The main lipid classes in the lipid matrix are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The aim of this study was to examine the effect of the chain length of FFAs on the thermotropic phase behavior and mixing properties of SC lipids. Fourier transform infrared spectroscopy and Raman imaging spectroscopy were used to study the mixing properties using either protonated or deuterated FFAs. We selected SC model lipid mixtures containing only a single CER, CHOL and either a single FFA or a mixture of FFAs mimicking the FFA SC composition. The single CER consists of a sphingoid base with 18 carbon atoms and an acyl chain with a chain length of 24 carbon atoms. When using lignoceric acid (24 carbon atoms) or a mixture of FFAs, the CER and FFAs participated in mixed crystals, but hydration of the mixtures induced a slight phase separation between CER and FFA. The mixed crystalline structures did not phase separate during storage even up to a time period of 3months. When using palmitic acid (16 carbon atoms), a slight phase separation was observed between FFA and CER. This phase separation was clearly enhanced during hydration and storage. In conclusion, the thermotropic phase behavior and the mixing properties of the SC lipid mixtures were shown to strongly depend on the chain length and chain length distribution of FFAs, while hydration enhanced the phase separation. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Proton conducting graft copolymers with tunable length and density of phosphonated side chains for fuel cell membranes

    DEFF Research Database (Denmark)

    Dimitrov, Ivaylo; Takamuku, Shogo; Jankova Atanasova, Katja

    2014-01-01

    Polysulfones functionalized with highly phosphonated poly(pentafluorostyrene) side chains of different lengths were synthesized applying controlled polymerization and modification methods. The graft copolymers' thermal properties were evaluated by differential scanning calorimetry and thermal...... gravimetrical analyses. The proton conductivity of membrane prepared from the graft copolymer with the shortest phosphonated side chains was 134 mS cm(-1) at 100 degrees C under fully immersed conditions. The graft copolymer TEM image shows a nanophase separation of ion-rich segments within the polysulfone...

  12. Development of environmentally friendly coatings and paints using medium-chain-length poly(3-hydroxyalkanoates) as the polymer binder.

    Science.gov (United States)

    van der Walle, G A; Buisman, G J; Weusthuis, R A; Eggink, G

    1999-01-01

    Unsaturated medium-chain-length poly(3-hydroxyalkanoates) (mcl-PHAs) produced by Pseudomonas putida from linseed oil fatty acids (LOFA) and tall oil fatty acids (TOFA), were used as the polymer binder in the formulation of high solid alkyd-like paints. The relatively high concentration of unsaturated alkyl side chains incorporated into the PHA resins resulted in oxidative drying PHA paints having excellent coating properties. The homogeneously pigmented PHA coatings yielded high-gloss, smooth and strong films upon curing and showed an excellent flexibility, a good adhesion to different substrates, cohesive film properties and resistance to chipping.

  13. σ-Bond Electron Delocalization in Oligosilanes as Function of Substitution Pattern, Chain Length, and Spatial Orientation

    Directory of Open Access Journals (Sweden)

    Johann Hlina

    2016-08-01

    Full Text Available Polysilanes are known to exhibit the interesting property of σ-bond electron delocalization. By employing optical spectroscopy (UV-vis, it is possible to judge the degree of delocalization and also differentiate parts of the molecules which are conjugated or not. The current study compares oligosilanes of similar chain length but different substitution pattern. The size of the substituents determines the spatial orientation of the main chain and also controls the conformational flexibility. The chemical nature of the substituents affects the orbital energies of the molecules and thus the positions of the absorption bands.

  14. Long-chain alkylimidazolium ionic liquids, a new class of cationic surfactants coated on ODS columns for anion-exchange chromatography.

    Science.gov (United States)

    Qiu, Hongdeng; Zhang, Qinghua; Chen, Limei; Liu, Xia; Jiang, Shengxiang

    2008-08-01

    Separations of common inorganic anions were carried out on ODS columns coated with two long-chain alkylimidazolium ionic liquids ([C(12)MIm]Br and [C(14)MIm]Br) as new cationic surfactants for ion chromatography. With phthalate buffer solution as the mobile phases and non-suppressed conductivity detection, high column efficiencies and excellent selectivity were obtained in the separation of inorganic anions. Chromatographic parameters are calculated and the results show that the coated column possesses significant potential for the analysis of some inorganic anions such as CH(3)COO(-), IO(3)(-), Cl(-), BrO(3)(-), NO(2)(-), Br(-), NO(3)(-), SO(4)(2-), I(-), BF(4)(-), and SCN(-). The effect of eluent pH values on the separation of anions has been studied on the column coated with [C(12)MIm]Br. The stability of the coated columns was also examined.

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

    Science.gov (United States)

    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.

  16. Effect of presence of benzene ring in surfactant hydrophobic chain on the transformation towards one dimensional aggregate

    Directory of Open Access Journals (Sweden)

    Rabah A. Khalil

    2015-07-01

    Full Text Available The formation of wormlike micelle and the following significant changes in rheological properties suffer misunderstanding from both theoretical and fundamental aspects. Recently, we have introduced a theory for interpreting such important phenomenon which is referred to as critical intermolecular forces (CIF. The theory has stated that the hydrophobic effect is the main factor for the formation of worm-like aggregates. Therefore, it seems interesting to check out the validity of this new physical insight through investigating the presence of benzene ring as less hydrophobic group in contrast to that of alkyl in surfactant tail. The mixture of anionic sodium dodecylbenzenesulphonate (SDBS and cationic cetyltrimethylammonium bromide (CTAB shows a high dynamic viscosity peak at the ratio of 80/20 of 3 wt.% CTAB/SDBS indicating the formation of wormlike micelles. The thermodynamic properties have been evaluated for this mixture exhibiting good agreement with the rheological changes. Interestingly, the results show the presence of benzene ring (in SDBS causing a negative effect towards the formation of one dimensional aggregate in contrast to previous results which support the proposed CIF theory. The presence of nonionic surfactant TritonX-100 in binary and ternary systems of SDBS and CTAB prohibits the formation of wormlike micelles.

  17. Effect of side chain length on the stability and structural properties of 3

    African Journals Online (AJOL)

    thiophene (DOOPT) and their dimers studied by Hartree-Fock (HF) and Density Functional Theory (DFT) methods. The DFT calculations suggest that dimers of the dialkoxyphenylthiophenes with longer side chains are thermodynamically more ...

  18. Anomaly in the Chain Length Dependence of n-Alkane Diffusion in ZIF-4 Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Seungtaik Hwang

    2018-03-01

    Full Text Available Molecular diffusion is commonly found to slow down with increasing molecular size. Deviations from this pattern occur in some host materials with pore sizes approaching the diameters of the guest molecules. A variety of theoretical models have been suggested to explain deviations from this pattern, but robust experimental data are scarcely available. Here, we present such data, obtained by monitoring the chain length dependence of the uptake of n-alkanes in the zeolitic imidazolate framework ZIF-4. A monotonic decrease in diffusivity from ethane to n-butane was observed, followed by an increase for n-pentane, and another decrease for n-hexane. This observation was confirmed by uptake measurements with n-butane/n-pentane mixtures, which yield faster uptake of n-pentane. Further evidence is provided by the observation of overshooting effects, i.e., by transient n-pentane concentrations exceeding the (eventually attained equilibrium value. Accompanying grand canonical Monte Carlo simulations reveal, for the larger n-alkanes, significant differences between the adsorbed and gas phase molecular configurations, indicating strong confinement effects within ZIF-4, which, with increasing chain length, may be expected to give rise to configurational shifts facilitating molecular propagation at particular chain lengths.

  19. Anomaly in the Chain Length Dependence of n-Alkane Diffusion in ZIF-4 Metal-Organic Frameworks.

    Science.gov (United States)

    Hwang, Seungtaik; Gopalan, Arun; Hovestadt, Maximilian; Piepenbreier, Frank; Chmelik, Christian; Hartmann, Martin; Snurr, Randall Q; Kärger, Jörg

    2018-03-15

    Molecular diffusion is commonly found to slow down with increasing molecular size. Deviations from this pattern occur in some host materials with pore sizes approaching the diameters of the guest molecules. A variety of theoretical models have been suggested to explain deviations from this pattern, but robust experimental data are scarcely available. Here, we present such data, obtained by monitoring the chain length dependence of the uptake of n- alkanes in the zeolitic imidazolate framework ZIF-4. A monotonic decrease in diffusivity from ethane to n- butane was observed, followed by an increase for n- pentane, and another decrease for n- hexane. This observation was confirmed by uptake measurements with n- butane/ n -pentane mixtures, which yield faster uptake of n- pentane. Further evidence is provided by the observation of overshooting effects, i.e., by transient n- pentane concentrations exceeding the (eventually attained) equilibrium value. Accompanying grand canonical Monte Carlo simulations reveal, for the larger n- alkanes, significant differences between the adsorbed and gas phase molecular configurations, indicating strong confinement effects within ZIF-4, which, with increasing chain length, may be expected to give rise to configurational shifts facilitating molecular propagation at particular chain lengths.

  20. Self-consistent field theoretic simulations of amphiphilic triblock copolymer solutions: Polymer concentration and chain length effects

    Directory of Open Access Journals (Sweden)

    X.-G. Han

    2014-06-01

    Full Text Available Using the self-consistent field lattice model, polymer concentration φP and chain length N (keeping the length ratio of hydrophobic to hydrophilic blocks constant the effects on temperature-dependent behavior of micelles are studied, in amphiphilic symmetric ABA triblock copolymer solutions. When chain length is increased, at fixed φP, micelles occur at higher temperature. The variations of average volume fraction of stickers φcos and the lattice site numbers Ncols at the micellar cores with temperature are dependent on N and φP, which demonstrates that the aggregation of micelles depends on N and φP. Moreover, when φP is increased, firstly a peak appears on the curve of specific heat CV for unimer-micelle transition, and then in addition a primary peak, the secondary peak, which results from the remicellization, is observed on the curve of CV. For a long chain, in intermediate and high concentration regimes, the shape of specific heat peak markedly changes, and the peak tends to be a more broad peak. Finally, the aggregation behavior of micelles is explained by the aggregation way of amphiphilic triblock copolymer. The obtained results are helpful in understanding the micellar aggregation process.

  1. Impact of the alkyl chain length on binding of imidazolium-based ionic liquids to bovine serum albumin

    Science.gov (United States)

    Zhang, Mengyue; Wang, Ying; Zhang, Hongmei; Cao, Jian; Fei, Zhenghao; Wang, Yanqing

    2018-05-01

    The effects of six imidazolium-based ionic liquids (ILs) with different alkyl chain length ([CnMim]Cl, n = 2, 4, 6, 8, 10, 12) on the structure and functions of bovine serum albumin (BSA) were studied by multi-spectral methods and molecular docking. ILs with the longer alkyl chain length have the stronger binding interaction with BSA and the greater conformational damage to protein. The effects of ILs on the functional properties of BSA were further studied by the determination of non-enzyme esterase activity, β-fibrosis and other properties of BSA. The thermal stability of BSA was reduced, the rate of the formation of beta sheet structures of BSA was lowered, and the esterase-like activity of BSA were decreased with the increase of ILs concentration. Simultaneous molecular modeling technique revealed the favorable binding sites of ILs on protein. The hydrophobic force and polar interactions were the mainly binding forces of them. The calculated results are in a good agreement with the spectroscopic experiments. These studies on the impact of the alkyl chain length on binding of imidazolium-based ionic liquids to BSA are of great significance for understanding and developing the application of ionic liquid in life and physiological system.

  2. Effect of double-tailed surfactant architecture on the conformation, self-assembly, and processing in polypeptide-surfactant complexes.

    Science.gov (United States)

    Junnila, Susanna; Hanski, Sirkku; Oakley, Richard J; Nummelin, Sami; Ruokolainen, Janne; Faul, Charl F J; Ikkala, Olli

    2009-10-12

    This work describes the solid-state conformational and structural properties of self-assembled polypeptide-surfactant complexes with double-tailed surfactants. Poly(L-lysine) was complexed with three dialkyl esters of phosphoric acid (i.e., phosphodiester surfactants), where the surfactant tail branching and length was varied to tune the supramolecular architecture in a facile way. After complexation with the branched surfactant bis(2-ethylhexyl) phosphate in an aqueous solution, the polypeptide chains adopted an alpha-helical conformation. These rod-like helices self-assembled into cylindrical phases with the amorphous alkyl tails pointing outward. In complexes with dioctyl phosphate and didodecyl phosphate, which have two linear n-octyl or n-dodecyl tails, respectively, the polypeptide formed antiparallel beta-sheets separated by alkyl layers, resulting in well-ordered lamellar self-assemblies. By heating, it was possible to trigger a partial opening of the beta-sheets and disruption of the lamellar phase. After repeated heating/cooling, all of these complexes also showed a glass transition between 37 and 50 degrees C. Organic solvent treatment and plasticization by overstoichiometric amount of surfactant led to structure modification in poly(L-lysine)-dioctyl phosphate complexes, PLL(diC8)(x) (x = 1.0-3.0). Here, the alpha-helical PLL is surrounded by the surfactants and these bottle-brush-like chains self-assemble in a hexagonal cylindrical morphology. As x is increased, the materials are clearly plasticized and the degree of ordering is improved: The stiff alpha-helical backbones in a softened surfactant matrix give rise to thermotropic liquid-crystalline phases. The complexes were examined by Fourier transform infrared spectroscopy, small- and wide-angle X-ray scattering, transmission electron microscopy, differential scanning calorimetry, polarized optical microscopy, and circular dichroism.

  3. Spectral sensitization of TiO2 by new hemicyanine dyes in dye solar cell yielding enhanced photovoltage: Probing chain length effect on performance

    International Nuclear Information System (INIS)

    Fadadu, Kishan B.; Soni, Saurabh S.

    2013-01-01

    Graphical abstract: New hemicyanine dyes based on indolenine moiety were utilized as light harvesting materials in dye sensitized solar cell. Chain lengths of the molecules were varied in order to study its effect of chain length on the performance of DSSC. Electron transfer kinetic of the solar cell was studied and it was found that the chain length changes the electron transfer kinetic. We have achieved remarkable photovoltage and overall performance of DSSC. Highlights: ► New hemicyanine dyes based on indolenine moiety were utilized as light harvesting materials in dye sensitized solar cell. ► Chain lengths of the molecules were varied in order to study its effect of chain length on the performance of DSSC. ► Electron transfer kinetic of the solar cell was studied and it was found that the chain length changes the electron transfer kinetic. -- Abstract: New hemicyanine dyes having indole nucleus with different alkyl chain length were synthesized and characterized using 1 H NMR and mass spectroscopy. These dyes were used to sensitize the TiO 2 film in dye sensitized solar cell. Nanocrystalline dye solar cells were fabricated and characterized using various electrochemical techniques. It has been found that the alkyl chain length present in the dye molecules greatly affects the overall performance of dye solar cell. Molecules having longer alkyl chain are having better sensitizers which enhance V oc to significant extent. Chain length dependent performance was further investigated using Tafel polarization and impedance method. Hemicyanine dye having hexyl chain has outperformed by attaining 2.9% solar to electricity conversion efficiency

  4. The impact of alkyl sulfate surfactant geometry and electrolyte on the co-adsorption of anionic surfactants with model perfumes at the air-solution interface.

    Science.gov (United States)

    Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig

    2013-08-01

    The impact of surfactant geometry and electrolyte on the co-adsorption of anionic surfactants and model perfumes at the air-solution interface has been studied by neutron reflectivity. The more hydrophobic perfume linalool, competes more favourably for the surface with sodium dodecylsulfate than was previously reported for the anionic surfactant, sodium dodecyl 6-benzenesulfonate. Due to an increase in surface activity of the sodium dodecylsulfate, the addition of electrolyte results in a reduction in the linalool adsorption. Changing the alkyl chain length affects the relative adsorption of linalool and surfactant at the interface. Similar measurements for the different alkyl sulfates and with electrolyte with the more hydrophilic perfume phenyl ethanol, reveal broadly similar trends. Although the relative adsorption of phenyl ethanol with sodium dodecylsulfate is substantially enhanced compared to sodium dodecyl-6-benzenesulfonate the effects are not as significant as was observed with linalool. The variations with alkyl chain geometry show the importance of the hydrophobic interaction between the perfume and surfactant and changes in the packing constraints on the relative adsorption. The results highlight the importance of the specific interaction between the surfactant and perfume, and the surfactant and perfume geometries on the relative adsorption at the interface. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Thermoresponsive Poly(2-oxazoline) Molecular Brushes by Living Ionic Polymerization: Kinetic Investigations of Pendant Chain Grafting and Cloud Point Modulation by Backbone and Side Chain Length Variation

    KAUST Repository

    Zhang, Ning

    2012-04-17

    Molecular brushes of poly(2-oxazoline)s were prepared by living anionic polymerization of 2-iso-propenyl-2-oxazoline to form the backbone and subsequent living cationic ring-opening polymerization of 2-n- or 2-iso-propyl-2-oxazoline for pendant chain grafting. In situ kinetic studies indicate that the initiation efficiency and polymerization rates are independent from the number of initiator functions per initiator molecule. This was attributed to the high efficiency of oxazolinium salt and the stretched conformation of the backbone, which is caused by the electrostatic repulsion of the oxazolinium moieties along the macroinitiator. The resulting molecular brushes showed thermoresponsive properties, that is, having a defined cloud point (CP). The dependence of the CP as a function of backbone and side chain length as well as concentration was studied. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Simulated glass-forming polymer melts: dynamic scattering functions, chain length effects, and mode-coupling theory analysis.

    Science.gov (United States)

    Frey, S; Weysser, F; Meyer, H; Farago, J; Fuchs, M; Baschnagel, J

    2015-02-01

    We present molecular-dynamics simulations for a fully flexible model of polymer melts with different chain length N ranging from short oligomers (N = 4) to values near the entanglement length (N = 64). For these systems we explore the structural relaxation of the supercooled melt near the critical temperature T c of mode-coupling theory (MCT). Coherent and incoherent scattering functions are analyzed in terms of the idealized MCT. For temperatures T > T c we provide evidence for the space-time factorization property of the β relaxation and for the time-temperature superposition principle (TTSP) of the α relaxation, and we also discuss deviations from these predictions for T ≈ T c. For T larger than the smallest temperature where the TTSP holds we perform a quantitative analysis of the dynamics with the asymptotic MCT predictions for the late β regime. Within MCT a key quantity, in addition to T c, is the exponent parameter λ. For the fully flexible polymer models studied we find that λ is independent of N and has a value (λ = 0.735 ) typical of simple glass-forming liquids. On the other hand, the critical temperature increases with chain length toward an asymptotic value T c (∞) . This increase can be described by T c (∞) - T c(N) ∼ 1/N and may be interpreted in terms of the N dependence of the monomer density ρ, if we assume that the MCT glass transition is ruled by a soft-sphere-like constant coupling parameter Γ c = ρ c T c (-1/4), where ρ c is the monomer density at T c. In addition, we also estimate T c from a Hansen-Verlet-like criterion and MCT calculations based on structural input from the simulation. For our polymer model both the Hansen-Verlet criterion and the MCT calculations suggest T c to decrease with increasing chain length, in contrast to the direct analysis of the simulation data.

  7. Novel Strategies for Production of Medium and High Chain Length Alcohols

    NARCIS (Netherlands)

    Lopez Contreras, A.M.; Kuit, W.; Springer, J.; Claassen, P.A.M.

    2011-01-01

    Fermentation-derived ethanol is currently widely used as transport fuel, both as such or as a blending component in gasoline (Antoni et al. 2007; Mielenz 2001). However, longer chain alcohols have higher energy densities and are less soluble in water than ethanol, which are important advantages for

  8. Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study.

    Directory of Open Access Journals (Sweden)

    Zuzanna Pietralik

    Full Text Available The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration, they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp and siRNA (21 bp. The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16. On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain.

  9. Ion solvation in polymer blends and block copolymer melts: effects of chain length and connectivity on the reorganization of dipoles.

    Science.gov (United States)

    Nakamura, Issei

    2014-05-29

    We studied the thermodynamic properties of ion solvation in polymer blends and block copolymer melts and developed a dipolar self-consistent field theory for polymer mixtures. Our theory accounts for the chain connectivity of polymerized monomers, the compressibility of the liquid mixtures under electrostriction, the permanent and induced dipole moments of monomers, and the resultant dielectric contrast among species. In our coarse-grained model, dipoles are attached to the monomers and allowed to rotate freely in response to electrostatic fields. We demonstrate that a strong electrostatic field near an ion reorganizes dipolar monomers, resulting in nonmonotonic changes in the volume fraction profile and the dielectric function of the polymers with respect to those of simple liquid mixtures. For the parameter sets used, the spatial variations near an ion can be in the range of 1 nm or larger, producing significant differences in the solvation energy among simple liquid mixtures, polymer blends, and block copolymers. The solvation energy of an ion depends substantially on the chain length in block copolymers; thus, our theory predicts the preferential solvation of ions arising from differences in chain length.

  10. Effects of chain length, chlorination degree, and structure on the octanol-water partition coefficients of polychlorinated n-alkanes.

    Science.gov (United States)

    Hilger, Bettina; Fromme, Hermann; Völkel, Wolfgang; Coelhan, Mehmet

    2011-04-01

    Log octanol-water partition coefficients (log Kow) of 40 synthesized polychlorinated n-alkanes (PCAs) with different chlorination degrees were determined using reversed-phase high performance liquid chromatography (RP-HPLC). In addition, log Kow values of a technical mixture namely Cereclor 63L as well as 15 individual in house synthesized C10, C11, and C12 chloroalkanes with known chlorine positions were estimated. Based on these results, the effects of chain length, chlorination degree, and structure were explored. The estimated log Kow values ranged from 4.10 (polychlorinated n-decanes with 50.2% chlorine content) to 11.34 (polychlorinated n-octacosanes with 54.8% chlorine content) for PCAs and from 3.82 (1,2,5,6,9,10-hexachlorodecane) to 7.75 (1,1,1,3,9,11,11,11-octachlorododecane) for the individual chloroalkanes studied. The results showed that log Kow value was influenced linearly at a given chlorine content by chain length, while a polynominal effect was observed in dependence on the chlorination degree of an alkane chain. Chlorine substitution pattern influenced markedly the log Kow value of chloroalkanes.

  11. The effect of the alkyl chain length on physicochemical features of (ionic liquids + γ-butyrolactone) binary mixtures

    International Nuclear Information System (INIS)

    Papović, Snežana; Bešter-Rogač, Marija; Vraneš, Milan; Gadžurić, Slobodan

    2016-01-01

    Highlights: • Influence of alkyl substituent length on IL properties was studied. • Nature of interactions between studied [C_nC_1im][NTf_2] and GBL were discussed. • Angell strength parameter indicates [C_nC_1im][NTf_2] are fragile liquids. • ILs properties regularly change with increase of the alkyl chain length. • Absence of GBL self-association upon addition of IL is observed. - Abstract: Densities and viscosities were determined and analysed for γ-butyrolactone (GBL) binary mixtures with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids (where alkyl = ethyl, hexyl, octyl) as a function of temperature at atmospheric pressure (p = 0.1 MPa) and over the whole composition range. Excess molar volumes have been calculated from the experimental densities and were fitted using Redlich–Kister’s polynomial equation. Other volumetric parameters have been also calculated in order to obtain information about interactions between GBL and imidazolium based ionic liquids with different alkyl chain length. From the viscosity measurements, the Angell strength parameter was calculated for pure ionic liquids indicating that all investigated electrolytes are “fragile” liquids.

  12. Electrical contacts to nanorod networks at different length scales: From macroscale ensembles to single nanorod chains

    KAUST Repository

    Lavieville, Romain; Zhang, Yang; Di Fabrizio, Enzo M.; Krahne, Roman

    2013-01-01

    The nature of metal-semiconductor interfaces at the nanoscale is an important issue in micro- and nanoelectronic engineering. The study of charge transport through chains of CdSe semiconductor nanorods linked by Au particles represents an ideal model system for this matter, because the metal semiconductor interface is an intrinsic feature of the nanosystem. Here we show the controlled fabrication of all-inorganic hybrid metal-semiconductor networks with different size, in which the semiconductor nanorods are linked by Au domains at their tips. We demonstrate different approaches to selectively contact the networks and single nanorod chains with planar electrodes, and we investigate their charge transport at room temperature. © 2013 Elsevier B.V. All rights reserved.

  13. Electrical contacts to nanorod networks at different length scales: From macroscale ensembles to single nanorod chains

    KAUST Repository

    Lavieville, Romain

    2013-11-01

    The nature of metal-semiconductor interfaces at the nanoscale is an important issue in micro- and nanoelectronic engineering. The study of charge transport through chains of CdSe semiconductor nanorods linked by Au particles represents an ideal model system for this matter, because the metal semiconductor interface is an intrinsic feature of the nanosystem. Here we show the controlled fabrication of all-inorganic hybrid metal-semiconductor networks with different size, in which the semiconductor nanorods are linked by Au domains at their tips. We demonstrate different approaches to selectively contact the networks and single nanorod chains with planar electrodes, and we investigate their charge transport at room temperature. © 2013 Elsevier B.V. All rights reserved.

  14. Surface properties and aggregate morphology of partially fluorinated carboxylate-type anionic gemini surfactants.

    Science.gov (United States)

    Yoshimura, Tomokazu; Bong, Miri; Matsuoka, Keisuke; Honda, Chikako; Endo, Kazutoyo

    2009-11-01

    Three anionic homologues of a novel partially fluorinated carboxylate-type anionic gemini surfactant, N,N'-di(3-perfluoroalkyl-2-hydroxypropyl)-N,N'-diacetic acid ethylenediamine (2C(n)(F) edda, where n represents the number of carbon atoms in the fluorocarbon chain (4, 6, and 8)) were synthesized. In these present gemini surfactants, the relatively small carboxylic acid moieties form hydrophilic head groups. The surface properties or structures of the aggregates of these surfactants are strongly influenced by the nonflexible fluorocarbons and small head groups; this is because these surfactants have a closely packed molecular structure. The equilibrium surface tension properties of these surfactants were measured at 298.2K for various fluorocarbon chain lengths. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain lengths for 2C(n)(F) edda (n=4, 6, and 8) showed a minimum for n=6. Furthermore, the lowest surface tension of 2C(6)(F) edda at the cmc was 16.4mNm(-1). Such unique behavior has not been observed even in the other fluorinated surfactants. Changes in the shapes and sizes of these surfactant aggregate with concentration were investigated by dynamic light scattering and transmission electron microscopy (TEM). The TEM micrographs showed that in an aqueous alkali solution, 2C(n)(F) edda mainly formed aggregates with stringlike (n=4), cagelike (n=6), and distorted bilayer structures (n=8). The morphological changes in the aggregates were affected by the molecular structure composed of nonflexible fluorocarbon chains and flexible hydrocarbon chains.

  15. Kinetic analysis of anionic surfactant adsorption from aqueous solution onto activated carbon and layered double hydroxide with the zero length column method

    NARCIS (Netherlands)

    Schouten, N.; van der Ham, Aloysius G.J.; Euverink, G.J.W.; de Haan, A.B.

    2009-01-01

    Low cost adsorption technology offers high potential to clean-up laundry rinsing water. From an earlier selection of adsorbents, layered double hydroxide (LDH) and granular activated carbon (GAC) proved to be interesting materials for the removal of anionic surfactant, linear alkyl benzene sulfonate

  16. Room temperature ionic liquids: A simple model. Effect of chain length and size of intermolecular potential on critical temperature.

    Science.gov (United States)

    Chapela, Gustavo A; Guzmán, Orlando; Díaz-Herrera, Enrique; del Río, Fernando

    2015-04-21

    A model of a room temperature ionic liquid can be represented as an ion attached to an aliphatic chain mixed with a counter ion. The simple model used in this work is based on a short rigid tangent square well chain with an ion, represented by a hard sphere interacting with a Yukawa potential at the head of the chain, mixed with a counter ion represented as well by a hard sphere interacting with a Yukawa potential of the opposite sign. The length of the chain and the depth of the intermolecular forces are investigated in order to understand which of these factors are responsible for the lowering of the critical temperature. It is the large difference between the ionic and the dispersion potentials which explains this lowering of the critical temperature. Calculation of liquid-vapor equilibrium orthobaric curves is used to estimate the critical points of the model. Vapor pressures are used to obtain an estimate of the triple point of the different models in order to calculate the span of temperatures where they remain a liquid. Surface tensions and interfacial thicknesses are also reported.

  17. Esterification of fatty acids using nylon-immobilized lipase in n-hexane: kinetic parameters and chain-length effects.

    Science.gov (United States)

    Zaidi, A; Gainer, J L; Carta, G; Mrani, A; Kadiri, T; Belarbi, Y; Mir, A

    2002-02-28

    The esterification of long-chain fatty acids in n-hexane catalyzed by nylon-immobilized lipase from Candida rugosa has been investigated. Butyl oleate (22 carbon atoms), oleyl butyrate (22 carbon atoms) and oleyl oleate (36 carbon atoms) were produced at maximum reaction rates of approximately equal to 60 mmol h(-1) g(-1) immobilized enzyme when the substrates were present in equimolar proportions at an initial concentration of 0.6 mol l(-1). The observed kinetic behavior of all the esterification reactions is found to follow a ping-pong bi-bi mechanism with competitive inhibition by both substrates. The effect of the chain-length of the fatty acids and the alcohols could be correlated to some mechanistic models, in accordance with the calculated kinetic parameters.

  18. Immobilization of lipases on alkyl silane modified magnetic nanoparticles: effect of alkyl chain length on enzyme activity.

    Directory of Open Access Journals (Sweden)

    Jiqian Wang

    Full Text Available 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 Fe(3O(4 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

  19. Immobilization of lipases on alkyl silane modified magnetic nanoparticles: effect of alkyl chain length on enzyme activity.

    Science.gov (United States)

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

    2012-01-01

    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. 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 Fe(3)O(4) 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. 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 enabling efficient enzyme recovery and recycling.

  20. Surfactant loss control in chemical flooding spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1993--September 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaran, P.

    1995-06-01

    The aim of this project is to elucidate the mechanisms underlying adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effect of surfactant structure, surfactant combinations, other inorganic and polymeric species is being studied. A multi-pronged approach consisting of micro and nano spectroscopy, microcalorimetry, electrokinetics, surface tension and wettability is used to achieve the goals. The results of this study should help in controlling surfactant loss in chemical flooding and also in developing optimum structures and conditions for efficient chemical flooding processes. During the second year of this three year contract, adsorption/desorption of single surfactants and select surfactant mixtures on alumina and silica was studied. Surfactants studied include the anionic sodium dodecyl sulfate (SDS), cationic tetradecyl trimethyl ammonium chloride (TTAC), nonionic pentadecylethoxylated nonyl phenol (NP-15) and the nonionic octaethylene glycol n-dodecyl ether (C{sub 12}EO{sub 8}) of varying hydrocarbon chain length. The microstructure of the adsorbed layer in terms of micropolarity and aggregation numbers was probed using fluorescence spectroscopy. Changes of microstructure upon dilution (desorption) were also studied. Presence of the nonionic surfactant in the mixed aggregate led to shielding of the charge of the ionic surfactant which in-turn promoted aggregation but reduced electrostatic attraction between the charged surfactant and the mineral surface. Strong consequences of surfactant interactions in solution upon adsorption as well as correlations between monomer concentrations in mixtures and adsorption were revealed.

  1. Collapse of Langmuir monolayer at lower surface pressure: Effect of hydrophobic chain length

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kaushik, E-mail: kaushikdas2089@gmail.com; Kundu, Sarathi [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035 (India)

    2016-05-23

    Long chain fatty acid molecules (e.g., stearic and behenic acids) form a monolayer on water surface in the presence of Ba{sup 2+} ions at low subphase pH (≈ 5.5) and remain as a monolayer before collapse generally occurs at higher surface pressure (π{sub c} > 50 mN/m). Monolayer formation is verified from the surface pressure vs. area per molecule (π-A) isotherms and also from the atomic force microscopy (AFM) analysis of the films deposited by single upstroke of hydrophilic Si (001) substrate through the monolayer covered water surface. At high subphase pH (≈ 9.5), barium stearate molecules form multilayer structure at lower surface pressure which is verified from the π-A isotherms and AFM analysis of the film deposited at 25 mN/m. Such monolayer to multilayer structure formation or monolayer collapse at lower surface pressure is unusual as at this surface pressure generally fatty acid salt molecules form a monolayer on the water surface. Formation of bidentate chelate coordination in the metal containing headgroups is the reason for such monolayer to multilayer transition. However, for longer chain barium behenate molecules only monolayer structure is maintained at that high subphase pH (≈ 9.5) due to the presence of relatively more tail-tail hydrophobic interaction.

  2. Effect of bidispersity in grafted chain length on grafted chain conformations and potential of mean force between polymer grafted nanoparticles in a homopolymer matrix.

    Science.gov (United States)

    Nair, Nitish; Wentzel, Nathaniel; Jayaraman, Arthi

    2011-05-21

    In efforts to produce polymeric materials with tailored physical properties, significant interest has grown around the ability to control the spatial organization of nanoparticles in polymer nanocomposites. One way to achieve controlled particle arrangement is by grafting the nanoparticle surface with polymers that are compatible with the matrix, thus manipulating the interfacial interactions between the nanoparticles and the polymer matrix. Previous work has shown that the molecular weight of the grafted polymer, both at high grafting density and low grafting density, plays a key role in dictating the effective inter-particle interactions in a polymer matrix. At high grafting density nanoparticles disperse (aggregate) if the graft molecular weight is higher (lower) than the matrix molecular weight. At low grafting density the longer grafts can better shield the nanoparticle surface from direct particle-particle contacts than the shorter grafts and lead to the dispersion of the grafted particles in the matrix. Despite the importance of graft molecular weight, and evidence of non-trivial effects of polydispersity of chains grafted on flat surfaces, most theoretical work on polymer grafted nanoparticles has only focused on monodisperse grafted chains. In this paper, we focus on how bidispersity in grafted chain lengths affects the grafted chain conformations and inter-particle interactions in an implicit solvent and in a dense homopolymer polymer matrix. We first present the effects of bidispersity on grafted chain conformations in a single polymer grafted particle using purely Monte Carlo (MC) simulations. This is followed by calculations of the potential of mean force (PMF) between two grafted particles in a polymer matrix using a self-consistent Polymer Reference Interaction Site Model theory-Monte Carlo simulation approach. Monte Carlo simulations of a single polymer grafted particle in an implicit solvent show that in the bidisperse polymer grafted particles

  3. Antiaromatic bisindeno-[n]thienoacenes with small singlet biradical characters: Syntheses, structures and chain length dependent physical properties

    KAUST Repository

    Shi, Xueliang

    2014-01-01

    Recent studies demonstrated that aromaticity and biradical character play important roles in determining the ground-state structures and physical properties of quinoidal polycyclic hydrocarbons and oligothiophenes, a kind of molecular materials showing promising applications for organic electronics, photonics and spintronics. In this work, we designed and synthesized a new type of hybrid system, the so-called bisindeno-[n]thienoacenes (n = 1-4), by annulation of quinoidal fused α-oligothiophenes with two indene units. The obtained molecules can be regarded as antiaromatic systems containing 4n π electrons with small singlet biradical character (y0). Their ground-state geometry and electronic structures were studied by X-ray crystallographic analysis, NMR, ESR and Raman spectroscopy, assisted by density functional theory calculations. With extension of the chain length, the molecules showed a gradual increase of the singlet biradical character accompanied by decreased antiaromaticity, finally leading to a highly reactive bisindeno[4]thienoacene (S4-TIPS) which has a singlet biradical ground state (y0= 0.202). Their optical and electronic properties in the neutral and charged states were systematically investigated by one-photon absorption, two-photon absorption, transient absorption spectroscopy, cyclic voltammetry and spectroelectrochemistry, which could be correlated to the chain length dependent antiaromaticity and biradical character. Our detailed studies revealed a clear structure-aromaticity-biradical character-physical properties-reactivity relationship, which is of importance for tailored material design in the future. This journal is

  4. Evaluation of clay hybrid nanocomposites of different chain length as reinforcing agent for natural and synthetic rubbers

    International Nuclear Information System (INIS)

    Yehia, A.A.; Akelah, A.M.; Rehab, A.; El-Sabbagh, S.H.; El Nashar, D.E.; Koriem, A.A.

    2012-01-01

    Highlights: → The modified organo-clay (MMT-ATBN) markedly reinforce natural and synthetic rubbers. → The reinforcing efficiency of the organo-clay is much higher than HAF carbon black. → The reinforcing efficiency of MMT modified with different alkylamines greatly depend on the chain length. → The good compatibility of modified organo-clay with NBR can be attributed to the chemical nature. -- Abstract: Polymer nanocomposites are one of the highly discussed research topics in recent time. It has been reported in the present paper the preparation and the properties of different nanoclays based on sodium montmorillonite (bentonite) and some organic amines of varying chain lengths (dodecylamine, hexadecylamine and octadecylamine) beside amine-terminated butadiene-acrylonitrile copolymer (ATBN). The hybrid clays have been characterized with the help of Fourier Transform Infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Wide angle X-ray diffractions (WXRD), and Thermogravimetric analysis (TGA). X-ray results showed that the intergallery distance of the clay is increased as a result of the intercalation of the amines and ATBN. The nanocomposite clays were incorporated in natural and synthetic rubbers (NR, SBR and NBR). The physico-mechanical properties are greatly improved with loading low concentrations of the nanocomposite clays compared with carbon black.

  5. Dynamic photoinduced realignment processes in photoresponsive block copolymer films: effects of the chain length and block copolymer architecture.

    Science.gov (United States)

    Sano, Masami; Shan, Feng; Hara, Mitsuo; Nagano, Shusaku; Shinohara, Yuya; Amemiya, Yoshiyuki; Seki, Takahiro

    2015-08-07

    A series of block copolymers composed of an amorphous poly(butyl methacrylate) (PBMA) block connected with an azobenzene (Az)-containing liquid crystalline (PAz) block were synthesized by changing the chain length and polymer architecture. With these block copolymer films, the dynamic realignment process of microphase separated (MPS) cylinder arrays of PBMA in the PAz matrix induced by irradiation with linearly polarized light was studied by UV-visible absorption spectroscopy, and time-resolved grazing incidence small angle X-ray scattering (GI-SAXS) measurements using a synchrotron beam. Unexpectedly, the change in the chain length hardly affected the realignment rate. In contrast, the architecture of the AB-type diblock or the ABA-type triblock essentially altered the realignment feature. The strongly cooperative motion with an induction period before realignment was characteristic only for the diblock copolymer series, and the LPL-induced alignment change immediately started for triblock copolymers and the PAz homopolymer. Additionally, a marked acceleration in the photoinduced dynamic motions was unveiled in comparison with a thermal randomization process.

  6. Thermodynamics on the micellization of various pure and mixed surfactants: Effects of head- and tail-groups

    International Nuclear Information System (INIS)

    Lee, Nam-Min; Lee, Byung-Hwan

    2016-01-01

    Highlights: • The values of critical micelle concentration of various pure and mixed surfactants are measured. • Thermodynamic parameters’ values are calculated to analyze the effects of head- and tail-groups on the micellization. • All the thermodynamic parameters’ values are decreasing with the increase of temperature. • The thermodynamic parameters’ values are depending severely on the chain length of alkyl group. - Abstract: The values of critical micelle concentration (CMC) for the micellization of various pure and mixed surfactants are determined by the UV–Vis spectrophotometric method. And the effects of temperature on the CMC values have been measured and thermodynamic parameters’ values are calculated to analyse the effects of head- and tail-groups on the micellization of surfactant molecules. The results show that the values of ΔG"o are negative and those of ΔS"o are positive for the micellization of all the surfactants within the measured temperature range. But the values of ΔH"o are positive or negative, depending on the kinds of surfactants. All these thermodynamic parameters’ values are decreasing together with the increase of temperature for all the surfactants. And these thermodynamic parameters’ values are depending severely on the chain length of alkyl group also as much as on the head-groups of surfactant molecules.

  7. Effect of side chain length and degree of polymerization on the decomposition and crystallization behaviour of chlorinated poly(vinyl ester) oligomers

    International Nuclear Information System (INIS)

    Heinze, D.; Mang, Th.; Popescu, C.; Weichold, O.

    2016-01-01

    Highlights: • Thermal behaviour of telomerized polyvinyl esters is investigated. • Thermal stability relies mainly on the contribution of side chains. • At equal molecular weights thermal stability is dictated by length of side chain. • Increasing the length of side chains improves also the packing degree of polymer. - Abstract: Four members of a homologous series of chlorinated poly(vinyl ester) oligomers CCl_3–(CH_2CH (OCO(CH_2)_mCH_3))_n–Cl with degrees of polymerization of 10 and 20 were prepared by telomerisation using carbon tetrachloride. The number of side chain carbon atoms ranges from 2 (poly(vinyl acetate) to 18 (poly(vinyl stearate)). The effect of the n-alkyl side chain length and of the degree of polymerization on the thermal stability and crystallization behaviour of the synthesized compounds was investigated. All oligomers degrade in two major steps by first losing HCl and side chains with subsequent breakdown of the backbone. The members with short side chains, up to poly(vinyl octanoate), are amorphous and show internal plasticization, whereas those with high number of side chain carbon atoms are semi-crystalline due to side-chain crystallization. A better packing for poly(vinyl stearate) is also noticeable. The glass transition and melting temperatures as well as the onset temperature of decomposition are influenced to a larger extent by the side chain length than by the degree of polymerization. Thermal stability is improved if both the size and number of side chains increase, but only a long side chain causes a significant increase of the resistance to degradation. This results in a stabilization of PVAc so that oligomers from poly(vinyl octanoate) on are stable under atmospheric conditions. Thus, the way to design stable, chlorinated PVEs oligomers is to use a long n-alkyl side chain.

  8. Effect of side chain length and degree of polymerization on the decomposition and crystallization behaviour of chlorinated poly(vinyl ester) oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Heinze, D.; Mang, Th. [Aachen University of Applied Sciences, Heinrich-Mussmann-Str. 1, 52428 Jülich (Germany); Popescu, C., E-mail: crisan.popescu@kao.com [KAO Germany GmbH, Pfungstädterstr. 98-100, 64297 Darmstadt (Germany); Weichold, O., E-mail: weichold@ibac.rwth-aachen.de [Institute of Building Materials Research, Schinkelstr. 3, 52062 Aachen (Germany)

    2016-08-10

    Highlights: • Thermal behaviour of telomerized polyvinyl esters is investigated. • Thermal stability relies mainly on the contribution of side chains. • At equal molecular weights thermal stability is dictated by length of side chain. • Increasing the length of side chains improves also the packing degree of polymer. - Abstract: Four members of a homologous series of chlorinated poly(vinyl ester) oligomers CCl{sub 3}–(CH{sub 2}CH (OCO(CH{sub 2}){sub m}CH{sub 3})){sub n}–Cl with degrees of polymerization of 10 and 20 were prepared by telomerisation using carbon tetrachloride. The number of side chain carbon atoms ranges from 2 (poly(vinyl acetate) to 18 (poly(vinyl stearate)). The effect of the n-alkyl side chain length and of the degree of polymerization on the thermal stability and crystallization behaviour of the synthesized compounds was investigated. All oligomers degrade in two major steps by first losing HCl and side chains with subsequent breakdown of the backbone. The members with short side chains, up to poly(vinyl octanoate), are amorphous and show internal plasticization, whereas those with high number of side chain carbon atoms are semi-crystalline due to side-chain crystallization. A better packing for poly(vinyl stearate) is also noticeable. The glass transition and melting temperatures as well as the onset temperature of decomposition are influenced to a larger extent by the side chain length than by the degree of polymerization. Thermal stability is improved if both the size and number of side chains increase, but only a long side chain causes a significant increase of the resistance to degradation. This results in a stabilization of PVAc so that oligomers from poly(vinyl octanoate) on are stable under atmospheric conditions. Thus, the way to design stable, chlorinated PVEs oligomers is to use a long n-alkyl side chain.

  9. Tuning the probe location on zwitterionic micellar system with variation of pH and addition of surfactants with different alkyl chains: solvent and rotational relaxation studies.

    Science.gov (United States)

    Banerjee, Chiranjib; Mandal, Sarthak; Ghosh, Surajit; Rao, Vishal Govind; Sarkar, Nilmoni

    2012-09-13

    In this manuscript, we have modulated the location of an anionic probe, Coumarin-343 (C-343) in a zwitterionic (N-hexadecyl-N,N-dimethylammonio-1-propanesulfonate (SB-16)) micellar system by three different approaches. The effect of addition of the surfactant sodium dodecyl sulfate (SDS) and the room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium octylsulfate (EmimOs) and N,N-dimethylethanol hexanoate (DAH), to the micellar solution has been studied. The effect of pH variation has been studied as well using solvent and rotational measurements. Migration of the anionic probe, C-343, from the palisade layer of SB-16 micelle to the bulk water has been observed to varying extents with the addition of SDS and EmimOs. The effect is much more pronounced in the presence of SDS and can be ascribed to the presence of the long alkyl (dodecyl) chain on SDS which can easily orient itself and fuse inside the SB-16 micelle and facilitate the observed migration of the probe molecule. This phenomenon is confirmed by faster solvation and rotational relaxation of the investigated probe molecule. The analogous fusion process is difficult in case of EmimOs and DAH because of their comparatively smaller alkyl (octyl and hexanoate) chain. However, the direction of C-343 migration is reversed with the decrease of pH of the SB-16 micellar medium. An increase in the average solvation and rotational relaxation time of the probe in acidic medium has been observed. Since experimental conditions are maintained such that the probe molecules and the zwitterionic SB-16 micelles remain oppositely charged, the observed results can be attributed to the increased electrostatic interaction (attractive) between them. Temperature dependent study also supports this finding.

  10. Effects of Chain Length and Saturability of Fatty Acids on Phospholipids and Proteins in Plasma Membranes of Bovine Mammary Gland.

    Science.gov (United States)

    Yan, Qiongxian; Tang, Shaoxun; Han, Xuefeng; Bamikole, Musibau Adungbe; Zhou, Chuanshe; Kang, Jinhe; Wang, Min; Tan, Zhiliang

    2016-12-01

    Free fatty acids (FFAs) in plasma are essential substrates for de novo synthesis of milk fat, or directly import into mammary cells. The physico-chemical properties of mammary cells membrane composition affected by FFAs with different chain lengths and saturability are unclear yet. Employing GC, FTIR and fluorescence spectroscopy, the adsorption capacity, phospholipids content, membrane proteins conformation, lipid peroxidation product, and free sulfhydryl of plasma membranes (PMs) interacted with different FFAs were determined. The mammary cells PMs at 38 and 39.5 °C showed different adsorption capacities: acetic acid (Ac) > stearic acid (SA) > β-hydroxybutyric acid (BHBA) > trans10, cis12 CLA. In the FTIR spectrum, the major adsorption peaks appeared at 2920 and 2850 cm -1 for phospholipids, and at 1628 and 1560 cm -1 for membrane proteins. The intensities of PMs-FFAs complexes were varied with the FFAs species and their initial concentrations. The β-sheet and turn structures of membrane proteins were transferred into random coil and α-helix after BHBA, SA and trans10, cis12 CLA treatments compared with Ac treatment. The quenching effects on the fluorescence of endogenous membrane protein, 1, 8-ANS, NBD-PE, and DHPE entrapped in PMs by LCFA were different from those of short chain FFAs. These results indicate that the adsorption of FFAs could change membrane protein conformation and polarity of head group in phospholipids. This variation of the mammary cells PMs was regulated by carbon chain length and saturability of FFAs.

  11. 4-N, 4-S & 4-O Chloroquine Analogues: Influence of Side Chain Length and Quinolyl Nitrogen pKa on Activity vs. Chloroquine Resistant Malaria+, #

    OpenAIRE

    Natarajan, Jayakumar K.; Alumasa, John; Yearick, Kimberly; Ekoue-Kovi, Kekeli A.; Casabianca, Leah B.; de Dios, Angel C.; Wolf, Christian; Roepe, Paul D.

    2008-01-01

    Using predictions from heme – quinoline antimalarial complex structures, previous modifications of chloroquine (CQ), and hypotheses for chloroquine resistance (CQR), we synthesize and assay CQ analogues that test structure – function principles. We vary side chain length for both monoethyl and diethyl 4N CQ derivatives. We alter the pKa of the quinolyl N by introducing alkylthio or alkoxy substituents into the 4 position, and vary side chain length for these analogues. We introduce an additio...

  12. Partition thermodynamics of ionic surfactants between phosphatidylcholine vesicle and water phases

    Science.gov (United States)

    Chu, Shin-Chi; Hung, Chia-Hui; Wang, Shun-Cheng; Tsao, Heng-Kwong

    2003-08-01

    The partition of ionic surfactants (sodium alkyl sulfate and alkyl trimethyl ammonium bromide) between phosphatidylcholine vesicles and aqueous phase is investigated by simple conductometry under different temperatures. The experimental results can be well represented by the proposed regular solution theory and the thermodynamic parameters satisfy the thermodynamic consistency. The deviation from ideal partition is manifested through the effective interaction energy between lipid and surfactant wb, which is O(kT) large. It is found that wb rises as the alkyl chain is decreased for a specified head group. This is attributed to significant mismatch of chain lengths between surfactant and lipid molecules. The partition coefficient K declines with increasing temperature. The energy barrier from bilayer to aqueous phase, Δμ/kT∝ln K, is in the range of 16-26 kJ/mol. As the alkyl chain length is decreased for a given head group, Δμ is lowered by 1.3-1.5 kJ/mol per methylene group. Two independent analyses are employed to confirm this result. Using the thermodynamic parameters determined from experiments, the internal energy, entropy, and free energy of the partition process can be derived. Partition is essentially driven by the internal energy gain. The solubilizing ability, which is represented by the maximum surfactant-lipid ratio in the bilayer, Reb also decreases in accord with the K parameter. It is because the change in temperature influences the surfactant incorporation into the bilayer more than the formation of micelles.

  13. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    Science.gov (United States)

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions.

  14. Application of nitrogen and carbon stable isotopes (δ(15N and δ(13C to quantify food chain length and trophic structure.

    Directory of Open Access Journals (Sweden)

    Matthew J Perkins

    Full Text Available Increasingly, stable isotope ratios of nitrogen (δ(15N and carbon (δ(13C are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR using δ(15N, and carbon range (CR using δ(13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15N or δ(13C from source to consumer between trophic levels and among food chains. δ(15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰, and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority

  15. Application of Nitrogen and Carbon Stable Isotopes (δ15N and δ13C) to Quantify Food Chain Length and Trophic Structure

    Science.gov (United States)

    Perkins, Matthew J.; McDonald, Robbie A.; van Veen, F. J. Frank; Kelly, Simon D.; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ15N, and carbon range (CR) using δ13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ15N or δ13C from source to consumer) between trophic levels and among food chains. δ15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of ecological systems

  16. Application of nitrogen and carbon stable isotopes (δ(15)N and δ(13)C) to quantify food chain length and trophic structure.

    Science.gov (United States)

    Perkins, Matthew J; McDonald, Robbie A; van Veen, F J Frank; Kelly, Simon D; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ(15)N, and carbon range (CR) using δ(13)C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15)N or δ(13)C from source to consumer) between trophic levels and among food chains. δ(15)N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13)C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13)C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of

  17. Interactions of a zwitterionic thiophene-based conjugated polymer with surfactants

    DEFF Research Database (Denmark)

    Costa, Telma; De Azevedo, Diego; Stewart, Beverly

    2015-01-01

    In this paper we investigate the optical and structural properties of a zwitterionic poly[3-(N-(4-sulfonato-1-butyl)-N,N-diethylammonium)hexyl-2,5-thiophene] (P3SBDEAHT) conjugated polyelectrolyte (CPE) and its interaction in water with surfactants, using absorption, photoluminescence (PL......), electrical conductivity, molecular dynamics simulations (MDS) and small-angle X-ray scattering (SAXS). Different surfactants were studied to evaluate the effect of the head group and chain length on the self-assembly. PL data emphasize the importance of polymer-surfactant electrostatic interactions...... in the formation of complexes. Nevertheless, conductivity and MDS data have shown that nonspecific interactions also play an important role. These seem to be responsible for the spatial position of the surfactant tail in the complex and, eventually, for breaking-up P3SBDEAHT aggregates. SAXS measurements on P3...

  18. PEGylation of Phytantriol-Based Lyotropic Liquid Crystalline Particles-The Effect of Lipid Composition, PEG Chain Length, and Temperature on the Internal Nanostructure

    DEFF Research Database (Denmark)

    Nilsson, Christa; Ostergaard, Jesper; Larsen, Susan Weng

    2014-01-01

    of these lipidic nonlamellar liquid crystalline particles by using DSPE-mPEGs with three different block lengths of the hydrophilic PEG segment. The effects of lipid composition, PEG chain length, and temperature on the morphology and internal nanostructure of these self-assembled lipidic aqueous dispersions based...

  19. Effect of Hydrophobic Chain Length on the Stability and Guest Exchange Behavior of Shell-Sheddable Micelles Formed by Disulfide-Linked Diblock Copolymers.

    Science.gov (United States)

    Fan, Haiyan; Li, Yixia; Yang, Jinxian; Ye, Xiaodong

    2017-10-19

    Reduction-responsive micelles hold enormous promise for application as drug carriers due to the fast drug release triggered by reducing conditions and high anticancer activity. However, the effect of hydrophobic chain length on the stability and guest exchange of reduction-responsive micelles, especially for the micelles formed by diblock copolymers containing single disulfide group, is not fully understood. Here, shell-sheddable micelles formed by a series of disulfide-linked copolymer poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-SS-PCL) containing the same chain length of PEG but different chain lengths of hydrophobic block PCL were prepared and well characterized. The influence of the chain length of hydrophobic PCL block on the stability and guest exchange of PEG-SS-PCL micelles was studied by the use of both dynamic laser light scattering (DLS) and fluorescence resonance energy transfer (FRET). The results show that longer PCL chains lead to a slower aggregation rate and guest exchange of micelles in the aqueous solutions containing 10 mM dithiothreitol (DTT). The cell uptake of the shell-sheddable PEG-SS-PCL micelles in vitro shows that the amount of internalization of dyes loaded in PEG-SS-PCL micelles increases with the chain length of hydrophobic PCL block investigated by flow cytometric analysis and confocal fluorescence microscopy.

  20. HLA-DPB1 typing with polymerase chain reaction and restriction fragment length polymorphism technique in Danes

    DEFF Research Database (Denmark)

    Hviid, Thomas Vauvert F.; Madsen, Hans O; Morling, Niels

    1992-01-01

    We have used the polymerase chain reaction (PCR) in combination with the restriction fragment length polymorphism (RFLP) technique for HLA-DBP1 typing. After PCR amplification of the polymorphic second exon of the HLA-DPB1 locus, the PCR product was digested with seven allele-specific restriction...... endonucleases: RsaI, FokI, ApaI, SacI, BstUI, EcoNI, and DdeI, and the DNA fragments were separated by electrophoresis in agarose gels. Altogether, 71 individuals were investigated and 16 different HLA-DPB1 types were observed in 26 different heterozygotic combinations, as well as five possible homozygotes....... Four heterozygotes could not be unequivocally typed with the PCR-RFLP method. The HLA-DPB1 typing results obtained with the PCR-RFLP method were compared with the typing results obtained with PCR allele-specific oligonucleotides (PCR-ASO) in 50 individuals. The results obtained with the two methods...

  1. Modulation of saturation and chain length of fatty acids in Saccharomyces cerevisiae for production of cocoa butter-like lipids

    DEFF Research Database (Denmark)

    Bergenholm, David; Gossing, Michael; Wei, Yongjun

    2018-01-01

    Chain length and degree of saturation plays an important role for the characteristics of various products derived from fatty acids, such as fuels, cosmetics, and food additives. The seeds of Theobroma cacao are the source of cocoa butter, a natural lipid of high interest for the food and cosmetics...... as the saturated fatty acid stearic acid is typically found only in low abundance. Demand for cocoa butter is increasing, yet T. cacao can only be cultivated in some parts of the tropics. Alternative means of production of cocoa butter lipids (CBLs) are, therefore, sought after. Yeasts also store fatty acids...... industry. Cocoa butter is rich in saturated fatty acids that are stored in the form of triacylglycerides (TAGs). One of the major TAG species of cocoa butter, consisting of two stearic acid molecules and one oleic acid molecule (stearic acid-oleic acid-stearic acid, sn-SOS), is particularly rare in nature...

  2. A kinetic model for growth and biosynthesis of medium-chain-length poly-(3-hydroxyalkanoates in Pseudomonas putida

    Directory of Open Access Journals (Sweden)

    M. S. M. Annuar

    2008-06-01

    Full Text Available A kinetic model is presented giving a mathematical description of batch culture of Pseudomonas putida PGA1 grown using saponified palm kernel oil as carbon source and ammonium as the limiting nutrient. The growth of the micro-organism is well-described using Tessier-type model which takes into account the inhibitory effect of ammonium at high concentrations. The ammonium consumption rate by the cells is related in proportion to the rate of growth. The intracellular production of medium-chain-length poly-(3-hydroxyalkanoates (PHA MCL by P. putida PGA1 cells is reasonably modeled by the modified Luedeking-Piret kinetics, which incorporate a function of product synthesis inhibition (or reduction by ammonium above a threshold level.

  3. The Relationship between the Monomer Chain Length and the Electro-Optical Properties of Polymer Dispersed Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Liu J.

    2016-03-01

    Full Text Available Five polymers dispersed liquid crystalline (LC films were fabricated using photo-polymerizable monomers with different lengths of carbon chains. These LC films have shown different electro-optical (EO properties. Through their SEM pictures, the relationship between the linear electro-optical effect and the mesh size of the polymer network was explored. With the increase of number of photo-polymerizable monomers, the mesh size of the polymer network would become larger. So the liquid crystal molecules would be easily oriented in the electric field and therefore, the threshold voltage and saturation voltage would decrease. The open state response times were also reduced and the off state response times would be extended. The DFT simulations have shown principal role of the ground state dipole moments in the observed electro-optical efficiency.

  4. Production of Medium Chain Length Polyhydroxyalkanoates From Oleic Acid Using Pseudomonas putida PGA1 by Fed Batch Culture

    Directory of Open Access Journals (Sweden)

    Sidik Marsudi

    2010-10-01

    Full Text Available Bacterial polyhydroxyalkanoates (PHAs are a class of p0lymers currently receiving much attention because of their potential as renewable and biodegradable plastics. A wide variety of bacteria has been reported to produce PHAs including Pseudomonas strains. These strains are known as versatile medium chain length PHAs (PHAs-mcl producers using fatty acids as carbon source. Oleic acid was used to produce PHAs-mcl using Pseudomonas putida PGA 1 by continuous feeding of both nitrogen and carbon source, in a fed batch culture. During cell growth, PHAs also accumulated, indicating that PHA production in this organism is growth associated. Residual cell increased until the nitrogen source was depleted. At the end of fermentation, final cell concentration, PHA content, and roductivity were 30.2 g/L, 44.8 % of cell dry weight, and 0.188 g/l/h, respectively.

  5. Synthesis of Medium-Chain-Length Polyhydroxyalkanoate Homopolymers, Random Copolymers, and Block Copolymers by an Engineered Strain of Pseudomonas entomophila.

    Science.gov (United States)

    Wang, Ying; Chung, Ahleum; Chen, Guo-Qiang

    2017-04-01

    Medium-chain-length polyhydroxyalkanoates (mcl-PHAs), widely used in medical area, are commonly synthesized by Pseudomonas spp. This study tries to use β-oxidation pathways engineered P. entomophila to achieve single source of a series of mcl-monomers for microbial production of PHA homopolymers. The effort is proven successful for the first time to obtain a wide range of mcl-PHA homopolymers from engineered P. entomophila LAC23 grown on various fatty acids, respectively, ranging from poly(3-hydroxyheptanoate) to poly(3-hydroxytetradecanoate). Effects of a PHA monomer chain length on thermal and crystallization properties including the changes of T m , T g , and T d5% are investigated. Additionally, strain LAC23 is used to synthesize random copolymers of 3-hydroxyoctanoate (3HO) and 3-hydroxydodecanoate (3HDD) or 3-hydroxytetradecanoates, their compositions could be controlled by adjusting the ratios of two related fatty acids. Meanwhile, block copolymer P(3HO)-b-P(3HDD) is synthesized by the same strain. It is found for the first time that even- and odd number mcl-PHA homopolymers have different physical properties. When the gene of the PHA synthase in the engineered P. entomophila is replaced by phaC from Aeromonas hydrophila 4AK4, poly(3-hydroxybutyrate-co-30 mol%-3-hydroxyhexanoate) is synthesized. Therefore, P. entomophila can be used to synthesize the whole range of PHA (C7-C14) homopolymers, random- and block copolymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH 2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH 2 ) considered are acetamide (CH 3 CONH 2 ), propionamide (CH 3 CH 2 CONH 2 ), and butyramide (CH 3 CH 2 CH 2 CONH 2 ); the electrolytes (LiX) are lithium perchlorate (LiClO 4 ), lithium bromide (LiBr), and lithium nitrate (LiNO 3 ). 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 (CH 3 CONH 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 terms of temporal heterogeneity and amide clustering in these multi

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

    Science.gov (United States)

    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.

  8. Analysis of polyethoxylated surfactants in microemulsion-oil-water systems III. Fractionation and partitioning of polyethoxylated alcohol surfactants

    International Nuclear Information System (INIS)

    Marquez, N.; Bravo, B.; Ysambertt, F.; Chavez, G.; Subero, N.; Salager, J.L.

    2002-01-01

    Oligomer distribution of polyethoxylated alcohol and polyethoxylated nonylphenol surfactants is studied by normal and reverse-phase high performance liquid chromatography (HPLC). A RP8 column is able to efficiently separate these surfactants according to their alkyl chain (lipophilic) group, while silica and amino columns separate them according to their polyether chain length (hydrophilic group). Polyethoxylated alcohol and polyethoxylated nonylphenol oligomers selectively partition between the microemulsion-oil-water phases of a Winsor III system. Partitioning of these oligomers was analyzed by HPLC with RI detection. The logarithm of the partition coefficient between the water and oil linearly increases with the number of ethylene oxide groups per molecule of oligomer. For a same ethoxylation degree, the partition coefficient of a polyethoxylated tridecanol is found to be higher than the one of the corresponding nonylphenol specie. On the other hand, a polyethoxylated nonylphenol exhibits a higher solubilization than the matching polyethoxylated alcohol

  9. Effect of the number, position and length of alkyl chains on the physical properties of polysubstituted pyridinium ionic liquids

    International Nuclear Information System (INIS)

    Verdía, Pedro; Hernaiz, Marta; González, Emilio J.; Macedo, Eugénia A.; Salgado, Josefa; Tojo, Emilia

    2014-01-01

    Highlights: • Synthesis of five polysubstituted pyridinium based-ionic liquids. • Physical properties of the pure ionic liquids were measured at several temperatures. • Thermal analysis of the pure ionic liquids was carried out by DSC and TGA techniques. • Density, speed of sound, and refractive index were fitted with a linear expression. • Viscosity data were correlated using the VFT equation. -- Abstract: The knowledge of the physical properties of ionic liquids is of high importance in order to evaluate their potential applicability for a given purpose. In the last few years, ionic liquids have been proposed as promising solvents for extractive desulfurization of fuels. Among them, recent studies have shown that ionic liquids derived from pyridinium affords excellent S-compounds removal capacity. In this work, the thermal analysis of five ionic liquids derived from pyridinium cation polysubstituted with different alkyl chains was carried out by Differencial Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA). Furthermore, the density, speed of sound, refractive index and dynamic viscosity for all the pure ionic liquids were also measured from T = (298.15 to 343.15) K. The effect of the number of cation alkyl chains, their length, and their position on the pyridinium ring, on the ionic liquid physical properties is also analyzed and discussed

  10. Increased mean aliphatic lipid chain length in left ventricular hypertrophy secondary to arterial hypertension: A cross-sectional study.

    Science.gov (United States)

    Evaristi, Maria Francesca; Caubère, Céline; Harmancey, Romain; Desmoulin, Franck; Peacock, William Frank; Berry, Matthieu; Turkieh, Annie; Barutaut, Manon; Galinier, Michel; Dambrin, Camille; Polidori, Carlo; Miceli, Cristina; Chamontin, Bernard; Koukoui, François; Roncalli, Jerôme; Massabuau, Pierre; Smih, Fatima; Rouet, Philippe

    2016-11-01

    About 77.9 million (1 in 4) American adults have high blood pressure. High blood pressure is the primary cause of left ventricular hypertrophy (LVH), which represents a strong predictor of future heart failure and cardiovascular mortality. Previous studies have shown an altered metabolic profile in hypertensive patients with LVH. The goal of this study was to identify blood metabolomic LVH biomarkers by H NMR to provide novel diagnostic tools for rapid LVH detection in populations of hypertensive individuals. This cross-sectional study included 48 hypertensive patients with LVH matched with 48 hypertensive patients with normal LV size, and 24 healthy controls. Two-dimensional targeted M-mode echocardiography was performed to measure left ventricular mass index. Partial least squares discriminant analysis was used for the multivariate analysis of the H NMR spectral data. From the H NMR-based metabolomic profiling, signals coming from methylene (-CH2-) and methyl (-CH3) moieties of aliphatic chains from plasma lipids were identified as discriminant variables. The -CH2-/-CH3 ratio, an indicator of the mean length of the aliphatic lipid chains, was significantly higher (P hypertensive group without LVH and controls. Receiver operating characteristic curve showed that a cutoff of 2.34 provided a 52.08% sensitivity and 85.42% specificity for discriminating LVH (AUC = 0.703, P-value hypertension.

  11. Fatty acid biosynthesis VII. Substrate control of chain-length of products synthesised by rat liver fatty acid synthetase

    DEFF Research Database (Denmark)

    Hansen, Heinz Johs. Max; Carey, E.M.; Dils, R.

    1970-01-01

    - 1. Gas-liquid and paper chromatography have been used to determine the chain-lengths of fatty acids synthesised by purified rat liver fatty acid synthetase from [1-14C]acetyl-CoA, [1,3-14C2]malonyl-CoA and from [1-14C]acetyl-CoA plus partially purified rat liver acetyl-CoA carboxylase. - 2....... A wide range (C4:0–C18:0) of fatty acids was synthesised and the proportions were modified by substrate concentrations in the same manner as for purified rabbit mammary gland fatty acid synthetase. - 3. The relative amount of radioactivity incorporated from added acetyl-CoA and malonyl-CoA depended...... of long-chain fatty acids was synthesised from carboxylated acetyl-CoA than from added malonyl-CoA. - 5. It is suggested that acetyl-CoA carboxylase may carboxylate acetate bound to fatty acid synthetase....

  12. Adsorption of sugar surfactants at the air/water interface.

    Science.gov (United States)

    Varga, Imre; Mészáros, Róbert; Stubenrauch, Cosima; Gilányi, Tibor

    2012-08-01

    The adsorption isotherms of n-decyl-β-D-glucoside (β-C(10)G(1)) as well as various n-alkyl-β-D-maltosides (β-C(n)G(2)) with n=8, 10, 12 and 14 were determined from surface tension measurements. Based on the analysis of the adsorption isotherms, the total free energy change of adsorption was determined and a novel method was proposed to determine the maximum adsorbed amount of surfactant. It can be concluded that the driving force for adsorption first increases with increasing adsorbed amount of the sugar surfactants and then levels off in a plateau. This peculiar behaviour is interpreted as formation of a thin liquid-like alkane film of overlapping alkyl chains at the air/water interface once a certain adsorbed amount is exceeded. The driving force of adsorption depends on the alkyl chain length only and is not affected by the type of the head group. The hydrophobic contribution to the standard free energy change of adsorption was compared with the values of sodium alkylsulfate and alkyltrimethylammonium bromide surfactants. This comparison reveals that the hydrophobic driving force of adsorption is the largest for the sodium alkylsulfates, whereas it is the same for the sugar surfactants and the alkyltrimethylammonium bromides. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Effect of surfactants on the properties of hydrotalcites prepared by the reverse micelle method

    Energy Technology Data Exchange (ETDEWEB)

    Holgado, Patricia H., E-mail: h.holgado@usal.es; Holgado, María J., E-mail: holgado@usal.es; San Román, María S., E-mail: sanroman@usal.es; Rives, Vicente, E-mail: vrives@usal.es

    2015-02-01

    Layered double hydroxides with the hydrotalcite-type structure have been prepared by the reverse micelles method. The layer cations were Ni{sup 2+} and Fe{sup 3+} in all cases and the interlayer anion was carbonate. We have studied the effect of the surfactant used (with linear chains of different lengths, or cyclic) and the effect of the pH on the properties of the solids formed. These have been characterized by element chemical analysis, powder X-ray diffraction, thermogravimetric analysis, temperature-programmed reduction, FT-IR and Vis–UV spectroscopies and scanning electron microscopy. It has been found that the samples prepared at pH 9 are more crystalline than those prepared at pH 11 and their crystallite sizes are always larger than for samples prepared by the conventional precipitation method. Surfactants with cyclic organic chains lead to a larger crystallite size, probably because the water pool vesicle where the crystallite grows is larger due to sterical hindrance of the organic chains. - Graphical abstract: Layered double hydroxides with the hydrotalcite-type structure with Ni{sup 2+} and Fe{sup 3+} cations in the layers have been prepared by the reverse micelles method. Different surfactants were used at different pH synthesis. Samples prepared at pH 9 are higher crystalline than those prepared at pH 11. Surfactants with cyclic organic chains lead to a larger crystallite size. - Highlights: • Hydrotalcites were prepared by the micelles reverse method. • Straight alkyl or cyclic chain surfactants were used. • All hydrotalcites are well crystallized at pH = 9 and 11. • The crystallite size depends on the linear/cyclic nature of the surfactant chain.

  14. Effect of surfactants on the properties of hydrotalcites prepared by the reverse micelle method

    International Nuclear Information System (INIS)

    Holgado, Patricia H.; Holgado, María J.; San Román, María S.; Rives, Vicente

    2015-01-01

    Layered double hydroxides with the hydrotalcite-type structure have been prepared by the reverse micelles method. The layer cations were Ni 2+ and Fe 3+ in all cases and the interlayer anion was carbonate. We have studied the effect of the surfactant used (with linear chains of different lengths, or cyclic) and the effect of the pH on the properties of the solids formed. These have been characterized by element chemical analysis, powder X-ray diffraction, thermogravimetric analysis, temperature-programmed reduction, FT-IR and Vis–UV spectroscopies and scanning electron microscopy. It has been found that the samples prepared at pH 9 are more crystalline than those prepared at pH 11 and their crystallite sizes are always larger than for samples prepared by the conventional precipitation method. Surfactants with cyclic organic chains lead to a larger crystallite size, probably because the water pool vesicle where the crystallite grows is larger due to sterical hindrance of the organic chains. - Graphical abstract: Layered double hydroxides with the hydrotalcite-type structure with Ni 2+ and Fe 3+ cations in the layers have been prepared by the reverse micelles method. Different surfactants were used at different pH synthesis. Samples prepared at pH 9 are higher crystalline than those prepared at pH 11. Surfactants with cyclic organic chains lead to a larger crystallite size. - Highlights: • Hydrotalcites were prepared by the micelles reverse method. • Straight alkyl or cyclic chain surfactants were used. • All hydrotalcites are well crystallized at pH = 9 and 11. • The crystallite size depends on the linear/cyclic nature of the surfactant chain

  15. Adsorption of dissymmetric cationic gemini surfactants at silica/water interface

    Science.gov (United States)

    Sun, Yuhai; Feng, Yujun; Dong, Hongwei; Chen, Zhi

    2007-05-01

    Adsorption of a series of cationic gemini surfactants 12-2- m ( m = 8, 12, 16) on the surface of silica was investigated. The critical micelle concentrations, cmcs, of cationic gemini surfactants in the initial solutions and in the supernatants were measured by conductometry and tensiometer. The changes in cmc values indicate that the ion exchanges take place between polar groups of gemini surfactants adsorbed and ions bound on the surface of silica. The adsorption isotherms of cationic gemini surfactants were obtained by a solution depletion method. Based on the driving force, the adsorption includes two steps, one of which is ion exchange, and the other is hydrophobic interaction. In each step, the tendency of surfactant molecules in the solution to form aggregates or to be adsorbed on the silica varies with their structures. The maximum adsorption amount of gemini surfactants on the silica, τmax, decreases as increasing in the length of one alkyl chain, m, from 8, 12 to 16. So the results show that the adsorption behaviors of gemini surfactants are closely related to the dissymmetry of gemini molecules.

  16. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Lixia [National Key Laboratory of Science and Technology on Vacuum Technology and Physics, Lanzhou Institute of Physics, Lanzhou, Gansu 730010 (China); Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China); Du, Pengcheng [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China); Zhou, Hui; Zhang, Kaifeng [National Key Laboratory of Science and Technology on Vacuum Technology and Physics, Lanzhou Institute of Physics, Lanzhou, Gansu 730010 (China); Liu, Peng, E-mail: pliu@lzu.edu.cn [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China)

    2017-02-28

    Highlights: • n-Alkyltrimethoxysilanes with various chain lengths were self-assembled on silicon. • Effect of alkyl chain lengths (C6, C12, or C18) on the SAMs was investigated. • Surface roughness of the SAMs decreased with increasing the alkyl chain lengths. • The C{sub 12}-SAM possessed superior friction reduction and wear resistance. - Abstract: It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C{sub 6}, C{sub 12}, or C{sub 18}) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (R{sub a}) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al{sub 2}O{sub 3} ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C{sub 12} alkyl chain (C{sub 12}-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C{sub 12}-SAM with desirable alkyl chain length.

  17. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    International Nuclear Information System (INIS)

    Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng

    2017-01-01

    Highlights: • n-Alkyltrimethoxysilanes with various chain lengths were self-assembled on silicon. • Effect of alkyl chain lengths (C6, C12, or C18) on the SAMs was investigated. • Surface roughness of the SAMs decreased with increasing the alkyl chain lengths. • The C 12 -SAM possessed superior friction reduction and wear resistance. - Abstract: It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C 6 , C 12 , or C 18 ) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (R a ) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al 2 O 3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C 12 alkyl chain (C 12 -SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C 12 -SAM with desirable alkyl chain length.

  18. Thermodynamic stability and retinol binding property of {beta}-lactoglobulin in the presence of cationic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Sahihi, M. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Bordbar, A.K., E-mail: bordbar@chem.ui.ac.ir [Department of Chemistry, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Ghayeb, Y. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2011-08-15

    Highlights: > The stability parameters of {beta}-lactoglobulin, BLG, in the presence of C{sub n}TAB have been evaluated. > Rising in hydrocarbon chain length increases the denaturating power of surfactants. > C{sub n}TAB enhances the retinol binding affinity of BLG in all of its concentration range. - Abstract: In this work the stability parameters of bovine {beta}-lactoglobulin, variant A (BLG-A), with regard to their transition curves induced by dodecyltrimethylammonium bromide (C{sub 12}TAB), tetradecyltrimethylammonium bromide (C{sub 14}TAB) and hexadecyltrimethylammonium bromide (C{sub 16}TAB) as cationic surfactants, were determined at 298 K. For each transition curve, the conventional method of analysis which assumes a linear concentration dependence of the pre- and post-transition base lines, gave the most realistic values for {Delta}G{sub D}(H{sub 2}O). The results represent the increase in the denaturating power of surfactants with an increase in hydrocarbon chain length. The value of about 22.27 kJ . mol{sup -1} was obtained for {Delta}G{sub D}(H{sub 2}O) from transition curves. Subsequently, the retinol binding property of BLG as its functional indicator was investigated in the presence of these surfactants using the spectrofluorimeter titration method. The results represent the substantial enhancement of retinol binding affinity of BLG in the presence of these surfactants.

  19. Comparison of Chain-Length Preferences and Glucan Specificities of Isoamylase-Type α-Glucan Debranching Enzymes from Rice, Cyanobacteria, and Bacteria.

    Directory of Open Access Journals (Sweden)

    Taiki Kobayashi

    Full Text Available It has been believed that isoamylase (ISA-type α-glucan debranching enzymes (DBEs play crucial roles not only in α-glucan degradation but also in the biosynthesis by affecting the structure of glucans, although molecular basis on distinct roles of the individual DBEs has not fully understood. In an attempt to relate the roles of DBEs to their chain-length specificities, we analyzed the chain-length distribution of DBE enzymatic reaction products by using purified DBEs from various sources including rice, cyanobacteria, and bacteria. When DBEs were incubated with phytoglycogen, their chain-length specificities were divided into three groups. First, rice endosperm ISA3 (OsISA3 and Eschericia coli GlgX (EcoGlgX almost exclusively debranched chains having degree of polymerization (DP of 3 and 4. Second, OsISA1, Pseudomonas amyloderamosa ISA (PsaISA, and rice pullulanase (OsPUL could debranch a wide range of chains of DP≧3. Third, both cyanobacteria ISAs, Cyanothece ATCC 51142 ISA (CytISA and Synechococcus elongatus PCC7942 ISA (ScoISA, showed the intermediate chain-length preference, because they removed chains of mainly DP3-4 and DP3-6, respectively, while they could also react to chains of DP5-10 and 7-13 to some extent, respectively. In contrast, all these ISAs were reactive to various chains when incubated with amylopectin. In addition to a great variation in chain-length preferences among various ISAs, their activities greatly differed depending on a variety of glucans. Most strikingly, cyannobacteria ISAs could attack branch points of pullulan to a lesser extent although no such activity was found in OsISA1, OsISA3, EcoGlgX, and PsaISA. Thus, the present study shows the high possibility that varied chain-length specificities of ISA-type DBEs among sources and isozymes are responsible for their distinct functions in glucan metabolism.

  20. Bacterial membrane activity of a-peptide/b-peptoid chimeras: Influence of amino acid composition and chain length on the activity against different bacterial strains

    DEFF Research Database (Denmark)

    Hein-Kristensen, Line; Knapp, Kolja M; Franzyk, Henrik

    2011-01-01

    and subsequent killing is usually not tested. In this report, six α-peptide/β-peptoid chimeras were examined for the effect of amino acid/peptoid substitutions and chain length on the membrane perturbation and subsequent killing of food-borne and clinical bacterial isolates. RESULTS: All six AMP analogues...... acid only had a minor effect on MIC values, whereas chain length had a profound influence on activity. All chimeras were less active against Serratia marcescens (MICs above 46 μM). The chimeras were bactericidal and induced leakage of ATP from Staphylococcus aureus and S. marcescens with similar time...... of onset and reduction in the number of viable cells. EDTA pre-treatment of S. marcescens and E. coli followed by treatment with chimeras resulted in pronounced killing indicating that disintegration of the Gram-negative outer membrane eliminated innate differences in susceptibility. Chimera chain length...

  1. On the chain length dependence of local correlations in polymer melts and a perturbation theory of symmetric polymer blends.

    Science.gov (United States)

    Morse, David C; Chung, Jun Kyung

    2009-06-14

    The self-consistent field (SCF) approach to the thermodynamics of dense polymer liquids is based on the idea that short-range correlations in a polymer liquid are almost independent of how monomers are connected into polymers over larger scales. Some limits of this idea are explored in the context of a perturbation theory for symmetric polymer blends. We consider mixtures of two structurally identical polymers, A and B, in which the AB monomer pair interaction differs slightly from the AA and BB interactions by an amount proportional to a parameter alpha. An expansion of the free energy to first order in alpha yields an excess free energy of mixing per monomer of the form alphaz(N)phi(A)phi(B) in both lattice and continuum models, where z(N) is a measure of the number of intermolecular near neighbors per monomer in a one-component (alpha=0) reference liquid with chains of length N. The quantity z(N) decreases slightly with increasing N because the concentration of intramolecular near neighbors is slightly higher for longer chains, creating a slightly deeper intermolecular correlation hole. We predict that z(N)=z(infinity)[1+betaN(-1/2)], where N is an invariant degree of polymerization and beta=(6/pi)(3/2) is a universal coefficient. This and related predictions about the slight N dependence of local correlations are confirmed by comparison to simulations of a continuum bead-spring model and to published lattice Monte Carlo simulations. We show that a renormalized one-loop theory for blends correctly describes this N dependence of local liquid structure. We also propose a way to estimate the effective interaction parameter appropriate for comparisons of simulation data to SCF theory and to coarse-grained theories of corrections to SCF theory, which is based on an extrapolation of perturbation theory to the limit N-->infinity.

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

    Energy Technology Data Exchange (ETDEWEB)

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit, E-mail: ranjit@bose.res.in [Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India)

    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

  3. Influence of trehalose 6,6'-diester (TDX) chain length on the physicochemical and immunopotentiating properties of DDA/TDX liposomes

    DEFF Research Database (Denmark)

    Kallerup, Rie Selchau; Madsen, Cecilie Maria; Schiøth, Mikkel Lohmann

    2015-01-01

    Linking physicochemical characterization to functional properties is crucial for defining critical quality attributes during development of subunit vaccines toward optimal safety and efficacy profiles. We investigated how the trehalose 6,6'-diester (TDX) chain length influenced the physicochemical...... and immunopotentiating properties of the clinically tested liposomal adjuvant composed of dimethyldioctadecylammonium (DDA) bromide and analogues of trehalose-6,6'-dibehenate (TDB). TDB analogues with symmetrically shortened acyl chains [denoted X: arachidate (A), stearate (S), palmitate (P), myristate (Myr) and laurate...

  4. Evaluation of medium-chain-length polyhydroxyalkanoate production by Pseudomonas putida LS46 using biodiesel by-product streams.

    Science.gov (United States)

    Fu, Jilagamazhi; Sharma, Umesh; Sparling, Richard; Cicek, Nazim; Levin, David B

    2014-07-01

    Medium-chain-length polyhydroxyalkanoate (mcl-PHA) production by Pseudomonas putida LS46 was analyzed in shake-flask-based batch reactions, using pure chemical-grade glycerol (PG), biodiesel-derived "waste" glycerol (WG), and biodiesel-derived "waste" free fatty acids (WFA). Cell growth, substrate consumption, mcl-PHA accumulation within the cells, and the monomer composition of the synthesized biopolymers were monitored. The patterns of mcl-PHA synthesis in P. putida LS46 cells grown on PG and WG were similar but differed from that of cells grown with WFA. Polymer accumulation in glycerol-based cultures was stimulated by nitrogen limitation and plateaued after 48 h in both PG and WG cultures, with a total accumulation of 17.9% cell dry mass and 16.3% cell dry mass, respectively. In contrast, mcl-PHA synthesis was independent of nitrogen concentration in P. putida LS46 cells cultured with WFA, which accumulated to 29% cell dry mass. In all cases, the mcl-PHAs synthesized consisted primarily of 3-hydroxyoctanoate (C(8)) and 3-hydroxydecanoate (C(10)). WG and WFA supported similar or greater cell growth and mcl-PHA accumulation than PG under the experimental conditions used. These results suggest that biodiesel by-product streams could be used as low-cost carbon sources for sustainable mcl-PHA production.

  5. Identification of Echinococcus granulosus strains using polymerase chain reaction-restriction fragment length polymorphism amongst livestock in Moroto district, Uganda.

    Science.gov (United States)

    Chamai, Martin; Omadang, Leonard; Erume, Joseph; Ocaido, Michael; Oba, Peter; Othieno, Emmanuel; Bonaventure, Straton; Kitibwa, Annah

    2016-07-29

    A descriptive study was conducted to identify the different strains of Echinococcus granulosus occurring in livestock in Moroto district, Uganda. Echinococcus cysts from 104 domestic animals, including cattle, sheep, goats and camels, were taken and examined by microscopy, polymerase chain reaction with restriction fragment length polymorphism and Sanger DNA sequencing. Echinococcus granulosus genotypes or strains were identified through use of Bioinformatics tools: BioEdit, BLAST and MEGA6. The major finding of this study was the existence of a limited number of E. granulosus genotypes from cattle, goats, sheep and camels. The most predominant genotype was G1 (96.05%), corresponding to the common sheep strain. To a limited extent (3.95%), the study revealed the existence of Echinococcus canadensis G6/7 in three (n = 3) of the E. granulosus-positive samples. No other strains of E. granulosus were identified. It was concluded that the common sheep strain of Echinococcus sensu stricto and G6/7 of E. canadensis were responsible for echinococcal disease in Moroto district, Uganda.

  6. Effects of Odd–Even Side Chain Length of Alkyl-Substituted Diphenylbithiophenes on First Monolayer Thin Film Packing Structure

    KAUST Repository

    Akkerman, Hylke B.

    2013-07-31

    Because of their preferential two-dimensional layer-by-layer growth in thin films, 5,5′bis(4-alkylphenyl)-2,2′-bithiophenes (P2TPs) are model compounds for studying the effects of systematic chemical structure variations on thin-film structure and morphology, which in turn, impact the charge transport in organic field-effect transistors. For the first time, we observed, by grazing incidence X-ray diffraction (GIXD), a strong change in molecular tilt angle in a monolayer of P2TP, depending on whether the alkyl chain on the P2TP molecules was of odd or even length. The monolayers were deposited on densely packed ultrasmooth self-assembled alkane silane modified SiO2 surfaces. Our work shows that a subtle change in molecular structure can have a significant impact on the molecular packing structure in thin film, which in turn, will have a strong impact on charge transport of organic semiconductors. This was verified by quantum-chemical calculations that predict a corresponding odd-even effect in the strength of the intermolecular electronic coupling. © 2013 American Chemical Society.

  7. Medium-chain-length poly-3-hydroxyalkanoates-carbon nanotubes composite anode enhances the performance of microbial fuel cell.

    Science.gov (United States)

    Hindatu, Y; Annuar, M S M; Subramaniam, R; Gumel, A M

    2017-06-01

    Insufficient power generation from a microbial fuel cell (MFC) hampers its progress towards utility-scale development. Electrode modification with biopolymeric materials could potentially address this issue. In this study, medium-chain-length poly-3-hydroxyalkanoates (PHA)/carbon nanotubes (C) composite (CPHA) was successfully applied to modify the surface of carbon cloth (CC) anode in MFC. Characterization of the functional groups on the anodic surface and its morphology was carried out. The CC-CPHA composite anode recorded maximum power density of 254 mW/m 2 , which was 15-53% higher than the MFC operated with CC-C (214 mW/m 2 ) and pristine CC (119 mW/m 2 ) as the anode in a double-chambered MFC operated with Escherichia coli as the biocatalyst. Electrochemical impedance spectroscopy and cyclic voltammetry showed that power enhancement was attributed to better electron transfer capability by the bacteria for the MFC setup with CC-CPHA anode.

  8. Distinguishing Heterodera filipjevi and H. avenae using polymerase chain reaction-restriction fragment length polymorphism and cyst morphology.

    Science.gov (United States)

    Yan, Guiping; Smiley, Richard W

    2010-03-01

    The cereal cyst nematodes Heterodera filipjevi and H. avenae impede wheat production in the Pacific Northwest (PNW). Accurate identification of cyst nematode species and awareness of high population density in affected fields are essential for designing effective control measures. Morphological methods for differentiating these species are laborious. These species were differentiated using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) of internal transcribed spacer (ITS)-ribosomal (r)DNA with up to six restriction endonucleases (TaqI, HinfI, PstI, HaeIII, RsaI, and AluI). The method was validated by inspecting underbridge structures of cyst vulval cones. Grid soil sampling of an Oregon field infested by both species revealed that H. filipjevi was present at most of the infested grid sites but mixtures of H. avenae and H. filipjevi also occurred. These procedures also detected and differentiated H. filipjevi and H. avenae in soil samples from nearby fields in Oregon and H. avenae in samples from Idaho and Washington. Intraspecific polymorphism was not observed within H. filipjevi or PNW H. avenae populations based on the ITS-rDNA. However, intraspecific variation was observed between H. avenae populations occurring in the PNW and France. Methods described here will improve detection and identification efficiencies for cereal cyst nematodes in wheat fields.

  9. The Impact of Polyether Chain Length on the Iron Clearing Efficiency and Physiochemical Properties of Desferrithiocin Analogues

    Science.gov (United States)

    Bergeron, Raymond J.; Bharti, Neelam; Wiegand, Jan; McManis, James S.; Singh, Shailendra; Abboud, Khalil A.

    2010-01-01

    (S)-2-(2,4-Dihydroxyphenyl)-4,5-dihydro-4-methyl-4-thiazolecarboxylic acid (2) was abandoned in clinical trials as an iron chelator for the treatment of iron overload disease because of its nephrotoxicity. However, subsequent investigations revealed that replacing the 4′-(HO) of 2 with a 3,6,9-trioxadecyloxy group, ligand 4, increased iron clearing efficiency (ICEa) and ameliorated the renal toxicity of 2. This compelled a closer look at additional polyether analogues, the subject of this work. The 3,6,9,12-tetraoxatridecyloxy analogue of 4, chelator 5, an oil, had twice the ICE in rodents of 4, although its ICE in primates was reduced relative to 4. The corresponding 3,6-dioxaheptyloxy analogue of 2, 6 (a crystalline solid), had high ICEs in both the rodent and primate models. It significantly decorporated hepatic, renal, and cardiac iron, with no obvious histopathologies. These findings suggest that polyether chain length has a profound effect on ICE, tissue iron decorporation, and ligand physiochemical properties. PMID:20232803

  10. Limits of a rapid identification of common Mediterranean sandflies using polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    Azzedine Bounamous

    2014-07-01

    Full Text Available A total of 131 phlebotomine Algerian sandflies have been processed in the present study. They belong to the species Phlebotomus bergeroti, Phlebotomus alexandri, Phlebotomus sergenti, Phlebotomus chabaudi, Phlebotomus riouxi, Phlebotomus perniciosus, Phlebotomus longicuspis, Phlebotomus perfiliewi, Phlebotomus ariasi, Phlebotomus chadlii, Sergentomyia fallax, Sergentomyia minuta, Sergentomyia antennata, Sergentomyia schwetzi, Sergentomyia clydei, Sergentomyia christophersi and Grassomyia dreyfussi. They have been characterised by sequencing of a part of the cytochrome b (cyt b, t RNA serine and NADH1 on the one hand and of the cytochrome C oxidase I of the mitochondrial DNA (mtDNA on the other hand. Our study highlights two sympatric populations within P. sergenti in the area of its type-locality and new haplotypes of P. perniciosus and P. longicuspis without recording the specimens called lcx previously found in North Africa. We tried to use a polymerase chain reaction-restriction fragment length polymorphism method based on a combined double digestion of each marker. These method is not interesting to identify sandflies all over the Mediterranean Basin.

  11. Effects of Odd–Even Side Chain Length of Alkyl-Substituted Diphenylbithiophenes on First Monolayer Thin Film Packing Structure

    KAUST Repository

    Akkerman, Hylke B.; Mannsfeld, Stefan C. B.; Kaushik, Ananth P.; Verploegen, Eric; Burnier, Luc; Zoombelt, Arjan P.; Saathoff, Jonathan D.; Hong, Sanghyun; Atahan-Evrenk, Sule; Liu, Xueliang; Aspuru-Guzik, Alá n; Toney, Michael F.; Clancy, Paulette; Bao, Zhenan

    2013-01-01

    Because of their preferential two-dimensional layer-by-layer growth in thin films, 5,5′bis(4-alkylphenyl)-2,2′-bithiophenes (P2TPs) are model compounds for studying the effects of systematic chemical structure variations on thin-film structure and morphology, which in turn, impact the charge transport in organic field-effect transistors. For the first time, we observed, by grazing incidence X-ray diffraction (GIXD), a strong change in molecular tilt angle in a monolayer of P2TP, depending on whether the alkyl chain on the P2TP molecules was of odd or even length. The monolayers were deposited on densely packed ultrasmooth self-assembled alkane silane modified SiO2 surfaces. Our work shows that a subtle change in molecular structure can have a significant impact on the molecular packing structure in thin film, which in turn, will have a strong impact on charge transport of organic semiconductors. This was verified by quantum-chemical calculations that predict a corresponding odd-even effect in the strength of the intermolecular electronic coupling. © 2013 American Chemical Society.

  12. Haplotyping the human T-cell receptor β-chain gene complex by use of restriction fragment length polymorphisms

    International Nuclear Information System (INIS)

    Charmley, P.; Chao, A.; Gatti, R.A.; Concannon, P.; Hood, L.

    1990-01-01

    The authors have studied the genetic segregation of human T-cell receptor β-chain (TCRβ) genes on chromosome 7q in 40 CEPH (Centre d'Etude du Polymorphisme Humain) families by using restriction fragment length polymorphisms (RFLPs). They constructed haplotypes from eight RFLPs by using variable- and constant-region cDNA probes, which detect polymorphisms that span more than 600 kilobases of the TCRβ gene complex. Analysis of allele distributions between TCRβ genes revealed significant linkage disequilibrium between only 6 of the 28 different pairs of RFLPs. This linkage disequilibrium strongly influences the most efficient order to proceed for typing of these RFLPs in order to achieve maximum genetic informativeness, which in this study revealed a 97.3% level of heterozygosity within the TCRβ gene complex. The results should provide new insight into recent reports of disease associations with the TCRβ gene complex and should assist in designing future experiments to detect or confirm the existence of disease-susceptibility loci in this region of the human genome

  13. Rapid differentiation of closely related isolates of two plant viruses by polymerase chain reaction and restriction fragment length polymorphism analysis.

    Science.gov (United States)

    Barbara, D J; Morton, A; Spence, N J; Miller, A

    1995-09-01

    Immunocapture reverse transcriptase-polymerase chain reaction (RT-PCR) followed by restriction fragment length polymorphism (RFLP) analysis of the product has been shown to be an effective procedure for discriminating serologically indistinguishable isolates of two plant viruses, raspberry bushy dwarf (RBDV) and zucchini yellow mosaic (ZYMV). For both viruses, only limited sequence information was available at the time of primer design, but most of the isolates which were tested could be amplified (the one exception being a serologically quite distinct isolate of ZYMV). Restriction endonucleases revealing diagnostic RFLPs were readily identified. Each of two isolates of ZYMV could be detected in the presence of the other and the relative proportions approximately quantified by visual estimation of the relative intensity of the appropriate bands. A range of isolates of different RBDV pathotypes were compared; isolates were grouped in ways that accorded with their known history. Computer analysis of the published sequence from which the primers had been derived showed the sequenced isolate to be identical with an isolate imported from the USSR. The PCR/RFLP procedure is rapid (it can be completed in less than 2 days), effective and will probably be generally applicable to distinguishing closely related virus isolates, even where little sequence information is available.

  14. Lyme disease with facial nerve palsy: rapid diagnosis using a nested polymerase chain reaction-restriction fragment length polymorphism analysis.

    Science.gov (United States)

    Hashimoto, Y; Takahashi, H; Kishiyama, K; Sato, Y; Nakao, M; Miyamoto, K; Iizuka, H

    1998-02-01

    A 64-year-old woman with Lyme disease and manifesting facial nerve palsy had been bitten by a tick on the left frontal scalp 4 weeks previously. Erythema migrans appeared on the left forehead, accompanied by left facial paralysis. Nested polymerase chain reaction-restriction fragment length polymorphism analysis (nested PCR-RFLP) was performed on DNA extracted from a skin biopsy of the erythema on the left forehead. Borrelia flagellin gene DNA was detected and its RFLP pattern indicated that the organism was B. garinii, Five weeks later, B. garinii was isolated by conventional culture from the erythematous skin lesion, but not from the cerebrospinal fluid. After treatment with ceftriaxone intravenously for 10 days and oral administration of minocycline for 7 days, both the erythema and facial nerve palsy improved significantly. Nested PCR and culture taken after the lesion subsided, using skin samples obtained from a site adjacent to the original biopsy, were both negative. We suggest that nested PCR-RFLP analysis might be useful for the rapid diagnosis of Lyme disease and for evaluating therapy.

  15. An Assessment of Weight-Length Relationships for Muskellunge,Northern Pike, and Chain Pickerel In Carlander's Handbook of Freshwater Fishery Biology

    OpenAIRE

    Daviscourt, Joshua; Huertas, Joshua; Courtney, Michael

    2011-01-01

    Carlander's Handbook of Freshwater Fishery Biology (1969) contains life history data from many species of freshwater fish found in North America. It has been cited over 1200 times and used to produce standard-weight curves for some species. Recent work (Cole-Fletcher et al. 2011) suggests Carlander (1969) contains numerous errors in listed weight-length equations. This paper assesses the weight-length relationships listed in Carlander for muskellunge, northern pike, and chain pickerel by comp...

  16. Effect of alkyl chain length and temperature on the thermodynamic properties of ionic liquids 1-alkyl-3-methylimidazolium bromide in aqueous and non-aqueous solutions at different temperatures

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat; Shekaari, Hemayat; Hosseini, Rahim

    2009-01-01

    The alkyl chain length of 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = propyl (C 3 ), hexyl (C 6 ), heptyl (C 7 ), and octyl (C 8 )) was varied to prepare a series of room-temperature ionic liquids (RTILs), and experimental measurements of density and speed of sound at different temperatures ranging from (288.15 to 308.15) K for their aqueous and methanolic solutions in the dilute concentration region (0.01 to 0.30) mol . kg -1 were taken. The values of the compressibilities, expansivity and apparent molar properties for [C n mim][Br] in aqueous and methanolic solutions were determined at the investigated temperatures. The obtained apparent molar volumes and apparent molar isentropic compressibilities were fitted to the Redlich-Mayer and the Pitzer's equations from which the corresponding infinite dilution molar properties were obtained. The values of the infinite dilution molar properties were used to obtain some information about solute-solvent and solute-solute interactions. The thermodynamic properties of investigated ionic liquids in aqueous solutions have been compared with those in methanolic solutions. Also, the comparison between thermodynamic properties of investigated solutions and those of electrolyte solutions, polymer solutions, cationic surfactant solutions and tetraalkylammonium salt solutions have been made

  17. Effect of alkyl chain length and temperature on the thermodynamic properties of ionic liquids 1-alkyl-3-methylimidazolium bromide in aqueous and non-aqueous solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)], E-mail: rahsadeghi@yahoo.com; Shekaari, Hemayat [Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Hosseini, Rahim [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2009-02-15

    The alkyl chain length of 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = propyl (C{sub 3}), hexyl (C{sub 6}), heptyl (C{sub 7}), and octyl (C{sub 8})) was varied to prepare a series of room-temperature ionic liquids (RTILs), and experimental measurements of density and speed of sound at different temperatures ranging from (288.15 to 308.15) K for their aqueous and methanolic solutions in the dilute concentration region (0.01 to 0.30) mol . kg{sup -1} were taken. The values of the compressibilities, expansivity and apparent molar properties for [C{sub n}mim][Br] in aqueous and methanolic solutions were determined at the investigated temperatures. The obtained apparent molar volumes and apparent molar isentropic compressibilities were fitted to the Redlich-Mayer and the Pitzer's equations from which the corresponding infinite dilution molar properties were obtained. The values of the infinite dilution molar properties were used to obtain some information about solute-solvent and solute-solute interactions. The thermodynamic properties of investigated ionic liquids in aqueous solutions have been compared with those in methanolic solutions. Also, the comparison between thermodynamic properties of investigated solutions and those of electrolyte solutions, polymer solutions, cationic surfactant solutions and tetraalkylammonium salt solutions have been made.

  18. Inhibition of nuclear T3 binding by fatty acids: dependence on chain length, unsaturated bonds, cis-trans configuration and esterification

    NARCIS (Netherlands)

    Wiersinga, W. M.; Platvoet-ter Schiphorst, M.

    1990-01-01

    1. Fatty acids have the capacity for inhibition of nuclear T3 binding (INB). The present studies were undertaken to describe the INB-activity of fatty acids as a function of chain length, unsaturated bonds, cis-trans configuration, and esterification. 2. Isolated rat liver nuclei were incubated with

  19. Characterisation of Toxoplasma gondii isolates using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) of the non-coding Toxoplasma gondii (TGR)-gene sequences

    DEFF Research Database (Denmark)

    Høgdall, Estrid; Vuust, Jens; Lind, Peter

    2000-01-01

    of using TGR gene variants as markers to distinguish among T. gondii isolates from different animals and different geographical sources. Based on the band patterns obtained by restriction fragment length polymorphism (RFLP) analysis of the polymerase chain reaction (PCR) amplified TGR sequences, the T...

  20. Lid opening and conformational stability of T1 Lipase is mediated by increasing chain length polar solvents

    Directory of Open Access Journals (Sweden)

    Jonathan Maiangwa

    2017-05-01

    Full Text Available The dynamics and conformational landscape of proteins in organic solvents are events of potential interest in nonaqueous process catalysis. Conformational changes, folding transitions, and stability often correspond to structural rearrangements that alter contacts between solvent molecules and amino acid residues. However, in nonaqueous enzymology, organic solvents limit stability and further application of proteins. In the present study, molecular dynamics (MD of a thermostable Geobacillus zalihae T1 lipase was performed in different chain length polar organic solvents (methanol, ethanol, propanol, butanol, and pentanol and water mixture systems to a concentration of 50%. On the basis of the MD results, the structural deviations of the backbone atoms elucidated the dynamic effects of water/organic solvent mixtures on the equilibrium state of the protein simulations in decreasing solvent polarity. The results show that the solvent mixture gives rise to deviations in enzyme structure from the native one simulated in water. The drop in the flexibility in H2O, MtOH, EtOH and PrOH simulation mixtures shows that greater motions of residues were influenced in BtOH and PtOH simulation mixtures. Comparing the root mean square fluctuations value with the accessible solvent area (SASA for every residue showed an almost correspondingly high SASA value of residues to high flexibility and low SASA value to low flexibility. The study further revealed that the organic solvents influenced the formation of more hydrogen bonds in MtOH, EtOH and PrOH and thus, it is assumed that increased intraprotein hydrogen bonding is ultimately correlated to the stability of the protein. However, the solvent accessibility analysis showed that in all solvent systems, hydrophobic residues were exposed and polar residues tended to be buried away from the solvent. Distance variation of the tetrahedral intermediate packing of the active pocket was not conserved in organic solvent

  1. 4-N-, 4-S-, and 4-O-chloroquine analogues: influence of side chain length and quinolyl nitrogen pKa on activity vs chloroquine resistant malaria.

    Science.gov (United States)

    Natarajan, Jayakumar K; Alumasa, John N; Yearick, Kimberly; Ekoue-Kovi, Kekeli A; Casabianca, Leah B; de Dios, Angel C; Wolf, Christian; Roepe, Paul D

    2008-06-26

    Using predictions from heme-quinoline antimalarial complex structures, previous modifications of chloroquine (CQ), and hypotheses for chloroquine resistance (CQR), we synthesize and assay CQ analogues that test structure-function principles. We vary side chain length for both monoethyl and diethyl 4-N CQ derivatives. We alter the pKa of the quinolyl N by introducing alkylthio or alkoxy substituents into the 4 position and vary side chain length for these analogues. We introduce an additional titratable amino group to the side chain of 4-O analogues with promising CQR strain selectivity and increase activity while retaining selectivity. We solve atomic resolution structures for complexes formed between representative 4-N, 4-S, and 4-O derivatives vs mu-oxo dimeric heme, measure binding constants for monomeric vs dimeric heme, and quantify hemozoin (Hz) formation inhibition in vitro. The data provide additional insight for the design of CQ analogues with improved activity vs CQR malaria.

  2. 4-N, 4-S & 4-O Chloroquine Analogues: Influence of Side Chain Length and Quinolyl Nitrogen pKa on Activity vs. Chloroquine Resistant Malaria+, #

    Science.gov (United States)

    Natarajan, Jayakumar K.; Alumasa, John; Yearick, Kimberly; Ekoue-Kovi, Kekeli A.; Casabianca, Leah B.; de Dios, Angel C.; Wolf, Christian; Roepe, Paul D.

    2009-01-01

    Using predictions from heme – quinoline antimalarial complex structures, previous modifications of chloroquine (CQ), and hypotheses for chloroquine resistance (CQR), we synthesize and assay CQ analogues that test structure – function principles. We vary side chain length for both monoethyl and diethyl 4N CQ derivatives. We alter the pKa of the quinolyl N by introducing alkylthio or alkoxy substituents into the 4 position, and vary side chain length for these analogues. We introduce an additional titratable amino group to the side chain of 4O analogues with promising CQR strain selectivity and increase activity while retaining selectivity. We solve atomic resolution structures for complexes formed between representative 4N, 4S and 4O derivatives vs. μ-oxo dimeric heme, measure binding constants for monomeric vs. dimeric heme, and quantify hemozoin (Hz) formation inhibition in vitro. The data provide additional insight for the design of CQ analogues with improved activity vs. CQR malaria. PMID:18512900

  3. Comparison of CHROMagar, polymerase chain reaction-restriction fragment length polymorphism, and polymerase chain reaction-fragment size for the identification of Candida species.

    Science.gov (United States)

    Jafari, Zahra; Motamedi, Marjan; Jalalizand, Nilufar; Shokoohi, Gholam R; Charsizadeh, Arezu; Mirhendi, Hossein

    2017-09-01

    The epidemiological alteration in the distribution of Candida species, as well as the significantly increasing trend of either intrinsic or acquired resistance of some of these fungi highlights the need for a reliable method for the identification of the species. Polymerase chain reaction (PCR) is one of the methods facilitating the quick and precise identification of Candida species. The aim of this study was to compare the efficiency of CHROMagar, PCR-restriction fragment length polymorphism (PCR-RFLP), and PCR-fragment size polymorphism (PCR-FSP) assays in the identification of Candida species to determine the benefits and limitations of these methods. This study was conducted on 107 Candida strains, including 20 standard strains and 87 clinical isolates. The identification of the isolates was accomplished by using CHROMagar as a conventional method. The PCR-RFLP assay was performed on the entire internal transcribed spacer (ITS) region of ribosomal DNA (rDNA), and the consequent enzymatic digestion was compared with PCR-FSP results in which ITS1 and ITS2 regions were separately PCR amplified. In both molecular assays, yeast identification was carried out through the specific electrophoretic profiles of the PCR products. According to the results, the utilization of CHROMagar resulted in the identification of 29 (33.3%) Candida isolates, while the PCR-RFLP and PCR-FSP facilitated the identification of 83 (95.4%) and 80 (91.9%) clinical isolates, respectively. The obtained concordances between CHROMagar and PCR-RFLP, between CHROMagar and PCR-FSP, as well as between PCR-RFLP and PCR-FSP were 0.23, 0.20, and 0.77, respectively. The recognition of the benefits and limitations of PCR methods allows for the selection of the most efficient technique for a fast and correct differentiation. The PCR-RFLP and PCR-FSP assays had satisfactory concordance. The PCR-FSP provides a rapid, technically simple, and cost-effective method for the identification of Candida species

  4. Modulation of saturation and chain length of fatty acids in Saccharomyces cerevisiae for production of cocoa butter-like lipids.

    Science.gov (United States)

    Bergenholm, David; Gossing, Michael; Wei, Yongjun; Siewers, Verena; Nielsen, Jens

    2018-04-01

    Chain length and degree of saturation plays an important role for the characteristics of various products derived from fatty acids, such as fuels, cosmetics, and food additives. The seeds of Theobroma cacao are the source of cocoa butter, a natural lipid of high interest for the food and cosmetics industry. Cocoa butter is rich in saturated fatty acids that are stored in the form of triacylglycerides (TAGs). One of the major TAG species of cocoa butter, consisting of two stearic acid molecules and one oleic acid molecule (stearic acid-oleic acid-stearic acid, sn-SOS), is particularly rare in nature as the saturated fatty acid stearic acid is typically found only in low abundance. Demand for cocoa butter is increasing, yet T. cacao can only be cultivated in some parts of the tropics. Alternative means of production of cocoa butter lipids (CBLs) are, therefore, sought after. Yeasts also store fatty acids in the form of TAGs, but these are typically not rich in saturated fatty acids. To make yeast an attractive host for microbial production of CBLs, its fatty acid composition needs to be optimized. We engineered Saccharomyces cerevisiae yeast strains toward a modified fatty acid synthesis. Analysis of the fatty acid profile of the modified strains showed that the fatty acid content as well as the titers of saturated fatty acids and the titers of TAGs were increased. The relative content of potential CBLs in the TAG pool reached up to 22% in our engineered strains, which is a 5.8-fold increase over the wild-type. SOS content reached a level of 9.8% in our engineered strains, which is a 48-fold increase over the wild type. © 2018 Wiley Periodicals, Inc.

  5. The conversion of BTEX compounds by single and defined mixed cultures to medium-chain-length polyhydroxyalkanoate.

    Science.gov (United States)

    Nikodinovic, Jasmina; Kenny, Shane T; Babu, Ramesh P; Woods, Trevor; Blau, Werner J; O'Connor, Kevin E

    2008-09-01

    Here, we report the use of petrochemical aromatic hydrocarbons as a feedstock for the biotechnological conversion into valuable biodegradable plastic polymers--polyhydroxyalkanoates (PHAs). We assessed the ability of the known Pseudomonas putida species that are able to utilize benzene, toluene, ethylbenzene, p-xylene (BTEX) compounds as a sole carbon and energy source for their ability to produce PHA from the single substrates. P. putida F1 is able to accumulate medium-chain-length (mcl) PHA when supplied with toluene, benzene, or ethylbenzene. P. putida mt-2 accumulates mcl-PHA when supplied with toluene or p-xylene. The highest level of PHA accumulated by cultures in shake flask was 26% cell dry weight for P. putida mt-2 supplied with p-xylene. A synthetic mixture of benzene, toluene, ethylbenzene, p-xylene, and styrene (BTEXS) which mimics the aromatic fraction of mixed plastic pyrolysis oil was supplied to a defined mixed culture of P. putida F1, mt-2, and CA-3 in the shake flasks and fermentation experiments. PHA was accumulated to 24% and to 36% of the cell dry weight of the shake flask and fermentation grown cultures respectively. In addition a three-fold higher cell density was achieved with the mixed culture grown in the bioreactor compared to shake flask experiments. A run in the 5-l fermentor resulted in the utilization of 59.6 g (67.5 ml) of the BTEXS mixture and the production of 6 g of mcl-PHA. The monomer composition of PHA accumulated by the mixed culture was the same as that accumulated by single strains supplied with single substrates with 3-hydroxydecanoic acid occurring as the predominant monomer. The purified polymer was partially crystalline with an average molecular weight of 86.9 kDa. It has a thermal degradation temperature of 350 degrees C and a glass transition temperature of -48.5 degrees C.

  6. Manipulating the morphology and textural property of γ-AlOOH by modulating the alkyl chain length of cation in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhe, E-mail: tangzhe1983@163.com; Hu, Xiaofu, E-mail: hjj19850922@126.cn; Liang, Jilei, E-mail: liang.jilei_ttplan@126.com; Zhao, Jinchong, E-mail: Dr.zhaojc@gmail.com; Liu, Yunqi, E-mail: liuyq@upc.edu.cn; Liu, Chenguang, E-mail: cgliu@upc.edu.cn

    2013-06-01

    Graphical abstract: - Highlights: • γ-AlOOH was the only product in all experiments. • Different morphology of γ-AlOOH was obtained according to the alkyl chain length. • The textural property of γ-AlOOH was changed according to the alkyl chain length. • The possible formation mechanisms for hollow sphere and microflower were proposed. - Abstract: We demonstrated that the morphology and textural property of γ-AlOOH can be tuned by modulating the alkyl chain length of cation in [C{sub n}mim]{sup +}Cl{sup −} (n = 4, 8, 16). Using the short alkyl chain length-based [C{sub 4}mim]{sup +}Cl{sup −} as the structure-directed reagent, the morphology of γ-AlOOH was not changed and preserved as the hollow sphere structure in all experiments. The specific area and the number of small meso-pores of γ-AlOOH increased with the increase of [C{sub 4}mim]{sup +}Cl{sup −} dosage. While, using the larger alkyl chain length-based ionic liquids as the soft-template, such as [C{sub 8}mim]{sup +}Cl{sup −} and [C{sub 16}mim]{sup +}Cl{sup −}, the morphologies of γ-AlOOH were changed from initiative hollow spheres into the final microflowers. The specific areas of γ-AlOOH firstly increased then decreased with the increase of their dosage. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). Furthermore, the possible formation mechanisms of γ-AlOOH have been proposed.

  7. Overexpression of O-polysaccharide chain length regulators in Gram-negative bacteria using the Wzx-/Wzy-dependent pathway enhances production of defined modal length O-polysaccharide polymers for use as haptens in glycoconjugate vaccines.

    Science.gov (United States)

    Hegerle, N; Bose, J; Ramachandran, G; Galen, J E; Levine, M M; Simon, R; Tennant, S M

    2018-03-30

    O-polysaccharide (OPS) molecules are protective antigens for several bacterial pathogens, and have broad utility as components of glycoconjugate vaccines. Variability in the OPS chain length is one obstacle towards further development of these vaccines. Introduction of sizing steps during purification of OPS molecules of suboptimal or of mixed lengths introduces additional costs and complexity while decreasing the final yield. The overall goal of this study was to demonstrate the utility of engineering Gram-negative bacteria to produce homogenous O-polysaccharide populations that can be used as the basis of carbohydrate vaccines by overexpressing O-polysaccharide chain length regulators of the Wzx-/Wzy-dependent pathway. The O-polysaccharide chain length regulators wzzB and fepE from Salmonella Typhimurium I77 and wzz2 from Pseudomonas aeruginosa PAO1 were cloned and expressed in the homologous organism or in other Gram-negative bacteria. Overexpression of these Wzz proteins in the homologous organism significantly increased the proportion of long or very long chain O-polysaccharides. The same observation was made when wzzB was overexpressed in Salmonella Paratyphi A and Shigella flexneri, and wzz2 was overexpressed in two other strains of P. aeruginosa. Overexpression of Wzz proteins in Gram-negative bacteria using the Wzx/Wzy-dependant pathway for lipopolysaccharide synthesis provides a genetic method to increase the production of an O-polysaccharide population of a defined size. The methods presented herein represent a cost-effective and improved strategy for isolating preferred OPS vaccine haptens, and could facilitate the further use of O-polysaccharides in glycoconjugate vaccine development. © 2018 The Society for Applied Microbiology.

  8. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    Science.gov (United States)

    Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng

    2017-02-01

    It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C6, C12, or C18) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (Ra) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al2O3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C12 alkyl chain (C12-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C12-SAM with desirable alkyl chain length.

  9. Effects of alkyl chain length and substituent pattern of fullerene bis-adducts on film structures and photovoltaic properties of bulk heterojunction solar cells.

    Science.gov (United States)

    Tao, Ran; Umeyama, Tomokazu; Kurotobi, Kei; Imahori, Hiroshi

    2014-10-08

    A series of alkoxycarbonyl-substituted dihydronaphthyl-based [60]fullerene bis-adduct derivatives (denoted as C2BA, C4BA, and C6BA with the alkyl chain of ethyl, n-butyl, and n-hexyl, respectively) have been synthesized to investigate the effects of alkyl chain length and substituent pattern of fullerene bis-adducts on the film structures and photovoltaic properties of bulk heterojunction polymer solar cells. The shorter alkyl chain length caused lower solubility of the fullerene bis-adducts (C6BA > C4BA > C2BA), thereby resulting in the increased separation difficulty of respective bis-adduct isomers. The device performance based on poly(3-hexylthiophene) (P3HT) and the fullerene bis-adduct regioisomer mixtures was enhanced by shortening the alkyl chain length. When using the regioisomerically separated fullerene bis-adducts, the devices based on trans-2 and a mixture of trans-4 and e of C4BA exhibited the highest power conversion efficiencies of ca. 2.4%, which are considerably higher than those of the C6BA counterparts (ca. 1.4%) and the C4BA regioisomer mixture (1.10%). The film morphologies as well as electron mobilities of the P3HT:bis-adduct blend films were found to affect the photovoltaic properties considerably. These results reveal that the alkyl chain length and substituent pattern of fullerene bis-adducts significantly influence the photovoltaic properties as well as the film structures of bulk heterojunction solar cells.

  10. Probing the Differential Tissue Distribution and Bioaccumulation Behavior of Per- and Polyfluoroalkyl Substances of Varying Chain-Lengths, Isomeric Structures and Functional Groups in Crucian Carp.

    Science.gov (United States)

    Shi, Yali; Vestergren, Robin; Nost, Therese Haugdahl; Zhou, Zhen; Cai, Yaqi

    2018-04-17

    Understanding the bioaccumulation mechanisms of per- and polyfluoroalkyl substances (PFASs) across different chain-lengths, isomers and functional groups represents a monumental scientific challenge with implications for chemical regulation. Here, we investigate how the differential tissue distribution and bioaccumulation behavior of 25 PFASs in crucian carp from two field sites impacted by point sources can provide information about the processes governing uptake, distribution and elimination of PFASs. Median tissue/blood ratios (TBRs) were consistently 90% of the amount of PFASs in the organism. Principal component analyses of TBRs and RBBs showed that the functional group was a relatively more important predictor of internal distribution than chain-length for PFASs. Whole body bioaccumulation factors (BAFs) for short-chain PFASs deviated from the positive relationship with hydrophobicity observed for longer-chain homologues. Overall, our results suggest that TBR, RBB, and BAF patterns were most consistent with protein binding mechanisms although partitioning to phospholipids may contribute to the accumulation of long-chain PFASs in specific tissues.

  11. Effect of stereochemistry, chain length and sequence pattern on antimicrobial properties of short synthetic β-sheet forming peptide amphiphiles.

    Science.gov (United States)

    Ong, Zhan Yuin; Cheng, Junchi; Huang, Yuan; Xu, Kaijin; Ji, Zhongkang; Fan, Weimin; Yang, Yi Yan

    2014-01-01

    In the face of mounting global antibiotics resistance, the identification and development of membrane-active antimicrobial peptides (AMPs) as an alternative class of antimicrobial agent have gained significant attention. The physical perturbation and disruption of microbial membranes by the AMPs have been proposed to be an effective means to overcome conventional mechanisms of drug resistance. Recently, we have reported the design of a series of short synthetic β-sheet folding peptide amphiphiles comprised of recurring (X1Y1X2Y2)n-NH2 sequences where X: hydrophobic amino acids, Y: cationic amino acids and n: number of repeat units. In efforts to investigate the effects of key parameters including stereochemistry, chain length and sequence pattern on antimicrobial effects, systematic d-amino acid substitutions of the lead peptides (IRIK)2-NH2 (IK8-all L) and (IRVK)3-NH2 (IK12-all L) were performed. It was found that the corresponding D-enantiomers exhibited stronger antimicrobial activities with minimal or no change in hemolytic activities, hence translating very high selectivity indices of 407.0 and >9.8 for IK8-all D and IK12-all D respectively. IK8-all D was also demonstrated to be stable to degradation by broad spectrum proteases trypsin and proteinase K. The membrane disrupting bactericidal properties of IK8-all D effectively prevented drug resistance development and inhibited the growth of various clinically isolated MRSA, VRE, Acinetobacter baumanni, Pseudomonas aeruginosa, Cryptococcus. neoformans and Mycobacterium tuberculosis. Significant reduction in intracellular bacteria counts was also observed following treatment with IK8-all D in the Staphylococcus. aureus infected mouse macrophage cell line RAW264.7 (P < 0.01). These results suggest that the d-amino acids substituted β-sheet forming peptide IK8-all D with its enhanced antimicrobial activities and improved protease stability, is a promising therapeutic candidate with potential to combat

  12. Methotrexate intercalated layered double hydroxides with the mediation of surfactants: Mechanism exploration and bioassay study

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Chao-Fan; Tian, De-Ying; Li, Shu-Ping, E-mail: lishuping@njnu.edu.cn; Li, Xiao-Dong

    2015-12-01

    Methotrexatum intercalated layered double hydroxides (MTX/LDHs) hybrids were synthesized by the co-precipitation method and three kinds of nonionic surfactants with different hydrocarbon chain lengths were used. The resulting hybrids were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD and FTIR investigations manifest the successful intercalation of MTX anions into the interlayer of LDHs. TEM graphs indicate that the morphology of the hybrids changes with the variation of the chain length of the surfactants, i.e., the particles synthesized using polyethylene glycol (PEG-7) present regular disc morphology with good monodispersity, while samples with the mediation of alkyl polyglycoside (APG-14) are heavily aggregated and samples with the addition of polyvinylpyrrolidone (PVP-10) exhibit irregular branches. Furthermore, the release and bioassay experiments show that monodisperse MTX/LDHs present good controlled-release and are more efficient in the suppression of the tumor cells. - Highlights: • Surfactants could be used to modify the dispersing state of MTX/LDHs hybrids. • Surfactants have great effect on the morphology of MTX/LDHs hybrids. • MTX/LDHs with good monodisperse degree are more efficient in the suppression of the tumor cells.

  13. Solubilization and mineralization of polycyclic aromatic hydrocarbons by Pseudomonas putida in the presence of surfactant

    International Nuclear Information System (INIS)

    Doong Rueyan; Lei Wengang

    2003-01-01

    The solubilization and mineralization of polycyclic aromatic hydrocarbons (PAHs) in a soil system amended with different surfactants was examined. Mineralization experiments were conducted with the addition of [ 14 C]pyrene. An inoculum of the PAH-degrading microorganism, Pseudomonas putida, was investigated for its sensitivity towards four non-ionic and one anionic surfactants with different polyoxyethylene (POE) chain lengths. The addition of surfactant was found to enhance the bioavailability of naphthalene, phenanthrene and pyrene with efficiencies ranging from 21.1 to 60.6%, 33.3 to 62.8% and 26.8 to 70.9%, respectively. The enhanced efficiency followed the order of Brij 30, Triton X-100, Tween 80, and Brij 35, which is correlated with the polyoxyethylene chain of the surfactants. Brij 35 and Tween 80 inhibited the growth of P. putida. However, microorganisms can utilize Triton X-100 and Brij 30 as the sole carbon and energy sources at concentrations above CMC values. In the aqueous system without the addition of surfactants, microorganisms could mineralize [ 14 C]pyrene to 14 CO 2 which corresponds to 28% of mineralization. The addition of surfactants decreased the mineralization rate of pyrene. Also, the fraction of the micellar-phase pyrene that can be directly biodegraded decreased as the concentration of micelle increases. However, the mineralization rate can be enhanced by the amendment of Brij 30 when soil was applied to the cultures. This suggests that biodegradable surfactants can be applicable for increasing the bioavailability and mineralization of PAHs in soil systems

  14. The structure of normal ionic micelles by interpretation of small-angle neutron scattering data from selectively labeled (2H, 19F) surfactant solutions

    International Nuclear Information System (INIS)

    Berr, S.S.

    1986-12-01

    We have determined the structure of micelles formed in water by several classes of ionic surfactants under a variety of experimental conditions using small-angle neutron scattering (SANS) techniques. Contrast between the micelles and the solvent was achieved through either selective deuteration or fluorination of the surfactant, or through the use of D 2 O. Interpretation of SANS data was facilitated by the use of Hayter, Penfold, and Hansen's rescaled Mean Spherical Approximation theory to calculate the scattering due to interparticle interactions. We have devised a number of micelle models, both spherical and ellipsoidal, to account for the scattering due to single micelles. It was found that changing the solvent from H 2 O to D 2 O results in the formation of larger micelles due to changes in the solvent-surfactant hydrocarbon interactions. This solvent isotope effect increased as the length of the alkyl chain increased. The fractional micellar charge did not change with respect to isotopic composition of solvent. We found that alkyltrimethylammonium bromide surfactants form drier micelles than do the sodium alkyl sulfate surfactants of equal chain length. Also, all micelles studied were found to be dry near the critical micelle concentration (cmc) and to become increasingly wetter as the concentration increased. The increase in aggregation number with respect to the square root of surfactant concentration was found to be linear for all systems studied. 80 figs

  15. Effects of a homologous series of linear alcohol ethoxylate surfactants on fathead minnow early life stages.

    Science.gov (United States)

    Lizotte, R E; Wong, D C; Dorn, P B; Rodgers, J H

    1999-11-01

    Effects of a homologous series of three primarily linear alcohol ethoxylate surfactants were studied in laboratory flow-through 28-day early-life-stage tests with fathead minnow (Pimephales promelas Rafinesque). Surfactants were a C(9-11), C(12-13), and C(14-15) with an average of 6, 6.5, and 7 ethylene oxide units per mole of alcohol, respectively. Average measured surfactant recoveries were 103%, 81%, and 79% of nominal concentrations for the C(9-11) EO 6, C(12-13) EO 6.5, and C(14-15) EO 7 studies, respectively. Embryo survival at 48 h was not adversely affected at any of the concentrations tested. Impaired hatching and deformed fry were observed only in the C(12-13) EO 6.5 study. The 28-day LC50 values were 4.87, 2.39, and 1.02 mg/L for the C(9-11) EO 6, C(12-13) EO 6.5, and C(14-15) EO 7 surfactants, respectively. The corresponding NOECs for survival were 1.01, 1.76, and 0.74 mg/L. Posthatch fry growth was more sensitive than survival for the C(12-13) EO 6.5 and C(14-15) EO 7 surfactants. Survival of posthatch fry decreased with increasing surfactant alkyl chain length. Twenty-eight-day laboratory data were compared to 96-h laboratory, 10-day laboratory and 30-day stream mesocosm data for fathead minnow previously determined for these surfactants. Survival endpoints from the different exposures were comparable and only varied within a factor of two. Similarity of results suggests that it is possible to effectively use 96-h, 10-day, or 28-day laboratory data to predict environmental effects concentrations of these surfactants for fish. http://link.springer-ny. com/link/service/journals/00244/bibs/37n4p536.html

  16. Effects of molecular and lattice structure on the thermal behaviours of some long chain length potassium(I) n-alkanoates

    Science.gov (United States)

    Nelson, Peter N.; Ellis, Henry A.; Taylor, Richard A.

    2014-01-01

    Lattice structures and thermal behaviours for some long chain potassium carboxylates (nc = 8-18, inclusive) are investigated using Fourier Transform Infrared spectroscopy, X-ray Powder Diffraction, Solid State spin decoupled 13C NMR spectroscopy, Differential Scanning Calorimetry and Thermogravimetry. The measurements show that the carboxyl groups are coordinated to potassium atoms via asymmetric chelating bidentate bonding, with extensive carboxyl intermolecular interactions to yield tetrahedral metal centers, irrespective of chain length. Furthermore, the hydrocarbon chains are crystallized in the fully extended all-trans configuration and are arranged as non-overlapping lamellar bilayer structures with closely packed methyl groups from opposite layers. Additionally, odd-even alternation, observed in density and methyl group chemical shift, is ascribed to the relative vertical distances between layers in the bilayer, that are not in the same plane. Therefore, for even chain homologues, where this distances is less than for odd chain adducts, more intimate packing is indicated. The phase sequences for all compounds show several reversible crystal-crystal transition associated with kinetically controlled gauche-trans isomerism of the polymethylene chains which undergo incomplete fusion when heated to the melt. The compounds degrade above 785 K to yield carbon dioxide, water, potassium oxide and an alkene.

  17. The critical main-chain length for helix formation in water: determined in a peptide series with alternating Aib and Ala residues exclusively and detected with ECD spectroscopy.

    Science.gov (United States)

    Longo, Edoardo; Moretto, Alessandro; Formaggio, Fernando; Toniolo, Claudio

    2011-10-01

    Critical main-chain length for peptide helix formation in the crystal (solid) state and in organic solvents has been already reported. In this short communication, we describe our results aiming at assessing the aforementioned parameter in water solution. To this goal, we synthesized step-by-step by solution procedures a complete series of N-terminally acetylated, C-terminally methoxylated oligopeptides, characterized only by alternating Aib and Ala residues, from the dimer to the nonamer level. All these compounds were investigated by electronic circular dichroism in the far-UV region in water solution as a function of chemical structure, namely presence/absence of an ester moiety or a negative charge at the C-terminus, and temperature. We find that the critical main-chain lengths for 3(10)- and α-helices, although still formed to a limited extent, in aqueous solution are six and eight residues, respectively. © 2011 Wiley-Liss, Inc.

  18. Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 4 - Synthesis of side-chain liquid crystalline polycarbonates with mesogenic groups having tails of different lengths

    NARCIS (Netherlands)

    Jansen, J.C.; Addink, R.; Nijenhuis, K.T.; Mijs, W.J.

    1999-01-01

    Side-chain liquid crystalline polycarbonates with alkoxyphenylbenzoate side groups, having a short spacer and tails ranging from 1 to 8 C-atoms, were synthesized. The polymers were prepared by an organo-zinc catalysed copolymerization of carbon dioxide and mesogenic 4-alkoxyphenyl

  19. Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5 - Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

    NARCIS (Netherlands)

    Jansen, J.C.; Addink, R.; Nijenhuis, K.T.; Mijs, W.J.

    1999-01-01

    The mesomorphic properties and thermal stability of side-chain LC polycarbonates with alkoxyphenyl benzoate side groups having a short spacer and alkoxy tails ranging from 1 to 8 carbon atoms were studied by DSC, X-ray diffraction and polarized light optical microscopy. All polymers have a smectic A

  20. Studies on the solvation dynamics of coumarin 153 in 1-ethyl-3-methylimidazolium alkylsulfate ionic liquids: dependence on alkyl chain length.

    Science.gov (United States)

    Das, Sudhir Kumar; Sarkar, Moloy

    2012-08-06

    Steady-state and time-resolved fluorescence behavior of coumarin 153 (C153) is investigated in a series of 1-ethyl-3-methylimidazolium alkylsulfate ([C(2)mim][C(n)OSO(3)]) ionic liquids differing only in the length of the linear alkyl chain (n = 4, 6, and 8) in the anion. The aim of the present study is to understand the role of alkyl chain length in solute rotation and solvation dynamics of C153 in these ionic liquids. The blueshift observed in the steady-state absorption and emission maxima of C153 on going from the C(4)OSO(3) to the C(8)OSO(3) system indicates increasing nonpolar character of the microenvironment of the solute with increasing length of the alkyl side chain of the anion of the ionic liquids. The average solvation time is also found to increase on changing the substituent from butyl to octyl, and this is attributed to the increase in the bulk viscosity of the ILs. A steady blueshift of the time-zero maximum of the fluorescence spectrum with increasing alkyl chain length also indicates that the probe molecule experiences a less polar environment in the early part of the dynamics. Rotational dynamics of C153 are also analyzed by using the Stokes-Einstein-Debye (SED), Gierer-Wirtz (GW), and Dote-Kivelson-Schwartz (DKS) theories. Analyses of the results seem to suggest decoupling of the rotational motion of the probe from solvent viscosity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Effect of the Alkyl Chain Length Incorporated into Donor Part on the Optoelectronic Properties of the Carbazole Based Dyes: Theoretical Study

    Directory of Open Access Journals (Sweden)

    Souad El Mzioui

    2017-12-01

    Full Text Available In this paper, we report a theoretical study using density functional theory (DFT and time-dependent (TD-DFT for R-D-π-A systems with various alkyl chains (R. Results show that the LUMO of the dye lies above the semiconductor conduction band, promoting the injection of electrons; the lower HOMO level promotes dye regeneration. The incorporation of methyl chain (CH3 has a significant reduction in the gap energy, improved red-shift absorption spectrum and increase the molar extinction coefficient at the maximum absorption wavelength compared to D. While, the increase in alkyl chain length from C2H5 to C6H13 present a relatively reduce of gap energies, low effect on the wavelength (438 nm and converged excitation energies. DOI: http://dx.doi.org/10.17807/orbital.v9i5.1003 

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

    Science.gov (United States)

    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.

  3. Bond length and electric current oscillation of long linear carbon chains: Density functional theory, MpB model, and quantum spin transport studies

    International Nuclear Information System (INIS)

    Oeiras, R. Y.; Silva, E. Z. da

    2014-01-01

    Carbon linear atomic chains attached to graphene have experimentally been produced. Motivated by these results, we study the nature of the carbon bonds in these nanowires and how it affects their electrical properties. In the present study we investigate chains with different numbers of atoms and we observe that nanowires with odd number of atoms present a distinct behavior than the ones with even numbers. Using graphene nanoribbons as leads, we identify differences in the quantum transport of the chains with the consequence that even and odd numbered chains have low and high electrical conduction, respectively. We also noted a dependence of current with the wire size. We study this unexpected behavior using a combination of first principles calculations and simple models based on chemical bond theory. From our studies, the electrons of carbon nanowires present a quasi-free electron behavior and this explains qualitatively the high electrical conduction and the bond lengths with unexpected values for the case of odd nanowires. Our study also allows the understanding of the electric conduction dependence with the number of atoms and their parity in the chain. In the case of odd number chains a proposed π-bond (MpB) model describes unsaturated carbons that introduce a mobile π-bond that changes dramatically the structure and transport properties of these wires. Our results indicate that the nature of bonds plays the main role in the oscillation of quantum electrical conduction for chains with even and odd number of atoms and also that nanowires bonded to graphene nanoribbons behave as a quasi-free electron system, suggesting that this behavior is general and it could also remain if the chains are bonded to other materials

  4. Equivalent chain lengths of all C4-C23 saturated monomethyl branched fatty acid methyl esters on methylsilicone OV-1 stationary phase.

    Science.gov (United States)

    Kubinec, Róbert; Blaško, Jaroslav; Górová, Renáta; Addová, Gabriela; Ostrovský, Ivan; Amann, Anton; Soják, Ladislav

    2011-04-01

    Isomer mixtures of monomethyl branched saturated C7-C23 fatty acid methyl esters (FAME) were prepared by performing a methylene insertion reaction to the straight chain FAME and this study model was completed by using commercially available standards of C4-C7 FAME. The equivalent chain lengths (ECL) of all 220 C4-C23 monomethyl branched FAME on OV-1 stationary phase were measured, achieving an average repeatability of ±0.0004 ECL units. The monomethyl branched FAME was identified by GC on the basis of regularity of the fractional chain lengths (FCL) dependence on the number of carbon atoms (C(z)) of individual homologous series of methyl 2-, 3-, …, 21-FAME. The prediction of retention of the first homologues, having the new position of methyl group beginning at higher carbon atoms number, and analogously for the second, third, fourth, and other members of the homologous series, allowed the dependence FCL=f(C(z)) for the first and subsequent members of beginning homologous of monomethyl derivatives of FAME. The identification was confirmed by mass spectrometry. All of the methyl isomers of FAME, which could not be completely separated by gas chromatography due to having a methyl group in surroundings of the middle of the carbon chain, were resolved by mass spectrometry using deconvolution in a SIM-mode. Measured gas chromatographic and mass spectrometric data were applied for identification of the monomethyl branched saturated FAME in tongue coating. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Is DNA a worm-like chain in Couette flow? In search of persistence length, a critical review.

    Science.gov (United States)

    Rittman, Martyn; Gilroy, Emma; Koohya, Hashem; Rodger, Alison; Richards, Adair

    2009-01-01

    Persistence length is the foremost measure of DNA flexibility. Its origins lie in polymer theory which was adapted for DNA following the determination of BDNA structure in 1953. There is no single definition of persistence length used, and the links between published definitions are based on assumptions which may, or may not be, clearly stated. DNA flexibility is affected by local ionic strength, solvent environment, bound ligands and intrinsic sequence-dependent flexibility. This article is a review of persistence length providing a mathematical treatment of the relationships between four definitions of persistence length, including: correlation, Kuhn length, bending, and curvature. Persistence length has been measured using various microscopy, force extension and solution methods such as linear dichroism and transient electric birefringence. For each experimental method a model of DNA is required to interpret the data. The importance of understanding the underlying models, along with the assumptions required by each definition to determine a value of persistence length, is highlighted for linear dichroism data, where it transpires that no model is currently available for long DNA or medium to high shear rate experiments.

  6. Critical determinant of intestinal permeability and oral bioavailability of pegylated all trans-retinoic acid prodrug-based nanomicelles: Chain length of poly (ethylene glycol) corona.

    Science.gov (United States)

    Li, Zhenbao; Han, Xiaopeng; Zhai, Yinglei; Lian, He; Zhang, Dong; Zhang, Wenjuan; Wang, Yongjun; He, Zhonggui; Liu, Zheng; Sun, Jin

    2015-06-01

    Pegylation method is widely used to prolong the blood circulation time of proteins and nanoparticles after intravenous administration, but the effect of surface poly (ethylene glycol) (PEG) chain length on oral absorption of the pegylated nanoparticles is poorly reported. The aim of our study was to investigate the influence of PEG corona chain length on membrane permeability and oral bioavailability of the amphiphilic pegylated prodrug-based nanomicelles, taking all trans-retinoic acid (ATRA) as a model drug. The amphiphilic ATRA-PEG conjugates were synthesized by esterification reaction between all trans-retinoic acid and mPEGs (mPEG500, mPEG1000, mPEG2000, and mPEG5000). The conjugates could self-assemble in aqueous medium to form nanomicelles by emulsion-solvent evaporation method. The resultant nanomicelles were in spherical shape with an average diameter of 13-20 nm. The drug loading efficiency of ATRA-PEG500, ATRA-PEG1000, ATRA-PEG2000, and ATRA-PEG5000 was about 38.4, 26.6, 13.1, and 5.68 wt%, respectively. With PEG chain length ranging from 500 to 5000, ATRA-PEG nanomicelles exhibited a bell shape of chemical stability in different pH buffers, intestinal homogenate and plasma. More importantly, they were all rapidly hydrolyzed into the parent drug in hepatic homogenate, with the half-time values being 0.3-0.4h. In comparison to ATRA solution and ATRA prodrug-based nanomicelles, ATRA-PEG1000 showed the highest intestinal permeability. After oral administration, ATRA-PEG2000 and ATRA-PEG5000 nanomicelles were not nearly absorbed, while the oral bioavailability of ATRA-PEG500 and ATRA-PEG1000 demonstrated about 1.2- and 2.0-fold higher than ATRA solution. Our results indicated that PEG1000 chain length of ATRA-PEG prodrug nanomicelles has the optimal oral bioavailability probably due to improved stability and balanced mucus penetration capability and cell binding, and that the PEG chain length on a surface of nanoparticles cannot exceed a key threshold with

  7. Biomimicry of surfactant protein C.

    Science.gov (United States)

    Brown, Nathan J; Johansson, Jan; Barron, Annelise E

    2008-10-01

    considerations but makes use of a non-natural, poly-N-substituted glycine or "peptoid" scaffold to circumvent the difficulties associated with SP-C. By incorporating unique biomimetic side chains in a non-natural backbone, the peptoid mimic captures both SP-C's hydrophobic patterning and its helical secondary structure. Despite the differences in structure, both SP-C33 and the SP-C peptoid mimic capture many requisite features of SP-C. In a surfactant environment, these analogues also replicate many of the key surface activities necessary for a functional biomimetic surfactant therapy while overcoming the difficulties associated with the natural protein. With improved stability, greater production potential, and elimination of possible pathogenic contamination, these biomimetic surfactant formulations offer not only the potential to improve the treatment of respiratory distress syndrome but also the opportunity to treat other respiratory-related disorders.

  8. Lipid membrane partitioning of lysolipids and fatty acids: Effects of membrane phase structure and detergent chain length

    DEFF Research Database (Denmark)

    Høyrup, Lise Pernille Kristine; Davidsen, Jesper; Jørgensen, Kent

    2001-01-01

    gel phase and at high temperatures in the disordered fluid phase of the phospholipid membrane vesicles. The long saturated acyl chains of the lysolipids and fatty acids varied from 10 to 16 carbon atoms and all titrations were performed below the critical micellar concentrations (cmc...... of magnitude higher when the saturated acyl chain of the detergents increases by two carbon atoms. The obtained partition coefficients are of importance in relation to a deeper understanding of the interplay between global aqueous and local membrane concentrations of the detergents and the functional influence...

  9. Degradation of surfactant-modified montmorillonites in HCl

    International Nuclear Information System (INIS)

    Madejová, Jana; Pálková, Helena; Jankovič, Ľuboš

    2012-01-01

    The effect of surfactant size on the extent of montmorillonites decomposition in HCl was investigated. Na-SAz montmorillonite and tetraalkylammonium salts of alkyl-chains length increasing from methyl- Me 4 N to pentyl- Pe 4 N were used for organo-montmorillonites preparation. Decreasing intensity of d 001 diffraction proved destruction of montmorillonite structure connected with gradual surfactant release. A shift of the SiO stretching band to 1097 cm −1 confirmed formation of amorphous silica phase. A new band near 7315 cm −1 corresponding to SiOH overtone revealed creation of protonated silica. This band was observed in the spectra of all acid-treated samples, also in those with minor decomposition of the structure. The size of the cations significantly affected decomposition of montmorillonites in HCl. The less stable were Na-SAz and Me 4 N-SAz in which the content of octahedral atoms dropped to ∼5% of their original values upon 8 h treatments. Et 4 N-SAz and Pr 4 N-SAz were slightly more resistant mainly at short times. Bu 4 N-SAz and Pe 4 N-SAz showed the least structural modifications, only 50% and 35% of octahedral atoms, respectively, were released into solution within 8 h treatments. This observation proves that bulky alkylammonium cations covering the inner and outer surfaces of montmorillonite prevent effectively the access of protons to the layers protecting the mineral from degradation in the acid. - Highlights: ► Hybrid materials were prepared from montmorillonite and alkylammonium cations with short alkyl chains. ► The effect of surfactant on organo-montmorillonites dissolution in HCl was studied. ► With increasing size of cation the extent of montmorillonite decomposition decreased. ► Bulky surfactants prevent the access of protons to the layers and thus protect montmorillonite from degradation.

  10. Novel extracellular medium-chain-length polyhydroxyalkanoate depolymerase from Streptomyces exfoliatus K10 DSMZ 41693

    DEFF Research Database (Denmark)

    Martinez, Virginia; de Santos, Patricia Gómez; García-Hidalgo, Javier

    2015-01-01

    reaction product. Markedly, PhaZSex2 is able to degrade functionalized polymers containing thioester groups in the side chain (PHACOS), releasing functional thioester-based monomers and oligomers demonstrating the potentiality of this novel biocatalyst for the industrial production of enantiopure (R)-3...

  11. Highly Grafted Polystyrene/polyvinylpyridine Polymer Gold Nanoparticles in a Good Solvent: Effects of Chain Length and Composition.

    Czech Academy of Sciences Publication Activity Database

    Posel, Zbyšek; Posocco, P.; Lísal, Martin; Fermeglia, M.; Pricl, S.

    2016-01-01

    Roč. 12, č. 15 (2016), s. 3600-3611 ISSN 1744-683X R&D Projects: GA ČR(CZ) GA13-02938S; GA MŠk LH12020 Institutional support: RVO:67985858 Keywords : block copolymers * chains * fiber optic sensors Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.889, year: 2016

  12. Revisit complexation between DNA and polyethylenimine — Effect of length of free polycationic chains on gene transfection

    DEFF Research Database (Denmark)

    Yue, Yanan; Jin, Fan; Deng, Rui

    2011-01-01

    Our revisit of the complexation between DNA and polyethylenimine (PEI) by using a combination of laser light scattering and gel electrophoresis confirms that nearly all the DNA chains are complexed with PEI to form polyplexes when the molar ratio of nitrogen from PEI to phosphate from DNA (N:P) r...

  13. Molecular organization and dynamics of micellar phase of polyelectrolyte-surfactant complexes: ESR spin probe study

    Science.gov (United States)

    Wasserman, A. M.; Kasaikin, V. A.; Zakharova, Yu. A.; Aliev, I. I.; Baranovsky, V. Yu.; Doseva, V.; Yasina, L. L.

    2002-04-01

    Molecular dynamics and organization of the micellar phase of complexes of linear polyelectrolytes with ionogenic and non-ionogenic surfactants was studied by the ESR spin probe method. Complexes of polyacrylic acid (PAA) and sodium polystyrenesulfonate (PSS) with alkyltrimethylammonium bromides (ATAB), as well as complexes of poly- N, N'-dimethyldiallylammonium chloride (PDACL) with sodium dodecylsulfate (SDS) were studied. The micellar phase of such complexes is highly organized molecular system, molecular ordering of which near the polymeric chain is much higher than in the 'center' of the micelle, it depends on the polymer-detergent interaction, flexibility of polymeric chain and length of carbonic part of the detergent molecule. Complexes of polymethacrylic acid (PMAA) with non-ionic detergent (dodecyl-substituted polyethyleneglycol), show that the local mobility of surfactant in such complexes is significantly lower than in 'free' micelles and depends on the number of micellar particles participating in formation of complexes.

  14. Aquatic toxicity and biodegradability of advanced cationic surfactant APA-22 compatible with the aquatic environment.

    Science.gov (United States)

    Yamane, Masayuki; Toyo, Takamasa; Inoue, Katsuhisa; Sakai, Takaya; Kaneko, Youhei; Nishiyama, Naohiro

    2008-01-01

    Cationic surfactant is a chemical substance used in hair conditioner, fabric softener and other household products. By investigating the relationship between the aquatic toxicity and the chemical structures of two types of mono alkyl cationic surfactants, alkyl trimethylammonium salts and alkyl dimethylamine salts, we have found that the C22 alkyl chain length is effective to reduce the toxicity. Besides, we have recognized that the amidopropyl functional group contributes to the enhanced biodegradability by investigating the biodegradation trend of (alkylamidopropyl)dimethylamine salt (alkyl chain length: C18). Based on these findings, we have developed mono alkyl cationic surfactant called APA-22, N-[3-(dimethylamino)propyl]docosanamide salt. APA-22 is formed by the C22 alkyl chain, amidopropyl functional group and di-methyltertiary amine group. We evaluated the aerobic and anaerobic biodegradability of APA-22 by two standard methods (OECD Test Guideline 301B and ECETOC technical document No.28) and found that this substance was degraded rapidly in both conditions. The toxicity to algae, invertebrate and fish of this substance are evaluated by using OECD Test Guideline 201, 202 and 203, respectively. All acute toxicity values are >1 mg/L, which indicates that environmental toxicity of this substance is relatively less toxic to aquatic organism. In addition, we estimated the biodegradation pathway of APA-22 and observed the complete disappearance of APA-22 and its intermediates during the test periods. Based on the environmental data provided above, we concluded that APA22 is more compatible with the aquatic environment compared to other cationic surfactants with mono long alkyl chain.

  15. Biomimetic oligosaccharide and peptide surfactant polymers designed for cardiovascular biomaterials

    Science.gov (United States)

    Ruegsegger, Mark Andrew

    A common problem associated with cardiovascular devices is surface induced thrombosis initiated by the rapid, non-specific adsorption of plasma proteins onto the biomaterial surface. Control of the initial protein adsorption is crucial to achieve the desired longevity of the implanted biomaterial. The cell membrane glycocalyx acts as a non-thrombogenic interface through passive (dense oligosaccharide structures) and active (ligand/receptor interactions) mechanisms. This thesis is designed to investigate biomimicry of the cell glycocalyx to minimize non-specific protein adsorption and promote specific ligand/receptor interactions. Biomimetic macromolecules were designed through the molecular-scale engineering of polymer surfactants, utilizing a poly(vinyl amine) (PVAm) backbone to which hydrophilic (dextran, maltose, peptide) and hydrophobic alkyl (hexanoyl or hexanal) chains are simultaneously attached. The structure was controlled through the molar feed ratio of hydrophobic-to-hydrophilic groups, which also provided control of the solution and surface-active properties. To mimic passive properties, a series of oligomaltose surfactants were synthesized with increasing saccharide length (n = 2, 7, 15 where n is number of glucose units) to investigate the effect of coating height on protein adsorption. The surfactants were characterized by infra red (IR) and nuclear magnetic resonance (NMR) spectroscopies for structural properties and atomic force microscopy (AFM) and contact angle goniometry for surface activity. Protein adsorption under dynamic flow (5 dyn/cm2) was reduced by 85%--95% over the bare hydrophobic substrate; platelet adhesion dropped by ˜80% compared to glass. Peptide ligands were incorporated into the oligosaccharide surfactant to promote functional activity of the passive coating. The surfactants were synthesized to contain 0%, 25%, 50%, 75%, and 100% peptide ligand density and were stable on hydrophobic surfaces. The peptide surface density was

  16. Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

    International Nuclear Information System (INIS)

    Alsabagh, A.M.; Migahed, M.A.; Awad, Hayam S.

    2006-01-01

    Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV (∼96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules

  17. Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

    Energy Technology Data Exchange (ETDEWEB)

    Alsabagh, A.M. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt); Migahed, M.A. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt)]. E-mail: mohamedatiyya707@hotmail.com; Awad, Hayam S. [Chemistry Department, Faculty of Girls for Science, Art and Education, Ain Shams University, Asmaa Fahmi Street, Helliopolis, Cairo (Egypt)

    2006-04-15

    Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV ({approx}96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules.

  18. Influence of alkyl chain length and anion species on ionic liquid structure at the graphite interface as a function of applied potential

    International Nuclear Information System (INIS)

    Li, Hua; Wood, Ross J; Atkin, Rob; Endres, Frank

    2014-01-01

    Atomic force microscopy (AFM) force measurements elucidate the effect of cation alkyl chain length and the anion species on ionic liquid (IL) interfacial structure at highly ordered pyrolytic graphite (HOPG) surfaces as a function of potential. Three ILs are examined: 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP), 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM] FAP), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] TFSA). The step-wise force-distance profiles indicate the ILs adopt a multilayered morphology near the surface. When the surface is biased positively or negatively versus Pt quasireference electrode, both the number of steps, and the force required to rupture each step increase, indicating stronger interfacial structure. At all potentials, push-through forces for [HMIM] FAP are the highest, because the long alkyl chain results in strong cohesive interactions between cations, leading to well-formed layers that resist the AFM tip. The most layers are observed for [EMIM] FAP, because the C 2 chains are relatively rigid and the dimensions of the cation and anion are similar, facilitating neat packing. [EMIM] TFSA has the smallest push-through forces and fewest layers, and thus the weakest interfacial structure. Surface-tip attractive forces are measured for all ILs. At the same potential, the attractions are the strongest for [EMIM] TFSA and the weakest for [HMIM] FAP because the interfacial layers are better formed for the longer alkyl chain cation. This means interfacial forces are stronger, which masks the weak attractive forces. (paper)

  19. Effects of Chain Length and Degree of Unsaturation of Fatty Acids on Structure and in Vitro Digestibility of Starch-Protein-Fatty Acid Complexes.

    Science.gov (United States)

    Zheng, Mengge; Chao, Chen; Yu, Jinglin; Copeland, Les; Wang, Shuo; Wang, Shujun

    2018-02-28

    The effects of chain length and degree of unsaturation of fatty acids (FAs) on structure and in vitro digestibility of starch-protein-FA complexes were investigated in model systems. Studies with the rapid visco analyzer (RVA) showed that the formation of ternary complex resulted in higher viscosities than those of binary complex during the cooling and holding stages. The results of differential scanning calorimetry (DSC), Raman, and X-ray diffraction (XRD) showed that the structural differences for ternary complexes were much less than those for binary complexes. Starch-protein-FA complexes presented lower in vitro enzymatic digestibility compared with starch-FAs complexes. We conclude that shorter chain and lower unsaturation FAs favor the formation of ternary complexes but decrease the thermal stability of these complexes. FAs had a smaller effect on the ordered structures of ternary complexes than on those of binary complexes and little effect on enzymatic digestibility of both binary and ternary complexes.

  20. Critical effects of alkyl chain length on fibril structures in benzene-trans(RR)- or (SS)-N,N'-alkanoyl-1,2-diaminocyclohexane gels.

    Science.gov (United States)

    Sato, Hisako; Nakae, Takahiro; Morimoto, Kazuya; Tamura, Kenji

    2012-02-28

    Vibrational circular dichroism (VCD) spectra were recorded on benzene-d(6) gels formed by chiral low molecular mass gelators (LMGs), trans(RR)- or trans(SS)-N,N'-alkanoyl-1,2-diaminocyclohexane (denoted by RR-C(n) or SS-C(n), respectively; n = the number of carbon atoms in an introduced alkanoyl group). Attention was focused on the effects of alkyl chain length on the structures of the gels. When n was changed from 6 to 12, the signs of the coupled peaks around 1550 cm(-1) in the VCD spectra, which were assigned to the symmetric and asymmetric C=O stretching vibrations from the higher to lower wavenumber, respectively, critically depended on the alkyl chain length. In the case of RR-C(n), for example, the signs of the couplet were plus and minus for n = 8, 9, 10 and 12, while the signs of the same couplet were reversed for n = 6 and 7. The conformations of LMGs in fibrils were determined by comparing the observed IR and VCD spectra with those calculated for a monomeric molecule. The observed reversal of signs in the C=O couplet was rationalized in terms of the different modes of hydrogen bonding. In the case of C(8), C(9), C(10) and C(12), gelator molecules were stacked with their cyclohexyl rings in parallel, forming double anti-parallel chains of intermolecular hydrogen bonds using two pairs of >NH and >C=O groups. In case of C(6) and C(7), gelator molecules were stacked through a single chain of intermolecular hydrogen bonds using a pair of >NH and >C=O groups. The remaining pair of >NH and >C=O groups formed an intramolecular hydrogen bond.

  1. The Alkali/Surfactant/ Polymer Process: Effects of Slug Size, Core Length and a Chase Polymer Le procédé alkali/surfactant/polymère : effets de la taille du bouchon, de la longueur de la carotte et d'un polymère de déplacement

    Directory of Open Access Journals (Sweden)

    Green K. A.

    2006-11-01

    Full Text Available An experimental study was conducted to examine the effects of slug size, core length, and a chase polymer on the effectiveness of the alkali/surfactant/polymer (A/S/P process in recovering waterflood residual oil. Core flood experiments were conducted with unfired linear Berea sandstone cores. The tertiary oil recovery, oil cut, pressure drop, and chemical propagation were measured for each flood. Tertiary oil recovery significantly increased with the slug size up to 0. 5 of a pore volume. Increasing the slug size further resulted in a smaller incremental increase in oil recovery. A slight increase in tertiary oil recovery was obtained when small size A/S/P slugs were followed with achase polymer having a viscosity higher than the slug. The lack of oil recovery with small A/S/P slugs was due to the consumption and dilution of the injected chemicals, especially the synthetic surfactant, due to adsorption and dispersion. Increasing the core length by a factor of 4. 5 (from 9 to 40. 6 cm had no significant effect on tertiary oil recovery. Chemical propagation was found to be a function of core length (i. e. , core Peclet number and the size of the chase polymer slug. Increasing core length and employing a chase polymer maintained the integrity of the A/S/P slug by decreasing the effect of dispersion and minimizing the influence of viscous fingering at the tail of the A/S/P slug. Une étude expérimentale a été effectuée pour examiner les effets de la taille du bouchon, de la longueur de la carotte et de l'emploi d'un polymère de déplacement sur l'efficacité du procédé A/S/P (alkali/surfactant/polymère dans la récupération d'huile résiduelle par injection d'eau. Les expériences d'injection ont été faites avec des carottes rectilignes en grès de Berea vert. La récupération tertiaire du pétrole, la présence d'eau, la perte de charge et la propagation chimique ont été mesurées pour chaque injection. La récupération tertiaire du

  2. Photo-Induced Phase Transitions to Liquid Crystal Phases: Influence of the Chain Length from C8E4 to C14E4

    Directory of Open Access Journals (Sweden)

    Simone Techert

    2009-09-01

    Full Text Available Photo-induced phase transitions are characterized by the transformation from phase A to phase B through the absorption of photons. We have investigated the mechanism of the photo-induced phase transitions of four different ternary systems CiE4/alkane (i with n = 8, 10, 12, 14; cyclohexane/H2O. We were interested in understanding the effect of chain length increase on the dynamics of transformation from the microemulsion phase to the liquid crystal phase. Applying light pump (pulse/x-ray probe (pulse techniques, we could demonstrate that entropy and diffusion control are the driving forces for the kind of phase transition investigated.

  3. Thermodynamics of non-ionic surfactant Triton X-100-cationic surfactants mixtures at the cloud point

    International Nuclear Information System (INIS)

    Batigoec, Cigdem; Akbas, Halide; Boz, Mesut

    2011-01-01

    Highlights: → Non-ionic surfactants are used as emulsifier and solubilizate in such as textile, detergent and cosmetic. → Non-ionic surfactants occur phase separation at temperature as named the cloud point in solution. → Dimeric surfactants have attracted increasing attention due to their superior surface activity. → The positive values of ΔG cp 0 indicate that the process proceeds nonspontaneous. - Abstract: This study investigates the effects of gemini and conventional cationic surfactants on the cloud point (CP) of the non-ionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The thermodynamic parameters of these mixtures were calculated at different cationic surfactant concentrations. The gemini surfactants of the alkanediyl-α-ω-bis (alkyldimethylammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as 'm-2-m' (m = 10, 12, and 16) and, on the other hand, with -C 16 alkyl groups and different spacers containing s carbon atoms, referred to as '16-s-16' (s = 6 and 10) were synthesized, purified and characterized. Additions of the cationic surfactants to the TX-100 solution increased the cloud point temperature of the TX-100 solution. It was accepted that the solubility of non-ionic surfactant containing polyoxyethylene (POE) hydrophilic chain was a maximum at the cloud point so that the thermodynamic parameters were calculated at this temperature. The results showed that the standard Gibbs free energy (ΔG cp 0 ), the enthalpy (ΔH cp 0 ) and the entropy (ΔS cp 0 ) of the clouding phenomenon were found positive in all cases. The standard free energy (ΔG cp 0 ) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic surfactants; however, it decreased with increasing surfactant concentration.

  4. Flow behaviour of inulin-milk beverages: Influence of inulin chain length and of milk fat content

    OpenAIRE

    Villegas, Beatriz; Costell, Elvira

    2003-01-01

    Inulin is used either as a macronutrient substitute or as a supplement added in foods mainly for its nutritional properties. Chemically, inulin consists of a long chain made up of fructose molecules and one glucose molecule at one end. The fructose molecules are connected by β-(2-1) bonds and the last fructose is linked with a glucose by an α-(1-2) bond as in sucrose [1, 2]. The average molecular weight and degree of polymerisation of inulin depend on the source of inulin, the time of harvest...

  5. Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants

    International Nuclear Information System (INIS)

    Min, Sa Hoon; Jang, Jyongsik; Lee, Kyung Jin; Bae, Joonwon

    2013-01-01

    Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol–gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant. (paper)

  6. Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Min, Sa Hoon; Jang, Jyongsik; Lee, Kyung Jin [School of Chemical and Biological Engineering, College of Engineering, Seoul National University, Shinlimdong 56-1, Seoul, 151-742 (Korea, Republic of); Bae, Joonwon [Department of Applied Chemistry, Dongduk Women' s University, Seoul 136-714 (Korea, Republic of)

    2013-06-28

    Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol-gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant. (paper)

  7. Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants

    Science.gov (United States)

    Min, Sa Hoon; Bae, Joonwon; Jang, Jyongsik; Lee, Kyung Jin

    2013-06-01

    Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol-gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant.

  8. Solute transport in a single fracture involving an arbitrary length decay chain with rock matrix comprising different geological layers.

    Science.gov (United States)

    Mahmoudzadeh, Batoul; Liu, Longcheng; Moreno, Luis; Neretnieks, Ivars

    2014-08-01

    A model is developed to describe solute transport and retention in fractured rocks. It accounts for advection along the fracture, molecular diffusion from the fracture to the rock matrix composed of several geological layers, adsorption on the fracture surface, adsorption in the rock matrix layers and radioactive decay-chains. The analytical solution, obtained for the Laplace-transformed concentration at the outlet of the flowing channel, can conveniently be transformed back to the time domain by the use of the de Hoog algorithm. This allows one to readily include it into a fracture network model or a channel network model to predict nuclide transport through channels in heterogeneous fractured media consisting of an arbitrary number of rock units with piecewise constant properties. More importantly, the simulations made in this study recommend that it is necessary to account for decay-chains and also rock matrix comprising at least two different geological layers, if justified, in safety and performance assessment of the repositories for spent nuclear fuel. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Critical Length Criterion and the Arc Chain Model for Calculating the Arcing Time of the Secondary Arc Related to AC Transmission Lines

    International Nuclear Information System (INIS)

    Cong Haoxi; Li Qingmin; Xing Jinyuan; Li Jinsong; Chen Qiang

    2015-01-01

    The prompt extinction of the secondary arc is critical to the single-phase reclosing of AC transmission lines, including half-wavelength power transmission lines. In this paper, a low-voltage physical experimental platform was established and the motion process of the secondary arc was recorded by a high-speed camera. It was found that the arcing time of the secondary arc rendered a close relationship with its arc length. Through the input and output power energy analysis of the secondary arc, a new critical length criterion for the arcing time was proposed. The arc chain model was then adopted to calculate the arcing time with both the traditional and the proposed critical length criteria, and the simulation results were compared with the experimental data. The study showed that the arcing time calculated from the new critical length criterion gave more accurate results, which can provide a reliable criterion in term of arcing time for modeling and simulation of the secondary arc related with power transmission lines. (paper)

  10. Optimized mixed oils remarkably reduce the amount of surfactants in microemulsions without affecting oral bioavailability of ibuprofen by simultaneously enlarging microemulsion areas and enhancing drug solubility.

    Science.gov (United States)

    Chen, Yizhen; Tuo, Jue; Huang, Huizhi; Liu, Dan; You, Xiuhua; Mai, Jialuo; Song, Jiaqi; Xie, Yanqi; Wu, Chuanbin; Hu, Haiyan

    2015-06-20

    The toxicity and irritation associated with high amounts of surfactants restrict the extensive utilization of microemulsions. To address these shortcomings, employing mixed oils to enlarge microemulsion areas therefore reducing surfactant contents is a promising strategy. However, what kinds of mixed oils are more efficient in enlarging microemulsion areas still remains unclear. In this research, we found that the chain length and degree of unsaturation of oils play a key role in enlarging microemulsion areas. The combination of moderate chain saturated oil caprylic/capric triglyceride (GTCC) with long chain unsaturated oil glycerol trioleate significantly increased the microemulsion areas. Solubility of ibuprofen in the mixed oils was unexpectedly and remarkably increased (almost 300mg/mL) compared with that (around 100mg/mL) of the single oil (GTCC), which also resulted in greatly increased solubility of ibuprofen in mixed oils-containing microemulsions. By optimizing the mixed oil formulation, the absolute amount of surfactant in drug-loaded microemulsions was reduced but increased drug oral bioavailability in rats was maintained. It could be concluded that the combined use of moderate chain oils and long chain unsaturated oils could not only acquire enlarged microemulsion areas but also enhanced drug solubility, therefore doubly reducing surfactant amount, which is extremely beneficial for developing safe microemulsions. Copyright © 2015. Published by Elsevier B.V.

  11. Synthesis of butyl acrylate-styrene block copolymers in emulsion by reversible addition-fragmentation chain transfer : effect of surfactant migration upon film formation

    NARCIS (Netherlands)

    Monteiro, M.J.; Sjöberg, M.; Göttgens, C.M.; Vlist, van der J.

    2000-01-01

    The synthesis of block copolymers in an environmentally friendly medium was carried out in emulsion polymerizations through the reversible addition-fragmentation chain transfer process, using a transfer active xanthate (MADIX) agent, under batch and starved-feed conditions. First, ab initio

  12. Effect of temperature and chain length on the viscosity and surface tension of binary systems of N,N-dimethylformamide with 1-octanol, 1-nonanol and 1-decanol

    International Nuclear Information System (INIS)

    Mohammad, Abubaker A.; Alkhaldi, Khaled H.A.E.; AlTuwaim, Mohammad S.; Al-Jimaz, Adel S.

    2014-01-01

    Highlights: • Effect of temperature and chain length on η and σ of DMF + 1-alkanol binary systems. • Viscosity and surface tension were obtained. • Δη, Δσ and G ∗E were calculated using the experimental data. • H σ and S σ were determined using the surface tension data. • Semi-empirical relations were used to estimate the viscosity of liquid mixtures. - Abstract: Viscosity and surface tension of binary systems of N,N-dimethylformamide DMF with higher 1-alkanols (C 8 –C 10 ) were measured at atmospheric pressure and four different temperatures over the entire range of mole fraction. The experimental measurements were used to calculate the deviations in viscosity and surface tension. Furthermore, the excess Gibbs free energy of activation, surface enthalpy and surface entropy of the (DMF + 1-alkanols) binary mixtures were determined. In addition, the deviation and excess properties were fitted to the method of Redlich–Kister (R–K) polynomial. Viscosity data of the binary systems were correlated with three different expressions (Grunberg and Nissan, the three-body, and four-body McAllister). The effects of the chain length of the higher 1-alkanols and temperature were investigated

  13. Individual Impact of Distinct Polysialic Acid Chain Lengths on the Cytotoxicity of Histone H1, H2A, H2B, H3 and H4

    Directory of Open Access Journals (Sweden)

    Kristina Zlatina

    2017-12-01

    Full Text Available Neutrophils are able to neutralize pathogens by phagocytosis, by the release of antimicrobial components, as well as by the formation of neutrophil extracellular traps (NETs. The latter possibility is a DNA-meshwork mainly consisting of highly concentrated extracellular histones, which are not only toxic for pathogens, but also for endogenous cells triggering several diseases. To reduce the negative outcomes initiated by extracellular histones, different approaches like antibodies against histones, proteases, and the polysaccharide polysialic acid (polySia were discussed. We examined whether each of the individual histones is a binding partner of polySia, and analyzed their respective cytotoxicity in the presence of this linear homopolymer. Interestingly, all of the histones (H1, H2A, H2B, H3, and H4 seem to interact with α2,8-linked sialic acids. However, we observed strong differences regarding the required chain length of polySia to bind histone H1, H2A, H2B, H3, and H4. Moreover, distinct degrees of polymerization were necessary to act as a cytoprotective agent in the presence of the individual histones. In sum, the outlined results described polySia-based strategies to bind and/or to reduce the cytotoxicity of individual histones using distinct polySia chain length settings.

  14. Effect of Acylglycerol Composition and Fatty Acyl Chain Length on Lipid Digestion in pH-Stat Digestion Model and Simulated In Vitro Digestion Model.

    Science.gov (United States)

    Qi, Jin F; Jia, Cai H; Shin, Jung A; Woo, Jeong M; Wang, Xiang Y; Park, Jong T; Hong, Soon T; Lee, K-T

    2016-02-01

    In this study, a pH-stat digestion model and a simulated in vitro digestion model were employed to evaluate the digestion degree of lipids depending on different acylglycerols and acyl chain length (that is, diacylglycerol [DAG] compared with soybean oil representing long-chain triacylglycerol compared with medium-chain triacylglycerol [MCT]). In the pH-stat digestion model, differences were observed among the digestion degrees of 3 oils using digestion rate (k), digestion half-time (t1/2 ), and digestion extent (Φmax). The results showed the digestion rate order was MCT > soybean oil > DAG. Accordingly, the order of digestion half-times was MCT digestion model, digestion rates (k') and digestion half-times (t'1/2 ) were also obtained and the results showed a digestion rate order of MCT (k' = 0.068 min(-1) ) > soybean oil (k' = 0.037 min(-1) ) > DAG (k' = 0.024 min(-1) ). Consequently, the order of digestion half-times was MCT (t'1/2 = 10.20 min) digested faster than soybean oil, and that soybean oil was digested faster than DAG. © 2015 Institute of Food Technologists®

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Effect of alkyl chain length on the rotational diffusion of nonpolar and ionic solutes in 1-alkyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imides.

    Science.gov (United States)

    Gangamallaiah, V; Dutt, G B

    2013-10-10

    Rotational diffusion of a nonpolar solute 9-phenylanthracene (9-PA) and a cationic solute rhodamine 110 (R110) has been examined in a series of 1-alkyl-3-methylimidazolium (alkyl = octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl) bis(trifluoromethylsulfonyl)imides to understand the influence of alkyl chain length on solute rotation. In this study, reorientation times (τr) have been measured as a function of viscosity (η) by varying the temperature (T) of the solvents. These results have been analyzed using the Stokes-Einstein-Debye (SED) hydrodynamic theory along with the ones obtained for the same solutes in 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides (Gangamallaiah and Dutt, J. Phys. Chem. B 2012, 116, 12819-12825). It has been noticed that the data for 9-PA and R110 follows the relation τr = A(η/T)(n) with A being the ratio of hydrodynamic volume of the solute to the Boltzmann constant and n = 1 as envisaged by the SED theory. However, upon increasing the alkyl chain length from methyl to octadecyl significant deviations from the SED theory have been observed especially from the octyl derivative onward. From methyl to octadecyl derivatives, the value of A decreases by a factor of 3 for both the solutes and n by a factor of 1.4 and 1.6 for 9-PA and R110, respectively. These observations have been rationalized by taking into consideration the organized structure of the ionic liquids, whose influence appears to be pronounced when the number of carbon atoms in the alkyl chain attached to the imidazolium cation exceeds eight.

  17. Oligothiophene-Indandione-Linked Narrow-Band Gap Molecules: Impact of π-Conjugated Chain Length on Photovoltaic Performance.

    Science.gov (United States)

    Komiyama, Hideaki; To, Takahiro; Furukawa, Seiichi; Hidaka, Yu; Shin, Woong; Ichikawa, Takahiro; Arai, Ryota; Yasuda, Takuma

    2018-04-04

    Solution-processed organic solar cells (OSCs) based on narrow-band gap small molecules hold great promise as next-generation energy-converting devices. In this paper, we focus on a family of A-π-D-π-A-type small molecules, namely, BDT- nT-ID ( n = 1-4) oligomers, consisting of benzo[1,2- b:4,5- b']dithiophene (BDT) as the central electron-donating (D) core, 1,3-indandione (ID) as the terminal electron-accepting (A) units, and two regioregular oligo(3-hexylthiophene)s ( nT) with different numbers of thiophene rings as the π-bridging units, and elucidate their structure-property-function relationships. The effects of the length of the π-bridging nT units on the optical absorption, thermal behavior, morphology, hole mobility, and OSC performance were systematically investigated. All oligomers exhibited broad and intense visible photoabsorption in the 400-700 nm range. The photovoltaic performances of bulk heterojunction OSCs based on BDT- nT-IDs as donors and a fullerene derivative as an acceptor were studied. Among these oligomers, BDT-2T-ID, incorporating bithiophene as the π-bridging units, showed better photovoltaic performance with a maximum power conversion efficiency as high as 6.9% under AM 1.5G illumination without using solvent additives or postdeposition treatments. These favorable properties originated from the well-developed interpenetrating network morphology of BDT-2T-ID, with larger domain sizes in the photoactive layer. Even though all oligomers have the same A-D-A main backbone, structural modulation of the π-bridging nT length was found to impact their self-organization and nanostructure formation in the solid state, as well as the corresponding OSC device performance.

  18. Determination of locust bean gum and guar gum by polymerase chain reaction and restriction fragment length polymorphism analysis.

    Science.gov (United States)

    Meyer, K; Rosa, C; Hischenhuber, C; Meyer, R

    2001-01-01

    A polymerase chain reaction (PCR) was developed to differentiate the thickening agents locust bean gum (LBG) and the cheaper guar gum in finished food products. Universal primers for amplification of the intergenic spacer region between trnL 3' (UAA) exon and trnF (GAA) gene in the chloroplast (cp) genome and subsequent restriction analysis were applied to differentiate guar gum and LBG. The presence of guar gum powder added to LBG powder was detectable. Based on data obtained from sequencing this intergenic spacer region, a second PCR method for the specific detection of guar gum DNA was also developed. This assay detected guar gum powder in LBG in amounts as low as 1% (w/w). Both methods successfully detected guar gum and/or LBG in ice cream stabilizers and in foodstuffs, such as dairy products, ice cream, dry seasoning mixes, a finished roasting sauce, and a fruit jelly product, but not in products with highly degraded DNA, such as tomato ketchup and sterilized chocolate cream. Both methods detected guar gum and LBG in ice cream and fresh cheese at levels <0.1%.

  19. Perfluoroalkyl sulfonates cause alkyl chain length-dependent hepatic steatosis and hypolipidemia mainly by impairing lipoprotein production in APOE*3-leiden CETP mice

    NARCIS (Netherlands)

    Bijland, S.; Rensen, P.C.N.; Pieterman, E.J.; Maas, A.C.E.; Hoorn, J.W. van der; Erk, M.J. van; Havekes, L.M.; Dijk, K.W. van; Chang, S.C.; Ehresman, D.J.; Butenhoff, J.L.; Princen, H.M.G.

    2011-01-01

    Perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) are stable perfluoroalkyl sulfonate (PFAS) surfactants, and PFHxS and PFOS are frequently detected in human biomonitoring studies. Some epidemiological studies have shown modest positive

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

    Science.gov (United States)

    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.

  1. Tunable, antibacterial activity of silicone polyether surfactants.

    Science.gov (United States)

    Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

    2015-08-01

    Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Enterococcus faecalis Responds to Individual Exogenous Fatty Acids Independently of Their Degree of Saturation or Chain Length.

    Science.gov (United States)

    Saito, Holly E; Harp, John R; Fozo, Elizabeth M

    2018-01-01

    Enterococcus faecalis is a commensal of the human gastrointestinal tract that can persist in the external environment and is a leading cause of hospital-acquired infections. Given its diverse habitats, the organism has developed numerous strategies to survive a multitude of environmental conditions. Previous studies have demonstrated that E. faecalis will incorporate fatty acids from bile and serum into its membrane, resulting in an induced tolerance to membrane-damaging agents. To discern whether all fatty acids induce membrane stress protection, we examined how E. faecalis responded to individually supplied fatty acids. E. faecalis readily incorporated fatty acids 14 to 18 carbons in length into its membrane but poorly incorporated fatty acids shorter or longer than this length. Supplementation with saturated fatty acids tended to increase generation time and lead to altered cellular morphology in most cases. Further, exogenously supplied saturated fatty acids did not induce tolerance to the membrane-damaging antibiotic daptomycin. Supplementation with unsaturated fatty acids produced variable growth effects, with some impacting generation time and morphology. Exogenously supplied unsaturated fatty acids that are normally produced by E. faecalis and those that are found in bile or serum could restore growth in the presence of a fatty acid biosynthetic inhibitor. However, only the eukaryote-derived fatty acids oleic acid and linoleic acid provided protection from daptomycin. Thus, exogenous fatty acids do not lead to a common physiological effect on E. faecalis The organism responds uniquely to each, and only host-derived fatty acids induce membrane protection. IMPORTANCE Enterococcus faecalis is a commonly acquired hospital infectious agent with resistance to many antibiotics, including those that target its cellular membrane. We previously demonstrated that E. faecalis will incorporate fatty acids found in human fluids, like serum, into its cellular membrane

  3. Modification of reduced-charge montmorillonites by a series of Gemini surfactants: Characterization and application in methyl orange removal

    International Nuclear Information System (INIS)

    Luo, Zhongxin; Gao, Manglai; Ye, Yage; Yang, Senfeng

    2015-01-01

    Highlights: • RCMs were modified by three Gemini surfactants with different spacer length. • The adsorption kinetics and thermodynamics of MO on organoclays were investigated. • Both the spacer length and clay layer charge have significant effects on the removal of MO. • The removal efficiency of MO increased with increasing clay layer charge. • Gemini surfactants modified RCMs were low-cost and high efficient adsorbents for the uptake of MO. - Abstract: The influences that the spacer chain length of Gemini surfactants and clay layer charge have on the structures and sorption characteristics of organoclays have been investigated. Organoclays were obtained by modifying a series of reduced charge montmorillonites (RCMs) using three Gemini surfactants with different spacer length. And their structures and sorption characteristics for methyl orange (MO) were examined. It was suggested that the amount, spacer length of Gemini surfactant and clay layer charge had significant effects on the microstructure of the organoclays. The adsorption experiments results claimed that the uptake of MO onto organoclays was in the order: 16-4-16-Mt > 16-8-16-Mt > 16-6-16-Mt, while it increased with increasing clay layer charge. The adsorption isotherms of MO onto the organoclays could be best described by Langmuir equation, and the adsorption kinetic was in good agreement with the pseudo-second-order model. Thermodynamic parameters demonstrated that the sorption process was spontaneous and endothermic in nature. This work will provide a deep insight into the interaction of Gemini-modified clays and MO, which pave the way for their practical applications in anionic dye adsorption

  4. Modification of reduced-charge montmorillonites by a series of Gemini surfactants: Characterization and application in methyl orange removal

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Zhongxin; Gao, Manglai, E-mail: mlgao@cup.edu.cn; Ye, Yage; Yang, Senfeng

    2015-01-01

    Highlights: • RCMs were modified by three Gemini surfactants with different spacer length. • The adsorption kinetics and thermodynamics of MO on organoclays were investigated. • Both the spacer length and clay layer charge have significant effects on the removal of MO. • The removal efficiency of MO increased with increasing clay layer charge. • Gemini surfactants modified RCMs were low-cost and high efficient adsorbents for the uptake of MO. - Abstract: The influences that the spacer chain length of Gemini surfactants and clay layer charge have on the structures and sorption characteristics of organoclays have been investigated. Organoclays were obtained by modifying a series of reduced charge montmorillonites (RCMs) using three Gemini surfactants with different spacer length. And their structures and sorption characteristics for methyl orange (MO) were examined. It was suggested that the amount, spacer length of Gemini surfactant and clay layer charge had significant effects on the microstructure of the organoclays. The adsorption experiments results claimed that the uptake of MO onto organoclays was in the order: 16-4-16-Mt > 16-8-16-Mt > 16-6-16-Mt, while it increased with increasing clay layer charge. The adsorption isotherms of MO onto the organoclays could be best described by Langmuir equation, and the adsorption kinetic was in good agreement with the pseudo-second-order model. Thermodynamic parameters demonstrated that the sorption process was spontaneous and endothermic in nature. This work will provide a deep insight into the interaction of Gemini-modified clays and MO, which pave the way for their practical applications in anionic dye adsorption.

  5. Production of medium-chain-length polyhydroxyalkanoate by Pseudomonas oleovorans grown in sugary cassava extract supplemented with andiroba oil

    Directory of Open Access Journals (Sweden)

    Diego Aires da Silva

    2014-12-01

    Full Text Available Pseudomonas oleovorans were grown on sugary cassava extracts supplemented with andiroba oil for the synthesis of a mediumchain- length polyhydroxyalkanoate (PHA MCL. The concentration of total sugars in the extract was approximately: 40 g/L in culture 1, 15 g/L in cultures 2 and 3, and 10 g/L in culture 4. Supplementation with 1% andiroba oil and 0.2 g/L of (NH42HPO4 was performed 6.5 hours after growth in culture 3, and supplementation with the same amount of andiroba oil and 2.4 g/L of (NH42HPO4 was performed at the beginning of growth in culture 4. The synthesis resulted mainly in 3-hydroxy-decanoate and 3-hydroxy-dodecanoate units; 3-hydroxy-butyrate, 3-hydroxy-hexanoate; and 3-hydroxy-octanoate monomers were also produced but in smaller proportions. P. oleovorans significantly accumulated PHA MCL in the deceleration phase of growth with an oxygen limitation but with sufficient nitrogen concentration to maintain cell growth. The sugary cassava extract supplemented with andiroba oil proved to be a potential substrate for PHA MCL production.

  6. Dependency of Anion and Chain Length of Imidazolium Based Ionic Liquid on Micellization of the Block Copolymer F127 in Aqueous Solution: An Experimental Deep Insight

    Directory of Open Access Journals (Sweden)

    Jignesh Lunagariya

    2017-07-01

    Full Text Available The non-ionic triblock copolymer, Pluronic® F127, has been selected to observe its interaction with ionic liquids (ILs in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC of F127 increased with the addition of ILs, which appeared logical since it increases the solubility of PPO (and PEO moiety, making it behaves more like a hydrophilic block copolymer that is micellized at a higher copolymer concentration. The results from DLS data showed good agreement with those obtained from the surface tension measurements. Upon the addition of ILs, the tendency in micellar size reduction was demonstrated by viscosity results, and therefore, intrinsic viscosity decreased compared to pure F127 in aqueous solution. The results were discussed as a function of alkyl chain length and anions of imidazolium based ILs.

  7. Identification of planorbids from Venezuela by polymerase chain reaction amplification and restriction fragment length polymorphism of internal transcriber spacer of the RNA ribosomal gene

    Directory of Open Access Journals (Sweden)

    Caldeira Roberta L

    2000-01-01

    Full Text Available Snails of the genus Biomphalaria from Venezuela were subjected to morphological assessment as well as polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP analysis. Morphological identification was carried out by comparison of characters of the shell and the male and female reproductive apparatus. The PCR-RFLP involved amplification of the internal spacer region ITS1 and ITS2 of the RNA ribosomal gene and subsequent digestion of this fragment by the restriction enzymes DdeI, MnlI, HaeIII and MspI. The planorbids were compared with snails of the same species and others reported from Venezuela and present in Brazil, Cuba and Mexico. All the enzymes showed a specific profile for each species, that of DdeI being the clearest. The snails were identified as B. glabrata, B. prona and B. kuhniana.

  8. Effects of PEG tethering chain length of vitamin E TPGS with a Herceptin-functionalized nanoparticle formulation for targeted delivery of anticancer drugs.

    Science.gov (United States)

    Zhao, Jing; Feng, Si-Shen

    2014-03-01

    Drug formulation by ligand conjugated nanoparticles of biodegradable polymers has become one of the most important strategies in drug targeting. We have developed in our previous work nanoparticles of a mixture of two vitamin E TPGS based copolymers PLA-TPGS and TPGS-TOOH with the latter for Herceptin conjugation for targeted delivery of anticancer drugs such as docetaxel to the cancer cells of human epidermal growth factor receptor 2 (HER2) overexpression. In this research, we investigated the effects of the PEG chain length in TPGS, which is in fact a PEGylated vitamin E, on the cellular uptake and cytotoxicity of the drug formulated in the Herceptin-conjugated nanoparticles of PLA-TPGS/TPGS-COOH blend (NPs). Such NPs of PEG1000, PEG2000, PEG3350 and PEG5000, i.e. the PEG of molecule weight 1000, 2000, 3350 and 5000, were prepared by the nanoprecipitation method and characterized for their size and size distribution, drug loading, surface morphology, surface charge and surface chemistry as well as in vitro drug release profile, cellular uptake and cytotoxicity. We found among such nanoparticles, those of PEG1000, i.e. of the shortest PEG tethering chain length, could result in the best therapeutic effects, which are 24.1%, 37.3%, 38.1% more efficient in cellular uptake and 68.1%, 90%, 92.6% lower in IC50 (thus higher in cytotoxicity) than the Herceptin-conjugated nanoparticles of PLA-TPGS/TPGS-COOH blend of PEG2000, PEG3350 and PEG5000 respectively in treatment of SK-BR-3 cancer cells which are of high HER2 overexpression. We provided a theoretical explanation from surface mechanics and thermodynamics for endocytosis of nanoparticles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Crystal structure of heterodimeric hexaprenyl diphosphate synthase from Micrococcus luteus B-P 26 reveals that the small subunit is directly involved in the product chain length regulation.

    Science.gov (United States)

    Sasaki, Daisuke; Fujihashi, Masahiro; Okuyama, Naomi; Kobayashi, Yukiko; Noike, Motoyoshi; Koyama, Tanetoshi; Miki, Kunio

    2011-02-04

    Hexaprenyl diphosphate synthase from Micrococcus luteus B-P 26 (Ml-HexPPs) is a heterooligomeric type trans-prenyltransferase catalyzing consecutive head-to-tail condensations of three molecules of isopentenyl diphosphates (C(5)) on a farnesyl diphosphate (FPP; C(15)) to form an (all-E) hexaprenyl diphosphate (HexPP; C(30)). Ml-HexPPs is known to function as a heterodimer of two different subunits, small and large subunits called HexA and HexB, respectively. Compared with homooligomeric trans-prenyltransferases, the molecular mechanism of heterooligomeric trans-prenyltransferases is not yet clearly understood, particularly with respect to the role of the small subunits lacking the catalytic motifs conserved in most known trans-prenyltransferases. We have determined the crystal structure of Ml-HexPPs both in the substrate-free form and in complex with 7,11-dimethyl-2,6,10-dodecatrien-1-yl diphosphate ammonium salt (3-DesMe-FPP), an analog of FPP. The structure of HexB is composed of mostly antiparallel α-helices joined by connecting loops. Two aspartate-rich motifs (designated the first and second aspartate-rich motifs) and the other characteristic motifs in HexB are located around the diphosphate part of 3-DesMe-FPP. Despite the very low amino acid sequence identity and the distinct polypeptide chain lengths between HexA and HexB, the structure of HexA is quite similar to that of HexB. The aliphatic tail of 3-DesMe-FPP is accommodated in a large hydrophobic cleft starting from HexB and penetrating to the inside of HexA. These structural features suggest that HexB catalyzes the condensation reactions and that HexA is directly involved in the product chain length control in cooperation with HexB.

  10. Allelic sequence variations in the hypervariable region of a T-cell receptor β chain: Correlation with restriction fragment length polymorphism in human families and populations

    International Nuclear Information System (INIS)

    Robinson, M.A.

    1989-01-01

    Direct sequence analysis of the human T-cell antigen receptor (TCR) V β1 variable gene identified a single base-pair allelic variation (C/G) located within the coding region. This change results in substitution of a histidine (CAC) for a glutamine (CAG) at position 48 of the TCR β chain, a position predicted to be in the TCR antigen binding site. The V β1 polymorphism was found by DNA sequence analysis of V β1 genes from seven unrelated individuals; V β1 genes were amplified by the polymerase chain reaction, the amplified fragments were cloned into M13 phage vectors, and sequences were determined. To determined the inheritance patterns of the V β1 substitution and to test correlation with V β1 restriction fragment length polymorphism detected with Pvu II and Taq I, allele-specific oligonucleotides were constructed and used to characterize amplified DNA samples. Seventy unrelated individuals and six families were tested for both restriction fragment length polymorphism and for the V β1 substitution. The correlation was also tested using amplified, size-selected, Pvu II- and Taq I-digested DNA samples from heterozygotes. Pvu II allele 1 (61/70) and Taq I allele 1 (66/70) were found to be correlated with the substitution giving rise to a histidine at position 48. Because there are exceptions to the correlation, the use of specific probes to characterize allelic forms of TCR variable genes will provide important tools for studies of basic TCR genetics and disease associations

  11. Density functional theory study of silodithiophene thiophenepyrrolopyrroledion-based small molecules: The effect of alkyl side chain length in electron donor materials

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dong Kyun; Yeo, Hak; Kwak, Kyung Won [Dept. of Chemistry, Chung-Ang University, Seoul (Korea, Republic of); Yoon, Young Woon; Kim, Bong Soo [Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Lee, Kyung Koo [Dept. of Chemistry, Kunsan National University, Gunsan (Korea, Republic of)

    2015-02-15

    Push–pull small molecules are promising electron-donor materials for organic solar cells. Thus, precise prediction of their electronic structures is of paramount importance to control the optical and electrical properties of the solar cells. Various types of alkyl chains are usually introduced to increase solubility and modify the morphology of the resulting molecular films. Here, using density functional theory (DFT) and time-dependent DFT (TD-DFT), we report the precise effect of increasing the length of the alkyl chain on the electronic structure of an electron donor molecule 6,60-((4,4-dialkyl-4H-silolo[3,2-b:4,5-b′]-dithiophene-2,6-diyl) bis(thiophene-5,2-diyl))bis(2,5-alkyl-3-(thiophen-2-yl) -2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (DTS1TDPP). Alkyl groups were attached to the bridging position (silicon atom) of the fused rings and nitrogen atom of the pyrrolopyrroledione groups. We demonstrate that the alkyl groups do not perturb the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, π-delocalized backbone structure, and UV–Vis absorption spectrum when they are placed at the least steric effect positions.

  12. Preparation, physicochemical characterisation and magnetic properties of Cu-Al layered double hydroxides with CO 32- and anionic surfactants with different alkyl chains in the interlayer

    Science.gov (United States)

    Trujillano, Raquel; Holgado, María Jesús; Pigazo, Fernando; Rives, Vicente

    2006-03-01

    Layered double hydroxides with the hydrotalcite-like structure, containing Cu(II) and Al(III) in the layers, and different alkyl sulphonates in the interlayer, have been prepared and characterised by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Their magnetic properties have been also studied. Except for the sample containing octadecanesulphonate in the interlayer, for which an excess of sulphonate exists, pure crystalline phases have been obtained in the other cases. Upon heating, combustion of the organic chain takes place at lower temperature than for the corresponding sodium salts. A two-dimensional antiferromagnetic behaviour is observed at 200 K in all samples containing intercalated sulphonate. The χT value is lower for the samples containing interlayer sulphonates (with layer-layer distances in the 21-31 Å range), than for a carbonate-containing analogue (basal spacing 7.51 Å).

  13. Roles of head group architecture and side chain length on colorimetric response of polydiacetylene vesicles to temperature, ethanol and pH.

    Science.gov (United States)

    Charoenthai, Nipaphat; Pattanatornchai, Thanutpon; Wacharasindhu, Sumrit; Sukwattanasinitt, Mongkol; Traiphol, Rakchart

    2011-08-15

    In this contribution, we report the relationship between molecular structures of polydiacetylene (PDA) vesicles, fabricated by using three monomers, 10,12-tricosadiynoic acid (TCDA), 10,12-pentacosadiynoic acid (PCDA) and N-(2-aminoethyl)pentacosa-10,12-diynamide (AEPCDA), and their color-transition behaviors. The modification of side chain length and head group of the PDA vesicles strongly affects the colorimetric response to temperature, ethanol and pH. A shorter side chain of poly(TCDA) yields weaker inter- and intra-chain dispersion interactions in the bilayers compared to the system of poly(PCDA), which in turn results in a faster color transition upon exposure to all stimuli. A change of head group in poly(AEPCDA) slightly reduces the transition temperature. Interestingly, the colorimetric response of poly(AEPCDA) vesicles to the addition of ethanol is found to occur in a two-step fashion while the response of poly(PCDA) vesicles takes place in a one-step process. The amount of ethanol required for inducing complete color-transition of poly(AEPCDA) vesicles is also much higher, about 87% v/v. The increase of pH to ~9 and ~10 causes a color-transition of poly(TCDA) and poly(PCDA) vesicles, respectively. The poly(AEPCDA) vesicles, on the other hand, change color upon decreasing pH to ~0. The colorimetric response also occurs in a multi-step fashion. These discrepancies are attributed to the architecture of surface layers of poly(AEPCDA), constituting amine and amide groups separated by ethyl linkers. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Thermosensitive mPEG-b-PA-g-PNIPAM comb block copolymer micelles: effect of hydrophilic chain length and camptothecin release behavior.

    Science.gov (United States)

    Yang, Xiao-Li; Luo, Yan-Ling; Xu, Feng; Chen, Ya-Shao

    2014-02-01

    Block copolymer micelles are extensively used as drug controlled release carriers, showing promising application prospects. The comb or brush copolymers are especially of great interest, whose densely-grafted side chains may be important for tuning the physicochemical properties and conformation in selective solvents, even in vitro drug release. The purpose of this work was to synthesize novel block copolymer combs via atom transfer radical polymerization, to evaluate its physicochemical features in solution, to improve drug release behavior and to enhance the bioavailablity, and to decrease cytotoxicity. The physicochemical properties of the copolymer micelles were examined by modulating the composition and the molecular weights of the building blocks. A dialysis method was used to load hydrophobic camptothecin (CPT), and the CPT release and stability were detected by UV-vis spectroscopy and high-performance liquid chromatography, and the cytotoxicity was evaluated by MTT assays. The copolymers could self-assemble into well-defined spherical core-shell micelle aggregates in aqueous solution, and showed thermo-induced micellization behavior, and the critical micelle concentration was 2.96-27.64 mg L(-1). The micelles were narrow-size-distribution, with hydrodynamic diameters about 128-193 nm, depending on the chain length of methoxy polyethylene glycol (mPEG) blocks and poly(N-isopropylacrylamide) (PNIPAM) graft chains or/and compositional ratios of mPEG to PNIPAM. The copolymer micelles could stably and effectively load CPT but avoid toxicity and side-effects, and exhibited thermo-dependent controlled and targeted drug release behavior. The copolymer micelles were safe, stable and effective, and could potentially be employed as CPT controlled release carriers.

  15. Ultrathin nanofibrous films prepared from cadmium hydroxide nanostrands and anionic surfactants.

    Science.gov (United States)

    Peng, Xinsheng; Karan, Santanu; Ichinose, Izumi

    2009-08-04

    We developed a simple fabrication method of ultrathin nanofibrous films from the dispersion of cadmium hydroxide nanostrands and anionic surfactants. The nanostrands were prepared in a dilute aqueous solution of cadmium chloride by using 2-aminoethanol. They were highly positively charged and gave bundlelike fibers upon mixing an aqueous solution of anionic surfactant. The nanostrand/surfactant composite fibers were filtered on an inorganic membrane filter. The resultant nanofibrous film was very uniform in the area of a few centimeters square when the thickness was not less than 60 nm. The films obtained with sodium tetradecyl sulfate (STS) had a composition close to the electroneutral complex, [Cd37(OH)68(H2O)n] x 6(STS), as confirmed by energy dispersive X-ray analysis. They were water-repellent with a contact angle of 117 degrees, and the value slightly decreased with the alkyl chain length of anionic surfactants. Ultrathin nanofibrous films were stable enough to be used for ultrafiltration at pressure difference of 90 kPa. We could effectively separate Au nanoparticles of 40 nm at an extremely high filtration rate of 14000 L/(h m2 bar).

  16. Use of length heterogeneity polymerase chain reaction (LH-PCR as non-invasive approach for dietary analysis of Svalbard reindeer, Rangifer tarandus platyrhynchus.

    Directory of Open Access Journals (Sweden)

    Sungbae Joo

    Full Text Available To efficiently investigate the forage preference of Svalbard reindeer (Rangifer tarandus platyrhynchus, we applied length-heterogeneity polymerase chain reaction (LH-PCR based on length differences of internal transcribed spacer (ITS regions of ribosomal RNA (rRNA to fecal samples from R. tarandus platyrhynchus. A length-heterogeneity (LH database was constructed using both collected potential food sources of Svalbard reindeer and fecal samples, followed by PCR, cloning and sequencing. In total, eighteen fecal samples were collected between 2011 and 2012 from 2 geographic regions and 15 samples were successfully amplified by PCR. The LH-PCR analysis detected abundant peaks, 18.6 peaks on an average per sample, ranging from 100 to 500 bp in size and showing distinct patterns associated with both regions and years of sample collection. Principal component analysis (PCA resulted in clustering of 15 fecal samples into 3 groups by the year of collection and region with a statistically significant difference at 99.9% level. The first 2 principal components (PCs explained 71.1% of the total variation among the samples. Through comparison with LH database and identification by cloning and sequencing, lichens (Stereocaulon sp. and Ochrolechia sp. and plant species (Salix polaris and Saxifraga oppositifolia were detected as the food sources that contributed most to the Svalbard reindeer diet. Our results suggest that the use of LH-PCR analysis would be a non-invasive and efficient monitoring tool for characterizing the foraging strategy of Svalbard reindeer. Additionally, combining sequence information would increase its resolving power in identification of foraged diet components.

  17. ASSOCIATION OF BRANCHED POLYETHYLENE IMINE WITH SURFACTANTS IN AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    Ismael C. Bellettini

    2015-07-01

    Full Text Available Three polymer-surfactant systems comprised of branched polyethylene imine (PEI with an anionic surfactant (sodium dodecylsulfate; SDS, a cationic surfactant (tetradecyltrimethylammonium bromide; TTAB, and a zwitterionic surfactant (N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate; SB3-14 were studied based on the properties of surface tension, pyrene fluorescence emission, dynamic light scattering, pH, and zeta potential measurements. The critical aggregation concentration (cac and polymer saturation point (psp were determined for all three systems. The effect of these surfactants on the physico-chemical characteristics (diameter and surface charge of the complexes formed was determined. Polymer-surfactant interactions occurred in all of the systems studied, with the strongest interactions, electrostatic in nature, occurring in the SDS-PEI system. After the neutralization of the polymer charges with the addition of the surfactant, the hydrophobic effect started to control the interlacing of the polymer chains. For the PEI-TTAB system, a very dense film was formed at surfactant concentrations above 2.0 mmol L-1. In this case, the bromide counter-ion interacted with both the positively-charged PEI and the head of the surfactant, which is responsible for the formation of double layer coordination complexes. For the system composed of PEI and the zwitterionic surfactant, less cooperative associations occurred in comparison with the other systems.

  18. Synthesis and Surface Activity of Cationic Amino Acid-Based Surfactants in Aqueous Solution.

    Science.gov (United States)

    Greber, Katarzyna E

    2017-01-01

    I studied the possibility of using amino acid-based surfactants as emulsifiers at the same time as preservatives. Fourteen lipopeptides were synthesized employing a solid phase peptide synthesis procedure. All compounds were designed to be positively charged from +1 to +4 and acylated with fatty acid chain-palmitic and miristic. The surface activity of the obtained lipopeptides was tested using a semi-automatic tensiometer to calculate parameters describing the behavior of lipopeptides in the air/water interface. Such parameters as CMC, surface tension at the CMC point ( σ CMC ), effectiveness ( π CMC ), and efficiency (pC20) were measured. Emulsifying properties of all lipopeptides were also examined. The studies reveal that the surface active properties of synthesized compounds strongly depend on the length of alkyl chains as well as on the composition of amino acid polar heads. The critical micelle concentration decreases with increasing alkyl chain length of lipopeptides with the same polar head. The effectiveness and efficiency decrease when the number of amino acids in the polar head increases. All lipopeptides established a very weak emulsification power and created unstable water/Miglyol 812 and water/paraffin oil emulsions. Results suggest that lipopeptides cannot be used as emulsifiers; nonetheless, it is possible to use them as auxiliary surfactants with disinfectant properties in combination with more potent emulsifiers.

  19. Surfactants in tribology

    CERN Document Server

    Biresaw, Girma

    2014-01-01

    Surface science and tribology play very critical roles in many industries. Manufacture and use of almost all consumer and industrial products rely on the application of advanced surface and tribological knowledge. The fourth in a series, Surfactants in Tribology, Volume 4 provides an update on research and development activities connecting surfactants and tribological phenomena. Written by renowned subject matter experts, the book demonstrates how improved design of surfactants can be harnessed to control tribological phenomena. Profusely illustrated and copiously referenced, the chapters also

  20. Genotyping of major histocompatibility complex Class II DRB gene in Rohilkhandi goats by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing

    Directory of Open Access Journals (Sweden)

    Kush Shrivastava

    2015-10-01

    Full Text Available Aim: To study the major histocompatibility complex (MHC Class II DRB1 gene polymorphism in Rohilkhandi goat using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP and nucleotide sequencing techniques. Materials and Methods: DNA was isolated from 127 Rohilkhandi goats maintained at sheep and goat farm, Indian Veterinary Research Institute, Izatnagar, Bareilly. A 284 bp fragment of exon 2 of DRB1 gene was amplified and digested using BsaI and TaqI restriction enzymes. Population genetic parameters were calculated using Popgene v 1.32 and SAS 9.0. The genotypes were then sequenced using Sanger dideoxy chain termination method and were compared with related breeds/species using MEGA 6.0 and Megalign (DNASTAR software. Results: TaqI locus showed three and BsaI locus showed two genotypes. Both the loci were found to be in Hardy–Weinberg equilibrium (HWE, however, population genetic parameters suggest that heterozygosity is still maintained in the population at both loci. Percent diversity and divergence matrix, as well as phylogenetic analysis revealed that the MHC Class II DRB1 gene of Rohilkhandi goats was found to be in close cluster with Garole and Scottish blackface sheep breeds as compared to other goat breeds included in the sequence comparison. Conclusion: The PCR-RFLP patterns showed population to be in HWE and absence of one genotype at one locus (BsaI, both the loci showed excess of one or the other homozygote genotype, however, effective number of alleles showed that allelic diversity is present in the population. Sequence comparison of DRB1 gene of Rohilkhandi goat with other sheep and goat breed assigned Rohilkhandi goat in divergence with Jamanupari and Angora goats.

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

    Science.gov (United States)

    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.

  2. Asymmetric Conjugated Molecules Based on [1]Benzothieno[3,2-b][1]benzothiophene for High-Mobility Organic Thin-Film Transistors: Influence of Alkyl Chain Length.

    Science.gov (United States)

    He, Keqiang; Li, Weili; Tian, Hongkun; Zhang, Jidong; Yan, Donghang; Geng, Yanhou; Wang, Fosong

    2017-10-11

    Herein, we report the synthesis and characterization of a series of [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based asymmetric conjugated molecules, that is, 2-(5-alkylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-Tn, in which T and n represent thiophene and the number of carbons in the alkyl group, respectively). All of the molecules with n ≥ 4 show mesomorphism and display smectic A, smectic B (n = 4), or smectic E (n > 4) phases and then crystalline phases in succession upon cooling from the isotropic state. Alkyl chain length has a noticeable influence on the microstructures of vacuum-deposited films and therefore on the performance of the organic thin-film transistors (OTFTs). All molecules except for 2-(thiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-ethylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene showed OTFT mobilities above 5 cm 2 V -1 s -1 . 2-(5-Hexylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-heptylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene showed the greatest OTFT performance with reliable hole mobilities (μ) up to 10.5 cm 2 V -1 s -1 because they formed highly ordered and homogeneous films with diminished grain boundaries.

  3. Identification of Pork Contamination in Meatballs of Indonesia Local Market Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP Analysis

    Directory of Open Access Journals (Sweden)

    Yuny Erwanto

    2014-10-01

    Full Text Available This research applied and evaluated a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP using cytochrome b gene to detect pork contamination in meatballs from local markets in Surabaya and Yogyakarta regions, Indonesia. To confirm the effectiveness and specificity of this fragment, thirty nine DNA samples from different meatball shops were isolated and amplified, and then the PCR amplicon was digested by BseDI restriction enzyme to detect the presence of pork in meatballs. BseDI restriction enzyme was able to cleave porcine cytochrome b gene into two fragments (131 bp and 228 bp. Testing the meatballs from the local market showed that nine of twenty meatball shops in Yogyakarta region were detected to have pork contamination, but there was no pork contamination in meatball shops in Surabaya region. In conclusion, specific PCR amplification of cytochrome b gen and cleaved by BseDI restriction enzymes seems to be a powerful technique for the identification of pork presence in meatball because of its simplicity, specificity and sensitivity. Furthermore, pork contamination intended for commercial products of sausage, nugget, steak and meat burger can be checked. The procedure is also much cheaper than other methods based on PCR, immunodiffusion and other techniques that need expensive equipment.

  4. Identification of Pork Contamination in Meatballs of Indonesia Local Market Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) Analysis.

    Science.gov (United States)

    Erwanto, Yuny; Abidin, Mohammad Zainal; Sugiyono, Eko Yasin Prasetyo Muslim; Rohman, Abdul

    2014-10-01

    This research applied and evaluated a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using cytochrome b gene to detect pork contamination in meatballs from local markets in Surabaya and Yogyakarta regions, Indonesia. To confirm the effectiveness and specificity of this fragment, thirty nine DNA samples from different meatball shops were isolated and amplified, and then the PCR amplicon was digested by BseDI restriction enzyme to detect the presence of pork in meatballs. BseDI restriction enzyme was able to cleave porcine cytochrome b gene into two fragments (131 bp and 228 bp). Testing the meatballs from the local market showed that nine of twenty meatball shops in Yogyakarta region were detected to have pork contamination, but there was no pork contamination in meatball shops in Surabaya region. In conclusion, specific PCR amplification of cytochrome b gen and cleaved by BseDI restriction enzymes seems to be a powerful technique for the identification of pork presence in meatball because of its simplicity, specificity and sensitivity. Furthermore, pork contamination intended for commercial products of sausage, nugget, steak and meat burger can be checked. The procedure is also much cheaper than other methods based on PCR, immunodiffusion and other techniques that need expensive equipment.

  5. Production of Medium-Chain-Length Poly(3-Hydroxyalkanoates from Saponified Palm Kernel Oil by Pseudomonas putida: Kinetics of Batch and Fed-Batch Fermentations

    Directory of Open Access Journals (Sweden)

    Annuar, M. S. M.

    2006-01-01

    Full Text Available The kinetics of medium-chain-length poly(3-hydroxyalkanoates, PHAMCL production by Pseudomonas putida PGA1 in batch and fed-batch fermentations were studied. With saponified palm kernel oil (SPKO supplying the free fatty acids mixture as the sole carbon and energy source, PHAMCL accumulation is encouraged under ammonium-limited condition, which is a nitrogen stress environment. The amount of PHAMCL accumulated and its specific production rate, qPHA were influenced by the residual ammonium concentration level in the culture medium. It was observed that in both fermentation modes, when the residual ammonium was exhausted (< 0.05 gL-1, the PHAMCL accumulation (11.9% and qPHA (0.0062 h-1 were significantly reduced. However, this effect can be reversed by feeding low amount of ammonium to the culture, resulting in significantly improved PHAMCL yield (71.4% and specific productivity (0.6 h-1. It is concluded that the feeding of low ammonium concentration to the culture medium during the PHAMCL accumulation has a positive effect on sustaining the PHAMCL biosynthetic capability of the organism. It was also found that increasing SPKO concentration in the medium significantly reduced (up to 50% the volumetric oxygen transfer coefficient (KLa of the fermentation system.

  6. Molecular identification of Candida species isolated from cases of neonatal candidemia using polymerase chain reaction-restriction fragment length polymorphism in a tertiary care hospital

    Directory of Open Access Journals (Sweden)

    Akeela Fatima

    2017-01-01

    Full Text Available Context: Candida spp. is an emerging cause of bloodstream infections worldwide. Delay in speciation of Candida isolates by conventional methods and resistance to antifungal drugs in various Candida species are responsible for the increase in morbidity and mortality due to candidemia. Hence, the rapid identification of Candida isolates is very important for the proper management of patients with candidemia. Aims: The aim was to re-evaluate the identification of various Candida spp. by polymerase chain reaction (PCR-restriction fragment length polymorphism (RFLP and to evaluate the accuracy, speed, and cost of phenotypic methodology versus PCR-RFLP. Settings and Design: Hospital-based cross-sectional study. Materials and Methods: Ninety consecutive clinical isolates of seven Candida species, isolated from blood of neonates and identified by routine phenotypic methods, were re-evaluated using universal primers internal transcribed spacer 1 (ITS1 and ITS4 for PCR amplification and Msp I restriction enzyme for RFLP. Statistical Analysis Used: Kappa test for agreement. Results: The results of PCR-RFLP were 100% in agreement with those obtained using conventional phenotypic methods. Identification could be achieved within 3 work days by both the methods. Our routine methods proved to be cost effective than PCR-RFLP. Conclusions: We can continue with our routine phenotypic methods and PCR-RFLP can be used for periodic quality control or when conventional methods fail to identify a species.

  7. Molecular identification of similar species of the genus Biomphalaria (Mollusca: Planorbidae determined by a polymerase chain reaction-restriction fragment length polymorphism

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    Caldeira Roberta Lima

    1998-01-01

    Full Text Available The freshwater snails Biomphalaria straminea, B. intermedia, B. kuhniana and B. peregrina, are morphologically similar; based on this similarity the first three species were therefore grouped in the complex B. straminea. The morphological identification of these species is based on characters such as vaginal wrinkling, relation between prepuce: penial sheath:deferens vas and number of muscle layers in the penis wall. In this study the polymerase chain reaction restriction fragment length polymorphism technique was used for molecular identification of these molluscs. This technique is based on the amplification of the internal transcribed spacer regions ITS1 e ITS2 of the ribosomal RNA gene and subsequent digestion of these fragments by restriction enzymes. Six enzymes were tested: Dde I, Mnl I, Hae III, Rsa I, Hpa II e Alu I. The restriction patterns obtained with DdeI presented the best profile for separation of the four species of Biomphalaria. The profiles obtained with all the enzymes were used to estimate the genetic distances among the species through analysis of common banding patterns.

  8. The color tuning of PS-b-P2VP lamellar films with changing the alkyl chain length of 1-iodoalkanes.

    Science.gov (United States)

    Shin, Sung-Eui; Kim, Su-Young; Shin, Dong-Myung

    2011-05-01

    Photonic crystals with tunability in the visible or near-infrared region have drawn increasing attention for controlling and processing light for the active components of future display. We prepared polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer of 57 kg/mol-b-57 kg/mol. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic moiety of PS-b-P2VP, are obtained by exposing the spin coated film under chloroform vapor. The band gaps of the lamellar films interestingly varied after immersion into the quaternizing solvents containing 5 wt% of iodomethane, iodoethane, 1-iodobutane, 1-iodopentane, 1-iodohexane and 1-iodooctane solubilized in n-hexane. The iodoalkanes reacted with pyridine groups in PS-b-P2VP and generated the alkyl pyridinium salts readily. The degree of quaternization, alkyl chain length of iodoalkane and the salt water concentration affects the spacing of layer structure of PS-b-P2VP. The iodomethane and iodohexane produced similar band gaps and salt concentration dependence. These results are very much dependent on the hydrophobic-hydrophilic characters of PS-b-P2VP lamellar surface.

  9. The prevalence of cryptosporidiosis in Turkish children, and geno typing of isolates by nested polymerase chain reaction-restriction fragment length polymorphism

    International Nuclear Information System (INIS)

    Tamer, Gulden S.; Turk, M.; Dagci, H.; Pektas, B.; Guruz, Adnan Y.; Uner, A.; Guy, E.C.

    2007-01-01

    Objective was to verify the incidence of cryptosporidiosis among Turkish elementary school students. The study was conducted in the Dept. of Parasitology, Faculty of Medicine, Ege University, Turkey during a 3-month period in 2006. We assessed the fecal samples of 707 children using modified acid-fast and phenol-auramine staining followed by modified Ritchie concentration method. All cryptosporidium species isolates were analysed by nested polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) to differentiate genotypes of the isolates. After the coprological examination, 4 samples were found to be positive for cryptosporidium species oocysts. In the present study, all 4 oocysts were of zoonotic origin and belonged to cryptoporodium parvum genotype 2 indicating that in Turkey the potential sources of human cryptosporidiosis is from animals. The application of genotyping to clinical isolates of cryptosporidium has significantly increased our knowledge and understanding of the distribution and epidemiology of this parasite. The PCR and RFLP techniques represent a more rapid and simple method of genotyping to support epidemiological and clinical investigations than conventional analytical DNA techniques. (author)

  10. Quinoidal Oligo(9,10-anthryl)s with Chain-Length-Dependent Ground States: A Balance between Aromatic Stabilization and Steric Strain Release

    KAUST Repository

    Lim, Zhenglong

    2015-11-12

    Quinoidal π-conjugated polycyclic hydrocarbons have attracted intensive research interest due to their unique optical/electronic properties and possible magnetic activity, which arises from a thermally excited triplet state. However, there is still lack of fundamental understanding on the factors that determine the electronic ground states. Herein, by using quinoidal oligo(9,10-anthryl)s, it is demonstrated that both aromatic stabilisation and steric strain release play balanced roles in determining the ground states. Oligomers with up to four anthryl units were synthesised and their ground states were investigated by electronic absorption and electron spin resonance (ESR) spectroscopy, assisted by density functional theory (DFT) calculations. The quinoidal 9,10-anthryl dimer 1 has a closed-shell ground state, whereas the tri- (2) and tetramers (3) both have an open-shell diradical ground state with a small singlet-triplet gap. Such a difference results from competition between two driving forces: the large steric repulsion between the anthryl/phenyl units in the closed-shell quinoidal form that drives the molecule to a flexible open-shell diradical structure, and aromatic stabilisation due to the gain of more aromatic sextet rings in the closed-shell form, which drives the molecule towards a contorted quinoidal structure. The ground states of these oligomers thus depend on the overall balance between these two driving forces and show chain-length dependence. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The normal chain length distribution of the O antigen is required for the interaction of Shigella flexneri 2a with polarized Caco-2 cells

    Directory of Open Access Journals (Sweden)

    Anilei Hoare

    2012-01-01

    Full Text Available Shigella flexneri causes bacillary dysentery in humans. Essential to the establishment of the disease is the invasion of the colonic epithelial cells. Here we investigated the role of the lipopolysaccharide (LPS O antigen in the ability of S. flexneri to adhere to and invade polarized Caco-2 cells. The S. flexneri 2a O antigen has two preferred chain lengths: a short O antigen (S-OAg regulated by the WzzB protein and a very long O antigen (VL-OAg regulated by Wzz pHS2. Mutants with defined deletions of the genes required for O-antigen assembly and polymerization were constructed and assayed for their abilities to adhere to and enter cultured epithelial cells. The results show that both VL- and S-OAg are required for invasion through the basolateral cell membrane. In contrast, the absence of O antigen does not impair adhesion. Purified LPS does not act as a competitor for the invasion of Caco-2 cells by the wild-type strain, suggesting that LPS is not directly involved in the internalization process by epithelial cells.

  12. Diffusional behavior of n-paraffins with various chain lengths in urea adduct channels by pulsed field-gradient spin-echo NMR spectroscopy

    International Nuclear Information System (INIS)

    Kim, Sunmi; Kuroki, Shigeki; Ando, Isao

    2006-01-01

    The diffusion coefficients (D) of n-paraffin molecules (n-C n H 2n+2 ) with various chain-lengths (n = 8, 12, 21, 26, 28 and 32) in the long channels of a deuterated urea-d 4 adduct have been measured at 25 deg. C by means of pulsed field-gradient spin-echo 1 H NMR method. The aim is to clarify diffusional behavior of the n-paraffin molecules in the urea adduct channels. From the experimental results, it is found that n-paraffin molecules are diffusing in the long channels and have two kinds of diffusion components, namely a fast (D ∼ 10 -10 m 2 /s) and a slow diffusion component (D ∼ 10 -11 m 2 /s). The diffusing-time (Δ) dependence of the diffusion coefficients of the n-paraffins shows some likely evidence of restricted diffusion since the n-paraffin molecules are confined in the urea channel. The diffusion coefficients (D) decrease as the carbon number increases from 8 to 28, and very slowly decreases as the carbon number increases from 28 to 32

  13. Simultaneous and rapid differential diagnosis of Mycoplasma genitalium and Ureaplasma urealyticum based on a polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    R Mirnejad

    2011-01-01

    Full Text Available Objectives: The aim of this investigation was to simultaneously detect and differentiate Mycoplasma genitalium and Ureaplasma urealyticum in female patients suffering from genital complications by polymerase chain reaction (PCR-restriction fragment length polymorphism (RFLP. Materials and Methods : Genital swabs were taken from 210 patients. They were transported to the laboratory in phosphate-buffered saline. For PCR, samples were analysed with genus-specific MyUu-R and MyUu-F primers. This primer set, which was originally designed in our laboratory, amplified a 465 bp fragment (M. genitalium and a 559 bp fragment (U. urealyticum. Samples containing a band of the expected sizes for the Mycoplasma strains were subjected to digestion with a restriction endonuclease enzyme of TaqI and Cac8I. Results: Of the 210 samples, a total of 100 (47.6% samples were found to be positive for Mycoplasmas (seven M. genitalium isolates, 3.3%; and 89 U. urealyticum isolates, 42.4%, and coinfections with both species were detected in four samples (1.9%. The PCR-RFLP results showed that M. genitalium and U. urealyticum are different by enzyme patterns. Conclusion: PCR-RFLP offers a rapid and easily applicable protocol to simultaneous detection and differentiation of M. genitalium and U. urealyticum from clinical samples when specific primers and restriction enzymes are used.

  14. Dynamic covalent surfactants

    NARCIS (Netherlands)

    Minkenberg, C.B.

    2012-01-01

    In this thesis the development of surfactant aggregates with fast exchange dynamics between the aggregated and non-aggregated state is described. Dynamic surfactant exchange plays an important role in natural systems, for instance in cell signaling, cell division, and uptake and release of cargo.

  15. Effect of alkyl chain length of imidazolium cations on the electron transport and recombination kinetics in ionic gel electrolytes based quasi-solid-state dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Huo, Zhipeng; Tao, Li; Wang, Lu; Zhu, Jun; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan; Zhang, Bing

    2015-01-01

    Highlights: •A series of novel IGEs based on 12-hydroxystearicacid as LMOG were prepared. •The QS-DSSCs exhibit excellent stability during the accelerated aging tests. •The influence of Im + alkyl chain length on the electron kinetic process is investigated. -- Abstract: A series of stable quasi-solid-state dye-sensitized solar cells (QS-DSSCs) are prepared by the 12-hydroxystearicacid as low molecular mass organogelator (LMOG) to gelate the ionic liquid with different alkyl chain lengths (3, 4, and 7). The influence of alkyl chain length of imidazolium cations (Im + ) on the kinetic processes of electron transport and recombination are investigated by Electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy/intensity-modulated photovoltage spectroscopy (IMPS/IMVS). It is found that the ionic gel electrolytes (IGEs) with different alkyl chain lengths of Im + can influence the competitive adsorption effects of imidazolium cations (Im + ) and Li + , and further affect the charge diffusion, the electron recombination/transport processes, the shift of TiO 2 conduction band edge and surface states distribution. The IGE with longer alkyl chain length of Im + can prolong the electron recombination lifetime, promote the incidental photon-to-electron conversion efficiency (IPCE) and the short circuit photocurrent density (J sc ). An excellent QS-DSSC based on the IGE with the longer alkyl chain of Im + gives the highest photoelectric conversion efficiency. Moreover, all the QS-DSSCs based on IGEs exhibit excellent durability without losing their photovoltaic performances during the accelerated thermal and light–soaking test. These results are very important to the researches on the electrochemical mechanism and application of QS-DSSCs based on IGEs

  16. (99m)Tc-labeled gastrins of varying peptide chain length: Distinct impact of NEP/ACE-inhibition on stability and tumor uptake in mice.

    Science.gov (United States)

    Kaloudi, Aikaterini; Nock, Berthold A; Lymperis, Emmanouil; Krenning, Eric P; de Jong, Marion; Maina, Theodosia

    2016-06-01

    In situ inhibition of neutral endopeptidase (NEP) has been recently shown to impressively increase the bioavailability and tumor uptake of biodegradable gastrin radioligands. Furthermore, angiotensin converting enzyme (ACE) has been previously shown to cleave gastrin analogs in vitro. In the present study, we have assessed the effects induced by single or dual NEP/ACE-inhibition on the pharmacokinetic profile of three (99m)Tc-labeled gastrins of varying peptide chain length: [(99m)Tc]SG6 ([(99m)Tc-N4-Gln(1)]gastrin(1-17)), [(99m)Tc]DG2 ([(99m)Tc-N4-Gly(4),DGlu(5)]gastrin(4-17)) and [(99m)Tc]DG4 ([(99m)Tc-N4-DGlu(10)]gastrin(10-17)). Mouse blood samples were collected 5min after injection of each of [(99m)Tc]SG6/DG2/DG4 together with: a) vehicle, b) the NEP-inhibitor phosphoramidon (PA), c) the ACE-inhibitor lisinopril (Lis), or d) PA plus Lis and were analyzed by RP-HPLC for radiometabolite detection. Biodistribution was studied in SCID mice bearing A431-CCK2R(+/-) xenografts at 4h postinjection (pi). [(99m)Tc]SG6 or [(99m)Tc]DG4 was coinjected with either vehicle or the above described NEP/ACE-inhibitor regimens; for [(99m)Tc]DG2 control and PA animal groups were only included. Treatment of mice with PA induced significant stabilization of (99m)Tc-radiotracers in peripheral blood, while treatment with Lis or Lis+PA affected the stability of des(Glu)5 [(99m)Tc]DG4 only. In line with these findings, PA coinjection led to notable amplification of tumor uptake of radiopeptides compared to controls (PTc]DG4 profited by single Lis (2.06±0.39%ID/g vs 0.99±0.13%ID/g in controls) or combined Lis+PA coinjection (8.91±1.61%ID/g vs 4.89±1.33%ID/g in PA-group). Furthermore, kidney uptake remained favourably low and unaffected by PA and/or Lis coinjection only in the case of [(99m)Tc]DG4 (Tc-radioligands based on different-length gastrins. Truncated [(99m)Tc]DG4 exhibited overall the most attractive profile during combined NEP/ACE-inhibition in mouse models, providing new

  17. Soil pretreatment and fast cell lysis for direct polymerase chain reaction from forest soils for terminal restriction fragment length polymorphism analysis of fungal communities

    Directory of Open Access Journals (Sweden)

    Fei Cheng

    Full Text Available Abstract Humic substances in soil DNA samples can influence the assessment of microbial diversity and community composition. Using multiple steps during or after cell lysis adds expenses, is time-consuming, and causes DNA loss. A pretreatment of soil samples and a single step DNA extraction may improve experimental results. In order to optimize a protocol for obtaining high purity DNA from soil microbiota, five prewashing agents were compared in terms of their efficiency and effectiveness in removing soil contaminants. Residual contaminants were precipitated by adding 0.6 mL of 0.5 M CaCl2. Four cell lysis methods were applied to test their compatibility with the pretreatment (prewashing + Ca2+ flocculation and to ultimately identify the optimal cell lysis method for analyzing fungal communities in forest soils. The results showed that pretreatment with TNP + Triton X-100 + skim milk (100 mM Tris, 100 mM Na4P2O7, 1% polyvinylpyrrolidone, 100 mM NaCl, 0.05% Triton X-100, 4% skim milk, pH 10.0 removed most soil humic contaminants. When the pretreatment was combined with Ca2+ flocculation, the purity of all soil DNA samples was further improved. DNA samples obtained by the fast glass bead-beating method (MethodFGB had the highest purity. The resulting DNA was successfully used, without further purification steps, as a template for polymerase chain reaction targeting fungal internal transcribed spacer regions. The results obtained by terminal restriction fragment length polymorphism analysis indicated that the MethodFGB revealed greater fungal diversity and more distinctive community structure compared with the other methods tested. Our study provides a protocol for fungal cell lysis in soil, which is fast, convenient, and effective for analyzing fungal communities in forest soils.

  18. Production of medium-chain-length polyhydroxyalkanoates by sequential feeding of xylose and octanoic acid in engineered Pseudomonas putida KT2440

    Directory of Open Access Journals (Sweden)

    Le Meur Sylvaine

    2012-08-01

    Full Text Available Abstract Background Pseudomonas putida KT2440 is able to synthesize large amounts of medium-chain-length polyhydroxyalkanoates (mcl-PHAs. To reduce the substrate cost, which represents nearly 50% of the total PHA production cost, xylose, a hemicellulose derivate, was tested as the growth carbon source in an engineered P. putida KT2440 strain. Results The genes encoding xylose isomerase (XylA and xylulokinase (XylB from Escherichia coli W3110 were introduced into P. putida KT2440. The recombinant KT2440 exhibited a XylA activity of 1.47 U and a XylB activity of 0.97 U when grown on a defined medium supplemented with xylose. The cells reached a maximum specific growth rate of 0.24 h-1 and a final cell dry weight (CDW of 2.5 g L-1 with a maximal yield of 0.5 g CDW g-1 xylose. Since no mcl-PHA was accumulated from xylose, mcl-PHA production can be controlled by the addition of fatty acids leading to tailor-made PHA compositions. Sequential feeding strategy was applied using xylose as the growth substrate and octanoic acid as the precursor for mcl-PHA production. In this way, up to 20% w w-1 of mcl-PHA was obtained. A yield of 0.37 g mcl-PHA per g octanoic acid was achieved under the employed conditions. Conclusions Sequential feeding of relatively cheap carbohydrates and expensive fatty acids is a practical way to achieve more cost-effective mcl-PHA production. This study is the first reported attempt to produce mcl-PHA by using xylose as the growth substrate. Further process optimizations to achieve higher cell density and higher productivity of mcl-PHA should be investigated. These scientific exercises will undoubtedly contribute to the economic feasibility of mcl-PHA production from renewable feedstock.

  19. Transcriptome analysis of Pseudomonas mediterranea and P. corrugata plant pathogens during accumulation of medium-chain-length PHAs by glycerol bioconversion.

    Science.gov (United States)

    Licciardello, Grazia; Ferraro, Rosario; Russo, Marcella; Strozzi, Francesco; Catara, Antonino F; Bella, Patrizia; Catara, Vittoria

    2017-07-25

    Pseudomonas corrugata and P. mediterranea are soil inhabitant bacteria, generally living as endophytes on symptomless plants and bare soil, but also capable of causing plant diseases. They share a similar genome size and a high proteome similarity. P. corrugata produces many biomolecules which play an important role in bacterial cell survival and fitness. Both species produce different medium-chain-length PHAs (mcl-PHAs) from the bioconversion of glycerol to a transparent film in P. mediterranea and a sticky elastomer in P. corrugata. In this work, using RNA-seq we investigated the transcriptional profiles of both bacteria at the early stationary growth phase with glycerol as the carbon source. Quantitative analysis of P. mediterranea transcripts versus P. corrugata revealed that 1756 genes were differentially expressed. A total of 175 genes were significantly upregulated in P. mediterranea, while 217 were downregulated. The largest group of upregulated genes was related to transport systems and stress response, energy and central metabolism, and carbon metabolism. Expression levels of most genes coding for enzymes related to PHA biosynthesis and central metabolic pathways showed no differences or only slight variations in pyruvate metabolism. The most relevant result was the significantly increased expression in P. mediterranea of genes involved in alginate production, an important exopolysaccharide, which in other Pseudomonas spp. plays a key role as a virulence factor or in stress tolerance and shows many industrial applications. In conclusion, the results provide useful information on the co-production of mcl-PHAs and alginate from glycerol as carbon source by P. mediterranea in the design of new strategies of genetic regulation to improve the yield of bioproducts or bacterial fitness. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yapei; Pitet, Louis M.; Finlay, John A.; Brewer, Lenora H.; Cone, Gemma; Betts, Douglas E.; Callow, Maureen E.; Callow, James A.; Wendt, Dean E.; Hillmyer, Marc A.; DeSimone, Joseph M. (Birmingham UK); (NCSU); (UNC); (Cal. Polytech.); (UMM)

    2013-03-07

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M{sub w} = 1500 g mol{sup -1}) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M{sub w} = 300, 475, 1100 g mol{sup -1}), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  1. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings.

    Science.gov (United States)

    Wang, Yapei; Pitet, Louis M; Finlay, John A; Brewer, Lenora H; Cone, Gemma; Betts, Douglas E; Callow, Maureen E; Callow, James A; Wendt, Dean E; Hillmyer, Marc A; DeSimonea, Joseph M

    2011-01-01

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M(w) = 1500 g mol(-1)) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M(w) = 300, 475, 1100 g mol(-1)), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  2. Effect of molecular chain length on the mechanical and thermal properties of amine-functionalized graphene oxide/polyimide composite films prepared by in situ polymerization.

    Science.gov (United States)

    Liao, Wei-Hao; Yang, Shin-Yi; Wang, Jen-Yu; Tien, Hsi-Wen; Hsiao, Sheng-Tsung; Wang, Yu-Sheng; Li, Shin-Ming; Ma, Chen-Chi M; Wu, Yi-Fang

    2013-02-01

    This study fabricates amine (NH(2))-functionalized graphene oxide (GO)/polyimide(PI) composite films with high performance using in situ polymerization. Linear poly(oxyalkylene)amines with two different molecular weights 400 and 2000 (D400 and D2000) have been grafted onto the GO surfaces, forming two types of NH(2)-functionalized GO (D400-GO/D2000-GO). NH(2)-functionalized GO, especially D400-GO, demonstrated better reinforcing efficiency in mechanical and thermal properties. The observed property enhancement are due to large aspect ratio of GO sheets, the uniform dispersion of the GO within the PI matrix, and strong interfacial adhesion due to the chemical bonding between GO and the polymeric matrix. The Young's modulus of the composite films with 0.3 wt % D400-GO loading is 7.4 times greater than that of neat PI, and tensile strength is 240% higher than that of neat PI. Compared to neat PI, 0.3 wt % D400-GO/PI film exhibits approximately 23.96 °C increase in glass transition temperature (T(g)). The coefficient of thermal expansion below T(g) is significantly decreased from 102.6 μm/°C (neat PI) to 53.81 μm/°C (decreasing 48%) for the D400-GO/PI composites with low D400-GO content (0.1 wt %). This work not only provides a method to develop the GO-based polyimide composites with superior performances but also conceptually provides a chance to modulate the interfacial interaction between GO and the polymer through designing the chain length of grafting molecules on NH(2)-functionalized GO.

  3. Pulmonary surfactant and lung transplantation

    NARCIS (Netherlands)

    Erasmus, Michiel Elardus

    1997-01-01

    Pulmonary surfactant lowers the surface tension at the air-water interface inside the alveolus. This is achieved by adsorption of surfactant phospholipids at the air-water interface, a process controlled by surfactant-associated proteins, such as SP-A. In this way, surfactant prevents collapse of

  4. Novel phytoceramides containing fatty acids of diverse chain lengths are better than a single C18-ceramide N-stearoyl phytosphingosine to improve the physiological properties of human stratum corneum

    Directory of Open Access Journals (Sweden)

    Oh MJ

    2017-09-01

    Full Text Available Myoung Jin Oh,1 Young Hoon Cho,1 So Yoon Cha,1 Eun Ok Lee,2 Jin Wook Kim,2 Sun Ki Kim,2 Chang Seo Park1 1Department of Chemical and Biochemical Engineering, Dongguk University, Chung-gu, Seoul, 2LCS Biotech, Gwonseon-gu, Suwon-si, Gyeonggi-do, Republic of Korea Abstract: Ceramides in the human stratum corneum (SC are a mixture of diverse N-acylated fatty acids (FAs with different chain lengths. C24 is the major class of FAs of ceramides. However, there are also other classes of ceramides with diverse chain lengths of FAs, and these lengths generally range from C16 to C26. This study aimed to prepare several types of phytoceramide containing diverse chain lengths of N-acylated FAs and compare them with C18-ceramide N-stearoyl phytosphingosine (NP in terms of their effects on the physiological properties of the SC. We chose natural oils, such as horse fat oil, shea butter, sunflower oil, and a mixture of macadamia nut, shea butter, moringa, and meadowfoam seed oil, as sources of FAs and phytosphingosine as a sphingoid backbone to synthesize diverse phytoceramides. Each phytoceramide exhibited a distinctive formation of the lamellar structure, and their FA profiles were similar to those of their respective natural oil. The skin barrier properties, as analyzed in human skin, clearly demonstrated that all the phytoceramides improved the recovery rate of the damaged SC and enhanced hydration better than C18-ceramide NP did. In conclusion, natural oil-derived phytoceramides could represent a novel class of ceramides for cosmetic applications in the development of an ideal skin barrier moisturizer. Keywords: fatty acid, chain length, phytoceramide, skin barrier, natural oil

  5. A reduction in growth rate of Pseudomonas putida KT2442 counteracts productivity advances in medium-chain-length polyhydroxyalkanoate production from gluconate

    Directory of Open Access Journals (Sweden)

    Zinn Manfred

    2011-04-01

    Full Text Available Abstract Background The substitution of plastics based on fossil raw material by biodegradable plastics produced from renewable resources is of crucial importance in a context of oil scarcity and overflowing plastic landfills. One of the most promising organisms for the manufacturing of medium-chain-length polyhydroxyalkanoates (mcl-PHA is Pseudomonas putida KT2440 which can accumulate large amounts of polymer from cheap substrates such as glucose. Current research focuses on enhancing the strain production capacity and synthesizing polymers with novel material properties. Many of the corresponding protocols for strain engineering rely on the rifampicin-resistant variant, P. putida KT2442. However, it remains unclear whether these two strains can be treated as equivalent in terms of mcl-PHA production, as the underlying antibiotic resistance mechanism involves a modification in the RNA polymerase and thus has ample potential for interfering with global transcription. Results To assess PHA production in P. putida KT2440 and KT2442, we characterized the growth and PHA accumulation on three categories of substrate: PHA-related (octanoate, PHA-unrelated (gluconate and poor PHA substrate (citrate. The strains showed clear differences of growth rate on gluconate and citrate (reduction for KT2442 > 3-fold and > 1.5-fold, respectively but not on octanoate. In addition, P. putida KT2442 PHA-free biomass significantly decreased after nitrogen depletion on gluconate. In an attempt to narrow down the range of possible reasons for this different behavior, the uptake of gluconate and extracellular release of the oxidized product 2-ketogluconate were measured. The results suggested that the reason has to be an inefficient transport or metabolization of 2-ketogluconate while an alteration of gluconate uptake and conversion to 2-ketogluconate could be excluded. Conclusions The study illustrates that the recruitment of a pleiotropic mutation, whose effects might

  6. Comparative analysis of human cytomegalovirus a-sequence in multiple clinical isolates by using polymerase chain reaction and restriction fragment length polymorphism assays.

    Science.gov (United States)

    Zaia, J A; Gallez-Hawkins, G; Churchill, M A; Morton-Blackshere, A; Pande, H; Adler, S P; Schmidt, G M; Forman, S J

    1990-01-01

    The human cytomegalovirus (HCMV) a-sequence (a-seq) is located in the joining region between the long (L) and short (S) unique sequences of the virus (L-S junction), and this hypervariable junction has been used to differentiate HCMV strains. The purpose of this study was to investigate whether there are differences among strains of human cytomegalovirus which could be characterized by polymerase chain reaction (PCR) amplification of the a-seq of HCMV DNA and to compare a PCR method of strain differentiation with conventional restriction fragment length polymorphism (RFLP) methodology by using HCMV junction probes. Laboratory strains of HCMV and viral isolates from individuals with HCMV infection were characterized by using both RFLPs and PCR. The PCR assay amplified regions in the major immediate-early gene (IE-1), the 64/65-kDa matrix phosphoprotein (pp65), and the a-seq of the L-S junction region. HCMV laboratory strains Towne, AD169, and Davis were distinguishable, in terms of size of the amplified product, when analyzed by PCR with primers specific for the a-seq but were indistinguishable by using PCR targeted to IE-1 and pp65 sequences. When this technique was applied to a characterization of isolates from individuals with HCMV infection, selected isolates could be readily distinguished. In addition, when the a-seq PCR product was analyzed with restriction enzyme digestion for the presence of specific sequences, these DNA differences were confirmed. PCR analysis across the variable a-seq of HCMV demonstrated differences among strains which were confirmed by RFLP in 38 of 40 isolates analyzed. The most informative restriction enzyme sites in the a-seq for distinguishing HCMV isolates were those of MnlI and BssHII. This indicates that the a-seq of HCMV is heterogeneous among wild strains, and PCR of the a-seq of HCMV is a practical way to characterize differences in strains of HCMV. Images PMID:1980680

  7. 99mTc-labeled gastrins of varying peptide chain length: Distinct impact of NEP/ACE-inhibition on stability and tumor uptake in mice

    International Nuclear Information System (INIS)

    Kaloudi, Aikaterini; Nock, Berthold A.; Lymperis, Emmanouil; Krenning, Eric P.; Jong, Marion de; Maina, Theodosia

    2016-01-01

    Introduction: In situ inhibition of neutral endopeptidase (NEP) has been recently shown to impressively increase the bioavailability and tumor uptake of biodegradable gastrin radioligands. Furthermore, angiotensin converting enzyme (ACE) has been previously shown to cleave gastrin analogs in vitro. In the present study, we have assessed the effects induced by single or dual NEP/ACE-inhibition on the pharmacokinetic profile of three 99m Tc-labeled gastrins of varying peptide chain length: [ 99m Tc]SG6 ([ 99m Tc-N 4 -Gln 1 ]gastrin(1–17)), [ 99m Tc]DG2 ([ 99m Tc-N 4 -Gly 4 ,DGlu 5 ]gastrin(4–17)) and [ 99m Tc]DG4 ([ 99m Tc-N 4 -DGlu 10 ]gastrin(10–17)). Methods: Mouse blood samples were collected 5 min after injection of each of [ 99m Tc]SG6/DG2/DG4 together with: a) vehicle, b) the NEP-inhibitor phosphoramidon (PA), c) the ACE-inhibitor lisinopril (Lis), or d) PA plus Lis and were analyzed by RP-HPLC for radiometabolite detection. Biodistribution was studied in SCID mice bearing A431-CCK2R(+/−) xenografts at 4 h postinjection (pi). [ 99m Tc]SG6 or [ 99m Tc]DG4 was coinjected with either vehicle or the above described NEP/ACE-inhibitor regimens; for [ 99m Tc]DG2 control and PA animal groups were only included. Results: Treatment of mice with PA induced significant stabilization of 99m Tc-radiotracers in peripheral blood, while treatment with Lis or Lis + PA affected the stability of des(Glu) 5 [ 99m Tc]DG4 only. In line with these findings, PA coinjection led to notable amplification of tumor uptake of radiopeptides compared to controls (P < 0.01). Only [ 99m Tc]DG4 profited by single Lis (2.06 ± 0.39%ID/g vs 0.99 ± 0.13%ID/g in controls) or combined Lis + PA coinjection (8.91 ± 1.61%ID/g vs 4.89 ± 1.33%ID/g in PA-group). Furthermore, kidney uptake remained favourably low and unaffected by PA and/or Lis coinjection only in the case of [ 99m Tc]DG4 (< 1.9%ID/g) resulting in the most optimal tumor-to-kidney ratios. Conclusions: In situ NEP

  8. Rotational diffusion of nonpolar and ionic solutes in 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides: is solute rotation always influenced by the length of the alkyl chain on the imidazolium cation?

    Science.gov (United States)

    Gangamallaiah, V; Dutt, G B

    2012-10-25

    In an attempt to find out whether the length of the alkyl chain on the imidazolium cation has a bearing on solute rotation, temperature-dependent fluorescence anisotropies of three structurally similar solutes have been measured in a series of 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides. Solute-solvent coupling constants obtained from the experimentally measured reorientation times with the aid of Stokes-Einstein-Debye hydrodynamic theory indicate that there is no influence of the length of the alkyl chain on the rotation of nonpolar, anionic, and cationic solutes 9-phenylanthracene (9-PA), fluorescein (FL), and rhodamine 110 (R110), respectively. It has also been noticed that the rotational diffusion of 9-PA is closer to the predictions of slip hydrodynamics, whereas the rotation of negatively charged FL and positively charged R110 is almost identical and follows stick hydrodynamics in these ionic liquids. Despite having similar shape and size, ionic solutes rotate slower by a factor of 3-4 compared to the nonpolar solute. Interplay of specific and electrostatic interactions between FL and the imidazolium cation of the ionic liquids, and between R110 and the bis(trifluoromethylsulfonyl)imide anion, appear to be responsible for the observed behavior. These results are an indication that the length of the alkyl chain on the imidazolium cation does not alter their physical properties in a manner that has an effect on solute rotation.

  9. Surfactant-assisted sol gel preparation of high-surface area mesoporous TiO2 nanocrystalline Li-ion battery anodes

    International Nuclear Information System (INIS)

    Casino, S.; Di Lupo, F.; Francia, C.; Tuel, A.; Bodoardo, S.; Gerbaldi, C.

    2014-01-01

    Highlights: • Mesoporous TiO 2 nanocrystalline lithium battery anodes with tunable morphology. • Simple sol–gel technique using different cationic surfactants is adopted. • Textural/morphological characteristics define the electrochemical behaviour. • TiO 2 anatase using C16TAB exhibits stable performance after 200 cycles. • It shows promising prospects as high-voltage safe Li-ion battery anode. - Abstract: We here investigate the physico-chemical/morphological characteristics and cycling behaviour of several kinds of nanocrystalline TiO 2 Li-ion battery anodes selectively prepared through a simple sol–gel strategy based on a low-cost titanium oxysulfate precursor, by mediation of different cationic surfactants having different features (e.g., chain lengths, counter ion, etc.): i.e., cetyl-trimethylammonium bromide (CTAB), cetyl-trimethylammonium chloride (CTAC), benzalkonium chloride (BC) or octadecyl-trimethyl ammonium bromide (C 18 TAB). X-ray diffraction profiles reveal single phase anatase having good correspondence with the reference pattern when using short chain CTAB, while in the other cases the presence of chloride and/or an increased chain length affect the purity of the samples. FESEM analysis reveal nanosized particles forming cauliflower-like aggregates. TiO 2 materials demonstrate mesoporous characteristics and large specific surface area ranging from 250 to 30 m 2 g −1 . Remarkably stable electrode performance are achieved by appropriately selecting the cationic surfactant and the surfactant/precursor ratio. Detailed analysis is provided on the effect of the reaction conditions upon the formation of mesoporous crystalline titania enlightening new directions for the development of high performing lithium storage electrodes by a simple and low cost sol–gel strategy

  10. Surfactant-assisted sol gel preparation of high-surface area mesoporous TiO{sub 2} nanocrystalline Li-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Casino, S. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Di Lupo, F., E-mail: francesca.dilupo@polito.it [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Francia, C. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Tuel, A. [IRCELYON, Institut de Recherches sur la Catalyse et l’environnement de Lyon, UMR 5256, CNRS-Université de Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); Bodoardo, S. [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Gerbaldi, C., E-mail: claudio.gerbaldi@polito.it [GAME Lab, Department of Applied Science and Technology – DISAT, Institute of Chemistry, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

    2014-05-01

    Highlights: • Mesoporous TiO{sub 2} nanocrystalline lithium battery anodes with tunable morphology. • Simple sol–gel technique using different cationic surfactants is adopted. • Textural/morphological characteristics define the electrochemical behaviour. • TiO{sub 2} anatase using C16TAB exhibits stable performance after 200 cycles. • It shows promising prospects as high-voltage safe Li-ion battery anode. - Abstract: We here investigate the physico-chemical/morphological characteristics and cycling behaviour of several kinds of nanocrystalline TiO{sub 2} Li-ion battery anodes selectively prepared through a simple sol–gel strategy based on a low-cost titanium oxysulfate precursor, by mediation of different cationic surfactants having different features (e.g., chain lengths, counter ion, etc.): i.e., cetyl-trimethylammonium bromide (CTAB), cetyl-trimethylammonium chloride (CTAC), benzalkonium chloride (BC) or octadecyl-trimethyl ammonium bromide (C{sub 18}TAB). X-ray diffraction profiles reveal single phase anatase having good correspondence with the reference pattern when using short chain CTAB, while in the other cases the presence of chloride and/or an increased chain length affect the purity of the samples. FESEM analysis reveal nanosized particles forming cauliflower-like aggregates. TiO{sub 2} materials demonstrate mesoporous characteristics and large specific surface area ranging from 250 to 30 m{sup 2} g{sup −1}. Remarkably stable electrode performance are achieved by appropriately selecting the cationic surfactant and the surfactant/precursor ratio. Detailed analysis is provided on the effect of the reaction conditions upon the formation of mesoporous crystalline titania enlightening new directions for the development of high performing lithium storage electrodes by a simple and low cost sol–gel strategy.

  11. PMMA-g-OEtOx Graft Copolymers: Influence of Grafting Degree and Side Chain Length on the Conformation in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Irina Muljajew

    2018-03-01

    Full Text Available Depending on the degree of grafting (DG and the side chain degree of polymerization (DP, graft copolymers may feature properties similar to statistical copolymers or to block copolymers. This issue is approached by studying aqueous solutions of PMMA-g-OEtOx graft copolymers comprising a hydrophobic poly(methyl methacrylate (PMMA backbone and hydrophilic oligo(2-ethyl-2-oxazoline (OEtOx side chains. The graft copolymers were synthesized via reversible addition-fragmentation chain transfer (RAFT copolymerization of methyl methacrylate (MMA and OEtOx-methacrylate macromonomers of varying DP. All aqueous solutions of PMMA-g-OEtOx (9% ≤ DG ≤ 34%; 5 ≤ side chain DP ≤ 24 revealed lower critical solution temperature behavior. The graft copolymer architecture significantly influenced the aggregation behavior, the conformation in aqueous solution and the coil to globule transition, as verified by means of turbidimetry, dynamic light scattering, nuclear magnetic resonance spectroscopy, and analytical ultracentrifugation. The aggregation behavior of graft copolymers with a side chain DP of 5 was significantly affected by small variations of the DG, occasionally forming mesoglobules above the cloud point temperature (Tcp, which was around human body temperature. On the other hand, PMMA-g-OEtOx with elongated side chains assembled into well-defined structures below the Tcp (apparent aggregation number (Nagg = 10 that were able to solubilize Disperse Orange 3. The thermoresponsive behavior of aqueous solutions thus resembled that of micelles comprising a poly(2-ethyl-2-oxazoline (PEtOx shell (Tcp > 60 °C.

  12. Structure and Conformational Dynamics of DMPC/Dicationic Surfactant and DMPC/Dicationic Surfactant/DNA Systems

    Directory of Open Access Journals (Sweden)

    Maciej Kozak

    2013-04-01

    Full Text Available Amphiphilic dicationic surfactants, known as gemini surfactants, are currently studied for gene delivery purposes. The gemini surfactant molecule is composed of two hydrophilic “head” groups attached to hydrophobic chains and connected via molecular linker between them. The influence of different concentrations of 1,5-bis (1-imidazolilo-3-decyloxymethyl pentane chloride (gemini surfactant on the thermotropic phase behaviour of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC bilayers with and without the presence of DNA was investigated using Fourier transformed infrared (FTIR and circular dichroism (CD spectroscopies, small angle scattering of synchrotron radiation and differential scanning calorimetry. With increasing concentration of surfactant in DMPC/DNA systems, a disappearance of pretransition and a decrease in the main phase transition enthalpy and temperature were observed. The increasing intensity of diffraction peaks as a function of surfactant concentration also clearly shows the ability of the surfactant to promote the organisation of lipid bilayers in the multilayer lamellar phase.

  13. Alkyl chain interaction at the surface of room temperature ionic liquids: systematic variation of alkyl chain length (R = C(1)-C(4), C(8)) in both cation and anion of [RMIM][R-OSO(3)] by sum frequency generation and surface tension.

    Science.gov (United States)

    Santos, Cherry S; Baldelli, Steven

    2009-01-29

    The gas-liquid interface of halide-free 1,3-dialkylimidazolium alkyl sulfates [RMIM][R-OSO(3)] with R chain length from C(1)-C(4) and C(8) has been studied systematically using the surface-specific sum frequency generation (SFG) vibrational spectroscopy and surface tension measurements. From the SFG spectra, vibrational modes from the methyl group of both cation and anion are observed for all ionic liquid samples considered in the present study. These results suggest the presence of both ions at the gas-liquid interface, which is further supported by surface tension measurements. Surface tension data show a decreasing trend as the alkyl chain in the imidazolium cation is varied from methyl to butyl chain, with a specific anion. A similar trend is observed when the alkyl chain of the anion is modified and the cation is fixed.

  14. Genomic DNA fingerprinting of clinical Haemophilus influenzae isolates by polymerase chain reaction amplification: comparison with major outer-membrane protein and restriction fragment length polymorphism analysis

    NARCIS (Netherlands)

    van Belkum, A.; Duim, B.; Regelink, A.; Möller, L.; Quint, W.; van Alphen, L.

    1994-01-01

    Non-capsulate strains of Haemophilus influenzae were genotyped by analysis of variable DNA segments obtained by amplification of genomic DNA with the polymerase chain reaction (PCR fingerprinting). Discrete fragments of 100-2000 bp were obtained. The reproducibility of the procedure was assessed by

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

    Science.gov (United States)

    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.

  16. Gemini (dimeric) Surfactants

    Indian Academy of Sciences (India)

    is in turn bonded to an identical hydrocarbon tail; alternatively,. ~. Tail spacer ... formed is dependent on surfactant structure, temperature, ionic strength and pH. The models of GS are .... micelle to the air/water interface. Moreover, GS can be ...

  17. Surfactants from petroleum paraffin wax

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, T.M.; Hussein, M.H.; El Sayed, A.S.

    Paraffin wax from Egyptian petroleum was purified and then oxidized to fatty acids which were esterified to form their methyl esters, fractionated and then hydrolysed. The obtained fatty acids were converted into the corresponding primary amines which were converted with ethylene oxide to form nonionic surfactants. The prepared primary amines were also converted into tertiary amines and then converted into cationic surfactants through condensation with benzyl chloride or 1-chloromethylnaphthalene. Also, amine oxide surfactants were prepared by oxidation of the tertiary amines with hydrogen peroxide. The surface active properties of all the prepared surfactants were determined, and the effect of their chemical structure on the surfactant properties are discussed in this paper.

  18. Effect of surfactants on the fluorescence spectra of water-soluble ...

    Indian Academy of Sciences (India)

    TECS

    Effect of surfactants on the fluorescence spectra of water-soluble. MEHPPV ... polyacrylic acid (PAA) chains grafted onto their backbone were found to be water soluble, and they exhi- ..... in other words the variation of emission intensity.

  19. Effect of selected non-ionic surfactants on the flow behavior of aqueous veegum suspensions.

    Science.gov (United States)

    Kennedy, Ross A; Kennedy, Michelle L

    2007-03-30

    The aim of this work was to investigate the influence of some non-ionic surfactants, Tween 80 and Brij 98, on the viscosity and flow behavior of a commercial montmorillonite clay, Veegum Granules. The effect of different concentrations of the surfactants on the shear stress-shear rate rheograms of hydrated concentrated clay suspensions was determined by shear viscometry. The addition of either surfactant increased the plastic viscosity and the yield stress of the suspensions. Furthermore, both surfactants altered the thixotropy of the suspensions to an extent that depended on both the surfactant concentration and the time of equilibration of the surfactant and Veegum. Brij 98 had a greater and more rapid effect. It is proposed that the surfactant polar head-groups anchor at the tetrahedral sheet surface, leaving the alkyl chains extending away from the edges and faces. Consequently, the alkyl chains undergo hydrophobic interactions that facilitate the association between the platelets and increase the physical structure within the suspension. Stereochemical differences between the polar groups may lead to differences in the way the surfactants associate with the tetrahedral sheet and hence their ultimate effect on the rheological behavior. There is a significant interaction between these surfactants and montmorillonite clays, and the rheological changes that occur could have a major impact on any pharmaceutical formulation that uses these ingredients.

  20. Effect of chemical structure on the cloud point of some new non-ionic surfactants based on bisphenol in relation to their surface active properties

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2011-06-01

    Full Text Available A series of non-ionic surfactants were prepared from bisphenol derived from acetone (A, acetophenone (AC and cyclohexanone (CH. The prepared bisphenols were ethoxylated at different degrees of ethylene oxide (27, 35, 43. The ethoxylated bisphenols were non-esterified by fatty acids; decanoic, lauric, myristic, palmitic, stearic, oleic, linoloic and linolinic. Some surface active properties for these surfactants were measured and calculated such as, surface tension [γ], critical micelle concentration [CMC], minimum area per molecule [Amin], surface excess [Cmax], free energy of micellization and adsorption [ΔGmic] and [ΔGads]. At a certain temperature, the cloud point was measured for these surfactants. From the obtained data it was found that; the cloud point is very sensitive to the increase of the alkyl chain length, content of ethylene oxide and degree of unsaturation. The core of bisphenol affected the cloud point sharply and they are ranked regarding bisphenol structure as BA > BCH > BAC. By inspection of the surface active properties of these surfactants, a good relation was obtained with their cloud points. The data were discussed on the light of their chemical structures.

  1. Microbial production of surfactants and their commercial potential.

    OpenAIRE

    Desai, J D; Banat, I M

    1997-01-01

    Many microorganisms, especially bacteria, produce biosurfactants when grown on water-immiscible substrates. Biosurfactants are more effective, selective, environmentally friendly, and stable than many synthetic surfactants. Most common biosurfactants are glycolipids in which carbohydrates are attached to a long-chain aliphatic acid, while others, like lipopeptides, lipoproteins, and heteropolysaccharides, are more complex. Rapid and reliable methods for screening and selection of biosurfactan...

  2. Influence of chain length of pyrene fatty acids on their uptake and metabolism by Epstein-Barr-virus-transformed lymphoid cell lines from a patient with multisystemic lipid storage myopathy and from control subjects.

    OpenAIRE

    Radom, J; Salvayre, R; Levade, T; Douste-Blazy, L

    1990-01-01

    The uptake and intracellular metabolism of 4-(1-pyrene)butanoic acid (P4), 10-(1-pyrene)decanoic acid (P10) and 12-(1-pyrene)dodecanoic acid (P12) were investigated in cultured lymphoid cell lines from normal individuals and from a patient with multisystemic lipid storage myopathy (MLSM). The cellular uptake was shown to be dependent on the fatty-acid chain length, but no significant difference in the uptake of pyrene fatty acids was observed between MLSM and control lymphoid cells. After inc...

  3. Dust as a surfactant

    International Nuclear Information System (INIS)

    Ignatov, A M; Schram, P P J M; Trigger, S A

    2003-01-01

    We argue that dust immersed in a plasma sheath acts as a surfactant. By considering the momentum balance in a plasma sheath, we evaluate the dependence of the plasma surface pressure on the dust density. It is shown that the dust may reduce the surface pressure, giving rise to a sufficiently strong tangential force. The latter is capable of confining the dust layer inside the sheath in the direction perpendicular to the ion flow

  4. MICROBIAL SURFACTANTS. I. GLYCOLIPIDS

    Directory of Open Access Journals (Sweden)

    Pirog T. Р.

    2014-02-01

    Full Text Available The review is devoted to surface-active glycolipids. The general characteristics, the physiological role of the rhamnolipids, trehalose lipids, sophorolipids, mannosylerythritol lipids and their traditional producers — the representatives of the genera Pseudozyma, Pseudomonas, Rhodococcus and Candida are given. The detailed analysis of the chemical structure, the stages of the biosynthesis and the regulation of some low molecular glycolipids are done. The own experimental data concerning the synthesis intensification, the physiological role and the practical use of Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 surfactants, which are a complex of the glyco-, phospho-, amino- and neutral lipids (glycolipids of all strains are presented by trehalose mycolates are summarized. It was found that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants have protective, antimicrobial and antiadhesive properties. It was shown that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants preparation of cultural liquid intensified the degradation of oil in water due to the activation of the natural petroleum-oxidizing microflora.

  5. Biodegradability of bacterial surfactants.

    Science.gov (United States)

    Lima, Tânia M S; Procópio, Lorena C; Brandão, Felipe D; Carvalho, André M X; Tótola, Marcos R; Borges, Arnaldo C

    2011-06-01

    This work aimed at evaluating the biodegradability of different bacterial surfactants in liquid medium and in soil microcosms. The biodegradability of biosurfactants by pure and mixed bacterial cultures was evaluated through CO(2) evolution. Three bacterial strains, Acinetobacter baumanni LBBMA ES11, Acinetobacter haemolyticus LBBMA 53 and Pseudomonas sp. LBBMA 101B, used the biosurfactants produced by Bacillus sp. LBBMA 111A (mixed lipopeptide), Bacillus subtilis LBBMA 155 (lipopeptide), Flavobacterium sp. LBBMA 168 (mixture of flavolipids), Dietzia Maris LBBMA 191(glycolipid) and Arthrobacter oxydans LBBMA 201(lipopeptide) as carbon sources in minimal medium. The synthetic surfactant sodium dodecyl sulfate (SDS) was also mineralized by these microorganisms, but at a lower rate. CO(2) emitted by a mixed bacterial culture in soil microcosms with biosurfactants was higher than in the microcosm containing SDS. Biosurfactant mineralization in soil was confirmed by the increase in surface tension of the soil aqueous extracts after incubation with the mixed bacterial culture. It can be concluded that, in terms of biodegradability and environmental security, these compounds are more suitable for applications in remediation technologies in comparison to synthetic surfactants. However, more information is needed on structure of biosurfactants, their interaction with soil and contaminants and scale up and cost for biosurfactant production.

  6. Gamma-irradiation of homodeoxyoligonucleotides 32P-labelled at one end: computer simulation of the chain length distribution of the radioactive fragments

    International Nuclear Information System (INIS)

    Teoule, R.; Duplaa, A.M.

    1987-01-01

    Electrophoresis on polyacrylamide gels of the fragments resulting from γ-irradiation of single-stranded oligodeoxyribonucleotides labelled at their 5'- or 3'-end proved a potent tool for analysis of the radiation-induced chain breakage of DNA. Owing to the fact that the oligonucleotide may be ruptured at more than one site, counting of the electrophoresis bands must be corrected and it is necessary to assess the influence of the cleavage position on the band intensities. A complicating factor is the inhomogeneity of the system due to the presence of the four bases A, T, C and G. To circumvent this problem, the homooligodeoxyribonucleotides (dA) 15 , (dC) 15 , (dT) 15 were used as experimental probes. They were γ-irradiated in solution, heated in alkali and resulting fragments separated by gel electrophoresis. A computer simulation of band intensities was compiled based on the general assumption that the chain breakage is homogeneous. Experimental results obtained from the homooligodeoxyribonucleotides labelled at either the 5' or the 3'-end are in excellent agreement with theoretical calculations. Abacus giving the gel band intensities (percentage) against the nucleotide positions and the remaining intensity of the original oligonucleotide have been obtained. (author)

  7. Enhanced solubilization of curcumin in mixed surfactant vesicles.

    Science.gov (United States)

    Kumar, Arun; Kaur, Gurpreet; Kansal, S K; Chaudhary, Ganga Ram; Mehta, S K

    2016-05-15

    Self-assemblies of equimolar double and single chain mixed ionic surfactants, with increasing numbers of carbon atoms of double chain surfactant, were analyzed on the basis of fluorescence and conductivity results. Attempts were also made to enhance the solubilization of curcumin in aqueous equimolar mixed surfactant systems. Mixed surfactant assembly was successful in retarding the degradation of curcumin in alkaline media (only 25-28 40% degraded in 10h at pH 13). Fluorescence spectroscopy and fluorescence quenching methods were employed to predict the binding position and mechanism of curcumin with self-assemblies. Results indicate that the interactions take place according to both dynamic and static quenching mechanisms and curcumin was distributed in a palisade layer of mixed aggregates. Antioxidant activity (using DPPH radical) and biocompatibility (using calf-thymus DNA) of curcumin-loaded mixed surfactant formulations were also evaluated. The prepared systems improved the stability, solubility and antioxidant activity of curcumin and additionally are biocompatible. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Porcine lung surfactant protein B gene (SFTPB)

    DEFF Research Database (Denmark)

    Cirera Salicio, Susanna; Fredholm, Merete

    2008-01-01

    The porcine surfactant protein B (SFTPB) is a single copy gene on chromosome 3. Three different cDNAs for the SFTPB have been isolated and sequenced. Nucleotide sequence comparison revealed six nonsynonymous single nucleotide polymorphisms (SNPs), four synonymous SNPs and an in-frame deletion of 69...... bp in the region coding for the active protein. Northern analysis showed lung-specific expression of three different isoforms of the SFTPB transcript. The expression level for the SFTPB gene is low in 50 days-old fetus and it increases during lung development. Quantitative real-time polymerase chain...

  9. Effect of a Long Chain Carboxylate Acid on Sodium Dodecyl Sulfate Micelle Structure: A Small-angle Neutron Scattering Study

    International Nuclear Information System (INIS)

    Arum Patriati; Edy Giri Rachman Putra

    2009-01-01

    The effect of different hydrocarbon chain length of carboxylate acid, i.e. dodecanoic acid, CH 3 (CH 2 ) 10 COOH and hexadecanoic acid, CH 3 (CH 2 ) 14 COOH as a co-surfactant in the 0.3M SDS micellar solution has been studied using small angle neutron scattering (SANS). Here, the present of dodecanoic acid has induced the SDS structural micelles. The ellipsoid micelles structures changed significantly in length (major axis) from 21.7 Armstrong to 35.5 Armstrong at a fixed minor axis of 16.7 Armstrong in the present of 0.005M to 0.1M dodecanoic acid. Nevertheless, this effect was not shown in the present of hexadecanoic acid with the same concentration range. The present of hexadecanoic acid molecules gave a small effect on growth of SDS micelles where the major axis of the micelle was simply elongated from 21.5 Armstrong to 23.5 Armstrong. It showed that the appropriate hydrocarbon chain length between surfactant and co-surfactant molecules is one of the determining factors in forming a mixed micelles structure. (author)

  10. Surfactant-Mediated Growth Revisited

    International Nuclear Information System (INIS)

    Meyerheim, H. L.; Sander, D.; Popescu, R.; Pan, W.; Kirschner, J.; Popa, I.

    2007-01-01

    The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films

  11. Influence of chain length of pyrene fatty acids on their uptake and metabolism by Epstein-Barr-virus-transformed lymphoid cell lines from a patient with multisystemic lipid storage myopathy and from control subjects.

    Science.gov (United States)

    Radom, J; Salvayre, R; Levade, T; Douste-Blazy, L

    1990-01-01

    The uptake and intracellular metabolism of 4-(1-pyrene)butanoic acid (P4), 10-(1-pyrene)decanoic acid (P10) and 12-(1-pyrene)dodecanoic acid (P12) were investigated in cultured lymphoid cell lines from normal individuals and from a patient with multisystemic lipid storage myopathy (MLSM). The cellular uptake was shown to be dependent on the fatty-acid chain length, but no significant difference in the uptake of pyrene fatty acids was observed between MLSM and control lymphoid cells. After incubation for 1 h the distribution of fluorescent fatty acids taken up by the lymphoid cell lines also differed with the chain length, most of the fluorescence being associated with phospholipid and triacylglycerols. In contrast with P10 and P12, P4 was not incorporated into neutral lipids. When the cells were incubated for 24 h with the pyrene fatty acids, the amount of fluorescent lipids synthesized by the cells was proportional to the fatty acid concentration in the culture medium. After a 24 h incubation in the presence of P10 or P12, at any concentration, the fluorescent triacylglycerol content of MLSM cells was 2-5-fold higher than that of control cells. Concentrations of pyrene fatty acids higher than 40 microM seemed to be more toxic for mutant cells than for control cells. This cytotoxicity was dependent on the fluorescent-fatty-acid chain length (P12 greater than P10 greater than P4). Pulse-chase experiments permitted one to demonstrate the defect in the degradation of endogenously biosynthesized triacylglycerols in MLSM cells (residual activity was around 10-25% of controls on the basis of half-lives and initial rates of P10- or P12-labelled-triacylglycerol catabolism); MLSM lymphoid cells exhibited a mild phenotypic expression of the lipid storage (less severe than that observed in fibroblasts). P4 was not utilized in the synthesis of triacylglycerols, and thus did not accumulate in MLSM cells: this suggests that natural short-chain fatty acids might induce a lesser

  12. Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

    International Nuclear Information System (INIS)

    Jobe, A.H.; Ikegami, M.; Seidner, S.R.; Pettenazzo, A.; Ruffini, L.

    1989-01-01

    Preterm lambs were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated lambs

  13. Biocatalytic synthesis of polymeric nanowires by micellar templates of ionic surfactants

    International Nuclear Information System (INIS)

    Nazari, K.; Adhami, F.; Najjar-Safari, A.; Salmani, S.; Mahmoudi, A.

    2011-01-01

    Highlights: → Soft-template production of polyguaiacol nanowire was done by peroxidase enzyme. → Main advantage of this simple method is producing soluble encapsulated nanowires. → Nanowire can be easily precipitated and separated by dilution with distilled water. → Size tuned templates of sodium decyl sulfate (d = 2.7 nm) gave nanowires with d = 2-4 nm. → Dried surfactant-coated wires recover freshly on specified and desired applications. -- Abstract: Micelle-templated polyguaiacol nanowires were successfully prepared via polymerization oxidation of guaiacol (o-methoxy phenol) by peroxidase enzyme in the presence of hydrogen peroxide at mild reaction conditions. The dimensions of the prepared nanowires were controlled by tuning the size and shape of the micelle structure via changing and controlling the type, chain length and molar concentrations of the ionic surfactant. The progress of the reaction and estimation of the size of soft micellar templates were followed by UV-Vis spectroscopy and dynamic light scattering (DLS). The resulting micelle encapsulated or purified polyguaiacol nanowires were characterized using transmission electron microscopy (TEM).

  14. Biocatalytic synthesis of polymeric nanowires by micellar templates of ionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, K., E-mail: nazarikh@ripi.ir [Research Institute of Petroleum Industry, NIOC, P.O. Box 14665-137, Tehran (Iran, Islamic Republic of); Chemistry Dept., Shahr Rey Islamic Azad University, P.O. Box 18735-334, Tehran (Iran, Islamic Republic of); Adhami, F.; Najjar-Safari, A.; Salmani, S. [Chemistry Dept., Shahr Rey Islamic Azad University, P.O. Box 18735-334, Tehran (Iran, Islamic Republic of); Mahmoudi, A. [Chemistry Dept., Karaj Islamic Azad University, Karaj (Iran, Islamic Republic of)

    2011-07-15

    Highlights: {yields} Soft-template production of polyguaiacol nanowire was done by peroxidase enzyme. {yields} Main advantage of this simple method is producing soluble encapsulated nanowires. {yields} Nanowire can be easily precipitated and separated by dilution with distilled water. {yields} Size tuned templates of sodium decyl sulfate (d = 2.7 nm) gave nanowires with d = 2-4 nm. {yields} Dried surfactant-coated wires recover freshly on specified and desired applications. -- Abstract: Micelle-templated polyguaiacol nanowires were successfully prepared via polymerization oxidation of guaiacol (o-methoxy phenol) by peroxidase enzyme in the presence of hydrogen peroxide at mild reaction conditions. The dimensions of the prepared nanowires were controlled by tuning the size and shape of the micelle structure via changing and controlling the type, chain length and molar concentrations of the ionic surfactant. The progress of the reaction and estimation of the size of soft micellar templates were followed by UV-Vis spectroscopy and dynamic light scattering (DLS). The resulting micelle encapsulated or purified polyguaiacol nanowires were characterized using transmission electron microscopy (TEM).

  15. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    International Nuclear Information System (INIS)

    Voisin, David

    2002-01-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and the CSC have been determined for mixtures of

  16. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Voisin, David

    2002-07-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and

  17. Kinetics and mechanism for the sonochemical degradation of a nonionic surfactant.

    Science.gov (United States)

    Singla, Ritu; Grieser, Franz; Ashokkumar, Muthupandian

    2009-03-26

    The sonolytic degradation of the nonionic surfactant, octaethylene glycol monododecyl ether (C(12)E(8)), has been studied at various initial concentrations below and above its critical micelle concentration (CMC). It has been observed that the degradation rate increases with an increase in the initial concentration of the surfactant until the CMC is reached. Above the CMC an almost constant degradation rate is observed, suggesting that the surfactant in its monomer form is involved in the degradation process. The degradation process of C(12)E(8) involves two distinct primary processes occurring at the bubble/solution interface: (a) hydroxylation/oxidation of the surfactant and (b) pyrolytic fragmentation of the surfactant. The oxidative cleavage of ethylene oxide units provides evidence for OH radical attack. Hydroxylation of the ethoxy chain gives rise to various short-chain carboxyalkyl-polyethylene glycol intermediates. The polyethylene glycol chain formed, due to the scission of the C(12)E(8) molecule, undergoes rapid hydroxylation/oxidation to yield simple compounds that have the potential to undergo further degradation. The detection of multiple intermediates indicates that several processes affect the complete degradation pathways of the surfactant molecule. TOC analysis, however, indicates that the sonolytic mineralization of the surfactant is difficult to achieve at reasonable rates due to the relatively low surface activity of the degradation products formed during sonolysis.

  18. Engineering a disulfide bond in the lid hinge region of Rhizopus chinensis lipase: increased thermostability and altered acyl chain length specificity.

    Directory of Open Access Journals (Sweden)

    Xiao-Wei Yu

    Full Text Available 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 t(1/2 value at 60°C and a 7°C increase of T(m 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 (k(cat 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.

  19. ADSORPTION OF SURFACTANT ON CLAYS

    Science.gov (United States)

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  20. Poloxamer-Decorated Polymer Nanoparticles for Lung Surfactant Compatibility

    DEFF Research Database (Denmark)

    Beck-Broichsitter, Moritz; Bohr, Adam; Ruge, Christian A

    2017-01-01

    Lung-delivered polymer nanoparticles provoked dysfunction of the essential lung surfactant system. A steric shielding of the nanoparticle surface with poloxamers could minimize the unwanted interference of polymer nanoparticles with the biophysical function of lung surfactant. The extent of poly......(styrene) and poly(lactide) nanoparticle-induced lung surfactant inhibition could be related to the type and content of the applied poloxamer. Escalations of the adsorbed coating layer thickness (>3 nm) as well as concentration (brush- rather than mushroom-like conformation of poly(ethylene glycol), chain......-associated proteins. Poloxamer-modified polymer nanoparticles represent a promising nanomedicine platform intended for respiratory delivery revealing negligible effects on the biophysical functionality of the lining layer present in the deep lungs....

  1. Dynamics of cyanophenyl alkylbenzoate molecules in the bulk and in a surface layer adsorbed onto aerosil. Variation of the lengths of the alkyl chain

    Energy Technology Data Exchange (ETDEWEB)

    Frunza, Stefan [National Institute of Materials Physics, R-077125 Magurele (Romania); Schoenhals, Andreas [BAM Federal Institute of Materials Research and Testing, D-12205 Berlin (Germany); Frunza, Ligia, E-mail: lfrunza@infim.ro [National Institute of Materials Physics, R-077125 Magurele (Romania); Beica, Traian; Zgura, Irina; Ganea, Paul [National Institute of Materials Physics, R-077125 Magurele (Romania); Stoenescu, Daniel [Telecom-Bretagne, Departement d' Optique, Technopole Brest-Iroise 29238 Cedex (France)

    2010-06-16

    Graphical abstract: The temperature dependence of the molecular mobility in composites shows an Arrhenius-type regime at low temperature and a glassy-type one at higher temperature separated by a crossover phenomenon. - Abstract: The molecular mobility of 4-butyl- and 4-pentyl-4'-cyanophenyl benzoate (CP4B, CP5B) and their composites prepared from aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range. Thermogravimetric and infrared investigations were additionally performed. High silica density (larger than 7 g aerosil/1 g of liquid crystal) was selected to observe a thin layer adsorbed on the surface of the silica particles. The data were compared with those of the member of the series with six carbon atoms in the alkyl tail. Bulk CP4B and CP5B show the dielectric behaviour expected for liquid crystals. For the composites one relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in a surface layer. The temperature dependence of the relaxation rates (and of the dielectric strength) shows a crossover behaviour with two distinguished regimes. At higher temperatures the data obey the Vogel-Fulcher-Tammann law, whereas an Arrhenius law is observed at lower temperature, in a close similarity to the behaviour of a constrained dynamic glass transition. The estimated Vogel and crossover temperature is independent on the tail length, while the activation energy for the low temperature branch increases weakly with increasing the alkyl tail.

  2. Surfactant media for constant-current coulometry. Application for the determination of antioxidants in pharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Ziyatdinova, Guzel, E-mail: Ziyatdinovag@mail.ru [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation); Ziganshina, Endzhe; Budnikov, Herman [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation)

    2012-09-26

    Highlights: Black-Right-Pointing-Pointer Applicability of surfactants in constant-current coulometry is shown for the first time. Black-Right-Pointing-Pointer Reactions of antioxidants with electrogenerated titrants in surfactant media are investigated. Black-Right-Pointing-Pointer Water insoluble antioxidants can be determined in water media with addition of surfactants. Black-Right-Pointing-Pointer Coulometric determination of antioxidants in pharmaceutical dosage forms using surfactants media is developed. - Abstract: Effect of surfactant presence on electrochemical generation of titrants has been evaluated and discussed for the first time. Cationic (1-dodecylpyridinium and cetylpyridinium bromide), anionic (sodium dodecyl sulfate) and nonionic (Triton X100 and Brij{sup Registered-Sign} 35) surfactants as well as nonionic high molecular weight polymer (PEG 4000) do not react with the electrogenerated bromine, iodine and hexacyanoferrate(III) ions. The electrogenerated chlorine chemically interact with Triton X100 and Brij{sup Registered-Sign} 35. The allowable range of surfactants concentrations providing 100% current yield has been found. Chain-breaking low molecular weight antioxidants (ascorbic acid, rutin, {alpha}-tocopherol and retinol) were determined by reaction with the electrogenerated titrants in surfactant media. Nonionic and cationic surfactants can be used for the determination of antioxidants by reaction with the electrogenerated halogens. On contrary, cationic surfactants gives significantly overstated results of antioxidants determination with electrogenerated hexacyanoferrate(III) ions. The use of surfactants in coulometry of {alpha}-tocopherol and retinol provides their solubilization and allows to perform titration in water media. Simple, express and reliable coulometric approach for determination of {alpha}-tocopherol, rutin and ascorbic acid in pharmaceuticals using surfactant media has been developed. The relative standard deviation of the

  3. Controlling Active Liquid Crystal Droplets with Temperature and Surfactant Concentration

    Science.gov (United States)

    Shechter, Jake; Milas, Peker; Ross, Jennifer

    Active matter is the study of driven many-body systems that span length scales from flocking birds to molecular motors. A previously described self-propelled particle system was made from liquid crystal (LC) droplets in water with high surfactant concentration to move particles via asymmetric surface instabilities. Using a similar system, we investigate the driving activity as a function of SDS surfactant concentration and temperature. We then use an optical tweezer to trap and locally heat the droplets to cause hydrodynamic flow and coupling between multiple droplets. This system will be the basis for a triggerable assembly system to build and couple LC droplets. DOD AROMURI 67455-CH-MUR.

  4. Genetic polymorphism of toll-like receptors 4 gene by polymerase chain reaction-restriction fragment length polymorphisms, polymerase chain reaction-single-strand conformational polymorphism to correlate with mastitic cows

    Directory of Open Access Journals (Sweden)

    Pooja H. Gupta

    2015-05-01

    Full Text Available Aim: An attempt has been made to study the toll-like receptors 4 (TLR4 gene polymorphism from cattle DNA to correlate with mastitis cows. Materials and Methods: In present investigation, two fragments of TLR4 gene named T4CRBR1 and T4CRBR2 of a 316 bp and 382 bp were amplified by polymerase chain reaction (PCR, respectively from Kankrej (22 and Triple cross (24 cattle. The genetic polymorphisms in the two populations were detected by a single-strand conformational polymorphism in the first locus and by digesting the fragments with restriction endonuclease Alu I in the second one. Results: Results showed that both alleles (A and B of two loci were found in all the two populations and the value of polymorphism information content indicated that these were highly polymorphic. Statistical results of χ2 test indicated that two polymorphism sites in the two populations fit with Hardy–Weinberg equilibrium (p˂0.05. Meanwhile, the effect of polymorphism of TLR4 gene on the somatic cell score (SCS indicated the cattle with allele a in T4CRBR1 showed lower SCS than that of allele B (p<0.05. Thus, the allele A might play an important role in mastitis resistance in cows. Conclusion: The relationship between the bovine mastitis trait and the polymorphism of TLR4 gene indicated that the bovine TLR4 gene may play an important role in mastitis resistance.

  5. (Cationic + nonionic) mixed surfactant aggregates for solubilisation of curcumin

    International Nuclear Information System (INIS)

    Kumar, Arun; Kaur, Gurpreet; Kansal, S.K.; Chaudhary, G.R.; Mehta, S.K.

    2016-01-01

    Highlights: • Critical micelle concentration of mixed surfactant has been measured. • Aqueous solubility and alkaline stability of curcumin has been significantly improved. • Location of curcumin within micelles has been evaluated. • Scavenging activity of curcumin has been improved. • Non-intercalative binding with ct-DNA has been observed. - Abstract: Curcumin is a potential drug for variety of diseases. Major limitations of curcumin are low water solubility, rapid hydrolytic degradation in alkaline medium and poor bioavailability. To overcome these limitations, highly potential mixed micellar system has been prepared. In order to reduce inter ionic repulsion and precipitation of surfactants, (cationic + non-ionic) mixed system have been chosen that directly influence its applicability. Hydrophobic chain of non-ionic surfactant significantly influences the cmc of mixed surfactant system as indicated by fluorescence and conductivity data. UV–visible spectroscopy analyses show that solubility, stability and antioxidant property of the curcumin is remarkably improved depending on cmc and aggregation number (N_a_g_g) of mixed surfactants, where N_a_g_g plays crucial role. Generally, curcumin undergoes complete degradation in slight basic medium, but stability has been maintained up to 8 h at pH-13 using formulated mixed micelles (only (20 to 25)% degraded). Location of curcumin which is monitored using emission spectroscopy, fluorescence quenching and "1H NMR spectroscopy techniques play the most important role. Observed results show that the major population of curcumin is located at the polar region and some are in hydrophobic region of the mixed micelles. To ensure the effect of mixed surfactants and curcumin loaded mixed surfactants on DNA, the interaction parameter indicates non-interclative interactions.

  6. Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

    Science.gov (United States)

    Miranda, Paulo Barbeitas

    solid/liquid interface. It is shown that the conformation of a monolayer adsorbed onto a solid substrate and immersed in a liquid is highly dependent on the monolayer surface density and on the nature of intermolecular interactions in the liquid. Fully packed monolayers are well ordered in any environment due to strong surfactant-surfactant interactions and limited liquid penetration into the monolayer. In contrast, loosely packed monolayers are very sensitive to the liquid environment. Non-polar liquids cause a mild increase in the surfactant conformational disorder. Polar liquids induce more disorder and hydrogen-bonding liquids produce highly disordered conformations due to the hydrophobic effect. When immersed in alkanes, under certain conditions the surfactant chains may become highly ordered due to their interaction with the liquid molecules (chain-chain interaction). In the case of long-chain alcohols, competition between the hydrophobic effect and chain-chain interaction is observed.

  7. N-terminal fatty acylated His-dPhe-Arg-Trp-NH(2) tetrapeptides: influence of fatty acid chain length on potency and selectivity at the mouse melanocortin receptors and human melanocytes.

    Science.gov (United States)

    Todorovic, Aleksandar; Holder, Jerry Ryan; Bauzo, Rayna M; Scott, Joseph Walker; Kavanagh, Renny; Abdel-Malek, Zalfa; Haskell-Luevano, Carrie

    2005-05-05

    The melanocortin system is involved in the regulation of a diverse number of physiologically important pathways including pigmentation, feeding behavior, weight and energy homeostasis, inflammation, and sexual function. All the endogenous melanocortin agonist ligands possess the conserved His-Phe-Arg-Trp tetrapeptide sequence that is postulated to be important for melanocortin receptor molecular recognition and stimulation. Previous studies by our laboratory resulted in the discovery that increasing alkyl chain length at the N-terminal "capping" region of the His-dPhe-Arg-Trp-NH(2) tetrapeptide resulted in a 100-fold increased melanocortin receptor agonist potency. This study was undertaken to systematically evaluate the pharmacological effects of increasing N-capping alkyl chain length of the CH(3)(CH(2))(n)CO-His-dPhe-Arg-Trp-NH(2) (n = 6-16) tetrapeptide template. Twelve analogues were synthesized and pharmacologically characterized at the mouse melanocortin receptors MC1R and MC3R-MC5R and human melanocytes known to express the MC1R. These peptides demonstrated melanocortin receptor selectivity profiles different from those of previously published tetrapeptides. The most notable results of enhanced ligand potency (20- to 200-fold) and receptor selectivity were observed at the MC1R. Tetrapeptides that possessed greater than nine alkyl groups were superior to alpha-MSH in terms of the stimulation of human melanocyte tyrosinase activity. Additionally, the n-pentadecanoyl derivative had a residual effect on tyrosinase activity that existed for at least 4 days after the peptide was removed from the human melanocyte culture medium. These data demonstrate the utility, potency, and residual effect of melanocortin tetrapeptides by adding N-terminal fatty acid moieties.

  8. Aerobic biodegradation of amphoteric amine-oxide-based surfactants: Effect of molecular structure, initial surfactant concentration and pH.

    Science.gov (United States)

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

    2017-03-01

    The present study was designed to provide information regarding the effect of the molecular structure of amphoteric amine-oxide-based surfactants and the initial surfactant concentration on their ultimate biodegradation. Moreover, given this parameter's pH-dependence, the effect of pH was also investigated. Three amine-oxide-based surfactants with structural differences in their hydrophobic alkyl chain were tested: Lauramine oxide (AO-R 12 ), Myristamine oxide (AO-R 14 ) and Cocamidopropylamine oxide (AO-Cocoamido). We studied the ultimate biodegradation using the Modified OECD Screening Test at initial surfactant concentrations ranged from 5 to 75 mg L -1 and at pH levels from 5 to 7.4. The results demonstrate that at pH 7.4, amine-oxide-based surfactants are readily biodegradable. In this study, we concluded that ω-oxidation can be assumed to be the main biodegradation pathway of amine-oxides and that differences in the biodegradability between them can be explained by the presence of an amide group in the alkyl chain of AO-Cocoamido; the CN fission of the amide group slows down their mineralization process. In addition, the increase in the concentration of the surfactant from 5 to 75 mg L -1 resulted in an increase in the final biodegradation of AO-R 12 and AO-R 14 . However, in the case of AO-Cocoamido, a clear relationship between the concentration and biodegradation cannot be stated. Conversely, the biodegradability of AO-R 12 and AO-R 14 was considerably lower in an acid condition than at a pH of 7.4, whereas AO-Cocoamido reached similar percentages in acid conditions and at a neutral pH. However, microorganisms required more time to acclimate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. MICROBIAL SURFACTANTS IN ENVIRONMENTAL TECHNOLOGIES

    Directory of Open Access Journals (Sweden)

    T. P. Pirog

    2015-08-01

    Full Text Available It was shown literature and own experimental data concerning the use of microbial surface active glycolipids (rhamno-, sophoro- and trehalose lipids and lipopeptides for water and soil purification from oil and other hydrocarbons, removing toxic heavy metals (Cu2+, Cd2+, Ni2+, Pb2+, degradation of complex pollution (oil and other hydrocarbons with heavy metals, and the role of microbial surfactants in phytoremediation processes. The factors that limit the use of microbial surfactants in environmental technologies are discussed. Thus, at certain concentrations biosurfactant can exhibit antimicrobial properties and inhibit microorganisms destructing xenobiotics. Microbial biodegradability of surfactants may also reduce the effectiveness of bioremediation. Development of effective technologies using microbial surfactants should include the following steps: monitoring of contaminated sites to determine the nature of pollution and analysis of the autochthonous microbiota; determining the mode of surfactant introduction (exogenous addition of stimulation of surfactant synthesis by autochthonous microbiota; establishing an optimal concentration of surfactant to prevent exhibition of antimicrobial properties and rapid biodegradation; research both in laboratory and field conditions.

  10. Preparation of a Fluorocarbon Polymerizable Surfactant and Its Application in Emulsion Polymerization of Fluorine-Containing Acrylate

    Directory of Open Access Journals (Sweden)

    Meng Zhao

    2017-11-01

    Full Text Available A novel polymerizable fluorocarbon surfactant, perfluoro (4–methyl–3, 6–dioxaoct–7–ene sodium sulfonate (PSVNa, was synthesized and characterized. The fluorocarbon surfactant PSVNa and its mixture PSVNa/SDS were used as emulsifiers during the emulsion polymerization of DFHMA/MMA. The investigation of polymerization kinetics, particle size, and stability of the emulsions revealed that PSVNa has excellent emulsifying properties. The NMR spectrum of the copolymer and the detection of residual PSVNa show that more than 95% of the fluorocarbon surfactants have been linked to the polymer chains by radical polymerization, which will greatly reduce the environmental pollution caused by fluorinated surfactants.

  11. Surfactant Membrane Phases Containing Mixtures of Hydrocarbon and Fluorocarbon Surfactants

    International Nuclear Information System (INIS)

    de Campo, Liliana; Warr, G.G.

    2005-01-01

    Full text: We describe the structure and stability of sponge and lamellar phases comprising mixtures of hydrocarbon and fluorocarbon surfactants. Such mixtures can show limited miscibility with each other, forming for example coexisting populations of hydrocarbon rich and fluorocarbon rich micelles under some circumstances. Our system is based on the well-characterised lamellar and sponge phases of cetylpyridinium chloride, hexanol and 0.2M brine, into which the partially fluorinated surfactant N-1H,1H,2H,2H-tridecafluorooctylpyridinium chloride is incorporated. By probing the structures with SAXS (small angle x-ray scattering) and SANS (small angle neutron scattering) using contrast variation, and by characterizing the dynamic properties with dynamic light scattering, we will describe the effect of incorporating the fluorinated surfactant on the phase equilibria and properties of the surfactant membrane structures. (authors)

  12. Theoretical and Simulations-Based Modeling of Micellization in Linear and Branched Surfactant Systems

    Science.gov (United States)

    Mendenhall, Jonathan D.

    's and other micellization properties for a variety of linear and branched surfactant chemical architectures which are commonly encountered in practice. Single-component surfactant solutions are investigated, in order to clarify the specific contributions of the surfactant head and tail to the free energy of micellization, a quantity which determines the cmc and all other aspects of micellization. First, a molecular-thermodynamic (MT) theory is presented which makes use of bulk-phase thermodynamics and a phenomenological thought process to describe the energetics related to the formation of a micelle from its constituent surfactant monomers. Second, a combined computer-simulation/molecular-thermodynamic (CSMT) framework is discussed which provides a more detailed quantification of the hydrophobic effect using molecular dynamics simulations. A novel computational strategy to identify surfactant head and tail using an iterative dividing surface approach, along with simulated micelle results, is proposed. Force-field development for novel surfactant structures is also discussed. Third, a statistical-thermodynamic, single-chain, mean-field theory for linear and branched tail packing is formulated, which enables quantification of the specific energetic penalties related to confinement and constraint of surfactant tails within micelles. Finally, these theoretical and simulations-based strategies are used to predict the micellization behavior of 55 linear surfactants and 28 branched surfactants. Critical micelle concentration and optimal micelle properties are reported and compared with experiment, demonstrating good agreement across a range of surfactant head and tail types. In particular, the CSMT framework is found to provide improved agreement with experimental cmc's for the branched surfactants considered. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

  13. Maternal long chain polyunsaturated fatty acid supplementation in infancy increases length- and weight-for-age but not BMI to 6 years when controlling for effects of maternal smoking

    Science.gov (United States)

    Currie, L.M.; Tolley, E.A.; Thodosoff, J.M.; Kerling, E.H.; Sullivan, D.K.; Colombo, J.; Carlson, S.E.

    2015-01-01

    Summary Long chain polyunsaturated fatty acids (LCPUFA) are added to infant formula but their effect on long-term growth of children is under studied. We evaluated the effects of feeding LCPUFA-supplemented formula (n=54) compared to control formula (n=15) throughout infancy on growth from birth-6 years. Growth was described using separate models developed with the MIXED procedure of SAS® that included maternal smoking history and gender. Compared to children fed control formula, children who consumed LCPUFA supplemented formula had higher length-/stature-/and weight-for-age percentiles but not body mass index (BMI) percentile from birth to 6 years. Maternal smoking predicted lower stature (2-6 years), higher weight-for-length (birth-18 months) and BMI percentile (2-6 years) independent of LCPUFA effects. Gender interacted with the effect of LCPUFA on stature, and the relationship between smoking and BMI, with a larger effect for boys. Energy intake did not explain growth differences. A relatively small control sample is a limitation. PMID:25936840

  14. Molecular self assembly of mixed comb-like dextran surfactant polymers for SPR virus detection.

    Science.gov (United States)

    Mai-Ngam, Katanchalee; Kiatpathomchai, Wansika; Arunrut, Narong; Sansatsadeekul, Jitlada

    2014-11-04

    The synthesis of two comb-like dextran surfactant polymers, that are different in their dextran molecular weight (MW) distribution and the presence of carboxylic groups, and their characterization are reported. A bimodal carboxylic dextran surfactant polymer consists of poly(vinyl amine) (PVAm) backbone with carboxyl higher MW dextran, non-functionalized lower MW dextran and hydrophobic hexyl branches; while a monomodal dextran surfactant polymer is PVAm grafted with non-functionalized lower MW dextran and hexyl branches. Layer formation of non-covalently attached dextran chains with bimodal MW distributions on a surface plasmon resonance (SPR) chip was investigated from the perspective of mixed physisorption of the bimodal and monomodal surfactant polymers. Separation distances between the carboxylic longer dextran side chains within the bimodal surfactant polymer and between the whole bimodal surfactant molecules on the chip surface could be well-controlled. SPR analysis of shrimp yellow head virus using our mixed surfactant chips showed dependence on synergetic adjustment of these separation distances. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Fundamental length and relativistic length

    International Nuclear Information System (INIS)

    Strel'tsov, V.N.

    1988-01-01

    It si noted that the introduction of fundamental length contradicts the conventional representations concerning the contraction of the longitudinal size of fast-moving objects. The use of the concept of relativistic length and the following ''elongation formula'' permits one to solve this problem

  16. Studying the silver nanoparticles influence on thermodynamic behavior and antimicrobial activities of novel amide Gemini cationic surfactants.

    Science.gov (United States)

    Shaban, Samy M; Abd-Elaal, Ali A

    2017-07-01

    Three novels amide Gemini cationic surfactants with various alkyl chains and their silver nanohybrid with silver nanoparticles were synthesized and a confirmation study for surfactant and their nanoparticles formation has been established using IR, 1 HNMR, TEM and UV-Vis spectroscopy. The surface-active properties of these surfactants and their nanoform were investigated through surface tension and electrical conductivity measurements and a comparative study has been established. The thermodynamic parameters of micellization and adsorption were assessed at temperatures range from 25 to 65°C. The effect of silver particles on the surface behavior of the synthesized surfactant has been discussed. The aggregation behavior of silver nanoparticles with these synthesized Gemini surfactants in water were investigated using dynamic light scattering and transmission electron microscopy. Furthermore, the antimicrobial activities of these synthesized amide Gemini surfactants and their nanostructure with silver against both Gram positive and Gram negative bacteria were also investigated. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Flame Length

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Flame length was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The tool...

  18. Biodegradation of surfactant bearing wastes

    International Nuclear Information System (INIS)

    Chitra, S.; Chandran, S.; Sasidhar, P.; Lal, K.B.; Amalraj, R.V.

    1991-01-01

    In nuclear industry, during decontamination of protective wears and contaminated materials, detergents are employed to bring down the level of radioactive contamination within safe limits. However, the surfactant present in these wastes interferes in the chemical treatment process, reducing the decontamination factor. Biodegradation is an efficient and ecologically safe method for surfactant removal. A surfactant degrading culture was isolated and inoculated separately into simulated effluents containing 1% yeast extract and 5-100 ppm sodium lauryl sulphate (SLS) and 1% yeast extract and 5-100 ppm of commercial detergent respectively. The growth of the bacterial culture and the degradation characteristics of the surfactant in the above effluents were monitored under both dynamic and static conditions. (author). 6 refs., 6 figs., 1 tab

  19. Treatment with exogenous surfactant stimulates endogenous surfactant synthesis in premature infants with respiratory distress syndrome

    NARCIS (Netherlands)

    Bunt, JEH; Carnielli, VP; Janssen, DJ; Wattimena, JLD; Hop, WC; Sauer, PJ; Zimmermann, LJI

    2000-01-01

    Objective: Treatment of preterm infants with respiratory distress syndrome (RDS) with exogenous surfactant has greatly improved clinical outcome. Some infants require multiple doses, and it has not been studied whether these large amounts of exogenous surfactant disturb endogenous surfactant

  20. Analytical calculation of chain length in ferrofluids

    Indian Academy of Sciences (India)

    2Department of Mechanical Engineering, Tezpur University, Assam 784028, India. MS received 4 ... under an external magnetic field applied parallel to the slit containing the ... of competition between magnetic dipolar interaction and.

  1. Synthesis of polymer nanostructures via the use of surfactant surface aggregates as templates

    Science.gov (United States)

    Marquez, Maricel

    method for the formation of nanometer-scale polymer structures on solid surfaces via template assisted admicellar polymerization (TAAP) is described. Admicellar polymerization uses a surfactant layer adsorbed on a surface to localize monomer to the surface prior to polymerization of the monomer. TAAP refers to nanostructures that form by restricting adsorption to the uncovered sites of an already-templated surface. In this case, the interstitial sites between adsorbed latex spheres were used as the template. Unlike most other process that form polymer nanostructures, polymer dimensions can be significantly smaller than the interstitial size because of sphere-surfactant-monomer interactions. As a proof of concept, nanostructures formed via TAAP were compared to structures prepared by others via adsorption of three different proteins (Bovine serum albumin, fibrinogen, and anti-mouse IgG) in the interstitial sites of colloidal monolayers. The size and shape of the nanostructures formed (honeycomb vs. pillars) was dependent upon the size of the spheres utilized and the method of polymer deposition (i.e. admicellar polymerization vs. polymer adsorption). Thinner honeycomb walls, and larger separation distances between the template and the nanostructures were consistently found for TAAP. In chapter 4, an in-depth study of the factors affecting TAAP is presented for three different monomers: aniline, pyrrole and methyl methacrylate; and three different surfaces: highly ordered pyrolytic graphite (HOPG), gold, and SiO2. Among the parameters discussed are the effect of monomer and surfactant concentration, surfactant chain length, polymerization time and temperature, solution ionic strength, substrate choice and surface treatment. Control over these parameters allowed the synthesis of polymer nanopillars, nanorings, honeycombs, and "honeytubes." Experimental results showed that the nanostructures' morphology can be effectively modified by changing the length of the hydrophobic

  2. Surfactant flooding of diesel-contaminated soils

    International Nuclear Information System (INIS)

    Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.A.

    1991-01-01

    At one installation, approximately 60,000 gallons of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of this research program after initial surfactant screening of 21 surfactants. Three of the surfactants were used for the surfactant flooding studies; the results from that phase of the research program are described

  3. Fundamental length

    International Nuclear Information System (INIS)

    Pradhan, T.

    1975-01-01

    The concept of fundamental length was first put forward by Heisenberg from purely dimensional reasons. From a study of the observed masses of the elementary particles known at that time, it is sumrised that this length should be of the order of magnitude 1 approximately 10 -13 cm. It was Heisenberg's belief that introduction of such a fundamental length would eliminate the divergence difficulties from relativistic quantum field theory by cutting off the high energy regions of the 'proper fields'. Since the divergence difficulties arise primarily due to infinite number of degrees of freedom, one simple remedy would be the introduction of a principle that limits these degrees of freedom by removing the effectiveness of the waves with a frequency exceeding a certain limit without destroying the relativistic invariance of the theory. The principle can be stated as follows: It is in principle impossible to invent an experiment of any kind that will permit a distintion between the positions of two particles at rest, the distance between which is below a certain limit. A more elegant way of introducing fundamental length into quantum theory is through commutation relations between two position operators. In quantum field theory such as quantum electrodynamics, it can be introduced through the commutation relation between two interpolating photon fields (vector potentials). (K.B.)

  4. Dicationic alkylammonium bromide gemini surfactants. Membrane perturbation and skin irritation.

    Directory of Open Access Journals (Sweden)

    João A S Almeida

    Full Text Available Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For this purpose, keratinocyte cells from human skin (NCTC 2544 cell line, frequently used as a model for skin irritation, were employed. The impact of the different gemini surfactants on the permeability and morphology of model vesicles was additionally investigated by measuring the leakage of calcein fluorescent dye and analyzing the NMR spectra of ³¹P, respectively. Detail on the interaction of gemini molecules with model membranes was also provided by a systematic differential scanning calorimetry (DSC and molecular dynamics (MD simulation. An irreversible impact on the viability of the NCTC 2544 cell line was observed for gemini concentrations higher than 25 mM, while no cytotoxicity was found for any of the surfactants in a concentration range up to 10 mM. A higher cytotoxicity was also found for gemini surfactants presenting longer spacer and shorter tails. The same trend was obtained in the calorimetric and permeability studies, with the gemini of longest spacer promoting the highest degree of membrane destabilization. Additional structural and dynamical characterization of the various systems, obtained by ³¹P NMR and MD, provide some insight on the relationship between the architecture of gemini surfactants and the respective perturbation mechanism.

  5. Differentiation of canine distemper virus isolates in fur animals from various vaccine strains by reverse transcription-polymerase chain reaction-restriction fragment length polymorphism according to phylogenetic relations in china

    Directory of Open Access Journals (Sweden)

    Zhao Jianjun

    2011-02-01

    Full Text Available Abstract In order to effectively identify the vaccine and field strains of Canine distemper virus (CDV, a new differential diagnostic test has been developed based on reverse transcription-polymerase chain reaction (RT-PCR and restriction fragment length polymorphism (RFLP. We selected an 829 bp fragment of the nucleoprotein (N gene of CDV. By RFLP analysis using BamHI, field isolates were distinguishable from the vaccine strains. Two fragments were obtained from the vaccine strains by RT-PCR-RFLP analysis while three were observed in the field strains. An 829 nucleotide region of the CDV N gene was analyzed in 19 CDV field strains isolated from minks, raccoon dogs and foxes in China between 2005 and 2007. The results suggest this method is precise, accurate and efficient. It was also determined that three different genotypes exist in CDV field strains in fur animal herds of the north of China, most of which belong to Asian type. Mutated field strains, JSY06-R1, JSY06-R2 and JDH07-F1 also exist in Northern China, but are most closely related to the standard virulent strain A75/17, designated in Arctic and America-2 genetype in the present study, respectively.

  6. Adsorption of naphthalene and ozone on atmospheric air/ice interfaces coated with surfactants: a molecular simulation study.

    Science.gov (United States)

    Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

    2012-03-15

    The adsorption of gas-phase naphthalene and ozone molecules onto air/ice interfaces coated with different surfactant species (1-octanol, 1-hexadecanol, or 1-octanal) was investigated using classical molecular dynamics (MD) simulations. Naphthalene and ozone exhibit a strong preference to be adsorbed at the surfactant-coated air/ice interfaces, as opposed to either being dissolved into the bulk of the quasi-liquid layer (QLL) or being incorporated into the ice crystals. The QLL becomes thinner when the air/ice interface is coated with surfactant molecules. The adsorption of both naphthalene and ozone onto surfactant-coated air/ice interfaces is enhanced when compared to bare air/ice interface. Both naphthalene and ozone tend to stay dissolved in the surfactant layer and close to the QLL, rather than adsorbing on top of the surfactant molecules and close to the air region of our systems. Surfactants prefer to orient at a tilted angle with respect to the air/ice interface; the angular distribution and the most preferred angle vary depending on the hydrophilic end group, the length of the hydrophobic tail, and the surfactant concentration at the air/ice interface. Naphthalene prefers to have a flat orientation on the surfactant coated air/ice interface, except at high concentrations of 1-hexadecanol at the air/ice interface; the angular distribution of naphthalene depends on the specific surfactant and its concentration at the air/ice interface. The dynamics of naphthalene molecules at the surfactant-coated air/ice interface slow down as compared to those observed at bare air/ice interfaces. The presence of surfactants does not seem to affect the self-association of naphthalene molecules at the air/ice interface, at least for the specific surfactants and the range of concentrations considered in this study.

  7. Thermodynamics of inclusion complex formation of β-cyclodextrin with a variety of surfactants differing in the nature of headgroup

    International Nuclear Information System (INIS)

    Benkő, Mária; Király, Zoltán

    2012-01-01

    Highlights: ► Inclusion complexation of β-cyclodextrins with various surfactants. ► Thermodynamic parameters determined by titration microcalorimetry. ► Stoichiometry of complexation is 1:1. ► The binding constant decreases linearly with increasing temperature. ► Enthalpy–entropy compensation is independent of the nature of the headgroup. - Abstract: The inclusion complexation of β-cyclodextrin with various surfactants, possessing the same alkyl chain length but differing in the hydrophilic headgroup, was investigated by isothermal titration microcalorimetry. Sodium dodecyl sulfate, sodium dodecyl sulfonate, dodecyltrimethylammonium bromide and dodecyl(dimethyl)amine oxide were investigated. The major aim of this study was to elucidate the effects of temperature and the nature of the headgroup on the complex formation. Thermometric titrations were effected between the temperatures (288 and 348) K. The results provided the stoichiometry, the equilibrium constant and the reaction enthalpy of complexation. Changes in Gibbs energy, entropy and van’t Hoff enthalpy were additionally calculated.

  8. Synthesis of carbohydrate-based surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Pemberton, Jeanne E.; Polt, Robin L.; Maier, Raina M.

    2016-11-22

    The present invention provides carbohydrate-based surfactants and methods for producing the same. Methods for producing carbohydrate-based surfactants include using a glycosylation promoter to link a carbohydrate or its derivative to a hydrophobic compound.

  9. Assessment of primary eye and skin irritants by in vitro cytotoxicity and phototoxicity models: an in vitro approach of new arginine-based surfactant-induced irritation

    International Nuclear Information System (INIS)

    Benavides, T.; Mitjans, M.; Martinez, V.; Clapes, P.; Infante, M.R.; Clothier, R.H.; Vinardell, M.P.

    2004-01-01

    Extensive efforts have been made, recently, to find surfactants with lower irritation potential than those presently commercially available, for use in pharmaceutical and cosmetic preparations. Cytotoxic and phototoxic effects of a novel family of dicationic arginine-diglyceride surfactant compounds, 1,2-diacyl,3-O-(L-arginyl)-rac-glycerol with alkyl chain lengths in the range from 8 to 14 carbon atoms, were compared to three commercial surfactants. The end-points used to assess toxicity were the red blood cell lysis assay and uptake of the vital dye neutral red 24 h after dosing (NRU), respectively. Two immortalized cell lines, murine fibroblast cell line, 3T3, and one human keratinocyte cell line, HaCaT, were used as in vitro models to predict the potential phototoxicity which could result in irritation, determined by resazurin reduction to resorufin and neutral red uptake (NRU). All tested surfactants had cytotoxicity effects as demonstrated by and decrease of NR uptake, which showed a clear concentration-response relationship. Concentrations resulting in 50% inhibition of NR uptake (IC 50 ) range from 1 μmol l -1 (hexadecyl trimethyl ammonium bromide) to 565 μmol l -1 (12,12-L-arginine). Erythrocyte haemolysis also showed a clear concentration-response relationship, the 50% of haemolysis ranged from 37 μmol l -1 (10,10-L-arginine) to 151 μmol l -1 (sodium lauryl sulphate). Phototoxicity was performed with 12,12-L-acetyl-arginine, the most stable chemical structure. The validated 3T3 NRU photoxicity assay was used and revealed a phototoxic potential

  10. Effect of Dialkyl Ammonium Cationic Surfactants on the Microfluidity of Membranes Containing Raft Domains.

    Science.gov (United States)

    Uyama, Makoto; Inoue, Kaori; Kinoshita, Koichi; Miyahara, Reiji; Yokoyama, Hirokazu; Nakano, Minoru

    2018-01-01

    It has been reported that a lot of receptors localize in lipid raft domains and that the microfluidity of these domains regulates the activation of these receptors. In this study, we focused on the lipid raft and in order to evaluate the physicochemical effects of surfactants on microfluidity of lipid membranes, we used liposomes comprising of egg-yolk L-α-phosphatidylcholine, egg-yolk sphingomyelin, and cholesterol as a model of cell membranes containing raft domains. The microfluidity of the domains was characterized by fluorescence spectrometry using 1,6-diphenyl-1,3,5-hexatriene and 2-dimethylamino-6-lauroylnaphthalene. Among several surfactants, dialkylammonium-type cationic surfactants most efficiently increased the microfluidity. It is therefore concluded that (1) the electrostatic interaction between the cationic surfactant and eggPC/eggSM/cholesterol liposome could be important, (2) surfactants with alkyl chains more effectively inserted into membranes than those with acyl chains, and (3) cationic surfactants with lower T m values have a greater ability to increase the fluidity.

  11. New thermo-sensitive chelating surfactants for selective solvent-free extraction of uranyl nitrate

    International Nuclear Information System (INIS)

    Prevost, S.; Larpent, C.; Testard, F.; Coulombeau, H.; Baczko, K.; Berthon, L.; Desvaux, H.; Madic, C.; Zemb, T.

    2004-01-01

    Functional surfactants were synthesised by grafting a chelating group (amino-acid residue) to the tip of a poly-ethoxylated nonionic surfactant chain (C i E j : C i H 2i +1(OCH 2 CH 2 ) j OH)) or in a branched position. C i E j nonionic surfactants are known to be thermo-reversible and to exhibit a clouding phenomenon associated to phase separation of micelles. The functional surfactants retain both surface-active properties, characteristic thermo-reversible behaviour and have efficient complexing properties toward uranyl. In the presence of uranyl nitrate, small micelles are formed at ambient temperature and the de-mixing leads to a separation of the target ion trapped by the functional surfactant (cloud point extraction). Those surfactants are more efficient than mixture of classical C i E j and complexing agent solubilized in the micelles. This reveals a synergistic effect of the covalent bond between the chelating group and the nonionic surfactant C i E j . This paper presents a systematic study of the extraction and aggregation properties and the influence of the nature of the ions. (authors)

  12. Impact of cationic surfactant on the self-assembly of sodium caseinate.

    Science.gov (United States)

    Vinceković, Marko; Curlin, Marija; Jurašin, Darija

    2014-08-27

    The impact of a cationic surfactant, dodecylammonium chloride (DDACl), on the self-assembly of sodium caseinate (SC) has been investigated by light scattering, zeta potential, and rheological measurements as well as by microscopy (transmission electron and confocal laser scanning microscopy). In SC dilute solutions concentration-dependent self-assembly proceeds through the formation of spherical associates and their aggregation into elongated structures composed of connected spheres. DDACl interacts with SC via its hydrophilic and hydrophobic groups, inducing changes in SC self-assembled structures. These changes strongly depend on the surfactant aggregation states (monomeric or micellar) as well as concentration ratio of both components, leading to the formation of soluble and insoluble complexes of nano- to microdimensions. DDACl monomers interact with SC self-assembled entities in a different way compared to their micelles. Surfactant monomers form soluble complexes (similar to surfactant mixed micelles) at lower SC concentration but insoluble gelatinous complexes at higher SC concentration. At surfactant micellar concentration soluble complexes with casein chains wrapped around surfactant micelles are formed. This study suggests that the use of proper cationic surfactant concentration will allow modification and control of structural changes of SC self-assembled entities.

  13. Binding of cationic surfactants to humic substances

    NARCIS (Netherlands)

    Ishiguro, M.; Tan, W.; Koopal, L.K.

    2007-01-01

    Commercial surfactants are introduced into the environment either through waste products or site-specific contamination. The amphiphilic nature of both surfactants and humic substances (HS) leads to their mutual attraction especially when surfactant and HS are oppositely charged. Binding of the

  14. Thermodynamic Insights into the Binding of Mono- and Dicationic Imidazolium Surfactant Ionic Liquids with Methylcellulose in the Diluted Regime.

    Science.gov (United States)

    Ziembowicz, Francieli Isa; Bender, Caroline Raquel; Frizzo, Clarissa Piccinin; Martins, Marcos Antonio Pinto; de Souza, Thiane Deprá; Kloster, Carmen Luisa; Santos Garcia, Irene Teresinha; Villetti, Marcos Antonio

    2017-09-07

    Alkylimidazolium salts are an important class of ionic liquids (ILs) due to their self-assembly capacity when in solution and due to their potential applications in chemistry and materials science. Therefore, detailed knowledge of the physicochemical properties of this class of ILs and their mixtures with natural polymers is highly desired. This work describes the interactions between a homologous series of mono- (C n MIMBr) and dicationic imidazolium (C n (MIM) 2 Br 2 ) ILs with cellulose ethers in aqueous medium. The effects of the alkyl chain length (n = 10, 12, 14, and 16), type, and concentration range of ILs (below and above their cmc) on the binding to methylcellulose (MC) were evaluated. The thermodynamic parameters showed that the interactions are favored by the increase of the IL hydrocarbon chain length, and that the binding of monocationic ILs to MC is driven by entropy. The monocationic ILs bind more effectively on the methoxyl group of MC when compared to dicationic ILs, and this outcome may be rationalized by considering the structural difference between the conventional (C n MIMBr) and the bolaform (C n (MIM) 2 Br 2 ) surfactant ILs. The C 16 MIMBr interacts more strongly with hydroxypropylcellulose when compared to methylcellulose, indicating that the strength of the interaction also depends on the hydrophobicity of the cellulose ethers. Our findings highlight that several parameters should be taken into account when designing new complex formulations.

  15. Persurf, a new method to improve surfactant delivery: a study in surfactant depleted rats.

    Directory of Open Access Journals (Sweden)

    Wolfram Burkhardt

    Full Text Available PURPOSE: Exogenous surfactant is not very effective in adults with ARDS, since surfactant does not reach atelectatic alveoli. Perfluorocarbons (PFC can recruit atelectatic areas but do not replace impaired endogenous surfactant. A surfactant-PFC-mixture could combine benefits of both therapies. The aim of the proof-of-principal-study was to produce a PFC-in-surfactant emulsion (Persurf and to test in surfactant depleted Wistar rats whether Persurf achieves I. a more homogenous pulmonary distribution and II. a more homogenous recruitment of alveoli when compared with surfactant or PFC alone. METHODS: Three different PFC were mixed with surfactant and phospholipid concentration in the emulsion was measured. After surfactant depletion, animals either received 30 ml/kg of PF5080, 100 mg/kg of stained (green dye Curosurf™ or 30 ml/kg of Persurf. Lungs were fixated after 1 hour of ventilation and alveolar aeration and surfactant distribution was estimated by a stereological approach. RESULTS: Persurf contained 3 mg/ml phospholipids and was stable for more than 48 hours. Persurf-administration improved oxygenation. Histological evaluation revealed a more homogenous surfactant distribution and alveolar inflation when compared with surfactant treated animals. CONCLUSIONS: In surfactant depleted rats administration of PFC-in-surfactant emulsion leads to a more homogenous distribution and aeration of the lung than surfactant alone.

  16. Kondo length in bosonic lattices

    Science.gov (United States)

    Giuliano, Domenico; Sodano, Pasquale; Trombettoni, Andrea

    2017-09-01

    Motivated by the fact that the low-energy properties of the Kondo model can be effectively simulated in spin chains, we study the realization of the effect with bond impurities in ultracold bosonic lattices at half filling. After presenting a discussion of the effective theory and of the mapping of the bosonic chain onto a lattice spin Hamiltonian, we provide estimates for the Kondo length as a function of the parameters of the bosonic model. We point out that the Kondo length can be extracted from the integrated real-space correlation functions, which are experimentally accessible quantities in experiments with cold atoms.

  17. Reactive surfactants in heterophase polymerization

    NARCIS (Netherlands)

    Guyot, A.; Tauer, K.; Asua, J.M.; Es, van J.J.G.S.; Gauthier, C.; Hellgren, A.C.; Sherrington, D.C.; Montoya-Goni, A.; Sjöberg, M.; Sindt, O.; Vidal, F.F.M.; Unzue, M.; Schoonbrood, H.A.S.; Schipper, E.T.W.M.; Lacroix-Desmazes, P.

    1999-01-01

    This paper summarizes the work carried out during 3 years in a Network of the program "Human Capital and Mobility" of the European Union CHRX 93-0159 entitled "Reactive surfactants in heterophase polymerization for high performance polymers". A series of about 25 original papers will be published in

  18. Novel star-like surfactant as dispersant for multi-walled carbon nanotubes in aqueous suspensions at high concentration

    Science.gov (United States)

    Qiao, Min; Ran, Qianping; Wu, Shishan

    2018-03-01

    A kind of novel surfactant with star-like molecular structure and terminated sulfonate was synthesized, and it was used as the dispersant for multi-walled carbon nanotubes (CNTs) in aqueous suspensions compared with a traditional single-chained surfactant. The star-like surfactant showed good dispersing ability for multi-walled CNTs in aqueous suspensions. Surface tension analysis, total organic carbon analysis, X-ray photoelectron spectroscopy, zeta potential, dynamic light scattering and transmission electron microscopy were performed to research the effect of star-like surfactant on the dispersion of multi-walled CNTs in aqueous suspensions. With the assistance of star-like surfactant, the CNTs could disperse well in aqueous suspension at high concentration of 50 g/L for more than 30 days, while the CNTs precipitated completely in aqueous suspension after 1 day without any dispersant or after 10 days with sodium 4-dodecylbenzenesulfonic acid as dispersant.

  19. Structure of DNA-Cationic Surfactant Complexes at Hydrophobically Modified and Hydrophilic Silica Surfaces as Revealed by Neutron Reflectometry

    DEFF Research Database (Denmark)

    Cardenas Gomez, Marite; Wacklin, Hanna; Campbell, Richard A.

    2011-01-01

    with dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) on hydrophobic surfaces, where we show that DNA molecules are located on top of a self-assembled surfactant monolayer, with the thickness of the DNA layer and the surfactant DNA ratio determined by the surface coverage of the underlying...... interfacial structures, a higher concentration in relation to its cmc is required for the more soluble DTAB surfactant with a shorter alkyl chain than for CTAB. Our results suggest that the DNA Molecules Will spontaneously form a relatively dense, thin layer on top of a surfactant monolayer (hydrophobic...... surface) or a layer of admicelles (hydrophilic surface) as long as the surface concentration of surfactant is great enough to ensure a high interfacial-charge density. These findings have implications for bioanalytical and nanotechnology applications, which require the deposition of DNA layers with well...

  20. Electrostatic Interactions Govern "Odd/Even" Effects in Water-Induced Gemini Surfactant Self-Assembly.

    Science.gov (United States)

    Mantha, Sriteja; McDaniel, Jesse G; Perroni, Dominic V; Mahanthappa, Mahesh K; Yethiraj, Arun

    2017-01-26

    Gemini surfactants comprise two single-tailed surfactants connected by a linker at or near the hydrophilic headgroup. They display a variety of water-concentration-dependent lyotropic liquid crystal morphologies that are sensitive to surfactant molecular structure and the nature of the headgroups and counterions. Recently, an interesting dependence of the aqueous-phase behavior on the length of the linker has been discovered; odd-numbered linker length surfactants exhibit characteristically different phase diagrams than even-numbered linker surfactants. In this work, we investigate this "odd/even effect" using computer simulations, focusing on experimentally studied gemini dicarboxylates with Na + counterions, seven nonterminal carbon atoms in the tails, and either three, four, five, or six carbon atoms in the linker (denoted Na-73, Na-74, Na-75, and Na-76, respectively). We find that the relative electrostatic repulsion between headgroups in the different morphologies is correlated with the qualitative features of the experimental phase diagrams, predicting destabilization of hexagonal phases as the cylinders pack close together at low water content. Significant differences in the relative headgroup orientations of Na-74 and Na-76 compared to those of Na-73 and Na-75 surfactants lead to differences in linker-linker packing and long-range headgroup-headgroup electrostatic repulsion, which affects the delicate electrostatic balance between the hexagonal and gyroid phases. Much of the fundamental insight presented in this work is enabled by the ability to computationally construct and analyze metastable phases that are not observable in experiments.

  1. Surfactant screening of diesel-contaminated soil

    International Nuclear Information System (INIS)

    Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.-A.

    1992-01-01

    At one installation in California, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, resulting in contamination at depths from 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. This paper summarizes a surfactant screening/surfactant flooding research program in which 22 surfactants were screened for their effectiveness in mobilizing the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on contaminated soil samples obtained from the site

  2. Surfactant gene polymorphisms and interstitial lung diseases

    Directory of Open Access Journals (Sweden)

    Pantelidis Panagiotis

    2001-11-01

    Full Text Available Abstract Pulmonary surfactant is a complex mixture of phospholipids and proteins, which is present in the alveolar lining fluid and is essential for normal lung function. Alterations in surfactant composition have been reported in several interstitial lung diseases (ILDs. Furthermore, a mutation in the surfactant protein C gene that results in complete absence of the protein has been shown to be associated with familial ILD. The role of surfactant in lung disease is therefore drawing increasing attention following the elucidation of the genetic basis underlying its surface expression and the proof of surfactant abnormalities in ILD.

  3. Surfactant -- Where Are We in 2003?

    Directory of Open Access Journals (Sweden)

    JF Lewis

    2004-01-01

    Full Text Available Surfactant research has progressed over the past several years to the extent that exogenous surfactant administration in patients with the acute respiratory distress syndrome (ARDS is now being evaluated. Unfortunately, clinical responses have been variable, and we now need to take a look at how surfactant is altered in this disease so that more effective treatment strategies can be developed. This review briefly discusses the biophysical and host defense properties of surfactant, the impact of mechanical ventilation (MV on the endogenous surfactant system and the most recent clinical data involving exogenous surfactant administration in patients with ARDS. Discussions regarding future directions of surfactant research both in ARDS and diseases other than acute lung injury are included.

  4. Comblike poly(ethylene oxide)/hydrophobic C6 branched chitosan surfactant polymers as anti-infection surface modifying agents.

    Science.gov (United States)

    Mai-ngam, Katanchalee

    2006-05-01

    A series of structurally well-defined poly(ethylene oxide)/hydrophobic C6 branched chitosan surfactant polymers that undergo surface induced self assembly on hydrophobic biomaterial surfaces were synthesized and characterized. The surfactant polymers consist of low molecular weight (Mw) chitosan backbone with hydrophilic poly(ethylene oxide) (PEO) and hydrophobic hexyl pendant groups. Chitosan was depolymerized by nitrous acid deaminative cleavage. Hexanal and aldehyde-terminated PEO chains were simultaneously attached to low Mw chitosan hydrochloride via reductive amination. The surfactant polymers were prepared with various ratios of the two side chains. The molecular composition of the surfactant polymers was determined by FT-IR and 1H NMR. Surface active properties at the air-water interface were determined by Langmuir film balance measurements. The surfactant polymers with PEO/hexyl ratios of 1:3.0 and 1:14.4 were used as surface modifying agents to investigate their anti-infection properties. E. coli adhesion on Silastic surface was decreased significantly by the surfactant polymer with PEO/hexyl 1:3.0. Surface growth of adherent E. coli was effectively suppressed by both tested surfactant polymers.

  5. Thermal stability and hot-stage Raman spectroscopic study of Ca-montmorillonite modified with different surfactants: A comparative study

    International Nuclear Information System (INIS)

    Sun, Zhiming; Park, Yuri; Zheng, Shuilin; Ayoko, Godwin A.; Frost, Ray L.

    2013-01-01

    Highlights: • A typical Ca-montmorillonite was modified with three surfactants through ion exchange. • The organoclays were characterized by XRD, TG and hot stage Raman. • The structural geometry and thermal properties of organoclays were analyzed. • The prepared organoclays show potential prospects in the environmental remediation. - Abstract: Three long chain cationic surfactants were intercalated into Ca-montmorillonite through ion exchange and the obtained organoclays were characterized by X-ray diffraction (XRD), high resolution thermogravimetric analysis (TG) and Raman spectroscopy. The intercalation of surfactants not only changes the surface properties of clay from hydrophilic to hydrophobic but also greatly increases the basal spacing of the interlayers based on XRD analysis. The thermal stability of organoclays intercalated with three surfactants (TTAB, DTAB and CTAB) and the different arrangements of the surfactant molecules intercalated into Ca-montmorillonite were determined by TG-DTG analysis. A Raman spectroscopic study on the Ca-montmorillonite modified by three surfactants prepared at different concentrations provided the detailed conformational ordering of different intercalated long-chain surfactants under different conditions. The wavenumber of the antisymmetric stretching mode is more sensitive than that of the symmetric stretching mode to the mobility of the tail of the amine chain. At room temperature, the conformational ordering is more easily affected by the packing density in the lateral model. With the increase of the temperature, the positions of both the antisymmetric and symmetric stretching bands shift to higher wavenumbers, which indicates a decrease of conformational ordering. This study offers new insights into the structure and properties of Ca-montmorillonite modified with different long chain surfactants. Moreover, the experimental results confirm the potential applications of organic Ca-montmorillonites for the removal

  6. Synthesis, surface properties and oil solubilisation capacity of cationic gemini surfactants

    NARCIS (Netherlands)

    Dam, Th.; Engberts, J.B.F.N.; Karthäuser, J.; Karaborni, S.; Os, N.M. van

    1996-01-01

    The critical micelle concentration (CMC) and the surface tension at the CMC have been determined for the gemini surfactants alkanediyl-u,w-bis(dimethyla1kylammoniubmr omide) by means of dynamic surface tension measurements. For the same number of carbon atoms in the hydrophobic chain per hydrophilic

  7. Modulation of the wettability of excipients by surfactant and its impacts on the disintegration and release of tablets.

    Science.gov (United States)

    Yang, Baixue; Xu, Lu; Wang, Qiuxiao; Li, Sanming

    2016-12-01

    To investigate the modulation of the wettability of excipients by different types of surfactants and its impacts on the disintegration of tablets and drug release. The critical micelle concentration (CMC) of surfactants, including sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), dodecyl trimethyl ammonium bromide (DTAB), cetyltrimethyl ammonium bromide (CTAB) and polysorbate (Tween-20 and Tween-80), was obtained using the platinum ring method. Contact angles of surfactant solutions on the excipient compacts and double-distilled water on the mixture of surfactant and the other excipient (magnesium stearate (MgSt) or sodium alginate (SA)) were measured by the sessile drop technique. Besides, surface free energy of excipients was calculated by the Owens method. Finally, the disintegration of tablets and in vitro dissolution testing were performed according to the method described in USP. The wettability of excipients could be enhanced to different extent with low concentration of surfactant solutions and maintained stable basically after CMC. For MgSt (hydrophobic excipient), the shorter the hydrophobic chain (C 12 , including SDS and DTAB), the better the wettability with the addition of surfactant in the formulation, leading to the shorter disintegration time of tablets and higher drug release rate. In contrast, the wettability of SA (hydrophilic excipient) was reduced by adding surfactant, resulting in the longer disintegration time of tablets and lower release rate. The modulation of the wetting of pharmaceutical excipients by surfactant had changed the disintegration time of tablets and drug release rate to a greater extent.

  8. Strong cooperative effect of oppositely charged surfactant mixtures on their adsorption and packing at the air-water interface and interfacial water structure.

    Science.gov (United States)

    Nguyen, Khoi T; Nguyen, Tuan D; Nguyen, Anh V

    2014-06-24

    Remarkable adsorption enhancement and packing of dilute mixtures of water-soluble oppositely-charged surfactants, sodium dodecyl sulfate (SDS) and dodecyl amine hydrochloride (DAH), at the air-water interface were observed by using sum frequency generation spectroscopy and tensiometry. The interfacial water structure was also observed to be significantly influenced by the SDS-DAH mixtures, differently from the synergy of the single surfactants. Most strikingly, the obtained spectroscopic evidence suggests that the interfacial hydrophobic alkyl chains of the binary mixtures assemble differently from those of single surfactants. This study highlights the significance of the cooperative interaction between the headgroups of oppositely charged binary surfactant systems and subsequently provides some insightful observations about the molecular structure of the air-aqueous interfacial water molecules and, more importantly, about the packing nature of the surfactant hydrophobic chains of dilute SDS-DAH mixtures of concentration below 1% of the CMC.

  9. On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Ingo, E-mail: ingo.hoffmann@tu-berlin.de [Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin (Germany); Institut Max von Laue-Paul Langevin (ILL), F-38042 Grenoble Cedex 9 (France); Farago, Bela; Schweins, Ralf; Falus, Peter; Sharp, Melissa [Institut Max von Laue-Paul Langevin (ILL), F-38042 Grenoble Cedex 9 (France); Prévost, Sylvain [Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin (Germany); Helmholtz-Zentrum Berlin, D-14109 Berlin (Germany); Gradzielski, Michael, E-mail: michael.gradzielski@tu-berlin.de [Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin (Germany)

    2015-08-21

    Oppositely charged polyelectrolyte (PE) surfactant mixtures allow the control of rheological parameters of a solution even at fairly low concentrations. For example, addition of 0.3 wt. % of anionic surfactant to a 1 wt. % solution of the polycation JR 400 increases the viscosity by 4 orders of magnitude. Recently, we could show that this increase is related to the formation of mixed, rod-like PE/surfactant aggregates which interconnect several polyelectrolyte chains [Hoffmann et al., Europhys. Lett. 104, 28001 (2013)]. In this paper, we refine our structural model of the aggregates to obtain a more consistent picture of their internal structure for different anionic surfactants. Combining small angle neutron scattering (SANS) and neutron spin-echo (NSE) allows us to determine the size of the aggregates. By comparing different contrasts, the internal structure of the aggregates can be elucidated and it is seen that the PE in the aggregates retains a relatively high freedom of movement. We proceeded to investigate the influence of the surfactant concentration and the surfactant type on structure and dynamics of the mixed aggregates. It is seen that the structural parameters of the aggregates depend very little on the surfactant concentration and headgroup. However, it is crucial to incorporate a sufficient amount of PE in the aggregates to increase the viscosity of the aggregates. By comparing viscous samples at 1 wt. % PE concentration with samples at a PE concentration of 0.3 wt. %, where no significant increase in viscosity is observed, we find that similar aggregates are formed already at this lower PE concentrations. However, the amount of PE incorporated in them is insufficient to interconnect several PE chains and therefore, they do not increase viscosity. So, our detailed investigation combining contrast variation SANS and NSE does not only allow to explain the viscosity behavior but also to deduced detailed information regarding the structures and

  10. The Molecular Era of Surfactant Biology

    OpenAIRE

    Whitsett, Jeffrey A.

    2014-01-01

    Advances in the physiology, biochemistry, molecular and cell biology of the pulmonary surfactant system transformed the clinical care and outcome of preterm infants with respiratory distress syndrome. The molecular era of surfactant biology provided genetic insights into the pathogenesis of pulmonary disorders, previously termed “idiopathic” that affect newborn infants, children and adults. Knowledge related to the structure and function of the surfactant proteins and their roles in alveolar ...

  11. The Biophysical Function of Pulmonary Surfactant

    OpenAIRE

    Rugonyi, Sandra; Biswas, Samares C.; Hall, Stephen B.

    2008-01-01

    Pulmonary surfactant lowers surface tension in the lungs. Physiological studies indicate two key aspects of this function: that the surfactant film forms rapidly; and that when compressed by the shrinking alveolar area during exhalation, the film reduces surface tension to very low values. These observations suggest that surfactant vesicles adsorb quickly, and that during compression, the adsorbed film resists the tendency to collapse from the interface to form a three-dimensional bulk phase....

  12. Acute Pathophysiological Effects of Intratracheal Instillation of Budesonide and Exogenous Surfactant in a Neonatal Surfactant-depleted Piglet Model

    Directory of Open Access Journals (Sweden)

    Chia-Feng Yang

    2010-08-01

    Conclusions: Intratracheal instillation of surfactant or surfactant plus budesonide can improve oxygenation and pulmonary histologic outcome in neonatal surfactant-depleted lungs. The additional use of budesonide does not disturb the function of the exogenous surfactant. Intratracheal administration of a corticosteroid combined with surfactant may be an effective method for alleviating local pulmonary inflammation in severe RDS.

  13. A Molecular Dynamics Study of Single-Walled Carbon Nanotubes (SWCNTs) Dispersed in Bile Salt Surfactants

    Science.gov (United States)

    Phelan, Frederick, Jr.; Sun, Huai

    2014-03-01

    Single-walled carbon nanotubes (SWNCTs) are materials with structural, electronic and optical properties that make them attractive for a myriad of advanced technology applications. A practical barrier to their use is that SWCNT synthesis techniques produce heterogeneous mixtures of varying lengths and chirality, whereas applications generally require tubes with narrow size distributions and individual type. Most separation techniques currently in use to obtain monodisperse tube fractions rely on dispersion of these materials in aqueous solution using surfactants. The dispersion process results in a mixture of colloidal structures in which individual tubes are dispersed and contained in a surfactant shell. Understanding the structure and properties of the SWCNT-surfactant complex at the molecular level, and how this is affected by chirality, is key to understanding and improving separations processes. In this study, we use molecular dynamics (MD) simulations to study the structure and properties of SWCNT-surfactant colloidal complexes. We tested a number of methods and protocols in order to build an accurate model for simulating SWCNT systems for a variety of bile salt surfactants as well as anionic co-surfactants, components that are widely used and important in experimental separation studies at NIST. The custom force field parameters used here will be stored in WebFF, a Web-hosted smart force-field repository for polymeric and organic materials being developed at NIST for the Materials Genome Initiative.

  14. Solubilization of Hydrophobic Dyes in Surfactant Solutions

    Directory of Open Access Journals (Sweden)

    Ali Reza Tehrani-Bagha

    2013-02-01

    Full Text Available In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, and temperature on dye solubilization has been discussed. Surfactant self-assemble into micelles in aqueous solution and below the concentration where this occurs—the critical micelle concentration (CMC—there is no solubilization. Above the CMC, the amount of solubilized dye increases linearly with the increase in surfactant concentration. It is demonstrated that different surfactants work best for different dyes. In general, nonionic surfactants have higher solubilization power than anionic and cationic surfactants. It is likely that the reason for the good performance of nonionic surfactants is that they allow dyes to be accommodated not only in the inner, hydrocarbon part of the micelle but also in the headgroup shell. It is demonstrated that the location of a dye in a surfactant micelle can be assessed from the absorption spectrum of the dye-containing micellar solution.

  15. Remediation using trace element humate surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Riddle, Catherine Lynn; Taylor, Steven Cheney; Bruhn, Debra Fox

    2016-08-30

    A method of remediation at a remediation site having one or more undesirable conditions in which one or more soil characteristics, preferably soil pH and/or elemental concentrations, are measured at a remediation site. A trace element humate surfactant composition is prepared comprising a humate solution, element solution and at least one surfactant. The prepared trace element humate surfactant composition is then dispensed onto the remediation site whereby the trace element humate surfactant composition will reduce the amount of undesirable compounds by promoting growth of native species activity. By promoting native species activity, remediation occurs quickly and environmental impact is minimal.

  16. Fluorescent visualization of a spreading surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Fallest, David W; Lichtenberger, Adele M; Fox, Christopher J; Daniels, Karen E, E-mail: kdaniel@ncsu.ed [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)

    2010-07-15

    The spreading of surfactants on thin films is an industrially and medically important phenomenon, but the dynamics are highly nonlinear and visualization of the surfactant dynamics has been a long-standing experimental challenge. We perform the first quantitative, spatiotemporally resolved measurements of the spreading of an insoluble surfactant on a thin fluid layer. During the spreading process, we directly observe both the radial height profile of the spreading droplet and the spatial distribution of the fluorescently tagged surfactant. We find that the leading edge of a spreading circular layer of surfactant forms a Marangoni ridge in the underlying fluid, with a trough trailing the ridge as expected. However, several novel features are observed using the fluorescence technique, including a peak in the surfactant concentration that trails the leading edge, and a flat, monolayer-scale spreading film that differs from concentration profiles predicted by current models. Both the Marangoni ridge and the surfactant leading edge can be described to spread as R{approx}t{sup {delta}}. We find spreading exponents {delta}{sub H}{approx}0.30 and {delta}{sub {Gamma}}{approx}0.22 for the ridge peak and surfactant leading edge, respectively, which are in good agreement with theoretical predictions of {delta}=1/4. In addition, we observe that the surfactant leading edge initially leads the peak of the Marangoni ridge, with the peak later catching up to the leading edge.

  17. Surfactant nebulisation : lung function, surfactant distribution and pulmonary blood flow distribution in lung lavaged rabbits

    NARCIS (Netherlands)

    Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

    1997-01-01

    Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform

  18. Photochemical key steps in the synthesis of surfactants from furfural-derived intermediates.

    Science.gov (United States)

    Gassama, Abdoulaye; Ernenwein, Cédric; Hoffmann, Norbert

    2009-01-01

    Furfural is oxidized to 2[5H]-furanone by using hydrogen peroxide or to 5-hydroxy-2[5H]-furanone by using photo-oxygenation. An amine function is introduced by photochemically induced radical addition of tertiairy amines, some of which carry an n-alkyl side chain as hydrophobic moiety. These amines are produced from fatty aldehydes and cyclic secondary amines. The resulting adducts are transformed into amphoteric surfactants possessing an ammonium and a carboxylate function. Amphoteric (pK(N) and isoelectric point) and surfactant properties such as the critical micelle concentration and the adsorption efficiency are determined.

  19. Electrostatic self-assembly in polyelectrolyte-neutral block copolymers and oppositely charged surfactant solutions

    International Nuclear Information System (INIS)

    Berret, J.-F.Jean-Francois; Oberdisse, Julian

    2004-01-01

    We report on small-angle neutron scattering (SANS) of colloidal complexes resulting from the electrostatic self-assembly of polyelectrolyte-neutral copolymers and oppositely charged surfactants. The polymers are double hydrophilic block copolymers of low molecular weight (between 5000 and 50 000 g/mol). One block is a polyelectrolyte chain, which can be either positively or negatively charged, whereas the second block is neutral and in good solvent conditions. In aqueous solutions, surfactants with an opposite charge to that of the polyelectrolyte interact strongly with these copolymers. The two species associate into stable 100 nm-colloidal complexes which exhibit a core-shell microstructure. For different polymer/surfactant couples, we have shown that the core is constituted from densely packed surfactant micelles connected by the polyelectrolyte chains. The outer part of the complex is a corona formed by the neutral soluble chains. Using a model of aggregation based on a Monte-Carlo algorithm, we have simulated the internal structure of the aggregates. The model assumes spherical cages containing one to several hundreds of micelles in a closely packed state. The agreement between the model and the data is remarkable

  20. Production of a biological surfactant

    Directory of Open Access Journals (Sweden)

    N. Gladys Rosero

    2002-01-01

    Full Text Available This paper summarizes the scale up work performed at the Colombian Petroleum Institute on a process to produce at pilot plant level a biosurfactant of the rhamnolipid type. By examination of both the activation conditions of the microorganism and design aspects of the broth, a stable condition was achieved which consistently triggers the production mechanisms and thus it was obtained a significant increment in biosurfactant productivity. The biological surfactant exhibited high efficiency in applications such as hydrocarbon biodegradation in saline environments, corrosion inhibition, and crude oil recovery from storage tank bottom sludges.

  1. Cryochromatography: a method for the separation of phosphoglycerides according to the number and length of saturated fatty acid components

    International Nuclear Information System (INIS)

    Henderson, R.F.; Clayton, M.H.

    1974-01-01

    A thin layer chromatographic method utilizing ultracold temperatures has been developed to separate phosphoglycerides containing only long-chain saturated fatty acids from phosphoglycerides containing fatty acids with any degree of unsaturation. The method is direct, nondiluting, and nondestructive. Since the surfactant lipids found in lung contain only long-chain, saturated fatty acids, the method should be particularly useful to those in lung lipid research. Studies on the uptake of labeled precursors into the lung surfactant lipids as well as work on quantitation of surfactant lecithins in the lung can be facilitated by this method. (U.S.)

  2. Solvation thermodynamics of phenylalcohols in lamellar phase surfactant dispersions

    International Nuclear Information System (INIS)

    Martyniak, A.; Scheuermann, R.; Dilger, H.; Tucker, I.M.; Burkert, T.; Hashmi, A.S.K.; Vujosevic', D.; Roduner, E.

    2006-01-01

    The distribution and the stability of five phenylalcohols in a lamellar phase composed of simple bilayers separated by water at 298 and 348K is explored using avoided-level-crossing muon-spin resonance (ALC-μSR). The dependence of the alignment of the bilayer chains on temperature appears to be a crucial factor determining the phenylalcohol partitioning: increasing order of the surfactant tails leads to expulsion of the solute. Moreover, we observed a systematic trend, the longer the chain the deeper the phenyl group dips into the lipid bilayer. Recent studies have shown that the hydrophobic effect is adequate to describe membrane partitioning of small amphiphilic molecules. The solvation thermodynamic properties ΔG sol , ΔH sol , and ΔS sol which determine the solute transfer from the double layer into water prove that the distribution also strongly depends on shape, chemical nature and different structure of phenylalcohols

  3. Solvation thermodynamics of phenylalcohols in lamellar phase surfactant dispersions

    Energy Technology Data Exchange (ETDEWEB)

    Martyniak, A. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Scheuermann, R. [Laboratory for muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Dilger, H. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Tucker, I.M. [Unilever Research and Development, Port Sunlight, Wirral CH63 3JW (United Kingdom); Burkert, T. [Institut fuer Organische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Hashmi, A.S.K. [Institut fuer Organische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Vujosevic' , D. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Roduner, E. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)]. E-mail: e.roduner@ipc.uni-stuttgart.de

    2006-03-31

    The distribution and the stability of five phenylalcohols in a lamellar phase composed of simple bilayers separated by water at 298 and 348K is explored using avoided-level-crossing muon-spin resonance (ALC-{mu}SR). The dependence of the alignment of the bilayer chains on temperature appears to be a crucial factor determining the phenylalcohol partitioning: increasing order of the surfactant tails leads to expulsion of the solute. Moreover, we observed a systematic trend, the longer the chain the deeper the phenyl group dips into the lipid bilayer. Recent studies have shown that the hydrophobic effect is adequate to describe membrane partitioning of small amphiphilic molecules. The solvation thermodynamic properties {delta}G{sub sol}, {delta}H{sub sol}, and {delta}S{sub sol} which determine the solute transfer from the double layer into water prove that the distribution also strongly depends on shape, chemical nature and different structure of phenylalcohols.

  4. Surfactant protein D in newborn infants

    DEFF Research Database (Denmark)

    Dahl, Marianne; Juvonen, Pekka Olavi; Holmskov, Uffe

    2005-01-01

    Surfactant protein D (SP-D) is a collectin that plays an important role in the innate immune system. The role of SP-D in the metabolism of surfactant is as yet quite unclear. The aims of this study were to establish normal values of SP-D in the umbilical cord blood and capillary blood of mature...

  5. Surfactant screening of diesel-contaminated soil

    International Nuclear Information System (INIS)

    Peters, R.W.; Shem, L.; Montemagno, C.D.; Lewis, B.

    1991-01-01

    At one installation, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of the research program in which 21 surfactants were screened for possible use to mobilize the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on actual contaminated soil samples obtained from the site

  6. Effect of Source, Surfactant, and Deposition Process on Electronic Properties of Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Dheeraj Jain

    2011-01-01

    Full Text Available The electronic properties of arrays of carbon nanotubes from several different sources differing in the manufacturing process used with a variety of average properties such as length, diameter, and chirality are studied. We used several common surfactants to disperse each of these nanotubes and then deposited them on Si wafers from their aqueous solutions using dielectrophoresis. Transport measurements were performed to compare and determine the effect of different surfactants, deposition processes, and synthesis processes on nanotubes synthesized using CVD, CoMoCAT, laser ablation, and HiPCO.

  7. GENOMIC DNA-FINGERPRINTING OF CLINICAL HAEMOPHILUS-INFLUENZAE ISOLATES BY POLYMERASE CHAIN-REACTION AMPLIFICATION - COMPARISON WITH MAJOR OUTER-MEMBRANE PROTEIN AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS

    NARCIS (Netherlands)

    VANBELKUM, A; DUIM, B; REGELINK, A; MOLLER, L; QUINT, W; VANALPHEN, L

    Non-capsulate strains of Haemophilus influenzae were genotyped by analysis of variable DNA segments obtained by amplification of genomic DNA with the polymerase chain reaction (PCR fingerprinting). Discrete fragments of 100-2000 bp were obtained. The reproducibility of the procedure was assessed by

  8. Phase Behaviour Study of Swiftlet Nest Using Virgin Coconut Oil with Non-Ionic Surfactants

    International Nuclear Information System (INIS)

    Siti Salwa Abd Gani; Siti Zulaika Adisah; Siti Salwa Abd Gani

    2015-01-01

    Virgin coconut oil (VCO) is the oil that obtained from fresh and mature kernel of the coconut by mechanical or natural means with or without the application of heat, which does not lead to alteration of the nature of the oil. It have advantages such as strengthens the immune system because of its lauric acid content. It also has medium-chain fatty acids which heighten metabolism and energy, thus stimulating the thyroid. Swiftlet nest as an active ingredient need to be dispersed in a carrier system. Thus, ternary phase diagrams were constructed to find the suitable and stable system for it. The phase behavior of systems has been investigated by constructing ternary phase diagrams consisting of non-ionic surfactants/VCO:bird nest/water. The surfactants used were Sorbitan tri-oleate (Span 85), Sorbitan mono-oleate (Span 80), Sorbitan monolaurate (Span 20), Polyoxyethylene(20) sorbitan tri-oleate (Tween 85) and Polyoxyethylene (20) sorbitan mono-oleate (Tween 80). These systems include several phase regions such as homogeneous, isotropic, two-phase and three-phase regions. Different hydrophilic lipophilic balance (HLB) value of non-ionic surfactants exhibit different ternary diagram characteristics. A lower HLB shows a more oil-soluble and a more water-soluble surfactant (larger homogeneous and isotropic region in ternary phase diagrams) whereas high value of HLB shows the reverse of that result. The results show that the T85/VCO:bird nest/water system gave better performance than the other four individual surfactant systems. As a conclusion, high hydrophilic lipophilic balance (HLB) values of surfactant were found to be a good surfactant for the formulation of VCO:bird nest emulsion for cosmetic and pharmaceutical purposes. (author)

  9. Surfactant replacement therapy--economic impact.

    Science.gov (United States)

    Pejaver, R K; al Hifzi, I; Aldussari, S

    2001-06-01

    Surfactant replacement is an effective treatment for neonatal respiratory distress syndrome. (RDS). As widespread use of surfactant is becoming a reality, it is important to assess the economic implications of this new form of therapy. A comparison study was carried out at the Neonatal Intensive Care Unit (NICU) of Northwest Armed Forces Hospital, Saudi Arabia. Among 75 infants who received surfactant for RDS and similar number who were managed during time period just before the surfactant was available, but by set criteria would have made them eligible for surfactant. All other management modalities except surfactant were the same for all these babies. Based on the intensity of monitoring and nursing care required by the baby, the level of care was divided as: Level IIIA, IIIB, Level II, Level I. The cost per day per bed for each level was calculated, taking into account the use of hospital immovable equipment, personal salaries of nursing, medical, ancillary staff, overheads and maintenance, depreciation and replacement costs. Medications used, procedures done, TPN, oxygen, were all added to individual patient's total expenditure. 75 infants in the Surfactant group had 62 survivors. They spent a total of 4300 days in hospital. (av 69.35) Out of which 970 d (av 15.65 per patient) were ventilated days. There were 56 survivors in the non-surfactant group of 75. They had spent a total of 5023 days in the hospital (av 89.69/patient) out of which 1490 were ventilated days (av 26.60 d). Including the cost of surfactant (two doses), cost of hospital stay for each infant taking the average figures of stay would be SR 118, 009.75 per surfactant treated baby and SR 164, 070.70 per non-surfactant treated baby. The difference of 46,061 SR is 39.03% more in non-surfactant group. One Saudi rial = 8 Rs (approx at the time study was carried out.) Medical care cost varies from place to place. However, it is definitely cost-effective where surfactant is concerned. Quality adjusted

  10. Evaluation of the mechanism of skin enhancing surfactants on the biomembrane of shed snake skin.

    Science.gov (United States)

    Wonglertnirant, Nanthida; Ngawhirunpat, Tanasait; Kumpugdee-Vollrath, Mont

    2012-01-01

    The aim of the present work was to investigate the effects of different surfactants at various concentrations as a skin penetration enhancer through the biomembrane of the shed skin of Naja kaouthia. Additionally, the enhancer mechanism(s) of each class of surfactants were evaluated using physical characterization techniques, such as scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and small and wide angle X-ray scattering (SWAXS). Our results showed that skin permeability increased with increasing concentrations of surfactants and the degree of increase was higher for the model hydrophilic permeant, deuterium dioxide (D(2)O), than the lipophilic permeant, ketoprofen (KP). Ionic surfactants, sodium lauryl sulfate (SLS) and cetyl trimethyl ammonium bromide (CTAB), demonstrated higher enhancement ability than the polyoxyethylene (20) sorbitan mono-oleate (Tween 80) non-ionic surfactant, which was consistent with the results from physical characterization studies. Increasing amounts of permeated drug resulted in an increase in membrane interactions. From our observations, it can be assumed that SLS and CTAB can be localized inside the biomembrane and thereby enhance drug permeation mainly through interactions with intercellular lipids in the stratum corneum (SC) and the creation of a perturbed microenvironment among lipid alkyl chains and polar head groups.

  11. Rhamnolipids--next generation surfactants?

    Science.gov (United States)

    Müller, Markus Michael; Kügler, Johannes H; Henkel, Marius; Gerlitzki, Melanie; Hörmann, Barbara; Pöhnlein, Martin; Syldatk, Christoph; Hausmann, Rudolf

    2012-12-31

    The demand for bio-based processes and materials in the petrochemical industry has significantly increased during the last decade because of the expected running out of petroleum. This trend can be ascribed to three main causes: (1) the increased use of renewable resources for chemical synthesis of already established product classes, (2) the replacement of chemical synthesis of already established product classes by new biotechnological processes based on renewable resources, and (3) the biotechnological production of new molecules with new features or better performances than already established comparable chemically synthesized products. All three approaches are currently being pursued for surfactant production. Biosurfactants are a very promising and interesting substance class because they are based on renewable resources, sustainable, and biologically degradable. Alkyl polyglycosides are chemically synthesized biosurfactants established on the surfactant market. The first microbiological biosurfactants on the market were sophorolipids. Of all currently known biosurfactants, rhamnolipids have the highest potential for becoming the next generation of biosurfactants introduced on the market. Although the metabolic pathways and genetic regulation of biosynthesis are known qualitatively, the quantitative understanding relevant for bioreactor cultivation is still missing. Additionally, high product titers have been exclusively described with vegetable oil as sole carbon source in combination with Pseudomonas aeruginosa strains. Competitive productivity is still out of reach for heterologous hosts or non-pathogenic natural producer strains. Thus, on the one hand there is a need to gain a deeper understanding of the regulation of rhamnolipid production on process and cellular level during bioreactor cultivations. On the other hand, there is a need for metabolizable renewable substrates, which do not compete with food and feed. A sustainable bioeconomy approach should

  12. Surfactants tailored by the class Actinobacteria

    Directory of Open Access Journals (Sweden)

    Johannes H Kügler

    2015-03-01

    Full Text Available Gloablly, the drive towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application.

  13. Surfactants tailored by the class Actinobacteria

    Science.gov (United States)

    Kügler, Johannes H.; Le Roes-Hill, Marilize; Syldatk, Christoph; Hausmann, Rudolf

    2015-01-01

    Globally the change towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application. PMID:25852670

  14. DNA compaction by azobenzene-containing surfactant

    International Nuclear Information System (INIS)

    Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Santer, Svetlana; Morozova, Elena; Lysyakova, Ludmila; Kasyanenko, Nina

    2011-01-01

    We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

  15. Interactions between ionic liquid surfactant [C12mim]Br and DNA in dilute brine.

    Science.gov (United States)

    He, Yunfei; Shang, Yazhuo; Liu, Zhenhai; Shao, Shuang; Liu, Honglai; Hu, Ying

    2013-01-01

    Interactions between ionic liquid surfactant [C(12)mim]Br and DNA in dilute brine were investigated in terms of various experimental methods and molecular dynamics (MD) simulation. It was shown that the aggregation of [C(12)mim]Br on DNA chains is motivated not only by electrostatic attractions between DNA phosphate groups and [C(12)mim]Br headgroups but also by hydrophobic interactions among [C(12)mim]Br alkyl chains. Isothermal titration calorimetry analysis indicated that the [C(12)mim]Br aggregation in the presence and absence of DNA are both thermodynamically favored driven by enthalpy and entropy. DNA undergoes size transition and conformational change induced by [C(12)mim]Br, and the charges of DNA are neutralized by the added [C(12)mim]Br. Various microstructures were observed such as DNA with loose coil conformation in nature state, necklace-like structures, and compact spherical aggregates. MD simulation showed that the polyelectrolyte collapses upon the addition of oppositely charged surfactants and the aggregation of surfactants around the polyelectrolyte was reaffirmed. The simulation predicted the gradual neutralization of the negatively charged polyelectrolyte by the surfactant, consistent with the experimental results. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Influence of surfactants in forced dynamic dewetting.

    Science.gov (United States)

    Henrich, Franziska; Fell, Daniela; Truszkowska, Dorota; Weirich, Marcel; Anyfantakis, Manos; Nguyen, Thi-Huong; Wagner, Manfred; Auernhammer, Günter K; Butt, Hans-Jürgen

    2016-09-20

    In this work we show that the forced dynamic dewetting of surfactant solutions depends sensitively on the surfactant concentration. To measure this effect, a hydrophobic rotating cylinder was horizontally half immersed in aqueous surfactant solutions. Dynamic contact angles were measured optically by extrapolating the contour of the meniscus to the contact line. Anionic (sodium 1-decanesulfonate, S-1DeS), cationic (cetyl trimethylammonium bromide, CTAB) and nonionic surfactants (C 4 E 1 , C 8 E 3 and C 12 E 5 ) with critical micelle concentrations (CMCs) spanning four orders of magnitude were used. The receding contact angle in water decreased with increasing velocity. This decrease was strongly enhanced when adding surfactant, even at surfactant concentrations of 10% of the critical micelle concentration. Plots of the receding contact angle-versus-velocity almost superimpose when being plotted at the same relative concentration (concentration/CMC). Thus the rescaled concentration is the dominating property for dynamic dewetting. The charge of the surfactants did not play a role, thus excluding electrostatic effects. The change in contact angle can be interpreted by local surface tension gradients, i.e. Marangoni stresses, close to the three-phase contact line. The decrease of dynamic contact angles with velocity follows two regimes. Despite the existence of Marangoni stresses close to the contact line, for a dewetting velocity above 1-10 mm s -1 the hydrodynamic theory is able to describe the experimental results for all surfactant concentrations. At slower velocities an additional steep decrease of the contact angle with velocity was observed. Particle tracking velocimetry showed that the flow profiles do not differ with and without surfactant on a scales >100 μm.

  17. BINDING OF IONIC SURFACTANTS ON OPPOSITELY CHARGED POLYELECTROLYTES OBSERVED BY FLUORESCENCE METHODS

    Institute of Scientific and Technical Information of China (English)

    Zhen Tong; Chao-yang Wang; Bi-ye Ren; Xin-xing Liu; Fang Zeng

    2003-01-01

    Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymersurfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.

  18. Small angle neutron scattering study of doxorubicin–surfactant ...

    Indian Academy of Sciences (India)

    The binding affinity of doxorubicin within the micelle carrier is enhanced through complex formation of drug and anionic surfactant, aerosol OT (AOT). Electrostatic binding of doxorubicin with negatively charged surfactants leads to the formation of hydrophobic drug–surfactant complexes. Surfactant-induced partitioning of ...

  19. Adsorption at air-water and oil-water interfaces and self-assembly in aqueous solution of ethoxylated polysorbate nonionic surfactants.

    Science.gov (United States)

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun X; Petkov, Jordan T; Tucker, Ian; Webster, John R P; Terry, Ann E

    2015-03-17

    The Tween nonionic surfactants are ethoxylated sorbitan esters, which have 20 ethylene oxide groups attached to the sorbitan headgroup and a single alkyl chain, lauryl, palmityl, stearyl, or oleyl. They are an important class of surfactants that are extensively used in emulsion and foam stabilization and in applications associated with foods, cosmetics and pharmaceuticals. A range of ethoxylated polysorbate surfactants, with differing degrees of ethoxylation from 3 to 50 ethylene oxide groups, have been synthesized and characterized by neutron reflection, small-angle neutron scattering, and surface tension. In conjunction with different alkyl chain groups, this provides the opportunity to modify their surface properties, their self-assembly in solution, and their interaction with macromolecules, such as proteins. Adsorption at the air-water and oil-water interfaces and solution self-assembly of the range of ethoxylated polysorbate surfactants synthesized are presented and discussed.

  20. Composition driven monolayer to bilayer transformation in a surfactant intercalated Mg-Al layered double hydroxide.

    Science.gov (United States)

    Naik, Vikrant V; Chalasani, Rajesh; Vasudevan, S

    2011-03-15

    The structure and organization of dodecyl sulfate (DDS) surfactant chains intercalated in an Mg-Al layered double hydroxide (LDH), Mg(1-x)Alx(OH)2, with differing Al/Mg ratios has been investigated. The Mg-Al LDHs can be prepared over a range of compositions with x varying from 0.167 to 0.37 and therefore provides a simple system to study how the organization of the alkyl chains of the intercalated DDS anions change with packing density; the Al/Mg ratio or x providing a convenient handle to do so. Powder X-ray diffraction measurements showed that at high packing densities (x ≥ 0.3) the alkyl chains of the intercalated dodecyl sulfate ions are anchored on opposing LDH sheets and arranged as bilayers with an interlayer spacing of ∼27 Å. At lower packing densities (x flat in the galleries with an interlayer spacing of ∼8 Å. For the in between compositions, 0.2 ≤ x organization of the chains and the interlayer spacing. The simulations are able to reproduce the composition driven monolayer to bilayer transformation in the arrangement of the intercalated surfactant chains and in addition provide insights into the factors that decide the arrangement of the surfactant chains in the two situations. In the bilayer arrangement, it is the dispersive van der Waals interactions between chains in opposing layers of the anchored bilayer that is responsible for the cohesive energy of the solid whereas at lower packing densities, where a monolayer arrangement is favored, Coulomb interactions between the positively charged Mg-Al LDH sheets and the negatively charged headgroup of the DDS anion dominate.

  1. Surfactant adsorption study in sandstone for enhanced oil recovery; Estudo da adsorcao de tensoativos em arenitos para recuperacao avancada de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Curbelo, Fabiola D.S.; Santanna, Vanessa C.; Barros Neto, Eduardo L. de; Dutra Junior, Tarcilio V.; Dantas Neto, Afonso A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Engenharia Quimica; Garnica, Alfredo I.C. [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Dept. de Tecnologia Quimica e de Alimentos; Lucena Neto, Marciano [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Dantas, Tereza N.C. [Faculdade Natalense para o Desenvolvimento do RN (FARN), Natal, RN (Brazil)

    2004-07-01

    Adsorption of surfactants from aqueous solutions in porous media is very important in Enhanced Oil Recovery (EOR) of oil reservoirs because surfactant loss due to adsorption on the reservoir rocks weakens the effectiveness of the injected chemical slug in reducing oil-water tension (IFT) and makes the process uneconomical. In this paper, two nonionic surfactants, such as alkyl phenol polyoxyethylene, with different ethoxylation degrees were studied, ENP95 and ENP150. The results of flow experiments of surfactant solutions in porous media showed that adsorption was higher for ENP95 because it has smaller ethoxylation degree than ENP150. This occurs what with increasing length of the head group, the molecules become more hydrophilic and, in associated structures, the steric hindrance between the head groups increases. Generally speaking, adsorption appears to be a cooperative process involving lateral interaction between surfactant and weak interaction with the solid surface. (author)

  2. Lung surfactant levels are regulated by Ig-Hepta/GPR116 by monitoring surfactant protein D.

    Directory of Open Access Journals (Sweden)

    Taku Fukuzawa

    Full Text Available Lung surfactant is a complex mixture of lipids and proteins, which is secreted from the alveolar type II epithelial cell and coats the surface of alveoli as a thin layer. It plays a crucial role in the prevention of alveolar collapse through its ability to reduce surface tension. Under normal conditions, surfactant homeostasis is maintained by balancing its release and the uptake by the type II cell for recycling and the internalization by alveolar macrophages for degradation. Little is known about how the surfactant pool is monitored and regulated. Here we show, by an analysis of gene-targeted mice exhibiting massive accumulation of surfactant, that Ig-Hepta/GPR116, an orphan receptor, is expressed on the type II cell and sensing the amount of surfactant by monitoring one of its protein components, surfactant protein D, and its deletion results in a pulmonary alveolar proteinosis and emphysema-like pathology. By a coexpression experiment with Sp-D and the extracellular region of Ig-Hepta/GPR116 followed by immunoprecipitation, we identified Sp-D as the ligand of Ig-Hepta/GPR116. Analyses of surfactant metabolism in Ig-Hepta(+/+ and Ig-Hepta(-/- mice by using radioactive tracers indicated that the Ig-Hepta/GPR116 signaling system exerts attenuating effects on (i balanced synthesis of surfactant lipids and proteins and (ii surfactant secretion, and (iii a stimulating effect on recycling (uptake in response to elevated levels of Sp-D in alveolar space.

  3. The Accelerated Late Adsorption of Pulmonary Surfactant

    OpenAIRE

    Loney, Ryan W.; Anyan, Walter R.; Biswas, Samares C.; Rananavare, Shankar B.; Hall, Stephen B.

    2011-01-01

    Adsorption of pulmonary surfactant to an air−water interface lowers surface tension (γ) at rates that initially decrease progressively, but which then accelerate close to the equilibrium γ. The studies here tested a series of hypotheses concerning mechanisms that might cause the late accelerated drop in γ. Experiments used captive bubbles and a Wilhelmy plate to measure γ during adsorption of vesicles containing constituents from extracted calf surfactant. The faster fall in γ reflects faster...

  4. Poly(ethylene oxide) surfactant polymers

    OpenAIRE

    VACHEETHASANEE, KATANCHALEE; WANG, SHUWU; QIU, YONGXING; MARCHANT, ROGER E.

    2004-01-01

    We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly (ethyleneoxide) (PEO) were simultaneously att...

  5. Study of conformation and dynamic of surfactant molecules in graphite oxide via NMR

    Energy Technology Data Exchange (ETDEWEB)

    Ai, X.Q. [Jiangsu Second Normal University, College of Physics and Electronic Engineering, Nanjing (China); Ma, L.G. [Nanjing Xiaozhuang University, School of Electronic Engineering, Nanjing (China)

    2016-08-15

    The conformation and dynamic of surfactant in graphite oxide (GO) was investigated by solid-state {sup 13}C magic-angle-spinning NMR and {sup 1}H-{sup 13}C cross-polarization/magic-angle-spinning NMR spectra. The conformation ordering of the alkyl chains in the confined system shows strong dependence on its orientation. While the alkyl chains parallel to the GO layer in lateral monolayer arrangement are in gauche conformation in addition to a small amount of all-trans conformation, those with orientation radiating away from the GO in paraffin bilayer arrangement is in all-trans conformation in addition to some gauche conformation even though high-order diffraction peaks appears. NMR results suggest that the least mobile segment is located at the GO-surfactant interface corresponding to the N-methylene group. Further from it, the mobility of the alkyl chain increases. The terminal methyl and N-methyl carbon groups have the highest mobile. The chains in all-trans conformational state are characterized as more rigid than chains with gauche conformation; each segment of the confined alkyl chains with the lateral monolayer arrangement exhibits less mobility as compared to that with the paraffin bilayer arrangement. (orig.)

  6. Falling chains

    OpenAIRE

    Wong, Chun Wa; Yasui, Kosuke

    2005-01-01

    The one-dimensional fall of a folded chain with one end suspended from a rigid support and a chain falling from a resting heap on a table is studied. Because their Lagrangians contain no explicit time dependence, the falling chains are conservative systems. Their equations of motion are shown to contain a term that enforces energy conservation when masses are transferred between subchains. We show that Cayley's 1857 energy nonconserving solution for a chain falling from a resting heap is inco...

  7. Telomere Length and Mortality

    DEFF Research Database (Denmark)

    Kimura, Masayuki; Hjelmborg, Jacob V B; Gardner, Jeffrey P

    2008-01-01

    Leukocyte telomere length, representing the mean length of all telomeres in leukocytes, is ostensibly a bioindicator of human aging. The authors hypothesized that shorter telomeres might forecast imminent mortality in elderly people better than leukocyte telomere length. They performed mortality...

  8. Adsorption of diclofenac onto organoclays: Effects of surfactant and environmental (pH and temperature) conditions

    OpenAIRE

    De Oliveira , Tiago; Guégan , Régis; Thiebault , Thomas; Le Milbeau , Claude; Muller , Fabrice; Teixeira , Vinicius; Giovanela , Marcelo; Boussafir , Mohammed

    2017-01-01

    Accepted Manuscript; International audience; Among pharmaceutical products (PPs) recalcitrant to water treatments, diclofenac shows a high toxicity and remains at high concentration in natural aquatic environments. The aim of this study concerns the understanding of the adsorption mechanism of this anionic PP onto two organoclays prepared with two long-alkyl chains cationic surfactants showing different chemical nature for various experimental pH and temperature conditions. The experimental d...

  9. Spectroscopic investigation on the interaction of some surfactant-cobalt(III) complexes with serum albumins

    Energy Technology Data Exchange (ETDEWEB)

    Vignesh, Gopalaswamy; Nehru, Selvan; Manojkumar, Yesaiyan; Arunachalam, Sankaralingam, E-mail: arunasurf@yahoo.com

    2014-01-15

    The interaction of HSA/BSA with single and double chain surfactant-cobalt(III) complexes, cis-[Co(phen){sub 2}(UA)Cl](ClO{sub 4}){sub 2}·2H{sub 2}O (1), cis-[Co(phen){sub 2}(UA){sub 2}](ClO{sub 4}){sub 3}·2H{sub 2}O (2), cis-[Co(en){sub 2}(UA)Cl](ClO{sub 4}){sub 2}·2H{sub 2}O (3), cis-[Co(en){sub 2}(UA){sub 2}](ClO{sub 4}){sub 3}·2H{sub 2}O (4), were investigated by steady state fluorescence, UV–vis absorption, synchronous, three dimensional fluorescence and circular dichroism spectroscopy. The results reveal that the quenching of HSA/BSA by all the four complexes takes place through static mechanism. The binding constant, binding sites and thermodymamic parameter were calculated. The results illustrate that the double chain surfactant-cobalt(III) complexes bind more strongly than the corresponding single chain complexes. The distance between donor (HSA/BSA) and acceptor (surfactant-cobalt(III) complexes) was obtained according to FRET. The results of synchronous, three dimensional and circular dichroism spectroscopy studies show that all the complexes caused considerable amount of conformational and some amount of environment changes in HSA/BSA. -- Highlights: • Binding of single and double chain surfactant-cobalt(III) complexes with serum albumins. • Hydrophobic attraction plays a major role in the binding process. • Binding induces considerable amount of conformational changes in the protein.

  10. Surfactant properties of human meibomian lipids.

    Science.gov (United States)

    Mudgil, Poonam; Millar, Thomas J

    2011-03-25

    Human meibomian lipids are the major part of the lipid layer of the tear film. Their surfactant properties enable their spread across the aqueous layer and help maintain a stable tear film. The purpose of this study was to investigate surfactant properties of human meibomian lipids in vitro and to determine effects of different physical conditions such as temperature and increased osmolarity, such as occur in dry eye, on these properties. Human meibomian lipids were spread on an artificial tear solution in a Langmuir trough. The lipid films were compressed and expanded to record the surface pressure-area (Π-A) isocycles. The isocycles were recorded under different physical conditions such as high pressure, increasing concentration and size of divalent cations, increasing osmolarity, and varying temperature. Π-A isocycles of meibomian lipids showed that they form liquid films that are compressible and multilayered. The isocycles were unaffected by increasing concentration or size of divalent cations and increasing osmolarity in the subphase. Temperature had a marked effect on the lipids. Increase in temperature caused lipid films to become fluid, an expected feature, but decrease in temperature unexpectedly caused expansion of lipids and an increase in pressure suggesting enhanced surfactant properties. Human meibomian lipids form highly compressible, non-collapsible, multilayered liquid films. These lipids have surfactants that allow them to spread across an aqueous subphase. Their surfactant properties are unaffected by increasing divalent cations or hyperosmolarity but are sensitive to temperature. Cooling of meibomian lipids enhances their surfactant properties.

  11. Conductive Supramolecular Architecture Constructed from Polyoxovanadate Cluster and Heterocyclic Surfactant

    Directory of Open Access Journals (Sweden)

    Toshiyuki Misawa

    2018-01-01

    Full Text Available Proton-conductive solid electrolytes are significant for fuel-cell battery technology. Especially for use in motor vehicles, proton conductors which work at intermediate temperatures (373–673 K under an anhydrous atmosphere are desired to improve the fuel cell stability and efficiency. Inorganic–organic hybrid supramolecular architectures are a promising option for the realization of highly conductive proton conductors. Here, a hybrid layered crystal was synthesized for the first time by using an proton-containing decavanadate (V10 anion and a heterocyclic surfactant cation. A simple ion-exchange reaction led to the formation of an inorganic–organic hybrid of V10 by using dodecylpyridazinium (C12pda as the heterocyclic surfactant. Single crystal X-ray analyses revealed that four C12pda cations were associated with one V10 anion, which was a diprotonated species forming a one-dimensional infinite chain structure through hydrogen bonds. Anhydrous proton conductivity was investigated by alternating current (AC impedance spectroscopy in the range of 313–393 K, exhibiting a maximum value of 1.7 × 10−5 S cm−1 at 373 K.

  12. Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide gemini surfactants as novel corrosion inhibitors for mild steel in formic acid

    Directory of Open Access Journals (Sweden)

    Mohammad Mobin

    2012-12-01

    Full Text Available Gemini surfactants, butanediyl 1,4-bis(dimethyl cetylammonium bromide, pentanediyl 1,5 - bis (dimethyl cetylammonium bromide and hexanediyl 1,6 - bis (dimethyl cetylammonium bromide from Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide series were synthesized in laboratory and were characterized by using Nuclear Magnetic Resonance (NMR spectroscopy. The surfactants were tested as corrosion inhibitors for mild steel in 20% formic acid. The influence of surfactants on mild steel corrosion inhibition was investigated by measuring the corrosion rate of mild steel in their absence and presence by weight loss measurements, solvent analysis of iron ions into the test solution and potentiodynamic polarization measurements. The surface morphology of the corroded steel samples in presence and absence of surfactants was evaluated by using Scanning Electron Microscopy (SEM. The synthesized gemini surfactants performed as excellent corrosion inhibitor, the inhibition efficiency (IE being in the range of 76.66-97.41%. The IE of surfactants is slightly affected by the spacer length. The IE increased with increase in surfactant concentration and temperature. The adsorption of gemini surfactants on the steel surface was found to obey Langmuir adsorption isotherm. The results of the potentiodynamic polarization studies are consistent with the results of weight loss studies.

  13. Degradation of surfactants by sono-irradiation

    International Nuclear Information System (INIS)

    Ashokkumar, M.; Grieser, F.; Vinodgopal, K.

    2000-01-01

    Full text: The ultrasound induced decomposition of a commercially available polydisperse nonylphenol ethoxylate surfactant (Teric GN9) has been investigated. Nearly 90% mineralization and/or degradation into volatile products of the surfactant is achieved after sonication for 24 hours. Ultrasound has been found to be a useful tool to achieve a number of chemical processes. Linear and branched alkyl benzene sulfonates and alkyl nonylphenol ethoxylates are widely used surfactants which accumulated in the environment and contribute to a well-recognised pollution problem. We have investigated the use of ultrasound in the degradation of both types of surfactants with the aim of understanding the mechanism of degradation in order to optimise the decomposition process. In this presentation, we report on the sonochemical degradation of Teric GN9- polydisperse, a nonylphenol ethoxylate with an average of 9 ethylene oxide units. The ultrasound unit used for the degradation studies of the surfactant solutions was an Allied Signal (ELAC Nautik) RF generator and transducer with a plate diameter of 54.5 mm operated at 363 kHz in continuous wave mode at an intensity of 2 W/cm 2 . Ultrasound induced cavitation events generate primary radicals inside gas/vapour filled bubbles. Due to the extreme conditions (T ∼ 5000 K; P ∼ 100 atm) generated within the collapsing bubble, H and OH radicals are produced by the homolysis of water molecules, if water is the medium of sonication. These primary radicals attack the surfactant molecules adsorbed at the bubble/water interface. The initial rate of reaction of the surfactant was found to be dependent on the monomer concentration in solution below and above the critical micelle concentration of the surfactants. This result strongly suggests that the initial radical attack on the surfactants occurs at the cavitation bubble/solution interface, followed by oxidative decomposition and pyrolysis of volatile fragments of the surfactant within

  14. Surfactant nebulization versus instillation during high frequency ventilation in surfactant-deficient rabbits

    NARCIS (Netherlands)

    Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

    Surfactant nebulization improves lung function at low alveolar doses of surfactant. However, efficiency of nebulization is low, and lung deposition seems to depend on lung aeration. High frequency ventilation (HFV) has been shown to improve lung aeration. We hypothesize that the combination of HFV

  15. Open lung ventilation preserves the response to delayed surfactant treatment in surfactant-deficient newborn piglets

    NARCIS (Netherlands)

    van Veenendaal, Mariëtte B.; van Kaam, Anton H.; Haitsma, Jack J.; Lutter, René; Lachmann, Burkhard

    2006-01-01

    OBJECTIVE: Delayed surfactant treatment (>2 hrs after birth) is less effective than early treatment in conventionally ventilated preterm infants with respiratory distress syndrome. The objective of this study was to evaluate if this time-dependent efficacy of surfactant treatment is also present

  16. Unit and internal chain profiles of maca amylopectin.

    Science.gov (United States)

    Zhang, Ling; Li, Guantian; Yao, Weirong; Zhu, Fan

    2018-03-01

    Unit chain length distributions of amylopectin and its φ, β-limit dextrins, which reflect amylopectin internal structure from three maca starches, were determined by high-performance anion-exchange chromatography with pulsed amperometric detection after debranching, and the samples were compared with maize starch. The amylopectins exhibited average chain lengths ranging from 16.72 to 17.16, with ranges of total internal chain length, external chain length, and internal chain length of the maca amylopectins at 12.49 to 13.68, 11.24 to 11.89, and 4.27 to 4.48. The average chain length, external chain length, internal chain length, and total internal chain length were comparable in three maca amylopectins. Amylopectins of the three maca genotypes studied here presented no significant differences in their unit chain length profiles, but did show significant differences in their internal chain profiles. Additional genetic variations between different maca genotypes need to be studied to provide unit- and internal chain profiles of maca amylopectin. Copyright © 2017. Published by Elsevier Ltd.

  17. Ordered silica particles made by nonionic surfactant for VOCs sorption

    Energy Technology Data Exchange (ETDEWEB)

    Difallah, Oumaima; Hamaizi, Hadj, E-mail: hamaizimizou@yahoo.fr [University of Oran, OranMenaouer (Algeria); Amate, Maria Dolores Urena; Socias-Viciana, Maria Del Mar [University of Almeria (Spain)

    2017-07-15

    Adsorption of light organic compounds such acetone, 1-propanol and carbon dioxide was tested by using mesoporous silica materials made from non ionic surfactant with long chain and silica sources as tetraethyl orthosilicate TEOS and modified Na-X and Li-A Zeolites. X-ray powder diffraction (XRD), nitrogen adsorption-desorption analysis and scanning electron microscopy (SEM) were applied to characterize the silica particles of a variety prepared samples. Acetone, 1-propanol and CO{sub 2} adsorption at 298K was evaluated by a volumetric method and indicate a high sorption capacity of organic compounds depending essentially on the porous texture of adsorbents. An adsorption kinetic model was proposed to describe the adsorption of VOCs over template-free mesoporous silica materials. A good agreement with experimental data was found. (author)

  18. Dilute Surfactant Methods for Carbonate Formations

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2006-02-01

    There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

  19. Chain networking revealed by molecular dynamics simulation

    Science.gov (United States)

    Zheng, Yexin; Tsige, Mesfin; Wang, Shi-Qing

    Based on Kremer-Grest model for entangled polymer melts, we demonstrate how the response of a polymer glass depends critically on the chain length. After quenching two melts of very different chain lengths (350 beads per chain and 30 beads per chain) into deeply glassy states, we subject them to uniaxial extension. Our MD simulations show that the glass of long chains undergoes stable necking after yielding whereas the system of short chains is unable to neck and breaks up after strain localization. During ductile extension of the polymer glass made of long chain significant chain tension builds up in the load-bearing strands (LBSs). Further analysis is expected to reveal evidence of activation of the primary structure during post-yield extension. These results lend support to the recent molecular model 1 and are the simulations to demonstrate the role of chain networking. This work is supported, in part, by a NSF Grant (DMR-EAGER-1444859)

  20. Degradation of Triton X-100 surfactant/lipid regulator systems by ionizing radiation in water

    International Nuclear Information System (INIS)

    Racz, Gergely; Obuda-University, Budapest; Csay, Tamas; Takacs, Erzsebet; Wojnarovits, Laszlo

    2017-01-01

    The radiolytic degradation of Triton X-100 surfactant was investigated at concentrations below and above the critical micelle concentration (CMC, ∼ 0.23 mmol dm -3 ) in air saturated aqueous solutions. At low concentrations the degradation took place both on the aromatic head and on the polyethoxylates chain, while above CMC it was shifted towards the chain. The CMC was higher in irradiated solutions at 10 Gy by a factor of 2, at 20 kGy by a factor of 3 than in the un-irradiated solution. The degradation of clofibric acid in the presence of TX-100 was more effective outside the micelles than inside them. (author)

  1. The Effect Of Organic Surfactants On The Properties Of Common Hygroscopic Particles: Effective Densities, Reactivity And Water Evaporation Of Surfactant Coated Particles

    Science.gov (United States)

    Cuadrarodriguez, L.; Zelenyuk, A.; Imre, D.; Ellison, B.

    2006-12-01

    Measurements of atmospheric aerosol compositions routinely show that organic compounds account for a very large fraction of the particle mass. The organic compounds that make up this aerosol mass represent a wide range of molecules with a variety of properties. Many of the particles are composed of hygroscopic salts like sulfates, nitrates and sea-salt internally mixed with organics. While the properties of the hygroscopic salts are known, the effect of the organic compounds on the microphysical and chemical properties which include CCN activity is not clear. .One particularly interesting class of internally mixed particles is composed of aqueous salts solutions that are coated with organic surfactants which are molecules with long aliphatic chain and a water soluble end. Because these molecules tend to coat the particles' surfaces, a monolayer might be sufficient to drastically alter their hygroscopic properties, their CCN activity, and reactivity. The aliphatic chains, being exposed to the oxidizing atmosphere are expected to be transformed through heterogeneous chemistry, yielding complex products with mixed properties. We will report the results from a series of observations on ammonium sulfate, sodium chloride and sea salt particles coated with three types of surfactant molecules: sodium lauryl sulfate, sodium oleate and laurtrimonium chloride. We have been able to measure the effective densities of internally mixed particles with a range of surfactant concentration that start below a monolayer and extend all the way to particles composed of pure surfactant. For many of the measurements the data reveal a rather complex picture that cannot be simply interpreted in terms of the known pure-compound densities. For unsaturated hydrocarbons we observed and quantified the effect of oxidation by ozone on particle size, effective density and individual particle mass spectral signatures. One of the more important properties of these surfactants is that they can form a

  2. Remote control of soft nano-objects by light using azobenzene containing surfactants

    Science.gov (United States)

    Santer, Svetlana

    2018-01-01

    We review recent progress in the field of light responsive soft nano-objects. These are systems the shape, size, surface area and surface energy of which can be easily changed by low-intensity external irradiation. Here we shall specifically focus on microgels, DNA molecules, polymer brushes and colloidal particles. One convenient way to render these objects photosensitive is to couple them via ionic and/or hydrophobic interactions with azobenzene containing surfactants in a non-covalent way. The advantage of this strategy is that these surfactants can make any type of charged object light responsive without the need for possibly complicated (and irreversible) chemical conjugation. In the following, we will exclusively discuss only photosensitive surfactant systems. These contain a charged head and a hydrophobic tail into which an azobenzene group is incorporated, which can undergo reversible photo-isomerization from a trans- to a cis-configuration under UV illumination. These kinds of photo-isomerizations occur on a picosecond timescale and are fully reversible. The two isomers in general possess different polarity, i.e. the trans-state is less polar with a dipole moment of usually close to 0 Debye, while the cis-isomer has a dipole moment up to 3 Debye or more, depending on additional phenyl ring substituents. As part of the hydrophobic tail of a surfactant molecule, the photo-isomerization also changes the hydrophobicity of the molecule as a whole and hence its solubility, surface energy, and strength of interaction with other substances. Being a molecular actuator, which converts optical energy in to mechanical work, the azobenzene group in the shape of surfactant molecule can be utilized in order to actuate matter on larger time and length scale. In this paper we show several interesting examples, where azobenzene containing surfactants play the role of a transducer mediating between different states of size, shape, surface energy and spatial arrangement of

  3. Partial nucleotide sequences, and routine typing by polymerase chain reaction-restriction fragment length polymorphism, of the brown trout (Salmo trutta) lactate dehydrogenase, LDH-C1*90 and *100 alleles.

    Science.gov (United States)

    McMeel, O M; Hoey, E M; Ferguson, A

    2001-01-01

    The cDNA nucleotide sequences of the lactate dehydrogenase alleles LDH-C1*90 and *100 of brown trout (Salmo trutta) were found to differ at position 308 where an A is present in the *100 allele but a G is present in the *90 allele. This base substitution results in an amino acid change from aspartic acid at position 82 in the LDH-C1 100 allozyme to a glycine in the 90 allozyme. Since aspartic acid has a net negative charge whilst glycine is uncharged, this is consistent with the electrophoretic observation that the LDH-C1 100 allozyme has a more anodal mobility relative to the LDH-C1 90 allozyme. Based on alignment of the cDNA sequence with the mouse genomic sequence, a local primer set was designed, incorporating the variable position, and was found to give very good amplification with brown trout genomic DNA. Sequencing of this fragment confirmed the difference in both homozygous and heterozygous individuals. Digestion of the polymerase chain reaction products with BslI, a restriction enzyme specific for the site difference, gave one, two and three fragments for the two homozygotes and the heterozygote, respectively, following electrophoretic separation. This provides a DNA-based means of routine screening of the highly informative LDH-C1* polymorphism in brown trout population genetic studies. Primer sets presented could be used to sequence cDNA of other LDH* genes of brown trout and other species.

  4. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    Directory of Open Access Journals (Sweden)

    M. Ammann

    2008-09-01

    Full Text Available Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3, an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g. The uptake coefficient was reduced by a factor of 5–50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15, which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12 and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  5. History of surfactant up to 1980.

    Science.gov (United States)

    Obladen, Michael

    2005-01-01

    Remarkable insight into disturbed lung mechanics of preterm infants was gained in the 18th and 19th century by the founders of obstetrics and neonatology who not only observed respiratory failure but also designed devices to treat it. Surfactant research followed a splendid and largely logical growth curve. Pathological changes in the immature lung were characterized in Germany by Virchow in 1854 and by Hochheim in 1903. The Swiss physiologist von Neergard fully understood surfactant function in 1929, but his paper was ignored for 25 years. The physical properties of surfactant were recognized in the early 1950s from research on warfare chemicals by Pattle in Britain and by Radford and Clements in the United States. The causal relationship of respiratory distress syndrome (RDS) and surfactant deficiency was established in the USA by Avery and Mead in 1959. The Australian obstetrician Liggins induced lung maturity with glucocorticoids in 1972, but his discovery was not fully believed for another 20 years. A century of basic research was rewarded when Fujiwara introduced surfactant substitution in Japan in 1980 for treatment and prevention of RDS. Copyright 2005 S. Karger AG, Basel

  6. Poly(ethylene oxide) surfactant polymers.

    Science.gov (United States)

    Vacheethasanee, Katanchalee; Wang, Shuwu; Qiu, Yongxing; Marchant, Roger E

    2004-01-01

    We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly(ethylene oxide) (PEO) were simultaneously attached to PVAm via reductive amination. Surfactant polymers with different PEO:hexanal ratios and hydrophilic/hydrophobic balances were prepared, and characterized by FT-IR, 1H-NMR and XPS spectroscopies. Surface active properties at the air/water interface were determined by surface tension measurements. Surface activity at a solid surface/water interface was demonstrated by atomic force microscopy, showing epitaxially molecular alignment for surfactant polymers adsorbed on highly oriented pyrolytic graphite. The surfactant polymers described in this report can be adapted for simple non-covalent surface modification of biomaterials and hydrophobic surfaces to provide highly hydrated interfaces.

  7. Surfactant use with nitrate-based bioremediation

    International Nuclear Information System (INIS)

    Wilson, B.H.; Hutchins, S.R.; West, C.C.

    1995-01-01

    This study presents results of an initial survey on the effect of six surfactants on the biodegradation of petroleum hydrocarbons in bioremediation applications using nitrate as the electron acceptor. Aquifer material from Park City, Kansas, was used for the study. The three atomic surfactants chosen were Steol CS-330, Dowfax 8390 and sodium dodecylbenzene sulfonate (SDBS); the three nonionic surfactants were T-MAZ-60, Triton X-100, and Igepal CO-660. Both Steol CS-330 and T-MAZ-60 biodegraded under denitrifying conditions. The Steol inhibited biodegradation of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEXTMB). Only toluene was rapidly degraded in the presence of T-MAZ-60. Biodegradation of all compounds, including toluene, appears to be inhibited by Dowfax 8390 and SDBS. No biodegradation of Dowfax 8390 or SDBS was observed. SDBS inhibited denitrification, but Dowfax 8390 did not. For the microcosms containing Triton X-100 or Igepal CO-660, removal of toluene, ethylbenzene, m-xylene, 1,3,5-TMB, and 1,2,4-TMB were similar to their removals in the no-surfactant treatment. These two surfactants did not biodegrade, did not inhibit biodegradation of the alkylbenzenes, and did not inhibit denitrification. Further studies are continuing with aquifer material from Eglin Air Force Base

  8. Recovering hydrocarbons with surfactants from lignin

    Energy Technology Data Exchange (ETDEWEB)

    Naae, D.G.; Whittington, L.E.; Ledoux, W.A.; Debons, F.E.

    1988-11-29

    This patent describes a method of recovering hydrocarbons from an underground hydrocarbon formation penetrated by at least one injection well and at least one production well, which comprises: injecting into the formation through an injection well a surfactant slug comprising about 0.1% to about 10% by weight of surfactants produced from lignin, the surfactants produced by placing lignin in contact with water, converting the lignin into low molecular weight lignin phenols by reducing the lignin in the presence of a reducing agent of carbon monoxide or hydrogen creating a reduction reaction mixture comprising oil soluble lignin phenols, the reduction occurring at a temperature greater than about 200/sup 0/C and a pressure greater than about 100 psi, recovering the oil soluble lignin phenols from the reduction mixture, and converting the lignin phenols into lignin surfactants by a reaction selected from the group consisting of alkoxylation, sulfonation, sulfation, aklylation, sulfomethylation, and alkoxysulfation; injecting into the formation through the injection well a drive fluid to push the surfactant slug towards a production well; and recovering hydrocarbons at the production well.

  9. Foaming behaviour of polymer-surfactant solutions

    International Nuclear Information System (INIS)

    Cervantes-MartInez, Alfredo; Maldonado, Amir

    2007-01-01

    We study the effect of a non-ionic amphiphilic polymer (PEG-100 stearate also called Myrj 59) on the foaming behaviour of aqueous solutions of an anionic surfactant (sodium dodecyl sulfate or SDS). The SDS concentration was kept fixed while the Myrj 59 concentration was varied. Measurements of foamability, surface tension and electrical conductivity were carried out. The results show two opposite effects depending on the polymer concentration: foamability is higher when the Myrj 59 concentration is low; however, it decreases considerably when the polymer concentration is increased. This behaviour is due to the polymer adsorption at the air/liquid interface at lower polymer concentrations, and to the formation of a polymer-surfactant complex in the bulk at higher concentrations. The results are confirmed by surface tension and electrical conductivity measurements, which are interpreted in terms of the microstructure of the polymer-surfactant solutions. The observed behaviour is due to the amphiphilic nature of the studied polymer. The increased hydrophobicity of Myrj 59, compared to that of water-soluble polymers like PEG or PEO, increases its 'reactivity' towards SDS, i.e. the strength of its interaction with this anionic surfactant. Our results show that hydrophobically modified polymers have potential applications as additives in order to control the foaming properties of surfactant solutions

  10. Rational Design and Synthesis of Carboxylate Gemini Surfactants with an Excellent Aggregate Behavior for Nano-La2O3 Morphology-Controllable Preparation.

    Science.gov (United States)

    Liao, Xueming; Gao, Zhinong; Xia, Yan; Niu, Fei; Zhai, Wenzhong

    2017-04-04

    A series of carboxylate gemini surfactants (CGS, C n -Φ-C n , n = 12, 14, 16, 18) with diphenyl ketone as a spacer group were prepared using a simple and feasible synthetic method. These CGS exhibited an excellent surface activity with extremely low critical micelle concentration (CMC) value (approximately 10 -5 mol/L), good performance in reducing surface tension (nearly 30 mN/m), and the ability of molecular self-assembly into different aggregate morphologies via adjusting the concentrations, which is attributed to the introduction of diphenyl ketone and carboxylic acid ammonium salt in the molecular structure. Moreover, the surface activity and self-assembly ability of CGS were further optimized by tuning the length of the tail chain. These excellent properties imply that CGS can be a soft template to prepare nanomaterials, especially in morphology-controllable synthesis. By adjusting the concentration of one of CGS (C 12 -Φ-C 12 ), nano-La 2 O 3 particles with diverse morphologies were obtained, including spherical shape, bead-chain shape, rod shape, velvet-antler shape, cedar shape, and bowknot shape. This work offers a vital insight into the rational design of template agents for the development of morphology-controllable nanomaterials.

  11. Enhanced Oil Recovery with Surfactant Flooding

    DEFF Research Database (Denmark)

    Sandersen, Sara Bülow

    , thus reducing the interfacial tension (IFT) to ultra low (0.001 mN/m), which consequently will mobilize the residual oil and result in improved oil recovery. This EOR technology is, however, made challenging by a number of factors, such as the adsorption of surfactant and co-surfactant to the rock...... be resistant to and remain active at reservoir conditions such as high temperatures, pressures and salinities. Understanding the underlying mechanisms of systems that exhibit liquid-liquid equilibrium (e.g. oil-brine systems) at reservoir conditions is an area of increasing interest within EOR. This is true...... studied. The effect of increased pressure became more significant when combined with increasing temperature. The experiments performed on the oil/ seawater systems were similar to the high pressure experiments for the surfactant system discussed above. Oil was contacted with different brine solutions...

  12. Surfactant mediated liquid phase exfoliation of graphene

    Science.gov (United States)

    Narayan, Rekha; Kim, Sang Ouk

    2015-10-01

    Commercialization of graphene based applications inevitably requires cost effective mass production. From the early days of research on graphene, direct liquid phase exfoliation (LPE) of graphite has been considered as the most promising strategy to produce high-quality mono or few-layer graphene sheets in solvent dispersion forms. Substantial success has been achieved thus far in the LPE of graphene employing numerous solvent systems and suitable surfactants. This invited review article principally showcase the recent research progress as well as shortcomings of surfactant assisted LPE of graphene. In particular, a comprehensive assessment of the quality and yield of the graphene sheets produced by different categories of the surfactants are summarized. Future direction of LPE methods is also proposed for the eventual success of commercial applications.

  13. Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

    Science.gov (United States)

    Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

  14. Early surfactant therapy and nasal continuous positive airways ...

    African Journals Online (AJOL)

    respiratory distress syndrome (RDS) receiving nasal continuous positive airways ... required FiO2 was allowed to rise above 0.4 before surfactant was administered. ... group received surfactant immediately and the high-threshold group ...

  15. The influence of nonionic surfactant Brij 30 on biodegradation of ...

    African Journals Online (AJOL)

    ONOS

    2010-09-06

    Sep 6, 2010 ... polluted air stream using biological process is highly efficient and has low ... Brij 30 was the most biodegradable surfactant among Brij 30, Tween 80 and ... The filter material contained surfactants that would enhance the ...

  16. Fullerene surfactants and their use in polymer solar cells

    Science.gov (United States)

    Jen, Kwan-Yue; Yip, Hin-Lap; Li, Chang-Zhi

    2015-12-15

    Fullerene surfactant compounds useful as interfacial layer in polymer solar cells to enhance solar cell efficiency. Polymer solar cell including a fullerene surfactant-containing interfacial layer intermediate cathode and active layer.

  17. Surfactant therapy in late preterm infants

    Directory of Open Access Journals (Sweden)

    Murat Yurdakök

    2013-06-01

    Full Text Available Late preterm (LPT neonates are at a high risk for respiratory distress soon after birth due to respiratory distress syndrome (RDS, transient tachypnea of the newborn, persistent pulmonary hypertension, and pneumonia along with an increased need for surfactant replacement therapy, continuous positive airway pressure, and ventilator support when compared with the term neonates. In the past, studies on outcomes of infants with respiratory distress have primarily focused on extremely premature infants, leading to a gap in knowledge and understanding of the developmental biology and mechanism of pulmonary diseases in LPT neonates. Surfactant deficiency is the most frequent etiology of RDS in very preterm and moderately preterm infants, while cesarean section and lung infection play major roles in RDS development in LPT infants. The clinical presentation and the response to surfactant therapy in LPT infants may be different than that seen in very preterm infants. Incidence of pneumonia and occurrence of pneumothorax are significantly higher in LPT and term infants. High rates of pneumonia in these infants may result in direct injury to the type II alveolar cells of the lung with decreasing synthesis, release, and processing of surfactant. Increased permeability of the alveolar capillary membrane to both fluid and solutes is known to result in entry of plasma proteins into the alveolar hypophase, further inhibiting the surface properties of surfactant. However, the oxygenation index value do not change dramatically after ventilation or surfactant administration in LPT infants with RDS compared to very preterm infants. These finding may indicate a different pathogenesis of RDS in late preterm and term infants. In conclusion, surfactant therapy may be of significant benefit in LPT infants with serious respiratory failure secondary to a number of insults. However, optimal timing and dose of administration are not so clear in this group. Additional

  18. Surfactant-Polymer Interaction for Improved Oil Recovery; FINAL

    International Nuclear Information System (INIS)

    Gabitto, Jorge; Mohanty, Kishore K.

    2002-01-01

    The goal of this research was to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, oil solubility in the displacing fluid and mobility control. Surfactant-polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation and viscous/heterogeneity fingering

  19. The Effects of Alkyl Chain Combinations on the Structural and Mechanical Properties of Biomimetic Ion Pair Amphiphile Bilayers

    Directory of Open Access Journals (Sweden)

    Cheng-hao Chen

    2017-10-01

    Full Text Available Ion pair amphiphile (IPA, a lipid-like complex composed of a pair of cationic and anionic surfactants, has great potentials in various pharmaceutical applications. In this work, we utilized molecular dynamics (MD simulation to systematically examine the structural and mechanical properties of the biomimetic bilayers consist of alkyltrimethyl-ammonium-alkylsulfate (CmTMA+-CnS− IPAs with various alkyl chain combinations. Our simulations show an intrinsic one-atom offset for the CmTMA+ and CnS− alignment, leading to the asymmetric index definition of ΔC = m − (n + 1. Larger |ΔC| gives rise to higher conformational fluctuations of the alkyl chains with the reduced packing order and mechanical strength. In contrast, increasing the IPA chain length enhances the van der Waals interactions within the bilayer and thus improves the bilayer packing order and mechanical properties. Further elongating the CmTMA+-CnS− alkyl chains to m and n ≥ 12 causes the liquid disorder to gel phase transition of the bilayer at 298 K, with the threshold membrane properties of 0.45 nm2 molecular area, deuterium order parameter value of 0.31, and effective bending rigidity of 20 kBT, etc. The combined results provide molecular insights into the design of biomimetic IPA bilayers with wide structural and mechanical characteristics for various applications.

  20. Surfactant-assisted sol–gel synthesis of forsterite nanoparticles as a novel drug delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Hassanzadeh-Tabrizi, S.A., E-mail: tabrizi1980@gmail.com [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Bigham, Ashkan [Advanced Materials Research Center, Materials Engineering Department, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Rafienia, Mohammad [Biosensor Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of)

    2016-01-01

    In the present study, forsterite nanoparticles were synthesized via surfactant-assisted sol–gel method using cetyltrimethyl ammonium bromide (CTAB) as a surfactant. The effects of CTAB contents and heat treatment on the textural properties and drug release from nanoparticles were investigated. The synthesized powders were studied by X-ray diffraction, Fourier transform infrared spectra, Brunauer–Emmett–Teller surface area analysis and transmission electron microscope images. Mg{sub 2}SiO{sub 4} materials demonstrated mesoporous characteristics and large specific surface area ranging from 159 to 30 m{sup 2}/g. The TEM results showed that forsterite nanorods had diameters about 4 nm and lengths ranging from 10 to 60 nm. It was found that the samples with 6 g CTAB show slower drug release rate than the other specimens, which is due to smaller pore size. This study revealed that the drug delivery of forsterite can be tailored by changing the amount of surfactant. - Highlights: • Forsterite nanoparticles were synthesized via surfactant-assisted sol–gel method. • Nanoparticles were loaded with ibuprofen as a novel drug delivery system. • Synthesized nanoparticles had a rod-like morphology. • CTAB concentration strongly affected the textural properties and drug release of the nanoparticles.

  1. Interactions between fluorinated cationic guar gum and surfactants in the dilute and semi-dilute solutions.

    Science.gov (United States)

    Wang, Chen; Li, Xiaorui; Li, Peizhi; Niu, Yuhua

    2014-01-01

    The interactions between the fluorinated cationic guar gum (FCGG) and ionic surfactants including cetyl trimethyl ammonium bromide (CTAB) and sodium lauryl sulfate (SDS) were studied by light scattering